Industrial measurement of combustion and NOx formation characteristics on a low-grade coal-fired 600MWe FW down-fired boiler retrofitted with novel low-load stable combustion technology

•A novel low-load stable combustion technology is applied on a 600MWe FW down-fired boiler.•33% rated load stable combustion without oil support is achieved.•Full-scale industrial measurements are carried out at 200, 240 and 540MWe.•Combustion and NOx formation characteristics at high and low load arecontrastivelystudied.