A system for blending biomass and gasified fine slag in a pulverized coal boiler

Abstract

The present application relates to the technical field of coal powder boiler blending combustion and solid waste disposal, and particularly relates to a blending combustion system for blending combustion of biomass and gasified fine slag in a coal powder boiler. The blending combustion system comprises a boiler, a raw coal powder conveying system, a biomass gasification conveying system, a gasified fine slag conveying system, a mixing device, a booster fan and an atomization device. The boiler is provided with a burner and a secondary air inlet. The inlet of the mixing device is connected with the raw coal powder conveying system and the biomass gasification conveying system respectively, and the outlet of the mixing device is connected with the burner of the boiler. The inlet of the atomization device is connected with the gasified fine slag conveying system and the booster fan respectively, and the outlet of the atomization device is connected with the secondary air inlet of the boiler. The atomized gasified fine slag is sprayed through a separate secondary air nozzle, and the blending ratio of the gasified fine slag is controlled to effectively reduce the melting and agglomeration phenomenon. The problem that the ash and slag of the system provided by the prior art is wrapped with combustible materials after the gasified fine slag is added, thereby hindering the combustion, is solved.

Description

Technical Field

[0001] This invention relates to the field of pulverized coal boiler co-firing and solid waste disposal technology, specifically to a co-firing system for pulverized coal boilers that co-firing biomass and gasified fine slag. Background Technology

[0002] Co-firing systems or technologies using pulverized coal boilers to co-fire biomass and gasification slag are a process of recycling high-carbon-content gasification slag and biomass. This not only utilizes the carbon resources but also converts high-carbon slag into low-carbon slag, facilitating the use of both gasification slag and biomass in building materials. By employing pulverized coal boilers for co-firing, comprehensive resource utilization of gasification slag and biomass is achieved, reducing environmental pollution.

[0003] Prior art 1: CN 216481074 U discloses a system suitable for direct co-firing of gasified fine ash in pulverized coal boilers. This system mainly includes a gasified fine ash conveying system, a high-temperature and high-pressure atomization drying system, and a novel pulverized coal conveying system. The gasified fine ash conveying system includes a gasified fine ash storage silo, a positive pressure feeding device, a paste pump, and a conveying pipeline connected in sequence. The high-temperature and high-pressure atomization drying system includes a hot primary air bypass and an atomizing device. The atomizing air is drawn from the hot primary air bypass, increased in pressure by a booster fan, and then led to the atomizing device to achieve atomization and drying of the gasified fine ash. The gasified fine ash carry-over flow conveying pipeline at the outlet of the atomizing device is connected to the pulverized coal pipeline via a mixing device, forming a novel pulverized coal conveying system that achieves efficient mixing of the gasified fine ash carry-over flow and the pulverized coal airflow.

[0004] However, in the system provided by the prior art 1, the pulverized coal feeding system and the gasification fine slag system enter the mixing device together, and then enter the boiler directly from the combustion chamber. As a result, after the gasification fine slag is added to the boiler, a large number of molten areas appear in the ash and slag, which encapsulate the combustibles and thus hinder combustion. Summary of the Invention

[0005] In order to solve the problem that in existing systems, after adding gasified fine slag, a large number of molten areas appear in the ash slag, which encapsulate combustibles and thus hinder combustion, the present invention aims to provide a co-firing system for pulverized coal boilers that co-fires biomass and gasified fine slag.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows.

[0007] This invention provides a co-firing system for pulverized coal boilers that co-fires biomass and gasified slag, comprising a boiler, a raw coal conveying system, a biomass gasification conveying system, a gasified slag conveying system, a mixing device, a booster fan, and an atomizing device; the boiler has a burner and a secondary air inlet; the inlet of the mixing device is connected to both the raw coal conveying system and the biomass gasification conveying system, and the outlet of the mixing device is connected to the burner of the boiler; the inlet of the atomizing device is connected to both the gasified slag conveying system and the booster fan, and the outlet of the atomizing device is connected to the secondary air inlet of the boiler.

[0008] This invention mainly involves injecting gasified fine slag through a separate secondary air inlet, thereby controlling the blending ratio of the gasified fine slag. At the same time, it effectively reduces melting and agglomeration, improves combustion efficiency, and solves the problem in existing systems where a large number of molten areas appear in the ash after adding gasified fine slag, which encapsulate combustibles and thus hinder combustion.

[0009] Preferably, the system further includes a primary air duct, the first outlet of which is connected to the inlet of the raw coal conveying system, and the second outlet of which is connected to the inlet of the booster fan. The system of the present invention uses a booster fan to provide high-temperature, high-pressure primary air for atomization to the atomizing device, eliminating the need for additional pre-drying of the gasified fine slag, thus reducing the investment cost and steam cost of the drying device.

[0010] Preferably, the co-firing system includes an air preheater, the flue gas outlet of the boiler is connected to a flue gas duct, and the outlet of the flue gas duct is connected to the inlet of the air preheater; a portion of the primary air duct is coiled inside the air preheater, configured to exchange heat and raise the temperature of the primary air within the primary air duct. The air preheater of this invention is used to exchange heat and raise the temperature of the primary air within the primary air duct. The primary air, after being heated by the air preheater, enters the raw coal conveying system and the booster fan via the primary air duct, respectively, for drying the pulverized coal and atomizing the gasified slag.

[0011] Preferably, the raw coal conveying system includes a coal mill, the first outlet of the primary air duct is connected to the inlet of the coal mill, and the outlet of the coal mill is connected to the mixing device.

[0012] Preferably, the raw coal pulverizing system includes a raw coal bunker, a coal feeder, and a pulverizing pipeline. The outlet of the raw coal bunker is connected to the inlet of the coal feeder, the outlet of the coal feeder is connected to the inlet of the pulverizing pipeline, the outlet of the pulverizing pipeline is connected to the inlet of the coal mill, and the outlet of the coal mill is connected to the first inlet of the mixing device. In this invention, coal in the raw coal bunker enters the pulverizing pipeline through the coal feeder, and then enters the coal mill through the pulverizing pipeline to grind the coal in the raw coal bunker. The finely ground coal powder then enters the mixing device.

[0013] Preferably, the blending system includes a first control system, the inlet of which is connected to the raw coal bunker, and the outlet of which is connected to the coal feeder.

[0014] Preferably, the biomass gasification conveying system includes a biomass gasification device and a purification device. The outlet of the biomass gasification device is connected to the inlet of the purification device, and the outlet of the purification device is connected to the second inlet of the mixing device. The biomass gasification device of this invention is used to heat and gasify the input biomass to form fuel gas. The purification device is used to purify the fuel gas. Biomass enters the biomass gasification device, is heated and gasified to form fuel gas, and then the fuel gas is purified by the purification device to remove solid particles and water and other impurities, thereby effectively alleviating ash accumulation and slagging on the boiler's tail heating surface. The purified fuel gas is sent to the mixing device to mix with finely ground coal powder. Then, the mixture is driven by primary air into the boiler's burner for co-combustion.

[0015] Preferably, the co-firing system includes a second control system, the inlet of which is connected to the biomass gasification device, and the outlet of which is connected to the purification device.

[0016] Preferably, the gasified fine slag conveying system includes a gasified fine slag storage bin, a positive pressure feeding device, and a paste pump; the outlet of the gasified fine slag storage bin is connected to the inlet of the positive pressure feeding device, and the outlet of the positive pressure feeding device is connected to the inlet of the paste pump; the outlet of the paste pump is connected to the inlet of the atomizing device. The gasified fine slag storage bin of this invention provides gasified fine slag, which enters the atomizing device through the positive pressure feeding device and the paste pump. The gasified fine slag in the atomizing device is atomized using high-temperature, high-pressure primary air for atomization, and then sent into the secondary air nozzle of the boiler. This invention connects the gasified fine slag conveying system to the primary air pipeline, and then, after atomization, enters the boiler, forming combustion particles before combustion. Because the atomized gasified fine slag is injected through a separate secondary air nozzle, the blending ratio of the gasified fine slag can be reduced, thereby effectively reducing melting and agglomeration.

[0017] Preferably, the blending system includes a third control system, the inlet of which is connected to the gasification slag storage bin, and the outlet of which is connected to the positive pressure feeding device. This invention, through the first, second, and third control systems, can adjust the blending ratio of coal, biomass, and gasification slag according to the required fuel blending ratio to meet the fuel requirements of the boiler combustion.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention injects atomized gasified fine slag through a separate secondary air inlet, thereby controlling the mixing ratio of the gasified fine slag, effectively reducing melting and agglomeration, improving combustion efficiency, and solving the problem in existing systems where a large number of molten areas appear in the ash after adding gasified fine slag, which encapsulate combustibles and thus hinder combustion.

[0020] 2. The system of the present invention uses a booster fan to provide high-temperature and high-pressure primary air for atomization to the atomization device, eliminating the need for additional pre-drying of gasified fine slag, thus reducing the investment cost and steam cost of the drying device. Attached Figure Description

[0021] Figure 1 This is a system layout diagram of a pulverized coal boiler co-firing system for biomass and gasified fine slag, provided as an embodiment of the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 1. Boiler; 2. Primary air fan; 3. Air preheater; 4. Raw coal bunker; 5. First control system; 6. Coal feeder; 7. Coal mill; 8. Biomass gasification unit; 9. Second control system; 10. Purification unit; 11. Mixing unit; 12. Gasification slag storage bin; 13. Third control system; 14. Positive pressure feeding device; 15. Paste pump; 16. Booster fan; 17. Atomizing device. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Prior art 1: CN 216481074 U discloses a system suitable for direct co-firing of gasified fine ash in pulverized coal boilers. This system mainly includes a gasified fine ash conveying system, a high-temperature and high-pressure atomization drying system, and a novel pulverized coal conveying system. The gasified fine ash conveying system includes a gasified fine ash storage silo, a positive pressure feeding device, a paste pump, and a conveying pipeline connected in sequence. The high-temperature and high-pressure atomization drying system includes a hot primary air bypass and an atomizing device. The atomizing air is drawn from the hot primary air bypass, increased in pressure by a booster fan, and then led to the atomizing device to achieve atomization and drying of the gasified fine ash. The gasified fine ash carry-over flow conveying pipeline at the outlet of the atomizing device is connected to the pulverized coal pipeline via a mixing device, forming a novel pulverized coal conveying system that achieves efficient mixing of the gasified fine ash carry-over flow and the pulverized coal airflow.

[0027] However, in the system provided by the prior art 1, the pulverized coal feeding system and the gasification fine slag system enter the mixing device together, and then enter the boiler directly from the combustion chamber. As a result, after the gasification fine slag is added to the boiler, a large number of molten areas appear in the ash and slag, which encapsulate the combustibles and thus hinder combustion.

[0028] Based on this, the present invention provides a co-firing system for pulverized coal boilers that co-fires biomass and gasified fine slag. The main feature of this invention is the injection of gasified fine slag through a separate secondary air inlet, thereby controlling the blending ratio of the gasified fine slag and effectively reducing melting and agglomeration, thus improving combustion efficiency. This solves the problem in existing systems where, after adding gasified fine slag, large molten areas appear in the ash, encapsulating combustibles and hindering combustion. A booster fan provides the high-temperature, high-pressure primary air for atomization to the atomization device, eliminating the need for additional pre-drying of the gasified fine slag, reducing investment costs for drying equipment and steam costs.

[0029] The technical solution of the present invention will be further described below through specific embodiments. Unless otherwise specified, the methods described in the following embodiments are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0030] like Figure 1 A co-firing system for pulverized coal boilers that co-fires biomass and gasified fine slag includes a boiler 1, a raw coal conveying system, a biomass gasification conveying system, a gasified fine slag conveying system, a mixing device 11, a booster fan 16, and an atomizing device 17.

[0031] The inlet of the raw coal conveying system is connected to the first outlet of the primary air duct, and the outlet of the raw coal conveying system is connected to the first inlet of the mixing device 11; the outlet of the biomass gasification conveying system is connected to the second inlet of the mixing device 11, and the outlet of the mixing device 11 is connected to the burner on the boiler 1.

[0032] Specifically, the raw coal conveying system provides finely ground coal, the primary air duct provides primary air, and the biomass gasification conveying system provides gasified biomass. The primary air feeds the coal powder into the mixing device 11, and the gasified biomass mixes with the coal powder airflow in the mixing device 11.

[0033] The first inlet of the atomizing device 17 is connected to the gasification fine slag conveying system, the second inlet of the atomizing device 17 is connected to the outlet of the booster fan 16, the inlet of the booster fan 16 is connected to the second outlet of the primary air duct, and the outlet of the atomizing device 17 is connected to the secondary air inlet on the boiler 1.

[0034] Specifically, the gasified fine slag conveying system is used to provide the gasified fine slag; the atomizing device 17 is used to atomize the gasified fine slag to form atomized gasified fine slag. The booster fan 16 is used to provide the atomizing device 17 with high-temperature, high-pressure primary air for atomization. After entering the atomizing device 17, the high-temperature, high-pressure primary air atomizes the gasified fine slag in the atomizing device 17 to form atomized gasified fine slag. The atomized gasified fine slag is sent into the boiler 1 through the secondary air inlet at the upper part of the furnace. In this embodiment of the invention, the atomized gasified fine slag is fed into the boiler 1, where it forms combustion particles and is then burned. Because the atomized gasified fine slag is injected through a separately established secondary air nozzle, the mixing ratio of the gasified fine slag can be reduced, and the melting and agglomeration of the gasified fine slag can be effectively reduced, thus improving combustion efficiency. Furthermore, the gasified fine slag in this embodiment of the invention does not require additional pre-drying, reducing the investment cost of drying equipment and steam costs.

[0035] Based on the above embodiments, as a more preferred embodiment, the co-firing system includes a primary air fan 2 and an air preheater 3; the flue gas outlet of the boiler 1 is connected to a flue gas duct, the outlet of the flue gas duct is connected to the inlet of the air preheater 3, and the outlet of the air preheater 3 is connected to a flue gas treatment system. The inlet of the primary air duct is connected to the primary air fan 2, a portion of the primary air duct is coiled inside the air preheater 3, the first outlet of the primary air duct is connected to the inlet of the raw coal conveying system, and the second outlet of the primary air duct is connected to the inlet of the booster fan 16.

[0036] Specifically, the air preheater 3 is used to exchange heat and raise the temperature of the primary air in the primary air duct. After the primary air is heated by the air preheater 3, it enters the raw coal conveying system and the booster fan 16 through the primary air duct to dry the coal powder and atomize the gasification slag.

[0037] Based on the above embodiments, as a more preferred embodiment, the raw coal conveying system includes a raw coal bunker 4, a coal feeder 6, a conveying pipeline and a coal mill 7. The outlet of the raw coal bunker 4 is connected to the inlet of the coal feeder 6, the outlet of the coal feeder 6 is connected to the inlet end of the conveying pipeline, the outlet end of the conveying pipeline is connected to the inlet of the coal mill 7, and the outlet of the coal mill 7 is connected to the first inlet of the mixing device 11.

[0038] Specifically, the coal in the raw coal bunker 4 enters the pulverizing pipeline through the coal feeder 6, and then enters the coal mill 7 to grind the coal in the raw coal bunker 4. The finely ground coal powder then enters the mixing device 11.

[0039] Based on the above embodiments, as a more preferred embodiment, the biomass gasification conveying system includes a biomass gasification device 8 and a purification device 10. The outlet of the biomass gasification device 8 is connected to the inlet of the purification device 10, and the outlet of the purification device 10 is connected to the second inlet of the mixing device 11.

[0040] Specifically, the biomass gasification unit 8 is used to heat and gasify the input biomass to form fuel gas. The purification unit 10 is used to purify the fuel gas. Biomass enters the biomass gasification unit 8, where it is heated and gasified to form fuel gas. The fuel gas is then purified by the purification unit 10 to remove solid particles and water, effectively alleviating ash and slagging on the boiler's tail-end heating surface. The purified fuel gas is then fed into the mixing unit 11 to mix with finely ground coal powder. The mixture is then carried by primary air into the burner of the boiler 1 for co-combustion.

[0041] Specifically, the purification device 10 includes a dust removal device, a scrubbing tower, and a dryer, which are connected in sequence. The dust removal device is used to remove dust from the fuel gas to remove solid particles. The scrubbing tower is used to further purify the fuel gas. The dryer is used to dry the fuel gas. The purification device 10 of this embodiment can effectively remove solid particles and impurities such as water from the fuel gas, thereby effectively alleviating the ash accumulation and slagging on the boiler tail heating surface.

[0042] Based on the above embodiments, as a more preferred embodiment, the gasification fine slag conveying system includes a gasification fine slag storage bin 12, a positive pressure feeding device 14, and a paste pump 15. The outlet of the gasification fine slag storage bin 12 is connected to the inlet of the positive pressure feeding device 14, and the outlet of the positive pressure feeding device 14 is connected to the inlet of the paste pump 15; the outlet of the paste pump 15 is connected to the inlet of the atomizing device 17.

[0043] Specifically, the gasified fine slag storage silo 12 is used to provide gasified fine slag. The gasified fine slag enters the atomizing device 17 through the positive pressure feeding device 14 and the paste pump 15. The gasified fine slag in the atomizing device 17 is atomized by the high-temperature and high-pressure primary air used for atomization, and then sent into the secondary air nozzle of the boiler 1. In this embodiment of the invention, the gasified fine slag is connected to the primary air pipeline through the gasified fine slag conveying system, and then enters the boiler after atomization. It forms combustion particles in the boiler and then burns. Because the atomized gasified fine slag is injected into the secondary air nozzle separately, the mixing ratio of the gasified fine slag can be reduced, thereby effectively reducing the phenomenon of melting and agglomeration.

[0044] Based on the above embodiments, as a more preferred embodiment, the co-firing system includes a first control system 5, a second control system 9, and a third control system 13. The inlet of the first control system 5 is connected to the raw coal bunker 4, and the outlet of the first control system 5 is connected to the coal feeder 6. The inlet of the second control system 9 is connected to the biomass gasification device 8, and the outlet of the second control system 9 is connected to the purification device 10. The inlet of the third control system 13 is connected to the gasification slag storage bin 12, and the outlet of the third control system 13 is connected to the positive pressure feeding device 14. The positive pressure feeding device 14 is specifically a positive pressure feeder, which works in conjunction with the paste pump 15 to feed the gasified slag in the gasified slag storage bin 12 into the atomizing device 17.

[0045] Specifically, the first control system 5 is located between the raw coal bunker 4 and the coal feeder 6; the second control system 9 is located between the biomass gasification device 8 and the purification device 10; and the third control system 13 is located between the gasification slag storage silo 12 and the positive pressure feeding device 14. The first control system 5, the second control system 9, and the third control system 13 can adjust the blending ratio of coal, biomass, and gasification slag according to the required fuel blending ratio to meet the fuel requirements of the boiler combustion. Specifically, the first control system 5 includes a first control valve; the second control system 9 includes a second control valve; and the third control system 13 includes a third control valve. The first, second, and third control valves are respectively connected to a control module to adjust the flow rates of coal, biomass, and gasification slag, thereby adjusting the blending ratio of coal, biomass, and gasification slag.

[0046] The specific implementation operation of the co-firing system for biomass and gasified fine slag in pulverized coal boilers is as follows:

[0047] Raw coal enters the coal mill 7 via the coal feeder 6, and after grinding and drying, it enters the pulverized coal conveying pipeline. The biomass gasification unit 8 heats and gasifies the input biomass, which is then sent to the purification unit 10. The gasified biomass is mixed with the pulverized coal airflow in the mixing unit 11; then, under the action of primary air, it is sent into the burner of the boiler 1.

[0048] The gasified fine slag in the gasified fine slag storage bin 12 enters the atomizing device 17 through the positive pressure feeding device 14 and the paste pump 15. The high-temperature and high-pressure primary air used for atomization enters the atomizing device 17 through the booster fan 16, and then atomizes and dries the gasified fine slag. The atomized gasified fine slag is sent into the boiler 1 from the secondary air inlet at the top of the furnace. Under the action of high temperature, the surface loses water and hardens to form fuel particles, which then enter the combustion zone of the boiler 1 for combustion. By injecting the atomized gasified fine slag through a separate secondary air nozzle, the blending ratio of the gasified fine slag can be reduced, thereby effectively reducing the phenomenon of melting and agglomeration.

[0049] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A co-firing system for pulverized coal boilers, comprising co-firing biomass and gasified fine slag, characterized in that, It includes a boiler (1), a raw coal conveying system, a biomass gasification conveying system, a gasification fine slag conveying system, a mixing device (11), a booster fan (16), and an atomizing device (17); The boiler (1) has a burner and a secondary air inlet; The inlet of the mixing device (11) is connected to the raw coal conveying system and the biomass gasification conveying system respectively, and the outlet of the mixing device (11) is connected to the burner of the boiler (1). The inlet of the atomizing device (17) is connected to the gasification fine slag conveying system and the booster fan (16) respectively, and the outlet of the atomizing device (17) is connected to the secondary air inlet of the boiler (1).

2. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 1, characterized in that, It also includes a primary air duct, the first outlet of which is connected to the inlet of the raw coal conveying system, and the second outlet of which is connected to the inlet of the booster fan (16).

3. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 2, characterized in that, The co-firing system includes an air preheater (3), the flue gas outlet of the boiler (1) is connected to a flue gas duct, and the outlet of the flue gas duct is connected to the inlet of the air preheater (3). A portion of the primary air duct is coiled inside the air preheater (3) and configured to exchange heat and raise the temperature of the primary air inside the primary air duct.

4. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 2, characterized in that, The raw coal conveying system includes a coal mill (7), the first outlet of the primary air duct is connected to the inlet of the coal mill (7), and the outlet of the coal mill (7) is connected to the mixing device (11).

5. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 4, characterized in that, The raw coal conveying system includes a raw coal bunker (4), a coal feeder (6), and a conveying pipeline. The outlet of the raw coal bunker (4) is connected to the inlet of the coal feeder (6), the outlet of the coal feeder (6) is connected to the inlet end of the conveying pipeline, the outlet end of the conveying pipeline is connected to the inlet of the coal mill (7), and the outlet of the coal mill (7) is connected to the first inlet of the mixing device (11).

6. The co-firing system for pulverized coal boilers using biomass and gasified fine slag according to claim 5, characterized in that, The co-firing system includes a first control system (5), the inlet of which is connected to the raw coal bunker (4), and the outlet of which is connected to the coal feeder (6).

7. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 1, characterized in that, The biomass gasification and conveying system includes a biomass gasification device (8) and a purification device (10). The outlet of the biomass gasification device (8) is connected to the inlet of the purification device (10), and the outlet of the purification device (10) is connected to the second inlet of the mixing device (11).

8. The co-firing system for pulverized coal boilers using biomass and gasified fine slag according to claim 7, characterized in that, The co-firing system includes a second control system (9), the inlet of which is connected to the biomass gasification device (8), and the outlet of which is connected to the purification device (10).

9. The co-firing system for pulverized coal boilers using biomass and gasified fine slag as described in claim 1, characterized in that, The gasified fine slag conveying system includes a gasified fine slag storage bin (12), a positive pressure feeding device (14), and a paste pump (15); the outlet of the gasified fine slag storage bin (12) is connected to the inlet of the positive pressure feeding device (14), the outlet of the positive pressure feeding device (14) is connected to the inlet of the paste pump (15), and the outlet of the paste pump (15) is connected to the inlet of the atomizing device (17).

10. The co-firing system for pulverized coal boilers using biomass and gasified fine slag according to claim 9, characterized in that, The co-firing system includes a third control system (13), the inlet of which is connected to the gasification fine slag storage bin (12), and the outlet of which is connected to the positive pressure feeding device (14).

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