Experimental Study On Characteristic Of Biomass Gasification In Top-lit Updraft (tlud) Fixed-bed Gasifier

To solve energy shortage and improve the"dirty, disorderly and bad"environment of rural areas in China, agricultural and forestry waste that used to be disposed should be fully used based on the local characteristics of China's rural areas. Fixed bed biomass gasifiers which can directly use various agricultural and forestry wastes that are widespread in rural areas, have been effectively used in rural areas. However, there are some problems for the current prevalent fixed-bed gasifier, such as low calorific value, high water and tar content, combustion instability, flameout, tempering, bypass and other issues. Particularly, high tar content block the promotion of biomass gasification technology in the rural areas.In this paper, a new generation of household-based biomass gasifier was developed to solve those problems, which features high-performance, clean, low-tar and high stability. It is fit for the need of the rural resident and could significantly improve rural living environment.Based on foreign R&D experience on Top-Lit UpDraft (TLUD) fixed-bed gasifier, and considering the characteristics of Chinese biomass, a small-scale Top-Lit UpDraft (TLUD) fixed-bed gasifier was designed and manufactured according to the principle of simple, low-cost, high-heat value, low-tar and high-stability.A series of cold state and hot state studies were carried out with four materials (peanut shell, rice husk, wood shavings and sawdust). It was found that the gasification performance was up to the need when four types of materials gasified in the air flowrate range of 2.5m3/h ~ 4.0m3/h. The results under different air flowrate (2.5m3/h, 3.0m3/h, 3.5m3/h, 4.0m3/h) were analyzed in details.In cold state trials, it was observed that the resistance of material layer was almost proportional to the increase of the air flowrate, and the gasifier was operated under slight pressure. In the same section, static pressure fluctuations were slight, ~3pa, and air distribution system design could ensure good air distribution.Hot state experiments were carried out to investigate the gasifier performance. The furnace temperature distribution (including the export of gas temperature and flame temperature), gas composition and calorific value, the response characteristics of each stage, furnace heat transfer characteristics and tar characteristics were studied carefully also. TLUD gasifier had a great upgrade on gas stability and materials adaptability, and overcame the difficulties such as tettoie, highwater and tar content in the gas which were inherent in the traditional fixed-bed gasifier.