Oxygen carrier recovery system and method for solid fuel chemical looping combustion device

Abstract

The invention discloses an oxygen carrier recovery system and method for a solid fuel chemical looping combustion device. The system comprises a first collector, a second collector, a first discharge valve, a second discharge valve, an air blower, a heat exchanger, a dryer, an electric separator, an ash bin, an airflow powder classifier, a fine powder recovery bin and a screw particle feeder. Wherein the first collector is arranged in a flue of the air reactor; the second collector is arranged in a flue of the fuel reactor; a material outlet of the dryer is opposite to an inlet of the electric separator, a dry air outlet of the dryer is communicated with a tail flue of the air reactor, and the communication position is located at the upstream of the first collector. According to the system disclosed by the invention, the separation of the oxygen carrier and the fly ash is realized by utilizing an electrostatic separation technology, the effective recovery of a non-magnetic oxygen carrier material is realized, the recovered oxygen carrier is graded, and the oxygen carrier with a larger particle size is sent back to the serial fluidized bed reactor, so that the oxygen carrier with the larger particle size is fully utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical-looping combustion, and particularly relates to an oxygen carrier recovery system for a solid fuel chemical-looping combustion device and an oxygen carrier recovery method for a solid fuel chemical-looping combustion device. Background Art

[0002] Since the Industrial Revolution, carbon emissions caused by human activities have become the main cause of global climate change, and fossil fuel combustion is the main source of carbon emissions. At present, fossil fuels account for more than 80% of China's primary energy structure. To address climate change, China has proposed the "dual carbon" strategy, and carbon capture and storage has become an important technical path for carbon emission reduction during fossil fuel combustion. Due to advantages such as in-situ separation of carbon dioxide and low carbon capture cost, chemical-looping combustion technology has become one of the most promising low-cost carbon capture technologies. This technology realizes fuel combustion by the cyclic transfer of oxygen between an air reactor and a fuel reactor through an oxygen carrier, and the carbon dioxide concentration in the combustion products is high, enabling in-situ capture.

[0003] Chemical-looping combustion is a two-step combustion process that uses an oxygen carrier to cycle between an air reactor and a fuel reactor to transfer oxygen from the air to the fuel. In the air reactor, the oxygen carrier first undergoes an oxidation reaction by contacting air at high temperature to obtain lattice oxygen; subsequently, the oxygen carrier is transported to the fuel reactor, where it oxidizes and burns the fuel by releasing lattice oxygen while being reduced itself. The oxygen carrier enables continuous chemical-looping combustion through alternating oxidation-reduction cycles. Since lattice oxygen replaces air to support fuel combustion, the water vapor and carbon dioxide generated by combustion are not diluted by nitrogen. After the tail gas of the fuel reactor condenses water vapor, high-concentration carbon dioxide can be obtained for in-situ capture.

[0004] In circulating fluidized bed chemical-looping combustion, the high wear rate of the oxygen carrier is one of the main bottleneck problems currently faced. The mechanical stress generated by the collision between the oxygen carrier particles and the wall surface and between the particles will cause mechanical wear; since the combustion device is in a high-temperature environment, high-temperature operation will have a thermal stress effect on the oxygen carrier, resulting in thermal wear; in addition, since the oxygen carrier undergoes alternating oxidation and reduction chemical reactions in chemical-looping combustion, more serious chemical wear caused by chemical stress will occur. In the actual operation of a chemical-looping combustion system, the wear of the oxygen carrier is jointly affected by the above three wear modes, leading to the wear of fluidized particles. The fine oxygen carrier particles generated by this wear will be discharged from the chemical-looping combustion device along with the flue gas. The chemical-looping combustion system usually has a very long operation cycle, and the wear of the oxygen carrier particles will cause a reduction in the bed material inventory. Therefore, it is necessary to continuously supplement new oxygen carrier particles during operation to ensure sufficient bed material and maintain the normal operation of the fluidized bed. Due to the large demand for oxygen carriers and the need for continuous supplementation, if this part of the worn oxygen carrier material can be recovered, losses can be avoided and reuse can be achieved, which can significantly reduce the cost of using oxygen carriers. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the first object of the present invention is to propose an oxygen carrier recovery system for a solid fuel chemical looping combustion device, which uses electrostatic separation technology to separate the oxygen carrier from fly ash, realizes the effective recovery of non-magnetic oxygen carrier materials, classifies the recovered oxygen carriers, and sends the oxygen carriers with larger particle sizes back to the serial fluidized bed reactor, making full use of the oxygen carriers with larger particle sizes.

[0006] The second object of the present invention is to propose a method for recovering oxygen carriers for a solid fuel chemical looping combustion device.

[0007] To achieve the above object, an embodiment of the first aspect of the present invention proposes an oxygen carrier recovery system for a solid fuel chemical looping combustion device. The system includes: a first collector, a second collector, a first discharge valve, a second discharge valve, a blower, a heat exchanger, a dryer, an electrostatic separator, an ash bin, an air flow powder classifier, a fine powder recovery bin, and a screw particle feeder; wherein,

[0008] The first collector is arranged in the air reactor flue. The bottom outlet of the first collector faces the top inlet of the first discharge valve, and the bottom outlet of the first discharge valve faces the material inlet of the dryer; the second collector is arranged in the fuel reactor flue. The bottom outlet of the second collector faces the top inlet of the second discharge valve, and the bottom outlet of the second discharge valve faces the material inlet of the dryer; the material outlet of the dryer faces the inlet of the electrostatic separator. The first outlet of the electrostatic separator faces the inlet of the ash bin, and the second outlet of the electrostatic separator faces the inlet of the air flow powder classifier. The first outlet of the air flow powder classifier faces the inlet of the fine powder recovery bin, and the second outlet of the air flow powder classifier faces the inlet of the screw particle feeder; the inlet of the blower is connected to the air, and the outlet of the blower is connected to the air side inlet of the heat exchanger. The air side outlet of the heat exchanger is connected to the drying air inlet of the dryer, and the drying air outlet of the dryer is connected to the tail flue of the air reactor, and the connection position is upstream of the first collector.

[0009] In addition, the oxygen carrier recovery system for a solid fuel chemical looping combustion device according to the above embodiment of the present invention may further have the following additional technical features:

[0010] According to an embodiment of the present invention, both the first collector and the second collector are bag filters. The air inlet of the first collector is connected to the tail flue of the air reactor, and the ash hopper at the lower part of the filter bag of the first collector is connected to the top inlet of the first discharge valve; the second collector is connected to the tail flue of the fuel reactor, and the ash hopper at the lower part of the filter bag of the second collector is connected to the top inlet of the second discharge valve.

[0011] According to an embodiment of the present invention, the heat exchanger is a tubular heat exchanger or a plate heat exchanger, which is arranged in the tail flue of the air reactor and the installation position is upstream of the first collector; alternatively, it is arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector.

[0012] According to an embodiment of the present invention, the electrostatic separator is a friction electrostatic belt separator.

[0013] According to an embodiment of the present invention, the pneumatic powder classifier includes a feeding control unit, a classifier main body, a high-efficiency cyclone collector, a pulse bag filter, a high-pressure induced draft fan and an electrical control system.

[0014] To achieve the above object, a second aspect embodiment of the present invention proposes an oxygen carrier recovery method for a solid fuel chemical looping combustion device. The method is based on the system of the above embodiment, and the method includes:

[0015] S1. Use the first collector to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the air reactor and temporarily store them in the ash hopper of the first collector. Use the second collector to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the fuel reactor and temporarily store them in the ash hopper of the second collector;

[0016] S2. Open the first discharge valve and the second discharge valve, and discharge the fine particulate matters temporarily stored in the ash hoppers of the first collector and the second collector through the first discharge valve and the second discharge valve respectively. The fine particulate matters are sent to the dryer;

[0017] S3. The blower sends fresh air into the heat exchanger. The normal-temperature fresh air becomes hot air at 140 to 280 °C after heat exchange through the heat exchanger and enters the dryer as hot drying air; fly ash and oxygen carrier fine particles enter from one end of the dryer and contact the hot drying air countercurrently in the dryer. After removing moisture, they are discharged from the other end of the dryer. Control the discharge temperature of the material above 80 °C for the next sorting; the used drying hot air is discharged into the tail flue of the air reactor, and the first collector is used to treat the dust carried during the drying process;

[0018] S4. The hot fly ash and the fine oxygen carrier particles after drying enter the electrostatic separator. In the feeding section of the electrostatic separator, due to different surface charging properties, charge transfer occurs during the contact and friction between the oxygen carrier and fly ash particles through the triboelectrification effect, causing the oxygen carrier and fly ash to carry different charges. Subsequently, when the oxygen carrier and fly ash carrying different charges pass through the electric field in the electrode region, each charged fine particle moves a small distance towards the flat electrode with the opposite charge and adheres to the annular conveyor belt on the surface of the flat electrode. As the belt moves, it leaves the electrode region to achieve separation. The fly ash obtained after separation is discharged into the ash bin for fly ash treatment. The oxygen carrier obtained after separation is recycled for the next step of classification and utilization.

[0019] S5. The recycled oxygen carrier is further transported to the pneumatic powder classifier for particle size classification. Through the pneumatic powder classifier, it is classified into large particle oxygen carriers and oxygen carrier powders according to the set classification particle size. Among them, the large particle oxygen carriers still meet the requirements for use in the serial fluidized bed and continue to be used for chemical looping combustion. They are sent back to the air reactor through the screw particle feeder. The oxygen carrier powder has no direct utilization value and is recycled as waste oxygen carrier material for use as a raw material for preparing recycled oxygen carriers.

[0020] In addition, according to the oxygen carrier recovery method of the solid fuel chemical looping combustion device in the above embodiments of the present invention, the following additional technical features may also be provided:

[0021] According to an embodiment of the present invention, in step S4, in the mixture of hot fly ash and fine oxygen carrier particles before separation, the mass ratio of the fine oxygen carrier particles ranges from 4% to 80%; the separable powder particle size range is from 0.5 microns to 300 microns.

[0022] According to an embodiment of the present invention, in step S4, the ground voltage applied to the flat electrode is between ±4 to ±10 kV, and the total voltage difference between the two electrodes is 8 to 20 kV; the gap adjustment range between the flat electrode and the annular conveyor belt is 9 to 18 mm, and the linear speed of the annular conveyor belt is 4 to 20 m / s.

[0023] According to an embodiment of the present invention, in step S4, the residual oxygen carrier mass fraction in the fly ash obtained after separation is 1% - 0.5%.

[0024] According to an embodiment of the present invention, in step S5, the classification particle size is 42 microns.

[0025] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the following technical advantages are mainly presented:

[0026] An oxygen carrier recovery system and method for a solid fuel chemical looping combustion device provided by the present invention are located at the end of the chemical looping combustion device, do not affect the normal operation of the chemical looping combustion device, and are suitable for retrofitting existing chemical looping combustion devices; the hourly processing capacity is as high as 23 tons, with a large processing capacity; the drying process utilizes the waste heat of the flue gas of the chemical looping combustion device and does not emit additional dust-containing gases. The power consumption per ton of material processed is about 1 kWh, mainly consumed by the drive motor, which is energy-saving and environmentally friendly; the applicable range of oxygen carrier materials is wide, effective for both insulating and conductive materials, and various types of oxygen carrier materials can be separated from fly ash by utilizing the difference in surface charge properties after contact and friction of different materials; the particle size range that can be processed is wide, and it is very suitable for separating very fine (<1 micron) to medium (~300 micron) particles. In particular, it can effectively separate fine-grained materials smaller than 75 microns that cannot be separated by conventional electrostatic separation technology at all; the mass ratio of oxygen carriers in the separated fly ash is less than 1%, and the separation is efficient; the separated oxygen carriers are respectively sent back to the serial fluidized bed reactor for reuse and recovered as fine powder according to different particle sizes, and the utilization is sufficient.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be understood through the practice of the present invention. Brief Description of the Drawings

[0028] Figure 1 It is a schematic diagram of an oxygen carrier recovery system for a solid fuel chemical looping combustion device according to an embodiment of the present invention.

[0029] The solid arrow in the figure represents the powder material flow direction, and the dashed arrow represents the gas material flow direction.

[0030] Reference Signs:

[0031] 1. First collector; 2. Second collector; 3. First discharge valve; 4. Second discharge valve; 5. Blower; 6. Heat exchanger; 7. Dryer; 8. Electrostatic separator; 9. Ash bin; 10. Airflow powder classifier; 11. Fine powder recovery bin; 12. Screw particle feeder. Detailed Embodiments

[0032] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0033] The oxygen carrier recovery system for a solid fuel chemical looping combustion device and the oxygen carrier recovery method for a solid fuel chemical looping combustion device proposed by the embodiments of the present invention will be described below with reference to the drawings.

[0034] As Figure 1 shown, the oxygen carrier recovery system for a solid fuel chemical looping combustion device according to an embodiment of the present invention may include: a first collector 1, a second collector 2, a first discharge valve 3, a second discharge valve 4, a blower 5, a heat exchanger 6, a dryer 7, an electrostatic separator 8, an ash bin 9, an air classifier 10, a fine powder recovery bin 11, and a screw particle feeder 12; wherein, the first collector 1 is arranged in the air reactor flue, the bottom outlet of the first collector 1 faces the top inlet of the first discharge valve 3, and the bottom outlet of the first discharge valve 3 faces the material inlet of the dryer 7; the second collector 2 is arranged in the fuel reactor flue, the bottom outlet of the second collector 2 faces the top inlet of the second discharge valve 4, and the bottom outlet of the second discharge valve 4 faces the material inlet of the dryer 7; the material outlet of the dryer 7 faces the inlet of the electrostatic separator 8, the first outlet of the electrostatic separator 8 faces the inlet of the ash bin 9, the second outlet of the electrostatic separator 8 faces the inlet of the air classifier 10, the first outlet of the air classifier 10 faces the inlet of the fine powder recovery bin 11, and the second outlet of the air classifier 10 faces the inlet of the screw particle feeder 12; the inlet of the blower 5 is in communication with the air, the outlet of the blower 5 is connected to the air side inlet of the heat exchanger 6, the air side outlet of the heat exchanger 6 is connected to the drying air inlet of the dryer 7, and the drying air outlet of the dryer 7 is in communication with the tail flue of the air reactor, and the communication position is upstream of the first collector 1.

[0035] Specifically, as Figure 1 shown, after the oxygen carrier recovery system operates, first, the first collector 1 is used to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the air reactor flue gas and temporarily store them in the ash hopper of the first collector 1, and the second collector 2 is used to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the fuel reactor flue gas and temporarily store them in the ash hopper of the second collector 2. Then, the first discharge valve 3 and the second discharge valve 4 are opened, and the fine particles temporarily stored in the ash hoppers of the first collector 1 and the second collector 2 are respectively discharged through the first discharge valve 3 and the second discharge valve 4, and the fine particles are sent to the dryer 7. It should be noted that the first discharge valve 3 and the second discharge valve 4 can prevent the flue gas in the tail flue of the air reactor and the tail flue of the fuel reactor from communicating with the atmospheric environment, and prevent the flue gas from leaking or air from entering the flue.

[0036] It should be understood that when chemical-looping combustion is carried out using a circulating fluidized bed reactor, steam is often used as the fluidizing gas and gasifying agent in the air reactor and the fuel reactor. The temperature in the flue gas duct is relatively high, and the steam does not condense. After the particulate matter is collected and discharged, it will be cooled due to exposure to the normal temperature environment, resulting in the condensation of steam and an increase in the conductivity of the particulate matter. As a result, the oxygen carrier and fly ash cannot carry different kinds of charges, and electrostatic separation cannot be carried out. Therefore, the material needs to be dried before electrostatic separation. Specifically, the blower 5 sends fresh air into the heat exchanger 6. The normal temperature fresh air becomes hot air at 140 to 280 °C after heat exchange in the heat exchanger 6 and enters the dryer 7 as the hot drying air; the fly ash and fine oxygen carrier particles enter from one end of the dryer 7 and contact the hot drying air countercurrently in the dryer 7. After removing the moisture, they are discharged from the other end of the dryer 7. The discharge temperature of the material is controlled above 80 °C for the next separation step; the used hot drying air is discharged into the tail flue of the air reactor, and the first collector 1 is used to treat the dust carried during the drying process.

[0037] Furthermore, the hot fly ash and fine oxygen carrier particles after drying enter the electrostatic separator 8. In the feeding section of the electrostatic separator 8, due to the different surface charging properties of the oxygen carrier and fly ash particles, a charge transfer phenomenon occurs during the contact and friction process between the particles through the triboelectric effect, causing the oxygen carrier and fly ash to carry different charges; subsequently, when the oxygen carrier and fly ash carrying different charges pass through the electric field in the electrode region, each charged fine particle moves a small distance towards the flat electrode with the opposite charge and adheres to the annular conveyor belt on the surface of the flat electrode. As the belt moves, it leaves the electrode region to achieve separation; the fly ash obtained after separation is discharged into the ash bin 9 and processed according to the fly ash treatment; the oxygen carrier obtained after separation is recycled for the next step of classification and utilization. The recycled oxygen carrier is further transported to the air classifier 10 for particle size classification. Through the air classifier 10, it is classified into large particle oxygen carriers and oxygen carrier powders according to the set classification particle size; among them, the large particle oxygen carriers still meet the requirements for use in the circulating fluidized bed and are continuously used for chemical-looping combustion and are sent back to the air reactor through the screw particle feeder 12; the oxygen carrier powder has no direct utilization value and is recycled as waste oxygen carrier material and used as the raw material for preparing the regenerated oxygen carrier.

[0038] According to an embodiment of the present invention, both the first collector 1 and the second collector 2 are bag filters. The air inlet of the first collector 1 is connected to the tail flue of the air reactor, and the ash hopper at the lower part of the filter bag of the first collector 1 is connected to the top inlet of the first discharge valve 3; the second collector 2 is connected to the tail flue of the fuel reactor, and the ash hopper at the lower part of the filter bag of the second collector 2 is connected to the top inlet of the second discharge valve 4.

[0039] According to an embodiment of the present invention, the filter bag materials of the first collector 1 and the second collector 2 are any one of fiberglass, PPS fiber, and PTFE, the filtration accuracy is 0.5 microns, and the operating temperature range is 100 to 250 °C.

[0040] According to an embodiment of the present invention, the heat exchanger 6 is a tubular heat exchanger or a plate heat exchanger, which is arranged in the tail flue of the air reactor and the installation position is upstream of the first collector 1; or, it is arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector 2.

[0041] Specifically, as Figure 1 shown, the heat exchanger 6 is arranged in the tail flue of the air reactor and the installation position is upstream of the first collector 1. The blower 5 sends fresh air into the heat exchanger 6, and the heat exchanger 6 transfers the heat of the flue gas in the tail flue of the air reactor to the air through heat exchange to heat the normal-temperature air.

[0042] Similarly, when the heat exchanger 6 is arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector 2, the blower 5 sends fresh air into the heat exchanger 6, and the heat exchanger 6 transfers the heat of the flue gas in the tail flue of the fuel reactor to the air through heat exchange to heat the normal-temperature air.

[0043] According to an embodiment of the present invention, the electrostatic separator 8 is a friction electrostatic belt separator.

[0044] According to an embodiment of the present invention, the pneumatic powder classifier 10 includes a feeding control unit, a classifier main unit, a high-efficiency cyclone collector, a pulse bag filter, a high-pressure induced draft fan, and an electrical control system.

[0045] In some embodiments of the present invention, the dryer 7 is a rotary dryer or a Venturi dryer.

[0046] Corresponding to the above embodiments, the present invention also proposes an oxygen carrier recovery method for a solid fuel chemical-looping combustion device.

[0047] The oxygen carrier recovery method for a solid fuel chemical-looping combustion device according to the embodiment of the present invention, which is based on the system of the above embodiment, may include the following steps:

[0048] S1, use the first collector 1 to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the air reactor and temporarily store them in the ash hopper of the first collector 1, and use the second collector 2 to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the fuel reactor and temporarily store them in the ash hopper of the second collector 2;

[0049] S2. Open the first discharge valve 3 and the second discharge valve 4 to discharge the fine particulate matters temporarily stored in the hoppers of the first collector 1 and the second collector 2 through the first discharge valve 3 and the second discharge valve 4 respectively. The fine particulate matters are sent to the dryer 7.

[0050] S3. The blower 5 sends fresh air into the heat exchanger 6. The normal-temperature fresh air becomes hot air at 140 to 280 °C after heat exchange in the heat exchanger 6 and enters the dryer 7 as hot drying air. The fly ash and the fine oxygen carrier particles enter from one end of the dryer 7 and contact the hot drying air in a countercurrent manner in the dryer 7. After the moisture is removed, they are discharged from the other end of the dryer 7. Control the discharge temperature of the material above 80 °C for the next separation. The used hot drying air is discharged into the tail flue of the air reactor, and the first collector 1 is used to treat the dust carried during the drying process.

[0051] S4. The dried hot fly ash and the fine oxygen carrier particles enter the electrostatic separator 8. In the feeding section of the electrostatic separator 8, due to different surface charging properties, the oxygen carrier and fly ash particles undergo charge transfer during the contact and friction process between particles through the triboelectrification effect, causing the oxygen carrier and fly ash to carry different charges. Subsequently, when the oxygen carrier and fly ash carrying different charges pass through the electric field of the electrode area, each charged fine particle moves a small distance towards the flat electrode with the opposite charge and adheres to the annular conveyor belt on the surface of the flat electrode. As the belt moves, it leaves the electrode area to achieve separation. The separated fly ash is discharged into the ash bin 9 for fly ash treatment. The separated oxygen carrier is recycled for the next step of classification and utilization.

[0052] S5. The recycled oxygen carrier is further transported to the pneumatic powder classifier 10 for particle size classification. Through the pneumatic powder classifier 10, it is classified into large particle oxygen carriers and oxygen carrier powders according to the set classification particle size. Among them, the large particle oxygen carriers still meet the requirements for use in the serial fluidized bed and continue to be used for chemical looping combustion and are sent back to the air reactor through the screw particle feeder 12. The oxygen carrier powder has no direct utilization value and is recycled as waste oxygen carrier material for use as a raw material for preparing recycled oxygen carriers.

[0053] According to an embodiment of the present invention, in step S4, in the mixture of hot fly ash and fine oxygen carrier particles before separation, the mass ratio of the fine oxygen carrier particles ranges from 4% to 80%; the separable powder particle size range is from 0.5 microns to 300 microns.

[0054] According to an embodiment of the present invention, in step S4, the ground voltage applied to the flat electrode is between ±4 and ±10 kV, and the total voltage difference between the two electrodes is 8 to 20 kV; the gap adjustment range between the flat electrode and the annular conveyor belt is 9 to 18 mm, and the linear velocity of the annular conveyor belt is 4 to 20 m / s.

[0055] According to an embodiment of the present invention, in step S4, the mass fraction of the residual oxygen carrier in the separated fly ash is 1% - 0.5%.

[0056] According to an embodiment of the present invention, in step S5, the classification particle size is 42 microns.

[0057] The following combines two specific embodiments to detail the specific process of the oxygen carrier recovery method for a solid fuel chemical looping combustion device according to the embodiments of the present invention.

[0058] Embodiment 1:

[0059] A perovskite-type oxide oxygen carrier is used, with the composition: CaMn 0.625 Ti 0.125 Fe 0.125 Mg 0.125 O 3-δ ; The solid fuel used is Huolinhe lignite. X-ray fluorescence analysis shows that the main components of the coal ash (in the form of oxides) are 57.21 wt.% SiO2, 20.77 wt.% Al2O3, 8.34 wt.% Fe2O3, 5.99 wt.% CaO, and 1.21 wt.% MgO; The method is as follows:

[0060] S1, Use the first collector 1 to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the air reactor, and use the second collector 2 to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the fuel reactor; The filter bag material of the dust collector is PPS fiber, the filtration accuracy is 0.5 microns, and the working temperature is 180°C; The particle size range of the fly ash and oxygen carrier fine particle mixture is 0.5 microns and above, and more than 93% of the fine particle mixture has a particle size distribution between 1 and 100 microns; After the fly ash and oxygen carrier fine particles are captured by the cloth bag, they are temporarily stored in the ash hopper at the bottom of the bag filter.

[0061] S2. Open the first discharge valve 3 and the second discharge valve 4 to discharge the fine particulate matters temporarily stored in the hoppers of the first collector 1 and the second collector 2 through the first discharge valve 3 and the second discharge valve 4 respectively. The fine particulate matters are sent to the dryer 7. The discharge valve can prevent the flue gas in the tail flue of the air reactor and the tail flue of the fuel reactor from leaking into the atmospheric environment, resulting in pollution, and can also prevent air from entering the tail flue of the fuel reactor, which has an adverse impact on the subsequent carbon dioxide purification and compression processes. The blower 5 sends fresh air into the heat exchanger 6. The normal-temperature fresh air becomes hot air at 260 °C after heat exchange in the heat exchanger 6 and enters the dryer 7 as hot drying air. The fly ash and the fine oxygen carrier particles enter from one end of the dryer 7 and come into countercurrent contact with the hot drying air in the dryer 7 to fully remove the moisture absorbed by the particulate matters in the fuel reactor flue gas with a high water vapor content. After the moisture is removed, they are discharged from the other end of the dryer 7. The discharge temperature of the material is controlled at 105 °C, effectively preventing the dried material from absorbing moisture when it comes into contact with normal-temperature air after being discharged from the dryer, which is beneficial for the next separation step. The temperature of the used hot drying air drops and the humidity rises, containing fine dust, and is discharged into the tail flue of the air reactor. The bag filter of the air reactor is used to treat the dust carried during the drying process.

[0062] S3. The dried hot fly ash and the fine oxygen carrier particles enter the friction electrostatic belt separator. In the mixture of hot fly ash and fine oxygen carrier particles before separation, the fine oxygen carrier particles account for 36.8% of the total mass of the mixture. In the feeding section of the electrostatic separator 8, due to different surface charging properties, the oxygen carrier and fly ash particles undergo charge transfer during the contact and friction process between particles through the triboelectrification effect, making the surface of the oxygen carrier carry positive charges and the surface of the fly ash carry negative charges. Subsequently, when the oxygen carrier carrying positive charges and the fly ash carrying negative charges pass through the electric field of the electrode area, the oxygen carrier moves towards the high-voltage flat negative electrode, and the ground voltage applied to the flat negative electrode is -8 kV, and it adheres to the annular conveyor belt on the surface of the flat negative electrode. The fly ash moves towards the high-voltage flat positive electrode, and the ground voltage applied to the flat positive electrode is +8 kV, and it adheres to the annular conveyor belt on the surface of the flat positive electrode. The gap between the flat electrode and the annular conveyor belt is 9 mm, and the linear velocity of the conveyor belt is 4 m / s. After the oxygen carrier and fly ash adhering to the conveyor belt move away from the electrode area with the belt, most of them fall off the belt due to the disappearance of the electric field force. The oxygen carrier and fly ash that do not fall off are respectively scraped off by the scraper to achieve separation. The separated fly ash is discharged into the ash bin 9 and processed according to the fly ash. The mass fraction of the residual oxygen carrier in the separated fly ash is 0.77%. The separated oxygen carrier is recycled for the next step of classification and utilization.

[0063] S4. The recycled oxygen carriers are further transported to the pneumatic powder classifier 10 for particle size classification. Since the particle size distribution range of the recycled oxygen carriers is relatively large, from 1 micron to 100 microns, in order to achieve the efficient utilization of the recycled oxygen carriers, the oxygen carriers are classified by particle size through the pneumatic powder classifier 10. Among them, the large particle oxygen carriers with a particle size greater than 42 microns still meet the requirements for use in the serial fluidized bed and can continue to be used for chemical looping combustion, and are sent back to the air reactor through the screw particle feeder 12. The oxygen carrier powder with a particle size less than 42 microns has no direct utilization value and is recycled as waste oxygen carrier material and can be used as a raw material for preparing regenerated oxygen carriers. After classification, the mass ratio of the large particle oxygen carriers with a particle size greater than 42 microns is 24.3%, and the mass ratio of the oxygen carrier powder with a particle size less than 42 microns is 75.7%.

[0064] Example 2:

[0065] The structure of the oxygen carrier recovery system for the solid fuel chemical looping combustion device is the same as that in Example 1;

[0066] A synthetic copper-based oxygen carrier is used, with a composition of: 30.0% CuO, 70.0% Al2O3, and non-magnetic. The solid fuel used is Shenhua bituminous coal. X-ray fluorescence analysis shows that the main components of the coal ash (in the form of oxides) are 50.16 wt.% SiO2, 18.75 wt.% Al2O3, 12.82 wt.% CaO, 4.92 wt.% Fe2O3, and 2.07 wt.% MgO. The method is the same as that in Example 1, and the differences are as follows:

[0067] S1. The filter bag materials of the first collector 1 and the second collector 2 are PTFE fibers, with a filtration accuracy of 0.5 microns and an operating temperature of 220 °C. The particle size range of the fly ash and oxygen carrier fine particle mixture is 0.5 microns and above, and more than 72% of the fine particle mixture has a particle size distribution between 1 and 100 microns;

[0068] S2. The blower 5 sends fresh air into the heat exchanger 6. The normal temperature fresh air becomes hot air at 210 °C after heat exchange in the heat exchanger 6 and enters the dryer 7 as hot drying air. The discharge temperature of the material in the dryer 7 is controlled at 90 °C;

[0069] S3. Among the hot fly ash and oxygen carrier fine particle mixture before separation, the oxygen carrier fine particles account for 41.7% of the total mass of the mixture. The ground voltage applied to the flat negative electrode is -16 kV, the ground voltage applied to the flat positive electrode is +16 kV, the gap between the flat electrode and the annular conveyor belt is 12 mm, and the linear velocity of the conveyor belt is 6 m / s. The residual oxygen carrier mass fraction in the separated fly ash is 0.61%;

[0070] S4. The particle size distribution range of the recycled oxygen carriers is from 1 μm to 125 μm; the oxygen carriers are classified according to the particle size by the pneumatic powder classifier 10. Among them, the large particle oxygen carriers with a particle size greater than 53 μm still meet the requirements for use in the serial fluidized bed and can continue to be used for chemical looping combustion, and are sent back to the air reactor through the screw particle feeder 12; the oxygen carrier powder with a particle size less than 53 μm has no direct utilization value and is recycled as waste oxygen carrier material and can be used as the raw material for preparing the regenerated oxygen carrier. After classification, the mass ratio of the large particle oxygen carriers with a particle size greater than 53 μm is 46.2%, and the mass ratio of the oxygen carrier powder with a particle size less than 53 μm is 53.8%.

[0071] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0072] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0073] In the present invention, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0074] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. An oxygen carrier recovery system for a solid fuel chemical looping combustion device, characterized in that, The system includes: a first collector (1), a second collector (2), a first discharge valve (3), a second discharge valve (4), a blower (5), a heat exchanger (6), a dryer (7), an electrostatic separator (8), an ash bin (9), an air-flow powder classifier (10), a fine powder recovery bin (11), and a screw pellet feeder (12); wherein, The first collector (1) is arranged in the flue of the air reactor. The bottom outlet of the first collector (1) faces the top inlet of the first discharge valve (3), and the bottom outlet of the first discharge valve (3) faces the material inlet of the dryer (7). The second collector (2) is arranged in the flue of the fuel reactor. The bottom outlet of the second collector (2) faces the top inlet of the second discharge valve (4), and the bottom outlet of the second discharge valve (4) faces the material inlet of the dryer (7). The material outlet of the dryer (7) faces the inlet of the electrostatic separator (8). The first outlet of the electrostatic separator (8) faces the inlet of the ash bin (9). The second outlet of the electrostatic separator (8) faces the inlet of the air-flow powder classifier (10). The first outlet of the air-flow powder classifier (10) faces the inlet of the fine powder recovery bin (11). The second outlet of the air-flow powder classifier (10) faces the inlet of the screw pellet feeder (12). The inlet of the blower (5) is connected to air, and the outlet of the blower (5) is connected to the air-side inlet of the heat exchanger (6). The air-side outlet of the heat exchanger (6) is connected to the drying air inlet of the dryer (7). The drying air outlet of the dryer (7) is connected to the tail flue of the air reactor, and the connection position is upstream of the first collector (1).

2. The oxygen carrier recovery system for a solid fuel chemical looping combustion device according to claim 1, wherein Both the first collector (1) and the second collector (2) are bag filters. The air inlet of the first collector (1) is connected to the tail flue of the air reactor, and the ash hopper at the lower part of the filter bag of the first collector (1) is connected to the top inlet of the first discharge valve (3). The second collector (2) is connected to the tail flue of the fuel reactor, and the ash hopper at the lower part of the filter bag of the second collector (2) is connected to the top inlet of the second discharge valve (4).

3. The oxygen carrier recovery system for a solid fuel chemical looping combustion device according to claim 1, wherein The heat exchanger (6) is a tubular heat exchanger (6) or a plate heat exchanger (6), which is arranged in the tail flue of the air reactor and the installation position is upstream of the first collector (1); or, it is arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector (2).

4. The oxygen carrier recovery system for a solid fuel chemical looping combustion device according to claim 1, wherein The electrostatic separator (8) is a friction electrostatic belt separator.

5. The oxygen carrier recovery system for the solid fuel chemical looping combustion device according to claim 1, wherein The air-flow powder classifier (10) includes a feeding control unit, a classifier main machine, a high-efficiency cyclone collector, a pulse bag filter, a high-pressure induced draft fan, and an electrical control system.

6. A method for recovering oxygen carriers for a solid fuel chemical looping combustion device, characterized in that, The method is based on the system according to any one of claims 1 to 5, and the method includes: S1. Use the first collector (1) to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the air reactor and temporarily store them in the ash hopper of the first collector (1). Use the second collector (2) to collect fly ash and oxygen carrier fine particles with a particle size greater than 0.5 microns carried in the flue gas of the fuel reactor and temporarily store them in the ash hopper of the second collector (2). S2. Open the first discharge valve (3) and the second discharge valve (4), and discharge the fine particulate matter temporarily stored in the ash hoppers of the first collector (1) and the second collector (2) through the first discharge valve (3) and the second discharge valve (4) respectively. The fine particulate matter is sent to the dryer (7). S3. The blower (5) sends fresh air into the heat exchanger (6). The normal-temperature fresh air becomes hot air at 140 to 280 °C after heat exchange in the heat exchanger (6) and enters the dryer (7) as hot drying air. Fly ash and oxygen carrier fine particles enter from one end of the dryer (7) and come into countercurrent contact with the hot drying air in the dryer (7). After removing moisture, they are discharged from the other end of the dryer (7). Control the discharge temperature of the material above 80 °C for the next separation. The used drying hot air is discharged into the tail flue of the air reactor, and the first collector (1) is used to treat the dust carried during the drying process. S4. The dried hot fly ash and oxygen carrier fine particles enter the electrostatic separator (8). In the feeding section of the electrostatic separator (8), due to different surface charging properties, the oxygen carrier and fly ash particles undergo charge transfer during the contact and friction process between particles through the triboelectrification effect, making the oxygen carrier and fly ash carry different charges. Subsequently, when the oxygen carrier and fly ash carrying different charges pass through the electric field of the electrode area, each charged fine particle moves a small distance towards the flat electrode with the opposite charge and adheres to the annular conveyor belt on the surface of the flat electrode. It is separated as the belt moves away from the electrode area. The fly ash obtained after separation is discharged into the ash silo (9) for fly ash treatment. The oxygen carrier obtained after separation is recycled for the next step of classification and utilization. S5. The recycled oxygen carrier is further transported to the pneumatic powder classifier (10) for particle size classification. Through the pneumatic powder classifier (10), it is classified into large particle oxygen carriers and oxygen carrier powders according to the set classification particle size. Among them, the large particle oxygen carriers still meet the requirements for use in a circulating fluidized bed and are continuously used for chemical looping combustion and sent back to the air reactor through the screw particle feeder (12). The oxygen carrier powder has no direct utilization value and is recycled as waste oxygen carrier material for use as a raw material for preparing regenerated oxygen carriers.

7. The oxygen carrier recovery method for the solid fuel chemical looping combustion device according to claim 6, characterized in that, In step S4, in the mixture of hot fly ash and oxygen carrier fine particles before separation, the mass ratio of oxygen carrier fine particles ranges from 4% to 80%; the separable powder particle size range is from 0.5 microns to 300 microns.

8. The oxygen carrier recovery method for a solid fuel chemical looping combustion device according to claim 6, characterized in that, In step S4, the voltage to ground applied to the flat electrode is between ±4 and ±10 kV, and the total voltage difference between the two electrodes is 8 to 20 kV; the gap between the flat electrode and the annular conveyor belt is adjusted in the range of 9 to 18 mm, and the linear velocity of the annular conveyor belt is 4 to 20 m / s.

9. The oxygen carrier recovery method for a solid fuel chemical looping combustion device according to claim 6, characterized in that, In step S4, the mass fraction of the residual oxygen carrier in the separated fly ash is 1% - 0.5%.

10. The oxygen carrier recovery method for a solid fuel chemical looping combustion device according to claim 6, characterized in that, In step S5, the classification particle size is 42 microns.

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