A combined heat, hydrogen and power tri-generation system based on the use of catalytic membrane reactors with a dual-loop organic Rankine cycle

Abstract

A dual-loop organic Rankine cycle (D-ORC) was used to recover waste heat from a biomass gasification process, for combined heat, hydrogen, and power (CHHP) generation. The process is based on the integration of biomass gasification with catalytic partial oxidation (CPO) and water-gas shift catalytic membrane reactors (WGS CMRs) for the simultaneous production and separation of hydrogen. The high temperature loop of the ORC was used to cool the CPO reactor effluent, while the low temperature loop was used to cool the WGS CMR retentate. Energy and exergy analyses were carried out to select the optima working fluids for this application. Hydrocarbons, siloxanes, hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs) were examined as potential candidates in this analysis. Results indicate that the highest efficiency was obtained when n-heptane and n-pentane were used as working fluids for the high and low temperature loops, respectively. Using this combination, electric and exergy efficiencies of 13.93% and 36.41% were computed, receptively. The process generates 1.37 kW of power, and produces 1.41 kg/hr of hydrogen at 773 K and 91.32 kg/hr of hot water at 363 K. The exergy analysis has also showed that the high temperature loop turbine and condenser have contributed the most, by around 32%, to the overall system irreversibility.