PF flow meter demonstration trials on a 500 MWe boiler

Since the installation of low NOx burners, the optimisation and control of PF distribution and PF size distribution have assumed greater significance. Balanced PF distribution and satisfactory fineness are two of the fundamental criteria for effective low NOx burner operation in terms of both NO, and combustion efficiency (carbon in ash). Maldistribution of fuel between burners caused by fuel roping leads to uncontrolled differences in the fuel to air ratio between burners. This results in localised rich and lean regions in the furnace leading to unacceptably high levels of unburned carbon. This leads to difficulty in meeting stringent emission levels, boiler efficiency loss and potential loss of ash sales due to increased carbon content Presently extractive sampling techniques are used for assessing fuel distribution; however, such approaches can only provide data as a spot reading over a limited period and fail to show the dynamic nature of fuel distribution. Accurate measurement of pulverised fuel/airflow has been a long-standing problem for utility operators. Recent years have seen developments from a number of manufacturers that could potentially provide operators with the information to fully optimise the coal combustion process