半水-二水法再结晶浓磷酸工艺流程过滤系统的优化

分析了半水-二水法再结晶浓磷酸生产工艺流程中过滤系统目前存在的问题,并从滤饼洗涤水的加入方式、过滤真空度控制及工艺管道结垢清理等操作方式进行优化。优化措施实施后,装置运行更加平稳,过滤系统的料浆过滤和洗涤效率得到显著提升,装置总磷收率由95%提高至98%以上。

半水-二水法磷酸装置中控制阀的选型

简述了半水-二水法磷酸的工艺及腐蚀特点,半水-二水法相比二水法在局部工况,尤其是在半水反应、半水过滤部分,料浆中P2O5的质量分数和温度较高,对阀门的磨损和腐蚀强度更大,对控制阀的选型提出了更高的要求。重点研究了各腐蚀性介质中隔膜控制阀和旋塞阀的材质选择,并结合控制阀在两个工程中的实际应用情况,给出了半水-二水法磷酸装置中各腐蚀性介质的控制阀选型意见。

半水-二水磷矿评价装置开发及其用途

简述了半水-二水磷矿评价装置的开发目的,分别从磷矿评价装置的流程和磷矿评价试验典型的分析指标两方面,介绍了半水-二水磷矿评价装置的开发内容。另外,阐述了半水-二水磷矿评价装置的功能及用途,即在评价装置的基础上,借助辅助分析仪器,进行磷矿理化性质分析、过程控制分析、成品酸分析、石膏矿物学特征分析等。最后,介绍了中国五环工程有限公司磷矿评价装置的开发进展及意义。

赴瑞典对半水—二水法磷酸技术的考察报告

本文介绍了采用诺斯克、哈特罗(Norsk Hydro)公司半水-二水法磷酸工艺的瑞典苏甫拉(Supra)工厂的实际运转情况,着重叙述了该法获取良好的半水物结晶的原理、条件以及开工率、磷得率、设备运输等情况。

大型半水—二水法磷酸装置开发与运行回顾

简要介绍了中国五环工程公司开发的大型半水—二水法磷酸装置的突出优势、工艺特点以及技术难点,重点介绍印度尼西亚磷肥项目磷酸主装置半水—二水法工艺设计指标、关键设备、总图布置、成品酸指标、装置性能考核等情况,最后指出了该装置运行取得的创新成果及其运用前景。

Resource allocation based on fairness and QoS provisioning for OFDMA-WLAN system

To satisfy different service requirements of multiple users in the orthogo nal frequency division multiple access wireless local area network OFDMA-WLAN system downlink transmission a resource allocation algorithm based on fairness and quality of service QoS provisioning is proposed. Different QoS requirements are converted into different rate requirements to calculate the QoSs atisfaction level.The optimization object is revised as a fairness-driven resource optimization function to provide fairness. The complex resource allocation problem is divided into channel allocation and power assignment sub-problems. The sub-problems are solved by the bipartite graph matching and water-filling based method.Compared with other algorithms the proposed algorithm sacrifices less data rate for higher fairnes and QoS satisfaction.The sim ulation results show that the proposed algorithm is capableo fp rovi ding QoS and fairness and performs better in a tradeoff among QoS fairness and data rate.

Surface modification of NiTi alloy by sol-gel derived porous TiO_(2)film

Titania films with nano-sized pores were prepared on the NaOH？HCl pretreated NiTi alloy substrate by sol？gel method.A crack-free film is obtained for the sample with a dense inner layer and a porous outside layer（sample TC1＋1）.The X-ray diffraction shows that the titania films are composed of anatase,and a little Ni4Ti3 phase in the heat treated substrate is also detected.The X-ray photoelectron spectroscopy results indicate that the titania film completely covered the NiTi substrate for sample TC1＋1.The sample TC1＋1 is hydrophilic with a contact angle about 20°,and UV illumination treatment for 15 min further decreases the contact angle to（9.2±3.2）°.The potentiodynamic polarization test in 0.9% NaCl solution reveals a better corrosion resistance of sample TC1＋1 than the polished NiTi sample.

铵盐在二水—二水流程中对磷石膏的影响

“二水-二水法”萃取磷酸新流程,是郑州工学院磷肥研究室提出的,并且从1984年7月开始,进行流程的可行性研究实验,取得了令人满意的结果。本文研究了铵盐在二水-二水流程中对磷石膏的影响.

Syntheses, Structures and Magnetic Properties of Two Co(II) Coordination Polymers with 2,5-Pyridine Dicarboxylic Acid

The hydro(solvo)thermal reactions of cobalt powder or its chloride with 2,5- pyridine dicarboxylic acid (H2PYDC) yielded two new complexes: [Co(II)2(PYDC)2(H2O)2- (H2O)4]n 1 and {Co(II)[NH2(CH3)2]2(PYDC)2}n 2. It is observed that the reactive solvents result in different connectivity modes of ligand and diverse dimensional extension of crystal structures. The correlation between structure and magnetic property will be discussed in this paper. Crystal data for 1: space group P1, a = 7.0419(17), b = 8.937(2), c = 9.6182(19) ?, α = 91.532(4), β = 99.869(10), γ = 107.889(11)o, V = 565.5(2) ?3, Z = 1, Dc = 1.845 g/cm3, μ = 1.56 mm-1, F(000) = 322 , R = 0.0505 and wR = 0.1580; and those for 2: space group C2/c, a = 14.9075(6), b = 8.2523(3), c = 16.9643(2) ?, β = 100.982(2)o, V = 2048.75(11) ?3, Z = 4, Dc = 1.560 g/cm3, μ = 0.892 mm-1, F(000) = 996, R = 0.0443 and wR = 0.1134.

Measurements of Hydrate Equilibrium Conditions for CH4, CO2, and CH4＋C2H6＋C3H8 in Various Systems by Step-heating Method

Phase equilibrium conditions of gas hydrate in several systems were measured by the step-heating method using the cylindrical transparent sapphire cell device.The experimental data for pure CH4 or CO2+deionized water systems showed good agreement with those in the literatures.This kind of method was then applied to CH4/CO2+sodium dodecyl sulfate(SDS)aqueous solution,CH4/CO2+SDS aqueous solution+silica sand,and(CH4+C2H6+C3H8)gas mixture+SDS aqueous solution systems,where SDS was added to increase the hydrate formation rate without evident influence on the equilibrium conditions.The feasibility and reliability of the step-heating method,especially for porous media systems and gas mixtures systems were determined.The experimental data for CO2+silica sand data shows that the equilibrium pressure will change significantly when the particle size of silica sand is less than 96μm.The formation equilibrium pressure was also measured by the reformation of hydrate.

The Assessment of Heavy Rains in the Region of Annaba （NE Algeria） to Improve Extreme Flood Forecasting ,, Use of Depth-Duration-Frequency Curves

The knowledge of space and time distribution of short duration rainfall depths is of primary interest in hydrotechnical studies and in extreme floods modelling. This work is carried out to establish a ＂DDF （Depth-Duration-Frequency）＂ relationship for the region of Annaba （Northeast of Algeria） through the examples of Pont Bouchet （El Hadjar）, Ain Berda and Chafia-Dam rainfall gauges. The results of the frequency study of stochastically generated annual series （Pearson＇s distribution type III model） and the regression analysis （least square method） permitted to develop a master curve that well describes heavy rainfalls distribution in the Annaba region. This 2-parameter model is used to predict, with sufficient accuracy, the amount of rain that could be recorded over a shorter duration from daily rainfall data in basins that lack recording rain gauges.

Kinetics of Forward Extraction of Boric Acid from Salt Lake Brine by2-Ethyl-1,3-hexanediol in Toluene Using Single Drop Technique

The kinetics of forward extraction of boric acid from salt lake brine by 2-ethyl-1,3-hexanediol in toluene was investigated using the single drop technique. The factors affecting the extraction rate include interfacial area between aqueous phase and organic phase, initial concentration of boric acid in aqueous phase, initial concentration of 2-ethyl-1,3-hexanediol in organic phase, and extraction temperature. The experimental results show that the extraction rate increases with the increase of the initial concentration of boric acid and2-ethyl-1,3-hexanediol, interfacial area of two phases, and temperature. With the temperature-dependence study, it is showed that the extraction is a diffusion-controlled process. The kinetic equation is presented for pH 1.0 in the aqueous phase and temperature of 318 K.

Effect of Gravity on Collective Excitations of a Quasi Two-Dimensional Bose Einstein Condensate in an Anharmonic Trap

Abstract Using variational method, the wave function of a quasi two-dimensional Bose-Einstein Condensate in an anharmonic trap is analyzed and the influence of gravity on the eollective excitations is studied. It is found that the effect of gravity on the condensate has got crucial dependence on the anharmonieity of the trap.

Determination of Water Content of Water-soluble Paints by Gas Chromatography

This paper describes the determination of water content of water-soluble paints by gas chromatography. The water in paints is extracted by dimethyl formamide (DMF) as a solvent.Isopropanol is used as an internal standard. The mixture is separated by low-speed centrifugation.Then a 1-uL sample of the supernatant from the prepared solution is injected into the gas chromatograph. The water content is determined by internal standard calibration curve. The rate of recovery of added standard of this method is more than 98%. Relative mean deviation is less than 3‰.The linearity of calibration curve is good and relativity coefficient is higher than 0.998.

Unconventional Landau Levels of Ultracold Fermionic Atoms on Two-Dimensional Honeycomb Lattice

We investigate the unconventional Landau levels of ultracold fermionic atoms on the two-dimensionalhoneycomb optical lattice subjected to an effective magnetic field,which is created with optical means.In the presenceof the effective magnetic field,the energy spectrum of the unconventional Landau levels is calculated.Furthermore,wepropose to detect the unconventional Landau levels with Bragg scattering techniques.

Developing a 2D vertical flow and sediment transport model for open channels using the Youngs-VOF method

A 2D vertical （2DV） numerical model, without o-coordinate transformation in the vertical direction, is developed for the simulation of flow and sediment transport in open channels. In the model, time-averaged Reynolds equations are closed by the k-e nonlinear turbulence model. The modified Youngs- VOF method is introduced to capture free surface dynamics, and the free surface slope is simulated using the ELVIRA method. Based on the power-law scheme, the k-e model and the suspended-load transport model are solved numerically with an implicit scheme applied in the vertical plane and an explicit scheme applied in the horizontal plane. Bedload transport is modeled using the Euler-WENO scheme, and the grid-closing skill is adopted to deal with the moving channel bed boundary. Verification of the model using laboratory data shows that the model is able to adequately simulate flow and sediment transport in open channels, and is a good starting point for the study of sediment transport dynamics in strong nonlinear flow scenarios.

Two-dimensional Numerical Simulation of an Elastic Wedge Water Entry by a Coupled FDM-FEM Method

Hydroelastic behavior of an elastic wedge impacting on calm water surface was investigated. A partitioned approach by coupling finite difference method （FDM） and finite element method （FEM） was developed to analyze the fluid structure interaction （FSI） problem. The FDM, in which the Constraint Interpolation Profile （CIP） method was applied, was used for solving the flow field in a fixed regular Cartesian grid system. Free surface was captured by the Tangent of Hyperbola for Interface Capturing with Slope Weighting （THINC/SW） scheme. The FEM was applied for calculating the structural deformation. A volume weighted method, which was based on the immersed boundary （IB） method, was adopted for coupling the FDM and the FEM together. An elastic wedge water entry problem was calculated by the coupled FDM-FEM method. Also a comparison between the current numerical results and the published results indicate that the coupled FDM-FEM method has reasonably good accuracy in predicting the impact force.

Droplet Contact Angle Measurement on Microstructures of Octocoral Sclerites-ESEM Image Analysis

This work explores the methodology for micron-scale water droplet contact angle derivation for the warty surface of octocoral sclerites. The calcite-made sclerites of the Red Sea octocoral Dendronephthya hemprichi have been chosen as a model for this study. Water droplet condensation on the sclerites has been in-situ investigated using Quanta 200 FEG （field emission gun） ESEM （environmental scanning electron microscope） under wet environmental conditions. Two different analysis methods of droplet top and side views have been applied to determine the contact angle based on the secondary electron images. The ESEM image analysis for the sclerites indicates that their surface is hydrophilic. The microscopic contact angle is measured to be 45.3°±6.3°. The macroscopic contact angle has been calculated by using the Wenzel model for the surface texturing of the sclerites.

Solving Two-Dimensional Moving-Boundary Problems with Meshless and Level Set Method

During the past decade, increasing attention has been given to the development of meshless methods using radial basis functions for the numerical solution of Partial Differential Equations （PDEs）. A level set method is a promising design tool for tracking, modelling and simulating the motion of free boundaries in fluid mechanics, combustion, computer animation and image processing. In the conventional level set methods, the level set equation is solved to evolve the interface using a capturing Eulerian approach. The solving procedure requires an appropriate choice of the upwind schemes, reinitialization, etc. Our goal is to include Multiquadric Radial Basis Functions （MQ RBFs） into the level set method to construct a more efficient approach and stabilize the solution process with the adaptive greedy algorithm. This paper presents an alternative approach to the conventional level set methods for solving moving-boundary problems. The solution was compared to the solution calculated by the exact explicit lime integration scheme. The examples show that MQ RBFs and adaptive greedy algorithm is a very promising calculation scheme.