The principle and scheme of selective control on process variables of LPG absorbing tower by use of DCS is explained in detail, including the selection and implementation of field instrument.

This article introduces the design principle,process flow,chlorine water-seal tank and chlorine absorption tower.

According to the problems which would happen when the waste-gas adsorption tower in the poly-unit of the plant is running,this paper analyses the reasons and offeres some developing suggestions.