Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
  • E02F3/8833—Floating installations
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
  • E02F3/8808—Stationary installations, e.g. installations using spuds or other stationary supports
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/88—Dredgers; Soil-shifting machines mechanically-driven with arrangements acting by a sucking or forcing effect, e.g. suction dredgers
  • E02F3/90—Component parts, e.g. arrangement or adaptation of pumps
  • E02F3/92—Digging elements, e.g. suction heads
  • E02F3/9243—Passive suction heads with no mechanical cutting means
• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F7/00—Equipment for conveying or separating excavated material
  • E02F7/005—Equipment for conveying or separating excavated material conveying material from the underwater bottom

Definitions

• Dredging may be performed through nozzles placed in contact with the sea bottom at a certain first position, from which it sucks up an amount of sediment, forming a crater in the sea bottom.
• the sediment will tend to slide into the crater as it becomes deeper and the crater walls will become steeper
• the nozzle becomes plugged and/ or get stuck
• US patent N 3,693,272 desc ⁇ bes a system (an apparatus) that principally enables dredging at (from) large depths.
• the solution has the limitation, however, that it relates to a mainly closed system that will be vulnerable to e g. large rocks and other extraneous matter, and it is not easily available for inspection and maintenance. Thus, it is not well suited for the purpose of the present invention where a significant variation in particle size must be expected, with rocks of substantial sizes constituting an essential element.
• US patent No. 3,815,267 also describes a closed system for sucking up sediment from a sea or ocean bottom, and has in general the same disadvantages or limitations as the above mentioned patent, if used for sediment having a large variation of particle size.
• US patent No 1 ,468, 199 describes a method and a device for dredging by means of a semi- submersible, open container operating at atmospheric pressure, and a suction pipe that is lowered to the sea bottom, wherein the suction force is provided entirely through the difference in liquid pressure between the surface and the outlet of the suction pipe into said open container.
• the patent also describes equipment to lift the sediment up to the level of the water surface
• Figure 1 shows a schematic view of one embodiment of the invention
• Figure 2 and 3 shows different variants of some details of the invention
• Figure 4 is a schematic view of an embodiment of the invention for a particular application
• Figure 5 shows a particular embodiment of a certain detail of the invention
• Figure 6 shows an extra functionality related to the embodiment of the invention illustrated in Figure 2.
• Figure 1 shows schematically means suited for conducting the invention in relation to dredging an area of the sea bottom 1 or the bottom of a water dam.
• a hose or pipe 2 is arranged to transport sediment from the bottom 1 to a container 3 that is arranged in a way where the level 4 of water and sediment within the container is lower than the natural water level 5 outside the container.
• the container 3 is preferably open to the surroundings and is under any circumstances arranged in a way so that maintenance and repair workers have easy access.
• In connection to the container 3 means are arranged to transport the sediment further in one or more fractions according to particle size.
• the container 3 may, for example, be arranged as part of a barge or have the form of a tank connected to e.g. the leg of an oil platform. It is preferred that the vertical level of the container may be adjusted according to varying requirements.
• a grating 6 is arranged at a level between the pipe outlet 7 and the level 4 of water and sediment in the container.
• rocks and particles with a smallest diameter larger than the grating openings will be held back on the grating while other sediment will pass therethrough.
• the sediment consisting of large particles is denoted the coarse fraction 8
• the sediment consisting of smaller particles is denoted the fine fraction 9.
• the fine fraction 9 may be removed separately by means of equipment that need not be dimensioned to handle large rocks or other large particles.
• Such means may comprise conventional pumps or the like.
• Figure 1 shows such a pump 10 with a pipe 11 connected thereto and arranged to transport the fine fraction 12 together with a regulated amount of water, to a separate tank 13, which e.g. may be located on a barge.
• the fine fraction may alternatively be pumped back to a different location under water or to a special land fill, possibly to an intermediate station for purification and subsequent further transportation.
• the further treatment of the fine fraction and/ or the coarse fraction is, however, not subject of this invention.
• Figure 1 shows a digging or lifting device 14 arranged to take care of the coarse fraction 8 held back on the grating 6.
• the coarse fraction may alternatively, in a controlled manner, be dropped back to a convenient location under water or placed in a separate container (not shown) e.g. on a barge or on a land fill.
• Figure 1 depicts a particular suction manifold 15 (also denoted a "saxophone head") with a number of openings or slits 16 at its lower end, and with an opening 17 at a vertical distance from the openings 16, arranged at the free end of the saxophone head. While the openings 16 at any time will suck in sediment and varying amounts of water, the opening 17 will always only suck in water. The lower the concentration of sediment in the pipe becomes, the larger the velocity and the larger becomes the sucking forcing.
• the saxophone head has the property that the sucking force is determined by the velocity with which the water flows in the pipe. This way the suction manifold 15 is self-regulating and will not easily become blocked.
• the suction manifold 15 With a convenient dimensioning of the suction manifold 15, i.e. a sufficient vertical distance between the openings 16 and the opening 17, the suction manifold will also function during and subsequent to a slide-out of sediment into the crater that the suction manifold may generate during dredging. This is due to the fact that the opening 17 is elevated to a level where it will always be free and able to suck water, ensuring that the sediment concentration in the nozzle 15 and the pipe 2 will rapidly reduce even subsequent to a near complete blockage.
• a sufficient distance may be in the order of 2-6 metres.
• the suction manifold shown m Figure 1 provides, in use, the important advantage that to a large extent it may be left alone on the sea bottom for shorter or longer pe ⁇ ods, and does not need to be continuously controlled
• buoyancy means may be connected to the suction manifold itself and/ or to parts of the pipe 2
• When dredging the suction manifold will gradually sink down into a self-created crater m the sea-bottom, while maintaining a self-regulating concentration of sediment as mentioned, the risk of blocking of pipe or suction manifold being as good as eliminated
• Figure 2 shows another embodiment of the container 3 Here there is no grating holding back the largest particles, instead there a pipe 18 is arranged to pump such sediment away This pumping may be effected by means of an ejector pump 19 connected to the pipe 18.
• An advantage of this way of handling the coarse fraction is that it to a larger extent it may be performed as a continuous process, the disadvantage being that it provides a less sharp distinction between the coarse and the fine fraction, as some fine particles will necessarily follow the coarse fraction
• the fine fraction will according to Figure 2 be removed by means of a conventional pump 10
• Figure 3 shows a still further embodiment of the container 3, where a substantially vertical tubmg 20 with a hatch 21 is arranged at the bottom of the container Normally the hatch is closed, and with the absence of a grating in the container, large rocks will collect close to the hatch, while finer particles will to a larger extent, be dispersed in the water above According to needs or according to regular intervals the hatch is temporarily opened, so that the rocks fall back to the bottom below the container. During opemng of the hatch there is fluid communication for water mside and outside the container 3.
• Figure 4 shows a va ⁇ ant of the invention in connection with a dam 22
• Many of the details corresponds to the details found in Figure 1, like the gratings 6 in the container 3 to hold back the largest particles/ rocks 8.
• a pipe 23 for transportation of the fine fraction together with a convenient amount of water extends to a position downstream of the dam 22, which position is one at a lower level than the level 4 in the container 3.
• the pipe 23 is extended with a slotted pipe 24 which has slots allowing particles to be sluiced into the tubing along with a controlled amount of water.
• This slotted pipe (sediment sluicer) is first described in "Gemini" No. 3, December 1994 and in “Hydropower and Dams", March 1995.
• amounts of the least contaminated water may be pumped off from this part of the container by means of a pump (not shown) . If the water level becomes so low that the desired ratio in the pipe 23 cannot be reached, more water may be allowed to enter the container 3.
• FIG 5 shows an alternative design of a suction manifold 25 with two openings or two sets of openings 16', 17'.
• the suction manifold is substantially straight, and comprises an outer, cylindrically mantle 26 inside of which is defined a substantially annular void 27. At the upper end of the mantle 26, openings 17' are provided into said annular void.
• the vertical extension of the mantle 26 is of the same magnitude as the height of the free end of the "saxophone head" 15.
• the manner of operation for the suction manifold 25 is similar to the manner of operation for the saxophone head 15.
• Sediment and some water will, during dredging, be sucked into the opening 16' and transported through the pipe 2' to a container (not shown) near the water surface.
• Water will be sucked into the opening(s) 17' and transported downwards in the annular void 27 to the lower end of the suction manifold, and from there on in a mixture with the sediment up to the container.
• the amount of water sucked into the opening(s) 17' will, like for the saxophone head, to a large extent be self-regulating dependent of the concentration of sediment in the pipe.
• Figure 6 shows principally the same embodiment of the invention as Figure 2, but with the added functionality that an ejector pump 28 is connected to the pipe 2 above the suction manifold (not shown) to improve the suction capacity.
• an ejector pump 28 is supplied with water from the container 3 through a supply conduit 29. It may possibly be convenient to filter this water as it enters the supply conduit 29.
• Such an ejector pump 28 may also be used in any embodiment of the invention, not just the one depicted in Figure 6.
• Useful ejector pumps for this purpose are described in PCT patent application No. PCT/NO00/003 9 and in Norwegian Patent Application No. 20001 4843.
• the present invention a simple maneuvering and positioning of the suction manifold is obtained, and it can be positioned exactly in a desired location. It may be used for dredging in comparatively deep waters and the risk of blockage of the suction pipe, leading to a shutdown, is very small. All equipment connected to the second level, i.e. to the container 3, is easily accessed for maintenance and repair works etc.
• the cross section of the pipe 2 will to a large extent be adjusted in accordance with the actual need, but will not generally exceed 50 cm and will, at the other end of the scale, seldom be less than 10 cm.
• the first two calculation examples are valid for a typical situation where dredging takes place in a harbour basin. It can be seen that the consumption of water is reduced significantly if ejector is used, and in addition the diameter of the suction pipe may be reduced and thereby easier to handle.

Landscapes

• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Mechanical Engineering (AREA)
• Jet Pumps And Other Pumps (AREA)
• Treatment Of Sludge (AREA)
• Paper (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Reciprocating Pumps (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=19911956

Family Applications (1)

Country Status (8)

Families Citing this family (14)

Citations (1)

Family Cites Families (9)

• 2000
  • 2000-12-27 NO NO20006659A patent/NO313596B1/no not_active IP Right Cessation
• 2001
  • 2001-12-21 MX MXPA03005839A patent/MXPA03005839A/es active IP Right Grant
  • 2001-12-21 JP JP2002557601A patent/JP2004522877A/ja active Pending
  • 2001-12-21 EP EP01273367A patent/EP1346107A1/de not_active Withdrawn
  • 2001-12-21 CN CN 01821428 patent/CN1277999C/zh not_active Expired - Fee Related
  • 2001-12-21 WO PCT/NO2001/000509 patent/WO2002057551A1/en active Application Filing
• 2003
  • 2003-06-20 ZA ZA200304805A patent/ZA200304805B/xx unknown
  • 2003-06-27 CR CR7012A patent/CR7012A/es unknown

Patent Citations (1)

Also Published As

Similar Documents

Legal Events