Polygeneration of liquid fuels and electricity by the atmospheric pressure hybrid solar gasification of coal

Abstract

An analysis of system operation and performance has been undertaken, for the first time, of a solar-hybrid coal-to-liquids polygeneration facility incorporating solar resource variability. The energetic and environmental performance of a coal-to-liquids process that is integrated with a solar hybridized, oxygen blown, atmospheric pressure gasifier (CTLsol) is compared with that of a reference, nonsolar, autothermal, pressurized gasification integrated, CTLref configuration. To allow the plant to respond to solar resource transience, pressurized storage of upgraded syngas and oxygen is incorporated into the proposed CTLsol system. The CTLsol process is simulated using a dynamic model that assumes pseudosteady state operation at each time-step, for a 12-month, hourly averaged solar insolation time-series. Both the CTLsol and CTLref systems were modeled using AspenPlus and Aspen HYSYS (v 7.1) software. The analysis of the CTLsol system’s performance showed an annually averaged improvement of 21% to the total energetic output and a reduction of 30% in the mine-to-tank greenhouse gas emissions relative to the CTLref system assuming equilibrium gasification conditions of 1400 °C and 1 bar-a. The integration of a pressurized syngas storage facility was shown to enable the CTLsol system to allow the variation in throughput of each unit of process equipment to be maintained within normal operational ranges despite the fluctuations in the transient solar input to the solar-hybrid coal gasification process.