Flue Gas Recirculation. An Emission Control Technique for Industrial Boilers

Abstract or Introduction

It is now a well-established fact that air pollution has worsened over the years and the major credit goes to industrial growth. The boilers and stoves are one of the major sources of air pollution from the industries. Therefore, controlling their emissions to a significant extent can lead to the reduction of air pollution. The greenhouse gases of family NOx are important pollutants to be considered in this regard. As per the study by CPCB (2011), in Delhi, industry power plants contribute to approximately 65% of total NOx emissions. Therefore, control of this pollutant may not only lead to the air quality improvement in terms of NOx pollution but will also be beneficial to the environment as NOx cause many ecotoxic effects such as acid rain, eutrophication, ozone formation etc.

There are various emission control technologies available for NOx emissions, which can be categorized into two parts-Combustion Control and Post-combustion technologies in the particular context of boilers. Post-combustion methods are mostly expensive as compared to the combustion control methods and are usually not deployed for boilers having input less than 100 MM Btu/hr. So, the focus should be more on combustion control rather than post-combustion treatment. One such powerful method of combustion control is named Flue Gas Recirculation (FGR) which causes a significant reduction in NOx emissions by recirculating flue gases from the boiler exhaust duct into the main combustion chamber. The essay discusses details of the different aspects of this technology.