CA1082257A - Apparatus for assisting movement of a flowable material - Google Patents

Abstract

ABSTRACT

The invention facilitates the movement of particulate matter (such as a powder) over a surface by making the surface from a material which is porous to gas. In use, gas is forced up through the surface and into the particulate matter. This makes the particulate matter flow more easily over the surface.
The invention is claimed to be particularly useful for assisting the flow of matter inside a tank to facilitate discharge of its load.

Description

` i ~015~22~7 -- ~his invention relates to apparatus for assisting - I movement of a flowable material, particularly a solid particulate material or a material containin~ solid ~- particles, for example powders, granules, cement, 1 5 concrete etc.
-`~ J ~he invention arose from the problem that such ~ materials are difficult to discharge from the containers - ~ in which they are transported. Xitherto such containers - ; have had to be tipped through a substantial angle in order to discharge their contents and difficult~ has been ;-i experienced in ensuring that the ~hole of the contents are discharged. Complicated and expensive e~uipment has - ~ been re~uired to effect such dischàr~ge and the removal ., - ~! of residual matter has been time consuming and therefore exæensive. It was pr~arily with these problems in mind that the present invention was conceived.
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; Another problem has been in ensuring that the . co~tainers are filled as completely as possible since access is often a~ailable only through ports which are ~- ~ 20 spaced apart at the top o~ the container. In the `- ~ regions between the ports, solid particulate material,`-- :i when poured into the container tends to fo~m pyramid - ~ or cone shaped piles in the container, whose peaks ¦ coincide with the access ports. Unfilled spaces are left between these piles. ~he invention can also be applied to overcome this problem~
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:~- - Yet another problem is that friction of the ~ particulate material on the base o~ the container during i ¦ discharge causes abrasion thereb~ severely limiting ~` ¦ 30 khe li~e of the container7 :, , -- 2 _ '; !
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Z~i7 The invention provides apparatus for controlling the mo-vement of a finely divided material with respect to a bulk con-tainer therefor, the apparatus comprising: support means defin-ing within the container a supporting surface being pervious to - 5 the flow of a gas; means for inducing gas to flow through the sup-port means to fluidize the flowabl0 material within the container;
an inlet orifice on the container for an additional supply of pressurised gas; a first duct having first and second ends, the `::
first end connecting with the inlet orifice; a venturi unit having first and second gas inlets and an outlet positioned as to be able to direct output from the venturi unit across said support meansJ
the first inlet of the venturi being connected to the second end of the duct to receive said additional pressurised gas delivered to the duct ancl the second inlet of the venturi being in communi-cation with the interior of the container whereby the additionalpressurised gas introduced into the duct entrains gas already ,:.
'~ within the container and admixes therewith to produce the venturi output; and means for controlling the flow of said output.
The invention also provides a vessel for flowable mate-rial adapted to be sealed in an air-tight manner and comprising a floor which is porous to gas but not to the said material, means . for introducing gas under pressure to a space below the floor and ~; a discharge outlet for the material.
` For the discharge of the material from a vessel construc-:~;
~- 25 ted as defined in the immediately preceding paragraph, compressed , . ~
- gas, e.g. air or inert gas, is introduced into a plenum or space below the floorO The gas is forced through the floor into the , main part of the container, thereby fluidizing the particulate ma-terial so that it can easily flow towards the outlet. This flow - 30 of the material towards the outlet can be produced by the pressure ,::
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:: of gas building up inside the container, by a slight tipping of the vessel, or preferably by both of these influences in combi-,; nationO
- A preferred feature is the provision of an inlet orifice for compressed air above the floor at a position remote from the outlet. When the bulk of material has been discharged, a blast of compressed air from this inlet can effectively remove almost all residual matter.
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j ~he invention is most applicable to generally cylindrical containers having one or a series of restricted inlet ports at the top. B~ introducing air through ' 1 the floor whilst such a container is being charged with 7 5 material it can be caused to settle substantiall~

3 uniformally so that the contalner can be filled more . . 3 ~ nearly to capacity than has hitherto been practicable.
- i Means for filtering dirt from the air entering the ~- ~ space beneath the ~loor is preferabl~ provided to prevent "' j 10 congestionO
~- ~ he a~orementioned floor or other support pre~erabl~
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i: includes a surface formed b~ a porous stainless steel . . . ~ ~
material, ~or example that obtainable in sheets ~rom ~; Pall Europe (type ~ and other types).
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Containers used ~or the bu~k transport of powders or ~_ other particula*e material can be ve~y large and therefore contain a large weight o~ material. The a~orementioned ."
i ~ `"floor" therefore has to be quite strong, and tAJhen, as is: usuai~ the container is cylindrical, the floor should be ~ 20 curved so as to ~ollow the contour o~ the cylindrical :~ base. ~he aforementioned porous stainless steel is ideal in that it can bend to the re~uired curvature and is sufficiently strong to withstand the load . .
~ placed on it. ~ever~heless~ suitable support is ,~,;.. i ~?,, ~ 25 preferably provided between the floor and the bottom of the c~lindrical container. Such support can `-~ convenientl~ be provided by longitudinal air channels . , ~ .
~ -to which air, or other gas is supplied from a suitable : :i , ~ .
; source. In this particular arrangement the channels ~j 30 have openings through which the gas issues to a ,....... I , .

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position immediately below the floor from ~Jhence it is ~orced upwardl~ through the floor.

- ~; A particular embodiment of the invention will no~J
-¦ be described b~ way o~ exanple with reference to the accompanying drawings, in which:-~igure 1 is a vertical axial cross-seçtion :~ ~ through a tanX constructed in accordance with the J invention;
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Figure 2 shows the tank as viewed in direction II indicated in Figure 1, the end wall of the tank being removed to reveal the interior;
~-- Figure 3 is a schematic diagram showing the fIow - ~ path of compressed gas; and - ~ ~igure 4 is an axial cross-section o~ a Venturi - 15 action device ~hich directs a blast of aix onto the floor of the tank to remove residual matter~
Referring now to ~igures 1, 2 and ~ of the drawings, there is sho~n a c~lindrical vessel 1 designed to .. , i _ withstand internal pressure. ~he vessel has a series : ~ 20 of man-lids 2 at the top through ~rhich material to be transported is introduced. Alternativel~ a special - injecting nozzle 3,which is optional, can be usedu .
At the rear end of the vessel is a discharge port 4 ; ~ which communicates with the main storage space 5 of the container above a ~loor 6 thereo~.
At the other, front end of the container ; c~linders 7 o~ compressed gas are supported~ thou~h i-t should be pointed out that in alternative arrangements an air compressor could be used instead.
~ duct 8 leads from the source of compressed s `: 1 ' . .

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~LC~822~7 ~.-': ' I gas to a mani~old 9 (~igure 3) ~hich is located at the - ' xear of -the vessel and from which the gas is distributed through to a ~n-turi device 10 in the ou-tlet port 4 / a valve ` i 11, and duct 12; and to an air cleaner 13 via duct ~1 5 14 and valve 150 `~ J From the cleaner 13 the gas (which may be air) ~ passes through duct 16 to a drier 17. On emerging from `-- the drier 17 the clean dry gas is split into two ~G~ - ~ streams. One stream returns through duct 18 and -~ 10 valve 18A to the front of the vessel l~hich it enters ~ J through connector 19 as sho~m in ~igure 1. It then ,..,. , ~ passes through twin vertical ducts 20 to inlet orifices . . . ~ .
i- 21 fitted with Venturi action nozzles, not shown in . i; ~ . ,; ., ~igure 1. ~he ducts 20 have horizontal ~ungs 22 connected ~ 15 across them. ~hese are shown b~st in Figure 2 and ~orm ,,, - ., ,' _ ~ a ladder in conjunction with the aucts 20. ~igure ~~ ~ 2 shows ducts 23 extending outwardl~ from the bottom ends of ducts 20 and terminating at additional orifices 21~.
~he other stream of clean dry gas from the drier ~t;'~; ' ' passes through duct 24 and valve 24A to a space or .. , .
; ~ plenum 25 (Figure 2) which is defined below the floor 6 of the vessel. ~he floor 6 is supported by longitudinal duct members which are-made from sheet ~- 25 metal bent to form an inver*ed "U" cross-section.
he upper and side surfaces of members 26 are formed ~ with a plurality of holes to allo~ passage of gas upwardly - I and side ways. Alternativel~, instead of having holes, the sides may be notched at their bottom edgesO ln i 30- an alternative construction, not sho~^~, it would ;~ I
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82ZS~7 ~ ~ be possible to use a combination of longitudinal and ; I transverse ducts instead of just the longitudinal ducts 20 illustrated.
Filling the spaces between the ducts 20 are members 27 formed o~ a grating or like material having a I pluralit~ of interstices, also to allow the passage of ; ~ gas. ~hese members 27 have an upper surface which is j flush with the upper surfaces of the ducts and over both o~ these is laid a la~er 28 of wire wool.
~he floor 6 is made of porous stainless sheets laid ~ on top o~ the wire wool, each one bending so as to j; ~ extend circumferentially but at a slightl~ greater radius of curvature than the cylindrical container ` itself. ~ongitudinal strips 29 are welded to the ~' 15 inner surface o~ the tank and thè porous sheets are -, i. " .,~
welded to these. ~he strips 29Oprovide the necessary ~- ~ strength to fulfil safet~ re~uirements. ~he individual stainless steel sheets overlap and are welded to each other.
~he illùstrated embodiment o~ the invention can -¦ easily be made starting from a standard container since the parts necessax~ for the construction of the ;1 floor can be introduced through the charging ports and then ~, ~ welded in position. ~he porous stainless steel sheets ` ~ 25 can be ~lexed sufficientl~ to enable them to enter .. ,.
the poxts. Alternativel~, when manufacturing a new container, the stainless steel sheets can be "
^ ~itted during assembl~ of the container.
~igure 4 shows a Venturi nozzle de~ice for fitting to the outlet ori~ices 21, 21A~
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his is formed of two housing parts ~0 and 31 which are held together by co-operating screw-threads.
~he compressed gas enters from ori~ice 21 ox 21A
through inlet 32 and is forced through an annular opening ~3 to ~orm a jet which entrains further air entering through the port 34. ~ relatively small ; volume of high pressure air is thus used to produce a blast formed by a relatively large volume of low pressure air; and this blast of air issues from orifice 35 and sweeps onto the floor 6 towards the outlet 4.
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In order to fill the container the man-lids 2 are opened one b~ one and the load is introduced into that portion of the tank which is im~ediately below it.
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Alternatively the special~ozzle 3 can be used for ; loading. Compressed gas is then introduced into ;., .~
the plenum 25 by opening valves 15 and 24A. ~he air is forced up through the floor 6 and mixes with the load thereby making it behave more like a fluid.
- 20 As a result the load tends to settle, forming a more level upper sur~ace; and more material ma~ then be ;~ introduced.
In order to discharge the load the container ' is tilted sl;ghtl~, with the front end uppermost, and the valves 11, 15 and 24A are opened~ ~he air ¦ flbwing up through the floor again mal~es the load assume a relatively fluid condition allowing it to ¦ ~low easily to the outlet 4: partly under the action f gravity, partl~ under the pressure building up inside the container, and partly under the action of . ,. i .
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;' zg7 the air supplied to the ~enturi device 10 (which in ~ I its principle of operation is similar to the device - I of ~igure ~ and therefore need not be described in detail).
When the container is nearly empty the valve ` ¦ 18A is opened. ~his pro~uces a blast of air fxom , .
orifices 35 which s~eeps residual material towards the 3 outlet 4 from which it is discharged. ~y regulating - - the valves 11, l~A and 24A the optimum performance ¢an be achieved.
~he illustrated containeriwas primarily designed . . . ~ , -.
to be transported by road, rail or boat but could alternatively be used simply for storage purposes.
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- An important feature o~ this embodiment is that the : . ! , container need be inclined onl~ at a~relatively small angle during the aischarge operation thereby avoiding . the need ~or expensive tipping mechanisms. Also, : . , ; the load is discharged quickl~ and with sufficient force to drive it along a pipe~line to the particular -~ 20 spot ~here it is to be used.
! It is emphasised that the illustra~ed embodiment of the invention has been described onl~ as one ; .
, ~ particular example of how the invention can be applied.
~here are other ~orms the invention can take. For ~ 25 example, it would be possible to convey materials -~- continuousl~ from one position to another, along a ¦ ~ duct or pipe-line constructed in accordance with ¦ the invention.

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Claims (7)

The embodiments of the invention in which an exclusive property of priveledge is claimed are defined as follows:-

1. Apparatus for controlling the movement of a finely divided material with respect to a bulk container therefor, the apparatus comprising.
support means defining within the container a supporting surface being pervious to the flow of a gas.
means for inducing gas to flow through the support means to fluidize the flowable material within the container;
an inlet orifice on the container for an additional supply of pressurised gas:
a first duct having first and second ends, the first end connecting with the inlet orifice:
a venturi unit having first and second gas inlets and an outlet positioned as to be able to direct output from the venturi unit across said support means, the first inlet of the venturi being connected to the second end of the duct to receive said additional pressurised gas delivered to the duct and the second inlet of the venturi being in communication with the interior of the container whereby the additional pressurised gas introduced into the duct entrains gas already within the container and admixes therewith to produce the venturi output and means for controlling the flow of said output.

2. Apparatus as claimed in claim 1, and further comprising;
a second duct having first and second ends, the first end of the second duct connecting with said inlet orifice;
a second venturi unit having first and second inlets and an outlet, the venturi being positioned as to be able to direct the output from the second venturi across the support means, the first inlet of the second venturi being connected to the second end of the second duct to receive pressurised additional gas delivered to the second duct and the second inlet of the venturi being in communication with the interior of the container whereby pressurised additional gas introduced into the second duct entrains gas already within the container and admixes therewith to produce said venturi output.

3. Apparatus as claimed in claim 2, in which said first and second ducts comprise the side rails of a ladder structure for enabling a person to enter and leave the lower regions of the interior of the container.

4. Apparatus as claimed in claim 1, in which the container further comprises an outlet for the flowable material including a material eductor unit.

5. Apparatus as claimed in claim 4, in which the material eductor unit comprises means for feeding a compressed gas to the flowable material as the flowable material passes through the outlet.

6. Apparatus as claimed in claim 5, in which the material eductor unit comprises a venturi unit whereby compressed gas applied thereto acts to at least assist the flow of flowable material through the outlet of the container.

7. Apparatus as claimed in claim 6, in which the pressure of the compressed gas is sufficiently high enough to be able to pump the flowable material from the container.