Typical Differential Pressure in psiLiquid Flow gpmGaseous Flow scfm Pipe I.D.for Launchingfor Running3 fps5 fps5 fps10 fps 2" 100-200 40-100 30 50 21 98 3" 100-150 35-85 70 100 46 172 4" 75-125 30-80 120 200 70… This paper deals with the dynamic model of the process of a normal pig restarting from a stoppage in horizontal gas pipeline.
As shown in Figures Response surface methodology (RSM) is a statistical experimental method for optimizing stochastic processes. Therefore, the velocity of gas at the tail and nose of the pig is equal to that of the pig [Three kinds of boundary conditions are used: (1) constant inlet flow rate and constant pressure at the outlet, simulating the releasing of a stuck pig by increasing upstream pressure; (2) constant inlet pressure and constant flow rate at the outlet, simulating the releasing of a stuck pig by pressure relief of downstream; (3) constant inlet flow rate and the outlet pressure to decrease in the rate of inlet pressure increase, which simulates the unstuck pig in the way of inlet pressurization together with outlet relief.To simulate the pigging process in gas pipeline, the pipe is divided into two sections: one behind the pig and the other in front of it. (4) The stiffness of the pipeline is large enough to keep the diameter unchanged during pigging.The transient flow dynamics can be modeled based on the continuity equation, momentum equation, and energy equation, respectively, as follows [To analyze the restarting process of a pig in horizontal gas pipeline, we made the following assumption: the pig stopped in the pipeline and the gas stopped flowing. (a) Pig is released by increasing upstream pressure; (b) pig is released by decreasing downstream pressure; (c) pig is unlocked in the way of inlet pressurization together with outlet relief.Distributions of gas parameters. Miles of Pipe. Runge-Kutta method is used for solving the pig speed equation. © 2020 Pigs Unlimited International LLC.
It promotes weight gain in the pigs and keeps them healthy. Moreover, the maximum speed a pig reaches, in the way of inlet pressurization together with outlet relief, is generally between the maximum speed corresponding to the inlet pressurization and that of outlet relief. Furthermore, response surface methodology (RSM) is used to study the maximum speed of pig. Based on the results of the RSM simulations, an empirical formula is present to predict the maximum speed of a pig restarting from a stoppage in gas pipeline.The following assumptions are adopted to simplify the model:(2) The fluid in the pipeline is a single-phase gas. Scroll Down. This paper presents the modeling of a pig restarting from a stoppage in gas pipeline. Pigging is a common operation in the oil and gas industry. ID 1,436.5-m (4,740.5-ft) test pipeline. Any author submitting a COVID-19 paper should notify us at Computational scheme for solving the coupling process of pigging.Pig speed variation due to different pressure strategies to release the pig from the stoppage.Pressure on the nose and tail of the pig. Desired Fill Time in Hours. It means at the initial moment, the gas velocity is zero and the pressure is equal everywhere.It is assumed that the upstream and downstream gas flows are fully coupled to the pig.
The equations for unsteady gas flow in pipe are solved by MOC. All Rights Reserved Values of the parameters adopted are shown in Table Pressure on the nose and tail of the pig in the three conditions is shown in Figure The distributions of gas parameters are shown in Figure Parametric sensitivity analysis of pig restarting from a stoppage in a horizontal gas pipeline is then carried out.
Model graphs of the obtained formulas are shown in Figure A calculation scheme using MOC to solve the equations of gas flow for estimating the pig dynamics has been shown. To release a pig from a stoppage in the way of increasing upstream pressure of decreasing downstream pressure is discussed. (a) Change of pig mass, (b) change of pipe diameter, (c) change of the stuck position, (d) change of pipe length, (e) change of obstruction force, and (f) change of gas pressure.Parametric sensitivity analysis of pig restarting from a stoppage by decreasing downstream pressure. Our mission is to be a leader and innovator of comprehensive pigging products and services in the pigging industry and to service our customers with 100% satisfaction. Because of the compressibility of the gas, starting up a pipeline inspection gauge (pig) from a stoppage can generate a very high speed of the pig, which is dangerous to the pipe and the pig itself. Pigging Formulas; Gallons per Minute(gpm) to Velocity, in feet per second (fps) Gallons per Minute(gpm) to Velocity, in feet per second (fps) Internal Pipe Diameter (i.d. Then the differential pressure between pig tail and nose is gotten from MOC results. If using a particular tool or method achieves similar results every time it is used, it has high precision, such as stepping on a scale several times in a row and getting the same weight every time. The process of a pig restarting from a stoppage in a horizontal gas pipe is simulated. Hence, an empirical formula for estimating the maximum speed a pig achieves from a restarting process, obtained from the average of the three results of the RSM simulations, is as follows. Figure As the pig moves across one or more grids during time step In this section, a 6 km horizontal gas pipeline is used for the simulation of pig restarting from a stoppage. There are two formulas for calculating standard deviation, with a very slight difference between them. Thank you for visiting our website and for your interest in Pigs Unlimited International, LLC. The process of a pig restarting from a stoppage in gas pipeline is simulated. The empirical formulas obtained would contribute to pig design and safe pigging.The data used to support the findings of this study are available from the corresponding author upon request.The authors declare that they have no conflicts of interest.This research was supported by the Graduate Innovation Foundation of School of Mechatronic Engineering of SWPU (CX2014BY09).Copyright © 2019 Honggang He and Zheng Liang. Custom products for any pipeline application. You will use one formula if your measured data represents an entire population. Pigging Formulas.