By Lee S. Langston

Just 60 years ago last summer, the first jet-powered aircraft flashed across the skies above the Baltic Sea to start the Jet Age.

The gas turbine-powered Heinkel He 178 took flight over German skies more than 60 years ago, when Hitler's war machine launched the Jet Age.

Hans von Ohain's aviation gas turbine powered the first flight of the Heinkel He 178 on Aug. 27, 1939, at the Heinkel Airfield in Marieneke, Germany. Frank Whittle's W1 jet engine was to power the first British jet aircraft 20 months later.

Von Ohain, who died in 1998 at age 86, received the R. Tom Sawyer Award, the International Gas Turbine Institute's highest honor, at a 1990 IGTI conference in Brussels. At the awards banquet, he was asked if he and his small team in 1939 had any idea that his invention would spawn the gas turbine industry.

No, he replied. What's more, he doubted they could do the same task today—too much paperwork. He also recalled that on the morning of the historic first flight, test pilot Erich Warsitz arrived in flight gear, carrying a hammer. Warsitz, who had just test-flown Germany's first rocket-powered aircraft, said it was his escape tool, if he needed to get out of the cockpit in a hurry.

Another historic gas turbine event occurred in the same year. Some 500 miles to the south of von Ohain's team, the Swiss company Brown Boveri completed development of the first modern land-based gas turbine. The turbine was installed at Neuchatel in the Swiss Alpine foothills to power a 4-megawatt electrical generator for backup power. It still does, six decades later. ASME designated the Neuchatel installation an International Historic Mechanical Engineering Landmark in September 1988.

Thus, last year marked the 60th anniversary of the gas turbine for aviation and electric power generation. It was also a year of healthy growth.

According to Forecast International, which provides the information to IGTI, the value of gas turbine production in 1999 will total $34 billion worldwide, up 21 percent from 1998 (which was up 12 percent from the 1997 total).

The greatest portion of the 1999 gas turbine market was associated with aviation. It is estimated that the value of jet engine production totaled $20 billion, up 11 percent from 1998. As a percentage of the marketplace, the total represents a decline. Aviation accounted for 59 percent of the 1999 total value, down from 64 percent in 1998.

In general, the civil aviation market was good for gas turbines in 1999, with more of the public flying and the start of a recovery for some of the depressed economies in Asia. Production value for this segment totaled $17.2 billion, an increase of 15 percent from the previous year.

At the same time, the value of turbines for the military market declined 7 percent to $2.8 billion, reflecting military budget cuts worldwide. Several new fighter programs are on the verge of production, and European nations are reassessing their air force inventories after the NATO bombing in Kosovo and Serbia, so the military market may increase in the near future.

As in 1998, the non-aviation segment of the gas turbine market has experienced the fastest rate of growth. The value of production for this segment in 1999 is estimated to be $14 billion, up 40 percent from 1998. This represents 41 percent of the total gas turbine market, up from 36 percent in 1998.

Almost all the non-aviation part of the market, $13 billion, represented the value of production for electric power gas turbines, an increase of 53 percent from $8.5 billion in 1998. The remaining $1 billion went for applications as varied as marine propulsion and mechanical drive turbines, including gas pipeline compressor drives.

There are several reasons for the boom in the power generation market.

Electric power turbines fueled by natural gas have the highest operating efficiencies—40 percent for simple cycle and up to 60 percent for combined cycle operation. They turn out fewer pollutants than other major combustion energy converters. A gas turbine power plant burning natural gas will emit much less nitrogen oxide and as much as 43 percent less carbon dioxide than a coal-burning steam plant of the same output. Gas turbines incur relatively low capital and operating costs.

Electric utilities in North America, facing deregulation, are placing record orders to replace old equipment and to increase electrical power reserve margins, which have gotten to be dangerously low, especially in the U.S. Midwest. This has filled the order books and production lines of the major gas turbine manufacturers for at least the next two years.

In an effort to meet new environmental regulations and to lower NO_x emissions even more, the gas turbine industry has run into a combustion instability problem called humming, which can lead to severe engine vibrations that can permanently damage a turbine.

Germany's jet pioneers breaking bread together: test pilot Erich Warsitz (left), aircraft builder Ernst Heinkel (center), and engine developer Hans von Ohain, in an undated photo. Von Ohain received the R. Tom Sawyer Award from ASME's International Gas Turbine Institute in 1990.

According to David Gillespie, manager of several gas turbine merchant plants in the U.S. Northeast, if humming sets in on one of his low NO_x, high firing temperature, high mass flow rate machines, it means cutting back on power and operating at lower outputs—and lower revenues.

The humming problem eventually will be solved, either by additional cost-benefit analysis that could result in more enlightened emission regulations, or by improved technology through research and development—for which the gas turbine industry is renowned.

There is another problem, not strictly technical, which became more acute in 1999. It has to do with the growing experience of users and buyers of the larger (greater than 50 MW) and newer, more advanced electric power gas turbines as they are being introduced into the marketplace.

During 1999, IGTI not only staged a highly successful Technical Congress and Gas Turbine Users Symposium, but also put on seminars in Atlanta, Houston, and Buenos Aires on topics of interest to electric power gas turbine users, buyers, insurers, and financiers. Complaints of seminar participants about new machines ranged from problems that the industry solved decades ago (rotor vibrations and through-bolt assembly procedures) to others that might have been solved through more OEM component testing before going to market (some of the humming problems, and combustor parts that fail during operation and enter the gas path to cause downstream turbine damage).

Much to their dismay, they concluded that extended commissioning periods, performance shortfalls, and outages for component repair or replacement have become all too common with the newest of large gas turbines.

Hans von Ohain's test pilot, Erich Warsitz, carrying his hammer was history's first real gas turbine user. One could argue that today's electric power gas turbine users also need hammers for their own protection.

That protection could come from the establishment of a third-party certifier of performance standards for new electric power gas turbines. Such a certification process would help to eliminate some of the new machine problems discussed at last year's sessions, and a set of standards would level the playing field for all OEMs.

Neuchatel, Switzerland, was the birthplace of the first modern land-based gas turbine, installed in 1939.

A certification process has long been in effect for civil aircraft gas turbines worldwide. In the United States, the third-party certifier is the Federal Aviation Administration.

The FAA regulations are in place and have the force of the law behind them because they directly concern public safety. However, the gas turbine is becoming the major means of electric power generation around the world. Society has now become so dependent on electric power that the possibility of a major electrical shutdown (say, in the northern midwestern states in winter) seriously involves public safety.

During 1999, discussions about performance standards, a certification program, and a third-party certifier have been going on among electric power gas turbine users, IGTI volunteers, and ASME Codes and Standards volunteers to determine the merits of such an undertaking.

Here is where the gas turbine stood in its 60th year, according to IGTI Technical Committee chairs and other volunteer leaders.

Cogeneration: Industrial and Cogeneration Committee chair Rakesh Bhargava reports that deregulation of electrical utilities worldwide has changed the power generation market, particularly development of the power plants operating in cogeneration modes.

The available data on new cogeneration plants, developed or under development in the last 18 months, suggest that the power rating of gas turbines used in cogeneration applications varies from 0.5 MW to 170 MW. Many cogeneration plants use gas turbines with ratings of 10 MW and less.

The development of cost-competitive microturbines ($300 to $500 per kilowatt) and solid oxide fuel cells has shown some promising results for a small power generation system. A great deal of research and development work is in progress to use the combined technologies of microturbines and fuel cells, and this combination has been shown to achieve an overall electrical efficiency of 60 percent and higher. The technology was expected to become commercially available by 2005, according to some estimates.

Microturbines: Mary Gerstner, who chairs the Vehicular and Small Turbomachinery Committee, reports that microturbines made marketplace advances in 1999, with several companies initiating commercial production and sales. Capstone Turbine Corp., a manufacturer of microturbines in Tarzana, Calif., announced a milestone of 6,000 hours of continuous operation for a unit at a customer site. Other companies say they will begin production this year. The early products introduced have been in the 25- to 100-kW range, but recent announcements from several producers have indicated that cogeneration units (initially hot water heating) are now being offered with some of the products.

Although the primary focus in the small gas turbine area has centered on distributed power markets, efforts in the vehicular arena continue. Recent sales of microturbines for commercial hybrid electric buses have been announced by at least two producers. The ability to operate with fuels from the existing infrastructure while producing extremely low emissions continues to be of great interest to the vehicular community in a world of ever more stringent emission regulations.

Measurements and control: According to Robert Luppold, chair of the Controls and Diagnostics Committee, the past year has seen a rapid increase in the interest in optical probes and microsensors. Microelectromechanical systems are finding application in turbomachinery instrumentation, usually in combination with microelectronics. The technology may reduce sensor size and cost by two orders of magnitude. Immunity to electromagnetic interferences makes optical sensors the preferred choice in some of the most demanding applications.

In the industrial sector of the market, control systems for low NO_x combustors are rapidly becoming more complex, with an emerging need for closed loop control on NO_x and CO levels. The demand for NO_x and CO sensors has increased significantly during the past 12 months.

The development of blade tip clearance probes that will form part of the closed loop control system has been actively pursued over the last year, with very significant progress, prompted by the emphasis on increased efficiency in large gas turbines.

Combustion: The Combustion and Fuels Committee chair, Jim Peters, reports significant advances during 1999 in computational combustion dynamics, combustion research, and combustion technology. The National Combustion Code, a joint university, government, and industry initiative, is coming close to validation and production under the guidance of the NASA Glenn Research Center in Cleveland.

Environmental issues: During 1999, more gas turbine power plants were installed, replacing old units and reducing air pollution and greenhouse gases for the same power output.

The chair of the Environmental and Regulatory Affairs Committee, Manfred Klein, pointed out in a report that regulations requiring simply a lower ppm of NO_x emissions (the rules that have given rise to the humming problem) are not necessarily better for the environment.

Klein predicts that, after energy conservation and the use of renewable resources, the construction and use of clean, efficient gas turbine power plants will be the most effective way to reduce greenhouse gases and regional air pollution during the coming century. Improved efficiency is the key, not the single-minded goal of ultralow NO_x.


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