Hydrocarbon dew-point control in natural gas.
Before entering distribution pipelines, natural gas needs to be treated to assure that during transportation the gas will not liquefy. The treatment consists of removal of valuable higher hydrocarbons. Technologies to remove higher hydrocarbons include low temperature separation, mechanical refrigeration adsorption and membrane treatment.
Most suitable membranes are membranes with much higher permeability for high hydrocarbons than for methane and ethane. Higher hydrocarbons can be collected from the permeate stream, leaving a lean product gas with low dew-point.
Feed gas = Raw natural gas
Retentate gas = Purified natural gas, mainly CH4
Permeate gas = Higher hydrocarbons