Content area
Full text
Follow these practical tips to determine the condition of your centrifugal compressors.
Centrifugal compressors are vital equipment in many chemical process industries (CPI) applications, including oil refining, chemical and petrochemical manufacturing, and natural gas processing. As such, it is important for chemical engineers to understand the basics of centrifugal compressors and their operation, which was the topic of a previous CEP article (1), as well as how to evaluate the performance of this critical equipment.
Performance testing may be done to:
* verify the guaranteed performance operating conditions
* determine how to improve performance when the compressor does not perform as required or does not satisfy process requirements
* ascertain whether performance problems are being induced by the installation
* track the condition of the compressor internals, especially if the gas is corrosive or causes fouling, or if a process upset has occurred that might damage the compressor
* provide information that may be useful for modifying existing equipment
* enable the gas composition to be estimated.
This article outlines methods for testing centrifugal compressors at the plant site. It focuses on evaluating a compressor's aerodynamic performance rather than mechanical testing (such as vibration and bearing temperature monitoring). The article does not address performance testing of fans, blowers, or other types of compressors (e.g., reciprocating, axial, screw), or the testing of materials and other components that are generally associated with quality assurance.
Note that the preferred method of establishing centrifugal compressor performance is under controlled laboratory conditions, generally by the compressor manufacturer at the factory and often witnessed by the purchaser. The field test procedure described here should not be used for that type of testing, which requires adherence to test codes, such as ASME PTC-10 (2).
When to test
Schedule the test for a time when suitable operating conditions can be maintained and the presence of key personnel to carry out the test can be assured. Allow enough time for the test team to determine the objectives of the testing and to obtain the proper instrumentation before starting the actual test.
If the purpose of the testing is to verify the guaranteed performance, the compressor manufacturer will want the test to be conducted as soon as possible after the compressor has started running....