The Optimization Design For New Type Briquetting Biomass Fuel Machine

With the fast increase of the energy consumption, the energy resources used in the world are increasing. At the same time, the prices of main kind of energy are archived a higher level which is never achieved. In order to relieve the energy crisis, every country pays more and more attention to the renewable energy. Our country also emphasizes it very much. For the renewable energy, the biomass energy is becoming important. The biomass energy can be used in many different ways. Because China is a large agricultural nation at present, it is becoming more and more important to use the massive straw resources. The method using the straw has many ways such as the solidification, liquefaction and gasification. The development of biomass solidification using the biomass briquetting machine to densify and shape the straw is quite rapid.From the investigation of the production and consumption market, it is concluded that the Screw briquetting mechanic have the highest Market share, although it is the oldest briquetting mechanic and have many disadvantages, we could only say that the price is everything. If we can improve the disadvantaged aspects, make longer workable lifetime of the screw and the forming sleeve, and improve the productivity for example, we will enhance the productivity, and let the product cost down. And finally, we will make the biomass briquetting production process a large scale forward.Through actual production, we can conclude that the screw head and the cone shape of forming sleeve is the stress concentration areas. So many times we found that the last part of screw and the flat part of forming sleeve is OK, however, the screw head and the cone shape of forming sleeve has wear and tear (the screw head means 2 times lead length from the thin end of screw). Therefore, we can improve the life of the main hardware by two ways: first, the screw can be split into the replacement screw head and the main-screw, at the same time, split forming sleeve into replacement sleeve and shape maintaining-sleeve. Although the workable lifetime of the replacement screw head and replacement forming sleeve have not significantly increased, but because the main stress does not focus on the other two parts, the life of which these parts works as one is significantly increased, Because we can replace the replaceable screw head and forming sleeve. So, the production cost is reduced.With the guidance of these design ideas, we made the force and motion analysis of the biomass and it shows that at certain rotation speed, biomass materials can get better axial transmission speed with screw pitch varing in a certain range. Based on that, we optimized the design parameters of the major parts of the machine, and get: 1) the varying range of screw pitch with which the optimal productivity ratio can reach; 2) the optimal value makes the nominal diameter acting in concert with diameter of screw and screw pitch to achieve the minimum mass of the screw. According to that result and the new design ideas, we designed the most important parameters, including screw pitch, teeth size, main-screw length, replacement screw head length, replacement sleeve length and shape maintaining-sleeve length, etc.With the help of a company, we proposed the design and produced a prototype. After the compurative experiment between the new machine and the old one, we can conclude that:1) The productivity enhanced 35.9% from the original machine. It almost reaches the design demand, but its significant improvement;2) The density of briquetting biomass fuel which new machine productes is reducal a little compared with the original one, from 1.1 kg ? dm -3 to 1.0 kg ? dm -3. It can also fit the demand of shape keeping of briquetting biomass fuel;3) The work noise of new machine is obviously lower than that the original one. However, the machine had obvious vibration during operation. So, we have to improve these aspects with several methods: first, making the base of machine heavier; second, fixing to the ground with screws.Finally, according to the new briquetting machine's productivity and the demand of charcoal and biomass charcoal market, we made economic feasibility analysis for this technology. And we reached the conclusion that if the machine can work reliable, this technology will be reliable, so that investors can quickly recover the cost, with good economic returns. It is believed that after improving the vibration and heating supply security problems, the machine will meet all the requirements of briquetting biomass fuel production.