Surface condensers are used when vapors condensed should not enter into the cooling water circuit, in order to recover them and avoid contamination of the cooling water system.
SURFACE COOLER - CONDENSERS
Surface coolers condensers Characterized because the vapor, usually water and hydrocarbons, goes in with a considerable quantity of no condensable gases, witch must be cooled so much as possible in order to keep the vapors contents of gases flowing to the following ejector stage beyond certain limits. In the condensation of vapors from a mixture with no condensing gas, the two fase composition vary greatly along the bundle as water vapor is removed, so that the transport properties of liquid and the vapor and gas mixture. The rate of condensation depends upon the diffusion of vapor through the no condensing gas as well as the heat transfer of gas and liquid films. So that the design of cooler condenser presents unusual troubles and requires very elaborated methods.
Are normally used as pre, inter and post-condenses in vacuum systems of oil refineries. The condensers may be stationary or floating head according to the service. The usual shells are the type E (TEMA classifications) for little sizes, type J for medium sizes and type X for big ones.