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Passive acoustic power spectra to monitor and control processing

  • US 4,877,488 A
  • Filed: 07/13/1987
  • Issued: 10/31/1989
  • Est. Priority Date: 10/30/1986
  • Status: Expired due to Term
First Claim
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1. A process for the non-intrusive passive acoustic detection and measurement of a change in thickness of a wall defining a reactor for processing material, wherein said change in thickness is due to erosion of said wall or material buildup on said wall, the wall vibrations produced during processing of the material within the reactor by impact of the material with the interior surface of the wall comprising:

  • (a) measuring the wall vibrations of said reactor wall and then determining a first power spectrum indicative of the measured wall vibrations as a function of frequency at a time t=0 while said reactor is operating,(b) operating said reactor for a time t,(c) measuring the wall vibrations of said reactor wall and then determining a second power spectrum indicative of the measured wall vibrations as a function of frequency at said time t, while said reactor is operating.(d) determining a frequency shift of a resonance on said first spectrum from the corresponding resonance on said second spectrum, and(e) correlating said frequency shift with the change in thickness of the reactor wall.

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