US3794388A

US3794388A - Method and arrangement for conveying particulate material from a lower level to an upper level

Info

Publication number: US3794388A
Application number: US00178655A
Authority: US
Inventors: M Westenberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-09-14
Filing date: 1971-09-08
Publication date: 1974-02-26
Anticipated expiration: 1991-02-26
Also published as: GB1360849A; NL7111355A; AU3345771A; AU466648B2; SE385109B; FR2107157A5; BE771299A; CA943580A

Abstract

The grit used for blast-scouring the interior of a tank or compartment in a ship, accessible only through a manhole, is entrained and raised by suction off the floor of the tank by a small distance, and is thereupon entrained and conveyed to the level of a deck above the tank by pneumatic pressure.

Description

United States Patent 1191 Westenberg 1 Feb. 26, 1974 METHOD AND ARRANGEMENT FOR 3,320,727 /1967 Farley et al. /327 R x CONVEYING PARTICULATE MATERIAL 3,618,302 11/1971 Cornet! 15/327 R X 3,454,307 7/1969 Bishop 302/55 FROM A LOWER LEVEL To AN UPPER 936,222 10/1909 Dalzell 302/58 x LEVEL 918,795 4/1909 Thurman 302/58 [76] Inventor: Martin Westenberg, Klosterstrasse 352 4 uc am..... 34 Frechen Germany 2,744,792 5/1956 Finn 302 59 x l 71 [22] Wed Sept 9 FOREIGN PATENTS OR APPLICATIONS [21] APPI' 178,655 151,958 0/1961 u.s.s.R.....- 1. 302/58 768,227 8/1934 France 302/21 Foreign Application Priority Data 709,703 3/1950 Great Bntam 302/58 Sept. 14, 1970 Germany P 317.2 Apr. 3, 1971 Germany P 21 16 462.5 P Blmk Assistant Examiner-W. Scott Carson I 52 us. c1 302/58, 214/15 R, 302/21, Atmmeyr Agent Striker 302/55, 302/57, 417/79 [51] Int. Cl. Bg 53/28, B65g 53/42 57 ABSTRACT [58] Field of Search 15/327 R, 327 C, 340, 347,

15/348; 214/12-14, 15 R, 15 302/21 25 he grit used for blast-scourmg the 1nter1or of a tank 53 55 51 417/79 83 234 or compartment in a ship, accessible only through a 1 manhole, is entrained and raised by suction off the [56] References Cited floor of the tank by a small distance, and is thereupon entrained and conveyed to the level of a deck above UNITED STATES PATENTS the tank by pneumatic pressure. 276,879 5/1883 Randolph 302/58 X 590,084 9/1897 Blanchard 214/14 X 5 Claims, 4 Drawing Figures v r PATENHBFEBZSISH SHEET 2 0F 4. v

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PAIENTEDnazsmn SHEET 3 BF 4 FIG.3

METHOD AND ARRANGEMENT FOR CONVEYING PARTICULATE MATERIAL FROM A LOWER LEVEL TO AN UPPER LEVEL BACKGROUND OF THE INVENTION The present invention relates generally to the conveying of particulate material, and more particularly to the conveying of particulate material from a lower level to an upper level. Still more particularly the invention relates to the removal of grit used in blast-scouring of the interior of a tank or compartment in a marine vessel, to the level of an upper deck above the compartment.

Tanks or compartments in marine vessels, especially in tankers, must be cleaned at regular intervals. This is well known and it is also known that conventionally such cleaning is carried out by a blast-scouring method, analogous to sand-blasting but using grit particles of crystalline sharp-edged configuration which are relatively heavy, having a specific weight on the order of 2.2-2.6. Of course, such particles accumulate on the bottom of the tank during the scouring operation, and

must naturally be removed before the tank can be reused.

Heretofore the height of such tanks has been relatively small, for instance on the order to [6 meters. With tanks of this height it was a relatively simple matter to remove the grit by introducing a suction conduit through the manhole into the tank and entraining and removing the particles by suction. However, the trend in the construction of tanker vessels is towards larger dimensions, in order for a single vessel to be capable of carrying very large tonnages of freight, that is oil or the like. These larger vessels have tanks which are substantially higher than those heretofore customary, and because of the large quantities of air which must be moved at high speed in order to be'able to withdraw the grit from the interior of the tanks by suction, it has been found that this approach is no longer feasible with these newer, higher tanks. Consequently, the way this problem has been handled recently is to bring such tankers into a drydock and to cut out a part of the hull plating to afford access to the interior of the tank or tanks, with the grit then being removed through the resulting opening. Subsequently the opening was welded shut again. It is hardly necessary toemphasize that this approach is not only expensive and time-consuming, but also risky to a certain extent because the repeated cuttingopen and re-welding of the hull plating may lead to dangerous structural weaknesses. Nevertheless,'these significant disadvantages have had to be accepted until now, because a more advantageous, economical and simpler removal of the grit particles from the tank or tanks was not available.

SUMMARY OF THE INVENTION Accordingly, it is a general object of the present invention to overcome the disadvantages of the prior art.

More particularly it is an object of the present invention to provide a method of removing such grit particles which is not possessed of the disadvantages outlined above.

A further object of the invention is to provide an arrangement for affording the removal of such grit particles, which arrangement also overcomes the disadvantages of the prior art.

A concomitant object of the invention is to provide for the simple, rapid and reliable removal of the grit, not only in small or conventional tankers but also in large or very large tankers having tall or very tall tanks, and to afford such removal in an economical manner.

In pursuance of the above objects, and of others which will become hereafter, one feature of the invention resides in a method of conveying particulate material from a lower level within a compartment aboard ship to an upper level on a deck above such compartment, which method comprises, briefly stated, the steps of raising the particulate material by suction above the lower level by afraction of the distance between the lower and upper levels, to an intermediate level where it is entrained and conveyed by pneumatic pressure to the upper level. At the upper level the thus-conveyed material is recovered by separating it from the entraining air stream.

In other words, the suction required for initially entraining the grit at the bottom of the tank need only be such as to lift the grit a relatively small distance,

whereas-once the grit is thus entrained-the actual work of raising it almost the entire height of the tank to the deck above the tank and to the device for recovering the grit from the entraining air stream, is carried out by a pneumatic-pressure conveying device, by means of which the grit can be economically and reliably conveyed even where substantial heights are involved, that is where substantial level differences must be bridged.

. It is advantageous according to the present invention to provide a mobile separator. and recovery unit which can be placed on the deck of the ship, and to accommodate the suction and pneumatic-pressure conveying device in a bottle-shaped or cylindrical housing which can be lowered into the tank through the manhole of the latter.

However, according to the invention it is also possible to connect the mobile separator and recovery unit with a suction conduit which can be inserted into the tank through the manhole thereof, and whose lower open end is surroundedby a substantially frustoconical ring whose largest diameter faces upwardly, which ring is in turn surrounded by a substantially cylindrical ring concentric therewith and whose lower edge defines with the upper edge of the frustoconical ring an air gap so that air drawn into the inlet of the suction conduit must at least in part pass through this annular air gap, thereby assuring that a relatively small volume of air is capable of properly entraining the gritand conveying it to the unit on the deck of the ship even over substantial heights.

In so far as this latter embodiment of the invention is concerned, a currently preferred construction provides for the upper open end portion of the suction conduit to be connected with a spherical container which can be placed on the deck of the ship, by means of a swivel joint which is air tight, and with a connecting nipple being provided which connects the container with a conduit leading to the separating and recovery unit.

duit extending to the separator and recovery unit. With this construction the initial quantities of grit which are entrained when the unit is placed into operation, will become deposited on the inner wall of the container, on the inner wall of the suction conduit and on the inner wall of the outlet nipple, and will form a channel through which the subsequently entrained grit will pass without being able to scour and damage the aforemen- BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic vertical cross-section through a vessel provided with an embodiment according to the present invention;

FIG. 2 is a diagrammatic detail view illustrating details of the embodiment according to FIG. 1;

FIG. 3 is a diagrammatic longitudinal section through a further embodiment of the invention; and

FIG. 4 is a diagrammatic side-elevational view embodiment of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Discussing now the drawing in detail, and firstly the embodiment which is illustrated in FIGS, 1 and 2, it will be seen that reference numeral identifies diagrammatically a tanker vessel which is shown in crosssection. The wall 12 defining a tank of the tanker vessel is here also illustrated as simultaneously constituting the hull plating, although this is not always the case. In any case this if of no consequence for an understanding of the present invention. Reference numeral 14 identifies the deck of the vessel above the tank, and the bottom of the tank and of the hull is identified with reference numeral 17.

Such a tanker will ordinarily have of course more than one tank or compartment, but only one is illustrated because this is all that is necessary for an understanding of the invention. Each tank will be provided with a manhole 15 through which access may be had from the tank to the deck, and which according to applicable standards must have a minimum diameter of 550 mm.

When the wall 12 of such a tank is scoured by blastscouring using the earlier-discussed grit particles 16, a large quantity-depending upon the height of the tank ten tons or more per individual tank-of such particles 16 will have accumulated on the bottom 17, which particles must of course be removed before the tank can be reused. This is accomplished by the arrangement illustrated in FIG. 1 and in more detail in FIG. 2.

It will be seen that the arrangement of this embodiment utilizes a separator and recovery station 18 where the grit is separated and dust removed from the entraining medium; this station 18 can be placed on the deck 14 and is mobile so that it can be moved from manhole to manhole. There is further provided a bottle or cylindrical unit 20 which can be lowered through the manhole 15, being so dimensioned that its maximum diameter is at least slightly smaller than the diameter of the manhole. In the upper part of the housing 20 there is provided a pneumatic suction conveying device 24 which is connected with a suction conduit 21 by means of which an operator 22 shown in FIG. 1 picks up the grit 16 in the same manner in which a vacuum cleaner picks up particles.

In the upper portion 24 of the unit 20 the entrained grit, which is picked up by an air current supplied via a conduit from the station 18, is separated from this air current.

The lower part of the unit 20 is provided with a pneumatic-pressure conveying device 26 which receives compressed air entering through the manhole 15; the device 26 entrains the grit separated from the suction air in the upper portion 24 of the unit 20 and conveys it under pressure through a conduit 27 up through the manhole 15 and to the station 18 where the grit is separated from the entraining air and is supplied via a conduit 28provided with a closure valve 29into a reservoir which is here illustrated as a separate barge or the like.

Details of theembodiment in FIG. 1 are shown in FIG. 2 where it will be seen that the unit 20 has a substantially cylindrical housing whose maximum crosssection including the connecting nipples for the various conduits is slightly smaller than the smallest diameter of the manhole 15. The unit 20 may be provided with an eye 50 or a hook or the like, to which a steel cable or similar suspending means 51 may be secured, so that it can be lowered through the manhole 15 until it is immediately adjacent the bottom 17 of the tank, or the layer of grit on the bottom 17.

A suction conduit 21 is connected via a rapidconnect and rapid-disconnect coupling, for instance a bayonet coupling 32 of known construction, with a chamber 31 provided in the upper portion 24 of the unit 20. The chamber 31 is further provided at the upper side of the unit 20 with a nipple 33 also provided with a rapid coupling for a suction conduit 34 which extends through the manhole 15to a suction air filter 35 constituting a part of the station 18. A blower 37, for instance a rotary piston blower, is provided with whose suction side the conduit 34 is connected, the blower 37 being connected with the filter 35 (which in turn is connected with the conduit 34) via a conduit 36.

The entrained grit 16 is separated from the suction air stream in the chamber 31 of the unit 20 and accumulates in this chamber 31. Dust removed in the filter 35, and any grit which may still be entrained at this point, are discharged via an outlet 38 from the filter 35 into the conduit 28. Reference numeral 39 designates the connecting nipple of the conduit 34.

There is further provided in the unit 20 a chamber 41, being located in the lower part of the unit 20 and cooperating with the pneumatic-pressure conveying device 26. The chamber 41 is connected via the diagrammatically illustrated conduit 40 and a connector tom of the chamber 41 in order to fluidize the grit therein and a portion of the compressed air is used directly for entraining this fluidized grit and conveying it through the conduit 44 which is connected at the upper side of the unit 20 with a nipple 45 which is provided with a rapid coupling for the connection of a conduit 46 which extends through the manhole to a filter 47 of the unit 18. In this filter 47 the grit is separated from the stream of air and supplied via an outlet 48 to the conduit 28.

Of course, the

chambers

31 and 41 must be in communication in order to transfer the grit accumulating in the chamber 31 into the chamber 41. This is achieved via a conduit 54 in which a valve, such as a slide valve 55, is provided which is normally closed because there is underpressure in the'chamber 31 and overpressure in the chamber 41. To effect transfer of grit from the chamber 31 into the chamber 41, an automatic control opens the valve 55 when a predetermined amount of grit has accumulated 'in the chamber 31, and simultaneously the supply of compressed air via the conduit 40 and the stream of suction air via the conduit 34 are switched off. There is now no pressure differential in the

chambers

31 and 41 and the grit accumulated in the former can fall into the latter when the valve 55 is opened, whereupon the valve 55 is closed again and of grit by the operator re-commences. At the same time the grit accumulated in the chamber 41 is conveyed to the station 18 via the conduits 44 and 27'.

The station 18 itself is advantageously mounted on a frame 60 provided with wheels or rollers 61 so that it can be moved to the different manholes 15 associated with the different tanks of a vessel.

The control device for controlling the various valves is not illustrated because it is known per se and not believed to require detailed discussion. It is, however, advantageously made a part of the station 18 so that only the unit need be located in the tank and only the rope 51 or cable 51, the conduit 34, the conduit 40, the conduit 27, and the valve-control conduits need pass through the manhole 15. I A device such as illustrated in FIGS. 1 and 2 is capable of conveying without any difficulty an amount of approximately ten tons of grit per hour, and the energy required is relatively low because a pneumatic-pressure conveying device requires substantially smaller amounts of air even at great conveying heights than the suction conveying devices which have been used heretofore.

The embodiment illustrated in FIGS. 3 and 4 is somewhat different from that of FIGS. 1 and 2. Here, a separating and recovering station 65 is provided on deck of the ship as shown in FIG. 4, and serves on the one hand for supplying suction air to initially entrain the grit and on the other hand to segregate the entrained grit from the stream of air. The suction air is applied through the suction conduit 66 shown in FIG. 3 which is lowered through a manhole into the tank and which in the illustrated embodiment has an upper tubular portion 67 and a lower tubular portion 68 which is telescopically guided in the portion 67 with slight play. An externally arranged cylinder and piston unit 70 has its cylinder connected to the upper tubular portion 67 and its piston rod 71 to the lower tubular portion 68. A nonillustrated control device controls the operation of the unit 70 in a sense telescoping the

tubular portions

67 and 68 apart or together, depending upon the length required of the suction conduit 66, so that in this manner the length of this conduit can be accommodated to the height of a given tank. Also, it may be necessary to lengthen the conduit 66 when the latter is pivoted in lateral direction in a manner to be discussed subsequently, in order to reach additional portions of the tank bottom. In the illustrated embodiment the upper tubular portion 67 as well as the lower tubular portion 68 are composed of several tubular sections which are connected by flanges 69.

In the embodiment of FIGS. 3 and 4 the conduit 66 is provided with a suction head utilizing a frustoconical ring 72 which so surrounds the lower open end and inlet of the tubular portion 68 that its largest diameter faces upwardly. A cylindrical ring 73 surrounds and is concentric with the tubular portion 68 and the ring 72 and is connected with radial ribs 74 to the tubular portion 68. The lower edge of the cylindrical ring 73 somewhat overlaps the upper edge of the ring 72, defining therewith an annular air gap. With this construction the suction air entering in the direction of the arrow 75 v must pass through the gap between the

rings

72 and 73, and in the region designated with the arrow 76 the air receives a strong acceleration due to the small crosssection of the annular air gap, thereby assuring that the grit will be subjected on the bottom of the tank to substantial turbulence so that it can be picked up better and'carried by the air stream into the suction conduit 66. It has been found, in fact, that this configuration of the suction head not only improves the pick-up of the grit from the bottom of the tank, but also the conveying of the grit through the suction conduit 66 to the station 65, so that the embodiment of FIGS. 3 and 4 permits the conveying of the grit by suction even over very substantial heights which heretofore could not be handled with the suction devices of the prior art.

It is advantageous, as shown in the drawing, if the upper end portion of the tubular portion 67 is connected to aball-s'haped container 77 which has secured to it at 79 the diagrammaticallly illustrated feet 78 on which it is supported on the deck of the vessel above the manhole. The connection of the tubular portion 67 with the container 77 is effected via an airtight swivel joint 81 at 79, so that the conduit 66 can be swiveled with reference to the container 77 to permit its inlet opening to be moved to different parts of the tank bottom.

A connecting nipple 83 is provided on the container 77 by means of which the latter can be connected with the diagrammatically illustrated (see the broken line) conduit 87 which leads to the station 65. According to the invention this connecting nipple 83 utilizesa first tubular portion 84 which extends from the interior to the exterior of the container 77 and has at its outer end a transverse wall 82 through which a second tubular portion of smaller diameter and identified with reference numeral 85 extends in coaxial relationship, being provided at its outer free end with a flange 86 at which the conduit 87 is connected. Of course, the conduit 87 can also be connected in other ways, for instance by screw threads or the like.

The dots in the interior of the container 77 and of the nipple 83 are intended to indicate that and how on initial operation of the device in FIGS. 3 and 4 the picked-up grit will form deposited layers on the inner walls of the container 77 and of the nipple 83, forming a flow channel for subsequently picked-up grit. This is highly advantageous because it means that the thusdeposited layers of grit prevent contact of the subsequently entrained grit with the inner surfaces of the respective walls, so that the sharp-edged grit cannot scour and eventually damage these walls. Because of the boundary layer friction a thin layer of such grit will also become deposited on the walls of the

tubular portions

67 and 68 and of the conduit 87, providing similar protection.

A connecting nipple 88 connects the conduit 87 with the separating chamber 89 of the station 65 shown in FIG. 4, and a compressed air filter 91 is diagrammatically illustrated in the chamber 89 and serves for continuous separation of entrained grit from the stream of entraining air.

Chamber 89 is provided with feet 90 by means of which it rests on glides 92 which permit the station 65 to be moved from place to place. Outlet opening 93 at the lower end of the chamber 89 permits the removal of the separated grit. A non-illustrated discharge compartment in the container 89 permits the removal of the separated grit so that it is possible to provide for continuous operation of the device without having to stop the operation when the accumulated grit is to be removed. Such compartments are already known.

A rotary piston suction type blower 96 provides the suction air stream for entrainment of the grit, and it is connected with the chamber 89 via a conduit 94 in which a fine filter 95 is accommodated. This means that in the event the main filter 91 should for any reason become inoperative, the fine filter 95 will almost immediately become clogged and lead to automatic switching-off of the unit. The air which leaves the fine filter is almost completely free of dust and other contaminants of a particulate nature.

lt will be appreciated that various modifications are possible and will suggest themselves to those skilled in the art. For instance, the ring 72 may have a somewhat different external contour than that illustrated, and the ring 73 can also be varied in its configuration, as long as it is assured that the necessary acceleration and turbulence of the air stream is achieved which is necessary for picking up the grit and conveying it with the same or substantially the same efficiency and effectiveness obtained with the construction discussed with reference to FIGS. 3 and 4. It is pointed out in this connection that the suction head of FIGS. 3 and 4 in effect provides for the same pneumatic pressure conveyance of material which in FIGS. 1 and 2 is obtained with the device 26, because of the significant acceleration with the suction air undergoes in passing through the annular air gap between the

rings

72 and 73.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a device for conveying particu late material from a lower to an upper level, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that from the standpoint of prior art fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. An arrangement for conveying particulate material from a lower level within a compartment to an upper level above such compartment, comprising first means for entraining and conveying said material by suction, and second means for recovering the conveyed material at said upper level, said first means comprising a suction conduit adapted for insertion into said compartment from said upper to said lower level and having a normally lower outlet opening; and a suction head comprising a frustoconical ring surrounding said outlet opening with its larger diameter portion facing upwardly, and a cylindrical ring concentric with said frustoconical ring and having a lower edge defining with an upper edge of said frustoconical ring an annular air gap.

2. An arrangement as defined in claim 1, wherein said particulate material is grit introduced into said compartment during a blast-scouring operation.

3. An arrangement as defined in claim 1, said suction conduit having an upper end portion; and further comprising a ball-shaped container normally supported on said upper level;.and an air-tight swivel joint connecting said upper end portion with said container.

4. An arrangement as defined in claim 3, said container having an interior; and further comprising a connecting nipple for connecting said container with said third means, said connecting nipple having a first tubular portion of larger diameter extending from the interior to the exterior of said container, a second tubular portion of smaller diameter coaxial with said first tubular portion and extending from the interior thereof outwardly beyond a free end of the same, and a coupling on said second tubular portion outside said first tubular portion for connection with said third means.

5. An arrangement as defined in claim 1, said suction conduit comprising at least two telescoped sections which are extendable and retractable for varying the length of said suction conduit means.

a a: a:

Claims

3. An arrangement as defined in claim 1, said suction conduit having an upper end portion; and further comprising a ball-shaped container normally supported on said upper level; and an air-tight swivel joint connecting said upper end portion with said container.