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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Silver,Ethylene Epoxidation,Ethylene Oxide,Rhenium,Strontium Titanate
- چکیده:
- چکیده انگلیسی: CO2 plays the most important role in pollution due to greenhouse gases, which causes global warming and climate change. Unfortunately, CO2 emission has increased significantly in recent decades. So, it is crucial to capture CO2. On the other hand, CO2 can be utilized for commercial products. There is plenty of CO2 utilization such as enhanced oil recovery (EOR), producing methanol, salicylic acid, urea, and so on. This paper tries to consider the applications of CO2 emitted from ethane treatment units of the Asalouyeh gas processing plant. But selecting the best application is a complex issue. A multi-criteria decision-making method, fuzzy TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution), considering economic, technical, and environmental aspects have been used to find the best application for CO2 utilization. Considering 10 criteria and comparing options with sensitivity analysis in 32 different modes, the results show that methanol production is often the best option and salicylic acid production is the worst option. It should be noted that the increase in the harvest with a very close distance in the majority of cases is the second priority.
- انتشار مقاله: 25-12-1398
- نویسندگان: Gholamreza Salehi,Seyed Sajjad Jalali,Mohammad Sadegh Noroozieh,Mir Iraj Araghi
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Exergy analysis,exergy destruction,Olefin,Ethylene Plant,Exergetic Efficiency
- چکیده:
- چکیده انگلیسی: One of the industries with high potential for energy saving is the petrochemical industry. Ethylene and propylene production plants (olefin plants) – as a part of the petrochemical industry – are very energy intensive. So, any try to improve their energy consumption efficiency could lead to a high amount of energy saving. Iran’s petrochemical industry uses old technologies and components and due to sanctions, it couldn’t be improved. The main idea of this paper is to improve the energy consumption of one of the biggest petrochemical plants in Iran. So, Marun olefin plant in Iran has been simulated as a case study and its different parts have been analyzed from exergy point of view, which shows the most energy intensive components so that we can focus on for improving the plant’s energy consumption. The plant has been divided into three sections and simulated using Aspen HYSYS process simulation software. Then, it has been analyzed using exergy analysis. Results show that the hydrogenation and separation section consisting of many different components has the highest exergy destruction rate and the highest potential for energy saving. Compression section and refrigeration system having compressors are the other parts highly destroying exergy respectively. The causes of exergy destruction for each component has been analyzed and recommendations have been proposed as well
- انتشار مقاله: 11-10-1396
- نویسندگان: Mosayeb Paashang,Seyyed Mohammad Sharifi,Gholamreza Salehi
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: HRSG,Combined Cycle Power Plant,Stream splitting,Start up time
- چکیده:
- چکیده انگلیسی: One of the main components in combined cycles is the heat recovery steam generator (HRSG) which is responsible for energy recovery from gas turbine exhaust stream and produce superheated steam. In this paper, driving force plot and exergy analysis is used to study the behavior of heat exchangers of an HRSG in base case and off design conditions. The results indicated that performance of high pressure super heaters is far from their ideal operation. Based on this conclusion, a new configuration for the HRSG is proposed to boost its performance. This new configuration is based on split concept where it splits the hot flue gas to bypass the high pressure superheats. Therefore more energy is delivered to the high pressure evaporator and consequently steam production rate increases. Another advantage of this configuration is that it reduces start up time of the HRSG and consequently decreases start up time of the plant which results in higher flexibility of the system. To examine the applicability of the proposed approach, it is used to improve start up time in an existing combined cycle power plant. The results indicate that pressure and mass flow rate of HP stream reaches to its design point almost 20 minutes sooner. Finally, a sensitivity analysis is performed on the effect of split ratio on the power production. The results show that there is an optimum value for split ratio in which power production of steam turbine is maximized.
- انتشار مقاله: 06-03-1397
- نویسندگان: Seyed Abootorab Moosazadeh Moosavi,Mostafa Mafi,Abdolrazzagh Kaabi Nejadian,Gholamreza Salehi,Masoud Torabi Azad
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: modeling,Exergy,Simulation,partial Oxidation,Hydrogen production unit,exchange reaction of methane and steam
- چکیده:
- چکیده انگلیسی: The POXR and SMR methods adopted in producing hydrogen from methane gas are simulated and exergy analysis of both the processes are run for comparison. The effective parameters of the feeding materials ratio and the system temperature for maximizing hydrogen production and increasing efficiency are assessed here. Influenced by the changes in these parameters the unit efficiency is increased up to 76%. The efficiency of POXR and SMR processes are calculated for new ratios. The results indicate that SMR process has higher exergy efficiency than POXR process. Exergy efficiency of SMR and POXR processes are obtained as to 73.2 and 66.9, respectively, where the SMR efficiency process is increased by 2.6% because of the changes in the feeding material ratio and temperature. Highest destruction of exergy in methanator reactor in SMR process is due to high temperature of reaction caused by irreversibility from chemical reactions. Exergy destruction is reduced at high temperature and unit molar ratio.
- انتشار مقاله: 07-03-1395
- نویسندگان: Gholamreza Salehi,Shahab Farzin
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Pinch technology,Heat exchanger network,Debottlenecking,Throughput Increase
- چکیده:
- چکیده انگلیسی: For energy saving retrofit projects, its economics are usually evaluated in terms of capital investment and payback time. The capital investment is in direct relation to the total heat recovery area of the network and the payback time factor is base on both the area and the energy savings. The debottlenecking is an increased throughput, which can be profitable in economic sense. The combination of these two different objectives leads to a new definition of payback time, which differs, from the simple payback of savings to investment ratio. The correlation among area, energy savings and throughput increase is assessed based on pinch technology. The variation in energy savings and network area with throughput increase considering both economic factors of investment and payback time is reflected in the results. The decomposition approach is implemented as well, and its contribution in rapid detection of the most economical opportunity of network debottlenecking is discussed and the findings are diagramed separately. A visual software code is developed and validated in this study.
- انتشار مقاله: 13-07-1395
- نویسندگان: Sara Kafashian,Gholam Reza Salehi,Majid Amidpour
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Mixed Refrigerant Cycle,Low Temperature Process,Optimal Arrangement
- چکیده:
- چکیده انگلیسی:
A refrigeration cycle is a chain of various pieces of equipment including compressors, condensers, evaporators, and expansion devices each of which takes on a particular thermodynamic process duty in the cycle that eventually results in the production of the required refrigeration. The results of optimized mixed refrigerant cycles (MRCs) in Part I show that the configuration of MRC is an effective parameter in power consumption. In spite of simplicity of MRCs machinery configuration in comparison with a conventional cascade cycle, it is possible to imagine different configurations, providing the process required refrigeration, for these cycles. But the question here is how to find a configuration taking advantage of the existing complicated interactions between low temperature process and refrigeration cycle so that the maximum efficiency and the best functionality will be guaranteed. In this paper, based on the success of the systematic method proposed in part I for the optimal selection of refrigerant composition and operating pressures, the method is extended to give optimal arrangement of the cycle components. An illustrative example is presented to show how the proposed method can be utilized in order to achieve the optimal MRC configuration.
- انتشار مقاله: 13-07-1395
- نویسندگان: Mostafa Mafi,Bahram Ghorbani,Gholam Reza Salehi,Majid Amidpour,Seyed Mojtaba Mousavi Nayenian
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Simulated Annealing,Exergy analysis,Irreversibility Index,process simulation,Process Optimization
- چکیده:
- چکیده انگلیسی: Abstract: In this paper, an exergy analysis approach is proposed for optimal design of distillation column by using simulated annealing algorithm. First, the simulation of a distillation column was performed by using the shortcut results and irreversibility in each tray was obtained. The area beneath the exergy loss profile was used as Irreversibility Index in the whole column. Then, First Optimization Algorithm (simulated annealing, SA) was implemented to Grassroots (Number of tray (N) vs. Reflux Ratio (RR)) and Retrofit (Nof vs. Feed splitting) cases, respectively. Next, SA was used to find the maximum recovery in a simple column by seven different variables (Feed Temperature, Feed Pressure, Reflux Rate, Number of theoretical stage, Feed Trays (Feed Splitting, three variables)) simultaneously. During the search for maximum recovery, it was tried to find a better Irreversibility Index. In the second part, SA optimization algorithm was used for a complex column with one pump-around and feed splitter to find a better condition, which means to find the best location for pump-around and feed trays in Distillation column. The main objective in SA was to maximize the recovery of the desired component and to find a better minimum Irreversibility Index. This method was implemented in de-ethanizer in the first optimization without using pump-around with seven degrees of freedom, Recovery growth was 5.1% and reduction in irreversibility index was 3%. At the best Irreversibility Index, growth of recovery was about 3.7% and irreversibility index reduction was 25%. In the second optimization with pump-around or eight different variables, in the best condition, Recovery Growth was 6.2% but had a very high Irreversibility Index. At the best irreversibility index, recovery reduction was 17% but reduction in irreversibility index was about 21% comparing with initial point. As a result, it is shown that, regarding recovery and Irreversibility, pump-around shouldnât be used in a column. Without using pump-around, a better condition, considering both factors, can be achieved.
- انتشار مقاله: 26-03-1395
- نویسندگان: Gholam Reza Salehi,Majid Amidpour,Amir Salehi,Mostafa Maleki,Bahram Ghorbani
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: Mixed Refrigerant Cycle,Low Temperature Process,Optimal Operating Conditions
- چکیده:
- چکیده انگلیسی: Abstract: Minimizing the work consumed in refrigeration system is the most effective measure to reduce the cost of products in sub-ambient chemical processes. The introduction of mixed working fluids into refrigeration system in place of pure working fluids is a recent advancement applied in the field. Due to the lack of systematic design method for Mixed Refrigerant Cycle (MRC), conventional approaches are largely trial-and-error, and therefore, operations might be far away from Optimal operating conditions. In this paper, a novel method for systematic design of MRCs with a given configuration is presented. It combines the benefits of thermodynamics approach and mathematical optimization. An ethylene process was chosen as a typical example of low temperature process. The simulation results show that MRCs can improve the thermodynamic performance of refrigeration system in the case of using Optimal operating conditions and also proper arrangement of the cycle components (cycle configuration).
- انتشار مقاله: 26-03-1395
- نویسندگان: Mostafa Mafi,Majid Amidpour,Mojtaba Nayenian,Gholam Reza Salehi,Bahram Ghorbani
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: modeling,System identification,Debutanizer Column,Dynamic Neural Networks
- چکیده:
- چکیده انگلیسی: Â Abstract: In this paper, Artificial Neural Network (ANN) was used for modeling the nonlinear structure of a debutanizer column in a refinery gas process plant. The actual input-output data of the system were measured in order to be used for system identification based on root mean square error (RMSE) minimization approach. It was shown that the designed recurrent neural network is able to precisely predict and track the response of the actual system. The comparison between the results of this paper and those of the most recent published studies as NARX model indicates the significance of the proposed approach.
- انتشار مقاله: 26-03-1395
- نویسندگان: Majid Amidpour,Gholam Reza Salehi,Ali Ghaffari,Hamed Sahraei
- مشاهده
- جایگاه : پژوهشی
- مجله: Gas Processing Journal
- نوع مقاله: Journal Article
- کلمات کلیدی: optimization,modeling,Integration,distillation,Sequence,Expander
- چکیده:
- چکیده انگلیسی: Based on two
integration steps, an optimization framework is proposed in this work for the
synthesis and design of complex distillation sequence. The first step is to
employ heat integration in sequence and reduce the heat consumption and total
annual cost of the process. The second one is to increase the exergetic
efficiency of sequence by generating power in implemented expanders in
sequence. The profit of power generation directly affects the operating cost of
the process and decreases the total annual cost. In each step, the target is to
minimize the objective function of total annual cost. A simulator is used to
simulate the equipmentâs specification and formulate the objective function of
cost. Results from employing these two integration steps for the considered
case study show the advantages of such a complex distillation sequence with
heat integration and power generation. The results represent a very high
improvement for the sequence Indirect since the properties of the intake flow
to the process are in a way that in this sequence not only do we have a high
freedom for carrying out heat integration, but a large amount of power is also
produced between the columns due to having high flow rate flows between the
columns- انتشار مقاله: 26-03-1395
- نویسندگان: Gholam Reza Salehi,Bahram Ghorbani,Kazem Hasanzadeh Lashkajani,Majid Amidpour
- مشاهده