US2126325A - Retort and retort setting - Google Patents

Description

Aug. 9, 1938. c. E. HAwKE 'RETORT AND RETORT SETTING Filed Oct. 2l, 1936 3 Sheets-Sheet 1 K mm WH EE. w N C.- R A C ATTORNEY.

Aug. 9, 1938. c. E. HAWKE RETORT AND RETORT SETTING 3 sheets-Sheet 2 Filed Oct. 21, 1936 NLM INVENTOR. y CLARENCE E. HAM/ KE BY M ATTORNEY.

Aug. 9, 1938. c. r:. HAWKE RETORT AND RETORT SETTING Filed oct. 21, 193e 3 Sheets-Sheet .'5l

INVENTOR. CLARENCE E, HAWKE ATTORNEY.

Patented Aug. 9, `1.938

UNITED STATES PATENT oFFlcEa aizsszs amour AND uproar sn'rrmc Clarence E.l Hawke, Metuchen, N. J., assigner, by mesne assignments, to The Carborundum Co pany, Niagara Falls, N. Y., a corporation of Delapplicati@ october 21, issn, ser-n1 No. 106,867

s claims. (ci. 263-37) A This application relates to improvements in retorts and retort settings. More particularly the application is concerned with vertical retorts composed of non-metallic refractories, and used 5 for metallurgical purposes or for the calcination of minerals. The present applicationis a con- Non-metallic refractories are extensively yused where resistance tovchange of shape at high temperatures and chemical inertness at high temperatures are required. It is not possible to construct a retort of non-metallic refractory materials that will be absolutely gas or vapor tight. Retorts can be built up of lnon-metallic refractory elements consisting of superimposed hollow one-piece sections. The walls of a retort can also belbuilt up by using\ combinations of refractory shapes with both horizontal and vverti- 'cal joints `which can `be lapped or which can have tongue and groove connections. The sections or elements oi' a retort can also be cemented together.' Such structures can be made -reasonably tight and will show little or no gas or vapor leakage, provided pressures are balanced within an inch or two of hydrostatic pressure. Such retorts, however, will not stand prolonged periods of operation without developing leaks either throu'ghthe opening of the vertical joints, or because "of the development and opening of cracks in the body of the refractories employed. x I have discovered that, in retorts of the type just "describe, little or no'trouble is caused by the opening oi' horizontal joints orby the de-` velopment or opening of cracks extending in a horizontal direction. This is due to the fact that the load imposed upon the refractory elements by the upper portion of'a retort (including the portion of the retort which extends beyond and above the heating chamber)` prevents the opening of 'horizontal joints or cracks and the development and opening of cracks extending in a horizontal direction. o l

, Among the refractories which are most useful 55 for high temperature work may be mentioned In such industrial applications as have been pressure.

silicon carbide, which has a high thermal conductivity (for a non-metallic refractory) and' which retains great strength to compressive loads at the temperatures to which retorts are ordinarily subjected. This characteristic permits the use of this material in thin sections. Even this refractory is liable, however, to the develop- .ment of hair-line cracks during prolonged' periods of operation in which strains are produced by non-uniform heating or by rapid c'ha'ngesin temperature or by changes in local Such causes are likely to produce changes in [volume which are not uniform throughout 'a given refractory element. `The strains so produced must be relieved, and are relieved when the refractory element cracks or fractures. These cracks may not be visible when they r'st occur on account of the minute4 thickness of the openingproduced. They will open up to a greater extent during prolonged periods of heating'unless some force is applied tov prevent the opening. In the case of a vertical retort therefore: the ilne cracks which occur in a horizontal direction are not likely to open up to any serious extent because of the superincumbent weight which tends to close the openings. The case is quite diilerent with vertical cracks. This invention is concerned principally with lthe development of practical means for preventing vertical cracks from opening up in retorts built of non-metallic refractories.

Forpurpcses o'f illustration my invention is `f lescribed with reference to vertical retorts having a rectangular cross-section. The type of retort has long sides (as illustrated4 in the acf companying drawings) and-narrow ends, the4 heat being transmitted from sources of heat situ- `ated outside of the opposite side walls.

In the accompanying drawings:

Figure l shows a horizontal section of a retort mounted in a furnace, the section being taken on the line I-I of Fig. v2; I i

'Figure 2 is a fragmentary sectional elevation taken on4 the line II-II of Figure l;

Figure 3 isl a fragmentary horizontal section taken on the line III-HI of Figure 4 and illusftrating a modificationof the means used for applying pressure to the end walls;

Figure 4 is a fragmentary sectional elevation taken on the line IV--IV of Figure 3;

Figure 5 is a fragmentary horizontal section illust'rating means for facilitating movement of a ompression member in a vertical Ydirection where such movement is desirable to reduce stresses resulting from`temperature changes;

Figure .6 is a, fragmentary horizontal section of a retort and adjacent setting, the end of the -retortshown being. oppositely disposed to that shown in Figure 5;

Figures ,7l and 8 are fragmentary elevations -partly in section illustrating means for-applying horizontal. forces 'to pairs of compression blocks which are in contact with end walls of the respective retorts, the form of the joints between adjacent tiles of the retorts being different in the two views;

Figure 9 is a horizontal section of a retort and f of part Yof the setting and shows side walls of the retort which can expand or contract horizontally independently of the end wall shown at the left; and f Figure 10 is a view similar to Figure 9 but showing weighted crank means for applying horizontal forces. to the side walls instead `of spring means.- x

Referring to the drawings in detail there is shown'in Figure 1 an elongated retort 2 whose sides 2 are made as long as practicable. Heat is transmitted to the material inside the retort through these long sides from combustion chambers 4. The distance between the side walls of the retort mayvary from 2 inches to 18 inches depending uponthe process involved. The eective heating of the material within the retort will not be much affected by the length of the walls 3,

`that is by the horizontal dimensions of the heating surfaces exposed to the combustion chambers. On the other `hand if the distance inside the retort between the side walls is too great, the materials near the wall of the retort will be overheated before the materials in the center of the retort reach the desired temperature. The optimum distance Ibetween the side walls will depend on the thermal conductivity of the materials under treatment. y

It has been found that little or no trouble occurs through cracking of the refractories in the end walls 5 since these walls are not exposed to the combustion gases and are also of relatively small horizontal dimensions, so that vit is anot usually necessary to use vertical joints in these end walls 5. The difilculties described above have been experienced in the side walls which are usually several feet in length and which therefore have to be built up from tiles with vertical as well views the retorts have been indicated without vertical joints, vertical cracks are `likely to form duringthe operation of the retorts. One of the objects of the present invention is to prevent such cracks'from opening up.

For efilclent operation the side walls of the retort have to be-built of a material having a high thermal conductivity while the walls 6 of the combustion chamber are built of a poorly conducting refractory such as hre-clay. As these` i two types of materials have `in general different rates of expansion, it is essential that the retort should not bevv rigidly tied in with the structure of vthe setting, -for if this is done the entire retort structure may be subjected to such strains as will cause destructive cracking of the refractories and the opening nup even of horizontal joints. It is impractical therefore to hold the retort in compression from the sides by rigidly tying the retort structure in with the structure of thesetting.

.In the practice of my invention I apply presf ample by rotation of as horizontal joints. While in some ofY the sure in a horizontal direction to either one or ture of the retort setting. For example, in Figure 1 the movable blocks 1 and Il are urged toward the respective ends of the retort by means of the springs 9 and I0. The amount of compression in the springs may be adjusted, for exthe member I2 which is threaded in the cap I3. As indicated in Figure 2 individual pressure-applying means may be used on a number of superimposed tiles in the endwalls.` f

In the modification shown in Figures 3 and 4 the end walls of the retort are pressed with the aid of blocks 1', which in turn are pressed by means of weightedlevers such as that indicated at I4. Pneumatic or hydraulic pressure devices mayalso be utilized, the hydraulic pressure being cushioned by means of a spring or by means of compressed air, as illustrated diagrammatically in my U. S. Patent No. 2,067,085. f

Horizontal forces should be applied to a suillcient number of the end wall. elements to prevent any vertical cracks or joints from opening up in the side walls as the result of internal pressures `produced by the load in the retortor by the de- `The end walls are therefore `not prevented from vertical expansion or contraction by their contact with the pressure-applying means. Where no such rollers `are shown (as in Figures 1 and 2) the applicationof horizontal forces can be omitted during the heating up period until the retort is brought to operating temperature. The horizontal forces are then applied by tightening up on the threadedy bolts I2 until the desired compressive force is obtained. With this arrangement, the spring pressure should be released before the retort is cooled.

In the modification shown in Figure 5 pro- Y vision is made for the movement of the compression memberl in a vertical direction, where, for example, relief is needed from strains due to changes in temperature. In this case the rollers I8 are carried by brackets I8 which are in. turn securely attached to the supporting members 2| of the retort setting. The plate 22 (to which the compression member 1' is attached) is thus permitted to move in a vertical direction during expansion orcontraction of the retort relatively to the supporting members 2l. Referring to Figure 6, one end of a retort may abut against rollers 23 which are supported on the retort setting while' the opposite end of the retort is pressed by the resilient means shown in Figure 5, which means is vertically movable with Yrespect to the adjacent setting asf explained above. f-

In the modification shown in Figure I means` are shown for applying a horizontal force to two compression blocks located adjacent-an end wall of a retort by means of a single force mecha- 75 nism. In this case a weighted lever mechanism (of the bell-crank type) is indicated in the drawings, but other means such as springs or hydropneumatic or pneumatic means or hydraulic means (cushioned by springs) may be used for applying the horizontal forces, as illustrated diagrammatically in my U. S. Patent 2,067,085.

The modification shown in Figure 8 is similar to that shown in Figure 'i except that the form of joint between the tiles that compose the end walls and side walls of the retort is diilerent.

In the modication shown in Figure 9 horizontal pressures are exerted on the side walls through terminal blocks 34. The joints in the end wall that run parallel to the length of the retort are sealed by means of loose packing in the chambers 35. Gravity forces this packing against the members 34 and causes a seal between the members 34 an-d the intermediate portion of the end wall and also between the members 34 and the adjacent retort setting.

As has been indicated above, the walls of the retorts are made of a non-metallic refractory having a low coeicient of thermal expansion and a high degree of mechanical strength at high temperatures, such as bonded silicon carbide or recrystallized silicon carbide. Other refractories havinga thermal conductivity greater than 0.006'

calorie/cm3/sec./C.,may be used if they possess the required mechanical strength, resistance to spalling and chemical inertness. The walls, of the retort setting can be made of re-clay backed with steel beams as indicated in Figure 1 of the drawings.

While I have described several methods by which the invention may be applied to vertical retorts, the principle underlying these methods is applicable to a still wider range of retort types and arrangements with their associated settings.

'I'he drawings are` intended to illustrate the practicability of the application of the invention in a Variety of forms.

I claim: g

1. A furnace for the heat treatment of materials comprising an elongated retort of rectangular horizontal cross section and having extended side walls forfheat transmission from combustion chambers located on each side of the retort and having narrow end'walls joining said side walls, said end walls being shielded from the combustion gases, an outer furnace wall surrounding the retort and the combustion chambers, said outer wall having a movable section of superimposed blocks adjacent one end of the retort, and a plurality of weighted bell-crank levers for exerting horizontal forces against the adjacent end of the retort and tending to close vertical cracks in the side walls of the retort.

2. The furnace structure described in'claim 1 in which the bell-crank lever compression mechanism transmits pressure through a member mounted for slidable movement in a vertical direction with respect to the outer wall of the furnace.

3. A retort having side Walls for heat transmission from exterior heating sources and end walls contacting with the retort setting, and

automatically controlled means disposed between the setting and a terminal portion of each side wall for applying independently to each side wall horizontal pressure tending to close vertically disposed joints and cracks.

4. A retort having side walls for heat transmission from exterior heating sources and end walls contacting with the retort setting, means disposed between the setting and a terminal portion of each side wall for applying independently to each side wall horizontal `pressure tending to close up vertically disposed joints and cracks, and cavities adjacent to terminal portions of the side walls containing finely divided material for sealing under the action of gravity the side walls with respect to the end walls and the retort setting.

5. A furnace for the heat treatment of materials comprising an elongated retort of rectangular cross section having extended side walls for heat transmission from combustion chambers located on each side ofthe retort and having narrow end walls one of which ts loosely between said elongated side walls, an outer furnace wall surrounding the retort and the combustion chambers, said outer furnace wall having two movable sections of superposed blocks in contact with the respective loosely tted ends of the side walls, and yieldable means for pressing said side walls of the retort in a horizontal direction.

6. A furnace for the heat treatment of materials comprising an elongated retort of rectangu lar cross section having 'extended side walls for heat transmission from combustion chambers located on 'each side of the retort and having narrow end walls one at least of which fits loosely l between said elongated side walls, an outer furrespect to the end walls of the retort and with y respect to the outer furnace wall.

7. A retort having side walls for heat transmission from exterior heating sources and end walls contacting with the retort setting, and gravity controlled means disposed between the retort setting and a terminal portion of each side wall for continuously applying independently to each side wall horizontal pressure tending to close vertically disposed joints and cracks.

8. Agretort having side walls for heat transmission from exterior heating sources and end walls contacting with the retort setting, and resilient means disposed between the retort setting and a terminal portion of each side wall for continuously applying independently to each side wall horizontal pressure tending to close vertically disposed joints and cracks.

CLARENCE E. HWKE.

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