Advanced Materials Research Vols. 781-784

Abstract: The oil/water interfacial properties and the stability of the emulsion of ASP flooding in Daqing Oilfield were investigated with the measurement of interfacial tension, interfacial shear viscosity,Zeta potential and turbidity of the oil/water system. The results show that, after NaOH has reacted with Daqing crude oil for a long time, the interfacial tension between the aqueous phase and Daqing model oil decreases. The absolute value of the Zeta potential of the surface of oil droplets increases. The changes of the interfacial shear viscosity between the aqueous phase and the oil phase do not appear to be obvious. The stability of O/W emulsion formed by Daqing model oil and the aqueous phase is enhanced. After NaOH has reacted with crude oil for 1d, the interfacial tension between oil phase and simulated water, Zeta potential and the stability of the oil/water emulsion become higher than that of the emulsion without NaOH. However, after NaOH has reacted with crude oil for 10 d and 30 d, respectively, the interfacial tension between oil phase and simulated water, Zeta potential and the stability of the O/W emulsion are lower than that of the emulsion with the same reaction for 1d.

Abstract: Biodiesel is an alternative energy resources, which produced from transesterification of oils and alcohols using homogeneous and heterogeneous catalysts. Ultrasonic was used as pre-mixer for KOH, Na₂SiO₃, palm oil and methanol before increasing the reaction temperature to 60°C using a water bath. All experiments were conducted at a molar ratio of methanol:oil of 6:1, reaction time of 60 min, reaction temperature of 60C and well mixing. The suspension was filtered after the end of the reaction. Purified biodiesel was obtained by water washing processes after crude biodiesel was separated from glycerol by 2 hr standing in a separating funnel. Filter solid cake was instantly used as supporter in next batch of the reaction. Effects of four variables, namely, pre-mixing period in the range of 0-10 s, number of filter cake recycle (2-4 cycles), sonicator power (10-90% of max. power of 200 watt and 20 kHz) and amount of KOH addition (0.25-0.75 g) were investigated. Response surface methodology was employed to evaluate and optimize the biodiesel production processes using Na₂SiO₃ adsorbed with KOH as catalyst. The design of experiment was carried out using the MINITAB RELEASE 16 and a result of 31 experiments was suggested to be made. The result showed the optimum condition of pre-mixing period of 14 s, the number of catalyst recycle to be 2 cycle, sonicator power of 36.3%and KOH addition of 0.3 g.

Abstract: The gas-liquid volumetric mass transfer coefficient was determined by the dynamic oxygen absorption technique using a polarographic dissolved oxygen probe and the gas-liquid interfacial area was measured using dual-tip conductivity probes in a bubble column slurry reactor. Feed-forward back propagation neural network models were employed to predict the gas-liquid volumetric mass transfer coefficient and liquid-side mass transfer coefficient for Alcohol/Ether fuel direct synthesis system in a commercial-scale bubble column slurry reactor. And the effects of various axial locations, superficial gas velocity and solid concentration on the gas-liquid volumetric mass transfer coefficient k_La_L and liquid-side mass transfer coefficient k_L were discussed in detail in the range of operating variables investigated.

Abstract: Co-utilization of coal and biomass has been shown as an effective way to reduce the carbon footprint. Pyrolysis technology not only transform carbonaceous materials such as coal and biomass into various chemical compounds and fuels, but also as the initial step of the thermochemical conversation. For the sake of a better understanding of the co-thermal conversation, it is very necessary to get a intensive study on the co-pyrolysis of coal and biomass. In this paper the co-pyrolysis characteristics of coal and spent mushroom compost (SMC) were investigated through an thermogravimetry analyzer from ambient temperature to 950 °C at different heating rates (10, 20 and 40 °C/min) under nitrogen condition. Kinetic parameters were determined by the by the Flynn-Wall-Ozawa (FWO) method. It was found that the activation energy decreased with the increasing of the biomass mass ratio, but with the biomass ratio reached 0.75 the activation energy increased again. This may be involved with the negative synergies between the biomass and coal. The results could provide useful information for the further study on the co-pyrolysis of coal and MSC.

Abstract: Supercritical Rankine cycles using organic fluids as working fluids in converting low-grade energy to high-grade power energy are investigated in the study. The main purpose is to identify suitable working fluids which may yield high system efficiencies in a supercritical Organic Rankine Cycle (ORC) system. R123, R134a, R152a, R22, and R245fa are used for the research. Results show that: at a constant superheating of expansion outlet, system efficiency improves with the increasing of evaporation pressure for all the working fluids and supercritical ORC has a higher efficiency than sub-ORC process. Furthermore, R152a performs the best compared with other refrigerants and is suitable for SORC system.

Abstract: One bituminous coal was modified with H₂O₂, (NH₄)₂S₂O₈ and HNO₃ respectively, to prepare coal samples with different surface properties. The oxygen groups on coal surface were characterized by X-ray photoelectron spectroscopy (XPS). The textures of the coal samples were investigated by N₂ adsorption at 77 K. The methane adsorption behaviors of the coal samples were measured at 303 K in pressure range of 0-5.3 MPa by a volumetric method. The methane adsorption data were fitted to the Langmuir model. It was observed that there was, in general, a positive correlation between the methane adsorption capacity and the S_BET of coals while a negative correlation between methane saturated adsorption capacity and the O_total/C_total. The methane adsorption capacity was determined by the coal surface chemistry when the microporosity parameters of two samples were similar. Coal with a higher amount of oxygen surface groups, and consequently with a less hydrophobic character, had lower methane adsorption capacity.

Abstract: A quantitative multivariate linear regression equation is established with the net calorific value of woody biomass fuel as the dependent variable and proximate analysis indexes as the independent variables. The prediction effect of the regression model is evaluated by the error analysis method. Results show that within the variable application ranges, the prediction error of the multiple linear regression model developed is small, and it could provide basis and reference for the calorific value prediction of woody biomass.

Abstract: Biomass-to-SNG technology is one of the most important applications of biomass energy. The simulating model of the SNG production via interconnected fluidized beds was established and the biomass-to-SNG process was simulated. The effects of the operating conditions of the gasifier, like the gasification pressure, gasification temperature and the steam to biomass ratio (S/B), on the composition of crude methane gas were studied. The simulating results showed that there was an optimum gasification temperature and pressure for the highest methane content in the crude methane gas, while S/B had adverse effects on it. To achieve higher methane content, the suitable gasification temperature is about 750 °C, S/B is about 0.4, and the gasification pressure may be not too high.

Abstract: Microwave catalytic pyrolysis of sewage sludge were conducted on a single mode microwave reactor. The effects of CaO and steam on hydrogen-rich gas formation characteristics were analyzed. The results indicated that the CaO can improve the formation of H₂ and CO. When CaO in sewage sludge increased from 0 to 0.75 g/(g dried sludge), the H₂ and CO concentration increased from 62 vol.% to 77 vol.%, while CH₄ and CO₂ concentrations decreased from 28 vol.% to 9 vol.%. The steam can also improve the formation of H₂ and CO, with 1.59 g/min of the steam flowrate, the H₂ and CO concentration increased to the maximum of 81 vol.%, and the CH₄ and CO₂ concentration decreased to the minimum of 16 vol.%. When the steam gasification was coupled with the CaO catalyzing, the H₂ concentration can reach to 61 vol.%, which was 79.3% higher than the experimental conditions absent of steam and CaO.

Abstract: Research on the synthesis of BrOnsted acidic ionic liquid by the method of solvent, the pyrolysis bio-fuel with cornus wisoniana oil drop acid esterification reaction, the catalyst dosage, reaction time and reaction temperature on the effects of the acid dropping and in the best optimization under the condition of the stability of the catalyst were investigated. The experimental results show that [BSPHSO₄ with high catalytic activity, optimization of process conditions as follows: 1.2% of catalyst, reaction temperature 75 °C, reaction time of 70 min, acid value reduced to 2.0 mg KOH/g. By optimizing the cycle experiment, the stability of the catalyst performance is good, the catalytic activity is relatively stable.