A model of grade transition is presented for a commercialized fluidized bed gas-phase
polyethyleneproduction process. The quantity of off-specification product and the time of
grade transition can be minimizedby the optimization of operating variables, such as
polymerization temperature, the ratio of hydrogen to ethylene,the ratio of co-monomer to
ethylene, feed rate of catalyst, and bed level. A new performance index, the ratio ofmelt
flow (MFR), is included in the objective function, for restraining the sharp adjustment of
operation variablesand narrowing the distribution of molecular weight of the resin. It is
recommended that catalyst feed rate andbed level are decreased in order to reduce the grade
transition time and the quantity of off-specification product.This optimization problem is
solved by an algorithm of sequential quadratic programming (SQP) in MATLAB.There is
considerable difference between the forward transition and reverse transition of grade with
regard to theoperating variables due to the non-linearity of the system. The grade
transition model is extended to a high spacetime yield (STY) process with the so-called
condensed model operation. In the end, an optimization strategy formulti-product transition
is proposed with two-level optimization of the objective function J(x, u) on the basis
ofthe optimal grade transition model. A sequential transition of six commercial
polyethylene grades is illustrated foran optimal multi-product operation.

An accurate one-dimensional, heterogeneous model taking account of axial dispersion and
heat transferto the reactor wall, and heat conduction through the reactor wall for methanol
synthesis in a bench scale reactorunder periodic reversal of flow direction is presented.
Adjustable parameters in this model are the effectivenessfactors for each of the three
reactions occurring in the synthesis and a factor for the bed to wall heat
transfercoefficient correlation. Experimental data were used to evaluate these parameters
and reasonable values of theseparameters were obtained. The model was found to closely
predict the reactor performance under a wide range ofoperating conditions, such as carbon
oxide concentrations, volumetric flow rate, and cyclic period.

The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and
nitrogen,dispersion of metallic Ru and catalytic activity of active carbon (AC) supported
ruthenium catalyst for ammoniasynthesis have been studied by means of pulse chromatography,
temperature-programmed desorption, and activitytest. Promoters K, Ba and Sm increased the
activity of Ru/AC catalysts for ammonia synthesis significantly, andparticularly, potassium
exhibited the best promotion on the activity because of the strong electronic donation
tometallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or
triple promoters. The activityof Ru/AC catalyst is dependent on the adsorption of hydrogen
and nitrogen. The high activity of catalyst could beascribed to strong dissociation of
nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit theadsorption
of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by
Sm2O3 showsthe best dispersion of metallic Ru, since the partly reduced SmOx on the surface
modifies the morphology of activesites and favors the dispersion of metallic Ru. The
activity of Ru/AC catalysts is in accordance to the correspondingamount of nitrogen
chemisorption and the desorption activation energy of nitrogen. The desorption activation
energyfor nitrogen decreases in the order of Ru＞Ru-Ba＞Ru-Sm＞Ru-Ba-Sm＞Ru-K＞Ru-K-Sm＞Ru
-K-Ba＞Ru-K-Ba-Sm,just opposite to the order of catalytic activity, suggesting that the
ammonia synthesis over Ru-based catalyst iscontrolled by the step of dissociation of
nitrogen.

Wiistite-based catalyst for ammonia synthesis exhibits extremely high activity and easy to
reductionunder a wide range of conditions. The reaction kinetics of ammonia synthesis can
be illustrated perfectly by boththe classical Temkin-Pyzhev and modified Temkin equations
with optimized α of 0.5. The pre-exponent factors andactivation energies at the pressures
of 8.0 and 15.0MPa are respectively ko = 1.09 × 1015, 7.35 × 1014 Pa0.5.s-1,and E =
156.6, 155.5kJ@mol-1 derived from the classical Temkin-Phyzhev equation, as well as ko =
2.45 × 1014,1.83 × 1014pa0.5.s-1, and E = 147.7, 147.2kJ.mol-1 derived from the modified
Temkin equation. Although thedegree of reduction under isothermal condition is primarily
dependent upon temperature, low pressure seems to beimperative for reduction under high
temperature and low space velocity to be considered as a high activity catalyst.The
reduction behavior with dry feed gas can be illustrated perfectly by the shrinking-sphere-
particle model, bywhich the reduction-rate constants of 4248exp (-71680/RT) and 644exp (-
87260/RT) were obtained for the powder(0.045-0.054 mm) and irregular shape (nominal
diameter 3.17 mm) catalysts respectively. The significant effect ofparticle size on
reduction rate was observed, therefore, it is important to take into account the influence
of particlesize on reduction for the optimization of reduction process in industry.

A novel multi-tube photoreactor with 0.0188 m3 valid reaction volume was constructed in
pilot-scale.This rectangular reactor consisted of 13 regularly distributed silica glass
tubes coating with TiO2 thin film photo-catalyst. Total active area of TiO2 thin film is
0.3916m2. The ratio of surface area to volume achieves 20.8m-1.Photocatalytic experiment of
phenol red demonstrates that the apparent reaction rate constant (k) is 0.074 65 h-1and
0.165 02 h-1 for reaction system with and without micro-bubbles mixing. The corresponding
apparent quantumefficiency (φa) is 8.1771 × 10-7 g.J-1 and 4.9036 × 10-7 g.J-1,
respectively. COD value of reactant could decreaseto 17 mg.L-1 and high performance liquid
chromatography (HPLC) only shows two absorption peaks in 24 h pho-tocatalytic process time,
so this photoreactor has good photomineralization effect. Experimental results reveal
thatphotocatalytic destruction of organics is possible by using the multi-tube
photoreactor.

The surface morphology of Ti-Mg supported catalyst and the polyethylene particles are
studied usingscanning electron microscope(SEM) technology. The results show that either the
catalyst’s surface or polymerparticle’s surface is irregular and has fractal
characteristics, which can be described by fractal parameter. The moreinteresting discovery
is that the surface fractal dimension values of the polymer particles vary periodically
with thepolymerization time. We call this phenomenon fractal evolution, which can be
divided into the "revolution" stageand the "evolution" stage. And then we present
polymerization fractal growing model (PFGM), and successfullydescribe and/or predict the
whole evolving process of the polyethylene particle morphology. under the different
slurrypolymerization (including pre-polymerization) conditions without H2.

Experiments for single and bisolute competitive adsorption were carried out to investigate
the adsorptionbehavior ofβ-naphthalenesulfonic acid (NSA) and sulfuric acid from their
solution at 25℃ onto weakly basic resinD301R. Adsorption affinity of sulfuric acid on
D301R was found to be much higher than that of NSA. The dataof single-solute adsorption
were fitted to the Langmuir model and the Freundlich adsorption model. The idealadsorbed
solution theory (IAST) coupled with the single-solute adsorption models were used to
predict the bisolutecompetitive adsorption equilibria. The IAST coupled with the Langmuir
and the Freundlich model for sulfuric acidand NSA, respectively, yields the favorable
representation of the bisolute competitive adsorption behavior.

The experiments of one-stage semi-circular and two-stage semi-circular impinging stream
drying as wellas the vertical and semi-circular combined impinging stream drying were
carried out. The velocity distribution andthe mean residence time of particles, and the
influence of various factors on drying characteristics were studied. Amathematical model of
granular material drying in a semi-circular impinging stream dryer was proposed, in
whichthe flow characteristics as well as the heat and mass transfer mechanisms were
considered. Reasonable numericalmethods were used to solve the equations. Under various
conditions, the calculated results agree well with theexperimental data. The unsteady-state
drying dynamic equation, as well as the variations of drying rate andmoisture content
versus time were obtained. The results indicate that constant drying rate period does not
existin a semi-circular impinging stream dryer. Appropriate semi-circular stage number and
curvature radius, flow-rateratio, air velocity, and higher inlet air temperature should be
used for enhancing the drying process.

An improved generalized predictive control algorithm is presented in this paper by
incorporating offlineidentification into online identification. Unlike the existing
generalized predictive control algorithms, the proposedapproach divides parameters of a
predictive model into the time invariant and time-varying ones, which are
treatedrespectively by offiine and online identification algorithms. Therefore, both the
reliability and accuracy of thepredictive model are improved. Two simulation examples of
control of a fixed bed reactor show that this newalgorithm is not only reliable and stable
in the case of uncertainties and abnormal disturbances, but also adaptableto slow time
varying processes.

Proportion integral differential generalized predictive control(PID-GPC), a new type of
generalizedpredictive control(GPC) is introduced, and its quality is analyzed with internal
model control (IMC). A veryimportant characteristic, which distinguishes GPC from ordinary
IMC, and the robust effect are found. At thesame time, a robust region is obtained
according to the control laws, so that the defect that the robust analysiscould be carried
out only with stable models is overcome. It is verified that the robustness of PID-GPC is
strongerthan general GPC.

The bottleneck analysis of the minimum cost problem for the generalized network (MCPGN) is
dis-cussed. The analysis is based on the network simplex algorithm, which gains negative
cost graphs by constructingaugmented forest structure, then augments flows on the negative
cost graphs until the optimal revolution is gained.Bottleneck structure is presented after
analyzing the augmented forest structure. The negative cost augmentedgraphs are constructed
with the bottleneck structure. The arcs that block the negative cost augmented graph arethe
elements of the bottleneck. The bottleneck analysis for the generalized circulation
problem, the minimum circu-lation problem and the circulation problem are discussed
respectively as the basal problems, then that for MCPGNis achieved. An example is presented
at the end.

Some novel 1: 1 and 1: 2 Fe complex azo dyes were synthesized in this study. The mass
spectrumanalysis of 1:1 and 1:2 Fe complex azo dyes is presented. Lightfastness, rubbing
fastness and washing fastness ofthese metallized complex dyes were evaluated for use on
wool. Results show that these dyes are of good lightfastnessand satisfactory brown shades.

Removal of hydrophobic organic contaminants (HOCs) from soil of low permeability by
electroremedia-tion was investigated by using phenanthrene and kaolinite as a model system.
Tween 80 was added into the purgingsolution in order to enhance the solubility of
phenanthrene. The effects of pH on the adsorption of phenanthreneand Tween 80 on kaolinite
and the magnitude of ζ-potential of kaolinite were examined, respectively. The effects
ofelectric field strength indicated by electric current on the electroremediation behavior,
including the pH of purgingsolution, the conductivity, phenanthrene concentration and flow
rate of effluent, were experimentally investigated,respectively. In case of an electric
field of 25 mA applied for 72 hours, over 90% of phenanthrene was removedfrom 424g (dry
mass) of kaolinite at an energy consumption of 0.148kW@h. The experimental results
described inpresent study show that the addition of surfactant into purging solution
greatly enhances the removal of HOCs byelectroremediation.

This study investigates the heterogeneous structure and its influence on drag coefficient
for concurrent-up gas-solid flow. The energy-minimization multi-scale (EMMS) model is
modified to simulate the variation ofstructure parameters with solids concentration,
showing the tendency for particles to aggregate to form clusters andfor fluid to pass
around clusters. The global drag coefficient is resolved into that for the dense phase, for
the dilutephase and for the so-called inter-phase, all of which can be obtained from their
respective phase-specific structureparameters. The computational results show that the drag
coefficients of the different phases are quite different,and the global drag coefficient
calculated from the EMMS approach is much lower than that from the correlationof Wen and
Yu. The simulation results demonstrate that the EMMS approach can well describe the
heterogeneousflow structure, and is very promising for incorporation into the two-fluid
model or the discrete particle model as theclosure law for drag coefficient.

A novel process for catalytic oxidation of methane to synthesis gas (syngas), which
consists of twoconsecutive fixed-bed reactors with air introduced into the reactors,
integrated Fischer-Tropsch synthesis, was inves-tigated. At the same time, a catalytic
combustion technology has been investigated for utilizing the F-T offgas togenerate heat or
power energy. The results show that the two-stage fixed reactor process keep away from
explosionof CH4/O2. The integrated process is fitted to produce diesel oil and lubricating
oil in remote gas field.

An experimental system was setup to study the pressure field of unconfined vapor cloud
explosions.The semi-spherical vapor clouds were formed by slotted 0.02 mm polyethylene
film. In the center of the cloudwas an ignition electrode that met ISO6164 "Explosion
Protection System" and NFPA68 "Guide for Venting ofDeflagrations". A data-acquisition
system, with dynamic responding time less than 0.001 s with 0.5% accuracy,recorded the
pressure-time diagram of acetylene-air mixture explosion with stoichiometrical ratio. The
initial clouddiameters varied from 60cm to 300cm. Based on the analysis of experimental
data, the quantitative relationshipis obtained for the cloud explosion pressure, the cloud
radius and the distance from ignition point. Present resultsprovide a useful way to
evaluate the building damage caused by unconfined vapor cloud explosions and to
determinethe indispensable explosion grade in the application of multi-energy model.

In this work a system which consists of chitosan microcores entrapped in ethylcellulose is
presented.Vitamin D2 was efficiently entrapped in chitosan microcores with spray-drying
method and was microencapsulatedby coating of ethylcellulose. The average size of chitosan
microspheres was 6.06 μm. The morphology and releaseproperties of microcapsules were
tested. The results of release in vitro showed that the microcapsule could realizesustained
release for 12 h in artificial intestinal juice.

The fluid flow and oil-water separation were simulated using a Reynolds stress transport
equationmodel of turbulence in water flow and a stochastic model of oil droplet motion.
Simulation results give the axialand tangential velocity components, the pressure and
turbulence intensity distribution and droplet trajectories fora hydrocyclone of F type and
a hydrocyclone proposed by the present authors. The flow field predictions are
inqualitative agreement with the LDV measurements. The results show that the proposed
hydrocyclone has betterperformance than the hydrocyclone of F type due to creating stronger
centrifugal force and lower axial velocity.

Destruction of industrial waste in cement rotary kilns (CRKs) is an alternative technology
for thetreatment of certain types of industrial waste (IW). In this paper, three typical
types of industrial wastes wereco-incinerated in the CRK at Beijing Cement Plant to
determine the effects of waste disposal (especially solid wastedisposal) on the quality of
clinker and the concentration of pollutants in air emission. Experimental results showthat
(1) waste disposal does not affect the quality of clinker and fly ash, and fly ash after
the IW disposal can still beused in the cement production, (2) heavy metals from IW are
immobilized and stabilized in the clinker and cement,and (3) concentration of pollutants in
air emission is far below than the permitted values in the China NationalStandard-Air
Pollutants Emission Standard (GB 16297-1996).

Liquid phase axial mixing was measured with the tracer technique in a packed column with
innerdiameter of 0.15 m, in which the structured packing, Mellapak 350Y, was installed. Tap
water as the liquid phaseflowed down through the column and stagnant gas was at elevated
pressure ranging from atmospheric to 2.0 MPa.The model parameters of Bo andθ were
estimated with the least square method in the time domain. As liquid flowrate was
increased, the liquid axial mixing decreased. Under our experimental conditions, the effect
of pressure onBo number on single liquid phase was negligible, and eddy diffusion was
believed to be the primary cause of axialmixing in liquid phase.

Monte Carlo method is applied to investigate the kinetics of ammonia oxidative
decomposition overthe commercial propylene ammoxidation catalyst(Mo-Bi). The simulation is
quite in agreement with experimentalresults. Monte Carlo simulation proves that the process
of ammonia oxidation decomposition is a two-step reaction.

An experimental study of vertical gas conveying of Geldart-D powder as a dilute phase is
performed ina pipe of length 22 m and internal diameter 0.05 m using a fluidized blow tank
at gas velocity ranging from 5 m.s-1to 13m.s-1 and loading ratio up to about 30. The
characteristics of gas conveying, such as pressure drop, thechoking velocity and the
minimum primary velocity of the fluidized blow tank, are discussed in detail.