RU2502785C2 - Thermal-oxidative cracking method of heavy oil residues - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to a method involving pre-heating of flows of heavy oil residues and oxygen-containing gas till temperature of 430-460°C, their mixing and supply of the obtained steam-liquid mixture to a cracking reactor in the form of one or more flows, at least in one or more tangentially located branch pipes.

EFFECT: simpler process and lower yield 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 an injector with air at a temperature of 50-250 ° C, a pressure of 0.5-1 MPa at an air supply speed of 0.1- 10 h ^-1 , separated in a separator into two streams - gaseous (exhaust air) and liquid (activated TNO). The liquid stream is heated to 380-410 ° C in a tube furnace and sent to a portable thermal cracking reactor TNO, where the thermal cracking reaction of TNO occurs. Liquid and vaporous products, reactions 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 (НК - 180 ° С), diesel (180-350 ° С) and vacuum gas oil (350-450 ° С), as well as fuel oil 450 ° С - (in the case of use of straight-run fuel oil as a feedstock), 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 refining 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, we have chosen for the prototype, is a method of processing TNO by oxidative cracking, including the flow of preheated feedstock up to 430-450 ° C in the upper part of the reactor and air up to 500-530 ° C in the lower part of the reactor, removal of the heavy residue from the lower part of the reactor and its feeding into the quenching apparatus or stripping column and from the upper part - light cracking products and their separation unit (RU 2335525).

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

During the processing of oil tar with the addition of 5% oil sludge at 450 ° C and an air temperature of 530 ° C, its consumption of 2.8 kg / 100 kg of raw materials, a pressure in the reactor of 1.2 atm and during 9 minutes of operation of the unit, the yield of light fractions was 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 by thermo-oxidative cracking at elevated pressure and temperature, including preheating the streams of the original liquid feed and oxygen-containing gas, cracking the oil residues in a vertical column reactor, in which heated streams of feed and oxygen-containing gas are mixed before being fed into the reactor, and the resulting gas-liquid mixture is fed into the reactor in the form of one or more streams, at least through one or more tangentially position of the sleeve (1).

To illustrate the method, hollow vertical column-type apparatuses of 1 l volume were used as reactors.

Depending on the method of product withdrawal from the column reactor, the principle of operation of the column reactors used to illustrate the method may 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 the 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 a remote gas-liquid separator (Figure 3).

Depending on the method of product withdrawal from the column reactor, the places (nozzles) for introducing gas-liquid flows into the reactor can 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 the heavy cracking residue from the bottom of the column reactor and light products from the upper part, the places (nozzles) for introducing the gas-liquid mixture flows 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 places (nozzles) for introducing the flows of the gas-liquid mixture are preferably located in the lower part of the reactor. In this case, part of the gas-liquid mixture stream can be fed through a pipe located in the bottom of the column (Figure 3).

The following examples illustrate the method.

Example 1

The process of thermooxidative cracking is carried out on the installation depicted in figure 3. Raw materials, tar of the Moscow refinery, with a flow rate of 2.3 kg / hour (stream I) and air with a flow rate of 167 l / hour (stream II) are heated in furnaces 1 and 2 to a temperature of 450 ° C and 445 ° 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 through a nozzle located in the bottom, and the second into its middle through a tangentially located nozzle. 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 0.11 MPa.

The resulting gaseous and liquid products of thermooxidative cracking are removed from the upper part of the reactor 4 and sent to the separator 5, from which liquid heavy products (stream III), as well as pairs of light hydrocarbon fractions (stream IV) are taken at a speed of 1.4 kg / h. Stream IV is sent to distillation column 6, from which a gasoline fraction (NK-180 ° C) is taken at a speed of 0.13 kg / h (stream V), and a diesel fraction (180-350 ° C) at a speed of 0.66 kg / h (stream VI ), bottoms (stream VII) at a rate of 0.02 kg / h, as well as gaseous products - the rest (stream VIII). Stream VII is combined with stream III. The resulting mixture of flows VII and III meets the requirements for road bitumen grade BN 60/90. The yield of light fractions is 34.3%. The yield of gaseous products is 3.9%.

Example 2

The process of thermo-oxidative cracking is carried out on the installation depicted in figure 2. Raw materials, tar of the Moscow refinery with a flow rate of 2.9 kg / h (stream I) and air with a flow rate of 190 l / hour (stream II) are heated in furnaces 1 and 2 to a temperature of 455 ° C and 465 ° C, respectively, and mixed in a mixer 3 The resulting gas-liquid mixture is divided into three streams, which are fed into the central part of the thermal oxidative cracking reactor 4 through three tangentially arranged nozzles. The temperature in the reactor is 460 ± 5 ° C. The pressure in the reactor is 0.25 MPa. Heavy products are removed from the bottom of the reactor at a speed of 1.62 kg / h (stream III). Gaseous reaction products (stream IV) are removed from the upper part of the reactor and sent to distillation column 5. A gasoline fraction (NK-180 ° С) is taken from the distillation column at a rate of 0.16 kg / h (stream V), and a diesel fraction (180- 350 ° C) at a rate of 0.94 kg / hour (stream VI), bottoms (stream VII) at a rate of 0.07 kg / hour, as well as gaseous products - the rest (stream VIII). Stream III is combined with stream VII, while the resulting mixture meets the requirements for road bitumen grade BN 60/90. The yield of light fractions is 37.9%. The yield of gaseous products 3.8%.

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 as a raw material, with a flow rate of 4.4 kg / h (stream I) and an oxygen-containing gas, composition,% vol .: oxygen - 54; nitrogen and inert - the rest, with a flow rate of 89 l / h (stream II). These streams are heated in furnaces 1 and 2 to a temperature of 460 ° C and 450 ° C, respectively, and mixed in a mixer 3. The resulting gas-liquid mixture in full is fed in one stream to the lower part of the oxidation cracking reactor 4 through a tangentially located pipe. The temperature in the reactor is 455 ± 5 ° C. The pressure in the reactor is 0.18 MPa. The result was: 1.64 kg / h of light hydrocarbons, incl. 0.42 kg / hour (stream V) of the gasoline fraction and 1.22 kg / hour (stream VI) of the diesel fraction. The heavy residue (the sum of flows III and VII), in the amount of 2.6 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 37.3%. The yield of gaseous products is 3.6%.

Example 4

The process is carried out analogously to example 1, but using Canadian Alberta bitumen as a raw material, with a flow rate of 2.3 kg / h (stream I) and an oxygen-containing gas of the composition,% vol .: oxygen - 45; nitrogen and inert - the rest; with a flow rate of 115 l / h (stream II). These streams are heated in furnaces 1 and 2 to a temperature of 440 ° C and 465 ° 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 very bottom of the thermooxidative cracking reactor through a pipe located in the bottom, and the second stream to the central part of the reactor through a tangentially located pipe. The temperature in the reactor is 450 ± 5 ° C. The pressure in the reactor is 0.12 MPa. The result was: 0.83 kg / hr of light fractions and 1.37 kg / hr of heavy cracking residue, which in its characteristics corresponds to oil heavy residues used in the production processes of compound oil bitumen. The yield of light fractions is 36.0%. The yield of gaseous products is 4.3%.

Example 5

The process is carried out analogously to example 4, but the bitumen flow to the mixer is heated to 440 ° 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 thermooxidative cracking reactor through a pipe located in the bottom, three other streams are fed through three tangentially located pipes placed on 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 39.8%. The yield of gaseous products is 3.7%.

Example 6 (comparative)

The process is carried out analogously to example 1, but 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 through a pipe located in the bottom, and the second into its middle through a radially located pipe.

In this case, the yield of light fractions is 29.1%. The yield of gaseous products 4.1%.

Example 7 (comparative)

The process is carried out analogously to example 2, but the resulting gas-liquid mixture is divided into three streams, which are fed into the Central part of the reactor 4 thermooxidative cracking through three radially arranged nozzles.

In this case, the yield of light fractions is 30.2%. The yield of gaseous products is 3.9%.

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 3.5-4.3% with a fairly high yield of light fractions (34-39%).

Claims (1)

A method of thermooxidative cracking of heavy oil residues at elevated temperature and pressure, comprising preheating the feed streams and oxygen-containing gas and feeding them into a vertical column reactor, characterized in that the heated flows are mixed before being fed into the reactor, and the resulting gas-liquid mixture is sent to the reactor in in the form of one or more flows, at least through one or more tangentially located nozzles.

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