Performance Tests of the Condensate Drain Pots at Wairakei

Abstract

As part of the investigation for a solution to the corrosion problem of the steam mains at Wairakei, the performance of the condensate drain pots was tested. Air-water model tests suggested that the typical shallow drain pots at Wairakei were not very efficient and that the efficiency could be improved by increasing the depth of the drain pot or by installing a baffle in the drain pot to destroy the vortex that caused the inefficiency. Deepening a shallow drain at Wairakei confirmed the finding of the model tests. Installing a baffle plate in each of two consecutive drain pots of a steam main enabled the efficiencies of the drain pots to be quantified and improvements in the efficiencies were clearly demonstrated. No significant effect by the baffle plate on the drain pot pressure drop was detected, however the pressure drop coefficient of a drain pot having the same diameter as the steam main was approximately twice that of a drain pot of thirds the pipe diameter.