CH655785A5 - Rotary oven intended for manufacturing plaster - Google Patents

Description

The present invention relates to a rotary kiln for the manufacture of plasters.

There are various commercial forms of plaster, which are obtained from raw plaster by means of an appropriate baking process.

Until recently, the use of plaster consisted exclusively of its direct application to walls and ceilings, apart, of course, from artisanal applications, of insignificant quantitative importance. However, appropriate experiments have highlighted remarkable advantages presented by the use of plaster in other construction applications, such as: prefabricated elements for partitions and false ceilings decorated or smooth. However, these plasters do not all contain the same degree of humidity, so that, in each case, cooking must be carried out at the appropriate temperature to allow obtaining semi-hydrated plasters and anhydrite plasters in the proportions suitable for obtaining a product with the precise characteristics desired, such as setting time, hardness and resistance, and other characteristics suitable for the intended application.

In order to be able to meet this growing demand for different varieties of plaster, manufacturers are frequently obliged, with the use of conventional baking ovens, to provide for independent manufacturing cycles, at different temperatures, and this in using quite primitive processes, without effective possibilities of quantitative and qualitative control.

The present invention relates to a rotary kiln intended for the manufacture of plasters offering the great advantage, thanks to its structure and its functional possibilities, of making it possible to obtain, during a single and same manufacturing cycle, and to from the same raw material being treated, plasters of different categories, in particular, semi-hydrated plasters and anhydrite plasters, in easily adjustable proportions.

This oven is of the type of ovens constituted by a large rotary cylindrical tubular body closed at one of its ends corresponding to its rear end, and coaxially integral with another external cylindrical tubular body of lesser length which extends over most of it. of the

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central scope of the large inner tubular body delimi- in the fact that, slightly in front of the front end of both between the two bodies, an annular chamber intermediate external cylindrical tubular body, are provided in the diary which, at its front end, is in communication with internal cylindrical tubular body, several openings with a material inlet hopper and, at its outgoing end, preferably eight in number, provided with rear flaps, is in communication with the interior body articulated freely, able to open and close successively-

inner cylindrical tubular by means of passages; said ment, by pivoting under the effect of gravity, during rotation

furnace further comprising ribs, fins, helices tion of the tubular body, said outlet openings, ampli-

and blades arranged inside said adjustable annulus chamber, opening inside a hopper of said air and said inner body and on the path of the unloading material intended for the reception of the so-called “semi-plaster”.

treat, outlet openings for the treated material, hydrated io ”. This is the plaster used for the prefabricated panels.

burner, a burner carriage, a hearth, brick means used in the construction of partitions, supports and rotary drive means. As decorated or smooth false ceilings, and in other applications indicated above, this type of oven is specially industrial. The oven according to the invention is further characterized

tiné to allow obtaining, during a continuous process by the fact that the movable part of the hearth, to which the cooking material, of the two basic types of plasters that are is is not previously evacuated by the first openings of the plaster semihydrate and anhydrite plaster, with their exit, reaches, by suitable passages, preferably by various variants. An essential characteristic of the two-passage oven located in succession and close to said openings

according to the invention resides in the fact that its hearth is executed at the outlet tures of the semi-hydrated plaster, has a wall in two parts, that is to say: interior covered with refractory material and of shape

,, _ .. r. ,. i,. . , 20 approximately conical with increasing diameter of the ar

- on the one hand, a fixed part in which the .. „is installed. .not , , , . ,, burner- and nere Vers avant'at least in the region of the said passages, the

,, '. '. ... ..., „, oven also being characterized in that the front edge

- on the other hand, a mobile part consisting of 1 one of, ... _ .. ...

... , i • î- of the same movable part delimited or comprises 1 opening end portions or front portion of the tubular body cylin-, _ j _ * •, ... ...

j. . . . yc or the outlet openings for plaster called "anhydrite",

dnque rotary switch; ,.,,,,. ^

J 2s whose suitable degree of cooking has been precisely reached the open ends or mouths of the two parts ali- in said movable part of the hearth where it receives more intense

axially constrained by said hearth, being placed opposite one of the heat effects of the burner, said opening or the other. said openings opening into a discharge hopper

A very great advantage which this mode of execution provides, appropriately.

follows from the fact that the total weight of the mobile assembly of the 3 ”Finally, the oven intended for the manufacture of plaster plaster is much smaller than that of the continuous batch assembly according to the invention, also present as nant rotary ovens known to date, which is based on a notable characteristic the fact that the crown which, direct-a compact and unitary structure encompassing the entire frame or indirectly, receives the motor movement of a hearth. suitable motor, is located around and near

The furnace is also characterized in that the hopper at the rear end of the inner cylindrical tubular body,

loading gives access to a plurality of inlet openings, The plaster intended to be used for direct application in provided exactly at the front end of the tubular body a work, or in walls and ceilings, is obtained external cylindrical, these inlet openings being, preferably by mixing in appropriate quantities of semi-hydrated plaster

rence, six in number and distributed in the previously mentioned circular alignment and plaster called anhydrite.

laire, so that their receptacles are arranged in a case 40 In the accompanying drawings, there is illustrated, by way of simple box. This avoids, to a very large extent, that a non-limiting example of embodiment, a rotary oven intended for

consequent amount of material poured into the tank hopper, the manufacture of plasters, according to the present invention.

It does not fall out of the oven due to waterlogging. . . ,.,,. •. j. ,

„,,. ,. ° ^ Figure 1 is a side view in longitudinal section,

According to the antenna technique, the means allowing,. . . , „. . 1 ... -i j «■ ■

,,. -. .., .li * „j r * divided into two parts to show the details of the oven

1 support and the rotation of the rotary assemblies of the ovens are 45,,. ,,. . _. ,. . . ._. ,,

...,, -, larger scale; the line A-B indicates the virtual plane of constituted by rolling rings resting on, ... ,, ...,. ,

, T r. . . , „. ..,.,, separation between the two halves: left half (illustrated rolls. A characteristic aspect of the invention resided in,,,...,,,,.,.

, e v 1 j 1 *> •,, at the top of the drawing board) and half

the fact that said rolling rings are placed around the,, .. ..... f,,,. ,,,

/,,. , ■, • ..... , on the right (illustrated in the lower part of the plate of cylindrical interlayer tabular body, near its front and rear ends, and, more precisely, in its 50, „..,... TT TT

_. ,. . . ., Figure 2 is a cross section along the line II-II

areas not covered by the outer cylindrical tubular body. Note that, preferably, the set formed by T J * J. . . . ,.

, , .Have- . •. •. .., Figure 3 is a cross section along the line the two tubular integral and coaxial bodies is has TTT TTT, r-,

• j •• * j 1. j j III-III of figure 1.

on its supports so as to present a slope of 1 order of, „. . ,, ...

1 in / - j j a i <- - •. ' ^ ^ Figure 4 is a cross section along the line IV-IV

1.5% descending from the front end to the back end. 55,,. 0

According to another characteristic of the oven according to the invention, the. I . *, • tl ,,

c „,, f 1. ,. • i .. 'Figure 5 is a cross section along the line V-V

internal surface of internal cylindrical tabular body is .1,1- <

from 13. fisurê 1

provided with blades in the form of sections of T? '.r. „. .., „

. , / I. •,. , j, »The rotary oven according to the invention is essentially composed

short length and all clustered in the same direction, these, .vi- ... . ,. ,

,,. f ... 1-L .., j,,. ment of a large rotating cylindrical tabular body 1

blades being arranged alternately, in the trans-60 direction. . ... r,,, „,

r ", j- provided, near its ends 1a and 1b, with dorsal rings, and forming straight alignments, in the direction -,,„. ,

. ..,. . ,. . -. bearing, respectively 2 and 2 ', supported on wheels

longitudinal section, a continuous fin also extending, n,,

,, j. . .. j. ,. . ... 0. respective waters 3 and 3 '. LJne toothed crown 4, located practi-

in the longitudinal direction between said alignments /, „. . ..... . ..., .. ,,

j, ti .. 1 •. * at the very end of the body 1, receives 1 action from a motorbike

contiguous blades. It is understood that the oven includes. ,. . „. . ,,, •> .-

, j *,., ^, ', •,,. ... ,, suitable gearbox (not shown in the drawings) supplied-

in addition to other fins, hehees blades and similar means of 6s,. ,. , ...

^. sant the driving force for the rotational movement of said current type thrust and known in the art .li- i- j • iax j ^ 1. 1 •

, cylindrical tabular body 1. Around this relevant tabular body

* t ',. •. • Ac 1 n-. ■. -, cylindrical 1, is mounted integrally and coaxially a

Another characteristic of the oven according to 1 invention resided n

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another cylindrical tubular body 5, of shorter length, which covers most of the central range of said cylindrical tubular body 1, up to the proximity of the rolling rings 2 and 2 '. Between the two tubular bodies 1 and 5, an intermediate annular chamber 6 is delimited, to which the raw plaster first accesses when it enters the furnace, by inlet openings 7 formed at one of the ends or end front of said annular chamber. The rear end 5a of the outer tubular body 5, is completely closed off by a wall 8, and has a plurality of passages 9 which put it in communication with the interior 10 of the inner tubular body 1 which delimits a cooking chamber, the rear end is also closed by means of a cover 11.

Particularly noteworthy is the fact that the hearth 12 is composed of two parts: a mobile part 12a and a fixed part 12b. The movable part 12a is established inside the portion 13 of the tubular body 1, substantially comprised between the end 1b of this body opposite its closed end 1a, and the front end 5b of the outer tubular body 5. fixed part 12b which is the heaviest part and of larger dimensions, is located opposite the mobile part 12a, and the adjacent ends or mouths, respectively 15 and 14, of said fixed and mobile parts are axially aligned and have a practically equal diameter. In the extreme rear end of the fixed body 12b is installed the burner 16 mounted on a burner carriage 16 '.

This arrangement is very important because it makes it possible to reduce the weight on the bearing rings 2 and 2 ', in particular as regards the ring closest to the burner (the ring 2' according to the example illustrated); this ring, in other known embodiments, having to support the load represented by the oven and the whole hearth.

Also constitutes, a particularly remarkable feature of the invention, the fact that the chamber 6 has several inlet ports 7, as indicated above. Preferably, there are provided six inlet openings 7 distributed in circular alignment, which has the advantage that in case, due to the automatic charging process, the receptacle 17 of one of these openings overflows , the excess material falls into the next mouth, thanks to the cascade arrangement of these mouths, which eliminates the long recovery cycle specific to traditional ovens, in which the raw material which overflows during the charging process comes back to the outside the oven, requiring a new transport, with the use of auxiliary means, to the entrance of the single mouth.

The exit of the baked plaster takes place through exit openings 18 and 19, according to another important characteristic of the invention.

Indeed, the outlet openings 18 are located in the inner tubular body 1, at a reduced distance from its end 1b, immediately before access to the movable part 12a of the hearth 12 and strictly after the outer tubular body 5 which does not cover them not. Preferably, eight outlet openings 18 are regularly provided on the cylindrical or peripheral surface of said body 1. These openings open inside an unloading hopper 20. According to FIG. 2, which is a cross section along the plane II — II which cuts the area of the outlet openings 18, it is noted that the latter are furthermore equipped with freely articulated flaps 21 which open and close successively by pivoting under the effect of gravity, during the rotation of the body tubular 1. In addition, the openings 18 are of adjustable amplitude by means of sliding doors 18 '. Regarding the outlet opening 19, which is located exactly in the open area 14 of the inner tubular body 1, and, more precisely, in the area of its connection with the mouth 15 of the fixed part 12b of the hearth, said opening can typically be entirely a single opening, as in the example illustrated or structured in the form of a poly-opening or multiple openings distributed peripherally near the front edge 14 of the movable part 12a of the hearth 12, similarly to the openings 18 previously described. The outlet opening (s) 19 also open (s) into an unloading hopper 22, making it possible to easily collect the cooked material from the cooking process.

The assembly formed by the two coaxial cylindrical tubular bodies 1 and 5 is preferably arranged so as to have an inclination of the order of 1.5% which descends from the front end where the burner 16 is installed up to 'at the opposite rear end. This arrangement favors the advance of the material which has just been introduced into the furnace through the inlet openings 7, when this material must first of all move towards the rear end, by traversing the chamber 6. We note, in this chamber 6 the presence of inclined longitudinal fins 23 integral with the inner face of the outer tubular body 5, and which extend from the proximity of the inlet openings 7 mentioned above to near the rear end 5a where find the passages 9 which put the chamber 6 in communication with the interior 10 of the interior tubular body 1. FIG. 3, which is a section along the line III-III of FIG. 1, conventionally limited to the exterior cylindrical tubular body 5, shows the shape and arrangement of said inclined longitudinal fins 23.

Bifid fins 24 also extend into the chamber 6, in the longitudinal direction of the latter. These longitudinal fins are integral with the outer face of the inner cylindrical tubular body 1, and cooperate with the inclined longitudinal fins 23 mentioned above.

Another characteristic arrangement of the furnace according to the invention is located inside the internal cylindrical tubular body 1 and consists of the special arrangement of blades 25 in the form of a short section and all inclined in the same direction. These blades are arranged alternately, in the transverse direction, and form rectilinear alignments, in the longitudinal direction. A continuous fin 26 also extending in the longitudinal direction of the body 1, is disposed between the contiguous alignments of blades 25 above. These blades and fins make it possible to ensure that the material being treated remains in the oven for the necessary period of time, when after having passed through the passages 9, said material continues its path inside the oven, by circulation inside the tubular body 1, towards the front end of said body to reach the outlet openings. This arrangement of the blades

25, combined with that of the continuous longitudinal fins

26, is indeed very effective in slowing the advance of the material towards the outlet openings 18 and / or 19, with the result that the degree of firing achieved is always that provided for obtaining plaster of the previously desired type. Figure 4, which is a cross section along line IV-IV of Figure 1, relating exclusively and in a conventional manner the inner tubular body 1, also allows to see the shape and arrangement of the bifid fins 24, blades 25 and continuous longitudinal fins 26.

It is also reported, as elements promoting the cooking process and, more particularly, the advance of the material being processed, the presence of helical fins 27 rigorously arranged in an alternate position with the passages 9. These fins 27 have for the role of efficiently routing the plaster towards the front of the interior body 1,

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at the moment when the circulation of said plaster coming from chamber 6 is reversed, so as to direct it towards the hearth 12.

Figure 5 is a cross section along the line V-V of Figure 1, which illustrates the passages 9 above.

In the connection zone between the interior 10 of the interior tubular body 1 and the movable part 12a of the sight glass, there are passages 28 for access to the hearth 12, preferably two in number and arranged in front of and close to the openings outlet 18, that is to say following said outlet openings by considering the direction of progression of the material being treated in the oven. Said movable part comprises, at least in this zone, an inner wall 29 of conical shape of increasing diameter from back to front, covered with refractory material.

The rotary kiln arranged according to the invention operates in the following manner: The assembly constituted by the coaxial tubular bodies 1 and 5 rotates continuously, driven by a motor (not illustrated in the drawings) which acts on the ring gear 4. The raw plaster, which is the starting material subjected to the treatment, is, after being appropriately ground, introduced into the furnace by the side of the inlet hopper 30 which gives access to the inlet openings 7. The slope of said tubular bodies and the action of any helical thrust fins which can be placed in the initial part of chamber 6 (fins not illustrated in the drawings), lead said material towards the rear part of the latter, so that this material moves in the opposite direction to that of the hot air and the flue gases in circulation: the arrows F indicate the direction of circulation of this air and these gases which are finally discharged outside by the upper part of the hopper e entry 30 above. The material then passes into the tubular body 1 via the passages 9 after which its direction of flow is reversed, as indicated above.

It is again emphasized that the shape and arrangement of the blades 25, in cooperation with the presence of the longitudinal fins 26, makes it possible to extend the residence time of the material inside the furnace, with very significant savings. of course length, while obtaining the same cooking effect compared to other known ovens.

When the plaster subjected to firing arrives in the zone of the outlet openings 18, it has reached a temperature of between 130 ° C. and 200 ° C., this with regard to the plaster called semi-hydrated. The precise regulation of the cooking temperature is ensured by means of an appropriate process duration control, and also by means of a burner control. Depending on the number of outlet openings 18 and / or their size adjusted appropriately, the output of a greater or lesser amount of this type of plaster is obtained, when the material being processed arrives in the area where are located in said openings, this quantity being discharged via the unloading hopper 20.

The material which has not been discharged through the openings 18 continues to cook at higher degrees and, for this purpose, it passes through the passages 28 and reaches the interior of the hearth 12, and more precisely in the interior of the movable part 12a of the latter, where it is exposed more directly to the action of the burner 16, thereby reaching temperatures between 400 ° C and 600 ° C, with peaks up to 800 ° C. This gives the plaster called anhydrite, also in several variants, depending on the concrete temperature reached,

which can be adjusted as desired by acting appropriately on the burner 16. The outlet to the outside of the anhydrite plaster obtained takes place through the outlet opening 19, which in the present example is a single outlet, but which can also be provided in the form of multiple outlets, as previously described for the evacuation of semi-hydrated plaster. The unloading hopper 22 is used to collect the anhydrite plaster thus obtained.

In the practical implementation of the object of the present invention, it is possible to modify all the details which do not affect, do not alter or change its specific essential design.

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Claims (10)

655785 2 1. Rotary oven intended for the manufacture of plasters, composed by a large rotating cylindrical tubular body (1) closed at one of its ends or rear end (la) and coaxially connected to another external cylindrical tubular body ( 5) of shorter length which extends over the greater part of the central range of said large tubular body (1) delimiting, between these two bodies, an intermediate annular chamber (6) whose front end (5b) is in communication with a charging hopper (30) of the material to be treated and the rear end (5a) of which is in communication with the interior of the internal cylindrical tubular body (1) by means of passages (9), said furnace further comprising means intended to ensure and regulate the circulation of the material to be treated and arranged inside said annular chamber and said internal body, and on the path of said material, outlet openings (18,19) for the latter, a burner (16) and a hearth (12), support means (2,3; 2 ', 3') and rotation drive means (4), characterized in that the hearth (12) of said furnace is executed in two parts: - On the one hand, a fixed part (12b) in which the burner (16) is installed; and, - on the other hand, a movable part (12a) constituted by one of the end portions or front portion (13) of the inner cylindrical tubular body (1); the open ends (14,15) of the two parts (12b, 12a) of said hearth (12) being placed opposite one another. 2. Rotary oven according to claim 1, characterized in that the burner (16) is installed in the bottom of the fixed part (12b) of the hearth (12). 3. Rotary oven according to claim 1, characterized in that the inlet or charging hopper (30) gives access to a plurality of inlet openings (7) formed at the front end (5b) of the tubular body cylindrical outer (5) and opening into the annular chamber (6). 4. Rotary oven according to sub-claim 3, characterized in that the inlet openings (7), for example six in number, are distributed in circular alignment, so that their receptacles are arranged in cascade. 5. Rotary oven according to claim 1, wherein the support means are constituted by rolling rings (2,2 ') which bear on rollers (3,3'), characterized in that said rolling rings (2,2 ') are arranged on the inner cylindrical tubular body (1), near its front (lb) and rear (la) ends, in areas not covered by the outer cylindrical tubular body (5). 6. Rotary oven according to claim 1, characterized in that the internal surface of the inner cylindrical tubular body (1) is provided with blades (25) being in the form of short sections and all inclined in the same direction, these blades being arranged alternately, in the transverse direction, and forming rectilinear alignments, in the longitudinal direction; a continuous fin (26) also extending in the longitudinal direction being disposed between said continuous alignments of said blades (25). 7. Rotary oven according to claim 1, characterized in that the inner cylindrical tubular body (1) is provided, on its periphery, with a plurality of outlet openings (18) arranged in front and at a short distance from the front end of the outer cylindrical tubular body (5), the said outlet openings (18) opening into an unloading hopper (20) intended for the reception of semi-hydrated plaster. 8. Rotary oven according to claim 7, characterized in that said outlet openings (18), for example eight in number, have an adjustable amplitude, and are provided with flaps (21) freely articulated, so as to be able to open and close successively, by pivoting under the effect of gravity, during the rotation of said cylindrical tubular body (1). 9. Rotary oven according to claim 1 or according to one of sub-claims 7 or 8, characterized in that the movable part (12a) of the hearth (12), includes passages (28), preferably the number of two, for the entry of material not discharged through the outlet openings (18), these passages being arranged after and close to said outlet openings (18) of semi-hydrated plaster, said movable part having its inner wall covered refractory material and approximately conical in shape increasing in diameter from rear to front, at least in the region (29) of said passages; and by the fact that the front edge of this wall delimits or comprises the outlet opening (s) (19) for plaster called anhydrite, said opening (19) or said openings (19) opening into a suitable unloading hopper (22) . 10. Rotary oven according to claim 1, characterized in that the crown (4) intended to receive the motor movement for the rotary drive of the mobile assembly (1,12a, 5) of said oven is arranged around and close to it from the rear end (1a) of the inner cylindrical tubular body (1).