Method and device for sensing a clearance
AssigneeABB Air Preheater, Inc.
InventorsKurt Karlsson, Stig Lundin
Life of this patent
Estimating the term…
Abstract
A method and an arrangement for sensing the clearance between an object and an object-adjacent surface, which is particularly for use in difficult ambient conditions, such as in dirty, corrosive environments and under varying temperature and pressure conditions, e.g. to measure and hold constant the clearance between the sector plates (3, 4) of a regenerative rotary air preheater and the end surfaces of the rotor (2, 8). The sensing device (7) includes a compressed-air operated pipe (9) which is mounted on the object (3, 4) and which includes a sound-emitting opening (14) located adjacent the surface (8), wherein changes in the distance (S) between the object (3, 4) and the surface (8) are represented by changes that occur in the resonant frequency of the pipe (9).
Claims7
A method of sensing a clearance between an object and an object-adjacent surface, and of generating a signal which is representative of a magnitude of said clearance and which is used to control a setting device that is operated to adjust the magnitude of said clearance to a desired magnitude, the method comprising:
- providing the object with at least one compressed-air operated pipe that includes a resonance tube that is tuned to a specific frequency and that includes an opening which is adapted to be placed adjacent to said object-adjacent surface such that a resonance frequency of the at least one pipe changes in accordance with the magnitude of the clearance;
- and
- identifying and utilizing said resonance frequency to control the setting device to adjust the magnitude of said clearance to the desired magnitude.
Dependencies are inferred from the claim text.