Cold start-up water supply system for circulating fluidized bed boilers in power plants

Abstract

This invention relates to a cold start-up water supply system for a circulating fluidized bed boiler in a power plant. It is applicable to the field of thermal power plant design technology. The technical solution adopted in this invention is: a cold start-up water supply system for a circulating fluidized bed boiler in a power plant, characterized by having a condensate storage tank, a fixed discharge collection tank, and a periodic blowdown expansion tank. The condensate storage tank is connected to the fixed discharge collection tank via pipelines and a condensate transfer pump and a check valve II sequentially installed on the pipelines. The fixed discharge collection tank is connected to the drain pipes of the boiler water-cooled wall via pipelines. The fixed discharge collection tank is also connected to the periodic blowdown expansion tank via pipelines and an electrically operated shut-off valve on the pipelines.

Description

Technical Field

[0001] This invention relates to a cold start-up water supply system for a circulating fluidized bed boiler in a power plant. It is applicable to the field of thermal power plant design technology. Background Technology

[0002] Circulating fluidized bed (CFB) boilers employ fluidized bed combustion and their main structure comprises two parts: the combustion chamber and the circulating furnace. In a conventional CFB boiler cold start-up, water from the condensate storage tank is pumped through the boiler feedwater pipeline to the high-pressure feedwater pipeline before the economizer inlet via the condensate transfer pump. After passing through the high-pressure feedwater pipeline, the water enters the boiler to complete the feedwater supply. After the feedwater supply is complete, the detachable short pipes in the feedwater system are removed to isolate the high-pressure feedwater system from the condensate system. This prevents high-pressure feedwater from entering the lower-pressure condensate system due to leaks in valves or other components in the feedwater pipeline, which could cause overpressure and other accidents in the condensate system.

[0003] Because circulating fluidized bed boilers start and stop relatively frequently, they need to be fed water to the boiler frequently. This causes operators to frequently disassemble and reassemble the detachable short pipes of the water supply pipeline. Since the pressure of the high-pressure water supply system is high, if the valves or plugs on the high-pressure water supply side leak, it can easily lead to personal safety accidents. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a cold start-up water supply system for a circulating fluidized bed boiler in a power plant, in view of the above-mentioned problems.

[0005] The technical solution adopted in this invention is: a cold start water supply system for a circulating fluidized bed boiler in a power plant, characterized in that: it has a condensate storage tank, a fixed discharge collection tank, and a periodic blowdown expansion tank, wherein the condensate storage tank is connected to the fixed discharge collection tank via pipelines and a condensate delivery pump and a check valve II installed sequentially on the pipelines, the fixed discharge collection tank is connected to the drain pipes of the boiler water-cooled wall via pipelines, and the fixed discharge collection tank is also connected to the periodic blowdown expansion tank via pipelines and an electric shut-off valve on the pipelines.

[0006] The pipeline between the condensate storage tank and the fixed discharge collection tank is sequentially equipped with a manual gate valve I, a filter screen, the condensate delivery pump, a check valve I, a manual gate valve I, a flange assembly, a manual stop valve I, a manual stop valve II, and the check valve II.

[0007] The pipeline between check valve I and manual gate valve I is connected to the condensate storage tank via a circulation pipeline and a manual shut-off valve III, a throttling orifice plate, and a manual shut-off valve IV installed on the circulation pipeline.

[0008] The condensate storage tank is connected to the condenser hot well via a bypass pipeline and a check valve III and a manual gate valve III installed on the bypass pipeline.

[0009] The pipeline between the manual gate valve II and the flange assembly is connected to the condenser hot well via a branch line; the bypass pipeline is connected in parallel to the branch line and the condensate storage tank.

[0010] The beneficial effects of this invention are as follows: In this invention, the condensate storage tank is pumped into the fixed discharge collection tank by the condensate transfer pump, and then enters the boiler water-cooled wall through the drain pipe of the boiler water-cooled wall, and then enters the boiler steam drum through the water-cooled wall to complete the water supply; this avoids the connection between the boiler water supply system and the high-pressure feedwater system, improves the safety of the entire system, and avoids safety production accidents caused by leakage of the high-pressure feedwater system.

[0011] After the boiler is filled with water, this invention eliminates the need to remove the water supply pipes, thus reducing the workload of daily operation and maintenance personnel.

[0012] In this invention, the regular drainage collection box receives condensate from the drainage pipes of each boiler water-cooled wall during normal boiler operation, and enters the periodic blowdown expansion container through the shut-off valve and the electric shut-off valve. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of an embodiment.

[0014] 1. Condensate storage tank; 2. Manual gate valve I; 3. Filter screen; 4. Condensate transfer pump; 5. Check valve I; 6. Manual gate valve II; 7. Flange assembly; 8. Manual stop valve I; 9. Manual stop valve II; 10. Check valve II; 11. Manual stop valve III; 12. Orifice plate; 13. Manual stop valve IV; 14. Check valve III; 15. Manual gate valve III; 16. Stop valve; 17. Electric stop valve; 18. Regular drain collection box; 19. Drainage pipes of boiler water-cooled walls; 20. Condenser hot well; 21. Periodic blowdown expansion tank. Detailed Implementation

[0015] This embodiment describes a cold start-up water supply system for a circulating fluidized bed boiler in a power plant, which includes a condensate storage tank, a periodic blowdown collection tank, and a periodic blowdown expansion tank.

[0016] In this example, the condensate storage tank is connected to the condenser hot well via pipeline I and a manual gate valve I, a filter screen, the condensate delivery pump, check valve I, and manual gate valve II, which are sequentially installed on pipeline I.

[0017] In this embodiment, a pipe 2 is connected to pipe 1 between manual gate valve 2 and condenser hot well. Pipe 2 is provided with flange assembly, manual stop valve 1, manual stop valve 2 and check valve 2 in sequence, and is connected to the fixed drain collection box through pipe 2. The fixed drain collection box is connected to the drain pipe of boiler water-cooled wall.

[0018] In this embodiment, a pipeline 3 is connected to pipeline 2 between the fixed discharge collection box and check valve 2. A shut-off valve and an electric shut-off valve are sequentially installed on pipeline 3, and the pipeline 3 is connected to the periodic sewage discharge expansion container.

[0019] In this example, a circulation pipeline is connected to pipeline I between check valve I and manual gate valve II. Manual shut-off valve III, orifice plate and manual shut-off valve IV are installed in sequence on the circulation pipeline, and the circulation pipeline is connected to the condensate storage tank.

[0020] In this embodiment, the manual shut-off valve III, the orifice plate, and the manual shut-off valve IV constitute the recirculation system of the condensate transfer pump, which is used to protect the condensate transfer pump. When the condensate flow rate is less than the minimum flow rate required by the condensate transfer pump, the manual gate valve II is closed, and the manual shut-off valves III and IV are opened. The condensate at the outlet of the condensate transfer pump returns to the condensate storage tank through the recirculation system.

[0021] In this embodiment, a bypass pipeline is connected in parallel between the condensate storage tank of pipeline I and the junction with pipeline II. The bypass pipeline is equipped with a check valve III and a manual gate valve III.

[0022] In this example, check valve III and manual gate valve III form a bypass system used to supply water to the condenser hot well, and are not used as the boiler water supply system.

[0023] In this example, the condensate storage tank is supplied with water via a condensate transfer pump. The water flows sequentially through manual gate valve I, filter screen, the condensate transfer pump, check valve I, manual gate valve II, flange assembly, manual stop valve I, manual stop valve II, and check valve II into the fixed discharge collection box. After that, the water enters the boiler water-cooled wall through the drain pipe of the boiler water-cooled wall, and then enters the boiler steam drum through the water-cooled wall, thus completing the water supply.

[0024] In this embodiment, the regular drainage collection box receives condensate from the drainage pipes of each boiler water-cooled wall during normal boiler operation, and enters the periodic blowdown expansion container through the shut-off valve and the electric shut-off valve.

[0025] The above embodiments are only used to explain the inventive concept of the present invention, and are not intended to limit the protection of the present invention. Any non-substantial modifications made to the present invention using this concept should fall within the protection scope of the present invention.

Claims

1. A cold start-up water supply system for a circulating fluidized bed boiler in a power plant, characterized in that: It has a condensate storage tank, a fixed discharge collection box, and a periodic blowdown expansion box. The condensate storage tank is connected to the fixed discharge collection box via pipelines and a condensate delivery pump and a check valve II installed in sequence on the pipelines. The fixed discharge collection box is connected to the drain pipe of the boiler water-cooled wall via pipelines. The fixed discharge collection box is also connected to the periodic blowdown expansion box via pipelines and an electric shut-off valve on the pipelines. The pipeline between the condensate storage tank and the fixed discharge collection tank is sequentially equipped with a manual gate valve I, a filter screen, the condensate delivery pump, a check valve I, a manual gate valve II, a flange assembly, a manual stop valve I, a manual stop valve II, and the check valve II; The pipeline between the check valve I and the manual gate valve II is connected to the condensate storage tank via a circulation pipeline and a manual shut-off valve III, a throttling orifice plate and a manual shut-off valve IV installed on the circulation pipeline. The condensate storage tank is connected to the condenser hot well via a bypass pipeline and a check valve III and a manual gate valve III installed on the bypass pipeline. The pipeline between the manual gate valve II and the flange assembly is connected to the condenser hot well via a branch line; the bypass pipeline is connected in parallel to the branch line and the condensate storage tank.

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