SIMULATION OF HYDROGEN PRODUCTION FROM BIOMASS PYROLYSIS GAS BY SECONDARY STEAM REFORMING

摘要

Hydrogen is currently being widely regarded as a futural energy carrier to reduce carbon emissions and other NO_x and SO_x pollutants. Many researchers have proved that hydrogen can be efficiently used in solid oxide fuel cells -gas turbine system (SOFC-GT) and molten carbonate fuel cells-gas turbine system (MCFC-GT). Hydrogen production from biomass resources offers the advantage of providing a renewable energy carrier for extensive reduction of the CO_2 emission. A secondary steam reforming process which consists of steam reforming of methane and water gas shift was proposed to further convert CH_4, CO and other hydrocarbons in biomass pyrolysis gas for promoting hydrogen yield. According to respective reaction mechanism, simulating calculations were carried out in two reforming processes separately. With the favor of PRO/II, the effects of reaction temperature and steam to carbon ratio on hydrogen yield were discussed in details in the steam reforming of methane. A reasonable calculation method was established for simulating the water gas shift process in which the effects of temperature and steam to CO ratio was investigated. The simulation made good results in optimizing reaction conditions for two reformers and predicting the volume rate of all gas components. It is proved by simulation that hydrogen-rich gas with >68 mol% H_2 could be produced, and the hydrogen yield could reach 48.18 molH_2/(Kg Biomass) and 45.85 mol/(Kg Biomass) respectively when using corn straw and rice husk as feedstock. The experiment data from a related reference was adopted to prove the reasonability of the simulation results which could show the feasibility of secondary steam reforming process, as well as provide good references for practical process operation.