1. Rotor Dynamic Issues:
* Misalignment: Even slight misalignment between the compressor stages or the entire rotor train can induce significant vibration and lead to increased bearing loads, accelerating wear and spark erosion. This is a prime suspect, especially after multiple overhauls, as components might not have been perfectly aligned during reassembly. Check alignment using laser alignment tools.
* Rotor imbalance: Unbalanced rotors are a major source of vibration. This could be due to manufacturing defects, wear, or damage to the rotor during operation or overhaul. Balancing the rotor is crucial.
* Critical speed issues: The operating speed might be too close to a critical speed of the rotor, leading to resonance and amplified vibration. This requires a detailed analysis of the rotor's natural frequencies.
* Rotor damage: Inspect the rotor carefully for cracks, pitting, scoring, or other forms of damage that can lead to imbalance and vibration. This is especially critical after multiple overhauls; a small imperfection could progressively worsen.
2. Bearing Issues:
* Bearing damage/wear: Even after overhaul, bearings might be incorrectly installed, damaged during installation, or suffering from premature wear due to contamination, improper lubrication, or excessive load. Inspect bearings closely for any signs of wear, damage, or improper fit.
* Lubrication problems: Inadequate lubrication, incorrect lubricant type, or contamination of the lubricant can lead to premature bearing wear and failure, contributing to vibration and spark erosion. Check the oil quality, quantity, and pressure.
* Incorrect bearing preload: Incorrect bearing preload can cause excessive vibration and wear.
3. Other Potential Issues:
* Gearbox problems: Problems within the integral gearbox (e.g., gear wear, misalignment, or broken teeth) can transmit vibrations to the rotor bearings.
* Seal failure: A leaking seal can introduce contaminants into the bearing system, leading to wear and damage.
* Valve problems: Malfunctioning valves (suction, discharge) can cause pulsations that translate into vibrations.
* Foundation issues: Problems with the compressor's foundation (e.g., cracks, settling) can amplify vibrations.
* Electrical issues: While less likely the primary cause of mechanical vibration, electrical problems (shorted windings in motors, etc.) can sometimes indirectly create unusual vibrations.
Troubleshooting Steps:
1. Vibration analysis: Conduct a thorough vibration analysis using accelerometers and spectrum analyzers to pinpoint the frequency and amplitude of the vibration. This will help to identify the source of the problem.
2. Visual inspection: Carefully inspect all components of the compressor, particularly the rotor, bearings, seals, and gearbox, for any signs of damage or wear.
3. Alignment check: Perform a precise alignment check of the compressor stages and the entire rotor train.
4. Oil analysis: Analyze the compressor oil for contamination, degradation, or the presence of metallic particles.
5. Bearing analysis: Inspect the bearing condition and possibly perform specialized bearing analysis to determine the root cause of the wear and failure.
Spark erosion: The spark erosion is likely a *consequence* of the vibration. The vibration causes the rotor to rub or impact against something (perhaps a slightly misaligned component), creating sparks and further exacerbating wear.
Solving this problem requires a methodical approach combining detailed inspection, vibration analysis, and expert assessment. It's strongly advised to consult with Ingersoll Rand service personnel or a qualified compressor specialist for diagnosis and repair. Attempting repairs without the proper expertise could lead to further damage and potentially hazardous situations.
