Power plant waste heat rejection and utilization options
Abstract
Process waste heat in large power generation plants is commonly rejected to lakes or rivers, or through the use of cooling towers. Although these waste heat rejection methods are quite effective, they may not be feasible in every application due to cost considerations or geographic location. Moreover, it is desirable to use the waste heat in additional processes, if possible, both from the standpoint of improved plant efficiency as well as reduced environmental impact. A comprehensive analysis of alternative methods of power plant waste heat rejection is presented here. Six approaches for rejecting or recovering the waste heat are considered: cooling canals, open-water algae bioreactors, wintertime greenhouse heating, spray ponds, modified solar towers, and updraft towers with heat exchangers. Each of the six technologies can be sized for the needs and operating conditions of a given power plant. The quantitative analysis tools developed in this work are validated by benchmarking against published results. Four of the alternative methods generate secondary benefits: the algae bioreactor, greenhouse heating, the modified solar tower, and the updraft tower with a heat exchanger produce biodiesel, extended periods of horticulture, and electric power, respectively. The Hoosier Energy power plant in Merom, Indiana is used as a case study for each alternative method of waste heat rejection. Each technology is designed to reject 332 MW of waste heat from the Merom plant. This heat rejection load is selected for the comparison as it represents the amount needed to lower the temperature of the waste water issuing from the power plant by 5 degrees Fahrenheit, a goal determined by Hoosier Energy to maintain a healthy habitat for the aquatic species residing in the reservoir. A comparison of the land footprint required to reject the 332 MW of heat using each of the alternative technologies is discussed. The sensitivity of the sizing of the different technologies to changes in the environmental and geometric parameters is quantified. Each technology presented here is a viable means of heat rejection from Hoosier Energy’s Merom power plant.
Degree
M.S.M.E.
Advisors
Garimella, Purdue University.
Subject Area
Mechanical engineering|Environmental engineering
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