Method and reaction system for producing low-carbon olefin and aromatic hydrocarbon
阅读说明：本技术 一种生产低碳烯烃和芳烃的方法及反应系统 (Method and reaction system for producing low-carbon olefin and aromatic hydrocarbon ) 是由 张执刚 龚剑洪 魏晓丽 张策 崔琰 刘宪龙 李�东 于 2020-05-08 设计创作，主要内容包括：一种生产低碳烯烃和芳烃的方法及反应系统,包括：(1)原料碳四组分引入催化裂化反应器,与再生器来的再生催化剂接触反应,反应得到的油气和催化剂混合物进入沉降器进行气固分离,分离出的反应油气经分离系统分离出乙烯、丙烯、芳烃产品和第一碳四组分；(2)第一碳四组分进入芳构化反应器与芳构化催化剂接触反应,反应产物经分离系统分离出乙烯、丙烯和芳烃产品；(3)第二碳四组分进入烷烃脱氢反应器,与脱氢催化剂接触进行脱氢反应,反应产物返回催化裂化反应器反应器。本发明提供的方法乙烯、丙烯和芳烃的产率高,能耗低。(A method and a reaction system for producing low-carbon olefin and aromatic hydrocarbon comprise: (1) introducing four components of raw material carbon into a catalytic cracking reactor, carrying out contact reaction with a regenerated catalyst from a regenerator, allowing a mixture of oil gas and the catalyst obtained by the reaction to enter a settler for gas-solid separation, and separating ethylene, propylene, an aromatic hydrocarbon product and a first four-component carbon from the separated reaction oil gas through a separation system; (2) the first four carbon components enter an aromatization reactor to contact and react with an aromatization catalyst, and ethylene, propylene and aromatic hydrocarbon products are separated from reaction products through a separation system; (3) and the second carbon four components enter an alkane dehydrogenation reactor, contact with a dehydrogenation catalyst to perform dehydrogenation reaction, and return the reaction product to the catalytic cracking reactor. The method provided by the invention has the advantages of high yield of ethylene, propylene and aromatic hydrocarbon and low energy consumption.)
1. A process for producing ethylene, propylene and aromatic hydrocarbons comprising:
(1) introducing four components of raw material carbon into a catalytic cracking reactor, carrying out contact reaction with a regenerated catalyst from a regenerator, allowing a mixture of oil gas and the catalyst obtained by the reaction to enter a settler for gas-solid separation, separating the separated reaction oil gas into dry gas, liquefied gas, gasoline, diesel oil and oil slurry through a separation system, and further separating propylene, propane and a first four-component carbon from the liquefied gas;
(2) the separated first four carbon components enter an aromatization reactor to contact and react with an aromatization catalyst, dry gas, liquefied gas and gasoline rich in aromatic hydrocarbon are separated from reaction products through a separation system, propylene, propane and a second four carbon components are further separated from the liquefied gas, and the aromatic hydrocarbon is further separated from the gasoline rich in aromatic hydrocarbon;
(3) and the second carbon four components enter an alkane dehydrogenation reactor, contact with a dehydrogenation catalyst to perform dehydrogenation reaction, and return the reaction product to the catalytic cracking reactor.
2. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 1, characterized by further comprising the step (4): and (3) separating propane from dry gas in the steps (1) and (2) to obtain ethane, and introducing the ethane into a steam cracking furnace for steam cracking to generate ethylene and propylene.
3. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, wherein the raw C four component is from a catalytic cracking unit and contains C four olefins and C four hydrocarbons, and the olefin content of the raw C four component is more than 20 wt%.
4. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 3, wherein the olefin content in the raw material carbon four component is 40 wt% to 80 wt%.
5. The method for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, wherein the catalyst in the step (1) is a catalytic cracking catalyst, and comprises an MFI-structured molecular sieve, a Y-type molecular sieve, clay and a binder, wherein the MFI-structured molecular sieve is contained in an amount of 5 to 60 wt%, preferably 10 to 50 wt%, the Y-type molecular sieve is contained in an amount of 1 to 40 wt%, preferably 1 to 30 wt%, the clay is contained in an amount of 10 to 70 wt%, preferably 15 to 45 wt%, and the binder is contained in an amount of 5 to 40 wt%, preferably 5 to 30 wt%, based on the total weight of the catalyst.
6. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, wherein the catalytic cracking reactor is a reactor comprising one or a combination of a riser reactor, a turbulent bed reactor and a fast bed reactor; the operating conditions of the catalytic cracking reactor were: the average temperature is 550-700 ℃, the reaction pressure is 0.15-0.5 MPa, and the reaction space velocity is 2-600 h-1。
7. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, characterized in that the aromatization catalyst comprises a molecular sieve, a metal active component selected from one or more of rare earth elements, elements of groups VIB, VIII, IIB and VIIB, and a refractory inorganic oxide support, preferably silica and alumina.
8. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, wherein the aromatization reactor is a fixed bed reactor.
9. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 8, wherein the aromatization reactor is operated under the following conditions: the reaction temperature is 350-450 ℃, the reaction pressure is 0.20-2.0 MPa, and the reaction space velocity is 0.2-2 h-1。
10. According to claimThe method for producing ethylene, propylene and aromatic hydrocarbons according to claim 1 or 2, characterized in that the alkane dehydrogenation reactor is a fixed bed reactor; the operating conditions are that the reaction temperature is 550-650 ℃, the reaction pressure is 0.10-0.5 MPa, and the reaction space velocity is 0.2-2 h-1。
11. A process of producing ethylene, propylene and aromatic hydrocarbons as claimed in claim 10, wherein the dehydrogenation catalyst comprises a molecular sieve and one or more metal active components selected from one or more of rare earth elements, group IA, IIA, VIB, VIII, IB and VIIB elements, and a refractory inorganic oxide support, wherein the refractory inorganic oxide support is silica and alumina.
12. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 2, wherein the step (4): propane separated by the oil-gas separation system enters a propane steam cracking furnace, ethane separated from dry gas enters an ethane steam cracking furnace, and ethylene and propylene are obtained through reaction.
13. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 2 or 12, wherein the steam cracking in the step (4) is carried out under the conditions of a reaction temperature of 780 to 850 ℃ and a residence time of 0.01 to 3 seconds.
14. The process for producing ethylene, propylene and aromatic hydrocarbons according to claim 2, wherein the same gas separation apparatus is used for the dry gas separation in the step (4), and the gas separation apparatus comprises a rectifying column and auxiliary facilities.
15. A reaction system for producing ethylene, propylene and aromatics, comprising a reaction unit, a catalyst, and a reactant stream; the reaction device comprises a catalytic cracking reactor, a regenerator, a first oil-gas separation system, a second oil-gas separation system, an aromatization reactor and an alkane dehydrogenation reactor which are communicated in sequence; the regenerator of the regenerator is communicated with the bottom of the catalytic cracking reactor, the upper part of the catalytic cracking reactor is provided with a settler and a gas-solid separation device, a spent agent outlet of the gas-solid separation device is communicated with the regenerator, an oil-gas outlet of the gas-solid separation device is communicated with the first oil-gas separation system, a C4 outlet of the first oil-gas separation system is communicated with the aromatization reactor, an outlet of the aromatization reactor is communicated with a second oil-gas separation system, a C4 outlet of the second oil-gas separation system is communicated with an alkane dehydrogenation reactor, and a product outlet of the dehydrogenation reactor is communicated with the catalytic cracking reactor; the catalytic cracking catalyst circularly flows in the catalytic cracking reactor and the regenerator, the aromatization catalyst is filled in the aromatization reactor, and light hydrocarbon raw materials are introduced through a raw material inlet of the catalytic cracking reactor and react in the reaction device.
16. The reaction system for producing ethylene, propylene and aromatic hydrocarbons according to claim 15, wherein said reaction apparatus further comprises a gas separation unit and a steam cracking furnace; the dry gas outlet and the liquefied gas outlet of the first oil-gas separation system and the second oil-gas separation system are communicated with a gas separation device, and ethane and propane outlets of the gas separation device are communicated with a steam cracking furnace.
17. The reaction system for producing ethylene, propylene and aromatic hydrocarbons according to claim 15 or 16, wherein the catalytic cracking reactor is a riser reactor, the aromatization reactor is a fixed bed reactor, and the alkane dehydrogenation reactor is a fixed bed reactor.
Technical Field
The invention relates to a method and a reaction system for producing chemical raw materials from petroleum raw materials, in particular to a method and a reaction system for producing ethylene, propylene and aromatic hydrocarbon from light hydrocarbon.
Technical Field
Ethylene, propylene and BTX aromatics are growing in demand each year as a large group of basic chemical feedstocks. The catalytic cracking is used as a device for processing heavy oil to produce gasoline, and a large amount of propylene is also produced as a byproduct, so that the catalytic cracking is a main supplement source of the propylene market. Wherein, the deep catalytic cracking (such as DCC process) using more selective molecular sieve (ZSM-5) as an active center can produce propylene in large quantity and produce certain propylene and BTX aromatic hydrocarbon as byproducts. At present, wax oil or hydrogenated wax oil is generally adopted in the process, and a small amount of residual oil or paraffin-based atmospheric residual oil is mixed as a raw material.
The technology for preparing propylene from liquefied gas rich in olefin takes liquefied gas with lower added value as raw material, and the carbon tetraolefin in the liquefied gas is cracked under the action of catalyst to generate propylene and ethylene with high added value and aromatic hydrocarbon-rich gasoline component with high octane value, for example, in the DCC family technology, C4 olefin is returned to a catalytic cracking device for cyclic cracking to generate ethylene and propylene. Meanwhile, ethanol gasoline is popularized nationwide in 2020, so that etherified C4 or etherified light gasoline products are limited to be added into finished gasoline, a large number of C4 etherifying devices are idle, and reprocessing and utilization of C4 olefins are concerned.
CN104878A discloses a method for producing low-carbon olefin, which takes gasoline, kerosene, diesel oil, vacuum wax oil, residual oil and a mixture as raw materials, and takes a Y-shaped molecular sieve and a ZSM-5 molecular sieve as active centers; a fluidized bed or a moving bed reactor is adopted; the operating conditions are that the pressure is 150 kPa-300 kPa, the reaction temperature is 550 ℃ and 650 ℃, and the space velocity is 0.2-20hr-1And the agent-oil ratio is 2-12. The method has high reaction temperature, more methane byproducts and large amount of unusable carbon four and diesel oil.
CN1034586A discloses a method for producing low-carbon olefin by hydrocarbon oil, which takes gasoline, kerosene, diesel oil, vacuum wax oil, residual oil and a mixture as raw materials, and takes a Y-shaped molecular sieve and a phosphorus-containing ZSM-5 molecular sieve as active centers; a fluidized bed or a riser reactor is adopted; the operation conditions are that the pressure is 120 kPa-400 kPa, the reaction temperature is 480 ℃ and 680 ℃, the residence time is 0.1-6 seconds, the agent-oil ratio is 4-20, and the atomized water vapor accounts for 1-50 percent of the weight of the raw materials. This method, despite modifying the catalyst, has similar problems to CN104878, i.e. high reaction temperature, more methane by-product, and generation of large amount of unusable carbon four and diesel.
CN1056595A discloses a method for producing carbon olefin by using multi-stage feeding from ethane to residual oil as raw material. The method uses a molecular sieve containing alkaline earth metal as an active center; a riser reactor is adopted; the operation conditions are that the pressure is 130 kPa-400 kPa, the reaction temperature is 600-900 ℃, the residence time is 0.1-6 seconds and the catalyst-oil ratio is 5-100, and the multi-stage feeding cracking is carried out from high to low according to different cracking difficulties. Although the method solves the problem of byproducts such as carbon four, the method also has the problem of more byproducts such as methane and coke for raw materials with poor processing property,
CN102337148A discloses a method for producing low-carbon olefins by using gasoline rich in four to eight carbon atoms as a raw material. The method uses the Y-type molecular sieve and the ZSM-5 molecular sieve as active centers(ii) a Adopting a riser reactor and a fluidized bed reactor; the operating conditions are that the pressure is 150 kPa-300 kPa, the reaction temperature is 480--1And the agent-oil ratio is 8-40. The method cannot solve the problem of accumulation of alkane components despite cyclic utilization of four-carbon to eight-carbon olefins.
CN101362961A discloses a method for producing low-carbon olefin and aromatic hydrocarbon by using hydrocarbons with the temperature of 160-270 ℃ as raw materials. The method uses a Y-type molecular sieve and a ZSM-5 molecular sieve as active centers; a riser reactor or a fluidized bed reactor is adopted; the operating conditions are that the pressure is 100 kPa-1000 kPa, the reaction temperature is 450 ℃ and 750 ℃, and the space velocity is 1-150hr-1And the agent-oil ratio is 1-150. The method solves the problem of the export of part of diesel oil.
CN 1667089A discloses a method for producing low-carbon olefin by using gasoline, kerosene, diesel oil, vacuum wax oil, residual oil and mixture as raw materials. The method comprises the steps of firstly carrying out hydrotreating on a raw material and a circulating material flow, and then feeding the material flows into a catalytic cracking reactor. Wherein the gas recycle is ethane, propane and C4. The liquid circulation feed is C5-C6, heavy gasoline aromatic raffinate oil, LCO, HCO and oil slurry. Although the method solves the problem of the output of most by-products, the method cannot solve the problem of the accumulation of alkane components and polycyclic aromatic hydrocarbon components.
The method has the problems of high carbon four-component cycle ratio, low propylene yield and high energy consumption.
Disclosure of Invention
The invention aims to solve the technical problems of high cycle proportion of the four carbon components, low propylene yield and high energy consumption in the prior art, and provides a method for producing low-carbon olefin and aromatic hydrocarbon with high product yield.
The second technical problem to be solved by the invention is to provide a catalytic conversion reaction system for producing low-carbon olefin and aromatic hydrocarbon.
A method for producing lower olefins and aromatics, comprising:
(1) introducing four components of raw material carbon into a catalytic cracking reactor, carrying out contact reaction with a regenerated catalyst from a regenerator, allowing a mixture of oil gas and the catalyst obtained by the reaction to enter a settler for gas-solid separation, separating the separated reaction oil gas into dry gas, liquefied gas, gasoline, diesel oil and oil slurry through a separation system, and further separating propylene, propane and a first four-component carbon from the liquefied gas;
(2) the separated first four carbon components enter an aromatization reactor to contact and react with an aromatization catalyst, dry gas, liquefied gas and gasoline rich in aromatic hydrocarbon are separated from reaction products through a separation system, propylene, propane and a second four carbon components are further separated from the liquefied gas, and the aromatic hydrocarbon is further separated from the gasoline rich in aromatic hydrocarbon;
(3) and the second carbon four components enter an alkane dehydrogenation reactor, contact with a dehydrogenation catalyst to perform dehydrogenation reaction, and return the reaction product to the catalytic cracking reactor.
A reaction system for producing low-carbon olefin and aromatic hydrocarbon comprises a reaction device, a catalyst and a reactant flow; the reaction device comprises a catalytic cracking reactor, a regenerator, a first oil-gas separation system, a second oil-gas separation system, an aromatization reactor and an alkane dehydrogenation reactor which are communicated in sequence; the regenerator of the regenerator is communicated with the bottom of the catalytic cracking reactor, the upper part of the catalytic cracking reactor is provided with a settler and a gas-solid separation device, a spent agent outlet of the gas-solid separation device is communicated with the regenerator, an oil-gas outlet of the gas-solid separation device is communicated with the first oil-gas separation system, a C4 outlet of the first oil-gas separation system is communicated with the aromatization reactor, an outlet of the aromatization reactor is communicated with a second oil-gas separation system, a C4 outlet of the second oil-gas separation system is communicated with an alkane dehydrogenation reactor, and a product outlet of the dehydrogenation reactor is communicated with the catalytic cracking reactor; the catalytic cracking catalyst circularly flows in the catalytic cracking reactor and the regenerator, the aromatization catalyst is filled in the aromatization reactor, and light hydrocarbon raw materials are introduced through a raw material inlet of the catalytic cracking reactor and react in the reaction device.
The method and the reaction system for producing the low-carbon olefin and the aromatic hydrocarbon have the beneficial effects that:
in the method for producing the low-carbon olefin by recycling the C-four fraction to the catalytic cracking device for further cracking, as the reaction speed of the C-four hydrocarbon is obviously lower than that of the C-four olefin, the conversion rate of the C-four olefin is higher and the conversion rate of the C-four hydrocarbon is extremely low in the reaction process of mixing the C-four fraction in the catalytic cracking reactor, so that the C-four hydrocarbon of the recycle stream is continuously accumulated in the recycling reaction process of the C-four components. In this case, if the carbon four cycle ratio is not increased, the propylene yield is reduced due to the decrease in the olefin content in carbon four. If the carbon four cycle ratio is increased, the energy consumption is greatly increased.
The method solves the problem of carbon tetrahydrocarbon accumulation in the carbon four-cycle material flow, and greatly reduces the energy consumption and the operation cost of the carbon four-cycle. The yield of ethylene, propylene and aromatic hydrocarbon is greatly increased, the ethylene, the propylene and the aromatic hydrocarbon can be produced to the maximum extent, and more high-quality cracking raw materials of ethane, propane and n-butane are provided for steam cracking. The method provided by the invention can also reduce the heat load of the aromatization device and reduce the energy consumption of the aromatization device.
Drawings
FIG. 1 is a schematic flow chart of a method for producing light olefins and aromatics provided by the present invention.
FIG. 2 is a schematic flow chart of the process for producing ethylene and propylene in comparative examples 1 and 2.
Wherein:
1-a catalytic cracking reactor; 2-an aromatization reactor; 3-alkane dehydrogenation reactor; 4-a regenerator; 5-a first oil-gas separation system; 6-a second oil-gas separation system; 8-regenerated catalyst inclined tube; 9-spent catalyst inclined tube; 10-a stripping section; 11-a settler; a 32-propane cracking furnace; a 33-ethane cracking furnace; 35-a gas separation device; 31. 34-dry gas line, 37-ethane line; 7-feed line; 12. 13, 14, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 36, 38-lines.
Detailed Description
The following specifically describes embodiments of the present invention:
the method for producing the low-carbon olefin and the aromatic hydrocarbon comprises the following steps:
(1) introducing four components of raw material carbon into a catalytic cracking reactor, carrying out contact reaction with a regenerated catalyst from a regenerator, allowing a mixture of oil gas and the catalyst obtained by the reaction to enter a settler for gas-solid separation, separating the separated reaction oil gas into dry gas, liquefied gas, gasoline, diesel oil and oil slurry through a separation system, and further separating propylene, propane and a first four-component carbon from the liquefied gas;
(2) the separated first four carbon components enter an aromatization reactor to contact and react with an aromatization catalyst, dry gas, liquefied gas and gasoline rich in aromatic hydrocarbon are separated from reaction products through a separation system, propylene, propane and a second four carbon components are further separated from the liquefied gas, and the aromatic hydrocarbon is further separated from the gasoline rich in aromatic hydrocarbon;
(3) and the second carbon four components enter an alkane dehydrogenation reactor, contact with a dehydrogenation catalyst to perform dehydrogenation reaction, and return the reaction product to the catalytic cracking reactor.
Preferably, the method further comprises the step (4): and (3) separating propane from dry gas in the steps (1) and (2) to obtain ethane, and introducing the ethane into a steam cracking furnace for steam cracking to generate ethylene and propylene.
In the method provided by the invention, the low-carbon olefin is ethylene and propylene.
Preferably, the raw material carbon four components come from a catalytic cracking unit and contain carbon four olefins and carbon four hydrocarbons, and the content of the olefins in the raw material carbon four components is more than 20 wt%. Preferably, the olefin content in the feed carbon four components is 40 wt% to 80 wt%.
In the method provided by the invention, the catalyst in the step (1) is a catalytic cracking catalyst and contains an MFI structure molecular sieve, a Y-type molecular sieve, clay and a binder, wherein based on the total weight of the catalyst, the content of the MFI structure molecular sieve is 5-60 wt%, preferably 10-50 wt%, the content of the Y-type molecular sieve is 1-40 wt%, preferably 1-30 wt%, the content of the clay is 10-70 wt%, preferably 15-45 wt%, and the content of the binder is 5-40 wt%, preferably 5-30 wt%.
In the method provided by the invention, the catalytic cracking reactor is one or more of a riser reactor, a turbulent bed reactor and a fast bed reactorA combined reactor; the operating conditions of the catalytic cracking reactor were: the average temperature is 550-700 ℃, the reaction pressure is 0.15-0.5 MPa, and the reaction space velocity is 2-600 h-1。
In the method provided by the invention, the gas-solid separation in the step (1) is carried out in a settler, a cyclone gas-solid separator is adopted to separate the catalyst and the reaction oil gas, and the separated catalyst is subjected to steam stripping in a steam stripper.
The method provided by the invention is characterized in that the aromatization reactor is a fixed bed reactor.
The method provided by the invention is characterized in that the aromatization catalyst contains a molecular sieve, a metal active component and a heat-resistant inorganic oxide carrier, wherein the metal active component is selected from one or more of rare earth elements, VIB, VIII, IIB and VIIB group elements, and the heat-resistant inorganic oxide is preferably silicon oxide and aluminum oxide.
In the method provided by the invention, the operation conditions of the aromatization reactor are as follows: the reaction temperature is 350-450 ℃, the reaction pressure is 0.20-2.0 MPa, and the reaction space velocity is 0.2-2 h-1。
In the method provided by the invention, the alkane dehydrogenation reactor is a fixed bed reactor; the operating conditions are that the reaction temperature is 550-650 ℃, the reaction pressure is 0.10-0.5 MPa, and the reaction space velocity is 0.2-2 h-1。
The dehydrogenation catalyst contains a molecular sieve, one or more metal active components and a heat-resistant inorganic oxide carrier, wherein the metal active components are selected from one or more of rare earth elements, IA, IIA, VIB, VIII, IB and VIIB elements, and the heat-resistant inorganic oxide carrier is silicon oxide and aluminum oxide.
Adopting a propane steam cracking furnace and an ethane steam cracking furnace or adopting an ethane-propane cracking furnace in the step (4); it is preferable to use a propane steam cracking furnace and an ethane steam cracking furnace. The steam cracking is carried out under the operating conditions that the reaction temperature is 780-850 ℃ and the retention time is 0.01-3 seconds.
In the method provided by the invention, two oil-gas separation systems are adopted in the steps (1) and (2). The separation system comprises a fractionating tower, an absorption stabilizing system and a gas separation device, wherein the separated oil gas enters a catalytic cracking fractionating tower, products below gasoline obtained from the top of the fractionating tower enter the absorption stabilizing system, the products of gasoline, dry gas and liquefied gas separated by the stabilizing system enter the gas separation device, and the propylene, propane and carbon are separated from the liquefied gas. The dry gas enters a split separation device to separate ethylene, ethane and other gases.
The aromatic hydrocarbon obtained in the step (2) is C6-C10 monocyclic aromatic hydrocarbon.
In the method provided by the invention, the raw material carbon four components refer to C4 components produced by a catalytic cracking unit, the catalytic cracking unit contacts a heavy oil raw material with a catalytic cracking catalyst, and the heavy oil raw material is subjected to cracking reaction under the catalytic cracking condition to obtain dry gas, liquefied gas, gasoline, diesel oil and oil slurry, wherein the liquefied gas is further separated to obtain C4 components. The heavy oil raw material is selected from one or a mixture of several of wax oil and atmospheric residue vacuum residue, or other organic compounds or hydrocarbons with carbon number more than 16. The catalytic cracking catalyst comprises an MFI structure molecular sieve, a Y-type molecular sieve, clay and a binder, wherein based on the total weight of the catalyst, the MFI structure molecular sieve accounts for 5-60 wt%, preferably 10-50 wt%, the Y-type molecular sieve accounts for 1-40 wt%, preferably 1-30 wt%, the clay accounts for 10-70 wt%, preferably 15-45 wt%, and the binder accounts for 5-40 wt%, preferably 5-35 wt%.
The operation conditions of the reactor in the catalytic cracking device are as follows: the average temperature is 500-700 ℃, the reaction pressure is 0.15-0.5 MPa, and the reaction space velocity is 2-600 h-1。
In the method provided by the invention, the same gas separation device is adopted in the dry gas separation in the step (4), and the gas separation device comprises a rectifying tower and accessory equipment.
In the method provided by the invention, one part of the C4 component separated by the first oil-gas separation system is introduced into the aromatization reactor, one part of the C4 component is returned to the catalytic cracking reactor for continuous reaction as the circulating C4, and the rest part of the C4 component can be thrown out as the C four product. The C4 outlet of the first oil-gas separation system is respectively communicated with the aromatization reactor, the catalytic cracking reactor and the carbon four product pipeline leading-out device.
One part of the C4 component separated by the second oil-gas separation system is introduced into the alkane dehydrogenation reactor, and the other part can be thrown out as a C four product. The C4 outlet of the second oil-gas separation system is respectively communicated with the alkane dehydrogenation reactor and the four-carbon product pipeline leading-out device.
The reaction product of the alkane dehydrogenation reactor can be partially thrown out besides returning to the catalytic cracking reactor for continuous reaction. And the product outlet of the alkane dehydrogenation reactor is also communicated with a four-carbon product pipeline leading-out device.
A reaction system for producing low-carbon olefin and aromatic hydrocarbon comprises a reaction device, a catalyst and a reactant flow; the reaction device comprises a catalytic cracking reactor, a regenerator, a first oil-gas separation system, a second oil-gas separation system, an aromatization reactor and an alkane dehydrogenation reactor which are communicated in sequence; the regenerator of the regenerator is communicated with the bottom of the catalytic cracking reactor, the upper part of the catalytic cracking reactor is provided with a settler and a gas-solid separation device, the spent agent outlet of the gas-solid separation device is communicated with the regenerator, the oil-gas outlet of the gas-solid separation device is communicated with the first oil-gas separation system, the C4 outlet of the first oil-gas separation system is communicated with the aromatization reactor, the outlet of the aromatization reactor is communicated with the second oil-gas separation system, the C4 outlet of the second oil-gas separation system is communicated with an alkane dehydrogenation reactor, and the product outlet of the alkane dehydrogenation reactor is communicated with the catalytic cracking reactor; the catalytic cracking catalyst circularly flows in the catalytic cracking reactor and the regenerator, the aromatization catalyst is filled in the aromatization reactor, and reactants are introduced through a raw material inlet of the catalytic cracking reactor and react in the reaction device.
Preferably, the reaction device further comprises a gas separation device and a steam cracking furnace; and the ethane outlet of the gas separation device is communicated with the ethane steam cracking furnace. The propane outlets of the first oil-gas separation system and the second oil-gas separation system are communicated with a propane steam cracking furnace.
Preferably, the catalytic cracking reactor is a riser reactor, the aromatization reactor is a fixed bed reactor, and the alkane dehydrogenation reactor is a fixed bed reactor.
The regenerator is a regenerator of various forms in the art that uses air or air mixed oxygen-rich gas to react with coke on the spent catalyst, burns off the coke on the spent catalyst to restore the activity of the spent catalyst, called regenerated catalyst, and raises the catalyst temperature to 600 ℃ to 760 ℃ in order to return to the reactor to bring heat and catalytic media to the reaction.
In the method and the reaction system for producing the low-carbon olefin and the aromatic hydrocarbon, the product outlets of the catalytic cracking reactor and the aromatization reactor can respectively adopt respective oil-gas separation systems, and can also share one set of oil-gas separation system. The oil-gas separation system can adopt one or a plurality of combinations of a fractionating tower, a rectifying tower, an absorption tower and a desorption tower.
FIG. 1 is a schematic flow diagram of the method provided by the present invention, as shown in FIG. 1, a carbon four raw material is preheated and enters a catalytic cracking reactor 1 through a line 7 to contact with a thermally regenerated catalyst from a regenerator 4 through a regenerated catalyst inclined tube 8 for reaction, the catalytic cracking reactor 1 is a riser reactor, the generated oil gas and catalyst enter a settler 11, a gas-solid separation device is arranged in the settler 11, the oil gas and the catalyst are separated in the settler 11, the separated spent catalyst with carbon enters a stripping section 10 to be stripped, and then enters the regenerator 4 through a spent catalyst inclined tube 9, the coke on the spent catalyst is burned off by air from a line 25 in the regenerator 4 to recover the activity, and then the air enters the bottom of the catalytic cracking reactor 1 through the regenerated catalyst inclined tube 8 to be recycled. The separated oil and gas enters the first oil and gas separation system 5 through a pipeline 12. Gasoline of the first oil-gas separation system is led out through a pipeline 15, diesel oil is led out through a pipeline 16, oil slurry is led out through a pipeline 26, propylene is led out through a pipeline 27, propane is led out through a pipeline 13 and enters a propane cracking furnace 32; the dry gas enters a gas separation device 35 through a pipeline 31, the gas separation device consists of a plurality of rectifying towers, H2-CH4 is led out through a pipeline 28 after separation, ethylene is led out through a pipeline 36, and ethane is led out through a pipeline 37 and enters an ethane cracking furnace 33. The first carbon four components separated by the first oil-gas separation system are led out through a pipeline 14 and enter the aromatization reactor 2, and a part of the first carbon four components are recycled to the catalytic cracking reactor through a pipeline 40.
The aromatization reactor is a fixed bed reactor, the second carbon four components and an aromatization catalyst are in contact reaction in the aromatization reactor, the reaction product enters a second oil-gas separation system through a pipeline 17, after separation, gasoline rich in aromatic hydrocarbon is obtained and is led out through a pipeline 20, propylene is led out through a pipeline 18, propane is led out through a pipeline 21 and enters a propane cracking furnace 32, dry gas is led out through a pipeline 34 and enters a gas separation device 35, and the second carbon four components are led out through a pipeline 19 and enter an alkane dehydrogenation and dehydrogenation reactor 3.
In the alkane dehydrogenation-dehydrogenation reactor 3, the four carbon components are in contact reaction with an alkane dehydrogenation catalyst, wherein the tetracarbon is dehydrogenated to generate tetracarbon olefin, and the reaction product is returned to the catalytic cracking reactor for reaction through a pipeline 24.
Propane separated by the first oil-gas separation system 5 enters the propane steam cracking furnace 32 through a pipeline 13, and propane separated by the second oil-gas separation system 6 enters the propane steam cracking furnace 32 through a pipeline 21 to generate propylene and ethylene. The ethane separated by the gas separation unit 35 is fed to the ethane cracking furnace 33 through a line 37 to produce ethylene and propylene.
The effects of the method for producing lower olefins and aromatic hydrocarbons and the reaction system provided by the present invention will be illustrated by the following examples and comparative examples, but the present invention is not limited thereto.
Comparative examples and examples, the C4 component used was a catalytic cracking separation column from Shijiazhuang, a division of petrochemical Co., Ltd., China, and the properties are shown in Table 1. The catalyst used is DMMC-1 catalyst produced by catalyst division of China petrochemical company Limited. The properties are shown in Table 2. The aromatization catalyst used is sold under the trademark DLP-XA and is produced by Shandong Daqi chemical technology Co. The dehydrogenation catalyst used was a commercial product number BDH-5, manufactured by Dalian Mittac.
Comparative examples 1 to 2
Comparative examples 1-2 adopt the process for producing ethylene and propylene by C4 recycle catalytic cracking as shown in figure 2, raw material carbon four components enter a catalytic cracking riser reactor through a line 7 after being preheated to contact with a thermal regeneration catalytic catalyst from a regenerator 4 through a regeneration catalyst inclined tube 8 for catalytic cracking reaction, the generated oil gas and catalyst flow upwards to enter a settler 11, a gas-solid separation device is arranged in the settler 11, the reaction oil gas and catalyst are separated in the settler 11, the separated spent catalyst with carbon enters the regenerator 4 through a spent catalyst inclined tube 9 after being stripped by a stripping section 10, coke on the spent catalyst is burnt by air from a line 25 in the regenerator 4 to restore the activity, and then the air enters the bottom of the riser reactor through the spent catalyst inclined tube 8 to circularly participate in the reaction. The separated oil and gas enters the first oil and gas separation system 5 through a pipeline 12. The first oil-gas separation system consists of a fractionating tower, a rectifying tower, an absorption tower and a desorption tower, gasoline obtained after separation is led out through a pipeline 15, diesel oil is led out through a pipeline 16, oil slurry is led out through a pipeline 26, propylene is led out through a pipeline 27, and propane is led out through a pipeline 13 and enters a propane cracking furnace 32 to generate propylene 23 and ethylene 22. The resulting dry gas is withdrawn via line 31 and passed to a gas separation unit 35, separated ethylene 28, other gases 36 and ethane 37, which is withdrawn via line 37 and passed to an ethane cracking furnace 33 to produce ethylene and propylene. The four carbon components are withdrawn via line 14, a portion of the four carbon components are returned to the catalytic cracking reactor via line 28, and the remaining four carbon components are withdrawn from the unit via line 20 as product.
The reaction conditions of comparative examples 1-2 are shown in Table 3, and the product yields are shown in Table 4.
Examples 1 to 2
The embodiment 1-2 adopts a reaction flow shown in the attached figure 1, specifically, (1) four components of raw material carbon are introduced into a catalytic cracking reactor and contact with a regenerated catalyst from a regenerator for reaction, an oil gas and catalyst mixture obtained by the reaction enters a settler for gas-solid separation, the separated reaction oil gas is separated into dry gas, liquefied gas, gasoline, diesel oil and oil slurry through a separation system, and further ethylene, propylene, aromatic hydrocarbon products and a first four components of carbon are separated; (2) the first four carbon components enter an aromatization reactor to contact and react with an aromatization catalyst, and dry gas, liquefied gas and gasoline rich in aromatic hydrocarbon are separated from reaction products through a separation system, so that ethylene, propylene, a second four carbon components and aromatic hydrocarbon products are further separated; (3) the second carbon four components enter an alkane dehydrogenation reactor, contact with a dehydrogenation catalyst to perform dehydrogenation reaction, and the reaction product returns to the catalytic cracking reactor; (4) and (2) separating the dry gas and the liquefied gas in the step (1) and (2) to obtain ethane and propane, and respectively introducing the ethane and the propane into an ethane steam cracking furnace and a propane steam cracking furnace for steam cracking to generate ethylene and propylene.
The reaction conditions of examples 1-2 are shown in Table 3, and the product yields are shown in Table 4.
As can be seen from table 4, the carbon four cycle ratios (carbon four feed/feedstock) of the examples of the carbon four feedstock a and the carbon four feedstock B are reduced by 0.2 and 0.3, respectively, compared to the comparative examples, and energy consumption is saved. In the product distribution, ethylene is respectively increased by 0.76 percent and 1.49 percent, propylene is respectively increased by 2.10 percent and 2.16 percent, and aromatic hydrocarbon (BTX) is respectively increased by 10.47 percent and 17.11 percent.
TABLE 1 composition of C4 components
Raw materials
C4 component A
C4 component B
Isobutane
26.18
38.75
N-butane
6.35
9.97
Butene-1
10.01
11.18
Isobutene
28.90
12.92
Cis-butenediol
16.52
14.06
Butene of trans-butene
12.03
13.12
TABLE 2 catalytic cracking catalyst composition and Properties
RE2O3
0.56
Al2O3
54
Physical Properties
Specific surface area, m2/g
100
Pore volume, cm3/g
0.176
Micropore volume, cm3/g
0.026
Apparent density, g/cm3
0.91
Sieving, according to
0-20μm
0.8
0-40μm
10.4
0-80μm
70.8
0-110μm
88.5
0-149μm
97.8
>149μm
2.2
APS,μm
64.3
Slightly reactive, wt% (520 ℃ C.)
55
TABLE 3
Item
Comparative example 1
Example 1
Comparative example 2
Example 2
Catalytic cracking reactor
C4 raw material
C4 component A
C4 component A
C4 component B
C4 component B
Reaction pressure/MPa
0.2
0.2
0.28
0.28
Reaction temperature/. degree.C
620
620
650
650
Regenerator temperature/. degree.C
690
690
710
710
Ratio of agent to oil
15
15
20
20
Reaction space velocity/h-1
10
10
50
50
Atomized steam/%)
25
25
15
15
Carbon to four cycle ratio
0.5
0.2
0.4
0.2
Aromatization reactor
Reaction pressure/MPa
/
1.1
/
1.3
Reaction temperature/. degree.C
/
380
/
420
Reaction space velocity/h-1
/
1.0
/
1.3
Alkane dehydrogenation reactor
Reaction pressure/MPa
/
0.3
/
0.3
Reaction temperature/. degree.C
/
600
/
620
Reaction space velocity/h-1
/
0.5
/
1.1
Ethane cracking reactor
Temperature/. degree.C
830
830
830
830
pressure/MPa
0.13
0.13
0.13
0.13
Atomized steam/%)
60
60
60
60
Propane cracking reactor
Temperature/. degree.C
815
815
815
815
pressure/MPa
0.13
0.13
0.13
0.13
Atomized steam/%)
60
60
60
60
TABLE 4
Example numbering
Comparative example 1
Example 1
Comparative example 2
Example 2
Product yield
H2-C2
5.77
8.12
7.94
9.38
C3-C4
76.38
54.51
86.26
72.73
C5+ gasoline
13.51
31.61
3.04
14.27
Diesel oil
0.77
1.31
0.42
0.75
Heavy oil
0.02
0.30
0.12
0.29
Coke
3.36
3.64
2.02
2.19
Ethylene
3.47
4.96
3.99
4.75
Propylene (PA)
16.59
18.75
8.58
10.68
BTX
1.26
18.37
1.34
11.81
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