فهرست مطالب mohammadreza sardashti birjandi

In this research, natural pozzolanic materials were used in cement production to reduce the emission of CO2 and energy consumption. The rate of substitution of cement with natural pozzolan powder varied from 20% to 50% in 100 samples. Compressive strength tests were carried out on mortar specimens (4×4×16 cm3) after 2, 7, and 28 days. The obtained activity index was approximately 85% and volcanic ash was pozzolan. The compressive strength values changed from 122 to 318 kg/cm2 after 7 days and from 201 to 433 kg/cm2 after 28 days. However, the reduction of CO2 emission with 20% to 50% of additive amounted from 130.74 tons to 419.32 tons of CO2 per ton of clinker. By using 3 to 53% of additives, electricity consumption decreases from 1.89 to 33.39 kWh per ton of clinker. Moreover, this amount of additive can raise energy savings from 99160.8 to 1751841.8 kJ per ton of clinker.

Ethylene is one of the most important basic materials in petrochemical industries. It is used as raw material in the production of many chemicals, such as polyethylene and ethylene glycol. The thermal cracking of hydrocarbons, such as ethane, is the most commonly used process for ethylene production. Thermal cracking furnaces provide the required energy for cracking ethane to ethylene. In this research, the cracking furnaces of the Morvarid petrochemical complex was simulated and controlled and sensitivity analysis were performed. For this purpose, firstly the unit was simulated in steady state using Aspen Plus® and after ensuring simulation accuracy, the results were used as the starting point for dynamic simulation in Aspen Dynamic® and the dynamic behavior of the unit was studied. The accuracy of this simulation was satisfactory in dynamic and steady-state forms, so that the average error of stream information compared to the design data were 0.42% and 1.15% for steady-state and dynamic simulation, respectively. Then the feed flow rate stepwise increased to 6.6% of the initial flow rate while the ethylene conversion was controlled at 38.5%. In order to achieve this conversion, the temperature of the thermal cracking furnaces increased to 1131℃ with increasing feed flow rate. With this changes, change of ethylene product flow rate was 0.86 of feedstock changes. Then, the change in the feed composition was investigated whilst the propane concentration in the feed stream was increased gradually as well as the ethane concentration was decreased by 10%. In this case, the mass fraction of propane in the feed flow was changed from 2.52% to 12.52%. Due to these changes and without changing the unit operating condition, finally, the ethylene flow rate decreased 3.3% compared to the primary state.

One of the widely used methods to remove acid gas is surface adsorption using solid molecular sieves. The advantages of H2S adsorption with molecular sieves can be seen in reversibility of the process, chemical and thermal stability, no secondary product, and high selectivity of H2S in these adsorbents. Therefore, in this study, Aspen-Adsim software was used to investigate the effect of various parameters on adsorption of H2S on 4A molecular sieve adsorbent. The desired bed is considered vertical and one-dimensional. The results related to the breakthrough curves and saturation time showed that maximum amount of adsorption occurred in early times. As the adsorption time increases, the rate of H2S adsorption decreases. The results of investigating the effect of operating parameters showed that increasing the tower pressure from 90 to 104 bar reduces the output H2S content by 21 ppm. Also, reducing the feed temperature showed significant results on amount of H2S absorption and the reduction of the output H2S content, so that for every one degree of temperature reduction in the feed gas temperature, the dew point temperature of the output was reduced by 1.6°C. Due to high amount of absorbent and its heat capacity compared to the amount of H2S in the gas phase, a slight temperature increase occurs along the tower so that the difference between inlet and outlet temperatures does not exceed 1˚C. According to the breakthrough curve, it was also determined that after 7920 seconds, the entire bed of the tower is saturated with H2S molecules.

Today, the use of renewable energies has become increasingly important due to the fossil fuels being consumed which cause environmental pollution. The use of solar energy due to the abundance and availability of this energy and the ability to save and convert it into other forms of energy has been considered. In this work, a stepped solar still is simulated in two dimensions using Comsol software. Also, increasing the number of stairs and adding a number of Fins to increase the amount of fresh water produced has been studied. The simulation results were compared with the experimental data. The average error rate for fresh water produced and the temperature of saline water obtained from the software with experimental values are 11.78 and 1.75 percent, respectively. The results show that as the number of steps increases, the amount of fresh water produced increases. In addition, adding three thermal fins with a size of 0.3 cm on the stairs compared to the existing state of the device, the amount of fresh water produced increases by 9.65%.

A huge part of the thermal energy consumed in energy industries is lost after exiting the process. Some of this waste heat can be recovered by various methods such as generating electrical energy, generating hot air for the production process or providing hot water. In Iran, the cement industry has always been far from the optimal use of resources, including energy, due to the existence of energy subsidies. In this research, the heat loss from the baking system of Nireez white cement plant as a model industry of the country to evaluate the simultaneous production of heat and electricity by using the organic Rankine cycle that generates electric power has been investigated in Span Plus V12 software. This evaluation is done to calculate the heat loss, including the mass and energy balance on the cooking system, as well as the energy balance on the pre-cooking system. The heat energy obtained enters the Rankine cycle and is converted into energy by the turbine. The results show that 635 kilowatts of electrical energy was produced from energy recycling, which leads to the elimination of 317.5 kg/hour of greenhouse gas.

Liquefied petroleum gas (LPG) refers to the hydrocarbon gases propane, butane or their combination. Liquid gas is often used for heating purposes and vehicle fuel. In refineries, the hydrocarbon flow of propane, butane and pentane contains impurities such as methyl mercaptan, ethyl mercaptan and other mercaptans. In this research, the simulation of mercaptanization unit of Abadan refinery has been done. First, the unit was simulated in the ProMax software and after the validation of the simulation, the effect of process variables such as the caustic flow rate, caustic concentration, sour feed flow rate and washing column pressure on the concentration of mercaptan in product has been investigated. The concentration of mercaptans in the output product has been discussed. The results of the simulation show that the total calculation error is less than 10%, which indicates the accuracy of the simulation in steady state. Based on the simulation results, with the increase of caustic flow rate, concentration of caustic solvent and washing column pressure, the amount of produced product (ethyl mercaptan and methyl mercaptan) decreases. Only by increasing the flow rate of sour feed, the amount of produced product will increase.

Gas pressure reduction stations are one of the most important parts of natural gas distribution networks. Risk assessment in operational units is a suitable method to assess risks, and their results can be used for management and decision-making regarding control and reduction of its consequences without critical concern. In other words, risk assessment is a process that identifies risks, assesses losses and determines risk characteristics. The present study aimed to model possible accidents, the subsequent evaluation of the consequences, and determination of safe boundaries in the suburban natural gas pressure reduction station located in the Bromi area of Ahvaz city using PHAST software.

In this study, possible scenarios based on the investigated background and utilizing the process data of the studied gas pressure reduction station, such as temperature, gas pressure, gas analysis, and meteorological data, and also using Pasquil's classification of atmospheric conditions the safe boundaries in the suburban natural gas pressure reduction station was investigated using PHAST software version 22.8 and. For this purpose, 6 possible scenarios were investigated in the selected atmospheric classes as well as the worst possible conditions. The consequences were evaluated based on different states of gas discharge, gas release, flash fire, sudden fire, and explosion.

Based on the obtained results, the areas with high-risk potential were related to gas release and explosion, respectively. Also, the highest risk range belonging to scenario number five was reported for a gas explosion with atmospheric class F and wave intensity of 0.02068 bars and equivalent to 358.5 meters. In this range, according to the damage caused by the explosion, with a probability of 95%, without serious damage, 50% of the windows will be broken, and therefore it can cause human injuries. Based on this, the safe distance in this station was determined to be 358.5 meters.

Based on concerns about the lack of risk assessment studies over the initial phases and during the operation of the station, the study shows that determining the safe boundaries and high-risk areas along with the priority of risk reduction is very necessary. It can be concluded that the modeling of accidents and the evaluation of the resulting consequences along with the determination of safe boundaries is one of the basic factors in the health of the working environment of personnel and the general public.

Heavy crude oil cracking units (hydrocracker) and crude oil desulfurization (hydrotreater) are the two most important hydrogen-consuming units in the refinery. Affected parameters such as hydrogen consuming units and environmental rules increase the necessity of optimization the hydrogen network in the refinery. In this article, we intend to obtain the optimal hydrogen network structure in Abadan Refinery using the superstructure method. The superstructure method includes a mathematical model that is able to provide the hydrogen necessity by consumers and design the optimal hydrogen network with the lowest cost. The results of optimization show the hydrogen from RPS CRU and COLD-SEP CRU streams, which were sent to the fuel system before optimization can be recovered and reused in the network. RPS CRU and COLD-SEP CRU flow rates of 5000 and 3600 (kg/h), respectively, with relatively high purity of hydrogen, can be sent to the PSA purifier for the recovery. In addition, regarding to the recovery there is no necessity to utilize the hydrogen production unit (U-57) and it will be taken out of service, and as a result, the purchase cost of the hydrogen production unit will be removed from the network.

Sulfur is one of the most important products in the processing of oil and gas, which is used in important industries such as sulfuric acid production and agriculture. Hence, the improvement of the efficiency of sulfur production processes at the industrial scale has paid a lot of attention. Due to some process problems such as the presence of heavy aromatic compounds and inappropriate temperature, the efficiency of this unit decreasesTherefore, in this paper, the steady state simulation of the modified Claus process of the Sulphur Recovery unit of the first refinery of the South Pars Gas Complex using Aspen Plus software has been done. The dynamics of CO2 concentration and furnace temperature were also studied. The simulation accuracy is desirable in the stable and dynamic state, so that the average error for the simulation flow data compared to the industrial data is 2.52% and 2.11% for the dynamic and dynamic mode, respectively. In addition, the results indicate an increase for sulfur produced by increasing the furnace temperature and reducing the concentration of CO2.

Hydrogen is one of the most important sources of renewable energy, but in most refineries, along with the production of hydrogen by fossil fuels, a significant amount of CO2 is also produced. This paper presents a mathematical model for CO2 emission from each unit in the hydrogen network as well as multi-objective optimization. This model includes linear mathematical programming (LP), which illustrates the relationship between CO2 emissions and feed input to the fuel system and the output product of the hydrogen generating unit. The model constant parameters are obtained from the experimental data from the hydrogen network of Bandar Abbas Oil refinery. The objective function is based on the multi-objective function, which simultaneously reducing CO2 emissions and also reducing total annual cost of hydrogen network. The results of optimized network indicated that total annual cost and CO2 emissions have been decreased by 29.1% and 22.4%, respectively. Furthermore, hydrogen within the fuel system was recovered to use in hydrogen network by purifications units. The amount of hydrogen recovery from fuel gas, which has been sent to purification units, is 16200 m3/h.

In this research, the simulation and control of gas sweetening unit of Fajr Jam refinery were studied. Initially, the simulation was carried out with diatolenamine solution. Then, a combination of ethanolamine and methyl ethanolamine was used to improve the process performance. The unit was simulated in a stable-state using a combination of ethanolamine and methyl ethanolamine in Aspen Plus®</sup> and after ensuring simulation accuracy, the results were used as the starting point for dynamic simulation in Aspen Dynamic®</sup> and the dynamic behavior of the unit was studied. Finally, the optimal operating conditions of the process were obtained using the surface response method. The simulation accuracy has been desirable in steady-state and dynamic forms and   the average error for the intensity of the amine flow rate input to the tower is 0.022%. The results of using the combination solution show adsorption of about 99.72% and 91.77% of carbon dioxide and hydrogen sulfide gas, respectively.</strong></em>

In this paper, the simulation of the displacement enclosure of the H-151 furnace unit of the distillation unit in the Isfahan refinery is carried out by using computational fluid dynamics (CFD). This simulation involves simultaneous investigation of fluid flow inside the tubes of displacement enclosure and the flue gas flow of convection section through the tubes as well as displacement enclosure gas flow by adding additional tubes in a two-dimensional state. Grid independency study was done for tube and displacement enclosure and the best grid with numbers of 315000 and 67024 were chosen for tube and displacement enclosure, respectively. The error of temperature and velocity diagrams for tubes with grid numbers 315000 were 0.021% and 0.0569% and for displacement enclosure with grid numbers, 67024 were 0.0712% and 0.0254%, respectively. The velocity and temperature diagrams for the tube, displacement enclosure, and displacement enclosure with additional tubes were obtained and examined. The results show that the flow at the beginning of the tube is turbulent. The fluid velocity inside the tube has been developed from 1.4 meters due to the large length of the tube. The comparison of the results obtained from the displacement enclosure with/without additional tubes has been shown that the temperature and velocity of the gas passing through the tubes are reduced by using additional tubes.

The purpose of the study is to present a new process cycle based on a pre-pressure stage to improve the performance of the mercaptan removal process from the natural gas in South Pars Gas Company. The separation process was simulated based on Pressure-temperature swing adsorption (PTSA) method using Aspen Adsorption software. Results showed that consumption power of compressor has been decressed by 36.83% using improved cycle. Moreover, the amount of separation capacity of mercaptans has been gained by increasing the inlet feed flow rate and the second heating stage temperature in both cycles. The maximum separation capacity was obtained by 7.7% at the feed flow rate of 2.3 kmol/hr and by 7.9% at the temperature of 298°C. The results demonstrated that the effect of temperature on separation capacity is greater than the inlet feed flow rate.The maximum separation capacity was obtained by 7.7% at the feed flow rate of 2.3 kmol/hr and by 7.9% at the temperature of 298°C. The results demonstrated that the effect of temperature on separation capacity is greater than the inlet feed flow rate.

The growing global population on the one hand, as well as the scarcity of fresh water resources, are the reasons for the global water crisis. Therefore, to cope with these conditions, humans need to find alternative and renewable freshwater sources through the treatment of existing unhealthy waters or desalination of saltwater. Staircase solar water purifiers are among the many devices used in water purification. This paper deals with the simulation of a staircase solar water desalination at the University of Sistan and Baluchestan with Comsol software. After comparing the experimental data and the results of the software, the influence of saline depth parameter on the stairs on the amount of fresh water output from desalination was investigated. For this purpose, the performance of the device for saline water depths of 0.005, 0.0075 and 0.01 m with inlet saline flow rate of 0.2 (kg / min) was investigated. The results show that with increasing salt-water depth, the water temperature decreases and the temperature difference between the water surface and the glass surface decreases and the amount of fresh water produced decreases.

The purpose of this research is to optimize the sulfur separation unit to increase sulfur production and simultaneously reduce the production of carbon dioxide based on the information of the unit for the separation of sulfur in the Ilam refinery. The input variables of the sulfur separation unit are the feed flow rate, airflow, furnace temperature, furnace pressure, first catalytic reactor temperature and the first catalytic reactor pressure. The mathematical model of the process was obtained using the surface response method (RSM) and the accuracy of the model was analyzed by analysis of variance. Finally, the operating conditions of the sulfur separation process were performed with numerical optimization method. The results showed that the most effective parameters are furnace temperature, air flow rate, and feed rate. The optimum points for the furnace temperature of 1039 °C, the airflow rate 469.38 kmol/h, and feed flow rate 1110.38 kmol/h were obtained which increased the sulfur production from 30% to 89% and decreased the production of dioxide Carbon from 55% to 8%.

In this paper, petrochemical synthesis gas production unit is simulated using Aspen Hysys software and the effect of changing parameters such as temperature and pressure on the output current of the secondary reactor in the unit is investigated. In addition, due to the age of the study unit, the addition of a tri-reforming reactor to increase the production efficiency of petrochemical synthesis gas has been investigated. The results also show that with increasing temperature on the output current of the secondary reactor, the percentage of methane conversion and the ratio of hydrogen to carbon monoxide increase. However, with increasing pressure, the conversion percentage of methane and the ratio of methane to hydrogen also decreases. In addition, by adding a tri-reforming reactor to the unit operating in the temperature range of 800 to 850 ° C, the unit will have the best performance in terms of synthesis gas production.