EFFECT OF VARIOUS BIOWASTES ON EMISSIONS IN COMBUSTION OF LIGNITE COAL IN A CIRCULATING FLUIDIZED BED COMBUSTOR

摘要

In this study, combustion of biomass and coal was carried out in a circulating fluidized bed combustor. A lignite coal which has high sulfur content and three biomasses were used in the experiments. The biomasses were hazelnut shells; woodchips and olive cake which is a waste of olive oil industry. Olive cake is a quite common biomass in Mediterranean countries. The experimental setup consists of a circulating fluidized bed combustor column, a fuel feeding system, electrical heaters, and two cyclones. Its thermal capacity is 30 kW. The combustor column has an inside diameter of 108 mm and a height of 6 m. The temperatures along the column are observed with thermocouples located at specific heights. The temperature of the column is kept at 850 oC during the combustion experiments. The pressure drops along the combustor column, cyclone, downcomer, and loopseal are continuously measured and observed in order to determine the solid mass flux within the combustor. A series of combustion tests for each fuel was performed in order to investigate the effect of excess air ratio and secondary air ratio on the flue gas emissions and combustion efficiency. Optimum Ca/S ratio was determined for each combustion tests in order to minimize SO2 emissions. During the combustion experiments, CO2, CO, O2, NO, and SO2, emissions in the flue gas was continuously measured and recorded by Gasmet DX-4000 flue gas analyzer.