Advanced Materials Research Vols. 608-609

Abstract: According to the specialty of straw briquette combustion, thermodynamic calculating and special processing methods, the special boiler which applies to cornstalk briquettes is designed and made. It has double fire grates which have function of smoke removing. Moreover, the combustion efficiency of this boiler is higher and the incomplete combustion loss of solid and gas is less. The contents of fume, nitrogen oxide and sulfur dioxide in the vent smoke are low enough to accords with national standard requirement. So it will have a splendid future to use straw as the substitute of coal in our country.

Abstract: This paper inoculated kitchen waste with activated sludge and fresh cow dung to explore the acidification and fermentation separated two-stage fermentation biogas process, in order to get acclimation acidification bacteria and methanogenic bacteria, high total solids content (TS) fermentation process, reduce the hydraulic load and shorten the fermentation cycle. The physiochemical characteristics of kitchen waste were that TS is 22.9%,the volatile solids (VS) is 11.7%, initial pH value is 6. The biogas producing process was as follow: Adjusting the TS of kitchen waste to 11.5% ,with 10% inoculum quantity, fermented at 37 °C , monitoring and adjusting pH. There were two biogas producing peak , and biogas production cycle was 15 days. The two-stage fermentation biogas process was as follow: Acidized the material of 22.9%TS for 5 days, Feeding the acidized material at the ratio of 1/4 to the vigorous biogas reaction system, then pH reduced but the biogas production was normal. After 5 days, pH raised and the second batch of material could be added. Feeding materials to the acidification tank and fermentation tank continuously, which can gradually get good acclimation acidification bacteria and methanogenic bacteria. Refluxing the biogas to acidification tank and methane fermentation tank, which can mix the materials evenly, shorten the fermentation cycle, improve the efficiency of the acidification and biogas production.

Abstract: Catalysts play critical roles in hydrotreating and hydrocracking processes of upgrading biomass-derived bio-oil to drop-in fuels. The selectivity and deactivate of catalysts, however, still remain biggest challenge. By using ZSM-5, alumina, and activated carbon as supports, different catalysts made up with Ru were prepared and tested in a bio-oil upgrading process. The effect of supports were investigated and compared in term of surface properties. The results showed that the ZSM-5 based catalysts got more water phase because of its highest surface acidity. The alumina changed to aluminum hydroxide in the presence of water at the reaction conditions. Activated carbon based catalysts showed good catalytic performance with more hydrocarbons and less water phase content in the upgraded bio-oil. All of upgraded bio-oils were verified by chemical analysis using a GC-MS. Nevertheless, further study for the kinetics of catalytically upgrading bio-oil is recommended.

Abstract: A mathematical model was developed to assess the economic feasibility of a biomass-based power plant in the Northeast of China. The objective of this model is to maximizes the net present value (NPV) of a biopower plant over its economic life, which subjects to the constraints of biomass availability, plant investment and operation & maintenance costs, plant capacity, transportation logistics, raw material and product pricing, financing, and business taxes. The model was applied in a biopower plant located in Wangkui County, China, which belongs to the National Bio-Energy Group Company Limited. Results showed that the maximum NPV of the Wangkui Biopower plant in the base case was approximately 117 million Yuan given the electricity sale price of 0.64 Yuan kWh-1 (or 0.75Yuan kWh-1 with tax). This study provides a reference for evaluating the economic feasibility of biopower plants based on biomass logistics networks in China.

Abstract: This research aims to study biogas production in King Mongkut's University of Technology North Bangkok Prachinburi Campus. Information of biogas energy from the food waste fermented in 2,000 liters capacity tank was analyzed to determine the heating value in order to calculate the Net Present Value (NPV), Internal Rate of Return (IRR) and Discount Payback Period (DPB). All the measured values from 15 days testing period are the gas quantity of 0.5-0.9 m3 and the average heat value of 10 MJ/m3.Ten fertilization chambers that have capacity of 6,000 liters each for biogas production should be replaced the original size of 2,000 liters tank because using the original tank could not reach breakeven point. By using 10 champers of 6,000 liters capacity each, the payback period has yielded within 5 years and 5 months and given the rate of return 22.48 percent per years throughout 20 years of recovery period.

Abstract: Activated carbons were prepared from coconut shells by using carbonization at 600 °C for 2 h followed by water steam activation. Effects of activation temperature, hold time and water steam amount on the yield, BET surface area and micropore volume of activated carbons were evaluated. The pore structure of the activated carbon was characterized by N2 adsorption at 77K. Surface area, micropore volume and pore size distribution (PSD) of the carbons were determined by the Brunauer–Emmett–Teller (BET) equation, Dubinin–Astakhov (DA) and the Non-Local Density Functional Theory (NLDFT) methods, respectively. The results show that activated carbons with specific surface area of 1500 m2/g and pore size lower than 2 nm can be produced at 900 °C for 1~2 h. Hold time could be reduced by increasing steam amount and activation temperature, but micropore was enlarged and yield was decreased. Increasing hold time could produce more micropores when steam amount and activation temperature were more appropriate. Pore size distribution shows that activated carbons are microporous dominant.

Abstract: Biomass tar was an inevitable by-product during biomass pyrolysis and gasification. The existence of biomass tar was a significant drawback for the use of biomass produced gases. At present, catalytic steam reforming was one of the most effective ways for tar conversion and elimination.In this paper, the coke-resistance Nickel-based monolithic catalyst and the Nickel-based monolithic catalyst were prepared, using cordierite as the catalyst carrier. Toluene and n-heptane were selected as two typical tar model compounds for the evaluation of catalyst performance in a fixed-bed reactor. The influences of temperature on the tar conversion efficiency were experimentally investigated. The results show that the two prepared monolithic catalysts have excellent performance for tar conversion. At 800°C, the conversion efficiency of toluene reach 82% and 80.4% over the coke-resistance Nickel-based monolithic catalyst and the Nickel-based monolithic catalyst, respectively. The addition of Cerium as the coke-resistance component remarkably reduces carbon deposition tendency with prolonged catalyst lifetime. monolithic catalysts have excellent performance for tar conversion. At 800°C, the conversion efficiency of toluene reached 82% and 80.4% over the coke-resistance Nickel-based monolithic catalyst and the Nickel-based monolithic catalyst, respectively. The addition of Cerium as the coke-resistance component remarkably reduces carbon deposition tendency with prolonged catalyst lifetime.

Abstract: With starch and NaOH, CaO as raw materials, the type of coal gasification catalyst prepared with mixed, the effects of different additive ratio on the viscosity, mechanical strength, thermal stability, chemical reactivity. The results show that the catalyst can improve the briquette indicators, play a good catalytic effect on the gasification of coal briquette, in 10% of the amount of catalyst, the effect of the additive is used in an amount 30% optimal.

Abstract: In this paper, the chars of wood dust, corn straw, rice husk and coal pulverized were obtained at different residual time of various pyrolysis temperature (1173 K, 1273 K and 1373 K) during the process of flash pyrolysis in the drop tube furnace (DTF). In order to obtain the parameters of porous structure which included specific surface area, pore volume and fractal dimension of char, low-temperature nitrogen adsorption method was employed to obtain nitrogen adsorption isotherm of chars sample. For the four chars, the corn straw char had the biggest specific surface area and pore volume, the rice husk in second place, the wood dust in third place, and the pulverized coal char in the last one. By taking Frenkel-Halsey Hil (FHH) method to analyze the fractal character of char surface structure, we found that the fractal dimension of biomass except wood char is higher than those of pulverized coal char.

Abstract: The aim of this paper is to discuss and find proper technologies to meet the new deNOX demand for biomass power plants in China. One of the outstanding features of these power plants is the emission of NOX at times which fails to meet the new standard. However, even if it’s above the emission standard, the value is not too high due to its low combustion temperature. Another feature is the large alkali content in the straw which forms fly-ash with vapour in flue gas. The traditional methods of SNCR and SCR will not fit bio-fuel boilers because of their low combustion temperature, small volume of furnace, high humidity and alkali metal in bio-fuel. Active coke adsorption maybe fit the installed boilers for its simple system and high efficiency. The recirculation of flue gas through a char layer needs to change the design of the boiler combustion system, which can cut immensely the deNOX operation cost of the biomass power plants.