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US 4,483,932 AGranted
Refractory bodies for corrosive environments
AssigneeNorton Company
InventorsMalcolm E. Washburn, Charles W. Taylor
Life of this patent
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AssigneeNorton Company
InventorsMalcolm E. Washburn, Charles W. Taylor
Estimating the term…
The gasification of coal can be accomplished more efficiently if it is operated at a temperature high enough so that the mineral constituents of the coal will form a molten slag which can be continuously removed from the gasifier during operation. Proper control of such a process requires careful temperature control, but the molten coal slag has been found to be corrosive to most thermocouple materials and to conventional refractory ceramics which are used as thermocouple protection tubes in other environments. It has now been found that magnesium chromite serves satisfactorily as a corrosion resistant refractory material in molten coal slags, and that thermocouple protection tubes of this material can be made by isostatic pressing of granular magnesium chromite and subsequent firing.
A hollow refractory body for service in molten coal slag, said body comprising magnesium chromite and chromia to the extent of at least 96% by weight and having a bulk density of at least 3.5 gm/cm.sup.3, a sufficient wall thickness so that the permeation of water through said wall is not greater than 2.0 cm.sup.3 of water per cm.sup.2 of area of wall surface per hour, a mean pore diameter not greater than 9 microns, and an upper bound of not more than 20 microns on the diameter of an individual pore among the group of smallest diameter pores which together aggregate to at least 90% of the total pore volume.
Dependencies are inferred from the claim text.