US2238941A - Preheating apparatus - Google Patents

Description

April 22, 1941. P. T. LINDHARD ETAL PREHEA'I ING APPARATUS Filed July 16, 1940 2 Sheets-Sheet 1 [III/III) ATTORNEY? April 22, 1941'. P. T. LINDHARD ETAL PREHEATING APPARATUS 2 Sheets-Sheet 2 Filed July l6, 1940 \M NM MM ATTORNEY)" Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE PREHEATING APPARATUS Povl T. Lirrdhard, Rumson, and Einar Svendsen, Cranford, N. J., assignors to F. L. Smidth & 00., New York, N. Y., a corporation of New Jersey Appiicatic-n July 16, 1949, Serial No. 345,723

15 Claims.

This invention relates to apparatus for the preheating of materials by hot gases, such, for example, as the exhaust gases from the kiln in which the materials are later burned, and more particularly, the invention has to do with a preheating apparatus which includes a novel grate or pervious support for the material undergoing treatment.

Preheating apparatus of the type referred to may take various forms and in one such apparatus, disclosed in United States Patent No. 2,024,453, issued December 17, 1935, on an application of Vogel-Jorgensen, the material to be preheated is deposited on the surface of a pervious cylindrical support which is mounted within an extension of the shell of a rotary kiln and rotates with the kiln. The continuously deposited material forms a layer which is held in place on the support by the hot gases from the kiln passing through the layer and support, and after the material has been carried through the major portion of a revolution, it is discharged from the support by compressed air and is introduced into the kiln. Instead of being mounted within an extension of the shell of a kiln, the Vogel-Jorgensen preheater may be a separate piece of apparatus connected to the kiln in such manner that the exhaust gases flow therefrom to the preheater and the preheated material passes directly to the kiln.

In either form of the preheater referred to, the support on which the material is deposited is subjected to varying temperatures during each revolution thereof, since, during a part of a revolution, hot gases pass through the support and at another point, compressed air flows through the support. The support, if made in one piece or several large pieces, may, therefore, warp as a result of expansion and contraction. The present invention is, accordingly, directed to the provision of a support or grate made up of a plurality of sections which can be readily mounted in position, and the grate and the supporting means therefor are of simple inexpensive construction. The formation of the grate of a plurality of sections overcomes contraction and expansion difficulties and the new grate can be readily assembled in the initial installation and taken apart for repairs, if necessary.

For a better understanding of the invention, reference may be had to the accompanying drawings in which Fig. l is a vertical sectional view through a preheating apparatus constructed in accordance with the invention;

Fig. 2 is a sectional view on the line 2--2 of Fig. 1;

Figs. 3 and 4 are sectional views on the lines 3-3 and 44, respectively, of Fig. 2;

Fig. 5 is a sectional view through one section of the new grate;

Fig. 6 is a fragmentary plan view on the line 56 of Fig. 2 with parts broken away; and

Fig. 7 is a sectional view on the line 1--'! of Fig. 2.

In the drawings, the grate of the invention is illustrated as mounted within an extension ID of the shell ll of a rotary kiln. The shell has the usual firebrick lining l2 and between the end of the shell and the extension is a collecting ring [3 provided with ports l4 formed by radial ribs IS. A sectional protecting ring [6 of high temperature metal is mounted within the collecting ring to protect the inner surface thereof and the extension II], which is of conical formation, is secured to the collecting ring by a flange l1. At its outer end, the extension is provided with a flange 18 to which is secured a wear ring I9 making sliding contact with the flange 20 of a stationary hood (not shown) which closes the feed end of the kiln.

Mounted on the inner face of the extension l0 and extending lengthwise thereof in alignment with the partitions l5 are ribs 2|, each rib being formed of a group of three sections, each of which is secured to the wall of the extension by cap screws 22 which pass through that wall and enter bosses 23 formed integrally with the rib sections. Along their outer edges, the rib sections are provided with flanges 24 engaging the inner surface of the wall of the extension and the ends of adjacent sections are provided with a slot and rib connection, generally designated 25 (Fig. 7), to permit relative expansion. The end 26 of the end section 2| a of each rib is received in a vertical slot 21 in the aligned partition [5 in the collector ring [3 and at the other end of the extension I0, a sectional ring 28 is secured to the inner face of the extension and'has notches 29 for receiving the adjacent ends of rib sections Zlb. To prevent gas leakage, the under surface of the flange 24 isprovided with a space for the reception of packing 3H and packing may also be introduced in the slots of the expansion connections 25 and in the notches 21 and 29.

Although the extension is frusto-conical in shape, the formation of each rib is such that its ree edge lies in a plane and along that edge is an integral flange 3| which is cut away at spaced points, as indicatedat 32. Inward from each cutout, the rib is stifiened by a short rib 33. If desired, the ribs may be provided with T-bars 34 bolted or otherwise secured thereto instead of being formed with the integral flanges described.

The grate is made up of a plurality of sections, each of which consists of a plurality of flat bars 35 extending vertically and having crossbars 36 securedto the upper edges thereof by welding. The crossbars are preferably round in section and they lie spaced apart a suitable distance to permit the passage of the gases between them. The outer fiat bars 35a are provided with outwardly projecting pins 31 which extend parallel to the crossbars 36 and lie below them a suitable dis-' tance, the outer ends of the pins lying inward from the ends of the crossbars.

In mounting the grate sections on the ribs, the sections are lowered in place against the outer edges of the ribs, with the pins passing through the cut-outs 32 in the flanges 3! or in the upper ends of the T--bars 34. Thereafter, the grate sections are moved endwise so that the pins are out of registry with the notches. The length of the grate sections is such that there are a number' of sections in lengthwise alignment closing the space between adjacent ribs, and in the construction shown, six grate sections are required for the purpose, although the number will vary'with different installations. When all of the sections are in place, they are held against endwise movement which would bring their pins in alignment with the cutouts '32 by means of key pieces 38. Each key piece is inserted at the end of a row of sections and its ends overlie the ribs on which the row of sections is mounted. The key piece is provided with a stud bolt 39 which passes through the Wall'of the extension and a nut 40, threaded on the exposed end of the bolt, serves to hold the key piece in place in tight contact with the ribs which it engages.

In the completed grate, the sections are not rigidlysecured in' place and may move slightly relative to one another both longitudinally and transversely. Expansion and contraction, therefore, do not cause binding that would producewarping.

Inside the extension at its outer end is mounted-a sectional ring 4| provided with flights 2. This ring is made of heat-resistant material and has bosses through which bolts 43 may be threaded into the ring 28 to hold the sectional ring in place. The flights 42 are inclined so as toprevent material deposited on the grate from escaping out the small end of the extension and the inner end portions 44 of the flights are-removed to permit a device for cleaning the grate to be passed between them.

As illustrated in Fig. 1, the material is deposited on the inner surface of the grate by a distributor 45 which may be of any suitable construction, as, for example, that disclosed in the co-pen ding application of Vogel-Jorgensen Serial No. 192,257, filed February 24, 1938. The layer of material on the grate is held in place by hot gases which issue from the kiln and pass through the layer and grate into the passages between adjacent ribs, whence the gases flow to the ports M. A mantle 46 encloses the collector ring and the gases are withdrawn through the ports and mantle by a fan (not shown) connected to a duct 41.

The material on the grate overlying each passage between a pair of ribs remains in position until the port in the collector ring connected to that passage comes into alignment with the end of an air pipe 48 extending through the wall of the mantle and terminating close to the outer ends of the ports. sages successively from the pipe flows along the passages and through the grate and causes the material thereon to be discharged into the trough of a screw conveyor 49 which carries the material forward and discharges it into the kiln. The conveyor and distributor are both protected from contact wi h the hot gases from the kiln by a partition 56 lying within the extension.

As pointed out above, the V ogel-J orgensen type of preheater may include a pervious support mounted within an extension of the shell of a rotary kiln, or the support may be part of a separate piece of apparatus. Also, the support may be arranged so that the material is deposited on the inner surface thereof and held in place by gases passing outwardly, or the'material may be deposited on the outer surface of the support and held in place by gases flowing inwardly. The grate of the invention is suitable for use in any of the types of apparatus referred to and the changes required to adapt the grate for use in that type of equipment in which the material is deposited on the outer surface of the support will be readily apparent.

We claim: 7

1. In a preheat-er, means for supporting a layer of material while hot gases pass through it, which comprises a pair of ribs lying side by side and having free edges, the ribs having lateral extensions formed with spaced cut-outs, a support for the ribs, a grate member resting on the ribs and having projections underlying the extensions, and a key piece at the end of the member preventing endwise movement thereof suificient to bring the projections thereof into line with the cut-outs.

2. In a preheater, means forsupporting a layer of material while hot gases pass through it,

which comprises a pair of ribs lying side by side and having free edges provided with flanges having spaced cut-outs, .a support for the ribs, a grate member resting on the flanges of the ribs and having projections underlying the. extensions, and a key piece at the end of the member preventing endwise movement thereof sufficient to bring the projections thereof into line with the cut-outs.

3. In a preheater, means for supporting a layer of material while hot gases pass through it, which comprises a plurality of ribs mounted side by side radially in an endless series and having free edges, the ribs having lateral extensions formed with spaced cutouts, a'suppor't for the ribs, grate members spanning the spaces between adjacent ribs, each member'having projections underlying the extensions, and key pieces at the ends of the spaces for preventing .endwise movement of the members suflicient to bring the projections thereof into line with the cut-outs.

4. In a preheater, means for supporting a layer of material while hot gases pass through it, which comprises a plurality of ribs mounted side by side radially in an endless-series and having free edges provided with flanges having spaced cut-outs, a support for the ribs, grate members spanning the spaces between adjacent ribs and resting on the flanges thereofleach member having projections underlying the flanges, and key pieces at the ends of the spaces for preventing endwise movement of the members sufficient to Air introduced into the pasthereof into line with the which comprises a plurality of ribs mounted side by side radially in an endless series and having free edges provided with flanges having spaced cut-outs, a support for the ribs, a plurality of grate sections spanning each space between ad jacent ribs, the sections lying in endwise alignment and resting on the rib flanges, each section having projections underlying the flanges of said ribs, and a key piece at the end of the group of sections between each pair of adjacent ribs for preventing endwise movement of the sections suflicient to bring the projections thereof into alignment with the cut-outs.

6. In a preheater, means for supporting a layer of material while hot gases pass through it, which comprises a drum-like support, a plurality of ribs mounted on the support side by side and extending generally radially, each rib having a free edge provided with a flange having spacedcut-outs, grate members spanning the spaces between adjacent ribs, each member having lateral projections underlying the flanges of said ribs, and key pieces at the ends of the spaces for preventing endwise movement of the members sufficient to bring the projections thereof into line with the cut-outs.

7. In a preheater, means for supporting a layer of material while hot gases pass through it, which comprises a plurality of ribs mounted side by side radially in an endless series and having free edges provided with flanges having cutouts, a support for the ribs, grate members resting on the flanges of adjacent ribs and spanning the spaces between said ribs, each member having lateral projections underlying the flanges, key pieces at the ends of the spaces for preventing endwise movement of the members suflicient to bring the projections thereof into line with the cut-outs, means for distributing material to be treated on said grate members, and means for introducing air into the spaces between adjacent ribs to discharge the material from said members.

8. In a preheater, means for supporting a layer of material while hot gases pass through it, which comprises a drum-like support, a plurality of ribs secured to the surface of the support and extending lengthwise thereof, said ribs and support defining passages extending longitudinally of the support and the ribs having free edges provided with flanges having spaced cutouts, grate members mounted on the ribs and forming perforate walls closing the passages,

said members having lateral projections underlying the flanges, key pieces adjacent one end of the support for preventing endwise movement of the grate members sufficient to bring the projections thereof into line with the cut-outs, means for distributing material to be treated on the surface of the grate members, and means for removing the treated material from said grate members.

9. In a preheat-er, means for supporting a layer of material while hot gases pass through it, which comprises a drum-like support, a plurality of ribs mounted on said support and extending side by side lengthwise thereof, each rib bein made up of sections with adjacent sections having interlocking ends, the ribs having free edges provided with flanges having spaced cutouts, a plurality of grate members mounted in endwise alignment to span the spaces between adjacent ribs, said grate members having lateral projections underlying the flanges, a pair of rings one at each end of the group of rings, the rings having notches in which the ends of the ribs are received, and a key piece in each space between adjacent ribs for preventing the members spanning said space from moving endwise sufficiently to bring the projections thereof into line with the cut-outs.

10. The combination with a rotary kiln having an extension at the inlet end thereof of a preheater for the materials to be fed into said kiln, said preheater including a plurality f ribs mounted on said extension and extending lengthwise thereofleach rib having a free edge provided with a flange having spaced cut-outs, a pluralityof grate members mounted on the ribs and having portions resting on the flanges thereof and projections underlying said flanges, and means holding the grate members against endwise movement sufficient to bring the projections thereof into line with the cut-outs.

11. The combination with a rotary kiln having an extension at the inlet end thereof of a preheater for the materials to be fed into said kiln, said preheater including a plurality of ribs mounted on said extension and extending lengthwise thereof, each rib having a free edge provided with a flange having spaced cut-outs, a plurality of grate members mounted on the ribs and having portions resting on the flanges thereof and projections underlying said flanges, means holding the grate members against endwise movement sufficient to bring the projections thereof into line with the cut-outs, means for distributing material on the surface of said grate members, and means for removing said material after it has traveled part of a revolution of the extension with the kiln.

12. The combination with a rotary kiln having an extension at the inlet end thereof of a preheater for the materials to be fed into said kiln, said preheater including a plurality of ribs mounted on said extension and extending lengthwise thereof, each rib having a free edge provided with a flange having spaced cut-outs, a plurality of grate members mounted on the ribs and having portions resting on the flanges thereof and projections underlying said flanges, means holding the grate members against endwise movement sufficient to bring the projections thereof into line with the cut-outs, means for distributing material on the surface of said grate members, means for removing said material after it has travelled part of a revolution of the extension with the kiln, and means at the free end of the extension for preventing loss of material from the grate members through said end.

13. The combination with a rotary kiln having an extension at the inlet end thereof of a preheater for the materials to be fed into the kiln, which comprises a collector ring disposed between the end of the kiln shell and the extension and having a plurality of ports, a plurality of ribs mounted on the extension in line with the walls of said ports and extending lengthwise of the extension, the ribs having free edges provided with flanges having cut-outs, grate members spanning the spaces between adjacent ribs and having projections underlying the flanges on said ribs, means mounted on the extension for preventing endwise movement of the grate members suflicient to bring their projections into line with the cut-outs, means for distributing material on the surface of the grate members, the hot gases from the kiln flowing through the .material and members and through the spaces between the ribs to escape through said ports, and means for introducing air through the ports into the spaces between the ribs, the air flowing through the grate members todischarge the mater-ial thereon.

14. In a preheater, the combination of a plurality of ribs lying side by side and having free edges provided with flanges having cut-outs,

grate members spanning the spaces between adjacent ribs, each member including longitudinal bars having lateral projections underlying the flanges on said ribs and crossbarsv secured to the longitudinal bars and having ends resting on the flanges, and means between adjacent ribs for preventing endwise movement of the grate flanges on said ribs and crossbars secured to the longitudinal bars and having ends resting on the flanges, and key pieces mounted between adjacent ribs, the key pieces having portions engageable by the grate members to prevent endwise movement thereof sufilcient to bring their projections into line with the cut-outs.

POVL T. LINDHARD. EINAR SVENDSEN.

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