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Show This paper will review the technical background for this equipment, effect of various operating parameters, describe generic equipment designs, evaluate applications for the low level heat and estimate the energy saving potential from widespread acceptance of this heat recovery technique. Although the primary emphasis will be on industrial boiler applications, the use of similar techniques for heat recovery from dryers or slurry heating will also be discussed. BACKGROUND The principle behind the condensation heat recovery is direct contact gas-liquid heat exchange between the boiler flue gas and a cold water stream. The process is illustrated schematically in Figure 1. The flue gas enters the unit at 300°F, or more, depending on the boiler operating conditions and is discharged at 100-120°F. The flue gas is cooled by direct contact with a cold water stream whereby part of the sensible and latent heat content of the flue gas is recovered. The operation is similar to a typical cooling tower operating in reverse. In this equipment a hot gas is cooled and the heat recovered is used to provide a hot water source as opposed to a cooling tower where a gas stream is heated and the hot water stream is cooled. The heat recovered from the flue gas can be transferred through a secondary heat exchanger to the process fluid being heated. Consequently, the heated fluid produced by the system would not have to be in contact with the flue gas if this contact would cause contamination. With clean-burning natural gas, the water used in the DCCHR heat exchanger can often be used directly in the process since quite often the small amount of acid contamination is acceptable. Other industrial process equipment where direct contact heat exchangers have been applied are reaction gas quenchers, compressor inter-coolers, fractionator condensers, adiabatic humidifiers, feed gas desuperheaters, barometric condensers, feedwater heaters, steam desuperheaters and submerged combustion evaporators. Consequently, the process of direct contact heat exchanger has been widely applied and its extension with the 9-4 KVB10-P-281 |