| On the basis of summarizing the present researches and applications on bioenergy utilization technologies, this thesis focuses attention on experimental and applied research on biomass gasification technology. As a key thermochemical conversion technology, the novel pyrolysis technology in this thesis can produce MCV fuel gas, which undoubtedly keeps harmony with the status quo of rural economy and characteristics of biomass resources in China. On the one hand, the performance criterion like gas production rate, tar content and operation mode has reached the commercialization level presently. On the other hand, studies on gas clarification and tar cracking technologies have been performed to optimize its technological and economic performance further.First of all, after a brief introduction to the concept of bioenergy and the common technologies adopted for its utilization, a review of current researches and developments of biomass gasification technologies is given. And also, the major programs, projects and researches have been introduced at length.By virtue of the experiments carried out on the modified pilot-scale biomass gasification system, the temperature field in the gasifier is made explicit. And also some principles about how the temperature, feedstock and extraction mode exert influences on heat value and production rate of gas are attained. In addition, some tentative tests of tar cracking and thermodynamic characteristics of biomass gas burner have been performed, which are that indispensable to design and operation of biomass gasification demonstration project. It has been indicated that as a pyrolysis gasification technology integrating combustion and gasification, it not only makes the fuel high-usage but also solves the problem of straw accumulation effectively by controlling operational parameters. With the merits of technical simplicity, better adaptability to materials, less start time and operational stability, this gasification technology can produce MCV(>2500kcal/Nm3) biomass fuel gas with low tar content(<50mg/m3), which entirely meets the Standard of Agricultural Ministry NY/T443-2001 ?Technical Specification and Acceptance of Standard for Straw Gasification System of Central Gas Supply.Based on the acquired data and operating experiences from pilot experiments, the demonstration project is devised comprehensively, which is concerned with so many aspects, such as choosing the site of demo plant, the portions' arrangement, gasification subsystem, condensation subsystem, tar catalytic reforming subsystem, purification and dryness subsystem, gas pipe networks and fire control subsystem. Furthermore, economic assessment has been given preliminarily. Therefore, the technological and economic feasibility for the construction and running of thedemonstration project can be guaranteed.Thanks to improved tar sampling method, the primary study on gas clarification technology is progressed. It has been shown that this updated sampling and measurement method, which can measure the content of tar and dust individually, appears much more precise and credible, particularly aiming at the characteristic of heavy tar and dust content in biomass gas. This clarification system that adopts two-level shell and tube condensers and one tar removal filter, has the advantages of high removal efficiency (97%~98%) and low operating cost. Besides, it has been made more environmentally friendly considering that wastewater from condensers has measured up to related effluent state standards after being disposed in tar clarifier-tank. In view of cost, the clarification effect and environmental protection, the cleaning system with coke as absorbent should be the fairly good choice that can produce less tar content and high quality household gas. The cost will be made fewer as well for the reason that coke in filter and clarifier-tank can be put into gasifier again to pyrolyze.In order to improve the clarification level and make preparations for generating electricity by means of biomass gasification...
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