Condenser Performance Measurement Using New On-Line Condenser Tube Flow Rate and Fouling Instruments

Harpster, T.J. & Harpster, J.W.

"Condenser Performance Measurement Using New On-Line Condenser Tube Flow Rate and Fouling Instruments" The 10th Annual EPRI Balance of Heat Exchanger NDE, June 16-18, 2008 San Antonio, TX.

Abstract 

This paper presents a first of its kind condenser tube circulating flow and fouling (CWFF) instrument useful for condenser performance monitoring.  Additionally, this paper will present basic troubleshooting techniques using the data from the CWFF instruments.  Case studies from plants that partnered with Intek’s Condenser Services Group are presented illustrating the value of this new data to identify unique problematic operating conditions.  Corrective actions that were initiated as a result of the new data to prevent performance and operational losses are also presented in these case studies.

 The meter technology is based on Intek’s Rheotherm® thermal flow metering principles.  The important features are that the applicable design is highly accurate, reliable and non-invasive to the flow measurement.  For most steam surface condensers used in the power industry, any flow and fouling instrument must be capable of surviving long term submersion, exposure to unfiltered circulating water, and allow ease of online or offline tube cleaning methods.  The CWFF will be shown to be well suited to these conditions and thus is an excellent choice for the measurement.

 Four case studies will be featured in which the CWFF instruments were used to identify or monitor unique problematic conditions in various operating power generation condenser units.  The first case study involves a plant that is located near the mouth of the Mississippi River and draws in water for a dual shell single pressure one pass condenser unit.  The plant was measuring higher than expected back pressures and was interested in identifying whether or not biologic fouling was the cause for the noted excess pressure.  After 15 days of data collection it was determined that biologic fouling was unlikely and the more likely reason for the noted excess back pressure was a dramatic decrease in river water level. The significant effects of subtle river level changes due to tides and drought were noted for the first time by this plant through the data from these instruments.  The second case study describes the identification of a sudden surge of macro fouling.  The plant commented that the macro fouling would have gone unnoticed and an opportunity to clean the debris would have been missed without the information provided by Intek’s condenser services team based on the CWFF instrument data.  The third case study involved the detection of outlet waterbox thermal stratification that indicates severe impedances to heat transfer in portions of the condenser tube bundle.  Corrective action for this plant has been recommended and will be discussed.  The fourth case study involves a plant that has known macro fouling issues and thus uses a bidirectional flow configuration to reverse flush the tube sheet debris on a daily basis.  The plant has since correlated the meter data to circulating water debris filter differential pressure measurements, providing operators with necessary information to decide when to reverse flush and/or clear debris from the filters rather than daily flushing.  The meters at this plant have also been used to compare circulating water pump capacities.

 Other uses of the CWFF instrument will be presented to demonstrate its utility for plant operations, performance control, maintenance troubleshooting and condenser diagnostics.  Their use to identify causes of high dissolved oxygen at low condenser air in-leakage is an added benefit to improving plant component life.