US 3681862 A
Description (OCR text may contain errors)
United States Patent De Koning et a].
[ 1 SUCTION DREDGER HAVING PLURAL PUMPS AND PLURAL ARTICULATED PIPE SECTIONS  inventors: Jan De Koning, Amsterdam; Tjako Aaldrik Walters, Utrecht, both of Netherlands  Assignee: N.V. Ingenkursbureau voor Systems en Octrooien Spanstaal", Rotterdam, Netherlands 22 Filed: Nov. 17, 1969 21 Appl. No.: 877,141
 Foreign Application Priority Data 3,407,520 10/1968 Donkers ..37/58 til [451 Aug. 8, 1972 FOREIGN PATENTS OR APPLICATIONS 6,501,405 8/1966 Netherlands ..37/58 980,549 1/1965 Great Britain ..37/58 3 l .041 10/1933 Netherlands ..37/58 Primary Examiner-Robert E. Pulfrey Assistant Examiner-Clifford D. Crowder Attorney-Imirie, Smiley, Snyder and Butrum ABSTRACT Suction dredger for sucking up a particulate material such as sand. A suction pipe is inserted into a body of sand below the bottom of a body of water to withdraw water-sand suspension having a desired concentration of sand in such suspension. At the lower end of the pipe, the sand is drawn in at very high concentration and at some level above this point water is separately introduced so that a desired concentration is obtained. The suction pipe consists of at least two pipe parts swingably connected to each other. The maximum suction output of the submerged pump is obtained by swinging the frame supporting the pump into a vertical position.
4 Claim, 3 Drawing Figures PATENTED M1 8 I972 SHEET 10F 2 TJ'AKO A. W LTERS PATENTEDAUB 8:912 3.681.862 sum 2 c; 2
INVENTORS JAN 62 KoNiNG TJAKO A. WdLTERs BY M MQ, Mama ATTK m was SUCTION DREDGER HAVING PLURAL PUMPS AND PLURAL ARTICULATED PIPE SECTIONS The invention relates to an improvement of a suction dredger comprising a pump and a suction pipe which is connected to said pump and which has at least one first nozzle for spoil at its lower end and at least one second nozzle mainly for water between the pump and said lower end, wherein said pump is mounted on a frame movably suspended from a ships body which is lowerable and liftable together with said pump relatively to said ships body, at least said first suction nozzle being arranged at an end part of said suction pipe.
Such a suction dredger is known.
In said known suction dredger said end part of said suction pipe is movably connected with said frame supporting said submerged pump. However, in said known suction dredger this pump cannot always be positioned at its maximum depth, at which maximum depth the pump has its greatest suction output, owing to the end part of the suction pipe being jammed in solid ground, for instance solid mud or clay covering the spoil or sand to be sucked up.
The invention has the object to provide a suction dredger in which this drawback is avoided.
The invention provides a suction dredger of the kind mentioned above, wherein said end part of the suction pipe communicates with an inlet part of said pump by means of an intermediate part of said suction pipe which is swingably connected to said inlet part as well as to said end part.
Preferably the intermediate part of the suction pipe consists of at least two parts swingably connected to each other.
The invention further has the object to provide a method of suction dredging particulate material below the bottom of a body of water, which comprises the steps of:
inserting the lower end of a suction pipe into a body of the material below the level of the bottom of a body of water,
communicating the suction pipe with a submerged suction pump to withdraw the particulate material through the lower end of the pipe commingling water with the particulate material at a point along the length of the pipe which is spaced above the lower end thereof,
measuring the concentration of particulate material in the particulate material-water mixture being withdrawn through the pipe above said point at which the particulate material and water are commingled,
maintaining the concentration of particulate material in the particulate material-water mixture within predetennined limits,
and adjusting the level of said submerged suction pump independent from the position of the lower end of the pipe.
Preferably the pump is maintained at its maximum depth.
The above mentioned and other features of the invention will be illucidated in the following description with reference to the accompanying drawings, wherein:
FIG. 1 is a preferred suction dredger according to the invention,
FIG. 2 is another preferred suction dredger according to the invention and FIG. 3 is a part of the suction dredger of FIG. 2.
The suction dredger according to the invention of FIG. 1 comprises a ship's body 1, a lowerable and liftable supporting frame 26 swingably mounted about a horizontal axis 25 on the ships body 1, a pump 3 fixed to said frame 26. The discharge pipe 2 of said pump 3 is swingably connected to the inlet pipe 44 of a pump 28 mounted in the ships body I. The discharge pipe 2 is swingably connected about said axis 25. The pressure side of the pump 28 communicates with a conveying pressure line 1 l.
The inlet pipe 27 of the pump 3 communicates through a flexible conduit 29 with an intermediate part 4 of the suction pipe 30, which in turn communicates through a flexible conduit 31 with an end part 24 of the suction pipe 30. The intermediate part 4 is swingably connected to the inlet pipe 27 and the end part 24 by means of pivot hinges 32 and 33.
The frame 26 and the suction pipe 30 are suspended from the ships body I by means of winches l0 and 8, 9 and cables 7 and 5, 6 for adjustably lifting and lowering them.
The lower end of the end part 24 has a first suction nozzle 22 for sucking in mainly spoil 34 surrounding said lower end and being fluidized. This lower end is covered by a cage 21.
A second suction nozzle 15 for taking in mainly water is provided in the intermediate part 4, the quantity of water taken in being adjustable by adjusting the flow area of suction nozzle 15 by means of a slide remotely controlled from the ships body for controlling the concentration of spoil in the spoil-water mixture sucked up by the pump 3. The value of this concentration is measured by means of a concentration sensitive pick up 45 incorporated in the intermediate part 4.
In the method according to the invention the pump 3 is submerged at the maximum depth obtained by lowering the frame 2 into the vertical or substantially vertical position, in order to use the maximum suction output of this pump 3. [t can be positioned at its maximum depth corresponding with vertical position of frame 26 independently from the position of the end part 24, 24'. FIG. I shows that the end part 24 of the suction pipe is jammed in a narrow gap 13 of solid ground 18.
The suction dredger of FIGS. 2 and 3 corresponds with that of FIG. 1 with the exception that the intermediate part 4 consists of two parts 40 and 4b instead of one rigid part, and that the second suction nozzle 15 is provided in the end part 24 in a particular way instead of in the intermediate part 4.
The intermediate parts 4a and 4b communicate with each other through a flexible conduit 37 and are swingably connected to each other by means of a pivot hinge 33. The intermediate parts 40 and 4b are suspended from the ships body 1 by means of winches 9a and 9b and cables 6a and 6b.
The end part 24 (FIG. 2) consists of an inner tube 23 communicating with the intermediate part 4, a pipe 16 telescopically slidable relatively to the inner pipe 23 by means of a remotely adjustable hydraulic jack 38 and of a jacket 17 surrounding the inner pipe 23 and the slidable pipe 16, and being connected to the inner pipe 23. The jacket 17 is provided with water inlets 39 at its upper end and with a first suction nozzle 22 for spoil at its lower end. Water 40 entering the jacket 17 through inlets 39 flows between jacket 17 and pipes 23 and 16 downwards and enters the slidable pipe 16 through a periphery gap between jacket 17 and the lower edge of slidable pipe 16, said gap forming the second suction nozzle for water. This water and the spoil entering the jacket 17 through the first suction nozzle 22 forms a water-spoil-mixture sucked up by pump 3. The lower edge of the slidable pipe 16 is kept in the vicinity of the level to which the spoil enters the jacket owing to suction of pump 3 and owing to the pressure available in the fluidized spoil 42 at the outside of the suction pipe 30. in the method according to the invention this pressure is picked up by means of pressure sensitive pick up 20. For controlling the concentration of spoil in the water-spoil-mixture the distance between the first suction nozzle 22 and the second suction nozzle 15 or the lower end of slidable pipe 16 is adjusted in dependence on the pressure picked up by means of pick up or in dependence on the measured value of the concentration picked up by means of above mentioned concentration sensitive pick up 45.. This distance is adjusted by means of hydraulic jack 38. The pressure picked up by pick up 20 is about equal to the sum of the weights of spoil column l-l, and water column [-l,,.
Since the cost price of the suction dredger increases sharply with the length of the supporting frame 26, and it is important that the pump 3 should be adapted to be mounted at the maximum depth, it is a great advantage of the suction dredger according to the invention that the supporting frame 26 can be disposed vertically or substantially vertically irrespective of the position of the end part 24.
What we claim is:
1. A suction dredger assembly comprising in combination:
a dredger vessel and a first pump mounted on said vessel, said first pump having an inlet for receiving a suspension of dredging spoil in water and an outlet for discharging such suspension;
frame means carried by said vessel and a second pump mounted on said frame means, said second pump having an inlet and having an outlet connected to the inlet of said first pump about a substantially horizontal pivot axis located remote from said inlet of the second pump;
means for raising and lowering said frame means relative to said vessel about said pivot axis whereby the inlet of said second pump may be disposed at a desired depth within the body of water supporting said vessel;
suction pipe means connected to the inlet of said second pump for inducting dredger spoil and forming a suspension thereof in water which is delivered to said second pump, said suction pipe means comprising a rigid free end section adapted to be inserted deeply into an underwater body of dredger spoil and an intermediate section extending between said end section above the level of dredger spoil and the inlet of said second pump, said intermediate section being swingably connected both to said end section and to the inlet of said second pump whereby said frame means may be lowered at least substantially to its maximum depth without requiring movement of said end section.
2. A suction dredger assembly as defined in claim 1 wherein said intermediatesecg It comprises a pair of suction pipe sections swlnga y connected to each other.
3. A suction dredger assembly as defined in claim 2 wherein said suction pipe means presents a first suction nozzle at the free end of said end section and a second suction nozzle within said end section in selectively spaced relation to said first suction nozzle to effect said formation of suspension.
4. A suction dredger assembly as defined in claim 1 wherein said suction pipe means presents a first suction nozzle at the free end of said end section and a second suction noule within said end section in selectively spaced relation to said first suction nozzle to effect said formation of suspension.
UNI'IED STATES PATEN'I OFFICE CERIIFICA'IE 0F CORRECTION Patent No. 3 I 681 I 852 Dated Aug 8, 1972 lnventofls) Ian de Koning and Tjako Aaldrik Wolters It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
In the assignee's name "Systems" should be Systemen Signed and sealed this 9th day of January 1973.
EDWARD M.FI.,ETCIIIZR,JR. ROBERT (IOT'ISCHALK Attesting Officer Commissioner of Patents FORM PO-OSO (10-69] USCOMWDC eoawhpfig w u s oovznnmzm murmur, ornc: lava o-ass-au