Batch and continuous bleaching regimen in the cooling tower of Montazer Ghaem power plant

Abstract

In order to control the microbial growth in the cooling tower of thermal power plant, oxidative and non-oxidative biocides are applied in the power industry. Oxidative biocides including chlorine dioxide and bromine-based compounds are effective for controlling microbial growth in cooling towers. The choice of biocide depends on the type of cooling tower, water quality, and regulatory requirements. In the most cases, the bleaching regimen is selected as the most effective and low-cost oxidative biocides in cooling tower. The bleaching regimen is carried out in batch mode generally and herein for the first time, the continuous bleach is examined in the cooling tower of Montazer Ghaem power plant by evaluating the microbial growth. In the batch mode, 0.25 m3 of 12% bleach is injected into 1600 m3 every 3 days and in the continuous mode, the same amount (0.0035 m3/h) is continuously injected. The TBC11Total Bacteria Count in the cooling water before bleach, after batch and continuous bleach are 106, 104 and 103 cfu/mL, respectively. In fact, the performance of the continuous bleach is 10 times more efficient than the batch bleach. The physicochemical parameters including conductivity, NaCl%, TDS, pH, anions and cations concentration are not changed significantly and the chemical conditions are stable in both regimes which is proved that changing the bleach injection does not require the different chemical control. The free chlorine concentration in the continuous mode is constant (0.05 ppm) which is controlled the microbial growth and avoided the copper and iron corrosion.