High Vibration of reciprocating compressor

[sjpark]

I have a problem that reciprocating compressor has very high vibration, 23 mm/sec Peak value.

The period of cylinder is 547 rpm. The dominant freq is 5 x rpm, the amplitude is 22 mm/sec at that freq(2735cpm).

on shop test report, it just had 5 mm/sec around.
After installation in field, the compressor has very high vibration. So, We put a tension bar between structure and the compressor to reduce vibration. It affected reducing vibration for a while. 23mm/sec -> 14 mm/sec

2 month latter, now vibration is increasing.
In my thought, there is no reason for that.

Who has any information about this kind of problem.
Please let me know.

 

[rob768]

resonance of the supporting structure? Is that a possibility?

 

[14739797]

Dear Sjpark
Where exactly is this high vibration ? On the Cilinders?? On the Frame??Would you be more specific Please.

 

[sjpark]

Thank you for your concerning,
I measured the frame(structure) vibration.

 

[14739797]

Dear Sjpark
If the assembling process was done under specification, and everything is properly in the assembling, I mean, ankle bolt are giving a good support to the compressor and the alignment is good and according to the tolerance, you should check the cylinders, do they have supports in the distance piece and in the head of the cylinder? Have you check the run out of the piston rods?? If something of this is not good the might give you high vibrations measures.
Also check the piston rod nut? Sometimes this piston rod nut gets loose and creates vibration in the compressor.
Worn bearings in the connecting rods and in the crosshead (shoe) would cause vibration also. But your equipment is new so I don’t think that this shell might be worn already.
Also check the stroke tolerance, in the head and the crank. If the stroke is out tolerance the piston might be hitting the packing.

 

[sjpark]

thank you so much for your kind and good reply

 

[Monkeywrench]

Check for gas pulsation and use orifices and or bottles to fix. Bracing of lines in and out will also help with this problem. Bolted on mass tuned to cancel resonance can be successful.