Studies on the preparation and properties of particle boards made from bagasse and PVC. I: Effects of operating conditions

Under study were the mechanical properties of particle boards comprised of ground sugarcane bagasse, PVC, and poly{methylene (polyphenyl isocyanate)} [PMPPIC]. The effects of different parameters, e.g. mixing temperature, molding conditions - platen temperature, time and pressure, particle size of bagasse, concentration of PVC and PMPPIC, as well as dilution of PMPPIC, on the mechanical properties of the resulting particle boards were also investigated. In general, the properties of particle boards change with the variation of mixing and molding conditions. A mixing temperature of 175°C and molding conditions [platen temperature, 190°C; time, 10 min; and pressure, 3.8 MPa] were believed to be optimal conditions of compounding particle boards. Both the mechanical properties and the density of particle boards of bagasse with a mesh size of 60, improved up to 20 weight % of PVC and 10 weight % of PMPPIC.     

Pyrolysis behaviour of Australian oil shales in a fluidized bed reactor and in a material balance modified Fischer assay retort

The pyrolysis behaviour of several Australian oil shales was determined using the material balance modified Fischer assay and a bench-scale fluidized bed pyrolysis reactor, with nitrogen or steam as the sweep gas. The assay oil yield, which ranged from 5.3 to 15.7 wt% of the dry shale, did not correlate well with the organic carbon contents of the shales. However, under both assay and fluidized bed pyrolysis conditions, a shale of high kerogen H/C had high organic carbon conversions to oil. Compared with the Fischer assay, nitrogen pyrolysis gave 7 ± 4 wt% more oil for the shales studied, and steam pyrolysis gave 15 ± 4 wt% more oil for all shales except one, which showed a 35 wt% increase in oil yield. However, the oils from both nitrogen and steam pyrolysis had lower H/Cs, higher sulphur and nitrogen contents, and more high boiling point fractions than those from the Fischer assay. Nitrogen pyrolysis oils were of higher quality than those produced by steam pyrolysis. With steam as the sweep gas, much more hydrogen and hydrogen sulphide were produced for all shales; in most cases, there was also more carbon monoxide and less hydrocarbon gases.     

Continuous enzymatic production of biodiesel from virgin and waste sunflower oil in supercritical carbon dioxide

A continuous process for biodiesel production in supercritical carbon dioxide was implemented. In the transesterification of virgin sunflower oil with methanol, Lipozyme TL IM led to fatty acid methyl esters yields (FAME) that exceeded 98% at 20 MPa and 40 °C, for a residence time of 20 s and an oil to methanol molar ratio of 1:24. Even for moderate reaction conversions, a fractionation stage based on two separators afforded FAME with >96% purity. Lipozyme TL IM was less efficient with waste cooking sunflower oil. In this case, a combination of Lipozyme TL IM and Novozym 435 afforded FAME yields nearing 99%.     

Influence of carbon black on decompression failure and hydrogen permeation properties of filled ethylene‐propylene–diene–methylene rubbers exposed to high‐pressure hydrogen gas

Eight carbon black (CB)‐filled ethylene–propylene–diene–methylene linkage (EPDM) rubbers were manufactured by varying the content and type of CB. Then, the relationship among crack damage caused by high‐pressure hydrogen decompression, the hydrogen permeation properties, and the mechanical properties of the rubbers was investigated. The hydrogen gas permeability of the rubbers decreased with an increase in the CB content and depended little on primary particle size. In contrast, the hydrogen gas diffusivity and solubility depended on both the CB content and primary particle size, that is, the hydrogen gas diffusivity decreased with an increase in the CB content and a decrease in the primary particle size, and the hydrogen gas solubility increased with an increase in the CB content and a decrease in the primary particle size. As for the mechanical properties, the CB‐filled rubbers were more strongly reinforced by an increase in the CB content and a decrease in the primary particle size. The crack damage by high‐pressure hydrogen decompression became larger as the ratio of the hydrogen gas solubility to estimated internal pressure at crack initiation relating to the mechanical properties became larger. As a smaller CB particle increases the hydrogen gas solubility of EPDM rubbers, while at the same time it reinforces the rubbers, the crack damage in the CB‐filled rubbers was not influenced by the primary particle size. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Co-pyrolysis of sugarcane bagasse with petroleum residue. Part II. Product yields and properties

The main objective of the present work was to study the pyrolysis under vacuum of sugarcane bagasse combined with petroleum residue (PR), in terms of yields and properties of the products obtained. Important synergetic effects were observed during the co-pyrolysis in a fixed bed reactor leading to an increase in charcoal yield. Maximum charcoal and minimum oil yields were obtained with 15 wt% of PR mixed with bagasse. At this concentration, sugarcane bagasse charcoal is almost completely covered with PR-derived pyrolytic carbon. At concentrations higher than 15 wt%, hydrocarbon vapours interacted less with the bagasse charcoal. Consequently, an appreciable increase in oil yield was observed. The oils obtained are complex emulsions, which consist of oxygenated compounds originating from bagasse, hydrocarbons originating from PR and water. Oils obtained from feedstock with concentrations up to 15 wt% PR are stable emulsions consisting of PR-derived products in bagasse-derived oil. The oil obtained from the 30 wt% PR-bagasse blend is an unstable emulsion. However, the emulsion obtained at 50 wt% PR is again stable. In this emulsion, the PR-derived oil constitutes a continuous phase. This emulsion exhibits a carbon Conradson residue value (9 wt%) similar to that of PR-derived oil. A detailed characterization of the gas, oil and charcoal co-pyrolysis products is presented.     

Water electrolysis and pressure drop behaviour in a three-dimensional electrode

Water electrolysis from acidified solution was used as a model system to investigate the net contribution of hydrogen bubbles to the pressure drop increase in a three-dimensional electrode. A bed of silvered glass beads in both fixed and fluidized state was used, assuming an unchanging particle surface during the experiments. Pressure drop behaviour with time was measured for different experimental conditions and presented relative to the pressure drop determined for a bubble free bed. Parameters, such as current density, electrolyte velocity and particle size, greatly influence the relative pressure drop behaviour in the three-dimensional electrode. A sudden increase in the pressure drop occurs with the appearance of a gas phase in the bed, reaching a constant value (plateau) after a certain time; this plateau corresponds to steady state conditions. The pressure drop increases with increasing current density. This increase is in the range 40-150% relative to the bubble free electrolyte flow through the bed. Electrolyte flow-rate also strongly influences the pressure drop in the hydrogen evolving fixed bed electrode. It was observed that the relative pressure drop decreases with increasing electrolyte velocity. At higher flow rates, peaks occur on the pressure drop-time curves, indicating the existence of channeling inside the bed in which spouting occurs. The time to reach the pressure drop plateau decreases with increasing electrolyte velocity as do the time intervals corresponding to maximum pressure drop values. At the minimum fluidization velocity the peaks disappear and the relative pressure drop decreases with time, tending to approach a constant value. For hydrogen evolution in the fluidized bed, the pressure drop is lower than that measured in the absence of gas, and reason for this decrease being the gas hold-up in the bed.     

三维上流式反应器床层流动和返混特性

采用内径为280 mm的上流式反应器,以空气模拟气相、甘油和水混合溶液模拟渣油。用3种不同粒径的氧化铝球形工业催化剂颗粒为填充颗粒,考察了不同模拟物系的颗粒粒径、颗粒密度、液相黏度、不同床层的高径比和不同操作条件对上流式反应器内床层压降及其波动、床层轴向返混的影响规律。得到模拟工业运行物系和操作条件的上流式反应器床层总压降关联式,相对误差在12%以内。床层总压降均随床层高径比、颗粒密度和液相黏度增加而增大,但随颗粒粒径的增大而减小,床层压降波动随表观气速增加而增大。填充颗粒粒径越小、颗粒密度越小、高径比越大,床层内轴向返混越严重;床层内压降和轴向返混均随表观气速的增加而增大。     

Influence of temperature and pressure on carbon black size distribution during allothermal cracking of methane

Allothermal cracking of methane is a suitable and eco-friendly way to simultaneously produce hydrogen and carbon black. The economic viability of the process relies on the ability to produce carbon black having well-defined characteristics, particularly concerning the particle size. A model for the study of the carbon particle size distribution during thermal cracking of methane has been developed. The model takes into account: heat transfer by conduction, convection, particle and gas radiation, homogenous and heterogenous reactions of methane dissociation, nucleation, and growth of solid carbon particle formed. The model alleges nanoparticles are in thermal equilibrium and do not impact the flow. A parametric study is made on operating pressure and temperature. As a result, the increase of the pressure and temperature increases the yield of thermal methane cracking. Moreover, results show a particle size distribution becoming narrower with increasing temperature and/or pressure. In these conditions, the particles population tends to be monodispersed.

Copyright © 2016 American Association for Aerosol Research     

膨化/生物法预处理对纤维素酶酶解蔗渣的影响

膨化后的甘蔗渣再进行白腐菌处理,其酶解得率高达92％以上。膨化使甘蔗渣纤维素结晶度下降,蔗渣纤维的三大组分含量也有较大的变化。试验表明,最佳膨化条件为：浸泡碱质量浓度40g/L,浸泡时间6h,压力0．6MPa,保温时间5min。     

Roasted Sunflower Kernel Paste (Tahini) Stability: Storage Conditions and Particle Size Influence

Sunflower tahini faces quality problems due to the tendency of oil to exudate, causing accelerated rancidity and low marketability. In this study, the colloidal and oxidative stability of different trimodal particle size distributions of sunflower tahini (cumulative volume percentages of small, middle and large class populations of 9.61–16.67, 43.03–55.03 and 47.36–28.3) was evaluated during storage at three different temperatures. Decreasing sample particle size decreased the sunflower tahini colloidal stability. The coarsest prototype, being the most stable tahini in terms of oil separation, was included in the oxidative stability storage test together with a commercial tahini. The peroxide values of the studied sunflower tahini samples increased significantly (p < 0.05) with storage time, irrespective of storage temperature, while the p‐anisidine values showed an irregular pattern. Considering 30‐meq O₂/kg as a PV limit, the commercial tahini showed good oxidative stability as it was under this when stored 3 months at 4 °C, 2 months at room temperature and 1 month at 40 °C. The coarsest tahini sample was under the limit when stored 2 months at 4 °C, 1 month at room temperature and 2 weeks at 40 °C. Particle size was shown to be an essential parameter for controlling sunflower tahini's overall stability.     

Product evolution during rapid pyrolysis of Green River Formation oil shale

The devolatilization of rich (209 cm³ kg⁻¹), rapidly heated (1000 K s⁻¹) Green River Formation, Colorado, oil shale has been studied at temperatures from ≈ 600 to 1100K, under helium (170 kPa) and vacuum. Oil yields decrease with increasing pressure at temperatures above the 800–900 K range. This is attributed to an increased probability of condensed phase cracking reactions involving oil precursors with increased pressure. The fact that escape of the oil from shale particles is vaporization-rate limited is supported by a comparison of the molecular weights of oil collected outside the particle and that left within the particle. The measured nature of particle porosity is consistent with the view that external gas pressure can affect vaporization rates within pores. Elemental and infrared characterization of different molecular weight fractions of oil are presented.     

Farm-scale recovery and filtration characteristics of sunflower oil for use in diesel engines

The “Hander,” new Type 52 oil expeller was evaluated to determine its performance in expressing sunflower oil for use in diesel engines. Strain gauges were mounted on the barrel of the expeller and were used to give a relative indication of barrel pressure. Relative barrel pressure was then used as the independent variable in determining performance. Filterability of four commercial sunflower oils and blends of these oils with No. 2 diesel fuel were determined at various temperatures and pressures. Oil extraction efficiency ranged from ca. 56% to 84% at low and high relative barrel pressures, respectively. The greatest oil extraction rate was 12.3 kg/hr at a feed rate of 40 kg/hr with an extraction efficiency of ca. 80%. Dewaxed sunflower oils and blends filtered much better than nondewaxed oils and their blends. Increasing temperature, pressure and percentage of diesel fuel in the blends increased filterability of dewaxed sunflower oil. Work on this project is supported by North Dakota Agricultural Experiment Station Project 1439.     

Hydro-liquefaction of woody biomass in sub- and super-critical ethanol with iron-based catalysts

Hydro-liquefaction of a woody biomass (Jack pine powder) in sub-/super-critical solution of ethanol without and with iron-based catalysts (5 wt% FeS or FeSO₄) was investigated with a stainless steel micro-reactor (10 mL) at temperatures of 473-623 K and an initial pressure of hydrogen varying from 2.0 to 10.0 MPa. Without catalyst, the oil yields were in the range of 17% and 44%, depending on temperature, reaction time and initial pressure of hydrogen. With catalysts, the Oil yields significantly increased while the yields of solid residue and gases and water decreased. A high oil yield of 63% was obtained with FeSO₄ at 623 K and 5 MPa of H₂ for 40 min. The elemental analyses and GC/MS measurements for the Oils revealed that the liquid products have much higher heating values than the crude wood sample and phenolic compounds were dominant in the Oils, irrespective of whether or what catalyst was used.     

用于PEMFC的天然气水蒸气制氢系统

针对质子交换膜燃料电池（PEMFC）的应用要求,开发了一个包括天然气水蒸气重整、CO变换和变压吸附净化的制氢工艺过程,并着重对重整反应和变压吸附的操作条件进行了实验研究。考察了温度、空速和水碳比对重整反应的影响,得到适宜的工艺操作条件,实验结果表明：温度650℃、水碳比6、空速42h^-1时,氢气含量为70.21%,甲烷转化率为77.41%;分析了温度、流速对变压吸附脱除CO效果的影响,结果表明：在0.2MPa、40℃和吸附、脱附时间120s的条件下,产品气中CO浓度接近于1×10^-6,经过多次循环后产品气质量稳定,可以连续获得满足80W质子交换膜燃料电池要求的高纯度氢气。     

Interesterification of tea seed oil and its application in margarine production

Blends of hydrogenated and nonhydrogenated tea seed oil (Lahijan variety) (30:70, w/w) were chemically interesterified at 60, 90, and 120°C for 30, 60, and 90 min in the presence of 1% (w/w) NaOH. Physicochemical properties of the products were compared with those of the noninteresterified mixture. Statistical comparison of m.p., iodine values (IV), and solid fat contents (SFC) showed that the sample having the highest ranking was interesterified at 120°C for 30 min. The sample was used as a hardstock (40%), with liquid tea seed oil and sunflower oil (ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100) as, a softstock (60%) for production of table magarine, and the properties of these margarines were compared with those of commercial ones. Samples E and D (ratio of 80:20 and 60:40 liquid tea seed oil/sunflower oil, respectively) had the lowest significant differences with commercial table margarine for physicochemical (m.p., IV, and SFC) and organoleptic characteristics, respectively. Generally, based on m.p. and SFC, margarines E and D were classified as soft margarine. The trans FA content of E, D, and commercial margarines were 1.8, 1.8, and 2.2%, respectively.     

Characterization of naphtha and carbon black obtained by vacuum pyrolysis of polyisoprene rubber

Pure polyisoprene and a commercial rubber sample containing 52% polyisoprene and 31% carbon black were pyrolysed at 500°C and at a total pressure varying between 0.8 and 28.0 kPa. The yields of gas, oil and pyrolytic carbon black (CB_P) changed little with the pyrolysis pressure. However, the oil composition and the CB_P characteristics depended considerably on the pyrolysis pressure. For example, the amount of dl-limonene, a valuable compound in the naphtha fraction, decreased with increasing pyrolysis pressure. The CB_P and the commercial carbon black initially present in the rubber sample were analysed by ESCA, SIMS and SEM. With decreasing pyrolysis pressure the surface chemistry of the CB_P became similar to that of the commercial carbon black initially present in the rubber. Therefore, rubber pyrolysis should be performed at low pressures in order to obtain products with a higher commercial value.     

Comprehensive study of the influence of total pressure on products yields in fluidized bed gasification of wood sawdust

Wood sawdust gasification experiments were performed in a steam fluidized bed at 800 °C between 2 and 10 bar. An evolution of gas yields with time was measured during the tests, and especially an increase of hydrogen and carbon dioxide yields. This test duration effect was ascribed to char build-up in the bed. As tests proceed, the contribution of char steam gasification to gas yield increases, and the catalytic effect of char on hydrocarbons and tar conversion and on water-gas shift reaction is enhanced.As total pressure increases from 2 to 10 bar, hydrogen, carbon dioxide and methane yields increase by 16%, 53% and 38% respectively, whereas carbon monoxide yield decreases by 33%. The changes in gaseous yields with pressure can be partly explained by the influence of pressure on gas phase reactions (acceleration of water-gas shift kinetics and change in hydrocarbon reactions). The increase of methane yield with pressure is rather suggested to be linked to a change in secondary pyrolysis reactions scheme under high pressure.     

几种典型铁矿粉的流化特性

利用内径150 mm的D型有机玻璃流化床模型,对澳矿、巴西矿、北方矿和钒钛矿典型铁矿粉的流化特性进行了实验研究,获得了其流化特性曲线、初始流化速度和最大床层压降,并将初始流化速度的实测值和理论计算值进行了比较分析. 结果表明,矿粉粒度是影响其流化特性的最主要因素,粒径越大,床层所需要的初始流化速度越大,实测值和理论估算值基本相符;粒度小于0.125 mm钒钛矿流动性较差,在流化过程中易出现沟流现象;粒度范围较宽的矿粉,完全流态化时,细矿粉随气流夹带逸出明显;在粒度相同的情况下,几种不同的铁矿粉的开始流化速度接近,而床层压降有较大差异,巴西矿的床层压降明显大于其他三种铁矿粉. 最大床层压降的最小值均出现在粒度为0.25~0.425 mm,为铁矿粉流态化还原过程中较适宜的粒度范围.     

喷动床中气体停留时间分布的研究

In a spouted bed of 80mm in ID and 1700mm in height, the gas residence time distributions at different radial positions in both spout and annular area were measured with five different kinds of particles as spouting material, air as spouting gas, and hydrogen as tracer. The effects of superficial gas velocity, operating pressure, particle size and its category on gas residence time distribution were discussed. It was found that the gas velocity profile in spout was more uniform than that in annulus. It could be concluded that the gas flow in the spout could be treated as a plug-flow, while that in the annulus inhibited a strong non-ideal flow behavior. Increasing the superficial gas velocity and decreasing the operating pressure, the particle density and its size gave rise to spouting disturbance, thus the measured tracer concentrations vs. time curves fluctuated. The variances of residence time distribution curves could be taken as a measure of the gas fluctuation degree.