US2447369A - Retort for distillation furnaces - Google Patents

Description

Aug. 17, 1948.

H. C. SCHWEITZER RETORT FOR DIS'IILLATION FURNACES Filed Feb. 12; 1943 INVENTOR. 15225527 CJCHWE/ TZEE.

4 ATTORNEYS Patented Aug. 17, 1948 UNITED STATES PATENT OFFICE RETORT FOR DISTILLATION FURNACES Herbert C. Schweitzer, New York, N. Y., assignor to The American Metal Company, Limited, New York, N. Y., a corporation of New York Application February 12, 1943, Serial No. 475,679

3 Claims.

sists of the reduction of oxides and other compounds of zinc by means of carbon in extraneously heated retorts, such retorts being formed by muiile-shaped cylindrical vessels closed at the back end and open'at the front end or mouth,

and placed within the furnace in an approximately horizontal position but somewhat inclined downwardly from back to front. Very serious losses occur in the use of retorts in distillation-furnaces by reason of the breaking and bending of the retorts and/or also by reason of destruction and perforation of the retort-wall due to the combined corrosive action of slags, metal vapors and other corrosive substances produced within the retorts during the distillation process.

Attempts have been made heretofore to produce retorts to overcome the defects mentioned. For example, muflled-shaped retorts with flat bottoms, the so-called Rhenish and Silesian retorts have been proposed, but attempts to produce these retorts by machine has greatly increased the cost thereof due principally to losses occurring during the extrusion of the retort mud through the die of the retort press and during the drying and baking or calcining process because of cracks formed frequently in the retort body during these different manufacturing steps. They are generally made by hand accordingly. Even when so made, the abrupt angles made between the bottom wall and the side wall of these flat-bottomed Rhenish and Silesian retorts, and in some instances the abruptly angled apex, result in a bending or crooking of the retort or production of cracks, particularly during the drying or baking operation. It is my belief that stresses are set up due to the necessary abrupt variations in the wall thickness, which are responsible for such defects.

Because of these defects, the usual practice in this country is to produce retorts of substantially circular, elliptical, or oval cross-section, which are supported at the ends only and are inclined with the mouth pointed downwards. These retorts are ordinarily manufactured by means of a hydraulic press. The walls of these retorts are usually of a uniform thickness of about one-inch throughout, which is a satisfactory thickness to permit the passage of heat therethrough for the maintenance of high temperatures in the distillation charge inside of the 2 1 retort, but otherwise has disadvantages. The temperature maintained inside of the retort is of the order of 2100-2600 F. and, in order to maintain such temperatures, the walls of the retorts used in practice in the United States are as indicated. As noted above, however, such retorts are subject to serious losses through break ing and bending in thedistillation operation and are particularly susceptible to destruction and perforation of the bottom retort wall due to the action of slags, metal-vapors, and other corrosive substances. No general thickening of the entire wall surface is practical because I have found that such thickening reduces the output and is otherwise undesirable.

However, I have found in accordance with my invention that an important increase of the average retort life can be obtained while the actual production of the distillation furnace, can be increased by thickening the retort wall only in a relatively small section of the wall, namely, about one-fifth to one-half of the circumference, while avoiding the sharp angles, with resulting cracks and bending of the Silesian and Rhenish retorts. This thickening is made in the portion against which the charge lies. I have found that by my manner of thickening, the retort life is greatly increased and although the conductivity of thewall is somewhat lowered, it is more than compensated for by the longer continuous operation of the retorts thus permitted.

7 The principal object of my invention accordingly is to produce an improved retort which will resist more effectively the action of heat and corrosion, which may be formed 'by the standard equipment usually found in the ceramic department of zinc plants and which will have substantially no greater tendency to crack or break in the drying and baking process than the ordinary cylindrical retorts now in use.

The invention accordingly comprises a ceramic distillation retort having an end opening and a substantially uniformly curved interior space (usually cylindrical) and an outer wall surface curved substantially throughout its extent and substantially free from abrupt bends, the lower wall of the retort being solidand as positioned for operation being gradually thickened toward the lowest portion of the retort, the retort wall beingof substantially uniform thickness otherwise. It also includes such, .a retort having a. slightly thickened top portion.

In the accompanying drawings which form part of this specification are shown embodimentsv of the invention as I now prefer to practise it. v

In the drawings,

Fig. 1 represents a longitudinal section of a preferred form of retort made in accordance with my invention;

Fig. 2 represents a cross-section on a reduced scale along the line 2-2 of Fig. 1;

Fig. 3 is a cross-section on a reduced scale of a modifiejd form :of retort such as :shown in Fig. 2, where the thickening of the lower wall of the retort occurs over about one-third of the circumference of the retort as contrasted with the showing in Fig. 2 where the thickening of the lower wall occurs over only about one-fifth of the circumference of the retort, and

Fig. 4 is a cross-section 'of a modification of the retort as shown in Fig. 1, in which both the top and lower part of the retort :are thickened, in each instance, for about one-fifth of the circumference of the retort.

The retort shown in Figs. 1 and 2 is a ceramic distillation retort closed at one end and open at *the other. 'The retort is formed in'one piece by extrusion from -a hydraulic press. The "retort is formed generally of a'we'll-known mixture of clay and-silica, or'clay and Carborundum or like mixture, which is made into mud in a well-known manner and 'then extruded. After extrusion, it *is then'ba ked and dried and'is ready to be placed in 'z'inc distillation furnace supported .at the endsonly'andslig'htly inclined with the open end pointed downwardly. The numeral I designates the top of the-retort and 2 designates the bottom-or lower part of the retort asit isnset in position'for'operation in the distillation furnace. The retort is in the form of a'tube closed by the end 'wa'll 3 at one end andhaving the open mouth .4 at the opposite end. The interior surface 5 of 'the retort is substantially cylindrical in form and in the "embodiments shown :in Figs. 1 and 2, the outer walls 6 are substantially cylindrical. The wall-of the retortis accordingly of substantially uniform thickness except in the lower portion of the 're'tort against which the charge lies. In this lower portionythe wall is gradually thickened until it reaches a maximum thickness at the "lowermost point on the retort designated by the numeral 2. As shown in Fig. 2, this thickening occurs throughout an arc of about 72. The thickening is equally distributed on either side of the vertical axis of the retort and extends throughout the length of the lower wall of the retort. This thickening is done while maintaining the other dimensions of the retort and its interior capacity substantially the same as in the usual cylindrical type.

In Fig. "3 a retort construction similar to that in Figs. '1 and Z'is shown except that the lower partof the retort :wall is thicken d through approximately one-third of the circumference of the retort.

In zinc distillation, the charge placed inside these retorts-contains zinc, carbon, and various impuritiesincluding basic impurities such as iron, barium, magnesium, etc. Where such charge has been-placed in the ordinary cylindrical (Belgian) type of retort commonly in use-in the United States, theaverage life of a retort made of plas- "tic clay, grog material and silica may be only two to three weeks, due to the corrosion of the retort wall caused by liquid slags, metal-vapors and other corrosive substances contained in the charge.

Due 'to progressive thickening of the retort wall 'over one-fourth to one-half of the total circumferenceinaccordance with my invention in the thickened bottom portion.

to receive the charge, the retort wall, according to my invention, is built up on the outside of the retort only. For instance, in a normal Belgian retort, with circular cross-section as shown in Fig. 1, and 'with an inside diameter of about 9 inches and an equal wall thickness of about 1 inch, one builds up progressively, according to the invention, the wall over about 70 to of the circumference (see Fig. 2) or up to of the circumference (see Fig. 3) by thickening the retort wall on the outside only in such-a manner that in the thickest wall-section (A-A, Figs.'2 and 3), the wall thickness is about 1 /2 inches.

Referring now to the embodiment shown in Fig. 4., it is sometimes desirable to-buildup the retort wall so that the diametrically opposedupper and lower sections of the retort areincreased in thickness. Thus, a reinforcement of the retort wall is obtained, enabling the .latter to resist better the action of slag dropping from an .upper part or" the furnace chamber on the'toproof of the retort as sometimes occurs where'a retort in an upper row becomes .corroded and its liquid charge is released and falls on the surface'of ta retort positioned therebelow. In this figure-the inner surface 5 of the retort is substantiallycylindrical as shown. The outer surface 6 .is partially cylindrical and then passes by smooth curves into the thickened portions adjacent to the top and bottom of the retort. In this figure, the

thickened top portion extends through an arc of about one-fifth of the circumference of the retort, namely, about 72; The same is true'oI The remainder of the side wall of the retort is ofuniform thickness. The top thickened portion is symmetric with respect to the vertical axis. The same is true of the bottom portion. As shown in this drawing, the thickness of the top wall of the retort is less than that of the lower wall, since it normally does not have to withstand the amount of corrosion that the lower wall sustains. Generally, this reinforcement of the top section of the retort wall may be very slight, not more than about 10-20% of the thickness of the unthickened side wall. For instance, where'the side walls are about one-inch in thickness, it is sufficient to reinforce the top wall up to about 1 inches.

The consumption of material :in'the manufacture of these retorts'is only relatively slightlyincreased by the building up of the-retort wall according to the present invention. 'Only about 10-15% of clay and other materials more "than for the normal retort with the same insi'de'diamstar is requiredfor the reinforcin of the walls of my improved retort, The retorts clescribedmay be easily extruded by a hydraulic press and-present little difficulty in distortion during extrusion and there are few accidents due to cracking or breaking during the drying and baking. It will be observed that the cross-section of the retorts show rounded surfaces throughout with substantially no abrupt angles or bends to occasion such cracking or rupture of the retorts. The life of the retorts prepared in accordance with the above is increased from 50 to 100% or more as stated over the cylindrical Belgian retorts in ordinary use, I find that it is possible to obtain this in crease in the retort life even working at somewhat higher furnace temperatures than would normally be employed with the round type of retort. The longer life of these retorts means, accordingly, that a greater output can be obtained from the distillation furnace and that time, material and labor are thereby saved.

In each of the figures it will be noted that the walls throughout are solid, that is, they have no passages or like openings therethrough to complicate extrusion from a hydraulic press.

What I claim is:

1. A ceramic distillation retort, extruded in one piece, having an end-opening, and having an un-- lined, substantially uniformly curved interior space and an outer wall surface curved substantially throughout its extent and substantially free from abrupt bends, the lower part of the retort as positioned for operation being gradually'thickened toward the lowest part, the retort wall being of substantially uniform thickness otherwise and being substantially solid throughout.

2. A zinc distillation retort closed at one end and open at the other, extruded in one piece, having an unlined substantially cylindrical interior space and an outer Wall space curved substantially throughout its length and free from abrupt bends and having a substantially uniform wall thickness except on the lower portion where each side wall is gradually thickened until it reaches a maximum thickness at substantially the lowest part of the retort as positioned for operation, said lower portion being substantially solid throughout.

3. A ceramic zinc distillation retort closed at one end and open at the other, formed in one piece, having a substantially cylindrical interior space and a partly cylindrical outer wall surface curved substantially throughout its extent and substantially free from abrupt bends, having a substantially uniform wall thickness in the side walls but both top and bottom walls of the retort as positioned for operation being thickened by a gradual thickening of the side walls from the upper and lower portions thereof respectively with the maximum thickness of the retort being substantially at the topmost and lowermost portions respectively thereof, said lower portion of said retort being substantially solid throughout.

HERBERT C. SCHWEITZE-R.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 258,222 Cross May 23, 1882 642,722 Sadtler Apr. 17, 1906 799,744 Maokay Sept. 19, 1905 818,070 Ziesing Apr. 17, 1906 1,084,679 Webster Jan. 20, 1914 1,133,313 Parmley Mar. 30, 1915 1,609,427 Queneau Dec. 7, 1926

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