Method for preventing pH value sudden change in desulfurization system of thermal power plant

Abstract

The invention discloses a method for preventing pH value sudden change in a desulfurization system of a thermal power plant, which comprises the following steps: step 1, after outputting of a PID controller which controls opening degree of a valve, adding the outputting to an anti-blockage flushing control loop, transmitting the outputting of the anti-blockage flushing control loop to a valve opening degree instruction; step 2, acquiring outputting amount of a PID controller which controls the opening degree of the valve, recording as output1 which is used as the inputting amount of the anti-blockage flushing control loop; and a step 3, in the anti-blockage flushing control loop, when the integral value of the outputting amount out1 to time t is larger than zero, namely opening degree increase of the valve is required for increasing flow, overlapping a pulse amount on the outputting amount out1, wherein the amplitude is 10-15% and sustaining time is 8-10s; and when the integral value of the outputting amount out1 is smaller than or equal with zero, sustaining the outputting amount out1. The method of the invention has advantages of: overcoming pH value sudden change caused by pipeline blockage, ensuring stable long-time input of a pH value automatic control system, and greatly reducing operation and monitoring of operation personnel.

Description

Technical field [0001] The invention belongs to the field of limestone slurry flow regulation of a desulfurization tower, and in particular relates to a method for preventing a sudden change in pH value of a desulfurization system in a thermal power plant. Background technique [0002] The pH value of the desulfurization system in thermal power plants is related to the desulfurization efficiency and operational safety of the desulfurization system. The pH value is generally controlled by the slurry supply gate to control the flow of limestone slurry entering the desulfurization tower. The flow rate of the large gate is increased, and the pH value decreases, and vice versa. The pH value automatic control in the prior art generally adopts a basic single-loop PID controller, which uses the pH set value and actual value to be calculated by the PID controller to control the output of the slurry valve. Because the working fluid is limestone slurry, pipelines and valves will often be bl...

AI Technical Summary

Problems solved by technology

Since the working fluid is limestone slurry, the pipes and valves will often be blocked after a period of operation. The specific performance is that the flow rate does not rise when the valve is opened at a normal control speed. It will increase instantaneously, seriously affecting the valve adjustment performance

Due to this reason, the pH value control system of most power plants cannot be put into normal operation, or operators often need to manually flush, which seriously affects the pH value control and the operation effect of the desulfurization system.

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