WO2015038023A1 - Method for producing a modified coking additive by means of delayed coking of petroleum residues (variants) - Google Patents

Abstract

The group of inventions relates to the field of petroleum refining, and specifically to producing, by means of delayed coking, petroleum coke containing more than 15% and less than 25% volatile substances for use as a coking additive in a coal coking charge. The method consists in heating a primary raw material and feeding same into an external section of a fractionating column for mixing with heavy gas oil used as a recycled material, forming a secondary raw material, heating same in a reaction heating furnace, and feeding same into a coking chamber where a coking additive and vapor-liquid coking products are formed. The latter are fractionated in the fractionating column, forming gas, petroleum, light and heavy gas oils and a coking distillation residue. According to a first variant, calcium oxide or calcium hydroxide is added as a modifier to the secondary raw material before same is fed into the coking chamber, the modifier being pre-mixed with heavy gas oil at a ratio of (25-35):(65-75). According to a second variant, calcium oxide or calcium hydroxide is added as a modifier to the distillation residue, and is pre-mixed with heavy gas oil at a ratio of (25-35):(65-75), after which the distillation residue is either mixed with the secondary raw material before being fed into the coking chamber, or is fed directly into the coking chamber. The contents of the modifier which is fed into the coking chamber are, in both variants, 0.5-10.0 percent by mass of the initial raw material.

Description

A method of obtaining additives modified coking delayed coking of oil residues (Options) The claimed group of inventions relates to the field of oil refining, in particular, to obtain oil coke delayed coking with a volatile content of more than 15% and less than 25% for use as a coking additive in the charge of coking coal . A known method of producing petroleum coke by delayed coking of oil residues, which consists in the fact that the feedstock is heated to a temperature of 300-350 ° C, fed to the remote section of the distillation column for mixing with the recirculate and the formation of secondary raw materials, heated secondary raw materials in a reaction-heating furnace to temperature 480-505 ° C and served in a coking chamber, where coke and vapor-liquid coking products are formed, fractionate the latter in a distillation column with the formation of gas, gasoline, light and heavy th gas oil and bottoms coking residue. As the recirculate using the bottom residue of coking (RF Patent for the invention изобретение "2209826, CL 10B 55/00, publ. 2003). The disadvantage of this method is to obtain the target product with a low content of volatile substances and a high sulfur content, which is unacceptable for use as a coking additive in the charge of coking coal in the production of blast furnace coke. Closest to both variants of the claimed objects is a method for producing additives coking delayed coking oil residues, including the supply of raw materials to the coking chamber with a temperature of 450-470 ° C, its coking for 14-24 hours. with a recirculation coefficient of not more than 1, 2 with the formation of a coking additive and steam-liquid bone products of coking, fractionation of the latter in a distillation column with the formation of gas, gasoline, light and heavy gas oils, and still bottoms of coking. Also, as in the above analogue, before being fed into the coking chamber, the feedstock is heated to a temperature of 300-350 ° C, fed to the remote section of the distillation column for mixing with the recirculate and forming secondary raw materials (RF Patent for the invention N ° 2400518, class С10В 55/00, publ. 2010). The disadvantage of this method is that when coking sulfurous oil residues, a coking additive is formed with a high sulfur content in organic form, which subsequently, falling into metallurgical coke, negatively affects the quality of cast iron, as well as the quality of steel obtained during the conversion of sulfur cast iron (steel becomes a breaker). To neutralize the negative impact of organic sulfur contained in ore, as well as in metallurgical coke, used as a fuel and a reducing agent in blast furnace production, fluxes are added to the charge during the smelting of pig iron, including calcium oxide in the form of lime. In this case, calcium oxides interact with sulfur contained in metallurgical coke, convert it to an inorganic form by the reaction:

 CaO + S + C -> CaS j + CO †

 slag

and are displayed as slag. The higher the sulfur content in metallurgical coke, the greater the amount of flux that follows add to the mixture, since the desulfurization process is advisable to carry out with an excess of calcium oxide in the slag. The need to introduce a large amount of flux during the smelting of pig iron overloads the blast furnace, reducing the productivity of cast iron. In the literature, laboratory studies are published under stationary conditions similar to the coking process in cubes, on the effect of alkaline additives on sulfurous coking raw materials. Moreover, most of the organic sulfur in the coking feedstock interacts with potassium hydroxide and converts it into a water-soluble salt, which ensures a decrease in sulfur content (N. S. Kazanskaya, M.E. Kazakov, E.V. Smidovich, E.R. Sarkisyants “On the properties of petroleum coke obtained in the presence of potassium oxide hydrates.” - Proceedings of the Universities Oil and Gas, 1974, No. 6, p. 55-58). In this case, a significant amount of potassium hydroxide is introduced, and this requires subsequent washing of the obtained coke with water to remove excess alkali. The claimed group of inventions is aimed at obtaining delayed coking additives coking with a low sulfur content in organic form. In the first embodiment of the proposed method, this is achieved by the fact that in the method for producing a coking additive by delayed coking of oil residues, including heating the feedstock, feeding it to the remote section of the distillation column for mixing with heavy gas oil as recirculate and forming secondary feedstock, heating the secondary feedstock in a reaction -heating furnace and feeding into the coking chamber, where a coking additive and vapor-liquid coking products are formed, fractionation of the latter in a distillation column with the formation of gas, gasoline, light and heavy gas oil and bottoms coking residue, according to the invention, the secondary raw materials before being fed into the coking chamber are mixed with a modifier - oxide (CaO) and / or calcium hydroxide (Ca (OH) ₂ ) before and after the reaction-heating furnace, while the content the modifier supplied to the coking chamber is 0.5-10.0% by weight of the feedstock, and the modifier is pre-mixed with heavy gas oil in the ratio (25-35) :( 65-75). Secondary raw materials with a modifier are mixed before and after the reaction-heating furnace. In the second embodiment of the proposed method, the technical result is achieved in that in the method for producing a coking additive by delayed coking of oil residues, including heating the feedstock, feeding it to the remote section of the distillation column for mixing with heavy gas oil as recirculate and forming secondary feedstock, heating the secondary feedstock in a reaction-heating furnace and feeding into the coking chamber, where a coking additive and vapor-liquid coking products are formed, fractionation of the latter into rectification according to the invention, calcium oxide and / or calcium hydroxide is added to the bottoms column with the formation of gas, gasoline, light and heavy gas oil and bottoms coking residue according to the invention as a modifier pre-mixed with heavy gas oil in the ratio (25-35) :( 65-75 ), after which the bottom residue is either mixed before feeding into the coking chamber with secondary raw materials, or fed directly into the coking chamber, while the content of the modifier supplied to the coking chamber is 0.5-10.0% by weight of the feedstock. In both variants of the proposed method, the secondary raw materials are heated in a reaction-heating furnace to a temperature of 450-490 ° C. In both variants of the proposed method for regulating the quality of heavy coking gas oil and bottoms withdrawn from the distillation column, the method includes supplying heavy gas oil irrigation circulating to the bottom of the column, while the quality and quantity of heavy gas oil and bottoms are controlled by changing the amount of irrigation on the plates of the column. In both variants of the proposed method, it is advisable to spray an antifoam additive in the upper part of the coking chamber in order to reduce the foaming intensity during coking of raw materials in the presence of calcium oxide and / or hydroxide. The supply of the modifier to the coking feedstock together with the secondary feedstock and / or bottoms will reduce the organic sulfur content of the resulting modified coking additive due to the interaction of the organic sulfur compound contained in the feedstock with calcium oxide and / or calcium hydroxide to form an inorganic inactive form of sulfur compound. Moreover, the addition of calcium oxide and / or hydroxide of less than 0.5% to the feedstock is impractical due to a slight decrease in the sulfur content of the coking additive, and the addition of metal oxide to more than 10.0% to the feedstock is impractical due to the increase in ash content in the resulting coking additive. Organization of circulating irrigation in the lower part of the distillation column with the possibility of regulating the quality of the heavy gas oil and bottoms that are removed, in particular, the temperatures of their beginning and end of boiling, and, as a result, viscosity, will provide a suspension of calcium oxide and / or hydroxide in heavy gas oil of a certain concentration with properties suitable for pumping. So, if heavy gas oil is removed from the column with a high boiling point, it has a high viscosity, which makes it difficult to pump the suspension with a pump with a calcium concentration of more than 35%. In this case, the amount of circulating irrigation to the bottom of the distillation column is increased, which contributes to the condensation of the highest boiling components from heavy gas oil and their conversion to bottoms. This achieves a simultaneous decrease in the viscosity of both heavy gas oil and bottoms. The supply of antifoam additives to the upper part of the coking chamber will prevent the transfer of coke foam into the distillation column and its coking in case of intensive foaming during coking of crude oil in the presence of calcium oxide and / or hydroxide. In the case of mixing the feedstock with calcium oxide, foaming is absent when heating the suspension of the modifier in heavy gas oil up to 300 ° C, while when mixing the feedstock with calcium hydroxide, foaming is already observed at a temperature of more than 80 ° C. In FIG. 1 shows a diagram of an implementation of the proposed method according to the first embodiment; in FIG. 2 - the same as in the second embodiment. The proposed method according to the first and second embodiment is as follows. The initial sulfur (primary) raw material is heated in the furnace 1 to a temperature of 250-390 ° C and fed to the remote section 2 of the distillation column 3, which also serves recycle - heavy coking gas oil from a distillation column. As a result of mixing the primary raw material with the recirculated material, secondary raw material is formed, which is heated in the reaction-heating furnace 4 to a temperature of 450-490 ° C and fed to the coking chamber 5, where a coking additive is formed, as well as vapor-liquid coking products, which are the helmets enter the distillation column, where they are fractionated to produce gas, gasoline, light and heavy gas oils and bottoms. According to the first variant of the proposed method, before being fed to the coking chamber 5, the secondary raw materials are mixed with a modifier — calcium oxide and / or hydroxide before and after the reaction-heating furnace 4, the modifier being pre-mixed with heavy gas oil in the ratio (25-35) : (65-75) with the formation of a suspension of the modifier in heavy gas oil using, for example, a mixer 6 or a disintegrator. According to the second variant of the proposed method, calcium oxide and / or calcium hydroxide is added to the bottom residue as a modifier pre-mixed with heavy gas oil in the ratio (25-35) :( 65-75) to form a suspension of the modifier in heavy gas oil using, for example, a mixer 6 or a disintegrator. After this, the bottom residue is either mixed before being fed into the coking chamber with secondary raw materials, or fed directly to the coking chamber. In both variants, the content of calcium oxide and / or calcium hydroxide supplied to the coking chamber is 0.5-10.0% by weight of the feedstock. In both cases, in order to prevent foaming, it is advisable to apply a mixture of modifier with heavy gas oil to the outlet part of the pumps (not shown) for transferring bottoms and secondary raw materials to the coking chamber. In addition, in both variants, the method includes circulating irrigation of heavy gas oil, wherein the quality and quantity of heavy gas oil and bottoms removed from the distillation column are controlled by changing the amount of circulating irrigation on the first plate below the battery of the distillation column. In addition, in both embodiments, an antifoam additive (not shown) is sprayed onto the top of the coking chamber. According to the variants of the proposed method, the following examples were carried out. Example 1 (in the first embodiment of the proposed method). The feedstock (tar mixture of West Siberian and Arlan oil), having a density of 1.025 g / cm, Conradson coking capacity of 24% by mass, sulfur content of 3.21% was coked in a delayed coking industrial plant as follows: The feedstock was heated in a tubular the furnace to a temperature of 310 ° C, after which it was fed to the remote section of the distillation column, where it was mixed with heavy coking gas oil as 10% recirculated feed. The resulting secondary raw materials were mixed with calcium oxide pre-mixed with heavy gas oil coking in a ratio of 25:75 with the formation of a suspension of calcium oxide in heavy gas oil. The content of calcium oxide was 2.5% by weight of the feedstock, after which it was heated in an oven to a temperature of 470 ° C and fed into a coking chamber, where a coking additive and vapor-liquid coking products were formed. The latter were fed through the helmet pipe to the lower part of the distillation chamber, where they were fractionated to form gas, gasoline, light and heavy gas oils, and still bottoms. The conditions for coking, the material balance of the process and the quality of the obtained coking additive according to example 1 are summarized in table. In the first embodiment of the proposed method, coking was carried out according to examples 2-5. Coking conditions and results are summarized in the same table. Example 6 (in the second embodiment of the proposed method). The same raw material was taken as in example 1, which was heated in a tube furnace to a temperature of 310 ° C, and then fed to the remote section of the distillation column, where it was mixed with heavy coking gas oil as 10% recirculate to the raw material. The resulting secondary raw materials were heated in a furnace to a temperature of 485 ° C and fed into a coking chamber, where a coking additive and vapor-liquid coking products were formed. The latter were fed through the helmet pipe to the lower part of the distillation chamber, where they were fractionated to form gas, gasoline, light and heavy gas oils, and still bottoms. The resulting bottom residue was mixed with calcium oxide pre-mixed with heavy gas oil coking in a ratio of 30:70 with the formation of a suspension of calcium oxide in heavy gas oil, and served directly into the coking chamber. The content of calcium oxide was 5% of the mass of the feedstock. In addition, according to the second variant of the proposed method, coking was carried out according to examples 7 and 8. The initial coking data, the quality of the coking additive according to examples 6-8 are also summarized in the table. For comparison with the options of the proposed method was obtained coking additive by the prototype method. Example 9 (prototype). The same raw materials as in example 1 were heated in a tube furnace to a temperature of 320 ° C, after which they were fed to the distillation section of the distillation column, where it was mixed with heavy coking gas oil as 10% recirculated to the raw material. The resulting secondary raw materials were heated in a furnace to a temperature of 470 ° C and fed into a coking chamber, where a coking additive and vapor-liquid coking products were formed. The latter were fed through the helmet pipe to the lower part of the distillation chamber, where they were fractionated to form gas, gasoline, light and heavy gas oils, and still bottoms. The data of example 9 are shown in the table. As can be seen from the data presented, the coking process in the presence of a modifier helps to reduce the content of organic sulfur in the resulting coking additive (to 0.65 - 2.87%, in the prototype - 3.62%). This is due to the partial binding of sulfur to calcium to form calcium sulfide. (CaS). Moreover, the greater the amount of modifier is introduced into the coking feedstock, the more the organic sulfur content in the coking additive decreases, but the ash content of the coking additive increases at the same time. This ash is represented either by calcium sulfide, which, in the future, when it enters the blast furnace as a part of metallurgical coke in the form of fuel and a reducing agent, passes into slag, thereby contributing to a decrease in the required amount of fluxes introduced to desulfurize the sulfur contained in the ore and fuel, or - in the form of unreacted with sulfur contained in the coking raw material, calcium oxide and / or hydroxide, which are the main components of fluxes, which also helps to reduce the number of fluxes introduced and at the same time contributes to an additional decrease in sulfur content in cast iron. The modifier is introduced into secondary raw materials or into bottoms coking gas oil in the form of a suspension of calcium oxide and / or calcium hydroxide in heavy coking gas oil. When a modifier is introduced at the outlet of the reaction-heating furnace, the temperature at the inlet to the coking chamber decreases, so the temperature of the secondary raw materials at the outlet of the furnace can be increased to 490 ° C. When preparing a suspension of calcium hydroxide in heavy coking gas oil at temperatures above 80 ° C, intense foaming is observed, therefore, in this case, it is necessary to prepare a suspension at low (less than 80 ° C) temperatures. In addition, when using calcium hydroxide as a modifier and the need to introduce a large amount of calcium (10% for raw materials) and in order to eliminate the need for a significant increase in the temperature of the secondary raw materials at the furnace outlet, when the modifier is introduced after the furnace, the concentration of calcium in the suspension should be as much as possible. However, this will increase the viscosity of the suspension and cause difficulties when pumping it. In this case, to obtain a suspension, it is necessary to use heavy gas oil with the lowest possible viscosity. The regulation of the viscosity of heavy gas oil in order to ensure the viscosity of the suspension required for normal operation of the pump is carried out by organizing circulating irrigation on plates at the bottom of the distillation column. An increase in the supply of chilled heavy gas oil, used as circulating irrigation, on the first plate below the distillation column battery, condenses the high boiling (and, as a result, high viscosity) fractions of heavy gas oil and converts them to the bottom residue, which leads to a decrease in temperature the end of boiling of heavy gas oil, lowering its viscosity, and, at the same time, lowering the temperature of the beginning of boiling of the bottom residue and lowering its viscosity. To reduce foaming and eliminate the likelihood of coke foam being transferred to the distillation column during coking in accordance with Examples 2 and 5-8, an anti-foam additive was applied to the top of the coking chamber. When a modifier is introduced in the form of a suspension in a heavy coking gas oil mixed with bottoms directly into the coking chamber, while the organic sulfur content in the resulting coking additive is reduced, the yield of the latter increases. This is due to the fact that the bottom residue is the highest boiling fraction formed during the coking process, having high density and coking ability and under the condition W

its involvement in the coking process gives an increase in the yield of coking additives. 5 It follows from the foregoing that the use of variants of the proposed method in comparison with the prototype will allow to obtain a coking additive with a low sulfur content in organic form. 6 In addition, when the bottoms of coking are involved in secondary raw materials, the yield of coking additive will increase.

The initial data of coking, the material balance of the process and the quality of the target product

Claims

Formula of the invention 1. A method for producing a modified coking additive by delayed coking of oil residues, which consists in the fact that the feedstock, after heating, is fed to the external section of the distillation column for mixing with heavy gas oil as recirculate and the formation of secondary raw materials, which are heated in a reaction-heating furnace and served in a coking chamber, where a coking additive and vapor-liquid coking products are formed, the latter are fractionated in a distillation column to form gas, gasoline, light and heavy gas oil and bottoms coking residue, characterized in that the secondary raw material before being fed into the coking chamber is mixed with calcium oxide and / or calcium hydroxide as a modifier, which is pre-mixed with heavy gas oil in the ratio (25-35) :( 65 -75), while the content of the modifier supplied to the coking chamber is 0.5-10.0% by weight of the feedstock. 2. The method according to p. 1, characterized in that the mixing of the secondary raw materials with the modifier is carried out before the reaction-heating furnace and / or after it. 3. The method according to p. 1 or 2, characterized in that the secondary raw materials are heated in a reaction-heating furnace to a temperature of 450-490 ° C. 4. The method according to p. 1 or 2, characterized in that it involves the circulation irrigation of heavy gas oil in the lower part of the distillation column, while the quality and quantity of heavy gas oil and still bottoms withdrawn from the distillation column, adjusted by changing the amount of circulating irrigation on the plates of the column. 5. The method according to p. 1 or 2, characterized in that the antifoam additive is sprayed into the upper part of the coking chamber. 6. A method of producing a modified coking additive by delayed coking of oil residues, which consists in the fact that the raw material after heating is fed to the remote section of the distillation column for mixing with heavy gas oil as recirculate and the formation of secondary raw materials, which are heated in a reaction-heating furnace and fed into a coking chamber, where a coking additive and vapor-liquid coking products are formed, the latter are fractionated in a distillation column to form gas, gasoline, light and heavy yellow gas oil and bottoms coking residue, characterized in that the oxide and / or calcium hydroxide are added to the bottom residue as a modifier pre-mixed with heavy gas oil in the ratio (25-35) :( 65-75), after which the bottom residue is either mixed before feeding into the coking chamber with secondary raw materials, or served directly into the coking chamber, the content of the modifier supplied to the coking chamber is 0.5-10.0% by weight of the feedstock. 7. The method according to p. 6, characterized in that the secondary raw materials are heated in a reaction-heating furnace to a temperature of 450-490 ° C. 8. The method according to p. 6 and 7, characterized in that it includes the circulation irrigation of heavy gas oil in the lower part of the distillation column, while the quality and quantity of heavy gas oil and still bottoms withdrawn from the distillation column, adjusted by changing the amount of circulating irrigation on the plates of the column. 9. The method according to p. 6 and 7, characterized in that an anti-foam additive is sprayed into the upper part of the coking chamber.