Experimental Study on a Ceramic Membrane Condenser with Air Medium for Water and Waste Heat Recovery from Flue Gas.

Heng Zhang,Liansuo An,Guoqing Shen,Da Teng,Shiping Zhang

doi:10.3390/membranes11090701

Abstract

Ceramic membrane condensers that are used for water and waste heat recovery from flue gas have the dual effects of saving water resources and improving energy efficiency. However, most ceramic membrane condensers use water as the cooling medium, which can obtain a higher water recovery flux, but the waste heat temperature is lower, which is difficult to use. This paper proposes to use the secondary boiler air as the cooling medium, build a ceramic membrane condenser with negative pressure air to recover water and waste heat from the flue gas, and analyze the transfer characteristics of flue gas water and waste heat in the membrane condenser. Based on the experimental results, it is technically feasible for the ceramic membrane condenser to use negative pressure air as the cooling medium. The flue gas temperature has the most obvious influence on the water and heat transfer characteristics. The waste heat recovery is dominated by latent heat of water vapor, accounting for 80% or above. The negative pressure air outlet temperature of the ceramic membrane condenser can reach 50.5 °C, and it is in a supersaturated state. The research content of this article provides a new idea for the water and waste heat recovery from flue gas.

Highlights

As of 2018, s third of the world’s electricity is supplied by coal, especially in China, where coal-fired power generation accounts for up to 69%
The flue gas temperature is reduced to 55~60 ◦C, so direct discharge of flue gas will cause a large amount of water and waste heat loss [3]
In the traditional 330 MW coal-fired power plant, the flue gas temperature at the outlet of the wet desulfurization tower is 55 ◦C, so the low-temperature waste heat loss caused by the discharge of wet saturated flue gas is 484 GJ/h, which is equivalent to wasting 16 t/h standard coal according to the calorific value

Summary

Introduction

As of 2018, s third of the world’s electricity is supplied by coal, especially in China, where coal-fired power generation accounts for up to 69%. The flue gas temperature is reduced to 55~60 ◦C, so direct discharge of flue gas will cause a large amount of water and waste heat loss [3]. In the traditional 330 MW coal-fired power plant, the flue gas temperature at the outlet of the wet desulfurization tower is 55 ◦C, so the low-temperature waste heat loss caused by the discharge of wet saturated flue gas is 484 GJ/h, which is equivalent to wasting 16 t/h standard coal according to the calorific value. The lower moisture content in the flue gas will help promote the dissipation of pollutants in the flue gas and reduce “gypsum rain” around coal-fired power plants [6]. Water and waste heat recovery play an important role in enhancing energy efficiency, reducing water consumption, and improving the environment of coal-fired power plants

Methods

Results

Conclusion