US1344893A - hofmann - Google Patents

Description

APPLICATION FH ED 0018!, 1918.

Patented June 29, 1920.

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APPARATUS FOR DRYING'GOODS IN LAYERS.

APPLICATION FILED OCT. 3!. 191a.

Patented June 29,-1920.

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UNITED STATES ALFRED HOFMANN, or zUnIoH, SWITZERLAND. I

I APPARATUS FOR. DRYING Goons IN LAYERS.

Application filed October 31, 1918.- Serial No. 260,559;

To all whom it may concern:

Be it known that .I, ALFRED HorMANN, a citizen of the Republic of Switzerland, residing at 7 Asylstrasse, Zurich, in the Canton of Zurich, Republic of Switzerland,have invented certain new and useful Improvements in Apparatus for Drying Goods in Layers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains. to make and use the same, reference being. had to the accompanying drawings, and to letters of reference marked thereon, which form a part of this specification. 1

The usual known drying machines having a number of conveyer bands have the draw- 7 back that only. one half, namely the upper half or stretch of the conveyer bands is utilized, while the lower half .or stretch runs idly. This entails a'double expenditure of constructional materials and powerand also a greater height of the machines. A further drawback is that a portion of the drying air can escape (with the loss of heat) almost without hindrance through theopen spaces left for the passage of the material being dried from an upper on to the next lowerv band. Heat is also lost by the large cooling surface of the machines due to their height.

This invention relates to the type of drying apparatus wherein an endlessconveyer' Now the object of my invention is to obviate the above described defect and to use practically the whole length of the different runs of the conveyer for drying purposes.

According to this invention I employ means which effect tilting and discharging of the frames at points beyond the centersv of the guideand driving wheels for the conveyer. In using the practically whole length of the runs, the. drying air is more perfectly utilized.

Two constructional forms of the im ings in which proved drying apparatus are illustrated by way of example in theaccompanying draw- F gure 1 is a vertical section on the line AB of Fig. 2.

Fig. 2 is a horizontal section on the line C-.-'D of Fig. 1 after removal of the carryng frames and their conveying and guid-- lI1 (lQVlC6S. I *ig. 3 is a vertical cross section on the line EF of Fig. 1. f Fig. 4 shows heating pipes with mixing plates and roof-like hoods;

F 1g. 5 is a separate view of tipping frames at a left hand turning point.

Fig. 6 is a plan of Fig. 5. 1

; F ig. 7 isa separate view of tipping frames at a right hand turning point with the exception of the topone.

Fig. 8 shows the top turning point at the right hand by which frames that face upward-in an upper stretch of the conveyer are also caused to faceupward in the lower stretchof the conveyer.

Fig. 9 is a partial side elevation of Fig. 87 and J V PATENT oFFlcE.

Fig. 10 is a separate view of the means of tensioning the endless conveyer chains.

. As shown the improveddrying apparatus comprises adrying chamber 1 provided with bearings on its longer sides for the chain driving wheels 2 and the chain guide wheels 3, and withpitch chains for both, taking a serpentine course through the drying chamber 1. Each shaft 5 of the chain driving wheels 2 carries outside the chamber 1 a worm wheel 6. With these gearing with worm wheels 6, there engage worms 8 fixed on a common vertical shaft 7 A bevel wheel 9 (Fig.2) fixed on the shaft 7 engages with a bevel wheel, 13 fixed on a shaft 12 that carries belt pulleys 10, 11. Shafts 1 1, 15

carrying two wheels 16, 17 outside the drying chamberl are mounted in angle-armed levers 19 fulcrumed on pins 18 (Figs. 1 and 10) and their horizontal arms are under the action of springs .20. This arrangement serves to tension the endless chains when they become expanded by heat and to allow the chains to contract'again in cooling.

The conveyer for the material to be dried consists of frames 21 pivoted on inwardly projecting portions of the joint pins 22 of the chains 4::(Figs. 5 and 6), and capable of swinging between the chains. In this movehand .portion). and Fig. 8, the frames 21 ment, as willbe perceived from Fig. 1 (right with their projecting portions (borders) 23 in passing from an upper stretch of the con tween the frames 21 widen only gradually and therefore allow the material to drop only very gradually so as not to form any heaps. The material lying on the flat side of the frames 21 is carried along by angle bars 24 (Fig. attached to the undersides of the frames. The material is prevented from falling sidewise by the sides 25 of the drying chamber (Fig. 9).

The chains 4 slide along guides 26 between. which the frames have room to swing. These guides 26 which are arranged in recesses in the sides 25 of the drying chamber 1 and are interrupted at the turning points,

are bent down at one end and bent up at the other. Both ends of the guides are extended beyond the centers ofv the corresponding guide and driving wheels, so that practically the whole length of the different runs of the conveyer may be utilized for drying purposes. At their free ends the frames 21 carry at each side a shoe 27 or a roller 28,

adapted to run on the guides 26. hen the shoes 27 or the rollers 28 have run off the downwardly bent ends of a pair of top bars 26 the frames comeinto a pendulating position (Figs. 5 and 7). until the shoes 27 or the rollers 28 have run up again on to the upwardly bent ends of. a pair of lower bars 26, thereby completing the turning of the frames '21 through 180.

As far as the top turning point (Fig. 1 right, andFig. 8) the frames 21 are pulled by the chains 4, but from that point onward they are pushed until they pass out of the drying chamber. Consequently the first turning point is constructed somewhat difq ferently from the other turning points (Fig. 8). The chain pins 22 that carry the frames 4 move in advance of the latter so that these remain approximately in a horizontal posi tion until their'rollers 28 haverun off the downwardly bent ends of the guides 26. Then they rock in the downward direction until the rollers 28 meet upwardly bent springs 29 that are carried by the guides 26 and serve to moderate the impact of the frames. The springs 29 are bent downward and outward'at 30 for the purpose of causing a complete emptying of the frames 21 as they fall. 31 is a stop for limiting the upward movement of the springs 29 Thus at this point the frames only change their direction", and instead of being pulled they are henceforth pushed, but they are not turned through 180 as at the other turning points. At all turning points however the upper frames are emptied on to the lower frames soas to turn and mix the material. For the purpose of supporting the material and allowing the air to pass through, the frames are covered with perforated sheet metal or with wire cloth 32 as shown in Fig. 6.

On leaving thefdrying chamber 1 the frames. 21 lose their support and tilt down anddischarge their contents. By striking a pin 33 the frames 21 are turned through 180 and completely emptied, and from this point onward they are again pulled along by the chains 4.

In order toprevent the combustion gases employed to heat the material. from coming in contact with the drying air, the said gases as they le. ve the fireplace are first cooled by being ledthrough pipes 34, arranged horizontally underneath the drying chamber 1. By means of a damper the combustion gases may also be led directly to the chimney- 36. and thence into the atmosphere; this is chiefly required. in the case of reat production of same on starting. TVhen the damper. 35 is closed the combustion gases pass first through the pipes 34 that heat the drying chamber, before they are led by a flue 37 into the chimney 36 where they rise as far. as the closed damper 38, and'travel in opposite directions through heating pipes 39. provided under the second, third. and fourth sections ofthat portion of the conveyer that is situated in the drying chamber, to which they give up the larger quantity of their heat. They pass then through a flue 40 into pipes 41 situated under the pipes 34, through which they travel in counter-current whereby the heat is completely utilized. A fan 42 draws the combustion gases out of the pipes 41 and delivers them into the atmosphere. In this manner the combustion gases do, not come in. anyway in contact with the material that is being dried, and any sparks that may be carried over cannot ignite the said material because even if the pipes, were leaky the fan suction would only such in drying air into the said pipes whereas burning particles could neverpass out.

The drying air. proper is blown by the fan 43 into the chamber 44 which contains the lowest heating pipes 41 where it takes up heat from the lowest/and coolest, section of those pipes so as to fully utilize the heat. It then flows along the highest and hottest pipes 34, the radiated heat from which heats it to the permissible maximum temperature, and then after having passed. throughthe iayers of material up to the upper. lengths of the piping it finally escapes into the atmos phere through an opening 45.

In passing from top to bottom through the layers of material, the dryingiair gives up heat to the material and becomes itself each of the three heated layers. This greater heating causes also a more rapid evaporation since the greater part of the steam or vapor is taken up and carried away by the hot air.

For the purpose of bringing the air into intimate contact with the pipes 34 and 39 and mixing it uniformly, and also of providing free spaces to allow seeds and small particles to drop through without falling on to the pipes and becoming burned, the said pipes are provided with mixing plates 46 and roof-like hoods 47 (Figs. 3 and 4). The droppings are collected in the pit 44 under the heating apparatus whence they can be removed from time to time through the opening 48.

What I claim is:

1. In an apparatus for drying bulk material a drying chamber, an endless conveyer, leading in a sinuous form through the drying chamber, wheels over which runs the conveyer, angle-armed levers situated outside the drying chamber on pins, and springs acting on their horizontal arms, said wheels being supported by the bell-crank levers.

2. I11 an apparatus for drying bulk material, a plurality of heating pipes arranged above one another for the purposeof progressively raising the temperature, roof-like hoods and mixing plates arranged over the pipes for utilizing the heating surface to the utmost, mixing the air, and preventing dropping particles of the material from falling on the aid heating devices.

3. A drying apparatus including in combination a drying chamber, an endless conveyer having a plurality of zig-zag runs, guide and driving wheels and stationary guides over which the conveyer passes, frames pivotally suspended from the conveyer, means to' effect tilting and discharging of the frames at points beyond the centers of the guide and driving wheel, pins positioned externally of the drying chamber, other uide wheels over which the conveyer passes fastened on the pins, angle-armed levers on the pins, and springs acting on the horizontal arms of the bell crank levers.

4. A drying apparatus including in combination, a drying chamber, an endless conveyer having a plurality of zig-zag runs, guide and driving wheels and stationary guides over which the conveyer passes, the delivery end portions thereof being curved downward and extended beyond the centers of the corresponding driving and guide wheels and the receiving end portions being curved upwardly and extended beyond the centers of the guide and driving wheels so as to reverse the direction of the frames and to invert the frame.

5. A drying apparatus including in combination, a drying chamber therein, an endless conveyer having a plurality of zig-zag runs, guide and driving wheels and stationary guides over which the conveyer passes,

conveyer frame pivotally suspended from the conveyer, means to effect tilting and discharging of the frame at points beyond the centers of said driving and guide wheels,

pipes arranged horizontally under the drying chamber for receiving heating gases, heating pipes arranged in the drying chamber and in connection with the horizontally disposed pipes, other pipes situated beneath the horizontal-pipes in connection with the heating pipes in the drying chamber and a fan in connection with the last mentioned pipe and adapted to draw the combustion gases out of all of the said pipes.

6. A drying apparatus including in combination a drying chamber, an endless conveyer having a plurality of zig-zag runs, guide and driving wheels and stationary guides over which the conveyer passes, frames pivotally suspended from the conveyer, means to effect tilting and discharging of the frames at points beyond the center of, the said guide and driving wheels, pipes arranged horizontally under the drying chamber adapted to receive heating gases, heating pipes arranged in the drying chamber and in connection with the horizontally disposed pipes, other pipes situated over the horizontally disposed pipes and'in connection with the heating pipe and drying chamber and roof, like hoods and mixing plates arranged over the first named pipe and over'the heating pipes in the drying chamber for utilizing the heating surface to the utmost end for mixing the air and preventing material from dropping and filling on the heating pipes.

7. A drying apparatus, including in com bination, a drying chamber, driving wheels at one end of the chamber, guide wheels at the other end of the chamber, stationary guides between the wheels, an endless conveyer operating over the wheels and guides so as to have a plurality of zig-zag runs within the chamber, spring tensioned anglearmed levers pivotally mounted exteriorly of the chamber, guide wheels mounted on the pivots of the levers and over which the conveyer passes, conveyer frames pivotally suspended from the conveyer, and means to effect tilting and discharging of the frames at points beyond the centers of the first mentioned guide and driving wheels.

In testimony whereof, I have signed my name to this specification.

ALFRED HOFMANN.

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