Catalytic reaction device and method for simultaneously co-producing cement raw material pre-decomposition and synthesis gas

Abstract

The application discloses a kind of catalytic reaction device and method for cement raw material pre-decomposition simultaneous co-production of synthesis gas, reactor includes in lower combustion section, in middle catalytic reaction synthesis section and in upper conveying section;Combustion section is sequentially arranged with material accident discharge port, gas inlet one, mixed gas inlet, gas mixture inlet one from bottom to top;Catalytic reaction synthesis section is sequentially arranged with gas inlet two, gas mixture inlet two, catalytic bed heating gas inlet, first catalyst feeding port, gas inlet three, gas mixture inlet three, second catalyst feeding port, catalytic bed heating gas outlet and gas-solid mixture outlet from bottom to top;First suspended catalytic bed and second suspended catalytic bed are arranged in catalytic reaction synthesis section.The cement production process and chemical catalytic reforming reaction process are coupled in the application, CO2 and H2O generated in cement production process are directly converted and utilized to produce synthesis gas, no carbon emission is generated, and total energy consumption is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of carbon emission reduction technology, and in particular to a catalytic reaction apparatus and method for pre-decomposing cement raw materials and simultaneously producing syngas. Background Technology

[0002] In the cement production process, in addition to CO2 generated by fuel combustion, a significant amount of CO2 is also produced by the decomposition of raw materials, accounting for about half of the total CO2 emissions from cement production. However, cement production is energy-intensive and releases large amounts of CO2, with the industry accounting for approximately 13% of China's total carbon emissions. Furthermore, the large volume of flue gas and low CO2 concentration in the cement industry pose greater challenges to carbon capture and utilization. Currently, the main pathways for carbon emission reduction in the cement industry include: 1. Maximizing the energy efficiency of existing processes and equipment; 2. Low-carbon cement technologies based on raw material substitution; 3. Fuel substitution to address coal-fired emissions during the calcination stage; and 4. Carbon capture, utilization, and storage (CCUS) for end-of-pipe treatment. However, due to the unique characteristics of cement production, a large amount of CO2 is still unavoidably generated during the process. Exploring economically efficient CO2 emission reduction technologies is of great significance to the cement industry. Developing a cement production process that can convert and utilize CO2 in situ can minimize carbon emissions during cement production and provide technological support for the cement industry.

[0003] Regarding the technical solution for a reactor used in the CO2 conversion and utilization to produce syngas during cement clinker production, Chinese Patent Publication No. CN114735956A discloses a low-carbon production method and system for cement clinker. The system involves a conversion furnace, but in this furnace, the catalyst is added together with the raw meal. The catalyst is derived from steel slag, resulting in a low content of catalytically active components. Furthermore, the steel slag is not activated through reduction and reconstruction, making it difficult to achieve a catalytic effect. Additionally, this invention uses partial oxidation of CH4 to provide heat for raw meal pre-decomposition and catalytic reforming, but the CH4 partial oxidation process... A large amount of water vapor will be generated during this process. The Gibbs free energy of CH4 water vapor reforming is about 79 kJ / mol, the Gibbs free energy of CH4 carbon dioxide reforming is about 97 kJ / mol, and the Gibbs free energy of carbonate decomposition coupled with CH4 dry reforming is about 184 kJ / mol. Given that the Gibbs free energy of CH4 water vapor reforming is the lowest, in a mixed atmosphere with excess CH4, CH4 is very likely to preferentially undergo reforming reaction with water vapor in the reactor, leaving CO2 in the atmosphere. Therefore, a large amount of CO2 will still exist in the tail gas of this process. Chinese Patent Publication No. CN109437604A discloses a method for recovering sensible heat from calcined lime and utilizing tail gas by using methane reforming. This process mixes CO2 tail gas with CH4 and then reintroduces it into the reaction tube through a pipeline, utilizing the sensible heat of lime to provide heat for the catalytic reaction. Chinese Patent Publication No. CN216799768U discloses a novel high-value utilization reaction system for CO2 from carbonate decomposition. This system also generates CO2 first and then introduces it into the catalytic reaction bed, failing to achieve in-situ utilization and not considering the water vapor problem in cement production. The catalyst is fixed, and the contact time and reaction time are both relatively short.

[0004] In summary, the existing design of CO2 catalytic conversion and utilization reactors in the cement industry still has the following problems:

[0005] (1) Considering that there is a considerable proportion of water vapor in the flue gas during the cement production process, which can be as high as 10% or more, and that the partial oxidation of CH4 will also produce a large amount of water vapor, the existing technical solutions have not solved the problem of water vapor competing with CO2 for CH4 in cement kilns.

[0006] (2) When using solid waste as a catalyst, it is necessary to reduce and reconstruct it in advance to reduce the active components to zero valence. Otherwise, it is difficult to achieve catalytic conversion effect. This step is not easy to implement in industry. Adding synthetic consumable catalyst directly to raw materials will lead to increased costs.

[0007] (3) After the carbonate decomposes to produce CO2, it is then mixed with CH4 through a pipeline and enters the catalytic reaction bed. This does not achieve in-situ utilization and does not take into account the problem of water vapor in the cement production process.

[0008] Therefore, it is urgent to design a reaction device suitable for the catalytic conversion and utilization of CO2 in the cement industry to achieve carbon emission reduction and carbon utilization. Summary of the Invention

[0009] To address the problems existing in the prior art, the present invention provides a catalytic reaction device and method for pre-decomposing cement raw materials and simultaneously producing syngas. Using this catalytic reaction device, CO2 and H2O generated in the rotary kiln and preheater during cement production can be directly converted and utilized to produce syngas products without generating CO2 emissions.

[0010] The present invention is implemented as follows: a catalytic reaction device for pre-decomposing cement raw materials and simultaneously producing syngas includes a reactor, which includes a combustion section at the bottom, a catalytic reaction synthesis section in the middle, and a conveying section at the top.

[0011] The combustion section is arranged from bottom to top as follows: material emergency discharge port, gas inlet 1, mixed gas inlet, and material-gas mixture inlet 1; the catalytic reaction synthesis section is arranged from bottom to top as follows: gas inlet 2, material-gas mixture inlet 2, catalytic bed heating gas inlet, first catalyst feed port, gas inlet 3, material-gas mixture inlet 3, second catalyst feed port, catalytic bed heating gas outlet, and gas-solid mixture outlet.

[0012] The catalytic reaction synthesis section is equipped with a first suspended catalytic bed and a second suspended catalytic bed. The first suspended catalytic bed is located below the second suspended catalytic bed. A connected spiral heat exchange tube is wound around the first and second suspended catalytic beds. The port of the spiral heat exchange tube at the first suspended catalytic bed is the inlet for the catalytic bed heating gas, and the port of the spiral heat exchange tube at the second suspended catalytic bed is the outlet for the catalytic bed heating gas. Gas inlet two and feed-gas mixture inlet two are located below the first suspended catalytic bed. The first catalyst feed port is located at the first suspended catalytic bed. Gas inlet three and feed-gas mixture inlet three are located between the first and second suspended catalytic beds. The second catalyst feed port is located at the second suspended catalytic bed. The gas-solid mixture outlet is located above the second suspended catalytic bed.

[0013] Preferably, the reactor is arranged from the outside to the inside as an outer shell, an outer heat insulation and heat storage layer, and an inner shell; the outer heat insulation and heat storage layer is filled from the outside to the inside with heat insulation cotton, TiO2 aerogel, and honeycomb ceramic heat storage material.

[0014] Preferably, a gas mixer is provided at the gas inlet, with oxygen channels around the gas mixer and a rotary kiln firing exhaust gas channel at the center; guide vanes are provided at the oxygen channels to allow oxygen to rotate in and mix evenly with the rotary kiln firing exhaust gas.

[0015] Preferably, a flame arrestor is provided at the connection between the first suspended catalytic bed and the combustion section.

[0016] Preferably, catalyst barrier nets are provided at the top and bottom of the first suspended catalyst bed and at the top and bottom of the second suspended catalyst bed;

[0017] Both the first and second suspended catalyst beds are cylindrical structures, and the diameter of the second suspended catalyst bed is 1.1 to 1.5 times the diameter of the first suspended catalyst bed.

[0018] The second catalyst feed port is located at the upper part of the second suspended catalyst bed and is used to add the second catalyst; the first catalyst feed port is located at the upper part of the first suspended catalyst bed and is used to add the first catalyst.

[0019] Preferably, the catalytic reaction synthesis section has a shape that is wide at the top, narrow in the middle, and wide at the bottom.

[0020] A method for pre-decomposing cement raw materials and simultaneously producing syngas includes the following steps:

[0021] (1) Nitrogen gas is introduced into the catalytic reaction device through the bottom gas inlet to replace the air in the device with nitrogen gas. After the gas flow is stable, the second catalyst is first added to the second catalyst feed port. After the second catalyst is stably suspended in the second suspension catalytic bed for a period of time, the first catalyst is added to the first catalyst feed port so that the first catalyst is kept in a suspended state in the first suspension catalytic bed.

[0022] (2) High-temperature gas is introduced into the gas inlet of the catalytic bed heating, and the two suspended catalytic beds are preheated to a certain temperature through the spiral heat exchange tube. After maintaining the temperature for a certain period of time, the nitrogen gas introduced into the gas inlet is gradually switched to the preheated reducing gas. The temperature is stabilized for a period of time and then the two suspended catalytic beds are heated to the temperature required for the reaction.

[0023] (3) Mix the preheated natural gas with the raw material to form the first material-gas mixture, gradually reduce the amount of reducing gas in the gas inlet, and pass the first material-gas mixture to the combustion section through the material-gas mixture inlet; mix the preheated oxygen with the rotary kiln burner tail gas that has been reduced to a certain temperature to form a mixed gas, and pass it to the combustion section through the mixed gas inlet.

[0024] The first feed gas mixture and the mixed gas meet in the combustion section and undergo an oxidation reaction to generate carbon dioxide and water vapor and release heat, forming a gas-solid mixture; then it moves upward to the lower part of the first suspended catalyst bed;

[0025] (4) Oxygen is introduced into the lower part of the first suspended catalyst bed through gas inlet 2; raw material is mixed with preheated natural gas through feed buffer device 2 to form a second material-gas mixture; a portion of the second material-gas mixture enters the lower part of the first suspended catalyst bed through material-gas mixture inlet 2;

[0026] After the gas-solid mixture 1, oxygen and a portion of the second gas mixture are mixed evenly, it enters the first suspended catalytic bed to undergo a methane oxidation reaction, generating carbon dioxide and water vapor and releasing heat. At the same time, a methane water vapor reforming reaction occurs to generate gas-solid mixture 2, which then continues to move upward to the position between the first and second suspended catalytic beds.

[0027] (5) Oxygen enters the position between the first and second suspended catalytic beds through the gas inlet 3-way; a portion of the second feed gas mixture enters the position between the first and second suspended catalytic beds through the feed gas mixture inlet 3-way;

[0028] After the gas-solid mixture 2 and oxygen are mixed evenly with a portion of the second feed gas mixture, they enter the second suspended catalytic bed to undergo a methane-carbon dioxide reforming reaction, generating gas-solid mixture 3. Then, it continues to move upward and exits the reaction device through the gas-solid mixture outlet.

[0029] Preferably, when the reactor is shut down, the supply of raw materials and rotary kiln combustion exhaust gas is stopped first, then the supply of natural gas is stopped, and finally the supply of oxygen is stopped. During this process, nitrogen is gradually introduced into the gas inlet to ensure that all the gas in the reactor is replaced with nitrogen. After that, the nitrogen is shut off, and the catalyst and other solid impurities are removed from the material emergency discharge port at the bottom of the reactor. The catalyst is then recovered by screening.

[0030] Preferably, the second catalyst comprises a methane carbon dioxide reforming catalyst and a small amount of methane steam reforming catalyst; the first catalyst is a methane steam reforming catalyst.

[0031] The methane carbon dioxide reforming catalyst has spherical, ellipsoidal, or irregular particles with a particle size of 0.3–0.5 mm; the methane steam reforming catalyst is hydrophobically treated, and the catalyst particles are spherical, ellipsoidal, or irregular particles with a particle size of 0.7–1.5 mm.

[0032] Preferably, in step (2), the source of the high-temperature gas is the flue gas from the rotary kiln outlet or heated air; if it is the flue gas from the rotary kiln outlet, the catalytic bed heating gas outlet is connected to the mixed gas inlet; if it is heated air, the heat comes from green hydrogen combustion, electric heating or solar heating.

[0033] The preheating temperature of the two suspended catalytic beds is 500-650℃; the reducing gas is H2, CO or a mixture thereof, the temperature of the reducing gas after preheating is 400-550℃, the reducing gas is introduced and held for 1-3 hours, and the reduction temperature is 450-600℃.

[0034] Preferably, in step (3), the temperature of the mixed gas is 350-450°C; the temperature of the combustion section is controlled by controlling the amount of oxygen, and the temperature of the mixture in the combustion section is 600-650°C.

[0035] Preferably, in step (4), the first suspended catalytic bed is in an oxygen-deficient state, with an oxygen concentration of <0.3%; the reaction temperature required for the first suspended catalytic bed is 650-750℃, and the reaction space velocity is 2000 h⁻¹. -1 ~4000h -1 The main components of the gas-solid mixture II are raw material, CH4, CO, H2 and CO2.

[0036] Preferably, in step (5), the reaction temperature required for the second suspended catalyst bed is 650℃~800℃, and the reaction space velocity is 2000h. -1 ~4000h -1 The main components of the gas-solid mixture 3 are pre-decomposed raw materials, CO, and H2.

[0037] Compared with the prior art, the advantages and positive effects of this invention are:

[0038] (1) The present invention can convert all the carbon dioxide and water vapor generated in the rotary kiln, the carbon dioxide and water vapor generated in the raw material decomposition heating device, and the carbon dioxide generated in the raw material decomposition into CO and H2, which can be used for downstream synthesis of high-value chemicals.

[0039] (2) Traditionally, in addition to the energy required for cement production, an extra energy supply is needed for the catalytic reforming reaction to produce syngas. However, this invention couples the cement production process and the chemical catalytic reforming reaction process together. The CO2 produced by carbonate decomposition is directly mixed with CH4 for catalytic reaction. Therefore, the total energy consumption is significantly reduced compared to cement production plus catalytic reforming alone.

[0040] (3) The suspended catalytic bed of the present invention adopts a layered arrangement, and the methane steam reforming and methane carbon dioxide reforming react in steps, distinguishing the catalytic reaction process and increasing the catalytic reaction time. Oxygen is introduced into the reactor in stages, avoiding the situation where the flue gas temperature soars due to the direct introduction of oxygen, which leads to the rapid decomposition of raw materials. Partial oxidation reaction occurs in the combustion section, the first suspended catalytic reaction bed and the second catalytic reaction bed, which can gradually release heat to control the temperature in the reactor, and maximize the catalytic reforming reaction of CO2 with methane on the surface of raw materials.

[0041] (4) The catalyst of the present invention can be recycled in a suspended catalytic reaction bed, which greatly improves the service life of the catalyst and solves the problem that solid waste as a catalyst needs to be reduced and reconstructed, making it difficult to achieve catalytic effect, and adding newly prepared catalyst will lead to increased cost. Attached Figure Description

[0042] Figure 1 This is a perspective view of the catalytic reaction apparatus provided in an embodiment of the present invention;

[0043] Figure 2 This is a cross-sectional view of the catalytic reaction apparatus provided in an embodiment of the present invention;

[0044] Figure 3 This is a front view of the gas mixer provided in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of the internal structure of the gas mixer provided in an embodiment of the present invention;

[0046] Figure 5 This is a cross-sectional view of the catalytic reaction synthesis section provided in an embodiment of the present invention.

[0047] In the diagram: 1. Material accident discharge outlet; 2. Gas inlet 1; 3. Mixed gas inlet; 4. Material-gas mixture inlet 1; 4-1. Raw material inlet 1; 4-2. Natural gas interface 1; 4-3. Feed buffer device 1; 5. Gas inlet 2; 6. Material-gas mixture inlet 2; 7. Catalytic bed heating gas inlet; 8. First catalyst feed port; 9. Gas inlet 3; 10. Material-gas mixture inlet 3; 10-1. Raw material inlet 2; 10-2. Natural gas interface 2; 10-3. Feed buffer device 2; 11. Second catalyst... 12. Catalyst feed port; 13. Catalyst bed heating gas outlet; 14. Gas-solid mixture outlet; 15. Gas mixer; 16. Oxygen channel; 17. Guide vane; 18. Rotary kiln calcination tail gas channel; 19. Flame arrestor; 10. First suspended catalyst bed; 11. Catalyst barrier mesh one; 12. Catalyst barrier mesh two; 13. Second suspended catalyst bed; 14. Catalyst barrier mesh three; 15. Catalyst barrier mesh four; 16. Spiral heat exchange tube; 17. Catalyst bed heating gas connecting pipe. Detailed Implementation

[0048] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] Example 1

[0050] Please see Figures 1 to 5 This embodiment discloses a catalytic reaction device for pre-decomposing cement raw materials and simultaneously producing syngas, including a reactor, which includes a combustion section at the bottom, a catalytic reaction synthesis section in the middle, and a conveying section at the top.

[0051] The combustion section is arranged from bottom to top as follows: material emergency discharge port 1, gas inlet 1 2, mixed gas inlet 3, and material-gas mixture inlet 4; the catalytic reaction synthesis section is arranged from bottom to top as follows: gas inlet 2 5, material-gas mixture inlet 2 6, catalytic bed heating gas inlet 7, first catalyst feed port 8, gas inlet 3 9, material-gas mixture inlet 3 10, second catalyst feed port 11, catalytic bed heating gas outlet 12, and gas-solid mixture outlet 13.

[0052] The catalytic reaction synthesis section is equipped with a first suspended catalytic bed 16 and a second suspended catalytic bed 17. The first suspended catalytic bed 16 is located below the second suspended catalytic bed 17. The first suspended catalytic bed 16 and the second suspended catalytic bed 17 are connected by a spiral heat exchange tube 18. The spiral heat exchange tube 18 in the first suspended catalytic bed 16 and the spiral heat exchange tube 18 in the second suspended catalytic bed 17 are connected by a catalytic bed heating gas connecting pipe 18-1. The port of the spiral heat exchange tube 18 at the first suspended catalytic bed 16 is the catalytic bed heating gas inlet 7, and the port of the spiral heat exchange tube 18 at the second suspended catalytic bed 17 is the catalytic bed heating gas outlet 12. Gas inlet 2 5 and feed gas mixture inlet 2 6 are located below the first suspended catalytic bed 16. The first catalyst feed port 8 is located at the first suspended catalytic bed 16. Gas inlet 3 9 and feed gas mixture inlet 3 10 are located between the first suspended catalytic bed 16 and the second suspended catalytic bed 17. The second catalyst feed port 11 is located at the second suspended catalytic bed 17. The gas-solid mixture outlet 13 is located above the second suspended catalytic bed 17.

[0053] In this embodiment, specifically, a feed buffer device 4-3 is provided at the feed gas mixture inlet 4, and a raw material inlet 4-1 and a natural gas interface 4-2 are provided on the feed buffer device 4-3; the feed gas mixture inlet 6 and the feed gas mixture inlet 3 10 are respectively connected to the main pipe by their respective branch pipes, and a feed buffer device 10-3 is provided on the main pipe, and a raw material inlet 10-1 and a natural gas interface 10-2 are provided on the feed buffer device 10-3.

[0054] In a preferred embodiment, the reactor is arranged from the outside to the inside as an outer shell, an outer heat-insulating layer, and an inner shell; the outer heat-insulating layer is filled from the outside to the inside with heat-insulating cotton, TiO2 aerogel, and honeycomb ceramic heat-storage material. This gradually reduces heat loss, with the outer layer providing insulation, the middle layer providing efficient heat insulation, and the inner layer storing heat, thus maintaining the internal temperature of the reactor.

[0055] In a preferred embodiment, a gas mixer 14 is provided at the mixed gas inlet 3. The gas mixer 14 is surrounded by oxygen channels 14-1, and at its center is a rotary kiln firing exhaust gas channel 14-3. Guide vanes 14-2 are provided at the oxygen channels 14-1 to ensure that the oxygen enters in a rotating manner and mixes evenly with the rotary kiln firing exhaust gas. The guide vanes 14-2 can control the flow direction of the oxygen, generating a swirling flow that forms turbulence with the central exhaust gas, promoting uniform mixing and enhancing mixing efficiency.

[0056] In a preferred embodiment, a flame arrestor 15 is provided at the connection between the first suspended catalytic bed 16 and the combustion section. The flame arrestor 15 prevents the flame from passing through, avoiding the flame from flowing from the combustion section to the suspended catalytic bed, which could lead to overheating, sintering, or failure of the catalyst, affecting reaction efficiency and catalyst life, and maintaining the temperature stability of the suspended catalytic bed.

[0057] In a preferred embodiment, catalyst barrier nets are provided at the top and bottom of the first suspended catalyst bed 16 and the top and bottom of the second suspended catalyst bed 17 to prevent the catalyst from falling off and moving upward with the flue gas, thus detaching from the suspended catalyst bed. Specifically, the bottom and top of the first suspended catalyst bed 16 are catalyst barrier net one 16-1 and catalyst barrier net two 16-2, respectively, and the bottom and top of the second suspended catalyst bed 17 are catalyst barrier net three 17-1 and catalyst barrier net four 17-2, respectively.

[0058] In a preferred embodiment, the second catalyst feed port 11 is located at the upper part of the second suspended catalyst bed 17 and is used to add the second catalyst; the first catalyst feed port 8 is located at the upper part of the first suspended catalyst bed 16 and is used to add the first catalyst.

[0059] In a preferred embodiment, both the first suspended catalyst bed 16 and the second suspended catalyst bed 17 are cylindrical structures, and the diameter of the second suspended catalyst bed 17 is 1.1 to 1.5 times the diameter of the first suspended catalyst bed 16. The different diameters of the catalyst beds and the different wind speeds result in different catalyst particle sizes in the two suspended catalyst beds, which can ensure that the catalyst is suspended.

[0060] In a preferred embodiment, the catalytic reaction synthesis section has a structure that is wide at the top, narrow in the middle, and wide at the bottom. To fully meet the catalytic effect and reduce carbon dioxide emissions, it needs to undergo two-stage catalysis with catalysts arranged in layers. The upper layer consists of small particles, and the lower layer consists of large particles. Raw materials can provide reaction sites for the catalytic reaction. To avoid excessively rapid decomposition of raw materials due to overheating, oxygen is added in steps to control the reaction to occur gradually.

[0061] A method for pre-decomposing cement raw materials and simultaneously producing syngas includes the following steps:

[0062] (1) Nitrogen gas is introduced into the catalytic reaction device through the bottom gas inlet 2 to replace the air in the device with nitrogen gas. After the gas flow is stabilized, the second catalyst is first added to the second catalyst feed port 11. After the second catalyst is stably suspended in the second suspension catalytic bed 17 for a period of time, the first catalyst is added to the first catalyst feed port 8 so that the first catalyst is kept in suspension in the first suspension catalytic bed 16.

[0063] (2) High-temperature gas is introduced into the gas inlet 7 of the catalytic bed heating, and the two suspended catalytic beds are preheated to a certain temperature through the spiral heat exchange tube 18. After maintaining the temperature for a certain period of time, the nitrogen gas introduced into the gas inlet 2 is gradually switched to the preheated reducing gas and stabilized at a certain reduction temperature for a period of time. Then the two suspended catalytic beds are heated to the temperature required for the reaction.

[0064] (3) The preheated natural gas and raw materials are mixed through the feed buffer device 4-3 to form the first material-gas mixture. The amount of reducing gas in the gas inlet 2 is gradually reduced, and the first material-gas mixture is passed to the combustion section through the material-gas mixture inlet 4. The preheated oxygen and the rotary kiln firing tail gas that has been reduced to a certain temperature are passed into the gas mixer 14 to form a mixed gas, which is then passed to the combustion section through the mixed gas inlet 3.

[0065] The first feed gas mixture and the mixed gas meet in the combustion section and undergo an oxidation reaction to generate carbon dioxide and water vapor and release heat, forming a gas-solid mixture; then it moves upward to the lower part of the first suspended catalyst bed 16;

[0066] (4) Oxygen is introduced into the lower part of the first suspended catalyst bed 16 through gas inlet 25; raw material is mixed with preheated natural gas through feed buffer device 210-3 to form a second material-gas mixture; a portion of the second material-gas mixture enters the lower part of the first suspended catalyst bed 16 through material-gas mixture inlet 26;

[0067] After the gas-solid mixture 1, oxygen and a portion of the second gas mixture are mixed evenly, it enters the first suspended catalytic bed 16 to undergo a methane oxidation reaction, generating carbon dioxide and water vapor and releasing heat. At the same time, a methane water vapor reforming reaction occurs to generate gas-solid mixture 2, and then continues to move upward to the position between the first suspended catalytic bed 16 and the second suspended catalytic bed 17.

[0068] (5) Oxygen is introduced into the position between the first suspended catalyst bed 16 and the second suspended catalyst bed 17 through gas inlet 39; a portion of the second material-gas mixture is introduced into the position between the first suspended catalyst bed 16 and the second suspended catalyst bed 17 through material-gas mixture inlet 310, and is close to the second suspended catalyst bed 17;

[0069] After the gas-solid mixture II, oxygen and a portion of the second feed gas mixture are mixed evenly, it enters the second suspended catalytic bed 17 to undergo a methane-carbon dioxide reforming reaction, generating gas-solid mixture III. Then it continues to move upward and exits the reaction device through the gas-solid mixture outlet 13, entering the cyclone separator.

[0070] In a preferred embodiment, when the reactor is shut down, the supply of raw materials and rotary kiln combustion exhaust gas is stopped first, then the supply of natural gas is stopped, and finally the supply of oxygen is stopped. During this process, nitrogen is gradually introduced through gas inlet 2 to ensure that all the gas in the reactor is replaced with nitrogen. After that, the nitrogen is shut off, and the catalyst and other solid impurities are removed from the material emergency discharge port 1 at the bottom of the reactor. The catalyst is then recovered through screening.

[0071] In a preferred embodiment, the second catalyst includes a methane carbon dioxide reforming catalyst and a small amount of methane steam reforming catalyst; the first catalyst is a methane steam reforming catalyst.

[0072] The methane carbon dioxide reforming catalyst has spherical, ellipsoidal, or irregular particles with a particle size of 0.3–0.5 mm; the methane steam reforming catalyst is hydrophobically treated, and the catalyst particles are spherical, ellipsoidal, or irregular particles with a particle size of 0.7–1.5 mm.

[0073] In a preferred embodiment, in step (2), the source of the high-temperature gas is the flue gas from the rotary kiln outlet or heated air; if it is the flue gas from the rotary kiln outlet, the catalytic bed heating gas outlet 12 is connected to the mixed gas inlet 3; if it is heated air, the heat comes from green hydrogen combustion, electric heating or solar heating.

[0074] The preheating temperature of the two suspended catalytic beds is 500-650℃; the reducing gas is H2, CO or a mixture thereof, and the synthesis gas produced by this invention can be used directly; the preheating method of the reducing gas is indirect heat exchange using waste heat from the cement production process, the temperature of the preheated reducing gas is 400-550℃, the reducing gas is introduced and held for 1-3 hours, and the reduction temperature is 450-600℃.

[0075] In a preferred embodiment, in step (3), the oxygen is preheated by indirect heat exchange using waste heat from the cement production process, and the temperature of the mixed gas is 350-450°C; the temperature of the combustion section is controlled by controlling the amount of oxygen, and the temperature of the mixture in the combustion section is 600-650°C.

[0076] In a preferred embodiment, in step (4), the first suspended catalyst bed 16 is in an oxygen-deficient state with an oxygen concentration of <0.3%; the reaction temperature required for the first suspended catalyst bed 16 is 650-750°C, and the reaction space velocity is 2000 h⁻¹. -1 ~4000h-1 The main components of the gas-solid mixture II are raw material, CH4, CO, H2 and CO2.

[0077] In a preferred embodiment, in step (5), the reaction temperature required for the second suspended catalyst bed 17 is 650℃~800℃, and the reaction space velocity is 2000h. -1 ~4000h -1 The main components of the gas-solid mixture 3 are pre-decomposed raw materials, CO, and H2.

[0078] Furthermore, it should be noted that after the first catalyst particles in the first suspended catalytic bed 16 are washed by the long-term gas-feed mixture, the first catalyst particles become smaller and will enter the second suspended catalytic bed 17 with the gas flow, and exert a part of the catalytic effect. At this time, it is necessary to replenish the first catalyst in the first suspended catalytic bed 16.

[0079] When additional heat is required to maintain the reaction in the two suspended catalytic beds, the supplemental heat comes from the high-temperature gas entering through the catalytic bed heating gas inlet 7, thus maintaining the two suspended catalytic beds at the required reaction temperature.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A catalytic reaction apparatus for pre-decomposing cement raw materials and simultaneously producing syngas, comprising a reactor, characterized in that: The reactor includes a combustion section at the bottom, a catalytic reaction synthesis section in the middle, and a conveying section at the top; The combustion section is arranged from bottom to top as follows: material emergency discharge port, gas inlet 1, mixed gas inlet, and material-gas mixture inlet 1; the catalytic reaction synthesis section is arranged from bottom to top as follows: gas inlet 2, material-gas mixture inlet 2, catalytic bed heating gas inlet, first catalyst feed port, gas inlet 3, material-gas mixture inlet 3, second catalyst feed port, catalytic bed heating gas outlet, and gas-solid mixture outlet. The catalytic reaction synthesis section is equipped with a first suspended catalytic bed and a second suspended catalytic bed. The first suspended catalytic bed is located below the second suspended catalytic bed. A connected spiral heat exchange tube is wound around the first and second suspended catalytic beds. The port of the spiral heat exchange tube at the first suspended catalytic bed is the inlet for the catalytic bed heating gas, and the port of the spiral heat exchange tube at the second suspended catalytic bed is the outlet for the catalytic bed heating gas. Gas inlet two and feed-gas mixture inlet two are located below the first suspended catalytic bed. The first catalyst feed port is located at the first suspended catalytic bed. Gas inlet three and feed-gas mixture inlet three are located between the first and second suspended catalytic beds. The second catalyst feed port is located at the second suspended catalytic bed. The gas-solid mixture outlet is located above the second suspended catalytic bed. A gas mixer is provided at the gas inlet, with oxygen channels around the gas mixer and a rotary kiln firing exhaust gas channel in the center; guide vanes are provided at the oxygen channels to allow oxygen to rotate in and mix evenly with the rotary kiln firing exhaust gas. A flame arrestor is provided at the connection between the first suspended catalytic bed and the combustion section; The top and bottom ends of the first suspended catalyst bed and the top and bottom ends of the second suspended catalyst bed are both provided with catalyst barrier nets; both the first and second suspended catalyst beds are cylindrical structures, and the diameter of the second suspended catalyst bed is 1.1 to 1.5 times the diameter of the first suspended catalyst bed; the second catalyst feed port is located at the upper part of the second suspended catalyst bed and is used to add the second catalyst; the first catalyst feed port is located at the upper part of the first suspended catalyst bed and is used to add the first catalyst. The catalytic reaction synthesis section has a shape that is wide at the top, narrow in the middle, and wide at the bottom.

2. The catalytic reaction device for pre-decomposing cement raw materials and simultaneously producing syngas according to claim 1, characterized in that: The reactor is arranged from the outside to the inside as an outer shell, an outer heat insulation and heat storage layer, and an inner shell; the outer heat insulation and heat storage layer is filled from the outside to the inside with heat insulation cotton, TiO2 aerogel, and honeycomb ceramic heat storage material.

3. A method for simultaneously producing syngas from cement raw meal pre-decomposition, the method being implemented based on the catalytic reaction apparatus for simultaneously producing syngas from cement raw meal pre-decomposition as described in any one of claims 1 to 2, characterized in that: Includes the following steps: (1) Nitrogen gas is introduced into the catalytic reaction device through the bottom gas inlet to replace the air in the device with nitrogen gas. After the gas flow is stable, the second catalyst is first added to the second catalyst feed port. After the second catalyst is stably suspended in the second suspension catalytic bed for a period of time, the first catalyst is added to the first catalyst feed port so that the first catalyst is kept in a suspended state in the first suspension catalytic bed. (2) High-temperature gas is introduced into the gas inlet of the catalytic bed heating, and the two suspended catalytic beds are preheated to a certain temperature through the spiral heat exchange tube. After maintaining the temperature for a certain period of time, the nitrogen gas introduced into the gas inlet is gradually switched to the preheated reducing gas. The temperature is stabilized for a period of time and then the two suspended catalytic beds are heated to the temperature required for the reaction. (3) Mix the preheated natural gas with the raw material to form the first material-gas mixture, gradually reduce the amount of reducing gas in the gas inlet, and pass the first material-gas mixture to the combustion section through the material-gas mixture inlet; mix the preheated oxygen with the rotary kiln burner tail gas that has been reduced to a certain temperature to form a mixed gas, and pass it to the combustion section through the mixed gas inlet. The first feed gas mixture and the mixed gas meet in the combustion section and undergo an oxidation reaction to generate carbon dioxide and water vapor and release heat, forming a gas-solid mixture; then it moves upward to the lower part of the first suspended catalyst bed; (4) Oxygen is introduced into the lower part of the first suspended catalyst bed through gas inlet 2; raw material is mixed with preheated natural gas through feed buffer device 2 to form a second material-gas mixture; a portion of the second material-gas mixture enters the lower part of the first suspended catalyst bed through feed-gas mixture inlet 2; After the gas-solid mixture 1, oxygen and a portion of the second gas mixture are mixed evenly, it enters the first suspended catalytic bed to undergo a methane oxidation reaction, generating carbon dioxide and water vapor and releasing heat. At the same time, a methane water vapor reforming reaction occurs to generate gas-solid mixture 2, which then continues to move upward to the position between the first and second suspended catalytic beds. (5) Oxygen enters the position between the first and second suspended catalytic beds through the gas inlet 3; a portion of the second feed gas mixture enters the position between the first and second suspended catalytic beds through the feed gas mixture inlet 3; After the gas-solid mixture 2 and oxygen are mixed evenly with a portion of the second feed gas mixture, they enter the second suspended catalytic bed to undergo a methane-carbon dioxide reforming reaction, generating gas-solid mixture 3. Then, it continues to move upward and exits the reaction device through the gas-solid mixture outlet.

4. The method for pre-decomposing cement raw materials and simultaneously producing syngas according to claim 3, characterized in that: When the reactor is shut down, first stop the supply of raw materials and rotary kiln combustion exhaust gas, then stop the supply of natural gas, and finally stop the supply of oxygen. During this process, nitrogen is gradually introduced into the gas inlet to ensure that all the gas in the reactor is replaced with nitrogen. After that, the nitrogen is shut off, and the catalyst and other solid impurities are removed from the material emergency discharge port at the bottom of the reactor. The catalyst is then recovered through screening.

5. The method for pre-decomposing cement raw materials and simultaneously producing syngas according to claim 3, characterized in that: The second catalyst includes a methane carbon dioxide reforming catalyst and a small amount of methane steam reforming catalyst; the first catalyst is a methane steam reforming catalyst. The methane carbon dioxide reforming catalyst has spherical, ellipsoidal, or irregular particles with a particle size of 0.3~0.5 mm; the methane steam reforming catalyst is hydrophobically treated, and the catalyst particles are spherical, ellipsoidal, or irregular particles with a particle size of 0.7~1.5 mm.

6. The method for supplying cement raw meal pre-decomposition and co-production of syngas according to claim 3, characterized in that: In step (2), the source of high-temperature gas is the flue gas from the rotary kiln outlet or heated air; if it is the flue gas from the rotary kiln outlet, the catalytic bed heating gas outlet is connected to the mixed gas inlet; if it is heated air, the heat comes from green hydrogen combustion, electric heating or solar heating. The preheating temperature of the two suspended catalytic beds is 500~650℃; the reducing gas is H2, CO or a mixture thereof, the temperature of the reducing gas after preheating is 400~550℃, the reducing gas is introduced and held for 1~3 h, and the reduction temperature is 450~600℃.

7. The method for pre-decomposing cement raw materials and simultaneously producing syngas according to claim 3, characterized in that: In step (3), the temperature of the mixed gas is 350~450℃; the temperature of the combustion section is controlled by controlling the amount of oxygen, and the temperature of the mixture in the combustion section is 600~650℃.

8. The method for pre-decomposing cement raw materials and simultaneously producing syngas according to claim 3, characterized in that: In step (4), the first suspended catalytic bed is in an oxygen-deficient state, with an oxygen concentration of <0.3%; the reaction temperature required for the first suspended catalytic bed is 650~750℃, and the reaction space velocity is 2000 h⁻¹. -1 ~4000 h -1 The main components of the gas-solid mixture II are raw material, CH4, CO, H2 and CO2.

9. The method for supplying cement raw meal pre-decomposition and co-production of syngas according to claim 3, characterized in that: In step (5), the reaction temperature required for the second suspended catalytic bed is 650℃~800℃, and the reaction space velocity is 2000 h⁻¹. -1 ~4000 h -1 The main components of the gas-solid mixture 3 are pre-decomposed raw materials, CO, and H2.

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