CA2057767A1 - Hot rod reactor for thermal processing of granular, pulverulent or paste materials - Google Patents

Abstract

The invention relates to a reactor for the thermal treatment of granular, pulverulent or pasty materials, comprising a drum provided with a feed mouth through which the material to be treated is introduced, and if necessary an outlet arranged at a distance. from the entrance mouth. A stirrer, preferably consisting of an endless screw, is placed in the drum so as to mechanically stir the material to be treated. A motor is provided to drive in rotation or in oscillation either the drum or the agitator or both so as to obtain the desired mechanical agitation of the material and its possible movement from the inlet mouth to the outlet, during that heating is applied to the material to be heat treated. According to the invention, this heating is obtained by electrical resistors integrated into the internal structure of the agitator and supplies current by an external source of electrical energy. Thanks to this structure, uniform heating is obtained associated with regular stirring and precise control of the residence time in the reactor, in a reliable, efficient and inexpensive manner. A process for treating granular, powdery or pasty materials using this reactor is also described. This process can be used in particular for the treatment of aluminum scum. However, it can also be used for drying beans, roasting coffee, and heat treatment of minerals or metals.

Description

2 ~ 77 ~ 7 The subject of the present invention is a reactor for the heat treatment of granulated materials, pulverulent or pasty.
The invention also relates to a method of heat treatment of granular, powdery materials or pasty, which is particularly usable when the materials to be treated require vigorous mixing and when precise control of residence time is required of these materials at the set temperature within the reactor.
In many industries, it is n ~ necessary to submit granulated materials, powdery or even pasty at uniform heating associated with regular agitation for a period of predetermined time. So in the industry such processing is often required for dry 6 beans or roast coffee. In industry pharmaceutical, such treatment may also be required for drying or even the reaction of various compounds. In other heavy industries, such treatments may also be required to ensure certain desired transformations of minerals or metals, or to recover products, such as, for example, the metallic aluminum found in the mixtures of aluminum oxide, nitrides, carbides and metallic aluminum known as "scum aluminum ", which are generated by reaction of aluminum melted with the ambient atmosphere during the maintenance of temperature and redesign of aluminum.
From an industrial point of view, this recovery aluminum takes place in a reactor in which ~ foams are heated to a temperature where aluminum metallic is melted while being simultaneously ~ energetically reassured so as to promote coalescence 2 ~ 77 ~

aluminum droplets formed. It is further n ~ necessary to control the time of foam life in the player for optimal use of the power dissipated in the latter.
Many equipments have been suggested up to this day to perform this type of heat treatment.
By way of nonlimiting examples, mention may be made of ovens rotary kilns, cyclone ovens, stirring dryers, fluidized reactors, spiral conveyors, etc.
Existing equipment generally 60nt effective. However, they each have disadvantages, like ensuring an imperfect blend, generating dust, to limit to a certain given value their use temperature ~ because of their structure, ability to operate continuously, etc. to name a few only a few.
One of the objects of the invention is to provide a new type of reactor for heat treatment of granulated, pulverulent or pasty materials, which ensures uniform heating and regular mixing of 6 materials to be treated, with in addition, when this is desired, precise control of the residence time of this material within the reactor.
Another object of the invention is to provide a reactor of the above type, which is simple in design and uses conventional technologies, well controlled6, reliable, efficient and inexpensive.
Yet another object of the invention is to provide a reactor of the above type, which may be used at relatively operating temperatures very simple and without generation gaseous effluents, as in the case of reactors traditional fo ~ sile fuel heating.
Another object of the invention is also to 2 ~ 77 ~ 7 provide a process for heat treatment of materials granules, powdery or pasty, which provides uniform heating of materials to be treated simultaneously ~ a regular mixing of these, while being simple to implement with well-mastered technologies, reliable, efficient and inexpensive.
The reactor according to the invention for the treatment thermal of granular, pulverulent or pasty materials is of the type comprising:
- a drum provided with a feed mouth by which the material to be treated is introduced;
- an agitator arranged in the drum ~ ur way mechanically agitating the material to be treated;
- motor means to enter ~ ner in rotation or in oscillation either the drum, the agitator or both in order to obtain the desired mechanical agitation material; and - means for heating the material introduced in the drum during its agitation.
According to the invention, this reactor is characterized in that the means for heating the material are constituted by electrical resistors integrated into the internal structure of the agitator, and supplied with current by an external source of electrical energy.
The method according to the invention of the treatment thermal of mat ~ rials granules, powders or p ~ teux is of the type consisting in heating the material to be treated in a drum for a predetermined period of time by mechanically agitating this material using a agitator arranged in the drum.
According to the invention, this process is characterized in what heating is done by means of resistors integrated into the agitator structure and powered by an external source of electrical energy.

2 ~ 77 ~ 7 According to a first possible embodiment, the drum is static and has an outlet arranged at a distance from the inlet mouth. In that case, the agitator is made up of one or more screws fine depending on the degree of agitation and mixing required, each screw being provided with a central shaft and arranged in the drum so as to move the material to treat from the inlet mouth to the outlet of the drum at a speed corresponding to a time of residence given. The motor means are then made up by a motor connected to the central shaft of the worm gear to drive it in rotation.
According to a second possible embodiment, the drum is rotatable about a central axis and is provided an outlet arranged at a distance from the inlet mouth.
Again, the agitator consists of one or more endless screw each provided with a central shaft and arranged in the drum so as to ensure movement of the material to be treated from the inlet mouth to the exit of the drum at a speed corresponding to a time of residence given. Of course, means are provided to allow the drum to rotate around its axis and the motor means 6 then consist of a motor connected to the drum to drive it in rotation around its axis.
According to a third possible embodiment, the agitator is shaped like a scraper so as to r ~ clean the inner wall of the drum when the means-engine are in operation. In this case, means may be provided to allow the drum to rotate around a central axis, the drive means then being constituted by a motor connected to the drum to drive the latter in rotation around its axis. Means can also be provided to give the scraper back and forth 7 ~ 7 comes in the direction of the central axis of the drum to increase the r ~ curage of ~ desired.
According to 12 chosen embodiment, the agitator which is pr ~ rence constituted by an endless screw, can therefore rotate or not around its axis. This rotation can be done in the same direction as the reactor or opposite direction, if it is also fitted with a rotational movement. Relative speed of rotation and the agitator in the reactor can, in practice, be optimized for mixing and heating requires material.
When the reactor is intended to operate at temp ~ high erasures, the drum may have a wall internal lined with refractories to reduce losses thermal.
As previously indicated, the heating of materials to be treated is carried out using resistors integrated into the internal structure of the agitator and supplied with current by a source external electrical energy to heat the latter by Joule effect. When the agitator which is preferably consists of an endless screw, provided with a shaft hollow, these electrical resistances can be placed in the hollow tree. When required by the process, additional resistors can be embedded in the inner wall of the drum to provide heating complementary and maintain the temperature profile desired.
As we can understand the agitator when constituted by an endless screw, serves also to control the residence time of the equipment in the drum.
As can also be understood, several agitators can be arranged either online or in 2 ~ 77 ~ 7 parall ~ le in the same drum. The word "agitator"
used in the singular in the claims should therefore be understood as possibly including several agitators the number and relative position of which may vary depending on the desired degree of agitation and the profile of temperature to be maintained inside the reactor.
The nature and geometry of the agitator can be chosen based on working temperatures as well that of the nature and geometry of the materials to be treated in order to avoid any chemical, thermal or abrasion due to the materials to be treated, while maintaining the necessary mechanical resistance. To this end, the agitator can be covered with an anti-wear layer, an anti-corrosion layer or both.
As can also be understood, the nature and the geometry of the electrical resistors used can be selected according to the density of desired power, geometry and nature of the agitator as well as the required mechanical strength.
The relative size of the agitator compared to to that of the drum can be chosen according to the size of the material to be treated, the thermal effect and the residence time sought. Similarly, the relative position of the agitator in the drum can be selected ~ e according to the heat distribution desired.
The reactor according to the invention can operate in continuous or discontinuous. This reactor can be waterproof5fied when control of the atmosphere is required.
The reactor according to the invention can be operated either horizontally, vertically or with a certain inclination. The choice of incline can incidentally be used to add to time control 2 ~ 7 ~ 7 of r ~ sid ~ nce of the material.
It will be understood that when the agitator is kept fixed, its electrical supply can be done directly. However, when the agitator is designed to be rotated at inside the drum, the supply of resistors electric can use mobile contacts (brooms) provided for this purpose, whose structure is well known and commonly used on rotor machines, lo unless the resistors are placed in a tube fixed coaxially inserted in the agitator, the latter can freely rotate around said tube.
When the agitator is shaped like a scraper, it can include pallets or fins which rub ~ ur the inner wall of the oven in fa, con à en ensure the re ~ curags.
The reactor according to the invention is advantageous insofar as it is suitable for any process requiring temperatures between 60C and 1200C or higher, both for food and chemicals mineral and organic than for metallurgy or pulp6 and papers, in short, for all heat treatments of produced pul ~ rulents, granules or p ~ teux.
Several practical embodiments will now be described with reference to the drawings annexed, on which:
- fig. l is a schematic sectional view illustrating a r ~ actor according to the invention provided with a tam ~ our rotary and a fixed agitator;
- fig. 2 is a view similar to that of the fig. 1, provided with a fixed drum and an aqitator rotary;
- fig. 3 is another view of the reactor illustrated in fig. 2, this reactor being specially 2 ~ 57 ~ 67 suitable for the treatment of aluminum foams: and - fig. 4 is a view similar to previous, illustrating another reactor according to the invention provided with a rotary drum and an agitator shaped like a scraper back and forth come.
Reactor 1 according to the invention as illustrated in fig. 1 comprises a rotary drum 3, the wall of which whether or not it is furnished with refractories. Means 5 are provided at each end of the drum to allow it to ~ rotate around its axis. An agitator 7 constituted by an endless screw provided with a central shaft is arranged in the drum so as to be submerged in the load and ensure a displacement of the material to treat from an inlet 11 to an outlet 13 ~ a speed corresponding to a residence time predetermined.
More precise control of residence time can be obtained with a slight slope given to the drum or by fixing a spiral on the wall internal of the latter.
A motor 9 is provided to drive in rotation the drum 3 around ~ on axis. This en ~ ra ~ nement can be carried out continuously or not depending on the type of treatment which one wishes to subject the material to treat.
According to the invention, the heating of the material to heat treatment is carried out with resistors electric 17 arranged in the hollow shaft of the screw endless 7 and connected, using contacts 19, to a external source of electrical energy.
The reactor 1 described above is simple to design and simple to implement. It involves ~
modest capital and operating costs, and made 77 ~ 7 use of well-controlled, efficient and effective electrotechnology relatively inexpensive.
The other reactor 21 according to the invention as as illustrated in fig. 2 is, like the r ~ actor 1, provided a h ~ licoidal heating agitator. In order to simplicity ~, the ~ elements previously described have been identified by the same numbers, to which the number 20.
In this embodiment, the drum 23 is fixed and it is the endless screw 27 which is driven in rotation by the motor 29 to ensure mixing of the material to be processed and its displacement in the drum while thereby controlling his residence time from the inlet mouth 31 to outlet 33 o ~ the material trait ~ is recovered.
Again, resistors 37 are arranged in the hollow shaft of the worm 27 to heat this and the material in the drum. In that case particular, the power supply of the resistors 27 can be done using a brush contact system 39.
According to another possible embodiment, all of the resistors 37 can be arranged in a tube coaxially arranged in the worm gear. In this last case, the tube in ~ uestion can serve as a support internal fixed for the endless screw which is thus turned around him. This embodiment presents the same advantages as previously, namely remove the need for mobile contact for resistances while facilitating the maintenance of everything.
Fig. 3 shows a possible application of reactor illustrated in fig. 2 for the treatment of aluminum scum.
Separation of aluminum from oxides, 2 ~ 7 ~

nitrides, and carbides found in scum 6 ~ performs ~ the interior of the reactor, by heating foam at a temperature sufficient to melt aluminum, and energetic brewing at all to promote the coalescence of metal droplets which, at the nettle ~
33 of the reactor, accumulate in a pocket provided for this effect where it6 can be retrieved via a hole casting 33 'then the rest of the scum ~ escapes with a 33 "discharge.
The reactor 21 is particularly interesting ~ ant insofar as it allows controlling the time of scum stay for optimal use of the then ~ dissipated ance. This reactor is also int ~ ressant as long as it meets the three conditions e6sential to the proper implementation of this process, to know proper heating, good brewing and good control of the residence time of the foam.
The advantages of this process for treating ~ aluminum foams used in reactor 21 by compared to the conventional process which uses an oven rotary ~ heating by fossil fuels, are the following:
1- total absence of gaseous effluents avoiding the need for expensive equipment to purify gases and risks of loss by training which are relatively important in the case of a rotary kiln;
2- obtaining a uniform temperature in the oven: and

3- arms ~ full age rarely obtained in an oven conventional rotary, where the mixture is not ideal and o ~
the material is not stirred to the core.
If necessary, we can use fins to improve the mix.
Another advantage of reactor 21 applied to 2 ~ r ~ l767 treatment of ~ cumes is the fact that it can operate in continued. Foams can be introduced regularly by the inlet mouth 31 and be collected ~ the outlet 33 with aluminum without requiring any stop.
The other reactor 41 according to the invention illustrated on the fiq. 4 is designed for the treatment of materials to high risk of cropping. Again, the same numbers as in fig. 1 were used, plus 40.
~ 0 As is known, some materials have tendency to become sticky when their temperature increases. This increase in viscosity makes operation of furnaces with difficult heat treatment because ~ m progressive encroûtaqe of the internal walls of the night oven tremendously uniform heat transfer and good oven running.
To remedy this problem, the actor heating agitator 6 according to the invention is provided with a rotary drum 43 driven by a motor 40. This oven is supplied by an inlet mouth 51 of material to be treated.
Arranged inside the oven is an agitator shaped like a scraper. This agitator is provided with a back and forth movement illustrated with an arrow in its longitudinal axis. As you can see, this agitator 47 is fitted with paddles which constantly allow scrub the walls of the drum as this one turns. ~ ien heard, in this aas as in previous case ~ teeth, the heating of the material to be treated is perform with electric resistors 57 incorporated into the internal structure of the agitator 47 and powered by an external source of energy electric.
~ ien heard, other modifications could be brought ~ es to the invention as it comes from ~ tre 2 ~ 7 ~ 7 previously described, without departing from the scope of the latter as defined in the appended claims.

Claims (15)

1. A reactor for the heat treatment of granular, powdery or pasty materials, of the type including:
- a drum provided with a feed mouth by which the material to be treated is introduced;
- an agitator arranged in the drum so mechanically agitating the material to be treated;
- motor means for driving in rotation or in oscillation either the drum, the agitator, or both in order to obtain the desired mechanical agitation material; and - means for heating the material introduced in the drum during its agitation, characterized in that that said means for heating the material are constituted by electrical resistors integrated in the internal structure of the agitator and supplied with current by an external source of electrical energy. 2. The reactor according to claim 1, characterized in that:
- the drum is static and has a outlet arranged at a distance from the inlet mouth;
- the agitator consists of an endless screw provided with a central shaft and arranged in the drum of so as to move said material to be treated from the mouth input to output of the drum at a speed corresponding to a predetermined residence time; and - the drive means consist of a motor connected to the central shaft of the worm gear for drive it in rotation. 3. The reactor according to claim 1, characterized in that:
- the drum has a central axis and an outlet arranged at a distance from the inlet mouth;
- the agitator consists of an endless screw provided with a central shaft and arranged in the drum of so as to move said material to be treated from the mouth input to output of the drum at a speed corresponding to a predetermined residence time; and - means are provided to allow the drum to rotate around its axis;
- the drive means consist of a motor connected to the drum to drive it in rotation around its axis. 4. The reactor of claim 1, characterized in that the agitator is shaped like a scraper to scrub the inner wall of the drum when the motor means are in operation. 5. The reactor according to claim 4, characterized in that:
- the drum has a central axis;
- means are provided to allow the drum to rotate around its axis;
- the motor means consist of a motor connected to the drum to drive it in rotation around its axis;
- means are also provided to give the scraper back and forth movement in the direction of the central axis of the drum. 6. The reactor according to any one of Claims 1 to 5, characterized in that the drum has an inner wall lined with refractories. 7. The reactor according to any one of Claims 1 to 5, characterized in that the drum has an internal wall in which are embedded electric resistors to provide heating complementary. 8. The reactor according to any one of Claims 1 to 5, characterized in that the agitator has a hollow shaft and said electrical resistances are placed in this hollow tree. 9. The reactor according to any one of Claims 1 to 5, characterized in that the agitator is covered with an outer anti-wear, anti-corrosion or both. 10. The reactor according to any one of Claims 1 to 5, characterized in that the drum is horizontal. 11. The reactor according to any one of claim 1 to 5, characterized in that the drum is slightly tilted. 12. A heat treatment process for granular, powdery or pasty materials, of the type of heating the material in a drum for a predetermined period of time by shaking mechanically said material by means of an agitator arranged in said drum, characterized in that said heating is carried out by means of electric resistors integrated into the agitator structure and supplied by an external source of electrical energy. 13. The method according to claim 11, characterized in that it further comprises a displacement of said material in the drum from an inlet mouth up to an exit provided therein, said displacement being carried out by said agitator shaped for this purpose like an endless screw. 14. The method according to claim 11 or 12, characterized in that mechanical agitation is obtained by rotary drive of the drum with respect to the agitator. 15. The method according to claim 11 or 12, characterized in that the mechanical stirrer is obtained by rotating the agitator relative to the drum.