جستجوی مقالات مرتبط با کلیدواژه « Pipeline » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

The pipeline transportation of natural gas serves as a conventional and economical method for transmitting natural gas, making it crucial to investigate for reducing pressure drop and preventing the occurrence of two-phase fluid formation. To address these concerns, this study delves with the transport of natural gas under supercritical conditions. Under such supercritical conditions, the gas temperature must be between the critical temperature and the maximum temperature within the two-phase region, while the gas pressure must exceed the maximum pressure within this region. The main objective of this study is to simulate natural gas pipeline behavior under supercritical and two-phase conditions utilizing Aspen Plus software version 12.1. The Peng-Robinson equation was employed to compute thermodynamic properties for pipeline simulation. Validation of pipeline simulations indicate a maximum relative error of 4.5% between simulated and actual pipeline data, demonstrating satisfactory agreement between simulation and pipeline data. After validation, pressure drop, temperature variations, density variations, and associated costs under supercritical and two-phase conditions were investigated. Findings reveal that under supercritical conditions, the pressure drop is three times less compared to two-phase conditions. Additionally, temperature reduction under supercritical conditions amounts to 21%, contrasting with a 53% reduction in two-phase conditions. Density variations in supercritical and two-phase states were approximately 5% and 36%, respectively. Finally, it was found that the cost of the total energy consumption required per year in supercritical and two-phase mode is almost similar and is equal to 1,860,000 and 1,831,000 dollars per year, respectively.

By using satellite geographic data, the control point of the 20-inch Sabzevar-Mashhad pipeline, which is located after Imam Taghi pump station, has been identified. A pressure transmitter is installed at the entrance of Imam Taghi pump station. In this study, by using the results of hydraulic and energy modeling of the pipeline with related software, the necessary calculations for placing this transmitter as a basis for pressure control in the 20-inch Sabzevar-Mashhad line have been performed. Also, the current state of operation of the line and its difference to the optimal conditions have been investigated and the improvement potentials have been identified. In the current operation method, the pressure at the control point is performed by performing hydraulic calculations on the pipeline profile map, which has led to the existence of additional pressure at the control point due to the error in this method. With the proposed operation method of this line and by modifying the operating procedures in the form of continuous monitoring and control of the pressure at the control point of this part of the pipeline using a pressure transmitter in the Imam Taqi pump station, as an alternative solution for performing pressure calculations. According to the profile maps of the pipeline, it is possible to increase the capacity of this part of the pipeline up to 230 million liters per year with the same consumption power, and it is also possible to save up to 593000 m3 of natural gas worth 4 billion Rial, with the same transfer volume. (Equivalent to one month's energy consumption of Sabzevar pump station’s turbines). In addition to the above, using this method reduces the operating hours of Sabzevar turbo pumps by 574 hours per year.

The use of carbon steel is conventional for the transmission and distribution of treated natural gas. In order to control the internal corrosion of the gas transfer pipelines, the moisture content is removed in dehydration unit. In addition, the amount of CO2 gas is limited to less than 2%. In this study, the cause of the failure of an 8-inch gas distribution pipeline is investigated. The pipeline was not in service for two years and then it was in operation for 6 years before the failure. Microscopic examinations, as well as chemical analyzes such as EDS and XRD, were used to determine the possible mechanisms of damage. In addition, the NORSOK CO2 corrosion model was used to determine the corrosion rate in operating conditions. The results showed that corrosion caused by carbon dioxide is the most likely cause of internal corrosion of the pipeline and the occurrence of the leakage.

The production of waxy crude oils from the oil fields is costly, complex, and has various problems depending on the conditions of each oil field and oil composition, among others. The majority of crude oils and their products contain substantial amounts of waxes called paraffin. The waxy crude oil behavior is a non-Newtonian flow behavior. This behavior causes complex equations. OLGA as a specialized software application is used for fluid transfer systems. In this work, simulation of waxy crude oil pipe line using by OLGA SOFTWARE was done. The obtained profiles include temperature, pressure, and thickness of wax layer at wall of pipeline. Also, the heat transfer coefficient of variation in the length at different times is obtained in this study.

We consider the problem of designing a new natural gas transmission network and expanding an existing network while minimizing the total investment and operating costs. We develop a mixed-integer nonlinear optimization model to determine pipelines in the network, compressor stations with their capacity as a variable, and their instalation schedule in a multi-period planning horizon. The model further decides on the amount of the produced natural gas in the steady-state flow for each period in the network. The model is solvable using Baron solver in Gams. We conduct computational studies on various cases generated using realistic network structure and data based on the natural gas network in Iran. Our analysis provides insights into sensitivity of network configuration and operations within different periods in the planning horizon and cost parameters of natural gas networks. Result proved 30 percentage decrease in cost of gas network transmission.

Pipelines are used to transport products mainly in the oil and gas industry. For effective operation, the pipelines must be pigged in periods of time. For a suitable performance, pigs should move at a constant velocity. It seems that the study of fluid flow around a moving pig, the pig dynamics and also, estimation of the pig movement variables is essential to control pig velocity. In this research, fluid flow around moving pig in pipeline is simulated by ANSYS CFX. At first, the force on static pig in pipeline for the different bypasses was obtained and compared with the previous study and the good agreement has been observed. Then,for mesh movement around moving pig in pipeline the remeshing method in the dynamic mesh technique was used. up and downstream distribution of pig and also velocity, acceleration and position of pig in different time are obtianed. Therefore, the Navier-Stokes equations for uncompressible viscous fluid flow are solved. The k-εturbulence model is used to simulate turbulence. In the study of pig movement through the pipe, the result showed that at first, the fluid force on pig is high and as time goes on, is reduced becouse the relative velocity between the pig and fluid flow is decreased and become equal to external force (friction force) so the net force on pig get zero. Thus, the pig acceleration is approaching to zero and the pig velocity is being constant. Also as pig goes forward the velocity and pressure through the pipe decrease because of pig acceleration reduction. So that the fluid condition becomes permanent. In the study of effect of pig on fluid velocity through the pipe, it is obvious that the most effect is on fluid velocity in pig output and in the long distance from the pig the it’s changes is low.

There are several ways to transport heavy crude oil; one of these, is emulsion method. The goal of this study is tocomparethe effective factors in transferring heavy crude oil in pipeline with and without emulsion method. In this paper, a heavy crude oil samplewith about15 API degrees is used. The HYSYS software is used to simulate the oil transmission and the results from these two conditions are compared. The results show that using emulsion method would cause the pressure to decrease about 6042.3 K Pa in pipeline. This pressure drop indicates that the emulsion method requires lower energy for crude oil transmission in pipeline. The difference of pump’s power for heavy crude oil transmission in pipeline by the two mentioned methods has been 132.49 KW.