Insulated furnace door system

An energy efficient entry door system for admitting elongate articles to a heating chamber of an industrial furnace wherein a temperature that is very substantially above that of ambient air is maintained, with the entry door system serving to open and close at least a selected portion of a substantially horizontally extending entry opening that communicates from outside of the furnace chamber to inside the furnace chamber, comprising:

• a) first support means including first support structure extending substantially horizontally at a location near the outside the entry opening along such upper structure as defines the top of a portion of an entry opening portion is to be opened and closed by the entry door system;
• b) door component means including a plurality of door components i) for being pivotally connected to the first support means and ii) for depending substantially vertically therefrom in a manner that causes the door components to normally be biased by gravity toward a closed position of engagement with such lower structure as defines the bottom of said portion of the entry opening;
• c) connection means i) for establishing a pivotal connection between the door component means and the first support means to enable the door component means to pivot about a substantially horizontal axis that extends substantially parallel to the support means at a location that is outside the entry opening, ii) for positioning said plurality of door components so as to extend in a substantially contiguous, side-by-side array that bridges the horizontal length of said portion of the entry opening, and iii) for enabling the door components to pivot independently between their "closed" positions and "open" positions that enable an elongate article to move along a path of travel that extends from outside the entry opening through the bottom of said portion of the entry opening and into a furnace chamber that is located inside the entry opening;
• d) wherein each of the door components has a rigid backing member that includes i) upper end region means for defining an upper end region that is connected by the connection means to said first support means, ii) lower end region means for defining a lower end region that engages said lower structure when the door component is closed, and iii) central region means for defining an inwardly curved, outwardly convex central region that extends progressively inwardly as it extends from its connection with the upper end region to its connection with the lower end region, with said lower end region means being configured to cause the lower end region to be positioned relatively inwardly with respect to the entry opening at all times regardless of whether the door component is "closed" or "open," with said upper end region means being configured to cause the upper end region to be positioned relatively outwardly with respect to the entry opening at all times regardless of whether the door component is "closed" or "open," and with said central region means being configured so that the central region defines outwardly facing engagement surface means that extends at least partially through the furnace entry opening for being engaged by an elongate article that is being moved through the entry opening, with said engagement surface being inclined inwardly as it extends at least partially through the furnace entry opening so that as the elongate article is moved through the entry opening, the engagement of the elongate article with the engagement surface causes the door component to pivot open and to remain open only to the extent needed to permit passage through the entry opening of the elongate article;
• e) first insulation means including a backing of insulation that extends along inwardly facing surface portions of the rigid backing member;
• f) second support means including second support structure extending substantially horizontally beneath such upper structure as defines the top of the entry opening;
• and,
• g) second insulation means including a curtain of insulation suspended from said second support means for depending alongside inner portions of the door components.

An energy efficient closure for minimizing heat loss through an elongate, horizontally extending furnace entry opening that is utilized to admit elongate charges of material including steel slabs, billets and blooms, to the interior of a furnace, such as a reheat furnace, comprising:

• a) door means including a plurality of depending, individually mounted, independently pivoted, inwardly curved, insulated door components arranged in a side-by-side array for selectively closing the furnace entry opening with each of the door components having upper end region means for remaining relatively outwardly with respect to the furnace entry opening so as to extend closely alongside such furnace structure as defines the top side of the furnace entry opening, having lower end region means for remaining relatively inwardly with respect to the furnace entry opening so as to be engageable with such furnace structure as extends along a bottom side of the furnace entry opening, and having inwardly curved central region means for extending between and connecting said upper end region means and said lower end region means, and for defining inwardly curved engagement surface means that extends at least partially through the furnace entry opening for being engaged by elongate charges of material that pass through the furnace entry opening, with the door components each being configured to be biased by gravity toward a normally closed position wherein the lower end region means engages such furnace structure as extends along the bottom side of the furnace entry opening to close the furnace opening, and with said engagement of elongate charges of material with the door components causing engaged ones of the door components to be pivoted away from their normally closed positions but only to the extent that is needed to permit passage through the furnace entry opening of the elongate charges of material;
• and,
• b) auxiliary insulation means for defining a curtain of insulation that depends from a water-cooled support that extends horizontally beneath and along such furnace structure as defines the top side of the furnace entry opening, with the curtain being formed by a plurality of depending bats of insulation that are arranged in a substantially contiguous side-by-side array.

A door component for being utilized together with other substantially identical door components to selectively open and close at least a portion of a horizontally extending entry opening of a steel reheat furnace, through which entry opening elongate charges of material are admitted to the interior of the reheat furnace, wherein the door component comprises:

• a) curved backing means formed from nodular cast iron:
• i) for defining an upper end region that is adapted for pivotal connection to a suitable support that extends horizontally along such upper furnace structure as defines the top of the furnace entry opening, with the location of said pivotal connection causing the upper end region of the curved backing means to be positioned and to remain positioned relatively outwardly with respect to the furnace entry opening;
• ii) for defining a lower end region for engaging such lower furnace structure as extends along the bottom of the furnace entry opening;
• and,
• iii) for defining an elongate, curved central region that connects smoothly with the upper end region at one end thereof, and that connects smoothly with the lower end region at the opposite end region thereof, with the curved backing means having concave inner surface means for facing toward the interior of the steel reheat furnace, and convex outer surface means for extending at least partially through the furnace entry opening and for being engaged by elongate charges of material during their passage through the furnace entry opening so that the door component will be "opened" only to the extent that is needed to permit such charges of material to pass through the furnace entry opening to be admitted to the interior of the reheat furnace;
• b) insulation means for extending along at least a substantial portion of said concave inner surface and including at least one bat of flexible, fiber blanket refractory insulation material;
• and,
• c) insulation mounting means for connecting said insulation means to the curved backing means.