The Large Capacity Pulverized Coal Fired Utility Boiler and the Low NOx Combustion Technology Developments in China in Response to Environmental Challenges

Abstract

Large capacity pulverized coal fired utility boiler technology is in quick developments in China, hundreds of super critical boilers have been constructed in the last several years which can achieve high efficiency and low pollutants emissions. The different types of super critical boilers are introduced in this paper, they include the single-furnace with double fireball corner fired furnace, the wall fired furnace and the tower-type furnace. The low NOx combustion technologies have been widely used to face the environmental challenges. The low NOx technologies employed in pulverized-coal boilers consist of the combustion modification and post-combustion technology. The low NOx combustion modification technology includes the low NOx burner, close coupled over fire air (CCOFA) and separated over fire air (SOFA). The post-combustion technology consists of selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) technologies. Zhejiang University develops integrated low NOx technology, including the low NOx combustion system, SNCR system and SCR system. This integrated technology can reduce the NOx emissions to be lower than 50 mg/Nm3.