Experimental And Applied Research On Biomass Tar Catalytic Cracking

In the process of gasification of biomass feedstock, tar occurs as the concomitant product of pyrolysis gas, with large molecular weight hydrocarbon as its main content. The occurrence of tar in gas has great influence on the process of gasification, the design of gasification equipment, the transportation and distribution system, and the final users of gas. With relatively great viscosity, tar content will adsorb some solid particles floated in the gas flow, such as ash particles and some biomass feedstock, which may cause conglomeration and sediment in the gasification equipment and transporting and distributing line of gas. When the conglomeration becomes serious, it will threaten the steady, safe, and long-term operation of the overall system.On the basis of the technology of purification of hot gas of biomass gasification and biomass utilization technology, this thesis focused attention on the experimental and applied research biomass tar catalytic pyrolysis aimed to the characteristics of biomass resource in China. First, a lot of data is obtained by the small-scale experimental scheme designed by us. And established the foundation for further application, after analysis of the them in detail,Biomass utilization have many profile in the aspect of environment, economics and society. During the process of gasification or cracking tar is the byproduct inevitably, which has many disadvantages. The elimination of tar and purification of the tarry gas is a crucial step in the development of biomass gasification. A promising way to solve the problem is the use of catalysts to catalytic cracking. A number of different sampling and analysis method was used in many manufactures and other works to determine the level of the organic and contaminants in the gas at the exit of the gasifier. The diversity of the methods make the comparison is difficult. This represent a significant barrier for further development and commercializing of the technology.As one important item in this research, the investigation on the technology of gas catalytic reconstruction was paid close attention in our laboratory. On the basis of reference on related research results in domestic and abroad, both theoretical and experimental study is performed. One set of equipment for gas catalystic reconstruction developed by us own is illustrated in the following figure, in which tar sampling system is also included. In this thesis, the experiment system: biomass tar catalytic pyrolysis, which overcomes the disadvantage of mixture of some typical compound. And some improvement was made to adapt the characters of tar content of China.The result of the experimental is the primary content of the thesis; it focused on the following parts:a) Effect of temperature on the yields of tar in the 3 biomass materials; With the increasing of the temperature, the tar yield of tar is decreased in both materials.b) The concept of ratio of conversion;c) Effect of temperature and residence time on tar conversion ratio; Increasing the temperature and residence time is beneficial to tar cracking,and the effect is not evidence when T>900C and Ï„ >1 .0sd) Effect of cracking temperature on the tar conversion ratio with SiC;e) Effect of different catalyst on the tar conversion ratio;Some catalyst was test in the experimental system and dolomite is a most promising one.f) The loss of the activity of catalyst and the regeneration;Running for a long time, the activity of the catalyst was reduced mainly for he carbon deposit and regeneration happened after the sediment was moved.g) The analysis of the tar content with the aid of GC/MS;Before the analysis by the GC/MS, a lot of pre-treatment was done to divide the tar into five part: Aliphatics, Aromatics, Ester, Polar, Asphaltenes. Except the Asphaltenes, the other 4 part was given to the GC/MS. h) Comparison of gas contents and flow rate before and after the catalyticcracking reaction;i) The energy cost of the catalytic cracking;After the exper...