Performance of a Condensing Heat Exchanger in Recovering Waste Heat from aNatural Gas-Fired Boiler

摘要

The performance of boiler heat exchangers is limited by the need to keep the fluegas temperature above its dew point to avoid condensation of corrosive acids. However, latent heat can be recovered at temperatures below the dew point of the gas by protecting the heat exchanger tubes from the acids. A new Teflon covering process demonstrates significant advantages over older coating technologies. To evaluate the effectiveness of this new Teflon covering for use in Army boilers, researchers selected the Louisiana Army Ammunition Plant (LAAP) as a demonstration site. A natural gas firetube boiler with a nominal firing rate of 20.5 million British thermal unit per hour (MBtu/h) and less than 10 percent condensate return was fitted with a Teflon-covered condensing heat exchanger to preheat makeup water. Tests were run to determine fuel consumption with and without the heat recovery system operating. Keywords: Heat exchangers; Boilers; Waste heat; Teflon. (jes)