Energy conservative brown coal conversion to hydrogen and power based on enhanced process integration: Integrated drying, coal direct chemical looping, combined cycle and hydrogenation

An integrated system for converting brown coal to H2 and power is proposed. This system consists of coal drying, coal direct chemical looping, combined cycle, and hydrogenation. The energy involved in each module is recirculated thoroughly before it is integrated with the other modules, meaning that any unrecoverable energy can be utilized in other modules. In coal direct chemical looping, three continuous reactions are employed, namely, reduction, oxidation, and combustion. Iron oxide is used here as the oxygen carrier that is recirculated among the reactors. Toluene is adopted as the organic carrier in the hydrogenation process, reacting with H2 to produce methylcyclohexane. We evaluated the performance of the system through a selection of operating conditions. The effect of the carbon conversion efficiency during the reduction was also clarified. The proposed system achieved high values for the production of H2 and power generation efficiencies, which are 71.4% and 19.9%, respectively.