## ESTIMATE OF EFFECT ON CAPACITY OF GAS TURBINES by PRE-COOLING INLET AIR FLOW

The following table (table 2) compares Turbine output (Capacity)  with and without evaporative pre-cooling.

Table 2:

 TEMP RANGE TOTAL HOURS OUTPUT W/O EVAP  % EFF             MW OUTPUT  W/EVAP % EFF              MW MW  HR GAIN \$/HR GAIN INCREASED EARNINGS 60-70 (f) 877 98 81.83 102 85.17 3.34 200.4 \$175,750.00 70-80 865 94.5 78.91 100 83.5 4.59 275.4 \$238,221.00 80-90 1,040 91 75.99 98 81.83 5.84 350.4 \$364,416.00 90-100 705 87 72.65 96 80.16 7.51 450.6 \$317,673.00 100-105 491 83.5 69.72 95 79.33 9.61 576.42 \$283,022.22 105-110 257 82 68.47 94.5 78.81 10.34 620.4 \$159,442.80 110-115 95 80.5 67.22 94 78.94 11.27 676.2 \$64,239.00 >115 30 79 65.97 94 78.94 12.52 751.2 \$22,536.00 TOTAL \$1,625,300.02

Table 2 above shows only increased earnings from capacity gain.  Efficiency (Heat Rate) gain is also significant.  Example: Using the 100-105(f) line above and average cost of \$1.90/million BTU's of natural gas..
Fuel Cost    Avg. H.R.        Output           Hours     Eff (%) increase      Increased Earnings (Efficiency)
\$1.90 12300 BTU  X  79,500 KW  X  491  X    (.95 - .835)     =       \$104,907 (this temp range only)

Notes:
1. 100% efficiency for Turbine without pre-cooling intake air is 83.5 Megawatts output @ ISO conditions of 590(f) at sea level.
2. Dollar value of product is based on \$.06 per kilowatt hour. Additional Gas Cost and water usage is not included.
3. On Combined Cycle Configuration more output in Gas Turbine results in more steam production for the steam turbine.  Typically at the ratio of 1 MW steam for every 2 MW increase of the Gas Turbine.  This factor is not included in the above and contributes to an offset in additional gas usage.  Additional water usage is minimal at the higher output.
4. Total hours are based on climate conditions reported by NOAA for a 3 year running average for Phoenix, AZ., which is similar to Las Vegas, NV., and other Southwest areas.
5. Evaporative cooling efficiency is based on using 12" thick Glacier-Cor Super Saturation Rigid Media @ 95% saturation efficiency @ 500 FPM face velocity.. Noise levels outside the Turbine are greatly reduced with the installation of the Premier Air Inlet Cooling/Filtration Unit configuration..

ASSUMPTIONS: Increased earnings are based on Turbine operation during all hours available for evaporative cooling use as indicated.
Downtime for the Turbine is not taken into consideration. Actual increased earnings would have to be determined on each operating hour.
Climate conditions are based on inlet air humidity of .0064/lbs of moisture per pound of dry air at sea level pressure of 101kPA. This condition will vary based on actual climate conditions.

Payback period from Evaporative Cooling
Payback period can be generally determined (estimated) by the following formula:
(A + B + C + D) - E

A = Acquisition cost less tax/investment credits.
B = Operating costs such as increased fuel, water, etc.
C = Maintenance costs including expendable equipment replacement.
D = Depreciation provision can be included if desired.
E = Increased Earnings due to higher Turbine efficiencies.

GENERATOR ROOM COOLING

A very significant source of additional savings with a short-term payback period is an investment in Evaporative Coolers for Generators. A typical installation is to mount Evaporative Cooling Modules on each side of the Generator room and use exhaust air to be pulled through the coolers and over the generators. Cooling is needed to keep the generator in it's design operating range.

Click here to go to actual performance data of Westinghouse 501B6 Turbine during 1998.