ChemIndustrial pH Neutralizing Applicaion and Flowsheets for Neutralizers and pH Control Systems

Applications and flowsheets for neutralizers and pH control systems

The following are descriptions and schematics illustrating some typical applications of ChemIndustrial neutralizers and pH control systems.

Drawing 1 (pdf): A two-way neutralizer installation using existing sump
In this system the acidic/basic waste liquid drains from the customer's process into an existing sump at a low point in the customer's plant. The sump is retrofitted with a custom-built ChemIndustrial fiberglass grid deck that bridges the sump and incorporates level sensing instrumentation and two redundant, alternating, transfer pumps.

Pre-wired cables connect pump motors and level sensors to the ChemIndustrial control panel. After the retrofit is installed on the sump and equipment cables are connected, this unit behaves like a standard ChemIndustrial duplex Liquid Waste Transfer Station (LWTS).

The retrofit LWTS transfers waste liquid to a surge tank. A correctly sized surge tank uncouples the instantaneous flow of the incoming process liquid from the treatment rate of the neutralizer thus allowing the neutralizer to be sized to treat the average flow instead of the peak waste liquid flow. This usually allows a smaller (lower cost) neutralizer to be installed.

From the surge tank, liquid flows into the ChemIndustrial two-way neutralizer by gravity via an on/off valve controlled by the neutralizer.

The neutralizer is capable of running in pure batch mode but it also has a second, more productive control algorithm: ChemIndustrial's Semicontinuous pH Control Algorithm™.

This opportunistic algorithm begins aggressive treatment of the waste liquid as soon as any becomes available, without waiting for the neutralizer to fill. The algorithm discharges liquid whenever pH is within the allowable discharge range. It ceases discharging and resumes treatment whenever pH drifts outside the control band.

This drawing also shows a typical application of ChemIndustrial's ChemWand® drum feeders to supply acid and base reagents to the two-way neutralizer.

Drawing 2 (pdf): A two-way neutralizer with one or more distributed Liquid Waste Transfer Tanks

Drawing 3 (pdf): A two-way neutralizer with Liquid Waste Transfer Tank and distributed control system

Drawing 4 (pdf): A large lab installation with central sump

Drawing 5 (pdf): A large lab installation with distributed sumps

Drawing 6 (pdf): A simple one-way neutralizer with surge tank

Drawing 7 (pdf): A small under-bench lab neutralizer

Drawing 8 (pdf): A simple two-way neutralizer with surge tank

Drawing 9 (pdf): A ready-mix concrete facility
In this system the acidic or basic waste liquid drains from its source into an open settling pond.

Often the waste liquid originates directly from a washout operation. In other cases the liquid is storm water that carries dissolved material and fines from a yard or mining site. In both cases, regulations require the pH of the liquid to be brought into the neutral range before discharge.

The drawing shows an automated one-way neutralizing system as it is applied at a readymix concrete plant or a mineral processing site. The neutralizer's automatic control system starts and stops the pond pump to transfer pond liquid to the neutralizer. The neutralizer treats the liquid automatically and discharges the treated liquid. When the pond reaches low level the neutralizer goes into standby mode until more liquid becomes available.

One of the functions of a surface pond is to act as a settling basin for suspended solids. However, it is difficult to ensure rapid, 100% settling efficiency in the pond. To minimize downsteam problems from suspended materials, ChemIndustrial offers an optional Hydroclone to dramatically reduce the amount of suspended material reaching the system outflow via the neutralizing skid.

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