Method for Controlling Liquid Level of Steam Drum of Thermoelectric Boiler

Abstract

The steam drum liquid level control method of the thermal power boiler involved in the present invention takes the three variables of the steam drum liquid level, the feedwater flow rate and the steam flow rate as the processing objects, the control system adopts the structure of feedforward + cascade as a whole, and the main regulator adopts the steam drum liquid level control method. The liquid level is a conventional PID regulator that detects and controls the variable. The deviation between the set value SP of the liquid level in the steam drum and the actual measured value LT is calculated by the PID regulator and the output is the set value of the feed water flow; the steam flow outside the drum is supplied. The measured value is used as a feedforward control variable; its sub-regulator adopts a single neuron self-adaptive PSD regulator with feedwater flow as the detection and control variable; through this technical solution, according to the complex situation of the boiler drum operation, advanced and reliable , Practical calculation, realize the self-adaptive optimal control of the boiler drum liquid level, and ensure the efficient and stable production of the boiler.

Description

technical field [0001] The invention relates to a boiler liquid level control method, in particular to a thermoelectric boiler steam drum liquid level control method. Background technique [0002] The boiler drum liquid level control system is an important key process in the boiler production process. The stability of the boiler drum liquid level is crucial to maintaining boiler safety, improving boiler efficiency, and reducing production costs. During boiler operation, the steam drum liquid level There are many factors affecting the stability, the main ones are the feed water flow and steam flow. When the feed water flow increases, because the temperature of the feed water is relatively low, it absorbs heat from the original saturated water and reduces the drum water volume. Therefore, The water level of the steam drum does not rise immediately at the beginning, but shows an initial inertia stage; when the steam load increases, from the perspective of material balance, the ...

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Problems solved by technology

[0002] The boiler drum liquid level control system is an important key process in the boiler production process. The stability of the boiler drum liquid level is crucial to maintaining boiler safety, improving boiler efficiency, and reducing production costs. During boiler operation, the steam drum liquid level There are many factors affecting the stability, the main ones are the feed water flow and steam flow. When the feed water flow increases, because the temperature of the feed water is relatively low, it absorbs heat from the original saturated water and reduces the drum water volume. Therefore, The water level of the steam drum does not rise immediately at the beginning, but shows an initial inertia stage; when the steam load increases, from the perspective of material balance, the steam volume is greater than the feed water volume, and the water level should drop, but in practice, a sudden increase in the steam load will cause As a result, the pressure of the steam drum decreases, the volume of steam in the steam-water mixture increases rapidly, and the water level rises rapidly, that is, the "false water level" phenomenon; The physical characteristics will change accordingly, which will cause the problem of model mismatch; in short, the boiler drum liquid level system is a system with large inertia, long lag time, and nonlinear time-varying

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