US2438258A

US2438258A - Pulp ejector

Info

Publication number: US2438258A
Application number: US619833A
Authority: US
Inventors: Stokes Rupert Octavius
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-10-04
Filing date: 1945-10-02
Publication date: 1948-03-23
Anticipated expiration: 1965-03-23

Description

amlh 23, o STOKES PULP EJECTOR Filed Oct. 2, 1945 3 Sheets-Sheet 1 R. o. STOKES PULP EJECTOR March 23, 1948.

Filed Oct. 2, 1945 5 Sheets-Sheet 2 March 23, 194.

R. OJ STOKES- PULP I EJECTOR Filed 001:. 2, 1945 3 Sheets-Sheet 5 Patented Mar. 23,, 1948 UNITED STATES PATENT OFFICE Application October 2, 1945, Serial No. 619,833 In Great Britain October- 4, 1944 8 Claims. 1

The invention relates to pulp ejectors, that is mechanism. by which settled solids can be drawn from the bottom of an under water pulp storage tank. The problem arises most frequently in the case of sand but it is met with whenever a finely divided solid in substantial quantity is suspended for storage or handling in a liquid and is liable to settle. The term sand used hereinafter must be considered as including any such solid, pulp being a suspension of sand so defined in water.

According to the invention the pulp ejector comprises three tubular members one within another and each with an open end of which the outer and middle ones project downwards into the sand vessel and terminate therein and the inner one is adapted to receive the pulp and pass it to the discharge, while provision is made for a supply of water to the space between the outer and middle tubular members to keep the sand in a teetering state and for a pressure diiference to make the pulp so produced flow away through the inner member.

The tubular members are not necessarily of circular cross section, If they are of rectangular cross section, the pulp is discharged in the form of a ribbon, which is advantageous in such cases as delivery of the pulp to a filter drum.

Preferably the middle tubular member is. adjustable in an up and down direction to vary its distance from the vessel bottom and so to modify the thickness of pulp discharged.

Where the pulp is discharged in an upward direction all three tubular members have their ends opening downwards. Th middle member is conveniently in the form of a sleeve, which permits some of the water to enter between it and the inner member. If the outlet is well below the water level in the vessel, the. pressure difierence is provided by the hydrostatic head due to the water in the vessel, and no additional pumping means will be required.

For discharge in a downward direction the inner member will be a pipe end projecting upwards through the bottom of the Vessel, and the middle member may take the form of a cap surrounding the inner member. In this case the full hydrostatic head of the water in the vessel down to the final discharge provides the required pressure difference, but discharge can be stopped by cutting oil the water supply, since the sand will then pack around the ejector.

The invention. is illustrated by two forms of construction shown in the accompanying drawings, in which Figure 1 is a sectional elevation of a pulp stor- 2 age tank or hopper with ancillary apparatus including an ejector according to the invention,

Figures 2 and 3 are enlarged views of the ejector shown in Figure 1 to explain its operation,

Figure 4 is a sectional elevation of another form r of ejector, and

Figure 5 is a similar View of the upper part of the storage tank to which the ejector of Figure 4 is fitted.

Referring first to Figure 1, a hopper l for storing sand or pulp has a bottom generally in the shape of an inverted cone, near the apex of which the ejector is fitted, as will be described later, The sand is fed by a launder 2 into a feed box 3 with open bottom. The wall of the hopper l terminates below the normal level of the water in the hopperan-d is surrounded by an outer wall t to form an annular clear water trough 5. Excess water is discharged by an overflow 6.

For discharging the pulp a curved pipe I terminates at one end near the apex of the cone,-

and at its other end, outside the hopper I, a valve 8 is fitted, which can be opened and closed by lever gear 9, The valve 8 discharges into a launder It).

To regulate the discharge of pulp through the- A rod Hi is movable inside the tube II through a range of heights by means of lever gear l5 and carries at its lower end a sleeve is with its lower edge projecting a little below that of the casing l3, The sleeve I6 is between the casing l3 and the lower end of the pipe 1, having a clearance hole by which the bent part of the pipe 1 passes out. This construction is seen more clearly in Figures 2 and 3 which will be referred to later.

For normal operation a horizontal pipe l'l connects the trough 5 to the pipe II, and a valve !8 in the pipe 1 with hand wheel l9 accessible from the platform l2 serves to control the water flow in the pipe H. A second water supply for starting and for emergencies comes through a pipe 20 to the tube H and is controlled by a valve 2!, which also has its hand wheel 22 accessible from the platform l2,

In normal use the hopper I will contain a thick mass of settled sand with more or less clear water 3 above it. When it is desired to discharge sand from the hopper, the sleeve I6 is raised to the required extent above the bottom fiat of the hopper l and the clear water valve l8 and the discharge valve 8 are Opened. Little water can percolate through the bed of sand to the outlet bend 1, since it would sufier a considerable loss of head due to friction. 7

On the other hand water enters the valve l8 and passes down the central Vertical tube ll'and cylindrical casing I3 with little loss of head. Some of this water passes between the casing l3 and the sleeve l6, causing the sand at the bottom to teeter and thus considerably reduce its friction. sleeve I6 and the outlet bend I and carries away the teetering sand to the discharge valve'fl,

The position of the sleeve l6 governs thethickness of the pulp discharged. If the sleeve is nearlydown on the flat, a thin pulp is discharged as indicated by the narrow column of dots 23 in Figure 3, and,'when it is in its highest position as shown in Figure 2 the thickest pulp consistent with the valve setting is discharged. The thicker pulp is indicated by the wider column of dots 24. In both figures thearrows denote the flow. The water supply valve 2| is provided for emergencies only, for instance when there is a chokage due to the apparatus having been shut down for a considerabletlme. p

It is not always necessary for water to flow down between the outlet bend and the sleeve. In the downward discharge. form of construction shown in Figures 4 and there is no corresponding flow of Water, all the water carrying the ejected pulp taking part in producing the teeter.

In this form of construction the hopper 25 is cylindrical at its upper part and has an open top surrounded by a launder 26 with a short overflow pipe 2?. At the centre of the hopper and levelwith the top is a feed well 28. A water. pipe 29 extends vertically through the centre of the feed well 28 nearly to the bottom of the hopper and has a T joint 38 in the feed well 28 to receive a horizontal pipe 3| from the launder 26. The horizontal pipe 3 is for carrying clear wateroverflowing from the hopper 25 into the launder for the purpose of discharging the hopper from the bottom, andthe upper part of the vertical pipe 29 is for an additional feed of fresh water for the same purpose when starting after a long shut down. 130th branches have regulating

valves

32 and 33.. r

The vertical pipe terminates at the lower end in a cylindro-conical hood or casing 34 which may if desired be supported from the bottom of the hopper by vertical legs or pins so as to leave a practically uninterrupted cylindrical sand inlet aperture below the open end of the casing. The top of the casing is closed except for the inlet by which the vertical pipe 29 enters.

A discharge bend 35 projects upwards through the bottomof the hopper 25 coaxially with the casing'fifl. Thetop edge of the bend 35 is about levelwith the bottom edge of'the casing 34. A

rod 36 coaxial wth the casing 3G and the top end of the bend'SE passes through the side of the bend -by a gland 31. A cylindrical cap 38 closed at the top is fixed to the top of the rod 35 and is clear of both the casing 34 and the discharge bend 35. The lower end of the rod 36 is provided with a hand wheel and screw device 39 by means of which the cap 38 can be raised or lowered in relation to the cylindricalcasing 34 and discharge bend 35 to stop or adjust the flow of pulp.

Other water flows down between the When it is desired to extract sand from the hopper 25, the valve 33 is opened and, if necessary, also the valve 32. The water flowing down between the casing 34 and the cap 38 sets the sand at this place into a condition of teeter and flows away under the cap 38 and downthe bend 35 carrying with it the sand as a pulp of thickness dependent as before on the vertical position of the cap 38.

It will be seen that by means of the invention pulp can be discharged from a hopper by gravity pnly, the hydrostatic head being sufiicient to ensure an adequate flow, whereas in known constructions having only two tubular members it is necessary to supply pressure water to keep the pulp in teeter and a suction pump to lift the pulp from the bottom of the hopper. In the case of the invention a pressure water supply is only provided, as explained above, to overcome a chokage on starting after a long period of rest with a considerable quantity of sand in the hopper. After getting the flow started the water supply may be cut off, the sand being carried to discharge by means of the water supplied with the feed.

What I claim is: V V V 1. A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end within and spaced from the second tubular member and having its other end arranged for the discharge of pulp outside the vessel, means for supplying water to the space between the first and second tubular members, and means for providing a pressure difference to discharge through the third tubular member the pulp teetering due tothe water supplied to the space between the first and second tubular membars.

2; A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and ter minating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member hav ing an open end within and spaced from the second tubular member and having its other end arranged for the discharge of pulp outside the vessel, a connection by which the supernatant water in the vessel can flow into the space between the first and second tubular members, and means for providing a pressure difference to discharge through the third tubular member the pulp teetering due to the water supplied to the space between the first and secondtubular members.

3. A pulp ejector in a vessel fromwhich pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end within and spaced from the second tubular member and having its other endoutside the vessel at a lower level than the normal liquid level within the vessel, and a connection by which the supernatant water in the vessel can flow into the space between the first and second tubular members.

4. A pulp ejector in a vessel from which pulp is to be discharged comprising a. first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end also projecting downwards within and spaced from the second tuba-- lar member, the said third tubular member passing through the lateral wall of the vessel and having its other end terminating outside the vessel at a lower level than the normal liquid level within the vessel and a connection by which the supernatant water in the vessel can fiow into the space between the first and second tubular members.

5. A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end projecting upwards within and spaced from the second tubular member, the said third tubular member passing through the bottom of the vessel to a discharge point therebelow and a connection by which the supernatant water in the vessel can fiow into the space between the first and second tubular members.

6. A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member in the form of a cap closed at the top and open at the bottom and located partly within and spaced from the first tubular member, a third tubular member having an open end projecting upwards within and spaced from the cap and having its other end below the vessel, and a connection by which the supernatant water in 6 the vessel can flow into the first tubular member at the top thereof.

7. A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member projecting downwards into the vessel and terminating there with an open end, a second tubular member projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end within and spaced from the second tubular member and having its other end arranged for the discharge of pulp outside the vessel, means for supplying water to the space between the first and second tubular members, means for providing a pressure difierence to discharge through the third tubular member the pulp teetering due to the water supplied to the space between the first and second tubular members and means for adjusting the position of the second tubular member in an up and down direction.

8. A pulp ejector in a vessel from which pulp is to be discharged comprising a first tubular member of circular section projecting downwards into the vessel and. terminating there with an open end, a second tubular member of circular section concentric with the first projecting downwards within and spaced from the first and likewise terminating there with an open end, a third tubular member having an open end of circular section located concentrically within and spaced from the second tubular member and having its other end arranged for the discharge of pulp outside the vessel, means for supplying water to the space between the first and second tubular members, and means for providing a pressure difference to discharge through the third tubular member the pulp teetering due to the water supplied to the space between the first and second tubular members.

RUPERT OCTAVIUS STOKES.