A device and control method for directly preparing gasoline hydrocarbons using exhaust gas from power plants

Abstract

The present invention relates to the technical field of chemical process for producing gasoline, and discloses a device and control method for directly preparing gasoline hydrocarbons by using exhaust gas from power plants, including a carbon dioxide purification device, a gas mixer, a hydrogen production device, a raw hydrogen regulating gate, a gas activator, a gas compressor, a heat exchanger, a first cooler, a synthesis cooler, a high-pressure flash tank, a heater, a gas separation device, a low-pressure flash tank, a pressure reducing valve, a light removal tower, a condenser, etc. The present invention directly synthesizes gasoline and other products through a reactor at a certain temperature and pressure after mixing carbon dioxide and hydrogen. This device for directly synthesizing gasoline by hydrogenating carbon dioxide has the advantages of simple equipment, short reaction process, low energy consumption, high efficiency, clean and environmental protection, and low equipment investment. The synthesized gasoline can be directly used as fuel oil or as blended gasoline, which is helpful for recycling carbon resources and reducing dependence on fossil energy, and achieving the purpose of carbon reduction and energy storage.

Description

Technical Field

[0001] The invention relates to the technical field of chemical process for producing gasoline, and in particular to a device and a control method for directly preparing gasoline hydrocarbons by utilizing exhaust gas from power plants. Background Art

[0002] Thermal power generation consumes a large amount of coal resources. The flue gas produced by the combustion of coal in power plant boilers contains high concentrations of carbon dioxide. If it is directly discharged, it will cause serious environmental problems. Environmental protection and the reduction of greenhouse gas emissions are increasingly gaining attention. How to rationally utilize carbon dioxide and convert it into usable renewable energy and use it is an effective way to solve environmental and carbon emissions. It is of great significance to use the exhaust gas of power plants to convert the carbon dioxide in the exhaust gas into liquid fuel or high value-added chemicals through purification and chemical synthesis methods. It is not only conducive to reducing carbon emissions, but also conducive to the comprehensive utilization of carbon dioxide resources.

[0003] After years of research and exploration by scientists, the reaction pathways for synthesizing gasoline hydrocarbons (C2+ hydrocarbons) by hydrogenating carbon dioxide are mainly divided into two categories: methanol intermediate pathway and non-methanol intermediate pathway. In the methanol intermediate pathway, carbon dioxide reacts with copper-zinc catalyst to produce methanol, and the product methanol is further dehydrated and converted into other hydrocarbon compounds; in the non-methanol intermediate pathway, carbon dioxide first reacts with reverse water gas shift (RWGS) to produce carbon monoxide, and carbon monoxide is then catalytically hydrogenated by Fischer-Tropsch synthesis (FTS) to produce gasoline hydrocarbons. This preparation method will cause a waste of resources during the synthesis process, and the process of preparing gasoline hydrocarbons is complicated and easy to cause environmental pollution.

[0004] Therefore, how to provide a device that can utilize the exhaust gas from power plants to directly synthesize gasoline hydrocarbons in one step is a technical problem that needs to be solved. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a device and a control method for directly preparing gasoline hydrocarbons by utilizing the exhaust gas of a power plant. The carbon dioxide in the exhaust gas of the power plant is catalytically hydrogenated to directly synthesize gasoline hydrocarbons, and the gasoline hydrocarbons are obtained by a low-temperature flash evaporation method. At the same time, the parameters of the synthesis process are analyzed through big data, and a synthesis control optimization model is established using an intelligent algorithm to improve the synthesis efficiency and greatly reduce the energy consumption of the synthesis process.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a device for directly preparing gasoline hydrocarbons using exhaust gas from a power plant, comprising a carbon dioxide purification and refining device and a hydrogen production device, wherein the outlet pipeline of the carbon dioxide purification and refining device is connected to a gas mixer through a carbon dioxide regulating valve; the outlet pipeline of the hydrogen production device is connected to a cold end outlet of a first heat exchanger through a raw hydrogen regulating valve, the hot end outlet of the first heat exchanger is connected to an inlet of a gas mixer, the outlet of the gas mixer is connected to an inlet of a first gas compressor, the outlet of the first gas compressor is connected to an inlet of a gas activator, and the outlet of the gas activator is connected to a cold end inlet of a second heat exchanger;

[0007] The hot end outlet of the second heat exchanger is connected to the top inlet of the synthesis reactor, the bottom outlet pipe of the synthesis reactor is connected to the hot end inlet of the first heat exchanger, the cold end outlet pipe of the first heat exchanger is connected to the hot side outlet of the first cooler, and the cold side outlet of the first cooler is connected to the hot side inlet of the synthesis cooler;

[0008] The cold side outlet of the synthesis cooler is connected to the inlet of the high-pressure flash tank, the top gas outlet pipeline of the high-pressure flash tank is connected to the cold side outlet of the heater, the hot side outlet of the heater is connected to the gas separation device, the recovery pipeline of the gas separation device is connected to the inlet of the second gas compressor, the outlet pipeline of the second gas compressor is connected to the outlet pipeline of the first gas compressor, and the discharge pipeline of the gas separation device is connected to the tail gas main pipe through the first pressure reducing valve;

[0009] The high-pressure flash tank is connected to the low-pressure flash tank through the second pressure reducing valve, the gas phase outlet pipeline at the top of the low-pressure flash tank is connected to the tail gas main pipe through the third pressure reducing valve, and the oil phase outlet pipeline of the low-pressure flash tank is connected to the inlet of the first light removal tower through the fourth pressure reducing valve;

[0010] The inlet of the first light-removing tower is connected to the fourth pressure reducing valve, the top gas phase pipeline of the first light-removing tower is connected to the hot side outlet of the condenser, the cold side liquid phase outlet pipeline of the condenser is connected to the top reflux port of the first light-removing tower, one path of the bottom liquid phase outlet pipeline of the first light-removing tower is connected to the cold side inlet of the first reboiler, the hot side outlet pipeline of the first reboiler is connected to the reboiler interface on the bottom side wall of the first light-removing tower, the other path of the bottom liquid phase outlet pipeline of the first light-removing tower is connected to the inlet of the first product delivery pump, and the outlet of the first product delivery pump is connected to the gasoline outlet pipeline.

[0011] Furthermore, the inlet pipe of the second light-removing tower is connected to the cold side gas phase outlet of the condenser, one path of the liquid phase outlet pipe at the bottom of the second light-removing tower is connected to the cold side outlet of the second reboiler, the hot side outlet pipe of the second reboiler is connected to the reboiler interface on the bottom side wall of the second light-removing tower, another path of the liquid phase outlet pipe at the bottom of the second light-removing tower is connected to the inlet of the second product delivery pump, and the outlet of the second product delivery pump is connected to the light hydrocarbon gas outlet pipe.

[0012] Furthermore, the synthesis reactor is a fixed bed reactor or a fluidized bed reactor.

[0013] Furthermore, a control method for a device for directly preparing gasoline hydrocarbons by utilizing exhaust gas from a power plant is disclosed, comprising the following operating steps:

[0014] Step S1: introducing heat transfer oil into the synthesis reactor;

[0015] Step S2: the carbon dioxide gas is mixed in the gas mixer, pressurized in the first gas compressor, activated in the gas activator after pressurization, and finally a mixed gas is obtained;

[0016] Step S3: heating the mixed gas in step S2 through the second heat exchanger, and then passing the mixed gas into the synthesis reactor containing the heat transfer oil in step S1 to generate a reaction mixed gas in the synthesis reactor;

[0017] Step S4: passing the reaction mixture in step S3 from the bottom of the synthesis reactor through the first heat exchanger for heat exchange, and then cooling the reaction mixture through the first cooler and the second cooler to obtain a cooled mixture;

[0018] Step S5: subjecting the cooled mixed gas in step S4 to high-pressure flash separation in the high-pressure flash tank to obtain a first gas and a first liquid;

[0019] Step S6: reducing the pressure of the liquid obtained in step S5 in the second pressure reducing valve to obtain oil;

[0020] Step S7: performing low-pressure flash separation on the oil liquid in step S6 in the low-pressure flash tank to obtain a second gas, oil liquid and liquid water;

[0021] The oil liquid is separated and purified in the first light removal tower to obtain a third gas, and the third gas is partially cooled in the condenser to become a cooling liquid;

[0022] Step S8: sending the uncooled third gas in step S7 into the second light-removal tower to further separate the second liquid and the fourth gas.

[0023] Furthermore, in step S1, the temperature of the heat transfer oil is controlled at 350-450° C., and the pressure of the synthesis reactor is controlled at 0.5-1.5 MPag.

[0024] Furthermore, in step S2, the mass ratio of carbon dioxide to hydrogen in the gas mixer is 22:3, and the pressure in the first gas compressor is 1.5-6.0 MPag.

[0025] Further, in step S3, the heat exchange temperature of the second heat exchanger is 260-460° C., the temperature of the reaction mixture generated in the synthesis reactor is 250-450° C., and the pressure is 1.0-6.0 MPag;

[0026] The temperature of the cooled mixed gas in step S4 is 20-40°C.

[0027] Further, the flash pressure of the high-pressure flash tank in step S5 is 1.0-5.0 MPag;

[0028] In step S6, the pressure of the second pressure reducing valve is 0.2-1.0 MPag.

[0029] Furthermore, in step S7, the pressure of the low-pressure flash tank is 0.5-2.5 MPag; the pressure of the first light-removal tower is 0.3-2.0 MPag.

[0030] Furthermore, in step S8, the pressure of the second lightness removal tower is 0.3-1.0 MPag.

[0031] The present invention provides a device and a control method for directly preparing gasoline hydrocarbons using exhaust gas from a power plant, which has the following beneficial effects compared with the prior art:

[0032] 1. The present invention uses a carbon dioxide purification device, a gas mixer, a hydrogen production device, a raw hydrogen regulating gate, a gas activator, a gas compressor, a heat exchanger, a first cooler, a synthesis cooler, a high-pressure flash tank, a heater, a gas separation device, a low-pressure flash tank, a pressure reducing valve, a light removal tower, a condenser, etc. In the heat exchange chamber of the synthesis reactor, carbon dioxide gas and hydrogen are catalytically directly synthesized into gasoline hydrocarbons. The exhaust gas of the power plant boiler is rich in high-concentration carbon dioxide. Through purification and purification, it is used as a synthetic raw material and hydrogen to undergo catalytic reaction in the reactor to synthesize gasoline hydrocarbons, generating gasoline fuel with high added value, promoting the resource recycling of carbon dioxide, reducing carbon emissions and dependence on fossil energy, and alleviating environmental pollution. The synthesis optimization model is used to optimize and control the reactor parameters, improve synthesis efficiency, and reduce energy consumption.

[0033] 2. In the present invention, carbon dioxide and hydrogen are used as raw materials to directly synthesize gasoline through a one-step reaction. The gasoline content in the product reaches more than 90%, which can be directly used as finished fuel oil or as a gasoline blending component.

[0034] 3. In the present invention, high-quality clean gasoline fuel can be directly synthesized by a one-step method. The synthesized gasoline hydrocarbons do not contain pollutants such as nitrogen and sulfur. The gasoline components meet the National VI standard. The synthesis device is simple, the synthesis process is short, the equipment investment is small, and the energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The schematic diagram of the structure of a device for directly preparing gasoline hydrocarbons by utilizing exhaust gas from a power plant according to an embodiment of the present invention is shown;

[0036] Figure 2 A schematic flow chart of a control method for a device for directly preparing gasoline hydrocarbons using exhaust gas from a power plant according to an embodiment of the present invention is shown;

[0037] Figure 3 A schematic diagram of a three-layer BP neural network structure in an embodiment of the present invention is shown;

[0038] Figure 4 A schematic diagram of a three-layer BP neural network algorithm process in an embodiment of the present invention is shown;

[0039] Figure 5 A schematic diagram of an improved PSO-BP neural network algorithm flow in an embodiment of the present invention is shown.

[0040] In the figure, 1, synthesis reactor; 2, high-pressure flash tank; 3, low-pressure flash tank; 4, first light-removal tower; 5, second light-removal tower; 6, carbon dioxide purification and refining device; 7, hydrogen production device; 10, first heat exchanger; 11, gas activator; 12, second heat exchanger; 13, gas mixer; 14, hydrogen regulating door; 15, hot oil outlet door; 16, temperature transmitter; 17, pressure transmitter; 18, temperature controller; 19, first gas compressor; 20, first cooler; 21, synthesis cooler; 22, heater; 23, second gas compressor compressor; 24, gas separation device; 25, first pressure reducing valve; 26, second pressure reducing valve; 30, third pressure reducing valve; 31, fourth pressure reducing valve; 40, first reboiler; 41, first product delivery pump; 42, condenser; 43, temperature transmitter; 44, pressure transmitter; 45, flow transmitter; 50, second reboiler; 51, second product delivery pump; 60, carbon dioxide regulating gate; 70, raw hydrogen regulating gate; 100, tail gas pipeline; 101, light hydrocarbon gas outlet pipeline; 102, gasoline outlet pipeline; 103, reaction waste water pipe. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0042] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0043] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0044] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] The following is a description of preferred embodiments of the present invention with reference to the accompanying drawings.

[0046] like Figure 1 As shown, an embodiment of the present invention discloses a device for directly preparing gasoline hydrocarbons using exhaust gas from a power plant, comprising a carbon dioxide purification and refining device 6 and a hydrogen production device 7, characterized in that the outlet pipeline of the carbon dioxide purification and refining device 6 is connected to a gas mixer 13 through a carbon dioxide regulating gate 60; the outlet pipeline of the hydrogen production device 7 is connected to a cold end outlet of a first heat exchanger 10 through a raw hydrogen regulating gate 70, the hot end outlet of the first heat exchanger 10 is connected to an inlet of the gas mixer 13, the outlet of the gas mixer 13 is connected to an inlet of a first gas compressor 19, the outlet of the first gas compressor 19 is connected to an inlet of a gas activator 11, and the outlet of the gas activator 11 is connected to a cold end inlet of a second heat exchanger 12;

[0047] The hot end outlet of the second heat exchanger 12 is connected to the top inlet of the synthesis reactor 1, the bottom outlet pipe of the synthesis reactor 1 is connected to the hot end inlet of the first heat exchanger 10, the cold end outlet pipe of the first heat exchanger 10 is connected to the hot side outlet of the first cooler 20, and the cold side outlet of the first cooler 20 is connected to the hot side inlet of the synthesis cooler 21;

[0048] The cold side outlet of the synthetic cooler 21 is connected to the inlet of the high-pressure flash tank 2, the top gas outlet pipeline of the high-pressure flash tank 2 is connected to the cold side outlet of the heater 22, the hot side outlet of the heater 22 is connected to the gas separation device 24, the recovery pipeline of the gas separation device 24 is connected to the inlet of the second gas compressor 23, the outlet pipeline of the second gas compressor 23 is connected to the outlet pipeline of the first gas compressor 19, and the discharge pipeline of the gas separation device 24 is connected to the exhaust gas main pipe 100 through the first pressure reducing valve 25.

[0049] It should be noted that the device in the present invention includes a carbon dioxide purification device 6, a gas mixer 13, a hydrogen production device 7, a raw hydrogen regulating gate 70, a gas activator 11, a gas compressor, a heat exchanger, a first cooler 20, a synthesis cooler 21, a high-pressure flash tank 2, a heater 22, a gas separation device 24, a low-pressure flash tank 3, a pressure reducing valve, a light removal tower, a condenser 42, etc. The synthesis reactor 1 is also connected to a circulating heat exchange mechanism to keep the reaction temperature of the synthesis reactor 1 at 230-400°C. The present invention directly synthesizes gasoline and other products by mixing carbon dioxide and hydrogen at a certain temperature and pressure through a synthesis reactor 1. This carbon dioxide hydrogenation direct synthesis gasoline device has the advantages of simple equipment, short reaction process, low energy consumption, high efficiency, clean and environmental protection, and low equipment investment. The synthesized gasoline can be directly used as fuel oil or as blended gasoline, which helps to recycle carbon resources and reduce dependence on fossil energy, thereby achieving the purpose of carbon reduction and energy storage.

[0050] It should also be noted that, in order to better separate the mixed gas, the gas separation device 24 in the present invention is a membrane reactor, the membrane permeate gas outlet pipe of the membrane reactor is connected to the inlet of the second gas compressor 23, and the membrane separation tail gas of the membrane separator is connected to the tail gas main pipe 100 after being decompressed by the first pressure reducing valve 25. The gas separation device 24 adopts gas membrane separation technology, which uses a polymer fiber material with special selective separation as a separation element. Under the action of a certain driving force, the binary or multi-component components are separated or enriched due to the different rates of permeating the membrane. When the mixed gas is under the action of a certain driving force (pressure difference or pressure ratio on both sides of the membrane), the gas with a relatively fast permeation rate such as water vapor, oxygen, hydrogen, helium, hydrogen sulfide, carbon dioxide, etc. permeates the membrane and is enriched on the permeation side of the membrane, while the gas with a relatively slow permeation rate such as nitrogen, argon, methane, hydrocarbons and carbon monoxide, etc., is retained on the retention side of the membrane and enriched to achieve the purpose of separating the mixed gas.

[0051] In some embodiments of the present application, in order to better separate and purify the mixed gas, in the present invention, the high-pressure flash tank 2 is connected to the low-pressure flash tank 3 through the second pressure reducing valve 26, the gas phase outlet pipeline at the top of the low-pressure flash tank 2 is connected to the tail gas main 100 through the third pressure reducing valve 30, and the oil phase outlet pipeline of the low-pressure flash tank 2 is connected to the inlet of the first light removal tower 4 through the fourth pressure reducing valve 31;

[0052] The inlet of the first light-removing tower 4 is connected to the fourth pressure reducing valve 31, the top gas phase pipeline of the first light-removing tower 4 is connected to the hot side outlet of the condenser 42, the cold side liquid phase outlet pipeline of the condenser 42 is connected to the top reflux port of the first light-removing tower 4, one path of the bottom liquid phase outlet pipeline of the first light-removing tower 4 is connected to the cold side inlet of the first reboiler 40, the hot side outlet pipeline of the first reboiler 40 is connected to the reboiler interface on the bottom side wall of the first light-removing tower 4, the other path of the bottom liquid phase outlet pipeline of the first light-removing tower 4 is connected to the inlet of the first product delivery pump 41, and the outlet of the first product delivery pump 41 is connected to the gasoline outlet pipeline 102.

[0053] In some embodiments of the present application, in order to separate the uncooled gas in the reaction, in the present invention, the inlet pipe of the second light-removal tower 5 is connected to the cold side gas phase outlet of the condenser 42, one path of the liquid phase outlet pipe at the bottom of the second light-removal tower 5 is connected to the cold side outlet of the second reboiler 50, the hot side outlet pipe of the second reboiler 50 is connected to the reboiler interface on the bottom side wall of the second light-removal tower 5, another path of the liquid phase outlet pipe at the bottom of the second light-removal tower 5 is connected to the inlet of the second product delivery pump 51, and the outlet of the second product delivery pump 51 is connected to the light hydrocarbon gas outlet pipe 101.

[0054] In some embodiments of the present application, the synthesis reactor 1 is a fixed bed reactor or a fluidized bed reactor.

[0055] It should be noted that, in order to ensure the stability of the heat source of the synthesis reactor 1, in the present invention, the heat exchange medium in the synthesis reactor 1 is heat transfer oil, including a heat transfer pipe and a heat transfer chamber, the reaction medium flow is the heat transfer chamber, and the circulating heat transfer oil flow is in the heat transfer pipe. The heat transfer oil is heated by the extraction steam after the power plant has done work, which can effectively ensure the stability of the heat source of the synthesis reactor, greatly accelerate the catalytic reaction of the synthesis reactor, and improve the reaction efficiency.

[0056] It should also be noted that in order to better control the reaction temperature in the synthesis reactor 1, the present invention also includes a temperature controller 18, which controls the reactor temperature by adjusting the flow rate of the heat transfer oil. The temperature controller 18 is controlled by a PLC, and the PLC controls the temperature of the synthesis reactor at an optimal temperature by calling a synthesis control optimization model to improve the reaction efficiency.

[0057] like Figure 2 As shown, the embodiment of the present invention discloses a control method for a device for directly preparing gasoline hydrocarbons using exhaust gas from a power plant, comprising the following operating steps:

[0058] Step S1: introducing heat transfer oil into the synthesis reactor;

[0059] Step S2: the carbon dioxide gas is mixed in the gas mixer, pressurized in the first gas compressor, activated in the gas activator after pressurization, and finally a mixed gas is obtained;

[0060] Step S3: heating the mixed gas in step S2 through the second heat exchanger, and then passing the mixed gas into the synthesis reactor containing the heat transfer oil in step S1 to generate a reaction mixed gas in the synthesis reactor;

[0061] Step S4: passing the reaction mixture in step S3 from the bottom of the synthesis reactor through the first heat exchanger for heat exchange, and then cooling the reaction mixture through the first cooler and the second cooler to obtain a cooled mixture;

[0062] Step S5: subjecting the cooled mixed gas in step S4 to high-pressure flash separation in the high-pressure flash tank to obtain a first gas and a first liquid;

[0063] Step S6: reducing the pressure of the liquid obtained in step S5 in the second pressure reducing valve to obtain oil;

[0064] Step S7: performing low-pressure flash separation on the oil liquid in step S6 in the low-pressure flash tank to obtain a second gas, oil liquid and liquid water;

[0065] The oil liquid is separated and purified in the first light removal tower to obtain a third gas, and the third gas is partially cooled in the condenser to become a cooling liquid;

[0066] Step S8: sending the uncooled third gas in step S7 into the second light-removal tower to further separate the second liquid and the fourth gas.

[0067] It should be noted that in the present invention, carbon dioxide and hydrogen are used as raw materials to directly synthesize gasoline through a one-step reaction. The gasoline content in the product reaches more than 90%, which can be directly used as finished fuel oil or as a gasoline blending component. In the present invention, high-quality clean gasoline fuel is directly synthesized through a one-step method. The synthesized gasoline hydrocarbons do not contain pollutants such as nitrogen and sulfur. The gasoline components meet the National VI standard. The synthesis device is simple, the synthesis process is short, the equipment investment is small, and the energy consumption is low.

[0068] In some embodiments of the present application, the temperature of the heat transfer oil in step S1 is controlled at 350-450° C., and the pressure of the synthesis reactor is controlled at 0.5-1.5 MPag.

[0069] It should be noted that by controlling the temperature of the heat transfer oil at 350-450°C and the pressure of the synthesis reactor 1 at 0.5-1.5 MPag, the reaction temperature of the heat exchange chamber of the synthesis reactor 1 can be maintained between 320-420°C.

[0070] In some embodiments of the present application, the mass ratio of carbon dioxide to hydrogen in the gas mixer in step S2 is 22:3, and the pressure in the first gas compressor is 1.5-6.0 MPag.

[0071] In some embodiments of the present application, the heat exchange temperature of the second heat exchanger in step S3 is 260-460° C., the temperature of the reaction mixture generated in the synthesis reactor is 250-450° C., and the pressure is 1.0-6.0 MPag;

[0072] It should be noted that in step S3, the overall reaction equation for generating the reaction mixture is: nCO2+(n~6n)H2=n1CO+n2CH4+(n3C2~n5C4)+(n6C5~n12C11)+n13H2O, wherein n is an integer between 1 and 12; the reaction catalyst is an iron-based / molecular sieve (Na-Fe3O4 / Fe5C2 / HZSM-5) multifunctional composite catalyst, and the reaction catalyst comprises three mutually compatible and complementary active sites, namely, Fe3O4 / Fe5C2 and / HZSM-5 acid sites. CO2 molecules achieve a series conversion with the help of such three-component active sites: CO2 is first reduced to CO through a reverse water-gas shift reaction at the Fe3O4 active site, and the generated CO undergoes a Fischer-Tropsch synthesis (FTS) reaction at the Fe5C2 active site and is converted into α-olefins, and then the olefin intermediate migrates to the acid site on the molecular sieve to generate gasoline fraction hydrocarbons with high selectivity. In the present invention, HZSM-5 molecular sieve is used in the composite catalyst, and its mesoporous structure is conducive to the mass transfer and diffusion of the intermediate species in the reaction, which helps to pull the reaction equilibrium and obtain a higher selectivity of the target product, and also helps to reduce carbon deposition and improve the stability of the composite catalyst. Adding additives K and Co to the reaction catalyst can change the existence form and dispersion of the transition metal in the catalyst, which is conducive to improving the activity of the Fe-based catalyst.

[0073] It should also be noted that part of the hydrogen in the reaction is introduced from the upper part of the synthesis reactor 1 through the hydrogen regulating gate 14. Since CO2 is first generated into CO through the reverse water gas reaction (RWGS), the hydrogen content is reduced in the process, which is not conducive to the formation of Fe5C2 in the catalyst. Supplementing the hydrogen content in the synthesis reactor is beneficial to increasing the Fe5C2 component in the catalyst, which is beneficial to further CO and H2 to undergo Fischer-Tropsch synthesis (FTS) reaction to generate gasoline hydrocarbon compounds.

[0074] In some embodiments of the present invention, the temperature of the cooled mixed gas in step S4 is 20-40°C.

[0075] In some embodiments of the present invention, the flash pressure of the high-pressure flash tank in step S5 is 1.0-5.0 MPag;

[0076] In some embodiments of the present invention, the pressure of the second pressure reducing valve in step S6 is 0.2-1.0 MPag.

[0077] It should be noted that, after the first gas obtained in step S5 is heated by the heater 22, it enters the gas separator to separate hydrogen and tail gas, the hydrogen is returned to the raw material inlet pipeline through the second gas compressor for reuse, and the tail gas is discharged to the power plant boiler for combustion through the tail gas pipeline 100.

[0078] In some embodiments of the present application, the pressure of the low-pressure flash tank in step S7 is 0.5-2.5 MPag, and the pressure of the first light-removal tower is 0.3-2.0 MPag.

[0079] It should be noted that the second gas generated in step S7 is sent to the tail gas main pipe 100 after being decompressed by the third pressure-increasing valve 30 from the gas phase outlet pipe at the top of the low-pressure flash tank, and then sent to the power plant boiler for combustion. The liquid in the oil phase outlet pipe of the low-pressure flash tank is sent to the first light removal tower 4 through the fourth pressure reducing valve 31, and the separated liquid water is continuously discharged to the power plant circulating water system for utilization.

[0080] It should also be noted that the oil liquid is sent to the downstream first light-removing tower 4 for further distillation and purification. The working pressure of the first light-removing tower 4 is 0.3-2.0 MPag. The separated third gas enters the condenser 42 through the top gas phase pipeline of the first light-removing tower 4. Part of the gas is cooled into liquid, and part of the gas is not cooled. The cooled liquid enters the first light-removing tower 4 through the top reflux port of the first light-removing tower 4 for secondary separation. There are two bottom liquid phase outlet pipelines of the first light-removing tower 4, one of which is heated by the first reboiler 40 and sent to the second light-removing tower 5 for recycling, and the other qualified gasoline is delivered to the gasoline outlet pipeline 102 via the first product delivery pump 41.

[0081] In some embodiments of the present application, the pressure of the second light-removal tower in step S8 is 0.3-1.0 MPag.

[0082] It should be noted that the uncooled part of the gas in step S7 is sent to the downstream second light-removing tower 5 for further separation, and the second liquid and the fourth gas are separated. Among them, the fourth gas is discharged to the tail gas pipeline 100 through the top outlet of the second light-removing tower 5, and there are two bottom liquid phase outlet pipelines of the second light-removing tower 5, one of which is heated by the second reboiler 50 and enters the second light-removing tower 5 through the second reboiler interface on the bottom side wall of the second light-removing tower 5, and the other qualified liquefied petroleum gas is transported to the light hydrocarbon gas outlet pipeline 101 through the second product delivery pump 51. In the present invention, carbon dioxide and hydrogen are used as raw materials to directly synthesize gasoline through a one-step reaction, and the gasoline content in the synthesized gasoline product reaches more than 90%, which meets the index conditions of blended gasoline. The content of the components of the synthesized gasoline product is detailed in Table 1.

[0083] Table 1:

[0084]

[0085] Example 1

[0086] In some embodiments of the present application, a three-layer BP neural network is also disclosed, in order to optimize and control the reactor parameters using the synthesis optimization model, improve the synthesis efficiency, and reduce energy consumption. In the present invention, the single-pass conversion rate of gasoline hydrocarbons in the synthesis tower is modeled, and the synthesis conversion rate of gasoline hydrocarbons is one of the main quality indicators of the gasoline hydrocarbon synthesis tower reaction process. It reflects the concentration of gasoline hydrocarbons obtained in the entire synthesis reaction process. Therefore, the main means to ensure the concentration of gasoline hydrocarbons is to control the conversion rate of gasoline hydrocarbons.

[0087] The present invention utilizes the PSO-BP neural network to model the conversion rate of a synthesis tower in one pass. Based on actual production experience and process and mechanism analysis, the important parameters in the cooler, flash tower and heat exchanger in the steady-state process of the gasoline hydrocarbon synthesis tower: temperature and pressure. The catalyst activity and the like can be considered to remain basically unchanged for a period of time, and their influence is ignored. The main process operation parameters in the gasoline hydrocarbon synthesis process are temperature, pressure, hydrogen-carbon ratio, synthesis gas flow rate, and air velocity as model training inputs, and the conversion rate of the synthesis tower in one pass is used as the model output to train the model.

[0088] BP neural network is a feedforward neural network, which consists of input layer, output layer and one or more hidden layers. The input signal goes from the input layer neurons, through the hidden layer, and finally reaches the output layer neurons. There is no connection between neurons in the same layer of BP neural network, and the output of each layer of neurons only serves as the input of the next layer of neurons. j represents the input of the jth node in the input layer, j = 1, ..., n; w ij It is represented as the connection weight between the i-th node in the input layer and the j-th node in the hidden layer; b 1j is the threshold of the jth node in the hidden layer; v jk is the connection weight between the jth node in the hidden layer and the kth node in the output layer; b 2k is the threshold of the kth node in the output layer; O k It represents the threshold of the kth node in the output layer. The input of the hidden layer and the output layer nodes is the weighted sum of the output and threshold of the previous layer nodes. The excitation degree of each node is determined by the excitation function, such as the sigmoid function, the hyperbolic tangent function, etc.

[0089] The learning process of BP neural network is the network "memory training" and "learning convergence" process formed by the repeated alternation of "pattern forward propagation" and "error back propagation". The feedforward working situation is that the input signal is from the neurons of the input layer (referred to as nodes), then passes through all the nodes of the hidden layer, and finally outputs through the output layer nodes, that is, a group of input samples are input from the input layer, pass through the input layer, hidden layer and output layer in turn, and the threshold of each node, the activation function and the weights between nodes are calculated, and finally the output of the network is obtained.

[0090] The error signal is the difference between the expected output of the network and the actual output of the network. The propagation process of the error signal is the process of "error back propagation" from the input layer to the intermediate hidden layer to correct the connection weights.

[0091] Example 2

[0092] In some embodiments of the present application, Figure 4 As shown, a three-layer BP neural network algorithm is disclosed. When the BP neural network is used for soft sensor modeling in the present invention, an improved PSO algorithm is used to obtain the optimal weight and threshold of the model.

[0093] The steps of a three-layer BP neural network algorithm are as follows:

[0094] Step (1): Initialize the weight to the minimum random value;

[0095] Step (2): Get the training vector;

[0096] Step (3): Forward propagation (operating the network to obtain the output value). The weight coefficient of this process remains unchanged, which can also be called the "information retrieval process". If the output value does not meet the expected output, it enters the reverse propagation process;

[0097] Step (4): Back propagation (using the back propagation differential equation to adjust the weights), the deviation signal is propagated back along the original forward propagation path, and the weight coefficients are adjusted;

[0098] Step (5): determine whether the process is finished;

[0099] Step (6): If yes, proceed to the next step to determine whether the error accuracy is met;

[0100] If not, return to step (1);

[0101] Step (7): Determine whether the error accuracy is met;

[0102] Step (8): If yes, it is successful, the trained weights are stored, and the entire algorithm ends;

[0103] If not, determine whether the maximum number of iterations is exceeded;

[0104] Step (8): Determine whether the maximum number of iterations is exceeded;

[0105] If so, it fails and the network cannot converge within the given number of iterations;

[0106] If not, return to step (1).

[0107] Among them, the output error of the network is:

[0108]

[0109] It should be noted that the back propagation of the error, that is, starting from the output layer, calculates the output error of each layer of neurons layer by layer, and then uses the error gradient descent method to adjust the threshold and weight of each layer, and modifies the network so that its output is close to the expected value. For the production of methanol, it is difficult to achieve the accuracy requirements of the BP neural network relying solely on the empirical model. The rapidly developing neural network has brought a solution for this, especially the more mature BP network, which has a simple algorithm, is easy to operate and implement, and can theoretically approximate nonlinear functions arbitrarily. It has been successfully applied to many fields such as function approximation and pattern recognition. The performance of the BP network is mainly determined by the training algorithm and the network structure, and is greatly affected by the sample and may fall into the local optimum. At present, the most commonly used is the gradient algorithm, mainly including the BP algorithm and the momentum BP algorithm. However, these methods are all local search algorithms. When solving nonlinear problems, since the learning algorithm can only change the connection weights and thresholds of the network, it is very easy to fall into the local optimum and it is difficult to obtain the expected results. It is not suitable for modeling industrial production processes. The establishment process of the neural network requires determining the structure of the network, the number of network layers, the number of neurons in each layer, the transfer function, the training algorithm, the weights and thresholds, etc. Neurons are the basic components of neural networks. The main difference between neuron models lies in their activation functions. The general feedforward BP network adopts a three-layer network structure, which is divided into input layer, hidden layer and output layer. In a multi-layer feedforward network, there is no connection between neurons in the same layer. Each layer of neurons receives input from the previous layer and outputs it to the next layer. The hidden layer action function generally adopts the Sigma function.

[0110] Example 3

[0111] In some embodiments of the present application, Figure 5 As shown, an improved PSO-BP neural network algorithm is also disclosed. In order to better control the gasoline hydrocarbon reaction process, an optimization control modeling based on the improved PSO-BP neural network is introduced. The performance of the BP network is mainly determined by the training algorithm and the network structure, and is greatly affected by the sample, and may fall into the local optimum. When the BP neural network is used to solve nonlinear problems, since the learning algorithm can only change the connection weights and thresholds of the network, it is very easy to fall into the local optimum and it is difficult to obtain the desired results. Therefore, the improved PSO algorithm is used to calculate the weights of the BP neural network to adapt it to the modeling of industrial production processes. First, the network structure is determined. According to the number of input and output variables, the number of neurons in the input layer of the neural network is determined to be the number of selected auxiliary variables, the number of neurons in the output layer is 1, and the number of neurons in the hidden layer is determined to be 5 after repeated experiments. Afterwards, all the connection weights and thresholds between neurons to be optimized are encoded, and the objective function adopts the mean square error generated during the network training process. The fitness function is as follows:

[0112]

[0113] In the formula, y 1n represents the neural network input, T 1n is the output, N is the number of training samples, and L is the number of neurons.

[0114] It should be noted that the steps of improving the PSO algorithm to optimize the BP neural network are as follows:

[0115] Step S101, determine the structure of the BP neural network, the number of neurons in the input layer, hidden layer, and output layer, and encode the weights and thresholds of the connections between the neurons of the neural network to represent the particles of the particle swarm.

[0116] Step S102, the fitness function uses the above objective function to initialize the particle swarm size N, learning factors cl and c2, inertia weight w, maximum number of iterations, as well as the initial position and speed of each particle, the individual optimal position and the group optimal position and accuracy.

[0117] Step S103, calculating the distance between the current particle and the optimal particle in the swarm, and determining a suitable inertia weight value according to the distance using an adaptive adjustment strategy.

[0118] Step S104, input particle i, input sample j, calculate the error of sample j, calculate the fitness value of each particle, and update the position and speed of the particle according to the inertia weight, and calculate the error.

[0119] Step S105, updating the optimal position of the population and the optimal position of the individual.

[0120] Step S106, determine whether the maximum number of iterations or accuracy has been reached, if so, terminate the condition, end and output the final weights and thresholds of the neural network, otherwise go to step 3.

[0121] It should also be noted that in order to improve the conversion rate and production efficiency of gasoline, in this application, after the model training and learning are completed, the model output values ​​of the training samples and the test samples are compared with the actual values, and the three performance indicators of the mean square error, relative error, and absolute error of the model after training and testing are used for comparative analysis. The accuracy of the model training and prediction is relatively high, and the algorithm can effectively perform global optimization, so that the model has higher accuracy and stronger prediction ability. At the same time, the model has better generalization ability. It effectively solves the problem that some variables are difficult to control in the gasoline hydrocarbon synthesis process, and improves the single-pass conversion rate and production efficiency of the synthesis.

[0122] In summary, the embodiment of the present invention is provided with a carbon dioxide purification device 6, a gas mixer 13, a hydrogen production device 7, a raw hydrogen regulating gate 70, a gas activator 11, a gas compressor, a heat exchanger, a first cooler 20, a synthesis cooler 21, a high-pressure flash tank 2, a heater 22, a gas separation device 24, a low-pressure flash tank 3, a pressure reducing valve, a light removal tower, a condenser 42, etc. The present invention directly synthesizes gasoline and other products through a reactor at a certain temperature and pressure after mixing carbon dioxide and hydrogen. This carbon dioxide hydrogenation direct gasoline synthesis device has the advantages of simple equipment, short reaction process, low energy consumption, high efficiency, clean and environmental protection, and low equipment investment. The synthesized gasoline can be directly used as fuel oil or as blended gasoline, which is helpful for recycling carbon resources and reducing dependence on fossil energy, and achieving the purpose of carbon reduction and energy storage.

[0123] Furthermore, in the present invention, carbon dioxide and hydrogen are used as raw materials to directly synthesize gasoline through a one-step reaction, and the gasoline content in the product reaches more than 90%, which can be directly used as finished fuel oil or as a gasoline blending component. High-quality clean gasoline fuel is directly synthesized through a one-step method, and the synthesized gasoline hydrocarbons do not contain pollutants such as nitrogen and sulfur. The gasoline components meet the National VI standard, and the synthesis device is simple, the synthesis process is short, the equipment investment is small, and the energy consumption is low.

[0124] In the description of the above embodiments, specific features, structures, materials or characteristics may be combined in a suitable manner in any one or more embodiments or examples.

[0125] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed by the present invention may be used in combination with each other in any manner, and the fact that these combinations are not fully described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0126] Those skilled in the art can understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A device for directly preparing gasoline hydrocarbons using exhaust gas from power plants, characterized in that: The invention comprises a carbon dioxide purification and refining device (6) and a hydrogen production device (7), wherein the outlet pipeline of the carbon dioxide purification and refining device (6) is connected to a gas mixer (13) through a carbon dioxide regulating valve (60); the outlet pipeline of the hydrogen production device (7) is connected to a cold end outlet of a first heat exchanger (10) through a raw hydrogen regulating valve (70), the hot end outlet of the first heat exchanger (10) is connected to an inlet of the gas mixer (13), the outlet of the gas mixer (13) is connected to an inlet of a first gas compressor (19), the outlet of the first gas compressor (19) is connected to an inlet of a gas activator (11), and the outlet of the gas activator (11) is connected to a cold end inlet of a second heat exchanger (12); The hot end outlet of the second heat exchanger (12) is connected to the top inlet of the synthesis reactor (1), the bottom outlet pipe of the synthesis reactor (1) is connected to the hot end inlet of the first heat exchanger (10), the cold end outlet pipe of the first heat exchanger (10) is connected to the hot side outlet of the first cooler (20), and the cold side outlet of the first cooler (20) is connected to the hot side inlet of the synthesis cooler (21); The cold side outlet of the synthesis cooler (21) is connected to the inlet of the high-pressure flash tank (2), the top gas outlet pipeline of the high-pressure flash tank (2) is connected to the cold side outlet of the heater (22), the hot side outlet of the heater (22) is connected to the gas separation device (24), the recovery pipeline of the gas separation device (24) is connected to the inlet of the second gas compressor (23), the outlet pipeline of the second gas compressor (23) is connected to the outlet pipeline of the first gas compressor (19), and the discharge pipeline of the gas separation device (24) is connected to the tail gas main pipe (100) through the first pressure reducing valve (25); The high-pressure flash tank (2) is connected to the low-pressure flash tank (3) via a second pressure reducing valve (26); the gas phase outlet pipeline at the top of the low-pressure flash tank (3) is connected to the tail gas main pipe (100) via a third pressure reducing valve (30); and the oil phase outlet pipeline of the low-pressure flash tank (3) is connected to the inlet of the first light removal tower (4) via a fourth pressure reducing valve (31); The inlet of the first light-removal tower (4) is connected to the fourth pressure reducing valve (31); the top gas phase pipeline of the first light-removal tower (4) is connected to the hot side outlet of the condenser (42); the cold side liquid phase outlet pipeline of the condenser (42) is connected to the top reflux port of the first light-removal tower (4); one path of the bottom liquid phase outlet pipeline of the first light-removal tower (4) is connected to the cold side inlet of the first reboiler (40); the hot side outlet pipeline of the first reboiler (40) is connected to the reboiler interface on the bottom side wall of the first light-removal tower (4); the other path of the bottom liquid phase outlet pipeline of the first light-removal tower (4) is connected to the inlet of the first product delivery pump (41); and the outlet of the first product delivery pump (41) is connected to the gasoline outlet pipeline (102).

2. The device for directly preparing gasoline hydrocarbons using exhaust gas from power plants according to claim 1, characterized in that: The inlet pipeline of the second light-removal tower (5) is connected to the cold side gas phase outlet of the condenser (42); one path of the liquid phase outlet pipeline at the bottom of the second light-removal tower (5) is connected to the cold side outlet of the second reboiler (50); the hot side outlet pipeline of the second reboiler (50) is connected to the reboiler interface on the bottom side wall of the second light-removal tower (5); the other path of the liquid phase outlet pipeline at the bottom of the second light-removal tower (5) is connected to the inlet of the second product delivery pump (51); and the outlet of the second product delivery pump (51) is connected to the light hydrocarbon gas outlet pipeline (101).

3. The device for directly preparing gasoline hydrocarbons using exhaust gas from power plants according to claim 1 is characterized in that: The synthesis reactor (1) is a fixed bed reactor or a fluidized bed reactor.

4. A control method for a device for directly preparing gasoline hydrocarbons using exhaust gas from a power plant according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: Step S1: introducing heat transfer oil into the synthesis reactor; Step S2: the carbon dioxide gas is mixed in the gas mixer, pressurized in the first gas compressor, activated in the gas activator after pressurization, and finally a mixed gas is obtained; Step S3: heating the mixed gas in step S2 through the second heat exchanger, and then passing the mixed gas into the synthesis reactor containing the heat transfer oil in step S1 to generate a reaction mixed gas in the synthesis reactor; Step S4: passing the reaction mixture in step S3 from the bottom of the synthesis reactor through the first heat exchanger for heat exchange, and then cooling the reaction mixture through the first cooler and the second cooler to obtain a cooled mixture; Step S5: subjecting the cooled mixed gas in step S4 to high-pressure flash separation in the high-pressure flash tank to obtain a first gas and a first liquid; Step S6: reducing the pressure of the liquid obtained in step S5 in the second pressure reducing valve to obtain oil; Step S7: performing low-pressure flash separation on the oil liquid in step S6 in the low-pressure flash tank to obtain a second gas, oil liquid and liquid water; The oil liquid is separated and purified in the first light removal tower to obtain a third gas, and the third gas is partially cooled in the condenser to become a cooling liquid; Step S8: sending the uncooled third gas in step S7 into a second light removal tower to further separate the second liquid and the fourth gas.

5. The control method according to claim 4, characterized in that: In step S1, the temperature of the heat transfer oil is controlled at 350-450°C, and the pressure of the synthesis reactor is controlled at 0.5-1.5 MPag.

6. The control method according to claim 4, characterized in that: In step S2, the mass ratio of carbon dioxide to hydrogen in the gas mixer is 22:3, and the pressure in the first gas compressor is 1.5-6.0 MPag.

7. The control method according to claim 4, characterized in that: In step S3, the heat exchange temperature of the second heat exchanger is 260-460° C., the temperature of the reaction mixture generated in the synthesis reactor is 250-450° C., and the pressure is 1.0-6.0 MPag; The temperature of the cooled mixed gas in step S4 is 20-40°C.

8. The control method according to claim 4, characterized in that: The flash pressure of the high-pressure flash tank in step S5 is 1.0-5.0 MPag; In step S6, the pressure of the second pressure reducing valve is 0.2-1.0 MPag.

9. The control method according to claim 4, characterized in that: The pressure of the low-pressure flash tank in step S7 is 0.5-2.5 MPag, and the pressure of the first light-removal tower is 0.3-2.0 MPag.

10. The control method according to claim 4, characterized in that: In step S8, the pressure of the second light-removal tower is 0.3-1.0 MPag.

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