Circulating cooling water treatment of thermal power plant based on microbial treatment process

Abstract

Circulating cooling water consumes a large amount of water in thermal power plant, and there are some problems such as scaling and corrosion in the system. This study presents a novel circulating cooling water treatment process based on microbes. The mechanism and influencing factors of microbial treatment process of circulating cooling water is studied. Water from circulating cooling system of a 300 MW thermal power unit was used, dynamic simulation test was carried out and com- pared between the microbial treatment process and the traditional chemical treatment process. The results showed that nutrient solution dosage on calcium hardness is positive, while the interaction between nutrient solution dosage and aeration rate has negative effect. When ammonia concentration is 10–50 mg/L and aeration rate is 1–3 L, and the minimum calcium hardness is 18.3 mmol/L. Reducing the concentration of nutrient solution and increasing the aeration rate are beneficial to slow down the corrosion of carbon steel and stainless steel. When ammonia concentration is 10–50 mg/L and aeration rate is 1–3 L, the minimum corrosion rates are 0.01552 and 0.00110 mm/a, respectively. Compared with traditional chemical treatment process, the microbial treatment process can achieve the scale inhibition and corrosion inhibition target at high concentration ratio, the highest concentration ratio can reach 5.4, and the corrosion rate of carbon steel and stainless steel is low. The green, efficient and environment-friendly microbial treatment process provides a new method for circulating cooling water treatment, which can obtain stable and economical operation of circulating cooling water system under high concentration ratio.