分散药起爆方式控制FAE燃料分散的数值模拟

为初步预示燃料的后期分散效应,运用ANSYS／DYNA3D程序,选择了四种起爆方式数值模拟分散药对FAE炸弹壳体起始阶段的破裂及运动过程。结果表明,分散药起爆方式即爆轰波传播方向对燃料分散有显著的影响,分散药起爆方式在FAE的研究中应受到特别重视。     

低热值燃料发电企业发展热电联产的探讨

为提高低热值燃料发电的热效率 ,应根据煤矿用户热能需求情况将低热值燃料发电厂改为热电联产电厂 ;具体论述了这种改造的必要性与可能性以及几种改造方式。     

Fe改性HZSM-5分子筛上甲醇耦合C4烃制低碳烯烃反应性能研究

用等体积浸渍法制备Fe改性HZSM-5分子筛催化剂（Fe/HZSM-5）。考察了Fe/HZSM-5在不同温度下对甲醇耦合C₄烃制低碳烯烃反应性能的影响,并利用紫外-可见漫反射光谱对Fe/HZSM-5进行了表征。结果表明,在低铁含量条件下,Fe改性HZSM-5分子筛上Fe（Ⅲ）主要以高分散隔离的形式存在于HZSM-5分子筛的表面,Fe改性提高了催化剂上的原料转化率以及乙烯和丙烯选择性,从而获得了较高的乙烯和丙烯总收率。在反应温度为550 ℃时,在Fe（Ⅲ）处理的HZSM-5分子筛上,乙烯和丙烯总收率最高可达42.1%,比未改性的HZSM-5提高了7％。     

Performance of a sonic burner system firing coal-oil mixtures

The development of coal—oil mixture technology is progressing at an accelerated rate and the aim of this work has been the development of a new burner system (termed the sonic burner) to increase lignite loadings in air-atomizing burner systems. The burner system developed incorporates a sonic velocity at the atomizing air throat and a fuel oil gun with a single, relatively large opening at its exit. Lignite loadings with No. 6 fuel oil have reached 60.0 wt%. The flame produced at these loadings was stable, compact and characteristic of a No. 6 fuel oil flame. Fuel line plugging did not occur at these high lignite loadings; however, pumping problems did preclude increased lignite loadings. Results of this study are directly applicable to higher rank coals. Although feasible from a combustion viewpoint, no inference should be made from these results concerning erosion, ash deposition, particulate control or pollution characteristics, the work reported being based solely on combustion characteristics.     

Aerodynamic behavior of a gas mask canister containing two porous media

This paper discusses the aerodynamic behaviors of a gas mask canister with a complex inner structure and two porous materials in the filter layer and the activated carbon layer. The effects of the distribution and area of holes in the main sieve diaphragm and the thickness of the activated carbon layer on the pressure drop and the flow structure were determined using computational fluid dynamic (CFD) tools. The momentum loss of porous flow calculated by Forchheimer's equation was added to the source term in the momentum equation. Streakline flow visualization was employed to observe gas flow structures within the empty canister and to identify the shortcomings of the prototype canister. Simulation results for the estimated inertial and viscosity parameters in Forchheimer's equation agree closely with experimental values. The porosity of the canister for intake flows of 15-135 L/min causes the flow behavior to transition gradually from linear (viscous effect) to slight non-linear behavior (slight inertia effect). This study uses air age as an index of the time that air resides within the canister to displace the adsorption time of toxic gas. This approach conveniently elucidates overall filter capacity and the positions of dead zones in the activated carbon layer. The simulation results reveal that the channel design of the main sieve diaphragm dominates the aerodynamic behavior of the fluid within the activated carbon layer. Better hole distribution and a larger hole area correspond to a lower pressure drop, a smaller dead zone, and a higher adsorption time. The results in this study provide a valuable reference for designing channels in the main sieve diaphragm, and will be helpful in designing gas mask canisters.     

A Comparative Study of the Explosion Characteristics of IPN and IPN/JP‐10 Mixtures in Air Aerosols

This article presents a comparison of the explosion characteristics of mixtures of isopropyl nitrate (IPN, (CH₃)₂CHONO₂) and JP‐10 (C₁₀H₁₆, tricycle [5.2.1.0^2,6] decane) in air aerosols. The explosion pressure, flame temperature, maximum rate of pressure rise, maximum rate of temperature rise, and lower flammability limits (LFLs) were measured for two sets of IPN and mixed IPN/JP‐10 in air aerosols at different concentrations and Sauter mean diameters (SMDs) of 19 μm and 34 μm, respectively, and the values were compared with the experimental results of JP‐10/air aerosols with SMDs of 20 μm and 35 μm (from our previous research). Experiments were also performed to study various concentrations at various ignition energies for the IPN/air aerosols and the explosions of binary mixture aerosols with various mass ratios of IPN and JP‐10. The experimental results indicated that for the IPN/air and JP‐10/air aerosols with a mean SMD of ∼34 μm, the maximum peak pressure and maximum peak temperature of the IPN/air aerosols were greater than those of the JP‐10/air aerosols. The maximum rate of pressure rise of the IPN/air aerosols reached a maximum value of 395.3 MPa/s at a mean SMD of ∼34 μm, and the pressure increased more abruptly in the IPN/air aerosols than in the JP‐10/air aerosols. The LFLs of the IPN/air aerosols occurred with a total concentration of 197 g/m³ at a mean SMD of 19 μm and a total concentration of 233 g/m³ at a mean SMD of 34 μm, whereas the LFLs for the JP‐10/air aerosols with SMDs of 20 μm and 35 μm were less than 47 g/m³ and 40 g/m³, respectively. The experimental results presented here also showed that the maximum peak pressure was 1.07 MPa at a binary liquid mass ratio of IPN:JP‐10 (%) of 72 : 28 and a mean SMD of ∼34 μm.     

Fuel cells—II. Propane and propylene on Adams' platinum catalyst

In order to control the quantity of previously adsorbed hydrogen in fuel electrodes to be used with hydrocarbons, the use of Adams' platinum catalyst was investigated. Preferred procedures for electrode preparation were developed. Adams' platinum oxide powder was intimately mixed with a silver powder and pressed to form a disk, which, fixed within a cell, was reduced with hydrogen in glacial HOAc and then treated with a water-proofing wax solution. Reduction could be stopped at a definite stage and the reduced electrode could be protected from air throughout all manipulative and measuring procedures. The potential behaviour of 15 electrodes reduced to differing degrees was studied in helium, propane, propylene and hydrogen at 80°C.

During flushing with propylene, the open-circuit potential increased quite rapidly after an induction period, which was related to the original degree of electrode reduction. The steady potential reached increased with the degree of reduction. The potential of an electrode initially saturated with hydrogen gradually decreased with propylene flushing, approaching a steady value.

The good discharge behaviour observed for propylene far exceeded that due to hydrogen adsorbed during electrode preparation. Propylene flushing for more than 20 h was necessary to reach a steady potential. On interruption of the discharges, the potential returned to almost the initial potential. The steady potential may represent an equilibrium potential between propylene, electrode and electrolyte, and may be called a “propylene potential”.     

双氧水—丙烯—甲醇体系的相态研究

钛硅分子筛催化丙烯环氧化是生产环氧丙烷的清洁工艺,其多相反应体系的相态研究是优化该反应体系的基础.采用可视相平衡仪对不同氧化剂体系（50％双氧水体系和30％双氧水体系）、不同温度（30～80℃）、不同压力（0.8～3.5 MPa）、不同物料配比[甲醇∶双氧水（摩尔比）为5～20,丙烯∶双氧水（摩尔比）为1～4]的进料体系进行了相态观测.结果表明,丙烯进料量和甲醇含量是影响体系相态的关键因素.在相同物料配比和相近的丙烯进料量下,50％双氧水体系比30％双氧水体系液相更易达到均相.此外,对于两种双氧水-丙烯-甲醇体系,甲醇含量一定时,丙烯的进料量越小,体系液相越易呈均相状态.总之,为了使丙烯和双氧水能在液相中充分接触,应使丙烯进料量接近体系温度、压力下丙烯在双氧水-甲醇溶液中的饱和溶解度.     

Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts

BACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon‐neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H‐ZSM‐5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds. RESULTS: Successive addition of Fe and P to the H‐ZSM‐5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co‐addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on‐stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air. CONCLUSION: Fe‐ and/or P‐modified H‐ZSM‐5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air. Copyright © 2010 Society of Chemical Industry     

溶胶-凝胶法制备丙烷脱氢Pt-Sn/Al2O3催化剂性能

采用溶胶-凝胶法和浸渍法制备了不同Sn组分含量的Pt-Sn/Al₂O₃催化剂, 通过XPS、TEM和H₂吸附等物化表征手段对催化剂进行了表征,考察了无H2存在下的催化剂丙烷脱氢性能。结果表明,采用溶胶-凝胶法导致一部分Sn组分被包埋,减少高温还原条件下Sn组分的析出而提高催化脱氢活性。在550 ℃反应 6.5 h的条件下,丙烯收率36.3%,丙烯选择性达98.8%。     

Effect of antioxidants on the oxidative stability of methyl soyate (biodiesel)

Biodiesel, an alternative diesel fuel derived from transesterification of vegetable oils or animal fats, is composed of saturated and unsaturated long-chain fatty acid alkyl esters. When exposed to air during storage, autoxidation of biodiesel can cause degradation of fuel quality by adversely affecting properties such as kinematic viscosity, acid value and peroxide value. One approach for increasing resistance of fatty derivatives against autoxidation is to treat them with oxidation inhibitors (antioxidants). This study examines the effectiveness of five such antioxidants, tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PrG) and α-Tocopherol in mixtures with soybean oil fatty acid methyl esters (SME). Antioxidant activity in terms of increasing oxidation onset temperature (OT) was determined by non-isothermal pressurized-differential scanning calorimetry (P-DSC). Analyses were conducted in static (zero gas flow) and dynamic (positive gas flow) mode under 2000 kPa (290 psig) pressure and 5 °C/min heating scan rate. Results showed that PrG, BHT and BHA were most effective and α-Tocopherol least effective in increasing OT. Increasing antioxidant loading (concentration) showed sharp increases in activity for loadings up to 1000 ppm followed by smaller increases in activity at higher loadings. Phase equilibrium studies were also conducted to test physical compatibility of antioxidants in SME-No. 2 diesel fuel (D2) blends. Overall, this study recommends BHA or TBHQ (loadings up to 3000 ppm) for safeguarding biodiesel from effects of autoxidation during storage. BHT is also suitable at relatively low loadings (210 ppm after blending). PrG showed some compatibility problems and may not be readily soluble in blends with larger SME ratios. Although α-Tocopherol showed very good compatibility in blends, it was significantly less effective than the synthetic antioxidants screened in this work.     

Impact of altitude on fuel consumption of a gasoline passenger car

Engines of new passenger cars are tuned at the sea level. However, in several countries, a significant part of the engine operation is performed at higher altitudes than that of the sea level. The different air density can have a significant impact on fuel consumption. In the case of gasoline engines, the higher altitude theoretically leads to lower fuel consumption due to lower throttle frictions due to the wider throttle opening. From the other side, as the air is less dense at higher altitudes, the vehicle aerodynamic is changed and this also leads to lower fuel consumption. This work studies, on three regulated driving cycles, the impact of high altitude on the fuel consumption of a gasoline passenger car. The impact of changed vehicle aerodynamics of higher altitudes, through the change of deceleration times, on fuel consumption is also analyzed.     

Analyse der potentiellen Explosionswirkung von kurzzeitig in die Atmosphäre freigesetzten Brenngasmengen. Teil I: Gesetze der Wolkenausbreitung und -deflagration aus Berstversuchen an Modellbehältern

Explosion hazard analysis of inflammable gas released spontaneously into the atmosphere . The processes of flash evaporation, atmospheric vapour cloud formation ignition and explosion after the bursting of vessels containing liquefied gas have been studied by model experiments with propylene heated up to 70°C and pressurized to 60 bar. The experiments have shown that a blast wave with considerable peak pressure in the vicinity of the vessel is produced already by flash expansion of the propylene. The experimentally determined decrease of peak pressure with growing distance could be scaled up to vessels of arbitrary size and different propylene temperatures. Scaling laws could be established as well for the calculation of peak pressure and positive pressure duration of the deflagration wave as functions of released mass and distance. The experiments have not revealed any evidence of a detonation process even when the cloud was ignited by an explosive charge.     

Emission of nitrogen oxides in a vortexing fluidized bed combustor

This study investigated experimentally the effects of fuel types and operating conditions on NO emission in a 0.45 m I.D. pilot scale vortexing fluidized bed combustor. Rice husk, soybean, high and low sulfur subbituminous coals, and bituminous coal were used as fuels. Silica sand was employed as the bed material. The effects of various operating conditions, such as bed temperature, excess air ratio, and stoichiometric air flow rate on NO emission were investigated. The dependence of the conversion of fuel-N on O/N and H/N weight ratios of the fuel was explored to understand the effect of fuel composition on NO emissions. The results show that the H/N ratio is a better indicator than the O/N ratio to represent the conversion of fuel-N to NO. Soybean was mixed with other fuels to study its characteristics for reducing NO emission. Taguchi method was applied to analyze the priority of operating conditions for dominating NO emission. It is found that the excess air is the most important factor to dominate NO emission.     

An empirical model for estimating evaporative hydrocarbon emissions from canister-equipped vehicles

An empirical model for the estimation of evaporative hydrocarbon emissions from canister-equipped vehicles has been developed from experimental data obtained from repeated tests on a single carbon canister. The model is able to predict canister adsorption and desorption behaviour under different loading and purging conditions and it calculates canister weight and breakthrough emissions for various experimental variables including temperature, mixture concentration and mass flow rate. The model enables the simulation of a full evaporative emission Sealed Housing for Evaporative Determination (SHED) test procedure taking into account vehicle-specific estimations of fuel vapour generation and permeation. Results from measurements conducted on a vehicle equipped with the same canister were used to calibrate the model. Model results were in good agreement with measured evaporative emissions from a number of vehicles.     

Relevant parameters involved in tribocharging of powders during dilute phase pneumatic transport

This work presents the results of an experimental study carried out on the tribo-charging of fine glass particles during their pneumatic conveying. The effect of several parameters such as the chemical nature of the transport pipe, the particles mean size, the solids flow rate, the air velocity and the relative humidity (RH) was examined. Experiments were carried out using several batches of monodisperse glass particles with mean particle sizes ranging from 75 μm to 500 μm. Both spherical and angular particles were used. Powders were conveyed through two types of pipe materials (Teflon and Nylon) at dilute loadings and varying relative humidities of air (0-90%). The total charge of conveyed powder was measured using a terminal Faraday cage. Furthermore, a series of four Faraday cages was used to measure the charge transfer between the wall and particles along the flow path. Greater electrostatic effects were observed for larger particles, higher air velocities, higher solids flowrate and lower RH.A simple model of charge transfer was also established in order to describe the time evolution of charges on the particles and the wall. Results showed that the tribocharging rate can be conveniently represented by an exponential-deceleration model.     

Novel micaceous reinforcing fillers with fire and smoke retarding qualities

This paper describes Miconite (hydrated potassium, magnesium aluminosilicate) and explains the processability and properties of Miconite-filled propylene homopolymer. With particles averaging 2.5 and 44 microns, this study found the compound processability, as given by its melt index, unchanged for filler loadings lower than 35%. Tensile strength of the original polymer doubled with the addition of the first 10% of Miconite and stayed constant for all loadings tested up to 60%. Tensile modulus increased linearly with filler loading. Elongation and impact behavior showed negligible decreases for loadings lower than 30%. Deterioration by ultraviolet and/or heat-aging was negative. Miconite provides matrix materials with fire and smoke retarding qualities.     

Modeling and Parametric Study of a Single Solid Oxide Fuel Cell by Finite Element Method

A 2D isothermal axisymmetric model of an anode‐supported solid oxide fuel cell has been developed. The model, which is based on finite element approach, comprises electronic and ionic charge balance, Butler–Volmer charge transfer kinetic, flow distribution and gas phase mass balance in both channels and porous electrodes. The model has been validated using available experimental data coming from a single anode‐supported cell comprising Ni–YSZ/YSZ/LSM–YSZ as anode, electrolyte and cathode, respectively. Hydrogen and steam were used as fuel inlet and air as an oxidant. The validation has been carried out at 1 atm, 1,500 ml min^–1 air flow rate and three different operating conditions of temperature and fuel flow rate: 1,073 K and 400 ml min^–1, 1,073 K and 500 ml min^–1, and 1,003 K and 400 ml min^–1. The polarization and power density versus current density curves show a good agreement with the experimental data. A parametric analysis has been carried out to highlight which parameters have main effect on the overall cell performance as measured by polarization curve, especially focusing on the influence of two geometrical characteristics, temperature and some effective material properties.     

SANC-08丙烯腈合成催化剂的开发

实验室开发出新型SANC-08丙烯腈合成催化剂,在反应温度440 ℃、反应压力0.084 MPa、催化剂负荷0.06 h^-1、n(空气)∶n(丙烯)=9.5和n(氨气)∶n(丙烯)=1.25反应条件下,丙烯转化率97%以上,丙烯腈选择性82%以上,丙烯腈收率大于80%,氨转化率94%以上。流化床反应器稳定性试验结果表明, 2 177 h时,丙烯腈收率78.9%,丙烯转化率94.6%,丙烯腈选择性83.3%。     

生物质下吸式气化炉气化制备富氢燃气实验研究

以制取富氢燃气为目标,在自热式下吸式气化炉反应器内,进行了生物质下吸式气化炉富氧/水蒸气及空气气化的制氢特性研究。实验结果表明,与空气气化相比,富氧/水蒸气气化可显著提高氢产率和产气热值。在实验条件范围内,最大氢产率达到45.16 g/kg;最大低位热值达到11.11 MJ/m3。在富氧/水蒸气气化条件下,燃气中H2+CO体积分数达到63.27%—72.56%,高于空气气化条件下的52.19%—63.31%。富氧/水蒸气气化条件下的H2/CO体积比比值为0.70—0.90,低于空气气化条件下的1.06—1.27。实验结果证实:生物质下吸式气化炉富氧/水蒸气气化是一种有效的制取可再生氢源的工艺路线。