DCS based three-stage wastewater pH control method and system

A control method and technology for wastewater, which are applied in water treatment parameter control, comprehensive factory control, chemical instruments and methods, etc., can solve the problems of pH value overshoot, no protection adjustment tank, and inability to pull the wastewater pH back to the target value, etc. Achieve the effect of reducing hysteresis and reducing pH fluctuations

Active Publication Date: 2020-02-04
WANHUA CHEM GRP CO LTD +1
View PDF5 Cites 3 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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 va...

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • DCS based three-stage wastewater pH control method and system
  • DCS based three-stage wastewater pH control method and system
  • DCS based three-stage wastewater pH control method and system

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] A chemical plant produces a stream of alkaline wastewater with a pH value between 10 and 12. 8% hydrochloric acid is used as a neutralizing agent to adjust the pH in a three-stage neutralization tank. It is hoped that the pH value will be controlled at 5 to 7. In addition to this stream of wastewater, this wastewater pool also regularly receives another stream of alkaline wastewater with a pH value above 13 (2-3 times per shift), which causes large fluctuations in the flow and composition of wastewater entering the neutralization tank. The designed simple circuit cannot realize the stable control of the pH value, requiring frequent manual intervention by the operator, the operation volume is as high as 15 times per shift, and the pH overshoots by more than ±3, which not only hinders the long-term stable operation of the wastewater treatment system, but also seriously affects The degree of automation of the device. For this reason, carry out transformation according to t...

Embodiment 2

[0095] A chemical plant produces a stream of acidic wastewater with a pH value between 3 and 4. Use 10% caustic soda as a neutralizing agent to adjust the pH in the neutralization tank. It is hoped that the pH value will be controlled at 6 to 8, because there is only one level of neutralization The mixing time of acidic wastewater and caustic soda is short, and the neutralization is incomplete. Therefore, the pH value of the wastewater at the outlet of the neutralization tank can only be controlled at (6-10), which affects the service life of downstream devices. For this reason, according to this patent, carry out transformation, enlarge it into a three-level protection pool, and add 10% caustic soda pipeline in the fine adjustment pool, and add 10% caustic soda pipeline and 10% hydrochloric acid pipeline in the protection pool, and control in DCS according to the design of this patent The program is reconfigured.

[0096] After transformation, the alkaline waste water first e...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

No PUM Login to view more

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...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Application Information

Patent Timeline
no application Login to view more
IPC IPC(8): C02F1/66
CPCC02F1/66C02F2209/06Y02P90/02
Inventor 王浩王远辉朱敏燕王亚辉田宇吴雪峰张宏科
Owner WANHUA CHEM GRP CO LTD
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap