Abstract: The coal-fire power plant located in the coastal are autilized the technology of natural draft cooling tower with flue gas injection and takes, the sea water into its recirculating cooling system. Both the static test and the dynamic simulation test of the scale inhibitor for the recirculating water were performed to ensure the safe, reliable and economic operation of the recirculating water system. WS330 phosphate-free scale inhibitor was used as the scale inhibitor for the recirculating water. The dosage of the scale inhibitor was determined through the static test, and then the simulation tests regarding various performance indices were carried out on the dynamic stimulation device. The test result reveals that the system functions normally if the mass concentration of the WS330 scale inhibitor is maintained at 8 mg/L and the concentration ratio is less than or equivalent to 2.5. With the corrosion rate of the titanium heat exchanger 2.5×10^-5 mm/a, the average adhesion rate 0.33 mg/cm² per month and the fouling resistance 1.4×10^-5 m²·K/W, all the indices above are far below their upper limits. Considering the fluctuation of the water quality and load, it is recommended to maintain the concentration ratio of this system at the range of 1.5~2.0 under normal operations. Finally it is concluded from the analysis that the natural draft cooling tower with flue gas injection had limited impacts on the concentration ratio in the cooling system using seawater as the recirculation cooling water.

Key words: coal-fired power plant, natural draft cooling tower with flue gas injection, recirculating cooling water, phosphate-free scale inhibitor, static test, dynamic simulation, critical concentration cycle