Papers by Keyword: Vacuum Pyrolysis

Abstract: Biomass pyrolysis for preparing bio-oil was studied on the vacuum pyrolysis system, where rape straw was chosen as the raw material. The experiment was designed by orthogonal method. And pyrolysis temperature, system pressure, heating rate and holding time were chosen as input variables to establish the prediction models about bio-oil yields and energy transformation ratio based on Generalized Regression Neural Network. The parameters of vacuum pyrolysis system were optimized for maximizing bio-oil yields and energy transformation ratio, and the optimization result was verified by experiment. The results of research show that the predicted values are fit well with the experimental values, which verifies the effectiveness of the prediction models. When pyrolysis temperature is 486.8°C, system pressure is 5.0kPa, heating rate is 18.1°C/min and holding time is 55.0min, bio-oil yield is 43.6% and energy transformation ratio is 35.5%. Both are close to the maximum, and the result is accurate by experimental verification.

Abstract: This thesis does thermal gravimetric analysis（TGA）studies on Chinese fir sawdust biomass by integrated thermal analyzer under vacuum conditions. Through the analysis on lostmass curve at different heating rate of 10, 15, 20 and 30°C/min, we found the process of Chinese fir sawdust vacuum pyrolysis can be mainly divided into three stages: evaporation of free water and combined water desorption, rapid lostmass of pyrolysis and slow decomposition of residues. The lostmass major temperature range is between 250 ~ 450°C, the peak temperature is between 365 ~ 400°C. When the pyrolysis temperature is 500°C, vacuum pyrolysis reaction of Chinese fir sawdust has basically completed. As the heating rate rises, the lostmass curve is moving to the right, the peak temperature is shifting to higher temperature, and the temperature range of thermal decomposition reaction widens significantly. According to experimental datas, we tried to obtain the vacuum pyrolysis dynamic parameters of Chinese fir sawdust, and the results are that the apparent activation energy of vacuum pyrolysis reaction of Chinese fir sawdust biomass is 128.34kJ/mol, with the pre-exponential factor being 6.42×109 and reaction order being 1.08, similar to first order reaction.

Abstract: This paper presents an integrated processing technology for the recycling of spent Zn-Mn dry batteries by means of dry-wet method, which combines mechanical decortications and vacuum technique. On the basis of analyzing current research and applications, the characteristics and problems of existing technologies in this field are discussed. Research achievements such as its processing, key techniques and equipment for mechanical decortications are introduced in detail. This technology has many advantages, including higher recovery rate, lower energy consumption, minimum secondary pollution and lower cost for equipment, which is suitable for the purpose of recycling spent batteries in small and medium-sized cities and provides a new option for technicians and researchers in related fields.

Abstract: Scrap tire is considered an environmental concern with inadequate final disposal. A good alternative can be to use the tire as an energy source. Pyrolysis is a thermal process that can transform the rubber portion of used tires into oil, gas and pyrolytic carbon. This type of carbon can be converted into carbon black (CB). The lime industry that demands great amount of energy could be one of the ways to take advantage the scrap tires adequately as energy source. This work aimed to study the operational conditions of the pyrolysis process as well as investigating the possibility to use the pyrolysis products from used tires as industrial fuel. A batch pilot-scale pyrolysis unit was built. Temperatures from 400 to 600oC and relative pressures from 0 to -500 mmHg were investigated in order to evaluate product distribution and quality. Experimental results showed that as the reactor temperature was increased the pyrolytic carbon yield remained constant with a mean of 39.8 wt % and the pyrolytic oil yield reached a maximum value of 45.1 wt % at 500 °C. It is also possible to show that the pyrolytic oil can be used as liquid fuels because of its high heating value (40-42 MJ/kg), excellent viscosity (1.6-3.7 cS), and reasonable sulfur content (0.97-1.54wt %). In addition, chemical and physical characterization was made in order to compare the pyrolytic carbon and oil with currently fuels used in Brazilian lime industries (wood charcoal and coke of petroleum).