CST, for prevention and remedy of vibrations in reciprocating compressor systems
Vibration is one of the main and more common causes of failure or unscheduled shutdown on rotating equipment. Reciprocating compressors in particular are often affected by vibration issues, since these are inevitably generated by the reciprocating motion and the pressure pulsations found in these machines.
Pressure pulsations can be originated by flow pulsations, which can in turn degenerate into acoustic resonance phenomena; therefore it is
important that pulsations are be kept as low as possible. In this way it is possible to ensure that the energy contained in these pulsations interacts as
little as possible with the plant mechanical system, generating less possible “shaking forces” and vibrations.
Furthermore, if the natural frequency of a mechanical part of the plant (whether it is piping, vessels, or support) coincides with an exciting
acoustic frequency, a mechanical resonance phenomenon may occur; this situation, bringing the system to very high vibration amplitudes, represents
in most of the cases, the main cause of cyclical fatigue failure of supports or small pipe branches.
During detailed engineering, technical countermeasures can be taken to avoid high levels of vibration: i.e. appropriated foundation design,
forces and couples balancing, volume bottles, orifices and suitable pipe supports.
Despite this, vibration problems sometimes still show up from the very first machine start-up, and not always as a result of poor detailed engineering;
in many cases the cause is to be found in not having paid enough attention to the interaction between the compressor and the rest of the system.
For the reasons above, the success of the project can be significantly affected by the assessments and decisions regarding methods of controlling
pulsation and vibration that must be taken already from the early stages of detailed engineering. The help of a consultant experienced in this field, like
Compression Service Technology, plays a key role: he has a comprehensive and unbiased view and has two important tasks: to ensure the goals of a state of the art design and to ensure that critical decisions about efficiency, safety and reliability are taken wisely and in the shortest time as possible.
The safety and reliability of a plant remain therefore a key factor for CST and avoiding high vibrations and the consequent breakage of the pipes, is our first mission for an optimal and safe plant operation.
