Alternative compressors

The predictive maintenance service for monitoring the functional and mechanical analysis of reciprocating compressors is based on multi-channel processing of in-cylinder pressure, high and low frequency vibration, ultrasound and temperature signals.

Measurement synchronization is performed with an encoder or tachometer, which serves as a piston position reference, in single and double acting cylinders, and in multi-stage compressors, driven by an electric motor or internal combustion engine.

From the closed P-V curve, the indicated or thermodynamic power (IHP), capacity and volumetric efficiencies in suction and discharge are calculated, and the head losses in valves can be evaluated.

From the open pressure curve correlated with the other mechanical variables can be detected:

• Clearances in crosshead elements (pin and sliders)
• Gas leaks in valves and piston rings
• Pressure pulsation
• Excess of head losses in conduit passages
• Cylinder liner wear
• Insufficient stem stress reversal
• Stem fatigue overloading
• Dysfunction of arresters

The diagnosis of the functional and mechanical condition of a reciprocating compressor is based on the analysis of the in-cylinder pressure curve (P-V ), according to the following procedure:

• Cylinder pressure measurement, synchronized with crankshaft position through encoder or dead center reference tachometer.
• Measurement of mechanical variables synchronized on the pressure pattern (vibration, ultrasound, temperature).
• Experimental calculation of indicated power (IHP) with evaluation of volumetric efficiencies, flow balance and compressor capacity, and stress analysis in connecting rod by composition of the experimental static load (pressure) and the theoretical dynamic load (inertia of the reciprocating train).
• Identification of valve, gas passage (pulsations and restrictions) and mechanical problems (impacts, friction and clearances) of the reciprocating train and its bedplate supports.
• Functional and mechanical status report with palliative recommendations, consult Preditec for more information.