US2275117A - Process and apparatus for preheating or drying slurry - Google Patents

Description

M. VOGEL-JORGENSEN 2,275,117 PROCESS AND APPARATUS FOR PREHEATING OR DRYING SLURRY March 3, 1942.

2 Sheets-Sheet 1 Filed July 22, 1939 M. VOGEL-JORGENSEN 2,275,117

March 3, 1942.

PROCESS AND APPARATUS FOR PREHEATING OR DRYING SLURRY 2 Sheets-Sheet 2 Filed July 22, 1939 III/A Patented Mar. 3, 1942 PROCESS AND APPARATUS FOR PREHEAT- ING OR. DRYING SLURRY Mikael Vogel Jorgensen,

Copenhagen, Denmark,

& 00., New York, N.

Jersey Frederiksberg, near assignor to F. L. Smidth Y., a corporation of New Application July 22, 1939, Serial No. 286,020

In Great Britain July 27, 1938 14 Claims.

This invention relates to the preheating or preheating and drying of slurry by a process in which the slurry, such as raw slurry for cement making, is spread over a mass or charge of relatively movable bodies through which hot gases pass. In the case of raw cement slurry which is later burnt in a rotary kiln, these gases are usually the exhaust gases from the kiln. By the term preheating I mean here and in the following description and claims the preheating which takes place prior to or simultaneously with, but not after the drying.

According to the invention, a mass or charge of relatively movable bodies is placed in one or more compartments formed between parallel perforated walls forming part of a structure that rotates as a whole, and the gases are caused to pass through the compartment or compartments but are prevented from bypassing the mass or bodies by making imperforate or screening those parts of the walls which are left clear of bodies as a result of the movement of the mass during the rotation of the structure. In other words, the walls are penetrated by the gases only over those parts that are at a given moment covered by the mass or bodies.

In the apparatus according to the invention, the space between the parallel walls is divided into sector-shaped compartments with imperforate radial partitions and a mass or charge of relatively movable bodies is placed in each compartment almost filling it.

Preferably, the structure is made part of a rotary kiln and the walls referred to above are in this case arranged transversely across the kiln; they may advantageously be placed in a widened zone of the inlet end of the kiln. The walls should be placed close together in comparison with the diameter of the kiln.

Other advantages and peculiarities of the invention will become apparent from the ensuing description taken in conjunction with the accompanying drawings which are given solely by way of example and in which:

Fig. 1 is a diagrammatical cross-section of the apparatus according to the invention, taken along the line A-B of Fig. 2.

Fig. 2 is a diagrammatical longitudinal section of said apparatus, taken along the line A'B of Fig. 1.

Fig. 2a is an enlarged sectional view oi a detail of the construction.

Fig. 3 shows a diagrammatical cross-section of amodificatlon of said apparatus, taken along the line C-Doi Fig. 4. I

fined by the tube 1, and at their outer ends they are enlarged by pockets 9 which extend outwardly beyond the kiln shell 8. Each pocket 9 consists of a casing l8 surrounding an opening 24 in the kiln shell and the casing is closed at the outer end by a plate I 9. The tube 1 is covered at the front end by a plate 22 which prevents the gases from passing through said tube. moving plate '22 when the kiln is not in tube I may serve as a manhole in case repairs are to be made in the kiln. In order to prevent the compartments from offering too much resistance to the flow of hot gases, the part of the kiln containing the compartments is made somewhat larger than is usual at the inlet end of a normal kiln, and a conical section 3 is therefore provided to connect the widened zone with the next zone further down the kiln.

In each compartment 2 there is placed a mass or charge of relatively movable bodies l0 and these charges are indicated in the drawings. It will be seen that each charge nearly fillsits compartment. At any given instant, the bodies in each upper compartment leave an empty space above them and also in each lower compartment leave an empty space near the axis of rotation. Each time one ofthe compartments passes through its horizontal position, the whole charge in it will slide outwardly or inwardly, as the case may be, and the sliding movement will be the more violent the less the charge in the compartment.

The slurry is delivered into the inlet end of the kiln through a pipe l2 and forms-a pool at the bottom of the kiln, as shown at I5. Said slurry By reuse, the

passes through the wall 4 on tothe bodies l0, and

while it is spread on them is preheated and dried to a greater or lesser extent by the hot gases from the kiln which pass in succession through the wall 5, the charge of bodies l0 and the wall 4. In order to allow the slurry and gases to pass in this manner, the walls 4 and 5 are provided with annularly positioned openings 23 partly screened by bars 20 welded to the sector-shaped plates. The openings 23 leave an imperforate annular central portion bounded by their inner edge I I and an imperforate outer portion bounded by their outer edge 25. At every stage during the operation the parts that are left uncovered by the relatively movable bodies are those at which the walls 4 and 5 are imperforate. In other words, the hot gases can only pass through the openings 23 in the walls 4 and 5 between the circular edges H and 25 and those annular parts are always covered by the bodies.

In practice it is found that there is a tendency for a cavity to form in the middle of each compartment,'andgases may flow through these eavities without passing over the slurry. In order to prevent this, the middle of each compartment is occupied by an impermeable member comprising a tube 16 which is formed so as to facilitate the sliding of the charge and is closed at its ends by plates l4 that are welded to said tube. Two uprights M are welded to the plates l4. As best shown in Fig. 2a, the uprights 2i project between.

the. two middle bars 20 in each compartment and are fixed to said bars by bolts passing through said bars and uprights. as indicated in the drawing.

In operation, the slurry is distributed over the bodies automatically as the kiln rotates and is preheated and more or less dried by the gases flowing up the kiln, as described. After this treatment it leaves the bodies partly as a result of their relative movement, particularly when one individual mass or charge slides as a whole from the inner to the outer end of the compartment or vice versa. The slurry passes next through the wall 5 and is conveyed through the conical section 3 by conveyor flights l3 projecting from said wall and then passes outwards down the kiln as usual.

It is obvious that the greater the difference in the slurry level before and after the compartments, the quicker the slurry will move through said compartments. If the slurry passes through them quickly, it will not be dried to a solid consistency therein, but will still be fluid when it leaves them. If quick flow is desired, the kiln may have a larger diameter after the compartmerits than in front of them, so that in the lower part of the kiln, the slurry level is higher before the compartments than after same. Thus the outer diameter of the compartments, taken at the ends of the pockets when these are provided, may be larger than that-of the kiln shell, and at the discharge side of the compartments, the kiln shell may be conical until the normal diameter is reached. This feature is shown in the mediflcations according to Figs. 3v and 4. If. however, slow flow of the slurry is desired, the diameter of the kiln below the compartments may be the same as that above them, as in Fig. 2. In any case, since as stated above the compartments should not offer too much resistance to the flow of the hot gases, the part of the kiln containing the compartments should be rather larger than is usual at the inlet end of a normal kiln.

The preheating or drying structure may be made independent of the kiln if desired, and arranged in front of the inlet end of the kiln to rotate independently and act as a separate preheating or drying drum.

While Ihave illustrated and described the preferred form of construction for carrying my ln-.

vention into efleet, this is capable of variation and modification, without departing from the spirit of theinvention. I therefore do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the appended claims.

I claim:

l. A process for treating slurry which comprises maintaining a mass of relatively movable bodies, rotating said mass of bodies in a vertical plane at a speed such that the bodies move relative to one another during such rotation, spreading slurry over said mass of bodies as it rotates, and passing gases through the rotating mass of bodies over which the slurry has been spread in a direction transverse to that in which the mass of bodies is rotating.

2. A process for treating slurry which comprises maintaining a series of masses of relatively movable bodies in vertical annular arrangement, rotating said series of masses of bodies in a vertical plane at a speed such that the bodies move relative to one another during such rotation, spreading slurry over said masses of bodies as they rotate, and passing gases through the rotating masses of bodies over which the slurry has been spread in a direction transverse to that in which the masses of. bodies are rotating.

3. A process for treating slurry which comprises maintaining a series of masses of relatively movable bodies in vertical arrangement with each mass being in a separate compartment, rotating said series of masses of bodies in a vertical plane at a speed such that the bodies move relative to one another during such rotation, spreading slurry over said masses of bodies as they rotate, the masses of bodies being insufiicient to fill their respective compartments whereby the masses of bodies with the slurry spread over them substantially constantly shift their position during rotation of said masses, and passing gases through the rotating masses of bodies over which the slurry has been spread in a direction transverse to that in which the masses of bodies are rotating.

4. A process for the heat treatment of slurry which comprises maintaining a series of masses of relatively movable bodies in vertical arrangement with each mass being in a separate compartment, rotating said series of masses of bodies in a vertical plane, substantially continuously introducing slurry into said series of masses of bodies and successively to said individual masses as the series rotates, with resultant spreading of the slurry over the bodies of the several masses, the masses of the bodies being insufliclent to fill their respective compartments whereby the masses of bodies with the slurry spread over them substantially constantly shift their position during rotation, passing heated gases through the rotating masses of bodies over which the slurry has been spread in a direction transverse to that in which the masses of bodies are rotating, and substantially continuously removing slurry over which said heated gases have passed from said masses of bodies.

Q 5. A process for heat treatment of slurry as set the compartment through the opening in one of the walls of said pair of walls and leaving through the opening in the other wall of said pair of walls, the size of the mass of bodies in said compartment being such that at least a part of the gas stream entering the compartment passes through said mass of bodies.

7. Apparatus for heat treatment of slurry which comprises a plurality of compartments arranged in a circular series and rotatable about the axis of the series, each compartment including a pair of walls extending transversely through said axis, each of said walls having an opening, a mass of relatively movable bodies in each compartment, means for confining the mass of bodies in each compartment for rotation therewith, means for introducing slurry into the compartments through the openings in corresponding walls thereof, the slurry leaving through the openings in the other walls, and means for passing hot gases through the compartments, the gases entering each compartment through an opening in one wall and leaving through the opening of the other, and the size of the mass of bodies in each compartment being such that a substantial part of the gas stream flowing through the compartment passes through the mass of bodies therein.

8. Apparatus for heat treatment of slurry which comprises a plurality of compartments arranged in a circular series and rotatable about an axis of the series, each compartment including a pair of imperforate substantially radially extending walls, a pair of side walls each in a plane extending transversely through said axis and each of which has an opening therein, and an outer imperforate wall, a mass of relatively movable bodies in each compartment, means for confining the mass of bodies in each compartment for rotation therewith, means for introducing slurry into each compartment through the opening in one of said side walls, the slurry leaving through the opening in the other of said side walls, and means for passing hot gases through the compartments, the gases entering' each compartment through the opening in one of said side walls and leaving through the opening in the other of said side walls, the size of the mass of bodies in each compartment being insufficient to fill it but such that a substantial part of the gas stream flowing through the compartment passes through the mass of bodies therein.

9. A rotary kiln for burning cement and the like having an inlet section at one end thereof and a preheating or drying section adjacent said inlet section and inwardly thereof, said preheating or drying section comprising a pair of side walls each of which lies in a plane extending transversely to the axis of the kiln, each of said side walls having a series of annularly positioned openings, imperforate radial partitions dividing generallysector-shaped compartments, at least one opening in each of said side walls leading into each compartment, a pocket at the outer end of each compartment projecting outwardly from the kiln shell and having imperforate walls, a mass of relatively movable bodies partly filling each compartment, means for introducing slurry into the compartments through theopenings in one of said side walls, the slurry leaving through the openings in the other of said side walls, the openings in said side walls providing the only means of egress for at least the major portion of the hot kiln gases whereby said gases enter each compartment through an opening in one side wall and leave through the opening in the other side wall, the size of the mass of bodies in each compartment being such that a substantial part of the gas stream flowing through the compartment passes through the massof bodies therein.

10. A rotary kiln for burning cement and the like having an inlet section at one end thereof, a preheating or drying section adjacent said inlet section and inwardly thereof, said preheating or drying section comprising a pair of side Walls each of which lies-in a planeextending transversely to the axis of the kiln, each of said side walls having a series of annularly positioned openings, imperforate radial partitions dividing the space between said walls into a plurality of the space between said walls into a plurality of generally sector-shaped compartments, at least one opening in each of said side walls leading into each compartment, a pocket at the outer end of each compartment projecting outwardly of said inlet section, and having imperforate walls, the portion of the kiln inwardly of the preheating or drying section and adjacent thereto extending outwardly to the periphery of said pockets, whereby the lower portion of that part of the kiln is in a plane below the plane of the lower part of the inlet section, a mass of relatively movable bodies partly filling each compartment, means for introducing slurry into-the compartments through the openings in one of said side walls, the slurry leaving through the openings in the other of said side walls, the openings in said side walls providing the only means of egress for at least the major portion of the hot kiln gases whereby said gases enter each compartment through an opening in one side wall and leave through the opening in the other side wall, the size of the mass of bodies in each compartment being such that a substantial part of the gas stream flowing through the compartment passes through the mass of bodies therein.

11. A rotary kiln for burning cement and the like having an inlet section at one end thereof, a preheating or drying section adjacent said inlet section and inwardly thereof said preheating or drying section comprising a pair of substantially parallel side walls extending transversely across the kiln adjacent said inlet, each of said side walls having a series of annularly positioned openings, screening means extending across said openings, imperforate radial partitions between said side walls and between openings of said series of annularly positioned openings, said partitions dividing the space between the side walls into a plurality of generally sector-shaped compartments having openings on opposite sides thereof, the defining edges of the openings in said side walls being spaced from said partitions from the outer edge of the side walls and from the inner defining wall of the compartments, a

pocket at the outer end of each compartment, said pockets projecting outwardly from the kiln shell and having an imperforate end wall, a mass of relatively movable bodies in each compartment, means for introducing slurry into the compartments through the openings in one of said side walls, the slurry after spreading over said masses of bodies leaving through the openings in the other of said side walls, said masses of bedies being insuflicient to fill the compartments but being sufilcient that the level thereof is above the upper level of said openings regardless of the angular position thereof, whereby-the stream of kiln gases in passing through said preheating or drying compartment must pass through said masses of bodies.

12. A rotary kiln for burning cement and the like as set forth in claim 11, in which each compartment has means therein for preventing the formation of a central cavity in the mass of bodies therein as said bodies shift during rotation of inlet section and inwardly thereof, said preheating or drying section comprising a pair of substantially parallel side walls extending transversely across the kiln, each of said side walls having a series of annularly positioned openings, imperiorate radial partitions dividing the space between said-side walls into a plurality of generally sector-shaped compartments, at least one opening in each of said side walls leading into each compartment, a pocket at the outer end of each compartment projecting outwardly from said inlet section and having imperforate walls, a mass of relatively movable'bodies partly filling each compartment, means for introducing slurry into the compartments through the openings in one of said side walls, the slurry leaving through the opening in the other of said side walls, the openings in said side walls providing the only means of egress for at least the major portion of the hot kiln gases whereby said gases enter each compartment through an opening in one side wall and leave through the opening in the other. side wall, the size ofthe mass of bodies in each.

compartment being insufilcient to completely fill the compartment but being such that a substantial part of the gas stream from the kiln passes through the mass of bodies therein, imperforate means in each compartment for preventing the formation of a central cavity in the charge of loose bodies therein as said bodies shift during rotation of the kiln, said kiln having an inwardly converging conical section adjacent and inwardly of said preheating or drying section, the outer part of said conical section extending out.- wardly to the periphery of said pockets, whereby the-lower portion of the conical section adjacent the preheating or drying section is in a plane below the plane of the lower part of the inlet section, thereby to increase the speed of flow of the slurry through said compartments, and conveyor flights carried by saidconical section to advance the slurry inwardly along the conical section as the kiln rotates.

14. A rotary kiln for burning cement and the like having an inlet section at one end thereof and a preheating or drying section adjacent said inlet section and inwardly thereof, said preheating or drying section comprising a pair of side walls each of which lies in a plane extending transversely to the axis of the kiln, each of said side walls having a series of annularly positioned openings, imperforate radial partitions dividing the space between said walls into a plurality of generally sector-shaped compartments, at least one opening in each of said side walls leading into each compartment, a mass of relatively movable bodies confined in and partly filling each compartment, means for introducing slurry into the compartments through the openings in one of said side walls, the slurry leaving through the openings in the other of said side walls, the openings in said side walls providing the only means of egress for at least the major portion of the hot kiln gases whereby said gases enter each compartment through an opening in one side wall and leave through the opening in the other side wall, the size of the mass of bodies in each compartment being such that a substantial part of the gas stream flowing through the compart ,ment passes through the mass of bodies therein.

MIKAEL VOGEL-JORGENSEN.

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