RU2458967C1 - Method for thermal-oxidative cracking of black oil - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for thermal-oxidative cracking of black oil, involving heating streams of starting material and an oxygen-containing gas and feeding into a cracking reactor. Before feeding into the reactor, the heated streams are mixed and the obtained liquid-gas mixture is fed into the reactor in form of one or more streams.

EFFECT: reduced output of gaseous products.

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Description

The invention relates to petrochemistry, in particular to the processing of heavy oil residues (TNO) to obtain light petroleum products.

A known method of processing TNO, including their processing with an ozone-containing mixture followed by thermal cracking of the obtained product at a pressure of 0.5-3.0 MPa and a space velocity of 1-2 h ^-1 . Thermocracking is carried out at a temperature of 400-430 ° C (RU 2184761).

The main disadvantage of this method is the formation of a significant amount of coke 0.2-0.25% of the amount of feed, which creates certain problems when implementing the process in a continuous mode. An additional disadvantage of this method is the use of equipment for producing ozone-containing mixtures and apparatuses for such processing.

A known installation for thermal cracking of TNO, in which the TNO is heated in the preheating unit to 100-200 ° C, is mixed in the injector with air at a temperature of 50-250 ° C, a pressure of 0.5-1 MPa at an air supply rate of 0.1- 10 h ^-1 , separated in the separator into two streams: gaseous (exhaust air) and liquid (activated TNO). The liquid stream is heated to 380-410 ° C in a tubular furnace and sent to the external thermal cracking reactor TNO, where the thermal cracking reaction of the TNO occurs. Liquid and vaporous reaction products are separated into fractions in the separation unit with the release of hydrocarbon gas, liquid fractions and heavy cracking residue, respectively. Depending on the type of TNO, hydrocarbon gas and light fractions are obtained: gasoline (HC - 180 ° C), diesel (180-350 ° C) and vacuum gas oil (350-450 ° C), as well as fuel oil 450 ° C (in case of use as feedstock of straight-run fuel oil), bitumen (in the case of using tar as a feedstock). The yield of cracking products is not given in the patent (RU 2232789).

The main disadvantage of this installation is its complexity.

A known method of processing TNO, comprising contacting all preheated feedstock with air directly in a thermal cracking reactor at 400-420 ° C, feeding raw materials to the upper part of the reactor and air to the lower part, followed by separation of the obtained products into hydrocarbon gas, liquid fractions and heavy residue (RU 2289607, figure 2). When processing oil tar at 420 ° C and an air flow rate of 2.5 l / kg of raw material, the yield of light fractions was 30%, gaseous 5%, fuel oil M100 - the rest.

The disadvantage of this method is the relatively low yield of light fractions.

The closest analogue to the claimed method is a method for processing TNO by oxidative cracking, which includes feeding flows of preheated feedstock to 430-450 ° C to the upper part of the reactor and air to 500-530 ° C to the lower part of the reactor, discharge from the lower part of the heavy reactor the remainder and its supply to the quenching apparatus or stripper and from the upper part - light cracking products and their separation unit (RU 2335525).

When processing straight-run fuel oil at 440 ° C and a pressure of 8.5–9 atm with a contact time of 10 min, the yield of light fractions (including gas) was 63%, the rest was fuel oil of the M100 brand.

When processing oil tar with the addition of 5% oil sludge at 450 ° C and an air temperature of 530 ° C, its consumption is 2.8 kg / 100 kg of feedstock, the pressure in the reactor is 1.2 atm and the cracking contact time is 9 min, the yield of light fractions is 36 %, gaseous products 5%, fuel oil M100 - the rest.

The main disadvantage of this method is the complex system of separation of the obtained products, including a quenching apparatus or stripper, as well as a sufficiently high yield of gaseous products (at least 5%), which are difficult to recycle.

An object of the invention is to simplify the process, as well as reducing the yield of gaseous products.

This problem is solved by a method of processing heavy oil residues, including heating the streams of the original liquid raw materials and oxygen-containing gas, cracking the oil residues at elevated pressure and temperature in the reactor, separating the resulting products into fractions in which heated streams of raw materials and oxygen-containing gas before feeding them into the column apparatus mixed, and the resulting gas-liquid mixture is sent to the reactor in the form of one or more streams.

To illustrate the method, hollow vertical column-type apparatuses of 1 l volume were used as reactors. However, the use of other types of reactors is not contraindicated. The principle of operation of the column reactors used to illustrate the method may also be different.

So, the presence in the reaction mass of non-condensable gas phase (mainly nitrogen) allows you to combine the cracking process with the process of removing the resulting light cracking products in the form of vapors with a gas stream from the upper part of the reactor and removal of the heavy cracking residue from the bottom of the column reactor (figure 2 )

The implementation of the process according to the scheme is not contraindicated, when liquid and gaseous products are removed from the upper part of the column reactor, and the separation process is carried out in an external gas-liquid separator (Fig. 1).

Depending on the method of product withdrawal from the column reactor, the place for introducing gas-liquid flows into the reactor may also be different. However, in order to reduce the entrainment of unconverted starting materials (oxygen and heavy products) from the reaction zone, in the case of removal of a heavy cracking residue from the bottom of the column reactor and light products from the top, the entry points of the gas-liquid mixture into the reactor should be located closer to the middle of the column (figure 2). In the case of removal of products from the upper part of the reactor, the entry points are preferably located in the lower part of the reactor (Fig. 1).

The following examples illustrate the method.

Example 1

Raw materials, tar of the Moscow refinery (stream I), with a flow rate of 2.1 kg / h and air (stream II) with a flow of 160 l / h, are heated in furnaces 1 and 2 to a temperature of 440 ° C and 450 ° C, respectively, and mixed in a mixer 3. The resulting gas-liquid mixture is divided into two streams, one of which is directed to the very bottom of the thermooxidative cracking reactor 4, and the second to its middle (Fig. 1). Due to the simultaneous occurrence of partial oxidation reactions and degradation of raw materials, the temperature in the reactor during this experiment was 440 ± 5 ° С. The pressure in the reactor is 0.1 MPa. The resulting gaseous and liquid products of thermo-oxidative cracking are removed from the upper part of the reactor 4 and sent to a separator 5, from which liquid heavy products (stream III) and vapors of light hydrocarbon fractions (stream IV) are taken at a speed of 1.38 kg / h. Stream IV is sent to distillation column 6, from which a gasoline fraction (NK - 180 ° C) is taken at a speed of 0.09 kg / h (stream V) and a diesel fraction (180-350 ° C) at a speed of 0.51 kg / h (stream VI) , bottoms (stream VII) at a rate of 0.03 kg / hour, and gaseous products - the rest (stream VIII). Stream VII is combined with stream III. The resulting mixture meets the requirements for road bitumen grade BN 60/90.

The yield of light fractions is 28.6%. The yield of gaseous products is 4%.

Example 2

Raw materials, tar of the Moscow refinery, with a flow rate of 2.7 kg / h and air with a flow rate of 180 l / h are heated in furnaces 1 and 2 to a temperature of 460 ° C and 455 ° C, respectively, and mixed in a mixer 3. The resulting gas-liquid mixture is divided into three flow, which is fed into the Central part of the reactor 4 thermooxidative cracking (Figure 2). The temperature in the reactor is 455 ± 5 ° C. The pressure in the reactor is 0.3 MPa. Heavy products are removed from the bottom of the reactor at a rate of 1.51 kg / h (stream III). Gaseous reaction products from the upper part of the reactor (stream IV) are sent to distillation column 5, from which a gasoline fraction (НК - 180 ° C) is taken at a rate of 0.14 kg / h (stream V) and a diesel fraction (180-350 ° C) with at a rate of 0.85 kg / h (stream VI), bottoms (stream VII) at a rate of 0.03 kg / hour, and gaseous products - the rest (stream VIII). Stream III is combined with stream VII. The resulting mixture meets the requirements for road bitumen grade BN 60/90.

The yield of light fractions is 36.7%. The yield of gaseous products is 4.8%.

Example 3

The process is carried out analogously to example 1, but using the heavy oil residue of vacuum distillation of combined oils of Kazakhstan with a flow rate of 4.2 kg / h (stream I) and an oxygen-containing gas of the composition, vol.%: Oxygen 48; nitrogen and inert - the rest, with a flow rate of 78 l / h (stream II). These streams are heated in furnaces 1 and 2 to a temperature of 460 ° C and 440 ° C, respectively, and mixed in a mixer 3. The resulting gas-liquid mixture in full is sent in one stream to the bottom of the thermooxidative cracking reactor 4 (Figure 1). The temperature in the reactor is 450 ± 5 ° C. The pressure in the reactor is 0.2 MPa. The result was: 1.40 kg / h of light hydrocarbons, incl. 0.3 kg / hour (stream V) of the gasoline fraction and 1.1 kg / hour (stream VI) of the diesel fraction. The heavy residue (the sum of flows III and VII), in the amount of 2.65 kg / h, in its characteristics corresponds to the oil fractions used in the production of compounding fuel oils, for example, grade M-100. The yield of light fractions is 34.8%. The yield of gaseous products is 3.6%.

Example 4

The process is carried out analogously to example 1, but using Canadian Alberta bitumen with a flow rate of 2.1 kg / h (stream I) and an oxygen-containing gas of the composition, vol.%: Oxygen 39; nitrogen and inert - the rest, with a flow rate of 109 l / h (stream II). These streams are heated in furnaces 1 and 2 to a temperature of 440 ° C and 460 ° C, respectively, and mixed in a mixer 3. The resulting gas-liquid mixture is divided into two streams. The first stream is directed to the bottom of the reactor, the second to the Central part of the reactor (Figure 1). The temperature in the reactor is 445 ± 5 ° C. The pressure in the reactor is 0.1 MPa. As a result, 0.68 kg / hr of light fractions and 1.33 kg / hr of heavy cracking residue were obtained, which in its characteristics corresponds to heavy oil residues used in the production processes of compound oil bitumen. The yield of light fractions 32.3%. The yield of gaseous products 4.2%.

Example 5

The process is carried out analogously to example 4, but the bitumen flow to the mixer is heated to 430 ° C, and air to 460 ° C. The resulting gas-liquid mixture is divided into four streams. The first stream is directed to the bottom of the reactor, the other three streams are distributed evenly throughout the column from its middle to the bottom. The temperature in the reactor is 440 ± 5 ° C. The pressure in the reactor is 0.1 MPa. The yield of light fractions is 34.3%. The yield of gaseous products 3.8%.

Carrying out the process by this method can significantly simplify the cracking technology, as well as reduce the yield of gaseous products from 5.0 to 3.6-4.6% with a fairly high yield of light fractions (28-37%).

Claims (1)

The method of thermo-oxidative cracking of heavy oil residues at elevated temperature and pressure, including preheating the feed streams and oxygen-containing gas and feeding them to a cracking reactor, characterized in that before feeding them into the reactor, the heated streams are mixed, and the resulting gas-liquid mixture is sent to the reactor in the form one or more threads.

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