US3593970A

US3593970A - Monolithic plastic nosering

Info

Publication number: US3593970A
Application number: US836373A
Authority: US
Inventors: John Williams Seebald
Original assignee: General Refractories Co
Current assignee: General Refractories Co
Priority date: 1969-06-25
Filing date: 1969-06-25
Publication date: 1971-07-20
Anticipated expiration: 1988-07-20

Abstract

A refractory lining wall for a rotary kiln made of conventional firebrick which terminates adjacent the nosering or discharge end of a the kiln forming a trough into which a plastic refractory is rammed which, when subjected to setting conditions, develops a strong ceramic bond and also bonds against the brick, thus providing a nonjointed monolithic nosering having high resistance to mechanical and thermal spalling.

Description

United States I Patent [72] Inventor John Williams Seebald Cranbury, NJ. [2|] Appl No 836,373 [22] Filed June 25, I969 [45] Patented July 20, 1971 [73] Assignee General Refractories Company Philadelphia, Pa.

[54] MONOLITHIC PLASTIC NOSERING 12 Claims, 4 Drawing Figs.

263/46, 264/30 [51] Int. Cl. F27b 7/00 [50] Field of Search 264/30; 263/32, 33,'46

[S6] References Cited UNITED STATES PATENTS 2,089,026 8/ 1937 Hoffman 263/33 2,169,512 8Il939 Borch 263/33 2,266,396 12/1941 Lincoln et al. 263/32 3,270,097 8/1966 Pavlica 264/30 Primary Examiner-John .l Camby Attorneys-Everett H. Murray. Jr. and McClure, Weiser &

Millnjan ABSTRACT: A refractory lining wall for a rotary kiln made of conventional firebrick which terminates adjacent the nosering or discharge end of a the kiln forming a trough into which a plastic refractory is rammed which, when subjected to setting conditions, develops a strong ceramic bond and also bonds against the brick, thus providing anonjointed monolithic nosering having high resistance to mechanical and thermal spalling.

This invention relates to a refractory lining for a rotary kiln such as those used in the cement industries, for firing refractories, and the like.

Heretofore rotary kilns were lined over their entire length including the nosering at the discharge end with conventional firebricks made of refractories such as fire clay, high aluminasilica, chemically bonded and burned magnesite and the like or of castables, mixtures of ground and sized aggregates containing either hydraulic-setting or air-setting cements. Since the nosering at the discharge endof the kiln is a high-temperature zone it is especially vulnerable and when constructed of the aforementioned conventional firebricks, it frequently exhibits thermaland mechanical spalling.

The prior arthas recognized these problems and has at tempted to provide certain improvements. See, for instance, US. Pat. Nos. 2,169,512; 2,196,445; and 2,321,217. The present invention makes a significant contribution to overcoming the problems of the prior art.

' The primary object of the invention is to provide a refractory lining for a rotary kiln which minimizes thermal spalling or breakage of the nosering at the discharge end thereof.

Another object of the invention is to provide a composite lining for a rotary kiln wherein all but the nose portion at the discharge end comprises a conventional firebrick, whereas the nose portion is a nonjointed or unitary monolithic ring formed of a plastic refractory.

. 2 wardly extending edge 22 forming with surface 24 of the metal shell which is unlined with bricks, a trough 26 which extends from the annular edge 22 of the brick to the discharge end Another object of the invention is to provide a composite rotary kiln lining of the character above described wherein the plastic forming the nonjointed monolithic nosering is such that it develops a strong bond at relatively low temperatures in the order of magnitude of 200300 F.

A further object of the invention is to provide a composite rotary kiln lining comprising conventional firebrick and a monolithic plastic retractory confined to thedischarge end or nosering of the kiln. The rotary kiln plastic nosering is readily and economically installed by ramming the plastic into the trough formed between the edge of the last brick ring and the metal shell of the kiln, and while retaining the plastic in place subjecting it to setting conditions whereupon it develops an internal bond of high strength and bonds as well against the brick ring.

These and other objects of the invention will become more apparent as the following description proceeds in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a conventional rotary kiln;

FlG. 2 is an enlarged axial fragmentary sectional view of the discharge end of the kiln prior to installation of the plastic monolithic nosering shown with a molding rim applied thereto;

FIG. 3 is a view similar to FIG. 2 illustrating the completed lining with the plastic monolithic nosering fomied therein; and

FIG. 4 is a sectional view taken on the line 44 of FIG. 3.

Specific reference is now made to the drawings in which similar reference characters are used for corresponding elements throughout.

indicated generally at 10 is a conventional rotary kiln such as that used in the cement industry which is essentially a cylindrical metallic shell 12, the interior of which is lined with a suitable refractory. In the instant case the lining is a composite. Affixed to the shell interiorly thereof in a conventional manner are conventional preformed fired bricks 14 made of such refractory materials as fire clay, high alumina-silica,

chemically bonded and burned magnesite or castables, mix

tures of ground and sized aggregates containing either hydraulic-setting or air-setting cement. The blocks can be mortared as at 16. a

The inner surface of the shell is lined with bricks 14 up to a predetermined distance, generally 6 to 9 inches or more up to 2 to 3 feet from edge 18 of the discharge end 20 of the kiln. Thus the last ring of bricks l4 terminates in an annular inedge 18. Normally the brick lining terminates at a conventional metal brick-retaining ring 27 which is welded circumferentially on the shell 12.

Affixed to surface 24 of the shell and extending radially into trough 26 are circumferentially spaced 'V anchor clips 28 made of high-temperature resistant metal, such as stainless steel, chrome-nickel alloy and the like. lnstead of metallic V- clips, studs, bolts and refractory anchor members may be used although the V-clips are preferred.

7 Press-fit upon or otherwise secured-to shell 12 around the edgel8 is a ringlike molding rim 30 having a cylindrical flange 32 which engages the outside surface of the shell and an inwardly extending substantially flat flange 34, preferably at right angles thereto, thus forming a retaining lip covering the edge 18 of the shell. With the rim in place trough 26takes the form of an annular cavity of channel cross section.

A plastic refractory 36 is then placed into the trough preferably by ramming with conventional pneumatic equipment against metal surface 24 and between the lip of flange 34 and edge 22 of the last ring of bricks whose inner surface 38 is made substantially flush with inner surface 40 of bricks 14. When the plastic refractory 36 is subjected to the conditions required for setting the plastic composition chosen, the plastic refractory 36sets forming a strong internal ceramic bond. In the setting process, the plastic refractory 36 also bonds against 42 to edge 22 of the bricks thus fonning a secure nonjointed monolithic nosering at the discharge end of the kiln.

As stated hereinbefore, the nonjointed monolithic nosering is made of plastic refractories which are well known in the art and generally comprise mixtures of calcined clays or ores blended with plastic clays and mixed with water to a proper consistency, the calcining acting to stabilize the refractory aggregates while the plastic clays act to form a strong ceramic bond when subjected to setting conditions. When these contain less raw clay they have a lesser degree of plasticity and are known as ramming mixes." it is to be understood that the term "plastic refractories used herein includes ramming mixes. See Chemical Engineering, July 31, 1967, pp. -104, article entitled A Guide To Selecting Modern Refractories by Burst and Spieckennan which is herein incorporated by reference.

Many different grades of plastics may be employed such as those made and sold by General Refractories Company of Philadelphia, Pa; under the trademark Brikram. For example, Brikram is a fire clay base plastic refractory which can be used where temperatures range from 1,800 to 2,900 F. Brikram Mix 8 has an additive that develops strength at room temperature and is air setting. Super Brikram mix has a high fusion point and can be used in furnaces operating at 3,000 F. or higher. Other grades of Brikram mixes have an alumina content of 55, 60, 70, 80 and percent for increased refractoriness. Chrome-base plastic refractory mixes may also be used.

The preferred plastics are those which are chemically bonded and develop adequate strength at 200-300 F., to be mechanically self-sustaining, particularly those of high alumina content, i.e., 50 percent or more by weight. Examples of these are Brikram 80 P-461 which contains 80 percent alumina and phosphoric acid as the bonding agent, which develops some strength at 200--300 F. and full strength at less than 1,000" F. and is abrasion and erosion resistant; and Brikram 90 FA which also contains phosphoric acid as the bonding agent but has a very high alumina content of 90 percent and hence develops a strong bond at 200-300 F. and has a service limit of 3,250 F. and has excellent resistance to spalling and abrasion.

While preferred embodiments of the invention have been shown and described herein, a skilled artisan may make minor variations without departing from the spirit of the invention.

Iclaim:

1. in a rotary kiln having a metallic casing wall with a discharge end, a refractory liner therefor comprising refractory bricks lining said casing wall and terminating in an end wall adjacent to but spaced inwardly from said discharge end of said casing wall thereby providing a trough beyond said end wall up to said discharge end, and a plastic nonjointed monolithic refractory filling said trough and bonded against said bricks at said end wall, thus forming a nosering resistant to mechanical and thermal spalling.

2. The combination of claim 1 and anchor means afiiited to the casing wall and embedded in said nonjointed monolithic nosering.

3. The combination of claim 1 wherein said plastic refractory ring is a heat-set, high alumina, chemically bonded composition which has become of self-sustaining strength at about 200300 F.

4. The combination of claim 3 wherein the alumina content is 80 percent90 percent and the bonding agent is phosphoric acid.

5. In a rotary kiln having a metallic casing wall with a discharge end, a refractory liner therefor comprising refractory bricks lining said casing wall and terminating in an end wall adjacent to but spaced inwardly from said discharge end of said casing wall thereby providing a trough beyond said end wall up to said discharge end, a plastic, nonjointed, set monolithic refractory filling said trough and bonded to said bricks at said end wall thus forming a nosering resistant to mechanical and thermal spalling.

6. The ring of claim 5 in which the ring is a phosphoric acid bonded plastic of an alumina content of at least 50 percent.

7. ln arotary kiln having a metallic casing wall with a discharge end, a refractory liner therefor comprising refractory prefired bricks lining said casing wall and terminating in an monolithic nosering bonded to bricks at said tion which starts developing strength at 200-300 F.

9. A process of manufacturing of a plastic, nonjointed monolithic refractory nosering in a refractory liner for a rotary kiln which comprises: Y

lining the interior of a rotary kiln with a refractory material, terminating said lining in an annular inwardly extending edge forming with a metal shell a trough which extends from the annular edge to the discharge end of the kiln,

filling said trough formed between the edge of the last brick ring and the metal shell of the kiln with a plastic refractory,

subjecting said plastic to setting conditions, whereupon it develops an internal bond of high strength and bonds to the brick ring and thereby forms an annular plastic refractory unitary monolithic nosering resistant to mechanical and thermal spalling.

10. The rotary kiln of claim 1 wherein the trough is completely filled with the plastic monolithic refractory filling.

11. The rotary kiln of claim 5 wherein the trough is completely filled with the plastic monolithic refractory filling.

12. The process of claim 9 wherein the plastic refractory completely fills the trough.

Claims

2. The combination of claim 1 and anchor means affixed to the casing wall and embedded in said nonjointed monolithic nosering.

3. The combination of claim 1 wherein said plastic refractory ring is a heat-set, high alumina, chemically bonded composition which has become of self-sustaining strength at about 200*-300* F.

4. The combination of claim 3 wherein the alumina content is 80 percent-90 percent and the bonding agent is phosphoric acid.

7. In a rotary kiln having a metallic casing wall with a discharge end, a refractory liner therefor comprising refractory prefired bricks lining said casing wall and terminating in an end wall adjacent to but spaced inwardly from said discharge end of said casing wall thereby providing a trough beyond said end wall up to said discharge end, and an unset plastic refractory unitarily filling said trough so that when it is subjected to setting conditions it forms a nonjointed spalling-resistant monolithic nosering bonded to bricks at said terminating end wall.

8. The combination of claim 5 wherein said plastic refractory is a heat-setting, high alumina, phosphate bonded composition which starts developing strength at 200*-300* F.

9. A process of manufacturing of a plastic, nonjointed monolithic refractory nosering in a refractory liner for a rotary kiln which comprises: lining the interior of a rotary kiln with a refractory material, terminating said lining in an annular inwardly extending edge forming with a metal shell a trough which extends from the annular edge to the discharge end of the kiln, filling said trough formed between the edge of the last brick ring and the metal shell of the kiln with a plastic refractory, subjecting said plastic to setting conditions, whereupon it develops an internal bond of high strength and bonds to the brick ring and thereby forms an annular plastic refractory unitary monolithic nosering resistant to mechanical and thermal spalling.