Applied Mechanics and Materials Vols. 291-294

Abstract: Tianjin biomass energy utilization situation is surveyed and the result shows there have five kinds of use pattern in Tianjin biomass energy utilization: household biogas, livestock and poultry farm biogas project, straw biogas project for centralized supply, straw gasification for centralized supply, and biomass thermal utilization. Then the using scale, advantages and problems of these five kinds of use pattern are described. Finally, this paper analyzes the biomass energy utilization strategy in Tianjin, respectively from the perspective of biomass project construction and management, energy comprehensive utilization, new countryside planning and construction.

Abstract: The chemical compositions of biodiesel are analyzed by GC-MS, and their molecular structures are investigated on the basis of the hybrid orbital theory. The CFPP of biodiesel is studied by CFPP tester, the solution crystallization theory and the similarity-intermiscibility principle. Good correlation models are proposed for predict CFPP of biodiesel by chemical compositions and the CFPP of biodiesel-petrodiesel blends by biodiesel ratio. The study shows that biodiesel is mainly composed of SFAME (C14:0～C24:0) and UFAME (C16:1～C22:1, C18:2 and C18:3 ). Carbon atoms of the alkyl for SFAME arrange in a zigzag pattern by ∠CCC=109.5°. C-C carbon atoms of the alkenyl arrange in a zigzag pattern by ∠CCC=109.5°, too, carbon chain is curved by C=C in ∠CCC=122.0°, and curved degree increases with increasing unsaturated degree. CFPP of biodiesel is mainly determined by chemical compositions. CFPP increases with the amount and carbon chain length of SFAME. CFPP of biodiesel-petrodiesel blends is mainly determined by chemical compositions and ratio of biodiesel. To lower SFAME≥C20:0 biodiesel, such as PME, CSME, WME, SBME and RME, it blending with -10PD can formed a eutectic mixture. CFPP of the eutectic mixture is -12 °C. The biodiesel ratio for the lowest CFPP rang increases with decreasing SFAME. Such as SFAME contents in PME, CSME, WME, SBME and RME are 35.86、32.12、31.04、18.29 and 14.69 w% respectively, and the range of biodiesel ratio is 5～20、10～20、20～30、30～50 and 40～60 v% respectively. To higher SFAME≥C20:0 biodiesel, such as PNME, CFPP increases with PNME ratio.

Abstract: Biomass briquetting technology is one of the key technologies in the utilization of biomass energy. In this paper, the mechanical characteristics of the die holes were analyzed to set up mathematical model in the briquettes forming process. The effects of the three key structure parameters, which include the inlet angle, forming taper angle and length-diameter ratio, were carried out by using the finite element software. The results indicated that the die hole with forming taper is easy to form back pressure, and the higher taper angle, the greater equivalent stress value is found in the corresponding parts, which is helpful for forming process. Combined with processing cost, energy consumption and wear analysis, the die hole forming taper should not be too big. For the corn straw, it can satisfy the molding pressure requirements to take 2° forming taper. The parameter of inlet angle main influences material grabbing, production efficiency and flat die manufacturing cost. For the corn straw, the inlet angle between 40° and 50° of die hole is not only beneficial to material grabbing and forming, but also can control flat die manufacturing cost and guarantee a certain production efficiency. Length to diameter ratio main influences the stress distribution in shape-preserving section and reflects the compressed extent of the material. Combined with energy consumption analysis, length to diameter ratio between 4:1 and 5:1 can guarantee the corn straw forming requirements. The above numerical simulation method and results can provide some reference for the flat die structure design and parameter optimization.

Abstract: In order to solve inconvenience of previous mathematical models in engineering practice and decision analysis, the empirical models of methane generation rate for single-phase and two-phase anaerobic digestion of kitchen wastes were established and revised by means of experimental observation and function fitting. The experiments of single-phase and two-phase anaerobic digestion of kitchen wastes were carried out by controlling temperature and pH of system at about 35°C and 7. Experimental results showed variation trend of methane production in single-phase and two-phase anaerobic digestion of kitchen wastes were similar to quadratic curve and linear curve respectively under neutral condition. Base on the observation, the benchmark empirical models of methane generation rate were created by method of function fitting, correlation coefficients of fitting function reached 0.9682 and 0.9772, respectively. The benchmark empirical models were revised by introducing load ratio, inhibition coefficients of pH and ammonia nitrogen. Results of significance variance test for empirical model showed the regression of empirical model was notable. It illustrated the empirical model could be used to predict methane production during single-phase and two-phase anaerobic digestion system of kitchen wastes. Moreover, the calculative process of empirical model was very simple.

Abstract: In this paper, under the premise of maximum temperature not more than 200 °C, the diethanolamine pulping process of pinus kesiya was optimized. AQ was used as the additive for pulping. Under the optimum pulping condition, the pulp properties were as follows: screened pulp yield 61.9%, viscosity 1306mL•g^-1 and kappa number 24.3. The handsheets physical properties were as follows: tensile index 77.6N•m•g^-1, bursting index 6.40kPa•m²•g^-1, tearing index 10.63mN•m²•g^-1

Abstract: The rice husk from China has been non-isothermally pyrolysed on thermogravimetric analyzer(TGA). The analyses were performed at different heating rates (20, 40, 60, 80, 100°C/min) up to 900°C with nitrogen as purge gas. The weight loss curve showed that the main pyrolysis of rice husk took place in the range of 200~500°C. On the basis of experiment data, a pyrolysis kinetic model was proposed. The kinetic parameters of activation energy(E) and frequency factor(A) were obtained by the Direct Arrhenius Plot Method. There was no clear relationship between activation energy and heating rate.

Abstract: Biodiesel was synthesized starting soybean oil and methanol using K2CO3 and phase-transfer catalysis TBAB. It was studied that the yield of biodiesel can be changed with reaction factors such as the kind and the amount of phase-transfer catalysis, the amount of K2CO3, reaction time, molar ratio between methanol and soybean oil, reaction temperature. The results show that the reaction conditions are as following: mass ratio of TBAB to soybean oil weight 0.6%, mass ratio of K2CO3 to soybean oil weight 1.5%, molar ratio between methanol and soybean oil 6∶1, reaction time 20 min, reaction temperature 40 °C. The yield of biodiesel reached 95% under the optimum reaction conditions.

Abstract: Thermogravimetry - Fourier transform infrared spectrometry (TG-FTIR) technique was applied to achieve thermal evaporation, decomposition and combustion of bio-oil and on-line analysis of the formed products. The experiments were performed under the N₂/O₂ atmosphere with different O₂ contents using a bio-oil sample derived from rice husk. According to the TG results, the thermogravimetric process included three stages, the evaporation of light volatiles, the decomposition of heavy components, and the combustion of the char residues. The kinetic calculation revealed that the activation energy values of the evaporation and decomposition stages would not be greatly affected by the O₂ content, while the activation energy values of the combustion stages would decrease as the rising of the O₂ content. Moreover, the FTIR results indicated that the major products in the evaporation stage were the water and organic volatile compounds. Whereas the products in the combustion stage were mainly CO₂ and H₂O, together with a little CO.

Abstract: The purpose of this paper is to introduce a methodology-Backcasting for policy makers in renewable energy development, with expect to enable the development of an alternative strategy and the facilitation of a more flexible and responsible policy agenda. Take biomass energy domain as a case to explain the application of this methodology, and multiple factors should be taken into account. The study indicates that China’s renewable energy is still in the transition period from research and development to industrial production, and the effective, scientific and timely decision-making from government policy makers is utmost crucial to the healthy development of renewable energy industry in China because it regulates the development path of this innovative industry. It is an innovation to link biomass industry development with urbanization strategy in China rural area in the long run.

Abstract: Wood vinegar is one of the major products of biomass pyrolysis, and it contains a large number of beneficial ingredients. We investigated the components of fresh and preserved wood vinegar gained from rice husk continuous pyrolysis and catalytic cracking. The main ingredients of fresh pyrolysis wood vinegar are acids, phenols and ketones. The species of ketones are more than any other compounds, but the content of each single component is very low. After a year’s preservation, the content of acids and alcohols increases, while phenols decreases. For the catalytic cracking wood vinegar, the content of acids is low, while the content of phenols and ketones is high. The content of acids, phenols and alcohols increases remarkably, and the content of ketones decreases sharply after a year. N in the wood vinegar exists in the form of amino, nitroso and cyclization. Ketol and unsaturated ketones could be generated by condensation reaction of ketones, and alcohols from the reduction reaction or addition reaction of ketones, caused the increase of alcohols and enol ketone. Phenol could be generated by dealkylation reaction of alkylphenol, and alkyl broke into small molecule alcohols and carboxylic acids, caused an increment of acids and alcohols. Acids and alcohols with longer carbon chain, which may be the by-products of some reactions or products of condensation reactions, are detected in the preserved wood vinegar.