Variable/power frequency mixed control system and method for desulfurizing absorption tower pH values

Abstract

The invention discloses a variable / power frequency mixed control system and method for desulfurizing absorption tower pH values, and belongs to the field of absorption tower pH value control. The variable / power frequency mixed control system comprises two sub-modules: a slurry supply pump variable frequency control module and a slurry supply adjustment valve power frequency control module; the twosub-modules are combined to form a three-impulse control system; a PID is used as a primary controller and a PI is used as a secondary controller; and when the frequency of a slurry supply pump is controlled, the openness of a slurry supply adjustment valve is controlled, so as to optimum control for absorption tower pH values is realized. According to the system and method, the rotation speed ofthe slurry supply pump is controlled via variable frequency and the slurry supply adjustment valve is controlled via power frequency through optimizing automatic absorption tower pH value control logic, so that automatic adjustment is realized in the whole process and the pH value adjustment quality is improved.

Description

technical field [0001] The invention relates to the technical field of pH value control of absorption towers, and more specifically relates to a pH value variable power frequency mixing control system and method for desulfurization absorption towers. Background technique [0002] The wet desulfurization method mainly uses the limestone slurry sprayed by the absorption tower to chemically react with sulfur dioxide and sulfur trioxide in the flue gas. In order to reduce the emission of sulfur dioxide from the chimney and achieve environmental protection standards, the main indicator of the chemical reaction in the absorption tower is to control the pH value. If the pH value is too high or too low, it will affect the desulfurization efficiency. Therefore, it is necessary to accurately control the pH value. [0003] For the desulfurization absorption tower system, pH value control is a complex process with large lag and strong coupling, and the smoothness of the slurry supply pi...

AI Technical Summary

Problems solved by technology

[0006] (1) Under the original power frequency single-loop control mode, the throttling loss of the control valve is large, the control valve moves frequently, the pipeline vibration is large, and the adaptability to coal types is poor

[0007] (2) Under the original control mode, when the slurry supply volume is at a low flow rate, the fluidity of the slurry will be poor, which will easily cause pipeline blockage, slurry supply interruption and environmental protection index over-discharge, so that the machine must be shut down to eliminate defects

[0008] (3) The quality of the original pH control is poor, and the pH value fluctuates greatly, which is unfavorable to the desulfurization efficiency

[0009] (4) The original control loop has no feed-forward control, and has poor adaptability to working conditions such as load changes, sulfur content changes, and flue gas changes, and cannot guarantee high desulfurization efficiency

However, this application still cannot solve the problem of large throttling loss of the regulating valve, frequent actions, and easy blockage of the pipeline when the slurry supply volume is low. Secondly, the control of pH value fluctuates greatly, which is unfavorable to the desulfurization efficiency.

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