US2421120A - Apparatus for effecting chemical reactions - Google Patents

Description

May 27, 1947. H. L. GRISWOLD EI'AL 2,421,120

APPARATUS FOR EFFECTING CHEMICAL REACTIONS Filed Nov. 10, 1942 3 Sheets-Sheet l a 9 4 5 2 I 7 i 2'5 I 1 AL: i l

I FIG. I.

INVENTOR. HOWARD L. GRISWOLD and ARTHUR I'ZCAPE 4 H62. BY fww iw ATTORNEY'S v T May 27, 1947. H. GRISWOLD ETAL APPARATUS FOR EFFEC'IING CHEMICAL REACTIONS Filed Nov. 10, 1942 3 Sheets-Sheet 2 [NV R. I'DWARD L. GRlSmLD and A THUR r. C APE. BY M ATTORNEYS H. L. GRISWOLD ETAL' 2,421,120

APPARATUS FOREFFECTING CHEMICAL REACTIONS a Sheets-Sheet a May 27, 1947.

Filed Nov. 10, 1942 ATTORNEYS Patented May 27, 1947 REACTIONS Howard L. Griswold, Canton, and Arthur T. Cape, Columbus, Ohio, assignors to Coast-Reduction,

Inc., Watsonville, Calif., a

ware

corporation of Deia- Application November 10, 1942, Serial No. 465,172

'4 Claims.

This invention relates, as indicated, to methods oi and apparatus for effecting chemical reactions, but has reference more particularly to the reduction of iron ores and the like.

In application Serial No. 449,088, there has been described an apparatus for reducing iron ores, such apparatus including a furnace 'of the so-called multiple-hearth type, the orebeing moved downwardly through the furnace, while a reducing gas is caused to flow upwardly through the furnace in countercurrent relation to the ore. The ore, in the course of its movement through the furnace is gradually rabbled across the hearths by means of rabbles disposed directly above each hearth, the reduced ore being finally discharged from the lowermost hearth through a suitable opening and into a cooler.

The present invention is directed more particularly, to improvements in the construction of the lowermost hearth of such a furnace, whereby a reducing gas or gases may be passed vertically upward through the ore while being rabbled, and at the same time, the ore is prevented from falling through the gas inlet openings in said hearth.

The invention can probably be best understood by reference to the accompanying drawings, wherein, for purposes of illustration, we have shown a preferred embodiment of the invention.

In said annexed drawings,

Fig, l is a cross-sectional view, showing the lowermost hearth of a furnace of the multiplehearth type, said hearth incorporating the principal features of the invention;

a Fig. 2 is a cross-sectional view, taken on the line 2-2 of Fig. l

Fig. 3 is a fragmentary cross-sectional view, on a greatly enlarged scale, taken on the line 3-3 of Figs. 2 and 4, and

Fig. 4 is a fragmentary cross-sectional on a greatly enlarged scale, taken on the line 4-4 of Fig. 2.

Referring more particularly to the drawings, there is illustrated a furnace of the multiple hearth type, comprising a cylindrical shell I, suitably lined with refractory material 2, and the lowermost hearth of which is indicated by the reference numeral 3.

The hearth 3 is an out feed hearth, receiving the ore from a central circular port or opening 4. in the hearth 5 immediately a'.ove the hearth arms 8, which are attached to the central shaft 8 of the furnace. A lute ring it is secured to the shaft 9 at a point immediately above the hearth vievi- 4o 3, and moving said ore, by means of rabbles 6,

to an opening I in the hearth adjacent the periphery thereof, whence the ore falls into a suit- 3, and serves to deflect the ore dropping through the opening 4 onto the hearth 3.

The present invention is, as previously stated, concerned primarily with the construction of the hearth 3, and such construction will now be described in detail.

The hearth 3 consists of a multiplicity of hearth or grate bars Ii, formed of cast iron or a suitable heat and wear-resistant alloy, and preferably arranged in a plurality of circumferential rows about the shaft 3. The hearth bars in each row are preferably arranged in staggered or offset relation to the bars in the rows immediately adjacent thereto.

Each of the bars II is of gradually increasing width, in a radially outward direction, as will be apparent from Fig. 2, and each bar comprises a body or hearth portion l2, which is inclined upwardly in the direction of movement of the ore, and has a vertical reinforcing rib l3, which depends from the lower edge of the hearth portion l2. These ribs l3 extend into recesses ll of bar supporting rings IS, the ribs resting on the bottoms of these recesses, as shown in Fig. 4.

The rings ii are preferably cast in segments, so as to facilitate removal and replacement of portions of the rings.

The hearth portion l2 of each bar is provided with a lip it at its forward edge, which overlaps the hearth portion of the bar immediately ahead, and rests upon ridges I! which project from the hearth portion of the bar directly above the rib l3.

The ridges I! have portions thereof removed to form elongated slots l8, and portions of the lips iii are removed as at l9 to permit access of gases to and egress of such gases from the slots.

Each of the hearth bars is also provided at its radially-inward end with a rounded flange 20 which overlaps and virtually interlocks with a hooklike flange 2| at the radially-outward end of the hearth bar immediately adjacent thereto.

The segments of the bar supporting rings I5 I able cooler. The rabblesli are mounted on rabble ore which finds its way below the hearth to cleanout openings II, for removal through clean-out doors 2!. The spaces between the hearth and the refractory material it serve as gas chambers from which the reducing gases are passed through the hearth, as will be presently explained.

To facilitate placement of the grate bars in position. the upper edges of the segments of the rings it are sloped as at 28, immediately in advance of the recesses ll.

With the foregoing constructional features in mind, the operation or use of the hearth will now be briefly described.

As the ore which falls onto the hearth from the opening 4 is rabbled across the hearth by the rabbles 6. the rabbles moving in the direction indicated by the arrows in Figs. 2 and 4, reducing gases are caused to flow upwardly from the spaces under the hearth, through the slots 18, and thence into the space above the hearth. such flow being indicated by the small arrows in Fig. 4. The gases, as they emerge into the space above the hearth level. are effective to cause a reduction of the iron ore from an oxidized state to a less oxidized state or to melting stock (sponge iron). Since the effective area of the slots is, due to the large number of grate bars, rather large, a considerable volume of reducing gas can be utilized in this manner for reduction purposes.

Since the lips ii of the grate bars overlap the adjacent grate bars and extend over the slots l8, the passage of the ore through these slots is effectively precluded, and at the same time, the ore is prevented from clogging the slots and thereby interfering with the flow oi the gases through th slots and into the space above the hearth. The flanges 20 and 2| likewise coact to prevent passage of ore downwardly through the joints between the grate bars.

While the invention has been described particularly with reference to the reduction of iron ore in a multiple hearth type furnace, utilizing rabbles for the movement of the ore, it is to be understood that the invention is applicable generally to the effecting of other chemical reactions between gases and solids, as to examples, the

roasting of ores, the oxidation of organic matter in the treatment of sewage, etc. It is also to be understood that the constructional features of the invention may be incorporated in other than the lowermost hearths of multiple hearth furnaces, and may, in fact, be used in connection with other types of hearth furnaces.

Instead of having a plurality of annular rows of grate bars, a single annular row of grate bars may be employed to form the hearth, the bars, in such case, being of suflicient length to extend across'the hearth area, i. e., of a length substantially equal to the radius of the furnace.

It is to be understood that the form of our invention, herewith shown and described, is to be taken as a preferred example of the same, and

that various changes in the shape, size and arrangement of parts may be resorted. as, without departing from the spirit of our invention, or the scope of the subjoined claims.

Having thus described our invention, we claim:

1. In apparatus or the character described, a hearth comprising an annular row of relatively fiat grate bars arranged in overlapping relation, means comprising ridgesat one edge of each bar extending vertically above the surface or each of the grate bars and into engagement with the overlapped portion 01 the adjacent grate bar, said ridges spacing said bars vertically at said edge in the region of said overlap to provide slotted openings, means for passing a gas through said openings, and means for causing a solid material to traverse said hearth.

2. In apparatus of the character described, a hearth comprising a plurality of grate bars, each of said grate bars having ridges extending above the surface of the bar adjacent one edge, and provided with cut out portions defining an open recess therebetween, and each of said bars having a, lip overhanging the adjacent bar and resting on the ridges thereof, and forming with said recess an elongated slot for the passage of a gas therethrough, said lips having portions thereof removed to facilitate access of said gas to and egress from said slot.

3. In apparatus of the character described, a hearth comprising a plurality of annularly arranged relatively flat grate bars, each having a substantially vertical radially-extending supporting rib at one edge, and a supporting ring having circumferentially-spaced recesses in its upper edge into which said ribs extend, the edges of the ring between said recesses sloping toward one of said recesses.

4. In apparatus of the character described, a hearth comprising a plurality of relatively flat grate bars arranged in overlapping relation, means comprising ridges at one edge of each bar extending vertically above the surface of each of the grate bars and into engagement with the overlapped portion of the adjacent grate bar, said ridges spacing said bars vertically in the region of said overlap to provide an elongated slot having substantially horizontal upper and lower walls, means for passing a gas through said slot, and means for causing a solid material to traverse said hearth.

HOWARD L. G RISWOLD. ARTHUR T. CAPE.

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

UNITED STATES PATENTS Number Name Date 2,287,663 Brassert June 23, 1942 2,296,522 Hartley Sept. 22, 1942 1,802,960 Simonds Apr. 28, 1931 1,874,340 Nygaard Aug. 30, 1932 456,733 Pederson July 28, 1891 1,547,908 Grouchy July 28, 1925 1,778,664 Dragon Oct. 14, 1930 1,711,131 Thomas Apr. 30, 1929 588,859 Flint Aug. 24, 1897

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