Industrial application of Computational Fluid Dynamics (CFD) requires the solution of complex fluid-flow problems in conjunction with equipment design, process and product development and optimization. For the successful solution of these problems, a high degree of coordination between industrial CFD engineers, software developers, consultants and academic scientists is necessary. In a refinery, CFD may be applied to a variety of problems. In particular, combustion, flames, flares and chemical reaction are of interest because of the physics and the complex nature of the process. Two applications are presented in this paper to demonstrate the use of CFD modeling for improving furnace operations. The first concerns improvements in reboiler operation by changing burner arrangement. A three-burner arrangement has resulted in tube burnout in the past. CFD modeling suggested a four-burner arrangement is better. The recommendation was accepted and implemented by the refinery in 2002. Feedback from the refinery suggests a much cooler furnace operation is observed in the field. The second application concerns predicting Coker furnace operation of as yet uninstalled heater. The Coker radiant section is modeled with 4 burners. Predicting the impact of burner-burner interaction on the radiant heat flux helps in determining the time period for decoke. Several mitigation steps are suggested to increase the run length between decoking intervals. Further recommendation to create a balanced heat flux profile is provided.
Industrial application of Computational Fluid Dynamics (CFD) are varied and many. However CFD requires the solution of complex fluid-flow problems in conjunction with equipment design, process and product development and optimization. The solution of such complex problems is possible through the coordination between industrial CFD engineers, software developers, consultants and academic scientists. In the petrochemical industry, CFD may be used for a variety of purposes such as air recirculation studies in LNG plants, burners in coker furnaces, multiphase studies in heat exchangers to name just a few. In particular combustion, flames, flares and chemical reaction are of interest because of the physics and the complex nature of the process. The topic selected for this presentation is the study of wet ground flares during a large-scale propane release and the effect of the radiation release on the environment and surrounding buildings and vegetation. The flare characteristics and radiation on the surrounding terrain form an integral part of the information required by the National standard for “Control of Major Hazard Facilities”. The study of individual flames from each burner with nozzles of the order of 1mm and the effect of 180 burners in a large area and surrounding terrain with length scales of several hundred meters make up a very intriguing problem of varying length scales. The results of this analysis are presented concentrating on the effects during the large scale conflagration event on the surrounding buildings, vegetation, aircraft, hills and mangroves.
The bending of large pipes due to temperature differentials between the bottom and top of the pipe is a very serious problem. The temperature differentials can either be caused by extremely cold liquids (such as methane or ethylene flowing from a lateral into a flare header) or hot liquids flowing at the bottom of a piping system (such as in a Vacuum transfer line) while the top is exposed to atmospheric conditions. In some cases liquids may be produced by Joule-Thompson cooling of high pressure cold gas as it expands through a safety-relief or emergency depressurization valve. The liquid so formed can accumulate, for example, on the dead leg side of a flare header. The differential expansion can deform the pipe so that it lifts off its supports. It takes a finite amount of time for the heat transfer by conduction to equilibrate the temperature to a more benign level. The initial stresses induced due to large thermal differential may even cause the pipe to crack in the region of the supports and T-joints to the laterals. This phenomenon has been observed in several industries, most predominantly in the petrochemical industry. This paper recounts the use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to study this important phenomenon. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow re´gime. Multiphase flows with heat transfer are analyzed using CFD. The temperatures on the walls of the pipe system are then transferred to the FEA and analyzed for heat transfer and thermal stresses. These stresses are compared to ASME standards to see if they are within allowable limits. This paper also recounts efforts to reduce the bending effect by preventing liquid accumulation on the dead leg side. Other methods that provide better supports for bent piping are studied. Further, methods of equilibrating the temperature faster to prevent the bowing of the pipe are also studied. It is hoped that this presentation will benefit people designing piping networks with varying liquid and vapor traffic.
The bending of large pipes due to temperature differentials between the bottom and top of the pipe is a very serious problem. The temperature differentials can either be caused by extremely cold liquids (such as methane or ethylene flowing from a lateral into a flare header) or hot liquids flowing at the bottom of a piping system (such as in a Vacuum transfer line) while the top is exposed to atmospheric conditions. In some cases liquids may be produced by Joule-Thompson cooling of high pressure cold gas as it expands through a safety-relief or emergency depressurization valve. The liquid so formed can accumulate, for example, on the dead leg side of a flare header. The differential expansion can deform the pipe so that it lifts off its supports. It takes a finite amount of time for the heat transfer by conduction to equilibrate the temperature to a more benign level. The initial stresses induced due to large thermal differential may even cause the pipe to crack in the region of the supports and T-joints to the laterals. This phenomenon has been observed in several industries, most predominantly in the petrochemical industry. This paper recounts the use of Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to study this important phenomenon. The liquid flowing from the lateral into the main header pipe is multiphase in the dispersed, stratified, slug or annular flow re´gime. Multiphase flows with heat transfer are analyzed using CFD. The temperatures on the walls of the pipe system are then transferred to the FEA and analyzed for heat transfer and thermal stresses. These stresses are compared to ASME standards to see if they are within allowable limits. This paper also recounts efforts to reduce the bending effect by preventing liquid accumulation on the dead leg side. Other methods that provide better supports for bent piping are studied. Further, methods of equilibrating the temperature faster to prevent the bowing of the pipe are also studied. It is hoped that this presentation will benefit people designing piping networks with varying liquid and vapor traffic by providing a safe environment free of cracks and spills.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.