US2925177A - Centrifugal separator - Google Patents

Description

2 Sheets-Sheet 1 Filed March 25, 1957 Feb. 16, 1960 E p, TROLAND 2,925,177

CENTRIFUGAL SEPARATOR Filed March 25, 1957 2 Sheets-Sheet 2 United States Patent O CENTRIFUG'AL SEPARATOR Application March 25, 1957, Serial No. 648,054

4 Claims. (Cl. 209-211) This invention relates to a centrifugal separator for separating solid material from liquid suspensions thereof and pertains more specifically to a safety interlock arrangement for valves communicating with a sump for the reception of material rejected by the separator.

It has been the practice to provide a sump at the bottom of a centrifugal separator for receiving material rejected from the separator at periodic intervals or as often as required by the accumulation of rejected material in the sump. The entrance to the sump from the separator is closed and the exit from the sump to the atmosphere is then opened to permit discharge of the rejected material. With such an arrangement there is a risk that inexperienced or careless workers might accidentally open simultaneously both the entrance and the exit to the sump, resulting in the discharge of the entire contents of the separator. Since such separators frequently are very large, holding hundreds of gallons of liquid suspension, such accidents may result in major damage.

One object of the present invention is to provide a safety interlock for the entrance and exit valves on the sump of a centrifugal separator arranged to prevent simultaneous opening of both valves.

' Another object is to provide a safetyinterlock of the type described in which a fluid pressure system is employed for actuating the valves.

Still another object is to provide a fluid-pressure actuating system for valves on the sump of a centrifugal separator, the pressure fluid for opening the exit valve being supplied through and controlled by actuating means for closing the entrance valve, the device being so arranged that it is impossible to open the exit valve until the entrance valve has first been closed.

Afurther object is to provide a device of the type described employing a fluid-pressure system for actuating the valves so constructed and arranged that it is impossible after the dumping operation to open the entrance valve until the exit valve has first been closed.

Other and further objects will be apparent from the drawings and from the description which follows.

In the drawings:

Fig. l is a view in side elevation, partly broken away and in section, of a centrifugal separator embodying the present invention;

Fig. 2 is a view in vertical section on an enlarged scale of the actuating cylinder and piston for actuating the entrance valve;

Fig. 3 is a schematic view showing the arrangement of pipes, valves and cylinders for controlling the valves with the entrance valve in open position and the exit valve in closed position; and e i Fig. 4 is a view corresponding to Fig. 3 showing the entrance valve in closed position and the exit valve in open position. fAs appears in Fig. 1, the separator comprises a generally cylindrical chamber having a tangential inlet 12 adjacent its upper end and an axial outlet 14 at its upper end for the accepted material withdrawn from the separator. The separator has a conical portion 16 at the lower end of cylindrical portion 10 opening into a sump chamber 18 at its bottom. The whole assembly is mounted upon angle iron supporting legs 15, 15.

Disposed within the separator is a valve 20 which is mounted for axial movement to and from. a raised position as shown in Fig. 1, in which the sump chamber 18 is open to the bottom of the separator, and a lowered position, in which it seals sump chamber 18 from conical portion 16. Valve 20 is mounted on the end of actuating piston rod 22 slidably arranged in cylinder 24 which in turn is secured in a housing 26 supported from the walls of conical portion 16 by a plurality of hollow struts 28, 28. A conical baffle 30 may be mounted over cylinder 24 as disclosed in my co-pending application, Serial No. 586,704 filed May 23, 1956. An exit valve or closure 34 is mounted on bracket 36 at the lower end of sump chamber 18 bracket 36 being pivoted to an angle iron support 38 secured to the sideof sump chamber 18 so that closure 34 is adapted to be swung to and from a closed position in which it seals ofi sump chamber 18, as shown in Fig. 1, and an open position in which sump chamber 18 is open to the atmosphere. The means for actuating closure 34 includes a linkage 40 pivoted at one end to bracket 36 and at the other end to a toggle 42 which in turn is pivotally mounted, on angle iron 38 and is secured to piston rod 44 slidably mounted in cylinder 46 which is pivotally secured at its upper end to bracket 48 mounted on the side of sump chamber 18.

Pressure- fluid lines 50, 52, 54 for supplying fluid under pressure to cylinders 24 and 46 are arranged to pass through hollow supporting struts 28, 28 as shown in Fig. 1. Cylinder 24, as shown in Fig. 2, includes an end closure 56 at its upper end into which fluid-pressure line 50 is threadedly engaged and which acts .as a stop for the upper face 58 of piston 22. Cylinder 24 also includes a closure member 60 at its lower end having a central cavity 62 of reduced diameter which mates with and receives a corresponding portion 64 of reduced diameter at the lower face of the piston. A passage 66 in the wall of closure member 60 communicates with fluidpressure line 54 while a second axially extending passage 68 in closure member 60 communicates with fluid-pres sure line 52. i

As shown in Figs. 3 and 4, a check valve 70 is provided in line 54 between cylinder 46 and cylinder 24, which communicates at one end with the lower reduceddiameter portion 62 of cylinder 24 as described above and at the other end with the lower portion of cylinder 46. Check valve 70 is arranged to permit fluid flow through line 54 into cylinder 24 and to prevent flow in the opposite direction. A branch line 72 connects the midpoint of line 54 to needle valve 74, while a separate line 76 arranged in parallel with line 52 communicates with the upper end of cylinder 46. A pressure fluid such as air is supplied to the control system through filter 80, water-trap 82 and pressure regulator and gauge 84, the air supply being introduced into a four-way slide valve 86 which may be of conventional construction and which includes a tubular housing 88 and a slide member including a pair of spaced sealing disks 90, 92 rigidly connected together by connecting rod 94. Sealing disks 90, 92 are actuated by a plunger rod 96 which in turn is actuated by a solenoid of any conventional vconstruction.

Outlets 100, 102 in the wall of valve 86 vent the interior Aline 110' connected to a source of water under pres sure is led through valve 112 into the side wall of sump chamber 18 nearthe top. A branch line 114 pro.- vided with pressure-actuated .iiontrol valve 116 summits: cates with sum'pchamber near its bpttdm. Valve 1 12 is adjusted so" that there is of water constantly through line 110 into sump' s, while valve 115 sea: justed so that flow through line 114 occurs only when the pressure within sump 18 is below a piedtermined value.

I a operation of the device, the liquid dispersion is introduced through inlet 12 under pressure and swirls downwardly around the inner face of chambers and 16' to form a vortex through the center of which the accepted material rises to exit through exit pipe 14. Any rejected solid particles are thrown out of the vortex and pass downwardly into sump chamber 18 through the entrance valve which is normally maintained open during operation of the device, valves 20 and 34 being in the position shown in Figs. 1 and 3. The constant flow of water through line 110 and valve 112 serves to prevent the rejection of too much material from the Separator into sump 18' by maintaining a gentle flow of liquid upwardly from sump 18 into conical portion 16. When it is desired to empty and clean out sump chamber 18, slide valve 86 is actuated by means of plunger 96 to 'the' position shown in Fig. 4, so that the supply of com pressed air is brought into communication with passage 106 while passage 104 communicates with vent 102. This introduces air under pressure through line 50 into the top of cylinder 24, urging piston 22 downwardly. Airalso passes through needle valve 74 and line 72 to line 54. However, no pressure buildsup in this line or in the bottom portion of cylinder 46 because line 54 is vented through check valve 70 and cavity 62 in the lower part of cylinder 24'through passage 68 and line 52 to passage 104 and 102, 7

As piston 22 descends, however, to the position shown in dotted lines in Fig; 2 where reduced-diameter portion 64 just enters cavity 62, line 54 is sealed off from its vent to the atmosphere so that air pressure can now begin to build up in the lower portion of cylinder 46. This pressure build-up occurs rather slowly because of the restricted rate of flow of the air through needle valve 74 so that piston 22 has time to complete the relatively small remaining portion of its travel, thus closing securely valve 20 before suflicient pressure has developed in the lower portion of cylinder 46 to move piston 44 appreciably. As soon as this pressure does build up, however, piston 44 is urged upwardly to open exit valve 34 as shown in Fig. 4, thus permitting the contents of sump chamber 18 to fall out.

"Water under pressure continues to be introduced through line 110 to wash the interior of sump 18 while the liquid dispersion to be separated continues to be introduced through inlet 12 of the main separator and the rejected material continues to accumulate on the upper face of now-closed valve 20 at the bottom of conical portion 16. In addition, when exit valve 34 is opened, the reduced pressure in sump 18 opens valve 116 and causes a flow of water through line 114 to wash clean the face of valve 34. After sump 18 has been cleaned, valve 86 is actuated to the position shown in Fig. 3, thus bringing passage 106 into communication with vent 100 and bringing passage 104 into communication with the supply of air under pressure. The compressed air passes through passage 104 and pressure line 76 to the upper end of cylinder 46, urging piston 44 downwardly and moving valve or closure 34 to closed position as shown in Fig. 3. At the same time the compressed air is introduced through passage 104 and line 52 to the lower part of cylinder 24. However, the air pressure is so adjusted by means of reduction valve 84 that it isinsufiicient to move valve 20 against the hydrostatic head above it in the separator, i. e., against the pressure drop across valve 20 when closure 34 is open to the atmosphere. As water under pressure continues to flow through lines 110 and 114 into sump chamber 18, the pressure within the sump chamber builds up. When sufiicient water has been introduced into sump 18 so as to balance a sufliciently large fraction of the pressure on the upperface of valve 20 and thus reduce the pressure drop across the valve, the air prespossible to open valve 20 unlessvalve 34 has first beelr closed, thus providing an automatic safety interlock for the two valves.

Although specific embodiments of the invention have been described'hereiu, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit and scope of. the appended claims.

I claim:

1. A centrifugal separator having an outlet. communi-f eating with a sump for the reception of rejected material and having a first valve at the entrance, to said sump and a second .valve at the exit thereof to the atmosphere;-

, said first valve being mounted within said separatoror movement toward and away from said outlet to seal the entrance to saidsump, means mounted within said separator including a fluid-actuated piston in a cylinder for actuatingsaid first valve, means for supplying fluid under limited pressure to said cylinder, said pressure being limited to only a portion of the pressure required to actuate said first valve against the pressure drop existing across it when said sump is open to the atmosphere, actuating. means for closing said'second valve, and meansfor .in

troducing fluid under pressure into said sumpto decrease the pressure drop across said first valve after said sec} ond valve has been closed to permit said piston to open said first valve.

2. A centrifugal separator having a bottom outlet communicating with a sump-for the reception of rejected mag terial and having a first valve between said outlet and said sump and a second valve at the exit of said sump, said first valve being-mounted for movement within said separator toward and away from said outlet to seal the connection between said separator and sump, means also mounted within said separator comprising a first fluid: actuated piston mounted in a first cylinder for opening and closing said first valve, 21 second fluid-actru ated piston mounted in a second cylinder for opening and closing said second valve, means for supplying fluid under limited pressure to said first cylinder, means responsive to the movement of said first piston for supplying fluid under pressure to said second cylinder to actuate said second piston only when said first valve is substantially closed, the pressure of the fluid supplied to' said first cylinder being limited to one less than that required to open said first valve against the pressure drop normally occurring across said valve when closed and when said sump is open to the atmosphere, and means for introducing liquid under pressure into said sump when both valves are closed to reduce the pressure drop across said first valve to permit it to be opened.

3. A separator as defined in claim 2 in which the means for supplying fluid to the second cylinder includes a vent communicating with the atmosphere through the first cylinder, said vvent being closed by the advance of the first piston in its cylinder. 7 p m 4. A separator as defined in claim 3 in which a single source is provided for supplying pressure fluid to both cylinders and said first piston has""a""leading portion of reduced diameter seating in a corresponding portion of the cylinder of reduced diametensa id vent entering said reduced-diameter portion of the cylinder and being closed by entry of the leading portion of the piston into said reduced-diameter portion.

References Cited in the file of this patent UNITED STATES PATENTS Chance Jan. 10, 1933 Berges July 3, 1945 Davis Sept. 5, 1950 Vissac Feb. 21, 1956 Polleys May 7, 1957 FOREIGN PATENTS Canada Nov. 6, 1956

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