Kinetic modeling of ethylbenzene isomerization using Bodenstein approximation technique

Ethylbenzene isomerization reaction is a significant reaction employed in the production of xylene isomers which are used as petrochemical feedstocks. The reaction which proceeds over Pt/Al2O3 catalyst is multi-pathway and multi-cycle in topology. Kinetic model for the reaction was developed in this study using the general rate equation approach. Bodenstein approximation, cross-to-square, and Y-to-delta transformation techniques were used to reduce the complex reaction network to a single cycle network. In addition, the general rate equation for reduced single cycle networks was applied to derive the model for the reaction. The Nelder-Mead simplex optimization technique was used to estimate the kinetic parameters in the model. The structure of the model developed indicates that the model reasonably represents the mechanism of the reaction although few anomalies were observed in the values of the kinetic parameters estimated. The activation energy obtained for the rate constants follows the expected trend for multi-step reactions

Price Transmission, Volatility and Discovery of Gram in Some Selected Markets in Rajathan State, India

Market integration in many agricultural commodities had been extensively studied for the insight it provides into the functioning of such markets, thus giving valuable information about the dynamics of market adjustment, and whether there exist market imperfection, which may justify government intervention. This study empirically investigated price transmission, volatility and discovery of gram across four wholesale gram markets, viz. Jaipur, Kishangarh, Chomu and Malpura in Rajasthan state of India using Johansen's multivariate cointegration approach, VECM, Granger causality tests, GARCH, EGARCH and ARIMA. Monthly wholesale gram price data spanning from January 2011 to December 2015 sourced from AGMARKNET were used. Multivariate cointegration showed that all the selected gram markets were cointegarted in the long-run, meaning long-run price association among these markets. The degree of market integration observed is consistent with the view that Rajasthan state gram markets are quite competitive; thus, provide little justification for extensive and costly government intervention designed to enhance market efficiency through improve competitiveness. Therefore, in order to sustain the present system of market integration, there is need to evolve mechanism that will generate market information and market intelligence which would serve as a platform for guiding farmers in marketing their produce

Mediating effect of positive psychological strength, study skills on examination anxiety among nigerian college students

Examination plays a vital role in the present contemporary educational setting as well as serving as an indicator and yardstick to place students in relation to their examination scores after they undergo the examination. However, students at different educational levels experience examination anxiety, which can interfere with making right decisions either before or during examinations and is considered to be a phenomenon associated with low examination scores. Therefore, the present research study was aimed at determining the mediating effect of positive psychological strengths between study skills and examination anxiety among Nigerian college students. The study employed survey research on 315 Nigerian college students. The result of the path analysis shows that study skills (SSK) have a significant and direct relationship on examination anxiety. The mediation between positive psychological strength (PPS) and examination anxiety is identified as being effective and significant. Therefore, positive psychological strength (PPS) acts as an effective mediator towards examination anxiety

Optimization and Non-Linear Identification of Reservoir Water Flooding Process

In this study, dynamic optimization and identification of petroleum reservoir waterflooding using receding horizon (RH) principles was examined. Two forms of the strategy were compared on a realistic reservoir model. Sequential quadratic programming (SQP) was applied to optimize net present value (NPV) using water injection rates as the variables. MRST from SINTEF was used for the reservoir modeling. The identification of the reservoir was performed using nonlinear autoregressive with exogenous input (NARX) neural network from MATLAB. Data for the network training and validation was obtained by carrying out a numerical experiment on a high fidelity model of the reservoir. This model was developed with Eclipse Reservoir Simulator from Schlumberger. From the results obtained, moving-end RH gave a higher NPV than fixed-end RH with a margin of $0.5 billion. The identification algorithm was very much effective and near perfect for the studied reservoir

Kinetic Modeling of Ethylbenzene Isomerization using Bodenstein Approximation Technique

Ethylbenzene isomerization reaction is a significant reaction employed in the production of xylene isomers which are used as petrochemical feedstocks. The reaction which proceeds over Pt/Al2O3 catalyst is multi-pathway and multi-cycle in topology. Kinetic model for the reaction was developed in this study using the general rate equation approach. Bodenstein approximation, cross-to-square, and Y-to-delta transformation techniques were used to reduce the complex reaction network to a single cycle network. In addition, the general rate equation for reduced single cycle networks was applied to derive the model for the reaction. The Nelder-Mead simplex optimization technique was used to estimate the kinetic parameters in the model. The structure of the model developed indicates that the model reasonably represents the mechanism of the reaction although few anomalies were observed in the values of the kinetic parameters estimated. The activation energy obtained for the rate constants follows the expected trend for multi-step reactions. &nbsp

Modeling and Simulation of Hemihydrate Phosphoric Acid Plant

In this paper, wet hemihydrate phosphoric acid process was modeled and simulated using ASPEN PLUS using properties of Sokoto Phosphate Rock to characterise the basic raw material. The process consisted of the reaction section, filtration section, and purification unit. Results of the simulation showed that the model developed in this study described the behavior of a real plant. Sensitivity analyses for the fundamental parameters were performed using the model. From the results of the sensitivity analyses, it was found that the temperature and pressure of the flash separator are the main factors that affect the purity of wet process phosphoric acid. At a temperature above 400°C, the purity of the phosphoric acid is maintained at 100%. This value changes at temperatures below 80°C where the phosphoric acid purity is maintained at 74%. This indicates that the purity of the acid increases with increase in flash separator temperature. The purity of the phosphoric acid varies inversely with the pressure of the flash separator. The purity of the phosphoric acid is about 84% at 0.5 bar. It decreases gradually with increase in pressure

Enhancing Oil Recovery through Waterflooding

Waterflooding is a simple and cheaper means of improving oil recovery from a reservoir by injecting water into the reservoir. Economic considerations suggest injection and production wells must be optimally placed considering reservoir geology, fluid properties, and well orientation. This study focuses on the effects of well placement and orientation on the performance of waterflooding process. The reservoir has a dimension of 2500 ft by 2500 ft by 150 ft. It is homogenous in porosity and heterogeneous in permeability. The performances of three cases considered in the study were evaluated and compared. Water production rates, bottom hole pressure limits for producer wells, well water cut and net present value (NPV) over the entire production period were considered in evaluating their performances. Reservoir modeling and simulation were carried out using MATLAB Reservoir Simulation Toolbox (MRST). It was verified from the investigation that Case III has a maximal production rate of 1,110,188.6 stb/day (stock tank barrel per day), decreasing to 11,005 stb/day after a span of 1400 days with a pressure decrease. Consequently, it was considered a better choice in terms of well placement. It was also estimated to have a maximal Net Present Value of 19.8 billion dollars, which makes it economically viable

Modular Cryogenic Energy Storage System: Simulation and Techno-Economic Analysis.

Sustaining economic growth while reducing reliance on fossil fuels for environmental protection is a global challenge. Efforts are made to decrease energy utilization by enhancing energy efficiency and discovering clean renewable energy sources. Cryogenic energy storage (CES) is a grid-scale energy system where electricity is stored in the form of liquefied gas. It is regarded as a solution because it allows for increased electricity generation while also providing economic benefits by avoiding costly operational consequences. The CES was modeled and simulated in Aspen HYSY V8.8 using three system confirmations: standalone adiabatic, waste heat integration, and combustion integration. Unlike in the conventional CES, Dowtherm-Q was used as the thermal fluid due to its thermal stability, non-corrosiveness, and high temperature resistance. The results indicated that the higher the adiabatic efficiency of the turbine, the greater the power generated; also, increasing the turbine inlet temperature enhanced the performance of the system configuration by lowering the pressure and increasing the power of the turbine. The economic analysis revealed that the waste heat-based system has both the lowest operating cost, capital cost, utility cost, and higher energy savings. Waste heat integration produces the most power (653.70 kW) and saves the most energy (69.58%), with lower capital costs, operating costs, and utility costs due to the increased adiabatic efficiency of the turbine. It implies that CES with waste heat integration is economically more promising compared to adiabatic standalone and the integration of combustion. &nbsp

Modeling and Simulation of Pyrolysis Process for a Beech Wood Material

Modeling and simulation of beech wood was carried out using Aspen Plus simulation commercial package. The model was created based on pyrolysis product yield, proximate and ultimate analysis of the wood species. In the model development, RYield was used to represent pyrolysis reactor as a non- stoichiometric type that decomposes the wood into categories of conventional compounds. The model was simulated to give the components compositions in both gaseous and liquid products. The simulation was first conducted at a temperature of 450oC, for range of feed particle sizes from 1.6-2.0 mm, using atmospheric pressure. Five different runs were carried out by varying their temperatures and particle size. The investigation revealed the effect of pyrolysis temperature and wood particle size on compositions of liquid and gaseous products. The results showed that production of methanol increases with temperature but decreases at temperatures beyond 550oC. Carbon dioxide yield decreases with increase in temperature while that of carbon monoxide and methane get higher as temperature increases