US1647083A - Furnace lining - Google Patents

Description

A. G. CROLL FURNACE LINING Filed July 5, 1923 Oct. 25, 1927,

INVENTOR v f' ATTORNEY;

Patented Oct. 25, 1927.

UNITED STATES PATENT OFFICE.

ANDREW G. CBOIIIJL, F WEATHERLY, PENNSYLVANIA, ASSIGNOR TO THE ATLAS PORTLAND CEMENT COMPANY, A CORPORATION OF PENNSYLVANIA.

FURNACE LINING.

Application filed .1u1y 5, 1923. Serial No. 649,533.

My invention relates to linings for apparatus in which materials are subjected to a high degree of heat, such for example as the rotary kiln used in the making of cement,

5 blast furnaces, etc. The object of my invention is to provide a lining for such apparatus which will be capable of absorbing and radiating heat to the materials being treated and at the same time act as an insulator for heat between the radiating surface or surfaces and the outer wall or shell of the apparatus. I will describe a lining embodying my invention and then point out the novel features in claims. In the accompanying drawing, Fig. 1 is a view, partly in elevation and partly in longitudinal section, showing a rotary cement kiln provided with one form of lining embodying my invention. Fig. 2 is a transverse sectional view on the line IIII of Fig. 1.

Fig. 3 is a detail view showing in side elevation and on an enlarged scale one of the blocks comprised in the lining shown in Figs. 1 and 2. Fig. 4 is an end view, and Fig. 5 a top view, of the block shown in Fig. 3.

Similar reference characters designate similar parts in each of the several views.

Heretofore it has been the customary practice, in apparatus in which a high degree of 0 heat is employed, to line the kiln or other container with fire brick, which, among its other characteristics, acts as a non-conductor of heat. In such apparatus economy can be effected if the lining can radiate heat to the material coming in contact with it, and at the same time serve as aheat insulator between the radiating surface and'the outer wall or shell of the container. One feature of my invention is the provision of a lining 40 having these two characteristics.

In .the accompanying drawing I have shown my invention applied to a rotary kiln, such as is commonly used in making Portland cement. The reference character A 4 designates the usual steel shell or wall of the kiln, which shell is mounted on rollers 2 and is rotated through the medium of gear wheels 5 driven by mechanism which is not shown in the drawing. One end of the shell terminates in a housing 3 from which the raw material is fed to the kiln, while the other or delivery end terminates in a housing 4 which receives the treated material from the kiln, and from which hot gases are supplied to the kiln. The burning zone of the shell, that is, the zone between the housing t and a point 6, is lined with fire-brick 7 of any suitable kind capable of withstanding the high temperature to which this zone is subjected. At the point 6 the shell may be lined with a single row 8 of fire-brick similar to that in the burning zone, except that it 1s deeper, as indicated in the drawing.

From point 6 to the feed end 3, that is, in the calcining zone, the shell A is provided with a lining B which, as here shown, comprises units or blocks b. In the articular embodiment of my invention i lustrated herein these blocks are spaced from the inner surface of the shell A by an auxiliary lining C made upof a suitable heat insulating brick.

Each unit or block b, as illustrated in Figs. 3, 4 and 5, is substantially rectangular in shape, and these blocks are laid against the lining C with the long dimension extending around the circumference of the shell. The inner and outer surfaces of the blocks are accordingly curved to conform with the curvature of the shell. The face or side of the block nearest to the shell A is preferably provided with a recess 9, thus leaving a flange 10 around the main or body portion of the entire block in order to reduce the weight of the block. This flange is of rigid heat-insulating substance, and may advantageously be made of one art cement and three parts fine clinker, t e clinker being soaked in water for approximately twelve hours before mixing with the cement. The opposite face of the block is made of a heatresisting and insulating substance, combined with a heat-conducting substance, which substances may be, as examples, cement and iron borings. Preferably the proportions of these substances are varied in such manner that the percentage of iron increases progressively from the flanged surface of the block to the inner" surface 11, the percentage of cement decreasing accordin ly. For example the face 11 of the bIock may be divided into four layers 6 b, b, and b,

and the proportions of iron and cement in these layers may be substantially in accordance with the following table:

Parts by volume Layer h borings Cement b l 3 3 b I 3 2 b B 3 1%: b t 3 i It will thus be seen that the portions of the block near the inner surface .11 are better conductors, and hence radiators, of heat than n the portions near the flan es 10, and that the degree of conductivity ecreases by stages from the former surface to the'latter.

The blocks 6 are attached to each other and to the auxiliary lining C by a suitable mortar which may consist, for example, of three parts fire clay and one part cement mixed with water to bring it to the consistenoy'of a rather stifi paste. The blocks are usually laid up on a forming arch which holds them in place until a section of the kiln is fully lined so that the blocks become self-supporting, whereupon the arch is removed.

In the operation of the kiln, the raw material, such as crushed rock, is introduced at the feed end 3 and travels toward the delivery end 4 due to the rotation of the shell ,A, whereas hot kiln gases are supplied to the shell at the delivery end and progress through the shell to the ch ney at the feed end; the moisture and other volatile matter contained in the raw material are driven oil by the heat of the kiln gases which heat gradually decreases in intensity as thegases approach the feed end of the kiln. With a lining combining a heat insulating substance and a heat-conducting substance, the operation is improved in that the lining B absorbs heat from the kiln gases and gives up heatto the raw material. This increases the efficiency of the kiln, so that I am enabled to increase the capacity of a kiln of given size, or to attain an equal capacity with lower fuel consumption.

The burning zone 4-6 of the shell is not lined with blocks 6 having the radiating characteristics because in this zone the clinker or raw material is in a very sticky condition so that it adheres to the lining 7, forming a coating which protects this lining from the kiln gases. It follows, of course, that there would be no object in equipping this zone with a heat-radiating lining such as the lining A.

Although I have herein shown and do scribed only one form of heat treatin apparatus and one form of lining embo ying my invention, it is understood that various Having thus described my invention, what I claim is:

l. A lining comprising a mixture of a heatinsulating substance and a heat-conducting substance varying in proportion progressively from a relatively small percentage of the heat-conducting substance to a relatively large percentage of the heat-conducting substance.

2. A lining comprising a mixture of a heat-insulating substance and a heat-conducting substance made up of layers varying in proportion progressively from a relatively small percentage of the heat-conducting substance to a relatively large percentage of the heat-conducting substance.

3. A'lining for a heat treating container comprising a mixture of a heat-insulating substance and a heat-conducting substance varying in proportion progressively from a relatively small percentage of the heat-conducting substance adjacent the container wall to a relatively large percentage of the heat-conducting substance at the inner surface of the lining.

4. A lining for a heat treating container, made up of a plurality of layers each comprising a mixture of aheat-insulating substance and a heat-conducting substance, the

percentage of the latter substance increasing progressively from the layer nearest to the wall of the container to the layer exposed to the material being treated.

5. A lining for a heat treating container comprising a blockhaving a body portion made of a mixture of heat-insulating substance and heat-conducting substance, and a flange of heat-insulating substance for spacing said body portion from the wall of the container.

6. A lining for a heat treating container comprising a block having a. bndv portion and a flange for spacing said body portion from the wall of the container. said body portion being made of a mixture of heatinsulating substance and heat-conducting substance, the percentage of heat-conducting substance increasing progressively by layerstrom said flange to the opposite surface of the block.

ANDREW G. CROLL.

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