Stratification transients in steam transporting pipes
- Sargent and Lundy, Chicago, IL (United States)
Thermal stratification may occur in horizontal piping segments due to temperature difference and lack of mixing between fluid layers. This results in nonuniform temperature transient profiles across the pipe sections that escalates the low cycle fatigue degradation of the concerned piping system. In the specific case of steam transporting pipes, the incipient warmup after a prolonged cold shutdown would result in steam condensation on the pipe walls. The temperature of accumulated condensate at the bottom of horizontal pipe segments is initially cooler than that of incoming hot steam flowing above it. In addition, the saturated steam high heat flux transfer, as it condenses on the upper portions of the pipe wall, is at least two orders of magnitude higher than the heat flux at the condensate-covered wetted bottom wall of the pipe. This condition generates stratified temperature transient profiles across the horizontal pipe sections. In this paper, the complex phenomenon of the thermal stratification in steam transporting pipes is parametrically investigated. The severity of the thermal stratification transients depends upon parameters such as pressure, steam quality, drainage efficiency, pipe size, material, and routing. The author used simplified finite difference heat transfer models to investigate the influences of these parameters. The resulting maximum linear, nonlinear, and average top to bottom temperature distributions are presented. The associated decay level at 1,000 seconds is also presented. In this paper, basic formulations used in the simplified finite difference heat transfer thermal stratification modeling are introduced. The parametric investigations are intended to provide the piping design engineers with load estimates resulting from the thermal stratification in steam transporting pipes.
- OSTI ID:
- 404278
- Report Number(s):
- CONF-960706-; ISBN 0-7918-1785-7; TRN: IM9652%%138
- Resource Relation:
- Conference: American Society of Mechanical Engineers (ASME) pressure vessels and piping conference, Montreal (Canada), 21-26 Jul 1996; Other Information: PBD: 1996; Related Information: Is Part Of Pressure vessels and piping codes and standards: Volume 1. PVP-Volume 338; Esselman, T.C. [ed.] [Altran Corp., Boston, MA (United States)]; Adams, T.M. [ed.] [Stevenson and Associates, Cleveland, OH (United States)]; Bhavnani, D. [ed.] [Public Service Electric and Gas Co., Hancock`s Bridge, NJ (United States)]; Cofie, N.G. [ed.] [Structural Integrity Associates, Inc., San Jose, CA (United States)]; Jones, D.P. [ed.] [Westinghouse Electric Corp., West Mifflin, PA (United States)]; Olson, D.E. [ed.] [Sargent and Lundy, Chicago, IL (United States)]; Thailer, H.J. [ed.] [Pacific Gas and Electric Co., San Francisco, CA (United States)]; PB: 295 p.
- Country of Publication:
- United States
- Language:
- English
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