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Solvocarb - pH Control Systems
A number of types of pH control system are available. Suitability depends on the method of carbon dioxide dissolution required and the existing collection and transfer systems for the wastewater.
Pipeline reactor
Pipeline reactor skids comprise a length of pipework typically in plastic in a hairpin configuration.
CO2 is injected at one end, the pH reduces over the length of the reactor and a pH analyser automatically feeds information back via a three-term process controller to adjust the CO2 flow in order to maintain the desired pH set point.
Pipeline reactors are ideal where the flow of water and the pH of the raw water are relatively consistent.
Neutralisation system
Where the flow and/or pH of the effluent is more variable - for example from process machine washing-down/rinsing cycles - BOC offers a tank neutralisation system. This incorporates a combined equalisation and neutralisation tank.
CO2 can either be injected into an integral side-stream dissolver system or, if the tank is deep enough, the CO2 diffuser can be efficiently employed to provide the dissolution.
The pH probe within the tank monitors pH and controls the injection of CO2 to achieve the desired pH level.
The BOC pH neutralisation system works by dissolving gaseous carbon dioxide into the alkali wastewater requiring pH reduction. Once in solution the carbon dioxide rapidly forms an acidic compound called carbonic acid. It is this acid that reacts with the alkalinity in the water; lowering the pH.
The neutralisation reaction is very fast and efficient, especially at high pH levels where it is twice as effective as sulphuric acid on a weight-to-weight basis.
Compact alkaline pH control system
Using CO2 is an environmentally-friendly process and known to be the Best Practicable Environmental Option (BPEO) upstream of any biological system.
It is much safer than aggressive mineral acid systems; there is no requirement for safety showers or bunded storage areas.
Good controllability is achievable with a self-limiting lower pH limit. The systems are fully automated with little operator input and little maintenance required.
Design and installation
The BOC Water Processes team provides a complete design and installation service right through to training and commissioning.
Once installation is complete, BOC continues to provide process and engineering support when required to ensure the system gives years of robust service.
Plant size
All sizes of plants have been designed and built with CO2 flow rates from 10 kg per hour to 10 tonnes per day.
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