Compressor Pulsation Study, Three stage reciprocating

Design Approach 2 / 3 stage / Parallel operation / 300rpm / Revamping / 3300kW

Acoustic, Vibration, API 618, API 688, Design approach 2, Reciprocating Compressor

Three (3) stage reciprocating compressors has been running for 25 years, since these compressors had been initially commissioned after construction. With consideration of improved process demand, it was necessary to revamp the process and pipe condition for these compressors, and this was due to perform new pulsation study. This pulsation study was performed as per Design Approach 3 procedure in accordance with API 618, API 688, and this page shares the analysis status of Design approach 2.

Scope of this analysis
Pulsation for Existing condition
Vibration Survey
Case Study
Pulsation Amplitude

1. Scope of this analysis

The scope of service for this pulsation study as Design approach 2 below activities;

Review for Existing Pulsation Study
Acoustic Modeling
Vibration Site Survey
Case Study as per Cylinder Phase Difference
Design Approach 1, Surge Volume Sizing as per API 618
Design Approach 2 for Acoustic Simulation
Pulsation Limit & Criteria Assessment
Pressure Drop by Surge Volume and Orifice

acoustic model for pulsation, API 618, Shaking Force — [Acoustic Model for Pulsation, Suction]

acoustic model, descharge, API 618, Shaking Force — [Acoustic Model for Pulsation, Discharge]

2. Pulsation for Existing condition

Pulsation study for existing condition was carried out, so that we can confirm if there is no design issue with high pulsation amplitude.

Review the previous pulsation study
To check the design reliability for pulsation control device
To check if the pulsation level by existing condition is complied with API 618
For suction, inter-stage, discharge piping system
Review the compressor operation data for Existing and Revamping condition

peak peak pulsation level, API 618, surge volume, Shaking Force — [Peak-Peak Pulsation Level]

3. Site Vibration Survey

Vibration survey and measurement was done at Site, and INERTANCE engineers checked if there was no high vibration issue for piping system with existing condition. And, the measured vibration levels were compared with related vibration criteria such as EFRC (European Forum for Reciprocating Compressors), ISO 10816-8 and Wachel chart, etc.

Measurement for pipe vibration
Vibration check for Crank case, Cylinder flange, Pulsation bottle, Piping system, etc.
Assessment for vibration criteria listed in below
EFRC (European Forum for Reciprocating Compressors)
ISO 10816-8
Wachel chart

vibration measurement point, surge volume, Shaking Force — [Vibration Measurement Point]

Vibration for Piping System, orifice, Shaking Force, surge volume — [Vibration for Piping System]

Vibration for Pulsation Bottle, surge volume, Shaking Force — [Vibration for Pulsation Bottle]

4. Case Study – compressor pulsation study

When these compressors are to be operated in conjunction with other compressor units and their associated piping system, the additive effect of pressure pulsations from multiple units shall be addressed. It was planned to run these compressors with parallel operation, hence, Case study was necessary to find out the worst case scenario as per each compressor cylinder phase difference.

Possible operation case to be checked
Step operation for reciprocating compressor (25%, 50%, 75%, 100%)
Single acting (SA) and Double acting (DA) operation
Cylinder phase difference for parallel operation
Multiple unit additive effects
Start-up operation with Nitrogen gas

Compressor Cylinder Phase Difference, API 688, surge volume — [Compressor Cylinder Phase Difference]

5. Pulsation Amplitude

Design approach 2 was to perform the acoustic simulation and piping restraint analysis, which include the pulsation control design via the use of pulsation suppression devices and proven acoustic techniques.