فهرست مطالب

Chemical and Petroleum Engineering - Volume:52 Issue: 2, 2018
  • Volume:52 Issue: 2, 2018
  • تاریخ انتشار: 1397/04/15
  • تعداد عناوین: 9
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  • Fereshte Tavakoli Dastjerd, Jafar Sadeghi * Pages 107-122
    The aim of this paper is the steady state and dynamic simulations of the ammonia unit of Shiraz petrochemical complex and system behavior study versus the feed flow rate change for producing a good quality product. The ammonia unit consists of the reformer units, shift converter units, carbon dioxide absorption unit, methanation unit, and ammonia synthesis unit. For this purpose, in the first step, the ammonia unit is simulated at a steady state using the Aspen Plus 2006.5 simulator. In the following stage, the required parameters are entered into the software for the dynamic simulation. The Aspen Plus was exported to Aspen dynamic. In this study, PI and PID controllers, as basic controllers, were automatically added and tuned by the Tyreus–Luyben tuning method. Finally, in order to ensure the accuracy of the proposed control structure, the feed flow rate increased by 5%. The results show that, first of all, the simulation accuracy at steady and dynamic states are optimal so that the mean errors are -0.01% and -0.02% for steady and dynamic states, respectively. The controlling structure can well control the 5% feed increase.
    Keywords: Ammonia Unit, Haber-Bosch Process, Nonlinear Behavior, Synthesis Reactor, simulation
  • kamyar movagharnejad*, Niousha Vafaei Pages 123-133
    A total of 1099 data points consisting of alcohol-alcohol, alcohol-alkane, alkane-alkane, alcohol-amine and acid-acid binary solutions were collected from scientific literature to develop an appropriate artificial neural network (ANN) model. Temperature, molecular weight of the pure components, mole fraction of one component and the structural groups of the components were used as input parameters of the network while the refractive index was selected as its output. The ANN was optimized once by genetic algorithm (GA) and once again by particle swarm optimization algorithm (PSO) in order to predict the refractive index of binary solutions. The optimal topology of the ANN-GA consisted of 13 neurons in the hidden layer and the optimal topology of the ANN-PSO consisted of 16 neurons in the hidden layer. The results revealed that the ANN optimized by PSO had a better accuracy (MSE=0.003441 for test data) compared to the ANN optimized with GA (MSE=0.005117 for test data).
    Keywords: Algorithm, Artificial Neural Network, Binary Liquid Mixture, Genetic Multi-Layer Perceptron, Particle Swarm Optimization, Refractive Index
  • Amirhossein Ghorbani, Ramin Karimzadeh *, Masoud Mofarahi Pages 135-143
    Dynamic modeling and simulation of fixed bed adsorption process was carried out by explaining the behavior of breakthrough curve parameter. Adsorption of sulfur compound, present in road fuel, has posed a great challenge. A model of fixed bed adsorption of benzothiophene from fuel was formulated with non-ideal plug flow behavior and considered velocity variation along a column. The model was solved using the Method of Line (MOL) numerical solution - a technique for solving PDEs - in which all but one dimension is discretized; as a result, the set of ODEs can be solved by highly accurate methods and low computational cost. The effects of various factors, such as flow rate (4-10 cc/min), inlet concentration (125-500 ppm), and bed height (10-40 cm), on adsorption performance, were investigated. Specific characteristics, typical of breakthrough curve, were analyzed in terms of degree of bed utilization, break point time, film mass transfer coefficient, and height of adsorption zone. High bed column, high flow rate, and high inlet concentration happened to be better conditions, in term of used overall bed capacity percent for adsorption system.
    Keywords: Adsorption, Benzothiophene, breakthrough curve, Fixed Bed, Modeling
  • Ahmed Zoeir, Seyyed Alireza Tabatabaei Nejad, Elnaz Khodapanah * Pages 145-155
    Application of foam in EOR, increases macroscopic sweep efficiency via awesome increscent of mobility control. Macroscopic manifestation of foam application performance in porous media is complex process that involves several interacting microscopic foam events. Stability as an important factor in foam injection within large reservoirs, depends on several variables including oil saturation, connate water salinity and the foam texture. In addition to mentioned parameters, internal structure is known to affect the foam’s stability and performance via influencing foam formation and destruction mechanisms within the porous media. In this paper we mathematically expressed main mechanism of snap-off for foam generation, mechanisms of capillary suction and diffusion coarsening for foam coalescences in some simplified models. Then we extended the calculations to more realistic 2D spherical models of porous media which were manufactured applying some morphological parameters. Simulation results show that in topologies in which the structure represents high difference in pore and throat average diameters, foam formation mechanisms are dominant making foam flow more stable while conversely when the path tortuosity is high, foam destruction mechanisms overcome and the stability decreases.
    Keywords: Foam Stability, Model Porous Media, Internal Structure, Rock Topology, Reservoir Rock
  • Mohammad Khosravi, Ali Ghadimi, Zahra Mansourpour *, Azadeh Ghaee, Behrouz Sadatnia Pages 157-167
    This paper investigates effects of different additives on morphology and subsequently, separation performance of asymmetric flat sheet Polyvinylidene fluoride (PVDF) membranes to separate CO2 using membrane contractor. Five different additives from different chemical families including Lithium chloride (salt), Polyethylene glycol 400 (polymer), glycerol (weak anti-solvents), methanol (alcohols) and acetic acid (weak secondary solvents) were used for controlling the morphology of the fabricated membranes. The fabricated PVDF membranes were applied to separate CO2 from a gas mixture of (20/80 wt/wt) CO2/N2 by contacting with (20/80 wt/wt) Monoethanolamine/H2O as absorbent. The investigations revealed that among the all considered additives, glycerol has the most promising effect on the performance of CO2 separation from the feed gas mixture. Effects of operational parameters such as flow rate and temperature of absorbents on the separation performance were also studied. Investigations showed that the lowest level of temperature (30 ºC) and the highest level of the flow rate of absorbent (500 ) provide better separation performance. Additionally, the presence of glycerol increased absorption performance (η) from 0.63 to 0.78 (at the lowest level of flow rate) and from 0.79 to 0.91 (at the highest level of flow rate) compared to the bare PVDF membranes.
    Keywords: Absorption Performance, Membrane Contactor, Morphology, Operating Parameters
  • Seyed Mostafa Seyed Atashi, Kamran Goshtasbi *, Rouhollah Basirat Pages 169-179
    Oil production may be accompanied by Sand Production (SP) in the weak sandstone reservoirs. Fluid flow is an important factor in transporting the separated grains and completing the SP mechanism. In this paper, the effect of fluid parameters, fluid flow, and fluid pressure on the SP is investigated by applying the Discrete Element Method (DEM). Parametric studies show that fluid velocity is reduced by increasing the fluid viscosity, leading to a drop in the SP. In the present study, for an accurate investigation and discovering the effects of viscosity and drag force, the boundary conditions were applied to retain the fluid velocity as a constant amount. The results showed that viscosity is directly related to SP. Moreover, we found that when the fluid velocity is high, there would be the possibility of catastrophic production in the reservoirs with a heavy oil fluid. The rock reservoir around the well will be loosened as soon as SP is initiated. The results also indicate that SP has a direct relation with fluid pressure, fluid velocity, and confining pressure.
    Keywords: DEM, Fluid Properties, numerical modeling, Sand Production
  • Marjan Roshandel, Rahmat Sotudeh, Gharebagh *, Sasan Mirzakhanlouei, Reza Hajiaghaee, Reza Ghaffarzadegan Pages 181-191
    Curcumin is an herbal plant with great therapeutic applications. Although it is useful in treating several diseases, its low solubility in water and low bioavailability in living systems are limiting factors in using curcumin as a medicine. One way to overcome these shortcomings is the production of curcumin micro/nano particles. In this research, the particles of curcumin loaded with polycaprolactone (PCL)/chitosan were synthesized by the electrospray technique. To obtain the optimal conditions, statistical optimization was carried out through Response Surface Method (RSM). The effect of flow rate, polymer concentration and PCL weight percentage on solution properties, mean particle size and particle size distribution were investigated. According to experimental results, the optimal size (471 nm) and size distribution (103) of particles were found at the lowest level of polymer concentration (2%) and flow rate (0.25 ml/hr) and the highest level of PCL weight percentage (80%). Thus, the result of this study can be used to improve the quality of curcumin based medicine.
    Keywords: Nano Particles, Statistical optimization, Design of Experiment, Curcumin, Electrospray, Micro
  • Siamak Alipour, Asadollah Karimi, Chiya Savari * Pages 193-200
    In this study, the techno-economic analysis of lignocellulosic biomass conversion to electricity in a small scale power plant was conducted. The proposed process is based on the thermal pathway of electricity production from a carbon content feed. Woods, forest and agricultural residues were considered as the biomass feed, which are available extensively in Iran. Besides, the process benefits not only from the maturity of the method and non-selectivity toward feed but also carbon neutrality and CO2 emission credit income. In order to estimate the minimum selling price (MSP) of the product by this process, the bare module cost model was used. Various equipment sizes were determined by mass and energy balances, whereas the studied power plant capacities were considered 0.5, 1, 5 and 10 MW. The model estimated that the product MSP were 5.83, 4.16, 1.99 and 1.58 ¢/kWh for 0.5, 1, 5 and 10 MW capacities, respectively. Furthermore, a sensitivity analysis was performed to investigate the relative significance of economic parameters on the MSP. The feed, transport, purchased equipment costs and CO2 emission credit income were considered as the sensitivity analysis parameters. Results have proved that the MSP was mainly impacted by the CO2 emission credit income.
    Keywords: Techno-economic, Electricity, Lignocellulosic Biomass, Sensitivity analysis, Power Plant
  • Sepehr Hamzehlouia , Jamal Chaouki* Pages 201-210
    Temperature measurement in microwave systems is essential for thermally driven processes, namely, catalytic reactions and ceramic sintering. Although, the application of direct thermometry methods, namely, thermocouples, have been commonly articulated in the available literature, however, contacted temperature measurement mechanisms have aroused concerns associated with the disruption of the electromagnetic field and local distortion of the field pattern leading to unprecedented measurement uncertainties. Consequently, the application of optical measurement methods has been advocated to diminish the associated concerns. However, due to the economical constrains and measurement range restrictions, the application of optical measurement systems, namely, pyrometers and optical fibers, has been deferred. In this study, an infrared thermopile, a precise and feasible temperature measurement system has been developed and calibrated to perform in microwave irradiation. Furthermore, the accuracy of the developed temperature system has been compared with the thermometry technique. It was concluded that thermopile stipulates unrivalled precision, succeeding a profound calibration procedure. It was further demonstrated that the thermopile is capable of the temperature measurement of the dielectric surfaces, exclusively, while the grounded thermocouple monitored the bulk temperature, a proportion of the gas phase and the solid phase temperature values. Consequently, the application of a thermopile coupled with a thermometry measurement method has been proposed to monitor the temperature of the dielectric catalyst active sites in gas-solid catalytic microwave-heated reactions.
    Keywords: Optical Measurement, Temperature Measurement, Thermometry, Thermopile