Method for directly starting steam-driven feed water pump of large-sized thermal power plant

Abstract

Disclosed is a method for directly starting a steam-driven feed water pump of a large-sized thermal power plant. Two steam inlet sources are designed for a steam turbine of the steam-driven feed water pump, and steam is supplied in a cold-section mode or a main steam mode and four-stage steam extraction mode. The method for directly starting the steam-driven feed water pump includes adding an auxiliary steam source; supplying steam to the steam-driven feed water pump by the auxiliary steam source in a starting phase; completing a water supply process for the boiler by the aid of the steam-driven water feed pump; gradually switching a small-machine steam inlet mode from an auxiliary supply mode into the cold-section mode or the main steam mode when parameters of cold-section steam or parameters of main steam meet requirements on inlet steam of the steam turbine of the water feed pump; and realizing a starting function of the steam-driven water feed pump. An electric starting water feed pump is omitted, the auxiliary steam source of the steam turbine of the steam-driven water feed pump is added, the steam-driven water feed pump is directly started, a bypass regulating valve system is disposed on a high-pressure water feed pipeline of a boiler, and the requirement on control of water feed flow of the boiler when load of the boiler is low is met.

Description

Technical field [0001] The invention relates to a method for directly starting a steam-driven feedwater pump in a large thermal power plant of 300MW and above, and belongs to the technical field of thermal power plant design. Background technique [0002] At present, the feedwater pump configuration scheme for 600MW or 1000MW units in thermal power plants is mostly 2×50% capacity steam-driven feedwater pumps plus 1×25-30% electric feedwater pumps. The functions of electric feedwater pumps include standby and start-up services for the unit. At present, due to the high reliability of the steam-driven pump unit, on the other hand, the electric pump with 30% of the capacity of the large-capacity unit puts pressure on investment and plant power consumption. Economical. Most of the newly built power plants do not consider the backup function of the electric pump, and only retain the start function. Although canceling the backup function of the electric feedwater pump can save a large ...

AI Technical Summary

Problems solved by technology

Although the cancellation of the standby function of the electric feed water pump can already save a large initial investment, the price of the start-up electric feed water pump for a 1000MW unit is about 4.5 million at present, and 9 million for two units, plus the cost of pipelines and valves , the investment of two 1000MW units in the electric feed water pump system reaches 10 million, and it is only a short-term service function when the units are started, which is obviously economical.

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