(286h) Coal Topping Pyrolysis Process: Fundamentals and Its Application

Coal is the main energy resource in China, accounting for 68% of the primary energy consumption. However, with the rapid development of economy and the increasing enviromental concern, the demanding of oil and natural gas has dramatically increased in recent decades. To cope with the energy situation, a coal topping process was put forward by Institute of Process Engineering, Chinese Academy of Sciences. The aim of this process is to obtain a high yield of light liquid fractions and gaseous products by flash pyrolysis. The remain char is combusted to provide heat to the pyrolysis system. One of the technical routes to realize this process is to use the circulating fluidized bed (CFB) system. In the CFB system, coal is firstly pyrolyzed in the downer. The char is combusted in the riser. The hot ash is circulated between the riser and the downer as heat carrier. Influence factors including pyrolysis temperature and coal particle size were investigated in a lab-scale fluidized reactor. Combustion properties of the char obtained in the pyrolysis system were evaluated in the drop tube reactor and thermal gravimetric analyzer, respectively. On a basis of the experimental data obtained in the lab-scale facility, the process capacity was scaled up to 10t/d. A continuous test was performed to optimize the process. Further, a 2t/h pilot scale facility was constructed, which is integrated with a 75t/h CFB boiler in a thermal power plant. The results from the lab-scale and pilot-scale facilities were compared.