AEP Turbine

The American Society of Mechanical Engineers (ASME International) on 8-7-2003 designated American Electric Power’s (NYSE: AEP) former Philo Unit 6 a Historic Mechanical Engineering Landmark for the unit’s groundbreaking and far-reaching technological advances.

Philo 6 “was the world’s first utility generating unit using steam at the supercritical pressure of 4,500 pounds per square inch (psi), almost twice that of previous units and at 1,150° F,” according to a plaque presented by ASME International to E. Linn Draper Jr., AEP chairman, president and chief executive officer. The plaque will be affixed to an existing sculpture that incorporates two Philo 6 turbine rotors in front of AEP’s Columbus headquarters. The Philo Plant, located on the Muskingum River nine miles south of Zanesville, was razed in 1983.

Very high pressure and temperature steam, combined with double reheating of the steam, at Philo 6 dramatically improved efficiency and reduced the amount of coal used to generate electricity. New technologies introduced at Philo 6 increased by one-third the thermal efficiency of coal-fired electric generation, to 40 percent. This percentage is a measure of the heat energy in coal that is converted to electricity.

Machines that convert heat into mechanical energy, as steam electric generating plants do, operate more efficiently at higher temperatures. A characteristic of water is that the higher its pressure, the higher its boiling temperature. Hence, higher steam pressure results in a more efficient generating plant.

“Successful operation of Philo 6 represented a watershed event in the history of steam electric generation,” Draper said. “Its impact was universal. What was groundbreaking technology at Philo 6 became normal operating procedure throughout the electric utility industry. ASME International landmark status is fitting recognition for the many engineers who designed and engineered Philo 6.”

Philo 6’s steam pressure of 4,500 psi was almost twice the pressure of 2,300 psi of the best conventional generating units in the mid-1950s. (Steam reaches the supercritical level at 3,208 psi.) Philo 6, announced in 1953, was completed and went into commercial operation in 1957. The 120-megawatt unit operated until 1975, was retired in 1979 and dismantled in 1983.

The higher pressure and temperature levels at Philo 6 required major changes and technological advances in steam generation, turbine design, metallurgy, feed pump capability and water purification.

Philo 6 produced profound effects. Experience gained from engineering, design, construction and operation of Philo 6 spawned a new generation of larger, more efficient generating units. The ASME International plaque makes note of this effect, saying Philo 6 “became the trailblazer for many that followed…”

In addition to AEP and ASME, other participants in the plaque presentation ceremony included representatives of Babcock & Wilcox (B&W) and General Electric (GE). B&W and GE designed and installed the steam generator and the turbine generator, respectively, at Philo 6.

ASME International sponsors the historic mechanical engineering landmarks program. Since its inception in 1971, 227 designations have been made of landmarks, sites and collections of note in the history of mechanical engineering.

ASME International is a 120,000-member engineering society that focuses on technical, educational and research issues. It conducts one of the world’s largest technical publishing operations, holds some 30 technical conferences and 200 professional development courses each year and sets many industrial and manufacturing standards.

American Electric Power owns and operates more than 42,000 megawatts of generating capacity in the United States and select international markets and is the largest electricity generator in the U.S. AEP is also one of the largest electric utilities in the U.S., with almost 5 million customers linked to AEP’s 11-state electricity transmission and distribution grid. The company is based in Columbus, Ohio.