Title
Elimination of flow-induced pulsations and vibrations in a process installation: a combination of on site measurements, calculations and scale modeling
Author
TNO Industrie en Techniek
van Bokhorst, E.
Peters, M.C.A.M.
Publication year
2008
Abstract
The aim of the work described in this paper was to trace and eliminate vibration sources in a low pressure system with high flow velocities. Considerable vibration on the pipe system between a flashing vessel (6.5 m diameter) and heat-exchangers resulted in fatigue failure, leakage and subsequent shut down of a chemical production plant. As compressors or pumps were not directly involved in the process, we considered aero-acoustic pulsations as the main cause of the high vibration levels. Analysis of the flow in the pipe system showed that mean flow velocities could rise up to 50m/s, which is rather high considering the speed of sound in the gas of 195 ms/s. Furthermore separation of the flow from the pipe wall occurs at the outlets of a flashing vessel, which resulted in estimated flow velocities of over 100 m/s in the vena contracta. This paper provides an overview of the analysis done by a onedimensional acoustical model and scale modeling of part of the piping. The recommended modification consists of a perforated pipe section between the outlets of the vessel and has been tested in a scale model. Tests have been performed with airflow at identical Mach numbers for different configurations with perforation ratios form 70 to 36%. The modification with a perforation ratio of 70% shows a reduction of a factor 5 of the pressure pulsation and vibration levels over the entire frequency range. The net pressure loss for this configuration is similar to that in the original lay-out without the perforated tube. This modification was implemented during a plant shutdown and proved to be very effective. The results are well in line with the predicted levels and on the basis of this success a similar design has been planned for two new installations.
Subject
Flow velocity
Lattice vibrations
Machine design
Plant shutdowns
A-Plant
Acoustical model
Chemical production
Fatigue failures
Fluid machineries
Frequency ranging
Mach numbers
Mean flow velocities
Mechanical engineers
Net pressure
On-site measurements
Pipe systems
Pressure pulsations
Process machinery
Scale modeling
Vibration levels
Vibration sources
Process engineering
Industrial Innovation
To reference this document use:
http://resolver.tudelft.nl/uuid:a6e2b402-2c16-49c7-ae0a-8c6618c67a23
TNO identifier
241026
ISBN
9781843344926
Source
10th European Fluid Machinery Congress, Advances in the Optimisation, Design and Maintenance of Process Machinery, 21-23 April 2008, Amsterdam, The Netherlands, 103-111
Document type
conference paper