Preventing dew point corrosion on convection heating surfaces in heating boiler - involves choking heating circuit during start=up to ensure single transition through dew point temperature

摘要

A method of preventing dew point corrosion on the convection heating surfaces in a heating boiler of a heating system involves raising the boiler temp. during the start-up phase of heating from the cold state. At the beginning of the start-up phase the temp. of the water returning to the boiler and the water in the boiler are measured simultaneously. The results are used to control a circulation control device such as a mixer valve or rotary pump to choke the circulating water quantity in the heating circuit and to heat the water in the boiler circuit. When the boiler water temp. exceeds the dew point temp. the heater circuit is opened. ADVANTAGE - Involves only one transition through dew point during start-up phase and eliminates use of unreliable return pumps.