Principal component analysis (PCA) is an effective method to extract relationships between variables and thus has been widely applied to multivariate statistical process monitoring and fault diagnosis. In this paper,an improved PCA is presented which uses principal-component-related variable residual (PVR) statistic to replace Q -statistic in the conventional PCA. The improved PCA can avoid the conservation of Q statistical test and provide more explicit information about the process conditions.As a result,the root cause that violates the Hotelling T² test but still satisfies Q test can be unambiguously identified,which is impossible in the conventional PCA.Then a simulated double-effect evaporator is monitored and diagnosed by using this proposed method and comparisons with the conventional PCA are made.The simulation result shows that the improved PCA is more sensitive to weak process changes and has an enhanced fault diagnosing performance.

Taxol, originally isolated from the bark of Taxus brevifolia, is a very important new anti-tumor drug.Reversed phase chromatography provides a rapid, efficient, and inexpensive method to separate and purify taxol. However, it is very important to scae-up the isolation process in order to obtain a large amount of taxol. From studies on the basic transport phenomena between solid phase and liquid phase, the rate model for non linear liquid chromatography under normal pressure is proposed.The process of taxol separation on C 18 - silica gel column could be described by this model very well.The numerical solution of model agrees well with experimental data.The factors affecting the separation of taxol, including feed concentration,feed rate and column size are investigated.It is confirmed that the mathematical model could be very useful for scaling-up chromatographic operation.

For shell-and-tube oil cooler with water cooling, the heat transfer resistance on the shell side is 80% of the total heat transfer resistance of the cooler,so oil heat transfer resistance is controlling.It is a key factor to increase heat transfer coefficient of oil on the shell side for making high performance oil cooler.Two measures to be taken to increase heat transfer coefficient of oil,are first to use highly effective enhanced tube,and second to use novel shell side baffle geometry.Petal-shaped fin tube has special three-dimensional fin, it can effectively induce turbulence of oil flow,help to form a thinner oil boundary layer.Helical baffle produces a psuedo helical flow path on the shell side.It is shown experimentally that when turbulent flow is guided through a tube bundle of a certain helical angle, significant enhancement of shell side coefficient is achieved. In this paper,the heat transfer and pressure drop performance of petal-shaped fin tube oil-cooler with helical baffle is compared with that of low fin tube oil-cooler with helical baffle.The experimental results show that the total heat transfer coefficient of petal-shaped fin tube oil-cooler with helical baffle is 10% higher than that of low fin tube oil-cooler with helical baffle,and pressure drop is 46% lower than that of low fin tube oil-cooler with helical baffle.

The correlation between energy dissipation and split ratio in a 35mm diameter de-oiling hydrocyclone was established by experiment.under the conditions of different overflow orifice diameters, as long as the split ratio is less than 25%,energy dissipation was a constant.It only changed with inlet flow rate.When the inlet flow rate was 30,40,50,60,70L·min ^-1 ,the energy dissipation is about 10,30,80,140,205N·m·s ^-1 respectively.Based on this characteristics of hydrocyclone and theoretical analysis,a prediction model of de-oiling hydrocyclone was proposed.The prediction of pressure drop ratio was identical with the test data.

The dilute gas-particle flows in a cyclone chamber with axial and tangential inlers of different swirl numbers were studied by using a Phase-Doppler Particle Anemometer(PDPA).The measured two-phase axial,tangential time-averaged velocities and fluctuation velocities under the same overall air flow-rate,with swirl numbers of 0,0.5 and 1.0 respectively,are reported here.The results show that the swirl intensity has a remarkable effect on the profiles of axial velocity,the vortex structure of tangential velocity,the two-phase fluctuation velocity and the anisotropy of turbulence.The swirl can generally reduce two-phase turbulence.The intensity of turbulent fluctuation and its anisotropy decrease significantly with increasing swirl number at first,and they increase a little while the swirl number exceeds 1.

The time-dependent liquid film thickness in horizontal and slightly inclined tubes was measured by using parallel-wire conductance probes,and various wave patterns were obtained.The features of probability density function,probability distribution, auto-correlation,cross-correlation and power spectrum density function of waves were studied in amplitude domain,time domain and frequency domain respectively. The parameters of wave,such as wave amplitude,wavelength,wave velocity and wave period were obtained. The variation of wave parameters with gas,liquid superficial velocities and tube inclination angle were presented.

The liquid-solid circulating moving bed reactor is a novel one, which consists of two or more reaction chambers and a particle transport system. Particles move down from the upper reaction chamber to the lower reaction chamber through an upper conduit and to the particle transport system through a lower conduit, then are lifted from the lower chamber to the upper reaction chamber through a riser.The circulating rate of particles and the flow of liquid in the two conduit are key to the continuous operation of the reactor.In this paper,the flow behavior of liquid in the conduits and particle circulation in the reactor are studied.At the same time the flow model is proposed and verified by experiment and simulation.

A model for the propylene chlorohydrin action process in propylene oxide plant is developed.The reactor featuring natural liquid circulating and forced gas recycling is considered as two bubble reactors connected in series,the first one being the chlorine absorber and the second one the chlorohydrination reactor.The reaction is of Fyvie mechanism and the mass transfer is characterized by simultaneous adsorption of two gases with the reactions carried out in the liquid phase.Side reaction occuring in the gas phase is also considered.The gas is assumed to be plug flow and the liquid complete mixing flow in both of the two reactors.The influence of the operating variables on conversion and yield is investigated by process simulation.The model presented is found to be successful in describing the static behavior of the reactor.It is demonstrated that low temperature,low feed gas ratio,low propylene chlorohydrin concentration and high recycle gas velocity are all favorable to improving the yield.

Moisture absorption by falling film liquid desiccant is certainly a problem of heat and mass transfer of two phase flow. Heat effect produced in dehumidification makes process air and falling film warmed.Experimental practice shows that these two flows obtain different portions of heat, thus the coefficients of heat transfer for liquid side and gas side are different.While the moisture removed from process air is the same as the water absorbed by liquid desiccant, so there is aunique coefficient of mass transfer for absorption. A detailed mathematical model describing the coupled heat and mass transfer is presented and solved numerically. The calculation results indicate that for laminar flow of both process air and falling film, the Nusselt number of liquid side is about 2.84, while that of gas side is about 6.54, and the Sherwood number at the gas-liquid interface is about 5.40.In addition, theoretical analysis is conducted under given ideal conditions.It is demonstrated that theoretical Nusselt number for liquid side is 3.636.For turbulent flow of process air, Nusselt numbers and Sherwood number all increase with the increase of Reynolds number.It is concluded that the coefficients of heat and mass transfer are dependent on the thermal physical characteristics of liquid desiccant and the flowing state of process air.

Coal pyrolysis in arc plasma jet is very complex.Some factors such as Coal Specific Enthalpy ( CSE ) and coal feed rate were discussed.Experiment results showed that coal conversion increased with CSE .With the increase in concentration of coal fed into plasma jet, the volume fraction of acetylene in product gas increased evidently, which led to the improvement of acetylene yield and specific energy requirement of the process.The increase of coal feed rate was not in favor of coal conversion and acetylene yield.Coal feed rate had obvious influence on component distribution, that is the carbon number of hydrocarbon in product gas was less than two with lower feed rate.With the increase of coal feed rate,component distribution became complex and the hydrocarbons with more than three carbons were present in product gas.A reaction mechanism is presented,which suggests that thermal pyrolysis of coal in plasma jet is the first step.The secondary pyrolysis of volatile matter has much more rapid reaction rate than coal pyrolysis,and the volatile matter is assumed to be the precursor of acetylene.Acetylene decomposition is a reversible but not an equilibrium reaction.The kinetic deductions showed that this hypothesis could explain the experimental results very well.

A new pruning strategy used to evaluate the optimal size of a multi-layered feed-forward neural network is proposed in this paper.The strategy is designed for arbitrary neural network converging after normal training.The output matrix of the hidden layer is calculated and used to extract characteristics.The number of the significant characteristics corresponds to the optimal number of hidden nodes.The redundant hidden nodes are deleted and their previous contributions are loaded on to the remaining ones.Therefore,the initial weights of the optimal structure can be mathematically calculated and assigned.After retrain the optimal structure, all the weights will be determined.Finally,this strategy is satisfactorily applied to solving a real pattern classification problem.The results indicate that this new method requires less computing time,and the accuracy of predictions is improved.Moreover,each stage of the proposed strategy possesses definite mathematical explanations so that the strategy could be generalized.

When electrolyzing the KCl zincic plating bath additionally containing acrylamide and N,N′ -methylenebisacrylamide,a composite process of zinc electrodeposition and acrylamide electropolymerization took place on the cathode surface and,as a result,a composite coating of zinc and polyacrylamide was obtained.It is sulggested that polyacrylamide macromolecular chains are distributed in the zincic coating at a molecular level,and this new composite coating is different from common one with solid particles distributed.The performance of composite coating,appearance features,adhesion strength and wetted capability,was studied.

An augmented van der Waals model of VLE of the pure compounds has been established by the molecular thermodynamic method, and an equation of calculating the enthalpy of vaporization at the normal boiling point is obtained from this model, which contains only a molecular size-dependent parameter.It is found that the parameter is directly proportional to the molar volume of liquid at the normal boiling point, and its values have the additivity of groups.The 45 group increments are regressed by 484 organic compounds.The calculation results of the enthalpy of vaporization for these compounds show that the average absolute deviation with the experimental values is 1.39% and is better than other methods published in the literatures.This method can be also used to calculate the enthalpies of vaporization at other temperatures.

A carbonation process was developed to coat Al(OH)₃ on aragonite whisker. Al(OH)₃ coating was obtained in a suspension,which contained 3Cao·Al₂O₃·6H₂O(C₃AH₆)-NaOH prepared by adding Ca(OH)₂ to NaAlO₂ aqueous solution.The CaCO₃ whiskers coated with fine particles of Al(OH)₃ were prepared by blowing CO₂ gas into the suspension.The formed Al(OH)₃ adhered to the CaCO₃ fibers as the substrate.In order to coat α -Al(OH)₃ on aragonite whisker , the pH value of the solution must be higher than 10.5.The formation of C₃AH₆ and complexation of calcium carbonate molecule with C₃A were the domain factors to get single aragonite phase whisker. Micro-analysis demonstrated that the existence of Al(OH)₃ crystal coating on the surface of aragonite-type calcium carbonate whisker.After the coated whiskers were treated strongly in an ultrasonic water bath.Al(OH)₃ still adhered to the CaCO₃ whiskers well.The reaction mechanism was also mentioned in this paper.

By using laser monitoring technique,the solubilities of p -toluic acid in N -methyl-2-pyrrolidone, N,N -dimethylformamide, N,N -dimethylacetamide,chloroform,acetic acid and water are measured in larger temperature intervals by synthetic method.As to the solubility of p -toluic acid in water,the experimental and literature data have satisfactory consistency.Given the solubilities of p -toluic acid, a solubility model is proposed. This model is verified by experimental and literature data, and the solubilities calculated by the model show good agreement with experimental and literature data.

A pendant drop tensiometry apparatus aided by video-image digitization technology was established, by which static interface or surface tension of some liquids was measured with satisfactory results.In order to study the effect of emulsifier concentration on emulsion stability, dynamic interfacial tension was measured between toluene and water against concentration of Tween 60(Polyoxyethylene(20) stearyl-sorbitanate). As expected, higher concentration is the Tween 60 solution in toluene injected into the toluene phase, faster falls the interface tension between toluene and water.Furthermore, it reveals interestingly that two steps of diffusion occur in the system, i.e ., at low and high concentration, after the surfactant solution is injected.The characteristic process of dynamic interface tension can be ascribed to diffusion control because of linearity between interface tension and the minus second root of aging time.The discovery is correlated to the fact that much higher concentration of surfactant above its critical micelle concentration is often required when a stable emulsion is planned to prepare.

The Solvents for extractive distillation to separate ethane/ethylene are studied and screened.Infinite relative volatility and infinite selectivity of 11 solvents with dipole moment from 0 to 11.36 are determined by gas stripping,which draws the conclusion that the selectivity of the solvent increases with its polarity.Two solvents, ACN and DMF, which have higher selectivity,are modified by adding water and salt, respectively.It is found that the effect of separation improves after modification, but the improvement is limited.

Vapor permeation has potential applications in the separation of organic solvent-water mixtures.Adsorption property of organic vapor influences mainly the membrane selectivity in vapor permeation.The adsorption isotherms of water,acetone, methanol, ethanol and isopropanol vapors on γ-Al₂O₃ membrane were measured by methods of dynamic chromatography.The parameters of the relevant Pickett isotherms were calculated.

Knetics and product distributions of cellulose decomposition in near-critical water were studied with a continuous flow-type apparatus for supercritical and near-critical water reactions.The experimental temperature range was from 513K to 583K and residence time from 0.5min to 1.6min.The effects of temperature and residence time on cellulose residue were demonstrated.The apparent actiation energy evaluated was 147kJ·mol ^-1 .In addition,the effects of temperature and residence time on the yield distributions of wter soluble oligomers,glucose and levulose,pyruvic aldehyde,5-hydroxymethyl furfural,furfural were described in detail.The experimental results showed that selective decomposition of cellulose in near critical water was possible.

The paper presents a method of measuring void fraction of steam generator by using optical fiber probes.Comparison is made between void fraction in a vertically upward tube by using optical fiber probes and the void fraction by quick-close valve.A new method of determining threshold is developed for signal processing from a synchronous measurement procedure.An experimental equation by which average void fraction can be obtained though measuring void fraction at axial center of tube.On-line measuring void fraction of steam generator with vertical tube can be achieved by using optical fiber probes.