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Author Hazell, Daniel
Title Modeling and Optimization of Condensing Heat Exchangers for Cooling Boiler Flue Gas
book jacket
Descript 108 p
Note Source: Masters Abstracts International, Volume: 49-06, page:
Adviser: Edward K. Levy
Thesis (M.S.)--Lehigh University, 2011
A large amount of water is present in vapor form in the flue gas of a coal power plant. Reduction of total water usage in power plants is the goal of this investigation. A secondary goal is to recover the heat that exists in the flue gas and transfer it to the feed water for usage elsewhere. To accomplish both of these goals a heat exchanger is used with bundles of in-line circular tubes. Cooling water is pumped through these tubes and flue gas is forced around these tubes resulting in convective heat transfer. Eventually the flue gas temperature drops below the water vapor dew point and water is condensed out of the flue gas. In addition, heat is transferred from the hot flue gas (135°F -- 300°F) to the cooling water (90°F -- 105°F) that is being pumped through the tubes
A previously developed computer simulation code was modified to predict heat transfer, condensation and pressure drop through a full scale heat exchanger. The heat exchanger was designed to carry the load of a 550 MW power plant producing 6 million lb/hr of flue gas. Tube spacing optimization was carried out and it was determined that relatively small transverse spacings and large longitudinal spacings resulted in the best heat transfer to cost ratio
Heat exchanger cost consisted of capital cost and operating cost. Capital cost was considered as a function of tube material. Stainless steel 304 was the most cost effective material in regions of water condensation. Nickel Alloy 22 was the most effective material in regions before water condensation where there was sulfuric acid condensation
Two different operating locations for the heat exchanger were considered: downstream of an ESP unit and downstream of an FGD unit. Use of the heat exchanger downstream of the FGD unit gave better water condensation per cost and a better heat transfer rate per cost. Operating conditions and different flow rate ratios were considered and predicted condensation efficiencies of up to 59% were attained with some configurations
School code: 0105
Host Item Masters Abstracts International 49-06
Subject Engineering, Mechanical
Alt Author Lehigh University. Mechanical Engineering
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