US1761401A - Filter and means for controlling the pulp level therein - Google Patents

Description

June 3, 1930- J. A. MccAsKl-:LL l1,761,401

FILTER AND MEANS FOR CONTROLLING THE PULP LEVEL THEREIN 'Filed oct. 1, 1925 2 sheets-sheet 1 v /A/VE/vro/P JASPER A. MQCHKELL.

I/ 5y www June 3, 1930. J. A, MccAsKl-:LL 1,761,401

FILTER AND" MEANS FOR CONTROLLING THE PULP LEVEL THEREIN Filed Oct. l, 1925 2 Sheets-Sheet 2 Y ff-I VvE/vrom JASPER MKELL Arr'owfrs Patented June 3, 1930 ra'rlarrr` OFFICE JASPER A. MQCASKELL, F SALT LAKE CITY, UTAH FILTER AND MEANS FOR CONTROLLING THE PULP LEVEL THEREIN Application led October 1, 1925.

This invention'relates to automatic feed-` Another object of the'inventionvis to pro# vide a feed regulationl forContinuous-ifilters which will automaticallystop the filter and l relieve the pressure therein when t-he pulp in the filter rises above a predetermined level.

.Another object of the invention isto provide automatic means for gradually feeding A pulp into a continuously operated filter. 2Q Various other objects of the invention will appear as' the description proceeds;

In the drawings, which illustrate one form ofembodiment of the invention- Figure 1 is an elevational view of a 4filter and feeding and feed `control mechanism therefor,"

Figure 2 is an enlarged view ofthe pulp levelcontrolling means shown in Fig. 1

Figure 3 is an enlarged side view of the controlling means shown in Figure 2. l

Referring morespecifically to the 'drawings, the continuous filter 10, which may be of either the pressure or suctiontype, as iis p well known in the art, comprises acasing 11 inside of which a series of circular filter leaves ora drum is mounted upon therotating hollow shaft 12through whichthe ltrate is drawnl ofi'. The pulp orsludge is admitted through a valve 13 to the desired level and the inside of the casing subjected to air pressure, such air being supplied through the pipe 14- to ,cause flow of the filtrate through the filter surface in the case of a pressure filter or the i shaft 12 is subjected to a vacuum in a vacuum filter toV draw the filtrate therethrough. As the liquid in the p ulp is forced through thc filter surface the cake is deposited on the outside thereof and as the filter revolves with the ho-llow shaft 12, the cake is scraped off the surface and deposited outside the sludge Serial No. 59,759.

tank. The level of the pulp in the filter should he kept below thetop of the sludge tank so that none of the sludge flows over the sides thereof. To effect this the flow of pulp into the filter is automatically controlled by the valve 13 which is balanced so that its operation will not be affected by a difference 1n pressure and is operated by a piston in the air cylinder 16. Airis admitted to the cylinder 16 through a pilot valve 17, which is in turn controlled by the float 18 through the lever 19, the shaft 20', the lever 21 and the link 22. The float 18 is raised and lowered by the pulp in the filter and when the pulp risesv to a predetermined level the fioat 18 actuates the pilot valve 17, admitting air into one end of the cylinder 16, which closes the valve 13 so that no more pulp is admitted to the filter; When the level of the pulp lowers, the float'V 18 is lowered, the pilot valve 17 is actuated' thus admitting air into the opposite end of the cylinder 16, and the valve 13 is opened, allowing the pulp to flow into the filter.

An electrical emergency cutoff is provided which operates in case the valve 13 does not close properly and the pulp continues to flow into the filter. A contact arm 23 is attached to the shaft 20 and when theA float 18 has. moved upwardly a predetermined distance past the normal high level of the pulp, the contact arm 23 presses against the button 24, and an electric circuit is closed through the solenoid 25, which raises the lever 26 and turns the three-way cock 27, thereby shutting off the high pressure air flowing through the pipe Q8 and allowing the air in pipes 29 and 3() to the filter and monte-jus 31 respectivelyy to escape through the exhaust port ofthe cock. rlhis relieves the pressure in the pipe 14 and in the filter casing and also in a manner to be hereinafter described prevents more pulp from being forced into the filter from t-he monte-jus. If desired, the escaping air off the driving power of the filter.

.In order to force the pulp into the filter, an apparatus commonly known in the artas a monte-juslis used. rhis device comprises a tank 31 which communicates through an opening in the bott-om and a T-connection 32 may be made to throw a switch and thus shutA with the feed pipe 33 and the filter 10. Swing- check valves 34 and 35 are placed at eitherI side of the connection 32 and are so placed that pulp may pass through them only in the direction of the filter. The compressed air pipe 30 opens into the top of the tank or monte-jus and airflow therethrough is controlled by a three-way cock 36. This cock is operated by the air cylinder 3T which is controlled by a pilot valve 38 similar to valve 17. A float 39 is attached to the shaft 40 extending through the walls of the tank by means of the lever l1', and an arm 42 and link @t3 communicate the movement of the float 39 to the pilot valve 38. Hence when the fioat 39 is caused to movc upwardly by the rising of the pulp in the tank 31, the pilot valve 33 is actuated, admitting air into one end of the cylinder 37. The three-way cock 36 is then operated by the piston in the cylinder 37 to stop the escape of the air being exhausted from the tank 31 bythe raising of the sludge therein, while at the same time compressed air is admitted to the tank 31 through the threeway cock 36 to put the sludge in the tank un der pressure and cause it to flow into the filter when the valve 13 is open.

The operation of the system is as follows:

Pulp is fed by gravity or any suitable means through the feed pipe 33 and check valve 35 into the tank 31 of the monte-jus. As the exhaust port of the cock 3G is opened the air in the tank passes out through the cock and allows the pulp to rise in the tank until it raises the float 39. Raising the fioat 39 closes the exhaust port of the cock 36 and at the same time allows high pressure air to )ass into the tank 31 through the pipe 30. I` he pulp is forced downwardly by the air and as the check valve 35 closes under the pressure, it can only pass through the check valve 34 and up through the open valve 13 into the filter. Then the level of the pulp in the tank 31 has fallen sufficiently to lower the float 39, the compressed air is shut off, already described, and the air in the tank is allowed to escape through the cock 36 and pulp flows into the tank as before. The pulp already in the .filter is prevented from coming back by the check valve 34. The operation just described is repeated until the pulp in the filter has risen high enough to raise the float 18, at which time the valve 13 is closed by air admitted into one end of the cylinder 16 and the flow of pulp into the filter is shut off.

A reducing valve 44 is placed between the filter and the pipe 29 and maintains the pressure in the filter at a little below the pressure in the monte-jus, so that the pulp will flow gradually into the filter. A pipe 4-5 admits air through a reducing valve 4h into a box surrounding the hollow shaft 12 at the end of the filter, such air being under slightly greater pressure so that it will fiow through certain passages in the shaft 12 and in reverse direcscribed in my Patent No. 1,266,133, May 141-,

It will thus be evident that I have provided a simple and efficient system for feeding pulp to pressure filters by which the pulp is gradually fed into the filter and a predetermined level of pulp maintained therein, the means for controlling the flow of pulp including emergency electrical means for shutting down the filter if the means for stopping the flow of pulp into the filter should become defective in any way as by a stick lodging in the valve 13 and preventing its closure.

In place of the check valves 34 and 35, air operated balanced valves may be used, voperating from the float 39 in the same manner as the cock 36 is operated, and connected so that the opening of one valve causes closing of the other and vice versa. These balanced valves insure smooth operation and open and close regardless of pressure differences across the valves.

The use of an automatic monte-jus removes the necessity for a pressure pump and eliminates the cost of operating the pump and by maintaining the pressure in the monte-jus only slightly higher than that in the filter a gradual fiow of sludge into the filter is asfA sured instead of the rush of sludge under the pressure of a pump.

lVhile I have described the system as applied to a pressure filter, it is evident that it may be equally advantageous in use with vacuum filters or under any conditions Where a gradual controlled feed is required, and I do not, therefore, desire to limit the invention to the form of embodiment illustrated-in the drawings, but to interpret the invention broadly within the scope of the appended claims.

I claim:

1. In combination with a continuous rotary pressure filter of the class described, automatic feed control mechanism comprising a monte-jus and means to operate it, a balanced valve, means in said filter to control said valve, an electrical circuit adapted to shut off said monte-jus operating means when said balanced valve reaches a predetermined position, and a connection between said monte-j us and said balanced valve to prevent fluctuations in pressure and pulp level in said lter.

2. In combination with a continuous rotary pressure filter of the class described, automatic feed control mechanism comprising a monte-jus, pressure means to operate said monte-jus, valve mechanism controlling the pressure in said monte-jus, valve mechanism in said filter adapted to limit the intro duction of pulp in said filter, and electrical means to stop the introduction of pulp to said filter and the operation of said monte-jus yvhei the pulp rises above a predetermined eve 3. In combination With a continuous rotary pressure filter of the class described, a monte-jus, said monte-jus and said filter being operated from the same pressure source, a balanced valve in'said filter and a balanced valve in said monte-jus, said valves simultaneously operating to prevent changes of pressure or changes in level in the pulp in said filter.

4. In combination with a pressure filter of the class described, automatic feed control mechanism adapted to continuously supply said filter With filter pulp, said mechanism Comprising a monte-jus, an inlet valve for said filter, a pilot valve, pulp level control means for operating said inlet valve operated by Said pilot valve and pressure means for closing said inlet valve and for stopping said `feed mechanism.

5. In combination with a continuous pressure filter of the class described7 comprising a balanced inlet valve for the ilter, a fluid pressure cylinder and piston for operating said valve, means to control said piston comprising a pilot valve and a oat resting upon the liquid in said filter, said float through the rise and fall of said liquid actuating the pilot valve to cause the piston to open and close said balanced valve, and means actuated by the rising of said float above a predetermined level to stop the iioiv of liquid to said balanced valve.

6. In combination with a continuous rotary pressure filter of the class described, 'auto matic feed control mechanism comprising a monte-jus, pressure means to operate said monte-jus, valve mechanism controlling the pressure in said monte-jus, valve mechanism in said filter adapted to limit the introduction of pulp in said filter, and means to stop the operation of said iilter and monte-jus When the pulp rises above a predetermined level.

In testimony whereofl I have aiiXed my signature to this specification.

JASPER A. MCCASKELL.

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