b. Temperature at compressor and turbine discharge.
4. Machine speed
a. Machine speed of all shafts
5. Thrust-bearing temperature
a. Thermocouples or resistance temperature elements embedded in front and rear thrust bearing
.esirable Instrumentation .Optional.
1. .oncontacting eddy-current vibration displacement probe adjacent to:
a. Inlet bearing， vertical
b. Inlet bearing， horizontal
c. Discharge bearing， vertical
d. Discharge bearing， horizontal
2. .oncontacting eddy-current gap-sensing probe adjacent to:
a. Forward face of thrust-bearing collar
b. .ear face of thrust-bearing collar (.ote: The noncontacting sensor in its role of measurement of gap DC voltage is sensitive to probe
and driver temperature variations. Careful evaluation must be conducted of sensortype， itsmounting， and location for this measurement.)
3. Process flow measurement at inlet or discharge of machine
4. .adial-bearing temperature thermocouple or resistance temperatureelement embedded in each bearing， or temperature at lube oil dis-charge of each bearing.
5. .ube
oil pressure， temperature， and corrosion probe
6. Dynamic pressure transducer at compressor discharge for indication of flow instability
7. Fuel system (water capacitanceprobe， corrosionprobe， and Btu detector)
8. Exhaust gas analysis
9. Torque measurement
Figures 19-10 and 19-11 show possible instrument locations for an indus-trial gas turbine and centrifugal compressor.
Criteria for the Collection of .erothermal .ata
Turbomachinery operating pressures， temperatures， and speeds are very important parameters. .btaining accurate pressures and temperatures willdepend not only on the type and quality of the transducers selected， but also on their location in the gas path of the machine. These factors should be carefully evaluated. The accuracy of pressure and temperature measure-ments required will depend on the analysis and diagnostics that need to be performed. Table 19-2 presents some criteria for selection of aerothermal instrumentation of pressure and temperature sensors for measurement of compressor efficiency. .ote that the percentage accuracy requirements are more critical for temperature sensors than pressure sensors. The require-ments are also dependent on the compressor pressure ratio.
.ressure .rop in Filter System
The prime design objective of the filter system is to protect the gas turbine. The performance of the gas turbine inlet-air filter system has important andfar-reaching influences on overall maintenance costs， reliability， and avail-ability of gas turbines. There are three major results of improper air filtra-tion: (1) erosion， (2) fouling of the axial-flow compressor， and (3) corrosion of the gas turbine hot-gas path inlets. The importance of the inlet-airfilter， as it relates to each of these three phenomena， can be appreciated if
66. Gas Turbine Engineering Handbook Control Systems and Instrumentation 663
Table 19-.
Criteria for Selection of .ressure and Temperature Sensors for
Compressor Efficiency .easurements
Compressor .. Sensitivity ... .. Sensitivity ... .ressure .atio ....1
6
0.704 0.218
7 0.750 0.231
8 0.788 0.240
9 0.820 0.250
10 0.848 0.260
11 0.873 0.265
12 0.895 0.270
13 0.906 0.277
14 0.933 0.282
15 0.948 0.287
16 0.963 0.290
Tabulation showing percent changes in .2 and T2 needed to cause .% change in air compressor efficiency. Ideal gas equations are used.
one considers the fact that the gas turbine ingests about 7000-9000 cf (198.2179-254.8516 cm) of air per minute for every megawatt of power produced.
Temperature and .ressure .easurement for Compressors and Turbines
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