Monitoring Variable Speed Bearings Using Ultrasound Dr James Neale BE ME PhD CMRP Energy Research Group University of Waikato Hamilton New Zealand
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Energy Research Group Overview Research into improving Industrial Energy Efficiency Compressed Air Steam Utility Loop Optimisation Heat Recovery and Heat Integration Pinch Analysis Industrial Fluid Flow Optimisation Renewable Energy Solutions Distributed Generation Energy Audit Methodology Development Energy Efficiency Policy Development Applications of Ultrasound Airborne Structure Borne
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Presentation Overview 1. Project Rationale a. Site: Fonterra Te Rapa b. Applications 2. Project Definition a. Variable Speed Applications b. Test Variables 3. Laboratory Testing a. Applications b. Results 4. In-Plant Implementation 5. Conclusions a. Implementation in Your Plant?
Project Definition 1. Variable Speed Applications a. Q: How does speed impact condition monitoring of bearings? b. Q: What is our acceptance standard? 2. Test Variables a. b. c. d. Speed Test Frequency Alarm levels? How does the acoustic response vary with speed for different applications/equipment?
Laboratory Testing The following equipment was used to test the effect of varying frequency and speed on the ultrasound level recorded. Smart Pump Pulp Screen Water Flume Air Heater Fan
Smart Pump
Smart Pump Bearing noise was measured in db at 4 points: Motor 1 - Outboard Bearing 2 - Inboard Bearing Pump 3 - Inboard Bearing 4 - Outboard Bearing 1 2 3 Motor Specifications: 25 kw 1475 rpm max. 4
Speed v db Results 30kHz
Pulp Screen
Pulp Screen 4 1 3 Bearing noise was measured in db at 4 points: Motor 1 - Outboard Bearing 2 - Inboard Bearing Pump 3 - Inboard Bearing 4 - Outboard Bearing 2 Motor Specifications 15 kw 2935 rpm max.
Speed v db Results 30kHz
Water Flume
Water Flume 1 Motor Specifications 4 kw 960 rpm max. 3 2 Bearing noise was measured in db at 3 points: Motor 1 - Outboard Bearing 2 - Inboard Bearing Pump 3 - Single Bearing
Speed v db Results 30kHz
Air Heater Fan
Air Heater Fan Bearing noise was measured in db at 2 points: Motor 1 - Outboard Bearing 2 - Inboard Bearing 1 2 Motor Specifications 4 kw 1445 rpm max.
Speed v db Results 30kHz
Summary - Speed v db @ 30 khz Variation in speed had little effect on db level of motor bearings tested at this frequency (less than 5 db). Variation in speed had marginally greater effect on db level of the application (driven end) bearings (5 to 25 db). Very application Specific. Potential for actual in-plant usage bands to be quite narrow, resulting in a lower db band in practice.
Smart Pump Frequency Variation
Pulp Screen Frequency Variation
Water Flume Frequency Variation
Air Heater Frequency Variation
Summary - Varying Test Frequency Ultrasound level trends higher at lower test frequency for most speed ranges. db level relatively stable with varying motor speed at all frequencies on motor bearings. db level increased on some pump/prop bearings as speed increased, for all frequencies.
In-Plant Implementation Condition Monitoring Implemented across a range of critical variable speed equipment Water Pumps Main Inlet & Exhaust Fans to Drier Chilled Water Compressors (Ammonia) Plate Freezer Compressors VSD Air Compressor Will be carried out over an extended period to allow long term trending of results.
In-Plant Implementation Measurements db level (using ultraprobe 10000) UP15000 (Please Gary!) motor speed (using displayed speed or a hand held strobe) Sound Files Ultimate Objectives Traffic Light Assessment Green good Red Bad Amber recheck etc Avoid Measuring Speed Keep life simple Sound File Primary Measure of Bad bearing Capture Lubrication Fault in timely manner
Implementation in Your Plant Establish baselines What are the speed limits? High Low How does the db Vary? Motor Driven End (Application) What is your acceptance Standard? Degrees of criticality False alarms? Modified Alarm Levels Lower level => db driven Upper level => Sound File driven
Acknowledgements Energy Research Group University of Waikato UE Systems Inc New Zealand Foundation for Research Science and Technology Research Contract UOWX0302 New Zealand National Energy Research Institute (NERI) Further information: jamesn@waikato.ac.nz