Status and Standardization of the Water-Chemical Regime for Power Generation Boilers

Resumo

The need to increase the amount of automatic chemical control is pointed out, especially by measuring the conductivity of cooled probes, including direct and H-cation probes. These studies demonstrate the possibility of automatic chemical control of the phosphate regime in drum boilers and quantitative monitoring of the amount of potentially acid substances, i.e., impurities in the feed water for flow-through boilers. It is proposed that the 2009 standards document STO by the firm NP “INVEL” should be taken as the basis with a number of changes and additions. For the first time, a number of standard limits for amine-containing water-chemical regulation of the steam-gas generating units are recommended. The following limits are proposed for the introduction of an amine water-chemical regime in units without copper-containing alloys: for the turbine condensate the conductivity of an H-cation sample should be less than 1.0 μS/cm and the amount of dissolved oxygen should be less than 20 μg/dm³; the feed water conductivity of an H-cation sample should be less than 1.0 μS/cm and the pH = 8.9 – 9.5; the amount of dissolved oxygen after the deaerator should be less than 10 μg/dm³ and the amount of film-forming amines greater than 10 μg/dm³. Schemes for preliminary treatment of low-mineral natural water with elevated contents of organic materials are proposed which reduce the acidity of the water by 70 – 80%.