System and method for adjusting flexibility of coal-fired unit using water supplementing tanks

Abstract

The invention provides a system and method for adjusting the flexibility of a coal-fired unit using water supplementing tanks. When the load of the system is increased, the opening degree of a first water feed pump is reduced, the water feeding amount is reduced, required steam extraction of a steam turbine is less, and the work of the steam turbine is increased; meanwhile, the liquid level of a condenser rises, and the cold water supplementing tank can store condensed water to prevent the liquid level of the condenser from being too high; and the water feeding amount is reduced, so that the liquid level of a deaerator is reduced, and at the time, the hot water supplementing tank supplements water to the deaerator under driving of a second water feed pump. When the load of the system is decreased, a part of exhausted steam of a high-pressure cylinder enters a jet type heat pump, the amount of steam entering a low-pressure cylinder is reduced, the work of the steam turbine is reduced, the jet type heat pump uses the exhausted steam of the steam turbine to heat low-temperature water in the cold water supplementing tank, and the mixed high-temperature water is injected into the hot water supplementing tank. According to the system, an external water supplementing tank adjusting system is added on the system of an original heat recovery system, the unit heat storage capacity is increased while the load of the unit is quickly increased or decreased, the equipment structure is simple, and the flexibility and economical efficiency of the unit are improved.

Description

technical field [0001] The invention relates to the technical field of flexibility adjustment of a coal-fired unit, in particular to a flexibility adjustment system and an adjustment method of a coal-fired unit using a makeup water tank. Background technique [0002] With the rapid development of my country's economy and the improvement of people's living standards, the demand for electricity is also increasing. Coal-fired units in the power system have a large capacity. In order to cope with large-scale wind power, solar energy and other new energy power generation and grid integration, as well as changes in my country's power consumption structure, coal-fired units will undertake more and more difficult peak-shaving tasks. This puts forward high requirements on the flexibility of coal-fired units, requiring them to be able to operate with a large change in load and to have a rapid change in load rate. When the power grid requires rapid load changes, the internal heat stor...

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Problems solved by technology

When the power grid requires rapid load changes, the internal heat storage capacity of the system is limited, and a more potential heat storage system is required to cooperate with traditional coal-fired units, and the liquid level of the condenser and deaerator will change, while the water level of the condenser If the water level is too low, the condensate pump will cause cavitation; if the water level of the deaerator is too high, it will cause the loss of working fluid and heat, and the working pressure in the deaerator will be unstable. , affecting equipment safety and deoxygenation effect, too low water level will cause cavitation of feed water pump

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