Deep heat supply cold end system of direct air cooling unit

Abstract

The invention discloses a deep heat supply cold end system of a direct air cooling unit, and relates to the technical field of cold ends of direct air cooling units of steam turbines of thermal powerplants. The system comprises a low-pressure cylinder, a steam exhaust device, a cooling water spraying mechanism, an air cooling island and an air cooling mechanical tower; the steam exhaust device isconnected with a steam exhaust outlet of the low-pressure cylinder, and the cooling water spraying mechanism is arranged in the steam exhaust device, so that cooling water can exchange heat with deadsteam in the steam exhaust device to form condensed water; the air cooling island is connected with the steam exhaust device through a steam exhaust pipeline, so that dead steam in the steam exhaustdevice can enter the air cooling island to be cooled; a steam exhaust valve is arranged on the steam exhaust pipeline, and the air cooling mechanical tower is connected with the steam exhaust device through a water drainage pipeline, so that condensed water in the steam exhaust device can be discharged into the air cooling mechanical tower to be cooled; Through implementation of the technical scheme, the risk of icing of the air cooling island can be effectively prevented while the low back pressure capacity of the unit is maintained during deep heat supply, and the safety and reliability of the unit can be effectively enhanced.

Description

technical field [0001] The invention relates to the technical field of the cold end of the steam turbine direct air cooling unit in a thermal power plant, in particular to a deep heat supply cold end system of the direct air cooling unit. Background technique [0002] Conventional thermal power direct air-cooled units are undergoing deep heating transformation such as low-pressure cylinder cutting, micro output, zero output, etc. Although the exhaust steam of the low-pressure cylinder is very small, it is also necessary to maintain low back pressure of the steam turbine to reduce the final blade of the steam turbine. The risk of overheating of the blades brought about by the blowing wind, while recovering from some system leakage and ensuring the pressure difference of the drain, etc. [0003] In the operation of the existing steam turbine, the exhaust steam of the steam turbine is condensed into the air-cooled island. Although the air-cooled island adopts a group design, th...

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Problems solved by technology

[0005] Technical solution 2 adopts a newly added surface heat exchanger, and the steam drawn from the outlet steam pipe of the exhaust device is condensed in the external condenser; for example, the patent with the publication number CN109469522A discloses a exhaust steam cooling system and exhaust steam cooling system. Method, by setting a pipe connected to the inlet of the exhaust steam cooler on the exhaust pipe from the exhaust steam of the steam turbine to the air cooling island, during the zero output operation of the low pressure cylinder of the direct air cooling unit in the winter heating season, the steam distribution of the air cooling condenser is closed. All steam inlet valves are piped, the air-cooled condenser is isolated, and all the exhaust steam of the steam turbine unit is introduced into the exhaust steam condenser for condensation. The cooling water source is taken from the auxiliary cooling water system of the unit, and the condensed water is returned to the exhaust device of the main engine, completely solving the problem of direct air cooling The freezing problem of the air-cooled condenser during the heating operation of the low-pressure cylinder with zero output in the heating season of the unit; however, this solution has the following technical defects: due to the low steam pressure and large specific volume, the exhaust steam extraction pipeline is very large, the pipeline layout and civil engineering design The construction is difficult. At the same time, the circulating water of the condenser needs to be taken from the closed cooling water system or an independent closed circulating water system is installed. Usually, the direct air cooling unit area is seriously short of water. This solution needs to increase a large amount of circulating water, which is not conducive to water saving. And the system pipeline is complex, the failure rate is high during operation, and the investment is large

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