CENTRAL-FUEL-RICH SWIRL COAL COMBUSTION TECHNOLOGY IN 1 025 t/h LEAN COAL FIRED BOILER

Abstract

The central-fuel-rich (CFR) swirl coal combustion burner is given. With the enhanced ignition-dual register burner (EI-DRB), a 1 025 t/h coal-fired boiler could not achieve a stable flame when burning the designed lean coal. Experiments on a single-phase test facility and the boiler are done and the CFR burner matching the boiler is gotten. Experiments show that with the CFR burner the ratio of the largest diameter and length of the central recirculation zone to the outer diameter of the outer secondary air duct of the new burner are over 1.40 and 1.89. This central recirculation zone can provide enough high temperature gas to ignite pulverized coal. The EI-DRB has no central recirculation zone. It is the disadvantage of the flame stabilization. The influence of the rotational speed of the feeder and position of the secondary air damper on the distribution of the gas temperature in the burner region is gotten. With the CFR burners, the boiler operates stably at 140 MW without auxiliary fuel oil. The boiler could operate stably at rated or low load with burning lean-coal or the mixture of lean-coal and anthracite (the mixture ratio is 1). The emission of NOx of boiler decreases.