ACUSYS AND ACUSCOMP

Simulation service by ACUSYS and ACUSCOMP according to API 618 standards of the pressure pulsations of one process reciprocating compressor skid

Client: OEM of large machines and plants

SCOPE OF THE WORK

The scope of the work described in this outline is that of performing the compressor system simulation and the analysis of the acoustic pulsations and shaking forces occurring in one process reciprocating compressor skid, to be supplied by the Client for installation in a refinery plant.
The plant object of this pulsation analysis includes the compressor skid produced by the Client and, for the correct performance of the acoustic analysis, the piping extending from the compressors skid to the first large vessel that can be considered as an open end from the acoustic point of view.
The simulations of the whole plant/compressor system were performed for each of the operation cases foreseen in the scope of work and spanning the operational compressor speed range.
The model implementation and simulation were performed by means of SATE's proprietary ACUSYS and ACUSCOMP software, based on the SIMULINK1 environment.
On the basis of the results of the ACUSCOMP simulations at variable speed, the worse speed conditions are selected to perform the complete acoustic pulsation analysis by ACUSYS, which allows verifying the pressure pulsations and shaking forces occurring in the modeled plant vs the API 618 standard limits.
The mechanical natural frequencies of the piping were also calculated to verify that they are far enough from the main exciting harmonics such that resonances induced by the acoustic pulsations do not occur. In order to avoid these resonances, which would generate excessive vibrations, the positions of the piping supports were properly modified and some additional supports were introduced.

1 MATLAB® and SIMULINK® are products by Mathworks Inc. (Natick, Mass, USA). They are a powerful mathematical numerical environment and simulation platform, suitable for multidisciplinary models development and implementation both as desktop and real time operation in embedded systems.

JOB OUTLINE

Input data received from the Client

Compressor datasheet and nominal operation conditions

Valves and equipment drawings and technical specifications

Piping isometric drawings, P&ID and PFD

Indications on the status (open/closed) of the various process valves during operations simulated

Main technical activities performed by S.A.T.E. 

Development of the piping simulation model in the ACUSYS environment

Development of the plant/compressor simulation model in the ACUSCOMP environment

ACUSCOMP simulations for each operation case (e.g. compressor running, start-up or normal operation)

ACUSYS runs to calculate the acoustic pulsations occurring along the piping

Output delivered to the Client

Indications on the remedies to be adopted to avoid exceedances of the API 618 limits on the pressure pulsations and mechanical vibrations (Modified Design)

Technical documentation: Report describing and commenting:

  1. the results of the acoustic pulsations analysis occurring in the Base Design,
  2. the runs and simulations performed to identify the remedies proposed to avoid exceedances of the API 618 limits
  3. the results of the simulations and of the acoustic pulsations analyses obtained with the suggested Modified Design
  4. the results of the mechanical analysis for the Modified piping design
  5. the results of the shaking forces analysis along the piping and the indication of the required supports stiffness to avoid exceedances of the API 618 standards limits

KNOW HOW AND EXPERTISE REQUIRED TO PERFORM THE JOB

The main competences that were needed to perform the job are in the following fields:

  1. Acoustics and fluid dynamics
  2. Machines and process simulation (reciprocating compressors in this case)
  3. API 618 standards
  4. Frequency data analysis
  5. Advanced use of the MATLAB/SIMULINK®  environment