Paul Zombo - Peering into the Inferno
Gas turbines are huge pieces of equipment weighing several hundred tons and assembled with a watchmaker’s precision. When a turbine is running, some of its parts heat up to over 1,100 degrees Celsius. This sophisticated machinery must be carefully monitored in order to maximize performance and prevent unnecessary degradation to individual components or, even worse, a complete failure. If not, the costs can be enormous. Just one turbine blade made of a nickel-based superalloy covered in a protective ceramic coating costs as much as a family car and there are approximately 300 in each gas turbine. And if a gas turbine in a power plant goes down completely, the resulting losses in electricity can rapidly rise to millions of dollars. These are all problems that Paul Zombo understands very well. The 49-year-old metallurgical engineer heads a highly specialized online monitoring unit and is responsible for providing service and field support for gas turbines in the U.S.
Zombo had his first encounter with infrared cameras at the Kennedy Space Center over 20 years ago. “We used them to monitor various functions of the space shuttle during launch and re-entry into the earth’s atmosphere,” he recalls. It was an experience that served him well when he came to look for a method to examine the inner workings of a gas turbine when online – i.e., without having to shut it down and open it up. This was no mean feat, since the turbine blades rotate as fast as 3,600 rpm in a stream of exhaust gases as hot as 1,500 degrees Celsius. Zombo’s solution was to develop a high-speed infrared camera that is mounted on the outside of the turbine. From there, it directly monitors – via a flange-mounted optical probe – the effect of the high temperatures on the blades within the turbine. To protect it against the extreme temperatures, the probe is equipped with an ingenious cooling system.
Siemens gas turbines in the U.S. were first equipped with this type of monitoring camera from 2004 onward. “Now we’re installing between 12 and 24 systems every year,” says Zombo. As a rule, it is new gas turbines that are equipped with the monitoring camera. This allows us to verify our latest designs even faster and better assure safe and efficient products for our customers. Before the development of Zombo’s infrared camera system, power-plant operators had no alternative but to shut down the turbine after a certain number of operating hours and inspect the blades, which involved substantial costs. Online monitoring means that operators now know when a blade really is damaged and must be replaced. Then, and only then, do they need to take the turbine offline. Zombo’s service team also uses the high-speed infrared camera with older gas turbines to track down the cause of operating problems.
“Infrared cameras are a fantastic piece of technology,” says Zombo, whose 38 inventions in this field have already spawned 17 granted individual patents and 26 IPR families. “They are more sensitive then I can image. The cameras still surprise me with their capabilities which lead to a wide range of potential applications.” Meanwhile, Zombo has come up with a new idea for enhancing the use of high-speed infrared cameras for monitoring gas turbines. The aim here is to measure the exact temperature of the blades. “In a gas turbine, temperature is the most critical factor,” Zombo explains. At present, it is still impossible to accurately determine the gas temperature inside a running turbine. Instead, approximate values are used. “But with precise measurements, we can control a turbine much more effectively and increase its efficiency and longevity,” says Zombo. So it should be easy to guess what his next patent will be.
Zombo has passed on his enthusiasm for technology to his oldest daughter Elizabeth, who much to his delight is now studying engineering. Her younger sister Victoria is still in high school and enjoys mathematics as her favorite subject. Zombo lives with his wife and inspiration of 27 years, Lisa, in Orlando, Florida.