US2644587A - Dewatering device for sand and the like - Google Patents

Description

July 7, 1953 R. s. WEBSTER I DEWATERING DEVICE FOR SAND AND THE LIKE Filed Dec. 51, 1949 2 Sheets-Sheet 1 DWI I 22 IIIII NVENT BY M @wv gx%% u y 7, 1953 R. s. WEBSTER DEWATERING DEVICE FOR SAND AND THE LIKE 2 Sheets-Sheet 2 Filed Dec. 31, 1949 INVENTOR. bY gfiflirn Patented July 7, 1953 DEWATERING DEVICE FOR SAND AND THE LIKE Roderick S. Webster, Chicago, Ill., assignor to The Hydro-Blast Corporation, Chicago, 111., a, corporation of Illinois Application December 31, 1949, Serial No. 136,349

8 Claims. 1 This invention relates to dewatering devices for sand and the like and more particularly to apparatus for mechanically removing water from granulated material such as sand.

In treating materials such as foundry sand, the sand is frequently mixed with water for cleaning, pumping and other purposes. Before the sand can be used, the water must be removed, and this is preferably done mechanically after which the sand may further be dried by heat. Heretofore the sand has been mechanically dewatered either on rotary screen units employing vacuum to draw water from the sand carried on the screen or in centrifugal units spinning the water from the sand by centrifugal force. Such units dewater the sand effectively but are very expensive and require a large amount of space.

It is one of the objects of the present invention to provide a dewatering device which is simple and inexpensive to manufacture and operate and which requires only a small amount of space.

Another object is to provide a dewatering device in which water is forced from the sand by compressed air. In the preferred construction the sand is confined in a vertical chamber having a perforated bottom, and compressed air is supplied to the top of the chamber to force the water downward from the sand.

Still another object is to provide a dewatering device which is automatically controlled to operate through a predetermined timed cycle. According to one feature of the invention the timed cycle is automatically started in response to the quantity of sand in the chamber.

A further object is to provide a dewatering device in which a supply opening at the upper part of the chamber is closed by a valve operated in response to admission of air to the chamber.

A still further object is to provide a highly efiective and powerful mechanism for operating a closure at the bottom of the chamber.

The above and other objects and advantages of the invention'will be more readily apparent when read in connection with th accompanying drawings, in which Figure 1 is a side elevation with parts'in section of a device embodying the invention;

Figure 2 is an axial section at right angles to Figure 1; I

Figure 3 is a diagram of the control circuit;

Figure 4 is a partial enlarged section of the bottom of the chamber and the closure therefor;

and

Figure 5 is a plan view of the chamber closure with parts broken away. e

The device, as shown, comprises a vertical elongated chamber IEI which is preferably cylindrical and which may be formed of a tubular steel pipe or the like. At its upper end the chamber carries a top closure plate H which may be detachably mounted on the chamber by means of bolts I2. Material is admitted through the closure plate I I through a vertical conduit l3 terminating at its lower end in an angular seat adapted to be closed by a flapper valve l4 pivoted to the conduit at the high side of the seat. At its upper end the conduit flares into a funnel portion 15 to which wet sand is supplied through a supply pipe I6. The pipe it leads from a hopper or storage bin I1 and contains a shut-off valve I8 to control the supply of wet sand. 7

The chamber I0 is open at its lower end and terminates, as best seen in Figure 4, in a sharp annular ridge l9 extending downwardly and terminating in a relatively sharp edge. The bottom of the chamber is adapted to be closed by a perforated disc 2| which may be reinforced by an annular rim-22. A screen 23 overlies the central perforated portion of the dis-c2! and is sufficiently fine substantially to prevent the flow of sand therethrough. The closure carries a pair of supporting arms 24 which are pivoted on a bracket 25 at one side of the chamber. The

pivotal connection is preferably loose so that the closure can float to a certain extent properly to find its seat without requiring accurate location of the pivot.

The closure is adapted to be moved toward and away from its seat by means of a toggle linkage which is constructed to provide a powerful closing force so that the closure disc will seat on the ridge I9 regardless of the fact that a certain amount of sand may accumulate on the disc. This linkage, as best seen in Figures 1 and 2, comprises a pair of bell crank levers pivoted on opposite sides of the chamber with short arms 21 thereof extending generally upward. The upper ends of the arms 2'! are pivoted to the ends of curved links 28 whose lower ends are pivoted to the sides of the closure. The relationship of the arms is such that when the closureis seated the arms 21 extend upward, as shown in full lines in Figure 1, to bring the alignment of pivots slightly over center to produce a toggle locking effect. This construction also provides a very high mechanical advantage for closing the closure with a relatively rapid movement of the closure when it is away from its seat. The levers 26 are swung about their pivots by fluid motors shown as air cylinders 29 connected to the lower shown in Figure 1. .grounded to the other side of the circuit, as inwhich is controlled by the cam 46.

arms of the levers and controlled by valves 3|. Movement of the levers in a direction to close the closure is limited by adjustable stops 32 which engage the outer or lower ends of the levers 26. Preferably the levers 26 are connected by a cross bar 33 to insure simultaneous operation thereof.

Compressed air is supplied to the upper part of the chamber l through a pipe 34 controlled by a valve 35. The pipe extends into the upper part of the chamber and terminates in a horizontal nozzle portion 36 directed against the outer side of the flapper valv [4, as seen in Figure 1. With this construction when air is being discharged from the nozzle portion it strikes the flapper valve and tends to move it toits closed position. Once the flapper valve is closed it will be held closed by the internal pressure in the chamber.

The valve 35 is controlled by a solenoid 31, the valve being normally closed and being opened by the solenoid when it is energized. The supply valve I8 is controlled by a fluid motor 38 connected to an operating lever on the valve and which is in turn controlled by a pilot valve 39.

The pilot valve 39 is shifted by a solenoid 4| being normally in a position to energize the motor 38 to close the valve [8 and being shifted to a position to operate the motor to open the valve |8 when the solenoid 4| is energized. The valve 3| is controlled by a similar solenoid 42. The

valve 3| normally occupies a position in which it controls the fluid motor 29 to pull down on the lever 26 to close the closure and is shifted when the solenoid is energized to operate the motor to open the closure.

The several parts are electrically controlled by a control circuit as indicated diagrammatically in Figure 3. This circuit includes a cyclic controller comprising a motor 43 driving a shaft 44 carrying a series of spaced cams 45, 46, 41, 48 and 49. The motor is connected at one side to a supply line and is connected at its other side to a switch 52 controlled by the cam 45 and to a switch contact 53. The contact 53 is paired with .a contact 54 and is in parallel with the switch .52 as illustrated, the contacts 53 and 54 being bridged by a movable contact 55 which is normally raised, as shown, and which is lowered by a solenoid 56. The solenoid 56 is connected at one side to a current source 51 which may be the same side of a circuit from which the line 5| leads and at its other side to an electrode 58 which projects into the top of the chamber H! to a level slightly below the lower end of the inlet conduit l3 as The casing is preferably dicated by the common ground line 59, so that when sand and water rise in the chamber to the level of the electrode a circuit will be completed through the solenoid 56.

The switch contact 55 also bridges contacts 6|, one of which is connected directly to the line 59 and the other of which controls a solenoid 62 which operates a second switch contact 63. The

contact 63 normally occupies the raised position shown in which the bridge contacts 64'are connected in circuit with the solenoid 4|. When the solenoid 62 is energized, the contact 63 is shifted down to bridge contacts 65, one of which is connected to the ground line and the other of which is connected through a switch I56 whose other side is connected to one of the contacts 6|.

The switch 52 and the contacts 53 and 54 are connected to contacts 67 of a double acting switch The switch normally closes to the contact 61 to complete a circuit to the ground line 59, and when it is shifted by the cam 46 it engages second contact 66. A timer switch 69 is connected'in parallel with the switch contact 61 and is normally open, as illustrated. The timer is controlled by a timing unit indicated generally at H which is connected in circuit with the contact 68 to energize the timing mechanism. The timing mechanism may be of any desired standard type such, for example, as a V heating coil associated with a bimetallic strip so that the switch 69 will be closed a predetermined time after the timing mechanism is energized by closing of the circuit to the contact 68.

The contact 68 is also connected to a contact 12 of a double acting switch controlled by the cam 47. The blade of this switch shown at '13 normally engages the contact 72 and is connected to the solenoid 37. When the cam 41 moves the blade downward, it engages a contact 14 which is connected directly to the ground line 59.

The solenoid 42 for operating the valve 3| is connected to a contact 15 which is adapted to be engaged by switch blade 76 when it is depressed by the cam 49,

. a The parts normally occupy the positions shown in Figure 3 with the valve 35 closed, the valve l8 open, the valve 3| shifted to closethe perforated closure and the sand at a level below the electrode. At this time a mixture of sand and water will flow from the hopper ll past the valve l8 and through the inlet conduit l3 into the chamber. When the level reaches the electrode 58, a circuit will be completed through the solenoid 56 to pull the movable contact 55 down to bridge contacts 53 and 54. This will complete a circuit from the motor 43 through the switch contact 67 to ground to start the'motor running. As soon as the motor starts, it closes the switch 52 through the cam 45 so that the motor will continue in operation after the level has dropped below the electrode 58. The contact 55 will also bridge the contacts 6| to energize the solenoid 62 and move the contact 63 down opening the circuit of the solenoid 4| so that the valve 8 will be closed and bridge the contacts 65 which constitute together with the switch 66 a holding circuit for the solenoid 62. Thus, as soon as the level in the chamber reaches the desired point determined by the setting of the electrode, the cycle controller starts in operation and the supply of wet sand to the chamber is shut oif.

A few seconds thereafter the cam 46 moves the switch contact away from contact 61 into'engagement with switch contact 68. This interrupts the motor operation and completes a circuit through the solenoid 31 through switch I2, 13 and contact 68 to ground so that the'air valve 35 will be opened. At this time compressed air is admitted through the nozzle 36 to close the valve I4 and to force water from the sand through the perforated closure plate. Preferably, a deflector trough 11 is provided below the closure plate to carry the water to any desired point of disposal.

The air continues to flow into the chamber as long as the timer switch 69 is open. I have found from actual experience that approximately one minute or slightly less is suificient to extract the optimum amount of water from the sand. During thisoperation the air does not penetrate the water but forces it in the manner of a fluid column through the perforated closure plate leaving the-sand relatively dry. The actual degree of with a rotary screen type dewaterer-or' with a centrifugal dewaterer' and varies between approximately five and ten per cent, depending upon the character of the sand. Due to this operation and the fact that very little air actually penetrates the sand and water column, the consumption of compressed air is quite small so that the apparatus operates economically and removes the water from the sand very rapidly.

After the desired interval for supply of air determined by the setting of the timer H, the switch 69 will close to again complete a circuit through the motor 43 andstart it running. The cam 46 immediately releases the switch contact which again engages the contact 6'! to complete the normal motor operating circuit so that the motor will continue in operation after the timer switch has again opened.

After an interval of a few seconds to allow for the air pressure in the chamber to be dissipated,

the cam 49 moves the switch blade 76 into engagement with the contact to energize the solenoid 42. This shifts the valve 3i to cause the fluid motor 29 to rock the toggle linkage to the dotted line position shown in Figure 1, thereby to open the closure 2|.

Upon initial opening of the closure 2|, a por tion of the relatively dry sand will drop by gravity from the chamber, but I have found that-the sand tends to bridge the chamber so that only the lower part of the sand falls freely therefrom. At this time the sand will be approximately as shown in Figure 2. i

In order to remove the sand from the chamber, the cam 41 moves'the contact 73 into engagement with the contact '14 to again energize the solenoid 37 and open the air valve 35. The valve is held open for only a very brief interval and admits air to the top of the chamber to blow the sand therefrom. I have found that only a slight pressure is required to remove the sand substantially completely from the chamber so that only a small amount of compressed air is used. When the switch blade 13 is released, it

again moves into engagement with the contact 12 to deenergize the solenoid 31 and allow the air valve to close. Immediately thereafter the cam 49 releases the switch blade 16 to de-energize the solenoid 42 so that the valve 3| will shift to a position such that the motor 29 will move the closure plate up to close the bottom of the chamber. Immediately following this operation the cam 48 opens the switch 66 to interrupt the holding circuit for the solenoid 62 so that the contact 63 can move up to bridge the contacts 64 and again energize the solenoid 4| to open the valve l8. At this time a new operating cycle is started, but the motor will continue to run until it reaches its zero position at which the cam releases the switch 52. This arrangement insures that the timer motor will always start from the same position so that each cycle will be identical. Furthermore, with the mechanism as described it will be apparent that the cycles are automatically controlled and will continue automatic operation as long as the hopper l! contains a mixture of sand and water to be supplied to the apparatus.

While one embodiment of the invention has been shown and described in detail herein, it will be understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

*What ls claimed is:

1. A dewatering device for sand and the like, comprising a vertical chamber of substantially uniform section and unobstructed throughout its height and open at the bottom, a supply connection at thetop of the chamber to supply wet sand thereto, a valve to close the supply. connection, a movable perforated closure for the bottomof the chamber, a pipe communicating: with the upper part of the chamber to supply compressed air thereto, a control valve in the air supply pipe, and a cyclic controller to open the control valve for a predetermined period to blow water from the wet sand through the perforated closure and thereafter to move the closure away from the bottom of the chamber to discharge the sand.

2. A dewatering device for sand and the like, comprising a verticalchamber of substantially uniform section and unobstructed throughout its height and open at the bottom, a supply connection at the top of the chamber to supply Wet sand thereto, a valve to close the supply con nection, a movable perforated closure for the bottom of the chamber, and a pipe communicating with the upper part of. the chamber to sup-' ply compressed air thereto, the valve being held closed in response to air pressure in the chamber, a control valve in the air supply pipe, power means to move the closure toward and away from the bottom of the chamber, and a cyclic controller operating in predetermined timed 'sequence to open the control valve, close the control valve, energize the power means tomove the closure away from the bottom of the chamher, and thereafter briefly to open the control Valve. I

3. A dewatering device for sand and the like. comprising a vertical chamber of substantially uniform section and unobstructed throughout its height and open at the bottom, a supply connection at the top of the chamber to supply wet sand thereto, a valve to close the supply connection, a movable perforated closure for the bottom of the chamber, a pipe communicating with the upper part of the chamber to supply compressed air thereto, the valve being held closed in response to air pressure in the chamber, a control valve in the air supply pipe,'a cyclic controller to open the control valve for a predetermined period and thereafter to move the closure away from a bottom of the chamber, and means responsive to the level of the wet sand in the chamber to initiate operation of a cyclic controller.

4. A dewatering device for sand and the like,

comprising a vertical chamber of substantially uniform section and unobstructed throughout its height and open at the bottom, a supply connection at the top of the chamber to supply wet sand thereto, a valve in the supply connection, a pipe communicating with the upper part of the chamber to supply compressed air thereto, a control valve in the pipe, a perforated closure for the bottom of the chamber, power means to move the closure toward and away from the bottom of the chamber, a cyclic controller operating in a predetermined timed sequence to close the valve in the supply connection, open the air control valve, close the air control valve, and actuate the power means to move the closure away from the bottom of the chamber and means responsive to the quantity of sand in the chamber to initiate operation of the control means.

5. A dewatering device for sand and the like,

comprising a vertical chamber of substantially uniform section and unobstructed throughout its height and open at the bottom, a supply connection at the top of the chamber to supply wet sand thereto. a valve in the supply connection, a pipe communicating with the upper part of the chamber to supply compressed air thereto, a control valve in the pipe, a perforated closure for the bottom of the chamber, power means to move the closure toward and away from the bottom of the chamber, and a cyclic controller operating in a predetermined timed sequence to close the valve in the supply connection, open the air control valve, close the air control valve, actuate the power means to move the closure away from the bottom of the chamber, reopen the air control valve briefly, actuate thegpower means to move the closure toward the bottom of the chamber, and open the valve in the supply connection.

6. The construction of claim including means responsive to the quantity of sand in the chamber to initiate operation of the control means.

7. 'A dewatering device for sand and the like, comprising a vertical chamber open at the bottom, a supply connection at the top of the chamber to supply wet sand thereto, a valve to close the supply connection, a perforated closure for the bottom of the chamber, power means to move the closure toward and away from the bottom of the chamber, a pipe connected to the upper part of the chamber to supply compressed air thereto, a control valve in the pipe, an electrically operated cycling controller to control the valves and the power means, an electrode in the chamber to contact the wet sand therein when it reaches a predetermined level,

I and 'a circuit connected to the electrode to con-- trol starting of the controller.

8. In a dewatering device for sand and the like, a vertical chamber, a supply conduit extending vertically through the top of the chamber and terminating at its lower end in a seat at an acute angle to its axis, a valve disc pivoted to the conduit at the high side of the seat, and an air supply pipe terminating in a generally horizontal nozzle directed at the outer surface of the valve disc whereby impact of supplied air against the valve disc tends to move it toward the seat.

RODERICK S. WEBSTER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 487,323 Ellis Dec. 6, 1892 565,973- Fowler Aug. 18, 1896 662,678 Hysore Nov. 27, 1900 751,810 Rice Feb. 9, 1904' 954,266 Doud Apr. 5, 1910 1,015,960 Kelly Jan. 30, 1912 1,081,744 Hubbard Dec. 16, 1918 1,575,907 Genter Mar. 9, 1926 1,585,549 Jorgensen May 18, 1926 1,710,410 Defenbaugh Apr. 23, 1929 1,721,105 Dotterweich July 16, 1929 1,861,537 Leek June 7, 1932 1,954,405 Dotterweich Apr. 10, 1934 1,961,893 Wadmanet a1. June 5, 1934 2,039,834 Petersen May 5, 1936 2,102,112 Costello Dec. 14, 1937 2,274,319 Chesterman Feb. 24, 1942 2,340,936 Cook Feb. 8, 1944 Kasser Mar. 14, 1944

Images