Quantitative Analysis of Frosting Characteristics on the Drip Tray of A Cryogenic Valve for LNG Ships

Cryogenic valves play a crucial role in the production and transportation of liquefied natural gas(LNG),and are primarily responsible for efficiently controlling the inflow and outflow of LNG and regulating pressure.However,due to their operation in low-temperature and high-humidity environments,crucial components such as drip trays are susceptible to frosting,which may lead to LNG leakage,thereby causing severe safety incidents.In this study,the user-defined function(UDF)is employed to redevelop Fluent,which integrates the frost growth model with the Eulerian multiphase flow model,to conduct a quantitative analysis of frosting on drip trays of cryogenic valves.The effects of environmental parameters,such as wind speed,ambient temperature,air humidity,and cold surface temperature on the growth of the frost layer were analyzed.This study reveals a limiting wind speed between 1 m/s and 2 m/s.Upon reaching this limit speed,the growth of the frost layer reaches its maximum,and further increases in the wind speed have no significant effect on the growth of the frost layer.Furthermore,the influence of the change in the flow field on droplet impingement and freezing during the growth of the frost layer is considered through the coupling method of the kinematic characteristics of water droplets and the collection coefficient of water droplets.This study identifies the influence of different parameters on the droplet impact efficiency,leading to the modification of the frost layer on the drip tray.

一种Tray装产品镭雕Logo的设备设计

本文阐述一种Tray装产品镭雕Logo的设备结构设计,Logo镭雕是一种加工方式,将汽车企业的标志、名称、图案、产品信息等,通过激光镭射技术刻在产品的外形上,达到立体浮雕的效果。镭雕技术在汽车行业内应用广泛,如:安全带、车钥匙、汽车灯具、汽车音箱、摄像头、行车记录仪、蓄电池等。本设计的核心结构包括:前/后Tray盘上下料结构、整Tray产品翻转结构、Tray盘定位/移动结构、镭雕机结构、CCD检测结构等。该设备可实现Tray装产品自动上下料、自动翻转以实现产品正反面镭雕、CCD对单个产品自动补偿定位、CCD目检的功能,生产效率高,质量好,更换产品方便,适应性强。

DOWNCOMER MIXING AND ITS EFFECT ON DISTILLATION TRAY EFFICIENCY

In this paper, the measurement of liquid mixing in a downcomer of segmental type of distillation column is presented. The extent of liquid mixing is calculated by means of a mixing pool model. The results indicate that liquid mixing in a downcomer is actually incomplete. It is a significant correction to the assumption of complete downcomer mixing or no downcomer mixing which is generally adopted in many distillation calculations. Besides, the present results are used in a two dimensional eddy diffusion model to calculate the distillation tray efficiency. It is shown that the assumption of complete downcomer mixing is closer to the actual situation than that of no downcomer mixing.

Research on Potted-Tray Grown Rice Seedling Transplanting by Machine

[Objective] In order to cultivate seedlings that are adaptable to farming system and transplanter, the technology for transplanting potted-tray grown rice seedlings with machine was introduced and studied. [Method] The transplanter-spe-cific seedlings were cultivated with potted-tray, bowl-shaped blanket tray and soft plastic flat plate respectively. The seeding rate and 20-50-day-old seedling height were investigated for the 3 sowing patterns. After the transplanting, the missing transplanting rate, upright seedling rate, seedling injury rate and green-returning pe-riod were investigated. [Result] Nursing seedlings with potted-tray had the advan-tages of saving seeds, high sowing precision, high seedling rate and high seedling rate. The 20-40-day-old seedlings had relatively high leaf age, seedling height and root number. However, 40 d after the transplanting, the growth of seedlings was slowed. The quality difference was smal est among the 20-day-old seedlings that were nursed with 3 different patterns, but since then the quality advantage of pot-ted-tray grown seedlings had been more and more prominent. There was smal dif-ference in quality among the 30-day-old seedlings. However, for the seedlings that were older than 40 d, the transplanting quality of potted-tray grown seedlings was higher than that of bowl-shaped blanket tray grown seedlings and soft plastic flat plate grown seedlings. In addition, the green-returning period of the potted-tray grown seedlings was significantly shortened. [Conclusion] Compared to the bowl-shaped blanket tray grown seedlings and soft plastic flat plate grown seedlings, the potted-tray grown seedlings were more suitable to transplant by machine in the wheat-rice double cropping areas of Chengdu Plain.

A Novel SiC Foam Valve Tray for Distillation Columns

The novel SiC foam valve tray was made of thin slices of SiC foam material with a high specific surfacearea. Hydrodynamic performances of the novel SiC foam valve tray were studied with air-water system at atmos-pheric pressure. These performance parameters included pressure drop, entrainment, weeping and clear liquidheight. The mass transfer efficiency of the SiC foam valve tray was measured in laboratory plate column. Comparedwith the F1 float valve tray, the dry pressure drop was decreased about 25%, the entrainment rate was about 70%lower at high gas load, the weeping was much better, and the mass transfer efficiency was far higher. Thus, theoverall performance of the novel SiC foam valve tray was better than that of F1 float valve tray.

SIMULATION OF TWO DIMENSIONAL LIQUID PHASE FLOW ON A DISTILLATION TRAY

A mathematical model describing the two dimensional liquid phase flow on a tray is presented, in which the k-ε model of turbulent flow was adopted with consideration of the rising vapor as a resisting force. The calculated results show that the theoretical prediction is in agreement with the experimental measurement.

Optimization and Aerodynamic Characteristics of New Air-Cushion Nozzle of Floating Furnace for Automobile Body Sheet

It is very important to develop new air-cushion nozzles so as to raise the heat treatment property of aluminum alloy automobile body sheet(ABS). A geometric model of air-cushion furnace equipment of ABS was built up and flow field was simulated by using k-ε turbulence equations of COMSOL Multi-physics. The influence and regularity of number(n),diameter(d) and arrangement of middle hole,and main control parameters of new air-cushion nozzle on aerodynamic characteristics and flow field were studied. The results show that:1) with n increases,airflow vortexes in air-cushion area increase in multiple; d decreases or n increases,air cushion pressure(p_c) becomes uniform; 2) average of p_c is proportional to pressure in nozzle box(p_t),when n increases,ratio of average of p_c to p_t increases,and when n ≤ 3 and d < b / 2,they have little effect on ratio of p_c average to p_t; 3) when n is an even number,n ≥4,and d ≤ b/2,p_c shows good uniformity; when n is an odd number,the center hole affects p_c uniformity greatly,and,when diameter of center hole is less than b / 4 and diameter of non-center is between b / 4 and b / 2,p_c has good uniformity. A new air-cushion jet model was presented,and the deviation of this new model with simulation data and experimental measured data are less than 7.75% and 7.76%,respectively. The present research is valuable for improving air-cushion stability,Al strip temperature homogeneity,and temperature control precision.

Computational Fluid-dynamics of Liquid Phase Flow on Distillation Column Trays

The liquid flow on a single-pass sieve distillation tray is simulated with a three-dimensional computational fluid dynamics (CFD) program with the K-ε turbulence model. In the model, a source term SMi is formulatedin the Navier-Stokes equations to represent the interfacial momentum transfer and another term Sc is added to themass transfer equation as the source of interfacial mass transfer. The simulation provides the detailed informationof the three-dimensional distribution of liquid velocity on the tray, the circulation area and the concentration profilealong the height of liquid layer.

Characteristics of Trays Using Inertial Separation Technology

Though they look very different,UOP SimulFlowTM,Koch-Glitsch Ultra-FracTM,Jaeger CoFloTM and Shell ConSepTM trays fall into the same category of trays using inertial separation technology. However,flooding mechanisms and the trends of entrainment and efficiency are different due to their different working principles. This paper provides a detailed analysis of these trays using available information from literature and U.S. Patents. Efforts are also made to interpret the observations reported. In terms of tray efficiency,it is found that SimulFlow,Ultra-Frac and CoFlo trays are typical point efficiency devices due to a completely mixed liquid pool on the tray deck,while ConSep trays can take advantage of liquid concentration gradient on the tray deck,which makes this tray at-tractive among all ultra high capacity trays.

Hydrodynamics performance and tray efficiency analysis of the novel vertical spray packing tray

Column setup has been widely utilized in the petroleum and chemistry industries. However, with the fast progress of industries and the increasingly serious energy shortage, designing a new column setup with better performance and higher capacity becomes more urgent. In order to improve column's capacity and expand operating condition, a new type of column tray named novel vertical spray packing(NVSP) tray was designed and experimented. The performances of the novel tray, including pressure drop, weeping, entrainment and tray efficiency, were tested in a plexiglass column. In addition, performances of the novel tray were compared with that of the sieve tray and the Glitsch V1 valve tray. Based on the experiment data, the mathematical correlations of pressure drop, weeping and entrainment for the novel tray were established by regression analysis method. A fundamental model of dry pressure drop of the novel tray was promoted at the form of sum mode. The results indicate that the novel tray has wider operating condition and better performance.

Bubble Formation Characteristics from a Sieve Tray with Liquid Cross-flow

An apparatus, designed to simulate bubbling of sieve tray operatedin froth regime, was employed. Bubble contact angles in and above theincipient weeping regime for an air-water-plexiglas system wereinvestigated. The influence of both liquid cross-flow and gas up-flowupon bubble contact angles was examined. A model consider- Ing theinfluence of liquid cross-flow was developed to predict bubble sizefrom a sieve hole in froth operation regime. The comparison showsthat the bubble sizes predicted by the present model are consistentwith our experimental Values and the available published experimentaldata.

Computational Fluid-dynamics of Liquid Phase Flow on Distillation Column Trays

A computational fluid-dynamics model is presented for predictingthe two-phase two-dimensional liquid phase flow on a distillationcolumn tray based on the modification of Navier-Stokes Equation byconsidering both the resistance and the enhanced turbulence createdby the uprising vapor. Experimental measurement of the local liquidphase velocity on an air-water simulator of 1.2 m in diameter byusing the hot film anemometer is briefly described. Two of theconventional fluid-dynamic constants are readjusted for the case ofliquid flow on a tray by fitting the experimental data.

CFD gas–liquid simulation of oriented valve tray

Computational fluid dynamics(CFD) has recently emerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers.The computation domain was established for two types of oriented valves within a tray and meshed into two parts with different grid types and sizes.The volume fraction correlation concerning inter-phase momentum transfer source was fitted based on experimental data,and built in UDF for simulation.The flow pattern of oriented valve tray under different operating conditions was simulated under Eulerian-Eulerian framework with realizable k-ε model.The predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations.Meanwhile,the velocity distribution and volume fraction of the two phases were demonstrated and analyzed,which are useful in design and analysis of the column trays.

SIZE DISTRIBUTION OF DROPLETS ABOVE A ROTATING STREAM TRAY AND MODEL OF DROPLET MOTION THEREIN

Droplet size distributions have been investigated with a two-probe system above a rotatingstream tray of 300 mm diameter.The measured distributions are found to follow the upper limitedlognormal distribution with three parameters dependent primarily on gas hole F-factor.A probabilitymethod is used to describe the initial state of the droplet population above the tray,and a model fordroplet motion is presented.The results computed with model agree well with experimental data.

The Analysis of Distillation Tray Column Efficiency by Fluid Dynamics and Mass Transfer Computation

It has long been found that the flow pattern of the liquid phase on distillation tray is of great importance on distillation process performance. But until now, there was very few published work on quantitative investigation of this subject. By combining the computational fluid dynamics (CFD) with the mass transfer equation, a theoretical model is proposed for predicting the details of velocity and concentration distributions as well as the tray efficiency of distillation tray column. Using the proposed model, four different cases corresponding to different assumptions of liquid and vapor flowing condition for a distillation tray column were investigated. In Case I, the distributions of velocity and concentration of the incoming liquid from the downcomer and the uprising vapor from the underneath tray spacing are uniform. In Case n, the distribution of the incoming liquid is non-uniform but the uprising vapor is uniform. In Case HI, the distribution of the incoming liquid is uniform but the uprising vapor is non-uniform. In Case IV, the distributions of both the incoming liquid and the uprising vapor are non-uniform. The details of velocity and concentration distributions on a multiple sieve tray distillation column in four different cases were simulated using the proposed model. It is found that the shape of the simulated concentration profiles of vapor and the liquid is quite different from case to case. The computed results also show that the tray efficiency is highly reduced by the maldistribution of velocity and concentration of the incoming liquid and uprising vapor. The tray efficiency for Case I is higher than Case Ⅱ or Case Ⅲ, and that for Case Ⅳ is the lowest. It also reveals that the accumulated effect of maldistribution becomes more pronounced when the number of column trays increased. The present study demonstrates that the use of computational method to predict the mass transfer efficiency for the tray column, especially for the large one, is feasible.

Effect of Structural Parameters on the Performance of NS High-efficiency Composite TraysⅠ.The Effect of Aperture and Opening Ratio on NS High-efficiency Composite Trays

In this paper,the structure and characteristics of the NS high-efficiency composite trays based on the doublelayer aperture jet sieve plate and compositely structured packing were investigated.The effect of aperture and opening ratio of plate on the fluid dynamics of the NS high-efficiency composite trays,such as the dry tray pressure drop,the wet tray pressure drop,the entrainment,the froth height,the leakage and mass transfer characteristics,were investigated.As a result, the low pressure drop,the high efficiency and the high capacity are the main advantages of the NS high-efficiency composite trays compared to other types of trays.According to this study,small aperture is useful for reducing the pressure drop and entrainment with a high mass transfer efficiency;while large aperture can achieve high capacity and efficiency in a broader operating range at the same pressure drop and entrainment.

Research of air-cushion isolation effects on high arch dam reservoir

A three-dimensional （3D） finite element model of air-cushion isolated arch dam is presented with the nonlinear gas-liquid-solid multi-field dynamic coupling effect taken into account.In this model,the displacement formulation in Lagrange method,pressure formulation in Euler method,nonlinear contact model based on Coulomb friction law are applied to the air-cushion,reservoir and contraction joint domain,respectively.The dynamic response of Jinping I arch dam with a height of 305 m is analyzed using the seismic records of the Wenchuan Earthquake in 2008.Numerical results show that the air-cushion isolation reduces significantly the hydrodynamic pressure as well as the opening width for the contraction joints of high arch dam.

Multi-enzymes Production Studies in Single Tray Solid State Fermentation with Opened and Closed System

The robustness ofA. awamori and A. oryzae as enzyme producers is exploited in fungal fermentation on agricultural solid waste. High-level production of extracellular glucoamylase, protease, cellulase and xylanase has been achieved. Three different types of ＇waste＇ solids （wheat bran, soybean hulls and rapeseed meal） have been used in studies of solid state fermentation （SSF）. The enzymes could be produced in significant levels by continuously supplying oxygen （02） through the tray system known as ＂closed＂ and ＂opened＂ tray systems. A perforated tray system was developed in this study that permits direct access to 02. Testing the tray system with different perforated mesh aperture sizes in this study did not yield different results in growth performance of A. awamori and A. oryzae. A. awamori and A. oryzae can be very versatile in producing various enzymes with different substrates with different starch, protein, hemiceilulose and cellulose contents. These studies indicate that A. awamori is more suitable for the efficient production of multiple enzymes in the closed system including xylanase and cellulase, while the production of glucoamylase and protease is superior in the opened system. A. oryzae is more suitable for the efficient production of protease and cellulase in the closed system, while the production of protease is more favourable the opened system. A. awamori efficiently consumed starch in wheat bran medium and produced very high glucoamylase activity, and after that, the fungus efficiently produced other enzymes to degrade other complex nutrients such as protein, hemicellulose and cellulose. Meanwhile, A. oryzae efficiently consumed protein in rapeseed meal and produced very high protease activity. The ability of both filamentous fungi, to convert biomass through SSF bioconversion will have a great impact on food and agro-industry in every aspect of life from food and medicine to fuel.

如何利用Authorware在System Tray中放置应用程序图标

对Authorware4 .0调用WindowsAPI和引用ActiveX控件的方法进行了详细的描述 。

Hydrodynamics and Mass Transfer of Jet Co-flow Packing Tray

The jet co-flow packing tray(JCPT) with three different types of perforation in equal opening fraction was tested in two rectangular columns with 0.12m in width and 0.27m in length operated with air-water system. The influences of gas phase orifice F-factor and clear liquid height Hc on the amount of liquid lifted, Q, were examined. The corresponding correlation between Q with F-factor and equivalent diameter of perforated holes as well as Hc was obtained. Furthermore, the non-steady state mass transfer performance of JCPT was tested by the humidification of air with water. Finally, by the analysis of data and comparison, it was found that the JCPT tray with single cap and two holes exhibited the highest mass transfer efficiency and best performance.