The cooling down of the gas stream to be cleaned is here carried out in direct contact with the cooled liquid in the liquid jet. The liquid itself is set to the desired temperature by indirect cooling, usually in a heat exchanger.
Due to the continuous input of liquid the phase boundary interface between the gas and the liquid is constantly renewed. The intensive contact brings about a washing, absorption and/or condensation effect and hence an exchange of matter between the gas and the liquid. The waste gas cools down to the condensation temperature and the pollutants and solvents contained in the waste gas condense as far as the saturation conditions. The condensate mixes with the liquid supplied and is collected together with the spray jet in the machine sump. The increase in liquid is drained via a filling level controller and the cleaned gas stream is discharged via a specially designed demister.
The condensing system can, if required, also be designed for operation in discontinuous processes (batch processes) and for variations in the waste gas flow rate. The technology is frequently applied as a pre-separator or quencher in the case of highly laden or very hot gas streams as a preliminary stage of further cleaning processes and can also be used for applications in closed waste gas systems (e.g. of a dryer or coating System).