DISTANCE MEASUREMENT IN FURNACES

摘要

Apparatus for determining, in a furnace (10) having a pipe (14) along which a hot gas is transmitted to a point of introduction (15) into the furnace, the distance between the point of introduction and the surface (19, 19a) spaced therefrom, includes means (22, 24, 26) including a protective jacket (24) for transmitting a light signal along the pipe (14) within the jacket and thence from the pipe towards the surface. This means is further adapted to receive a light signal at the pipe which includes a reflection of the transmitted signal from the surface and to direct the received signal back along the pipe within the jacket (24). Means (30, 34, 36) is provided to determine the distance between the point of introduction of the gas and the surface by analysing the received signal relative to the transmitted signal. A preferred apparatus uses a laser (32), an optical fibre (22) and time-of-flight ranging.