The Technical And Experimental Study Of Pelleting Biomass With Dual Ultrasonic Vibrators

Biomass is a renewable and environmentally friendly clean energy, which is considered as one of the best alternatives to fossil fuels. Biomass pelleting technology is one of the main developmental direction of biomass energy conversion and utilization, which can significantly increase the density of the biomass and reduce the transportation and storage costs of the biomass. According to a series of problems of traditional biomass pelleting technology, such as needing of high temperature, high pressure, the pollution resulting from the additives, our group creatively applied dual ultrasound to pellet biomass and presented a new technology of pelleting biomass with dual ultrasonic. This new technology don’t need high temperature, high pressure and additive when pelleting biomass, it only needs indoor temperature, low pressure and without additives, which has a good prospect. This article studies on the pelleting machining tool, the ultrasonic transducer and the biomass pelleting technology with dual ultrasound:First, we summarized the machine’s structural requirements and designed the machine’s overall structure and overall control by analyzing the difference of the pelleting machining tool with dual ultrasound and the traditional biomass pelleting technology. Then we completed mechanical machining and assembly of machining tool combining with the machine parameters and performance indicator.Secondly, according to theory of one-dimensional vertical vibration, we designed the transducer, horn and tool size, then we analysised the modal of ultrasonic vibrator based on finite element analysis software ANSYS Workbench.Finally, paper studied on the influencing factors such as pelleting time (s), pressure (psi), pellet weight (g), moisture content (%) on the pellet density and relax density of biomass with the method of dual ultrasonic vibration-assisted pelleting of biomass, and optimized the pelleting parameters using the orthogonal experiment, and used relaxation ratio directly reflecting pellet density under different pelleting conditions. The results were as follows:1) The order of the influencing factors to the pellet density was pelleting time> pellet weight> pressure> moisture content. The most suitable pelleting conditions were that the pelleting time was 50s, the pelleting pressure was 25psi, the pellet weighs was 1.0g, and the moisture content was 15%. The pellet density was 1.366×103kg/m3 under the optimized conditions.2) The relax density of pellet was gradually decreased under all pelleting condition, but with different degrees of relax density decreasing. The relax ratio of pellet got maximum when the pelleting time was 30s, the pelleting pressure was 25psi, the pellet weight was 1.0g, and the moisture content was 15%.