A system for eliminating smoke plume and utilizing waste heat from flue gas

Abstract

The present invention discloses a flue gas waste heat utilization system for eliminating smoke plumes, comprising an air preheater, a first heat exchanger, a dust collector, a desulfurization tower and a chimney, wherein the flue gas from the boiler enters the air preheater, the air preheater is connected to the atmosphere, the flue gas is used to preheat the air entering the air preheater, the flue gas outlet of the air preheater is connected to the flue gas inlet of the first heat exchanger, the flue gas entering the first heat exchanger exchanges heat with the water entering the first heat exchanger, the flue gas outlet of the first heat exchanger is connected to the flue gas inlet of the dust collector, the flue gas outlet of the dust collector is connected to the flue gas inlet of the desulfurization tower, the flue gas outlet of the desulfurization tower is connected to the flue gas inlet of the chimney through a first pipeline, and an eighth valve is provided on the first pipeline. The beneficial effects of the present invention are: maximally saving the waste heat energy of flue gas, truly achieving the effects of energy saving, emission reduction and elimination of visual pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of desulfurization, environmental protection and comprehensive energy utilization, and specifically relates to a system for eliminating smoke plume and utilizing waste heat of flue gas. Background Art

[0002] At present, in order to meet the ultra-low emission requirements, most domestic thermal power plants use wet desulfurization devices to treat flue gas. Wet desulfurization devices can significantly remove SO 2 At the same time, it has a certain capture effect on particles with a diameter of 1-2.5um or more in the flue gas. The flue gas at the outlet of the wet flue gas desulfurization device is generally saturated wet flue gas at 45-55℃. After being discharged from the chimney, it mixes with the low-temperature air in the environment. During the mixing process, water vapor may condense and precipitate, and white-gray wet smoke plumes can be seen, commonly known as "white smoke". The appearance of wet smoke plumes causes visual pollution. At the same time, the high-humidity flue gas rises and forms water droplets when it is cooled, which will also affect the lives of residents around the power plant.

[0003] The source of white smoke plume is water. Saturated water vapor in flue gas is generated by absorbing heat and contains a large amount of latent heat. Therefore, the key to eliminating white smoke is to control the temperature and humidity of the discharged flue gas. When water absorbs heat and rises to a certain temperature, it will turn into water vapor. When the heat in the water vapor is removed and its temperature is lowered to the condensation temperature, the steam condenses into water. This is a reversible process that is commonly found in nature.

[0004] Part of the water vapor in wet flue gas comes from combustion and process, and part comes from wet desulfurization and dust removal and water evaporation. The key to wet flue gas deoxidation is to control the absolute humidity and relative humidity of exhaust gas as low as possible or change the state of water vapor. At present, the flue gas deoxidation technologies for coal-fired power plants mainly include flue gas heating, flue gas condensation, and flue gas condensation reheating. The flue gas heating technology heats the saturated wet flue gas to make the flue gas state away from the saturated humidity curve, achieve wet smoke plume elimination, and improve the flue gas diffusion effect. The flue gas condensation technology reduces the flue gas temperature, cools the flue gas along the saturated humidity curve, and recovers the supersaturated water vapor in the flue gas to reduce the absolute humidity of the flue gas. Using the flue gas condensation cooling method, the critical cooling amplitude decreases linearly with the increase of ambient temperature and increases with the increase of ambient humidity.

[0005] Tan Houzhang, Liu Xing, Wang Wenhui, et al. Research on technical routes of flue gas desulfurization under ultra-low emission background [J]. Clean Coal Technology, 2019, 25(2): 38-44. Note: The outlet of the wet flue gas desulfurization unit is generally saturated wet flue gas at 45-55℃. When the outlet flue gas temperature of the device is 50℃, it can be directly discharged without visible wet plume when the ambient temperature is above 34.4-40.4℃. For hot and dry areas, direct discharge of saturated wet flue gas in summer can achieve wet plume-free operation.

[0006] Flue gas heating technology eliminates wet smoke plumes, and the flue gas temperature rise amplitude decreases with the increase of ambient temperature. When the ambient temperature is lower than 11°C, the flue gas temperature rise amplitude must reach more than 30°C to eliminate the wet smoke plume; when the ambient temperature is higher than 16°C, the flue gas temperature rise amplitude can be eliminated if it is below 30°C. Using the flue gas condensation cooling method, the cooling amplitude decreases linearly with the increase of ambient temperature. At low temperatures (5°C), the cooling amplitude is large, reaching 32.0-36.8°C; at high temperatures (25°C), the cooling amplitude is small, reaching 10.52-15.73°C. Using the flue gas condensation reheating method, the cooling amplitude and temperature rise amplitude required to eliminate wet smoke plumes are lower than those using heating or condensation technology alone; the use of condensation reheating can broaden the scope of application of wet smoke plume elimination and can be applied to ambient temperatures below zero. Summary of the invention

[0007] In view of the deficiencies in the prior art, an object of the present invention is to provide a system for eliminating smoke plume and utilizing waste heat of flue gas.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A system for eliminating smoke plume and utilizing flue gas waste heat, characterized in that it comprises an air preheater, a first heat exchanger, a dust collector, a desulfurization tower and a chimney;

[0010] Flue gas from the boiler enters the air preheater,

[0011] The air preheater is connected to the atmosphere, and the flue gas is used to preheat the air entering the air preheater.

[0012] The flue gas outlet of the air preheater is connected to the flue gas inlet of the first heat exchanger, and the flue gas entering the first heat exchanger exchanges heat with the water entering the first heat exchanger.

[0013] The flue gas outlet of the first heat exchanger is connected to the flue gas inlet of the dust collector,

[0014] The flue gas outlet of the dust collector is connected to the flue gas inlet of the desulfurization tower.

[0015] The flue gas outlet of the desulfurization tower is connected to the flue gas inlet of the chimney through a first pipeline, and an eighth valve 1.8 is arranged on the first pipeline.

[0016] Furthermore, the said system for eliminating smoke plume and utilizing waste heat of flue gas also includes a spray-type direct contact heat exchanger and a lithium bromide refrigerator;

[0017] The flue gas inlet of the spray type direct contact heat exchanger is connected with the flue gas outlet of the desulfurization tower, and the flue gas outlet of the spray type direct contact heat exchanger is connected with the first pipeline through the second pipeline to form a first connection point, and the second pipeline is provided with a ninth valve 1.9, and the first connection point is located on the pipeline connecting the eighth valve 1.8 and the chimney;

[0018] A sixth valve 1.6 is provided on the pipeline connecting the flue gas inlet of the spray type direct contact heat exchanger and the flue gas outlet of the desulfurization tower;

[0019] The cooling water inlet of the lithium bromide refrigerator is connected to the water outlet of the spray type direct contact heat exchanger, the cooling water outlet of the lithium bromide refrigerator is connected to the water inlet of the spray type direct contact heat exchanger, and a tenth valve 1.10 is provided on the pipeline connecting the water inlet of the spray type direct contact heat exchanger and the cooling water outlet of the lithium bromide refrigerator;

[0020] Feedwater reheating is the process of extracting part of the steam that has done work from certain intermediate stages of the steam turbine and sending it to the reheat heater to heat the boiler feed water. The corresponding thermodynamic cycle is called the reheat cycle.

[0021] The role of heat recovery heating: it increases the boiler feed water temperature, increases the average heat absorption temperature of the working fluid in the boiler, improves thermal economy, and the heat recovery exhaust air does not enter the condenser to release heat, which reduces the condensing gas flow rate of the turbine, reduces the cold source loss, and improves the absolute internal efficiency of the turbine.

[0022] The circulating water inlet of the first heat exchanger is connected to the evaporator outlet of the lithium bromide refrigerator, and the circulating water outlet of the first heat exchanger is connected to the evaporator inlet of the lithium bromide refrigerator; the 16th valve 1.16 is provided on the pipeline connecting the circulating water inlet of the first heat exchanger and the evaporator outlet of the lithium bromide refrigerator, and the 15th valve 1.15 is provided on the pipeline connecting the circulating water outlet of the first heat exchanger and the evaporator inlet of the lithium bromide refrigerator.

[0023] Furthermore, the smoke plume elimination and flue gas waste heat utilization system further includes a second heat exchanger and an air mixing heater;

[0024] The smoke inlet of the second heat exchanger is connected to the second pipe through the third pipe, and a second connection point is formed. The second connection point is located on the pipe between the ninth valve 1.9 and the smoke outlet of the spray type direct contact heat exchanger. The seventh valve 1.7 is provided on the third pipe. The seventh valve 1.7 is connected to any part of the smoke inlet pipe of the second heat exchanger, and the fourth pipe is extended to the first pipe to form a third connection point. The seventh valve 1.7 is provided on the fourth pipe.

[0025] The smoke outlet of the second heat exchanger is connected to the smoke inlet of the air mixing heater, and the smoke outlet of the air mixing heater is connected to the smoke inlet of the chimney; a fourteenth valve 1.14 is provided on the pipe connecting the smoke outlet of the air mixing heater and the smoke inlet of the chimney;

[0026] The air inlet of the air preheater is connected to the atmosphere, the air outlet of the air preheater is connected to the air inlet of the air mixing heater, and a first valve 1.1 is provided on the pipeline connecting the air inlet of the air preheater and the atmosphere;

[0027] The circulating water inlet of the first heat exchanger is connected with the circulating water outlet of the second heat exchanger, and the circulating water outlet of the first heat exchanger is connected with the circulating water inlet of the second heat exchanger. A fourth valve 1.4 is provided on the pipe connecting the circulating water inlet of the first heat exchanger and the circulating water outlet of the second heat exchanger, and a third valve 1.3 is provided on the pipe connecting the circulating water outlet of the first heat exchanger and the circulating water inlet of the second heat exchanger.

[0028] Furthermore, any part of the pipe connecting the smoke outlet of the second heat exchanger and the smoke inlet of the air mixing heater extends out of a fifth pipe to the first pipe and forms a fourth connecting point; the first connecting point, the third connecting point and the fourth connecting point are located on the pipe connecting the 8th valve 1.8 and the chimney, and the first connecting point, the third connecting point and the fourth connecting point are successively arranged away from the 8th valve 1.8, and the 18th valve 1.18 is arranged on the pipe between the third connecting point and the fourth connecting point; the 19th valve 1.19 is arranged on the fifth pipe.

[0029] Preferably, it also includes a heat recovery system for improving turbine efficiency and energy utilization. An opening is provided on the pipe connecting the water outlet of the spray-type direct contact heat exchanger and the cooling water inlet of the lithium bromide refrigerator. The opening is connected to the heat recovery system. A 13th valve 1.13 is provided on the pipe connecting the opening and the heat recovery system.

[0030] Preferably, it also includes a fifth valve 1.5 and a second valve 1.2 for controlling water supply and return of the heating network between heat users, the circulating water inlet of the first heat exchanger is connected with the water outlet of the heat user, and the circulating water outlet of the first heat exchanger is connected with the water inlet of the heat user to supply hot water to the heat user, and the fifth valve 1.5 is provided on the pipe connecting the circulating water inlet of the first heat exchanger and the water outlet of the heat user, and the second valve 1.2 is provided on the pipe connecting the circulating water outlet of the first heat exchanger and the water inlet of the heat user.

[0031] Preferably, it also includes an 11th valve 1.11 and a 12th valve 1.12 for controlling the flow of cooling capacity between the cold user, the cooling water inlet of the lithium bromide refrigerator is connected to the water outlet of the cold user, the cooling water outlet of the lithium bromide refrigerator is connected to the water inlet of the cold user, the 12th valve 1.12 is provided on the pipeline connecting the cooling water inlet of the lithium bromide refrigerator and the water outlet of the cold user, and the 11th valve 1.11 is provided on the pipeline connecting the cooling water outlet of the lithium bromide refrigerator and the water inlet of the cold user.

[0032] In the method for using the flue gas waste heat utilization system for eliminating smoke plumes as described above, when the ambient temperature is above 34.4-40.4°C, the 8th valve 1.8 and the 18th valve 1.18 are opened, and the remaining valves are closed; the flue gas coming out of the boiler is processed by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower in sequence, and then discharged into the atmosphere through the chimney. After the above treatment, no white smoke appears at the chimney outlet.

[0033] When the flue gas outlet temperature of the desulfurization tower is above 45℃ and the ambient temperature is above 34.4-40.4℃, it can be discharged directly without visible wet plume. For high temperature and dry areas, direct discharge of saturated wet flue gas in summer can achieve wet plume-free operation. At this time, the 8th valve 1.8 and 1.18 are opened, and the other valves are closed. The flue gas comes out of the boiler, passes through the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, and the flue gas comes out of the desulfurization tower to the chimney and is directly discharged into the atmosphere.

[0034] In the method of using the flue gas waste heat utilization system for eliminating smoke plumes as described above, when the ambient temperature is 25-34.4°C, open the 6th valve 1.6, the 9th valve 1.9, the 18th valve 1.18, the 10th valve 1.10, the 15th valve 1.15, and the 16th valve 1.16, and close the remaining valves; the flue gas coming out of the boiler is processed in sequence by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower, and then enters the spray-type direct contact heat exchanger for spray cooling. The cooled flue gas enters the chimney and is directly discharged into the atmosphere. After the above treatment, no white smoke appears at the chimney outlet.

[0035] The circulating water in the lithium bromide refrigerator exchanges heat with the flue gas of the first heat exchanger to reduce the flue gas temperature. The lithium bromide refrigerator performs cooling. The cooling water enters the spray-type direct contact heat exchanger to spray the flue gas. The cooling water is treated and then returns to the lithium bromide refrigerator.

[0036] Preferably, when refrigeration is needed, the 11th valve 1.11 and the 12th valve 1.12 are opened; the lithium bromide refrigerator supplies the heated water to the refrigerator for refrigeration, and supplies the refrigeration capacity to the cold user.

[0037] The flue gas comes out of the boiler, passes through the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, and enters the spray-type direct contact heat exchanger for spray cooling. The cooled flue gas enters the chimney and is directly discharged into the atmosphere; the flue gas passes through the first heat exchanger to heat the circulating water in the lithium bromide refrigerator, the temperature of the flue gas is reduced, the lithium bromide refrigerator is cooled, and the cooling water enters the spray-type direct contact heat exchanger to spray the flue gas, condense the water vapor in the flue gas, and remove some pollutants at the same time. The condensed water is treated and returned to the lithium bromide refrigerator, and the rest goes to the heat recovery system to improve the efficiency of the turbine and improve energy utilization.

[0038] In the method for using the system for eliminating smoke plume and utilizing waste heat of flue gas as described above, when the ambient temperature is 16-25° C., the first valve 1.1, the third valve 1.3, the fourth valve 1.4, the eighth valve 1.8, the seventeenth valve 1.17, and the fourteenth valve 1.14 are opened, and the remaining valves are closed;

[0039] The flue gas coming out of the boiler is processed in sequence by the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, the second heat exchanger, the air mixing heater, and enters the chimney to be discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet.

[0040] Preferably, if the heating period is handled, the second valve 1.2 and the fifth valve 1.5 are opened, and the first heat exchanger heats the circulating water of the heating network and supplies it to the heat users.

[0041] The flue gas comes out of the boiler, passes through the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, the second heat exchanger, the air mixing heater, and enters the chimney and is discharged into the atmosphere. The flue gas heats the air in the air preheater, the flue gas releases heat, and the temperature of the flue gas decreases. In the first heat exchanger, the circulating water is heated, the flue gas temperature further decreases, the flue gas flow volume becomes smaller, and the fly ash resistivity is correspondingly reduced, thereby greatly improving the working performance of the dust collector. Under the same dust removal efficiency conditions, the dust collector design can adopt a smaller dust collector specification, less energy consumption, and a smaller footprint. The hot circulating water heats the flue gas coming out of the desulfurization tower in the second heat exchanger. After the heated flue gas comes out of the second heat exchanger, it goes to the air mixing heater and mixes with the hot air coming out of the air preheater to be heated again, and then discharged from the chimney to the atmosphere. The flue gas is heated by hot water and hot air in stages to reduce the heat transfer temperature difference and reduce energy loss. If it is in the heating period, while the flue gas heating technology eliminates the wet smoke plume, the second valve 1.2 and the fifth valve 1.5 are opened, and the first heat exchanger heats the circulating water of the heating network to supply heat users. At the same time, part of the circulating water of the heating network is used to heat the flue gas coming out of the desulfurization tower.

[0042] In the method for using the system for eliminating smoke plume and utilizing waste heat of flue gas as described above, when the ambient temperature is not greater than 16°C, the first valve 1.1, the sixth valve 1.6, the ninth valve 1.9, the tenth valve 1.10, the thirteenth valve 1.13, the fifteenth valve 1.15, the sixteenth valve 1.16, the fourteenth valve 1.14, the eighteenth valve 1.18, and the nineteenth valve 1.19 are opened, and the remaining valves are closed;

[0043] The flue gas coming out of the boiler is processed in sequence by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower, and then enters the spray-type direct contact heat exchanger for spray cooling, and then enters the air mixing heat exchanger and the chimney to be discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet.

[0044] The flue gas comes out of the boiler, passes through the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, and enters the spray type direct contact heat exchanger, sprays to cool down, and then enters the air mixing heater and enters the chimney to be discharged into the atmosphere. The flue gas heats the air in the air preheater and heats the circulating water in the first heat exchanger; the flue gas coming out of the desulfurization tower is condensed in the spray type direct contact heat exchanger, and the condensed flue gas enters the air mixing heater and mixes with the hot air coming out of the air preheater to be heated, and then discharged into the atmosphere from the chimney. The circulating water heated in the hot first heat exchanger enters the lithium bromide refrigerator, and the prepared cooling water enters the spray type direct contact heat exchanger to remove water vapor and pollutants in the flue gas. The water vapor in the flue gas condenses into water, and the condensed water returns to the lithium bromide refrigerator after treatment, and the rest goes to the heat recovery system to improve the efficiency of the turbine and improve energy utilization. The flue gas comes out of the spray type direct contact heat exchanger, enters the air mixing heater, mixes with the hot air and heats it, and then enters the chimney to be discharged into the atmosphere.

[0045] Preferably, the flue gas temperature at the flue gas outlet of the desulfurization tower is above 45°C, above 50°C, or above 55°C.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] This system can solve the smoke plume phenomenon that occurs during flue gas emission at different ambient temperatures; it can use the flue gas direct emission method to deal with the flue gas emission when the flue gas temperature of the desulfurization tower is above 45°C and the ambient temperature is above 34.4-40.4°C; it can use the flue gas condensation cooling method to deal with the flue gas emission when the flue gas temperature of the desulfurization tower is above 45°C and the ambient temperature is 25-34.4°C; it can use the flue gas heating technology to deal with the flue gas emission when the flue gas temperature of the desulfurization tower is above 45°C and the ambient temperature is 16-25°C; it can use the flue gas condensation reheating technology to deal with the flue gas emission when the flue gas temperature of the desulfurization tower is above 45°C and the ambient temperature is below 16°C; it can eliminate the energy consumed by eliminating wet smoke plumes at different ambient temperatures. At the same time, different technical solutions are adopted: condensation technology is used to dehumidify the smoke plume, and the waste heat of the flue gas is used to drive the lithium bromide refrigerator to condense the water vapor in the flue gas; the flue gas heating technology is used to dehumidify the smoke plume, and the waste heat of the flue gas is used to heat the air and circulating water respectively, and the hot water and hot air are used to heat the flue gas in stages, which reduces the heat exchange temperature difference and reduces energy loss; the technology of first condensing and then heating the flue gas to dehumidify the smoke plume can make full use of the waste heat of the flue gas, reduce the energy required for dehumidifying the smoke plume, and save the waste heat energy of the flue gas to the maximum extent, which can truly achieve energy saving, emission reduction and elimination of visual pollution. At the same time, the heating and cooling systems are introduced into the flue gas waste heat utilization system to fully utilize the waste heat of the flue gas, eliminate wet smoke plumes and reduce environmental pollution.

[0048] In addition, the system for eliminating smoke plume and flue gas waste heat described in the present invention can also determine the method of eliminating wet smoke plumes according to the actual needs of heating and cooling; for example, during the heating period, if there is surplus waste heat, the heating plume removal scheme can be selected, and during the cooling period, if there is surplus cooling, the condensation plume removal scheme can be selected, that is, the flue gas waste heat is fully utilized to eliminate wet smoke plumes and reduce environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic structural diagram of a first embodiment of a system for eliminating smoke plume and utilizing flue gas waste heat according to the present invention;

[0050] Figure 2 This is a schematic structural diagram of a second embodiment of a system for eliminating smoke plume and utilizing waste heat of flue gas according to the present invention;

[0051] Figure 3 This is a schematic structural diagram of a third embodiment of a system for eliminating smoke plume and utilizing flue gas waste heat according to the present invention;

[0052] Figure 4 This is a schematic structural diagram of a fourth embodiment of a system for eliminating smoke plume and utilizing flue gas waste heat according to the present invention;

[0053] Figure 5 This is a flow chart of a system for eliminating smoke plume and utilizing waste heat of flue gas according to the present invention;

[0054] In the figure:

[0055] 1- boiler, 2- air preheater, 3- first heat exchanger, 4- dust collector,

[0056] 5- desulfurization tower, 6- spray direct contact heat exchanger, 7- lithium bromide refrigerator, 8-cold user, 9-second heat exchanger, 10, air mixing heater, 11, chimney,

[0057] 1.1-1st valve, 1.2-2nd valve, 1.3-3rd valve, 1.4-4th valve,

[0058] 1.5-5th valve, 1.6-6th valve, 1.7-7th valve, 1.8-8th valve,

[0059] 1.9-9th valve, 1.10-10th valve, 1.11-11th valve, 1.12-12th valve,

[0060] 1.13-13th valve, 1.14-14th valve, 1.15-15th valve, 1.16-16th valve,

[0061] 1.17-17th valve, 1.18-18th valve, 1.19-19th valve. DETAILED DESCRIPTION

[0062] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0063] The detailed description and technical contents of the present invention are described as follows with reference to the accompanying drawings:

[0064] Please refer to Figure 1 and Figure 5 , Figure 1 This is a schematic diagram of the structure of the first embodiment of a system for eliminating smoke plume and utilizing waste heat of flue gas according to the present invention. Figure 1 As shown, when the flue gas outlet temperature of the desulfurization tower 5 is above 45°C and the ambient temperature is above 34.4-40.4°C, open the 8th valve 1.8 and the 18th valve 1.18 (for details, refer to Figure 5), close the other valves; the flue gas from the boiler 1 is processed by the air preheater 2, the first heat exchanger 3, the dust collector 4, and the desulfurization tower 5 in turn, and then discharged into the atmosphere through the chimney 11; when the flue gas temperature at the outlet of the desulfurization tower is above 45°C and the ambient temperature is above 34.4-40.4°C, it can be directly discharged without visible wet plume. For high-temperature and dry areas, direct discharge of saturated wet flue gas in summer can achieve wet plume-free operation. At this time, the eighth valve 1.8 and 1.18 are opened, and the other valves are closed. The flue gas comes out of the boiler 1, passes through the air preheater 2, the first heat exchanger 3, the dust collector 4, and the desulfurization tower 5. The flue gas comes out of the desulfurization tower 5 to the chimney 11 and is directly discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet.

[0065] Please refer to Figure 2 and Figure 5 , Figure 2 This is a schematic diagram of the structure of the second embodiment of the smoke plume elimination and flue gas waste heat utilization system of the present invention. Figure 2 As shown: when the flue gas outlet temperature of the desulfurization tower 5 is above 45°C (for example, 50°C) and the ambient temperature is 25-34.4°C, open the 6th valve 1.6, the 9th valve 1.9, the 18th valve 1.18, the 10th valve 1.10, the 15th valve 1.15 and the 16th valve 1.16, and close the remaining valves; the flue gas coming out of the boiler 1 is processed by the air preheater 2, the first heat exchanger 3, the dust collector 4 and the desulfurization tower 5 in sequence, and then enters the spray-type direct contact heat exchanger 6 for spray cooling. The cooled flue gas enters the chimney 11 and is directly discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet; the circulating water in the lithium bromide refrigerator 7 exchanges heat with the flue gas of the first heat exchanger 3 to reduce the flue gas temperature, the lithium bromide refrigerator 7 cools, the cooling water enters the spray-type direct contact heat exchanger 6 to spray the flue gas, and the cooling water passes through The flue gas is processed and then returns to the lithium bromide refrigerator 7; the flue gas comes out of the boiler 1, passes through the air preheater 2, the first heat exchanger 3, the dust collector 4, the desulfurization tower 5, and enters the spray-type direct contact heat exchanger 6 for spray cooling. The cooled flue gas enters the chimney 11 and is directly discharged into the atmosphere; the flue gas passes through the first heat exchanger 3 to heat the circulating water in the lithium bromide refrigerator 7, the temperature of the flue gas is reduced, the lithium bromide refrigerator 7 is refrigerated, and the cooling water enters the spray-type direct contact heat exchanger 6 to spray the flue gas, condense the water vapor in the flue gas, and remove part of the pollutants at the same time. The condensed water is processed and then returns to the lithium bromide refrigerator 7, and the rest is sent to the heat recovery system to improve the efficiency of the turbine and the energy utilization rate; when refrigeration is needed, the 11th valve 1.11 and the 12th valve 1.12 are opened; the lithium bromide refrigerator 7 supplies the heated water to the refrigerator for refrigeration, and supplies the cooling capacity to the cold user 8.

[0066] Please refer to Figure 3 and Figure 5 , Figure 3This is a schematic diagram of the structure of the third embodiment of the flue gas waste heat utilization system for eliminating smoke plumes according to the present invention. When the flue gas outlet temperature of the desulfurization tower 5 is above 45°C (for example, 50°C) and the ambient temperature is 16-25°C, the first valve 1.1, the third valve 1.3, the fourth valve 1.4, the eighth valve 1.8, the seventeenth valve 1.17, and the fourteenth valve 1.14 are opened, and the remaining valves are closed;

[0067] The flue gas from the boiler 1 is processed in sequence by the air preheater 2, the first heat exchanger 3, the dust collector 4, the desulfurization tower 5, the second heat exchanger 9, the air mixing heater 10, and enters the chimney 11 to be discharged into the atmosphere;

[0068] The flue gas comes out of the boiler 1, passes through the air preheater 2, the first heat exchanger 3, the dust collector 4, the desulfurization tower 5, the second heat exchanger 9, the air mixing heater 10, and enters the chimney 11 to be discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet. The flue gas heats the air in the air preheater 2, the flue gas releases heat, and the temperature of the flue gas decreases. In the first heat exchanger 3, the circulating water is heated, the flue gas temperature further decreases, the flue gas flow volume becomes smaller, and the fly ash resistivity is correspondingly reduced, thereby greatly improving the working performance of the dust collector 4. Under the same dust removal efficiency conditions, the dust collector 4 can be designed with a smaller dust collector 4 specification, less energy consumption, and a smaller footprint. The hot circulating water heats the flue gas coming out of the desulfurization tower 5 in the second heat exchanger 9. After the heated flue gas comes out of the second heat exchanger 9, it goes to the air mixing heater 10 and mixes with the hot air coming out of the air preheater 2 to be heated again, and then discharged from the chimney 11 to the atmosphere. The flue gas is heated by hot water and hot air in stages, reducing the heat transfer temperature difference and energy loss. If it is in the heating period, while the flue gas heating technology eliminates the wet smoke plume, the second valve 1.2 and the fifth valve 1.5 are opened, and the first heat exchanger 3 heats the circulating water of the heat network and supplies it to the heat users. At the same time, part of the circulating water of the heat network is used to heat the flue gas coming out of the desulfurization tower 5.

[0069] Please refer to Figure 4 and Figure 5 , Figure 4 This is a schematic diagram of the structure of the fourth embodiment of the flue gas waste heat utilization system for eliminating smoke plumes according to the present invention. When the flue gas outlet temperature of the desulfurization tower 5 is above 45°C (for example, 50°C) and the ambient temperature is not greater than 16°C, open the first valve 1.1, the sixth valve 1.6, the ninth valve 1.9, the tenth valve 1.10, the thirteenth valve 1.13, the fifteenth valve 1.15, the sixteenth valve 1.16, the fourteenth valve 1.14, the eighteenth valve 1.18, and the nineteenth valve 1.19, and close the remaining valves;

[0070] The flue gas coming out of the boiler 1 is processed in sequence by the air preheater 2, the first heat exchanger 3, the dust collector 4, and the desulfurization tower 5, and then enters the spray type direct contact heat exchanger 6 for spray cooling, and then enters the air mixing heat exchanger and enters the chimney 11 to be discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet.

[0071] The flue gas comes out of the boiler 1, passes through the air preheater 2, the first heat exchanger 3, the dust collector 4, the desulfurization tower 5, enters the spray type direct contact heat exchanger 6, sprays to cool down, then enters the air mixing heater 10, enters the chimney 11 and is discharged into the atmosphere. The flue gas heats the air in the air preheater 2, and heats the circulating water in the first heat exchanger 3; the flue gas coming out of the desulfurization tower 5 is condensed in the spray type direct contact heat exchanger 6, and the condensed flue gas enters the air mixing heater 10 and is mixed with the hot air coming out of the air preheater 2 to be heated, and then is discharged into the atmosphere from the chimney 11. The circulating water heated in the hot first heat exchanger 3 enters the lithium bromide refrigerator 7, and the prepared cooling water enters the spray type direct contact heat exchanger 6 to remove water vapor and pollutants in the flue gas. The water vapor in the flue gas condenses into water, and the condensed water returns to the lithium bromide refrigerator 7 after treatment, and the rest goes to the heat recovery system to improve the efficiency of the steam turbine and the energy utilization rate. The flue gas comes out of the spray type direct contact heat exchanger 6, enters the air mixing heater 10, is mixed with the hot air and heated, and then enters the chimney 11 and is discharged into the atmosphere.

[0072] It is known from common technical knowledge that the present invention can be implemented by other embodiments that do not deviate from its spirit or essential features. Therefore, the above disclosed embodiments are only illustrative in all respects and are not exclusive. All changes within the scope of the present invention or within the scope equivalent to the present invention are included in the present invention.

Claims

1. A method for using a system for eliminating smoke plume and utilizing waste heat from flue gas, characterized in that: It includes air preheater, first heat exchanger, dust collector, desulfurization tower and chimney; Flue gas from the boiler enters the air preheater, The air preheater is connected to the atmosphere, and the flue gas is used to preheat the air entering the air preheater. The flue gas outlet of the air preheater is connected to the flue gas inlet of the first heat exchanger, and the flue gas entering the first heat exchanger exchanges heat with the water entering the first heat exchanger. The flue gas outlet of the first heat exchanger is connected to the flue gas inlet of the dust collector, The flue gas outlet of the dust collector is connected to the flue gas inlet of the desulfurization tower. The flue gas outlet of the desulfurization tower is connected to the flue gas inlet of the chimney through a first pipe, and an eighth valve (1.8) is provided on the first pipe; It also includes spray-type direct contact heat exchangers and lithium bromide refrigerators; The flue gas inlet of the spray type direct contact heat exchanger is connected to the flue gas outlet of the desulfurization tower, and the flue gas outlet of the spray type direct contact heat exchanger is connected to the first pipeline through the second pipeline to form a first connection point, and the second pipeline is provided with a ninth valve (1.9), and the first connection point is located on the pipeline connecting the eighth valve (1.8) and the chimney; A sixth valve (1.6) is provided on the pipeline connecting the flue gas inlet of the spray type direct contact heat exchanger and the flue gas outlet of the desulfurization tower; The cooling water inlet of the lithium bromide refrigerator is connected to the water outlet of the spray type direct contact heat exchanger, the cooling water outlet of the lithium bromide refrigerator is connected to the water inlet of the spray type direct contact heat exchanger, and a tenth valve (1.10) is provided on the pipeline connecting the water inlet of the spray type direct contact heat exchanger and the cooling water outlet of the lithium bromide refrigerator; The circulating water inlet of the first heat exchanger is connected to the evaporator outlet of the lithium bromide refrigerator, and the circulating water outlet of the first heat exchanger is connected to the evaporator inlet of the lithium bromide refrigerator; a 16th valve (1.16) is provided on the pipeline connecting the circulating water inlet of the first heat exchanger and the evaporator outlet of the lithium bromide refrigerator, and a 15th valve (1.15) is provided on the pipeline connecting the circulating water outlet of the first heat exchanger and the evaporator inlet of the lithium bromide refrigerator; Also included is a second heat exchanger and an air mixing heater; The smoke inlet of the second heat exchanger is connected to the second pipe through the third pipe to form a second connection point, the second connection point is located on the pipe between the ninth valve (1.9) and the smoke outlet of the spray type direct contact heat exchanger, and the seventh valve (1.7) is arranged on the third pipe; the seventh valve (1.7) is connected to any part of the smoke inlet pipe of the second heat exchanger, and the fourth pipe is extended to the first pipe to form a third connection point, and the fourth pipe is provided with a seventeenth valve (1.17); The smoke outlet of the second heat exchanger is connected to the smoke inlet of the air mixing heater, and the smoke outlet of the air mixing heater is connected to the smoke inlet of the chimney; a 14th valve (1.14) is provided on the pipe connecting the smoke outlet of the air mixing heater and the smoke inlet of the chimney; The air inlet of the air preheater is connected to the atmosphere, the air outlet of the air preheater is connected to the air inlet of the air mixing heater, and a first valve (1.1) is provided on the pipeline connecting the air inlet of the air preheater and the atmosphere; The circulating water inlet of the first heat exchanger is connected to the circulating water outlet of the second heat exchanger, the circulating water outlet of the first heat exchanger is connected to the circulating water inlet of the second heat exchanger, a fourth valve (1.4) is provided on the pipeline connecting the circulating water inlet of the first heat exchanger and the circulating water outlet of the second heat exchanger, and a third valve (1.3) is provided on the pipeline connecting the circulating water outlet of the first heat exchanger and the circulating water inlet of the second heat exchanger; Any part of the pipeline connecting the smoke outlet of the second heat exchanger and the smoke inlet of the air mixing heater extends out of a fifth pipeline to the first pipeline, and forms a fourth connection point; the first connection point, the third connection point and the fourth connection point are located on the pipeline connecting the eighth valve (1.8) and the chimney, and the first connection point, the third connection point and the fourth connection point are arranged away from the eighth valve (1.8) in sequence, and the pipeline between the third connection point and the fourth connection point is provided with an eighteenth valve (1.18); the fifth pipeline is provided with a nineteenth valve (1.19); The method of use includes: When the ambient temperature is greater than 34.4℃, open the 8th valve (1.8) and the 18th valve (1.18), and close the other valves; the flue gas from the boiler is processed by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower in sequence, and then discharged into the atmosphere through the chimney. After the above treatment, there is no white smoke at the chimney outlet; When the ambient temperature is greater than 25°C and less than 34.4°C, open the 6th valve (1.6), the 9th valve (1.9), the 18th valve (1.18), the 10th valve (1.10), the 13th valve (1.13), the 15th valve (1.15), and the 16th valve (1.16), and close the remaining valves; the flue gas from the boiler is processed by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower in turn, and then enters the spray-type direct contact heat exchanger for spray cooling. The cooled flue gas enters the chimney and is directly discharged into the atmosphere. After the above treatment, no white smoke appears at the chimney outlet; The circulating water in the lithium bromide refrigerator exchanges heat with the flue gas of the first heat exchanger to reduce the flue gas temperature. The lithium bromide refrigerator performs cooling. The cooling water enters the spray-type direct contact heat exchanger to spray the flue gas. The cooling water is treated and then returns to the lithium bromide refrigerator. When the ambient temperature is greater than 16°C and less than 25°C, open the first valve (1.1), the third valve (1.3), the fourth valve (1.4), the eighth valve (1.8), the seventeenth valve (1.17), and the fourteenth valve (1.14), and close the remaining valves; The flue gas from the boiler is processed in sequence by the air preheater, the first heat exchanger, the dust collector, the desulfurization tower, the second heat exchanger, the air mixing heater, and then enters the chimney and is discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet; When the ambient temperature is not greater than 16°C, open the 1st valve (1.1), the 6th valve (1.6), the 9th valve (1.9), the 10th valve (1.10), the 13th valve (1.13), the 15th valve (1.15), the 16th valve (1.16), the 14th valve (1.14), the 18th valve (1.18), and the 19th valve (1.19), and close the remaining valves; The flue gas coming out of the boiler is processed in sequence by the air preheater, the first heat exchanger, the dust collector, and the desulfurization tower, and then enters the spray-type direct contact heat exchanger for spray cooling, and then enters the air mixing heat exchanger and the chimney to be discharged into the atmosphere. After the above treatment, there is no white smoke at the chimney outlet.

2. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas according to claim 1, characterized in that: It also includes a heat recovery system for improving turbine efficiency and energy utilization. An opening is provided on a pipe connecting the water outlet of the spray-type direct contact heat exchanger and the cooling water inlet of the lithium bromide refrigerator. The opening is connected to the heat recovery system. A 13th valve (1.13) is provided on the pipe connecting the opening and the heat recovery system.

3. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas according to claim 1, characterized in that: It also includes a fifth valve (1.5) and a second valve (1.2) for controlling water supply and return of the heating network between the heat user and the heat user; the circulating water inlet of the first heat exchanger is connected to the water outlet of the heat user; the circulating water outlet of the first heat exchanger is connected to the water inlet of the heat user to supply hot water to the heat user; the fifth valve (1.5) is arranged on the pipe connecting the circulating water inlet of the first heat exchanger and the water outlet of the heat user; and the second valve (1.2) is arranged on the pipe connecting the circulating water outlet of the first heat exchanger and the water inlet of the heat user.

4. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas according to claim 1 is characterized in that: It also includes an 11th valve (1.11) and a 12th valve (1.12) for controlling the flow of cooling capacity between the cold user and the cold user. The cooling water inlet of the lithium bromide refrigerator is connected to the water outlet of the cold user, and the cooling water outlet of the lithium bromide refrigerator is connected to the water inlet of the cold user. The 12th valve (1.12) is arranged on the pipeline connecting the cooling water inlet of the lithium bromide refrigerator and the water outlet of the cold user, and the 11th valve (1.11) is arranged on the pipeline connecting the cooling water outlet of the lithium bromide refrigerator and the water inlet of the cold user.

5. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas as claimed in claim 4 is characterized in that: When refrigeration is required, open the 11th valve (1.11), the 12th valve (1.12), the 15th valve (1.15), and the 16th valve (1.16); The circulating water in the lithium bromide refrigerator exchanges heat with the flue gas of the first heat exchanger to reduce the flue gas temperature. The lithium bromide refrigerator supplies the heated water to the refrigerator for refrigeration, and supplies the cooling capacity to cold users.

6. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas as claimed in claim 4, characterized in that: When cooling is needed, the 11th valve (1.11) and the 12th valve (1.12) are opened; the lithium bromide refrigerator supplies heated water to the refrigerator for cooling, and supplies the cooling capacity to the cold users.

7. The method for using the system for eliminating smoke plume and utilizing waste heat of flue gas as claimed in claim 3 is characterized in that: If it is the heating period, the second valve (1.2) and the fifth valve (1.5) are opened, and the first heat exchanger heats the circulating water of the heating network and supplies it to the heat users.

8. A method for using a system for eliminating smoke plume and utilizing waste heat of flue gas according to any one of claims 5 to 7, characterized in that: The flue gas temperature at the desulfurization tower outlet is above 45°C.

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