Thermodynamic analysis of a combined Organic Rankine Cycle (ORC) with Proton Exchange Membrane Electrolyzer (PEME) in an integrated biomass conversion system

The energy content of product gas obtained from biomass gasification requires further processing to reach equivalent standards of natural gas. The product gas is produced at high temperature and undergoes cooling in a heat exchanger system prior to a cleanup process. This study presents the thermodynamic modelling of an integrated biomass to energy plant composed of a gasifier and digester, integrated with an Organic Rankine Cycle (ORC) and a Proton Exchange Membrane Electrolyzer (PEME) configuration for syngas upgrade. Thermal energy from steam at 290°C obtained from the syngas cooling process in view of waste heat recovery is utilized in the ORC for power generation, and as an energy source for the PEME. Six potential ORC working fluids aiming a maximum power generation of the ORC system are considered: R1243zf, R1234ze(Z), R1234yf, R1233zd(E), Isobutane, and Propane. R1233zd(E) is identified as most suitable working fluid with power output of 280.6kW and a thermal efficiency of 19.23 % for ORC configuration with regenerator. An increase in the flow rate of hydrogen resulted in a raise in the power consumption of the PEME, and a corresponding decrease of the ORC net power for each working fluid. Hydrogen gas produced from the PEME was used in upgrading the product gas from the gasification and anaerobic digestion processes through methanation model to comparable natural gas standard. The composition and lower heating value of upgraded product gas was 97.18% CH4, 2.82% H2, and 50.03 MJ/kg, respectively. The efficiency of the PEME was 88.79% with hydrogen gas rate of 0.51kmol/s. In further work, the process parameters will be optimized via multi-objective approach under thermo-economic aspects.     «

The energy content of product gas obtained from biomass gasification requires further processing to reach equivalent standards of natural gas. The product gas is produced at high temperature and undergoes cooling in a heat exchanger system prior to a cleanup process. This study presents the thermodynamic modelling of an integrated biomass to energy plant composed of a gasifier and digester, integrated with an Organic Rankine Cycle (ORC) and a Proton Exchange Membrane Electrolyzer (PEME) configu...     »