Chemical Composition

Chemicals are added to boiler feedwater to protect the boiler shell and heat transfer surfaces from scale deposits and corrosion and in some cases to protect the process and condensate systems.

The rate of steam generation varies with time of day and production requirements yet we are apparently happy to test a sample of boiler water once a day or even twice a week and base all the chemical protection requirements on those test results.

Can we be absolutely sure that we are doing our best to protect the boiler? Over 70% of all recorded boiler failures are attributable in one way or another to the chemical treatment.  

The function of a boiler is to transfer the energy in fuel into steam: it can do this efficiently only if the heat transfer surfaces within the boiler are maintained in a clean condition by the correct pre-treatment of the feedwater and boiler water.

It is generally acknowledged that the most satisfactory method of boiler water conditioning consists in accurate control of preliminary softening/demineralisation process, followed by the addition of suitable reagents in controlled proportions based on the composition of the water and the operating pressure of the boiler.

The composition of the reagents and the quantities added can only be determined by expert chemical analysis of the water supply but once determined it is essential that they are accurately applied.

Accurate chemical dosing cannot be achieved without knowing the rate at which the feedwater enters the boiler.

Testing boiler water daily and adjusting the feed rate of the chemicals based on these results presupposes that the hourly steam generation rate is constant. No matter how large or small your boiler plant, steaming rate will vary hour to hour day to day.

If you don’t know how much water is being fed into your boiler how can you accurately protect it?

Wouldn’t it be beneficial to all companies operating steam boiler plant to measure the boiler feedwater flow rate, automatically sample the boiler water and adjust the chemical dosing according to the results?