Reaction system and process for preparing low-carbon olefin

Abstract

The invention provides a reaction system and process for preparing low-carbon olefin, and belongs to the field of petroleum processing. The reaction system for preparing the low-carbon olefins comprises a heavy hydrocarbon supply end, a first catalytic cracking reactor, a second catalytic cracking reactor, a regenerator, an incineration cracking furnace, a steam stripping pipe and a separation device, the incinerator is provided with a shell pass and a tube pass; the top of the first catalytic cracking reactor and the top of the second catalytic cracking reactor are communicated with a steam stripping pipe; a gas phase outlet of the steam stripping pipe is communicated with the separation device; a solid phase outlet of the steam stripping pipe is communicated with the regenerator; a gas phase outlet of the regenerator is communicated with a shell pass of the incineration cracking furnace; and a low-carbon alkane outlet of the separation device is communicated with a tube pass of the incineration cracking furnace. The CO combustion heat in the regenerated flue gas is supplied to high-temperature cracking of ethane and propane in the reaction oil gas, so that the yield of low-carbon olefin is further increased.

Description

Technical Field

[0001] This invention belongs to the field of petroleum processing, specifically relating to a reaction system and process for producing low-carbon olefins. Background Technology

[0002] Low-carbon olefins are important basic organic chemical raw materials with wide applications in various fields. For example, ethylene is mainly used to produce materials such as polyethylene, ethylene oxide, and polyvinyl chloride, while propylene can be used to produce chemical products such as acrylonitrile, propylene oxide, and acetone.

[0003] Currently, the typical process for producing low-carbon olefins is naphtha steam cracking, which has low yields of ethylene and propylene, making it difficult to meet the growing market demand. In response, CN1490287A discloses a method for producing low-carbon olefins using a mixture of hydrocarbons containing C4 or C5 monoolefins as feedstock. The hydrocarbon mixture reacts with a catalyst in a fixed-bed reactor, resulting in higher yields of ethylene and propylene.

[0004] Although existing methods for producing low-carbon olefins from olefin feedstocks have significantly improved the yield of low-carbon olefins, the problem of low ethylene and propylene content in the products still exists. Furthermore, the flue gas generated during catalyst regeneration contains some heat energy that is not being fully utilized. Summary of the Invention

[0005] The purpose of this invention is to provide a method for increasing the yield of low-carbon olefins, which utilizes the heat from an incinerator to crack ethane and propane, thereby further increasing the yield of low-carbon olefins.

[0006] On one hand, the technical solution of the present invention provides a reaction system for producing low-carbon olefins, including an olefin component supply end, a heavy hydrocarbon supply end, a first catalytic cracking reactor, a second catalytic cracking reactor, a regenerator, an incineration cracking furnace, a stripping pipe, and a separation device; the incinerator has a shell side and a tube side; the olefin component supply end is connected to the first catalytic cracking reactor; the heavy hydrocarbon supply end is connected to the bottom of the second catalytic cracking reactor; the top of the first catalytic cracking reactor is connected to the stripping pipe, and the top of the second catalytic cracking reactor is connected to the stripping pipe; the gas phase outlet of the stripping pipe is connected to the separation device; the solid phase outlet of the stripping pipe is connected to the regenerator; the gas phase outlet of the regenerator is connected to the shell side of the incineration cracking furnace; the separation device contains low-carbon alkane (C 1～4 The outlet tube of the alkane (preferably propane or ethane) is connected to the incineration pyrolysis furnace.

[0007] As a preferred technical solution, the olefin fraction outlet (C5) of the separation device + The olefin fraction is connected to the bottom of the first catalytic cracking reactor.

[0008] As a preferred technical solution, the solid phase outlet of the regenerator is connected to the bottom of the first catalytic cracking reactor and the bottom of the second catalytic cracking reactor, respectively.

[0009] As a preferred technical solution, the system further includes a settling device, which contains a first cyclone separator and a gas collection chamber. The gas collection chamber is located at the gas phase outlet of the first cyclone separator, and the gas phase outlet of the stripping pipe is connected to the gas collection chamber. The gas phase outlet of the cyclone separator is connected to the gas collection chamber.

[0010] As a preferred technical solution, the separation device includes a fractionation tower and an olefin separation unit (using equipment and processes known in the prior art); the gas collecting chamber is connected to the fractionation tower; the C5 of the fractionation tower... + The distillate outlet is connected to an olefin separation unit; the C of the olefin separation unit 5～12 The olefin fraction outlet is connected to the bottom of the first catalytic cracking reactor.

[0011] As a preferred technical solution, the system further includes a second cyclone separator and an energy recovery unit; the gas phase outlet of the regenerator is connected to the second cyclone separator; the gas phase outlet of the second cyclone separator, the energy recovery unit, and the shell side of the incinerator are sequentially connected.

[0012] As a preferred technical solution, the system also includes a waste heat boiler and a flue gas desulfurization and denitrification system; the shell side of the incinerator, the waste heat boiler, and the flue gas desulfurization and denitrification system are connected in sequence.

[0013] On the other hand, the present invention provides a process for producing low-carbon olefins using any of the above-mentioned reaction systems, comprising the steps of: in a first catalytic cracking reactor, olefin components are contacted with a catalyst to carry out catalytic cracking reaction I, obtaining a first mixture, the first mixture containing a first reactant gas and a first catalyst to be regenerated; in a second catalytic cracking reactor, heavy hydrocarbons are contacted with a catalyst to carry out catalytic cracking reaction II, obtaining a second mixture, the second mixture containing a second reactant gas and a second catalyst to be regenerated; after the first mixture and the second mixture are mixed, they are subjected to gas-solid separation I to obtain a first catalyst to be regenerated, a second catalyst to be regenerated, hydrogen, and low-carbon alkanes (C 1～4 Alkanes), low-carbon olefins (C 1～4 (olefins) and C5 + Fractions (fractions with more than 5 carbon atoms, C5 as described in this invention) + The initial boiling point of the fraction is greater than 20℃ and less than 140℃; the C5 +The fraction undergoes a second separation to obtain an olefin fraction, which enters the first catalytic cracking reactor. The first and second spent catalysts are stripped through the stripping pipe and then enter the regenerator for incomplete regeneration (oxygen-deficient, for CO production), yielding regenerated flue gas and regenerated catalyst. The regenerated flue gas enters the shell side of the incineration cracking furnace for combustion (combustion reaction occurs in the shell side of the incinerator, providing heat to the tube side). The low-carbon alkanes (preferably ethane, propane, and butane) enter the tube side of the incineration cracking furnace and undergo a cracking reaction to obtain olefin-rich cracked gas (CO combustion provides heat, and a high-temperature cracking reaction occurs in the tube side / furnace tubes of the incinerator, yielding low-carbon olefin-rich gas).

[0014] As a preferred technical solution, the temperature of the regenerated flue gas is higher than 300°C, more preferably higher than 500°C, and even more preferably higher than 600°C.

[0015] As a preferred technical solution, the concentration of CO in the regenerated flue gas is greater than 1 wt.%, preferably greater than 3 wt.%, and more preferably 7 wt.%.

[0016] As a preferred technical solution, the regenerated catalyst enters both the first catalytic cracking reactor and the second catalytic cracking reactor. Alternatively, the regenerated catalyst is returned to the first catalytic cracking reactor; or, the first catalyst to be regenerated is mixed with the regenerated catalyst and then returned to the second catalytic cracking reactor.

[0017] As a preferred technical solution, the conditions for the catalytic cracking reaction I include:

[0018] The reaction temperature is 550–800℃, preferably 580–750℃, and more preferably 600–700℃;

[0019] The reaction pressure is 0.01–1 MPa, preferably 0.1–0.8 MPa, and more preferably 0.2–0.5 MPa;

[0020] The reaction time is 0.05–10 s, preferably 0.1–5 s, and more preferably 0.2–2 s;

[0021] The catalyst and the olefin component are in a weight ratio of (5-50):1, preferably (10-35):1, and more preferably (12-30):1. The olefin component includes olefin feedstock and / or olefin fraction.

[0022] As a preferred technical solution, the olefin component is a gas-phase feed.

[0023] As a preferred technical solution, the olefin component contains 50 wt.% to 100 wt.%, preferably 80 wt.% to 100 wt.%.

[0024] As a preferred technical solution, the olefin component has an olefin content of C4 to C5. 12 Olefins, preferably C4-C6 olefins.

[0025] As a preferred technical solution, the conditions for the catalytic cracking reaction II include:

[0026] The reaction temperature is 500–600℃, preferably 530–580℃;

[0027] The reaction pressure is 0.01–1 MPa, preferably 0.05–1 MPa;

[0028] The reaction time is 0.01–80 s, preferably 0.1–60 s;

[0029] The weight ratio of the catalyst to the heavy hydrocarbon is (1-100):1, preferably (3-50):1.

[0030] As a preferred technical solution, the heavy hydrocarbon is selected from at least one of vacuum gas oil, atmospheric gas oil, coking gas oil, deasphalted oil, vacuum residue, atmospheric residue, heavy aromatics raffinate, coal liquefaction oil, oil sands oil, and shale oil.

[0031] As a preferred technical solution, the conditions for the pyrolysis reaction include:

[0032] The reaction temperature is 750–950℃, preferably 770–900℃; that is, the heat generated by the combustion of regenerated flue gas heats the low-carbon alkanes (preferably ethane and propane) obtained in the tube side (furnace tube) of the incineration pyrolysis furnace to 750–950℃, preferably 770–900℃.

[0033] As a preferred technical solution, the combustion conditions of the regenerated flue gas include: CO in the regenerated flue gas comes into contact with oxygen-containing gas and undergoes a combustion reaction; the oxygen content in the oxygen-containing gas is 20v% to 100v%, preferably 21v% to 35v%; the temperature is 500℃ to 1150℃; the pressure is 0.01MPa to 1MPa; and the ratio of oxygen-containing gas to CO is 1:1.8 to 1:2 (molar ratio) based on pure oxygen and pure CO.

[0034] The residence time of the low-carbon alkane (preferably ethane or propane) is 0.1–2.5 s, preferably 0.1–2 s, and more preferably 0.2–1.5 s;

[0035] Preferably, dilution steam is injected into the low-carbon alkane (preferably ethane or propane), wherein the ratio of water vapor to ethane and propane is 0.1–2, preferably 0.2–1.5.

[0036] As a preferred technical solution, the shell-side temperature of the incineration pyrolysis furnace is 1000–1250°C.

[0037] As a preferred technical solution, the temperature of the incineration pyrolysis furnace shell (furnace) is controlled by the flow rate of the supplementary fuel, which is preferably natural gas and / or methane-rich gas.

[0038] As a preferred technical solution, the catalyst is a mesoporous molecular sieve catalyst and / or a small-pore molecular sieve catalyst; the mesoporous molecular sieve catalyst is selected from one or more of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, and ZSM-48. The small-pore molecular sieve can be a SAPO molecular sieve, and further, the SAPO molecular sieve can be selected from one or more of SAPO-34, SAPO-11, and SAPO-47.

[0039] All of the above-mentioned raw materials used in this invention can be prepared in-house or purchased commercially; this invention does not impose any particular limitations on them.

[0040] This invention utilizes the heat from the combustion of CO in regenerated flue gas to power the high-temperature cracking of ethane and propane in the reaction oil and gas, thereby further increasing the production of low-carbon olefins. The low-value-added ethane and propane products from catalytic cracking are introduced into a cracking furnace for cracking to obtain a stream rich in ethylene and propylene. Furthermore, the CO from the regenerated flue gas powers the cracking furnace, thus reducing energy consumption while increasing the production of low-carbon olefins. Attached Figure Description

[0041] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0042] Figure 1 This is a schematic diagram of one embodiment of the catalytic conversion system for producing low-carbon olefins according to the present invention.

[0043] In the diagram, 101 is the first catalytic cracking reactor, 102 is the second catalytic cracking reactor, 3 is the riser, 7 is the incineration cracking furnace, 9 is the stripping pipe, 11 is the horizontal pipe, 12 is the settling tank, 13 is the first cyclone separator, 14 is the gas collection chamber, 15 is the waiting inclined tube, 16 is the regenerator, 20 is the main oil and gas pipeline, 21 is the fractionation tower, 30 is the olefin separation unit, 32 is the second cyclone separator, 33 is the energy recovery unit, 39 is the waste heat boiler, and 41 is the flue gas desulfurization and denitrification system.

[0044] Pipelines 1, 2, 3, 4, 5, 6, 8, 10, 17, 18, 19, 22, 23, 24, 25, 26, 27, 28, 29, 31, 34, 35, 36, 37, 38, 40, 42. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0046] The tools used in the various embodiments of the present invention.

[0047] The following is a detailed description of an embodiment of the present invention.

[0048] The present invention is further described in detail below through examples, but the invention is not limited thereto. All raw materials used in the examples are commercially available. The catalyst used in the examples and comparative examples is commercially available as TCC-1, produced by Sinopec Catalyst Co., Ltd., Qilu Branch.

[0049] The properties of the heavy oil used in the embodiments and comparative examples of this invention are shown in Table 1.

[0050] Table 1 Heavy hydrocarbon components

[0051]

[0052] Example 1

[0053] The catalytic conversion system for producing low-carbon olefins consists of a first catalytic cracking reactor 101 (fluidized bed reactor), a second catalytic cracking reactor 102 (fluidized bed reactor), a settling tank 12, an incineration cracking furnace 7, a regenerator 16, a fractionation tower 21, an olefin separation unit 30 (equipment and process known and commonly used in this technical field), a second cyclone separator 32, an energy recovery unit 33, a waste heat boiler 39, and a flue gas desulfurization and denitrification system 41.

[0054] The upper opening of the riser 3 is connected to the bottom of the first catalytic cracking reactor 101.

[0055] The top of the first catalytic cracking reactor 101 is connected to the stripping pipe 9.

[0056] The top of the second catalytic cracking reactor 102 is connected to the stripping pipe 9.

[0057] The solid phase outlet of stripping pipe 9 is connected to regenerator 16.

[0058] The settling tank 12 is equipped with a first cyclone separator 13 and a gas collecting chamber 14. The gas collecting chamber 14 is located at the gas phase outlet of the first cyclone separator 13. The gas phase outlet of the stripping pipe 9 is connected to the cyclone separator 13. The gas phase outlet of the cyclone separator 13, the gas collecting chamber 14, and the fractionation tower 21 are connected in sequence.

[0059] The regenerated flue gas outlet (gas phase outlet) of the regenerator is connected to the second cyclone separator 32. The gas phase outlet of the second cyclone separator 32, the energy recovery unit 33, the furnace of the incineration pyrolysis furnace 7, the waste heat boiler 39, and the flue gas desulfurization and denitrification system 41 are connected in sequence.

[0060] like Figure 1 As shown, in the first catalytic cracking reactor 101, the pre-lifting medium (steam, dry gas, or a mixture thereof) enters the riser 3 via pipeline 1, and the preheated regenerated catalyst enters the riser 3 via pipeline 24. Under the lifting action of the pre-lifting medium, the preheated regenerated catalyst rises into the first catalytic cracking reactor 101. The olefin-rich (C20-C40) catalyst from pipeline 2... 5～12 The components are injected from the bottom into the first catalytic cracking reactor 101. The olefin-rich components come into contact with the catalyst and / or preheated regenerated catalyst, undergoing catalytic cracking reaction I. The first mixture after the reaction enters the first cyclone separator in the settling tank 12 through the horizontal pipe 11. After gas-solid separation in the first cyclone separator, the first reacted oil and gas and the first catalyst to be regenerated are obtained. The first catalyst to be regenerated is introduced into the stripping pipe 9 through the pipeline 10, and the first reacted oil and gas enters the gas collecting chamber 14.

[0061] In the second catalytic cracking reactor 102, heavy hydrocarbons (heavy feedstock oil, composition as shown in Table 1) from pipeline 5, atomized steam from pipeline 6, and preheated regenerated catalyst from pipeline 19 are mixed and injected into the second catalytic cracking reactor 102 from the bottom. The heavy hydrocarbons come into contact with the catalyst and / or the preheated regenerated catalyst, and catalytic cracking reaction II occurs. The second mixture after the reaction is separated by the first cyclone separator 13 in the settling tank 12 to obtain the second reaction oil gas (containing liquid phase products) and the second catalyst to be regenerated. The second catalyst to be regenerated enters the stripping pipe 9, and the second reaction oil gas enters the gas collecting chamber 14.

[0062] In stripping pipe 9, the first catalyst to be regenerated and the second catalyst to be regenerated come into contact with stripping steam from pipeline 25 for stripping. After stripping, the first catalyst to be regenerated and the second catalyst to be regenerated enter the regenerator 16 through the stripping inclined pipe 15.

[0063] The first and second reaction oil gases from the gas collecting chamber 14 enter the fractionation tower 21 via the large oil and gas pipeline 20 for the first separation process. The separated ethane and propane are introduced into the furnace tubes of the incineration cracking furnace 7 via pipeline 22 as cracking feedstock; the separated hydrogen and methane are led out via pipeline 42; the separated ethylene is led out via pipeline 23; the separated propylene is led out via pipeline 26; the separated butane is led out via pipeline 28; and the separated butene is led out via pipeline 27 (not returned to the catalytic conversion reactor 101), although butene can also be returned to the catalytic conversion reactor 101 for further reaction. Catalytic cracking distillate oil with an initial boiling point greater than 20°C and less than 140°C is introduced via pipeline 29 into the olefin separation unit 30 for the second separation process. After separation, olefin-free and olefin-rich streams are obtained respectively: the olefin-free stream is led out via pipeline 31, and the olefin-rich stream is returned to the catalytic conversion reactor 101 via pipeline 4 as feedstock for further reaction.

[0064] Inside regenerator 16, the main air entering via pipeline 17 comes into contact with the first and second catalysts to be regenerated, removing coke from the catalysts and regenerating the deactivated catalysts to obtain regenerated catalysts. Supplementary fuel entering via pipeline 18 provides heat to the regenerated catalysts, resulting in preheated regenerated catalysts and regenerated flue gas. The preheated regenerated catalyst is divided into two streams, entering catalytic conversion reactor 101 via pipeline 24 and catalytic cracking reactor 102 via pipeline 19, respectively.

[0065] The regenerated flue gas enters the cyclone separator 32 via pipeline 35, then enters the energy recovery unit 33 via pipeline 36, and then enters the furnace of the incineration pyrolysis furnace 7 via pipeline 37 for combustion, providing heat for the reaction inside the furnace tubes. The exhaust gas after combustion enters the waste heat boiler 39 via pipeline 38, and then enters the flue gas desulfurization and denitrification system 41 via pipeline 40. Ethane and propane in the furnace tubes of the incineration pyrolysis furnace 7 react with water vapor from pipeline 34, and the resulting pyrolysis gas containing ethylene and propylene is led out via pipeline 8.

[0066] Example 2

[0067] The process of producing cracked gas using the catalytic conversion system for preparing low-carbon olefins as described in Example 1.

[0068] In the first catalytic cracking reactor 101, 1-pentene is contacted with the regenerated TCC-1 catalyst that has been preheated to 650°C to carry out catalytic cracking reaction I to obtain the first mixture. The first mixture undergoes gas-solid separation in the first cyclone separator. The gas phase (first reaction oil and gas) enters the gas collection chamber 14, and the solid phase (first waiting catalyst) enters the regenerator 16 through the waiting inclined tube 15.

[0069] In the second catalytic cracking reactor 102, heavy oil comes into contact with regenerated TCC-1 catalyst preheated to 650°C, and catalytic cracking reaction I occurs to obtain a second mixture, which includes second reaction oil gas (containing light oil) and second spent catalyst.

[0070] The first and second spent catalysts enter the regenerator 16 and undergo coke regeneration with air at 650°C to obtain regenerated TCC-1 catalyst and regenerated flue gas. The regenerated flue gas enters the furnace of the incineration pyrolysis furnace 7 for combustion.

[0071] The first and second reaction oil gases (containing light oil) are mixed and fed into fractionation tower 21 for fractionation according to their boiling range, yielding ethane, propane, ethylene, propylene, butene, and catalytic cracking distillate (20℃ < initial boiling point < 140℃). Ethane and propane are introduced into the furnace tubes of incineration cracking furnace 7 to contact with steam for steam cracking, yielding cracked gas containing ethylene and propylene. The catalytic cracking distillate is introduced via pipeline 29 to olefin separation unit 30, where it is separated into an olefin-free stream (leading out via pipeline 31) and an olefin-rich stream (olefin content 80 wt%). The olefin-rich stream is returned to the bottom of catalytic conversion reactor 101 via pipeline 4.

[0072] The reaction conditions and product distribution of this embodiment are shown in Table 2.

[0073] Comparative Example

[0074] The comparative experiment was conducted in accordance with Example 1, except that ethane and propane were not introduced into the incineration pyrolysis furnace for steam cracking. The reaction conditions and product distribution are shown in Table 2.

[0075] Table 2 Reaction conditions and products

[0076]

[0077]

[0078] As shown in Table 2, coupling the production of low-carbon olefins from light feedstocks with heavy oil catalytic cracking improved the yields of ethylene, propylene, and butene in the resulting reaction oil and gas.

[0079] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88, ..., 69-71, and 70-71. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0080] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A reaction system for producing low-carbon olefins, including an olefin component supply end, a heavy hydrocarbon supply end, a first catalytic cracking reactor, a second catalytic cracking reactor, a regenerator, an incineration cracking furnace, a stripping pipe, and a separation unit; The incinerator has a shell side and a tube side; The olefin component supply end is connected to the first catalytic cracking reactor; The heavy hydrocarbon supply end is connected to the bottom of the second catalytic cracking reactor; The top of the first catalytic cracking reactor is connected to the stripping pipe. The top of the second catalytic cracking reactor is connected to the stripping pipe; The gas phase outlet of the stripping pipe is connected to the separation unit; The solid phase outlet of the stripping pipe is connected to the regenerator; The gas phase outlet of the regenerator is connected to the shell side of the incineration pyrolysis furnace; C of the separation device 1～4 The alkane outlet is connected to the tube side of the incineration cracking furnace.

2. The reaction system for producing low-carbon olefins according to claim 1, characterized in that, The olefin fraction outlet of the separation unit is connected to the bottom of the first catalytic cracking reactor; And / or, the solid phase outlet of the regenerator is connected to the bottom of the first catalytic cracking reactor and the bottom of the second catalytic cracking reactor, respectively; And / or, the system further includes a settling device, which has a first cyclone separator and a gas collection chamber, the gas collection chamber being located at the gas phase outlet of the first cyclone separator; The gas phase outlet of the stripping pipe is connected to the gas collection chamber; the gas phase outlet of the cyclone separator is connected to the gas collection chamber.

3. The reaction system for producing low-carbon olefins according to claim 1, characterized in that, The separation unit includes a fractionation tower and an olefin separation unit; The gas collecting chamber is connected to the fractionation tower; C5 of the fractionation tower + The distillate outlet is connected to an olefin separation unit; C of the olefin separation unit 5～12 The olefin fraction outlet is connected to the bottom of the first catalytic cracking reactor.

4. The reaction system for producing low-carbon olefins according to claim 1, 2, or 3, characterized in that, The system also includes a second cyclone separator and an energy recovery unit; The gas phase outlet of the regenerator is connected to the second cyclone separator; The gas phase outlet of the second cyclone separator, the energy recovery unit, and the shell side of the incinerator are connected in sequence; And / or, the system further includes a waste heat boiler and a flue gas desulfurization and denitrification system; the shell side of the incinerator, the waste heat boiler, and the flue gas desulfurization and denitrification system are connected in sequence.

5. A process for producing low-carbon olefins using the reaction system of any one of claims 1-4, characterized in that, Including the following steps: In the first catalytic cracking reactor, the olefin component comes into contact with the catalyst to carry out catalytic cracking reaction I, and a first mixture is obtained, wherein the first mixture contains a first reacted oil and gas and a first catalyst to be generated; In the second catalytic cracking reactor, heavy hydrocarbons come into contact with the catalyst to carry out catalytic cracking reaction II, and a second mixture is obtained. The second mixture contains the second reaction oil and gas and the second ungenerated catalyst. After the first mixture and the second mixture are mixed, they are subjected to gas-solid separation I to obtain the first catalyst to be regenerated, the second catalyst to be regenerated, hydrogen, low-carbon alkanes, low-carbon olefins, and C5. + Fraction; the C5 + The fraction undergoes a second separation to obtain an olefin fraction, which then enters the first catalytic cracking reactor. The first and second catalysts are stripped through the stripping pipe and then enter the regenerator for incomplete regeneration to obtain regenerated flue gas and regenerated catalyst. The regenerated flue gas enters the shell side of the incineration pyrolysis furnace for combustion. The low-carbon alkanes enter the tube side of the incineration pyrolysis furnace and undergo a pyrolysis reaction to obtain pyrolysis gas containing olefins.

6. The process for producing low-carbon olefins according to claim 5, characterized in that, The combustion conditions of the regenerated flue gas include: CO in the regenerated flue gas comes into contact with oxygen-containing gas and undergoes a combustion reaction; preferably, the oxygen content in the oxygen-containing gas is 20v% to 100v%, more preferably 21v% to 35v%; preferably, the temperature is 500℃ to 1150℃; the pressure is 0.01MPa to 1MPa; preferably, the ratio of oxygen-containing gas to CO, based on pure oxygen and pure CO, is 1:1.8 to 1:2 (molar ratio); And / or, the temperature of the regenerated flue gas is higher than 300°C, preferably higher than 500°C, and more preferably higher than 600°C; And / or, in the regenerated flue gas, the concentration of CO is greater than 1 wt.%, preferably greater than 3 wt.%, and more preferably 7 wt.%; And / or, the regenerated catalyst enters the first catalytic cracking reactor and the catalytic cracking reactor.

7. The process for producing low-carbon olefins according to claim 5 or 6, characterized in that, The conditions for the catalytic cracking reaction I include: The reaction temperature is 550–800℃, preferably 580–750℃, and more preferably 600–700℃; The reaction pressure is 0.01–1 MPa, preferably 0.1–0.8 MPa, and more preferably 0.2–0.5 MPa; The reaction time is 0.05–10 s, preferably 0.1–5 s, and more preferably 0.2–2 s; The weight ratio of the catalyst to the olefin component is (5-50):1, preferably (10-35):1, and more preferably (12-30):

1. The olefin component includes olefin feedstock and / or olefin fraction. And / or, the olefin component is a gas-phase feed; And / or, in the olefin component, the olefin content is 50 wt.% to 100 wt.%, preferably 80 wt.% to 100 wt.%; And / or, the olefin component has an olefin of C4 to C6. 12 Olefins, preferably C4-C6 olefins.

8. The process for producing low-carbon olefins according to any one of claims 5-7, characterized in that, The conditions for the catalytic cracking reaction II include: The reaction temperature is 500–600℃, preferably 530–580℃; The reaction pressure is 0.01–1 MPa, preferably 0.05–1 MPa; The reaction time is 0.01–80 s, preferably 0.1–60 s; The weight ratio of the catalyst to the heavy hydrocarbon is (1-100):1, preferably (3-50):1; And / or, the heavy hydrocarbon is selected from at least one of vacuum gas oil, atmospheric gas oil, coking gas oil, deasphalted oil, vacuum residue, atmospheric residue, heavy aromatics raffinate, coal liquefaction oil, oil sands oil, and shale oil.

9. The process for producing low-carbon olefins according to any one of claims 5-8, characterized in that, The conditions for the pyrolysis reaction include: The reaction temperature is 750–950℃, preferably 770–900℃; The residence time of the low-carbon alkane is 0.1 to 2.5 s, preferably 0.1 to 2 s, and more preferably 0.2 to 1.5 s; Preferably, dilution steam is injected into the low-carbon alkane, wherein the ratio of water vapor to ethane and propane is 0.1–2, preferably 0.2–1.

5. And / or, the shell-side temperature of the incineration pyrolysis furnace is 1000–1250°C.

10. The process for producing low-carbon olefins according to any one of claims 5-9, characterized in that, The catalyst is a mesoporous molecular sieve catalyst and / or a small-pore molecular sieve catalyst; the mesoporous molecular sieve catalyst is selected from one or more of ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, and ZSM-48; The small-pore molecular sieve can be a SAPO molecular sieve, and further, the SAPO molecular sieve can be selected from one or more of SAPO-34, SAPO-11, and SAPO-47.

Images