Pilot-scale study on combustion characteristics, slagging characteristics and flue gas composition of coal oilfield wastewater slurry

As the volume of oil extraction continues to rise, the issue of oilfield wastewater treatment has become increasingly urgent. Traditional water treatment technologies struggle to effectively and economically eliminate the pollution caused by oilfield wastewater, as well as efficiently utilize its various components. This study proposes the utilization of oilfield wastewater for the preparation of coal water slurry, and the combustion experiments of coal oilfield wastewater slurry (COWS) and original coal water slurry (CWS) under various working conditions are conducted on a pilot-scale horizontal furnace. The investigation focused on the combustion characteristics, slagging characteristics and flue gas composition, as these indicators directly impact the industrial application of such slurry fuel. The combustion characteristics results reveal that both COWS and CWS demonstrate stable ignition and combustion across all working conditions, with combustion efficiency exceeding 99.69%, and the incorporation of oilfield wastewater promotes volatiles precipitation and combustion. The slagging characteristics results indicate that the flame temperature within the furnace is critical in determining slagging occurrence, and the incorporation of oilfield wastewater increases the likelihood of slagging. The flue gas composition measurement results indicate that the incorporation of oilfield wastewater slightly elevates carbon monoxide (CO) levels, albeit within a low concentration range. Additionally, oilfield wastewater demonstrates a modest reduction in sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions. These test results underscore that incorporating oilfield wastewater into the preparation of fuel coal water slurry not only facilitates thorough treatment of oilfield wastewater, but also enhance the combustion performance of slurry fuel within the furnace, thereby offering significant industrial application potential.