Online ash discharge system and method of large chemical looping combustion device

Abstract

The invention discloses an online ash discharge system and method for a large chemical looping combustion device. The system comprises a first collector, a second collector, a first discharger, a second discharger, a screw feeder, a dryer, a magnetic separator, an oxygen carrier recovery bin, an ash bin, an air blower, a heat exchanger and an induced draft fan. An inlet of the screw feeder is respectively opposite to an outlet of the first discharger and an outlet of the second discharger, an outlet of the screw feeder is opposite to a feed port of the dryer, and a discharge port of the dryer is opposite to a feed port of the magnetic separator; an exhaust port of the dryer is connected with an air inlet of the induced draft fan; an exhaust port of the induced draft fan is communicated with a tail flue of the air reactor, and the communication position is located at the upstream of the first collector. The system has the advantages of being high in automation degree, energy-saving, environment-friendly, efficient in separation, large in treatment capacity, capable of avoiding oxygen carrier ash discharge loss, capable of discharging ash on line, free of influence on operation and performance of a chemical looping combustion device and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical looping combustion, and in particular to an on-line ash discharge system for a large-scale chemical looping combustion device and an on-line ash discharge method for a large-scale chemical looping combustion device. Background Art

[0002] At present, fossil fuels account for more than 80% in the primary energy structure of our country. China has proposed the "dual carbon" strategy, and carbon capture and storage has become an important technical path for carbon emission reduction in the process of fossil fuel combustion. Due to advantages such as in-situ separation of carbon dioxide and low cost of carbon capture, chemical looping combustion technology has become one of the most potential low-cost carbon capture technologies. This technology realizes fuel combustion by the cyclic transfer of oxygen carriers between an air reactor and a fuel reactor. The concentration of carbon dioxide in the combustion products is high, and in-situ capture can be achieved.

[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 contacts air at high temperature to undergo an oxidation reaction 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 will not be diluted by nitrogen. After the tail gas of the fuel reactor condenses water vapor, high-concentration carbon dioxide can be obtained to achieve in-situ capture.

[0004] In the early stage, chemical looping combustion technology mainly studied gaseous fuels such as natural gas. Due to the important position of coal in the energy structure, coal chemical looping combustion technology has subsequently become a hot topic. In recent years, chemical looping combustion technologies for solid fuels such as biomass fuels have also been developed. At present, this technology has entered the megawatt-level demonstration stage, and multiple demonstration devices have been built worldwide. The serial double-circulation fluidized bed is the most suitable configuration for large-scale devices, similar to commercial circulating fluidized bed boilers.

[0005] However, the ash generated by solid fuel combustion has an adverse interaction with oxygen carrier particles. For example, the low-melting components in the ash can cause sintering and agglomeration of oxygen carrier particles. The space inside the chemical looping combustion device is limited, and ash needs to be continuously discharged. However, there are many problems with existing ash discharge methods, such as the inability to discharge ash during operation, intermittent ash discharge leading to ash accumulation and oxygen carrier loss, etc. In addition, due to the design and actual efficiency limitations of the cyclone separator, some fine oxygen carrier particles will leave the reactor with the flue gas, further resulting in oxygen carrier loss. Summary of the Invention

[0006] 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 provide an online ash removal system for a large-scale chemical looping combustion device, which has the advantages of high automation, energy conservation and environmental protection, high separation efficiency, large processing capacity, avoiding ash removal loss of oxygen carriers, online ash removal, and not affecting the operation and performance of the chemical looping combustion device.

[0007] The second object of the present invention is to provide an online ash removal method for a large-scale chemical looping combustion device.

[0008] To achieve the above object, an online ash removal system for a large-scale chemical looping combustion device according to an embodiment of the first aspect of the present invention includes: a first collector, a second collector, a first discharger, a second discharger, a screw feeder, a dryer, a magnetic separator, an oxygen carrier recovery bin, an ash bin, a blower, a heat exchanger, and an induced draft fan; wherein,

[0009] The bottom of the first collector is connected to the inlet of the first discharger, and the bottom of the second collector is connected to the inlet of the second discharger; the inlet of the screw feeder faces the outlets of the first discharger and the second discharger respectively, the outlet of the screw feeder faces the feed inlet of the dryer, the discharge outlet of the dryer faces the feed inlet of the magnetic separator, the bottom of the magnetic separator is provided with a magnetic material outlet and a non-magnetic material outlet, the magnetic material outlet faces the oxygen carrier recovery bin, and the non-magnetic material outlet faces the ash bin; the air inlet of the blower is communicated with air, and the air 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 hot air inlet of the dryer; the exhaust outlet of the dryer is connected to the air inlet of the induced draft fan; the exhaust outlet of the induced draft fan is communicated with the tail flue of the air reactor, and the communication position is upstream of the first collector.

[0010] In addition, the online ash removal system for a large-scale chemical looping combustion device according to the above embodiment of the present invention may further have the following additional technical features:

[0011] According to an embodiment of the present invention, both the first collector and the second collector are bag filters. The 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 discharger; 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 discharger; a first level sensor and a second level sensor are arranged in the ash hopper of the first collector, and the position of the first level sensor is higher than that of the second level sensor; a third level sensor and a fourth level sensor are arranged in the ash hopper of the second collector, and the position of the third level sensor is higher than that of the fourth level sensor.

[0012] According to an embodiment of the present invention, both the first discharger and the second discharger are pressure-resistant two-stage series rotary air locks, and the air leakage rate of the first discharger and the second discharger < 0.5%; wherein,

[0013] When the storage height of the material in the ash hopper of the first collector is higher than the first level sensor, start the first discharger to unload the material; when the storage height of the material in the ash hopper of the first collector is lower than the second level sensor, close the first discharger and stop unloading the material;

[0014] When the storage height of the material in the ash hopper of the second collector is higher than the third level sensor, start the second discharger to unload the material; when the storage height of the material in the ash hopper of the second collector is lower than the fourth level sensor, close the second discharger and stop unloading the material.

[0015] According to an embodiment of the present invention, the filter bag materials of the first collector and the second collector are any one of fiberglass, PPS fiber, and PTFE, the filtration accuracy is 0.5 microns and above, and the working temperature range is 100 to 250 °C.

[0016] 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; or, arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector.

[0017] According to an embodiment of the present invention, the magnetic separator is a multi-layer conveyor belt permanent magnet roll type high-intensity high-gradient magnetic separator; the magnets in the magnetic separator are neodymium iron boron permanent magnets, the number of magnetic rolls is 10, the magnetic field strength is 15000 T, and the recovery efficiency of weakly magnetic particles > 98%.

[0018] According to an embodiment of the present invention, the magnetic separator is used to recover oxygen carriers, and the oxygen carrier types are iron, cobalt, nickel, and manganese-based oxygen carriers with ferromagnetic or weak magnetic properties, or perovskite-type oxide oxygen carriers with magnetic properties.

[0019] According to an embodiment of the present invention, the blower is equipped with a frequency converter regulator and a throttle for adjusting the air pressure and flow rate; the flue gas inlet temperature on the flue gas side of the heat exchanger is 260 to 400 °C, the flue gas outlet temperature on the flue gas side is 110 to 200 °C, and the air outlet temperature on the air side is 200 to 350 °C. The waste heat of the flue gas from the large-scale chemical looping combustion device is used to heat the air to obtain the drying hot air required by the dryer; a plurality of temperature measuring points are installed on both the air side and the flue gas side of the heat exchanger to monitor the temperatures of the air and the flue gas.

[0020] According to an embodiment of the present invention, the induced draft fan is equipped with a frequency converter regulator and a throttle for adjusting the air pressure and flow rate; the dryer is a Venturi dryer, and the Venturi dryer includes a primary hot air pipe, a secondary hot air pipe, an air volume regulator, a Venturi tube, and a gas-solid separator; the hot air inlet pressure of the Venturi dryer is 2000 to 6000 Pa, the hot air temperature is 180 to 320 °C, the gas velocity at the outlet of the flared section of the Venturi tube is 4 - 10 m / s, and the material temperature at the discharge port of the dryer is 120 to 150 °C; a plurality of temperature measuring points and pressure measuring points are installed in the dryer to monitor the temperature and pressure of the drying hot air.

[0021] To achieve the above object, a second aspect embodiment of the present invention proposes an online ash discharge method for a large-scale chemical looping combustion device based on the system of the above embodiment. The method includes:

[0022] S1, using the first collector to capture the fine particles in the flue gas at the tail of the air reactor and temporarily store them in the ash hopper of the first collector, and using the second collector to capture the fine particles in the flue gas at the tail of the fuel reactor and temporarily store them in the ash hopper of the second collector, where the fine particles are dust particles with a particle size greater than or equal to 0.5 microns;

[0023] S2, opening the first unloader and the second unloader, and discharging the fine particles temporarily stored in the ash hoppers of the first collector and the second collector through the first unloader and the second unloader respectively, and the fine particles are sent to the screw feeder;

[0024] S3, starting the screw feeder to convey the fine particles to the feed inlet of the dryer;

[0025] S4. Start the blower to send fresh air into the heat exchanger. The heat exchanger heats the normal-temperature air and feeds the heated drying air into the hot air inlet of the dryer under the air pressure of the blower.

[0026] S5. Start the induced draft fan to create a negative pressure inside the dryer. The heated drying air is mixed with the fine particles inside the dryer to remove the moisture adsorbed by the fine particles. The dried fine particles pass through the gas-solid separator together with the drying exhaust air. The dried fine particles are separated and discharged through the discharge port of the dryer. The dusty and water-containing drying exhaust air is discharged through the exhaust port of the dryer.

[0027] S6. The drying exhaust air enters the upstream flue of the first collector through the induced draft fan and is discharged after the dust carried by the drying exhaust air is captured by the first collector.

[0028] S7. The dried fine particles contain fuel ash and oxygen carrier particles that leave the large-scale chemical looping combustion device without being effectively separated by the cyclone separator. After passing through the magnetic separator, due to the magnetic difference between the fuel ash and the oxygen carrier particles, the fine particles are separated into magnetic materials and non-magnetic materials. The oxygen carrier particles enter the oxygen carrier recovery bin as magnetic materials to avoid ash discharge loss, and the fuel ash enters the ash bin as non-magnetic materials for temporary storage and is treated as industrial waste residue.

[0029] Generally speaking, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

[0030] The on-line ash discharge system and method for a large-scale chemical looping combustion device provided by the present invention can discharge fuel ash on-line while the chemical looping combustion device is operating, avoiding the adverse effect of the accumulation of fuel ash in the combustion device on the oxygen carrier particles; effectively separating the flue gas of the chemical looping combustion device from the atmospheric environment during unloading, avoiding the leakage of carbon dioxide-rich flue gas and reducing the carbon capture efficiency, and at the same time avoiding the adverse effect of air entering the carbon dioxide-rich flue gas on subsequent carbon sequestration; the drying device utilizes the waste heat of the chemical looping combustion system, is energy-efficient and can effectively treat the wet fine particles unloaded from the flue gas with a high water vapor content, solving the problem that the particulate matter captured in the flue duct agglomerates due to being in a high water vapor content environment and it is difficult to separate the oxygen carrier particles from the fuel ash; recovering the oxygen carrier particles escaping from the flue through magnetic separation technology, avoiding the loss of oxygen carrier due to ash discharge; the dust-containing gas generated by ash discharge is discharged through the tail gas treatment system of the chemical looping combustion device without generating additional pollution; the ash discharge system has a high degree of automation, is energy-saving and environment-friendly, has high separation efficiency and large processing capacity, and is suitable for use in large-scale chemical looping combustion devices.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned by practice of the present invention. Brief Description of the Drawings

[0032] Figure 1 It is a schematic diagram of an on-line ash removal system for a large-scale chemical looping combustion device according to an embodiment of the present invention.

[0033] In the figure, the solid arrows indicate the flow direction of the particulate matter; the dashed arrows indicate the flow direction of the gas.

[0034] Reference Signs:

[0035] 1, First collector; 2, Second collector; 3, First discharger; 4, Second discharger; 5, Screw feeder; 6, Dryer; 7, Magnetic separator; 8, Oxygen carrier recovery bin; 9, Ash bin; 10, Blower; 11, Heat exchanger; 12, Induced draft fan. Detailed Embodiment

[0036] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0037] An on-line ash removal system for a large-scale chemical looping combustion device and an on-line ash removal method for a large-scale chemical looping combustion device proposed according to an embodiment of the present invention will be described below with reference to the drawings.

[0038] As Figure 1As shown in the figure, the on-line ash removal system for a large-scale chemical looping combustion device according to an embodiment of the present invention may include: a first collector 1, a second collector 2, a first discharger 3, a second discharger 4, a screw feeder 5, a dryer 6, a magnetic separator 7, an oxygen carrier recovery bin 8, an ash bin 9, a blower 10, a heat exchanger 11, and an induced draft fan 12; wherein, the bottom of the first collector 1 is connected to the inlet of the first discharger 3, and the bottom of the second collector 2 is connected to the inlet of the second discharger 4; the inlet of the screw feeder 5 faces the outlets of the first discharger 3 and the second discharger 4 respectively, the outlet of the screw feeder 5 faces the feed inlet of the dryer 6, the discharge outlet of the dryer 6 faces the feed inlet of the magnetic separator 7, the bottom of the magnetic separator 7 is provided with a magnetic material outlet and a non-magnetic material outlet, the magnetic material outlet faces the oxygen carrier recovery bin 8, and the non-magnetic material outlet faces the ash bin 9; the air inlet of the blower 10 is communicated with air, and the air outlet of the blower 10 is connected to the air side inlet of the heat exchanger 11; the air side outlet of the heat exchanger 11 is connected to the hot air inlet of the dryer 6; the exhaust outlet of the dryer 6 is connected to the air inlet of the induced draft fan 12; the exhaust outlet of the induced draft fan 12 is communicated with the tail flue of the air reactor, and the communication position is upstream of the first collector 1.

[0039] Specifically, as Figure 1 shown in the figure, after the on-line ash removal system starts to work, first, the first collector 1 is used to capture the fine particles in the tail gas of the air reactor and temporarily store them in the ash hopper of the first collector 1, and the second collector 2 is used to capture the fine particles in the tail gas of the fuel reactor and temporarily store them in the ash hopper of the second collector 2. When there is more material stored in the ash hopper, the first discharger 3 and the second discharger 4 are opened, and the fine particles temporarily stored in the ash hoppers of the first collector 1 and the second collector 2 are discharged through the first discharger 3 and the second discharger 4 respectively, and the fine particles are sent to the screw feeder 5.

[0040] It should be understood that when chemical looping combustion is carried out in a circulating fluidized bed reactor, steam is usually used as the fluidizing gas in the air reactor and the fuel reactor. Subsequently, the fluidizing gas is discharged through the flue. The temperature in the flue is relatively high and the steam does not condense. After these particulate matters are collected and discharged, they will be cooled to room temperature, and the condensation of steam causes the particulate matters to adhere, which is not conducive to the separation of fuel ash and oxygen carrier particles. Therefore, drying is required before magnetic separation. Specifically, start the screw feeder 5 to convey the fine particulate matters to the feed inlet of the dryer 6, and then start the blower 10 to send fresh air into the heat exchanger 11. The heat exchanger 11 heats the room temperature air and introduces the heated dry air into the hot air inlet of the dryer 6 under the air pressure of the blower 10. At the same time, start the induced draft fan 12 to create a negative pressure in the dryer 6. The heated dry air is mixed with the fine particulate matters in the dryer 6 to remove the moisture adsorbed by the fine particulate matters. The dried fine particulate matters are separated together with the dry exhaust air through the gas-solid separator. The dried fine particulate matters are separated and discharged through the discharge port of the dryer 6. The dust-containing and water-containing dry exhaust air is discharged through the exhaust port of the dryer 6. The dry exhaust air discharged from the dryer 6 enters the upstream flue of the first collector 1 through the induced draft fan 12 and is discharged after the dust carried in the dry exhaust air is captured by the first collector 1. The dried fine particulate matters contain fuel ash and oxygen carrier particles that have not been effectively separated by the cyclone separator and leave the large-scale chemical looping combustion device. After passing through the magnetic separator 7, due to the magnetic difference between the fuel ash and the oxygen carrier particles, the fine particulate matters are separated into magnetic materials and non-magnetic materials. The oxygen carrier particles enter the oxygen carrier recovery bin 8 as magnetic materials to avoid ash discharge loss, and the fuel ash enters the ash bin 9 as non-magnetic materials for temporary storage and is treated as industrial waste residue.

[0041] 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 discharger 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 discharger 4; a first level sensor and a second level sensor are arranged in the ash hopper of the first collector 1, and the position of the first level sensor is higher than the position of the second level sensor; a third level sensor and a fourth level sensor are arranged in the ash hopper of the second collector 2, and the position of the third level sensor is higher than the position of the fourth level sensor.

[0042] Further, according to an embodiment of the present invention, both the first discharger 3 and the second discharger 4 are pressure-resistant two-stage series rotary air locks, and the air leakage rate of the first discharger 3 and the second discharger 4 is <0.5%; wherein, when the storage height of the material in the ash hopper of the first collector 1 is higher than the first level sensor, the first discharger 3 is started to unload the material; when the storage height of the material in the ash hopper of the first collector 1 is lower than the second level sensor, the first discharger 3 is closed to stop unloading the material; when the storage height of the material in the ash hopper of the second collector 2 is higher than the third level sensor, the second discharger 4 is started to unload the material; when the storage height of the material in the ash hopper of the second collector 2 is lower than the fourth level sensor, the second discharger 4 is closed to stop unloading the material.

[0043] 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 or more, and the operating temperature range is 100 to 250 °C.

[0044] According to an embodiment of the present invention, the heat exchanger 11 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, arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector 2.

[0045] Specifically, as Figure 1 shown, the heat exchanger 11 is arranged in the tail flue of the air reactor and the installation position is upstream of the first collector 1. The blower 10 sends fresh air into the heat exchanger 11, and the heat exchanger 11 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.

[0046] Similarly, when the heat exchanger 11 is arranged in the tail flue of the fuel reactor and the installation position is upstream of the second collector 2, the blower 10 sends fresh air into the heat exchanger 11, and the heat exchanger 11 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.

[0047] According to an embodiment of the present invention, the magnetic separator 7 is a multi-layer conveyor belt permanent magnet roller type high magnetic field high gradient magnetic separator; the magnet in the magnetic separator 7 is a neodymium iron boron permanent magnet, the number of magnetic rollers is 10, the magnetic field strength is 15000 T, and the recovery efficiency of weakly magnetic particles is >98%.

[0048] According to an embodiment of the present invention, the magnetic separator 7 is used to recover oxygen carriers, and the oxygen carrier types are iron, cobalt, nickel, manganese-based oxygen carriers with ferromagnetism or weak magnetism, or magnetic perovskite-type oxide oxygen carriers.

[0049] According to an embodiment of the present invention, a blower 10 is installed with a variable frequency regulator and a throttle for regulating the wind pressure and flow rate; the flue gas inlet temperature on the flue gas side of the heat exchanger 11 is 260 to 400 °C, the flue gas outlet temperature on the flue gas side is 110 to 200 °C, and the air outlet temperature on the air side is 200 to 350 °C. The waste heat of the flue gas of the large-scale chemical looping combustion device is used to heat the air to obtain the drying hot air required by the dryer 6; a plurality of temperature measuring points are installed on both the air side and the flue gas side of the heat exchanger 11 for monitoring the temperatures of the air and the flue gas.

[0050] According to an embodiment of the present invention, an induced draft fan 12 is installed with a variable frequency regulator and a throttle for regulating the wind pressure and flow rate; the dryer 6 is a Venturi dryer, and the Venturi dryer includes a primary hot air pipe, a secondary hot air pipe, an air volume regulator, a Venturi tube, and a gas-solid separator; the hot air inlet pressure of the Venturi dryer is 2000 to 6000 Pa, the hot air temperature is 180 to 320 °C, the gas velocity at the outlet of the flared section of the Venturi tube is 4 - 10 m / s, and the material temperature at the discharge port of the Venturi dryer is 120 to 150 °C; a plurality of temperature measuring points and pressure measuring points are installed in the dryer 6 for monitoring the temperature and pressure of the drying hot air.

[0051] In another embodiment of the present invention, the dryer 6 is a rotary dryer.

[0052] Corresponding to the above embodiments, the present invention also proposes an on-line ash discharge method for a large-scale chemical looping combustion device.

[0053] The on-line ash discharge method for a large-scale chemical looping combustion device based on the system of the foregoing embodiments of the present invention may include the following steps:

[0054] S1. Use the first collector 1 to capture the fine particles in the flue gas at the tail of the air reactor and temporarily store them in the ash hopper of the first collector 1, and use the second collector 2 to capture the fine particles in the flue gas at the tail of the fuel reactor and temporarily store them in the ash hopper of the second collector 2, wherein the fine particles are dust particles with a particle size greater than or equal to 0.5 microns;

[0055] S2. Open the first discharger 3 and the second discharger 4, and discharge the fine particles temporarily stored in the ash hoppers of the first collector 1 and the second collector 2 through the first discharger 3 and the second discharger 4 respectively. The fine particles are sent to the screw feeder 5;

[0056] S3. Start the screw feeder 5 to convey the fine particles to the feed port of the dryer 6;

[0057] S4. Start the blower 10 to send fresh air into the heat exchanger 11. The heat exchanger 11 heats the normal temperature air and passes the heated drying air into the hot air inlet of the dryer 6 under the wind pressure of the blower 10;

[0058] S5. Start the induced draft fan 12 to create a negative pressure in the dryer 6. The heated drying air is mixed with the fine particles in the dryer 6 to remove the moisture adsorbed by the fine particles. The dried fine particles pass through the gas-solid separator together with the drying exhaust air. The dried fine particles are separated and discharged through the discharge port of the dryer 6. The dust-containing and water-containing drying exhaust air is discharged through the exhaust port of the dryer 6.

[0059] S6. The drying exhaust air enters the upstream flue of the first collector 1 through the induced draft fan 12 and is discharged after the fine particles carried in the drying exhaust air are captured by the first collector 1.

[0060] S7. The dried fine particles contain fuel ash and oxygen carrier particles that leave the large-scale chemical looping combustion device without being effectively separated by the cyclone separator. After passing through the magnetic separator 7, due to the magnetic difference between the fuel ash and the oxygen carrier particles, the fine particles are separated into magnetic materials and non-magnetic materials. The oxygen carrier particles enter the oxygen carrier recovery bin 8 as magnetic materials to avoid ash discharge loss, and the fuel ash enters the ash bin 9 as non-magnetic materials for temporary storage and is treated as industrial waste residue.

[0061] The following combines three specific embodiments to detail the specific process of the online ash discharge method for the large-scale chemical looping combustion device according to the embodiments of the present invention.

[0062] Embodiment 1:

[0063] Using hematite oxygen carrier, the main components are: 83.7% Fe2O3, 6.3% SiO2, 2.4% Al2O3, 7.6% impurities, with ferromagnetic properties; the solid fuel used is Pingdingshan anthracite; the method is as follows:

[0064] S1. Use the first collector 1 to capture the fine particles in the flue gas at the tail of the air reactor, and use the second collector 2 to capture the fine particles in the flue gas at the tail of the fuel reactor; the filter bag materials of the first collector 1 and the second collector 2 are glass fiber, the filtration accuracy is 2.0 microns, and the working temperature is 240 °C; the fine particles consist of anthracite ash and hematite oxygen carrier particles escaping from the flue, with a particle size range of 2.0 microns and above, and more than 85% of the fine particles have a particle size distribution between 33 and 90 microns; the fine particles are captured by the filter bag and fall under the action of gravity, and are temporarily stored in the ash hopper below the filter bag.

[0065] S2. When the storage material height in the ash hopper of the first collector 1 is higher than the first level sensor, start the first unloader 3 to unload the material; when the storage material height in the ash hopper of the first collector 1 is lower than the second level sensor, close the first unloader 3 and stop unloading the material; when the storage material height in the ash hopper of the second collector 2 is higher than the third level sensor, start the second unloader 4 to unload the material; when the storage material height in the ash hopper of the second collector 2 is lower than the fourth level sensor, close the second unloader 4 and stop unloading the material; the fine particulate matter is sent to the screw feeder 5; both the first unloader 3 and the second unloader 4 are pressure-resistant two-stage series rotary air locks, and the air leakage rate is 0.47%.

[0066] S3. Start the screw feeder 5 to convey the fine particulate matter to the feed inlet of the dryer 6; adjust the feeding rate through the frequency conversion controller to match the unloading rate.

[0067] S4. Start the blower 10. The air is filtered by the air filter and then sucked into the air inlet of the blower 10, and then pumped into the heat exchanger 11. The type of the heat exchanger 11 is a tube bundle heat exchanger 11. The flue gas inlet temperature on the flue gas side is 380 °C, the flue gas outlet temperature on the flue gas side is 180 °C, and the air outlet temperature on the air side is 320 °C. Utilize the waste heat of the flue gas of the chemical looping combustion device to heat the air to obtain the drying hot air required by the dryer 6. Adjust the air pressure and flow rate entering the heat exchanger 11 through the frequency conversion regulator and throttle installed on the blower 10. Monitor the air and flue gas temperatures through multiple temperature measuring points installed on the air side and flue gas side of the heat exchanger 11. The heat exchanger 11 heats the normal temperature air to a high temperature and introduces the high-temperature drying air into the hot air inlet of the dryer 6 under the air pressure of the blower 10.

[0068] S5. Start the induced draft fan 12 and adjust through the frequency conversion regulator and throttle installed on the induced draft fan 12 to establish a negative pressure in the dryer 6. The hot air inlet pressure of the dryer 6 is 4000 Pa, and the hot air temperature is 280 °C. The drying hot air is mixed with the fine particulate matter in the dryer 6 to remove the moisture adsorbed by the fine particulate matter. The gas velocity at the outlet of the flared section of the venturi tube is 7 m / s. The dried fine particulate matter is separated together with the drying exhaust air through the gas-solid separator, and the dried fine particulate matter is separated and discharged through the discharge port of the dryer 6. The material temperature at the discharge port is 140 °C. The low-temperature, dust-containing, and water-containing drying exhaust air is discharged through the exhaust port of the dryer 6.

[0069] S6. The drying exhaust air is discharged into the tail flue of the air reactor through the induced draft fan 12 and enters the upstream flue of the first collector 1. Utilize the first collector 1 to capture the dust carried in the drying exhaust air, and then discharge it together with the flue gas of the air reactor.

[0070] In S7, the fine particulate matter after drying contains fuel ash and oxygen carrier particles that have left the large-scale chemical looping combustion device without being effectively separated by the cyclone separator. After passing through the magnetic separator 7, due to the magnetic difference between the fuel ash and the oxygen carrier particles, the fine particulate matter is separated into magnetic material and non-magnetic material. Among them, the mass ratio of anthracite coal ash after magnetic separation is 52.7%, and the mass ratio of hematite oxygen carrier particles is 47.3%; a multi-layer conveyor belt permanent magnet roller type high-gradient magnetic separator is used, with neodymium iron boron permanent magnets, 10 magnetic rollers, and a magnetic field strength of 15000 T; the oxygen carrier particles enter the oxygen carrier recovery bin 8 as magnetic material, and the fuel ash enters the ash bin 9 as non-magnetic material for temporary storage and is treated as industrial waste residue; the recovery efficiency of hematite oxygen carrier particles is >99%.

[0071] Example 2:

[0072] The structure of the on-line ash discharge system for the large-scale chemical looping combustion device is the same as that in Example 1;

[0073] Ilmenite oxygen carrier is used, with the main components being: 65.5% FeTiO3, 14.8% Fe2O3, 14.1% TiO2, and 5.6% impurities, having weak magnetism; the solid fuel used is Shenhua bituminous coal; the method is the same as that in Example 1, and the differences are as follows:

[0074] In S1, the filter bag materials of the first collector 1 and the second collector 2 are PPS fibers, with a filtration accuracy of 1.0 μm and an operating temperature of 200 °C; the fine particulate matter consists of bituminous coal ash and ilmenite oxygen carrier particles that escape from the flue, with a particle size range of 1.0 μm and above, and more than 85% of the fine particulate matter has a particle size distribution between 23 and 96 μm;

[0075] In S2, the air leakage rate of the first discharger 3 and the second discharger 4 is 0.45%;

[0076] In S4, the flue gas inlet temperature on the flue gas side of the heat exchanger 11 is 340 °C, the flue gas outlet temperature on the flue gas side is 150 °C, and the air outlet temperature on the air side is 280 °C;

[0077] In S5, the hot air inlet pressure of the dryer 6 is 5000 Pa, the hot air temperature is 240 °C; the gas velocity at the outlet of the flare section of the venturi tube is 8 m / s; the material temperature at the discharge port of the dryer 6 is 130 °C;

[0078] In S7, after magnetic separation by the magnetic separator 7, the mass ratio of bituminous coal ash is 71.6%, and the mass ratio of ilmenite oxygen carrier particles is 28.4%. The recovery efficiency of the magnetic separator 7 for ilmenite oxygen carrier particles is >98.5%.

[0079] Example 3:

[0080] The on-line ash discharge system for the large-scale chemical looping combustion device has the same structure as that in Embodiment 1;

[0081] A perovskite-type oxide oxygen carrier is adopted, and the main components are: CaMn 0.625 Ti 0.125 Fe 0.125 Mg 0.125 O 3-δ , which has weak magnetism; the solid fuel adopted is Huolinhe lignite; the method is the same as that in Embodiment 1, and the differences are:

[0082] S1. The filter bag materials of the first collector 1 and the second collector 2 are PTFE fibers, the filtration accuracy is 0.5 microns, and the working temperature is 180 °C; the fine particulate matters are composed of lignite ash and CaMn 0.625 Ti 0.125 Fe 0.125 Mg 0.125 O 3-δ oxygen carrier particles, the particle size range is 0.5 microns and above, and more than 85% of the fine particulate matters have a particle size distribution between 38 and 106 microns;

[0083] S2. The air leakage rates of the first discharger 3 and the second discharger 4 are 0.41%;

[0084] S4. The flue gas inlet temperature on the flue gas side of the heat exchanger 11 is 310 °C, the flue gas outlet temperature on the flue gas side is 130 °C, and the air outlet temperature on the air side is 260 °C;

[0085] S5. The hot air inlet pressure of the dryer 6 is 6000 Pa, the hot air temperature is 220 °C; the gas velocity at the outlet of the flare section of the Venturi tube is 9 m / s; the material temperature at the discharge port of the dryer 6 is 120 °C;

[0086] S7. After magnetic separation by the magnetic separator 7, the mass ratio of lignite ash is 78.8%, and the mass ratio of CaMn 0.625 Ti 0.125 Fe 0.125 Mg 0.12 5O 3-δ oxygen carrier particles is 21.2%, and the recovery efficiency of the magnetic separator 7 for CaMn 0.625 Ti 0.125 Fe 0.125 Mg 0.125 O 3-δ oxygen carrier particles is > 98.0%.

[0087] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", 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 may be combined in a suitable manner in any one or more embodiments or examples.

[0088] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed 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 such 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.

[0089] In the present invention, unless otherwise clearly specified and limited, the terms such as "mounted", "connected", "connected to", "fixed" etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, 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 circumstances.

[0090] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not 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 on-line ash discharging system for a large-scale chemical-looping combustion device, characterized in that, The system includes: a first collector (1), a second collector (2), a first discharger (3), a second discharger (4), a screw feeder (5), a dryer (6), a magnetic separator (7), an oxygen carrier recovery bin (8), an ash bin (9), a blower (10), a heat exchanger (11), and an induced draft fan (12); wherein, The bottom of the first collector (1) is connected to the inlet of the first discharger (3), and the bottom of the second collector (2) is connected to the inlet of the second discharger (4); the inlet of the screw feeder (5) faces the outlets of the first discharger (3) and the second discharger (4) respectively, the outlet of the screw feeder (5) faces the feed inlet of the dryer (6), the discharge outlet of the dryer (6) faces the feed inlet of the magnetic separator (7), the bottom of the magnetic separator (7) is provided with a magnetic material outlet and a non-magnetic material outlet, the magnetic material outlet faces the oxygen carrier recovery bin (8), and the non-magnetic material outlet faces the ash bin (9); the air inlet of the blower (10) is in communication with air, and the air outlet of the blower (10) is connected to the air side inlet of the heat exchanger (11); the air side outlet of the heat exchanger (11) is connected to the hot air inlet of the dryer (6); the exhaust outlet of the dryer (6) is connected to the air inlet of the induced draft fan (12); the exhaust outlet of the induced draft fan (12) is in communication with the tail flue of the air reactor, and the communication position is upstream of the first collector (1).

2. The online ash discharging system for a large-scale 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 discharger (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 discharger (4); a first level sensor and a second level sensor are arranged in the ash hopper of the first collector (1), and the position of the first level sensor is higher than that of the second level sensor; a third level sensor and a fourth level sensor are arranged in the ash hopper of the second collector (2), and the position of the third level sensor is higher than that of the fourth level sensor.

3. The on-line ash discharging system for a large-scale chemical looping combustion device according to claim 2, characterized in that, Both the first discharger (3) and the second discharger (4) are pressure-resistant two-stage series rotary air locks, and the air leakage rate of the first discharger (3) and the second discharger (4) < 0.5%; wherein, When the storage height of the material in the ash hopper of the first collector (1) is higher than the first level sensor, start the first discharger (3) to unload the material; when the storage height of the material in the ash hopper of the first collector (1) is lower than the second level sensor, close the first discharger (3) to stop unloading the material; When the storage height of the material in the ash hopper of the second collector (2) is higher than the third level sensor, start the second discharger (4) to unload the material; when the storage height of the material in the ash hopper of the second collector (2) is lower than the fourth level sensor, close the second discharger (4) to stop unloading the material.

4. The online ash discharging system for a large-scale chemical looping combustion device according to claim 2, characterized in that, The filter bags of the first collector (1) and the second collector (2) are made of any one of fiberglass, PPS fiber, and PTFE, with a filtration accuracy of 0.5 microns or more and a working temperature range of 100 to 250 °C.

5. The on-line ash discharging system for a large-scale chemical-looping combustion device according to claim 1, wherein The heat exchanger (11) is a tubular heat exchanger or a plate heat exchanger, arranged in the tail flue of the air reactor and installed upstream of the first collector (1); or, arranged in the tail flue of the fuel reactor and installed upstream of the second collector (2).

6. The on-line ash discharge system for a large-scale chemical-looping combustion device according to claim 1, characterized in that, The magnetic separator (7) is a multi-layer conveyor belt permanent magnet roller type high-gradient magnetic separator with strong magnetic field; the magnets in the magnetic separator (7) are neodymium iron boron permanent magnets, the number of magnetic rollers is 10, the magnetic field strength is 15000 T, and the recovery efficiency of weakly magnetic particles is > 98%.

7. The online ash discharging system for a large-scale chemical looping combustion device according to claim 1, wherein The magnetic separator (7) is used to recover oxygen carriers, and the types of oxygen carriers are iron, cobalt, nickel, manganese-based oxygen carriers with ferromagnetic or weakly magnetic properties, or magnetic perovskite-type oxide oxygen carriers.

8. The on-line ash discharging system for a large-scale chemical looping combustion device according to claim 1, wherein The blower (10) is equipped with a frequency converter regulator and a throttle valve to adjust the wind pressure and flow rate; the flue gas inlet temperature on the flue gas side of the heat exchanger (11) is 260 to 400 °C, the flue gas outlet temperature on the flue gas side is 110 to 200 °C, and the air outlet temperature on the air side is 200 to 350 °C. The waste heat of the flue gas of the large-scale chemical looping combustion device is used to heat the air to obtain the drying hot air required by the dryer (6); multiple temperature measuring points are installed on both the air side and the flue gas side of the heat exchanger (11) to monitor the temperatures of the air and the flue gas.

9. The online ash removal system for a large-scale chemical looping combustion device according to claim 1, wherein, The induced draft fan (12) is equipped with a frequency converter regulator and a throttle valve to adjust the wind pressure and flow rate; the dryer (6) is a Venturi dryer, and the Venturi dryer includes a primary hot air pipe, a secondary hot air pipe, an air volume regulator, a Venturi tube, and a gas-solid separator; the hot air inlet pressure of the Venturi dryer is 2000 to 6000 Pa, the hot air temperature is 180 to 320 °C, the gas velocity at the outlet of the flared section of the Venturi tube is 4 - 10 m / s, and the material temperature at the discharge port of the dryer (6) is 120 to 150 °C; multiple temperature measuring points and pressure measuring points are installed in the dryer (6) to monitor the temperature and pressure of the drying hot air.

10. An online ash discharging method for a large-scale chemical-looping combustion device based on the system according to any one of claims 1 to 9, characterized in that, The method includes: S1, using the first collector (1) to capture the fine particulate matter in the tail flue gas of the air reactor and temporarily store it in the ash hopper of the first collector (1), and using the second collector (2) to capture the fine particulate matter in the tail flue gas of the fuel reactor and temporarily store it in the ash hopper of the second collector (2), where the fine particulate matter is dust particles with a particle size greater than or equal to 0.5 microns; S2. Turn on the first unloader (3) and the second unloader (4), and unload the fine particulate matters temporarily stored in the hoppers of the first collector (1) and the second collector (2) through the first unloader (3) and the second unloader (4) respectively. The fine particulate matters are sent to the screw feeder (5). S3. Start the screw feeder (5) to convey the fine particulate matters to the feed inlet of the dryer (6). S4. Start the blower (10) to send fresh air into the heat exchanger (11). The heat exchanger (11) heats the normal temperature air and passes the heated dry air into the hot air inlet of the dryer (6) under the air pressure of the blower (10). S5. Start the induced draft fan (12) to create a negative pressure in the dryer (6). The heated dry air and the fine particulate matters are mixed in the dryer (6) to remove the moisture adsorbed by the fine particulate matters. The dried fine particulate matters are separated from the dry exhaust air together through the gas-solid separator. The dried fine particulate matters are separated and discharged through the discharge port of the dryer (6). The dusty and water-containing dry exhaust air is discharged through the exhaust port of the dryer (6). S6. The dry exhaust air enters the upstream flue of the first collector (1) through the induced draft fan (12) and is discharged after the first collector (1) captures the dust carried in the dry exhaust air. S7. The dried fine particulate matters contain fuel ash and oxygen carrier particles that leave the large-scale chemical looping combustion device without being effectively separated by the cyclone separator. After passing through the magnetic separator (7), due to the magnetic difference between the fuel ash and the oxygen carrier particles, the fine particulate matters are separated into magnetic materials and non-magnetic materials. The oxygen carrier particles enter the oxygen carrier recovery bin (8) as magnetic materials to avoid ash discharge loss. The fuel ash enters the ash bin (9) as non-magnetic materials for temporary storage and is treated as industrial waste residue.

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