Recovery of MWe Capacity Through Condenser Improvements

Harpster, J.W. & Rubin, L.J.
“Recovery of MWe Capacity Through Condenser Improvements” EPRI NPPI Conference, Austin, TX, June 28-29, 2004.

Abstract

Throughout the 20th century, condenser performance limitations associated with steam flow dynamics have been poorly understood.  Designers relied heavily, and still do today, on prior ad-hoc experience, often resulting in oversized condenser designs and continual tinkering with tube sheet layouts in the hope of capturing benefit from experience-based inputs.  Uncertain design consideration can manifest itself in missed functions, features or specifications, in material additions to project costs, and finally in less-than-optimal performance and consequent loss of value.

A common condenser design problem is excessive air binding.  This phenomenon will cause higher than anticipated back pressure and Dissolved Oxygen (DO) in condenser condensate, contributing to lost load, corrosion and corrosion byproduct deposition.  Each of these conditions can contribute to reduced availability in nuclear plants, forced outages, excessive boiler cleaning needs, and significant lost revenues associated with them.

A science-based engineering service program is described in this paper.  It is now possible - through improved understanding of steam dynamics - to analyze condenser design configurations and engineer retrofits of existing condensers to eliminate identified historical design deficiencies.  As an example, patented methods can be employed to mitigate the problem of air binding and thereby lower condensate DO and other gases, where noted, and reduce turbine back pressure.  Two partial case studies at nuclear installations are presented to demonstrate the impact on performance and on cash flow valuation by this new approach.  An estimated 12 MWe capacity recovery is projected in one of the cases.