A DCS-based three-stage wastewater pH control method and system

Abstract

The invention discloses a DCS-based three-stage wastewater pH control method and system, comprising the following steps: (1) using tools to collect process wastewater flow, pH value, and fine-tuning pool and protection pool wastewater pH value, and communicate into DCS; (2) Obtain the amount of acid / alkali entering the first-level rough adjustment tank through the preset soft instrument, multiply it by the neutralization scale factor as the set value of the neutralizer, and perform preliminary neutralization in the first-level rough adjustment tank; (3) Continue to add a neutralizer for adjustment according to the deviation between the pH value of the wastewater in the fine adjustment tank and the set value, and assign different PID parameters to the controller in different intervals of the titration curve according to the pH value of the wastewater; (4) According to the pH value of the wastewater in the protection tank Deviation from the set value, when the deviation exceeds the set range, continue to add neutralizer for adjustment. The purpose of the present invention is to improve the pH adjustment accuracy of wastewater through multi-stage adjustment, reduce the influence of pH fluctuation on the downstream device process and equipment, ensure the long-term stable operation of the device, and obtain obvious economic benefits.

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 neutralizing agent to adjust its pH value. The stability of the pH control of the process wastewater directly affects the stable and safe operation of the downstream device. [0003] At present, most pH automatic control adopts simple control action for adjustment, and no automatic control scheme is designed for the characteristics of strong nonlinearity and hysteresis in the pH adjustment process. As a result, the pH of the neutralized wastewater fluctuates greatly, which in turn causes the downstream devices to be too acidic or too alkaline, which affects the treatment effect of subsequent facilities such as flocculation sedimentation, catalytic oxidation, and biochemical treatment. Therefore, the inabilit...

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

Images