Trefoil construction for rotary kilns

A heat exchanger structure for a rotary kiln, said kiln having a cylindrical body on an incline with one end higher than the other and mounted for rotation about the longitudinal axis thereof, said cylindrical body having a steel shell and a refractory brick lining therewithin, said kiln receiving during rotation thereof at the higher end for passage down the incline a charge of materials-to-be-processed and at the lower end heated gases for countercurrent flow against said charge, said heat exchanger structure defined as having a longitudinal axis coaxial with that of said cylindrical body, the x-axis, a plane normal thereto in which lies the upstream face of said trefoil structure having a substantially vertical line therein, the y-axis, intersecting said longitudinal axis, and a substantially horizontal line therein, the z-axis, intersecting said longitudinal axis, said heat exchanger structure comprising, in combination:

• three or more bases formed from radial blocks of castable refractory material equidistantly spaced about and adjustably attached at one surface thereof to the inner surface of said steel shell, each said base extending axially along said steel shell and on the surface opposite the attachment having a profile therein for accepting spoke blocks;
• three or more walls formed from spoke blocks of castable refractory material, each of said walls extending radially from one of said bases and axially along the length of said base to the center portion of the cylindrical body, said spoke blocks having in one side thereof a profile complementary to said radial blocks for mating therewithin and having on the side opposite thereof a profile for accepting additional ones of said spoke blocks, said spoke blocks interlocking in the direction of the x-axis and emplaceable in a lap bond arrangement;
• a hub assembly formed from hub segments of castable refractory material interlocking with the spoke block of the walls and extending axially along the centralmost portion of the walls;
• each said spoke block, when viewing the exterior of said walls, having an offset profile and forming a wall resistant to forces exerted parallel to the x-axis resulting from the flow of said charge during the rotation of the kiln;
• and,
• adjustment means for inserting between said steel shell and said radial blocks, said adjustment means adjusting for said deformations of said steel shell and providing resistance to forces exerted parallel to the y-axis and z-axis resulting from said deformations.

A trefoil structure for a rotary kiln, said kiln having a cylindrical body on an incline with one end higher than the other and mounted for rotation about the longitudinal axis thereof, said cylindrical body having a steel shell and a refractory brick lining therewithin, said kiln receiving at the higher end for passage down the incline a charge of materials-to-be-processed and at the lower end heated gases for countercurrent flow against said charge, said trefoil structure comprising, in combination:

• a plurality of radial blocks of castable refractory material forming three or more bases equidistantly spaced about and adjustably attached at one surface thereof to the inner surface of said steel shell, each said base extending axially along said steel shell and on the surface opposite the attachment having a profile therein for accepting spoke blocks;
• a plurality of spoke blocks of castable refractory material forming three trefoil walls, each of said walls extending radially from one of said bases and axially along the length of said base to the center portion of the cylindrical body, said spoke blocks having in one side thereof a profile complementary to said radial blocks for mating therewithin and having on the side opposite thereof a profile for accepting additional ones of said spoke blocks, said spoke blocks emplaceable in a lap bond arrangement and interlocking in the direction of the longitudinal axis of the kiln;
• a plurality of hub segments of castable refractory material interlocking with one another and with the spoke blocks of the walls to form an interlocked hub extending axially along and joining the centralmost portion of the walls;
• each said spoke block, when viewing the exterior of said walls, having an offset profile and forming a wall resistant to forces exerted parallel to the longitudinal axis resulting from the flow of said charge during the rotation of the kiln;
• adjustment means for inserting between said steel shell and said radial blocks, said adjustment means adjusting for said deflections of said steel shell and resisting forces exerted normal to the longitudinal axis resulting from said deflections;
• and,
• a retaining ring mounted about the interior of the steel shell downstream of the trefoil structure maintaining the positioning of the refractory bricks against forces exerted during kiln operation.