RU2837197C2 - Heat treatment process and system with increased output of pitch - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing pitch from a starting material, where the starting material contains one of the following materials: (i) decantate from petroleum products, (ii) heavy coal tar distillate. Method comprises feeding said starting material in a fluid liquid phase into a heat-conducting part of a channel at least partially made from a heat-conducting material which promotes heat transfer; controlled supply of heat to said heat-conducting part of said channel containing initial material to increase temperature of initial material to 459–535 °C at pressure of at least 46 pounds per sq in. (g), so as to maintain said starting material in liquid phase; maintaining a substantially uniform flow of said initial material through at least a portion of said heat-conducting part of said channel at a substantially constant temperature for a period of time sufficient to convert part of said starting material into pitch while limiting formation of mesophase to 0.7 wt. % in a combined stream; reduction of temperature of said combined flow to 275–385 °C, separation of said pitch from said combined flow and obtaining finished pitch. Invention also relates to a continuous method of producing pitch, finished pitch, a heat treatment subsystem for producing pitch and a distillation system for producing pitch.

EFFECT: optimization of pitch yield, reduction of insoluble quinoline content and creation of mesophase in pitch.

41 cl, 14 dwg, 14 tbl, 4 ex

Description

STATEMENT OF PRIORITY

This application claims priority to pending U.S. application Ser. No. 16/520,135, filed July 23, 2019, the contents of which are incorporated herein by reference in their entirety.

DISADVANTAGES OF EXISTING SOLUTIONS

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

The present invention relates to improvements in the production of pitch from hydrocarbon feedstock. In particular, the invention relates to the thermal treatment of by-products of the distillation of coal tar and petroleum products in order to optimize the yield of pitch, reduce the content of insoluble quinoline and create a mesophase in the pitch.

KNOWN TECHNICAL SOLUTIONS

Coal is a vital raw material for the production of a number of useful products on which the modern world depends. In particular, bituminous coal mined from the earth is heated in a furnace called a coke oven, and through the destructive distillation or carbonization of the coal, coke and coal tar are formed. Coke is widely used as a fuel and a source of chemical reagents in the steel industry. Coal tar is a dark liquid released from coal during the coking process. It is used in waterproofing materials used in road construction, in the production of asphalt, in waterproofing roofs, and for impregnating wood and other building materials. Coal tar is a complex mixture of approximately 10,000 predominantly aromatic and semi-aromatic compounds that typically boil at temperatures from 50 to over 550 °C, including, but not limited to, benzene, toluene, xylene, indene, phenol, naphthalene, benzothiophene, quinoline, methylnaphthalene, enephthene, fluorene, phenanthrene, anthracene, carbazole, fluoranthene, pyrene, tetracene, triphenylene, chrysene, benzo(a)pyrene, coronene, and benzo(ghi)perylene. Coal tar can therefore be distilled into a variety of fractions by separating and collecting the individual components, each of which is valuable in its own right. A significant portion of distilled coal tar is a residue in the form of coal tar pitch. This substance is used in the production of anodes for aluminum smelting, as well as electrodes for electric arc furnaces used in the steel industry. One of the most important quality characteristics of coal tar pitch is its suitability for use as a binder in the manufacture of anodes and electrodes. Parameters such as softening point, specific gravity, proportion of insoluble quinoline, and coke number describe the suitability of coal tar pitch for use in various production processes and industries.

In addition, pitch is obtained not only from coal but also from oil. In this case, the raw materials are the products of catalytic cracking of oil, such as decantate or ethylene cracking bottoms (ECB). Decantate is formed as a result of catalytic cracking and distillation of oil at oil refineries. Decantate is stable during storage and has a high boiling point. It contains aromatic and heterocyclic compounds. ECB is less thermally stable than decantate and its distillation products. It can explode during storage and therefore finds less application. The processes of producing pitch from coal tar or oil products are similar. Moreover, they use the same equipment, but in different operating modes. However, the systems for producing pitch from oil products and coal tar may differ from each other. Such properties of oil pitch as softening point, proportion of insoluble quinoline (QI) or coke number differ from the properties of coal tar pitch. The production of mixtures of petroleum and coal tar pitch in a certain proportion helps to solve the problems of raw material shortage and high cost. In addition, mixing helps to achieve the desired characteristics of the final product.

There are many methods for producing coal tar or petroleum pitch. For example, one embodiment of such a process is shown in Fig. 1A. In a known distillation process, water-containing petroleum products 1 are used as feedstock. The feedstock is coal tar or petroleum refining products, such as decantation or KOEK. The feedstock 1 is fed to the first column C1 through a line 10, which is a pipe or trough. The line 10 has a small diameter compared to the internal volume of the first column C1. Therefore, the feedstock 1 is fed to the line 10 with increased pressure. When the feedstock 1 passes through the diaphragm 11 and enters the first column C1, it experiences a sharp pressure drop. As a result, the feedstock is separated into components with different boiling points. The first column C1 is a dehydrator, in which the contents are heated to a predetermined temperature in order to remove light fractions. In an alternative design, the line 10 passes through one or more heat exchangers in order to increase the temperature of the feedstock before it enters the column C1. The first column C1 serves mainly to remove water, so that at the bottom of the column "dried fuel oil" or "dehydrated crude" (depending on the composition of the feedstock) is formed. The water content of this substance does not exceed a specified level. For example, heaters such as steam heaters are used to heat the first column C1 to a temperature of ~160 °C in order to separate the distillate 12,. Which includes water vapor and light molecules with a relatively low boiling point - such as water and light fractions of oil, also called BTX (benzene, toluene, xylene). Distillates 12 rise to the top of the first column C1 and are removed through the steam line 13. The remaining heavier molecules, including polyaromatic hydrocarbons (PAH), fall to the bottom of the column. Bottom residue is the fraction of distillate with heavier components that sinks to the bottom of the distillation column due to its greater mass and higher boiling point. Bottom residue in column C1 contains PAHs and other heavier molecules. It is often called dehydrated fuel oil 14.

The dehydrated fuel oil 14 from the bottoms of the column C1 is fed to the second column C2 via line 15 for further distillation. Accordingly, the dehydrated fuel oil from the first column C1 is the feedstock for the second column C2. The second column C2 is a fractionating column for multi-stage distillation. The multi-stage distillation column ensures optimal fractionation efficiency and purity of the valuable chemicals formed. The column contains several trays 20, which cover at least part of the diameter of the column. Distillation condensate is formed on the trays, which facilitates irrigation and further fractionation of the feedstock components. The column can also contain bulk or structured packing 21, through which evaporated molecules pass, which facilitates fractionation. Regardless of the design, boiling steam rises up the column, and the liquid flows down under the action of gravity. At any stage, the steam coming from below is hotter than the liquid flowing down. As a result of counter-current contact, heat is transferred from the steam to the liquid. In this case, the low-boiling light components of the liquid evaporate and the heavier components of the steam condense. It is the evaporation of light fractions and condensation of heavy ones at successive stages that leads to the functioning and purification of the raw material components.

Distillation in the second column C2 is usually carried out by heating it to a bottom temperature of 250-270 °C and even to 360 °C with a heater at atmospheric pressure. In this stage, light distillates 22 are removed, including naphthalene, which is sold as such or used in the production of dyes and plastics, and is also processed into naphthalene refined oil (NRN), which is distilled at a temperature of 210-315 °C. Light distillates 22 are withdrawn from the second column C2 through a steam line 23. A part of the light distillate 22 can be returned to the second column C2 for reflux for the purpose of repeated distillation and fractionation. The bottoms obtained in the C2 column are usually called stripped crude or stripped fuel oil 25. Depending on the composition of the feedstock, it contains high-molecular aromatic hydrocarbons (such as PAHs) containing medium and heavy distillates.

The stripped crude oil or fuel oil 25 from the bottoms of column C2 is fed to the third column C3 via line 26. Various fuel oils and pitches can be additionally introduced into line 26, including stripped fuel oil, medium or soft pitch 27 with a softening point of 40-125 °C, preferably ~90 °C (this temperature strongly depends on the final softening point of the finished pitch). They are mixed with the stripped crude oil or fuel oil 25 and become additional feedstock for the third column C3. Such an addition increases the volume of the feedstock or changes its characteristics. In the third distillation column C3, which contains packing 21 and/or trays, the contents are heated by a heater to a temperature above 315 °C. Caution must be exercised at this stage, since mesophase begins to form at a temperature of ~390 °C. Mesophase is a precursor to coke that will form in the resulting asphalt pitch as solid particles. It is important to note that the term "mesophase" as used herein refers only to detectable mesophase with a particle size greater than 4 μm. "Incipient" mesophase with a particle size of up to and including 4 μm is not considered mesophase in this document. Coke formation in the pitch is to be avoided in this process because it hinders the use of the pitch in the manufacture of anodes for the aluminum industry and electrodes for steel production. In addition, the ability of the pitch to reliably wet the coke during the mixing step in the manufacture of carbon articles such as anodes or electrodes is limited, which reduces the electrical conductivity of the article. Therefore, a vacuum is applied in the third column C3 to reduce the boiling point at which the components are fractionated and distilled.

In the third column C3, various distillates may be obtained, each of which is a mixture of different components. For example, the first middle distillate 35 is distilled first and can be withdrawn from the third column C3 through line 36. The first middle distillate 35 is a mixture of different carbon molecules, for example, having at least 12 carbon atoms and, therefore, having a high molecular weight. They are called carbon black feedstock ("CBF") and are used in the production of raw materials for rubber. A portion of the first middle distillate 35 can be returned to the third column C3 for reflux and refractionation.

The second middle distillate 38 may be removed from the third column C3 via the distillate withdrawal line 39. The second middle distillate 38 may contain compounds used in the production of creosote wood preservatives, which may be separated from the remainder of the distillate for further processing and use in other applications - for example, for impregnating railroad ties, telephone poles and in other wood preservative applications. A portion of the second middle distillate 38 may be returned to the third column C3 for reflux and refractionation.

Heavy distillate 41 contains even higher molecular weight components. It is withdrawn from the third column C3 via the steam line 42. Heavy distillate 41 is a by-product containing soot feedstock. A portion of heavy distillate 41 can be returned to the third column C3 for reflux and refractionation.

The bottom residue in the third column C3 is coal tar pitch 50. Pitch 50 is a thick black liquid that contains a mixture of substances including PAH. This is the final product of the pitch production system described above. Pitch is discharged from the third column C3 through the outlet line 51 and transferred to consumers. Pitch 50 is characterized by various properties, including softening point, specific gravity, proportion of insoluble quinoline and coke number. The properties determine the quality of the pitch and its applicability in various production processes and industries. The distillation process is controlled by selecting different fractions of distillates at different times and/or in different volumes, which allows selectively changing the characteristics of the finished product 50. For example, coal tar pitch 50 with a softening point (as determined on the Mettler apparatus) of 108-140 °C and a quinoline content of no more than 10-20% is used as a binder in the production of anodes and electrodes. Coal tar pitch used for impregnation should have an even lower content of insoluble quinoline.

In the second embodiment of the resin production method shown in Fig. 1B, wet feedstock 1 is fed through a diaphragm 11 into the first column C1 for dehydration. Light fractions of oil and water are removed in the form of a distillate 12, and dehydrated fuel oil 14 is fed into the second column C2 via line 15.

The second column C2 is a multi-stage fractionating unit, as in the other known process, and is heated by a heater to a temperature of ~250-270 °C at atmospheric pressure. However, in this embodiment, the light distillate 22 is distilled and removed through the steam line 23, and the middle distillate 38 is distilled and removed from the second column C2 through the distillate line 39. The light distillate 22 contains naphthalene refined oil (NRN) and other light distilled petroleum fractions. The middle distillate 38 contains creosote, which can be separated and purified. The light and middle distillates 22, 38 can be mixed and stored together or subsequently processed for the purpose of producing purified creosote.

In this embodiment, the stripped oil or fuel oil 25 in the bottoms C2 is then fed to the fourth (for this embodiment, the third) column C4 via a line 26' from column C2 to column C4, and then fed (under normal or increased pressure) to the fourth column C4 through a diaphragm 11, which can be equipped with a sprayer. During such distillation, the heavy distillate 41 (heavy oil) is separated from the residue, which allows the heavy distillate 41 to be removed from the fourth column C4 via a steam line 42. The components of the heavy distillate 41 can subsequently be fractionated by further distillation or processing to obtain soot and other aromatic compounds. The bottoms in the fourth column C4 are pitch 50. This is either coal tar pitch if the feedstock is coal tar, or petroleum pitch if the feedstock is decantation.

In a third embodiment of the pitch production, as shown in Fig. 1C, four columns are used that perform distillation and/or separation of oil products from the bottoms during the production of pitch. In particular, wet oil feedstock 1 is first dehydrated in the first column C1 in order to remove distillates 12, including water and light oil fractions. Then, the dehydrated fuel oil 14 is distilled in the second fractionating column C2 in order to obtain a light distillate 22. The resulting stripped oil or fuel oil 25 is then fed to the third fractionating column C3, where the middle distillate 38 is removed. In this embodiment, the bottoms from the third column C3 are fed to the fourth evaporating column C4, where, due to a sharp pressure drop, the heavy distillate 41 is separated. Only the useful product remains - pitch 50.

The above known pitch production processes are capable of providing, depending on the process parameters, a pitch yield of 15-60% of the raw material (either coal tar or decantate). Optimization of processes and increase in yield are important, but their effectiveness is difficult to determine, and even more difficult to successfully implement on an industrial scale for commercial production.

One way to increase yield involves heat treatment (also called thermal processing or thermal soaking) of distillates and by-products used as raw materials in pitch production. Thermal treatment has three main parameters: temperature, pressure, and soaking time.

Many attempts have been made to find ways to increase pitch yield (and other properties) by heat treatment. The results have varied widely, and the number of commercially successful industrial projects is very small. The cited patents fully disclose the time and temperature regimes, but with little understanding of the mechanics of the process that lead to the increased yield, and little disclosure of the actual combinations of time and temperature that produce specific yield figures.

U.S. Patent No. 3,140,248 discloses the preparation of a pitch binder with an impregnation step. A petroleum fraction with a boiling point of 200-650 °C is first catalytically and then thermally cracked. The residue obtained from thermal cracking is held at a temperature of 480-590 °C and a pressure of 30-400 psi for 4-20 minutes. Short holding times and high linear flow rates are preferred to minimize coke formation. The use of a submerged coil is disclosed without detail.

U.S. Patent No. 3,318,801 discloses the use of a thermal holding drum and a short tubular heater. The thermal holding drum is maintained at a temperature of 340-425 °C and a pressure of 0-30 psig for 3-90 minutes. The tubular heater provides rapid heating to 425-510 °C at a pressure of 25-250 psig for 2-30 minutes.

U.S. Patent No. 3,673,077 discloses a heat soak process used in the manufacture of pitch binder to increase the insoluble toluene (IT) content. The conditions are 350-450°C, pressure ~75 psig, and soak time from 15 minutes to 25 hours. It is also disclosed that air is passed through the reactor if necessary.

U.S. Patent No. 4,039,423 discloses a thermal treatment of decantation to produce petroleum pitch. The conditions are 413-524 °C at 220-440 psig, with a holding time of 3-300 minutes. Continuous turbulent rather than laminar flow is preferred, which minimizes coke formation and maintains insoluble quinolines in suspension. It also improves mixing efficiency and reduces reaction time. The softening point of the products ranges from 79-135 °C.

EC Patent No. 1 739 153 discloses the use of heat treatment of coal tars and distillates under an inert gas atmosphere. Conditions: 340-400 °C, pressure less than 145 psig, holding time 3-10 hours. Preferred parameters: 370-400 °C at 14 psig for 4-6 hours. It is assumed that heat treatment under an inert gas atmosphere increases the planarity of the molecular structure and stabilizes the product of the main reaction, limiting the occurrence of side reactions. This improves wettability, graphitization and increases the reaction yield. Anthracene oil can be used as a raw material.

U.S. Patent No. 8,757,651 discloses the use of heat treatment of coal tar distillate at 350-440 °C under 50-120 psig to produce pitch. The holding time is from 1 to 7 hours. Creosote oils with a low content of insoluble quinolines can be used as feedstock. It is believed that the heat treatment can polymerize relatively low molecular weight components to form larger molecules. Subsequent distillation of the product is contemplated to function into components. The final products have a coke number of 55-70% and a softening point of 90-140 °C. Another target is less than 15% insoluble quinolines. Batch and continuous heat treatment are proposed, but details of the reactor are not provided.

U.S. Patent No. 9,222,027 discloses a heat treatment using an electrically heated tubular reactor operating at high flow rates and pressures. Also described are salt and molten metal baths. The process parameters are 450-560 °C at 500-900 psig, with a holding time of 1-2 minutes. Laminar and turbulent flows in the reactor tubes are considered, with turbulent flow being preferred. The Reynolds number of turbulent flow is considered to be greater than 4,000. A Reynolds number greater than 10,000 is preferred, with 25,000 achieving the best experimental results. Suggestions of achieving a Reynolds number greater than 50,000 are presented without any experimental data.

U.S. Patent Application No. 20170121834 discloses the production of petroleum pitch using thermal processing. The reaction chamber operates at 360-460 °C and 215-265 psi. The holding time is from 15 minutes to 5 hours. An inert gas environment or at least an oxygen-free environment is required. Decantate, lubricant extracts and gas oils are used as feedstock.

Despite the efforts made, there remains room for further improvement, as the existing solutions have not achieved commercial success. Therefore, a method and device for thermal treatment that can be used to process coal tar and petroleum by-products and at the same time give predictable and stable results on an industrial scale remains unknown in the art. Critical limitations of the application area of the known solutions are the formation of excess coke or mesophase after thermal treatment, which prevents continuous processing of the raw materials. As a rule, this is due to excessive application of the treatment or excessive variation in duration and temperature. Experience with existing solutions shows that recirculation of the contents of a batch reactor has a negative effect on the quality of the pitch.

DISCLOSURE OF INVENTION

The paper discloses processes for heat treatment of distillate by-products formed during the production of coal tar or petroleum products, which ensure an increase in the yield of pitch. Particular attention is paid to the parameters of holding time, temperature and pressure, which ensure the minimization of coking and mesophase formation. The corresponding processes for the production of coal tar or petroleum pitch, which use heat treatment processes, are disclosed.

In particular, the heat treating processes of the present invention utilize a heavy distillate that is distilled in the late stages of producing pitch and decantate from petroleum products as a starting material (feedstock). The inventive heat treating processes heat treat this starting material (feedstock) at a specific temperature, pressure, and holding time to form additional pitch and increase the overall yield of the product. Accordingly, the inventive heat treating processes increase the overall efficiency of the overall pitch production and also allow for the recovery of less profitable by-products. Control of temperature, pressure, and holding time during the heat treating process is critical to minimize the formation of insoluble quinolines and to prevent the formation of mesophase. The present invention utilizes high temperatures, which may be above 510 °C, and pressure ranges, such as above 46 psig, for example above 46-300 psig. In the heat treatment apparatus, the feedstock and reactants are maintained in the liquid phase at a pressure of 60-300 psig or even above 60-300 psig to maintain the feedstock and reactants in the liquid phase. This allows them to move steadily throughout the heat treatment subsystem. Since mesophase is known to form at ~390 °C, the present invention provides for an appropriate residence time to minimize the possibility of mesophase formation and hence coking. The present invention also attempts to achieve, as far as is physically possible under practical conditions, turbulent heating of the feedstock followed by the creation of a core flow through the reactor section of the heat treatment apparatus in order to maintain a continuous and steady flow of feedstock through the system to achieve approximately uniform heat exposure (we will conventionally call this regime "near uniform flow"). By core flow, in this description, we mean near uniform flow. Longer residence times in the system increase the likelihood of mesophase formation and coking. This can be reduced by lowering the temperature, but this is not desirable. After heat treatment, the raw material can be fed back into the continuous pitch production process as additional raw material to increase product yield.

In addition, there is reason to believe that in the future, pitch with an increasingly higher softening point will find industrial applications. Today, the softening point of most pitches and pitch blends on the market is in the range of 90-150 °C. The lower softening point of pitch is due to the high content of PAHs. A decrease in this parameter increases the softening point. Many of these compounds may be carcinogenic. A number of states and countries are introducing increasingly strict restrictions on the exposure of people and the environment to such substances. Therefore, in the future, the softening point of pitch may increase, since this will allow the removal of more carcinogenic compounds with a high PAH content. Heavy distillate contains many highly aromatic compounds. As is known, increasing the amount of heavy distillate removed during pitch formation leads to an increase in the softening point of the pitch. An additional advantage will be the development of a method for using this additional heavy distillate, especially if additional quantities of pitch can be obtained from it. The systems and processes disclosed in this patent provide just such an advantage.

The following is a detailed description of the heat treatment and pitch production systems and processes, their features and advantages. The drawings mentioned in the text are attached to the patent application.

DESCRIPTION OF DRAWINGS

Fig. 1A is a flow chart of the first embodiment of the known method for producing pitch from wet coal tar or decantation.

Fig. 1B is a flow chart of a second embodiment of a known method for producing pitch.

Fig. 1C - flow chart for implementing the third variant of the known method for producing pitch.

Fig. 2A is a flow chart of a first embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from coal tar.

Fig. 2B is a flow chart of a second embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from coal tar.

Fig. 2C is a flow chart of a third embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from coal tar.

Fig. 3A is a flow chart of a first embodiment of a pitch production system of the present invention that includes thermal treatment to increase the yield of pitch from petroleum by-products such as decantate.

Fig. 3B is a flow chart of a second embodiment of the pitch production system proposed in the present invention, which includes thermal treatment to increase the yield of pitch from petroleum products.

Fig. 3C is a flow chart of a third embodiment of the pitch production system proposed in the present invention, which includes thermal treatment to increase the yield of pitch from petroleum products.

Fig. 3D is a flow chart of a fourth embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from petroleum by-products such as decantate.

Fig. 3E is a flow chart of a fifth embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from petroleum products.

Fig. 3F is a flow chart of a sixth embodiment of the pitch production system of the present invention, which includes thermal treatment to increase the yield of pitch from petroleum products.

Fig. 4A is a flow chart of a first embodiment of the heat treatment system proposed in the present invention.

Fig. 4B is a flow chart of a second embodiment of the heat treatment system proposed in the present invention.

In all drawing views, the same positions correspond to the same equipment elements.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

As shown in the accompanying drawings, the present invention relates to heat treatment systems 300, 300', pitch production systems 100, 100', 100" (from coal tar) and 200, 200', 200" (from petroleum products). For example, Figs. 2A-2C show various embodiments of producing pitch 150 from coal tar 102, and Figs. 3A-3C show various embodiments of producing petroleum pitch 250 from decantation 203. Figs. 4A-4B show various heat treatment subsystems 300, 300' compatible with any of the pitch production systems.

Coal tar

First, consider pitch production systems. In a first embodiment of such a system 100, schematically shown in Fig. 2A, the process begins with the dewatering of coal tar 102. The raw coal tar 102 most likely contains some water or moisture formed as a result of the initial coking process. The moisture level should not exceed about 4% by weight so as not to slow down the pitch production process. For dewatering, the coal tar 102 is fed to the first column C1 through a line 110. The line 110 may pass through at least one heat exchanger (not shown), in which heat is supplied to it from other elements of the system, thereby preheating the pitch 102 in the line and simultaneously cooling another element.

As disclosed in this document and in the drawings, heat exchangers eliminate mixing of components, but provide heat transfer from a hotter substance to a colder one. This allows for efficient use of heat generated in the system, which is especially important at industrial scales of production, when the costs of heating the elements of the system are very expensive, which requires a large amount of fuel. To efficiently use heat, several heat exchangers can be installed in the system. In at least one embodiment of the invention, distillate lines pass through the heat exchangers to cool it before storage and to heat another component - such as raw pitch 102. In other embodiments, petroleum products are used to heat the cooling component in the heat exchangers.

In at least one embodiment of the invention, the coal tar 102 has an initial temperature of ~50 °C. The coal tar 102 is heated to a temperature of ~160 °C as it passes through the feed line C1 110 and at least one or, in some cases, multiple heat exchangers. Thus, when the coal tar 102 enters the first column C1, its temperature is at least 160 °C. As the coal tar 102 passes through the line 110, it is under a pressure of, for example, ~100 psia. The first column C1 operates at atmospheric pressure (about 1 atm or 14.7 psia). When the coal tar 102 enters the first column C1 through the diaphragm 111, the sudden pressure drop causes the resin 102 to instantly evaporate and then separate into its constituent components. Preferably, there is no reboiler or other heater for heating the first column C1. Therefore, the temperature of the first column C1 is approximately equal to the temperature of the incoming wet coal tar 102 - not less than 160 °C.

Water vapor and distilled light ends (such as BTX) rise in the first column C1 and are withdrawn via vapor line 113. They are then condensed in water-cooled condensers at a maximum temperature of ~75 °C and collected as column distillate C1 in line 112. Water distills at a temperature of ~100 °C. Light ends distill at about the same temperature: benzene (80 °C), toluene (110 °C) and possibly xylene (144 °C). Thus, these light ends and water are distilled and withdrawn together. The light ends, which constitute about 1% of the coal tar volume, are immiscible with water and are decanted to form the upper layer of distillate 112 in column C1. They are then pumped to storage. The specific gravity of the light fractions should be monitored and not allowed to exceed it (e.g. not more than 0.92 at 15.5 °C), since otherwise the separation of oil fractions from condensed water will deteriorate. This can happen when there is an excess feed of wet coal tar 102 into the first column C1.

Distillation in the first column C1 continues until the water content in the dehydrated fuel oil 114, collected in C1 as a still residue, decreases to a level of no more than 2.5 mass % (preferably less than 0.5%). In this case, the specific gravity is no less than 1.15 at 15.5 °C. Then this dehydrated fuel oil 114 is removed from the first column C1 through line 115, which can pass through at least one heat exchanger to increase the temperature of the dehydrated fuel oil 114 to 250-270 °C before it enters the second column C2 for distillation of light fractions.

In the second column C2, the dehydrated fuel oil 114 is further distilled to obtain a light distillate 122 that contains crude naphthalene in the form of NPH. This process is called stripping the light fractions of the fuel oil, since it removes the lowest boiling fraction (the top distillate) of the dehydrated fuel oil 114. The incoming dehydrated fuel oil 114 already has a temperature of 250-270 °C when it enters the second column C2. The feed to the column C2 is controlled by a heater, vacuum systems and a condenser of the second column C2. The second column C2 is an atmospheric pressure column (1 atm) with distillation trays 120 located below the feed point of the dehydrated fuel oil 114. In at least one embodiment, 20-30 trays are installed in the second column C2. Above the feed point of dehydrated fuel oil 114, there may also be at least one section of packing 121 that further purifies the light distillate 122 as it is distilled. The second column C2 may be equipped with a heater, such as a reboiler with a fired process heater or another suitable heat source, for the purpose of heating the bottoms to a temperature of 350-360 °C and further distilling the light distillate 122. The vapors of the light distillate 122 rise through the second column C2 and are typically withdrawn through a distillate line 123 with a feed of about 15-22% of the feed to the column C2. The light distillate 122 may then be condensed in one or more condensers to convert it to a liquid form that contains NPH with naphthalene, and then cooled with water in a heat exchanger. The light distillate 122 preferably contains 55-65% naphthalene. It can be further processed in oil refineries to separate and purify naphthalene. The light distillate 122 preferably has a maximum specific gravity of 1.03 at 70 °C. The properties of the light distillate 122 are presented in Tables 1 and 2. At least a portion of the light distillate 122 can be returned to the top of the second column C2 for additional reflux, which limits the amount of high-boiling compounds and increases the content of the gasoline fraction in the light distillate 122. In the present disclosure, it should be especially noted that all distillate and vapor streams can be diverted, stored for further use and returned to a suitable point in the process, as is well known to those skilled in the art. The liquid reflux in column C2 condenses higher boiling compounds from the vapors above the feed point, which increases the fractionation efficiency in the upper fractionating section of the second column C2. Light distillate 122 can flow into the column at a feed rate of at least 10% of the feed to column C2 to increase the naphthalene content of the light distillate 122. 15-22% of the original coal tar 102 is removed as light distillate 122.

The bottoms of the C2 column contain lean fuel oil 125, which is then pumped to the third column C3 via line 126 to produce pitch with the desired softening point. Line 126 retains heat, so that the lean fuel oil 125 entering the third column C3 has approximately the same temperature as the bottoms of the C2 column. Alternatively, soft pitch 127 can be fed to line 126 before the third column C3 and mixed with the lean fuel oil 125 fed to the C3 column as feed. This is done to adjust the temperature, increase the volume of the feed, or to remove residual oil from the soft pitch. The third column C3 is preferably a vacuum column, operating at an absolute pressure of 40-100 millibars (0.77-1.9 psia). It also comprises trays 120 and packing sections 121 at the top for carrying out multi-stage distillation. A heater, such as a reboiler with a fired process heater or other suitable heat source, may be used to heat the bottoms in the column C3 to a temperature of 350-360 °C in order to bring the heavy petroleum distillates coming from the stripped fuel oil 125 to boiling by recirculating the liquid bottoms C3.

As the stripped fuel oil 125 is distilled in the third column C3, the distillate vapors rise through the column and are condensed by recirculating various distillates. In particular, the first middle distillate 135 is collected through the distillate line 136 and is cooled externally by other process media, flows of heat-transfer oil product or water for the purpose of condensation. Its properties are given below in Tables 1 and 2. The first middle distillate 135 is an intermediate soot raw material. It is used primarily to improve the quality of other substances and as a mixture with oil products. Some of it can be returned back to the third column C3 or sent for storage and sale. Less than 5% of the original coal tar 102 is distilled off as the first middle distillate 135.

The second product from the third column C3 is the second middle distillate 138. It contains creosote components such as the petroleum base for creosote produced to WEI-C or AWPA standards. The second middle distillate 138 is withdrawn through the distillate line 139 and is cooled externally by other process fluids, heat transfer oil streams or water for the purpose of condensation. 13-22% of the total amount of crude pitch 102 is distilled as the second middle distillate 138. The properties of the second middle distillate 138 are given below in Tables 1 and 2. In addition, its maximum distillation is 10% at a temperature of 300 °C and 65-90% at a temperature of up to 355 °C. In some cases (especially in Europe), the content of not more than 10 parts per million of benzo(a)pyrene is allowed. At least a portion of the distilled second middle distillate 138 can be recycled to the third column C3 for reflux. The creosote contained in the second middle distillate 138 is very useful in many industries, for example as a wood preservative. Therefore, its quality is checked by monitoring the temperature range of distillation and the content of benzo(a)pyrene. The quality of the second middle distillate 138 is determined by its share of the total amount of coal tar 102. It is desirable that it be in the range of 14-20%. In addition, the quality depends on the temperature of the distillate when it is recycled to the third column C3 for reflux. A temperature range of 100-115 °C is preferred.

The third product obtained from the distillation of the stripped fuel oil 125 in the third column C3 is the heavy distillate 141, which is withdrawn through the distillate line 142. It is cooled externally by other process media, heat transfer oil or water flows for the purpose of condensation. This heavy distillate 141 is also a mixture of components, mainly containing soot feedstock. But it also contains additional components that are absent in the first middle distillate 135, as shown in Table 1 below. This increases the PAH level and the boiling point of the heavy distillate 141. In addition, the heavy distillate 141 has an extremely low, practically zero, concentration of insoluble quinolines and toluene. The maximum distillation degree of the heavy distillate, equal to 10%, is achieved at temperatures up to 355 °C. At least a portion of the heavy distillate 141 may be returned to the third column C3 for further distillation and fractionation by reflux. Approximately 14% of the total amount of the starting pitch 102 may be distilled off as the heavy distillate 141.

The main properties of the various distillates formed in the first embodiment of the coal tar production system 100 are given below in Tables 1 and 2. The amount of components depends on the desired softening temperature of the resulting pitch.

Table 1.

Component Light distillate 1st stream of middle distillate 2nd stream of middle distillate Heavy distillate (% of total) (% of total) (% of total) (% of total) Benzene 0.20 Toluene 0.30 Ethylbenzene 0.20 m+p xylene 0.30 Styrene 0.20 o-xylene 0.24 3+4 ethyltoluene 0.10 0.07 1,3,5-trimethylbenzene 1.14 0.03 Phenol 0.73 0.05 1,2,3-triethylbenzene 0.10 0.08 Indan 0.48 0.05 0.08 Inden 4.53 0.75 0.01 Naphthalene 62.40 3.49 0.20 Methylnaphthalenes 11.75 11.38 0.20 0.08 Quinoline 0.77 0.37 0.34 0.03 Acenaphthene 0.70 17.68 8.20 0.44 Acenaphthylene 1.09 7.75 4.23 0.26 Dibenzofuran 1.29 0.59 0.43 0.03 Fluorene 1.85 10.14 7.53 0.04 Phenantliren 1.59 12.70 26,22 5.23 Anthracene 0.24 2.90 4.45 1.46 Carbazole 1.78 4.75 2.02 4H-cyclopenta[def]
phenanthlyren 0.89 3.36 1.35 Fluoranthene 1.33 8.66 15.13 Pyrene 0.51 3.89 13.86 Benz[a]anthracene 0.01 5.29 Chrysen 5.25 Benzofluoranthenes 4.84 Benzo(e)pyrene 1.48 Benzo(a)pyrene 1.76 Boiling point 80-340 °C 248-425 °C 265-437 °C 308-496 °C

Table 2.

Component 1st stream of middle distillate 2nd stream of middle distillate Heavy distillate Melting point 115 °C (%) Melting point 130 °C (%) Melting point 115 °C (%) Melting point 130 °C (%) Melting point 115 °C (%) Melting point 130 °C (%) Inden 0.4 0.6 0.1 0.1 0.1 Naphthalene 3.3-4.9 3.2-6.2 0.3-0.9 0.4-0.8 0.1 0.1 Thionaphthalene 0.1-0.3 0.2 0.1 0.1 0.1 0.1 Quinoline 1.4-2.2 1.2-1.6 0.4-0.6 0.3-0.5 0.1 0.1 Isoquinoline 0.5-0.7 0.4-0.6 0.1 0.1 Indole 1.0-1.4 1.0-1.2 0.2-0.4 0.3 2-methylnaphthalene 5.5-6.9 5.3-5.9 1.1-1.5 1.0-1.4 0.2 0.2 1-methylnaphthalene 2.6-3.2 2.4-2.8 0.5-0.7 0.5-0.7 0.1 0.1 Biphenyl 2.2-2.4 2.0-2.6 0.7 0.5-0.9 0.1 0.1 Dimethylnaphthalenes 2.7-3.1 2.5-3.1 0.8-1.0 0.7-1.1 0.1 0.2 Acenaphthene 0.3-0.5 0.3-0.5 0.1 0.1 0.1 0,0 Acenaphthylene 14.7-16.1 15.9-17.3 5.5-6.3 57-7.3 0.8-1.0 1.0 Dibenzofuran 7.6-8.6 7.3-8.7 3.6-4.0 3.3-4.5 0.6-0.8 0.8 Fluorene 9.9-10.9 10.5-10.7 5.7-6.5 6.0-70 1.0-1.2 1.3 2-methylfluorene 0.6-0.8 0.7 0.5-0.7 0.6 0.1 0.1 1-methylfluorene 0.3 0.3 0.3 0.3 0.1 0.1 Dibenzothiophene 1.4-1.6 1.5 1.6-1.8 1.7-1.9 0.5 0.6 Phenanthrene 19.6-22.6 21.4-22.0 25.7-30.1 28.2-30.8 7.5-8.5 9.0-10.0 Anthracene 5.3-5.9 5.6-5.8 6.4-8.2 7.9-8.9 2.1-2.5 2.5-2.9 Carbazole 2.3-3.1 2.2-2.8 4.2-5.8 4.9-5.5 1.6-2.0 1.9-2.1 3-methylphenanthrene 0.7 0.7 1.2-1.4 1.3 0.5 0.6 2-methylphenanthrene 1.0 0.8-1.0 1.7-2.1 1.6-2.0 0.7-0.9 0.9 Cyclopenta[def]phenanthrene 1.5-1.7 1.5-1.7 3.2-3.8 3.4-3.6 1.4-1.6 1.6-1.8 (4+1)-methylphenanthrene 0.3 0.3 0.6-0.8 0.7 0.3 0.4 Fluoranthene 3.9-5.1 3.5-4.5 14.5-17.3 13.3-15.5 14.5-16.1 16.2-18.2 Pyrene 2.3-3.1 2.0-2.6 9.8-11.8 8.3-9.9 14.5-16.1 15.9-17.7 Benzo[a]fluorene 0.2 0.1 0.7-0.9 0.6-0.8 3.1-3.5 3.4-3.6 Benzo[b]fluorene 0.2 0.2 0.9-1.1 0.7-1.1 3.5-3.9 3.7-4.1 Benz[a]anthracene 8.2-8.7 9.1-9.7 Chrysen 7.5-8.3 8.2-8.8 Benzo(bjk)fluoranthene 7.1-7.9 10.0-10.8 B(e)P 2.4-2.6 3.5-3.7 Benzo(a)pyrene 2.7-3.1 4.1-4.3

The bottom residue in the column C3 is the desired finished product - coal tar pitch 150. Its quality parameters include, among others, the softening point, the proportion of distillates released at a temperature of up to 355 °C, the content of insoluble quinolines and toluene. These three parameters depend on the temperature of the bottom residue C3 and the feed of heavy distillate 141. Preferably, the softening point of the finished pitch 150 is in the range of 100-140 °C, and the content of insoluble quinolines does not exceed 20%. In addition, the preferred ash content in the finished pitch 150 is no more than 0.4%, and the desired proportion of distillate released at temperatures of up to 355 °C is no more than 4%. The system 100 and the corresponding technological process are capable of providing a pitch yield of ~40% and higher. Pitch 150 is withdrawn from the third column C3 via line 151 for further storage, transportation, use or sale.

The pitch production system 100 includes a heat treatment subsystem 300. Details of the heat treatment subsystem 300 are provided below and in Figs. 4A and 4B. It should be noted that the heat treatment process 300 is capable of increasing the overall pitch yield 150 by 2-10%, ensuring that a rate of 42-50% is achieved. In some embodiments of the invention, the pitch yield is increased to a preferred value of 44%. The increase in the pitch yield 150 is achieved by heat treating the distilled heavy distillate 141 at a pre-selected temperature and holding time, and then feeding the heat-treated product to the third column C3 for further distillation and fractionation of the pitch in the resin production system 100, as shown in Fig. 2A.

The present invention also includes a second embodiment of a coal tar pitch manufacturing system 100', schematically shown in Fig. 2B. Coal tar pitch 102 is heated to 160-170 °C by passing through at least one heat exchanger (not shown) in a feed line 110 to a column C1. The pitch is then under a pressure of ~100 psig. Coal tar pitch 102 is fed to a first column C1 through an orifice 111. The material from line 110 enters the column C1 through this orifice. In this embodiment, the first column C1 is a dehydrator operating at near atmospheric pressure of ~900 mmHg (17.4 psig). The pressure difference between the feed line 110 and the first column C1 causes the wet coal tar 102 to flash evaporate, releasing water vapor and light oil fractions such as benzene, toluene and xylene to form distillate 112 in column C1. As in other embodiments, the bottoms in the first column C1 are dehydrated fuel oil 114. The fuel oil remains in the first column C1 until its water content is reduced to ~2.5% (preferably to less than 0.5%). Its parameters are the same as those of the dehydrated fuel oil 114 described above.

The dehydrated fuel oil 114 is fed through a line 115 from the column C1 to a second column C2, which is a fractionator or a multi-stage distillation column, as described above. In this case, a vacuum of 120-180 mm Hg (2.3-3.48 psia) is created in the second column C2. The column is heated to an internal temperature of 182-230 °C. In a second embodiment of the process system 100', a light distillate 122' is withdrawn through a line 123. The light distillate 122' has the composition and properties presented below in Table 3. A middle distillate 138' is also distilled and withdrawn from the second column C2. Middle distillate 138' has the composition and properties presented below in Table 3. Still residues C2 are heated by a heater (not shown) to a temperature of 350-365 °C, which ensures their circulation and facilitates the distillation process. Stripped light and middle distillates 122', 138' may be mixed and stored together. They may also be stored separately and then processed, for example, to obtain purified creosote, which is sold to customers or used for other purposes.

The bottoms C2 contain the stripped fuel oil 125'. Its properties are similar to those described earlier. The temperature is in the range of 350-365 °C, and the pressure is 180-220 mm Hg (3.48-4.25 psi (abs.)). In the second embodiment of the process for producing pitch 100', the stripped fuel oil 125' is fed from the second column C2 to the fourth column C4 through line 126'. The fourth column C4 is an evaporative column, unlike the above-described fractionating third column C3. The stripped fuel oil 125' is fed to the fourth column C4 through an opening 111 (for example, a sparger or other suitable device). The fourth column C4 is under vacuum at a pressure of 40-70 mm Hg. (0.77-1.35 psia). When the trimmed fuel oil 125 is flashed in the fourth column C4, the heavy distillate 141' is separated at a temperature of 290-365 °C and is withdrawn through the distillate line 142. This heavy distillate 141' contains the components and has the properties listed below in Table 3. The heavy distillate 141' is then fed to the heat treatment subsystem 300 described below for heat treatment to increase the yield of pitch. After passing through the heat treatment subsystem 300, the heat treated product enters the line 115 connecting columns C1 and C2 and is mixed with the feedstock of column C2 for additional fractionation and distillation. The yield of 150' pitch obtained as a result of this process is 20-40% higher compared to the original yield of heavy distillate 141' without heat treatment.

The various distillates obtained by the second preferred embodiment of the pitch production system have the properties presented in Table 3.

Table 3.

Component Light distillate (% of total volume) Middle distillate (% of total volume) Heavy distillate (% of total volume) Benzene 0.16 Toluene 0.17 Ethylbenzene 0.07 m+p xylene 0.32 Styrene 0.23 o-xylene 0.13 3+4 ethyltoluene 0,00 1,3,5-trimethylbenzene 0,00 Phenol 0.12 1,2,3-triethylbenzene 0,00 Indan 1.45 0.07 Inden 3.21 0.22 Naphthalene 53.76 12.86 Methylnaphthalenes 7.58 0.90 Quinoline 0.61 5.16 Acenaphthene 3.79 0.63 2.35 Acenaphthylene 1.36 1.96 0.07 Dibenzofuran 2.26 3.71 0.29 Fluorene 2.88 17.03 0.83 Phenanthrene 4.43 2.91 9.77 Anthracene 0.97 1.62 3.19 Carbazole 1.61 1.83 4H-cyclopenta[def]
phenanthrene 2.00 2.00 Fluoranthene 11.56 16.23 Pyrene 8.03 14.74 Benz[a]anthracene 0.50 4.71 Chrysen 1.76 4.98 Benzofluoranthenes 0.82 4.09 Benzo(e)pyrene 0.39 1.16 Benzo(a)pyrene 0.62 1.46 Boiling point 80-340 °C 265-496 °C 279-496 °C

In a third embodiment of a pitch manufacturing system 100", shown in Fig. 2C, coal tar 102 is heated to a temperature of 124-184 °C as it passes through at least one heat exchanger (not shown) in a feed line 110 of a column C1 at a pressure of 158-161 psig. Coal tar 102 is fed to a first column C1 through an orifice 111. It is through this orifice that the material from line 110 enters column C1. In this embodiment, the first column C1 is a dehydrator that is at atmospheric pressure of ~15.6 psia. The pressure drop between feed line 110 and first column C1 causes the wet coal tar 102 to flash, separating water vapor and light oil fractions such as BTX as a distillate. 112 with a temperature of ~115 °C. As in the previously described embodiments, the bottoms of column C1 are dehydrated fuel oil 114, which remains in the first column C1 until its water content decreases to no more than 2.5% (preferably less than 0.5%) and the temperature reaches approximately 230 °C.

The third embodiment of the system 100" differs from the previous embodiments in that it uses four columns for distillation and separation of oil fractions during the production of pitch. In particular, dehydrated fuel oil 114 is fed to the second fractionator column C2 via line 115 and heated to a temperature of ~262 °C using a heater (not shown). Light distillate 122" is distilled from the second column C2 and can be returned to the column for further fractionation. The properties of the light distillate 122" are given below in Table 4. It can contain HPH and other light oil fractions. The finished stripped fuel oil 125", formed as a bottoms residue in column C2, can be fed to the third column C3 via line 126 for further distillation.

In the third column C3, the pitch is heated to a temperature of ~330 °C using a heater (not shown) to distill off the middle distillate 138". The properties of the middle distillates 138" are given below in Table 4. They may contain creosote and a number of carbon black compounds. The middle distillate 138" can also be returned to the third column C3 for additional distillation and fractionation. The soft pitch 127", formed as the bottoms of the third column C3, has close to the required characteristics. However, it is possible to obtain too low a softening point, for example, ~90 °C. To increase the softening point of the pitch, further removal of oil fractions is necessary.

To achieve this, the soft pitch 127" can be fed through a line connecting columns C3 and C4 to a fourth flash column C4, which uses the pressure drop to remove oil fractions from the solids. For example, the fourth column C4 may be under a vacuum of ~1 psia. Under the action of the pressure drop, the heavy distillate 141" is distilled off, leaving the coal tar pitch 150" at the bottom of the fourth column, which is withdrawn for further use or sale. The heavy distillate 141" is at a temperature of ~310 °C and a pressure of ~1 psia. Its properties are presented below in Table 4.

The next step in the 100" process is the thermal treatment of the stripped heavy distillate 141" in the thermal treatment subsystem 300, which is described in more detail below. After thermal treatment, the heavy distillate 141" is mixed with the stripped fuel oil 125" to form the feedstock for the C3 column, or is fed separately to the C3 column for the purpose of stripping the middle distillate 138" and then the heavy distillate 141" from the newly formed additional amount of pitch.

The properties of the distillates produced in the third preferred embodiment of the coal tar pitch production system 100" are shown in Table 4.

Table 4.

Component Light distillate (% of total volume) Middle distillate (% of total volume) Heavy distillate (% of total volume) Benzene Toluene Ethylbenzene 0-0.58 0-0.55 m+p xylene Styrene 0-0.43 0-0.32 o-xylene 3+4 ethyltoluene 1,3,5-trimethylbenzene 0-1.23 0-0.58 Phenol 1,2,3-triethylbenzene Indan 0.55-0.74 0-0.29 Inden 6.45-6.58 3.00-4.28 0-0.28 Naphthalene 47.89-56.51 3.48-6.00 Methylnaphthalenes 6.56-11.19 1.32-5.00 Quinoline 0-1.47 Acenaphthene 2.12-3.88 6.00-6.71 2.01-4.41 Acenaphthylene 1.71-2.16 0-3.00 0-2.00 Dibenzofuran 1.50-3.69 2.50-3.38 0.16-0.53 Fluorene 0.71-2.85 4.81-5.00 0.78-1.73 Phenanthrene 0.04-0.96 17.00-17.11 6.51-12.81 Anthracene 1.55-3.00 2.25-4.18 Carbazole 1.49-3.00 1.39-3.24 4H-cyclopenta(def)
phenanthrene 0-2.17 0-1.92 Fluoranthene 10.00-13.60 14.82-18.35 Pyrene 10.00-10.93 13.51-19.27 Benz[a]anthracene 2.50-2.53 5.18-5.46 Chrysen 1.29-1.50 4.56-5.85 Benzofluoranthenes 0.50-1.47 3.72-3.93 Benzo(e)pyrene 0.41-0.50 1.02-1.20 Benzo(a)pyrene 0.50-0.56 1.36-1.54 Boiling point 176-336 °C 265-496 °C 308-496 °C

Oil pitch

Petroleum products serve as a feedstock for the production of petroleum pitch 250, as shown in Fig. 3A-3C. For example, as shown in Fig. 3A, a petroleum distillate, such as decantate (typically petroleum product 203), is used as a feedstock for the production of pitch. Decantate 203 is a mixture of heavy fractions obtained as a result of catalytic cracking of petroleum products. In many ways, it is similar to coal tar 102, but differs in a higher content of aliphatic hydrocarbons from petroleum, which complicates the chemical processes for processing the decantate 203. However, many of the steps are similar. In some embodiments, KOEK is used as a feedstock 203 for the production of pitch 200 - alone or in combination with decantate. However, KOEK is less stable, especially in the form of vapor, and is explosive, which makes it difficult to use as a feedstock. In addition, KOEK is usually not suitable for the manufacture of impregnating pitch. The decanter is very stable during storage and convenient to use, therefore, in at least one embodiment of the invention, the use of this substance is preferred. The systems for producing petroleum pitch 200, 200', 200" are described in the mode of using the decanter 203 as a feedstock. It should be borne in mind that any heavy oil or mixture obtained as a result of cracking oil (catalytic or otherwise), having a suitable content of sulfur, carbon and coke number, can serve as a feedstock.

The dehydration and distillation sections of the petroleum pitch production system 200, 200', 200" shown in Figs. 3A-3C and 3D-3F are similar to the dehydration and distillation sections of the coal tar pitch production systems 100, 100', 100" shown in Figs. 2A-2C, respectively. However, the petroleum pitch production systems 200, 200', 200" can have different parameters at each stage. Unless specifically stated otherwise, as is known to those skilled in the art, the parameters for processing coal tar are equally applicable to the processing of petroleum products. In addition, the heat treatment process 300, 300' can be carried out as a first stage in the production of petroleum pitch 250 - before dehydration and distillation of the feedstock, as shown in Figs. 3A-3C. In the production of coal tar pitch 150, this process is carried out after dehydration and distillation of the feedstock. This is primarily due to the chemical composition of the decantate, which does not contain heavier components (compared to coal tar), and the water content at the time of delivery is usually lower. Thus, by-products of the distillation of the decantate are generally not suitable for heat treatment without mixing with other products. Therefore, in the petroleum pitch production systems 200, 200', 200" decantation 203 is fed into the heat treatment subsystem 300, 300'. Such heat treatment subsystems 300, 300' are described in more detail below and are also shown in Figs. 4A and 4B. They can have the same design as the subsystems used in the production of coal tar pitch 150, 150', 150".

As shown in Fig. 3A, in the first embodiment of the pitch production system 200, the decant 203 initially passes through the thermal processing subsystem 300 and then is sent to the rest of the distillation system. The specific process route depends on the mode of operation (batch or continuous) and the water content. If the decant 203 does not require dewatering, then the dehydrator C1, described below and shown in Figs. 3A-3C, can be eliminated and streams 326' and 215 can be combined, as is known to those skilled in the art. If the dehydrator C1 is required, or when carrying out a potentially continuous process, the decantate 203 or the mixed light distillate 222, the first middle distillate 235, the second middle distillate 238, the heavy distillate 241 in any combination can be re-directed to the heat treatment subsystem 300 or the dehydrator C1, as shown in more detail below. In this case, as shown in Fig. 3D-3F, the decantate 203 can be sent to the dehydrator C1 together with the feed stream 310A. After dehydration, as shown below, the decantate is returned for heat treatment via the outlet stream 215A and fed to the heat treatment subsystem 300. Moreover, in a continuous mode of operation, the distillate stream 243 can be recycled to the first column C1 of the dehydrator via the inlet stream 310A. In embodiments using a dehydrator C1, the product is introduced and stripped in the first column of the dehydrator C1. The pressure drop between the incoming heat-treated oil products and the first column C1 results in the separation of light fractions such as naphtha or BTX (benzene, toluene and xylene) from the remainder of the decanter 203. These fractions are withdrawn as a C1 distillate 212 via a line 213. It should be especially noted that BTX and other light fractions can be withdrawn from the reactor 320, as described in more detail below.

The remaining dehydrated fuel oil 214 is fed to the second column C2 of the fractionator via line 215 or returned for thermal processing as discussed above. The second column C2 is heated to a temperature of 350-365 °C by a heater, as in the previously described embodiments, for the purpose of distilling light distillate 222 from the oil. Such distillate contains HPH and creosote. Light distillate 222 can also be recycled in the subsystem 200 for further thermal processing and distillation by feeding it to the light distillate stream 224.

The bottoms in column C2 contain stripped fuel oil after heat treatment 225, which is fed to heat exchangers to raise the temperature to 375-415 °C before being fed to the third column C3, where it undergoes further distillation. As the stripped fuel oil 225 is distilled, various distillates are stripped to form petroleum pitch 250. In particular, the first middle distillate 235 is distilled first, followed by soot feedstock and other components. Stripping of the second middle distillate 238, which contains a number of heavier molecules, is possible. The heavy distillate 241 is stripped last. It contains the heaviest fractions. All of these distillates may be mixed in various combinations and recycled to the subsystem 200 for further thermal processing and distillation by adding to the first middle distillate stream 237, the second middle distillate stream 240 and the heavy distillate stream 243, respectively. As discussed below, the pitch 250 is required to be removed prior to all types of thermal processing. As can be seen from Fig. 3A, the distillate streams 224, 237, 240 and 243 may be mixed in any combinations for subsequent mixing with the fresh decantation liquid 203 entering the thermal processing subsystem 300 at the beginning of the pitch manufacturing process 200 or optionally fed to the dehydrator C1. In addition, it is assumed that distillate streams 224, 237, 240 and 243 may be fed separately to heat treatment subsystem 300 in recirculation mode.

The second embodiment of the pitch production system 200' shown in Fig. 3B is similar, but differs in the distillation step. In particular, the light distillate 222' and the middle distillate 238' are stripped in the second column C2 at a temperature of 350-415 °C. The resulting stripped fuel oil 225' is then fed to the fourth column C4 (as noted above, it is an evaporative one). The heavy distillate 241' is distilled in the fourth column C4 to form the finished petroleum pitch 250'. The light 222', middle 238' and heavy 241' distillates can be recycled to the subsystem 200' for further thermal processing and distillation as a stream of light 224, middle 240 and heavy 243 distillate, respectively. These streams may be mixed before recirculation and feeding to the heat treatment subsystem 300 or fed separately.

A third embodiment of the pitch production system 200", shown in Fig. 3C, is similar, but differs in that it uses four columns in the dehydration and distillation process. Light distillate 222" is stripped in a second fractionator column C2 to produce lean fuel oil 225". Middle distillate 238" is withdrawn from the third fractionator column C3 to produce soft pitch 227', and heavy distillate 241" is withdrawn from the fourth flash column C4 to produce finished petroleum pitch 250". Light 222", middle 238", and heavy 241" distillates can be recycled to subsystem 200" for further thermal processing and distillation as a stream of light 224, middle 240, and heavy 243 distillate, respectively. These streams may be mixed before recirculation and feeding to the heat treatment subsystem 300 or fed separately.

In a preferred embodiment, the light 222', middle 238' and heavy 241' distillates produced by the second embodiment of the petroleum pitch production system 200' have the properties shown in Table 5 below. The properties of the distillates produced in other embodiments of the invention will be similar.

Table 5.

Component Light distillate (% of total volume) Middle distillate (% of total volume) Heavy distillate (% of total volume) Benzene 0.88 Toluene 1.00 Ethylbenzene 1.73 m+p xylene 4.00 Styrene 1.64 o-xylene 5.81 3+4 ethyltoluene 1.65 0.20 1,3,5-Trimethylbenzene 4.88 0.23 Phenol 1.35 0.17 1,2,3-triethylbenzene 5.22 0.08 Indan 0.53 0.09 Inden 0.50 0.14 Naphthalene 0.63 0.90 0.09 Methylnaphthalenes 1.50 5.06 0.61 Quinoline 0.07 0.26 0.40 Acenaphthene 0.04 0.87 0.14 Acenaphthylene 0.03 1.32 0.15 Dibenzofuran 0.05 1.32 0.18 Fluorene 0.06 1.00 0.11 Phenanthrene 1.73 1.68 Anthracene 0.47 0.46 Garbazole 0.37 0.30 4H-cyclopenta[def]
phenanthrene 0.46 1.35 Fluoranthene 1.00 1.43 Pyrene 1.57 6.92 Benz[a]anthracene 0.20 1.47 Chrysen 0.05 2.35 Benzofluoranthenes 0.17 0.26 Benzo(e)pyrene 0.11 Benzo(a)pyrene 0.04 Boiling point >80-340 °C 160-425 °C 218-495 °C

Heat treatment

The present invention also includes heat treatment subsystems 300, 300' for heating distillates formed during the production of coal tar 100, 100', 100" or the initial decantation during the production of petroleum pitch 200, 200', 200". In the heat treatment subsystems 300, 300', specified temperatures and holding times are achieved in order to enrich the substance being processed and to obtain additional pitch that is not formed without heat treatment. This increases the overall yield of resin. It should be noted that these subsystems are interchangeable in design and represent interchangeable embodiments of any of the systems described in the present document.

In Fig. 4A, a first embodiment of a heat treatment subsystem 300 is shown. The product is fed to the subsystem 300 from a pitch production system. For example, this is a heavy distillate 141 from the production of coal tar pitch 100, a decantate 203 or a mixture of a light distillate 222, a middle distillate 238 (or a first and second middle distillate 235, 238) and a heavy distillate 241 from the production of petroleum pitch 200. Regardless of the composition, the feedstock is fed to the heat treatment subsystem 300 in the form of an input stream 310. The feedstock has a temperature of 265-300 °C. The feed stream is fed at a rate of 4-9 tons/hour at a pressure of 3.3-7.5 bar(g) (47.86-108.78 psig). More preferred are temperatures of 273-293 °C, feed rates of 5.5-9 t/h and pressures of 3.5-6.5 bar(g) (50.76-94.27 psig). Even more preferred are temperatures of 278-288 °C, feed rates of 6.5-9 t/h and pressures of 3.8-5.5 bar(g) (55.11-79.77 psig). Finally, most preferred are temperatures of ~283 °C, feed rates of ~7 t/h and pressures of approximately 4.5 bar(g) (65.27 psig). It should be especially noted that the specified flow rates are not process limitations. Increasing the feed rates beyond the described ranges only requires appropriate recalculation of the remaining parameters. The inlet line 310 of the heat treatment subsystem is a pipe or other channel with a diameter of ~2 inches (50.8 mm). A pump 311, such as a blower or other design, is installed in the inlet line 310 of the heat treatment subsystem to supply the feedstock and raise the pressure to 6.2-11.7 barg (89.92-169.69 psig), more preferably to 7.2-9.7 barg (104.42-140.69 psig), even more preferably to 7.5-8.7 barg (108.78-126.18 psig), and most preferably to ~8.8 barg (127.63 psig). The input line 310 of the heat treatment subsystem directs the initial product to the heat exchanger 312, which increases the temperature of the product to 459-535 °C or 455-490 °C, more preferably to 470-490 °C, even more preferably to 475-490 °C and most preferably to ~480 °C. From the heat exchanger 312, the initial product moves along the line 313 (which can be heated) to the process heater 314 (preferably with turbulent flow). The process heater 314 can be a thermal reactor of any type, in particular with induction heating. For example, in at least one embodiment of the invention, the process heater 314 includes an immersion coil 315 made of a thermally conductive material to facilitate heat transfer, and a line 313 is connected to the coil 315. It should be understood that "thermally conductive" is considered to be a substance that transfers heat or facilitates heat transfer, and not any particular mechanism or mode of heating. Although not required, turbulent flow of the input stream in the process heater 314 is highly desirable. At least one source 316 is used, such as an AC, DC or other type of energy supply, to provide operation of the process heater 314 and heat the coil 315. It should be noted that any known type of thermal energy can be used, including inductive heating, open flame, molten substances (such as salt or metal), electric heating coils, etc. The only limitation is the ability to supply the desired amount of heat. As the material passes through the coil 315 and the process heater 314, it is brought to a temperature of 475-510 °C and a pressure of 4.2-11.7 bar(g) (60.92-169.69 psig), more preferably 490-510 °C at a pressure of 5.2-9.7 bar(g) (75.42-140.69 psig), even more preferably 495-510 °C at 5.5-8.7 bar(g) (79.77-126.18 psig), and most preferably ~500 °C at ~6.8 bar(g) (98.63 psig).

The heated material exits the process heater 314 through the line 317 and moves into the reactor 320. The outlet line of the reactor 317 can have a smaller diameter than the aforementioned inlet line 310, for example, ~5/4 inches (31.75 mm), in order to create a high-speed or turbulent flow. The reactor 320 consists of several vessels, pipes or channels through which the heated material passes. In this case, the desired holding time in the heat treatment subsystem 300 is achieved. Accordingly, the reactor 320 can have different lengths, shapes, sizes and locations, as is known to those skilled in the art, in order to achieve the desired holding time. In practice, the heated material is introduced into the reactor 320 and passes through as a continuous flow with a structural core. Typically, the flow moves uniformly or nearly uniformly within the normal flow characteristics of the pipeline or vessel. It is preferable, however, to use an elongated vessel with a length to diameter ratio of about 10:1.

For example, in at least a first embodiment of the invention, the outlet line of the reactor 317 is in fluid communication with a first vessel 321, through which a heated substance is fed into this vessel. Since the heated substance is at a high temperature, the free volume of the first vessel 321 is filled with an inert gas 318 (e.g., nitrogen, argon, etc.) in order to prevent oxygen from entering the vessel. The first vessel 321 can have various shapes and/or diameters, as discussed above. In at least one embodiment, it has a length of ~16 m and a diameter of ~14 inches (0.3 m). The vessel can be thermally insulated in order to retain the heat of the heated substance and maintain a temperature of ~500 °C. The first vessel 321 is also under a pressure of 6-7 bar (87-101.5 psi). At such temperature and pressure, the heated substance remains in the liquid phase, which is necessary for its movement through the subsystem 300. Although true adiabatic conditions are practically unattainable, it is assumed that the temperature in the first container 321 (as well as in the corresponding containers of any other embodiment, including the embodiment with a single container, which is considered separately) remains nearly constant over a significant portion of the path of the heated substance through the container. We will call such a regime "nearly constant temperature". In describing this preferred embodiment, temperature deviations of ±30 °C, more preferably ±10 °C, and most preferably ±5 °C will be considered as corresponding to the near constant temperature regime. In addition, it is assumed that in practice the heated substance should pass through the container as uniformly as possible and in the form of a nearly uniform flow.

The heated substance enters the first vessel 321 from below and rises as additional volumes of the substance enter. The heated substance moves through the first vessel 321 essentially in the form of a flow with a structural core so that all the molecules move with almost the same mass flow rate, as far as this can be achieved. It should be understood that, although it is hardly possible to create a complete flow with a structural core due to the mechanics of the interaction of the liquid with the inner surface of the housing, the design of the housing and the reactor 320 as a whole is such that the flow is as uniform as possible. It is necessary to avoid fluctuations in the flow rate in the flow inside the first vessel 321. This is necessary so that all the molecules of the heated substance move through the reactor 320 with the most uniform mass flow rate possible in order to calculate the holding time. The longer the holding time, the longer the molecules of the heated substance are exposed to the effect of a given reaction temperature and the higher the risk of mesophase formation, which can lead to the appearance of coke. Turbulence is useful for creating a nearly uniform flow with a structural core, but it should not reach a level where some molecules move faster and others are captured by vortices or local recirculation of the substance. It is believed that the deviations caused by excessive turbulence lead to a violation of the heat treatment regime in the subsystem 300 and, therefore, negatively affect the quality of the additional pitch 150, 250 obtained in this way.

As the heated substance rises in the first vessel 321, vapors containing light molecular chains 322 are formed above the liquid. They contain small sections of carbon chain molecules that were unable to combine with other molecules or were torn off as by-products during the formation of pitch. The light chains 322 can be removed from the first vessel 321 for further processing, for example, by scrubbing or other means of collecting non-condensable gases. In practice, this vaporous substance is considered to contribute to the uniformity of the flow passing through the vessel. When the level of the heated substance in the first container 321 rises to a predetermined outlet point, it flows into the intermediate line 323, which is hydraulically connected to the first container 321 and the second container 324. The cross-section of the intermediate line 323 can be less than or equal to the cross-section of the first or second containers 321, 323. In at least one embodiment, the intermediate line 323 has a diameter of ~3 inches (76.2 mm), preferably no more than one fifth of the diameter of the first container 321. The line transfers the heated substance from the first container 321 to the second container 324 for further holding.

In at least one embodiment, the second vessel 324 may be a riser or similar elongated structure with a diameter of ~6 inches (0.15 m) and a length of ~5 m. It should have minimal dimensions to slow down further reaction and be provided with thermal insulation to retain heat of the material and maintain a temperature of ~500 °C. The heated material moves through the second vessel 324 in a nearly uniform manner in the form of a flow with a structured core (the terms "uniformly moving flow" and "flow with a structured core" are interchangeable in this text), as described above. The reactor outlet line 325 is in fluid communication with the second vessel 324. This line transfers the heated material from the second vessel 324 to the heat exchanger 312. This can be the heat exchanger 312 described above or another heat exchanger (preferably the same). The outlet line of the reactor 325 can have the same diameter as the outlet line of the reactor 317, for example, ~1.25 inches (31.75 mm), which provides a high pumping rate. The heated material leaving the reactor 320 and returning to the heat exchanger 312 loses some heat when passing through the reactor 320 and is cooled to 465-510 °C, more preferably to 480-510 °C, even more preferably to 485-510 °C, and most preferably to 490 °C. The heated material is then cooled in heat exchanger 312 and its pressure and temperature drop to 275-325 °C and 3.7-11.7 bar(g) (53.66-169.69 psig), more preferably to 280-315 °C and 5.2-9.7 bar(g) (75.42-140.69 psig), still more preferably to 288-305 °C and 5.0-8.7 bar(g) (72.52-126.18 psig), and most preferably to ~300 °C and 6.5 bar(g) (94.27 psig). The heat-treated material contains additional pitch formed as a result of the heat action. To obtain additional pitch, the heat-treated material is removed from the heat exchanger 312 via the outlet line 326, which is connected to various other lines of the resin production systems 100, 100', 100", 200', 200', 200" depending on the embodiment and method of removing the heat-treated product for distillation and removal of oil fractions in order to extract additional pitch. In particular, the outlet line 326 can be connected to the line 126 for transferring the substance from the column C2 to the column C3 in the coal tar production systems 100 and 100", as shown in Fig. 2A and 2C, respectively, for the purpose of feeding additional raw material to the column C3; to the line 115 for transferring the substance from the column C1 to the column C2 of the coal tar pitch production system 100', as shown in Fig. 2B, for feeding additional raw material to the column C2; and also directly to the first column C1 in the petroleum resin production systems 200, 200', 200", as shown in Fig. 3A-3C, for dewatering and subsequent distillation. In other embodiments of the invention, the product after the heat treatment is fed to various sections of the pitch production system. Mixing the heat-treated material with the lean fuel oil 125, 125" or dehydrated fuel oil 114 in embodiments of coal tar processing systems further reduces the temperature, feed and pressure such that the C3 or C2 feedstock, respectively, receives a temperature of 358-375 °C at a flow rate of 98-130 ^m3 /h and a pressure of 2.3-5.5 bar(e) (33.35-79.77 psig), more preferably 362-373 °C at a flow rate of 99-120 ^m3 /h and a pressure of 2.5-4.9 bar(e) (36.26-71.07 psig), even more preferably 364-370 °C at a flow rate of 99-110 ^m3 /h and a pressure 2.8-4.5 bar(g) (40.61-65.27 psig), and most preferably ~367 °C at ~99 ^m3 /h and ~3.5 bar(g) (50.76 psig). It should be noted that in any continuous process, the pitch formed as a result of the heat treatment must be separated from the other fractions contained in the heat treated material before these remaining fractions are reintroduced into the heat treatment subsystem to form additional pitch. In practice, it is undesirable to subject the pitch material to heat treatment since this has a high probability of causing mesophase or coke formation. Therefore, the pitch must be separated by distillation before reheating.

The holding time of the heated material in the heat treatment subsystem 300 is the duration of the heat treatment process. It is defined as the time during which the heated material passes through the following loop: from the heat exchanger 312 to the reactor 320 and again to the heat exchanger 312 for cooling. This loop determines the time during which the heated material is exposed to elevated temperatures of ~500 °C and, therefore, during which precautions must be taken to avoid the formation of mesophase. The holding time depends on the exact values of the temperature and pressure in the system. Higher temperatures or pressures correspond to a shorter holding time. In at least one embodiment, the heat treatment subsystem 300 provides for heating the feedstock (i.e., the starting material) at a temperature of ~500 °C and a pressure of 87-101.5 psig for 3-7 minutes, preferably 7 minutes.

The various distillate fractions produced in the 100, 100', 100" resin production systems have been described fairly well above. Therefore, provided the feedstock (coal tar) and the heavy distillate 141 are constant, the holding time and reaction temperature are relatively predictable, although the exact relationship between the various parameters is quite complex. A number of approximate ranges of operating parameters for the heavy distillate heat treatment process are given below:

Table 6.

Parameter The widest range Preferred range Most preferred range Target value Temperature [°C] 475-510 490-510 495-510 500 Pressure [psi(e)] 46.2 at 490°C 155 at 510°C 60.7 at 490°C 126 at 510°C 65.1 at 495°C 111.5 at 510°C 83.9 Holding time [min] 49.2 at 475°C 3.0 at 510°C 23.6 at 490°C 4.3 at 510°C 16.3 at 495°C 5.7 at 510°C 7.4 at 500 °C Pitch yield [%] 45 15 40 20 35 25 30

Table 7 shows the results of additional calculations of the parameters for various estimated pitch yields at different flow rates during the heat treatment of heavy coal tar distillate. They were obtained taking into account the complex relationship between the parameters noted above.

Table 7.

Consumption
[l/h] Temperature
[°C] Pressure
[psi(e)] Estimated pitch yield
[%] Holding time
[min] 1250 470 >50 22.7 16.4 475 >54 25.6 16.3 480 >60 28.8 16.2 485 >63 32.3 16.1 490 >66 36.2 16.0 495 >71 40.3 15.9 500 >74 44.6 15.8 505 >83 48.8 15.7 1000 470 >50 26.3 20.5 475 >55 29.6 20.4 480 >60 33.2 20.3 485 >63 37.1 20.1 490 >66 41.3 20.0 495 >71 45.5 19.8 500 >74 49.9 19.7 505 >83 54.7 19.6 750 470 >50 31.5 27.4 475 >55 35.4 27.2 480 >60 39.5 27.0 485 >63 43.9 26.9 490 >66 48.5 26.7 495 >71 53.2 26.5 500 >74 58.1 26.3

A second embodiment of the heat treatment subsystem 300' is shown in Fig. 4B. It is also compatible with any of the pitch production systems. Without such heat treatment, the pitch yield is 15-25% of the volume of the initial decantation 203. With heat treatment according to the process described in relation to the system 300', the yield can be increased by 25-30%, and the total pitch yield will be 40-50%. If the distillates are subjected to repeated heat treatment, then the total pitch yield can be increased to 60-80% depending on the quality of the raw materials and distillates.

In this embodiment of the heat treatment subsystem 300', the reactor assemblies 320' may differ slightly from those previously described, as may some of the operating parameters of the overall heat treatment subsystem 300'. As a non-limiting example, in the experimental design, the feedstock enters the heat treatment subsystem 300' at a temperature of 49-104 °C and the flow rate is 7.2-13.1 tons/hour at a pressure of 20-70 psig. The injection pump 311 is a high pressure feed pump with a flow rate of ~2 gpm at 300 psig, although other flow rates and pressures are possible. The injection pump 311 increases the feedstock feed to the heat exchanger 312 to approximately 20.3 tons/hour and the pressure to 200-260 psig.

Heat exchanger 312 increases the temperature of the feedstock to 413-430 °C by heating it with hotter components, such as hot products from the following parts of system 300'. The feedstock is fed to process heater 314, where it is further heated to a temperature of 465-500 °C depending on the characteristics of the feedstock.

As in the previous embodiment, the process heater 314 is an inductive heating coil or an immersion coil. It is fed from any suitable source 316, for example, a transformer or other device that delivers 1 MW of power. The source 316 can have several electrical connections to the process heater 314 and / or its coils 315. The connections in the coils can be located at regular intervals, for example, every three turns of the coil 315. Any other design is possible that ensures the supply of sufficient power to the process heater 314. The process heater 314 is equipped with a coil 315 of sufficient length. The feedstock is located in the coil and is heated to the desired temperature. Then it leaves the process heater 314 through the outlet line of the reactor 317.

The outlet line of the reactor 317 is in fluid communication with the first vessel 321' of the reactor 320'. This first vessel 321' may be a reactor with a flow with a structured core, as described earlier. The heated substance enters the first vessel 321' from the bottom and rises upward at a nearly uniform speed, avoiding turbulence and maintaining the same flow rate for all molecules of the heated substance. The first vessel 321' is under a pressure of 100-200 psig, preferably in the range of 100-175 psig, and is also filled with an inert gas 318 (such as nitrogen or argon) to limit the oxygen content in the first vessel 321' taking into account the high temperatures. The heated substance at the inlet to the first vessel 321' preferably has a temperature of 482.2-496 °C. As it moves along the first container 321', the substance loses some heat, cooling by 20-30 °C.

In embodiments of the invention, the first container 321' may comprise a separation zone 328 occupying a certain portion of the container 321', preferably near the top thereof. The separation zone 328 has a larger diameter and, therefore, a larger internal volume than the rest of the first container 321'. In embodiments of the invention, this additional space allows vapors, including small hydrocarbon molecules that were unable to form pitch 150, 250 during its production, to separate from the liquid and be removed from the container as a product designated as LC1 322'. The removal limits undesirable foaming, leading to the appearance of turbulent flow. The vapors LC1 322' rise to the top of the first container 321'. The temperature of the substance LC1 322' is 437.8-443.3 °C. It is removed from the first container 321' at a point located above the separation zone 328. The removed vapors LC1 322' are directed to a condenser, where they are condensed and/or thermally destroyed in a gas cleaning device.

The LC2 substance 333 is formed in the separation zone 328 in the form of foam and/or vapor. The LC2 substance 333 contains non-condensable gases. It can be withdrawn from the separation zone 328 of the first container 321' and fed to the second container 324'. In a preferred embodiment of the invention, additional light molecular chains LC2 333 are fed to the second container 324' at its midpoint (along the length). The liquid heated substance from the first container 321' is also fed to the second container 324' via the inter-reactor line 323' when the level of the heated substance in the first container 321' reaches a certain value. The heated substance from the first container 321' is mixed with the LC2 substance 333 in the second container 324', creating an additional flow with a structural core flowing through the second container 324'. The second container 324' is also filled with neutral gas 318, which may have the same or different composition as the gas in the first container 321'. In the second container 324', the heated substance is at practically the same temperature and pressure as in the first container 321', although certain losses are possible when the heated substance passes through the reactor 320'.

The vapors that collect in the upper portion of the second vessel 324' are removed as light molecular chains LC3 340, which are subsequently allowed to mix with the LC1 substance 322' and condense back into a liquid. The mixed LC1 322' and LC3 340 substances contain high boiling compounds that can be separated and purified at a refinery for sale or further use. The remainder of the LC1 322' and LC3 340 substances can be thermally destroyed as discussed above. The bottoms from the second vessel 324' contain the thermally treated substance, which is then sent back to the heat exchanger 312 via the outlet line of the reactor 325 for cooling. After cooling, the heat-treated substance is returned to the pitch production system 100, 100', 100", 200', 200", 200" (depending on the specific embodiment) with the above-mentioned substance injection points. Alternatively, the heat-treated substance is fed from the reactor 320' back to the column C1 or cooled by traditional methods.

The holding time during the heat treatment using the second embodiment of the system 300' depends at least on the temperature. For example, if the coal tar is heated to a temperature of 482.2-500 °C, the holding time during the heat treatment process 200' is 10-20 minutes, whereas at a temperature of ~537.8 °C, the holding time can be ~5 minutes. At lower reaction temperatures, the holding time can be as long as 60 minutes. These are just a few non-limiting examples.

It has been shown that with a single passage of the starting material through the heat treatment subsystem 300' proposed in the present invention, the pitch yield increases by 2.5 times, reaching ~40% compared to ~15% without heat treatment. Additional pitch 150, 250 is also obtained by re-passing the starting material through the heat treatment subsystem 300' at least once or several times. However, there is a risk of mesophase formation when the heat load is increased. Therefore, in some embodiments, it is useful or even necessary to subject the heat treatment product to distillation in order to remove the formed pitch 150, 250 so that it does not pass through the heat treatment subsystem 300' again. This will limit or prevent the formation of mesophase in the pitch 150, 250.

Unlike the 102 coal tar feedstock, 203 decantation has a greater variation in composition and concentration from batch to batch. This further complicates the relationships between temperature, holding time, and pressure. However, the desired pitch parameters (coke number greater than 47% and mesophase less than 0.7%) determine the limits of acceptable pitch yield increase, since values that are too high or too low result in pitch with either insufficient coke number or too much mesophase. Given these limitations, the relationship between holding time and temperature in decantation heat treatment is described by the following equations:

,

where 25 is the percentage increase in yield with the introduction of heat treatment (depends on the required pitch parameters: coke number of at least 47% and mesophase content of no more than 0.7%); T _r is the reaction temperature in degrees Celsius; T _c = 653 and R _t is the holding time in minutes. The first factor of 0.1 corresponds to the percentage increase in pitch yield for each degree Fahrenheit increase in temperature, and the second factor of 0.1 corresponds to the percentage increase in pitch yield with each additional minute of holding time. Depending on the limitations of a particular system, the above equation can be expressed in terms of the holding time R _t or the reaction temperature T _r as:

,

.

In preferred embodiments, during the thermal treatment of decantation 203, the reaction temperature T _r is in the range of 454-483 °C, and the holding time R _t is from 3 to 25 minutes. Interestingly, the 25% yield increase corresponding to the constants "25" and "250" in the above equations also applies to decantation 203 feedstock with a specific gravity of -5 to 0 API degrees. An increase in yield above or below this value results in either an unacceptable mesophase content or a low coke number. As is common practice in the oil industry, the specific gravity in API degrees is related to the normal specific gravity by the following relationship:

.

Therefore, although a different specific gravity of the decantate 203 in the production of petroleum pitch 200" may require a change in the operating parameters of the 200 system, the above equation applies equally well to different specific gravities of the starting decantate 203.

The above equation for predicting reaction temperature and duration allows the calculation of the approximate operating parameter ranges shown in Table 8 for the thermal treatment process of petroleum distillates using the thermal treatment subsystem 300' disclosed herein at a medium gradient in the reactor:

Table 8.

Reaction temperature
(min) Temperature
(°C) Pitch output
(mass %) Coke number
(mass %) Total mesophase content 1 496 54 47.3 0.9 2.5 482 47.5 49.4 0.6 5 482 53.7 49.2 0.4 10 482 54.3 50.5 0.5 10 468 43 47.3 0.1 10 477 53.7 48.0 0.2 20 459 44.7 47.7 0.6 20 460 43.8 49.4 0.3 20 463 46.4 47.8 0.6 20 459 47.5 50.1 0.5 20 468 40.0 47.6 0,0 20 471 40.0 50.0 0.7

These and other features of the preferred embodiments of the invention are further illustrated by the following non-limiting examples.

EXAMPLES

The following examples present experimental data obtained by measuring and/or testing certain parameters of the described pitch production systems and/or heat treatment subsystems. Specific embodiments of the invention are mentioned as necessary.

EXAMPLE 1. Determining the rate of removal of heavy distillates

A series of experiments were conducted to determine the maximum rate of withdrawal of heavy distillate 141 from the third column C3 in the first embodiment of the coal tar pitch production system 100 discussed above without reducing its overall productivity. Heat treatment of the heavy distillate 141 is important for the separation of benzo(a)pyrene, as well as for maintaining a higher softening temperature of the resulting pitch 150, for example, ~130 °C when determined on a Mettler apparatus.

If the goal is to increase pitch yield by 5%, then the flow rate in Heat Treatment Subsystem 300 is calculated as follows. Assuming an annual pitch production of ~300,000 t/yr, 5% of this figure is ~15,000 t/yr, i.e. additional pitch will be required. The figure of 15,000 t/yr divided by the assumed yield of 30% is ~50,000 t/yr, and at 300 days of operation per year gives 166 t/day, which corresponds to the flow rate in Heat Treatment Subsystem 300 of 7 t/hr, which is necessary for the increase in pitch yield by 5%.

The coal tar pitch system 100 can typically operate at a pitch throughput of ~31.5 t/h. To subject the heavy distillate 141 to the heat treatment process 300 at a rate of ~7 t/h would require an equivalent reduction in pitch throughput. Tests were conducted to determine whether the required reduction in pitch throughput could be achieved to increase pitch yield without compromising the existing process.

During the test, the withdrawal of heavy distillate 141 was simulated by partially closing the valve in the heavy distillate line 142 from the third column C3 with different degrees of overlap. Partial flow overlap simulated the withdrawal of petroleum product. The tests were conducted at four different valve positions with different percentages of overlap. First, the overlap was 55% (normal operating mode), and then - 35, 30 and 25%. At each valve position, the flow rate was measured in order to control the volume of simulated withdrawal of heavy distillate 141. To control the effect on the system, the heat load was measured, and the quality control of the pitch manufacturing process was carried out by measuring the softening temperature of the finished pitch (on a Mettler apparatus). Other parameters were also measured for control. To better understand the effect, the degree of separation, the benzo(a)pyrene content and the distillation range were also measured. The test results are summarized in Table 9.

Table 9.

Flow valve closing [%] 55 35 30 25 Heavy distillate consumption [m/h] 31.5 22.4 18.8 10.8 Heavy distillate consumption 6.5 6.5 6.3 6.5 Thermal load E3 [MW] 1.32 1.20 1.09 0.70 Cooling capacity of heavy distillate zone [MW] 1.04 0.85 0.72 0.27 Temperature of heavy distillates collection tray [°C] 279.4 288.2 293.7 301.4 Flash evaporation pressure [mbar abs.] 112.5 116.7 114.4 112.6 Temperature of the second collection plate of middle distillate [°C] 207.3 211.7 214.8 220.8 Second control valve in the middle distillate line 100
(cold) 100
(cold) 100
(cold) 100
(cold) Pressure at the top of the column [mbar(abs.)] 73.5 74.2 75.9 78.0 Yield of first middle distillate [-] 6.9 7.2 8.4 10.0 Heavy Distillate Collection Plate Level [%] 80.52 77,74 78.48 70.42 Mettler temperature [°C] 128.0 130.3 127.8 127.7 Benzo(a)pyrene [ppm] - - 3.69 3.95 Distillation temperature range [0-300 °C] - - 1 1 Distillation temperature range [0-355 °C] - - 76 68

The results show that the consumption of heavy distillate 141 in the heat treatment can be reduced while maintaining the normal operation of the pitch production system 100. This is evidenced by the effect of the reduction in consumption on the heat load. At the flow shutoff of 55%, some normal variation in parameters occurs, although this is the standard operating mode. This is evident from the temperature of the second middle distillate, which differs from the normal temperature of 210 °C.

Despite maintaining normal operation, it should be noted that the second middle distillate cooling circuit was loaded to its maximum. This allowed the temperature of the second middle distillate in the tray to increase during the experiment, which led to an increase in the yield of the first middle distillate. Achieving maximum cooling of the second middle distillate is difficult, especially when additional power for cooling is taken at the expense of reducing the flow rate of heavy distillate.

In general, both temperature monitoring and laboratory testing indicate that the column is not being cooled sufficiently. This effect is amplified when additional flow is removed from the loop. Therefore, additional cooling may be required to eliminate the loss in cooling capacity or reduce energy consumption.

Overall, the results show that a flow rate of 7 t/h in the heat treatment process is possible, but additional cooling may be required to produce low PAH creosote.

EXAMPLE 2. Determining reactor temperatures

To further design the full-scale heat treatment subsystems 300, a number of commonly encountered conditions were analyzed. In particular, the temperature of the process heater 314 was evaluated. Temperatures of 420, 445, 471, 497, and 522 °C were considered. The lower limit of this estimate is based on preliminary autoclaving results that showed limited reactivity. The upper limit is based on the measured autoignition temperature of heavy distillate, equal to 542 °C. For safety reasons, the maximum reactor temperature is limited to 522 °C.

Previous experiments have shown that the heavy distillate can be exposed to 550°C for 5.2 min without mesophase or coke formation. The results of previous experiments with long holding times are presented in Table 10.

Table 10.

Temperature (°C) Holding time (hour) Yield, % (softening point 115°C) 395 4 15.7 401 2 10.6 420 5 26.7

Based on the previous data, kinetic modeling was performed at a heavy distillate flow rate of 7 t/h and a desired total pitch yield of 30%, as specified in Example 1. The results of the kinetic calculations are presented in Table 11.

Table 11.

Reactor outlet temperature 420 445 471 497 522 Reactor volume [ ^m3 ] 17.9 8.2 3.71 1.74 0.82 Holding time [min] 142.7 64.3 28.6 13.1 6.1 Required energy consumption [kW] 360 374 376 391 383

The maximum holding time under laboratory conditions was 5.2 min. As can be seen from Table 11, most of the calculated results significantly exceed this value. Therefore, such kinetic calculations may overestimate the reaction rates.

EXAMPLE 3. Tests at different temperatures and holding times during heat treatment. Raw material: coal tar

To evaluate the feasibility of heat treatment of heavy distillate in pitch production, tests were conducted. Initial experiments were conducted at temperatures ranging from 365 to 510 °C and holding times ranging from 4.5 minutes to 2 hours. From the results of the experiments, a reaction rate constant was obtained. Two more experiments were conducted in the adiabatic mode to test whether the reaction was endothermic. The reactor was carefully insulated to eliminate the influence of the furnace heat and to consider only the heat released by the heavy distillate in the reactor. The experiments were conducted in a reactor with a structured core flow.

All experiments were conducted under identical conditions. The heavy distillate was placed in a feed tank and pumped through the reactor with a rotary pump. The reactor was installed in a furnace with a preheater. Reactors of different capacities were used in the experiments - from 299 to 330 ml. The heavy distillate was pumped through the reactor to achieve a specified holding time at a specified temperature. After the furnace, the heavy distillate passed through a cooling coil to reduce the temperature before being fed to either a waste tank or a sample collection tank. Samples were collected after the temperature in the reactor had stabilized. In most experiments, samples weighing 1000 g were collected.

All tubes were heated to maintain the heavy distillate as a liquid throughout the experiment. The feed tank was maintained at 100 °C, the cooling coil was maintained at 180 °C, and the sample and waste collection vessels were maintained at 150 °C. Temperature sensors were installed at several locations on the heater and reactor to monitor the temperature profile of the heavy distillate. A nitrogen purge was used during the experiments to maintain a neutral atmosphere. The experiments were conducted at elevated pressure to compensate for the vapor pressure of the heavy distillate. Typical pressures were ~100 psig.

The oil products after heat treatment had to be distilled to determine the yield of pitch in a particular sample. Vacuum distillation was used for this purpose. It was carried out in a round-bottomed flask. The sample weight was ~400 g. A 1 m long Vigreux column was used as a distillation column. All samples were distilled under full vacuum. At the beginning of the distillation, the temperature of the bottoms was 250 °C, and then gradually increased until enough product was distilled to obtain the predicted volume of pitch. If the pitch did not fit into the required melting point range of 105-130 °C, another distillation was carried out. During the second distillation, the temperature of the bottoms was increased or decreased to distill more or less distillate in order to obtain a pitch with a higher or lower melting point, respectively.

A series of analyses were performed on the heat-treated petroleum products, pitch and distillate. The heat-treated product was analyzed by Fourier transform infrared (FTIR) spectroscopy to calculate the aromatic hydrocarbon content. The melting point of the pitch was measured. The acceptable range was 105-130 °C. The content of insoluble quinolines was measured and should be minimal. In addition, the pitch was analyzed for benzo(a)pyrene content. The distillate was analyzed by gas chromatography (GC) to calculate the conversion of compounds in the heavy distillate and the reaction rate constant. A portion of the product was also analyzed by gas chromatography mass spectroscopy (GCMS) to allow comparison with the GC results.

The test data are summarized in Table 12.

Table 12.

Experiment F18024 F18025 F18027 F18028 F18029 F18031 F18032 F18033 F18034 Pitch yield, % 13.83 16.55 38.31 37.23 23.94 17.79 30.45 45.24 55.01 Mettler temperature [°C] 103.35 126.35 125.8 119.7 128.85 116.9 119.25 121.85 118.8 Content of insoluble quinolines, % 0.1 0.08 0.11 0,00 0.513 0.22 0.84 0.2 0.31 Adjusted pitch yield 11.34 18.97 40.62 38.23 26.90 18.20 31,36 46.70 55.82 Reactor volume [ml] 205.89 205.89 205.89 139.52 139.52 139.52 205.89 205.89 205.89 Average temperature [°C] 479.2 501.5 539.8 538,0 521.8 499.7 519.8 551.2 562.7 Holding time [min] 4.7 4.5 4.4 2.9 3.0 3.1 4.5 4.2 4.1

Experiment F19008 F19012 F19015 F19016 Pitch yield, % 27.6 24.54 19.13 30.42 Mettler temperature [°C] 111.35 129.85 119.9 118.7 Content of insoluble quinolines, % 0.19 0 Adjusted pitch yield 26.82 27.71 20.18 31,21 Reactor volume [ml] 67 327,0 326.7 326.7 Average temperature [°C] 528 465.2 488.8 514.4 Holding time [min] 1.78 37.8 8.6 8.2

The data show an increase in pitch yield at the temperatures and holding times tested, confirming that heat treatment of heavy distillate can increase pitch yield.

The results of adiabatic experiments (which tested whether the reaction was endothermic) are given in Table 13.

Table 13.

Experiment F19020 F19021 Reactor inlet temperature [°C] 482 499.8 Temperature in the middle of the reactor [°C] 483 499.8 Reactor outlet temperature [°C] 483.75 500.8

EXAMPLE 4. Testing at different temperatures and holding times. Petroleum products

In laboratory tests, the decantate obtained from the petroleum product was heat treated at various temperatures and holding times. The decantate was held at elevated temperature in an autoclave under a constant pressure of 200 psig. A short delay was introduced for the time required to heat the decantate to the desired temperature. After exposure to the desired temperature for a specified time, the heat-treated product was rapidly cooled to stop the thermal effect and limit the formation of mesophase. The pitch formed during the heat treatment was separated by distillation with the removal of unreacted decantate. The resulting pitch was analyzed for coke number and mesophase content. The results of the experiments are summarized in Table 14.

Table 14.

Holding time at temperature (min) Delay (min) Heat treatment time (min) Temperature (°C) Pitch yield (wt.%) Coke number (mass %) Total mesophase content 0 1 1 496 54 47.3 0.9 2.5 2 4.5 482 47.5 49.4 0.6 5 2 7 482 53.7 49.2 0.4 10 2 12 482 54.3 50.5 0.5 10 2 12 468 43 47.3 0.1 10 2 12 477 53.7 48.0 0.2 20 5 25 459 44.7 47.7 0.6 20 5 25 460 43.8 49.4 0.3 20 2 22 463 46.4 47.8 0.6 20 5 25 459 47.5 50.1 0.5

In all experiments, pitch of acceptable quality was obtained with a coke number of over 47% and a mesophase content of less than 0.7%.

Since numerous minor modifications and changes can be made to the preferred embodiments of the invention, it is intended that all information set forth in the preceding description and shown in the drawings is illustrative and not limiting. The scope of the invention is defined by the appended claims and their legal equivalents.

Claims (86)

1. A method for producing pitch from a starting material, wherein the starting material comprises one of the following materials: (i) petroleum decantate, (ii) heavy coal tar distillate; Moreover, this method includes the following steps: feeding said source material in a fluid liquid phase into a heat-conducting portion of a channel at least partially made of a heat-conducting material that facilitates heat transfer; controlled application of heat to said heat-conducting portion of said channel containing said feedstock material to raise the temperature of said feedstock material to 459-535°C at a pressure of at least 46 psig so as to maintain said feedstock material in a liquid phase; maintaining a substantially uniform flow of said feedstock material through at least a portion of said heat-conducting portion of said channel at a substantially constant temperature for a time sufficient to convert a portion of said feedstock material into pitch while limiting the formation of mesophase to 0.7% by weight in the combined flow; reducing the temperature of said combined stream to 275-385 °C; and separating said pitch from said combined stream and obtaining finished pitch. 2. The method of claim 1, wherein the feedstock is selected from the group consisting of: (i) petroleum decantate and (ii) heavy coal tar distillate; and wherein said separation step comprises separating said pitch from said combined stream and obtaining finished pitch in the following proportions: (i) at least 25% by weight of said petroleum decantate; (ii) at least 15% by weight of said heavy coal tar distillate. 3. The method according to claim 1, characterized in that the starting material is a heavy distillate based on coal tar, which is heated to a temperature of 475-510 °C at a pressure of 46-155 psi (g). 4. The method according to paragraph 3, characterized in that: a) the said practically uniform flow at the said practically constant temperature is maintained for 3.0-49.2 minutes, or b) the pitch yield is in the range from 15 to 45% by weight, or c) said temperature is about 475°C, said pressure is about 46.2 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 49.2 minutes to produce about 45% by weight of pitch, or (d) said temperature is about 510°C, said pressure is about 155 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 3 minutes to obtain about 15% by weight of pitch. 5. The method according to claim 1, characterized in that the starting material is a heavy distillate based on coal tar, which is heated to a temperature of 490-510 °C at a pressure of 60.7-126 psi (g). 6. The method according to paragraph 5, characterized in that: a) the said practically uniform flow at the said practically constant temperature is maintained for 4.3-23.6 minutes, or b) the pitch yield is from 20 to 40% by weight, or c) said temperature is about 490°C, said pressure is about 60.7 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 23.6 minutes to produce about 40% by weight of pitch, or (d) said temperature is about 510°C, said pressure is about 126 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 4.3 minutes to obtain about 20% by weight of pitch. 7. The method according to claim 1, characterized in that the starting material is a heavy distillate based on coal tar, which is heated to a temperature of 495-510 °C at a pressure of 65.1-111.5 psi (g). 8. The method according to paragraph 7, characterized in that: a) the said practically uniform flow at the said practically constant temperature is maintained for 5.7-16.3 minutes; or b) the pitch yield is in the range of 25-35% by weight, or c) said temperature is about 495°C, said pressure is about 65.1 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 16.3 minutes to produce about 35% by weight of pitch, or (d) said temperature is about 510°C, said pressure is about 111.5 psig, said substantially uniform flow is maintained at said substantially constant temperature for about 5.7 minutes to obtain about 25% by weight of pitch. 9. The method of claim 1, wherein said starting material is a heavy coal tar distillate that is heated to a temperature of about 500°C at a pressure of about 83.9 psig. 10. The method of claim 9, wherein said substantially uniform flow is maintained at said substantially constant temperature for approximately 7.4 minutes to obtain approximately 30% by weight of pitch yield. 11. The method of claim 1, wherein the starting material is a decantation of petroleum products having an API gravity of -5 to 0, and the starting material is under a pressure of 80-300 psi (g) applied at a substantially constant temperature for a period the duration of which is calculated using the following equation: , where T _r is the reaction temperature in degrees Celsius; T _c = 653, R _t is the holding time in minutes, which makes it possible to increase the pitch yield by at least 25% by weight, and said pitch has a coke number of at least 47% by weight. 12. The method according to claim 1, characterized in that the starting material is a decantation of petroleum products, which is heated to a temperature of 459-496 °C at a pressure of 80-300 psi (excess). 13. The method according to item 12, characterized in that a) the said practically uniform flow at the said practically constant temperature is maintained for 1-25 minutes, or b) the pitch yield is in the range of 40-54.3% by weight with a coke number from 47.3 to 50.5% by weight, or c) said temperature is about 496 °C, said substantially uniform flow is maintained at said substantially constant temperature for about 1 minute to produce about 54 wt.% pitch with a coke value of about 47.3 wt.%, or d) said temperature is in the range of 468-482 °C, said substantially uniform flow is maintained at said substantially constant temperature for about 10 minutes to obtain a pitch in the range of 43-54.3 wt.% with a coke number of 47.3-50.5 wt.%, or d) said temperature is in the range of 459-471 °C, said substantially uniform flow is maintained at said substantially constant temperature for about 20 minutes to obtain a pitch in the range of 40-47.5 wt.% with a coke number of 47.7-50.1 wt.%. 14. The method according to claim 1, characterized in that said channel additionally contains a heat-conducting section through which said source material flows in the form of a turbulent flow, and a reactor section in which the flow of said source material flows practically uniformly. 15. The method according to claim 13, characterized in that the temperature of the source material is increased in the heat-conducting section and maintained almost constant in the reactor section. 16. The method according to claim 1, characterized in that it additionally includes the step of heating the source material before introducing it into the channel. 17. The method according to paragraph 16, characterized in that the said heating stage and the said temperature reduction stage are carried out simultaneously in a common heat exchanger. 18. The method according to paragraph 1, characterized in that the separation of said portion of the pitch from said combined stream is carried out by distillation. 19. A continuous method for producing pitch from a source material, comprising the steps of recycling the combined stream obtained by the method according to item 1, after separating a portion of the pitch, as the specified source material. 20. A finished pitch with a reduced content of insoluble quinoline (QI), obtained by the method according to any of paragraphs 1-19, wherein said finished pitch is characterized by: softening temperature in the range from 100 to 140 °C; content of insoluble quinoline (QI) not more than 0.84% by weight; mesophase content of no more than 0.7% by weight based on the total weight of the finished pitch; and coke number above 47%. 21. A heat treatment subsystem for producing pitch from a feedstock, wherein the feedstock comprises one of the following materials: (i) petroleum decantate, (ii) heavy coal tar distillate; Moreover, this system contains: pump; a channel in fluid communication with said pump, said channel at least partially consisting of a heat-conducting portion made of a heat-conducting material that facilitates heat transfer and having at least one separate section, said section having: first lower end, a liquid inlet located at said first lower end and in fluid communication with said pump, second top end, a vapor phase outlet located near said second upper end, an intermediate section between said first lower end and said second upper end, and a liquid outlet located between said liquid inlet and said vapor phase outlet and located within said intermediate section, defining within said channel a vapor space located between said liquid outlet and said second upper end, and a liquid space located between said liquid outlet and said first lower end; wherein said heat-conducting portion of said channel has a maximum temperature of 459-535 °C and a maximum pressure of at least 46 psig, and said intermediate portion of said channel has dimensions and shape that enable the pump to maintain a continuous and substantially uniform upward flow of said incoming liquid stream at a substantially constant temperature in said liquid space for a period of time sufficient to convert at least a portion of said feedstock material into pitch, while limiting mesophase formation to a level of no more than 0.7 wt. % in the combined stream, to produce finished pitch. 22. The heat treatment subsystem of claim 21, wherein the starting material is selected from the group consisting of: (i) petroleum decantate and (ii) heavy coal tar distillate; and wherein the finished pitch is obtained in the following proportions: (i) at least 25% of said petroleum decantate; (ii) at least 15% of said heavy coal tar distillate. 23. The heat treatment subsystem according to item 21, characterized in that said channel additionally contains a reactor section. 24. A heat treatment subsystem according to paragraph 21 or 23, characterized in that said heat-conducting part additionally contains a heating section having dimensions that make it possible to create a turbulent flow of the source material. 25. The heat treatment subsystem of claim 24, wherein the heating section is characterized in that it: i) has inductive heating and/or ii) is an elongated coil. 26. The heat treatment subsystem of claim 23, wherein said reactor section further comprises at least one holding vessel for maintaining (i) the feedstock at a substantially constant temperature and/or (ii) for maintaining a substantially uniform flow of the feedstock. 27. A heat treatment subsystem according to paragraph 23 or 24, characterized in that said reactor section additionally contains an inert atmosphere. 28. The heat treatment subsystem according to claim 21, characterized in that it contains a heat exchanger for transferring thermal energy from said combined flow to said source material before it is introduced into said channel. 29. The heat treatment subsystem according to paragraph 23 or 26, characterized in that said reactor section contains a first container and a second container, wherein the first container has a larger volume than the second container. 30. The heat treatment subsystem according to paragraph 29, characterized in that the second container has minimal dimensions. 31. The heat treatment subsystem according to item 26, characterized in that said holding container has an elongated shape with a length to diameter ratio of 10:1 or more. 32. A heat treatment subsystem according to paragraph 21, characterized in that the said practically constant temperature is within the deviation range from plus 30 °C to minus 30 °C. 33. The heat treatment subsystem according to paragraph 32, characterized in that the said practically constant temperature is within the deviation limits of (i) from plus 10 °C to minus 10 °C or (ii) from plus 5 °C to minus 5 °C. 34. The heat treatment subsystem according to paragraph 27, characterized in that said reactor section contains a first container and a second container, wherein the first container has a larger volume than the second container. 35. The heat treatment subsystem according to paragraph 34, characterized in that the second container has minimal dimensions. 36. A distillation system for producing pitch with a mesophase content of no more than 0.7% by weight from a starting material of the following options: (i) a decantation water from petroleum products and (ii) a heavy distillate of coal tar, wherein this distillation system comprises at least one distillation column, and this distillation system is designed to produce said pitch with the achievement of (i) an increase in the pitch yield by at least 25% by weight based on the decantation water from petroleum products or (ii) a pitch yield of at least 15% by weight based on the heavy distillate of coal tar, wherein this distillation system additionally comprises: a heat treatment subsystem according to any one of paragraphs 21-35, comprising: (iii) a heat treatment subsystem for receiving and processing said petroleum product decantation and producing pitch therefrom; or (iv) a heat treatment subsystem in fluid communication with said at least one distillation column system for receiving and processing said heavy coal tar distillate and producing pitch therefrom; and said at least one distillation column: (v) is in fluid communication with said heat treatment subsystem for receiving and fractionating said heat treated decantation effluent into individual fractions including pitch, or (vi) is designed to receive and fractionate coal tar into component fractions including pitch and heavy distillate based on coal tar. 37. The distillation system according to claim 36, characterized in that it additionally contains a plurality of distillation columns. 38. The distillation system according to claim 37, characterized in that at least one of said distillation columns (i) is a flash distillation column in the case of using decantation from petroleum products or heavy coal tar distillate or (ii) further comprises a dehydrator in the case of using heavy coal tar distillate. 39. The distillation system of claim 36, wherein (i) in the case of using a petroleum decantate, said decantate is recycled to the heat treatment subsystem after removing pitch in the distillation column, or (ii) in the case of using a heavy coal tar distillate, said heavy coal tar distillate is recycled to said heat treatment subsystem after removing said pitch in said distillation column. 40. The distillation system of claim 37, wherein (i) in the case of using a petroleum decantate, said decantate is recycled to the heat treatment subsystem after removing pitch in the distillation column, or (ii) in the case of using a heavy coal tar distillate, said heavy coal tar distillate is recycled to said heat treatment subsystem after removing said pitch in said distillation column. 41. The distillation system of claim 38, wherein (i) in the case of using a petroleum decantate, said decantate is recycled to the heat treatment subsystem after removing pitch in the distillation column, or (ii) in the case of using a heavy coal tar distillate, said heavy coal tar distillate is recycled to said heat treatment subsystem after removing said pitch in said distillation column.

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