Dear Sir,

Your November 1999 issue, like always, has very informative technical articles.

Dr. M.P. Boyce’s “Optimizing Operation” (Combined Cycle Plants) in particular is full of very useful data. However, it is not understood why Dr. Boyce has put “ambient temperature and humidity” as uncontrollable losses on the output and heat rate of turbines.

Combustion Turbine Inlet Air Conditioning (CTIAC) is now a known and well-tried technology and there are many such installations, especially in the United States.

It is now economically viable to run combustion turbines/combined cycle stations at any pre-determined (ISO conditions or even lower) inlet air conditions, allowing both full power and high efficiency whenever this is required.

Recent CTIAC installations include a large project in Saudi Arabia in which this technology will provide 10°C inlet air to five large combustion turbines for full capacity operation for five hours every day. There are systems available which would provide even on-line cooling of inlet air for continuous full rating and high efficiency.

In installations where combined cycle units are to be operated at full load for certain hours and at peak loads for most of late night/early morning, a patented process is now available to utilize the same cooling coil (which is only of use during full capacity operation) to increase part-load combined cycle efficiencies, thus saving fuel during many hours of normal part-load operation.

CTIAC technology needs to be accepted by professionals in general and the methodical working of Dr. Boyce in many facets of combustion turbine operation demands that he put his analytical expertise in this field also.

Engineer Ainul Abedin
Karachi, Pakistan
Fax: +92 21 452 02

Thanks for your comments on PEi. We put your points to Dr. Boyce and received the following reply:

Dear Mr. Abedin,

I am glad that you liked my article and found it full of very useful data.

I am very aware of Combustion Turbine Inlet Air Conditioning and have been a proponent of it in many situations throughout the world.

In fact I have three projects where we are looking into this and other sources for augmentation of power.

The reason we considered temperature and humidity as uncontrollable losses in this article, is because in the context of this article we were not advocating a change for power augmentation.

The additional cost of putting in a system such as CTIAC can only be justified if the plant can sell the excess power.

It does not fall into a category of a loss, or of optimization of existing plants.

With best regards,
Dr. Meherwan P. Boyce, P.E.
The Boyce Consultancy, Houston, USA
Fax:+1 713-807-0088

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