The Need for Improvement
Water fed to a boiler contains dissolved minerals and gasses which will cause serious damage if left unchecked: feedwater treatment is necessary to prevent the damage occurring.
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.
Much is made of the need to ensure correct combustion, water feed and Total dissolved solid levels but little attention is paid to the chemical dosing.
Over dosing chemicals can lead to a reduction in efficiency, an increase in blowdown and energy wastage, under dosing leads to premature failure
Historically, boiler water has been manually tested with corrective adjustments made to the chemical dosage rate based on the results.
BS 2486:1997 states under section 2.5 Sampling and Testing:
“As a minimum, boiler water, feed water and condensate should be tested once per day and the ion exchange plant should be tested three times a day”
If a daily test is sufficient, have you ever considered why more than 70% of all recorded boiler failures are accredited to incorrect water treatment?
The rule of thumb that governs the testing of boiler water has its roots way back in the past when the ‘Lancashire Boiler’ reigned supreme.
The design and construction of boilers has changed considerably since then. For the same steam output, boiler size has reduced and the steam release rate increased. Yet we still persist in accepting a daily water test.
Steam boilers are designed to deliver dry steam and are fully automatic in operation. The maximum steam output from a boiler at any given pressure is governed by the rate at which heat can be supplied and transferred in the boiler. Modern Steam Boilers have a high heat transfer rate: Chemical deposits or scale inhibit or restrict heat transfer, boiler efficiency falls and the possibility of failure increases.
With modern controls that comply with the Health & Safety Guidance Note PM5 or Safed PSG2 Arrangement 3, Steam Boilers can operate without manual intervention save for the weekly evaporation test to ensure that the safety alarm systems operate correctly.
Yet we pay lip service to the quality of water inside the boiler.
Is it not time then to change our attitude to water treatment?
Automatic monitoring and chemical dosing controls should be fitted as standard, particularly in boiler houses that operate with reduced supervision.
