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Reciprocating compressor diagnostics


Problem

 
Abnormal power consumption on natural gas reciprocating compressor.
 
 
Overview
 
The customer complained an abnormal power absorbment on his natural gas reciprocating compressor. This affirmation began from the power consumption read from the compressor’s drivers (gas motor).
SINT Technology suggested to carry out a P-V cycle and torque analysis in order to understand the real power used by compressor and find the cause of this high consumption.
 
 
On-Site measurement campaign
 
A complex on-site measurement campaign was planned.
Particularly, following measurements were done:
 
  • P-V cycles measurements
  • Torque measurement on driven shaft
  • Temperature and pressure measurements on each stage (static parameter)
  • Temperature on each valve cover
 
 
 
 
 
 
 
 
 
 
Figure 1 - Measurement chain for P-V cycle and static parameters
 
Figure 2 – Measurement chain for torque measurement
 
 
Results
 
Practically, the measurements were carried out in the following configurations:
 
  • OLD Valves
  • NEW Valves
 
The measurement results are summarized follow.
 
 
 
   
 


Table 1 – Results summary
 
Figure 5 – Valve cover temperature summary
 
 
Conclusion
 
The measures carried out on the compressor, with the old valves, had shown an excessive power consumption compared to standard conditions.
Particularly, the data analysis with the old valve configuration, specially on the cylinder no. 2, shows an evident discrepancy between theoretical and measured cycles.
Principally, we note the excessive valve loss specially at the discharge.
Also the valve cover temperature analysis show an excessive temperature at the discharge.
 
These losses are connected to the reduction of the valves passage section.
An inspection of the valves had confirmed this problem (see following figures). Hence, a substitution of the valves was decided.
 
 
Figure 6 - Cylinder 2 – HE valve               Figure 7 - Cylinder 2 – HE seat valve
 
The new measurement campaign carried out with new valves configuration has shown a very good improvement. A very good correspondence between measured and theoretical cycles were reached and a substantial increase of the machine efficiency was observed.
 
 
Successfully
 
Problem solved in few days.
Thanks to measurement campaign and the analysis carried out, it was possible to find the causes and also the solution to the abnormal power consumption.
Thanks to SINT Technology, an efficiency increase of 13% was reached.
 
 
Advantages
 
  • Machinery efficiency increase
  • Reduction of running costs
  • Reduction the maintenance costs
  • Quick problems troubleshooting thanks to real time data elaboration
  • Easy installation in field
  • Smart design of the test