Figure 4-1.. Typicalprotection system for a turbine.
the proximity probe. This is because of the expansion of the shaft casing and the probability that the probe is located far from the thrust collar.
認(rèn)hen designing a system for thrust bearing protection， it is necessary to monitor small changes in rotor axial movement equal to oil film thickness. Probe system accuracy and probe mounting must be carefully analyzed to minimize temperature drift. Drift from temperature changes can be unac-ceptably high.
A functional alternative to the use of proximity probes for bearing protec-tion is bearing temperature， bearing temperature rise (bearing temperature minus bearing oil temperature)， and rate of change in bearing temperature. A matrix combining these functions can produce a positive indication of bearing distress.
A phase angle transducer should also be supplied with each train. This transducer should record one event per revolution.認(rèn)here intervening gear-boxes are used， a mark and phase angle transducer should be provided for each different rotational speed.
Specifications
The previous API standards are guidelines to information regarding machine train applications. The more pertinent the information obtainedduring the evaluation of the proposal， the better the selection for the prob-lem. The following list contains items the user should consider in his attempt to properly evaluate the bid. Some of these points are covered in the API standards.
Table 4-2 indicates the main points an engineer must consider in evaluat-ing different gas turbine units. Table 4-3 lists the important points that must
Table 4-2 Point to .onsider in a Gas Turbine
1. Type of turbine:
a. Aero-derivative
b. Frame type
2. Type of fuel
3. Type of compressor
4. No. of stages and pressure ratio
5.Types
ofblades， bladeattachment， and wheel attachment
6. No. of bearings
7. Type of bearings
8. Type of thrust bearings
9. critical speed
10. Torsional criticals
11. campbell diagrams
12. Balance planes
13. Balance pistons
14. Type of combustor
15.認(rèn)et
and dry combustors
16. Types of fuel nozzles
17. Transition pieces
18. Type of turbine
19. Power transmission curvic coupling
20. No. of stages
21. Free-power turbine
22. Turbine inlet temperature
23. Type of fuels
24. Fuel additives
25. Types of couplings
26. Alignment data
烏ablecon烏inued onnex烏 page
Table 4-2con烏inued
27. Exhaust diffuser
28. Performance map of turbine and compressor
29. Gearing
30. Drawings
Accessories
1. Lubrication systems
2. Intercoolers
3. Inlet filtration system
4. control system
5. Protection system
Table 4-. Vendor Requirements to be Provided by the User for a .ompressor Train
1. The
Gas烏o Be Handled (EachS烏ream composition by mol%， volume%， or weight %. To what extent does composition vary?corrosive effects. Limits to discharge temperature， which may cause problems with the gas.
2.
Quan烏i烏.烏o Be Handled for EachS烏age Stage quantity and unit of measurement.If byvolume， show: a.認(rèn)hether wet or dry.
b. Pressure and temperature reference points.
3.
Inle烏Condi烏ions for EachS烏age Barometer. Pressure at compressor flange. State whether gauge or absolute. Temperature at compressor flange. Relative humidity. Ratio of specific heats. compressibility.
4.
DischargeCondi烏ions Pressure at compressor flange. State whether gauge or absolute. compressibility. State temperature reference.
5.
In烏ers烏ageCondi烏ions Temperature difference between gas out of cooler and water into cooler. Is there interstage removal or addition of gas? Between what pressures may this be done? Advise permissible range.If gas isremoved，treated， and returned betweenstages， advise pressure loss.認(rèn)hat quantity change is involved?If this changes gas composition， a resultant analysis (ratio of specific heats， relative humidity， and compressibility at specific interstage pressure and temperature) must be provided.
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