Advanced Materials Research Vols. 724-725

Abstract: As one of a agricultural provinces of China, Yunnan has abundant biomass resources such as crops straw, wood wastes and so on. However, the exact annual output of biomass resources has not been statistically calculated. Through carefully collecting and recalculating data from 2000 to 2008 year, the accurate main crops straw yield of Yunnan were calculated by using the Straw to Product Ratio (RPR) coefficient of different crops in this paper. Yunnan produced some 23 million tons of crops straw per year. The three largest contributions to the total output of crops straw were from corn, sugarcane and rice, which amounted to 39%, 28% and 16% of the total crops straw respectively. This paper analyzed the present status of utilization of biomass in Yunnan and proposed that more than 60% of crops straw were burnt in the field at present, which has caused serious environmental pollution. There was still 19 million tons of biomass from agriculture, forestry and flower industry each year can be used as biomass energy resources, which was equivalent to about 9.5 million tons of standard coal, and can provide about 2.76 × 10¹⁴KJ biomass energy.

Abstract: Lignocellulosic biomass can be an ideal feedstock for fermentative hydrogen production if properly pretreated and hydrolyzed. In this research, to enhance hydrogen production from cornstalk, acid and alkali pretreatments were performed. Alkali pretreatment was conducted at 80°C for 60 min and room temperature for 7 days with the addition of 4% NaOH; acid pretreatments at 190°C, and 120°C for 10 min and 120 min, respectively, with the addition of 1.7% H₂SO₄. All the chemical components change of the substrates was detected. The highest lignin reduction of 75.6%, compared to untreated samples, was found at 80°C with 4% NaOH dosage. Under this pretreatment condition, highest increase in reducing sugar and hydrogen yield (up to 11.8 g/L and 71.8 ml/g-pretreated cornstalk) was obtained. The present results suggested an efficient pretreatment method to increase hydrogen production from lignocellulosic biomass.

Abstract: The article deals with the evaluation of wood chips moisture and compares two methods of moisture determining. The problem of moisture determining consists mainly in selecting a suitable method according to the estimation of content of water in wood chips. Another factor to be considered is the fact that moisture in wood chips due to the ambient conditions (temperature, pressure, humidity) changes over time.

Abstract: Coaled carbon-based solid acid (Coal-SO₃H) was prepared by sulfonating ultra-low ash Taixi coal and characterized by XPS, IR and PXRD. It was used as a new, efficient and recyclable catalyst for fructose dehydration to form 5-hydroxymethylfurfural (5-HMF) in dimethyl sulfoxide (DMSO). Reaction time, temperature and catalyst amounts were investigated respectively. The results showed that 81.6 % yield of 5-HMF achieved in dimethyl sulfoxide (DMSO) at 140 °C after 140min using the Coal-SO₃H as catalyst. The ash, carbonization temperature and sulfonated way which could influence the catalyst performance for preparing 5-HMF had been investgated.

Abstract: In this paper, effect of acid curing agent on the foaming of liquefied bamboo-based resol resin (PBF) were studied. The research result indicated that the optimal acid curing agent were mixture of p-toluenesulfonic acid and H₃PO₄, curing of PBF resol resin was analysized in detail and computer-aided software was applied for calculating thermodynamics characteristic of foaming process so that integrative assistantwas controlled better. Its apparent activation energy was 1.226 kJ·mol^-1. The PBF foam showed satisfactory densities and compressive properties.

Abstract: In order to verify the correspondence of numerical simulation and experimental results in the electric heating biogas digester system, an electric heating biogas digester experimentdevice was established, and according to the experimental conditions, software Fluent was used to simulate the process of the heat transfer in the system. Before simulation, analyze theexperimental data through the calculation of heat balance and modify it, then use the modifiedexperimental data, compile UDF to characterize the dynamic boundary conditions, choosestandard turbulence model through the Raleigh number, numerical solving the process. Numericalsimulation results show: simulation process basically reflects the experiment, the simulation dataand experimental data are good agreement, and error within 1%. It is concluded that thenumerical simulation analysis is accurate, method is reliable.

Abstract: According to the resource characteristics of Chinas western alpine region, the thermal equilibrium experiment and analysis of solar digester is studied in this paper. Under the simulation conditions, the experiment showed that preheating time of solar digester will be shorter with the heat temperature increasing, and the shortest preheating time is 35 min. At the same time the calculation result showed the effective thermal efficiency in preheating stage is gradually increased from 75.7%, 84.6% to 99.3%. In order to maintain the digester thermostat 860 kJ/m³/h heat should be provided to the digester. The digester temperature can be maintained above 33°C within 10 hours in the case of a low humidity in summer. The auxiliary heat sources and additional insulation layer added to the system should be considered in the case of winter and high humidity day in summer.

Abstract: Growing attention had been drawn to the use of biomass as fuel for electricity generation in China. However, as a fairly new imported technology in localization, it had met serious problems with slagging and fouling of the super-heaters. The slag deposit on the first super-heaters in a biomass boiler was characterized by XRD, SEM-EDS and XRF to make clear the reason for the slag deposit. According to the results, alkali metal such as K, Na and Ca were predominant in the slag deposit. NaCl and KCl in the form of halite and sylvite were confirmed by XRD.

Abstract: This paper describes the oxygen-enriched combustion characteristics of pure cotton from municipal solid waste applying the non-isothermal thermogravimetric analysis, the apparent activation energy and the pre-exponential factor of oxygen-enriched combustion were obtained by kinetic analysis. Experimental results show that the pure cotton combustion process consists of two phases, which are volatile release and combustion phase and fixed carbon combustion phase. It has been found that combustion performance of pure cotton is improved when oxygen concentration increases to certain value and compensation effect exists in pure cotton combustion with the variation of oxygen concentration. The experimental results can provide direction for disposal of pure cotton as an energy resource.

Abstract: Hydrolysis of cellulose and hemicelluloses of lignocellulosic materials to obtain reducing sugar can be used to produce ethanol by microbial fermentation. Effective pretreatment is necessary for optimal hydrolysis. This study investigated the positive effect of freeze-thaw treatment on low temperature sulfuric acid pretreatment for convert wheat straw to reducing sugar. Freeze-thaw treatment conditions were optimized: at -20°C for 12h, and at room temperature (25°C) for 1h, followed. After twice repeating of freeze-thaw treatment and pretreatment with 2wt% sulfuric acid for 16h at 80°C and enzymatic digestibility with 20U/g of cellulase loading, 67% cellulose and hemicelluloses were converted to glucose and xylose. The yield of furfural was decreased by 65% during sulfuric acid pretreatment. The time of acid hydrolysis was shortened by 20%.