BIOMASS REACTIVITY IN GASIFICATION BY THE HYNOL PROCESS

A thermobalance reactor was used to evaluate the reactivity of poplar wood during gasification under operating conditions specific for the H ynol process where biomass is gasified at 30 atm and 800 degrees C wit h a hydrogen-rich gas recycled from methanol synthesis. The gasificati on involved a rapid devolatilization and pyrolysis reaction of the vol atile matter in biomass and a slow reaction of residual carbon with th e process gas. Nearly 86% of 1/8-in. poplar particles and 90% of sawdu st were converted into gas products by a feed gas corresponding to the Hynol process (66% H-2) in 60 min. About 4% additional conversion of the 1/8-in. particles was obtained when gasification time was extended from 60 to 150 min. Gasification rate and biomass conversion were str ongly affected by reaction temperature and particle size. The conversi on was proportional to the partial pressures of H-2 and steam in the f eed gas. A kinetic model was developed to correlate the experimental d ata and quantitatively express gasification rates and biomass conversi on as functions of reaction time. The activation energies for the rapi d and slow reactions were estimated to be 3.8 and 34 kcal/g-mol, respe ctively.