US2245881A - Apparatus for drying fine granular materials - Google Patents

Description

June 1941- e. A. VISSAC APPARATUS FOR DRYING FINE GRANULAR MATERIALS Filed July 17, 1939 2 Sheets-Sheet l INVENTOR June 7, 1941. agA 'xvlssAc 2,245,881

QEPA-RATU'S nafx'in' FINE GRANULA'R MATERIALS Patented June 17, 1941 UNITED STATES PATENT OFFICE APPARATUS FOR DRYING FINE GRANULAR MATERIALS Gustave Andre Vilsac, Calgary. Alberta. Canada Application Jilly 17, 1939, Serial No. 284,977 7 Claims. (Cl. 34 l64) This invention relates to apparatus for drying fine granular materials.

There are a number of devices for drying wet granular materials as they pass over shaking screens by directing a current of hot air or gases downwardly through the granular materials on the screens. These devices are very effective for comparatively large -or coarse materials since they not only remove the moisture by the hot air or air or gases to be circulated through the devices. This results in an extremely large percentage of the materials being forced V downwardly through the screens by the current of air or gases.

85 progress towards the discharge ends thereof.

It is an object of thepresent invention to provide a novel apparatus for drying fln'e granular materials, including coal, so as to avoid the disadvantages and failures ofthe previously used apparatus. 7

Another object is the provision of appai'atu! in which fine granular materials are periodically suspended above shaking screens by upward drier materials.

A further objectis the provision of apparatus for drying fine granular materials in which the circulation of gases or air therethrough is arranged to prevent any leakage out of the apparatus.

A still further object is the provision of apparatus of the character described in which a pul- 60 sating current of hot gases or air is directed upwardly through ng screens with-the pulsations synchronized with the movement of the screens.

bers of the apparatus, and Figure 5 is an enlarged detail of a counterbalanced flap at the end of a screen.

Referring more particularly to the drawings, l0 and l l indicate two inclined shaker screens supported by suitable oscillatable hangers I2 and I3, respectively, on each side thereof, suspended from beams It secured to vertical supports IS. The screens are preferably covered with wire mesh, perforated plates or wedge wire screen surfaces of proper mesh, and are oscillated in and continuous operation.

The wet granular material is deliveredfrom a chute'20 on to underlie approximately the other half thereof. One set of hoppers Z5 and 26 is disposed beneath the section 2| of the screen l0 while the other set of said hoppers is disposed beneath the section 22 of the screen. Each oi said hoppersis provided with a short pipe 21 at the opening in the bottom thereof. Similarly, a pair of hoppers 28 is suspended from the screen half thereof, with one set disposed beneath the section 23 or said screen and the other set of hoppers disposed beneath the the flue 55 of a furnace 55 which is section 24 of the screen. Each of the hoppers 25 and 55 is provided with a short pipe at the opening in the bottom thereof.- The hoppers under the screens l5 and II are arranged in the same manner. In Figure 1, only one of each of the hoppers 25, 25, 25 and 55 is shown. Figure 2 tion of the pair of hoppers 25 in relation to the screen l5, the remaining hoppers being similarly disposedin relation to their respective screens.

A hood 52 is mounted on and overlies substantially the whole of the screen II and a hood 53 is mounted on and overlies the screen II in a sim ilar'manner. The hoods 52 and 53 are provided with outlet openings 54 and 55, respectively, in the ends thereof, the ends in question being the ends facing the lower ends of the shaker screens. counterbalanced flaps 35' are mounted at each end of the hoods 52 and 55. Each flap 55 is pivotally suspended from its hood and is provided with-a weighted counter-balancing arm 51 and at its lower or trailing edge with a strip 55 formed shows the posipivot point of the hanger l2 (Figure 1) immediately thereabove. A flange 55 is formed around and extends outwardly from the upper end of the sleeve 55, said flange lying in, the same plane as said sloped upper end. Agplate 51 is slidably mounted on a bearing plate 55 which, in turn, is secured to the flange 55. The plate 51 has an opening" therein and a sleeve 1| extending upof canvas or other suitable material, see Figure 5.

The trailing edges of these flaps rest upon the granular materials as they pass thereunder and said materials, now dried, are discharged from the screen H on to a discharge chute 45.

A pair of chambers 4| and 42 are situated side by side beneath the hoppers 25, 25, and 55, both chambers communicating at their forward ends with a pair of vertically disposed pulsators 43 and 44. The pulsator 43 is divided into sections 45 and 45 while the pulsator 44 is divided into sections 41 and 48,- the sections 45 and 41 communicating with the chamber 4i and the sections 45 and 48 communicating with the chamber 42. Blades 55 and 5|, disposed at an angle of 90 with respect to each other, are rotatably mounted in the sections 45 and 46 of the pulsator 43, and blades 52 and", disposed at right angles to each other, are rotatably mounted in the sections 41 and 45 of the pulsator 44, all said blades being rotated by a suitable source of power, such as a variable speed motor 49, see Figure 2.

The pulsator 42 is connected by a pipe 54 to provided with an automatically controlled blower 51, the flue 55 being provided with a damper 55 above the pipe 54. The pulsator 44 is connected by a pipe 55 to an auxiliary air fan 5|, said fan being operated by a suitable source of power (not shown) which may, if desired, be the same as thatoperating the pulsators. An adjustable baflle plate 52 is mounted between the pulsators 45 and 44 andit may be swung upwardly to direct hot gases from the pipe 54 to the pulsator 44 or it may be swung downwardly to direct cool air from the pipe 55 to the pulsator 42.

. The chambers 4| and 42 have a plurality of outlet openings 54 formed in the tops thereof, one for each hopper disposed beneath the screens 15 and H, and a sleeve 55 extending upwardly from each opening. From the description so far, it will be seen that the hoppers oscillate with the screens while the chambers are stationary so that it is necessary to provide a flexible coupling therebetween.

.Figure 3 is an enlarged detail of the coupling between the pipe 21 di the hopper 25 and the adjacent sleeve '55 of the chamber 4 I. I As all these couplings are the same, only one need be described in detail. Referring particularly to Figure 3, the upper end of the sleeve 55 is sloped so that it lies at a tangent to an imaginary circle drawn with its centre coinciding with the upper wardly from said opening and adjustable damper 14 amount of gases passing through each sleeve of the chambers 4| and the pipej21 of. the hopper 25. As a result of this construction, the sliding plate 51 lies at a tangent to an imaginary circle with its centre coinciding with the upper pivoting point of the hanger l2 above mentioned. the plate 55 between the latter and rollers 12 held thereabove by supports 13 which are mounted on the flange 55 and extend upwardly past the bearing plate 55. When the hopper oscillates with the screen ll, both a vertical and a lateral motion is imparted thereto so that the lower end of the pipe 21 moves through an arc, the centre 01' which is the upper pivot point of the hanger l2 referred to above. The sliding plate 51 allows the pipe 21 to move laterally while the sleeve 1| permits said pipe to move vertically. The sliding plate 51 and its sleeve 1| act as a flexible coupling to prevent gases from passing from the sleeve 55 into the atmosphere outside the device.

Each outlet opening 54 is provided with an by means of which the 55 may be regulated. Furthermore, the dampers may be pivoted downwardly or upwardly selectively to direct gases through the sleeves 55 from the bottom and/or from the top 0! the chambers 4| and 42.

The outlet openings 24 and 55 of the hoods 32 and 33 are connected to horizontal pipes 15 and 15, respectively, by means .of flexible couplings similar to those just described. In this case, the bearing plates 55 are mounted directly on the ends of the hoods and the sleeves 1| of the plates 51 slidably flt into their respective horizontal pipes. These couplings function in the same manner as the previous couplings, the only difference being that the hoods oscillate while the pipes 15 and 15 remain stationary. The horizontal pipes 15 and 15 are connected at their free ends to a dust'collector 11 which is connected by a suction pipe 15 to an exhaust fan 15 having a discharge pipe 55. If desired, the rearward ends 42 may be connected to the dust collector 11 by pipes 5|, each controlled by a damper 52.

The granular material to be treated, say, for example, 'flne coal, passes through the chute 25 on to the shaker screen lb. The inclined shaker screens l5 and H are subjected to opposed and continuous oscillation, during which time the coal passes over the screen i5 and on to the screen ll, whence it is discharged into the discharge chute 45. During its travel over these screens, the coal is constantly subjected to substantially alternate vertical and horizontal movement. The horizontal movement causes the coal to move towards the discharge ends of the screens and the vertical movement continually loosens up the coal to permit hot gases to pass freely therethrough for drying purposes. In this apparatus, the coal is subjected to intense heat as it starts to move across the screen 15 when it is wettest and then heat to which it is subjected is lessened as the coal progresses across the screens and becomes dryer.

slidably fltting into This plate is free to slide on In operation, the blower 51 iorces hot gases without appreciably interfering with the operai'rom the furnace 56 through the flue 55, the pipe tion 01' the apparatus, merely by opening the B4 and the pulsator 43, into the chambers 4| and dampers 82. This short circuits the gases and 42. At the same time, the auxiliary fan 6| forces without the resistance of the materials on the cold air through the pipe 60 and the pulsator 44 screens, the gases quickly blow any material that into the chambers 4| and 42. If the gases are may have accumulated in the chambers, into the too hot, the bailie plate 62 may be adjusted to dust collector.

permit cold air from the pipe 80 to-mix with the The speed of reciprocation oi the screens is if the. air is too cold, said baflie plate may be 10 the well known theory of shaking screens or mix with the cold air hefore'it reaches the pulsastrokes per minute. It is well known that the enter the chambers on top of the cold air and stroke of the screen. In view oi this, the puitime and the sections 46 and 48 are also open side of a screen is being dried in suspension, the

to the chambers 4| and 42. charge end 01' the screen.

The mixture of hot gases and cold air is di- The coal is subjected to the greatest heat as it rected through the outlet openings 64, the hoppassm over the hoppers 25 where it is wettest pers, the coal on the screens, the pipes 15 and and as it progressively passes over the hoppers l6, and into th dust collector H where any water 2', 28 and 30 it is subjected to increasingly less posited, the gases and air being discharged by plied to dried fine coal -is injurious to the coal cold air in the hot gases passing through the terial being dried. These pulsators create a seassist in regulating the mixture passing through amplitude of the pulsations, for a given amount,

each pair of hoppers. The more a damper is of ener y, may be greatly increased by obtaining chambers. The drawings show each succeeding in other words, by creating a condition of resdamper 14 opened to a greater extent than the onance in the apparatus. By employing a previous one, beginning, at the entrance end 01' variable drive for the pulsators, the timing of the chambers. the pulsations may be varied to suit the vary- As previously described, the screen i0 isdivided ing' conditions. The type, condition and densilongitudinally into two sections 2| and 22 while .ty of the material being dried efl'ects these con-- the screen II is alsodivided into two longitudinal ditions.- In this way, the gases in the apparatus sections 23 and 24. The sections 2| and 23 01' constantly pulsste in resonance with the apps- 25, 26, 28 and 30 therebeneath with the chamber ciency with a minimum of power.- 4| and the sections 22 and 24 communicate The combined capacity of the blower 51 and with the chamber 62. With this arrangement, come the resistance of the pipes and Joints bescreens so that the hot gases are directed through fan 19 is sufficient to overcome the resistance of the bed of coal on one side only of the screens 05 the dust collector 11 and the pipes and joints in and H at anyone particular time. By alabove the screens and it is slightly higher than each side of the screens by the oscillation thereof. room inwhich the apparatus is located, so that g It is tobe understood that the term hot gases as used in the foregoing description and in the following claims, includes hot air. For example, air may be heated in the furnace and used in drying the granular materials.

recting a flow of hot gases upwardly through the I material to raise the latter above the screen,

means for making the gases directed through the screen adjacent its discharge end cooler than those directed therethrough at its forward end, and means for-periodically interrupting the flow of gases during movement of the screen towards its discharge end to permit the material to rest thereon during each interruption, whereby the material is subjected to periods of drying and to periods of movement towards the discharge end of the screen.

2. Apparatus for drying ilne granular material, comprising a screen for receiving and agitating the material, means for shaking the screen in a longitudinal posed below said screen, a hood disposed above the screen in an area overlying the hopper, means for directing a flow of hot gases through the hopper and through the material to raise the latter above the screen, means for withdrawing the gases from the hood, and means for periodically interrupting the flow of gases during movement of the screen towards its discharge end to permit the material to rest thereon during each interruption, whereby the material is subjected to .periods of drying and to periods of movement towards the discharge end of the screen;

3. Apparatus for drying flne granular material, comprising a screen for receiving and agitating the material, means for shaking the screen in a longitudinal direction, a hopper disposed below said screen, a hood disposed above the screen in an area overlying the hopper, a blower adapted to direct hot gases through the hopper and through the material to raise the latter above the screen, an exhaust fan connected to the hood for withdrawing the gases therefrom, the. capacity of the exhaust fan being at least slightly greater than that of the blower, and means for periodically interrupting the flow of gases during movement of the screen towards its discharge end to permit the material to rest thereon during each interruption, whereby the material is subjected to periods of drying and to periods of movement charge end of the screen.

4. Apparatus for drying fine granular material, comprising a screen for receiving and agitating the material, means for shaking the screen in a longitudinal direction, a pair of hopper's disposed below the screen, a hood disposed above the screen in an area overlying the hoppers, means for directing a flow of hot gases through the hoppers and through the material to raise the latter above the screen, means for withdrawing the gases from the hood, and means'for alternately interrupting the flow of gases to each hopper direction, a hopper distowards the disduring movement of the screen towards its discharge end to permit the material thereabove to rest on the screen during each interruption, whereby the material is alternately subjected to periods of drying and to periods of movement towards the discharge end of the screen.

5. Apparatus for drying fine granular material, comprising a screen for receiving and agitating the material, means for shaking the screen in a longitudinal direction, a hopper disposed below the screen, a hood disposed above the screen in an area overlying the hopper, a chamber communicating with the interior of the hopper. means for directing a flow of hot gases through the chamber and through the material to raise the latter above the screen, means for selectively mixing cold air with the gases before passing through the screen, and means for periodically interrupting the flow of gases during movement of the screen towards its discharge end to permit the material to rest thereon during each interruption, whereby the material is subjected to periods of drying and to periods of movement towards the discharge end of the screen;

6. Apparatus for drying fine granular material, comprising a screen for receiving and agitating the material, means for shaking the screen in a longitudinal direction, a plurality of hoppers disposed longitudinally of the apparatus below the screen, a hood disposed above the screen in an area overlying the hoppers, a chamber communicating with the interiors of the hoppers, means for directing a flow of hot gases through the top portion of the chamber and through the material to raise the .latter above the screen, means for supplying a flow of cold air to the chamber beneath the hot gases, means for directing some cold air along with the hot gases through at least one hopper adjacent the discharge end of the screen, and means for periodically and simultaneously interrupting the flow of gases and cold air during movement of the screen towards its discharge end to permit the material-to rest on the screen during each interruption, whereby the material is subjected to periods of drying and to periods of movement towards the discharge end of the screen.

7. Apparatus for drying fine granular material, comprising a plurality of screens for receiving and agitating the material, means for shaking the screen in a longitudinal direction, a plurality of hoppers disposed below the screens, a hood disposed above each screen in an area overlying the hoppers thereunder, a chamber communicating with the interiors of the hoppers, means for directing a flow of hot gases through the top portion of the chamber and through the material to raise the latter above the screens, means for supplying cold air to the chamber beneath the hot gases, means for selectively intermixing at least a little of the hot gases and cold air before entering the chamber, means for directing some cold air along with the hot gases through at least some hoppers, means for controlling the amount of cold air directed through each hopper, means for withdrawing the mixture of gases and cold air from the hoods, and means for periodically and simultaneously interrupting the flow of gases and cold air during movement of the screens towards theirdischarge ends to permit the material to rest on the screens during each interruption, whereby the material is subjected to periods of drying and to periods of movement towards the discharge end of the screen.

GUSTAVE ANDRE VISSAC.

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