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Steam Boiler Feedwater Chemical Dosing "The Need for Improvement"

It is not necessary to know chemistry to appreciate the fundamentals of water treatment. Good water treatment practice is dependent on a suitable treatment regime for the whole system; from the cold feed to the returning condensate.

Water fed to a boiler contains dissolved minerals and gasses which will cause serious damage if left unchecked: feedwater treatment is necessary to prevent that damage occurring.

Boiler feedwater chemicals need to be applied and maintained at specified concentrations for their desired effects to be achieved. The object is to optimise the chemical characteristics in order to reduce the risk of corrosion, sludge precipitation or formation of deposits which may lead to tube or boiler failure.

The present method of manually setting the stroke length and pulse rate of dosing pumps enables chemicals to be added in a simple 'Open-Loop' system with no feedback except for a daily manual test. Any change in feedwater temperature or quality or steam generation rate will cause an imbalance.

'Open-Loop' systems, those without the intelligence of feedback, tend to be very inefficient and wasteful.

However, 'Closed-Loop' or 'Feedback' control is inherently stable and eliminates all the short comings of the 'Open-Loop' system.

Adopting a 'Dosing on Demand, Closed-Loop' control regime maintains boiler efficiency, reduces fuel costs, saves money and most importantly improves safety.