Applied Mechanics and Materials Vols. 291-294

Abstract: In this paper, the combustion characteristics of palm kernel meal were investigated in a circulating fluidized bed (CFB 100)(height=3000mm, inner diameter=100mm). The results showed that the temperature and pressure of the furnace were relatively steady. The contents of SiO2, Na2O and K2O of the bed material ranged smoothly with the process, the particle size of the bed material fluctuated slightly. The alkali metal contents of bed material were ranged from 1.5% to 3.5%.

Abstract: Much attention has been paid to municipal solid waste (MSW) incineration power generation and biomass energy. The co-firing power generation tests of MSW and biomass were performed in a MSW incineration power plant in North China. Experimental results showed that the running efficiency of generator unit had achieved the optimum state when the blended ratio was 14% (w%); the concentration of fly ash decreased greatly, and the concentration of SO₂ and NO_X increased slightly. These contents can be referenced in the running of MSW incineration power plant and the using of biomass energy later.

Abstract: This study employed statistically based on experimental designs to optimize transesterification conditions for biodiesel production from waste oil via lipase-catalyzed in homoeothermy. Optimization of different reaction parameters were done by using response surface methodology. Results indicated optimum conditions including: alcohol to oil molar ratio 3:1, lipase concentration 58.38 U each gram of oil, water and n-hexane content were 24.59% and 13.28% respectively, reaction temperature at 20 °C , and reaction time for 24 h. Under these optimal conditions, 98.24% yield of biodiesel was obtained. This study will probably contribute to the development of continuous enzymatic processes, and maybe a suitable method for industrial production of biodiesel.

Abstract: Methanogens are important environmental microbial and play an important role in the nature of the carbon-cycling, its unique physiological characteristics and metabolic mechanisms make it play an indispensable role in environmental protection and energy field. At present, known methane biosynthesis has three pathways: acetic acid, H/CO₂, methyl compound as the substrates generate methane through different reaction. Ecological factor affecting methanogens are mainly temperature, pH value, redox potential, etc. In this paper, we carry on analyzing the research progress of the methanogens species, its physiological characteristics, metabolic pathway, ecological factor and industrial application, and propose methods and the thinking of study to improve methane gas production by adjusting the ecological factor as the control factor.

Abstract: Biomass has attracted more and more attention in the world as renewable energy. Biomass direct-fired technology is a relatively mature technology with widely application in China. Due to the high content of alkali metals and chlorine in the biomass fuel, biomass direct-fired power plant suffers from ash-deposition and corrosion problems of low-temperature heating surface in boiler, accordingly impact the security and economy of boiler. Based on the literature survey, on-site detection, as well as EDXRF experimental analysis, reasons which resulted in ash-depostion and corrosion problems of air preheater are analyzed for 2×50MW CFB (Circulating Fluidized Bed) boilers in Zhanjiang Biomass Direct-fired Power Plant by Guangdong Yudean Group. Suggestive measures to prevent ash-depostion and corrosion are also proposed in this paper by the analysis of biomass combustion characteristics, ash-depostion and corrosion formation mechanism.

Abstract: Two cesium phosphotungstate-derived solid acid catalysts (Cs2.5H0.5PW12 and Cs0.5H2.5PW12) were prepared. The resulting catalysts were characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption and desorption isotherm and temperature programmed desorption of ammonia(NH3-TPD). The Cs2.5H0.5PW12 and Cs0.5H2.5PW12 were respectively used to catalyze the tranesterification of castor oil and methanol for the synthesis of biodiesel with the assistance of microwave. Results shown microwave radiation can greatly enhance the transesterification process when compared with conventional heating method. Cs2.5H0.5PW12 showed better catalyst performance than Cs0.5H2.5PW12. A maximum yield of 90% was obtained from the using of 30:1 molar ratio of methanol to castor oil and 15 wt % mass ratio of catalyst to castor oil at 343 K under microwave radiation after 4h.

Abstract: Thermogravimetric analysis (TGA) was employed to study the pyrolysis characteristics of two biomass materials (poplar and pine wood) and their demineralized samples under nitrogen atmosphere. Based on the experimental results, the pyrolysis kinetics were calculated. The results indicated that the starting and ending time of devolatilization were delayed after the demineralization of the biomass. For all the materials, the temperature of the maximum weight loss rate occurred at around 390°C, while the maximum values increased a little after demineralization. The pine wood was more difficult to decompose than the poplar wood, due to its high activation energy values. In addition, after demineralization, the activation energy values of the pine wood decreased, while the values of the poplar wood were not significantly changed.

Abstract: Eethyl levulinate (EL) can be produced by direct conversion of glucose in ethanol medium. Both sulfuric acid and solid acid catalyst (USY) can be used as effective acid catalyst. The maximum EL yields were almost same. However, the usage of USY is helpful to limit the diethyl ether (DEE) production efficiently for recycling of ethanol. In ethanol/water mixed medium, water addition has significant effect on the products distribution. EL yield decreased obviously in water-rich medium. Meanwhile, the amount of DEE decreased with the increase of water addition. However, water addition has the opposite effect on the humic solid formation, and more humic solid can be formed in water-rich medium.

Abstract: Rheological properties of microalgae suspensions affect the mixing and mass transport in photobioreactor systems and the design of downstream biomass processing technologies，and directly impact the energy demand and system performance of algae biofuel production. The purpose of this paper is to obtain the rheological properties as a function of volume fraction. The volume fractions of microalgae suspensions φ were derived according to the size distribution of the microalgae cells and cell number concentrations per cubic meter liquid. We found that at low concentrations, microalgae suspensions display a Newtonian fluid behavior. At high concentrations, microalgae suspensions behave as a shear thinning non-Newtonian fluid. The results are of potential scientific relevance and also useful in relation to the design of algae bioprocessing for the large scale production of economic biofuels.

Abstract: In the present study, catalytic pyrolysis characteristics of corn straw pellet were studied in biomass pyrolysis test bench. The effect of content of CaO added in biomass pellet on pyrolysis products was investigated. The results showed that: with the increase of CaO content, the yield of tar decreased ,and the yield of char and gas increased. Among gas compositions, the volume percentage of CO、H2、CH4 increased, while the volume percentage of CO2 decrease greatly. The Calorific values of the gas increase distinctly. The results have significant theoretical guidance on the application of biomass pellets in biomass gasification equipments.