Solid fuel feeding system and method for moving bed chemical looping combustion reactor

Abstract

The invention aims to provide a solid fuel feeding system and method for a moving bed chemical-looping combustion reactor, and belongs to the technical field of chemical-looping combustion, the solid fuel feeding system comprises a moving bed combustion reactor, a porous funnel-shaped baffle and a cyclone mixing bin are arranged in the moving bed combustion reactor, the cyclone type mixing bin is located at the bottom of the porous funnel-shaped baffle, the porous funnel-shaped baffle is connected with the cyclone type mixing bin through a connecting pipe, a discharging pipe is arranged at the bottom of the cyclone type mixing bin, and a solid fuel feeding pipe is arranged on one side of the moving bed combustion reactor. The solid fuel feeding pipe penetrates through the middle of the side wall of the moving bed combustion reactor and is connected with the wall face of the cyclone type mixing bin in an internally tangent mode, and the cyclone type mixing bin is internally provided with a material distributing cone with the tip facing upwards. By using the feeding system provided by the invention, the fuel and the oxygen carrier can be mixed more uniformly.

Description

Technical Field

[0001] This invention belongs to the field of chemical looping combustion technology, specifically relating to a solid fuel feeding system and method for a moving bed chemical looping combustion reactor. Background Technology

[0002] Human-caused combustion of fossil fuels leads to significant carbon dioxide (CO2) emissions, necessitating effective CO2 capture measures. Current CO2 capture methods primarily include pre-combustion (fuel decarbonization), combustion (oxygen-enriched combustion), and post-combustion (CO2 absorption). However, these three types of CO2 capture processes face high raw material or operating costs, significantly limiting their large-scale utilization.

[0003] Chemical looping combustion is a novel combustion technology that utilizes the lattice oxygen in metal oxides (oxygen carriers) to facilitate the migration of oxygen from the air to the fuel, avoiding direct contact between air and fuel. This allows for the direct acquisition of high-concentration CO2 at the fuel reactor outlet. Based on the type of oxygen carrier movement, fuel reactors can be classified into three categories: fixed-bed, moving-bed, and fluidized-bed. Fixed-bed reactors have poor heat and mass transfer, cannot directly use solid fuels, and have poor operational continuity. Fluidized-bed reactors achieve better heat and mass transfer, but have a large oxygen carrier bed volume and suffer from severe wear. Countercurrent moving-bed reactors can effectively combine the advantages of both, but current research primarily focuses on gaseous fuels, mainly because countercurrent operation of solid fuels and oxygen carriers cannot be achieved. S. Luo, S. Bayham, L. Zeng, O. McGiveron, E. Chung, A. Majumder, LS Fan, Conversion of metallurgical coke and coal using a Coal Direct Chemical Looping (CDCL) moving bed reactor, Appl. Energy. 118 (2014) 300–308.doi:10.1016 / j.apenergy.2013.11.068, proposed the design of a direct solid fuel moving bed chemical looping combustion reactor: a solid fuel inlet is set in the middle of the reactor, the solid fuel first undergoes pyrolysis and gasification reaction, the generated volatiles move upward and react with the highly oxidized oxygen carrier to generate CO2 and water vapor, while the residual char moves downward with the oxygen carrier, and a gasifying agent inlet is added at the bottom of the reactor to further improve the conversion of residual char.

[0004] Because the oxygen carrier hinders the entry of solid fuel, existing technologies use solid fuel that is finer than the oxygen carrier. While this design can achieve solid fuel feeding to some extent, it suffers from severe uneven fuel distribution. Solid fuel is concentrated on the inlet side, resulting in insufficient mixing between the oxygen carrier and solid fuel, further reducing the utilization rate of the oxygen carrier. Summary of the Invention

[0005] The purpose of this invention is to provide a solid fuel feeding system and method for a moving bed chemical looping combustion reactor, which can solve the problem of uneven mixing of fuel and oxygen carrier when traditional solid fuels are directly used in a moving bed chemical looping combustion reactor.

[0006] The present invention adopts the following technical solution: A solid fuel feeding system for a moving bed chemical looping combustion reactor includes a moving bed combustion reactor, wherein the moving bed combustion reactor has an oxygen carrier inlet at the top and an oxygen carrier outlet at the bottom, and a tail gas outlet is provided on one side of the top of the moving bed combustion reactor. The moving bed combustion reactor is equipped with a porous funnel-shaped baffle and a cyclone mixing chamber. The cyclone mixing chamber is located at the bottom of the porous funnel-shaped baffle and is connected to the cyclone mixing chamber through a connecting pipe. The bottom of the cyclone mixing chamber is equipped with a discharge pipe. A solid fuel feed pipe is provided on one side of the moving bed combustion reactor. The solid fuel feed pipe passes through the middle of the side wall of the moving bed combustion reactor and is internally connected to the wall of the cyclone mixing chamber. The cyclone mixing chamber is equipped with a feed cone with its tip pointing upwards.

[0007] Furthermore, the two ends of the porous funnel-shaped baffle are connected to the inner wall of the moving bed combustion reactor.

[0008] Furthermore, the tilt angle of the porous funnel-shaped baffle is greater than the angle of repose of the oxygen carrier, so as to ensure that the oxygen carrier can move smoothly under the action of gravity.

[0009] Furthermore, the sidewall of the porous funnel-shaped baffle is provided with several openings, the diameter of which is smaller than the particle size of the oxygen carrier, to prevent the oxygen carrier from leaking directly while ensuring the smooth passage of volatile gases.

[0010] Furthermore, the porous funnel-shaped baffle, connecting pipe, cyclone mixing bin, distribution cone, discharge pipe, and moving bed combustion reactor are arranged coaxially to ensure uniform flow of oxygen carrier within the reactor.

[0011] Furthermore, the inner wall of the cyclone mixing hopper is provided with several baffles.

[0012] Furthermore, the top wall of the cyclone mixing silo is provided with several vent holes. The diameter of the vent holes is smaller than the particle size of the oxygen carrier particles and solid fuel particles, so as to prevent the oxygen carrier from escaping from the cyclone mixing silo and at the same time ensure that the volatiles move upward.

[0013] Furthermore, the diameter ratio of the cyclone mixing silo to the moving bed combustion reactor is 0.2-0.8; the diameter ratio of the cyclone mixing silo to its overall height is 0.2-0.4.

[0014] Furthermore, the diameters of the connecting pipe, solid fuel feed pipe, and discharge pipe are all greater than 15 times the particle size of the oxygen carrier.

[0015] Furthermore, the diameter ratio of the connecting pipe to the cyclone mixing chamber is 0.4-0.8, the diameter ratio of the solid fuel inlet pipe to the cyclone mixing chamber is 0.45-0.85, and the diameter ratio of the discharge pipe to the cyclone mixing chamber is 0.25-0.75; the ratio of the insertion depth of the connecting pipe into the cyclone mixing chamber to the diameter of the cyclone mixing chamber is 0.5-0.8. This ensures that the oxygen carrier and solid fuel move downwards after being fully mixed, reducing the adverse effects on the mixing caused by airflow.

[0016] Furthermore, the shape of the baffle includes any one or a combination of several of the following: teardrop, conical, cylindrical, and spherical, to achieve thorough mixing of the oxygen carrier and solid fuel.

[0017] A feeding method for a solid fuel feeding system in a moving bed chemical looping combustion reactor includes the following steps: S1. Start the oxygen carrier circulation system to ensure that the oxygen carrier level in the moving bed combustion reactor is higher than the upper edge of the porous funnel-shaped baffle. S2. High-speed airflow carries solid fuel particles from the solid fuel feed pipe into the cyclone mixing chamber, where they move spirally downwards along the wall of the cyclone mixing chamber together with the oxygen carrier and are fully mixed under the turbulence of the baffle plate. The carrier gas used for the solid fuel particles is one or a combination of carbon dioxide, water vapor, and exhaust gas from a moving bed combustion reactor. The flow rate of the carrying gas used in the solid fuel particles is lower than the critical fluidization rate of the oxygen carrier. The temperature of the carrying gas used for the solid fuel particles must not exceed the ignition point of the solid fuel particles.

[0018] The beneficial effects of this invention are as follows: Solid oxygen carrier particles and solid fuel can be mixed more evenly in a cyclone mixing chamber. The cyclone mixing chamber is similar to a cyclone separator. Solid particles move in a circular motion along the wall and move downward under the action of gravity. With the disturbance of the baffles on the wall, the mixing effect of oxygen carrier particles and solid fuel will be better.

[0019] The airflow carries solid fuel into the cyclone mixing chamber, where it mixes with the oxygen carrier and spirals downwards along the wall into the reaction zone of the reactor body. By using a combination of porous funnel-shaped baffles and the cyclone mixing chamber as a solid fuel feeding system, uniform mixing of solid fuel and oxygen carrier is achieved. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the present invention; Wherein: 1-Porous funnel-shaped baffle; 2-Connecting pipe; 3-Solid fuel feed pipe; 4-Cyclone mixing bin; 5-Distribution cone; 6-Discharge pipe; 7-Moving bed combustion reactor; 8-Baffle plate; 9-Oxygen carrier inlet; 10-Oxygen carrier outlet; 11-Tail gas outlet. Detailed Implementation

[0021] The invention will be further described with reference to the accompanying drawings.

[0022] As shown in the figure, a solid fuel feeding system for a moving bed chemical looping combustion reactor includes a moving bed combustion reactor 7. The moving bed combustion reactor 7 has an oxygen carrier inlet 9 at the top and an oxygen carrier outlet 10 at the bottom. The moving bed combustion reactor 7 also has a tail gas outlet 11 on one side of the top. The moving bed combustion reactor 7 is equipped with a porous funnel-shaped baffle 1 and a cyclone mixing chamber 4. The two ends of the porous funnel-shaped baffle 1 are connected to the inner sidewall of the moving bed combustion reactor 7. The cyclone mixing chamber 4 is located at the bottom of the porous funnel-shaped baffle 1. The porous funnel-shaped baffle 1 is connected to the cyclone mixing chamber 4 through a connecting pipe 2. The bottom of the cyclone mixing chamber 4 is equipped with a discharge pipe 6. A solid fuel feed pipe 3 is provided on one side of the moving bed combustion reactor 7. The solid fuel feed pipe 3 passes through the middle of the sidewall of the moving bed combustion reactor 7 and is internally connected to the wall of the cyclone mixing chamber 4. The cyclone mixing chamber 4 is equipped with a feed cone 5 with its tip pointing upwards.

[0023] Furthermore, the tilt angle of the porous funnel-shaped baffle 1 is greater than the angle of repose of the oxygen carrier.

[0024] Furthermore, the sidewall of the porous funnel-shaped baffle 1 is provided with a plurality of openings, the diameter of which is smaller than the particle size of the oxygen carrier.

[0025] Furthermore, the porous funnel-shaped baffle 1, connecting pipe 2, cyclone mixing bin 4, distributing cone 4, unloading pipe 6, and moving bed combustion reactor 7 are arranged coaxially.

[0026] Furthermore, the inner wall of the cyclone mixing hopper 4 is provided with several baffles 8.

[0027] Furthermore, the top wall of the cyclone mixing hopper 4 is provided with several air vents, the diameter of which is smaller than the particle size of the oxygen carrier particles and the solid fuel particles.

[0028] Furthermore, the diameter ratio of the cyclone mixing chamber 4 to the moving bed combustion reactor 7 is 0.2-0.8; the diameter ratio of the cyclone mixing chamber 7 to its overall height is 0.2-0.4.

[0029] Furthermore, the diameters of the connecting pipe 2, the solid fuel feed pipe 3, and the discharge pipe 6 are all greater than 15 times the particle size of the oxygen carrier.

[0030] Furthermore, the diameter ratio of the connecting pipe 2 to the cyclone mixing bin 4 is 0.4-0.8, the diameter ratio of the solid fuel feed pipe 3 to the cyclone mixing bin 4 is 0.45-0.85, and the diameter ratio of the discharge pipe 6 to the cyclone mixing bin 4 is 0.25-0.75; the ratio of the depth of the connecting pipe 2 inserted into the cyclone mixing bin 4 to the diameter of the cyclone mixing bin 4 is 0.5-0.8.

[0031] Furthermore, the shape of the baffle 8 includes any one or a combination of several of the following: teardrop shape, cone shape, cylinder shape, and sphere shape.

[0032] A method for feeding solid fuels into a moving bed chemical looping combustion reactor includes the following steps: The oxygen carrier circulation system is activated to ensure that the oxygen carrier level in the moving bed combustion reactor 7 exceeds the upper edge of the porous funnel-shaped baffle 1. A high-speed carbon dioxide gas stream carries pulverized coal particles from the solid fuel feed pipe 3 into the cyclone mixing chamber 4, where they spiral downwards along the wall of the cyclone mixing chamber 4 together with the copper-iron ore oxygen carrier, undergoing thorough mixing under the turbulence of the baffles. Once the system stabilizes, the carry-on gas stream is switched to the exhaust gas from the moving bed combustion reactor 7, and a waste heat recovery system is used to recover the heat from the exhaust gas, ensuring that the exhaust gas temperature is below the ignition point of the pulverized coal particles.

[0033] The airflow carries solid fuel into the cyclone mixing chamber 4, where it mixes with the oxygen carrier along the wall and spirals downwards into the reaction zone of the moving bed combustion reactor 7. This solves the problem of uneven mixing between fuel and oxygen carrier when solid fuel is directly used in a moving bed chemical looping combustion reactor.

[0034] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. A solid fuel feeding system for a moving bed chemical looping combustion reactor, characterized in that: The moving bed combustion reactor (7) is provided with an oxygen carrier inlet (9) at the top and an oxygen carrier outlet (10) at the bottom. A tail gas outlet (11) is provided on one side of the top of the moving bed combustion reactor (7). The moving bed combustion reactor (7) is provided with a porous funnel-shaped baffle (1) and a cyclone mixing chamber (4). The two ends of the porous funnel-shaped baffle (1) are connected to the inner side wall of the moving bed combustion reactor (7). The cyclone mixing chamber (4) is located at the bottom of the porous funnel-shaped baffle (1). The porous funnel-shaped baffle (1) is connected to the cyclone mixing chamber (4) through a connecting pipe (2). The bottom of the cyclone mixing chamber (4) is provided with a discharge pipe (6). A solid fuel feed pipe (3) is provided on one side of the moving bed combustion reactor (7). The solid fuel feed pipe (3) passes through the middle of the side wall of the moving bed combustion reactor (7) and is internally connected to the wall of the cyclone mixing chamber (4). The cyclone mixing chamber (4) is provided with a feed cone (5) with its tip pointing upwards.

2. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The inclination angle of the porous funnel-shaped baffle (1) is greater than the angle of repose of the oxygen carrier; the sidewall of the porous funnel-shaped baffle (1) is provided with a number of openings, the diameter of which is smaller than the particle size of the oxygen carrier.

3. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The porous funnel-shaped baffle (1), connecting pipe (2), cyclone mixing bin (4), distributing cone (4), unloading pipe (6) and moving bed combustion reactor (7) are arranged coaxially.

4. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The inner wall of the cyclone mixing silo (4) is provided with several baffles (8).

5. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The top wall of the cyclone mixing silo (4) is provided with several air vents, the diameter of which is smaller than the particle size of the oxygen carrier particles and the solid fuel particles.

6. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The diameter ratio of the cyclone mixing silo (4) to the moving bed combustion reactor (7) is 0.2-0.8; the diameter ratio of the cyclone mixing silo (7) to its overall height is 0.2-0.

4.

7. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The diameters of the connecting pipe (2), the solid fuel feed pipe (3), and the discharge pipe (6) are all greater than 15 times the particle size of the oxygen carrier.

8. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 1, characterized in that: The diameter ratio of the connecting pipe (2) to the cyclone mixing silo (4) is 0.4-0.8, the diameter ratio of the solid fuel feed pipe (3) to the cyclone mixing silo (4) is 0.45-0.85, and the diameter ratio of the discharge pipe (6) to the cyclone mixing silo (4) is 0.25-0.75; the ratio of the depth of the connecting pipe (2) inserted into the cyclone mixing silo (4) to the diameter of the cyclone mixing silo (4) is 0.5-0.

8.

9. A solid fuel feeding system for a moving bed chemical looping combustion reactor according to claim 4, characterized in that: The shape of the baffle (8) includes any one or a combination of several of the following: teardrop, conical, cylindrical and spherical.

10. A feeding method for a solid fuel feeding system for a moving bed chemical looping combustion reactor as described in any one of claims 1-8, characterized in that: Includes the following steps: S1. Start the oxygen carrier circulation system to ensure that the oxygen carrier level in the moving bed combustion reactor (7) exceeds the upper edge of the porous funnel-shaped baffle (1); S2. High-speed airflow carries solid fuel particles from the solid fuel feed pipe (3) into the cyclone mixing chamber (4), where they move spirally downward along the wall of the cyclone mixing chamber (4) together with the oxygen carrier and are fully mixed under the turbulence of the baffle plate (8). The carrier gas used for the solid fuel particles is one or a combination of carbon dioxide, water vapor, and the tail gas from the outlet of the moving bed combustion reactor (7). The flow rate of the carrying gas used in the solid fuel particles is lower than the critical fluidization rate of the oxygen carrier. The temperature of the carrying gas used for the solid fuel particles must not exceed the ignition point of the solid fuel particles.

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