Abstract: An instrument assembly is mounted to view the inside of a furnace or boiler, its probe extending into a port in the furnace wall. To remove slag built up within the port, a deslagger unit is mounted upon the assembly and includes a shiftable blade surrounding the probe lens. A displacing mechanism mounted upon the assembly is periodically actuated to rectilinearly shift the blade within the confines of the port to dislodge built up slag therein.

Abstract: Infrared emitting surfaces such as a smelt bed in a Kraftchemical recovery boiler can be monitored by a closed circuit infrared camera equipped with a 1.5 micrometer edge filter. The camera power supply is isolated from the heat sensitive camera pick up tube and yoke assembly. This separation also makes it easier to mount and dismount the tube on and off of the boiler. The tube is contained in a housing which is supported by bearings which are slidable on rods attached to the boiler wall. This attachment ensures that the image produced will not change with mounting and dismounting the camera. An image change would result in a waste of smelt bed chemicals.