A high-efficiency desulfurization system for coal gas boilers and its application method

Abstract

This invention relates to a high-efficiency desulfurization system and application method for a gas boiler. A high-temperature flue gas bypass is added between the air preheater and the downstream economizer, leading to the main flue gas pipeline after the gas heater. The sodium bicarbonate delivery pipeline is connected to the high-temperature flue gas bypass via a connecting pipe. The sodium bicarbonate enters the high-temperature flue gas bypass through the connecting pipe and mixes with the high-temperature flue gas. After preheating by the high-temperature flue gas, it is injected into the main pipeline through a new injection device to carry out the desulfurization reaction, bypassing the air preheater and gas heater, thus avoiding blockages in these two systems that could prevent the boiler from achieving 100% load regulation capability. This invention uses high-temperature flue gas to preheat the sodium bicarbonate, improving its reactivity and ensuring optimal reaction temperature and desulfurization efficiency. Simultaneously, the existing desulfurization system is retained, serving as a backup for the existing system, improving its stability and facilitating online maintenance and repair without affecting the stable operation of the power generation system. This invention has very high practical value.

Description

Technical Field

[0001] This patent application belongs to the field of desulfurization technology, and more specifically, relates to a high-efficiency desulfurization system for coal gas boilers and its application method. Background Technology

[0002] The desulfurization system of the gas boiler uses a dry desulfurization method with baking soda. Baking soda is fed into the front end of the air preheater via a grinder and jet fan. The air preheater contains a heat exchanger with staggered finned tubes. Baking soda easily gets trapped between the finned tubes, causing blockage and increasing the pressure difference across the air preheater. This leads to overload operation of the boiler's forced and induced draft fans. As operating time increases, the flue gas desulfurization system becomes increasingly unstable, even exceeding safety limits. Furthermore, due to the increased pressure difference in the boiler flue gas system, the boiler no longer has 100% load regulation capability when the induced draft fan is running at full load, requiring frequent shutdowns for air preheater cleaning, which affects the normal operation of the boiler generator unit. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a high-efficiency desulfurization system and application method for coal gas boilers. In order to address the shortcomings of the existing desulfurization system, the desulfurization system for coal gas boilers is modified to eliminate the blockage of the air preheater, improve the desulfurization reaction efficiency, and ensure the stable operation of the boiler generator set.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: A high-efficiency desulfurization system for coal gas boilers includes a sodium bicarbonate pulverizing system, a conveying system, a desulfurization reaction system, and a bag filter dust collection system. The baking soda powder making system includes a redundant arrangement of a No. 1 baking soda hopper and a No. 2 baking soda hopper, a No. 1 grinder connected to the No. 1 baking soda hopper, and a No. 2 grinder connected to the No. 2 baking soda hopper; The conveying system includes a No. 1 jet blower connected to No. 1 grinding mill, a No. 2 jet blower connected to No. 2 grinding mill, a sodium bicarbonate conveying pipeline connected to both No. 1 and No. 2 jet blowers, a connecting pipeline connected to the middle of the sodium bicarbonate conveying pipeline, a high-temperature flue bypass connected to the connecting pipeline, a boiler connected to the high-temperature flue bypass, a main flue gas pipeline connected to the boiler, and a gas heater installed on the main flue gas pipeline. The boiler is equipped with an air preheater and a lower-stage economizer. The high-temperature flue bypass is located between the air preheater and the lower-stage economizer. The end of the high-temperature flue bypass is led to both sides (e.g., the east and west sides) of the main flue gas pipeline after the gas heater. The high-temperature flue bypass is connected to the desulfurization reaction system. The desulfurization reaction system includes the original injection device and the new injection device. The original injection device is connected to the sodium bicarbonate delivery pipeline and contains 8 injection pipes. Its state is that the injection pipe valves are closed. The original desulfurization pipeline injection inlet of the original injection device is located between the air preheater and the lower economizer. One end of the new injection device is connected to the high-temperature flue bypass, and the other end is connected to the main flue gas pipeline into which sodium bicarbonate is injected. The injection inlet of the new injection device is located on both sides of the main flue gas pipeline (for example, the east and west sides), and it adopts a large-diameter swirl injection method. The baghouse dust collection system includes a baghouse dust collector and an ash silo. The input end of the baghouse dust collector (16) is connected to the main flue gas pipeline, and the output end is connected to the ash silo.

[0005] Furthermore, grinding mill #1 and grinding mill #2 grind baking soda to a particle size of 800~1000 mesh. The two grinding mills are arranged in a one-in-use-one-standby configuration. Nitrogen booster systems are installed on the outlet pipes of the jet blowers #1 and #2, which are existing equipment.

[0006] Furthermore, the bending radius of the high-temperature flue bypass should be no less than 1500mm to reduce friction loss along the path.

[0007] Furthermore, a spiral flow guiding device is installed in the sodium bicarbonate conveying pipeline and the high-temperature flue bypass to balance the flue gas volume, flue gas velocity and flue gas pressure.

[0008] Furthermore, a flue gas regulating valve and a remote temperature and pressure measuring point are installed on the high-temperature flue bypass, which are used to adjust the flue gas volume and monitor the flue gas temperature and pressure, respectively.

[0009] Furthermore, a purging system is added to the front end of the valve of the new injection device, and the air source for the purging system is nitrogen.

[0010] Furthermore, the material of the filter bag in the baghouse dust collector should have a service temperature of not less than 180℃ and a service life of not less than 3 years.

[0011] Furthermore, the baghouse dust collector includes a pulse-jet cleaning system. The working principle of this system is as follows: Each row of filter bags has a pulse-jet pipe connected to the air distribution manifold via an electromagnetic pulse valve. Compressed air in the air distribution manifold presses against the trigger diaphragm and the main diaphragm, keeping the electromagnetic pulse valve closed. Under the excitation of the electromagnetic valve, a pressure difference is generated on the trigger diaphragm, causing it to lift. Air leaks out from one side of the main diaphragm, which then lifts under the pressure difference. Compressed air from the air distribution manifold enters the pulse-jet pipe and, guided by the pipe, rushes into the filter bags. The rapidly descending compressed airflow within the filter bags creates a sudden radial deformation of the filter bags relative to the bag cage, causing the dust accumulated on the filter bag surface to fall off. When the electromagnetic pulse valve is not activated, the air leak is closed, and the air pressure resets the trigger diaphragm and the main diaphragm, closing the electromagnetic pulse valve.

[0012] A method for applying a high-efficiency desulfurization system for a coal gas boiler, utilizing the aforementioned system, includes the following steps: S1. Baking soda is conveyed to the corresponding grinder through the baking soda hopper. After being ground by the grinder, the baking soda is conveyed to the baking soda conveying pipeline by the corresponding jet fan. S2. Close the original injection device valve, open the connecting pipeline valve and the new injection device valve, and at the same time, adjust the flue gas regulating valve on the high-temperature flue bypass to control the high-temperature flue gas at a suitable temperature to improve the sodium bicarbonate reaction activity and ensure the optimal reaction temperature and optimal desulfurization efficiency of sodium bicarbonate. S3. Baking soda enters the high-temperature flue bypass through the connecting pipe and mixes with the high-temperature flue gas at a suitable temperature for preheating. The preheated baking soda is then injected into the main flue gas pipeline through the valve of the new injection device to carry out the desulfurization reaction. S4. After the reaction, the baking soda enters the bag filter for recycling and is finally transported to the ash silo for recycling and storage. Specifically, the desulfurization products after the desulfurization reaction enter the bag filter together with the flue gas, and the desulfurization by-products enter the ash hopper of the bag filter. The dust is collected by the scraper conveyor and then transported to the ash silo by the bucket elevator for recycling and storage. S5. When the new injection device malfunctions, close the valve of the new injection device and open the valve of the original injection device, and use the original desulfurization pipeline for the desulfurization reaction; this avoids shutdown accidents caused by exceeding environmental protection standards and ensures stable and effective desulfurization.

[0013] Furthermore, in S2, the suitable temperature for the high-temperature flue gas is 200℃~400℃.

[0014] Due to the adoption of the above technical solution, the beneficial effects achieved by this invention are: This invention completely solves the systemic hidden dangers of the flue gas system of a gas boiler by changing the injection location and method of the desulfurizing agent sodium bicarbonate. By adopting a premixing method of sodium bicarbonate into the flue gas, the desulfurization efficiency is improved and the production cost is reduced. After being preheated by high-temperature flue gas, the flue gas is injected into the main pipeline through a new injection device to carry out the desulfurization reaction, without passing through the air preheater and gas heater. This avoids the blockage of the air preheater and gas heater, which could prevent the boiler from having 100% load regulation capability and avoid environmental shutdown accidents. At the same time, the original desulfurization system and the existing desulfurization system are mutually redundant, further improving the stability of the desulfurization system and ensuring the stable operation of the boiler generator unit. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the process structure of the present invention.

[0016] Figure 2 This is a schematic diagram illustrating the working principle of the dust removal jet cleaning system in this invention.

[0017] The following are marked in the diagram: 1# Baking soda hopper, 2# Baking soda hopper, 1# Grinding mill, 3# Grinding mill, 4# Grinding mill, 1# Jet blower, 5# Jet blower, 6# Lower-stage economizer, 7# Air preheater, 8# Original jetting device, 9# Baking soda conveying pipeline, 10# Connecting pipeline, 11# High-temperature flue bypass, 12# Main flue gas pipeline, 13# Gas heater, 14# New jetting device, 15# Bag filter, 16# Boiler induced draft fan, 17# Boiler, 18# Ash silo. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the embodiments.

[0019] A high-efficiency desulfurization system for coal gas boilers, such as Figure 1 This includes a baking soda powdering system, a conveying system, a desulfurization reaction system, and a bag filter dust collection system; The baking soda powdering system includes a baking soda hopper 1, a baking soda hopper 2, a grinder 3, and a grinder 4. Baking soda hopper 1 is connected to grinder 3, and baking soda hopper 2 is connected to grinder 4. Baking soda is added to the hoppers and ground into particles with a size of 800-1000 mesh by the grinders.

[0020] Specifically, the two grinding machines (grinding machine 1# and grinding machine 2#) are arranged with separate pipelines, one for use and one for standby.

[0021] The conveying system includes a #1 jet blower 5, a #2 jet blower 6, a baking soda conveying pipe 10, a connecting pipe 11, and a high-temperature flue bypass 12. Specifically, it includes a #1 jet blower 5 connected to a #1 grinder 3, a #2 jet blower 6 connected to a #2 grinder 4, a baking soda conveying pipe 10 (DN159) connected to both #1 jet blower 5 and #2 jet blower 6, a connecting pipe 11 (DN150) connected to the middle of the baking soda conveying pipe 10, and a high-temperature flue bypass 12 connected to the connecting pipe 11. The system includes a flue bypass 12 (DN600), a boiler 18 connected to the high-temperature flue bypass 12, a main flue gas duct 13 connected to the boiler 18, and a gas heater 14 installed on the main flue gas duct 13. The boiler 18 is equipped with an air preheater 8 and a lower-stage economizer 7. The high-temperature flue bypass 12 is located between the air preheater 8 and the lower-stage economizer 7. The end of the high-temperature flue bypass 12 is led to both sides of the main flue gas duct 13 after the gas heater 14, such as the east and west sides. The high-temperature flue bypass 12 is connected to the desulfurization reaction system.

[0022] A new high-temperature flue bypass 12 is added between the air preheater 8 and the lower-stage economizer 7, leading to both sides (east and west sides) of the main flue gas pipeline 13 after the gas heater 14. The baking soda delivery pipeline 10 is connected to the high-temperature flue bypass 12 through the connecting pipeline 11. The ground baking soda is delivered to the baking soda delivery pipeline 10 by the jet blower, and then enters the high-temperature flue bypass 12 through the connecting pipeline 11 to mix with the high-temperature flue gas. After being preheated by the high-temperature flue gas, it enters the new jetting device 15.

[0023] Specifically, nitrogen-assisted propulsion systems are installed in the outlet pipes of jet blowers #1 (5) and #2 (6), and pneumatic ball valves are used for the outlet valves. Remote pressure and temperature measuring points are installed in the outlet pipes, and local pressure gauges are installed at the powder injection nozzles.

[0024] Specifically, the bending radius of the newly added high-temperature flue bypass 12 shall not be less than 1500mm, in order to reduce friction loss along the way.

[0025] Specifically, the sodium bicarbonate conveying pipeline 10 and the high-temperature flue bypass 12 are equipped with spiral flow guiding devices to balance the flue gas volume, flue gas velocity and flue gas pressure.

[0026] Specifically, the high-temperature flue bypass 12 is equipped with a flue gas regulating valve and a remote temperature and pressure measuring point, which are used to adjust the flue gas volume and monitor the flue gas temperature and pressure, respectively.

[0027] The desulfurization reaction system includes the original injection device 9 and the new injection device 15. The original injection device 9 is connected to the sodium bicarbonate conveying pipeline 10 and contains 8 spray pipes. Its state is that the spray pipe valves are closed. The original desulfurization pipeline inlet of the original injection device 9 is located between the air preheater 8 and the lower economizer 7. One end of the new injection device 15 is connected to the high-temperature flue bypass 12 and the other end is connected to the main flue gas pipeline 13 into which sodium bicarbonate is injected. The spray inlets of the new injection device 15 are located on both sides of the main flue gas pipeline 13 (for example, the east and west sides respectively). It adopts a large-diameter swirl injection method. When the valve of the new injection device 15 is opened, the preheated sodium bicarbonate is injected into the main flue gas pipeline 13 to carry out the desulfurization reaction of the flue gas.

[0028] Specifically, a purging system is added to the front end of valve 15 of the new injection device, and nitrogen is used as the purging gas source.

[0029] The baghouse dust collection system includes a baghouse dust collector 16 and an ash silo 19. The input end of the baghouse dust collector 16 is connected to the main flue gas duct 13, and the output end is connected to the ash silo 19. The desulfurization products after the desulfurization reaction enter the baghouse dust collector along with the flue gas, and the desulfurization by-products enter the dust collector's ash hopper. The dust collected by the scraper conveyor is then transported to the ash silo by the bucket elevator for recycling and storage.

[0030] Specifically, the material of the 16 filter bags in the baghouse dust collector has an operating temperature of not less than 180℃ and a service life of not less than 3 years.

[0031] Specifically, the bag filter 16 includes a dust removal pulse-jet cleaning system, the working principle of which is as follows: Figure 2 As shown: Each row of filter bags has a blowpipe connected to the air distribution manifold via an electromagnetic pulse valve. Compressed air in the air distribution manifold presses against the trigger diaphragm and the main diaphragm, keeping the electromagnetic pulse valve closed. Under the excitation of the electromagnetic valve, a pressure difference is generated on the trigger diaphragm, causing it to lift. Air is released from one side of the main diaphragm, which then lifts under the pressure difference. Compressed air from the air distribution manifold enters the blowpipe and is guided into the filter bags by the blowpipe.

[0032] The rapidly descending compressed airflow within the filter bag causes a sudden radial deformation of the filter bag relative to the cage, causing accumulated dust on the filter bag's surface to fall off. When the electromagnetic pulse valve is not activated, the air vent is closed, and the air pressure triggers the diaphragm and main diaphragm to reset, closing the electromagnetic pulse valve.

[0033] The application method of this invention is as follows: 1) Baking soda is conveyed to the corresponding grinder through the baking soda hopper. After being ground by the grinder, the baking soda is conveyed to the baking soda conveying pipe 10 by the corresponding jet fan.

[0034] 2) Close the original injection device 9 valve, open the connecting pipe 11 valve and the new injection device 15 valve, and at the same time control the flue gas temperature at around 300℃ (generally 200℃~400℃) by adjusting the flue gas regulating valve on the high temperature flue bypass 12 to improve the sodium bicarbonate reaction activity and ensure the optimal reaction temperature and optimal desulfurization efficiency of sodium bicarbonate.

[0035] 3) Baking soda enters the high-temperature flue bypass 12 through the connecting pipe 11 and mixes with the high-temperature flue gas at about 300°C for preheating. The preheated baking soda is then injected into the main flue gas pipe 13 through the valve of the new injection device 15 along with the high-temperature flue gas to carry out the desulfurization reaction.

[0036] 4) The sodium bicarbonate after the reaction enters the bag filter 16 for recovery and is finally transported to the ash silo 19 for recycling and storage. Specifically, the desulfurization products after the desulfurization reaction enter the bag filter 16 together with the flue gas, and the desulfurization by-products enter the ash hopper of the bag filter 16. The dust is collected by the scraper conveyor and then transported to the ash silo 19 by the bucket elevator for recycling and storage.

[0037] 5) When the new injection device 15 malfunctions, close the valve of the new injection device 15 and open the valve of the original injection device 9. Use the original desulfurization pipeline to carry out the desulfurization reaction, thus avoiding the shutdown accident caused by exceeding environmental protection standards and ensuring stable and effective desulfurization effect.

[0038] This invention can effectively ensure the high-efficiency and stable operation of the desulfurization system. On the one hand, it ensures the stable operation of the boiler generator unit, and on the other hand, it avoids environmental accidents caused by unit shutdown due to pipeline blockage, which would lead to gas release. It improves the stability of the desulfurization system and has significant practical effects.

[0039] This invention adds a high-temperature flue gas bypass (DN600) between the air preheater and the downstream economizer, leading to the main flue gas pipeline after the gas heater. The sodium bicarbonate delivery pipeline (DN159) is connected to the high-temperature flue gas bypass (DN600) via a connecting pipeline (DN150). Sodium bicarbonate enters the high-temperature flue gas bypass (DN600) through the connecting pipeline (DN150) and mixes with the high-temperature flue gas. After preheating by the high-temperature flue gas, it is injected into the main pipeline through a new injection device to carry out the desulfurization reaction of the flue gas, bypassing the air preheater and gas heater. This avoids the blockage of the air preheater and gas heater, preventing the boiler from achieving 100% load regulation capability. This invention uses high-temperature flue gas to preheat the sodium bicarbonate, improving its reactivity and ensuring the optimal reaction temperature and desulfurization efficiency. Simultaneously, the original desulfurization system is retained, serving as a backup for the existing system, improving its stability and facilitating online maintenance and repair without affecting the stable operation of the power generation system. It has very high practical value.

Claims

1. A high efficiency coal gas boiler desulfurization system, characterized in that: This includes a baking soda pulverizing system, a conveying system, a desulfurization reaction system, and a bag filter dust collection system. The baking soda powder making system includes a redundant arrangement of a No. 1 baking soda hopper (1) and a No. 2 baking soda hopper (2), a No. 1 grinder (3) connected to the No. 1 baking soda hopper (1), and a No. 2 grinder (4) connected to the No. 2 baking soda hopper (2). The conveying system includes a No. 1 jet blower (5) connected to the No. 1 grinder (3), a No. 2 jet blower (6) connected to the No. 2 grinder (4), a sodium bicarbonate conveying pipeline (10) connected to both the No. 1 jet blower (5) and the No. 2 jet blower (6), a connecting pipeline (11) connected to the middle of the sodium bicarbonate conveying pipeline (10), a high-temperature flue bypass (12) connected to the connecting pipeline (11), a boiler (18) connected to the high-temperature flue bypass (12), and a... The boiler (18) is connected to the main flue gas pipe (13) and the gas heater (14) is installed on the main flue gas pipe (13). The boiler (18) is equipped with an air preheater (8) and a lower economizer (7). The high temperature flue bypass (12) is located between the air preheater (8) and the lower economizer (7). The end of the high temperature flue bypass (12) is led to both sides of the main flue gas pipe (13) after the gas heater (14). The high temperature flue bypass (12) is connected to the desulfurization reaction system. The desulfurization reaction system includes the original injection device (9) and the new injection device (15). The original injection device (9) is connected to the sodium bicarbonate conveying pipeline (10) and contains 8 injection pipes. Its state is that the injection pipe valves are closed. The original desulfurization pipeline injection inlet of the original injection device (9) is located between the air preheater (8) and the lower economizer (7). One end of the new injection device (15) is connected to the high temperature flue bypass (12) and the other end is connected to the main flue gas pipeline (13) into which sodium bicarbonate is injected. The injection inlet of the new injection device (15) is located on both sides of the main flue gas pipeline (13) and it adopts a large-diameter swirl injection method. The bag filter dust collection system includes a bag filter (16) and an ash silo (19). The input end of the bag filter (16) is connected to the main flue gas duct (13), and the output end is connected to the ash silo (19).

2. A high efficiency coal gas boiler desulphurization system as claimed in claim 1, wherein: The No. 1 grinder (3) and No. 2 grinder (4) grind baking soda to a particle size of 800~1000 mesh. The outlet pipes of the No. 1 jet blower (5) and No. 2 jet blower (6) are equipped with nitrogen booster systems.

3. A high efficiency coal gas boiler desulphurization system as claimed in claim 2, wherein: The bending radius of the high-temperature flue bypass (12) shall not be less than 1500mm.

4. A high efficiency coal gas boiler desulphurization system as claimed in claim 2, wherein: Spiral guide devices are installed in the sodium bicarbonate conveying pipeline (10) and the high-temperature flue bypass (12) to balance the flue gas volume, flue gas velocity and flue gas pressure.

5. The high-efficiency coal gas boiler desulfurization system according to claim 1, characterized in that: The high-temperature flue bypass (12) is equipped with a flue gas regulating valve and a remote temperature and pressure measuring point, which are used to adjust the flue gas volume and monitor the flue gas temperature and pressure, respectively.

6. A high-efficiency coal gas boiler desulfurization system according to any one of claims 1-5, characterized in that: The new injection device (15) is equipped with a purging system at the front end of the valve, and the purging system uses nitrogen as its gas source.

7. The high-efficiency coal gas boiler desulfurization system according to claim 1, characterized in that: The material of the filter bag in the bag dust collector (16) has a service temperature of not less than 180℃ and a service life of not less than 3 years.

8. A high-efficiency coal gas boiler desulfurization system according to claim 1, characterized in that: The bag filter (16) includes a dust removal pulse jet system. The working principle of the dust removal pulse jet system is as follows: There is a pulse jet pipe on each row of filter bags, which is connected to the air distribution manifold through an electromagnetic pulse valve. The compressed air in the air distribution manifold presses the trigger diaphragm and the main diaphragm to keep the electromagnetic pulse valve closed. Under the excitation of the electromagnetic valve, a pressure difference is generated on the trigger diaphragm, the trigger diaphragm is lifted, and the air on one side of the main diaphragm is released. The main diaphragm is lifted under the action of the pressure difference, and the compressed air in the air distribution manifold enters the pulse jet pipe and is guided into the filter bag by the pulse jet pipe. The compressed air flow that rushes down quickly in the filter bag forms a sudden radial deformation of the filter bag relative to the bag cage, causing the dust accumulated on the surface of the filter bag to fall off. When the electromagnetic pulse valve is not energized, the air outlet is closed, the air pressure resets the trigger diaphragm and the main diaphragm, and the electromagnetic pulse valve is closed.

9. A method for applying a high-efficiency coal gas boiler desulfurization system, utilizing the system described in any one of claims 1 to 8, characterized in that... Includes the following steps: S1. Baking soda is conveyed to the corresponding grinder through the baking soda hopper. After being ground by the grinder, the baking soda is conveyed to the baking soda conveying pipe (10) by the corresponding jet blower. S2. Close the valve of the original injection device (9), open the valve of the connecting pipe (11) and the valve of the new injection device (15), and at the same time, adjust the flue gas regulating valve on the high temperature flue bypass (12) to control the high temperature flue gas at a suitable temperature to improve the reaction activity of sodium bicarbonate and ensure the optimal reaction temperature and optimal desulfurization efficiency of sodium bicarbonate. S3. Baking soda enters the high-temperature flue bypass (12) through the connecting pipe (11) and mixes with the high-temperature flue gas at a suitable temperature for preheating. The preheated baking soda is then injected into the main flue gas pipeline (13) through the valve of the new injection device (15) to carry out the desulfurization reaction. S4. The baking soda after the reaction enters the bag filter (16) for recycling and is finally transported to the ash silo (19) for recycling and storage. S5. When the new injection device (15) malfunctions, close the valve of the new injection device (15), open the valve of the original injection device (9), and use the original desulfurization pipeline for desulfurization reaction.

10. The application method of a high-efficiency coal gas boiler desulfurization system according to claim 9, characterized in that: In S2, the suitable temperature for high-temperature flue gas is 200℃~400℃.

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