Concentration control of silica in water chemical regime for natural circulation high pressure drum boiler unit of thermal power station

Abstract

The effective relations of silica (SiO₂) concentration in boiler drum and generated steam, with respect to pH and pressure for a natural circulation water wall tubes (WWTs) high-pressure (158 and 100 kGք cm⁻²) boiler, (Type TGME-206-COB, Russia) at Ghorasal Thermal Power Station (GTPS) Bangladesh, has been studied. Extensive analyses of different parameters of boiler water chemical regime (WCR) of the plant based experimental results revealed that on maintaining SiO₂ 0.35 (± 0.15) mgL⁻¹ in boiler drum clean (evaporation) section [at pH 9.1 (± 0.1), temperature 330ºC (± 10ºC)] of boiler WCR provides excellent results with less corrosion or scale formation in interior surface of boiler WWTs and turbine blades. Such a procedure is effective for high softening of make up water SiO₂ 0.02 (± 0.01 mgL⁻¹) ensuring high degree of purity of feed water cycle of the boiler and appropriate dosing of chemicals in boiler.