A new polygeneration system was established by combining coal pyrolysis with semicoke combustion, semicoke gasification and a steam Rankine cycle, and calculation approaches were developed to analyze the system. The energy and exergy efficiencies of the system were 683% and 76.8%, respectively. The standard energy quality factor alpha(theta) values of the 17 components and the energy quality factor alpha of each system stream were obtained based on the benchmark of the selected environmental reference state. The features of the energy grade of the components were elucidated according to their energy quality factors. And the exergy destruction processes in system blocks were exhibited and analyzed in combination with the concept of the energy quality factor. In the DRYER and PYRO, the majority of exergy destructions were used to pay the thermodynamic penalty of the increased energy grade of the coal. In the BUR and GASIF, the energy grade difference between the semicoke and output gas was the main cause of exergy destruction. Especially in the BUR, the energy grade difference was enormous and the exergy destruction was large. In HEX2, the average energy grade difference between Q(ED) and Q(EA) was the main cause of the exergy destruction. Finally, from the perspective of the energy quality factor, some potential improvements were analyzed to reduce the exergy destruction in the blocks. (C) 2017 Elsevier Ltd. All rights reserved.