Catalytic reaction device and method for pre-decomposing cement raw material and co-producing synthesis gas at same time

Abstract

The invention discloses a catalytic reaction device and method for pre-decomposing cement raw materials and co-producing synthesis gas at the same time. A reactor comprises a combustion section located on the lower portion, a catalytic reaction synthesis section located in the middle and a conveying section located on the upper portion. The combustion section is sequentially provided with a material accident discharge port, a gas inlet I, a mixed gas inlet and a material-gas mixture inlet I from bottom to top; the catalytic reaction synthesis section is sequentially provided with a gas inlet II, a material-gas mixture inlet II, a catalytic bed heating gas inlet, a first catalyst feeding hole, a gas inlet III, a material-gas mixture inlet III, a second catalyst feeding hole, a catalytic bed heating gas outlet and a gas-solid mixture outlet from bottom to top; a first suspension catalytic bed and a second suspension catalytic bed are arranged in the catalytic reaction synthesis section. According to the invention, the cement production process and the chemical catalytic reforming reaction process are coupled, CO2 and H2O generated in the cement production process are directly converted and utilized to produce synthesis gas, carbon emission is not generated, and the total energy consumption is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon emission reduction, and in particular to a catalytic reaction device and method for pre-decomposing cement raw materials and simultaneously co-producing synthesis gas. Background Art

[0002] During cement production, in addition to CO2 generated by fuel combustion, the decomposition of raw materials also produces significant amounts of CO2, accounting for approximately half of total CO2 emissions from cement production. However, cement production consumes significant amounts of energy and releases significant amounts of CO2 during the process, contributing to approximately 13% of China's total carbon emissions. Furthermore, the cement industry's high flue gas volume and low CO2 concentrations pose significant challenges for carbon capture and utilization. Currently, the main approaches to carbon emission reduction in the cement industry include: 1. Optimizing the energy efficiency of existing process equipment; 2. Developing low-carbon cement technologies based on raw material substitution; 3. Fuel substitution to address coal-fired emissions during the calcination phase; and 4. Carbon capture, utilization, and storage (CCUS) for end-of-pipe disposal. However, due to the unique nature of cement production, significant amounts of CO2 are unavoidable during the production process. Exploring cost-effective and efficient CO2 emission reduction technologies is crucial for the cement industry. Developing a cement production process that utilizes CO2 in situ could minimize carbon emissions during cement production and provide technical support for the industry.

[0003] Regarding the technical solution of a reactor for the conversion and utilization of CO2 to produce synthesis gas in the cement clinker production process, Chinese Patent Publication No. CN114735956A discloses a low-carbon production method and system for cement clinker. The system involves a converter, but in the converter, the catalyst is added together with the raw material. The catalyst uses the components of steel slag, the content of catalytically active components is low, and the steel slag is not activated by reduction and reconstruction, so it is difficult to achieve a catalytic effect. In addition, the invention uses partial oxidation of CH4 to provide heat for the pre-decomposition and catalytic reforming of the raw material, but in the CH4 partial oxidation process, the catalyst is added together with the raw material. A large amount of water vapor will be produced, and the Gibbs free energy of CH4 water vapor reforming is about 79kJ / mol, the Gibbs free energy of CH4 carbon dioxide reforming is about 97kJ / mol, and the Gibbs free energy of carbonate decomposition coupled with CH4 dry reforming is about 184kJ / 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 undergo reforming reaction with water vapor in the reactor, and CO2 will still remain in the atmosphere. Therefore, there will still be a large amount of CO2 in the exhaust gas of this process. Chinese Patent Publication No. CN109437604A discloses a method for recovering sensible heat from burned lime and utilizing tail gas by 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 carbonate decomposition CO2 high-value utilization reaction system. This system also first generates CO2 and then enters the catalytic reaction bed. In-situ utilization is not achieved, and the problem of water vapor in the cement production process is not considered. The catalyst is fixed, and the contact time and reaction time are both short.

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

[0005] (1) Considering that a considerable proportion of water vapor exists in the flue gas during cement production, which can be as high as more than 10%, and the partial oxidation of CH4 also produces a large amount of water vapor, the existing technical solutions do not solve the problem of water vapor and CO2 competing for CH4 in cement kilns;

[0006] (2) Using solid waste as a catalyst requires reduction and reconstruction in advance to reduce the active components to zero valence, otherwise it is difficult to achieve a catalytic conversion effect. This step is not easy to implement in industry, and directly adding a synthetic consumable catalyst to the raw material will increase the cost;

[0007] (3) After carbonate decomposition produces CO2, it is mixed with CH4 through a pipeline and then enters the catalytic reaction bed. In situ utilization is not achieved, and the problem of water vapor in the cement production process is not considered.

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

[0009] To solve 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 synthesis gas. The catalytic reaction device can directly convert and utilize the CO2 and H2O generated in the rotary kiln and preheater during the cement production process to produce synthesis gas products without generating CO2 emissions.

[0010] The present invention is achieved by providing a catalytic reaction device for pre-decomposing cement raw materials and simultaneously producing synthesis gas, comprising a reactor, wherein the reactor comprises a combustion section located at the bottom, a catalytic reaction synthesis section located in the middle, and a conveying section located at the top;

[0011] The combustion section is sequentially arranged with a material accident discharge port, a gas inlet 1, a mixed gas inlet, and a material gas mixture inlet 1 from bottom to top; the catalytic reaction synthesis section is sequentially arranged with a gas inlet 2, a material gas mixture inlet 2, a catalyst bed heating gas inlet, a first catalyst feeding port, a gas inlet 3, a material gas mixture inlet 3, a second catalyst feeding port, a catalyst bed heating gas outlet, and a gas-solid mixture outlet from bottom to top;

[0012] A first suspended catalytic bed and a second suspended catalytic bed are arranged in the catalytic reaction synthesis section. The first suspended catalytic bed is located below the second suspended catalytic bed. The first suspended catalytic bed and the second suspended catalytic bed are wound with interconnected spiral heat exchange tubes. The spiral heat exchange tube port at the first suspended catalytic bed is the catalytic bed heating gas inlet, and the spiral heat exchange tube port at the second suspended catalytic bed is the catalytic bed heating gas outlet; the second gas inlet and the second material-gas mixture inlet are located below the first suspended catalytic bed, the first catalyst feeding port is located at the first suspended catalytic bed, the third gas inlet and the third material-gas mixture inlet are located between the first suspended catalytic bed and the second suspended catalytic bed, the second catalyst feeding port is located at the second suspended catalytic bed, and the gas-solid mixture outlet is located above the second suspended catalytic bed.

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

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

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

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

[0017] The first suspended catalytic bed and the second suspended catalytic bed are both cylindrical structures, and the diameter of the second suspended catalytic bed is 1.1 to 1.5 times the diameter of the first suspended catalytic bed;

[0018] The second catalyst feeding port is located on the upper portion of the second suspended catalytic bed and is used for adding the second catalyst; the first catalyst feeding port is located on the upper portion of the first suspended catalytic bed and is used for adding the first catalyst.

[0019] Preferably, the catalytic reaction synthesis section has an outer shape of a structure 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 synthesis gas comprises the following steps:

[0021] (1) nitrogen is introduced into the catalytic reaction device through the bottom gas inlet to replace the air in the device with nitrogen. After the airflow is stable, the second catalyst is first added to the second catalyst feeding port. After the second catalyst is stably suspended in the second suspended catalyst bed for a period of time, the first catalyst is added to the first catalyst feeding port to keep the first catalyst in a suspended state in the first suspended catalyst bed;

[0022] (2) introducing high-temperature gas into the heating gas inlet of the catalyst bed, preheating the two suspended catalyst beds to a certain temperature through the spiral heat exchange tube, maintaining it for a certain period of time, gradually switching the nitrogen introduced into the gas inlet one to the preheated reducing gas, stabilizing it at a certain reducing temperature for a period of time, and then heating the two suspended catalyst beds to the temperature required for the reaction;

[0023] (3) Mixing the preheated natural gas with the raw meal to form a first material-gas mixture, gradually reducing the amount of reducing gas in the gas inlet, and passing the first material-gas mixture to the combustion section through the material-gas mixture inlet; mixing the preheated oxygen with the rotary kiln exhaust gas cooled to a certain temperature to form a mixed gas, and passing the mixed gas 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 oxidation reaction, generating carbon dioxide and water vapor and releasing heat to form a gas-solid mixture; then, the mixture moves upward to the lower position of the first suspended catalytic bed;

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

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

[0027] (5) oxygen is introduced into the position between the first suspended catalyst bed and the second suspended catalyst bed through the gas inlet three; a portion of the second feed gas mixture is introduced into the position between the first suspended catalyst bed and the second suspended catalyst bed through the feed gas mixture inlet three;

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

[0029] Preferably, when the reaction unit is shut down, the introduction of raw materials and rotary kiln combustion exhaust gas is stopped first, followed by the introduction of natural gas, and finally the introduction of oxygen. During this process, nitrogen is gradually introduced into the gas inlet to ensure that all the gas in the reaction unit is replaced by nitrogen. After that, the nitrogen is turned off, the catalyst and other solid impurities are taken out from the material accident discharge port at the bottom of the reaction unit, and the catalyst is recovered by screening.

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

[0031] The methane carbon dioxide reforming catalyst particles are spherical, ellipsoidal or irregular particles with a particle size of 0.3 to 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 to 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 the 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°C; the reducing gas is H2, CO or a mixture thereof, the temperature of the preheated reducing gas is 400-550°C, the reducing gas is introduced and maintained for 1-3 hours, and the reduction temperature is 450-600°C.

[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 catalyst bed is in an oxygen-deficient state, with an oxygen concentration of <0.3%; the reaction temperature of the first suspended catalyst bed is 650-750°C, and the reaction space velocity is 2000h -1 ~4000h -1 ; The main components of gas-solid mixture 2 are raw meal, CH4, CO, H2 and CO2.

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

[0037] Compared with the prior art, the present invention has the following advantages and positive effects:

[0038] (1) The present invention can convert the carbon dioxide and water vapor generated by firing in the rotary kiln, the carbon dioxide and water vapor generated by the heat supply from the decomposition of raw materials in the catalytic reaction device, and the carbon dioxide generated by the decomposition of raw materials into CO and H2 for the downstream synthesis of high-value chemicals.

[0039] (2) In addition to the energy required for cement production, the conventional method requires additional energy for the catalytic reforming reaction to produce synthesis gas. However, the present invention couples the cement production process and the chemical catalytic reforming reaction process together. The CO2 produced by the decomposition of carbonates is directly mixed with CH4 for catalytic reaction. Therefore, the total energy consumption is greatly reduced compared with the separate cement production and catalytic reforming.

[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 and the raw material decomposes rapidly due to the direct introduction of oxygen. Part of the 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 the raw material.

[0041] (4) The catalyst of the present invention is suspended in a suspended catalytic reaction bed and can be recycled, which greatly increases the service life of the catalyst and solves the problem that solid waste needs to be reduced and reconstructed as a catalyst, which makes it difficult to achieve a catalytic effect and the addition of newly prepared catalysts will lead to increased costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a perspective view of a catalytic reaction device provided by an embodiment of the present invention;

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

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

[0045] Figure 4 1 is a schematic diagram of the internal structure of a gas mixer provided by an embodiment of the present invention;

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

[0047] In the figure: 1. Material accident discharge port; 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 feeding 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 feeding port Chemical feeding port; 12. Catalytic bed heating gas outlet; 13. Gas-solid mixture outlet; 14. Gas mixer; 14-1. Oxygen channel; 14-2. Guide vanes; 14-3. Rotary kiln firing tail gas channel; 15. Flame arrester; 16. First suspended catalytic bed; 16-1. Catalyst barrier net one; 16-2. Catalyst barrier net two; 17. Second suspended catalytic bed; 17-1. Catalyst barrier net three; 17-2. Catalyst barrier net four; 18. Spiral heat exchange tube; 18-1. Catalytic bed heating gas connecting pipe. DETAILED DESCRIPTION

[0048] The technical solution of the present invention will be described clearly and completely below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] Example 1

[0050] See also Figures 1 to 5 This embodiment discloses a catalytic reaction device for pre-decomposing cement raw materials and simultaneously producing synthesis gas, comprising a reactor, wherein the reactor comprises a combustion section at the bottom, a catalytic reaction synthesis section at the middle, and a conveying section at the top;

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

[0052] A first suspended catalytic bed 16 and a second suspended catalytic bed 17 are arranged in the catalytic reaction synthesis section. The first suspended catalytic bed 16 is located below the second suspended catalytic bed 17. A connected spiral heat exchange tube 18 is wound in the first suspended catalytic bed 16 and the second suspended catalytic bed 17. The spiral heat exchange tube 18 in the first suspended catalytic bed 16 is connected to the spiral heat exchange tube 18 in the second suspended catalytic bed 17 through a catalytic bed heating gas connecting tube 18-1. The end of the spiral heat exchange tube 18 at the first suspended catalytic bed 16 is the catalytic bed heating gas inlet 7, and the end of the spiral heat exchange tube 18 at the second suspended catalytic bed 17 is the catalytic bed heating gas outlet 12; the gas inlet 2 5 and the material gas mixture inlet 2 6 are located below the first suspended catalytic bed 16, the first catalyst feeding port 8 is located at the first suspended catalytic bed 16, the gas inlet 3 9 and the material gas mixture inlet 3 10 are located between the first suspended catalytic bed 16 and the second suspended catalytic bed 17, the second catalyst feeding port 11 is located at the second suspended catalytic bed 17, and 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 material-gas mixture inlet 4, and a raw meal inlet 4-1 and a natural gas interface 4-2 are provided on the feed buffer device 4-3; the material-gas mixture inlet 2 6 and the material-gas mixture inlet 3 10 are respectively connected to the main pipe by their respective branch pipes, and a feed buffer device 2 10-3 is provided on the main pipe, and a raw meal inlet 2 10-1 and a natural gas interface 2 10-2 are provided on the feed buffer device 2 10-3.

[0054] As a preferred embodiment, the reactor is arranged from the outside inwards with an outer shell, an outer thermal insulation and storage layer, and an inner shell. The outer thermal insulation and storage layer is filled with thermal insulation cotton, TiO2 aerogel, and honeycomb ceramic thermal storage materials from the outside inwards. This gradually reduces heat loss, with the outer layer providing insulation, the middle layer providing high-efficiency insulation, and the inner layer storing heat to maintain the reactor's internal temperature.

[0055] In a preferred embodiment, a gas mixer 14 is provided at the mixed gas inlet 3. Gas mixer 14 is surrounded by oxygen channels 14-1 and centered within a rotary kiln exhaust gas channel 14-3. Guide vanes 14-2 are provided at oxygen channel 14-1 to swirl oxygen into the air and mix it evenly with the rotary kiln exhaust gas. Guide vanes 14-2 control the flow direction of the oxygen, generating a swirl that creates turbulent flow with the exhaust gas at the center, promoting even mixing and enhancing mixing efficiency.

[0056] As a preferred embodiment, a flame arrester 15 is provided at the connection between the first suspended catalytic bed 16 and the combustion section. The flame arrester 15 blocks the passage of flames, preventing the flames from flowing from the combustion section to the suspended catalytic bed, which could cause overheating, sintering, or failure of the catalyst, thereby affecting reaction efficiency and catalyst life, and maintaining a stable temperature in the suspended catalytic bed.

[0057] As a preferred embodiment, catalyst barrier nets are installed at the top and bottom of the first suspended catalytic bed 16 and the top and bottom of the second suspended catalytic bed 17 to prevent the catalyst from falling and moving upward with the flue gas, thereby preventing it from escaping from the suspended catalytic bed. Specifically, the bottom and top of the first suspended catalytic bed 16 are catalyst barrier net 1 16-1 and catalyst barrier net 2 16-2, respectively, while the bottom and top of the second suspended catalytic bed 17 are catalyst barrier net 3 17-1 and catalyst barrier net 4 17-2, respectively.

[0058] As a preferred embodiment, the second catalyst feeding port 11 is located above the second suspended catalyst bed 17 for adding the second catalyst; the first catalyst feeding port 8 is located above the first suspended catalyst bed 16 for adding the first catalyst.

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

[0060] As a preferred embodiment, the catalytic reaction synthesis section has an outer shape of a wide top, narrow middle, and wide bottom structure. In order to fully achieve the catalytic effect and reduce carbon dioxide emissions, two-stage catalysis is required, and the catalyst is arranged in layers, with small particles on the upper layer and large particles on the lower layer; the raw material can provide reaction sites for the catalytic reaction. In order to avoid excessive decomposition of the raw material 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 synthesis gas comprises the following steps:

[0062] (1) Nitrogen is introduced into the catalytic reaction device through the bottom gas inlet 2 to replace the air in the device with nitrogen. After the airflow stabilizes, the second catalyst is first added to the second catalyst feeding port 11. After the second catalyst is stably suspended in the second suspended catalyst bed 17 for a period of time, the first catalyst is added to the first catalyst feeding port 8 to keep the first catalyst in a suspended state in the first suspended catalyst bed 16;

[0063] (2) High-temperature gas is introduced into the catalyst bed heating gas inlet 7, and the two suspended catalyst 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 introduced into the gas inlet 2 is gradually switched to the preheated reducing gas, and the temperature is maintained at a certain reducing temperature for a period of time, and then the two suspended catalyst beds are heated to the temperature required for the reaction;

[0064] (3) The preheated natural gas and the raw meal are mixed through the feed buffer device 4-3 to form a 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 combustion tail gas cooled to a certain temperature are passed into the gas mixer 14 to form a mixed gas, which is 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 to form a gas-solid mixture. The mixture then moves upward to the lower portion of the first suspended catalyst bed 16.

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

[0067] After the gas-solid mixture 1, oxygen and a portion of the second feed gas mixture are evenly mixed, they enter the first suspended catalytic bed 16 to undergo a methane oxidation reaction, generating carbon dioxide and water vapor and releasing heat. Simultaneously, a methane steam reforming reaction occurs to generate a gas-solid mixture 2, which then continues to move upward to a 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 the gas inlet 3 9; a portion of the second gas mixture is introduced into the position between the first suspended catalyst bed 16 and the second suspended catalyst bed 17 through the gas mixture inlet 3 10, and close to the second suspended catalyst bed 17;

[0069] After the gas-solid mixture 2 and oxygen are evenly mixed with a portion of the second feed gas mixture, they enter the second suspended catalytic bed 17 to undergo a methane carbon dioxide reforming reaction to generate a gas-solid mixture 3, which then continues to move upward, exits the reaction device through the gas-solid mixture outlet 13, and enters the cyclone separation device.

[0070] As a preferred embodiment, when the reaction device is shut down, the introduction of raw materials and rotary kiln combustion exhaust gas is first stopped, followed by the introduction of natural gas, and finally the introduction of oxygen. During this process, nitrogen is gradually introduced into the gas inlet 2 to ensure that all the gas in the reaction device is replaced by nitrogen. After that, the nitrogen is turned off, and the catalyst and other solid impurities are removed from the material accident discharge port 1 at the bottom of the reaction device, and the catalyst is recovered by screening.

[0071] As 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 particles are spherical, ellipsoidal or irregular particles with a particle size of 0.3 to 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 to 1.5 mm.

[0073] As 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°C; the reducing gas is H2, CO or a mixture thereof, and the synthesis gas produced by the present invention can be directly used; the reducing gas is preheated by indirect heat exchange with waste heat in the cement production process, the temperature of the preheated reducing gas is 400-550°C, the reducing gas is introduced and maintained for 1-3 hours, and the reduction temperature is 450-600°C.

[0075] As a preferred embodiment, in step (3), the oxygen is preheated by indirect heat exchange with 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] As 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 of the first suspended catalyst bed 16 is 650-750°C, and the reaction space velocity is 2000h -1 ~4000h-1 ; The main components of gas-solid mixture 2 are raw meal, CH4, CO, H2 and CO2.

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

[0078] In addition, it should be noted that after the first catalyst particles in the first suspended catalytic bed 16 are flushed by the material-gas mixture for a long time, the first catalyst particles become smaller and will enter the second suspended catalytic bed 17 with the air flow and exert a partial catalytic effect. At this time, the first catalyst in the first suspended catalytic bed 16 needs to be replenished.

[0079] When additional heat is required to maintain the reaction of the two suspended catalyst beds, the additional heat comes from the high-temperature gas entering through the catalyst bed heating gas inlet 7, so that the two suspended catalyst beds are maintained at the temperature required for the reaction.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 device for pre-decomposing cement raw materials and simultaneously producing synthesis gas, comprising a reactor, characterized in that: The reactor comprises a combustion section at the bottom, a catalytic reaction synthesis section at the middle, and a conveying section at the top; The combustion section is sequentially arranged with a material accident discharge port, a gas inlet 1, a mixed gas inlet, and a material gas mixture inlet 1 from bottom to top; the catalytic reaction synthesis section is sequentially arranged with a gas inlet 2, a material gas mixture inlet 2, a catalyst bed heating gas inlet, a first catalyst feeding port, a gas inlet 3, a material gas mixture inlet 3, a second catalyst feeding port, a catalyst bed heating gas outlet, and a gas-solid mixture outlet from bottom to top; A first suspended catalytic bed and a second suspended catalytic bed are arranged in the catalytic reaction synthesis section. The first suspended catalytic bed is located below the second suspended catalytic bed. The first suspended catalytic bed and the second suspended catalytic bed are wound with interconnected spiral heat exchange tubes. The spiral heat exchange tube port at the first suspended catalytic bed is the catalytic bed heating gas inlet, and the spiral heat exchange tube port at the second suspended catalytic bed is the catalytic bed heating gas outlet; the second gas inlet and the second material-gas mixture inlet are located below the first suspended catalytic bed, the first catalyst feeding port is located at the first suspended catalytic bed, the third gas inlet and the third material-gas mixture inlet are located between the first suspended catalytic bed and the second suspended catalytic bed, the second catalyst feeding port is located at the second suspended catalytic bed, and the gas-solid mixture outlet is located above the second suspended catalytic bed.

2. The catalytic reaction device for pre-decomposition of cement raw materials and simultaneous co-production of synthesis gas according to claim 1, characterized in that: The reactor is arranged with an outer shell, an outer thermal insulation and heat storage layer and an inner shell from the outside to the inside; the outer thermal insulation and heat storage layer is filled with thermal insulation cotton, TiO2 aerogel and honeycomb ceramic thermal storage material from the outside to the inside.

3. The catalytic reaction device for pre-decomposition of cement raw materials and simultaneous co-production of synthesis gas according to claim 1, characterized in that: A gas mixer is provided at the mixed gas inlet, with oxygen channels around the gas mixer and a rotary kiln exhaust gas channel in the center; guide blades are provided at the oxygen channel to allow oxygen to rotate in and mix evenly with the rotary kiln exhaust gas.

4. The catalytic reaction device for pre-decomposition of cement raw materials and simultaneous co-production of synthesis gas according to claim 1, characterized in that: A flame arrester is provided at the connection between the first suspended catalytic bed and the combustion section.

5. The catalytic reaction device for pre-decomposition of cement raw materials and simultaneous co-production of synthesis gas according to claim 1, characterized in that: The top and bottom of the first suspended catalytic bed and the top and bottom of the second suspended catalytic bed are both provided with catalyst barrier nets; The first suspended catalytic bed and the second suspended catalytic bed are both cylindrical structures, and the diameter of the second suspended catalytic bed is 1.1 to 1.5 times the diameter of the first suspended catalytic bed; The second catalyst inlet is located on the upper portion of the second suspended catalytic bed and is used for adding the second catalyst; the first catalyst inlet is located on the upper portion of the first suspended catalytic bed and is used for adding the first catalyst.

6. The catalytic reaction device for pre-decomposition of cement raw materials and simultaneous co-production of synthesis gas according to claim 1, characterized in that: The catalytic reaction synthesis section has an outer shape of a structure that is wide at the top, narrow in the middle, and wide at the bottom.

7. A method for pre-decomposing cement raw meal and simultaneously producing synthesis gas, the method being implemented based on the catalytic reaction device for pre-decomposing cement raw meal and simultaneously producing synthesis gas according to any one of claims 1 to 6, characterized in that: The steps include: (1) nitrogen is introduced into the catalytic reaction device through the bottom gas inlet to replace the air in the device with nitrogen. After the airflow is stable, the second catalyst is first added to the second catalyst feeding port. After the second catalyst is stably suspended in the second suspended catalyst bed for a period of time, the first catalyst is added to the first catalyst feeding port to keep the first catalyst in a suspended state in the first suspended catalyst bed; (2) introducing high-temperature gas into the heating gas inlet of the catalyst bed, preheating the two suspended catalyst beds to a certain temperature through the spiral heat exchange tube, maintaining it for a certain period of time, gradually switching the nitrogen introduced into the gas inlet one to the preheated reducing gas, stabilizing it at a certain reducing temperature for a period of time, and then heating the two suspended catalyst beds to the temperature required for the reaction; (3) Mixing the preheated natural gas with the raw meal to form a first material-gas mixture, gradually reducing the amount of reducing gas in the gas inlet, and passing the first material-gas mixture to the combustion section through the material-gas mixture inlet; mixing the preheated oxygen with the rotary kiln exhaust gas cooled to a certain temperature to form a mixed gas, and passing the mixed gas 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 oxidation reaction, generating carbon dioxide and water vapor and releasing heat to form a gas-solid mixture; then, the mixture moves upward to the lower position of the first suspended catalytic bed; (4) Oxygen is introduced into the lower portion of the first suspended catalyst bed through the second gas inlet; the raw meal is mixed with the preheated natural gas through the second feed buffer device to form a second feed-gas mixture; a portion of the second feed-gas mixture enters the lower portion of the first suspended catalyst bed through the second feed-gas mixture inlet; After the gas-solid mixture 1, oxygen and a portion of the second feed gas mixture are evenly mixed, they enter the first suspended catalytic bed to undergo a methane oxidation reaction, generating carbon dioxide and water vapor and releasing heat. Simultaneously, a methane steam reforming reaction occurs to generate a gas-solid mixture 2, which then continues to move upward to a position between the first and second suspended catalytic beds. (5) oxygen is introduced into the position between the first suspended catalyst bed and the second suspended catalyst bed through the gas inlet three; a portion of the second feed gas mixture is introduced into the position between the first suspended catalyst bed and the second suspended catalyst bed through the feed gas mixture inlet three; After being evenly mixed, the gas-solid mixture 2, oxygen and a portion of the second feed gas mixture enter the second suspended catalytic bed to undergo a methane carbon dioxide reforming reaction to generate a gas-solid mixture 3, which then continues to move upward and exits the reaction device through the gas-solid mixture outlet.

8. The method for pre-decomposition of cement raw meal and simultaneous co-production of synthesis gas according to claim 1, characterized in that: When the reaction unit is shut down, first stop introducing raw materials and rotary kiln combustion exhaust gas, then stop introducing natural gas, and finally stop introducing oxygen. During this process, nitrogen is gradually introduced into the gas inlet to ensure that all the gas in the reaction unit is replaced by nitrogen. Then, turn off the nitrogen, remove the catalyst and other solid impurities from the material accident discharge port at the bottom of the reaction unit, and recover the catalyst through screening.

9. The method for pre-decomposition of cement raw meal and simultaneous co-production of synthesis gas according to claim 1, characterized in that: The second catalyst includes a methane-carbon dioxide reforming catalyst and a small amount of a methane-water steam reforming catalyst; the first catalyst is a methane-water steam reforming catalyst; The methane carbon dioxide reforming catalyst particles are spherical, ellipsoidal or irregular particles with a particle size of 0.3 to 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 to 1.5 mm.

10. The method for pre-decomposition of cement raw meal and simultaneous co-production of synthesis gas according to claim 1, characterized in that: In step (2), the source of the high-temperature gas is the flue gas from the rotary kiln outlet, or the 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°C; the reducing gas is H2, CO or a mixture thereof, the temperature of the preheated reducing gas is 400-550°C, the reducing gas is introduced and maintained for 1-3 hours, and the reduction temperature is 450-600°C.

11. The method for pre-decomposition of cement raw meal and simultaneous production of synthesis gas according to claim 1, characterized in that: 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.

12. The method for pre-decomposition of cement raw meal and simultaneous co-production of synthesis gas according to claim 1, characterized in that: In step (4), the first suspended catalyst bed is in an oxygen-deficient state, with an oxygen concentration of <0.3%; the reaction temperature of the first suspended catalyst bed is 650-750°C, and the reaction space velocity is 2000h -1 ~4000h -1 ; The main components of gas-solid mixture 2 are raw meal, CH4, CO, H2 and CO2.

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

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