Development of an integrated membrane condenser system with LNG cold energy for water recovery from humid flue gases in power plants

Abstract

This paper investigates a detailed thermodynamic analysis of a modular-type membrane condenser system where a cooler or condenser is connected in series upstream of the membrane condenser module. A coolant circulates inside the cooler/condenser to cool down the industrial flue gas up to saturation conditions. The analysis covers water recovery rate and energy requirement for different combinations of flue gas humidity, flow rate, and temperature. Additionally, a case study is included which considers a practical industrial exhaust flue gas where the constituents of the flue gas with volumetric ratio and the feed parameters are referred from the literature. The case study investigated the utilization of cold energy obtained by LNG regasification facility as a cooling power source for the water vapor recovery process. A detailed heat transfer analysis based on the heat exchanger model is performed to determine the required mass flow rate of cooling water and natural gas. It is concluded that, the water self-sufficiency of a power plant can be achieved if the mass flow rate of the −50 °C natural gas which is entering the membrane condenser is kept around 0.3 kg s−1 for every 1 kg s−1 flow rate of the 168 °C flue gas.