Pyrolysis-Bridged Hybrid Power Systems and Their Application for Thermal Power Plants

Abstract

A hybrid power system based on coal pyrolysis and steam integration is proposed to improve the performance of power plants. The most outstanding features of the system are a pyrolysis process integrated with a circulating fluidized bed boiler and power generation by the steam integration. The model of the hybrid power system is set up by THERMOFLEX software and Aspen Plus. Results show that the thermal efficiency of pyrolysis process can achieve values of 90%–95%, and the majority of the energy used by the pyrolysis is consumed during the drying and quench processes. Compared with a conventional steam cycle power system, the gross electric efficiency and thermal efficiency of the new system are increased by 1.9% and 5.1%, respectively. Energy and exergy analyses are presented to study the performance differences of two systems. Exergy destruction of the boiler with steam integration is decreased in the new system. Exergy destruction of gas turbines is lower than that of the boiler. Although additional exergy loss occurs in the pyrolyzer and heat recovery steam generator, the overall exergy loss of the new system is less than that of the conventional system.

Multifluid Modeling of Coal Pyrolysis in a Downer Reactor

“…Fast pyrolysis is one efficient method for the thermochemical conversion of low-rank coals. Recent studies have shown that fast coal pyrolysis followed by gasification and combustion of the generated char is a more effective and environmentally friendly method for low-rank coal utilization compared with those of direct combustion. − …”

Effect of hydrogen-rich gas from char gasification on rapid pyrolysis products of low rank coal in a downer pyrolyzer

“…Poly-generation technologies combining low-and-mid temperature pyrolysis with combustion or gasication have been developed to implement the pre-extraction of volatiles from coal. [4][5][6][7] In most of these processes, coal is rst fed to a pyrolyzer to extract volatiles, and then the resulting char is sent to a combustor or gasier for heat/power or syngas production. Between the two reactors, hot ash from the combustor or gasier supplies heat for coal pyrolysis.…”