The activity of commercial water gas shift catalysts

Published kinetic data for commercial water gas shift catalysts are interpreted in terms of pore diffusional effects. The Arrhenius plots of apparent activity show the curvature typical of the transition from reaction to pore diffusion control and the apparent activities of different catalyst pellets vary quite widely. Effective diffusivity data are used to calculate intrinsic rate constants from the apparent activity data and it is found that the intrinsic activities of the catalysts considered are all similar. Furthermore the intrinsic activities, calculated in this way, give linear Arrhenius plots and activation energies which are in good agreement with values obtained experimentally using small catalyst particles (22–27 K. Cals). The effect of pressure on apparent catalyst activity is also discussed and it is shown that this effect may be accounted for satisfactorily by pore diffusional effects and it is not necessary to assume a change in the intrinsic rate equation at least at pressures below 20 atms.     

异常高压气藏动态预测研究

在异常高压气藏开发过程中,由于应力敏感性造成的渗透率变化无法忽略,因此在建立二项式渗流方程时必须考虑由于应力敏感性造成的渗透率的变化情况,定义新的拟压力形式的渗流方程。再以物质平衡原理为基础,导出定容异常高压气藏的压降方程,并与井筒流动方程相结合,建立动态预测模型。由于该模型很好的考虑到了应力敏感性造成的影响,使得更适用于实际生产过程中,对于异常高压气藏生产动态的预测有较好的效果。     

浮头式废热锅炉转化气流动特性的试验研究

通过大比例尺模型试验，测定了浮头式废热锅炉的环室、分配套筒和辐射状横掠管束的转化气沿轴向和环向流动的不均匀性。分析了造成流动不均匀性的原因及对传热的影响，给出了改进分配套筒多孔结构的方法，为大型合成氨厂的浮头式废热锅炉的设计和改造提供了试验依据。     

Effects of tar model compounds on commercial water gas shift catalysts

One attractive application of the catalytic water gas shift (WGS) reaction is the production of a syn-gas with high hydrogen concentration from gasification of solid combustibles. The catalyst's behavior can be affected by the hydrocarbons with high molecular weight (tar) still present in the gas after its purification. In this work the effect of some tar model compounds on two typical commercial WGS catalysts were investigated. A low temperature catalyst composed of Cu/Zn/Al and a high temperature catalyst based mainly on Fe and Cr were tested. N-hexadecane, fluorene, phenol, and octanol were used as tar model compounds. Besides these compounds, the effect of biodiesel was also investigated. In all cases a concentration of 0.5 g/Nm³ was used. Generally it was observed that a low concentration is often sufficient to produce a rapid deactivation. Catalysts were characterized by means of BET and XRD.     

Experimental and numerical investigation of supported rhodium catalysts for partial oxidation of methane in exhaust gas diluted reaction mixtures

The partial oxidation of methane/oxygen mixtures with large exhaust gas dilution (46.3 vol% H₂O and 23.1 vol% CO₂) has been investigated experimentally and numerically over Rh/CeO₂-ZrO₂, Rh/ZrO₂ and Rh/α-Al₂O₃ catalysts. Experiments were carried out in a short-contact-time reactor at 5 bar and included exhaust gas analysis, temperature measurements along the reactor, and catalyst characterization. Additional experiments were performed in an optically accessible channel-flow reactor and involved in situ Raman measurements of major gas-phase species concentrations over the catalyst boundary layer and laser-induced fluorescence (LIF) of formaldehyde. A full elliptic two-dimensional numerical code that included elementary hetero-/homogeneous chemical reaction schemes and relevant heat transfer mechanisms in the solid was used in the simulations. The employed heterogeneous reaction mechanism, including only active Rh sites, reproduced the experiments with good accuracy. The ratio of active to geometrical surface area, deduced from hydrogen chemisorption measurements, was the single model parameter needed to account for the effect of different supports. This indicated that water activation occurring on support sites, resulting in inverse OH spillover from the support to the noble metal sites, could be neglected under the present conditions with high water dilution. An evident relationship between noble metal dispersion and catalytic behavior, in terms of methane conversion and synthesis gas yields, could be established. Both measurements and predictions indicated that an increasing Rh dispersion (in the order Rh/α-Al₂O₃, Rh/ZrO₂, and Rh/CeO₂-ZrO₂) resulted in higher methane conversions, lower surface temperatures, and higher synthesis gas yields.     

Experimental investigation of gas combustion regularities in narrow tubes

Combustion wave propagation in flowing combustible gas has been studied experimentally in tubes with inner diameters larger and smaller than the critical diameters. Combustion wave velocity has been shown to depend on the material of the tube walls, the tube inner diameter, the mixture composition, and the gas flow rate. In a tube which has an inner diameter larger than the critical diameter, two flame-propagation regimes exist.Translated from Fizika Goreniya i Vzryva, Vol. 32, No. 1, pp. 42–47, January–February, 1996.     

商用蜂窝式SCR催化剂脱除NO_x试验研究

为了评价燃煤电厂广泛采用的选择性催化还原工艺对不同形态NO_x的脱除效果,以某商用蜂窝式SCR催化剂为例,在SCR脱硝试验装置上研究了氧量、温度、空速、氨氮摩尔比等反应条件对NO、N_2O和NO_2脱除过程的影响。结果表明,氧量可以促进NO氧化以及NO与氨的催化还原反应;高温可以促进NO的脱除和氨气氧化为N_2O;空速升高会导致NO脱除率先升高后降低;氨氮摩尔比提高在促进NO脱除的同时会增加氨逃逸;与NO_2可以完全脱除相反,N_2O与氨气不发生反应。因此,为真正实现NO_x的超净排放,应适当控制锅炉运行参数避免N_2O的生成。     

Progress towards the commercial application of gold catalysts

Now that gold catalysis is a valuable and exciting new field of catalysis as a whole, the exploitation of gold catalysts for commercial applications is being pursued. This is being assisted by new work on preparation and utilization methods to increase their durability during use. Other factors, including a substantial increase in investment in gold catalysis R&D, need to be considered before widespread application will occur. We show that new opportunities for commercial exploitation can be monitored via patent mapping, followed by careful examination of key patents.     

双切环流气体分布器性能的实验研究

湿空气透平(HAT)循环被誉为21世纪最有竞争力的先进动力循环,HAT循环的核心部件饱和器采用了填料塔的结构形式,为了提高整塔的性能,改进并设计了双切环流气体分布器.目前,双切环流气体分布器设计依然主要依靠经验进行设计,而实验的方法依然是分布器性能最可靠的研究方法.文中利用直径φ800 mm的饱和器实验台,对改进后的双...     

Two-phase flow through pressure safety valves. Experimental investigation and model prediction

Due to the lack of experimental data regarding two-phase flow through safety relief valves, a number of different calculation methods are presently available in the literature for their sizing. All these models mainly refer to the flow through an ideal nozzle, so that, in order to match the measured values, a discharge coefficient is to be introduced in the calculation, the coefficient thus depending on the model adopted. Furthermore, most of the available data are referred to a few operating conditions. As a result, none of the available models is presently considered sufficiently accurate to be used in a wide range of operating conditions.In the present paper, new data are produced on a steam/water flashing system through a real valve with different values of the main operating parameters (vapour quality, inlet pressure, mass flow rate, and backpressure). The measurements are compared with the predictions of a commonly used homogeneous equilibrium model (HEM), the so-called ω method, and show that the model markedly underestimates the mass flow rate in the whole range of conditions investigated. This unexpectedly implies the introduction of a two-phase discharge coefficient much higher than the vapour coefficient.Finally, a new correlation for the discharge coefficient as a function of the main operating parameters is proposed.     

氧化锌法处理低浓度SO2烟气的试验研究和生产实践

论述用氧化锌法处理低浓度SO2气体的基本原理、试验研究和生产实践。采用pH值约5的氧化锌浆液吸收气体中的SO2,然后用硫酸分解或蒸汽加热分解产生的亚硫酸锌,获得高浓度SO2和氧化锌或硫酸锌,SO2和氧化锌重新使用,硫酸锌作为副产品。试验及生产实践均证明,氧化锌法吸收效率高、流程简单,由于原料容易获得,特别适合于铅锌冶炼厂低浓度SO2烟气或硫酸装置尾气的处理。     

Experimental investigation on injection characteristics of bioethanol-diesel fuel and bioethanol-biodiesel blends

This paper analyses the fuel injection characteristics of bioethanol-diesel fuel and bioethanol-biodiesel blends considered as fuel for diesel engines. Attention is focused on the injection characteristics which significantly influence the engine characteristics and subsequently the exhaust emissions. In this context the following injection characteristics have been investigated experimentally: fuelling, injection timing, injection delay, injection duration, mean injection rate, and injection pressure. The tested fuels were neat mineral diesel fuel, neat biodiesel made from rapeseed oil, bioethanol/diesel fuel and bioethanol/biodiesel blends up to 15% (v/v) bioethanol with an increment of 5%. The fuels blends were experimentally investigated in a fuel injection M system at rated condition (FL, 1100 rpm), peak torque (FL, 850 rpm), and maximum pump speed (1100 rpm) for different partial loads (PL 75% and PL 50%), at ambient temperature.It has been proven that for all operating regimens tested, the addition of bioethanol to biodiesel reduces fuelling, injection timing, injection duration, mean injection rate and maximum injection pressure and increases injection delay compared to pure biodiesel. Meanwhile, increasing bioethanol in diesel fuel shows no significant variations or a slightly increase in fuelling, injection timing, injection duration, and mean injection rate and a decrease in injection delay and maximum injection pressure, compared to pure diesel fuel.The influence of bioethanol in biodiesel is much more significant that in diesel fuel; it has a beneficial effect on biodiesel injection characteristics because bioethanol addition brings them nearer to the diesel fuel one and it is expected to decrease biodiesel NO_x emissions.     

弓形折流板换热器动态特性试验研究

建立了可进行壳管式换热器动态特性试验研究系统,通过试验研究的方法对以水-油为换热工质的弓形折流板换热器动态特性进行了试验研究,进口流量扰动为等百分比流量特性.研究了四种流量扰动方式下水和油出口温度的动态响应.同时研究了在一定Re数下,异侧不同的流体扰动量对换热器进出口温升的影响.实验表明液液换热系统温度的动态响应时间比较长,在正负的流量扰动下,弓形折流板换热器进出口温度变化呈现线性变化,进出口温升在正负流量扰动下其变化趋势具有对称特征.     

液化石油气燃爆泄放特性的实验研究

利用５２４Ｌ球形容器对液化石油气燃爆泄放特性进行了研究，其试验结果可为从事安全工程设计的技术人员提供参考。     

Experimental investigation of particle contact time at the wall of gas fluidized beds

The contact time of particles at the walls of gas fluidized beds has been studied using a radioactive particle tracking technique to monitor the position of a radioactive tracer. The solids used were sand or FCC particles fluidized by air at room temperature and atmospheric pressure at various superficial velocities, covering both bubbling and turbulent regimes of fluidization. Based on the analysis of tracer positions, the motion of individual particles near the walls of the fluidized bed was studied. The contact time, contact distance and contact frequency of the particles at the wall were evaluated from these experimental data. It was found that in a bed of sand particles, the mean wall contact time of the fluidized bed of sand particles decreases by increasing the gas velocity in the bubbling and increases in the turbulent fluidization. In other words, the particle-wall contact time is minimum at the onset of turbulent fluidization in the bed of sand particles. However, the mean wall contact time is almost constant in both regimes of fluidization in the bed of FCC particles. All the existing models in the literature predict a decreasing contact time when the gas velocity in the bed is increased. It was also shown that the contact distance increases monotonously by increasing the gas velocity in the bed of sand particles, while it is almost constant for the bed of FCC particles. Contact frequency has a trend similar to that of the contact time for both sand and FCC particles.     

含氰化氢的混合气磷铵吸氨的实验研究

在玻璃填料塔中,用磷铵吸氨法回收氰化氢和氨气的混合气中的氨,研究了温度、吸收剂的浓度、液气比、进口浓度等条件对氨回收率的影响。结果表明,较好的工艺条件为:吸收温度45℃,吸收液浓度2.1 mol/L,液气比11 L/m~3。     

含氰化氢的混合气磷铵吸氨的实验研究

在玻璃填料塔中,用磷铵吸氨法回收氰化氢和氨气的混合气中的氨,研究了温度、吸收剂的浓度、液气比、进口浓度等条件对氨回收率的影响。结果表明,较好的工艺条件为:吸收温度45℃,吸收液浓度2.1 mol/L,液气比11 L/m³。     

Experimental investigation of pressure-drop characteristics across multi-layer porous metal structures

This study investigates the effect of airflow (in the range of 0–70 m s^?1) on the pressure-drop characteristics for a novel multi-layered, nickel-based porous metal, as a function of thickness (affected by sectioning) and density (affected by compression). In addition to generating unique data for these materials, the study highlights the need for precise pinpointing of the different flow regimes (Darcy, Forchheimer and Turbulent) in order to enable accurate determination of the permeability (K) and form drag coefficient (C) defined by the Forchheimer equation and to understand the complex dependence of length-normalised pressure drop on sample thickness.