Correction-free pyrometry in radiant wall furnaces

US5316385A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventor

• Andrew Thomas · Houston, US

Key dates

• Filing date: Mar 30, 1993
• Grant date: May 31, 1994
• Expiry date: Mar 30, 2013

Classification

• Technology area (CPC G): Physics
• CPC primary: G01J5/0875
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and apparatus to produce correction-free pyrometry is described. The method determines the optimum position for a pyrometer that "views" a specular, spherical or near-spherical target in a furnace through pyrometer optics and a window in a wall of the furnace. The positioning method uses nonparaxial optical analysis to determine the position of an image of the window in the target. The window image is free of any image of the furnace walls, that is, it is free from wall radiance, and pure target radiance can be obtained in that region. The optical analysis is then used to back project the pyrometer detector through the pyrometer optics and onto the surface of the target. If the detector projection falls completely within the image of the window, the detector will read only pure target radiance and no correction will be necessary to obtain the temperature of the target through pyrometry.