EXPERIMENTAL STUDY ON AM-STAGED COMBUSTION IN A W-SHAPED BOILER FURNACE

The experimental study was carried out on the air-staged combustion of different coal in a 1 MW W-shaped furnace. The combustion process occurred in two zones: the pre-stage combustion zone and the primary combustion zone. A variable SR was introduced to represent the air stoichiometric ratio in the pre-stage combustion zone. It is found that as SR decreases in the test range, the flame penetration depth is lengthened, and the temperature at the exit of the furnace decreases. Meanwhile, the maximum temperature in the central of the furnace first increases and then decreases, whereas the combustible loss and nitrogen oxides (NO,) emissions first decrease and then increase. The value of SR corresponding to the optimal combustion performance is 0.67 for lean coal and 0.65 for anthracite. Besides, it is also indicated that the effects of air-staging method are more significant on the lean coal than that on the anthracite.