This book’s content is the same as the “Design of Gas Turbine Combined Cycles and Cogeneration Systems” seminar, which I taught about seventy times in twenty years, 1990 through 2009. About three thousand engineers from around the world attended these 3-day sessions and received versions of this book. Many additional printed copies were sold or given to those requesting them, but the book was never turned over to a mass-media publisher and has remained in limited circulation of a few thousand printed copies.
Friends have asked why this was never turned over to a mass-media publisher. There are several reasons. First, the content was evolving with the result that the entire book was always like Mr. Micawber’s goal of an entire suit of new clothes at once, in the Dickens novel “David Copperfield”. By the time one chapter was updated, another had gone out-of-date. This was due to my primary focus on the development and expansion of the Thermoflow software suite, leaving no time to update the entire book at once. Second, the instability and boom-bust cycles in the thermal power generation industry, and the economy as a whole, had a disruptive effect. Whenever a boom period produced high seminar attendance at frequent seminars, resulting in renewed enthusiasm to update much of the book and widely publish it, a bust ensued and thwarted the momentum. Third, is aversion to dealing with the corporate mass publishing industry.
Since the last time I taught the seminar in 2009, many have asked why it was no longer being offered. The answer is partly in the preceding paragraph, but there are additional reasons. When I started the seminar in 1990, combined cycles were not mainstream, and many experienced plant designers had much better understanding of coal and nuclear Rankine Cycle plants (which then generated 70% of US electricity) than combined cycle plants (which then generated less than 10% of US electricity). When I last taught the seminar in 2009, combined cycles had become mainstream, their principles more widely understood, and were on their way to generating 30% of US electricity. Also, when I started the seminar in 1990, GT PRO® was a bare-bones calculation tool, DOS-based, no user-friendly graphics, and with limited built-in expertise and features. By 2009, thanks to my brilliant colleagues at Thermoflow, especially Dr. Gwo-Tung Chen and Dr. Patrick Griffin, GT PRO® had become a highly user-friendly combination of calculation tool and expert knowledge repository. Over time, the knowledge taught in the seminar and explained in this book was embedded into the Thermoflow software suite. Practically-useful exergy analysis of combined cycles, pioneered in my 1980’s papers, and covered to the extent time permitted in the seminar and its book was integrated into GT PRO®, so any user had full access to this technique and knowledge. My models for the cooled gas turbine, published in the 1980’s, were embedded into the THERMOFLEX® program as a “Cooled Turbine Stage” component available to all users of this program. Many design and modeling procedures for steam turbines, condensers, and cooling towers, described in the seminar, had been integrated into the Thermoflow software suite by 2009. The methodology of selecting cogeneration cycle configurations was embedded into PDE®. The logic of parsing through and analyzing different repowering configurations was built into its own dedicated Thermoflow program, RE-MASTER. Thus, in effect, the Thermoflow software suite, with its greatly increased user-friendliness, and its inclusion of much of the content of the seminar and this book, has subsumed the seminar and this book as a repository of plant design knowledge, analysis, and modeling.
Another reason for my waning enthusiasm to repeat the seminar, is the changing audience. At the earlier seminars, the audience included many highly experienced engineers. Those new to combined cycles had a solid grasp of Rankine Cycle practice, and understood how to analyze and calculate thermal power cycles. This enabled them to quickly understand the content that was new to them. Some were gas turbine experts at major OEMs who certainly understood their gas turbines better than I, but came to learn about combined cycle optimization, or steam turbines, or HRSGs. Some were HRSG, or steam turbine, or cooling tower experts from major OEMs, who certainly knew their specialty and its details far better than I, but came to learn about the complete cycle and its other components. With this audience profile, it was likely that for much of the content, there was someone in the audience who knew more about the current topic than I, and many of those contributed valuable comments from which the rest of the audience and I learnt many new things. However, by the latter seminars, the profile had increasingly tilted towards an inexperienced and undereducated audience, with many struggling to follow or understand the content or its basic concepts; and this made teaching it more challenging and less stimulating.
When I started the seminar in 1990, I invited my friend and colleague, the late R. W. (Dick) Foster-Pegg, to teach portions of it. Dick was a great engineer, with an immense grasp of engineering principles and applications, despite minimal theoretical training. He complemented my (at that time) academically-biased background. Dick was 32 years my senior, had worked at Rolls-Royce on airplane piston engines during World War II, on gas turbines starting in the 1950’s, and on practical engineering of combined cycles in the 1960’s, at Bechtel then at Westinghouse, until retiring in the 1980s. I had earned my Ph.D. on gas turbine cooling at MIT in the late 1970’s, then as a professor at MIT in the 1980’s did extensive original work, supervised many theses, and wrote numerous publications on practically applying fundamental thermodynamics and heat transfer to gas turbine and combined cycle analysis and optimization. The diversity between Dick’s background and generation and mine, created a unique learning experience for those who attended the seminar until Dick retired from participating in 2000; and from 2000 through 2009, I taught it alone.
The copyright notice at the beginning of each chapter indicates the vintage of its content. Chapters 1-3, 5-7, and 9-18 are my original content from 1990 with some updates and revisions over the years (year of latest revision as shown). Chapters 4, 8, 19 and 20 are my newer content written in 1999 and 2000 on subjects which had been taught by Dick in earlier seminars. Chapters 21 and 22 were written in 2008 on CO2 capture and solar thermal energy, topics that had not been considered earlier.
Chapters 1 and 2, which focus on basic applied thermodynamics and cycle analysis, include original fundamental insights and interpretations that had not been previously published. They draw heavily on the work I had done at MIT, much of it published in papers during the 1980’s and referenced at the end of Chapter 2. Some who attended the seminar reiterated these insights and analyses in subsequent publications, with a few unfortunately omitting reference to the seminar and its book they received.
Although this book has not been updated at all since 2009, and some chapters since 2002, its fundamental insights and approach remain as relevant as ever. The main differences between current practice and the book’s content will be found in the chapters dealing with gas turbines. The principles are as valid as always, but higher firing temperatures, better materials, and improved aerodynamics have added a few percentage points to both gas turbine and combined cycle efficiencies.
Maher A. Elmasri