Coal, Gas

Free Pressure Revisited

Issue 3 and Volume 102.


Free Pressure Revisited

I was intrigued by Figure 1 of the article, “OG&E`s Seminole Plant Operates Under Free Pressure.” This figure is similar to ones that were in 1988 and 1991 Heat Rate Improvement Conference papers co-authored by H.F. Martin and the writer. We were both employed by the Power Generation Business Unit, Westinghouse Electric Corp., and called the operating procedure “combined sliding pressure-constant pressure operation.”

At the time of the 1991 paper there were, in operation, eight generating units using the concept with Westinghouse steam turbines. The first applications, as I recall, were on Colstrip 3 and 4, Montana Power Co. The operational mode was integrated into a coordinated turbine-boiler control system with the turbine control system using either the MODII or MODIII DEH (Digital-electro hydraulic) control system. Computer simulations indicated a heat rate improvement up to 0.3 percent as compared to conventional operation. The data were derived from Colstrip thermal performance.

Prior to my retirement in May, 1994, I kept a list of the generating units (Westinghouse steam turbines) using the combined mode of operation. However, I have been unable to retrieve the list and cannot remember what the other generating units were. I vaguely recall that one utility had three units (Westinghouse turbines) operating in the combined mode.

I suspect there were Westinghouse patents on the coordinated turbine-boiler control system. In addition, the writer was granted a U.S. patent in August 1992 which presented a procedure for determining the optimum load (throttle flow) level for effecting the change from constant to sliding pressure operation and vice versa. The methodology could adjust for manufacturing tolerances and variations in turbine flow capability because of first stage nozzle block erosion and for blading seal degradation or flow area deviations in downstream blading of the BP section.

George J. Silvestri, Jr.

Winter Park, Fla.

Give Us a Try

BSME, MBA credits, registered Professional Engineer, U.S. Coast Guard licensed Merchant Marine Engineering Officer of ocean steam and motor vessels of unlimited horsepower, etc. Are these credentials held by an unskilled person? No, but these credentials are held by an engineer with 43+ years empirical knowledge of marine, naval and utility power generation plants who just, unfortunately, happens to be a member of an industry outcast group – who are all over 50 years of age. This writer, and many, many others like him, are deemed too experienced, thus too costly to employ.

We`re some of the people who helped achieve improved heat rates, availability, economically competitive specific horsepower rates, reduced environmental emissions on a cost-effective basis, designed real-time power plant diagnostics etc. It would seem that engineers in the U.S.A. are hired (used) when needed then discarded when the need passes, like a pair of worn out socks.

The mature engineers should be respected and employed as long as they`re capable and have a desire to be professionally employed. Deeming this huge knowledge base as too expensive, therefore laying them all off, is sticking industry`s head in the sand.

I, and many others like me, am capable, available now, ready to go, willing to travel as needed, desirous of contributing our knowledge base to the benefit of addressing the power industry`s needs. Give us a try, as we mature engineers are competitive and cost-effective. You`ll never make a better investment.

Frederick H. Dams Jr., P.gif.

Scottsdale, Ariz.

The 5%factor

I read with great interestyour News Update article “Study exposes treaty risks” in the November, 1997 issue.

I was delighted to see that someone has finally gotten it right. The five percent factor is the dirty little secret that all of those “do gooders” out there don`t want the public to know about. That information is being disseminated almost nowhere. It needs to be presented to the public, and my writing a letter to my local newspaper to complain about the one-sided reporting and the erroneous presentation of the data does some good, but it only scratches the surface. What is needed is that people with more clout need to step up and get the word out.

Douglas Doremus

Baton Rouge, La.

Deregulation`s Downside

Rarely does a month go by that we do not see an article concerning the impact that deregulation is having on the power industry. While most of your features and editorials portray these changes in a positive light as we put such reliable technologies as nuclear power on the back burner in favor of such simple machines as natural gas-fired turbines, it`s time to slow down and be realistic about the bad news as well as the good.

As has happened in virtually every deregulated industry, the natural consequence is lower prices to the consumer. As the first law of nature says, however, “ya don`t get somethin` for nothin`.”

Believe it or not, there are other inevitable consequences of bottom-line-only management–massive layoffs of good people, lower salaries for the survivors, overstressed workers who must take on more responsibility and consequently make more mistakes, and the resulting deterioration in morale and customer service. In the power industry, where safety is so important and the environmental consequences of a loss of control so potentially devastating, this is a recipe for disaster.

Let`s look at the long term. Sure, IPPs and their use of natural gas have been successful–only because this country has needed only incremental amounts of new power over the past two decades, creating a temporary market for small plants. It is worthwhile asking where the capital–or the engineering expertise–is going to come from when we need hundreds of gigawatts instead of a few hundred megawatts. One thing for certain is that it won`t come from the IPPs.

We are more dependent on foreign sources for oil–and more susceptible to economic crisis in the event of a cutoff–than we have ever been. As of 1992, DOE projections still showed that the known supplies of natural gas would run out in 60 years “at current rates of extraction.” Since your (December, 1997) feature projects increasing the rate of consumption to the tune of several hundred GW, it`s reasonable to assume that we`re destined to run out faster. Like it or not, running out of fuel is still a very real possibility–and we`ll run out of natural gas and oil long before we run out of nuclear fuels.

Yes, competition is bringing changes–whether or not they`re good changes is another issue entirely.

Michael F. Cohen, MEA, P.gif.

Virginia Beach, Va.

Solutions Needed

Your September, 1997, editorial, “Electricity is Beautiful” starts as a paean to a beauty which we all can see. Then it changes to a shallow attack on environmental “utopians.”

It`s not about perfection, it`s about the unforeseen consequence of even little changes. Change can trigger cascades of ecological consequences that we are too dumb to understand today. When the environment is 99.9999 percent pristine, that odd millionth part may be a keystone of the entire structure of life.

Today`s environmental problems give me an uncomfortable feeling: unexplained extinction of amphibians around the world, deformed frogs in Minnesota, PCBs falling in Antarctic snow, the persistence of El Niño, disappearance of the American honeybee, coral reefs dying worldwide, outbreaks of toxic microorganisms in the Chesapeake, anaerobic zones in the Gulf of Mexico, ozone holes sweeping temperate latitudes, changing weather patterns, loss of species diversity, mysterious increases in cancer and asthma incidence … If you are a thinking person, you have to be looking for the patterns.

Most of the profession has come `round to genuine concern about the environment. We don`t need to be defensive–we engineers have the savvy to be among the first to grasp the complex problems and help solve them. Our better spokesmen have outgrown brash defensiveness. Please join them.

Michael P. Gembol

Institute of International