Analytical Study of Coke Drum Skirt Support Hot Box
Nirmal Pravin Chandra1, S. B. Belkar2
1Nirmal Pravin Chandra, Department of Mechanical Engineering, PREC, Loni, India.
2Prof. S. B. Belkar, Head of Department, Department of Mechanical Engineering, PREC, Loni, India.
Manuscript received on July 19, 2014. | Revised Manuscript received on July 20, 2014. | Manuscript published on July 25, 2014. | PP:1-6 | Volume-2 Issue-9, July 2014. | Retrieval Number: E0668032514/2014©BEIESP
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© The Authors. Published By: Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: Delayed coke drums are operated under severe conditions of cyclic heating and forced cooling that apply repetitive thermal stresses to the drum walls and the skirt. Since thermal cycling is most severe near the bottom of the coke drum, where temperatures can reach up to 1000°F, the skirt and other attachment welds are just as prone to cracking and premature structural failure as the vessel wall. The purpose is to determine a skirt / “Hot-box” junction geometry which will minimize thermal gradient stresses and improve fatigue life. The process flow of coke drum along with the temperature gradient due to coking process and the effect of thermal stresses on the skirt shell junction/ hot-box using finite element model. In present project work comparative analysis of hot box is done by analytical, FEA using ANSYS 13. Study demonstrates that by modifying the dimensions of the hot box such as length, will affects the fatigue life of coke drum. This appears to be due to the longer hot-box length, which results in a more gradual thermal gradient and also moves the gradient lower on the skirt away from the welded connection.
Keywords: Coke drum, Hot box, fatigue life