The centrifugal compressor testing article provides you with information about the centrifugal compressor mechanical running test and centrifugal compressor thermodynamic performance test. This content also covers what is called the centrifugal compressor factory acceptance test.
This article is a supplementary article for the Third Party Inspection for Centrifugal Compressor.
Both tests are done separately. The purpose of these tests is to verify the specified mechanical properties and the specified thermodynamic performance data of the compressor.
Centrifugal Compressor Testing - Applicable Standards
The applicable standards for these tests are:
Required Data for Centrifugal Compressor Mechanical Running Test
Following data need to be extracted from a centrifugal compressor design book, datasheet and operating manual and to be available during the test.
Specified Operating Speeds
Maximum Shaft Vibration
Lube Oil Data
Preparation for Centrifugal Compressor Mechanical Running Test
Normally a check list is used for controlling which all items are based design and actual operating condition.
The following components are used from Centrifugal Compressor Test Stand (Not Original)
The following components are used from centrifugal compressor (original)
Note: The coupling and instruments are used from both systems i.e. test stand and original components of compressor
Centrifugal Compressor Testing - Mechanical Running Test
The mechanical running test is done with the following sequence:
Unfiltered and filtered displacement amplitudes and the corresponding phase angles will be recorded and plotted vs. speed during coast down. Bode plots during coast down.
After completion of the mechanical running test and after sufficient cooling-down the compressor will be checked according to the inspection and test plan.
Shaft vibrations and axial displacements are measured. Vibration measurements are carried out with the vendor measuring system. All other necessary instrumentation for vibration analysis needs to be available by centrifugal compressor vendors.
For assessment of the allowable amplitudes of the shaft vibrations according to design the monitoring systems installed in the test stand are used. For visualization and preparing plots a mobile diagnostic system are used.
Run out is determined and recorded. Only these values are binding for the machine. At low speed the shaft vibration monitor only indicates the slow-roll-signal.
If the measured slow-roll-signal values during the test run exceed distinctly the specified run out values, run out are controlled and, if necessary, refurbished after completion of the test run without repeating the test run.
Required Data for Thermodynamic Performance Test
Following data need to be extracted from a centrifugal compressor design book, datasheet and operating manual and to be available for calculations.
Similarly the test medium and related operating parameter need to be identified. N2 normally is used as the test medium. Following also need be specified:
Test Meduim Inlet Condition
Test Meduim Discharge Condition
Centrifugal Compressor Testing - Thermodynamic Performance Test Procedure
Before starting the thermodynamic performance test the compressor is operated for a sufficient period of time at the calculated test conditions to demonstrate acceptable mechanical operation and stable values of all measurements.
All instruments are inspected separately and the measured variables in identical measuring planes are compared to each other.
The duration of the test is depending on the time needed to reach steady-state test conditions. This condition is insured by steady-state values of pressures and temperatures.
An automated data acquisition system is used. The data are recorded, processed and displayed online.
Centrifugal Compressor Testing - Measuring and Analysis
Previous to the test all measuring instruments for pressure and temperature are calibrated. On customer's request the calibration can be redone after the test for one instrument each for pressure and temperature at the inlet and discharge port.
The inlet and discharge pressures and temperatures are measured on the basis of the applicable documents.
The mass flow is measured according to BS EN ISO 5167-2
The shaft power will be calculated with the heat balance method.
For the mechanical power losses the design value is used.
The Reynolds Number correction is done in accordance to ICAAMC.
Measuring uncertainty per BS ISO 5389
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