Biomass boiler flue gas deep treatment and waste heat cascade deep utilization system

Abstract

The utility model discloses a biomass boiler flue gas deep treatment and waste heat cascade deep utilization system which comprises an air blower and a boiler, one side of the boiler is connected with a dust remover, the side face of the dust remover is communicated with an induced draft fan, and a port of the induced draft fan is connected with a flue gas deep purification and waste heat utilization tower. The surface of the flue gas deep purification and waste heat utilization tower is respectively communicated with a high-temperature waste heat water pump and a flue gas purification circulating water pump; the output end of the high-temperature waste heat water pump is connected with a heat supply network water plate type heat exchanger. In order to solve the current problems that HCL gas is contained in smoke of a biomass boiler, the smoke exhaust loss of the boiler is large, an air pre-heater is corroded at low temperature and dust accumulation is serious and the like, a plurality of key new technical achievements such as a smoke grading treatment system and a waste heat grading utilization system are adopted, so that efficient HCL removal treatment of high-temperature smoke, gradient deep utilization of waste heat and the like are realized; and the discharge amount of pollutants and water vapor in flue gas is effectively reduced, the efficiency of the boiler is improved, and the energy-saving and environment-friendly integrated effect is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy conservation and environmental protection, and particularly relates to a system for deep treatment of flue gas of a biomass boiler and cascade deep utilization of waste heat. Background Technique

[0002] The emissions of harmful gases from biomass boilers are relatively clean, but SO2 gas and HCL gas can still be monitored in the exhaust gas after combustion. Moreover, the emission amount of HCL gas is much higher than that of coal combustion, mainly because the chlorine content in biomass is high. These emissions are prone to react with potassium in biomass to form aerosols, polluting the air.

[0003] The heat loss in the combustion of biomass boilers is mainly the flue gas heat loss. A large amount of flue gas heat is discharged through the chimney, greatly reducing the efficiency of biomass boilers. The reason for the flue gas heat loss is that the water content of biomass fuel is much higher than that of biomass boilers. After the biomass fuel with high water content enters the furnace, higher drying temperature and longer drying time are required to reduce the water content. The higher the water content, the lower the low calorific value of biomass. Therefore, when burning biomass fuel with high water content, the temperature field in the furnace is relatively low and it is difficult to burn. More water also increases the flue gas volume and the heat loss of exhaust gas.

[0004] Low-temperature corrosion mainly occurs at the cold section of the air preheater, and the most serious part is the cold air inlet end. The chlorine content and alkali metal content in biomass fuel are both high. Under the action of high temperature in the furnace, part of the chlorine in the fuel reacts chemically with alkali metal salts and exists in the form of gaseous HCL. When the metal wall temperature of the air preheater tube is lower than the flue gas acid dew point, the hydrochloric acid formed by chlorides will become the main cause of low-temperature corrosion. Content of the Utility Model

[0005] Therefore, the purpose of the utility model is to provide a system for deep treatment of flue gas of a biomass boiler and cascade deep utilization of waste heat. Aiming at the problems existing in the current biomass boilers, such as HCL gas in the flue gas, large boiler exhaust losses, serious low-temperature corrosion and ash accumulation of the air preheater, etc., a variety of key new technical achievements such as a flue gas grading treatment system and a waste heat grading utilization system are adopted to achieve efficient HCL removal treatment of high-temperature flue gas, cascade deep utilization of waste heat, etc., effectively reducing the emissions of pollutants and water vapor in the flue gas, improving the efficiency of the boiler and achieving the integrated effect of energy conservation and environmental protection.

[0006] To solve the above technical problems, according to one aspect of the present utility model, the present utility model provides the following technical solution: A system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat, comprising a blower and a boiler. One side of the boiler is connected to a dust collector, and the side of the dust collector is communicated with an induced draft fan. The port of the induced draft fan is connected to a flue gas deep purification and waste heat utilization tower, and the surface of the flue gas deep purification and waste heat utilization tower is respectively communicated with a high-temperature waste heat water pump and a flue gas purification circulating water pump;

[0007] The output end of the high-temperature waste heat water pump is connected to a heat network water plate heat exchanger, and the output end of the flue gas purification circulating water pump is connected to an air heater. The input end of the heat network water plate heat exchanger is communicated with a heat network water circulating pump, and the output end of the heat network water circulating pump is connected to a heat pump condenser. A heat pump evaporator is arranged at the position of the heat pump condenser.

[0008] As a preferred scheme of the system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat according to the present utility model, a chimney is communicated with the top end of the flue gas deep purification and waste heat utilization tower.

[0009] As a preferred scheme of the system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat according to the present utility model, it further comprises a desalting water pump, and the output end of the desalting water pump is connected to a desalting water heating plate heat exchanger.

[0010] As a preferred scheme of the system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat according to the present utility model, it further comprises a heat network make-up water pump, and the output end of the heat network make-up water pump is connected to a heat network make-up water heating plate heat exchanger.

[0011] As a preferred scheme of the system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat according to the present utility model, a spray layer, a water separation layer, and a packing layer are arranged inside the flue gas deep purification and waste heat utilization tower.

[0012] As a preferred scheme of the system for deep treatment of flue gas from a biomass boiler and cascaded deep utilization of waste heat according to the present utility model, the spray layer, the water separation layer, and the packing layer are vertically distributed.

[0013] Compared with the prior art, the advantages of the present utility model are as follows:

[0014] In view of the current problems existing in biomass boilers, such as HCL gas in the flue gas, large boiler exhaust losses, serious low-temperature corrosion and ash accumulation in the air preheater, etc., a variety of key new technological achievements, such as a flue gas grading treatment system and a waste heat utilization system with different grades of energy, are adopted to achieve efficient HCL removal from high-temperature flue gas, cascade deep utilization of waste heat, etc., effectively reducing the emissions of pollutants and water vapor in the flue gas, and improving the boiler efficiency to achieve the integrated effect of energy conservation and environmental protection. Brief Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the drawings and specific embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0016] Figure 1 is the structural diagram of the present invention.

[0017] In the figure: 1, blower; 2, boiler; 3, dust collector; 4, induced draft fan; 5, flue gas deep purification and waste heat utilization tower; 6, high-temperature surplus hot water pump; 7, flue gas purification circulating water pump; 8, heat network water plate heat exchanger; 9, air heater; 10, heat network water circulating pump; 11, chimney; 12, heat pump condenser; 13, heat pump evaporator; 14, desalted water heating plate heat exchanger; 15, heat network make-up water heating plate heat exchanger; 16, desalted water pump; 17, heat network make-up water pump. Detailed Embodiments

[0018] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below with reference to the drawings.

[0019] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0020] Secondly, the present invention is described in detail with reference to the schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the cross-sectional views showing the device structure will be enlarged locally out of the general proportion, and the schematic diagrams are only examples and should not limit the scope of protection of the present invention herein. In addition, in actual production, three-dimensional spatial dimensions including length, width and depth should be included.

[0021] In order to make the purpose, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the drawings.

[0022] The utility model provides a system for deep treatment of flue gas and cascaded deep utilization of waste heat in a biomass boiler. Aiming at the problems existing in the current biomass boiler, such as HCL gas in the flue gas, large heat loss of boiler exhaust, serious low-temperature corrosion and ash accumulation in the air preheater, etc., a variety of key new technical achievements, such as a flue gas grading treatment system and a waste heat utilization system by grade of heat quality, are adopted to achieve efficient HCL removal from high-temperature flue gas, cascaded deep utilization of waste heat, etc., effectively reducing the emissions of pollutants and water vapor in the flue gas, and improving the efficiency of the boiler to achieve the integrated effect of energy conservation and environmental protection.

[0023] Figure 1 Shown is a schematic diagram of the overall structure of an embodiment of a system for deep treatment of flue gas and cascaded deep utilization of waste heat in a biomass boiler of the utility model. Please refer to Figure 1 In this embodiment, the main structure includes a blower 1 and a boiler 2. One side of the boiler 2 is connected to a dust collector 3, and the side of the dust collector 3 is communicated with an induced draft fan 4. The port of the induced draft fan 4 is connected to a flue gas deep purification and waste heat utilization tower 5. The surface of the flue gas deep purification and waste heat utilization tower 5 is respectively communicated with a high-temperature surplus hot water pump 6 and a flue gas purification circulating water pump 7;

[0024] The output end of the high-temperature surplus hot water pump 6 is connected to a heat network water plate heat exchanger 8, and the output end of the flue gas purification circulating water pump 7 is connected to an air heater 9. The input end of the heat network water plate heat exchanger 8 is communicated with a heat network water circulating pump 10. The output end of the heat network water circulating pump 10 is connected to a heat pump condenser 12. A heat pump evaporator 13 is arranged at the position of the heat pump condenser 12;

[0025] It also includes a desalting water pump 16, and the output end of the desalting water pump 16 is connected to a desalted water heating plate heat exchanger 14;

[0026] It also includes a heat network make-up water pump 17, and the output end of the heat network make-up water pump 17 is connected to a heat network make-up water heating plate heat exchanger 15;

[0027] In specific use, for a 75t / h biomass boiler, the flue gas temperature at the outlet of the dust collector is 120°C, the flue gas flow rate is 190,000 m³ / h, the combustion-supporting air flow rate is 9,000 m³ / h, and the average outdoor ambient temperature is -0.8°C. The flue gas first enters the flue gas deep purification and waste heat utilization tower 5. Inside the flue gas deep purification and waste heat utilization tower 5, the flue gas first passes through the flue gas spray purification layer. Approximately 400 t / h of flue gas purification circulating water sprays the flue gas, reducing the flue gas temperature to about 65°C. The temperature of the flue gas purification circulating water rises to 60°C. The 60°C flue gas purification circulating water is transported by the flue gas purification circulating water pump 7 to the air heater 9 to heat the combustion-supporting air for the boiler, raising the air temperature from -0.8°C to 30°C. The heat consumed by the air is 1 MW. The heated combustion-supporting air is sent into the boiler through the blower 1. At this time, the temperature of the 400 t / h flue gas purification circulating water drops from 60°C to about 58°C and then enters the flue gas spray purification layer for spraying.

[0028] After being purified by the spray purification layer, the flue gas temperature drops to about 65°C and then enters the high-temperature waste heat recovery section of the flue gas deep purification and waste heat utilization tower 5. Approximately 600 t / h of high-temperature waste hot water at 38°C sprays the flue gas for the second time to cool it down, reducing the flue gas temperature to 43°C. The temperature of the high-temperature waste hot water rises from 38°C to 49°C. The 49°C high-temperature waste hot water is transported by the high-temperature waste hot water pump 6 to the heat network water plate heat exchanger 8 to exchange heat with the heat network water, heating the heat network water transported by the heat network water circulation pump 10 from 35°C to 46°C. A part of the waste hot water that has dropped to 38°C returns to the high-temperature waste heat recovery section of the flue gas deep purification and waste heat utilization tower 5 to spray and cool the flue gas, reducing the flue gas temperature to 43°C. Another part of the 38°C waste hot water enters the demineralized water heating plate heat exchanger 14 and the heat network make-up water heating plate heat exchanger 15 respectively to heat the heat network make-up water and demineralized water. Due to the large fluctuations in the flow rates of the heat network make-up water and demineralized water, the temperature of the waste hot water fluctuates greatly. To stabilize the temperature of the waste hot water, the waste hot water after heat exchange in the demineralized water heating plate heat exchanger 14 and the heat network make-up water heating plate heat exchanger 15 converges and then enters the heat pump evaporator 13 to reduce the temperature of the waste hot water to about 15°C. The cold source of the heat pump condenser 12 is the heat network return water transported by the heat network water circulation pump 10.

[0029] The 43°C flue gas enters the deep waste heat recovery section of the flue gas deep purification and waste heat utilization tower 5, and the flue gas is deeply cooled by the 15°C waste hot water, finally reducing the flue gas temperature to about 25°C, and then being discharged to the atmosphere through the chimney 11.

[0030] Although the present utility model has been described above with reference to the embodiments, various improvements can be made to it and components thereof can be replaced with equivalents without departing from the scope of the present utility model. In particular, as long as there is no structural conflict, the features in the embodiments disclosed by the present utility model can be combined with each other in any way, and the exhaustive description of these combinations is not given in this specification only for the consideration of saving space and resources. Therefore, the present utility model is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system, comprising a blower (1) and a boiler (2), characterized in that: A dust collector (3) is connected to one side of the boiler (2), and an induced draft fan (4) is connected to the side of the dust collector (3); a port of the induced draft fan (4) is connected to a flue gas deep purification and waste heat utilization tower (5); and a high-temperature waste heat water pump (6) and a flue gas purification circulating water pump (7) are respectively connected to the surface of the flue gas deep purification and waste heat utilization tower (5); The output end of the high-temperature waste heat water pump (6) is connected to a heat network water plate heat exchanger (8), and the output end of the flue gas purification circulating water pump (7) is connected to an air heater (9). The input end of the heat network water plate heat exchanger (8) is connected to a heat network water circulating pump (10), and the output end of the heat network water circulating pump (10) is connected to a heat pump condenser (12). A heat pump evaporator (13) is arranged at the position of the heat pump condenser (12).

2. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system according to claim 1, characterized in that: The top of the flue gas deep purification and waste heat utilization tower (5) is connected to a chimney (11).

3. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system according to claim 2, characterized in that: It also includes a desalted water pump (16), the output end of the desalted water pump (16) being connected to a desalted water heating plate exchanger (14).

4. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system according to claim 3, characterized in that: It also includes a heating network water replenishment pump (17), the output end of the heating network water replenishment pump (17) being connected to the heating network water replenishment heating plate exchanger (15).

5. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system according to claim 4, characterized in that: The flue gas deep purification and waste heat utilization tower (5) is provided with a spray layer, a water separation layer and a packing layer inside.

6. A biomass boiler flue gas deep treatment and waste heat cascade deep utilization system according to claim 5, characterized in that: The spray layer, the water distribution layer and the filler layer are distributed vertically.

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