vibration measurements and analyses to enhancing plant
TRANSCRIPT
Vibration Measurements and Analyses to
Enhancing Plant Reliability
Jyoti K. Sinha, CEng, FIMechE
Programme Director,
Reliability Engineering and Asset Management (REAM) MSc
Head, Dynamics Laboratory
Head, Structures, Health & Maintenance (SHM)
Department of Mechanical Aerospace and Civil Engineering
The University of Manchester, UK
Email – [email protected]
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"Everything should be made as simple as possible, but not simpler”
“Current thinking can not solve the current problem created by current
thinking”
IncoME-V 2020, BIT ZhuhaiSource: Google Image
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Albert Einstein
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Content
• Introduction and Background
• Examples
-Design Qualifications
-Design Modification/Optimisation
-Structural Health Monitoring
-Machine Installation
- Aged Machine
• Concluding Remarks
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Quality; Productions; Safety.
No Reactive Maintenance.
Low Maintenance Overhead.
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How to achieve?
Plant objectives
Background & Introduction
Source: Google Image
Background & Introduction
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Reliable Design qualifications.
Root Cause Analysis based on PHYSICS of the subject
Robust Health Monitoring (Accurate Predictive approach).
ENSURE OVERALL GOOD RELIABILITY OF EACH ASSET
(‘old age’)
(‘infant mortality’)
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Examples: Few Failures due to High Vibration
Tacoma Narrows Bridge Earthquake
Gearbox failureSource: Google images
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Source: MAMJ, 30(5), 2015
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Few Typical Industrial Examples
Source: Noise & Vibration Worldwide 37(5) 2006Source: Shock & Vibration Digest 29(2) 1997
Source: Paper No. C06,NCAM-2004, India.
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Blind Men and Elephant
“Trial and Error” Method!!!
Source: Google Image
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• Replace or repair faulty parts
• Replace by New Machine
• Machine from different
manufacturers
• Several other attempts
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Mass (m)
Spring
m
Physical Representation Representation of a Dynamic System
Equation of Motion:
Inertia Force + Damping Force + Stiffness Force = External Force
m a(t) + c v(t) + k y(t) = F(t),
Damping
(c)k
y(t)m
AccelerationVelocity
Displacement
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A Simple Vibration System Background
Design Qualification and/or Optimization.
Machine Installation
Health Monitoring - Mechanical & Civil Structures
- Machines
- Piping
Age related problem in Machines and Structures
Isolation and Control, etc.
Broader Roles of Vibration Analysis
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IncoME-V 2020, BIT Zhuhai
Vibration Measurements & Analyses
Source: Google Image
+
Jyoti K. Sinha, Book cover page, CRC Press, 2014
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Design Qualifications
Static Qualification: Static loads bearing capacity
Dynamic Qualification
Seismic Qualification
Design Optimisation to meet the design requirements
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Methods
• Analysis – Limitation FE Model itself.
•
• Shake Table Testing – Availability?
• Comparison
Seismic Qualifications
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Ideal FE Model In-situ Modal Tests
Significant Difference in Modeshapes. Stress ?
Storage TankApprox. 24m long and 4m dia.
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Max deformation due to Seismic loads
Comparison of the ideal (FE model with ideal boundary conditions)
and the experimental (in-situ) cases of deflection of Tank in lateral
direction due to Design seismic loads
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In-service loads:- Flow-induced Excitation.
- Machine induced vibration.
Methods:- Full scale Experimental model with Excitation facility.
- In-situ Tests and Analysis during Installation and
commissioning.
Dynamics Qualification
and Design Modification
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Design Modification in Fuel Channel
of a Research Reactor
Flow Induced Vibration
Original Design Modified Design
Vibration:
Flexing
along
length
Vibration:
NO
Flexing
along
length
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Contact Detection: Two Co-axial Tubes with two spacers
235MWe PHWR contains 306 Coolant Channels
Front View
Side View
Source: Nucl Eng Design 155(3), 591-596, 1995
flo
w
flow
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Coolant Channel
Source: Google Image
Contact
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Contact Detection: Two Co-axial Tubes with two spacers
Contact between inner
and outer tubes is not
acceptable for the
safety reason!
Intrusive inspection of
3 channels per day is
only possible!!
Vibration-based
contact detection
takes only 3 days to
inspect all 306
channels
Source: Nucl Eng Design 155(3), 591-596, 1995
Contact
No Contact
flo
w
Combined Spectrum
Flow Induced
Excitation
flow
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Centrifugal Pumps: Study during installation and commissioning in Jan 1991
Pump Assembly
N
Acceptable
vibration level
Source: Noise & Vibration Worldwide 37(5) 2006
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High vibration at casing
– Not Acceptable
Modal Tests conducted
54Hz
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Resonance at 2nd mode with Pump RPM 3000RPM
causing HIGH VIBRATION at Casing.
Source: Noise & Vibration Worldwide 37(5) 2006 & JKSinha, Book, CRC Press, 2015
Pump
Stool
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Solution:Stiffening of Stool by welding a thick plate.
Additional “U” bolts to the discharge line.
NO ANY MAJOR PROBLEM SINCE 1991
Centrifugal Pumps: Diagnosis & Solution
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Centrifugal Pump: Aging effect
Pump Motor
Coupling Bearings
• 1500RPM, 23000LPM
• Commissioned in 1984.
• Frequent failure of both bearings.
• Faults always detected by Contl. condition monitoring.
• Main root cause ?
Source: Insight 48(8) 2006
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Pump: Vibration Measurements
Source: Insight 48(8) 2006
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Pump
Motor
Bearing
Pedestals
Modal tests conducted.
Resonating at 2x with 2nd mode.
Solution:
Supports Stiffening
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Concluding Remarks
“Early failure”
related to
Design/ Installation
“Useful Life”
related to
Random Failure
“Old Age”
related to
Frequent Failure
1st Stage
2nd Stage
Condition Monitoring 3rd Stage
3 stages in Vibration Analysis can change “Bath Tub Concept”!
Source: Google Image
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Examples demonstrate the usefulness of Vibration
Measurements and Analyses in different industrial
applications to enhance Plant Reliability.
‘Magic Solution’Vibration (Ant) problem in
Structures/Machines (Elephant)
Source: Google Image
Concluding Remarks