Method for the non-destructive control of a particle filter and associated device

Abstract

A nondestructive method for detecting internal defects of a filter, for example a catalytic filter, and a device for implementing the method. The method may be used in particular for treating a gas laden with soot particulates. The filter includes a honeycomb filter element or a plurality of honeycomb filter elements. In the method the presence or absence of the defects is determined by measuring a propagation of a gas stream such as air through the filter element or elements.

1 - 14 . (canceled) 
   
   
       15 . A nondestructive method for detecting internal defects of a filter, or a catalytic filter, or a filter used for treating a gas laden with soot particulates, the filter including a honeycomb filter element or a plurality of honeycomb filter elements including a set of adjacent ducts or channels having parallel axes separated by porous walls, the ducts being sealed by plugs at one or other of their ends, to delimit inlet chambers opening via a gas inlet side and outlet chambers opening via a gas removal side, such that gas crosses the porous walls, the method comprising:
 determining presence or absence of the defects by measuring a propagation of a gas stream or air through the filter element or elements.   
   
   
       16 . The method as claimed in  claim 15 , in which the defects are at least one o: a break in the walls in a honeycomb element or of joints between elements, incomplete sealing of the ducts, cracks in the walls or joints, missing, porous or supplementary plug, inhomogeneous distribution of the wall or joint thicknesses, imperfect seal of a coating cement. 
   
   
       17 . The method as claimed in  claim 15 , in which the presence or absence of the defects is determined by comparison with a reference value corresponding to a filter not having any internal defects. 
   
   
       18 . The method as claimed in  claim 15 , in which the propagation of the gas stream through the filter is evaluated by analyzing a transmission spectrum of an infrared radiation at an outlet of the filter, or by infrared thermographic analysis. 
   
   
       19 . The method as claimed in  claim 15 , in which the propagation of the gas stream through the filter is evaluated by at least one measurement of gas velocity at an outlet of the filter. 
   
   
       20 . The method as claimed in  claim 19 , in which a series of measurements of the gas velocity are taken to obtain a profile of the velocities at the filter outlet. 
   
   
       21 . The method as claimed in  claim 20 , in which the presence or absence of the defects is determined by comparison between the series of gas velocities obtained on the filter. 
   
   
       22 . The method as claimed in  claim 20 , in which the measurement pitch is equal to or lower than the width of a duct. 
   
   
       23 . The method as claimed in  claim 15 , in which the porous walls of the filter are previously loaded with a soot concentration of at least 1 gram per liter. 
   
   
       24 . A device for implementing a method as claimed in  claim 15 , comprising:
 means for sending a gas or air into the filter;   means for confining gas flow introduced into the filter;   means for regulating flow rate and/or pressure of the air introduced into the filter; and   means at an outlet of the filter for measuring the propagation of a gas stream or air through the filter element or elements.   
   
   
       25 . The device as claimed in  claim 24 , in which the measurement means for measuring includes means for measuring gas velocity, selected from propeller anemometers, hot wires, Pitot tubes, hot ball systems, hot film systems, PIV (Particle image velocimetry) type systems, LDA (laser doppler anemometry) type systems measuring the doppler effect associated with the air velocity. 
   
   
       26 . The device as claimed in  claim 25 , in which the means for regulating includes a butterfly valve associated with a precision valve. 
   
   
       27 . The device as claimed in  claim 24 , in which the means for measuring includes systems in which the propagation of the gas stream is evaluated by analyzing transmission spectrum of an infrared radiation at an outlet of the filter, or by infrared thermographic analysis. 
   
   
       28 . Application of the method as claimed in  claim 15 ,
 for controlling particulate filter production methods,   for controlling particulate filter recycling methods,   for studies for design, characterization or development of particulate filters, with regard to selection of materials usable in the filters,   for filter endurance control studies.   
   
   
       29 . Application of the device as claimed in  claim 24 ,
 for controlling particulate filter production methods,   for controlling particulate filter recycling methods,   for studies for design, characterization or development of particulate filters, with regard to selection of materials usable in the filters,   for filter endurance control studies.