Coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system

Abstract

The utility model provides a flue gas waste heat indirect recovery and desulfurization water balance system for a coal-fired power plant. The system comprises a flue gas desulfurization system, a slurry heat exchanger and a cooling water circulation system, the output end of the flue gas desulfurization system is connected with a first inlet of the slurry heat exchanger, and a first outlet of the slurry heat exchanger is connected with the input end of the flue gas desulfurization system; a second inlet of the slurry heat exchanger is connected with the output end of the cooling water circulation system, a second outlet of the slurry heat exchanger is connected with the input end of the cooling water circulation system, and the tail end of the second inlet cooling water circulation system is arranged in a heating water pump room. And the returned water and supplemented circulating water of the heating water pump room are conveyed into the slurry heat exchanger through the booster pump. The system recovers and utilizes the waste heat of the slurry in the absorption tower of the desulfurization system of the coal-fired power plant, greatly reduces the energy consumption, and reduces the energy consumption cost.

Description

Technical Field

[0001] This utility model relates to the field of indirect recovery of waste heat from flue gas in coal-fired power plants, and in particular to an indirect recovery and desulfurization water balance system for waste heat from flue gas in coal-fired power plants. Background Technology

[0002] The flue gas emitted by coal-fired power plants during power generation is generally above 110℃. Some of the heat is absorbed by the slurry spray of the desulfurization system absorption tower and enters the slurry. The heat of the existing slurry is mostly ignored or directly discharged, which not only causes a huge waste of energy, but also has an adverse impact on the environment. Utility Model Content

[0003] To address the aforementioned technical problems, a system for indirect recovery of waste heat from flue gas in coal-fired power plants and for desulfurization water balance is provided. The technical means employed in this invention are as follows:

[0004] A flue gas waste heat indirect recovery and desulfurization water balance system for coal-fired power plants includes a flue gas desulfurization system, a slurry heat exchanger, and a cooling water circulation system. The output end of the flue gas desulfurization system is connected to the first inlet of the slurry heat exchanger, the first outlet of the slurry heat exchanger is connected to the input end of the flue gas desulfurization system, the output end of the second inlet cooling water circulation system is connected to the second inlet of the slurry heat exchanger, and the second outlet of the slurry heat exchanger is connected to the input end of the cooling water circulation system. The end of the second inlet cooling water circulation system is located in a heating water pump house. The circulating water after returning and replenishing the heating water pump house is transported to the slurry heat exchanger by a booster pump.

[0005] Furthermore, the flue gas desulfurization system includes a desulfurization tower, an induced draft fan connected to the input end of the desulfurization tower, a slurry spraying system installed inside the desulfurization tower, a first inlet of the slurry heat exchanger connected to the bottom of the desulfurization tower, and a first outlet of the slurry heat exchanger connected to the upper part of the desulfurization tower and connected to the slurry spraying system.

[0006] Furthermore, the flue gas output end of the desulfurization tower is connected to the chimney.

[0007] Furthermore, the pipeline between the second outlet of the slurry heat exchanger and the main pipeline of the heating water pump room serves as the main heating water pipeline, and system branch pipelines are also connected to it. A first valve is installed on the pipeline connecting the system branch pipeline and the main heating water pipeline.

[0008] Furthermore, a water collection pit is provided on the pipeline between the output end pipeline of the heating water pump room and the second inlet of the slurry heat exchanger, and the booster pump is provided on the pipeline between the water collection pit and the second inlet of the slurry heat exchanger.

[0009] Furthermore, the water source for the heating water pump room also includes a heating water return pipe, one branch of which is directly connected to a sump. The output pipe of the heating water pump room is connected to the sump. A fourth valve is installed on the pipe connecting the heating water return pipe to the sump, and a fifth valve is installed on the pipe connecting the output pipe of the heating water pump room to the sump.

[0010] Furthermore, the pipeline flowing into the sump also includes at least one system branch pipeline, and a sixth valve is installed between the system branch pipeline and the pipeline flowing into the sump.

[0011] This invention has the following advantages: It recovers and utilizes the waste heat from the slurry in the desulfurization system of a coal-fired power plant, significantly reducing energy consumption and costs, as well as environmental pollution, thus providing significant economic and environmental benefits. This waste heat can be recycled and reused to meet heating and industrial heating needs. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a system diagram of the present utility model.

[0014] Figure 2 This is a system diagram of Embodiment 2 of the present utility model.

[0015] In the diagram: 1. Exhaust fan; 2. Desulfurization tower; 3. Chimney; 4. Slurry heat exchanger; 5. Slurry circulation pump; 6. System branch pipeline; 7. First valve; 8. Second valve; 9. Heating water pump room; 10. Third valve; 11. Fourth valve; 12. Fifth valve; 13. Sump; 14. Water supply system; 15. Sixth valve; 16. Seventh valve; 17. Boiler pump; 18. Flue gas heat exchanger; 19. Boiler feedwater source; 20. Deaerator to boiler system; 21. Boiler. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0017] like Figure 1 As shown in the figure, this utility model embodiment discloses an indirect recovery and desulfurization water balance system for waste heat from flue gas in a coal-fired power plant, including a flue gas desulfurization system, a slurry heat exchanger 4, and a cooling water circulation system. The output end of the flue gas desulfurization system is connected to the first inlet of the slurry heat exchanger, the first outlet of the slurry heat exchanger is connected to the input end of the flue gas desulfurization system, the output end of the second inlet cooling water circulation system of the slurry heat exchanger is connected, and the second outlet of the slurry heat exchanger is connected to the input end of the cooling water circulation system. The end of the second inlet cooling water circulation system is located in a heating water pump room 9. A second valve 8 is installed on this pipeline to control the flow rate of water entering the heating water pump room. During normal use, this valve is a normally open valve. The circulating water after returning water and replenishing water from the heating water pump room is transported to the slurry heat exchanger by a booster pump 17.

[0018] Furthermore, the flue gas desulfurization system includes a desulfurization tower 2, an induced draft fan 1 connected to the input end of the desulfurization tower, a slurry spraying system installed inside the desulfurization tower, a first inlet of the slurry heat exchanger connected to the bottom of the desulfurization tower, a slurry circulation pump 5 installed between the desulfurization tower and the first inlet of the slurry heat exchanger, and a first outlet of the slurry heat exchanger connected to the upper part of the desulfurization tower and connected to the slurry spraying system.

[0019] In this embodiment, the slurry heat exchanger can be a plate heat exchanger.

[0020] The second inlet of the slurry heat exchanger is located above the heat exchanger, and the second outlet is located below the heat exchanger. As an optional implementation, in this application, a slurry heat exchanger is used for heat exchange. During the circulation process, the slurry temperature drops, resulting in a reduction in the evaporation rate inside the desulfurization tower and making it difficult to control the liquid level. The circulation rate is controlled by adjusting the output of the slurry circulation pump 5.

[0021] Furthermore, the flue gas output end of the desulfurization tower is connected to the chimney 3.

[0022] Furthermore, the pipeline between the second outlet of the slurry heat exchanger and the main pipeline of the heating water pump room serves as the main heating water pipeline, to which system branch pipelines 6 are connected. A first valve 7 is installed on the pipeline connecting the system branch pipeline and the main heating water pipeline. The system branch pipelines specifically constitute the return water system of each unit. The number of return water pipelines varies depending on the unit. Of course, a check valve is installed at the front end and / or rear end of the first valve 7 to prevent water that has undergone heat exchange in the slurry heat exchanger from flowing back into the unit.

[0023] Furthermore, a sump 13 is installed on the pipeline between the output end of the heating water pump room and the second inlet of the slurry heat exchanger, and the booster pump is installed on the pipeline between the sump and the second inlet of the slurry heat exchanger. The sump can also be connected to other pipelines (not shown in the figure) besides this system, and can be adjusted according to the actual production situation, such as the plant demister flushing or limestone slurry preparation pipeline, as part of the water recycling.

[0024] Furthermore, the water source for the heating water pump room also includes a heating water return pipe, and a third valve 10 is installed on the heating water return pipe. The third valve has a preset opening degree in normal state, and the third valve adjusts the return water flow based on the water flow in the heating water pump room.

[0025] One branch of the heating water return pipeline is directly connected to the sump, and the output pipeline of the heating water pump house is also connected to the sump. A fourth valve 11 is installed on the pipeline connecting the heating water return pipeline and the sump, and a fifth valve 12 is installed on the pipeline connecting the output pipeline of the heating water pump house and the sump. The output water flow of the heating water pump house is regulated by the fourth valve 11 and the fifth valve 12. When the water in the sump is used excessively by other systems, such as the aforementioned plant demister flushing or the limestone slurry preparation pipeline in a short period of time, the opening of the fourth valve 11 is increased to replenish the system water in real time.

[0026] Furthermore, the pipeline flowing into the sump also includes at least one system branch pipeline, with a sixth valve 15 installed between the system branch pipeline and the pipeline flowing into the sump. The system branch pipeline mentioned here is an additional water supply system 14, such as the condensate system outlet water from the unit's chimney and flue, mechanical seal water from branch lines, paddle circulation pumps, agitators, etc., and cooling water for the oxidation blower bearings. This water itself has a certain flow rate and a relatively high overall cleanliness, and will not cause significant pollution to the pipeline. Under normal circumstances, this water is discharged. Collecting this water through the sump also enables the reuse of water resources.

[0027] Of course, at least one valve should be installed before and after the booster pump, such as the seventh valve 16 shown in the figure, to ensure that the water output of the system is limited during unit maintenance.

[0028] As an optional implementation method, such as Figure 2 As shown, improvements can also be made to the pipeline between the desulfurization tower and the chimney by installing a flue gas heat exchanger 18 to further utilize the waste heat of the flue gas. The flue gas heat exchanger is a plate flue gas heat exchanger or a shell and tube flue gas heat exchanger. The water source for heating is the boiler feed water source 19. The heated water source is supplemented to the deaerator-to-boiler system 20, and then water with a certain amount of heat enters the boiler 21. Of course, valves can be installed on the pipeline in the above system as needed.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A flue gas waste heat indirect recovery and desulphurization water balance system for coal fired power plants, characterized in that, The system comprises a flue gas desulfurization system, a slurry heat exchanger and a cooling water circulation system, the output end of the flue gas desulfurization system is connected with the first inlet of the slurry heat exchanger, the first outlet of the slurry heat exchanger is connected with the input end of the flue gas desulfurization system, the second inlet of the slurry heat exchanger is connected with the output end of the cooling water circulation system, the second outlet of the slurry heat exchanger is connected with the input end of the cooling water circulation system, the end of the second inlet cooling water circulation system is arranged in the heating water pump house, and the circulating water after passing through the heating water pump house and supplement is transported to the slurry heat exchanger through the booster pump.

2. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system according to claim 1, characterized in that, The flue gas desulfurization system comprises a desulfurization tower, the input end of the desulfurization tower is connected with an induced draft fan, the inside of the desulfurization tower is provided with a slurry spraying system, the first inlet of the slurry heat exchanger is connected at the bottom of the desulfurization tower, and the first outlet of the slurry heat exchanger is connected at the upper part of the desulfurization tower and connected with the slurry spraying system.

3. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system according to claim 2, characterized in that, The flue gas output end of the desulfurization tower is connected with a chimney.

4. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system according to claim 1, characterized in that, The pipeline between the second outlet of the slurry heat exchanger and the main pipeline of the heating water pump house is used as the main pipeline of the heating water, and a system branch pipeline is further connected on the pipeline.

5. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system of claim 1, wherein, The pipeline between the output end pipeline of the heating water pump house and the second inlet of the slurry heat exchanger is provided with a sump, and the booster pump is arranged on the pipeline between the sump and the second inlet of the slurry heat exchanger.

6. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system according to claim 5, characterized in that, The water source of the heating water pump house further comprises a heating water return pipeline, one branch of the heating water return pipeline is directly connected with the sump, the output end pipeline of the heating water pump house is connected with the sump, the fourth valve is arranged on the pipeline between the heating water return pipeline and the sump, and the fifth valve is arranged on the pipeline between the output end pipeline of the heating water pump house and the sump.

7. The coal-fired power plant flue gas waste heat indirect recovery and desulfurization water balance system according to claim 6, characterized in that, The pipeline into the sump further comprises at least one system branch pipeline, and the sixth valve is arranged between the system branch pipeline and the pipeline into the sump.

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