高酸值生物柴油原料的预酯化反应装置的实验研究

以固体酸为催化剂,对高酸值废弃油脂进行预酯化反应研究。讨论了不同降低水分含量的方法对反应的影响,并考察了反应条件(醇油摩尔比、反应时间)对预酯化效果的影响。实验结果表明:在反应体系中添加吸水剂分子筛可提高预酯化反应效率;反应体系中添加过量的甲醇能大大缩短反应时间,在反应温度75℃,催化剂加入量为10%(W/W),最佳醇油摩尔比8∶1,最佳反应时间4h的条件下,可将酸化油的酸值降至3.8mgKOH.g-1,满足酯交换反应酸值小于4.0mgKOH.g-1要求。     

花椒籽油生物柴油制备工艺研究

以花椒籽油为原料,对KOH催化其与甲醇发生酯交换反应制备生物柴油进行研究。采用物理萃取法降低花椒籽油中游离脂肪酸的含量,三次萃取后酸值达到2 mgKOH/g以下。研究了花椒籽油和甲醇在氢氧化钾催化下的酯交换反应。进行了不同醇油摩尔比、催化剂用量、反应时间、反应温度等反应条件下对产率的影响,得到最佳反应条件为醇油物质的量之比为12∶1,催化剂添加量为油脂质量的1.2%,反应温度为60～65℃,反应时间为45 min。     

花椒籽油生物柴油制备工艺研究

以花椒籽油为原料,对KOH催化其与甲醇发生酯交换反应制备生物柴油进行研究.采用物理萃取法降低花椒籽油中游离脂肪酸的含量,三次萃取后酸值达到2 mgKOH/g以下.研究了花椒籽油和甲醇在氢氧化钾催化下的酯交换反应.进行了不同醇油摩尔比、催化剂用量、反应时间、反应温度等反应条件下对产率的影响,得到最佳反应条件为醇油物质的量之比为12∶1,催化剂添加量为油脂质量的1.2％,反应温度为60 ～65℃,反应时间为45 min.     

高酸值油料一步法制备生物柴油研究

以酸值123.04 mg KOH/g的棕榈油脱臭馏出物(PFAD)为原料,在带压反应器中,用浓硫酸为催化剂,采用一步法催化酯化反应制备生物柴油。重点研究反应温度、反应时间、催化剂用量和醇油比等因素对酯化和酯交换反应的影响。结果表明,提高反应温度能促进酯化反应和酯交换反应,使高酸值原料经一次反应直接转化为目的产物——脂肪酸甲酯,从而缩短制备流程,降低成本,强化酯化反应进行,提高脂肪酸甲酯收率。当催化剂用量为0.5%(质量分数)、醇油物质的量之比7∶1、在130℃反应90 min后,生物柴油的最高收率达到88.1%。较之酸碱两步法催化高酸值油料制备生物柴油能显著缩短反应时间、简化工艺流程、降低生产成本。     

馏分油脱酸剂技术研究及应用进展

从馏分油中脱除环烷酸是石油炼制的一个重要步骤。针对传统碱洗电精制工艺存在碱和酸用量大、乳化严重、能耗高及环境危害大等缺点,开发了馏分油脱酸剂技术。其中,Ⅰ型技术主要用于各种高酸(度)值、高密度和高黏度的常压馏分油与减压馏分油的脱酸精制。Ⅱ型技术主要应用于酸度小于100mgKOH/100mL的轻柴油的脱酸精制。Ⅲ型技术还处于实验研究阶段,确定的适宜操作条件为:反应温度20～70℃、脱酸剂用量为待处理原料油质量的2.0%。在此条件下,所得精制柴油的酸度为0.2mgKOH/100mL,精制油质量收率达99.8%。与其他工艺相比,Ⅲ型技术使用强碱溶剂脱酸,剂油比低至2.0%,聚结温度低,能耗低,无废水排放,有利于环保;同时碱渣油含量显著降低,环烷酸质量也有所提高,粗酸值达到186.2mgKOH/g,油含量仅11%。目前正在进行真正意义上的绿色脱酸工艺实验研究。     

固体超强酸SO2-4/TiO2-SiO2催化制备生物柴油

叙述了以固体超强酸SO4^2-／TiO2-SiO2为催化剂,催化大豆油和甲醇的酯交换反应制备生物柴油的实验。结果表明,该催化剂对酯交换反应有很高的催化活性,催化剂的活性不受体系中游离脂肪酸的影响。在醇油摩尔比为13：1时,每摩尔油使用1．0g催化剂,125℃反应3h,脂肪酸甲酯的收率达90％。催化剂的吡啶红外谱图表明催化剂具有L酸中心和B酸中心,催化剂的NH3-TPD曲线表明催化剂具有超强酸性。     

四种原油评价与可行性加工方案探讨

对巴士拉原油、龙卡多原油、梵高原油、邦加原油的一般性质、直馏产品收率、产品性质进行比较和数据分析,结合大连石化现状,对原油加工方案进行探讨.结论认为,巴士拉原油各直馏馏分的收率比例适中,硫含量高,需要与其他硫含量低的原油混炼;龙卡多原油各直馏馏分的收率比例适中,但是硫含量高,酸值达到0.5mgKOH/g,需要与其他硫含量低、酸值低的原油混炼;邦加原油除减压塔底油收率稍低外,其他各直馏馏分的收率比例适中,但酸值高达0.5mgKOH/g,需要与其他酸值含量低的原油混炼;梵高原油为偏重原油,重整原料、航煤和柴油馏分收率小,大部分为减压馏分和渣油馏分,酸值超过1.0mgKOH/g,加工时会严重腐蚀常减压装置,应根据需要掺炼其他酸值低的原油,后续加工可通过催化裂化或加氢裂化等深度加工工艺,生产出高价值的轻馏分油.原油评价为生产计划系统、生产调度排产系统和原油优化调合系统提供数据支持,并为选择效益最优的原油采购方案,确保生产装置平稳运行,保证原油加工效益最大化提供技术支持.     

季铵碱催化剂在合成生物柴油中的应用

对合成生物柴油的几种方法进行了比较,讨论了以季铵碱作催化剂,以大豆油为原料合成生物柴油的工艺条件,并研究了原料油的酸值和含水量对脂肪酸甲酯转化率的影响.试验结果表明,该酯化及转酯化反应的最佳反应条件:催化剂的投入量为油重的0.5%,油醇的物质的量比为1∶6,反应温度为60℃,搅拌时间为30min;原料油的酸值小于2,原料水分质量分数在1%以下.     

桐油制备生物柴油的研究

以桐油为原料,研究了高酸值原料油的预酯化工艺条件,以及酯交换反应过程中甲醇加入的方式.对桐油预酯化工艺条件的研究结果表明,在搅拌速度一定的情况下,预酯化工艺的最佳条件为醇油摩尔比7∶1、硫酸用量为1.5%(质量比)、反应温度70℃、反应时间2 h;在研究的四个因素(醇油摩尔比,催化剂浓度,反应温度,反应时间)中,反应温度对酯化反应转化率的影响最大.在酯交换反应过程中,对分批加入甲醇的初步研究结果表明,在醇油摩尔比6 ∶1、KOH浓度 1%(质量比)、反应温度60℃、反应时间1 h的条件下,分两批加入甲醇的收率比一次加入甲醇的收率提高了4%.     

固体超强碱催化乙醇酯化生物油

利用固体超强碱KF/γ-Al2O3为催化剂,以乙醇与生物油中的有机酸酯化反应为基础,探讨催化酯化对生物油的提质改性效果.考察了改质前后生物油的基本理化性能,采用四球摩擦磨损试验机研究了改质前后生物油的摩擦学性能,利用GC-MS分析了其酯化前后生物油的组成.结果表明:催化酯化反应后的生物油的运动粘度和酸值降低,抗磨和减摩性能提高,酯化后的生物油中酸类成份含量降低、酯类成份含量明显增大.醇油质量比为2∶1,50℃温度下采用固体超强碱KF/γ-Al2O3催化酯化反应2h,反应前后相比,油品酸值降低了29.08％、平均摩擦系数降低了32.53％、磨斑直径减小了11.79％.     

Performance assessment of some ice TES systems

In this paper, a performance assessment of four main types of ice storage techniques for space cooling purposes, namely ice slurry systems, ice-on-coil systems (both internal and external melt), and encapsulated ice systems is conducted. A detailed analysis, coupled with a case study based on the literature data, follows. The ice making techniques are compared on the basis of energy and exergy performance criteria including charging, discharging and storage efficiencies, which make up the ice storage and retrieval process. Losses due to heat leakage and irreversibilities from entropy generation are included. A vapor-compression refrigeration cycle with R134a as the working fluid provides the cooling load, while the analysis is performed in both a full storage and partial storage process, with comparisons between these two. In the case of full storage, the energy efficiencies associated with the charging and discharging processes are well over 98% in all cases, while the exergy efficiencies ranged from 46% to 76% for the charging cycle and 18% to 24% for the discharging cycle. For the partial storage systems, all energy and exergy efficiencies were slightly less than that for full storage, due to the increasing effect wall heat leakage has on the decreased storage volume and load. The results show that energy analyses alone do not provide much useful insight into system behavior, since the vast majority of losses in all processes are a result of entropy generation which results from system irreversibilities.     

Aerodynamic performance effects of leading-edge geometry in gas-turbine blades

The purpose of this paper is to illustrate the advantages of the direct surface-curvature distribution blade-design method, originally proposed by Korakianitis, for the leading-edge design of turbine blades, and by extension for other types of airfoil shapes. The leading edge shape is critical in the blade design process, and it is quite difficult to completely control with inverse, semi-inverse or other direct-design methods. The blade-design method is briefly reviewed, and then the effort is concentrated on smoothly blending the leading edge shape (circle or ellipse, etc.) with the main part of the blade surface, in a manner that avoids leading-edge flow-disturbance and flow-separation regions. Specifically in the leading edge region we return to the second-order (parabolic) construction line coupled with a revised smoothing equation between the leading-edge shape and the main part of the blade. The Hodson–Dominy blade has been used as an example to show the ability of this blade-design method to remove leading-edge separation bubbles in gas turbine blades and other airfoil shapes that have very sharp changes in curvature near the leading edge. An additional gas turbine blade example has been used to illustrate the ability of this method to design leading edge shapes that avoid leading-edge separation bubbles at off-design conditions. This gas turbine blade example has inlet flow angle 0°, outlet flow angle −64.3°, and tangential lift coefficient 1.045, in a region of parameters where the leading edge shape is critical for the overall blade performance. Computed results at incidences of −10°,   −5°,   +5°,   +10° are used to illustrate the complete removal of leading edge flow-disturbance regions, thus minimizing the possibility of leading-edge separation bubbles, while concurrently minimizing the stagnation pressure drop from inlet to outlet. These results using two difficult example cases of leading edge geometries illustrate the superiority and utility of this blade-design method when compared with other direct or inverse blade-design methods.     

Effect of co-cultivation of Chlamydomonas reinhardtii with Azotobacter chroococcum on hydrogen production

Chlamydomonas reinhardtii cc124 and Azotobacter chroococcum bacteria were co-cultured with a series of volume ratios and under a variety of light densities to determine the optimal culture conditions and to investigate the mechanism by which co-cultivation improves H₂ yield. The results demonstrated that the optimal culture conditions for the highest H₂ production of the combined system were a 1:40 vol ratio of bacterial cultures to algal cultures under 200 μE m^?2 s^?1. Under these conditions, the maximal H₂ yield was 255 μmol mg^?1 Chl, which was approximately 15.9-fold of the control. The reasons for the improvement in H₂ yield included decreased O₂ content, enhanced algal growth, and increased H₂ase activity and starch content of the combined system.     

Natural-gas fueled spark-ignition (SI) and compression-ignition (CI) engine performance and emissions

Natural gas is a fossil fuel that has been used and investigated extensively for use in spark-ignition (SI) and compression-ignition (CI) engines. Compared with conventional gasoline engines, SI engines using natural gas can run at higher compression ratios, thus producing higher thermal efficiencies but also increased nitrogen oxide (NO_x) emissions, while producing lower emissions of carbon dioxide (CO₂), unburned hydrocarbons (HC) and carbon monoxide (CO). These engines also produce relatively less power than gasoline-fueled engines because of the convergence of one or more of three factors: a reduction in volumetric efficiency due to natural-gas injection in the intake manifold; the lower stoichiometric fuel/air ratio of natural gas compared to gasoline; and the lower equivalence ratio at which these engines may be run in order to reduce NO_x emissions. High NO_x emissions, especially at high loads, reduce with exhaust gas recirculation (EGR). However, EGR rates above a maximum value result in misfire and erratic engine operation. Hydrogen gas addition increases this EGR threshold significantly. In addition, hydrogen increases the flame speed of the natural gas-hydrogen mixture. Power levels can be increased with supercharging or turbocharging and intercooling. Natural gas is used to power CI engines via the dual-fuel mode, where a high-cetane fuel is injected along with the natural gas in order to provide a source of ignition for the charge. Thermal efficiency levels compared with normal diesel-fueled CI-engine operation are generally maintained with dual-fuel operation, and smoke levels are reduced significantly. At the same time, lower NO_x and CO₂ emissions, as well as higher HC and CO emissions compared with normal CI-engine operation at low and intermediate loads are recorded. These trends are caused by the low charge temperature and increased ignition delay, resulting in low combustion temperatures. Another factor is insufficient penetration and distribution of the pilot fuel in the charge, resulting in a lack of ignition centers. EGR admission at low and intermediate loads increases combustion temperatures, lowering unburned HC and CO emissions. Larger pilot fuel quantities at these load levels and hydrogen gas addition can also help increase combustion efficiency. Power output is lower at certain conditions than diesel-fueled engines, for reasons similar to those affecting power output of SI engines. In both cases the power output can be maintained with direct injection. Overall, natural gas can be used in both engine types; however further refinement and optimization of engines and fuel-injection systems is needed.     

Hydrogen production by steam-gasification of carbonaceous materials using concentrated solar energy – V. Reactor modeling,optimization, and scale-up

A chemical reactor for the steam-gasification of carbonaceous particles (e.g. coal, coke) is considered for using concentrated solar radiation as the energy source of high-temperature process heat. A two-phase reactor model that couples radiative, convective, and conductive heat transfer to the chemical kinetics is applied to optimize the reactor geometrical configuration and operational parameters (feedstock's initial particle size, feeding rates, and solar power input) for maximum reaction extent and solar-to-chemical energy conversion efficiency of a 5 kW prototype reactor and its scale-up to 300 kW. For the 300 kW reactor, complete reaction extent is predicted for an initial feedstock particle size up to 35 μm at residence times of less than 10 s and peak temperatures of 1818 K, yielding high-quality syngas with a calorific content that has been solar-upgraded by 19% over that of the petcoke gasified.     

汽轮机数字电液调节系统挂闸异常的技术完善

分析了200MW汽轮机数字电液调节系统在运行中存在的挂闸异常问题,采取了相应的技术处理措施,且运行实践效果良好。     

新型高压共轨ECU升压模块的数字化开发与优化

为了提高喷油器电磁阀的响应速率,提出了一种基于CPLD(复杂可编程逻辑器件)应用于高压共轨ECU的数字升压模块。鉴于该升压电路结构参数多,其升压电压的恢复响应要求高等特征,基于Pspice建立了升压电路的仿真模型,研究了不同电路参数下升压模块的输出特性,全面优化了该升压模块的性能。结果显示,该升压模块的最大转换效率可以达90%以上。在柴油发动机上对ECU的试验表明,升压电压最大波动不超过10%,其恢复时间仅为1.3ms,功率管最大温升仅为41℃,满足整机运行范围内ECU的需求。     

Trace metal chemistry and silicification of microorganisms in geothermal sinter, Taupo Volcanic Zone, New Zealand

As part of a pilot study investigating the role of microorganisms in the immobilisation of As, Sb, B, Tl and Hg, the inorganic geochemistry of seven different active sinter deposits and their contact fluids were characterised. A comprehensive series of sequential extractions for a suite of trace elements was carried out on siliceous sinter and a mixed silica-carbonate sinter. The extractions showed whether metals were loosely exchangeable or bound to carbonate, oxide, organic or crystalline fractions. Hyperthermophilic microbial communities associated with sinters deposited from high temperature (92–94°C) fluids at a variety of geothermal sources were investigated using SEM. The rapidity and style of silicification of the hyperthermophiles can be correlated with the dissolved silica content of the fluid. Although high concentrations of Hg and Tl were found associated with the organic fraction of the sinters, there was no evidence to suggest that any of the heavy metals were associated preferentially with the hyperthermophiles at the high temperature (92–94°C) ends of the terrestrial thermal spring ecosystems studied.     

Exergetic evaluation of 5 biowastes-to-biofuels routes via gasification

This paper presents the exergy analysis results for the production of several biofuels, i.e., SNG (synthetic natural gas), methanol, Fischer–Tropsch fuels, hydrogen, as well as heat and electricity, from several biowastes generated in the Dutch province of Friesland, selected as one of the typical European regions. Biowastes have been classified in 5 virtual streams according to their ultimate and proximate analysis. All production chains have been modeled in Aspen Plus in order to analyze their technical performance. The common steps for all the production chains are: pre-treatment, gasification, gas cleaning, water–gas-shift reactions, catalytic reactors, final gas separation and upgrading. Optionally a gas turbine and steam turbines are used to produce heat and electricity from unconverted gas and heat removal, respectively. The results show that, in terms of mass conversion, methanol production seems to be the most efficient process for all the biowastes. SNG synthesis is preferred when exergetic efficiency is the objective parameter, but hydrogen process is more efficient when the performance is analyzed by means of the 1st Law of Thermodynamics. The main exergy losses account for the gasification section, except in the electricity and heat production chain, where the combined cycle is less efficient.     

Decomposition of limestone in a solar reactor

The thermal decomposition of limestone has been selected as a model reaction for developing and testing an atmospheric open solar reactor. The reactor consists of a cyclone gas/particle separator which has been modified to let the concentrated solar energy enter through a windowless aperture. The reacting particles are directly exposed to the solar irradiation. Experimentation with a 60 kW reactor prototype was conducted at PSI's 90m² parabolic solar concentrator, in a continuous mode of operation. A counter-current flow heat exchanger was employed to preheat the reactants. Eighty five percent degree of calcination was obtained for cement raw material and 15% of the solar input was converted into chemical energy (enthalpy).The technical feasibility of the solar thermal decomposition of limestone was experimentally demonstrated. The use of solar energy as a source for high-temperature process heat offers the potential of reducing significantly the CO₂ emissions from lime producing plants. Such a solar thermochemical process can find application in sunny rural areas for avoiding deforestation.