Abstract: Prediction of benzene transport in soil and volatilization from soil to the atmosphere is important for the preservation of human health and management of contaminated soils. The adequacy of a simple numerical model, assuming two-phase diffusion and equilibrium of liquid/solid adsorption, was investigated by experimental data of benzene concentration in a flux chamber (with headspace) where Andosol and sand were filled. Adsorption experiment for liquid phase was performed to determine an adsorption coefficient. Furthermore, adequacy of vapor phase adsorption was also studied through two runs of experiment using sand with different water content. The results show that the model adequately predicted benzene transport and volatilization from Andosol and sand with water content of 14.0%. In addition, the experiment additionally revealed that vapor phase adsorption should be considered in diffusion model for sand with very low water content.
Abstract: This paper describes a one-dimensional numerical model for natural gas production from the dissociation of methane hydrate in hydrate-capped gas reservoir under depressurization and thermal stimulation. Some of the hydrate reservoirs discovered are overlying a free-gas layer, known as hydrate-capped gas reservoirs. These reservoirs are thought to be easiest and probably the first type of hydrate reservoirs to be produced. The mathematical equations that can be described this type of reservoir include mass balance, heat balance and kinetics of hydrate decomposition. These non-linear partial differential equations are solved using finite-difference fully implicit scheme. In the model, the effect of convection and conduction heat transfer, variation change of formation porosity, the effect of using different equations of state such as PR and ER and steam or hot water injection are considered. In addition distributions of pressure, temperature, saturation of gas, hydrate and water in the reservoir are evaluated. It is shown that the gas production rate is a sensitive function of well pressure.
Abstract: A kinetic model for propane dehydrogenation in an
industrial moving bed reactor is developed based on the reported
reaction scheme. The kinetic parameters and activity constant are
fine tuned with several sets of balanced plant data. Plant data at
different operating conditions is applied to validate the model and
the results show a good agreement between the model
predictions and plant observations in terms of the amount of main
product, propylene produced. The simulation analysis of key
variables such as inlet temperature of each reactor (Tinrx) and
hydrogen to total hydrocarbon ratio (H2/THC) affecting process
performance is performed to identify the operating condition to
maximize the production of propylene. Within the range of operating
conditions applied in the present studies, the operating condition to
maximize the propylene production at the same weighted average
inlet temperature (WAIT) is ΔTinrx1= -2, ΔTinrx2= +1, ΔTinrx3= +1 ,
ΔTinrx4= +2 and ΔH2/THC= -0.02. Under this condition, the surplus
propylene produced is 7.07 tons/day as compared with base case.
Abstract: In this work, the precipitation of asphaltene from a Malaysian light oil reservoir was studies. A series of experiments were designed and carried out to examine the effect of CO2 injection on asphaltene precipitation. Different pressures of injections were used in Dynamic flooding experiment in order to investigate the effect of pressure versus injection pore volume of CO2. These dynamic displacement tests simulate reservoir condition. Results show that by increasing the pore volume of injected gas asphaltene precipitation will increases, also rise in injection pressure causes less precipitation. Sandstone core plug was used to represent reservoir formation during displacement test; therefore it made it possible to study the effect of present of asphaltene on formation. It is found out that the precipitated asphaltene can reduce permeability and porosity which is not favorable during oil production.
Abstract: An artificial neural network (ANN) model is
presented for the prediction of kinematic viscosity of binary mixtures
of poly (ethylene glycol) (PEG) in water as a function of temperature,
number-average molecular weight and mass fraction. Kinematic
viscosities data of aqueous solutions for PEG (0.55419×10-6 –
9.875×10-6 m2/s) were obtained from the literature for a wide range
of temperatures (277.15 - 338.15 K), number-average molecular
weight (200 -10000), and mass fraction (0.0 – 1.0). A three layer
feed-forward artificial neural network was employed. This model
predicts the kinematic viscosity with a mean square error (MSE) of
0.281 and the coefficient of determination (R2) of 0.983. The results
show that the kinematic viscosity of binary mixture of PEG in water
could be successfully predicted using an artificial neural network
model.
Abstract: Natural gas is defined as gas obtained from a natural underground reservoir. It generally contains a large quantity of methane along with heavier hydrocarbons such as ethane, propane, isobutene, normal butane; also in the raw state it often contains a considerable amount of non hydrocarbons, such as nitrogen and the acid gases (carbon dioxide and hydrogen sulfide). The acid gases must be removed from natural gas before use. One of the processes witch are use in the industry to remove the acid gases from natural gas is the use of alkanolamine process. In this present paper, a simulation study for an industrial gas sweetening plant has been investigated. The aim of the study is to investigate the effect of using mixing amines as solvent on the gas treatment process using the software Hysys.
Abstract: In this study, production possibilities of hydrogen and/or methane via SCWG from black grape residues have been investigated. For this aim, grape residues which remain as a byproduct of the wine making process have been used. Since utilization from grape residues is limited due to the high moisture content, supercritical water gasification is the most convenient method. The effect of the gasification temperature and type of catalyst on supercritical water gasification have been investigated. Gasification experiments were performed in a batch autoclave at four different temperatures 300, 400, 500 and 600°C. K2CO3 and Trona (NaHCO3.Na2CO3·2H2O) were used as catalyst. Real biomass types of black grape residues have been successfully gasified and the product gas (hydrogen, methane, carbon dioxide, carbon monoxide and a small amount of ethane and ethylene) were identified by using gas chromatography. A TOC analyzer was used to determine total organic carbon (TOC) content of aqueous phase. The amounts of carboxylic acids, aldehydes, ketones, furfurals and phenols present in the aqueous solutions were analyzed by high performance liquid chromatography. When the temperature increased from 300°C to 600°C, mol% of H2 in gas products increased. The presence of catalysts improves the hydrogen yield. Trona showed gasification activity to be similar to that of K2CO3. It may be concluded that the use of Trona instead of commercially produced catalysts, can be preferably used in the gasification of biomass in supercritical water.
Abstract: The mechanism of microwave heating is essentially
that of dielectric heating. After exposing the emulsion to the
microwave Electromagnetic (EM) field, molecular rotation and ionic
conduction due to the penetration of (EM) into the emulsion are
responsible for the internal heating. To determine the capability of
microwave technology in demulsification of crude oil emulsions,
microwave demulsification method was applied in a 50-50 % and 20-
80 % water-in-oil emulsions with microwave exposure time varied
from 20-180 sec. Transient temperature profiles of water-in-oil
emulsions inside a cylindrical container were measured. The
temperature rise at a given location was almost horizontal (linear).
The average rates of temperature increase of 50-50 % and 20-80 %
water-in-oil emulsions are 0.351 and 0.437 oC/sec, respectively. The
rate of temperature increase of emulsions decreased at higher
temperature due to decreasing dielectric loss of water. These results
indicate that microwave demulsification of water-in-oil emulsions
does not require chemical additions. Microwave has the potential to
be used as an alternative way in the demulsification process.
Abstract: In the present study, a procedure was developed to
determine the optimum reaction rate constants in generalized
Arrhenius form and optimized through the Nelder-Mead method. For
this purpose, a comprehensive mathematical model of a fixed bed
reactor for dehydrogenation of heavy paraffins over Pt–Sn/Al2O3
catalyst was developed. Utilizing appropriate kinetic rate expressions
for the main dehydrogenation reaction as well as side reactions and
catalyst deactivation, a detailed model for the radial flow reactor was
obtained. The reactor model composed of a set of partial differential
equations (PDE), ordinary differential equations (ODE) as well as
algebraic equations all of which were solved numerically to
determine variations in components- concentrations in term of mole
percents as a function of time and reactor radius. It was demonstrated
that most significant variations observed at the entrance of the bed
and the initial olefin production obtained was rather high. The
aforementioned method utilized a direct-search optimization
algorithm along with the numerical solution of the governing
differential equations. The usefulness and validity of the method was
demonstrated by comparing the predicted values of the kinetic
constants using the proposed method with a series of experimental
values reported in the literature for different systems.
Abstract: Arvia®, a spin-out company of University of Manchester, UK is commercialising a water treatment technology for the removal of low concentrations of organics from water. This technology is based on the adsorption of organics onto graphite based adsorbents coupled with their electrochemical regeneration in a simple electrochemical cell. In this paper, the potential of the process to adsorb microorganisms and electrochemically disinfect them present in water has been demonstrated. Bench scale experiments have indicated that the process of adsorption using graphite adsorbents with electrochemical regeneration can be used for water disinfection effectively. The most likely mechanisms of disinfection of water through this process include direct electrochemical oxidation and electrochemical chlorination.
Abstract: In this work, several ASP solutions were flooded into
fractured models initially saturated with heavy oil at a constant flow
rate and different geometrical characteristics of fracture. The ASP
solutions are constituted from 2 polymers i.e. a synthetic polymer,
hydrolyzed polyacrylamide as well as a biopolymer, a surfactant and
2types of alkaline. The results showed that using synthetic
hydrolyzed polyacrylamide polymer increases ultimate oil recovery;
however, type of alkaline does not play a significant rule on oil
recovery. In addition, position of the injection well respect to the
fracture system has remarkable effects on ASP flooding. For instance
increasing angle of fractures with mean flow direction causes more
oil recovery and delays breakthrough time. This work can be
accounted as a comprehensive survey on ASP flooding which
considers most of effective factors in this chemical EOR method.
Abstract: Experimental liquid-liquid equilibra of butan-2-ol -
ethanol -water; pentan-1-ol - ethanol - water and toluene - acetone -
water ternary systems were investigated at (25oC). The reliability of
the experimental tie-line data was ascertained by using Othmer-Tobias
and Hand plots. The distribution coefficients (D) and separation
factors (S) of the immiscibility region were evaluated for the three
systems.
Abstract: Batch fermentation of 5, 10 and 25 g/L biodiesel
derived crude glycerol was carried out at 30, 37 and 450C by
Clostridium pasteurianum cells immobilized on silica. Maximum
yield of 1,3-propanediol (PDO) (0.60 mol/mol), and ethanol (0.26
mol/mol) were obtained from 10 g/L crude glycerol at 30 and 370C
respectively. Maximum yield of butanol (0.28 mol/mol substrate
added) was obtained at 370C with 25 g/L substrate. None of the three
products were detected at 45oC even after 10 days of fermentation.
Only traces of ethanol (0.01 mol/mol) were detected at 450C with 5
g/L substrate. The results obtained for 25 g/L substrate utilization
were fitted in first order rate equation to obtain the values of rate
constant at three different temperatures for bioconversion of glycerol.
First order rate constants for bioconversion of glycerol at 30, 37 and
45oC were found to be 0.198, 0.294 and 0.029/day respectively.
Activation energy (Ea) for crude glycerol bioconversion was
calculated to be 57.62 kcal/mol.
Abstract: Energetic and structural results for ethanol-water mixtures as a function of the mole fraction were calculated using Monte Carlo methodology. Energy partitioning results obtained for equimolar water-ethanol mixture and ether organic liquids are compared. It has been shown that at xet=0.22 the RDFs for waterethanol and ethanol-ethanol interactions indicated strong hydrophobic interactions between ethanol molecules and the local structure of solution is less structured at this concentration as at ether ones. Results obtained for ethanol-water mixture as a function of concentration are in good agreement with the experimental data.
Abstract: In this paper, removal of chromium(VI) from aqueous
solution has been researched using reverse osmosis. The influence of
transmembrane pressure and feed concentration on permeate flux,
water recovery, permeate concentration, and salt rejection was
studied. The results showed that according to the variation of
transmembrane pressure and feed concentration, the permeate flux
and salt rejection were in the range 19.17 to 58.75 l/m2.min and
99.51 to 99.8 %, respectively. The highest permeate flux, 58.75
l/m2.min, and water recovery, 42.47 %, were obtained in the highest
pressure and the lowest feed concentration. On the other hand, the
lowest permeate concentration, 0.01 mg/l, and the highest salt
rejection, 99.8 %, were obtained in the highest pressure and the
lowest feed concentration.
Abstract: The aim of this work was to study the in vitro effects
of δ-lactam 1 and its 4-chlorophenyl derivative 2, on the proliferative
responses of human lymphocytes and Th1 and Th2 cytokine
secretion. The possible protective role of vitamin E on intracellular
stress oxidative induced by these compounds was also investigated.
Peripheral blood lymphocytes were isolated using differential
centrifugation on a density gradient of Histopaque. They were
cultured with mitogen concanavalin A, vitamin E (10 μM) and with
different concentrations of the compounds 1 and 2 (0.1 to 10 μM).
Proliferation (MTT assay), IL-2, INFγ and IL-4 (Elisa kits),
intracellular superoxide anion were determined. 1 and 2 were
immunostimulant and increased cytokine secretion with a shift away
from Th1 response to Th2. These properties were however
accompanied by an increase in intracellular oxidative stress. The
presence of vitamin E exhibited protective effects by reducing δ-
lactam-induced superoxide anion generation in lymphocytes.
Abstract: In this paper, the test purpose will be to assess
whether or not the accelerated model proposed by Eyring will be able
to translate results for the shape and scale parameters of an
underlying Weibull model, obtained under two accelerating using
conditions, to expected normal using condition results for these
parameters. The product being analyzed is a new type of insulate
fluid, and the accelerating factor is the voltage stresses applied to the
fluid at two different levels (30KV and 40KV). The normal operating
voltage is 25KV. In this case, it was possible to test the insulate fluid
at normal voltage using condition. Both results for the two
parameters of the Weibull model, obtained under normal using
condition and translated from accelerated using conditions to normal
conditions, will be compared to each other to assess the accuracy of
the Eyring model when the accelerating factor is only the voltage
stress.
Abstract: Films of pure tin oxide SnO2 and in presence of
antimony atoms (SnO2-Sb) deposited onto glass substrates have
shown a sufficiently high energy gap to be transparent in the visible
region, a high electrical mobility and a carrier concentration which
displays a good electrical conductivity [1]. In this work, the effects of
polycrystalline silicon substrate on the optical properties of pure and
Sb doped tin oxide is investigated.
We used the APCVD (atmospheric pressure chemical vapour
deposition) technique, which is a low-cost and simple technique,
under nitrogen ambient, for growing this material. A series of SnO2
and SnO2-Sb have been deposited onto polycrystalline silicon
substrates with different contents of antimony atoms at the same
conditions of deposition (substrate temperature, flow oxygen,
duration and nitrogen atmosphere of the reactor). The effect of the
substrate in terms of morphology and nonlinear optical properties,
mainly the reflectance, was studied. The reflectance intensity of the
device, compared to the reflectance of tin oxide films deposited
directly on glass substrate, is clearly reduced on the overall
wavelength range. It is obvious that the roughness of the poly-c
silicon plays an important role by improving the reflectance and
hence the optical parameters.
A clear shift in the minimum of the reflectance upon doping level
is observed. This minimum corresponds to strong free carrier
absorption, resulting in different plasma frequency. This effect is
followed by an increase in the reflectance depending of the antimony
doping. Applying the extended Drude theory to the combining
optical and electrical obtained results these effects are discussed.
Abstract: Water recycling represents an important challenge for many countries, in particular in countries where this natural resource is rare. On the other hand, in many operations, water is used as a cooling medium, as a high proportion of water consumed in industry is used for cooling purposes. Generally this water is rejected directly to the nature. This reject will cause serious environment damages as well as an important waste of this precious element.. On way to solve these problems is to reuse and recycle this warm water, through the use of natural cooling medium, such as air in a heat exchanger unit, known as a cooling tower. A poor performance, design or reliability of cooling towers will result in lower flow rate of cooling water an increase in the evaporation of water, an hence losses of water and energy. This paper which presents an experimental investigate of thermal and hydraulic performances of a mechanical cooling tower, enables to show that the water evaporation rate, Mev, increases with an increase in the air and water flow rates, as well as inlet water temperature and for fixed air flow rates, the pressure drop (ΔPw/Z) increases with increasing , L, due to the hydrodynamic behavior of the air/water flow.
Abstract: Isobaric vapor-liquid equilibrium measurements are
reported for binary mixture of 2-Methyltetrahydrofuran and Cumene
at 97.3 kPa. The data were obtained using a vapor recirculating type
(modified Othmer's) equilibrium still. The mixture shows slight
negative deviation from ideality. The system does not form an
azeotrope. The experimental data obtained in this study are
thermodynamically consistent according to the Herington test. The
activity coefficients have been satisfactorily correlated by means of
the Margules, and NRTL equations. Excess Gibbs free energy has
been calculated from the experimental data. The values of activity
coefficients have also been obtained by the UNIFAC group
contribution method.