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Those old power plants

Issue 8 and Volume 100.

LETTERS

Those oldpower plants

I have read and reread Bob Smock`s March 1996 piece, “There`s gold in those old power plants,” and for the life of me cannot find the rationale for the “movement.”

Somehow the idea is being pursued that new investment in old plants is going to result in a revitalized facility with higher fuel efficiencies. Just how that is going to come about is not at all clear, and there do not seem to be any real clues in your article.

Can it be that conversion to combined-cycle plants is what the entrepreneurs have in mind? If so, how does one evaluate the future economies of an upgrade consisting of, say, an “old,” 25-plus-year steam-cycle plant, coupled with a new gas-turbine cycle upgrade–only to end up with a half-old, half-new facility. How long will the combined-cycle plant be around; what depreciation rate is appropriate; and who, if anyone, has actually done this?

On the environmental side of the picture, how much grandfathering protection can one count on with, say, circulating water system permits, stack emissions, etc.?

The whole picture is quite cloudy from my perspective, and I was wondering what I may have overlooked in your piece.

Of course, spending money to gain access to new energy markets might be the answer, but hardly worth the tag of “gold in those old power plants.”

What am I missing?

Donald J. Binder

Sigma Energy International Inc.

Gas turbines fire up

Your story in the June issue, “Gas turbines fire up after 100 years,” was like a visit from an old friend. By no means was it a solo effort but as a young sales engineer representing Westinghouse out of El Paso, Texas, I received sales credit for the 5,000 kW unit installed at West Texas Utilities` (WTU) Ft. Stockton plant shown in the photo. As I recall, start up went well and I made several routine service calls to WTU. Do you know if the unit is still in operation?

It brings back fond memories because after a long trip I would often get down on the floor with my three-year-old son and use a toy car to trace out the roads to Ft. Stockton with the intent to teach him how to read a map. In spite of such treatment, the kid turned out okay and is a chemical engineer with Texaco.

Russell C. W. Crom

Mount Prospect, Ill.

The article on gas turbine history was interesting and informative, but a chapter was missing:

In the early 1960s, Turbo Power and Marine (TP&M) was formed by United Aircraft (now United Technologies) to utilize the FT-4 aircraft engine to power utility “free turbines.” More than 1,000 of these installations were installed in the next decade. At a conservative rating ranging from 12,000 to 20,000 hp, the GT4 hot-gas generator was used to power TP&M, as well as other turbine manufacturers` designs. Initially, the application was for natural gas line pumping (boost in-line pressure from 600 to 900 psi about every 100 miles), with Cooper Bessemer as the contractor.

Approximately 60 of these 12,000 hp units were on gas lines here and abroad. Concurrently, the viability of 20 MW electric peakers was recognized and installed. Worthington developed and commercialized a dual-input, free-turbine driving alternator at 40 MW. To better use this asset, four pairs were ganged together driving a single alternator, resulting in 150 MW output. Such utilities as Public Service Electric and Gas Co. of New Jersey (PSNJ), with four 150 MW installations, and Southern California Edison Co., I believe, are still using these large power plants today, as are many of the paired and single units.

Just as important as the durability and mechanical reliability of these engines was the concept and fruition of a totally electronic (analog solid state) control system. The control system was started, loaded and governed by speed and exhaust gas temperature, while providing the safety features for remote operation. For the multi-engine station, the specification called for cold start, synchronize and power-up to 150 MW in less than three minutes. This was easily accomplished by the aircraft derivative.

The engines were also dual-fuel capable, and one could switch from liquid to natural gas and back while under power. The PSNJ 150 MW units were operating locally during the 1965 blackout, but the grid would not accept the power. By the way, the blackout created an urgent demand for single-engine peakers at nuclear plant sights when it was suddenly realized that the grid could not be counted upon for control and cooling power at the nuclear plant.

The GT4 engine was a mature power plant, having accumulated millions of flight hours with hydro-mechanical fuel controls. The challenge to design an extremely reliable electronic control system was of prime importance. The system surpassed all expectations. In the early 1970s, the excellent experience of this exposure to electronic engine controls led to the development of the military and commercial, digital control systems. These systems enable the more refined aircraft engines of today to have the outstanding performance and longevity many take for granted.

Jarl Johnson

Fort Lauderdale, Fla.