Abstract
The fuel staging combustion technology is a promising low NOx combustion technology for coal-fired boiler. In order to reduce NOx emissions, the burners of a 600 MWe coal-fired boiler are retrofitted in which methane gas is selected as a secondary fuel for re-combustion. The CFD models of combustion process are built to investigate effects of the methane gasratio on combustion process and NOx emissions. A total of 4 cases are numerically studied, including the pure coal combustion case, the coal combustion with 7.5%, 10%, 12.5% of methane gas re-combustion cases respectively. The results show that the re-combustion of methane can reduce the temperature at primary combustion zone, but increase the temperatures at the re-combustion area and the furnace outlet. The NOx concentration at the furnace outlet reduces with the increasing methane gas ratio. Methane re-combustion can greatly benefit to the NOx emissions reduction.
Highlights
The past many years have seen the emergence of a growing desire worldwide to take actions to protect the environment from the degrading effects of all forms of pollution
The results show that the re-combustion of methane can reduce the temperature at primary combustion zone, but increase the temperatures at the re-combustion area and the furnace outlet
Glarborg et al carried out a study on the re-combustion characteristics of biomass gas, the results showed that, a higher methane concentration can lead to the greater NOx reduction rate at the excess air coefficient of 0.9 in re-combustion zone [8]
Summary
The past many years have seen the emergence of a growing desire worldwide to take actions to protect the environment from the degrading effects of all forms of pollution. The low NOx combustion and the flue gas de-nitrification technologies are the main methods to reduce nitrogen oxide emissions from coal-fired boilers. This technology reduces NOx emissions by setting up a less oxygen-burning section in furnace to restore a part of NOx to N2 [3] [4]. Glarborg et al carried out a study on the re-combustion characteristics of biomass gas, the results showed that, a higher methane concentration can lead to the greater NOx reduction rate at the excess air coefficient of 0.9 in re-combustion zone [8]. Shi et al studied the effect of methane on the mixing characteristics of gas re-combustion in a coal-fired boiler [9]. The results can provide a theoretical basis for retrofitting old units in service aiming NOx emission reduction
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
