Physicochemical Analysis of Organic Impurities in the Coolant of Combined Heat and Power Plants Equipped with Combined-Cycle Power Installations

Abstract

In 2018, combined-cycle power installations equipped with heat-recovery steam generators were commissioned at the combined heat and power plant nos. 1, 2, and 3 (CHPP-1, CHPP-2, and CHPP-3) in the city of Kazan. The content of organic substances in the blowdown water of clarifiers, in chemically demineralized water, in evaporating plant condensate, in heat-recovery steam generator feed water and blowdown water, and in turbine condensate was investigated. Organic substances in dry form were separated from water samples using the extraction method. The physicochemical properties and structures of the separated organic impurities were determined using an elemental analysis, infrared spectroscopy, high-efficient liquid chromatography, chromatography-mass spectrometry, and nuclear magnetic resonance methods. It was found that the content of total organic carbon (TOC) was higher than its standardized value in the heat-recovery steam generator feed water, slightly higher than the standardized value in the condensate of evaporators, and in compliance with the existing standard requirements in the turbine condensate and chemically demineralized water. Humic substances that are not removed from water during its pretreatment and enter in the heat-recovery steam generator feed water were identified as the main organic component. It is shown that ion exchange is an efficient technology for removing organic impurities from makeup water for the heat-recovery steam generator.