Efficiency evaluation of dry hydrogen production from biomass gasification

The hydrogen production from biomass gasification needs to be improved through investigation of the operating parameters and thermodynamic efficiencies (energy and exergy). A comprehensive study is conducted to predict H-2 production with a gasifier using a quantity of 14.5 kg/s from biomass (wood sawdust) and an amount of 6.3 kg/s of steam at 500 K and evaluate system performance through energy and exergy efficiencies for hydrogen production from biomass. The gasification process takes place in a temperature range of 950-1500K and steam-biomass ratio of 0.17-0.51. The results indicate that an improvement in exergy efficiency from 33 to 37% is possible during hydrogen production only. It becomes more sensitive if the temperature goes beyond 1000K. In this regard, the exergy efficiency increases from 42 to 47% when all of the product gases are taken in consideration and from 47 to 52% when all of the products from the gasification process are taken in consideration. Over a range of gasifier temperatures, the gasification ratio is 97-105g H-2/kg of biomass while hydrogen yield reaches 1.5 kg/s for the studied biomass. (C) 2010 Elsevier B.V. All rights reserved.