مجله فرآیند نو
پیاپی 49 (بهار 1394)

Identification of the location of energy loss is the most important step in energy optimization of industrial plants. Exergy analysis specifies the points of irreversibility and the amount of exergy loss. According to the equipment exergy loss، the energy bottlenecks of unit will be specified. Exergy Analysis of Abadan catalytic reforming unit shows heat exchangers، which preheating the feed streams of unifiner and platformer fire heaters (H-E-1 and P-E-1)، have the maximum exergy loss of heat exchangers network. Adding two pairs of heat exchangers to these heat exchangers، the network is retrofitted. Therefore the exergy loss reduces 4. 0769 (MMBtu/hr) in winter and 4. 4563 (MMBtu/hr) in summer. This retrofit needs approximately $215000 investment and will also reduce heat duty of hot and cold utilities to 15 and 9 MMBtu/hr، respectively. This retrofit causes 7% energy saving. The payback period of this investment is 45 months and then will save $57000 annually.

Diffusion Coefficient is the most important effective parameter in mass transfer. A correlation for estimating the diffusion coefficients of some gases is presented. The new correlation is based on physical properties of the solvent and solute which are available with a minimum cost. The modeling is based on Wilke-Chang model with empirical corrections in which solute molecule radius (R) and ξ parameter have been taken into account. The results reveals that while Wilke-Chang correlation for prediction of diffusion of CO_2، N_2 and O_2 has the 9% error and new correlation has only 3. 8%. Also Wilke-Chang prediction for diffusion of CO2 in water has 6. 5% error while new model predicts that with 2. 7% error.

In this paper، a thermodynamic modeling approach is presented for characterizing the behaviors of a crude oil preheat furnace. Convection sections and radiant section are modeled and a simple model for combustion is given، where only a single pass is considered for modeling. Thermal equations are proposed based on mass and energy balance، thermodynamic، heat transfer and also based on semi-empirical relation for the crude oil thermo-physical behaviors. The parameters are defined based on geometrical information، empirical relations and experimental data from real furnace performances. Capability of the developed models in predicting the output oil temperature is validated by a comparison between the obtained results from simulation experiments and the data taken from the real system responses.

Refineries in the cycle of fuel and energy supplying have an incomparable role. Continuous production with attention to non contamination of environment needs to optimization of wastewater and disposal treatment processes and using of new techniques in wastewater treatment plants. Amount of excess biological sludge in Bandar Abbas refinery is 40-50 ton/month. Estimations show that the cost of sludge management in this plant is about 40-60% of total cost. Addition to disposal of this sludge with oily contaminates maybe cause to damage of environment. For minimization of excess sludge in this research used advanced oxidation processes. Results show that using of hydrogen peroxide in compare with ozonation and peroxone had better results. In optimized condition، amount of excess sludge and COD can reduce up to 73. 33% and 56. 97% respectively.

The oily wastewaters from oil refineries and oil distribution centers are one of the most important environmental pollutants in recent decades. In this research، the performance of different membranes in oily water treatment has been reviewed and furthermore، the performance of nanostructured polyethersulfone (PES) hollow fiber membranes in oil/water separation process has been investigated and the effect of operating parameters such as pressure، oil concentration and cross flow velocity of feed on the membrane performance is studied. Increasing the pressure makes more membrane compactness، therefore the optimum operating conditions for oil separation are P = 1، low feed concentration and high cross flow velocity. All the fabricated membranes showed complete separation of oil from water. Therefore، they can effectively be used in oily water treatment. Membrane #M1 with the pore size of 15. 6 nm showed the best permeation flux of 12. 4 (L/m2/hr) with 100% oil rejection.

The genetic/quadratic search algorithm (GQSA) is a hybrid genetic algorithm (GA) for optimizing plant economics when a process simulator models the plant. By coupling a regular GA with an algorithm based upon a quadratic search، the required number of objective function evaluations for obtaining an acceptable solution decreases significantly in most cases. The GQSA combines advantages of GA and quadratic search techniques، e. g. determining a global optimum for a problem with a high probability for discontinuous as well as non-convex optimization problems while at the same time providing faster convergence than conventional GA. In this work، the performance of both the GQSA and the GA was compared using four different test functions and an economic optimization problem for a turbo-expander process. Numerical test results indicate that the convergence of the GQSA is either better than to those of GA for all tests employing the same genetic parameters

Human resource is the most important resource in the organization. However، the mental health is even more effective than physical health and it may have effects on basic elements of an organization. This study examines the causes of job burnout among the employees of National Refining and Distribution Company and the influence of these factors on employee empowerment and then effect of these factors in People capability maturity. These factors are been bases element in organization and reached to its objectives. the results identify 19 factors in three categories including organizational factors; interpersonal factors; and intrapersonal factors;. job burnout variable has a significant effect on the maturation of employee empowerment and among the variable components of job burnout، the items of age، awareness of organizational policies، performance evaluation، and welfare facilities، working environment، interpersonal relationships، leadership and emotional commitment have a significant impact on People capability maturity