Clean Co-production of H2 and power from low rank coal. (1st December 2016) - Aziz, Muhammad
Abstract: This work proposes a state-of-the art integrated system for the co-production of H2 and power from low rank coal with high total energy efficiency. A model of this system is developed based on enhanced process integration technology, incorporating coal drying, gasification, chemical looping, power generation, and hydrogenation. In this model, heat circulation and process integration technologies are effectively combined, minimizing the exergy losses. Iron-based materials are used as oxygen carriers and are circulated in a chemical looping module consisting of three continuous processes: reduction, oxidation, and combustion. The toluene-methyl cyclohexane system is employed as a liquid organic H2 carrier to store H2 generated from coal. The effects of the fluidization velocity in drying, the steam-to-fuel ratio in gasification, and the chemical looping pressure are evaluated with regard to the power generation and H2 production efficiencies as well as the overall efficiency, and the proposed integrated system exhibits very high efficiencies of approximately 12, 72, and 84%, respectively. Highlights: Energy-efficient co-production of H2 and power from low rank coal is proposed. Exergy losses are minimized by application of enhanced process integration. Drying fluidization velocity gives no significant impact to total energy efficiency. Steam-to-fuel ratio in gasification effects the amount of produced power and H2 . Higher chemical looping pressure results in higher power generation efficiency.