Influences of Component Cost Changes on the Optimum Design of Large Natural Draft Dry Cooling Systems

摘要

Various cost components of a large natural draft dry cooling system are identified: tower, heat exchanger, headers, condenser, pumps, auxiliary power loss, and cost due to high heat rate. An analysis is presented for heat exchanger area, tower exit area, and exchanger tube length and number, for a system using spine-fin heat exchanger. Calculations are made over a range of design parameters, but four of these parameters (approach, water pumping power, ITD, and heat rejection rate) are chosen for the economic optimization of the entire system. The headers, condensers, and pumps are sized. The auxiliary power loss and effects of high heat rate are determined. The various cost components are summed up to obtain the total cost of the cooling system in terms of the four chosen parameters and the various cost coefficients. The total cost of the system is optimized with respect to the four chosen parameters. A sensitivity analysis is carried out by determining the effect on the optimum cost of independently varying each of the cost components. The result is a ranking of the components in terms of how much improvement could be made in the overall cost of the cooling system by an improvement of each of the various components.