- since 1996 -
|NDT.net Issue - 2010-11 - NEWS ||NDT.net Issue: 2010-11|
Publication: e-Journal of Nondestructive Testing (NDT) ISSN 1435-4934 (NDT.net Journal)
Fouled heat-exchanger tubes remain hidden, untested in the backbone of America s energy infrastructureAcousticEye B.V.5, Leusden, Netherlands
In his October 26 op-ed piece, The Corrosion of America, New York Times Bob Herbert declares, Most of us take clean and readily available water for granted. But the truth is that the nation s water systems are in sorry shape.
Improving water systems and infrastructure generally, says Mr. Herbert, would go a long way toward improving the nation s dismal economic outlook.
While Mr. Herbert s column centers on water infrastructure, he is right that broad-based attention to the condition of America's utility-delivery infrastructure would not only ensure increased public safety and energy efficiency, but would create real and sustainable jobs.
Another profound example of hidden, but absolutely vital infrastructure is the many thousands of miles of heat exchanger pipes that form the backbone of things like power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas processing, and sewage treatment.
The Stanford University campus energy facility combined heat and power (CHP or cogeneration) plant, as one power-generation example, consists of 360 miles of heat exchanger tubing. In the Chicago suburb of Elgin, Ill., the 645,000-square-foot Sherman Health hospital facility utilizes 1,000 heat pumps and 140 miles of heat-exchanger pipe. Beneath the parking lot of Murray High School in Utah lies a geothermal heat exchanger system consisting of 45 miles of pipe, through which water runs in a constant loop, transferring heat between the school building and the ground.
Boiler-tube leakage, likewise, is the major cause of downtime and power-generation loss in thermal power plants approximately 60% of boiler outages are caused by heat-exchanger tube leaks. Likewise, tube-based HVAC chillers often represent a power plant's single largest electric load, and fouled heat-exchanger tubes, leaking refrigerant, changes in water temperature, and other variables can escalate operating costs by 8-10% per year.
Heat transfer is the one factor that has the greatest single effect on chiller performance, says Tal Pechter, CEO and co-founder of heat-exchanger tube test-equipment maker, AcousticEye. The biggest chillers can have over five miles of condenser and evaporator tubes, making clean and open tubes vital to maintaining power efficiency and the greenest possible operation. Tube fouling in power generation plants reduces the ability for heat to transfer across the heat exchanger, lowering the efficiency of the heat exchanger, and leading to an increase in costs.
According to Pechter, the problem is that there are far too many tubes in the power-generation infrastructure to be efficiently and effectively tested using today s standard testing methods. The result is that the vast majority of heat-exchanger tubes more than 80% routinely go untested.
AcousticEye's Dolphin system uses Acoustic Pulse Reflectometry (APR) reflected sound waves to test heat-exchanger tubes. Because the Dolphin is fast and easy to use, it allows 100% of tubes to be tested, eliminating the guesswork around heat-exchanger tube degradation and failure. The result is dramatic power generation uptime skyrockets, energy efficiency climbs sharply, and steady jobs for test professionals are created.
As AcousticEye s Pechter puts it, There are more than 13 billion tubes operating in heat exchangers today, and only 1 billion are tested every year. The cost, says Pechter, is estimated to be more than $30 billion annually.
With new technologies like the AcousticEye Dolphin, it is time to start testing every single one of the heat-exchanger tubes in our energy infrastructure. As Bob Herbert concludes, We can start getting our act together now, or we can pay dearly later.