Emission characteristics of co-combustion of a low calorie and high sulfur-lignite coal and woodchips in a circulating fluidized bed combustor: Part 1. Effect of excess air ratio

The results of the tests showed that increasing excess air had a cooling effect on the combustor, but at the same time it also provided smoother temperature profile along the combustor. In order to get minimum flue gas emissions, the optimum excess air ratios for the co-combustion tests of fuel mixture including 10%, 30% and 50% by wt. of woodchips were determined to be 1.18, 1.32 and 1.41, respectively. While woodchips addition to the lignite made CO emissions worse, it did not change NO emission. CO and NO emissions were below the limits but SO2 emission was above the limit for the case of 10% and 30% woodchips co-combustion at optimum excess air ratio. In the case of 50% woodchips co-combustion, SO2 and NO emissions were under the limits but CO emission was a little above the limit at optimum excess air ratio.