Zhang Yaning

Exergy Analysis of Biomass Gasification with Steam/Air: A Comparison Study

Biomass gasification with steam/air is compared from an exergetic aspect. The comparison details include the exergy efficiencies of the product gases, tar, char and the lost part from the same biomass of both steam gasification and air gasification. Some conclusions can be obtained from the results. In the temperature range from 800¿ to 1200¿ analyzed in this paper, exergy efficiencies of both steam gasification and air gasification have the same changing tendency: gas exergy efficiency increases, while exergy efficiencies of tar and char decline. On the while, the exergy efficiencies of gases, tar and char of steam gasification are higher than that of air gasification. From this aspect, steam gasification is a better technology, especially when the tar and char can be efficiently used. When the gasification temperature increases, both these two technologies improve.

Experimental Study on Direct-Fired Characteristics about Biomass Derived Crude Syngas

In order to solve the problem of slagging in biomass direct-fired and high tar content in biomass gasification, the method of using low-temperature gasification and crudesyn gas high temperature direct combustion for biomass is proposed. By changing the equivalence ratio of gasifying agents (ER-G) and the mass ratio of steam to air agents (S/A)for gasification, the syngas produced by rice husk was direct fired under different conditions in the experimental stage. The gasification temperature in gasifier and the flame stability in furnace were studied, and the gas volume fraction in gasifier was measured by gas chromatography analysis in off-line model. The results are shown as follows: The temperature ingasifier increases as ER-G increases and S/A declines. When the ER-G is lower than 0.3, the worse stability to flame in furnace shows. The volume fraction of H2 is the highest when ER-G is 0.35 and S/A is 0.10; and the flame stability in furnace is better in this situation. The volume fraction of CO increases as ER-G increases, while the trend is gradually smaller. The results in this paper would set base for the design and running of a crude syngas direct-fired system.