US2305272A - Heat exchange apparatus - Google Patents

Description

15, 1942. l. s. PETERsEN 2,305,272 HEAT EXCHANGE APPARATUS Filed Feb. 2e, 1942 2 'sheets-sheet 1 INVE7?LI3L` @LA ATTORNEYS L. s. PETl-:RsEN

HEAT EXCHANGE APPARATUS Dec. 15, 1942.

2 sheets-sheet 2 Filed Feb. 26;'.1942

ATTORNEY@ Patented Dec. 15, 1942 HEAT EXCHANGE APPARATUS Louis Steffen Petersen, Forest Hills, N. Y., assignor to F. L. Smidth & Co., New York, N. Y., a corporation of New Jersey Application February 26, 1942, serial No. 432,421

12 Claims.

This invention relates to heat exchange apparatus for use in heating dry pulverulent material by hot gases. More particularly, the invention'is concerned with an apparatus of the type 'referred to containing novel features, the use of which greatly reduces damage resulting from unequal expansion of the parts and insures that the material undergoing treatment will pass through the apparatus without substantial back spill or accumulation at specific points. The apparatus of the inventionrmay be advantageously incorporated in a rotary kiln for burning cement by the dry process andan embodiment of the invention for that purpose will, accordingly, be illustrated and described in detail. It will be apparent, however, that the'utility of the invention is not limited to that particular use.

In dry process cement kilns as now customarily made, it is the common practice to provide heat exchangers in the upper or inlet end of the kiln, these exchangers usually taking the form of metal crosses supported on shoes bolted to the kiln shell and defining chambers. As many as eight chambers defined by such crosses have been employed and they serve to interrupt the owing gas stream and increase its contact with the pulverulent material. The crosses are ordinarily made of castings interconnected by suitable plates which permit the castings to expand and contract Vfreely when heated and cooledin acwith respect toheat economy, but difliculties have been encountered in their use because of the buckling of the interconnecting parts. Trouble has also been experienced in the loosening of the bolts for the interconnections as a result of continuous expansion andcontraction of the parts, the loosening sometimes proceeding to the point where failure of the crosses occurs.

Another diiiiculty encountered with the present constructions is that back spill occurs at the points where the material enters' or leaves the cross system and this results in theraccumulation of material at those points. Such accumulations are likely to lead to cascading of the material with a resultant increase in the proportion of fine particles in the material and alsoY an increase in the dust loss.

The present invention is directed to the proviplurality of partitions vextending lengthwise of the kiln and secured to the kiln shell. Each partition is made up of a plurality of plates laid edge to edge in a row and the outer ends of the plates extend radially relative to the kiln while the inner ends lie at similar angles to radii. These inner ends are connected to a cylinder closed at one end, the connections allowing for considerable expansion of the plates. The cylinder is made up of comparatively thin plate so that ,itk

may undergo a degree of deformation radially without producing excessive stresses in the partition plates. Also, because of the formation of the inner ends of the plates at anglesto radii, expansion'of the plates produces a twist or rotation of the cylinder, so that expansion of the plates is not likely to cause damage to the cylinder or the connections of the plates thereto.

The partitions are formed on both surfaces with ribs which serve as flights by which material is advanced through the space between the kiln shell and the outer surface of the kiln, these ribs further stiffening the plate castings. In addition, the end plates of each partition are formed partitions and serving to advance material into the apparatus and to discharge it therefrom, respectively. The means employed for the purpose prevents back spill at the inlet and outlet ends of the apparatus and thus avoids the diiculties above mentioned.

For a better understanding oi the invention, reference may be had to the accompanying drawings in which f Fig. 1 is a longitudinal sectional view through an apparatus of the invention employed in connection with a kiln;

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

' 4 4 and 5 5, respectively, of Fig. l.

The new apparatus includes a chamber through which the hot gases and the pulverulent material pass in opposite directions and, when the invention is embodied in a kiln, the chamber is formed by a section of the kiln shell f at the inlet end of the kiln. The shell has the usual lining I I and it is mounted at a slight incline and rotated during operation in the usual way.

Within the heat exchanger section of the kiln are partitions extending lengthwise of the kiln. Six such partitions are employed in the apparatus illustrated and each partition ismade up of a plurality of cast plates I2, each having a foot I3 which is secured to the kiln shell by bolts M. From its point of attachment,l each plate extends inwardly along a radius of the kiln for most of its length and its inner end l5 is then turned to lie at an angle to a kiln radius. One of each 5 pair of adjacent plates is formed along one edge with an offset flange l5 slightly overlapping the adjacent edge of the next plate, so that the partitions are substantially continuous from end to end. lo Disposed within the inner ends of the partil tions is a cylinder Il which is made up of a number of Sections IS of thin plate lying end to end. Each section is secured to the inner ends of the partition plates in a circumferential row by bolts IB and the cylinder is of slightly less diameter than a cylinder tangent to the inner ends of the partitions at ordinary temperatures. The cylinu drical section at the inlet end of the kiln is closed by a plate 29 and each section of the cylinder is provided at one end with a ring 2| welded to the inner surface thereof and extending into the adjacent section so as to close the joints between sections. At the ends of the cylinder are circumferential flanges 22 providing support for portions of the end plates to be described.

Each plate is pro-vided on its opposite faces with ribs 23, 24 which extend at such angles as to act as flights for advancing the material through the space between the inner surface of the kiln '3oand the outer surface of the cylinder. These ribs further serve as means for stiffening the plates. The plates at the ends of the partitions diifer from the rest in including means projecting be yond the ends of the partitions and serving to advance 'material into the space between the kiln shell and the central cylinder and to discharge the material from that space, respectively. The means also serve to prevent back spill and accumulation of material at the ends of the partitions. li'0 The means referred to take the form of fianges '5 mounted along the outer edges of the end plates and each such flange has a portion 25a projecting beyond the end of the partition with which it is associated and serving the propellingllr,

function above referred to and another portion 25h preventing back spill. Each flange terminates at its inner end in a strap 25 having an end 27 which straddles the edge of flange 22, this arrangement being employed to strengthen and reinforce the flanges.

In the operation of the apparatus as used in the kiln, the material advancing down the kiln during the rotation of the latter is engaged by the flanges Z5 at the inlet end of the apparaus and advanced thereby into the space between the shell and the central cylinder il'. The material is advanced through the space outside the cylinder by the action of the ribs 23, Ed and, when it reaches the discharge end of the apparatus, the 50 material is propelled therefrom by flanges 25 mounted on the partitions and appropriately formed for the purpose.

rhe hot gases from the kiln flow through the space between the kiln shell and the central 55 cylinder and heat the pulverulent material in the usual way. Temperature variations in the hot gases result in expansion and contraction of the partition plates andgas these plates expand, their inner ends tend to move inward toward the cylinder and also somewhat tangentially thereof. lnitial expansion of the' plates results in the inner ends of the plates contacting with the cylinder and, thereafter, further expansion Iof the plates Vresults in twisting or rotation of the-cylinder to T5 a slight extent and also flexing of the cylinder. Upon lowering of the temperature with resultant contraction of the plates, the actions occurring are the reverse of those described. Since accumulation of material at the inlet and outlet ends of the apparatus is avoided, cascading is substantially prevented and an increase in the amount of dust and in the dust loss is consequently avoided.

In the specific construction described, the heat exchanger of the invention is incorporated in a rotary kiln, ut it will be apparent that the invention `1nayif desired, be utilized in the form of aseparate piece of equipment to which the material to be heated and the'heating medium are supplied.

I claim:

1. A-heat 'exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the wall of the chamber, the partitions being of less length than the cylindrical chamber and having their inner ends at an angle toradii of the chamber, a closed cylinder secured to the'inn'er Yends of the partitions and lying concentrically with the chamber,

means on similar faces of the partitions for advancing material lengthwise of the' chamber, and means at the inlet and outlet ends of the partitions and extending1 beyond said ends for advancing'ma'terial from that part of the chamber'adjacent the inlet ends of the partitions into the space between the chamber and cylinder and for propelling material out of said space into the part o-f the chamber adjacent the outlet ends of the partitions, respectively.

2. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the wall of the chamber, the' partitions being of less length than the cylindrical chamber and having their inner ends at an angle to radii of the chamber, a closed cylinder secured to the inner ends of the partitions and lying concentrically with the chamber, means on similar faces of the partitions for advancing material lengthwise of the chamber, and means at the inlet and outlet ends of the partitions and extending beyond said ends for advancing material from that part of the chamber adjacent the inlet ends of the partitions into the space between the chamber and cylinder and for propelling material out of said` space into that part of the chamber adjacent the outlet ends of the partitions, respectively, said means also preventing back spill and accumulation of the material at said ends.

3. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the wall of the chamber, the partitions being of less length than the cylindrical chamber and having their inner ends at an angle to radii of the chamber, means on similar faces of the partitions for advancing material'lengthwise of the chamber, and flanges on the partitions at the inlet and outlet ends thereof adjacent the chamber wall and extending beyond said ends at an angle to the plane of the i partitions for advancing material from that part of the chamber adjacent the'inlet ends of the partitions into the space between the 'chamber and cylinder and for propelling material out of said space into that part of the chamber adjacent the outlet ends of the partitions, respectively.

e. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row length- Wise of the chamber, the inner ends of the plates lying at similar angles to' radii of the chamber, a closed lcylinder lying vconcentrically with the chamber and made up of a plurality of unitary sections placed end to end and secured to the inner ends of said plates, and means on similar faces of the plates for advancing material lengthwise of the chamber.

5. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the Wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the chamber, the inner ends of the plates lying at similar angles to radii of the chamber, a closed cylinder lying concentrically with the chamber and made up of a plurality of unitary sections placed end to end, each section being secured to the inner ends of a circumferential row of plates, means closing the joints between adjacent sections of the cylinder, and means on similar faces of the plates for advancing material lengthwise of the chamber.

6. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly eX- tending partitions secured to the wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the chamber and being of less length than the chamber, the inner ends of the plates lying at similar angles to radii of the chamber, a closed cylinder lying concentrically with the chamber and secured to the inner ends of the plates, means on similar faces of the plates for advancing material lengthwise of the chamber, and means at the inlet and outlet ends of the partitions and extending beyond said ends for advancing material from that part of the chamber adjacent the inlet ends of the partitions into the space between the chamber and cylinder and for propelling material out of said space into that part of the chamber adjacent the outlet ends of the partitions, respectively.

7. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the Wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the chamber and being of less length than the chamber, the inner ends of the plates lying at similar angles to radii of the chamber, a closed cylinder secured to the inner ends of the plates and lying concentrically with the chamber, ribs on similar faces of the plates for advancing material lengthwise of the cylinder, and flanges secured to the plates at the inlet and outlet ends of the partitions and extending beyond said ends for advancing material from that part of the chamber adjacent the i'nlet ends of the partitions into the space between the chamber and cylinder and for propelling material out of said space into that part of the chamber adjacent the outlet ends of the partitions, respectively.

3. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to the wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the chamber and being of less length than the chamber, the inner ends of the plates lying at similar angles to radii of the chamber, a closed part of the chamber adjacent the outlet ends of the partitions, respectively, said means also preventing back spill and accumulation of the material at said ends.

9. A heat exchanger which comprises a rotary cylindrical chamber, a plurality of inwardly extending partitions secured to theY wall of the chamber, each partition being made up of a plurality of plates lying edge to edge in a row length- Wise of the chamber and being of less length than the chamber, said plates having plane portions adjacent the wall of the chamber and inner ends at similar angles to radii of the chamber, a closed cylinder secured to the inner ends of the plates and lying concentrically With the chamber, ribs on similar faces of the plates for advancing material lengthwise of the chamber, and flanges secured to the plates at the inlet and outlet ends of the partitions adjacent the chamber wall andr extending beyond said ends, said flanges lying at an angle to the plane of the plates on which they are mounted and acting to advance material from that part of the chamber adjacent the inlet ends of the partitions into the space between the chamber and cylinder and to propel material out of said space into that part of the chamber adjacent the outlet ends of the partitions, respectively.

l0. A rotary kiln having a heat exchanger section at one end containing a plurality of inwardly extending partitions secured to the shell of the kiln, the partitions having their inner ends lying at an angle to radii of the kiln, a closed cylinder secured to the inner ends of the partitions and lying concentrically with the kiln, means on similar faces of the partitions for advancing material lengthwise of the kiln, and means at the inlet and outlet ends of the partitions for extending beyond said ends and advancing material from that part of the kiln adjacent the inlet ends of the partitions into the space between the inner wall of the kiln and the cylinder and for propelling material out of said space into that part of the kiln adjacent the outlet ends of the partition, respectively.

11. A rotary kiln having a heat exchanger section at one end containing a plurality of inwardly extending partitions secured to the wall of the kiln, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the kiln, the inner ends of the plates lying at similar angles to radii of the kiln, a closed cylinder lying concentrically with the kiln and made up of a plurality of unitary sections placed end to end, each section being secured to the inner ends of plates in a circumferential row around the kiln, means closing the joints between adjacent sections of the cylinder, and means on similar faces of the plates for advancing material lengthwise of the kiln outside the cylinder secured zto the inner ends of the plates cylinder.

k12. A rotary kiln having a heat exchanger section at one end containing a plurality of inwardly extending partitions secured to the Wall of the kiln, each partition being made up of a plurality of plates lying edge to edge in a row lengthwise of the kiln, the inner ends of. the plates lyingl at similar angles to radii of the kiln, a closed cylin der lying concentrically with the kiln and made up-o-f a plurality of sections each secured to the inner ends of plates in a circumferential `row around the kiln, means closing the joints between adjacent sections of the cylinder, means on similar faces of the plates for advancing material lengthwise of the kiln outside the cylinder, and

Y tions into the space between the cylinder and the kiln shell and for propellingmaterial out of said space into that part of the kiln adjacent the outlet end of the partitions, respectively.

LOUIS STEFFEN PETERSEN.

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