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Pulsation Study for Reciprocating Compressor
The pulsation study for reciprocating compressor could be performed as per API 618, and INERTANCE has a capability to perform below kinds of acoustic analysis , shaking force estimation and mechanical study as per Design approach procedure.
- Pulsation Study as per API 618
- Pulsation Suppression Device
- Surge Bottle Sizing as per API 618 & API 11P
- Shaking Force (Unbalanced Forces)
- Acoustic Simulation
- Calculation of Peak-to-Peak Amplitude Levels
- Piping Vibration Criteria
- Piping Modification
- Mechanical Review and Piping Restraint Analysis
- Mechanical Study for Natural Frequency
- Separation Margin Requirements
- Acoustic Controls by Orifice
- Acoustic Resonance
- Acceleration Head
- Surge Volume and Acoustic Filter
- Helmholtz Frequency Estimation
The objective to perform this study is to avoid problems with vibration, performance, reliability, and flow measuring error caused by acoustical interaction between the compressor and the relevant piping system.
Pulsation study procedure has been determined as per API 618 guideline.
Here, INERTANCE shows the brief procedure for related study of reciprocating compressor as follows;
Pulsation Study : Design Approach 1
Design Approach 1 is to perform the empirical pulsation suppression device design using proprietary and empirical analytical techniques to meet line side pulsation levels and the maximum pressure drop based on compressor normal operating condition.
Design Approach 2
Design Approach 2 is to perform the acoustic simulation and piping restraint analysis, which include the control design through the use of pulsation suppression devices and proven acoustic techniques. In case the detail design of piping system is finalized, the acoustic simulation has to be performed for system reliability. Then, the separation margin based on mechanical natural frequency has to be checked to avoid the mechanical resonance.
Design Approach 3, API 618
Design Approach 3 is to perform the mechanical analysis with forced mechanical response analysis in addition to Acoustic study. The forced mechanical response analysis for compressor cylinder as well as associated piping systems has to be performed as results of previous analysis results.
INERTANCE has a capability to select the sizing of surge volume as well as low pass filter, and the related pipe support design, where necessary.
Recent Project – Pulsation Study of reciprocaitng compressor
INERTANCE recently performed a pulsation analysis of a reciprocating compressor.
These 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
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
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.
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
Case 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
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.
- Pulsation control device design
- Surge volume, Pulsation bottle, Pulsation suppression device
- Orifice at compressor cylinder flange
- Pipe support span table for separation margin
- Pulsation induced shaking force
- Shaking force assessment and criteria by API 618
- Pulsation at cylinder flange, Surge volume and piping system
Key Words
- Reciprocating Compressor
- Pulsation
- Acoustic
- API 618, API 688
- Vibration measurement, survey
- Surge Volume, Orifice
- Shaking Force
- Vibration
INERTANCE has a capability regarding noise and vibration engineering, and our experts are familiar with assessment of API 618 study & Mechanical study. For further information, contact us at (mountain@inertance.com).
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