In this paper, a heat exchanger network is simulated by a new transshipment model. The model is a stage-wise representation of thermodynamic control volume. Within each stage, hot stream and cold stream are split with heat exchange between each other, then are mixed at different temperatures and enter the next stage. This transshipment model is meshed with a nonlinear programming to model both the selection of stream matches and the derivation of a heat exchanger network configuration, and allows the feasible space to be defined by a set of linear constraints. A new simultaneous optimal synthesis method is thusdeveloped on solid physical background to generate automatically a heat exchanger network which provides simultaneously optimal utility consumption level, srteam matches and network configuration. The method overcomes the shortcomings of such decomposition methods as (extend) pinch point design, dual temperature difference method and mathematical programming, and has unique advantages compared with other simultaneous optimization models, Working examples have proved that the proposed method compares favorably with the other existing methods.

The mass transfer characteristics in an annular pulsed extraction column were studied with four different annular widths. 30% TBP(in kerosene)-HNO3 - H2O was used as experimental system (water as continuous phase). The solute concentration profiles under steady state were measured. Mass transfer parameters were estimated from the diffusion model by fitting the measured concentration profiles. Correlation of mass transfer parameters (Hoxand Hoxd) was suggested. Results showed that the "true" mass transfer unit height Hox of four annular extraction columns can be correlated with the same equation and the diffusion unit height Hoxd is in direct proportion to the 0. 16 power of the ratio of annular width to column diameter. In comparison with annular column 0. 05m in diameter, the correlation equation of Hox is the same for two kinds of annular column, but that of Hoxd is different. It indicates that axial miximg is affected by column diameter.

In this paper, Extended Huckel Molecular Orbital Theory (EHMO) and Complete Neglect Differential and Overlap Method (CNDO/2) are used to calculate chemical reactivity indices of paraffins and their radicals. Through analysing the dependence of known elementary reaction rate constants on the chemicl reactivity indices, a method for predicting unknown kinetic rate constants is presented. By means of the method, a relation between kinetic behavior of reactants (macro-properties) and their molecular structural properties (micro -properties) is established. The method is used to predict elementary rate constants of thermal cracking of paraffins and is proved to be feasible and reliable. On this basis, PFR model and pseduo - steady - state assumption are used to describe the thermal cracking process of C4- paraffins. Michelson and pseudo -Newton methods are used to self - consistently solve kinetic differential and algebraic equations. The simulated results have good agreement with overall experimental data published in the literature. It indicates that the established kinetic model of thermal cracking of paraffins is correct and reliable.

This paper briefly describes the structure and performance of a special bipolar filter press -type chlorate cell. The cathode is oxygen diffusion electrode, which replaces the current iron cathode, and air acts as de - polarizer. When the cell is operated at the 100 mA/cm2current density, the average single cell voltage is between 2. 000 and 2. 200V. The current efficiency can reach 90 ± 2% with the absence of Na2Cr2O7 in electrolyte. The D. C. consumption is 3700±100kW · h/t NaClO3. The cell can be operated steadily.

The hydrodynamics of a liquid - solid circulating fluidized bed was investigated in a plexiglass equipment of 140 mm in inner diameter and 3 m in height. In the circulating fluidizing regime, the bed has the characteristics of uniform distribution of phase holdups in the axial direction but non - uniform in the radial position. The solid circulating rate keeps constant when the superfacial liquid velocity changes within the circulating fluidization regime. Because of the non-uniformity of the phase holdups in the radial position there is a great difference between the theoretical results based on the generalized fluidization principles and the experimental results of the variation of the solid circulating rate versus the bed voidage.

Following the work reported in paper I, the hydrodynamics of the liquid-solid circulating fluidized bed were studied further. The experimental results of the apparent slip velocity between liquid and solid show that there is a great difference between the experimental results and the theoretical calculated values based on the generalized fluidization relationships. The experimental results of the apparent relative drag coefficients also show that there is a large difference between the theoretical and experimental results. It seems conclusion can be drawn that it is difficult to predict the hydrodynamics of the liquid - solid circulating fluidized bed by using the generalized fluidization relations.

The solubility of CO2 in aqueous methyldiethanolamine solutions was measured in atmospheric pressure cell and high pressure cell, respectively. The experimental temperature was from 40 to 100℃ , CO2 partial pressure was from 1 to 1000 kPa and the concentration of methyldiethanolamine was from 2. 0 to 4. 28 kmol/m3. A simple model and a thermodynamic model which can be used for engineering calculation were established by using the solubility data determined. The heat of solution were calculated from the experimental results with the Gibbs -Duhem equation.

Based on the similarity between pVT and Tμp relationships, Patel - Teja equation of state was used to develop a unified viscosity model for both pure gases and liquids. By using a general mixing rule for the EOS parameters, the viscosity equation was used to predict the viscosities of binary light hydrocarbon mixtures (a total of 1894 data points) and simulated natural gases, the overall average absolute deviations being 11. 93% and 16. 75%, respectively. For reservoir crude oils and natural gases under high pressure, significant improvement in viscosity predictions was observed as compared with the viscosity model currently used for reservoir mixtures.

A new design of mixer-settler is presented. The mixer has several mixing chambers in series and with water dispersed in oil in the mixer. The mixer with several mixing chambers in series can improve the residence time distribution of both phases in the mixer significantly. The dispersion of water in oil can increase the rate of mass transfer. The new design also has the advantages of low backmixing in the mixer and very little intrastage and interstage short circuiting. Both the new design and the existing mixer settler in which mixer is a single mixing chamber with oil dispersed in water in the mixer were used to separate rare earth elements totest their performance. Laboratory results indicated that the ratio of efficiency for the separation of light group and heavy group of rare earth elements is 1. 426 and the ratio of efficiency for the separation of two neighbouring rare earth elements is mostly greater than 1 when the flow capacity is between 1. 46 and 2. 92m3/(m2·h).

The problem of improving structural flexibility of heat exchanger networks is to retrofit the configuration of a heat exchanger network whose flexibility does not meet the requirement and enhance its flexibility, so as to decrease its energy consumption caused by uncertain parameters. In this paper the key variables for controlling flexibility of a heat exchanger network are identified by a flexibility analysis method. The worst operation point is established in the range of the uncertain parameters. Then two subproblems of temperature difference key variable and heat load key variable are solved to configure the corresponding e-quivalent structure, and the flexibility of the network can be efficiently improved, by using the strategies of shifting, splitting and decreasing heat load.

The theoretical calculation methods,i. e. , the numerical method and the simplified integral method, for predicting particle flow rate through an orifice have been established by using the theory of nonfluidized gas - particle two phase flow. The active stress state and the passive stress state of the particle flow are discussed. The choice of the signs ±and in the theoretical equations is also proposed. The empirical equations for evaluating the correctness factor,Co,which is used to make correction for the particle flow rate Gp calculated by the numerical method and the simplified integral method under the passive stress state, are also given on the basis of regression analysis for experimental data. The predicted value of particle flow rate is in good agreement with the experimental data.

Solderability of tin - based composite coating was studied by adding TUM series of additives to the soldering bath. The 3 second wetting force of the composite coating almost reached the theoretical value, with its solderability approaching the best level. The effect of inner factors (surface oxidic film, "tin pest")on solderability was investigated. The microcrys-talline structure and surface oxidation were examined with X - ray diffraction and ion probe, and the mechanism of the effect of composite particles on solderability was studied.

On the basis of the change in value of motion energy of particles passing through a shock wave during the time of speed relaxation, this functional relations were set up betweenflow parameters both in front and back of shock wave of supersonic nozzle and average size of particles as well as they and specific surface area of particles, and this relations were supported satisfactorily by the experiment in this paper. The research conclusion made known that the pulverizing effect of shock wave increased with strengthening shock waves and enlarging particles size in certain range, and it was fluctuate change with varying Mach number. However, shock wave did not make the particles size vary too much, on the contrary, it made the jet speed of nozzle reduced, and also made the intensity of impact pulverizing reduced , it is disadvantage to improve the comprehensive grinding efficiency of a jet mill. Hence, shock wave should be eliminated as possible as in the design and operation for a jet mill.

A mathematical model which describes the membrane distillation of aqueous solution containing more volatile solute is improved. Mass and heat transfers of two volatile compounds in the membrane and air gap are concerned. The paper proposes a mathematical simulation method which is divided the whole membrane length into tiny sections and calculates part for part. The simulation results agree with the experimental data satisfactorily.

In this paper, the refining of naphthalene by parametric pumping fractional crystallization technique is studied. A mathematical model for batch multistage fractional crystallization is established based on principles of crytsallization and sweating. The Gauss - Newton method is used to give a numerical solution cnystalliztion of the model. The calculated results are consistent with the medial experimental values. This mathematical model is correct and can be the basis for scaling up parametric pumping fractional crystallization.

Inorganic hydroxyapatite (HAP) and its mixture with polyvinylalcohol (PVA) used as a dispersant system in styrene suspension polymerization, the effects of dispersed phase ratio, the concentration of HAP and stirring speed on the formation of polymer particle were examined experimentally. The characteristics of coalescence and breakup of droplets were analyzed in particular. The results showed that the growth of suspension styrene droplets was independent of the dispersing mechanism of stabilizer but was a process of coalescence and breakup of droplets. The growth of droplets could be controlled by adjusting the way of adding dispersant during polymerization. It was observed that droplet size distribution changed from single - peaked to bimodal distribution and then back to single - peaked distribution with the dispersant added in two batches. These results will help to produce suitably sized polymer particle with a narrower size distribution.

The activity coefficients of NaBr in the system NaBr - NaAc - H_2O at 298. 15K were determined from EMF measurements at constant total ionic strengths of 0. 1, 0. 5, 1. 0, 1. 5, 2. 0, 2. 5 and 3. 0 mol/kg. At each total ionic strength studied the measurements were carried out at different ratios of the NaAc to NaBr ionic strengths. The experimental activity coefficients were fitted by using the Harned equation, Scatchard equation and Pitzer equation. Although all these models can be successfully applied to the analysis of this system, the Pitzer equation leads to better fitting than the others. Finally, the excess Gibbs free energy of these mixtures was also calculated.

A particle removal method is proposed for the computer simulation of excess Gibbs free energy for the Lennard -Jones mixture fluids, and an approximate equation is derived. This method presents satisfactory results for the mixtures where the molecules are of identical interaction energy parameters, but of different molecule sizes, in particular. Moreover , this method reduces computing effort and can be extended to high density region.

The removal of yeast cell debris following high - speed bead mill disruption was studied by using polyethylene glycol (PEG) precipitation. The partition rule of cell debris was investigated in PEG/inorganic salts systems. Cell debris might be partitioned between the bottom, intermediate and top phases in different aqueous two - phase compositions. When there was only PEG or there were PEG and a little amount of salt, yeast homogenate was separated into a supernatant containing intracellular products and a solid cell debris sediment by using only low speed centrifugation. The effective removal of cell debris and the extraction of intracellular alcohol dehydrogenase were further studied by using the liquid -solid two -phase system and aqueous two -phase systems.