Biomass gasification process integration with Stirling engine, solid oxide fuel cell, and multi-effect distillation

Abstract

Today, the use of a variety of energy with the approach of maximizing the efficiency of energy systems is inevitable regarding the increasing trend of energy demand in the world. Process integration reduces the number of equipment required and energy consumption. In this paper, an integrated structure is developed that includes a solid oxide fuel cell (SOFC), a Stirling engine, an organic Rankine cycle (ORC), and a multi-effect distillation using biomass gasification. This integrated structure produces 3103 kW net power, 2.773 kg s−1 desalinated water, and 3.908 kg s−1 hot water by receiving 1000 kg h−1 of biomass. Total electrical and total exergy efficiencies of the integrated system were obtained as 62.88% and 51.56%, respectively. The SOFC and ORC cycles energy efficiencies obtained 53.19 and 22.29%, respectively. The SOFC unit and ORC system exergy efficiencies were calculated by 58.09% and 50.77%, respectively. The largest contribution of the exergy destruction rate occurs in the solid oxide fuel cell and the heat exchangers, accounting for 37.31% and 30.43%. In the performed parametric analysis, the effect of moisture content of gasifier input fuel on the performance of the system was evaluated. One of the most important results is the increase of the total electrical efficiency of the system to 70.81% in case of the increase of moisture to 40 vol%. The maximum amount of net generated power and SOFC generated power occur at 25 vol% moisture content of gasifier input fuel.