A Mathematical Model for Study of Cyclic Purge in Vessels with Complex Geometry
Abstract
Removal of impurities from stagnant regions in process vessels and flow components is a major bottleneck of purge operations and typically associated with large downtimes and UHP gas consumption. A comprehensive mathematical model is developed for study of the purge process in chambers with complex geometry and stagnant regions inaccessible to gas flow. The model takes into account the dynamics of removing impurities in the gas phase as well as those adsorbed on the chamber surfaces. Using this model, the conventional Steady State Purge (SSP) is compared with a proposed unsteady Pressure Cyclic Purge (PCP) technique. PCP is found to be advantageous over SSP in terms of gas usage and purge time required to reach a given target cleanliness. The effects of a number of key design and operational parameters such as chamber geometry, pressure range, and cycling pattern are investigated. The results show that the model is a powerful tool for finding the optimum operating conditions for purging a system.
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PEARLSTEIN, Ronald M., KERRY, Berger R., CHRISTOPHER, Hartz L., and JEFF, Fregger. Evaluating electronics-grade gas-line purging requirements. Solid State Technology, 2001, vol. 44, no. 3, pp. 119-128.
DHEANDHANOO, Seksan, YANG, James, CIOTTI, Ralph and YESENOFSKI, David. Empirical Validation of a Gas Distribution System Moisture Drydown Model. Journal of the IEST, 1998, vol. 41, no. 2, p. 33-38.
DHEANDHANOO, Seksan, JAMES, Yang H., and MICHAEL, Wagner D. Modeling the characteristics of gas system dry-down. Solid State Technology, 2001, vol. 44, no. 6, p. 125-134.
JAMES, Kubus M., GREGORY, Leggett H. Piping system dry down predictions with field verification. In: Microcontamination Conference Proceedings, 1993. pp. 212-221.
YANG, Tian-Shiang, WU, Chuan-Hsieh and YEH, Chia-Feng. Analysis of moisture purge in high purity gas distribution systems. International Journal of Heat and Mass Transfer, 2006, vol. 49, no. 9-10, p. 1753-1759.
YAO, Junpin, WANG, Hao, DITTLER, Roy, GEISERT, Carl and SHADMAN, Farhang. Application of pressure-cycle purge (PCP) in dry-down of ultra-high-purity gas distribution systems. Chemical Engineering Science, 2010, Vol. 65, no. 17, p. 5041-5050.
KISHORE, Jivaan, SHADMAN, Farhang, DITTLER, Roy and CARL, Geisert. Pressure cycling for purging of dead spaces in high-purity gas delivery systems. AIChE Journal, 2015, Vol. 61, no. 11, p. 3973-3980.
VERMA, Nishith K., HAIDER, Asad M., and FARHANG, Shadman. Contamination of Ultrapure Systems by Back‐Diffusion of Gaseous Impurities. Journal of the Electrochemical Society, 1993, vol. 140, no. 5, p. 1459-1463.
DITTLER, Roy, KISHORE, Jivaan, GEISERT, Carl and SHADMAN, Farhang. Contamination of Ultra-High-Purity (UHP) Gas Distribution Systems by Back Diffusion of Impurities. Journal of the IEST, 2014, Vol. 57, no. 1, p. 63-76.
PANTON, Ronald L. Incompressible Flow, 2nd ed., John Wiley & Sons, 1996.
BRODKEY, Robert S., and HARRY, Hershey C. Transport phenomena: a unified approach. Vol. 2. Brodkey Publishing, 2003.
SIEFERING, Kevin L., and WALTER, Whitlock H. Measurement and modeling of moisture adsorption properties of 316 stainless steel tubing samples. Journal of Vacuum Science Technology, 1994, A 12, no.5, pp. 2685–2691.
U.S. Army Corps of Engineers. Engineering and Design Liquid Process Piping. Department of the Army, Engineering Manual No.1110-1-4008, 1999.
COMSOL, A. Comsol Multiphysics Reference Manual, Tegnérgatan, Stockholm, Sweden, 2013.
GGAKHELADZE, L., GELASHVILI, G., MDIVNISHVILI, M., NANOBASHVILI, I., NANOBASHVILI, S., and ROSTOMASHVILI, G.I. Shock wave propagation in gases under subatmospheric pressure. Czechoslovak journal of physics, 1999, vol. 49, no. 6, pp. 993-997.
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