Water Chemistry Development for a Thermal Power Plant Circulating Cooling System Using the VTIAMIN EKO-1 Chemical Agent

Abstract

Numerous substances and complex chemical agents, as well as various biocides for inhibiting the growth of microbial colonies and algae, are commercially available in the market of water treatment chemicals. In frequent cases, the chemicals offered in the market are not adapted to the water chemistry conditions of power plant circulating cooling systems (CCSs), and attempts of using them may lead to violation of the circulating water or effluent (blowdown) water quality standards. The aims of this study were to investigate the effectiveness of the VTIAMIN EKO-1 chemical agent and to select its optimal dose to reduce the corrosion rate of heat transfer surfaces and prevent mineral deposits from forming on them under the conditions of the experimental bench facility simulating the operation of CCSs for the condensers of steam turbines used at combined heat and power plants (CHPPs) equipped with a PGU-450 combined-cycle power unit. During the bench tests, the circulating and makeup water quality in terms of main indicators was monitored on a daily basis. For evaluating the corrosiveness of circulating water flowing in the experimental bench facility, a pair of corrosion rate surveillance specimens (coupons) made of St. 20 carbon steel and one brass coupon were installed at all test stages. The circulating water scale-forming properties were evaluated based on the results from visual examination and weighing of the thermal electric heater and the surveillance specimen made of stainless steel as well as the stabilization coefficient (calcium transport) calculation results. After having been evaporated, the CHPP makeup water that has not been subjected to corrective (reactant) treatment has increased scale-forming and corrosive properties with respect to carbon steels and medium-level scale-forming and corrosive properties with respect to brass. By using the VTAMIN EKO-1 chemical agent in the optimal dose, the carbon steel corrosion rate was slowed down by a factor of 3.7; the linear deposit-formation rate was decreased by a factor of 27.5, and the stabilization coefficient was kept at a level of 95.72%. In so doing, the requirements posed to the chemical agent’s key components by the standards for fishery water bodies were not violated. With the average content of the VTIAMIN EKO-1 reagent in circulating water at a level of 9.54 mg/dm3, its effectiveness in terms of corrosion protection and prevention of scale formation has been demonstrated. The estimated demand for the chemical agent is 33 397 kg/year.