Showing 10 results for Gas
F. Golbabaei, S. Moradi Hanifi, H. Hassani, H. Shirkhanlo, M. Hossini,
Volume 3, Issue 3 (12-2013)
Abstract
Introduction: Pollutants in gas turbine air intake can cause erosion ،corrosion، fouling as well as reduction of power and efficiency of turbine and noticeable economic losses. In order to select the appropriate filtration system, air monitoring of turbine inlet and its filtration is essential. Therefore, this study was performed to assess the quality of gas turbines inlets in a gas power plant in Tehran.
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Material and Method: In this cross- sectional study, the concentration of particulates contained in air intake of 4 types of gas turbines, including: Fiat, Assec, Hitachi and mitsubishi were evaluated in second-half of spring season. For this means, 12 series of air samples were collected using 8 stages cascade Impactor, model AN -200 made by OGAWA company on cellulose – ester filters . The dust concentrations were determined gravimetrically in different ranges of sizes . Then the concentrations of 8 metals including Sodium, Potassiumu Lead, Mercury, Aluminum ,Copper and Cadmium were measured using ,Atomic Absorption Spectroscopy method and the data were statistically analyzed by SPSS Software, version16.
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Results: The results showed that the mean of particulate concentration with the diameter less than 4.7 µ were 64% ,66% ,60% ,67% for Fiat, Assec, Hitachi, mitsubishi respectively and it was 64.25% totally. The concentrations of all assessed metals in particulates less than 4.7 µ were greater than of larger than 5 µ. There were not any differences between particulate concentration in the inlet of Fiat and Hitachi (P>0.05), while in the case of other gas turbine intakes , there were statistically significant differences (P<0.05).
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Conclusion: Based on mass distribution of particles, the highest concentration belongs to particles with diameter of less than 4.7 µ. These particles could damage turbine blades, especially due to the presence of sodium and potassium as corrosive elements in this range (200 µg/m3). Therefore,this range of particle size must be considered in selecting the air intake filtration system.
H. Zohdirad , T. Ebadi, S. Givehchi,
Volume 6, Issue 1 (4-2016)
Abstract
Introduction: Leakage from process equipment and the entrance of flammable fluids to surrounding atmosphere may cause flammable gas cloud. The coincidence of flammable gas cloud with ignition source could make flash fire or vapor cloud explosion that cause injury and fatality. The concept of reduction of confluence of flammable gas cloud and potential sources of ignition is known as hazardous area classification. Several standards have provided methods regarding hazardous area classification; however, of the disadvantages of them are lack of an accurate determination of hazardous areas due to potential leakage sources which is because of low flexibility in process condition variation and equipment layout and also not considering effect of weather conditions and cumulative effects of release sources.
Method: In this paper, risk-based hazardous area classification is optimized using parameters such as the number of influencing release sources and weather condition probabilities. In this method, the determining factor of hazardous area boundary is the probability of acceptable ignition for every specific location. This probability is calculated using quantitative risk assessment with PHAST RISK software version 6.7 on the gas boosting unit of a gas refinery as a case study.
Result: The results of this method showed the full dependency of hazardous area boundary to cumulative effects of potential sources of release and the prevailing wind direction and it also demonstrated that the suggested optimized method can consider wind direction probabilities and cumulative effects of potential sources of release in risk-based hazardous area classification calculation.
Conclusion: Comparing the results of this method with the usual method determines that this method has some advantages such as considering all sources of release and cumulative sources of release and considering wind direction probabilities in determining boundary of zone 2 which makes the hazardous area classification very precise and flexible.
P. Heyrani, A. Baghaei,
Volume 6, Issue 1 (4-2016)
Abstract
Introduction: Nowadays, gas and oil account for 60 percent of world energy resources. Transporting crude oil and its products are accomplished through a number of ways among which pipelines are of the utmost significance. Considering the extent of pipelines in installation and residential areas and also high potential for damage, the safety of these pipes and application of risk management principles have undeniable importance. Bow-tie risk assessment method is one of the ways to determine safety level. The tool is a qualitative and semi-quantitative method the data of which are implemented by specialists and experts via conducting surveys.
Method and material: In the present study, Bow-tie technique was employed having been combined with fuzzy logic in which Likret Scale was applied to quantify the qualitative (verbal) data to reduce the uncertainty of risk evaluation of Amaak No.10 gas pipeline and Bongestan No.12 petroleum pipeline. In this way, factors affecting the pipeline safety were at first, recognized through the checklists. Then, the risk evaluation of pipplines was conducted using the mentioned method.
Results: The results of the study showed that third party damages, initial defects in materials, and constructing pipeline with failure possibility of 0.0484 stood at the highest in terms of importance (equivalent to 12.32%) in destroying oil and gas pipelines. In addition, the toxic impacts and environmental damages with occurrence possibility of 0.00327 were the most striking consequences of gas and oil leakage based on event tree analysis.
Conclusion: Considering the recognized factors leading to destruction of pipelines and their most notable outcomes, instructions on how to control and reduce the potential consequences were suggested, with emphasis on the removal of the most probable causes.
Saber Moradi Hanifi, Leila Omidi, Gholamreza Moradi,
Volume 9, Issue 1 (4-2019)
Abstract
Introduction: Fire and explosion are the most common consequences of natural gas pipeline accidents. The results of previous studies showed a higher rate of accidents in natural gas transmission lines. Given that a large number of people living in the vicinity of natural gas pipelines with a higher severity of related accidents. The aim of current study was to estimate risks using the method of quantitative calculation of risk and simulation of natural gas pipeline leakage using areal locations of hazardous atmospheres (ALOHA) in natural gas power generation.
Material and Methods: The method of quantitative calculation of risk was used to identify and prioritize risks. The simulation of the consequences of natural gas pipeline leakage was done by ALOHA software. Calculations of individual and social risks were performed based on statistical data obtained from the literature.
Results: The most serious effect of natural gas pipeline leakage was heat radiation effect of jet flame. Considering three leakage apertures in the natural gas pipeline 80, 130, and 300 mm, individual risks for each leakage aperture were 0.073, 0.114, and 0.569 and the number of deaths was 115, 400, and 3386, respectively. Increases in the leak aperture can lead to an increase in the number of deaths and decrease in the cumulative rate of accidents.
Conclusion: The most serious consequence of natural gas pipeline leakage was heat radiation effect of jet flame. The individual risk and social risk are beyond the acceptable risks range.
Faranak Najarian, Farideh Golbabaei, Asghar Ghahri, Kamal Azam,
Volume 9, Issue 4 (12-2019)
Abstract
Introduction: Occupational exposure to sevoflurane as an anesthetic gases in hospitals, dental clinics and veterinary clinics has been reported in various studies. Considering the harmful effects of sevoflurane anesthetic gas on the health of exposed personnel such as reproductive, preterm delivery and fetal abnormalities and increased spontaneous abortion, it is necessary to remove them from the air of the work environment, especially the treatment centers, with inexpensive and optimal methods. This study was aimed to compare two oxide-titanium based on Activated Carbon/ Graphene Oxide Nanosheets in nano and non-nano scales.
Material and Methods: Titanium oxide particles and nanoparticles were coated on actived carbon/ Graphene Oxide Nanosheets adsorbents. The prepared sorbents were characterized by instrumental techniques such as BET, SEM, XRD, FTIR and SEM-EDS to determine their properties. After characterization, the breakthrough and adsorption capacity of sevoflurane on both adsorbents were determined using the modified wheeler equation. Finally, the software of Microsoft Office Excel 2016 and SPSS Statistic version 21 IBM were used for statistical analysis of data.
Results: the results of XRD, SEM-EDAX analysis confirmed the stabilization of titanium oxide particles and nanoparticles on the sorbents. Furthermore, the FTIR results determined the functional groups on the sorbents. The BET results also showed the coating of titanium oxide nanoparticles on composite decreased the specific surface area of adsorption in comparison to adsorption containing titanium oxide particles. The adsorption capacity of the activated carbon/ Graphene Oxide Nanosheets coated with titanium oxide nanoparticles and titanium oxide particles were 240.7 and 210.5 mg sevoflurane per gram of sorbent, respectively (p-value<0.001).
Conclusion: The results showed that composite of activated carbon/nano oxide graphene coated with titanium oxide nanoparticles has a higher adsorption capacity of sevoflurane than other composite coated with titanium oxide particle, under the same conditions. This increase can be as a result of changes in surface chemistry (increase of the functional groups) in composite.
Younes Mehrifar, Zohreh Mohebian, Hamideh Bidel,
Volume 10, Issue 2 (5-2020)
Abstract
Introduction: Risk identification and investigation is an appropriate and practical approach for the occupational health professionals. This paper aims to determine exposure to the gases and metal fumes and to perform risk analysis in three common types of welding activities in a shipbuilding industry.
Material and method: This analytical cross-sectional study was conducted in a shipbuilding industry and three types of welding were considered including SMAW, MIG and MAG welding. Sampling of Mn and Cr fumes was carried out using NIOSH 7300 standard method, and NIOSH 6014 method NO2 sampling, and also direct reading devices for CO and O3 gases. Moreover, SQCRA risk assessment method was adopted to specify the level of exposure risk.
Results: The results of risk analysis showed that among gas pollutants, O3 and NO2 in all welding processes had a very high-risk level, while among the metal pollutants; Mn metal showed a high and very high risk level in MIG and SMAW welding.
Conclusion: According to the both sampling results and risk analysis, MIG process welders are more dangerous position than other types of welding.
Seyedeh Reyhaneh Shams, Ali Jahani, Mazaher Moeinaddini, Nematallah Khorasani, Saba Kalantary,
Volume 10, Issue 4 (11-2020)
Abstract
Introduction: As a metropolitan area in Iran, Tehran is exposed to damage from air pollution due to its large population and pollutants from various sources. Accordingly, research on damage induced by air pollution in this city seems necessary. The main purpose of this study was to forecast ozone in the city of Tehran. Considering the hazards of ozone (O3) gas on human health and the environment and its ascending trend over the past decades, it is also essential to study and predict its quantities in the air. Forecasting ozone in the air can be further used to prevent and control pollution by authorities.
Material and Methods: Using an analytical-applied research method, this study was to predict ozone gas in this metropolitan area via daily ozone data of air quality measurement stations, traffic variables, green space, as well as time factors such as one-day time delay. In this regard, an artificial neural network (ANN) model was employed to forecast ozone concentration using the MATLAB software.
Results: The results of the ANN model were compared with a linear regression one. Correlation coefficient and root-mean-square error (RMSE) of the ANN model were subsequently compared with R2=0.734 and RMSE=0.56 as well as R2=0.608 and RMSE=11.69 regression equations.
Conclusion: It was concluded that the error in the ANN model was smaller than that in the regression one. According to the results of the sensitivity analysis of the season parameters, the length of sunshine hours had the most significant effect on the amount of ozone gas in Tehran air.
Mostafa Mirzaei Aliabadi, Hossein Ramezani, Omid Kalatpour,
Volume 12, Issue 1 (3-2022)
Abstract
Introduction: In process industries, some of the primary events may result in secondary events in an industrial unit called the domino effect. Since refinery storage tanks are always at risk of fire and explosion, quantitative risk assessment is important in determining the severity and outcome of an accident, taking into account the effects of dominoes on the main industry, neighbors, and society and can play an important role in risk management. Therefore, the purpose of this study was to quantitatively evaluate the risk of condensate storage tanks taking into account the domino effect.
Material and Methods: The technique used in this study was Quantitative Risk Assessment (QRA), the analysis of the consequences of which was performed using PHAST (7.22) after setting goals, studying the process, identifying hazards and scenarios. Then, to determine the extent of the domino effects of the escalation vectors were matched against the threshold, and after screening, the overall vulnerability of the repositories for mapping individual risk levels was calculated.
Results: In the leakage scenario, after considering the domino effects, the risk contour 10-4 to about 250 meters and the risk contour 10-5 to about 400 meters increased. Also in the catastrophic rupture scenario, the radius of risk contour of the 10-5 increased to100 m after considering the domino effects up to around damage tank.
Conclusion: As can be deduced from the results, using this method can give a clear picture of the consequences of chain events and the probability of damage to nearby employees, equipment and neighbors, which is very important in risk, emergency and crisis management.
Ali Fardi, Mohammad Karkhaneh, Hamidreza Heidari, Abolfazl Mohammadbeigi, Ahmad Soltanzadeh,
Volume 12, Issue 2 (6-2022)
Abstract
Introduction: Methane is one of the most widely used gases in industries with a high flammability potential. This study aimed to evaluate the efficiency of ventilation systems installed on methane valve pits based on hazardous areas classification.
Material and Methods: This study was implemented in a steel industry in Qom Province in 2019. The tools used in this study were a DELTA OHM pitot tube (DO-2003) to measure wind speed, EPA Protocol for equipment leak emission estimates (U.S. Environmental Protection Agency) and IEC-60079-10 for evaluating the safety of ventilation of methane valve pits.
Results: The methane LELm was about 0.0334 kg/m3, and the volume of the release area was approximately VZ = 0.053 m3. The expected leak emissions were within the Vz < 0.1 m3 range. The ventilation system embedded on methane distribution pipelines was not effective for openings with diameters of more than 0.3 mm and the volume of gas inside the valve pits would quickly exceed high ventilation border which might lead to a dangerous accumulation of gas in the valve pits.
Conclusion: Given that a very small opening or leak in gas transmission valves may lead to the formation of an explosive atmosphere, it is essential to monitor methane before entering the valve pit area and performing any operations on valve pits.
Alireza Askarian, Mahnaz Mirza Ebrahim Tehrani, Seyed Mohammad Taghi Sadatipour, Seyed Ali Jozi, Reza Marandi,
Volume 12, Issue 4 (12-2022)
Abstract
Introduction: Unit risk management is a critical component of gas refining management, as risks that are not well-managed may lead to trip production failures. The present study aimed to provide a structural model for investigating the role and effect of different variables on stopping the gas production process in the gas refinery.
Material and Methods: This study was a retrospective cross-sectional and systematic analysis, which was carried out on key risks in the trip gas sweetening unit in a gas refinery industry located in Asaluyeh, Iran. The systems analysis was applied by using Fishbone Diagram, and then data modeling was prepared by Structural Equation Modeling (SEM) for an incident that occurred during gas sweetening production. Tools for the data analysis included the SPSS 24 and Smart PLS 2 software.
Results: Results of this research indicate that “Environment Risk” with a path coefficient of 0.943 and T- Value of 103.791; “Cost Risk” with a path coefficient of 0.937 and T- Value of 95.168; “Implementation of management system Risk” with a path coefficient of 0.847 and T- Value of 35.23; “Accident Risk” with path coefficient of 0.577 and T- Value of 25.410; “Time Risk” with path coefficient of 0.758 and T- Value of 15.121; “Human Error Risk” with path coefficient of 0.712 and T- Value of 11.215 had the most important coefficients of the paths respectively, that are effective in stopping production concerning other risks. Also, by comparing the path coefficients of the risks we can see that the impact of each of the risks on stopping production is different.
Conclusion: The findings of the present study revealed that a combination of variables can affect stopping production in the gas industry. Therefore, the role of these risks in losses in the refinery system should be investigated.
