Automatic control method for transformation process of supercritical or ultra-supercritical unit from hygrometric state to dry state

Abstract

The invention discloses an automatic control method for a transformation process of a supercritical or ultra-supercritical unit from a hygrometric state to a dry state. Currently, the dry-hygrometricstate transformation of a/an (ultra-)supercritical unit mostly adopts a manual operation mode. The technical scheme adopted by the automatic control method is characterized in that firstly a reasonable state transformation node is determined; a theoretical coal feeding amount increment required by a boiler is calculated according to process parameters of stable operation of the unit at a hygrometric state before state transformation; the boiler coal amount is gradually increased according to an optimum coal feeding amount changing rate which is determined through a unit feature test in the state transformation process until the theoretical coal feeding amount increment is reached; and at the initial period of the state transformation, in consideration of the delay feature of the boiler, the water feeding amount at the inlet of a coal economizer is reduced by lowering the water feeding flow, so that the state transformation process is accelerated. By adopting the automatic control method, stable transition of the working conditions in the state transformation process is realized; and the change of the unit parameters is slow, so that abnormal phenomena of equipment failure, overheating of heated surfaces or tripping caused by frequent switching of dry-hygrometric state transformation and acute fluctuation of unit parameters are avoided.

Description

technical field [0001] The invention relates to the technical field of intelligent control of thermal power units, in particular to a method for automatic control of a super (super) critical unit from a wet state to a dry state. technical background [0002] Ultra (ultra)critical units have many advantages such as high economy, good environmental protection, and strong load adaptability. They are the main thermal power units for electricity production in my country in the near future and in the future. The pressure of the working fluid in the super (super) critical unit is above the critical point. When the water reaches the critical pressure, the latent heat of vaporization is 0, and the complete vaporization of water is completed instantly. There is no difference between the two parameters. cycle, so only once-through boilers can be used. The once-through boiler is a boiler that relies on the pressure of the feed water pump to make the feed water pass through the economiz...

AI Technical Summary

Problems solved by technology

Since the dry-wet state switching only occurs during the start-up process of the unit, many operators have little operation on the dry-wet state switching and have insufficient accumulated experience. There is psychological pressure on this switching process

In particular, the starting system with boiler water circulation pump has many operating equipments, and the operating conditions are more complicated

The operation level of power plant operators is uneven, and there are often phenomena such as large load fluctuations when switching between dry and wet states, overheating of steam temperature, and frequent switching between dry and wet states.

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