Continuous blowdown of the steam boiler based on the alkalinity of the boiler water |

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Guidelines for maintaining the water-chemical mode of steam boilers prescribe continuous blowdown of boilers based on dry residue or salt content.

For example, RTM 108.030.114-77 (Stationary steam boilers of low and medium pressure. Organization of a water-chemical mode) gives the following formula for calculating the percentage of continuous blowdown based on the boiler steam capacity.

      ,    %   (1)



Smw –makeup water salinity, mg/l (ppm)

Sbw – boiler water salinity, mg/l

Q – the share of makeup water in the feed water of a steam boiler


К – the share of condensate return .

The equation (1) assumes that the salinity of the returned condensate and the salinity of the steam produced are equal to zero.

This equation is used universally to calculate the fraction (percent) of steam boiler blowdown from steam production.

In fact, the calculation using this equation contains a significant error. It’s all about the method for determining the salinity of boiler water.

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