Calculation of Reactor Characteristics and Techno-Economic Assessment of a System for Hydrogen Production from Biomass Using Gasification in Chemical Cycles

The calculation method developed by the authors is supplemented by the heat balance of a circulating fluidized bed (CFB) reactor for burning coke residue in a CFB reactor‒gas-generator system. The following options are examined: with the supply of additional dried fuel to the reactor as an alternative method for keeping the required gasification temperature of particles at the CFB reactor outlet and application as a fuel of a mixture of wood biomass and Kuznetsk coal benefication products. The thermal cycle of the plant has been modified as applicable, and the calculation results are presented. It has been demonstrated that gasification of a mixture of biomass and coal benefication enables increasing the overall system capacity (production of hydrogen + electricity) without a considerable growth in the biomass consumption. In this case, the hydrogen production decreases, and the hydrogen production efficiency drops but the efficiency of electricity generation rises. The hydrodynamic calculation of CFB reactors was performed to attain the specified flowrates of circulating material required to maintain proper temperatures in the reactors. The flowrate of circulating particles can be increased by increasing the pressure difference (loading level or weight of material in the reactors). The overall dimensions of the reactors have been determined, and their layout is presented. A procedure for calculating capital and operating expenditures is outlined, and these expenditure components are estimated. The cost of hydrogen production using biomass without CO₂ emission over the life cycle of the plant was estimated (USD 1.45/kg). Approximately 2/3 of the formed CO₂ is already ready for storage. Therefore, we have only to remove CO₂ from the flue gas flow from the CFB reactor of the gas generator. This level corresponds to available foreign data on similar plants operating on natural gas and is lower than that provided by the widely used technology of steam reforming of natural gas with CO₂ capture.