Performance analysis of ceramic membrane tube modules for water and heat recovery in coal-fired power plants

Abstract

Ceramic membrane separation technology is a promising method for water and heat recovery from exhaust flue gas in thermal power plants. Matching among function, load and structure of membrane modules is critical to design and operation of such recovery processes. In this paper, an analytical model based on membrane separation mechanism is proposed to evaluate the water and heat recovery performance in a ceramic membrane module. A series of calculation considering both structural parameters and load conditions in a power plant is conducted. Results show that under the conditions of different flue gas temperature and water vapor volume fraction, the membrane module has three working modes corresponding to different condensation processes. For flue gas with high temperature and low humidity, the temperature rise of cooling water can reach up to 40 °C when the mass flow rate ratio of cooling water to flue gas is less than 50%. For flue gas with low temperature and high humidity, low cooling water temperature could promote water recovery process. Keeping the mass flow rate ratio higher than 200% can maintain the water recovery rate not less than 60%. The optimal water and heat recovery rate is obtained by optimizing the size and structure of the membrane module within limited volume. This study provides a basis for structure optimization and operation regulation of ceramic membrane modules for water and heat recovery purpose.