Reciprocating rotary drum high loading chemical looping co2 capture combustion process

Abstract

This invention relates to a reciprocating rotary kiln high-filling chemical loop CO2 capture and roasting method, comprising: filling an oxygen-carrying medium into a closed rotary kiln; the kiln body alternately rotates forward and backward, and the oxygen-carrying medium moves axially reciprocally through a material guiding structure; sequentially performing oxidation, first purging, reduction, and second purging; the air pipeline and fuel pipeline are interlocked with dual valves and inertial isolation between valves. Oxidation flue gas, carbon dioxide-rich flue gas, and purging mixture are diverted and discharged through corresponding branches, and waste heat is recovered while maintaining diversion. The duration of each stage is adjusted according to the effective volume of the kiln, the filling amount, and online gas detection results; the oxygen-carrying medium can be filled in batches or dynamically replenished and discharged in equal amounts, and is combined with material preheating, double-gate gas seals, composite seals, and explosion relief structures. This method helps reduce oxygen-carrying medium wear and gas cross-contamination, improves atmosphere switching safety, and increases waste heat utilization.

Description

Technical Field

[0001] This invention relates to the fields of chemical chain combustion and carbon dioxide separation technology, and more specifically, to a reciprocating rotary drum high-filling chemical chain CO2 capture and roasting method. Background Technology

[0002] Chemical looping combustion utilizes oxygen-carrying media such as metal oxides to transfer lattice oxygen, separating the fuel oxidation process from air. The oxygen-carrying media releases lattice oxygen and is reduced in the fuel atmosphere, transforming the fuel into a gaseous mixture primarily composed of carbon dioxide and water vapor. The reduced oxygen-carrying media then comes into contact with air to complete oxidation and regeneration. Because the fuel does not directly mix with air, the chemical looping process can generate a high concentration of carbon dioxide gas on the fuel side.

[0003] Existing chemical looping devices mostly employ a dual-reactor fluidized bed. The oxygen-carrying medium needs to circulate continuously between the two reactors and maintain fluidization at a high gas velocity. Although this method ensures sufficient gas-solid contact, frequent collisions between particles and between particles and equipment can easily lead to wear, pulverization, and entrainment. At the same time, the solid circulation channel between the two reactors may cause cross-contamination between the air and fuel sides, allowing nitrogen to be mixed into the fuel-side products, increasing the load on subsequent separation processes.

[0004] In fixed-bed chemical looping devices, the oxygen-carrying medium is essentially stationary, making it difficult to simultaneously handle large-scale, long-cycle operation during bed switching and regeneration. Traditional rotary kilns typically rotate continuously in a single direction while conveying materials, with the material moving unidirectionally from the feed end to the discharge end. This makes it inconvenient to repeatedly subject the same batch of oxygen-carrying medium to oxidation, purging, and reduction atmospheres in a predetermined sequence within the same kiln.

[0005] For rotary chemical looping units, atmosphere switching also involves safety and sealing issues. If only a single valve is used for switching between air and fuel lines, valve leaks or control malfunctions may allow oxidizing and combustible gases to enter the kiln simultaneously. Insufficient sealing of moving parts, feed inlets, and discharge outlets of the rotary kiln can lead to the infiltration of outside air or the leakage of high-temperature flue gas. Directly introducing ambient-temperature oxygen-carrying media into the high-temperature kiln body will also cause a significant temperature drop.

[0006] Furthermore, the oxidation, reduction, and purging times vary for rotary kilns with different effective volumes and loading amounts. Using a fixed duration can easily lead to incomplete reactions or excessive consumption of purging media. If the flue gas from each stage is mixed and discharged through the same pipeline, it will reduce the carbon dioxide enrichment effect and will also hinder the separate utilization of the waste heat from the nitrogen-containing flue gas, carbon dioxide-rich flue gas, and purging gas. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a reciprocating rotary drum high-filling chemical chaining CO2 capture and roasting method to reduce the wear of the oxygen-carrying medium during high-speed fluidization and cross-equipment circulation, reduce the cross-mixing of oxidizing atmosphere and fuel atmosphere, and solve the problems of safe atmosphere switching, staged exhaust, operating parameter adaptation, cold material replenishment and dynamic replenishment and discharge sealing of rotary chemical chaining devices.

[0008] The technical solution adopted by this invention to solve its technical problem is: constructing a reciprocating rotary drum high-filling chemical loop CO2 capture and roasting method, comprising: An oxygen-carrying medium is filled in a closed rotary kiln, and a material guiding structure is provided inside the cylinder of the rotary kiln; the cylinder is controlled to rotate alternately in the forward and reverse directions, so that the material guiding structure drives the oxygen-carrying medium to move in opposite directions along the axial direction of the cylinder during the forward and reverse rotations respectively; Within one cycle, the following stages are executed sequentially: oxidation stage, first purging stage, reduction stage, and second purging stage. In the oxidation stage, oxygen-containing gas is introduced into the rotary kiln to oxidize the reducing oxygen-carrying medium. In the first purging stage, the introduction of oxygen-containing gas is stopped and a purging medium is introduced. In the reduction stage, gaseous fuel is introduced into the rotary kiln to reduce the oxidized oxygen-carrying medium. In the second purging stage, the introduction of gaseous fuel is stopped and a purging medium is introduced. During the oxidation, reduction and purging stages, the corresponding exhaust passages are selectively opened to divert and exhaust the flue gas from each stage, and the cycle is repeated after the second purging stage.

[0009] According to the above scheme, the material guiding structure includes at least one of a spiral guide plate, intermittent spiral blades, and inclined lifting plate disposed on the inner wall of the cylinder. When the cylinder rotates forward, the material guiding structure drives the oxygen-carrying medium to move in a first axial direction. When the cylinder rotates in reverse, the material guiding structure drives the oxygen-carrying medium to move in a second axial direction opposite to the first axial direction.

[0010] According to the above scheme, the air pipeline containing oxygen gas and the fuel pipeline containing gaseous fuel are respectively equipped with dual valve groups. Each dual valve group includes a control valve and a quick-closing valve that are spaced apart along the gas flow direction and shut off when power is lost. An isolation chamber is formed between the two valves. The dual valve groups of the air pipeline and the dual valve groups of the fuel pipeline are mechanically and / or electrically interlocked. Carbon dioxide or inert gas is introduced into the isolation chamber during atmosphere switching.

[0011] According to the above scheme, the first purging stage and the second purging stage use at least one of preheated nitrogen, carbon dioxide, water vapor, and high-temperature inert flue gas as the purging medium; the oxygen content and combustible component concentration in the exhaust gas are detected online, and the corresponding purging stage ends when the oxygen content or combustible component concentration reaches the corresponding preset safety threshold.

[0012] According to the above scheme, the exhaust passage includes a nitrogen-containing flue gas branch, a carbon dioxide-rich flue gas branch, and a purging mixture branch. The nitrogen-containing flue gas branch is activated during the oxidation stage, the carbon dioxide-rich flue gas branch is activated during the reduction stage, and the purging mixture branch is activated during the first purging stage and the second purging stage.

[0013] According to the above scheme, the nitrogen-containing flue gas branch, the carbon dioxide-rich flue gas branch, and the purging mixed gas branch are respectively connected to the heat exchange channels isolated from each other in the waste heat recovery unit, and the flue gas at each stage after heat exchange is kept separate; the carbon dioxide-rich flue gas recovers carbon dioxide after heat exchange and condensation to remove water, and the waste heat recovery unit generates steam and / or provides a preheating heat source for oxygen-carrying medium, gaseous fuel, or purging medium.

[0014] According to the above scheme, the gaseous fuel is methane, synthesis gas containing carbon monoxide and hydrogen, or a mixture thereof. The gaseous fuel is desulfurized before entering the dual valve group of the fuel pipeline, and the total sulfur content after desulfurization is not higher than 20 ppm.

[0015] According to the above scheme, the volume of the oxygen-carrying medium accounts for 15% to 35% of the effective volume of the rotary kiln; the initial running time of the oxidation stage, reduction stage, first purging stage and second purging stage is determined according to the effective volume of the rotary kiln and the amount of oxygen-carrying medium; and the end time of each stage is corrected according to the flue gas composition, temperature and pressure detected online.

[0016] According to the above scheme, the oxygen-carrying medium adopts a batch filling-batch discharging mode or an intermittent dynamic equal-volume replenishment and discharge mode; the oxygen-carrying medium is preheated before entering the kiln; the feeding and discharging components used for dynamic equal-volume replenishment and discharge both include two-stage gates and an air-locking chamber located between the two-stage gates; during replenishment and discharge, inert gas is introduced into the air-locking chamber; the rotating connection of the rotary kiln adopts a composite seal combining mechanical seal and inert gas seal.

[0017] According to the above scheme, the rotary kiln is equipped with explosion-proof doors and explosion-proof holes, and an explosion-proof wall is installed on the outside of the key area of ​​the rotary kiln. When the system is started, the air tightness is checked and the inert gas is replaced with air while the air pipeline and fuel pipeline are closed. The rotary kiln and waste heat recovery unit are gradually heated by the auxiliary heating device. After reaching the preset starting temperature, the oxygen-carrying medium is filled and enters the cycle.

[0018] The reciprocating rotary drum high-filling chemical loop CO2 capture and roasting method of the present invention has the following beneficial effects: 1. This invention completes the oxidation and reduction of the oxygen-carrying medium in the same rotary kiln in a time-sharing manner, reducing the high-speed circulation and transportation of the oxygen-carrying medium between multiple reactors, thereby reducing system complexity and material wear.

[0019] 2. The rotary kiln alternates between forward and reverse rotation, and the material guiding structure causes the oxygen-carrying medium to move back and forth along the axial direction. This can refresh the gas-solid contact interface at a higher loading rate and prevent materials from accumulating in a single position in the cylinder for a long time.

[0020] 3. The oxidation, purging and reduction processes are executed in sequence. The air pipeline and fuel pipeline are connected simultaneously through dual valves, interlocks and inertial isolation between valves to reduce the possibility of simultaneous conduction. Online detection is used to improve the safety of atmosphere switching.

[0021] 4. Flue gas from different stages is discharged through independent branches, which can reduce the mixing of carbon dioxide-rich gas and nitrogen-containing flue gas, and recover waste heat from each branch while maintaining the diversion.

[0022] 5. Pre-desulfurization of fuel helps to delay the decline of the activity of oxygen-carrying media and reduce the treatment load of sulfur-containing pollutants at the downstream end.

[0023] 6. Adjust the duration of each stage according to the equipment volume, filling amount and online detection results to adapt to different specifications of rotary kilns and reduce excessive purging.

[0024] 7. The two modes of batch filling and dynamic equal-volume replenishment can meet the needs of intermittent production and long-cycle operation respectively. Material preheating, double gate air seal and composite seal help reduce the temperature drop and air leakage during replenishment.

[0025] 8. Active isolation and kiln purging are combined with passive protection such as explosion-proof doors, explosion-proof holes, and explosion-proof walls to form a multi-layered safety protection system. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the system used in the reciprocating rotary drum high-filling chemical chain CO2 capture and roasting method of the present invention; Figure 2 This is a schematic diagram of another embodiment of the reciprocating rotary drum high-filling chemical chain CO2 capture and roasting method of the present invention; In the diagram: 1. Rotary kiln; 2. Oxygen-carrying medium; 3. Kiln tail sealing cover; 4. Feeding device; 5. Carbon dioxide and water vapor mixture regulating valve; 6. Nitrogen and water vapor mixture regulating valve; 7. First purging mixture regulating valve; 8. Multi-channel waste heat boiler; 9. First mixture exhaust fan; 10. Nitrogen and water vapor mixture exhaust fan; 11. Carbon dioxide and water vapor mixture exhaust fan; 12. Nitrogen gas holder; 13. Carbon dioxide gas holder; 14. First drive fan; 15. Second drive fan; 16. First heat exchanger; 17. Second heat exchanger; 18. First ejector; 19. Second ejector; 20. Nitrogen opening valve ; 21. Air quick-cut-off valve; 22. Air electric cut-off valve; 23. Fuel quick-cut-off valve; 24. Carbon dioxide opening valve; 25. Fuel electric cut-off valve; 26. Kiln head sealing cover; 27. Discharge device; 28. First flue gas switching valve; 29. ​​Second flue gas switching valve; 30. Material guiding structure; 31. First high-temperature steam quick-cut-off valve; 32. First high-temperature steam electric cut-off valve; 33. Second high-temperature steam quick-cut-off valve; 34. Second high-temperature steam electric cut-off valve; 35. Second purging mixed gas regulating valve; 36. Third purging mixed gas regulating valve; 37. Second mixed gas exhaust fan; 38. Third mixed gas exhaust fan. Detailed Implementation

[0027] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, the invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the drawings are for illustrating the connection relationships between the various components and do not represent actual dimensions or proportions; the control system, online gas analyzer, fuel desulfurization device, condensate removal device, and safety interlock unit, not shown in the drawings, can be configured according to the following functional requirements. Where there is no contradiction, the technical features of the various embodiments can be combined with each other.

[0028] like Figure 1 As shown, the reciprocating rotary kiln chemical loop roasting system includes a rotary kiln 1, an oxygen-carrying medium 2 filled in the rotary kiln 1, a kiln tail sealing cover 3 and a kiln head sealing cover 26 respectively installed at both ends of the rotary kiln 1, a feeding device 4, a discharging device 27, an air inlet unit, a separate exhaust unit, a waste heat recovery unit, and a circulating gas return unit. The rotary kiln 1 is driven by a drive mechanism capable of alternately outputting positive and negative torques to reciprocate according to a set speed, direction, and duration.

[0029] A material guiding structure 30 is provided inside the rotary kiln 1, and the oxygen-carrying medium 2 is located within the material movement area defined by the material guiding structure 30 and the inner wall of the kiln. The material guiding structure 30 can be a continuous spiral guide plate, intermittent spiral blades, a lifting plate inclined relative to the axis of the kiln, or a combination of the above structures. When the rotary kiln 1 rotates in the forward direction, the material guiding structure 30 pushes the oxygen-carrying medium 2 to move along the axial direction of the kiln in the first direction; when the rotary kiln 1 rotates in the reverse direction, the material guiding structure 30 pushes the oxygen-carrying medium 2 to move in the second direction opposite to the first direction, thereby causing the same batch of oxygen-carrying medium 2 to repeatedly migrate, tumble, and renew the gas-solid contact interface within the rotary kiln 1.

[0030] The feeding device 4 is located on the side of the rotary kiln 1 near the kiln tail sealing cover 3, and the discharging device 27 is located on the side of the rotary kiln 1 near the kiln head sealing cover 26. Both the feeding device 4 and the discharging device 27 are sealed and connected to the internal space of the rotary kiln 1. When used for dynamic feeding and discharging, the feeding device 4 and the discharging device 27 are respectively equipped with two-stage gates and an airlock chamber located between the two-stage gates. Nitrogen, carbon dioxide, or other inert gases are introduced into the airlock chamber to suppress the entry of outside air and the leakage of gas from the kiln. The rotary connection between the kiln tail sealing cover 3, the kiln head sealing cover 26, and the rotary kiln 1 adopts a composite sealing structure combining mechanical seal and inert gas seal.

[0031] The intake unit includes an air intake branch and a fuel intake branch. Along the airflow direction, the air intake branch is sequentially equipped with an air quick-cut-off valve 21 and an air electrically operated shut-off valve 22. The nitrogen opening valve 20 is connected to the valve isolation section between the air quick-cut-off valve 21 and the air electrically operated shut-off valve 22. Along the fuelflow direction, the fuel intake branch is sequentially equipped with a fuel quick-cut-off valve 23 and a fuel electrically operated shut-off valve 25. The carbon dioxide opening valve 24 is connected to the valve isolation section between the fuel quick-cut-off valve 23 and the fuel electrically operated shut-off valve 25. The air quick-cut-off valve 21, the air electrically operated shut-off valve 22, the fuel quick-cut-off valve 23, and the fuel electrically operated shut-off valve 25 are electrically connected to the control system. The control system uses hard-wired interlocking, program interlocking, or a combination of both to ensure that the air intake branch and the fuel intake branch cannot be simultaneously in a conductive state.

[0032] The separate exhaust unit is located on the exhaust side of the rotary kiln 1 and includes a carbon dioxide and water vapor mixture regulating valve 5, a nitrogen and water vapor mixture regulating valve 6, and a first purging mixture regulating valve 7. These three regulating valves are respectively connected to isolated heat exchange channels in the multi-channel waste heat boiler 8, ensuring physical separation of the reduction stage flue gas, oxidation stage flue gas, and purging stage flue gas during heat exchange. The multi-channel waste heat boiler 8 can utilize the high-temperature gases from each stage to generate steam, or provide a heat source for preheating the oxygen-carrying medium, fuel, and purging medium.

[0033] The branch containing the carbon dioxide and water vapor mixture regulating valve 5 is connected to the carbon dioxide and water vapor mixture exhaust fan 11 via the first heat exchange channel of the multi-channel waste heat boiler 8; the branch containing the nitrogen and water vapor mixture regulating valve 6 is connected to the nitrogen and water vapor mixture exhaust fan 10 via the second heat exchange channel of the multi-channel waste heat boiler 8; and the branch containing the first purge mixture regulating valve 7 is connected to the first mixture exhaust fan 9 via the third heat exchange channel of the multi-channel waste heat boiler 8. After heat exchange and water removal by the condensation and dehydration device, the carbon dioxide and water vapor mixture can enter the carbon dioxide gas holder 13; the nitrogen and water vapor mixture can enter the nitrogen gas holder 12 after heat exchange and water removal as needed; the purge mixture is recycled, purified, or discharged based on online monitoring results.

[0034] The circulating gas outlet of the carbon dioxide gas holder 13 is directly connected to the first drive fan 14, and the outlet of the first drive fan 14 is connected to the first ejector 18 via the first heat exchanger 16. The circulating gas outlet of the nitrogen gas holder 12 is directly connected to the second drive fan 15, and the outlet of the second drive fan 15 is connected to the second ejector 19 via the second heat exchanger 17. The first ejector 18 and the second ejector 19 are connected to the air inlet end of the rotary kiln 1 or the kiln head sealing cover 26, and are used to send pressurized and preheated carbon dioxide circulating gas, nitrogen circulating gas or other inert circulating gas into the rotary kiln 1. The first heat exchanger 16 and the second heat exchanger 17 can use the heat medium output from the multi-channel waste heat boiler 8 or other process waste heat to preheat the circulating gas.

[0035] The first flue gas switching valve 28 and the second flue gas switching valve 29 are installed on the recirculation return pipeline and electrically connected to the control system. Based on the current state of the oxidation stage, the first purging stage, the reduction stage, and the second purging stage, the control system selects to open at least one of the first flue gas switching valve 28 and the second flue gas switching valve 29 to control the recirculation gas entering the first injector 18 and / or the second injector 19. When the first flue gas switching valve 28 and the second flue gas switching valve 29 are closed, the corresponding recirculation return pipeline is isolated from the rotary kiln 1.

[0036] A fuel desulfurization device is installed upstream of the fuel intake branch, and an online gas analyzer is installed on the exhaust side of rotary kiln 1. The control system is connected to each valve, each exhaust fan, each drive fan, the online gas analyzer, and the rotary kiln drive mechanism. The fuel desulfurization device, the online gas analyzer, and the control system are located in... Figure 1 (Not shown in the image). Online gas analyzers are used to detect at least oxygen and combustible components, and can further detect carbon dioxide, carbon monoxide, hydrogen, methane, temperature, and pressure.

[0037] Before starting the system, keep the air quick-cut-off valve 21, air electric shut-off valve 22, fuel quick-cut-off valve 23, and fuel electric shut-off valve 25 closed. Perform an airtightness check on the rotary kiln 1, kiln tail sealing cover 3, kiln head sealing cover 26, feeding device 4, discharging device 27, all gas pipelines, and multi-channel waste heat boiler 8. After the airtightness check is passed, open the nitrogen opening valve 20 and / or carbon dioxide opening valve 24 to perform inertial purging on the isolation section between the two valves. At the same time, introduce inert gas into the rotary kiln 1 through the first injector 18 and / or the second injector 19 to remove residual air or combustible gas from the system.

[0038] After inertial replacement is completed, the rotary kiln 1 and the multi-channel waste heat boiler 8 are gradually heated using an auxiliary burner, an external hot air furnace, or other auxiliary heating devices. During the heating process, the air intake branch and the fuel intake branch are kept closed, and inertial protection is maintained based on pressure and gas composition detection results. After reaching the preset initial temperature, the preheated oxygen-carrying medium 2 is sealed and loaded into the rotary kiln 1 through the feeding device 4. The preheating heat source for the oxygen-carrying medium 2 can be steam generated by the multi-channel waste heat boiler 8, waste heat hot air, or circulating gas heated by the first heat exchanger 16 and the second heat exchanger 17.

[0039] In the batch loading-batch discharging mode, a predetermined amount of oxygen-carrying medium 2 is loaded at once through the feeding device 4, and no replenishment or discharge is performed within a set number of chemical chain cycles. When the oxygen-carrying medium 2 reaches the set number of cycles, the lower limit of activity, or the lower limit of mechanical strength, the cycle stops and the entire batch is discharged through the discharge device 27. In the intermittent dynamic equal-volume replenishment and discharge mode, a basic loading amount is maintained in the rotary kiln 1. After reaching the replenishment and discharge node, preheated fresh oxygen-carrying medium 2 is added through the feeding device 4, and an approximately equal amount of oxygen-carrying medium 2 is discharged through the discharge device 27, so that the loading amount in the rotary kiln 1 remains within the allowable range.

[0040] The normalized cycle process of this invention is as follows: S1, Oxidation Stage. The control system confirms that the fuel quick-cut-off valve 23 and the fuel electric cut-off valve 25 are closed, and introduces carbon dioxide into the intervalve isolation section of the fuel inlet branch through the carbon dioxide opening valve 24 to form gas isolation. The nitrogen and water vapor mixture regulating valve 6 and the nitrogen and water vapor mixture exhaust fan 10 are opened, followed by the opening of the air quick-cut-off valve 21 and the air electric cut-off valve 22, allowing air to enter the rotary kiln 1. The rotary kiln 1 is controlled to rotate alternately in the forward and reverse directions, and the material guiding structure 30 drives the oxygen-carrying medium 2 to move back and forth along the cylinder axis. The reduced oxygen-carrying medium reacts with oxygen in the air and is converted into an oxidized oxygen-carrying medium. The resulting high-temperature gas, mainly composed of nitrogen and containing water vapor and residual oxygen, is sequentially discharged through the nitrogen and water vapor mixture regulating valve 6, the multi-channel waste heat boiler 8, and the nitrogen and water vapor mixture exhaust fan 10. After reaching the preset oxidation endpoint, the air quick-cut-off valve 21 and the air electric cut-off valve 22 are closed.

[0041] S2, First Purging Stage. Keep the air quick-cutoff valve 21, air electric cutoff valve 22, fuel quick-cutoff valve 23, and fuel electric cutoff valve 25 closed. Open the first purging mixture regulating valve 7 and the first mixture exhaust fan 9. According to the preset purging strategy, open the first flue gas switching valve 28 and / or the second flue gas switching valve 29. Preheated carbon dioxide is fed into the rotary kiln 1 from the carbon dioxide gas holder 13 via the first drive fan 14, the first heat exchanger 16, and the first injector 18, and / or preheated nitrogen is fed into the rotary kiln 1 from the nitrogen gas holder 12 via the second drive fan 15, the second heat exchanger 17, and the second injector 19. The purging gas pushes the oxidizing gases in the kiln through the first purging mixture regulating valve 7, the multi-channel waste heat boiler 8, and the first mixture exhaust fan 9 for discharge. When the online gas analyzer detects that the oxygen content is not higher than the preset safety threshold, the first purging ends.

[0042] S3, Reduction Stage. The control system confirms that the air quick-cut-off valve 21 and the air electric cut-off valve 22 are closed, and introduces nitrogen into the inter-valve isolation section of the air intake branch through the nitrogen opening valve 20 to form gas isolation. The first purge mixture regulating valve 7 is closed, and the carbon dioxide and water vapor mixture regulating valve 5 and the carbon dioxide and water vapor mixture exhaust fan 11 are opened. Subsequently, the fuel quick-cut-off valve 23 and the fuel electric cut-off valve 25 are opened, allowing the desulfurized gaseous fuel to enter the rotary kiln 1. The oxidizing oxygen-carrying medium releases lattice oxygen and oxidizes the gaseous fuel, generating a high-temperature gas mainly composed of carbon dioxide and water vapor. This high-temperature gas is sequentially discharged through the carbon dioxide and water vapor mixture regulating valve 5, the multi-channel waste heat boiler 8, and the carbon dioxide and water vapor mixture exhaust fan 11. Taking the general Me / MeO system as an example, syngas can undergo CO+MeO→CO2+Me and H2+MeO→H2O+Me; the overall reaction of methane can be summarized as CH4+4MeO→CO2+2H2O+4Me, and the actual stoichiometric relationship is determined according to the valence state of the oxygen-carrying medium.

[0043] S4, Second Purging Stage. Keep the air quick-cutoff valve 21, air electric cutoff valve 22, fuel quick-cutoff valve 23, and fuel electric cutoff valve 25 closed. Open the first purging mixture regulating valve 7 and the first mixture exhaust fan 9. According to the preset purging strategy, open the first flue gas switching valve 28 and / or the second flue gas switching valve 29 to allow the preheated inert gas supplied through the first injector 18 and / or the second injector 19 to replace the residual fuel, carbon monoxide, hydrogen, or other combustible components in the rotary kiln 1. The purging mixture is discharged by the first mixture exhaust fan 9 after recovering waste heat through the multi-channel waste heat boiler 8. When the online gas analyzer detects that the combustible component content is not higher than the preset safety threshold, the second purging ends, and the process returns to S1 to begin the next cycle.

[0044] S5. Separate heat exchange and recycling. During the oxidation, reduction, and two purging stages, only the corresponding regulating valves 5, 6, or 7 are opened, allowing the gases from different stages to enter the mutually isolated heat exchange channels of the multi-channel waste heat boiler 8. In the reduction stage, the gas is condensed and dehydrated to obtain carbon dioxide-rich gas. A portion of this carbon dioxide-rich gas can be sent to the carbon dioxide gas holder 13 and used as circulating purging gas, while the remainder is output as carbon dioxide product. In the oxidation stage, the gas, after dehydration as needed, can be sent to the nitrogen gas holder 12 and used as circulating purging gas. The purging mixture is returned to the corresponding gas holder, enters the purification device, or is discharged according to its composition.

[0045] The method for determining the operating parameters of this invention is as follows: The control system pre-stores process parameters corresponding to different effective volumes of rotary kilns, oxygen-carrying media loading amounts, oxygen-carrying media types, and fuel types. During the initial run, the initial running lengths of the oxidation stage, the first purging stage, the reduction stage, and the second purging stage are selected based on the effective volume of rotary kiln 1 and the actual loading amount of oxygen-carrying media 2. During operation, the inlet flow rate, cylinder rotation speed, forward and reverse rotation durations, and the end times of each stage are corrected based on the gas composition curves obtained from the online gas analyzer and the changes in temperature and pressure.

[0046] Preferably, the volume of the oxygen-carrying medium 2 accounts for 15% to 35% of the effective volume of the rotary kiln 1, and more preferably 31.7% to 33.6%. The filling range is used to take into account the oxygen-carrying capacity per unit volume of the oxygen-carrying medium 2, the gas flow space, and the reciprocating tumbling space. The specific filling amount is determined by cold and hot tests based on the form of the material guiding structure 30, the particle size or block size of the oxygen-carrying medium 2, and the rotational speed of the rotary kiln 1.

[0047] Preferably, the total sulfur content of the gaseous fuel after desulfurization treatment is not higher than 20 ppm. The criterion for ending the first purging is that the oxygen content detected online is not higher than the safety threshold set for the fuel used and the operating temperature; the criterion for ending the second purging is that the content of combustible components detected online is not higher than a preset proportion of their corresponding lower explosive limit. As a further preferred embodiment, the preset proportion is not higher than 5%.

[0048] Preferably, the temperature of the high-temperature gas entering the multi-channel waste heat boiler 8 at each stage is 700-900℃, and the terminal temperature of the flue gas after heat exchange is 160-180℃. The flow rate, temperature, and pressure of each heat exchange channel of the multi-channel waste heat boiler 8 are controlled separately to recover waste heat at different stages while maintaining gas separation.

[0049] Rotary kiln 1 is also equipped with explosion-proof doors, explosion-proof vents, and explosion-proof walls. The set opening pressure of the explosion-proof doors is preferably 0.12–0.15 MPa. The explosion-proof vents are connected to the safety flow channel. The fire resistance rating of the explosion-proof walls outside the critical areas of rotary kiln 1 is preferably not less than 3 hours. The above parameters should be further verified based on the design pressure, effective volume, fuel properties, and applicable safety regulations of rotary kiln 1.

[0050] Figure 1 The diagram illustrates an arrangement where air and fuel enter from one end of the rotary kiln 1, and gases from each stage exit from the other end. In other embodiments, the air inlet branch, fuel inlet branch, and the first injector 18 and second injector 19 can be arranged either centrally at the same end or opposite at both ends, depending on the kiln length, site conditions, and flow field requirements, as long as valve interlocking and inertial isolation prevent air and fuel from entering the rotary kiln 1 simultaneously and allow gases from different stages to be diverted and discharged.

[0051] The purging media supplied by the first injector 18 and the second injector 19 can be carbon dioxide and nitrogen, respectively, or water vapor, high-temperature inert flue gas, or a combination thereof, depending on the properties of the oxygen-carrying medium 2 and the fuel. For purging media that may react adversely with the oxygen-carrying medium 2, their allowable temperature, flow rate, and contact time should be determined through material compatibility testing.

[0052] In addition to generating steam and power, the multi-channel waste heat boiler 8 can also use the recovered heat for preheating the oxygen-carrying medium 2, preheating gaseous fuel, preheating the purging medium, or supplying heat to the plant area through the first heat exchanger 16, the second heat exchanger 17, or an independent heat exchange circuit. The heat exchange channels of the multi-channel waste heat boiler 8 can be set in the same shell or can be composed of multiple independent heat exchange devices.

[0053] Figure 2 The arrangement of air and fuel entering from both ends of the rotary kiln 1 is shown. In this embodiment, high-temperature steam is used as the purging gas to purge the interior of the rotary kiln. After the oxidation stage, the second high-temperature steam quick-cut-off valve 33, the second high-temperature steam electric cut-off valve 34, the second purging mixed gas regulating valve 35, and the second mixed gas exhaust fan 37 are opened, while other valves are closed, and high-temperature steam purging is performed. During the purging process, the incompletely reacted air in the kiln, the N2 generated during the oxidation stage, and the high-temperature steam are all sent to the multi-channel waste heat boiler 8 via the second purging mixed gas regulating valve 35 to recover waste heat, and then discharged via the second mixed gas exhaust fan 37. The reduction reaction stage can only begin after the oxygen concentration in the kiln is determined to be stably below the explosion limit. After the reduction stage, the first high-temperature steam quick-cut-off valve 31, the first high-temperature steam electric cut-off valve 32, the third purging mixed gas regulating valve 36, and the third mixed gas exhaust fan 38 are opened, while other valves are closed, and high-temperature steam purging is performed. During the purging process, unreacted gaseous fuel, CO2 generated during the reduction stage, and high-temperature steam within the kiln are all sent to the multi-channel waste heat boiler 8 via the third purging mixed gas regulating valve 36 to recover waste heat, and then discharged via the third mixed gas exhaust fan 38. The oxidation reaction stage can only proceed after the concentration of combustible gases within the kiln has been determined to be consistently below the explosion limit. To prevent the third mixed gas exhaust fan 38 from discharging combustible gases such as CO, a combustion device can be installed for combustion treatment.

[0054] and Figure 1 Compared to the same-side setting method, Figure 2 The process involves introducing air and fuel on one side and purging with high-temperature steam on the other. Whether the purging occurs after the oxidation stage or the reduction stage, the flue gas outlet corresponding to the purging is located at the end of the reaction, which is more conducive to the rapid discharge of high-concentration flue gas and can greatly shorten the purging time. Figure 2The embodiment uses high-temperature steam as the purging gas for the rotary kiln, which reduces the need for heat exchangers and ejectors, resulting in a simpler structure. The waste heat from the high-temperature steam can also be recovered and utilized.

[0055] Figure 2 The feed device 4 and discharge device 27 are located on opposite sides, but they can also be located on the same side, i.e., the feed device 4 is also located on the kiln head side. The pipeline containing the steam mixture regulating valve 5 is located on the kiln head side, just like the feed device 4. To prevent CO generated due to incomplete reaction from mixing into the pipeline collecting CO2+H2O during the reduction stage, i.e., the pipeline containing the carbon dioxide and steam mixture regulating valve 5, a fluidized bed or other reducer can be installed on the pipeline containing the carbon dioxide and steam mixture regulating valve 5. This allows the medium in the feed device 4 to capture CO and purify CO2.

[0056] The values ​​in the above embodiments are preferred ranges or example values, and are not intended to limit the scope of protection of this invention. Those skilled in the art can adjust the material and form of the oxygen-carrying medium 2, the size of the rotary kiln 1, the form of the material guiding structure 30, the models of each valve and fan, and the process parameters without departing from the concept of this invention.

[0057] This invention can adopt a batch filling-batch discharging mode. After reaching the set number of cycles, the air and fuel supply is stopped, inert purging is completed, and the material is cooled to the allowable temperature. Then, the oxygen-carrying medium 2 is discharged through the discharge device 27 for testing its activity retention rate, mechanical strength, and wear condition.

[0058] The present invention can also adopt a dynamic equal-volume feeding and discharging mode. At each set number of cycles, preheated fresh oxygen-carrying medium 2 is fed in through the feeding device 4, and at the same time, an approximately equal amount of oxygen-carrying medium 2 is discharged through the discharging device 27. The control system adjusts the air intake flow rate, forward and reverse rotation duration, and stage duration for the subsequent one to three cycles based on the changes in temperature and exhaust composition in the rotary kiln 1 after feeding.

[0059] The online gas analyzer continuously monitors oxygen, carbon dioxide, carbon monoxide, and combustible component content. The control system does not use initial duration as the sole switching condition; instead, it switches valves only after the minimum operating time for a given stage is reached and the corresponding component threshold is met. This prevents insufficient reaction or inadequate purging after equipment scaling up. The gases in carbon dioxide holder 13 and nitrogen holder 12 are returned via the first drive fan 14 and the second drive fan 15, respectively, and are preheated in the first heat exchanger 16 and the second heat exchanger 17 before being recycled as purging gases.

[0060] The gaseous fuel is clean syngas obtained through pressurized gasification and deep desulfurization. The carbon dioxide and water vapor mixture formed in the reduction stage is sequentially discharged through the carbon dioxide and water vapor mixture regulating valve 5, the multi-channel waste heat boiler 8, and the carbon dioxide and water vapor mixture exhaust fan 11. After condensation and dehydration, it enters the carbon dioxide gas holder 13 or the fine treatment reactor.

[0061] The refining reactor is filled with an oxidized oxygen-carrying medium or a carbon monoxide oxidation catalytic medium, which further converts residual carbon monoxide in the carbon dioxide-rich gas into carbon dioxide. The refined oxygen-carrying medium can be returned to rotary kiln 1 under high-temperature conditions or regenerated in a separate regeneration unit. This refining step is optional and does not affect the basic cycle of oxidation-first purging-reduction-second purging within rotary kiln 1.

[0062] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for high-filling chemically chained CO2 capture and roasting using a reciprocating rotary drum, characterized in that, include: An oxygen-carrying medium is filled in a closed rotary kiln, and a material guiding structure is provided inside the cylinder of the rotary kiln; the cylinder is controlled to rotate alternately in the forward and reverse directions, so that the material guiding structure drives the oxygen-carrying medium to move in opposite directions along the axial direction of the cylinder during the forward and reverse rotations respectively; Within one cycle, the following stages are executed sequentially: oxidation stage, first purging stage, reduction stage, and second purging stage. In the oxidation stage, oxygen-containing gas is introduced into the rotary kiln to oxidize the reducing oxygen-carrying medium. In the first purging stage, the introduction of oxygen-containing gas is stopped and a purging medium is introduced. In the reduction stage, gaseous fuel is introduced into the rotary kiln to reduce the oxidized oxygen-carrying medium. In the second purging stage, the introduction of gaseous fuel is stopped and a purging medium is introduced. During the oxidation, reduction and purging stages, the corresponding exhaust passages are selectively opened to divert and exhaust the flue gas from each stage, and the cycle is repeated after the second purging stage.

2. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The material guiding structure includes at least one of a spiral guide plate, intermittent spiral blades, and inclined lifting plate disposed on the inner wall of the cylinder. When the cylinder rotates forward, the material guiding structure drives the oxygen-carrying medium to move in a first axial direction. When the cylinder rotates in reverse, the material guiding structure drives the oxygen-carrying medium to move in a second axial direction opposite to the first axial direction.

3. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The air pipeline containing oxygen gas and the fuel pipeline containing gaseous fuel are each equipped with a dual valve assembly. Each dual valve assembly includes a control valve and a quick-closing valve that closes when power is lost, spaced apart along the gas flow direction, and an isolation chamber is formed between the two valves. The dual valve assemblies of the air pipeline and the dual valve assemblies of the fuel pipeline are mechanically and / or electrically interlocked, and carbon dioxide or inert gas is introduced into the isolation chamber during atmosphere switching.

4. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 3, characterized in that, The first and second purging stages use at least one of preheated nitrogen, carbon dioxide, water vapor, and high-temperature inert flue gas as the purging medium; the oxygen content and combustible component concentration in the exhaust gas are detected online, and the corresponding purging stage ends when the oxygen content or combustible component concentration reaches the corresponding preset safety threshold.

5. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The exhaust passage includes a nitrogen-containing flue gas branch, a carbon dioxide-rich flue gas branch, and a purging mixture branch. The nitrogen-containing flue gas branch is activated during the oxidation stage, the carbon dioxide-rich flue gas branch is activated during the reduction stage, and the purging mixture branch is activated during the first purging stage and the second purging stage.

6. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 5, characterized in that, The nitrogen-containing flue gas branch, the carbon dioxide-rich flue gas branch, and the purging mixed gas branch are respectively connected to the heat exchange channels isolated from each other in the waste heat recovery unit, and the flue gas at each stage after heat exchange is kept separate; the carbon dioxide-rich flue gas recovers carbon dioxide after heat exchange and condensation to remove water, and the waste heat recovery unit generates steam and / or provides a preheating heat source for oxygen-carrying medium, gaseous fuel, or purging medium.

7. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The gaseous fuel is methane, syngas containing carbon monoxide and hydrogen, or a mixture thereof, and the gaseous fuel is desulfurized before entering the dual-valve assembly of the fuel pipeline.

8. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The volume of the oxygen-carrying medium accounts for 15% to 35% of the effective volume of the rotary kiln; the initial running time of the oxidation stage, reduction stage, first purging stage and second purging stage is determined according to the effective volume of the rotary kiln and the amount of oxygen-carrying medium; and the end time of each stage is corrected according to the flue gas composition, temperature and pressure detected online.

9. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 8, characterized in that, The oxygen-carrying medium adopts either a batch filling-batch discharging mode or an intermittent dynamic equal-volume replenishment and discharging mode. The oxygen-carrying medium is preheated before entering the kiln. The feeding and discharging components used for dynamic equal-volume feeding and discharging both include two-stage gates and an airlock chamber located between the two-stage gates. During feeding and discharging, inert gas is introduced into the airlock chamber. The rotating connection of the rotary kiln adopts a composite seal combining mechanical seal and inert gas seal.

10. The method for high-filling chemical looping CO2 capture and roasting using a double rotary drum according to claim 1, characterized in that, The rotary kiln is equipped with explosion-proof doors and explosion-proof holes, and an explosion-proof wall is installed on the outside of the key areas of the rotary kiln. When the system is started, the air tightness is checked and the inert gas is replaced with air and fuel pipelines in the closed state. The rotary kiln and waste heat recovery unit are gradually heated by the auxiliary heating device. After reaching the preset starting temperature, the oxygen-carrying medium is filled and enters the cycle.

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