The complicated reaction system of methanol synthesis from CO ₂ and H ₂ in the reactor with silicone rubber/inorganic composite membrane was studied. In this paper, the effects of silicone rubber/ceramic composite membrane in the process of reaction of oxygen-containing compounds are investigated in detail through experimental work. Part of theoretical results is tested and verified, and the effects of process parameters on reaction behavior are also discussed. In the silicone rubber/ceramic composite membrane, the conversion of the main reaction increases by 22% against traditional fixed bed reaction. Experimental results also show that L _1,opt , the optimal nonuniform parameter of membrane permeation rate does exist.

A mathematical model of ethylene oxide synthesis in three-phase bubble column slurry reactor is presented. It accounts for axial dispersion of liquid phase, settling-dispersion of catalyst and gas-liquid mass transfer. The effects of parameters, such as superficial gas velocity,height of three-phase slurry bed,diameter of reactor and molar fraction of ethylene in the feed syngas on axial distribution of catalyst concentration in the reactor,molar fraction of ethylene oxide in exit gas,selectivity of ethylene oxide and space-time yield were examined. Reasonable design parameters, such as the size of industrial reactor, superficial gas velocity,selectivity of ethylene oxide and space-time yield were predicted and useful information for the design of three-phase bubble column slurry reactor of ethylene oxide synthesis was obtained.

Measurements and modeling of the fundamental properties were performed in two cold-state turbulent bed contactors, TBC, with an inner diameter of 0.1 and 1.0 m and height of 3.0 and 9.0 m respectively. A CFD model was used in numerical computation and scale-up of the countercurrent three-phase fluidized bed reactor for flue gas desulfurization. The pressure drop and radial profiles of local gas holdup and axial liquid velocity in the countercurrent three-phase bubble column were measured and calculated by CFD model. Correlation on the interfacial force, C _w, was found sensitive to the diameter of reactor. The correlation was improved in the modeling of large diameter reactor. Good agreement between experimental and calculated values were found. Some studies on this model and simulation for predicting further the local flow and reaction characteristics of the countercurrent three-phase TBC scrubber with 5.0 m ID are reported in the paper. A model based on penetration theory, physical chemistry properties and dynamical properties of fluid is developed to calculate the dynamic absorption rate of sulfur dioxide in limestone slurry.

By means of visual observation on flow patterns and heat transfer experiments,the flow patterns transitions during flow condensation in small/mini-diameter tubes of 1-5mm,and in turn,the heat transfer mechanisms based on different flow patterns are explored.The results show that,with decreasing tube diameter,the area occupied by annular flow in flow map of inclined tubes increases,that is to say,the flow pattern which is characterized by uniform distribution of condensate film along tube periphery will become dominating.This implies the reducing effect of gravity on flow patterns of two-phase flow in small diameter tubes,the tube wall temperature distribution along periphery becomes more uniform.The corresponding heat transfer experiments also reveal that heat transfer temperature difference has different influences on condensation Nusselt number, Nu ,for different diameter tubes. For example,temperature difference has little effect on Nu for horizontal tube of 1.94mm i.d.,due to the different flow patterns.The present study is helpful to understanding the heat transfer mechanism of flow condensation in small/mini-diameter tubes.

Experimental results on heat transfer characteristics of kerosene at supercritical pressure flowing inside a stainless-steel tube with an internal diameter of 1.70 mm are discussed in this paper. The tests are conducted at pressures of 5,15 MPa, mass velocities of 8500-51000 kg·m ^-2 ·s ^-1 , and heat fluxes up to 55 MW·m ^-2 . Enhancement of heat transfer due to pseudo-boiling is found when wall temperature reaches pseudocritical temperature. Deterioration of heat transfer occurs with wall heat flux increasing. The critical heat flux increases when an additive is added into kerosene. At a very high heat flux secondary enhancement of heat transfer occurs, which could limit the deterioration of heat transfer. A turbulent heat transfer correlation for this kind of heat transfer which fits the data well is given.

Theoretical analyses and experimental studies on flow boiling heat transfer were made in a vapor-liquid-solid three-phase fluidized bed. A heat transfer coefficient correlation incorporating asymptotic model and suface renewal was proposed. In this heat transfer coefficient correlation,total heat transfer between the fluidized bed and wall surface is divided into three parts:convection heat transfer between solid particles and wall surface, convection heat transfer between vapor-liquid two-phase flow and wall and flow nuclei boiling heat transfer with the presence of solid particles. The calculated values agree well with the experimental data.

This paper,taking a continuous heat recovery adsorption air-conditioning system/heat pump as study object,through dynamic analysis on system cycle characteristics,lists a series of dynamic equations about system main components such as adsorber,heat source,condenser,evaporator and so on.In the dynamic equations,variation of heat recovery process for adsorber is considered and a non-balance adsorption equation of adsorber is introduced.In addition,calculation methods of main performance parameters are also given.The work has laid a foundation for further analysis of cycle characteristics and dynamic performances.

By calculation of the system dynamic equations under non-balance adsorption condition, such curves as curve of adsorber temperature vs time, curve of condensing temperature vs time, curve of momentary refrigeration power vs time and p-t-x curve of adsorber are obtained. The calculation models are verified after these curves are compared with experimental data. According to calculation result, influences of some design parameters, which include heat transfer coefficient, mass of heating and cooling medium inside adsorber, specific heat of heat and cooling medium, on p-t-x diagram, SCP and COP are discussed, and the mechanism of the influences is analyzed. In addition,such operating parameters affecting p-t-x diagram as heat source temperature, cooling water temperature and cycle time, are also discussed. The work has laid a foundation for optimum operation and optimum design of a continuous heat recovery adsorption air-conditioning system/heat pump.

A new kind of recurrent neural network structure-state integrated recurrent neural network (SIRNN), which can be used in modeling nonlinear dynamic chemical process systems, is put forward here and the BP algorithm,used in training multi-layer feed-forward neural networks, is used as its learning algorithm. The special recurrent structure of SIRNN, which successfully combines state feed-back, time-series and integrated node together, is different from other recurrent neural networks that it makes the network memorize more past system states and that it keeps the network structure from being too complex. Thereby, SIRNN can be used in modeling high order nonlinear dynamic systems. Input-output models of a second order dynamic nonlinear SISO system using different recurrent neural networks are respectively built and their performance is compared. The result shows that the model using SIRNN performs better than other three recurrent neural networks and also, the SIRNN has higher ability of fault tolerance. This indicates its promising future in the application to true systems. The SIRNN is also used in modeling a MISO CSTR system and its performance is tested. The result shows that after training, the model output can well accord with the output trend of the CSTR system.

In order to monitor, control and optimize the overall chemical process, it is necessary to observe different kinds of variables/parameters. The problem of placing sensors with respect to different criteria, for instance, total cost, system reliability, system accuracy, is known as the problem of sensor network design. This paper studies the problem of non-redundant sensor network design for linear processes. Much research has been done for this problem, but no one of them considered the case that multiple sensors could be used to measure the same variable. Additionally, prior studies neither considered cost, system reliability and system accuracy simultaneously, nor were capable of guaranteeing a global optimal result. In this paper, based on the graph theory concepts, a MILP model is presented for designing the cost-optimal sensor network considering system reliability and system accuracy. The proposed model also consideres the case that multiple sensors could be used to measure the same variable. In order to get a global optimal result, the MILP model is solved by using branch- bound method with the existing software LINGO. The efficiency of the MILP model is demonstrated through an application on the steam-metering network.

In this paper, a multi-objective optimization model that combines the minimization of make span and environmental impact of wastes is proposed for multiproduct batch chemical process scheduling. In this model, environmental impact factors for various wastes and a decision factor are defined for trading off between make span and environmental impact of wastes. An improved SA (Simulated Annealing) algorithm is adopted for solving the problem,and several cases for an example problem are studied.The results show that the proposed model can be used to reflect how the environmental impact consideration affects the scheduling of a multiproduct batch process.

This paper presents a new approach of superstructure mathematical programming combined with total site pinch analysis for utilities and multi-processes optimal synthesis.For the heat integration retrofit,the total site pinch analysis can give the targets of utilities usage and heat recovery,but cannot offer practical designs of optimal network.Based on the total site pinch analysis,a superstructure of utilities heat exchanger network retrofitting can be built which involves only the feasible and better retrofit options.Then an improved Mixed Integer Nonlinear Programming(MINLP)model for the network superstructure is proposed which contains non- convex non-linear objective and constraints.It can be solved with the improved mixed continuous evolutionary algorithm.The presentation has advantages of making use of the results of total site pinch analysis,reducing the scale of superstructure,and having the capability of reaching global optimum.A numerical example of energy integration retrofit in a 300000 t·a ^-1 ethylene plant illustrates that the combined method can reach the total site pinch analysis targets(of minimum utilities usage and maximum steam generation)and can reach global optimum of utilities heat exchanger network.

Mathematical programming approach has been widely used for the systematic synthesis of process flowsheets. In this paper, a new logic and heuristic knowledge based MINLP approach to process synthesis is presented, which makes modeling more easily and systematically. In a typical superstructure, there are three types of unit: equipment, inlet/outlet stream and mixer/splitter. Each equipment is associated with a binary variable y i ( i =1,2,..., N ), and each inlet/outlet stream is also associated with a binary variable z i ( i =1,2,..., M ). The topology of the superstructure can be divided into 4 connection types as follows: 1-1 connection relations, 1- n connection relations, exclusive 1- n connection relations and m-n connection relations. With the logical representations of each relation, the superstructure can be converted to a logic-based MINLP model, which will be solved directly or through its algebraic forms. Operating experiences are expressed in logical forms, so that they can be integrated into the MINLP model as hard-logic or heuristic knowledge. This approach was used in a sample of utility system synthesis, which supplied three types of steam, several types of mechanical energy, electricity and water for a petroleum refinery. The synthesis result was compared with the hierarchical decomposition approach and the traditional mathematical programming approach, which showed that this approach could get better results than hierarchical decomposition. In comparison with the mathematical programming approach, this technique reduced the number of variables and the solving space, so the model size and computing time were decreased.

In this paper, a three-distribution-parameter general model for reactor network synthesis is proposed. The three distribution parameters refer to side feeding, recycling and bypassing.Because they can greatly influence the concentration and residence time profile within the reactors, which make the proposed general model compact and efficient. The synthesis problem can be formulated as an optimization problem based on this general model. By orthogonal collocation on finite element discretization approach, the original model is transformed into a NLP problem. After optimization,the optimal solution of distribution parameters can be obtained. Then the reactor type varying from maximum mixing to minimum mixing and the configuration including series and parallel connection in the reactor network can be directly decided according to the optimal solution of distribution parameters. From the example study, it can be concluded that these three distribution parameters can give a comprehensive reflection of optimal characteristics of reactor network under various reaction kinetics and an objective formulation, and a practical network can be easily obtained from the optimal solutions.

The antagonistic extractions of cadmium and zinc with di(2-ethlhexyl)dithiophosphoric acid (D2EHDTPA)-dioctylamine (DOA) were investigated. The diagram of synergistic extraction showed that the extraction of cadmium and zinc are antagonistic.The extracted complexes were CdA ₂ and ZnA ₂.There were three reactions in the extraction, their contributions to the extraction changed with pH, and the U shaped curve of lg D -pH in the extraction of cadmium could be explained with the three reactions.

By means of a single-tube set-up,the effect of jet flow exciting frequency ( f ) on refrigeration efficiency ( η ) and the influence of some factors,i.e. tube length, expansion rate, heat transfer conditions and discharging at the heat end of the tube,on optimal jet flow exciting frequency are studied experimentally in this paper.The results show that there exists a number of peak value refrigeration efficiency when the exciting frequency is increased.The variation of η due to the change of f can be over 12%.The optimal jet flow exciting frequency is significantly decreased when the tube length is increased, the expansion rate is decreased,the heat transfer condition outside of the tube is improved, or a part of heat gas is discharged at the heat end of the tube.An optimal parameters matching relationship, which can be used to predict the value of the optimal jet flow exciting frequency, is obtained.

The enzymatic limited hydrolysis of soy protein isolate (SPI) by Alcalase 0.6L was carried out with pH-stat method at pH 8.0,50℃.The effects of the main parameters on the degree of hydrolysis, x , were investigated and a model based on the experiment results was deduced.The results showed that the substrate and the enzyme-substrate intermediate induced enzyme inhibition,which occurred due to free enzyme attacking the enzyme-substrate complexes.A critical 0 would correspond to a constant 0,which was 96.77mg·ml ^-1 under the experiment condition.The kinetic parameters calculated from the experiment data were K _m=0.016mol·L ^-1 and V _max =0.765mol·min·L ^-1 .The results showed that x can be regulated to about 6.0 with the mentioned factors in 30min.The good fitness between predicted and measured results confirmed the usefulness of the model.

Based on the kinetics of nitration and oxidation of dinitrotoluene,the steady-state mathematical model is developed for producing trinitrotoluene with o -nitrotoluene in the last-stage nitration process.The industrial process was simulated by using Monte Carlo and Quasi-Newton methods.The kinetic parameters are estimated according to the industrial process data.The results show that trinitrotoluene can be produced with o -nitrotoluene instead of toluene and a higher productivity can be obtained by using the same equipment.The simulation can provide theoretical guidance for innovation of industrial process.

Trimethoxybenzaldehyde (TMB) was hydrogenated over Pd/C in H 2-AcOH,in H 2-MeOH and in NH 2NH 2-PhMe system respectively.In Pd/C-TMB-H 2-AcOH system,TMB was reduced into 3,4,5-trimethoxytoluene (TMT) via 3,4,5-trimethoxybenzyl acetate and (1′-hydroxy)ethyl (3,4,5-trimethoxy)benzyl ether.In Pd/C-TMB-H 2-MeOH system,TMB was reduced into TMT via 3,4,5-trimethoxybenzyl alcohol,methyl(3,4,5-trimethoxy)benzyl ether and bis(3,4,5-trimethoxy)benzyl ether.In Pd/C-TMB-NH 2NH 2-PhMe system,TMB was reduced into TMT directly with mild manner and higher selectivity.

A high-pressure experimental apparatus for asphaltene precipitation is established and then used to determine the amount of asphaltene precipitation in degassed Caoqiao crude oil and recombined Caoqiao reservoir oil under gas (CO ₂ and hydrocarbon gas) injection.The scaling equation for normal pressure n -alkane/asphaltene system is extended to high-pressure gas-injected oil systems and then tested by comparison with the present experimental data and those available in the literature.The results show that it can give good predictions for asphaltene precipitation behavior in high-pressure gas-injected oil systems.

A new approximate concentration profile model for batch adsorption in a spherical adsorbent is proposed.The whole process of batch adsorption is divided into two stages.The first stage is that adsorption front moves from the surface of particle to its center.The second stage is a process in which adsorbate is accumulated in the intraparticle.Both concentration profiles of two stages are assumed to be cubic approximation of sphere radius.Compared with exact solution and other approximate models such as parabolic concentration profile and n -th concentration profile,the new model is closely matched with exact solution and is more accurate than n -th and parabolic models,especially during the initial adsorption period when Biot number is greater.This model can be used in the calculations of complex process of unsteady adsorption of spherical adsorbent.