DCS based three-stage wastewater pH control method and system

Abstract

The invention discloses a DCS based three-stage wastewater pH control method and a system. The method comprises the following steps: (1) acquiring flow rate and a pH value of process effluent, a wastewater pH value of a fine adjustment tank and a wastewater pH value of a protection tank with tools, and carrying out communication with a DCS; (2) obtaining an acid / base amount entering a first-stagecoarse adjustment tank through a preset soft meter, multiplying the acid / base amount by a neutralizing proportional factor so as to obtain a set value of a neutralizer, and carrying out preliminary neutralization in the first-stage coarse adjustment tank; (3) continuing to add the neutralizer for adjustment according to a deviation between the wastewater pH value of the fine adjustment tank and the set value, and endowing a controller with different PID parameters in different intervals of a titration curve according to the wastewater pH value; and (4) continuing to add the neutralizer for adjustment according to a deviation between the wastewater pH value of the protection tank and the set value when the deviation exceeds a set interval. The method and the system have the aims that through multistage adjustment, the accuracy of wastewater pH adjustment is increased, the influence on processes and equipment of downstream devices caused by pH fluctuations is reduced, long-cycle stable operation of the devices is guaranteed, and the economic benefit is obvious.

Description

technical field [0001] The invention relates to a DCS-based three-stage wastewater pH control method and system. Background technique [0002] Before the acidic or alkaline process wastewater is sent to the downstream device for treatment, it is often necessary to add a neutralizer to adjust its pH value. The stability of the pH control of the process wastewater directly affects the stability and safe operation of the downstream device. [0003] At present, most of the pH automatic control is adjusted by simple control function. There is no automatic control scheme designed for the characteristics of strong nonlinearity and hysteresis in the pH adjustment process. When the flow and composition of wastewater change, it is easy to cause excessive addition of neutralizer. This leads to large fluctuations in the pH of the wastewater after neutralization, which in turn causes the downstream devices to be too acidic or too alkaline, which affects the treatment effects of subsequen...

AI Technical Summary

Problems solved by technology

This invention has the following disadvantages: ① neutralization is carried out through a single-stage wastewater tank, and the hysteresis of the mixing process between wastewater and neutralization is not fully considered, and the pH value of the neutralized wastewater cannot be accurately controlled; ② the wastewater pH value PID controller uses a fixed The PID parameter does not fully take into account the nonlinearity of the pH adjustment process, which may easily lead to overshooting of the pH value; ③ there is no protective adjustment pool, and the pH of the wastewater cannot be pulled back to the target value after adding too much neutralizer

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