Chinese Journal of Chemical Engineering

Two-Phase Flow Characteristics in a Coalescence-Dispersion Pulsed-Sieve-Plate Extraction
Column

TANG Xiaojin, LUO Guangsheng, LI Hongbo, WANG Jiading

2004, 12(1): 1-6. doi:

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A study on two-phase flow characteristics in a coalescence-dispersion pulsed-sieve-plate
extraction column of 150mm in diameter was carried out with a working system of 30% tri-
butyl-phosphate (TBP) (in kerosene)nitric acid-water. The influence of operation conditions
on the holdup of the dispersed phase was investigated.According to the analysis of the
experimental data, there was a turning point on the curve of ln(Vs) versus ln(1-φ)under
certain pulse intensity. When the holdup is higher than the value at the turning point, the
two-phase flow characteristics can be described with the modified Pratt’s equation,
otherwise a new relation in the form of φ =1/2.75uk (uc + 4ud) may be used, which is
proposed by this study.

Experimental Research on Flow Maldistribution in Plate-Fin Heat Exchangers

ZHANG Zhe, LI Yanzhong, XU Qing

2004, 12(1): 7-13. doi:

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The flow maldistribution and the effect of different inlet configuration on the flow
distribution in platefin heat exchangers were studied experimentally. It is found that the
flow maldistribution is serious because of the defects of inlet configurations, while the
inlet configuration and Reynolds number are the main factors affecting the flow
distribution. The improved inlet configurations, which are the header with a two-stage
distributing configuration and the guide vane with a fluid complementary cavity were
proposed and tested in this paper. The experimental results show that the improved inlet
configurations can effectively improve the performance of flow distribution in heat
exchangers.

Simulation of the Internal Transport Phenomena for PEM Fuel Cells with Different Modes of
Flow

HU Mingruo, ZHU Xinjian, GU Anzhong

2004, 12(1): 14-26. doi:

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A numerical model for proton exchange membrane (PEM) fuel cell is developed, which can
simulate such basic transport phenomena as gas-liquid two-phase flow in a working fuel
cell. Boundary conditions for both the conventional and the interdigitated modes of flow
are presented on a three-dimensional basis. Numerical techniques for this model are
discussed in detail. Validation shows good agreement between simulating results and
experimental data. Furthermore, internal transport phenomena are discussed and compared for
PEM fuel cells with conventional and interdigitated flows. It is found that the dead-ended
structure of an interdigitated flow does increase the oxygen mass fraction and decrease the
liquid water saturation in the gas diffusion layer as compared to the conventional mode of
flow. However, the cathode humidification is important for an interdigitated flow to
acquire better performance than a conventional flow fuel cell.

The Simulations of Annulus-Core Structure in CFB

OUYANG Jie, LI Jinghai, SUN Guogang

2004, 12(1): 27-32. doi:

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In this paper, the stochastic particle-trajectory model is proposed for simulating the
dynamic behavior of circulating fluidized bed (CFB). In our model, the motion of solid
phase is obtained by calculating the individual particle trajectory while gas flow is
obtained by solving the Navier-Stokes Equation including two-phase interaction.For the
calculation of solid phase, the motion of each particle is decomposed into a collision
process and a suspension process. In suspension process, the less important and/or unclear
forces are described as a random force considering gravity, drag force and pressure
gradient. As a result, the proposed model gives some numerical simulations of CFB.It
indicates that the stochastic particle-trajectory model can be used to simulate
qualitatively the annulus-core structure of CFB and the influences of stochastic factors
cannot be ignored. In a CFB, the coupling of stochastic factors between two phases makes
the radial voidage decreased. Moreover, the upward motion of particles is mitigated by both
stochastic factors and turbulence between two phases.

Analysis of the Medium Resistance for Constant Pressure Filtration

WU Yanxiang, WANG Biyu

2004, 12(1): 33-36. doi:

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A mathematical model for constant pressure filtration is established. The distribution of
hydraulic pressure within the cake and the medium resistance are measured. The medium
resistance Rm is calculated from the suppositional filtration time θm. It is demonstrated
that Rm is nearly a constant for a given filter cloth.

Properties of Bentonite Enhanced Loess and Laterite

LIU Yangsheng, BAI Qingzhong, NIE Yongfeng

2004, 12(1): 37-41. doi:

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Loess and laterite distributed widely in the northern and southern China cannot be directly
used as the natural barrier to isolate the solid waste because of their high hydraulic
conductivity. In this paper, they are enhanced by bentonite to improve their hydraulic
performance. The impact of bentonite content and water content on compressive strength of
the compacted soil was investigated. The effects of bentonite content, water content,dry
density and hydraulic graiient on the hydraulic conductivity were studied in detail. For
the laterite and the laterite with 8% of bentonite, the experimental results of hydraulic
conductivity can be applied in the engineering design. However, for the loess and the
bentonite enhanced loess, those of hydraulic conductivity can not be directly applied in
the engineering design because their hydraulic performance does not comply with the Darcy’s
law. These experimental results have to be carefully modified before application.

Two Types of Novel Feedstock Injection Structures of the FCC Riser Reactor

FAN Yiping, CAI Feipeng, SHI Mingxian, XU Chunming

2004, 12(1): 42-48. doi:

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Based on the analysis of flow characteristics of the FCC riser feedstock injection zone,
two novel feedstock injection structures are put forward. By investigating three flow
parameters in the feedstock injection zone under the three different structures (the
traditional and the novel No. 1, No. 2 structures): the local density, the particle
backmixng ratio, and the jet eigen-concentration, the flow feature under three structures
were obtained. The experimental results demonstrate that the flow features under both
proposed structures are obviously improved comparing with those under the traditional
structure. Especially, the performance of the deflector-structured No. 2is more desirable
than that of No. 1.

Estimation of Kinetic Parameters for Autocatalytic Oxidation of Cyclohexane Based on a
Modified Adaptive Genetic Algorithm

LIU Pingle, ZOU Lishan, LUO He'an, WANG Liangjie, ZHENG Jinhua

2004, 12(1): 49-54. doi:

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A modified genetic algorithm of multiple selection strategies, crossover strategies and
adaptive operator is constructed, and it is used to estimate the kinetic parameters in
autocatalytic oxidation of cyclohexane. The influences of selection strategy, crossover
strategy and mutation strategy on algorithm performance are discussed.This algorithm with a
specially designed adaptive operator avoids the problem of local optimum usually associated
with using standard genetic algorithm and simplex method. The kinetic parameters obtained
from the modified genetic algorithm are credible and the calculation results using these
parameters agree well with experimental data.Furthermore, a new kinetic model of
cyclohexane autocatalytic oxidation is established and the kinetic parameters are estimated
by using the modified genetic algorithm.

Hydrodynamic Behaviour of a Gas-Solid Air-loop Stripper

LIU Mengxi, LU Chunxi, SHI Mingxian

2004, 12(1): 55-59. doi:

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In this paper, the principles of airlift loop reactor in gas-liquid and gas-liquid-solid
systems are extended to gas-solid system. The models on bed average voidage in draft tube
and the particle circulation velocity in a gas-solid loop reactor are deduced. The
experiments are also conducted on a φ600mm×7000mm reactor. The catalyst voidage and
catalyst circulation velocity are measured at different radial and axial positions in draft
tube and annulus, respectively. The experimental data are analyzed systemically and
represented satisfactorily by the proposed models.

Active Fault Tolerant Control of a Class of Nonlinear Time-Delay Processes

WANG Dong, ZHOU Donghua, JIN Yihui

2004, 12(1): 60-65. doi:

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Based on a nonlinear state predictor (NSP) and a strong tracking filter (STF), a sensor
fault tolerant generic model control (FTGMC) approach for a class of nonlinear time-delay
processes is proposed. First, the NSP is introduced, and it is used to extend the
conventional generic model control (GMC) to nonlinear processes with large input time-
delay. Then the STF is adopted to estimate process states and sensor bias, the estimated
sensor bias is used to drive a fault detection logic. When a sensor fault is detected, the
estimated process states by the STF will be used to construct the process output to form a
"soft sensor", which is then used by the NSP (instead of the real outputs) to provide state
predictors. These procedures constitute an active fault tolerant control scheme. Finally,
simulation results of a three-tank-system demonstrate the effectiveness of the proposed
approach.

Study on Multi-stream Heat Exchanger Network Synthesis with Parallel Genetic/Simulated
Annealing Algorithm

WEI Guanfeng, YAO Pingjing, LUO xing, ROETZEL Wilfried

2004, 12(1): 66-77. doi:

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The multi-stream heat exchanger network synthesis (HENS) problem can be formulated as a
mixed integer nonlinear programming model according to Yee et al. Its nonconvexity nature
leads to existence of more than one optimum and computational difficulty for traditional
algorithms to find the global optimum. Compared with deterministic algorithms, evolutionary
computation provides a promising approach to tackle this problem. In this paper, a
mathematical model of multi-stream heat exchangers network synthesis problem is setup.
Different from the assumption of isothermal mixing of stream splits and thus linearity
constraints of Yee et al., non-isothermal mixing is supported. As a consequence, nonlinear
constraints are resulted and nonconvexity of the objective function is added.To solve the
mathematical model, an algorithm named GA/SA (parallel genetic/simulated annealing
algorithm) is detailed for application to the multi-stream heat exchanger network synthesis
problem. The performance of the proposed approach is demonstrated with three examples and
the obtained solutions indicate the presented approach is effective for multi-stream HENS.

Hierarchical On-line Scheduling of Multiproduct Batch Plants with a Combined Approach of Mathematical Programming and Genetic Algorithm

CHEN Li, WANG Kefeng, XU Xiaoyu, YAO Pingjing

2004, 12(1): 78-84. doi:

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In this contribution we present an online scheduling algorithm for a real world
multiproduct batch plant.The overall mixed integer nonlinear programming (MINLP) problem is
hierarchically structured into a mixed integer linear programming (MILP) problem first and
then a reduced dimensional MINLP problem, which are optimized by mathematical programming
(MP) and genetic algorithm (GA) respectively. The basis idea relies on combining MP with GA
to exploit their complementary capacity. The key features of the hierarchical model are
explained and illustrated with some real world cases from the multiproduct batch plants.

A New Model for Prediction of Surface Tension of Pure Fluids

YANG Chunsheng, ZHONG Chongli

2004, 12(1): 85-91. doi:

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A new model based on the theoretical work of Boudh-Hir and Mansoori was developed for
prediction of surface tension of pure fluids. The new model has the advantage of not
requiring densities in the calculation, and the input parameters are critical temperature
and connectivity indices. A total of 209 compounds covering a wide variety of substances
were used to develop the model, and the overall correlative AAD is 4.21%. To test its
predictive ability, the model is further used to predict the surface tension of 25 more
compounds that were not included in the model development. The overall predictive AAD is
4.07%, which illustrates that the model is reliable. The model proposed is simple and easy
to apply, with good predictive accuracy.

Isothermal and Isobaric Vapor-Liquid Equilibria of α-Pinene+cis-Pinane+1-Hexanol
System

MA Lu, LI Haoran, WANG Congmin, HAN Shijun

2004, 12(1): 92-95. doi:

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This paper presents the isothermal and isobaric vapor-liquid equilibria measured with an
inclined ebulliometer for α-pinene + cis-pinane + 1-hexanol system at temperatures of
368.15K, 383.15 K and 408.15K, and at pressures of 26.66 kPa and 53.33 kPa. The measured
ternary results are analyzed using the UNIQUAC equation with the temperature-dependent
binary parameters. Satisfactory agreements are obtained between the experimental results
and the theoretical analysis.

An Improved Adaptive Multi-way Principal Component Analysis for Monitoring Streptomycin
Fermentation Process

HE Ning, WANG Shuqing, XIE Lei

2004, 12(1): 96-101. doi:

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Multi-way principal component analysis (MPCA) had been successfully applied to monitoring
the batch and semi-batch process in most chemical industry. An improved MPCA approach,
step-by-step adaptive MPCA (SAMPCA), using the process variable trajectories to monitoring
the batch process is presented in this paper. It does not need to estimate or fill in the
unknown part of the process variable trajectory deviation from the current time until the
end. The approach is based on a MPCA method that processes the data in a sequential and
adaptive manner. The adaptive rate is easily controlled through a forgetting factor that
controls the weight of past data in a summation. This algorithm is used to evaluate the
industrial streptomycin fermentation process data and is compared with the traditional
MPCA. The results show that the method is more advantageous than MPCA,especially when
monitoring multi-stage batch process where the latent vector structure can change at
several points during the batch.

Production of Validamycins from Crude Substrates by Streptomyces hygroscopicus in an
External-loop Airlift Bioreactor with a Low Height-to-Diameter Ratio

ZHENG Yuguo, CHEN Xiaolong, WANG Zhao, SHEN Yinchu

2004, 12(1): 102-107. doi:

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Fermentation experiments to produce validamycins from crude substrates by Streptomyces
hygroscopicus were carried out in an external-loop airlift bioreactor (0.0115 m3 ) with a
low ratio of height to diameter of the riser of 2.9 and a ratio of riser to downcomer
diameter of 6.6. The influences of gas flow rate and liquid volume on fermentation of
validamycins were investigated. Comparisons of validamycin fermentation were made among the
external-loop airlift bioreactor, a mechanically stirred tank bioreactor (0.010m3 ) and
shaking flasks. Under the same operation conditions including fermentation medium
composition, inoculum ratio and culture temperature,the fermentation time in the external-
loop airlift bioreactor (45 h) was shorter than that in the shaking flasks (100 h)and the
same as that in the mechanically stirred tank bioreactor. After a total fermentation time
of 45 h under optimized operation conditions, average validamycin concentration obtained in
the external-loop airlift bioreactor was close to 19630μg.m1-1 validamycin concentration
in the mechanically stirred tank bioreactor. It was demonstrated that the external-loop
airlift bioreactor could substitute for the mechanically stirred tank bioreactor in
production of validamycins from crude substrates with dregs by Streptomyces hygroscopicus.

Preliminary Study on the Performance and Interaction of Recycling Hydrolytic-Aerobic
Combined Process of High Concentration Starch Wastewater

LI Qingbiao, LIAO Xinkai, WU Zhiwang, DENG Xu, HUANG Yili, LU Yinghua, SUN Daohua, HONG Mingyuan, WANG Lin

2004, 12(1): 108-112. doi:

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A new recycling hydrolytic-aerobic combined process was developed to treat the high
concentration used. At first, the hydrolytic degradation and aerobic degradation process
were examined in two batch reactors,respectively. In the stand-alone hydrolytic process,
starch in the wastewater almost disappeared after 11 h treatment,but CODCr remained as high
as 5803mg. L-1 after two days. In the aerobic process, the biodegradation rate of starch
was much slower during the first 11 h than that in the hydrolytic process, although the
CODCr removal efficiency reached 89.6% and more than 90% starch could be degraded after
37.5 h. To determine the interaction effects of the two processes, a series of hydrolytic-
aerobic combinations were examined in details. Hydrolytic process played an important role
in the whole recycle combination process as it could improve the biodegradability of the
high concentration starch wastewater. However, from the other experiments, the negative
effect of hydrolytic acidification was found in the hydrolytic-aerobic combination, which
suggested that the aerobic microorganisms needed time to adapt themselves to the acidic
environment. The effect of the degrading time, which was spent in the hydrolytic and
aerobic unit, and the number of circulations, with which the wastewater went through the
two units were investigated. It was found that a recycle combination of 6 h hydrolytic
process with 12 h aerobic process was highly effective and potentially economical, in which
the final removal efficiency of CODCr and efficiency of starch degradation reached 94.1%
and 98.8%, respectively.

Autotrophic Biofilters for Oxidation of Nitric Oxide

CHEN Jianmeng, CHEN Jun, Lance Hershman, WANG Jiade, Daniel P.Y.Chang

2004, 12(1): 113-117. doi:

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Carbon foam-a kind of new engineering material as packing material was adopted in three
biofilters with different pore dimensions and adapted autotrophic nitrite nitrobacteria to
investigate the purification of nitric oxide (NO) in a gas stream. The biofilm was
developed on the surface of carbon foams using nitrite as its only nitric source. The
moisture in the filter was maintained by ultrasonic aerosol equipment which can minimize
the thickness of the liquid film. The liquid phase nitrification test was conducted to
determine the variability and the potential of performance among the three carbon foam
biofilters. The investigation showed that during the NO-2-N inlet concentration of 200 g-L
-1 .min-1 to 800 g-L-1 .min-1, the 24PPC (pores per centimeter) carbon foam biofilter had
the greatest potential, achieving the NO-2-N removal efficiency of 94% to 98%. The 8PPC and
18PPC carbon foam biofilters achieved the NO-2-N removal efficiency of 15% to 21% and of
30% to 40%, respectively. The potential for this system to remove NO from a gas stream was
shown on the basis of a steady removal efficiency of 41% to 50% which was attained for the
24PPC carbon foam biofilter at specified NO inlet concentration of 66.97mg.m-3to 267.86
mg.m-3 and an empty-bed residence time of 3.5 min.

Process Development and Design of Chlorine Dioxide Production Based on Hydrogen Peroxide

CHEN Yun, JIANG Yanbin, QIAN Yu

2004, 12(1): 118-123. doi:

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This paper presents a process development and design of chlorine dioxide production based
on hydrogen peroxide. The process is characterized by cleaner production, high efficiency,
and waste minimization. Optimization of process conditions, selection of equipment, and
experiment of recycle of waste acid are carried out. The process design is realized in
consideration of several aspects such as operation, material, equipment design and safety.
An industrialized process flowsheet is developed according to experiment. A pilot testing
is carried out to confirm the lab results. Process design of chlorine dioxide production
based on hydrogen peroxide is realized.

Studies on Spinel LiMn2O4 Cathode Material Synthesized from Different Mn Sources

TANG Zhiyuan, FENG Jijun, PENG Yaning

2004, 12(1): 124-127. doi:

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The spinel LiMn2O4 cathode material was synthesized with the solid-state reaction method.
Four manganese compounds including electrolytic manganese dioxide (EMD), MnCO3, Mn3O4 and
nano-EMD were used as Mn sources while LiOH.H2O was used as the uniform Li source. The
crystal structure characteristics of these samples produced were investigated by means of
XRD, SEM, particle size distribution analysis and specific surface area testing. Their
electrochemical properties were also studied by comparing their specific capacity, charge
and discharge efficiency and cycle performance.

The Study of Dissolution Kinetics of K2SO4 Crystal in Aqueous Ethanol Solutions with a
Statistical Rate Theory

LIU Chang, FENG Xin, JI Xiaoyan, CHEN Dongliang, WEI Tao, LU Xiaohua

2004, 12(1): 128-130. doi:

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Dissolution kinetics of K2SO4 crystal in aqueous ethanol solutions was studied on-line with
ion selective electrode. The concentration of K2SO4 was calculated from the determined
electromotive force in which the activity coefficient of components in the liquid phase was
calculated with the Pitzer equation. Dissolution kinetic parameters in the modified
statistical rate theory were regressed. The correlation results show that dissolution rate
of K2SO4 is slower in aqueous ethanol solutions than that in aqueous solutions. The two
most important reasons are as follows:(1) The solubility of K2SO4 in aqueous ethanol
solutions is lower than that in aqueous solutions, which causes a decrease of the driving
force of mass transfer. (2) The process of surface reaction of K2SO4 became slower due to
the addition of ethanol, so that the whole process is mainly dominated by the surface
reaction instead of mass transfer.

Kinetics of Conversion of Methane with Electric Field Enhanced Plasma

WANG Baowei, XU Genhui, SUN Hongwei

2004, 12(1): 131-133. doi:

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Methane conversion was studied with electric field enhanced plasma (EFEP) technique at the
atmosphere pressure and low temperature ranging from 323 K to 373 K. The conversion of
methane is up to 60%-80%.The kinetics of methane conversion was studied using microreactor.
The reaction model of power function type was obtained as: r = 90.99exp (-26980/RT)C0.226A
(mol.m-3.s-1). The global kinetics parameters were calculated by the variable simple-pure
shape method. The calculating results are in good agreement with experimental data.

Calculation of H₂O-NH₃-CO₂ Vapor Liquid Equilibria at High Concentration Conditions

WEI Shun'an, ZHANG Hongjing

2004, 12(1): 134-136. doi:

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A vapor liquid equilibrium model and its related interactive energy parameters based on
UNIQUAC model for the H2O-NH3-CO2 system without solid phase at the conditions of
temperature from 30℃ to 90℃,pressure from 0.1 MPa to 0.4 MPa, and the maximum NH3 mass
fraction up to 0.4 are provided. This model agrees with experimental data well (average
relative error ＜ 1%) and is useful for analysis of industrial urea production.

Extraction Behavior and Wastewater Treatment of Amino Sulfonic Acid with Alamine 336

QIN Wei, LI Zhenyu, WANG Min, DAI Youyuan

2004, 12(1): 137-142. doi:

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p-Amino benzene sulfonic acid (PABSA) is selected as the solute with amphoteric functional
group,Lewis acid and Lewis base, to be separated from its dilute solutions. An aliphatic,
straight chain amine, Alamine 336, is used as the extractant, and kerosene, 1-octanol,
chloroform, butyl acetate and benzene as the diluent. The effects of pH value of solution,
extractant concentration, salt and types of diluent on the distribution coefficient, D,are
studied. There is a peak of D value with pH value of solution, the polar diluents are
favorable for extracting PABSA, and the salt in aqueous phase reduces values of D
apparently. The extraction equilibrium is described using the mass action law, and the
calculated data according to the proposed model agree with the experimental data well.
Further, the extraction behavior for other amino benzene sulfonic acids, 1-amino-8-naphtol
-3,6-disulfonic acid (H acid) and 4,4′-diaminostilbene-2,2′Cdisulfonic acid (DSD acid),
is investigated in a wide pH value region.Finally, H acid and DSD acid are successfully
removed from wastewater by the extraction with Alamine 336.

Effect of Diluents on the Extraction of Oxalic Acid by Trialkylphosphine Oxide

LI Yuxin, WANG Yundong, DAI Youyuan

2004, 12(1): 137-148. doi:

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In liquid-liquid solvent extraction processes, diluents have a strong influence on the
extraction mechanism and efficiency. In this study, benzene, cyclohexane, trichloromethane,
carbon tetrachloride, methyl isobutyl ketone (MIBK), butyl acetate, and 1-octanol were used
as diluents in the extraction of oxalic acid by trialkylphosphine oxide (TRPO). The effects
of extractant concentration, initial concentration of oxalic acid and diluent type on the
extraction equilibrium partition coefficient are analyzed. The sequence of the extraction
ability by different diluents is MIBK ＞ butyl acetate ＞ cyclohexane=benzene ＞ carbon
tetrachloride ＞ 1-octanol ＞ trichloromethane.Extraction mechanism was analyzed and
extraction model parameters were evaluated.

Investigation on Methane Decomposition and the Formation of C₂ Hydrocarbons in DC Discharge
Plasma by Emission Spectroscopy

HE Jianxun, HAN Yuanyuan, GAO Aihua, ZHOU Yinsui, LU Zhiguo

2004, 12(1): 149-151. doi:

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The IR emission spectra of methane were measured under DC glow discharge conditions. The
distinct difference in time between methane decomposition and C2 hydrocarbons formation was
specially pointed out. C2hydrocarbons formed at the end of methane decomposition. The
optimum condition for C2 hydrocarbon formation was studied and the optimum combination
between electric current density and methane input quantity was suggested. The appropriate
reaction conditions for methane decomposition and C2 hydrocarbons formation are different,
so high yield of C2 hydrocarbons will be probably obtained when different conditions are
taken.

Studies on Catalytic Pyrolysis of Daqing Atmospheric Residue

MENG Xianghai, XU Chunming, ZHANG Qian, GAO Jinsen

2004, 12(1): 152-155. doi:

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Catalytic pyrolysis of Daqing atmospheric residue on catalyst CEP-1 was investigated in a
confined fluidized bed reactor. The results show that reaction temperature, the mass ratios
of catalyst to oil and steam to oil have significant effects on product distribution and
yields of light olefins. The yields of light olefins show the maxima with the increase of
reaction temperature, the mass ratios of catalyst to oil and steam to oil, respectively.The
optimized operating conditions were determined in the laboratory, and under that condition
the yields of ethylene, propylene and total light olefins by mass were 15.9%, 20.7% and
44.3% respectively. The analysis of pyrolysis gas and pyrolysis liquid indicates that CEP-1
has good capacity of converting heavy oils into light olefins,and there is a large amount
of aromatics in pyrolysis liquid.

Kinetics of Bulk Polymerization of Octamethylcyclotetrasiloxane

FANG Xin, CHEN Zhirong, YIN Hong, SU Kefeng

2004, 12(1): 156-158. doi:

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The kinetics of bulk polymerization of octamethylcyclotetrasiloxane under acid circumstance
is studied.A kinetic model is put forward and kinetic parameters are obtained through
optimization.