Gas Turbine Handbook : Principles and Practices

Appendix C 381
Solving for CDT yields 886°F.
At 95% and 100% RH the air flow into the gas turbine includes 16.6
pps of water. At a latent heat of vaporization of 970 Btu/# this water
will give up 16,050 Btu/sec (cp = 0.24672).
Using Q = W A
• c p
• ∆T
Solving for ∆T yields 130°F.
Therefore, the dry bulb temperature of 886°F will be reduced to
756°F.
This addresses the maximum amount of water that can be expected
to be evaporated in the inlet system upstream of the gas turbine-compressor
inlet. Now consider adding water for wet compression.
Consider first adding 90 gpm of water to this inlet condition. This is
approximately 2.5% of the inlet flow.
Within the compressor this water is evaporated through latent heat
of evaporation.
At 90 gmp = 12.5 pps; then 12.5 pps ⋅ 970 Btu sec
= 12,125 Btu/sec Heat Absorbed
Again solving for ∆T yields 99°F. Therefore, the injection of 90 gpm
into the air stream at the compressor inlet will result in a compressor
discharge temperature of 656°F.
Increasing amounts of water can be added until either the compressor
surges or the discharge from the compressor contains liquid water
droplets.
Consider adding 10% water at the original inlet conditions.
10% water = 50 pps = 360 gpm.