When Operations tells you that one of your main condensers has high back pressure, how do you address this situation?

As low pressure steam is condensed into a liquid, a vacuum is created in the condenser.  From a thermodynamic point of view, the higher the vacuum, the better the turbine and generator will operate. 

There are several areas you must investigate to determine the proper corrective action.

1. Are the main circulating pumps operating normally?
   
   
2. Condenser tubes can become fouled or blocked.  You can solve this problem by mechanically cleaning the tubes.  Common methods used include shooting brushes or scrapers through the tubes with a high-pressure water/air mixture, or using traditional hydroblasting techniques.
   
   
3. Since the main condenser is under a vacuum, air leakage can be an issue.  Also, non-condensable gases – other than steam – can accumulate in the condenser during operations.  To determine if this is a problem, complete the following tests:
1. Inspect the entire outside surface of the condenser for leaks.  Use helium and other tracer gases to detect leaks in the condenser structure.
2. Since each condenser has an air-ejector system for removing non-condensable gases, inspect this system to ensure it is working properly.
   
   
4. Leaks in the tubes or the tube-to-tube sheet joints also cause the condenser to not operate properly.  These types of leaks can cause major damage to the steam system by allowing contaminants to enter the boiler feed water system.  You can identify this problem by using hydrostatic testing or non-destructive testing (NDT) methods such as eddy current testing.

While there are a number of reasons for high back pressure in condensers, a thorough investigative process can identify the culprit.

Need help with maintenance and repair of your condensers?  Contact XChanger Mechanical today!

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