A low-carbon emission combustion system for generator sets

Abstract

This invention relates to the field of coal-fired power generation technology, specifically a low-carbon emission combustion system for generator sets. Addressing the problem of substandard low-carbon emissions from small coal-fired power plants, this invention provides a low-carbon emission combustion system for generator sets to achieve low carbon emissions. The invention comprises three units: pulverized coal combustion, flue gas purification, and biomass combustion. The pulverized coal combustion unit and the biomass combustion unit are each connected to a flue gas purification unit via their respective flue gas ducts. The flue gas purification unit is connected to a flue gas recovery tank via a main flue gas pipe. The flue gas recovery tank is connected to a carbon dioxide fixation device via a pipe, and the carbon dioxide fixation device is connected to a chimney via a pipe. This invention can retrofit existing small coal-fired units, reducing pulverized coal consumption and emissions by combining pulverized coal and biomass combustion. It also allows for the study of the impact of various combustion modes, such as single or combined combustion of pulverized coal and biomass, air-oxygen mixing, and flue gas recycling, on emissions, and the acquisition of research data.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to a low-carbon emission combustion system for generator sets. Background Technology

[0002] Carbon emission reduction in coal-fired power plants is a current development trend. Existing research on coal-fired power plants largely focuses on combustion adjustments and optimizations for large-capacity units, with little improvement to the combustion systems themselves. Small units still primarily use coal-fired boilers. my country currently retains many small units, which, if not upgraded to meet low-carbon emission standards, will have to be dismantled. Current research on low-carbon emission, especially zero-emission combustion, for small units is severely lacking, and there is a shortage of combustion systems capable of enabling low-carbon emissions in small units. Summary of the Invention

[0003] This invention addresses the technical problem that existing small coal-fired power plants cannot achieve low-carbon emissions by simply burning coal. It provides a low-carbon emission combustion system for generator sets. This system can be implemented by modifying existing small coal-fired units to simultaneously burn biomass and pulverized coal, achieving low-carbon emission combustion and further realizing zero-emission combustion. Further combustion can utilize various combustion methods for pulverized coal and / or biomass materials. During combustion, the different effects of air-oxygen mixing and flue gas recirculation on combustion emissions can be studied, obtaining research data on low-carbon emissions from small unit combustion and laying the foundation for further in-depth research on low-carbon emissions from small unit combustion.

[0004] The technical solution adopted by this invention to solve the technical problem is as follows: A low-carbon emission combustion system for a generator set, comprising a pulverized coal combustion unit and a flue gas purification unit. The pulverized coal combustion unit includes a fluidized bed boiler, and the flue gas purification unit includes a cyclone separator, a denitrification device, a desulfurization device, and a bag filter. The fluidized bed boiler is connected to the flue gas purification unit through a second flue gas pipeline, and the flue gas purification unit is connected to a chimney through a pipeline. The fluidized bed boiler is connected to an air tank for air intake through a pipeline, and the feed inlet of the fluidized bed boiler is connected to a pulverized coal supply source. The combustion system is characterized by further including a biomass combustion unit, which includes a biomass boiler, a biomass fuel storage bin, and a biomass gas treatment device. The biomass fuel storage bin is connected to the biomass gas treatment device through a biomass gas transmission pipeline, and the biomass gas treatment device is connected to the biomass boiler through a gas pipeline. The biomass boiler is connected to an air tank for air intake through a pipeline, and the exhaust gas from the biomass boiler is connected to the flue gas purification unit through a first flue gas pipeline. The flue gas purification unit is connected to a flue gas recovery tank through a flue gas main, and the flue gas recovery tank is connected to a carbon dioxide fixation device through a pipeline. The carbon dioxide fixation device is connected to the chimney through a pipeline. This invention adds a biomass combustion unit to the existing pulverized coal combustion system. By combining pulverized coal combustion and biomass combustion, the amount of pulverized coal used is reduced, and the emissions from pulverized coal combustion are also reduced. At the same time, the flue gas from the two boilers can share a single flue gas purification unit for treatment, simplifying the system composition. After removing carbon dioxide, the gas is discharged into the atmosphere, further realizing low-carbon emission combustion in small units. The biomass combustion unit operates by burning biomass gas as an energy source. Biomass fuel storage bins store biomass fuels such as straw, which are dried, pressurized, and gasified to produce biomass gas. This biomass gas is then sent through a biomass gas pipeline to a biomass gas treatment device for purification and impurity removal. The purified biomass gas is then sent through a gas pipeline to the biomass boiler for combustion, working in conjunction with air supplied through the pipeline. The flue gas from both the biomass boiler and the fluidized bed boiler is sent to a flue gas purification system through first and second flue gas pipelines, respectively, for denitrification, desulfurization, and impurity removal. The purified flue gas is stored in a flue gas recovery tank and then sent out for further carbon dioxide removal via a carbon dioxide fixation device before finally being discharged into the atmosphere through a chimney. The flue gas recovery tank can temporarily store the purified flue gas and discharge it to the carbon dioxide fixation device at an appropriate rate to ensure its normal and efficient operation and to remove carbon dioxide from the flue gas. The biomass boiler and the fluidized bed boiler share the same air tank, which supplies gas to assist combustion.

[0005] As a further improvement and supplement to the above technical solution, the present invention adopts the following technical measures: the cyclone separator is connected to the denitrification device through a denitrification pipeline, the denitrification device is connected to the bag filter through a pipeline, the bag filter is connected to the desulfurization device through a bag filter pipeline, and the desulfurization device is connected to the flue gas main through a desulfurization outlet pipeline; the first flue gas pipeline and the second flue gas pipeline merge and are connected to the inlet of the cyclone separator, and the cyclone separator is connected to the recovery box through an impurity pipeline; the generator set low-carbon emission combustion system also includes a heat exchanger, the heat exchanger is connected to the pipeline connecting the denitrification device and the bag filter through its hot medium inlet and outlet, and the heat exchanger is connected to the pipeline connecting the air tank inlet through its cold medium inlet and outlet. The flue gas inside the flue gas purification unit is processed sequentially through a cyclone separator, a denitrification device, a bag filter, and a desulfurization device. During the process, the flue gas generated by the biomass boiler and the fluidized bed boiler is first separated into particulate impurities and gases in the cyclone separator. The gas is then sent to the denitrification device for denitrification treatment, while the particulate impurities are sent to the recovery tank through the impurity pipe. The denitrified flue gas exchanges heat with the air sent from the air tank through a heat exchanger. After the air is preheated, it is sent to the biomass boiler and the fluidized bed boiler for combustion support. After heat exchange, the flue gas is sent to the flue gas recovery tank after dust removal and desulfurization treatment by the bag filter.

[0006] A gas mixing tank is connected to the pipe leading to the cold medium outlet of the heat exchanger. The pipe between the gas mixing tank and the heat exchanger is an air outlet pipe equipped with a first flow valve. The gas mixing tank is connected to an oxygen tank via a pipe with an oxygen flow valve. The pipe on the output side of the gas mixing tank is a gas mixing pipe equipped with a second flow valve. The gas mixing pipe branches at its distal end to form an air pipe for the biomass boiler and an air pipe for the fluidized bed boiler, which are respectively connected to the biomass boiler and the fluidized bed boiler. During operation, air and oxygen are first uniformly mixed in the gas mixing tank, and then sent to the biomass boiler and the fluidized bed boiler through the pipes to enhance combustion. This method is more efficient than allowing air and oxygen to be separately introduced into the boiler and mixed inside for combustion.

[0007] A heater is installed on the pipeline between the oxygen flow valve and the oxygen tank. The oxygen supplied from the oxygen tank is heated by the heater. After being preheated, the oxygen is sent to the gas mixing tank to be fully mixed with the preheated air. This avoids the problem of the oxygen significantly reducing the mixture temperature when mixing with the air due to low temperature, which would affect the combustion effect of the biomass boiler and fluidized bed boiler.

[0008] A first booster fan is installed on the pipeline on the output side of the second flow valve. The first booster fan can effectively pressurize the incoming air-oxygen mixture to maintain the gas supply in the pipeline. The pressurized air-oxygen mixture is divided into two paths and sent to the fluidized bed boiler burning pulverized coal and the biomass boiler burning biomass combustible gas, respectively, to improve the combustion efficiency of the two boilers.

[0009] The pipeline connecting the cyclone separator and the denitrification device is a denitrification pipeline. The denitrification pipeline is branched to form a dust collector inlet pipe and connects to a dust collector. The dust collector exhaust port side is connected to a pipeline and branches into a branch outlet pipe and a dust collector outlet pipe. The dust collector outlet pipe connects to a flue gas recovery tank. The far end of the branch outlet pipe connects to a flue gas combustion pipe. The flue gas combustion pipe is equipped with a flue gas flow regulating valve. The flue gas combustion pipe branches at the far end to form a branch pipe that connects to a biomass boiler and a fluidized bed boiler. The pipeline between the cyclone separator and the denitrification unit is branched and connected to a dust collector. The pipeline at the dust collector's outlet branches again, becoming a dust collector outlet pipe that returns to the flue gas recovery tank and a branch outlet pipe that connects to two combustion boilers. One of these branch outlet pipes also receives a flue gas combustion-supporting pipeline from a branch pipe at a distant end, sending the flue gas back to the biomass boiler and fluidized bed boiler for continued combustion and recycling, thus improving the combustion efficiency of the biomass boiler and fluidized bed boiler. The recycled flue gas can then be sent through the pipeline to the flue gas recovery tank, treated by a carbon dioxide fixation device, and discharged externally, improving environmental friendliness. The flue gas combustion-supporting pipeline first removes dust from the flue gas, then pressurizes it, and then sends it back to the biomass boiler and / or fluidized bed boiler to burn together with biomass and / or pulverized coal, reducing nitrogen oxide emissions. However, biomass combustion produces pollutants such as carbon monoxide and nitrogen oxides.

[0010] The denitrification pipeline is branched to form a denitrification bypass pipe. The other end of the denitrification bypass pipe merges with the pipeline at the outlet of the denitrification unit and connects to the heat medium inlet of the heat exchanger. The connecting pipeline between the heat exchanger and the bag filter is branched to form a dust collector bypass pipe. The other end of the dust collector bypass pipe merges with the pipeline at the outlet of the bag filter that connects to the desulfurization unit. The connecting pipeline between the bag filter and the desulfurization unit is branched to form a desulfurization bypass pipe. The other end of the desulfurization bypass pipe connects to the main flue gas pipe. These three bypass pipes allow gas to bypass the denitrification unit, bag filter, and desulfurization unit via pipelines, and the bypass pipes can be used in various ways. In the initial stage of combustion, the mixture of coal and biomass gas produces a large amount of impurities. At this time, the three bypass pipes can carry flue gas during the initial combustion of biomass boilers and fluidized bed boilers, allowing the flue gas to bypass the denitrification device, bag filter, and desulfurization device and be sent to the flue gas recovery tank to protect the aforementioned three devices. All three bypass pipes are open. After the boiler is in normal combustion, the three bypass pipes are closed, and the flue gas is sent to the flue gas recovery tank after being treated by the denitrification device, bag filter, and desulfurization device. Before ignition and combustion, this system can also be purged with air. The air supplied by the air tank is sent to the boiler for purging through the pipeline. At this time, the three bypass pipes must be closed. The air coming out of the boiler can purge the denitrification device, bag filter, and desulfurization device before being sent to the flue gas recovery tank. After the denitrification device, bag filter, and desulfurization device have been purged, the three bypass pipes are opened and the inlets of the denitrification device, bag filter, and desulfurization device are closed at the same time. The purging air is then sent to the flue gas recovery tank after purging through the three bypass pipes and bypassing the denitrification device, bag filter, and desulfurization device.

[0011] A second booster fan is installed on the branch outlet pipe. The function of the second booster fan is to pressurize the flue gas sent to the boiler, ensuring a continuous and stable supply of flue gas to the biomass combustion furnace and fluidized bed boiler, maintaining the efficiency of flue gas recycling, and reducing nitrogen oxide emissions when the pressurized flue gas enters the boiler.

[0012] The pulverized coal supply is a pulverized coal silo. The outlet of the pulverized coal silo is connected to a pulverized coal conveyor belt. The far end of the pulverized coal conveyor belt is connected to a first conveyor belt and a second conveyor belt. The far ends of the first and second conveyor belts are respectively connected to a fluidized bed boiler and a biomass boiler to supply pulverized coal. The fluidized bed boiler and the biomass boiler are connected to the same common pulverized coal silo via conveyor belts. The pulverized coal from the silo is relayed to different boilers via the front pulverized coal conveyor belt and the rear first and second conveyor belts.

[0013] This invention combines pulverized coal combustion and biomass combustion to reduce emissions from pulverized coal combustion. Simultaneously, the flue gas from two boilers can share a single flue gas purification unit for treatment, and after carbon dioxide removal, it is released into the atmosphere, achieving low-carbon emission combustion in small-scale units. Furthermore, this invention can investigate the impact of air-oxygen mixing and flue gas on combustion emissions through different combinations of combustion methods. Attached Figure Description

[0014] Figure 1 : A schematic diagram of the system structure described in this invention.

[0015] In the diagram: 1. Biomass gas processing unit; 1-1. Gas pipeline; 2. Biomass gas transmission pipeline; 3. Biomass fuel storage bin; 4. Pulverized coal bin; 5. Pulverized coal conveyor belt; 5-1. First conveyor belt; 5-2. Second conveyor belt; 6. Biomass boiler; 6-1. First flue gas pipeline; 7. Fluidized bed boiler; 7-1. Second flue gas pipeline; 8. Cyclone separator; 8-1. Dust collector inlet pipe; 8-2. Denitrification pipeline; 8-3. Denitrification bypass pipe; 8-4. Impurity pipeline; 8-5. Recovery box; 9. Denitrification device; 10. Dust collector; 10-1. Dust collector outlet pipeline; 11. Heat exchanger; 12. Air tank; 13. Air outlet pipeline; 13-1. First flow valve; 13-2 13-3. Second flow valve; 13-4. Gas mixing pipeline; 13-5. First booster fan; 14. Gas mixing tank; 15. Bag filter; 15-1. Dust collector bypass pipe; 15-2. Bag filter pipeline; 16. Desulfurization unit; 16-1. Desulfurization bypass pipe; 16-2. Desulfurization outlet pipeline; 16-3. Flue gas combustion pipeline; 16-4. Flue gas main pipe; 16-5. Flue gas flow regulating valve; 16-6. Flue gas boiler air pipe; 16-7. Biomass boiler air pipe; 17. Second booster fan; 17-1. Branch outlet pipeline; 18. Flue gas recovery tank; 19. Carbon dioxide fixation device; 20. Chimney; 21. Oxygen tank; 22. Heater; 22-1. Oxygen flow valve. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] like Figure 1As shown, a low-carbon emission combustion system for a generator set includes a pulverized coal combustion unit, a flue gas purification unit, a biomass combustion unit, and a heat exchanger 11. The biomass combustion unit includes a biomass boiler 6, a biomass fuel storage bin 3, and a biomass gas treatment device 1. The biomass fuel storage bin 3 is connected to the biomass gas treatment device 1 via a biomass gas pipeline 2. The biomass gas treatment device 1 is connected to the biomass boiler 6 via a gas pipeline 1-1. The biomass boiler 6 receives air from an air tank 12 via a pipeline. The exhaust gas from the biomass boiler 6 is connected to the flue gas purification unit via a first flue gas pipeline 6-1. The pulverized coal combustion unit includes a fluidized bed boiler 7, which receives air from an air tank 12 via a pipeline. The feed inlet of the fluidized bed boiler 7 is connected to a pulverized coal supply. The fluidized bed boiler 7 is connected to the flue gas purification unit via a second flue gas pipeline 7-1. The flue gas purification unit includes a cyclone separator 8, a denitrification device 9, and a desulfurization device 1. 6 and bag filter 15, the first flue gas pipe 6-1 and the second flue gas pipe 7-1 merge and are connected to the inlet of cyclone separator 8, the cyclone separator 8 is connected to recovery box 8-5 through impurity pipe 8-4, the cyclone separator 8 is connected to denitrification device 9 through denitrification pipe 8-2, the denitrification device 9 is connected to bag filter 15 through pipe, the bag filter 15 is connected to desulfurization device 16 through bag filter pipe 15-2, the desulfurization device 16 is connected to flue gas main pipe 16-4 through desulfurization outlet pipe 16-2, the flue gas main pipe 16-4 is connected to flue gas recovery tank 18, the flue gas recovery tank 18 is connected to carbon dioxide fixation device 19 through pipe, the carbon dioxide fixation device 19 is connected to chimney 20 through pipe; the heat exchanger 11 is connected to the pipe connecting denitrification device 9 and bag filter 15 through its hot medium inlet and outlet, and the heat exchanger 11 is connected to the air inlet pipe connecting air tank 12 through its cold medium inlet and outlet.

[0018] Furthermore, a gas mixing tank 14 is connected to the pipe connected to the cold medium outlet of the heat exchanger 11. The pipe between the gas mixing tank 14 and the heat exchanger 11 is an air outlet pipe 13 with a first flow valve 13-1 installed on it. The gas mixing tank 14 is connected to an oxygen tank 21 through a pipe with an oxygen flow valve 22-1. A heater 22 is installed on the pipe between the oxygen flow valve 22-1 and the oxygen tank 21. The pipe on the output side of the gas mixing tank 14 is a gas mixing pipe 13-3. A second flow valve 13-2 is installed on the gas mixing pipe 13-3. A first booster fan 13-4 is installed on the pipe on the output side of the second flow valve 13-2. The gas mixing pipe 13-3 branches at its far end to form a biomass boiler air pipe 16-7 and a fluidized bed boiler air pipe 16-6. The biomass boiler air pipe 16-7 and the fluidized bed boiler air pipe 16-6 are respectively connected to the biomass boiler 6 and the fluidized bed boiler 7.

[0019] Furthermore, the denitrification pipeline 8-2 is also branched to form a dust collector inlet pipe 8-1 and connected to a dust collector 10. The exhaust port side of the dust collector 10 is connected to a pipeline and branched into two branches: a branch outlet pipe 17-1 and a dust collector outlet pipe 10-1. The dust collector outlet pipe 10-1 is connected to a flue gas recovery tank 18. A second booster fan 17 is installed on the branch outlet pipe 17-1. The far end of the branch outlet pipe 17-1 is connected to a flue gas combustion-supporting pipeline 16-3. A flue gas flow regulating valve 16-5 is installed on the flue gas combustion-supporting pipeline 16-3. The flue gas combustion-supporting pipeline 16-3 is branched at the far end to form a branch pipe connected to a biomass boiler 6 and a fluidized bed boiler 7.

[0020] The denitrification pipeline is also branched to form a denitrification bypass pipe 8-3. The other end of the denitrification bypass pipe 8-3 merges with the pipeline on the outlet side of the denitrification device 9 and then connects to the heat medium inlet of the heat exchanger 11. The connecting pipeline between the heat exchanger 11 and the bag filter 15 is branched to form a dust collector bypass pipe 15-1. The other end of the dust collector bypass pipe 15-1 merges with the pipeline on the outlet side of the bag filter 15 that connects to the desulfurization device 16. The connecting pipeline between the bag filter 15 and the desulfurization device 16 is branched to form a desulfurization bypass pipe 16-1. The other end of the desulfurization bypass pipe 16-1 is connected to the flue gas main pipe 16-4.

[0021] In this embodiment, the coal powder supply source is the same coal powder bin 4. The outlet of the coal powder bin 4 is connected to the coal powder conveyor belt 5. The far end of the coal powder conveyor belt 5 is connected to the first conveyor belt 5-1 and the second conveyor belt 5-2. The far ends of the first conveyor belt 5-1 and the second conveyor belt 5-2 are respectively connected to the fluidized bed boiler 7 and the biomass boiler 6 to supply coal powder.

[0022] The invention operates in three steps: the first step is system purging, which cleans the pipelines; the second step is combustion preparation, which prepares the combustible material by sending it into the corresponding boiler; and the third step is combustion, which ignites the boiler for combustion.

[0023] In the first step, the air tank 12 is opened to release air. The air flows out of the air tank and passes through the cold medium pipeline in the heat exchanger. The amount and speed of the air released through the air pipe can be adjusted by the first flow valve 13-1. The air enters the gas mixing tank 14 through the pipeline, and the air flow is further adjusted by the second flow valve 13-2, so that the air enters the first booster fan 13-4 for pressurization. The pressurized air is sent to the fluidized bed boiler 7 and the biomass boiler 6 at high temperature, high speed and high flow rate to purge the furnaces of the two boilers. The purged air flows out from the first flue gas pipeline 6-1 and the second flue gas pipeline 7-1 connected to the two boilers respectively, and is sent to the cyclone separator 8 for separation. The separated impurities are sent to the recovery box 8-5 through the impurity pipeline 8-4 for return. After separation, the gas exits from the cyclone separator 8, passes through the denitrification device 9, the internal heat medium pipeline of the heat exchanger 11, the bag filter 15, and the desulfurization device 16, and enters the main flue gas pipe 16-4, then enters the flue gas recovery tank 18 for recovery. At this time, the denitrification bypass pipe 8-3, the dust collector bypass pipe 15-1, the desulfurization bypass pipe 16-1, and the dust collector inlet pipe 8-1 are all closed. After the denitrification device, the bag filter, and the desulfurization device have been purged, the inlets of the three devices are closed, and the denitrification bypass pipe 8-3, the dust collector bypass pipe 15-1, and the desulfurization bypass pipe 16-1 are opened, so that the purging air bypasses the three devices and is purged through the bypass pipe into the flue gas recovery tank 18. The dust collector can also be purged with air as needed, and the purging air is also sent into the flue gas recovery tank 18.

[0024] In the second step, the coal in the pulverized coal silo 4 is transported in advance via the pulverized coal conveyor belt 5 and the first conveyor belt 5-1 and the second conveyor belt 5-2 to the respective furnaces of the fluidized bed boiler 7 and the biomass boiler 6. The oxygen tank 21 is opened, and the oxygen is heated by the heater 22 and then sent into the gas mixing tank 14 to mix with the air in the tank. The mixed gas is pressurized by the first booster fan 13-4 on the pipeline. During the gas transmission process, the oxygen flow rate can be adjusted by the oxygen flow control valve 22-1 and the mixed gas flow rate can be adjusted by the second flow valve 13-2. At the same time, a large amount of biomass materials such as straw stored in the biomass fuel storage silo 3 are dried, pressurized and gasified to generate biomass gas. The biomass gas is sent to the biomass gas treatment device 1 through the biomass gas transmission pipeline 2 to remove impurities and purify it. The purified biomass gas is sent to the biomass boiler 6 through the gas pipeline 1-1 to wait for mixing and combustion with the oxygen-enriched mixed gas and pulverized coal.

[0025] In the third step, combustion can be carried out in three ways: co-combustion, separate combustion, and flue gas-assisted combustion. Co-combustion means that both the biomass boiler and the fluidized bed boiler are ignited. Separate combustion means that either the biomass boiler or the fluidized bed boiler is selected for combustion. Flue gas-assisted combustion means that flue gas is sent into the corresponding two boilers to help with combustion.

[0026] During co-combustion, both biomass boiler 6 and fluidized bed boiler 7 operate and burn. The flue gas generated by biomass boiler 6 is discharged through the first flue gas pipe 6-1, and the flue gas generated by fluidized bed boiler 7 is discharged through the second flue gas pipe 7-1. The flue gas from both boilers merges and enters cyclone separator 8. Cyclone separator 8 separates large particulate impurities from the flue gas. These impurities enter impurity pipe 8-4 and then into impurity recovery box 8-5 for periodic processing. The processed flue gas is then discharged through denitrification pipe 8-2 and sent to denitrification device 9 for denitrification treatment. At this time, both the dust collector inlet pipe 8-1 and the denitrification bypass pipe 8-3 are... When the system is closed, the denitrified flue gas enters the heat exchanger 11 to heat the air passing through the heat exchanger. The flue gas after heat exchange enters the bag filter 15 for dust removal and is then sent to the desulfurization unit 16 for desulfurization treatment via the bag filter pipe 15-2. At this time, both the dust collector bypass pipe 15-1 and the desulfurization bypass pipe 16-1 are closed. The flue gas from the desulfurization unit 16 is sent to the flue gas main pipe 16-4 via the desulfurization outlet pipe 16-2 and then enters the flue gas recovery tank 18 for recovery. The flue gas from the flue gas recovery tank 18 passes through the carbon dioxide fixation device 19 for carbon dioxide capture and treatment. The treated flue gas is then discharged into the atmosphere through the chimney 20.

[0027] When pulverized coal is burned alone, only the pulverized coal exits from the pulverized coal silo 4 and is sequentially fed into the fluidized bed boiler 7 via the pulverized coal conveyor belt 5 and the first conveyor belt 5-1 for combustion; the biomass boiler does not burn. Conversely, when biomass is burned alone, the pulverized coal in the pulverized coal silo 4 is fed into the biomass boiler 6 via the pulverized coal conveyor belt 5 and the second conveyor belt 5-5, and is mixed with the biomass fuel gas fed into the biomass fuel storage silo 3 for combustion. When the flue gas is used for combustion assistance, the dust collector inlet pipe 8-1 needs to be opened so that the flue gas from the cyclone separator 8 first enters the dust collector 10 through the corresponding branch pipe for dust removal, and then is sent to the second booster fan 17 through the branch outlet pipe 17-1. After pressurization, it is then sent to the corresponding biomass boiler 6 or fluidized bed boiler 7 through the flue gas combustion assistance pipe 16-3 to assist combustion and further reduce nitrogen oxide emissions.

[0028] In the initial stage of boiler combustion, due to the large amount of impurities, the denitrification bypass pipe 8-3, the dust collector bypass pipe 15-1, and the desulfurization bypass pipe 16-1 can be opened to allow the flue gas to bypass the denitrification device, the bag filter, and the desulfurization device and be sent into the flue gas recovery tank, thus protecting the aforementioned three devices. At this time, all three bypass pipes are open. After the boiler is in normal combustion, the three bypass pipes are closed, and the flue gas is sent into the flue gas recovery tank after being treated by the denitrification device, the bag filter, and the desulfurization device.

[0029] After combustion, the supply of pulverized coal and / or biomass gas is stopped, while oxygen and air are continued to be supplied. Once the pulverized coal and / or biomass gas are completely burned, the oxygen supply from oxygen tank 21 is stopped and the oxygen flow valve 22-1 is closed. Air is continued to be supplied to reduce the furnace temperature of the boiler. At the same time, the remaining flue gas is blown to the cyclone separator 8 for separation and treatment. After separation, the flue gas is discharged in two paths. One path of flue gas continues to pass through heat exchanger 11, bag filter 15, desulfurization device 16, and flue gas recovery tank 18. The other path of flue gas passes through dust collector inlet pipe 8-1 and dust collector 10 and is then sent to flue gas recovery tank 18. The flue gas recovered by flue gas recovery tank 18 is then treated by carbon dioxide fixation device 19 and discharged into the atmosphere from chimney 20. Air tank 12 and first flow valve 13-1 are then closed.

[0030] The combustion system described in this invention can perform various combustion processes of pulverized coal and / or biomass materials, such as combustion in a single boiler, simultaneous combustion in two boilers, or flue gas recirculation for combustion assistance. The combustion process can be used to study the different effects of air-oxygen mixing and flue gas recirculation on combustion emissions, and to obtain research data on low-carbon emissions from small-scale unit combustion for further in-depth research.

Claims

1. A low-carbon emission combustion system for a generator set, comprising a pulverized coal combustion unit and a flue gas purification unit, wherein the pulverized coal combustion unit includes a fluidized bed boiler (7), and the flue gas purification unit includes a cyclone separator (8), a denitrification device (9), a desulfurization device (16), and a bag filter (15). The fluidized bed boiler (7) is connected to the flue gas purification unit through a second flue gas pipe (7-1), and the flue gas purification unit is connected to a chimney (20) through a pipe. The fluidized bed boiler (7) is connected to an air tank (12) for air intake through a pipe, and the feed inlet of the fluidized bed boiler (7) is connected to a pulverized coal supply. The system is characterized by... The combustion system also includes a biomass combustion unit, which includes a biomass boiler (6), a biomass fuel storage bin (3), and a biomass gas treatment device (1). The biomass fuel storage bin (3) is connected to the biomass gas treatment device (1) through a biomass gas pipeline (2). The biomass gas treatment device (1) is connected to the biomass boiler (6) through a gas pipeline (1-1). The biomass boiler (6) is connected to an air tank (12) through a pipeline for air intake. The biomass boiler (6) is connected to a flue gas purification unit through a first flue gas pipeline (6-1). The flue gas purification unit is connected to a flue gas recovery tank (18) through a flue gas main pipe (16-4). The flue gas recovery tank (18) is connected to a carbon dioxide fixation device (19) through a pipeline. The carbon dioxide fixation device (19) is connected to a chimney (20) through a pipeline.

2. The low-carbon emission combustion system for generator sets according to claim 1, characterized in that: The cyclone separator (8) is connected to the denitrification device (9) via a denitrification pipe (8-2). The denitrification device (9) is connected to the bag filter (15) via a pipe. The bag filter (15) is connected to the desulfurization device (16) via the bag filter pipe (15-2). The desulfurization device (16) is connected to the flue gas main pipe (16-4) via the desulfurization outlet pipe (16-2). After the first flue gas pipe (6-1) and the second flue gas pipe (7-1) merge... The cyclone separator (8) is connected to the inlet of the cyclone separator (8), and the cyclone separator (8) is connected to the recovery box (8-5) through an impurity pipe (8-4); the low carbon emission combustion system of the generator set also includes a heat exchanger (11), which is connected to the pipes of the denitrification device (9) and the bag filter (15) through its hot medium inlet and outlet, and the heat exchanger (11) is connected to the air inlet pipe of the air tank (12) through its cold medium inlet and outlet.

3. The low-carbon emission combustion system for generator sets according to claim 2, characterized in that: A gas mixing tank (14) is connected to the pipe connected to the cold medium outlet of the heat exchanger (11). The pipe between the gas mixing tank (14) and the heat exchanger (11) is an air outlet pipe (13) and is equipped with a first flow valve (13-1). The gas mixing tank (14) is connected to an oxygen tank (21) through a pipe with an oxygen flow valve (22-1). The pipe on the output side of the gas mixing tank (14) is a gas mixing pipe (13-3). A second flow valve (13-2) is installed on the gas mixing pipe (13-3). The gas mixing pipe (13-3) is branched at the far end to form a biomass boiler air pipe (16-7) and a fluidized bed boiler air pipe (16-6). The biomass boiler air pipe (16-7) and the fluidized bed boiler air pipe (16-6) are respectively connected to the biomass boiler (6) and the fluidized bed boiler (7).

4. The low-carbon emission combustion system for generator sets according to claim 3, characterized in that: A heater (22) is installed on the pipeline between the oxygen flow valve (22-1) and the oxygen tank (21).

5. The low-carbon emission combustion system for generator sets according to claim 3, characterized in that: A first booster fan (13-4) is installed on the pipeline on the output side of the second flow valve (13-2).

6. The low-carbon emission combustion system for generator sets according to claim 2, characterized in that: The denitrification pipeline (8-2) is branched to form a dust collector inlet pipe (8-1) and connected to a dust collector (10). The dust collector (10) is connected to a pipeline on the exhaust port side and branched into a branch outlet pipe (17-1) and a dust collector outlet pipe (10-1). The dust collector outlet pipe (10-1) is connected to a flue gas recovery tank (18). The far end of the branch outlet pipe (17-1) is connected to a flue gas combustion-supporting pipeline (16-3). A flue gas flow regulating valve (16-5) is installed on the flue gas combustion-supporting pipeline (16-3). The far end of the flue gas combustion-supporting pipeline (16-3) is branched to form a branch pipe connected to a biomass boiler (6) and a fluidized bed boiler (7).

7. The low-carbon emission combustion system for generator sets according to claim 6, characterized in that: The denitrification pipeline is branched to form a denitrification bypass pipe (8-3). The other end of the denitrification bypass pipe (8-3) merges with the pipeline on the outlet side of the denitrification device (9) and then connects to the heat medium inlet of the heat exchanger (11). The connecting pipeline between the heat exchanger (11) and the bag filter (15) is branched to form a dust collector bypass pipe (15-1). The other end of the dust collector bypass pipe (15-1) merges with the pipeline on the outlet side of the bag filter (15) that connects to the desulfurization device (16). The connecting pipeline between the bag filter (15) and the desulfurization device (16) is branched to form a desulfurization bypass pipe (16-1). The other end of the desulfurization bypass pipe (16-1) is connected to the flue gas main pipe (16-4).

8. The low-carbon emission combustion system for generator sets according to claim 6, characterized in that: A second booster fan (17) is installed on the branch outlet pipe (17-1).

9. The low-carbon emission combustion system for generator sets according to any one of claims 1 to 8, characterized in that: The coal powder supply source is a coal powder silo (4). The outlet of the coal powder silo (4) is connected to a coal powder conveyor belt (5). The far end of the coal powder conveyor belt (5) is connected to a first conveyor belt (5-1) and a second conveyor belt (5-2). The far ends of the first conveyor belt (5-1) and the second conveyor belt (5-2) are respectively connected to a fluidized bed boiler (7) and a biomass boiler (6) to supply coal powder.

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