Abstract: An induction galvanneal strip furnace utilizes a plurality of radiation (infrared or optical) pyrometers which measure strip temperature and provide a feedback signal which is compared with a set point or reference temperature signal from a set point generator to produce an error signal proportional to the measured variable minus the set point or reference temperature. The error signal is processed by use of a conventional proportions integrator derivative algorithm to produce a control signal which controls the electrical energy supplied to the induction coils. Each of the radiation pyrometers is positioned at the emergence or downstream side of the downstream most induction coil of a set of induction coils that it controls to thereby provide rapid, accurate control of strip temperature and with a more efficient utilization of electrical energy and high quality in the finished product.

Abstract: A high temperature refractory brick wall is repaired by removing and replacing damaged brick while the wall is maintained at a temperature below normal operating temperature but sufficiently high to avoid damage from contraction resulting from cooling. New brick having a coefficient of thermal expansion compatible with the heated wall are used to avoid cracking of the wall due to expansion during heat-up. Workers wearing protective clothing, preferably incorporating a circulating fluid cooling system, remove the damaged brick and install new brick in their place in walls having surface temperatures of about 500.degree. F. or higher and internal temperatures substantially above 500.degree. F., preferably at least about 1500.degree. F.

Abstract: A pit cover for retaining heat in an open top, ring-shaped, carbon anode baking furnace comprises an insulating cement cast into the form of the cover, at least one metal beam embedded in the insulating cement, and a plurality of stainless steel needles interspersed substantially throughout the insulating cement for reinforcement purposes. The insulating cement has a K factor of approximately 2 to 4, a density of approximately 80 to 100 lb./ft..sup.3, a cold crushing strength in the range of 1,000 to 5,000 psi, and a low iron content, preferably, less than 2%.

Abstract: This invention relates to a device for cleaning opposed walls of a furnace pit. The device comprises a plurality of rotating screw-type cutters for removing built-up deposits upon the opposed walls of the furnace pit, a plurality of linkage arms for carrying the plurality of rotating screw-type cutters, a plurality of air motors for independently adjusting the speed of each half of the plurality of rotating screw-type cutters along each opposed wall of the furnace pit, and universal joints for allowing floating adjustment of each of the plurality of rotating screw-type cutters against each opposed wall of the furnace pit.