Gas Turbine Handbook : Principles and Practices

Gas Turbine Inlet Treatment 115
Chapter 8
Gas Turbine Inlet Treatment
THE ENVIRONMENT
Gas turbines are installed in many environments from desert
to coastal, tropical, arctic, agricultural, oil fields, etc. The
weather conditions, temperature range, and type, concentration,
and particle size of airborne contaminates can be defined well
in advance of equipment purchase and installation. Chart 8-1 summarizes
the dust concentration and particle size in various environments
in which gas turbines operate. Each environment brings with
it specific atmospheric contaminants. For example, sand, salt, and
dust are the problem contaminants in the desert; salt is the major
concern in coastal areas; dust, pollen, and chemicals (fertilizers) are
the impediments in agricultural locations; and snow and ice must
be contended with in the arctic regions. These contaminants are the
cause of erosion, corrosion and fouling. Some contaminants like salt,
when combined with high temperatures, attack turbine blade and
nozzle material. This is commonly referred to as sulfidation attack
and can seriously and rapidly reduce performance and shorten turbine
life. A general overview of the characteristics of particles and
particle size analysis methods can be found in Appendix C-1.
In the effort to improve performance and lower fuel consumption
and emissions, secondary problems are often created. Two examples
are: the injection of steam or water into the combustor to increase
power output and decrease fuel consumption, and the installation
of evaporative coolers or fogger systems in the gas turbine inlet to
reduce temperature and increase power output. For example, if potable
(drinking) water were injected into the combustor the mineral
deposits that would form on the hot turbine airfoils would render
them completely useless in less than a year. Another example, one
of overtreatment, would be the use of demineralized/deionized (DI)
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