Condenser air inleakage audits are generally performed with the unit online. American Efficiency Services has experienced teams positioned in key locations across the United States that utilize proven techniques to efficiently identify sources of condenser leakage within the vacuum boundary of the turbine and/or condenser system. While a complete condenser air inleakage test can typically be performed in one to three shifts, factors such as the unit’s size, response and/or clear-out times, number of air leaks identified, and whether or not the station elects to conduct condenser repairs and reinspect the air leaks can affect the length of time needed to complete a condenser air inleakage audit.
What is the industry standard for acceptable condenser air inleakage? Most condenser air inleakage standards have been developed by research organizations and individual stations. These condenser standards vary from station to station depending on condenser system design and operation. The most common standard used for an acceptable rate of condenser air inleakage is one cubic foot per minute (CFM) for every 100 megawatts of generator capability. Most stations have adopted this condenser standard with a tolerance between 1 and 2 CFM per 100 megawatts. Other stations rely on their history of backpressure and dissolved oxygen to gauge when a condenser air inleakage test is required. A routine audit schedule integrated into your condenser maintenance program is the best way to determine how effective your condenser operates as a key component in a complex system.
Condenser Services are available 24 hours a day, 7 days a week, 365 days a year. AES performs routine, outage prep, and emergency leak detection services to manage your condenser air inleakage challenges.
Surface condensers are designed to be a vacuum-tight system with cooling water flowing through tubes. The cold tube surface condenses the steam creating a reduction in volume inside the condenser which produces the vacuum. Air and non-condensables (air inleakage) that enter the steam space from outside the unit can cause a reduction in vacuum, resulting in operational inefficiencies and impacting your bottom line.
Condenser air removal systems are designed to remove a certain amount of condenser air inleakage. As the design limitations of the air removal system are approached, the efficiency of the unit decreases. To maximize operational efficiency, condenser air inleakage must be minimized.
As condenser air inleakage increases, loss of vacuum occurs as the backpressure increases. The rate at which the backpressure increases due to air inleakage is dependent on the effectiveness of the air removal system. The air removal system should be able to control small amounts of air inleakage before detrimental operational effects are observed.
While other factors can contribute to an increase in backpressure (such as fouled condenser tubes) that reduce heat transfer, a condenser air inleakage audit is an excellent first step for solving a high backpressure problem since the inspections are conducted online.
Dissolved oxygen is another by-product of excessive condenser air inleakage and yet another reason to let American Efficiency Services perform a condenser air inleakage audit. Air that enters the steam space and cannot be removed through the condenser’s air takeoff system can become entrained in the condensate.
Although it is thought that the entrained oxygen passes through the entire system, the condensate pumps are designed to separate a percentage of the entrained oxygen and discharge it back to the condenser through the pump vent for final evacuation through the air removal system (a vacuum pump or air ejector). The entrained oxygen that is sent back to the condenser is detected by the mass spectrometer, confirming leaks under the hotwell (water) level.
The percentage of air that passes through the feed water system to the boiler sets up corrosive conditions that can affect the entire system. If the dissolved oxygen levels remain high for prolonged periods of time, the result will be a decrease in the life expectancy of any affected components, longer outages, and lost revenue. Adopting a routine vacuum leak detection plan as part of your condenser maintenance program will keep air inleak low, allow components to operate as designed, and maximize life expectancy.
Why Do We Use it for condenser air-in leakage testing?
Helium is applied to the various components within the vacuum boundary of a Turbine and/or Condenser system. A leaking component will allow the helium to enter the steam space and from there, the helium will be removed by the unit’s air removal system. AES will have an inspector located at the discharge of the air removal system with a mass spectrometer sensitive to helium.
As the helium is ejected from the system, the mass spectrometer registers an indication. The leak will be recorded and at the completion of the inspection, all leaks will be discussed with plant personnel.
Our helium leak detector results discussion will include the severity of the leak, the location of the leak, and potential repair options. Our staff engages in proper report writing so that our reports are so efficient you might agree they are “almost too good” as other plant managers have commented to us in the past. We pay strict attention to all details during the process in order to provide you the most thorough results possible. Once the helium leak detector is completed, you will understand every step you need to take to correct the problem.
Trust our team with your air leak detector inspection so that you know how to keep everything running efficiently and safely.