Advanced Materials Research Vols. 953-954

Abstract: Numerical simulation is a new and effective method to study the engine performance. In this paper, combustion model of biodiesel engine is established, and the cylinder pressure, NO_x and Soot emission are calculated. The research results indicate that the model established by AVL FIRE software can calculate the biodiesel engine performances accurately, which is an effective way to study engine performances conveniently.

Abstract: In this study, the gasification processes of different Taiwan’s agriculture wastes were studied by using software of Fire Dynamics Simulator (FDS), which developed by American National Institute of Standards and Technology (NIST), to build a model of downdraft fixed bed gasifier. Details of the operation condition for the Taiwan’s agriculture waste biomass fuel in the gasifier were obtained. They include traction fan speed, leakage air, internal temperature, moisture, and cold gas efficiency. The simulated results are found in small type fixed bed biomass gasifier under traction fan initial speed is 0.2m/s, the leakage air in the gasification area is less than 10% of the amount of wind quantity by traction fan and moisture content of solid biomass is limited at 10% ~ 20%(vol.) that temperature in gasification zone with steady supply fuel gas condition is near 850~900°C.

Abstract: By using mechanical force, biomass can be compressed or extruded into densified solid fuel with higher bulk density and higher calorific value, which makes it convenient in transportation and storage. The compressing technology of biomass is considered as one of the simplest and the most direct way to utilize biomass as a fuel in the world. However, due to the different chemical composition of biomass, the compression mechanism of biomass particles is different from other particles of coal, ceramics, metals and other materials. A comprehensive study on the compression mechanism of densified biomass fuel was carried out in this paper. The effects of the common chemical components of biomass on the quality of the densified fuel were further explored. The purpose of this paper is to provide a theoretical basis and a technical reference to understand the compression mechanism of biomass.

Abstract: Biomass is a kind of clean energy, which is inexhaustible and renewable. Densifying biomass into solid fuel has become one of the most important ways of utilizing biomass as a source of energy, which can overcome the shortcomings of biomass, such as low heat value, small buck density and irregular shape, etc. The main processing methods and equipments for densified biomass fuel were introduced in the paper, including their main components and working principles. The performances comparison between different types of equipment were analyzed. The purpose of this paper is to provide a reference for developing equipments of densified biomass fuel to promote a further development of densified biomass fuel industry in China.

Abstract: In this paper, the pyrolysis characteristics of Chlorella vulgaris (C. vulgaris) (a kind of microalgae) under different microwave power and pyrolysis atmosphere are studied by microwave oven. The results show that under N₂ atmosphere, a power of 1500W is required for optimal oil production, 2250W for optimal gas production and 750W for optimal residue. Under CO₂ atmosphere, a power of 2250W is required for maximum oil production, 1500W for maximum gas production and 750W for maximum residue.

Abstract: In order to reduce the environmental pollution of coal-fired heating, coal plus biomass co-firing has been put into test. In this experiment, based on the a 20t coal-fired steam boiler of heating company in northeastern region, through observing the data that generated by different fuels ratio, it did the economic and social analysis by using contrast method and computer technology. The results showed: when the ratio of straw and coal is 1:11, it gains optimal benefit.

Abstract: As the only renewable energy which can be converted into liquid fuels, biomass has developed various technologies of energy utilization. In order to adjust the syngas composition, increase the ratio of H₂/CO and reduce CO₂ content, this paper conducted biomass gasification experiment in an entrained flow bed on CaO sorption. The paper studied influence factors like the gasification temperature, ratio of CaO/B and gasification parameters, such as ratio of H₂/CO, cold gas efficiency, cold gas yield or tar content in syngas. The result showed that raising gasification temperature or increasing added content of CaO which were beneficial to the improvement of H₂ content. A maximum H₂ output with a concentration of 62.7% and H₂/CO ratio of 3.19 was achieved at CaO/C=1, H₂O/B=0.3 and T=1100°C, meanwhile the cold gas efficiency was 86.07%, the cold gas yield reached 1.2Nm³/kg biomass, and the tar content was dropped to 314.6mg/Nm³.

Abstract: To improve the gas production ability, relatively low cost H₃PO₄ was chosen as the pretreating agent in this study. Rice straws were pretreated by four different weight percentages (2%, 4%, 6% and 8%) of H₃PO₄ retting for seven days in an biochemical incubator at (25±1) °C, and the effects with different conditions of H₃PO₄ pretreatment on anaerobic digestion of rice straws for variation of components and anaerobic digestion performance (under temperature of (35±1) °C) were studied. The results showed that the peak value of biogas production was attained on the 1^st day for using 6% H₃PO₄ pretreatment on rice straw, which is 2284 mL. The test daily methane content of different pretreatment conditions mainly ranges from 3.8% to 43.1%, with the highest recorded at the 12^th day of the 2% H₃PO₄- treated rice straw. The cumulative biogas production of 6% H₃PO₄ pretreatment was the highest, about 16 474 mL.

Abstract: To discuss the effect of NaOH pretreatment technology for biogas production and methane (CH₄) content enhancement during the anaerobic digestion of rice straw waste, a self-designed laboratory-scale continuous anaerobic biogas digester was used in this study. Anaerobic biogas slurry, NaOH pretreatment and anaerobic digestion were evaluated for biogas production from rice straw. The results showed that the peak value of biogas production was attained on the 16^th day by using 6% NaOH pretreatment on rice straw. However, the highest CH₄ content was 60.8% on the 24^th day for the 4% NaOH-treated rice straw. The cumulative biogas production of 6% NaOH pretreatment was the highest, about 18 720 mL, which was followed by 8% NaOH (15 057 mL), 4% NaOH (12 103 mL), and 2% NaOH (10 754 mL).

Abstract: Lignocellulosic biomass gasification is considered as one of the effective methods for transforming scattered biomass into heat, power and various chemicals. As a fundamental step for biomass gasification, pyrolysis has remarkable influence on products distribution and char reactivity during the further step. Further research on the pyrolysis process of lignocellulosic biomass is beneficial to optimize and promote the process of gasification. In this paper, pyrolysis characteristic of a kind of lignocellulosic biomass model compound (cellulose) was explored through thermogravimetric analyzer. The temperature was from 25 °C to 950 °C under various heating rates (10, 20, 40 °C·min^-1) with nitrogen atmosphere. A three step selecting method for mechanism function was used to check out the optimum model from fifteen kinds of most frequently used mechanisms. The results indicated that under various heating rates, the optimum mechanism model for the cellulose in this paper was different. The values of activation energy and frequency factor for cellulose pyrolysis calculated by the three step method in this paper under 10, 20, 40 °C·min^-1 were 245.95, 212.09 and 144.27 kJ·mol^-1, 8.47E+17, 5.35E+18 and 1.20E+11 s^-1, respectively.