US1846614A - Tunnel kiln car and refractory slab therefor - Google Patents

Description

Fb. 23, 1932. R. w. ROWLAND ,614

TUNNEL KILN CAR AND REFRACTORY SLAB THEREFOR V Fi ledJune 12, 1931 INVEN TOR. RoezRl t/ Rama AND BY Y W a /ATTORNEY Patented Feb. 23, 1932 UNITED" STATES PATENT OFFICE ROGER W. ROWLAND, OF NEW CASTLE, PENNSYLVANIA, ASSIGNOR TO NEWCASTLE RE- FRACTORIES COMPANY, OF NEW CASTLE, DELAWARE, CORPORATION OF DELA- WARE TUNNEL KILN CAR AND REFRACTORY SLAB THEREFOR Application filed. June 12,

to withstand high temperatures and to possess considerable mechanical strength. Heretofore the superstructure platforms have been composed by a plurality of flat refrac tory slabs of general rectangular contour longitudinally and transversely and with adjacent slabs arranged end-to end or sideby-side and the supporting posts positioned at the corners thereof. The slabs and posts are usually made of fire clay or other highly siliceous material.

When cars of the above type are loaded with goods to be treated and passed through a tunnel kiln of standard design, the superstructure and goods are usually progressively heated to a high temperature and then cooled. Duringthe passage of the car through the heating section or sections of the kiln, the material forming and adjacent to the exposed surface portions of the slabs will receive more heat than the material in the center portions thereof. The resulting difference in the rates of expansion of these portions of the slabs causes the latter to be subjected to internal stresses, which, when coupled with heavy load stresses, frequently results in'cracking or a rupture of the'slab and in many cases breakage of the goods supported thereon. During the passage of the car'through the cooling section of the kiln, the material forming and adjacent to the exposed surface portions of the slabs gives up heat at a greater rate than the material'in the center portions thereof with a resulting difference in the rates of contraction of these portions. Contraction stresses consequently occur, which also tend towards a rupture of the slab structure.

The main object of my present invention is the provision of a kiln car platform slab which is light in weight, low in cost, and in which all portions of the slab structure will 1931. Serial No. 543,823.

be subjected in use to substantially uniform heating and cooling effects.

In carrying out my invention I form each kiln carplatform'slab with one or more internal passages extending throughout the slab. When more than one passage is formed in each slab, all of the passages, may extend in the same direction, or one or more may be arranged normal to the remaining. In assembling the slabs, I preferably arrange them on the car so that the slab passages will all extend in the same direction as the general path of the kiln chamber atmosphere, whereby the amount of the kiln chamber gases passing through the slab passages will be increased. The amount of material in the slabs is thus reduced as well as the cost of production and the weight thereof. Any reduction in weight of the superstructure elements will facilitatetheir handling and also decrease the amount of fuel consumed in fielating these non-productive parts in the The various features 7 of novelty which characterize myinvention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, and the advantages possessed by it reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described pre ferred embodiments of the invention.

Of the drawings:

Fig. 1 is an end elevation of a kiln car having a goods supporting superstructure embodying my invention;

Fig. 2 is aside elevation of the car shown in Fig. 1; and

Fig. 3 is a perspective view of a modified slab construction.

In the drawings, I have illustrated a car especially suitable for use in moving ceramic goods through a tunnel kiln of the mufie type in the direction indicated. The car as shown, comprises a body portion A which is formed in the usual manner by superposed rows of refractory blocks A arranged on a metallic frame A which is provided at its underside with wheels A for engaging tracks 13 arranged in the bottom of the kiln chamber. A series of longitudinally spaced transversely extending refractory girders C are arranged on the upper row of blocks A and provide transverse circulation chambers C through the car. The girders C serve as supports for the goods carrying superstructure of the car.

The car superstructure as shown consists of a lower platform D, an intermediate platform D and an upper platform D all of which are formed by a plurality of fiat refractory slabs D as hereinafter described and are used for supportin ceramic goods requiring treatment, as indicated in Fig. 1. The slabs D assembled to form the various platforms are preferably made of rectangular longitudinal and transverse cross-section. The assembled slabs are positioned with their vertical edge portions substantially in contact. The adjacent transversely extending edge portions of each pair of adjacent slabs in the platform D are preferably mounted on corresponding girders C. The slabs forn'r ing the intermediate and upper platforms D and D respectively, are mounted on the lower platform D by posts E positioned at various spaced points thereon, preferably at the corners of the slabs.

l/Vhen the car illustrated is employed in a downdraft mullle kiln, for example, the portions of the slabs of each platform along the longitudinal center line of the car are usually cut away or recessed to permit a downflow circulation through the car and into the transverse channels C, as indicated by the arrows in Fig. 1. In kilns of this type, the kiln chamber atmosphere is circulated through the channels G into contact with the walls of combustion chambers (not shown) extending longitudinally at the sides of the kiln chamber.

When in use in a downdraft mufl'le kiln, the upper portion of the car superstructure is usually heated to a slightly higher temperature than the lower central portion thereof. lVhen the platform slabs are made solid, as has been heretofore the case, the material forming and adjacent to the exposed surfaces of the slabs will receive a greater amount of heat than the material nearer to the centers of the slabs, while the car is passed through the heating sections of the kiln. A corresponding difference in the rates of expansion of these portions of each slab consequently occurs and invariably causes stresses to be set up in the slab which, if sufiiciently great, will cause a rupture in the slab structure. lVith solid slabs arranged as described, these stresses are greatest in the portion of the slabs on which the goods are positioned. The presence of heavy loads coupled with expansion strains usually results in the forn'iation of cracks in the slab structure and not infrequently in a rupture of the slab while in the kiln, damage to goods on the car, and possibly interference with the car movements. During the passage of the cars through the cooling section of the kiln, contraction strains will occure in each slab due to the differences in the rates at which the different portions give off heat, with results similar to those just described. In general, the slabs in the plat forms D, D D increase in the order named in their liability to damage from the above causes.

In accordance with my present invention, each of the slabs having a liability for rupturing because of differences in the rates of expansion or contraction of different portions thereof is formed with one or more horizontal passages D which extend through the portion of the slab which has heretofore had the lowest rate of expansion or contraction. lVith slabs of the shape illustrated, the pas- D are of considerably greater width than depth and preferably symmetrically ar-- ranged re ative to one of the center lines thereof. \Vhen the slabs are arranged as shown in a kiln in which the circulation of the kiln chamber atmosphere is transverse to the kiln length. the passages D are advantageously formed and/or arranged in the slabs so as to extend transversely of the car and parallel to the channel C. main circulation is longitudinally of the kiln chamber, as in a direct fire kiln, a longitudinal positioning of the passage D is preferable. VVhen so arranged in parallel with the path of flow of the heating gases, a great er amount of the circulating kiln atmosphere will pass through the passages in both the heating and cooling sections of the kiln.

In the slab construction shown 1n Figs. 1

and 2, two passages D are formed in each slab and symmetrically arranged at opposite sides of the center line and parallel to the transverse side edges thereof. When two ich slabs are used for the width of the car, their respective passages will be in alignment. In the slab shown in Fig. 3, only one passage D is shown extending through the longer horizontal portion thereof, while two similar passages D are symmetrically arranged normal to and intersecting the passage D. The proportioninp" of the slabs depends largely upon the size of the kiln car on which they are to be used, while the arrangement of the slab passages depends primarily on the operating conditions to which they are to be subjected. The slabs may be so formed by a suitable casting, pressing, ramming or extruding operation and thereafter fired.

lVhen in use, the slab passages will generally have a circulation therethrough sulficient in amount to cause the material in the portions of the slab surrounding the passages to be always subjected to substantially the same temperature conditions as the ma terial forming and adjacent to the exposed When the surfaces thereof. All portions of the slabs will then have substantially the same rates of expansion and contraction with a consequent elimination of internal strains in the slab structure.

lhe described slab formation is also advantageous in reducing the amount of ma terial used in making the slabs with a consequent reduction in the cost of production and weight of the slabs. Any decrease in slab weight advantageously increases the ratio of the weight of goods being treated to the weight of the unproductive superstructure elements and thereby lowers the amount of fuel consumed in heat-ing these elements. The decrease in weight also facilitates the handling of the slabs when such operations are necessary in loading or unloading the goods.

Vlhile in accordance with the provisions of the statutes, I have illustrated and described the best forms of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the forms of the constructions disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases only the slabs in the upper platform need be made in the manner described.

Having now described my invention, wha I claim as new and desire to'secure by Letters Patent, is: I

1. A kiln car having a goods supporting superstructure comprising a plurality of vertically spaced goods supporting platforms, each formed by a horizontally arranged goods supporting refractory slab structure, one of said slab structures having a horizontal passage extending therethrough and arranged parallel to the direction of circulation of the kiln chamber atmosphere.

2. A kiln car having a goods supporting superstructure comprising a plurality of vertically spaced goods supporting platforms, each formed by a plurality of horizontally arranged goods supporting refractory slabs of oblong cross-section supported on posts, some of said slabs having one or more shallow horizontal passages of substantial width opening to opposite sides thereof and arranged for the passage therethrough of the kiln chamber atmosphere.

3. A mufiie kiln car having a goods supporting superstructure comprising a plurality of vertically spaced goods supporting platforms, each formed by a plurality of horizontally arranged flat goods supporting refractory slabs, said platform slabs having horizontal passages extending transversely of said car to permit the circulation therethrough of the kilnchamber atmosphere.

4. A kiln car goods supporting platform slab of rectangular cross-section and formed of refractory material, and having a hori- 63A kiln car goods supporting platformslab or rectangular form and made of refractory material, and having a plurality of horizontal passages formed therein and opening at opposite edge portions thereof, two of said passages being arranged normal to one another and intersecting.

Signed at New Castle, in the count-y of Lawrence and State of Pennsylvania, this 2nd day of June, A. D. 1931.

i V ROGER W. ROVLAND.

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