BINSFELD ENGINEERING INC.

April 2014

 
 





Oil and gas industry - refinery at twilight - factory - petrochemical plant
            Oil Refinery at night.



 





 
Torque Talk   Apr 2014  
 
This is an impressive bit of engineering work by Troy Feese at Engineering Dynamics Inc., successfully diagnosing an expensive equipment failure and then implementing the proper solution.

 

If you have a good application or success story involving the TorqueTrak instruments that you would like to share in this newsletter, please send it to me for consideration.

 

 
Thank you.
 
Bob Holden
Sales Manager

 

 

 

Case History:  Motor / ID Fan System for Main Crude Unit at Refinery

 

 By Troy Feese, P.E.

Engineering Dynamics Incorporated

San Antonio, Texas, USA

Web: http://www.engdyn.com/

 

 

Engineering Dynamics Incorporated (EDI) performed a field test of an induced draft (ID) fan system at a refinery that was experiencing failures of couplings, flexible disc style.  The fan is part of an atmospheric furnace that heats approximately 152,000 barrels of crude per day.  The ID fan is driven by a 350 HP induction motor.  The motor speed is controlled by a variable frequency drive (VFD) from 0 to 1200 RPM.  The trouble began when the motor was changed out for one of similar electrical performance, but of different physical size.

 

The failure of the original flexible disc coupling consisted of a crack in the spacer, which appeared to originate at a bolt hole.  Initially, plant maintenance was blamed for possibly over tightening the coupling bolts.  The 45 degree angle of the crack in the coupling spacer is a typical indication of high torsional vibration.

 

To quantify the transmitted and dynamic torque in the coupling, a TorqueTrak 10K telemetry system from Binsfeld Engineering was used.  The waterfall plot below shows a torsional natural frequency (TNF) of the system near 58 Hz, which was being excited by 1× electrical frequency of the VFD.   This resulted in high dynamic torque in the coupling when operating the fan at 1000 - 1200 RPM.

 

EDI performed a torsional analysis of the system and selected an alternate coupling with standard rubber blocks in compression to detune the TNF away from the 1× electrical frequency of the VFD.  The new coupling was installed and the equipment has been working satisfactorily for over 6 years.  This case history shows the importance of performing a torsional analysis on a new system or when a system is modified.  The TorqueTrak 10K strain gage telemetry system from Binsfeld Engineering was very valuable in collecting data and determining the cause of the original flexible disc coupling failure.

 

Products from Binsfeld
TorqueTrak Revolution
Continuous Torque and Power Data
 Designed for permanent installations and continuous monitoring, the TorqueTrak Revolution instrument fromBinsfeld Engineering Inc. provides continuous output data from the rotating shaft for four key parameters: torque, power, RPM and direction of rotation. It is an inductive, non-contact system - no batteries, no wear surfaces - machined to fit the shaft, up to 40 inches diameter.
 
TorqueTrak 10K
Fast & Easy Torque Measurements
For temporary testing or short term measurements it doesn't get much easier than theTorqueTrak 10Ktelemetry instrument from Binsfeld Engineering Inc. Accurate and simple to use, the TorqueTrak 10K fits any size shaft and any torque level. It is ideal for field work and troubleshooting marine propulsion systems, drive systems, compressors, conveyors and other large machinery. Normally, units are in stock, ready to ship.

 

© Binsfeld Engineering Inc. All Rights Reserved.

4571 W. MacFarlane Rd. ● Maple City, MI 49664 ● USA

Phone: 231.334.4383 ● Fax: 231.334.4903 ● Toll Free: 800.524.3327

bob@binsfeld.com