Inlet manifold tests and performance evaluation of dephlegmators in air-cooled steam condensers

• Main Author: Smit, Leslie van Zyl
• Other Authors: Kroger, D. G.
• Format: Others
• Language: en_ZA
• Published: Stellenbosch : Stellenbosch University 2012
• Subjects: Condensers (Steam); Heat exchangers; Power plants; Dissertations > Mechanical and mechatronic engineering; Theses > Mechanical and mechatronic engineering
• Online Access: http://hdl.handle.net/10019.1/51800

Thesis (MScEng)--University of Stellenbosch, 2000. === ENGLISH ABSTRACT: Measurements on air-cooled reflux steam condensers or dephlegmators at different power plants have shown that sections of these units do not transfer heat effectively over a range of operating conditions. The ineffective sections may be due to flooding in the finned tubes although entrainment of condensate in certain steam inlet manifolds is usually the main reason for the poor performance. In this dissertation factors that limit effective dephlegmator operation are discussed and the influence of two inlet manifold designs on dephlegmator operation is investigated. Laboratory experiments are conducted to show under which conditions liquid entrainment occurs and to visualize the flow distribution within the respective manifolds. An alternative, essentially horizontal arrangement of the dephlegmator is proposed. In order to evaluate the performance of such a system, the heat transfer and pressure drop on the steam-side is determined experimentally in an air-cooled finned tube. No flooding was observed during tests conducted at zero and negative tube angles to the horizontal. === AFRIKAANSE OPSOMMING: Toetse op lugverkoelde stoom terugvloeikondensors, of deflegmators, by verskeie kragstasies het getoon dat sekere dele van hierdie eenhede onder verskeie werkstoestande nie warmte effektief oordra nie. Hierdie oneffektiewe dele kan deur vloeding van die vinbuise veroorsaak word alhoewel die meesleur van kondensaat in sekere stoom inlaatspruitstukke gewoonlik die hoof oorsaak is. In hierdie dissertasie word faktore wat effektiewe deflegmator werksverrigting beinvloed bespreek en die invloed van twee inlaatspruitstukontwerpe op deflegmator werksverrigting ondersoek. Eksperimente is in 'n laboratorium uitgevoer om aan te toon onder watter werkstoestande vloeistof samesleping voorkom en om vloeiverdeling binne die onderskeie inlaatspruitstukke te visualiseer. 'n Altematiewe, wesenlike horisontale deflegmator opstelling word voorgestel. Die werksverrigting van hierdie voorstelling is ondersoek deur die warmteoordrag en stoorn-kant drukval eksperimenteel te bepaal in 'n lugverkoelde vinbuis. Geen vloeding is opgemerk vir toetsgevalle waar klein negatiewe of zero hoeke tot die horisontaal ondersoek is nie.