The search for optimum condenser cooling water flow rate in a thermal power plant

Heat losses from the thermal power plant cycle are due mainly to heat rejection through the condenser. Operating the condenser at optimum circulation water flowrate is essentially important to ensure maximum efficiency and minimum operating cost of the plant. In this study, computer program codes were developed in Microsoft Excel macros for simulation of a thermal plant at various circulation water flowrate, to determine the optimum condenser cooling water flowrate for the process. The study revealed that operating the condenser at reduced cooling water flow rate of 32,000 m 3/h instead of the base case scenario of 32,660 m 3/h, reduced the total heat transfer area requirement from 13,256 m 2 to 8,113 m 2, with the condenser making the highest contribution to heat transfer area reduction. The annualized capital cost also reduced to $12,271,064.30/yr from $16,809,876.50/yr. There was 2% increase in the cycle efficiency and fuel saving of 3.8% was achieved. The economic implications of heat recovery improvement were modifications to the air ejector, gland condenser, and replacement of the drain cooler, low pressure heater and high pressure heaters. The fixed capital for plant modification was $4,694,220.96 with payback period of 1.8 years. ► Reduction in cooling water flowrate reduces total heat transfer area requirements. ► Reduced cycle heat loses increase cycle efficiency and fuel saving. ► Water cooled thermal power plant is sensitive to cooling water inlet temperature. ► Heat recovery improvement results in equipment modification.