DISCHARGING SYSTEM FOR A HOPPER

Abstract

The invention provides a method and system for discharging dredged material stored within a hopper. The discharging system comprising a plurality of sensors on at least one bottom wall of the hopper for acquiring information over a dredged material stored within the hopper; an outlet on a lower part of the hopper for discharging the dredged material; and at least one water jet valve for fluidizing the dredged material while discharging; wherein a quantity of water flowing out of the at least one water jet valve is based on the acquired information from the plurality of sensors.

Claims

1. A discharging system for a hopper, the discharging system comprising: a plurality of sensors on at least one bottom wall of the hopper for acquiring information over a dredged material stored within the hopper; an outlet on a lower part of the hopper for discharging the dredged material; and at least one water jet valve for fluidizing the dredged material while discharging; wherein a quantity of water flowing out of the at least one water jet valve is based on the acquired information from the plurality of sensors.

2. The discharging system of claim 1, comprising a water level measurement system for acquiring a water level information of a water level within the hopper and wherein the acquired information from the plurality of sensors is corrected based on the water level information.

3. The discharging system of claim 1, wherein the plurality of sensors comprises at least one of: a pressure sensor, a density sensor, and a concentration sensor.

4. (canceled)

5. The discharging system of claim 1, wherein the plurality of sensors comprises at least four sensors.

6. The discharging system of claim 1, wherein the hopper comprises a number of hopper sections, and at least one hopper section comprises a sensor of the plurality of sensors as well as at least one water jet valve both associated with the hopper section, and wherein the quantity of water flowing out of the at least one water jet valve and into the hopper section is based on the acquired information from the sensor.

7. The discharging system of claim 1, wherein adjacent sensors among the plurality of sensors in a row are separated by a first distance, wherein the first distance is 55 mm or greater.

8. (canceled)

9. The discharging system of claim 1, wherein adjacent rows are spaced apart by a second distance, wherein the second distance can be 110 mm or greater.

10. (canceled)

11. The discharging system of claim 1, wherein the plurality of sensors comprises at least a pair of sensors, each pair of sensors comprising a pressure sensor and a density sensor.

12. The discharging system of claim 11, wherein the pressure sensor and the density sensor in each pair of sensors are spaced apart by a third distance, wherein the third distance is 20 mm or greater.

13. (canceled)

14. The discharging system of claim 1, wherein a position of each sensor of the plurality of sensors is different than a position of each of the at least one water jet valve, wherein the position of each sensor is not in-line with a direction of water flowing out of the at least one water jet valve.

15. The discharging system of claim 1, wherein a direction of water flowing out of the at least one water jet valve is adjusted based on the acquired information from the plurality of sensors.

16. The discharging system of claim 1, further comprising a control system for obtaining the acquired information over a dredged material from the plurality of sensors, and controlling the quantity of water flowing out of the at least one water jet valve based on the acquired information.

17. The discharging system of claim 1, wherein the at least one wall has a slope (), wherein the slope is 30 degrees or less.

18. (canceled)

19. The discharging system of claim 1, wherein the at least one bottom wall comprises: a first bottom wall and a second bottom wall, such that the first bottom wall and the second bottom wall slope downwardly to the lower part of the hopper where the outlet is.

20. The discharging system of claim 1, further comprising a discharging pump for controlling a quantity of dredged material discharged through the outlet on the lower part of the hopper, and/or a jet pump for controlling the quantity of water flowing out of the at least one water jet.

21. (canceled)

22. A dredging vessel comprising a hopper containing dredged material and a discharging system according to claim 1.

23. A method of discharging dredged material from a hopper of a vessel within which the dredged material is stored, the method comprising, while the dredging material is being discharged through an outlet on a lower part of the hopper: acquiring, from at least one sensor, information of the dredged material; and fluidizing the dredging material by opening at least one water jet valve based on the acquired information of the dredged material such that the dredging material is discharged, wherein a quantity of water flowing out of the at least one water jet valve is based on the acquired information from the plurality of sensors.

24. The method of claim 23, further comprising: obtaining, by a control system, the acquired information over a dredged material from the plurality of sensors; and controlling the quantity of water flowing out of the at least one water jet valve based on the acquired information.

25. The method of claim 23, further comprising: measuring a water level within the hopper; and correcting the acquired information from the plurality of sensors based on the measured water level.

26. The method of claim 23, wherein the at least one sensor comprises at least one of: a pressure sensor, a density sensor, and a concentration sensor.

27. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0025] The invention will be described in more detail below, with reference to preferred embodiments as shown in the drawings attached, in which:

[0026] FIG. 1 shows cross sectional view of a hopper.

[0027] FIG. 2 shows a top view of a discharging system for a hopper.

[0028] FIG. 3 shows a front view of a discharging system for a hopper.

[0029] FIG. 4 shows a front view of a discharging system for a hopper according to an alternative embodiment.

[0030] FIG. 5 shows a control system for controlling the discharging of a hopper.

DETAILED DESCRIPTION

[0031] The aspects of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the disclosure are shown.

[0032] FIG. 1 shows a cross sectional view of a hopper 10 in a TSHD 2. The TSHD 2 comprises a hopper 10 charged with a mixture of dredged materials 20 (e.g. sand, silt, gravel, clay, rock, etc.) and water 21, wherein the dredged materials are deposited on the lower part of the hopper forming a sediment layer and water is over the dredged materials. The water level 19 in the hopper 10 may change during operations.

[0033] FIG. 2 shows a top view of a discharging system for the hopper 10 and FIG. 3 shown a front view of the discharging system for the hopper 10. The hopper 10 comprises two lateral walls 12, two bottom walls 14, and a discharging area 16 on the lowest part of the hopper. The discharging area 16 is placed between the two bottom walls 14.

[0034] A plurality of sensors is placed on the bottom walls 14 of the hopper. The plurality of sensors are placed in a mirror symmetry arrangement on the two bottom walls 14, that is, the arrangement of sensors on one on the bottom walls 14 is identical to the arrangement of sensors on the other bottom wall 14 with respect to the discharging area 16. Alternatively, the plurality of sensors can be placed in an asymmetric arrangement on the two bottom walls 14.

[0035] As shown in FIG. 2, the plurality of sensors are distributed in a number of rows R parallel to the discharging area 16, and, in each row, a number N of sensors, that is, the plurality of sensor 22, 24 are distributed in three rows, in which the first and second row each has two pressure sensors 22 and two density sensors 24 and in which the third row has four pressure sensors 22 and four density sensors 24. Alternatively, the plurality of sensors can be distributed in one or more rows parallel to the discharging area 16, each row has a different number of sensors. Adjacent sensors on a same row are spaced apart by a first distance (d1). The first distance (d1) can be 55 mm or greater. Adjacent rows are spaced apart by a second distance (d2). The second distance (d2) can be 110 mm or greater.

[0036] Optionally, the plurality of sensors can be grouped in pairs of sensors 25, i.e. a pressure sensor 22 and a density sensor 24. A pressure sensor 22 and a density sensor 24 in each pair 25 are spaced apart by a third distance (d3). The third distance depends on the arrangement and number of sensors in the hopper. The distance (d3) can be 20 mm or greater. Optionally, each pair of sensors 25 in the hopper can have a different distance between each sensor of the pair of sensors.

[0037] The discharging area 16 comprises two outlets 26 for discharging the dredged material. Alternatively, the discharging area 16 can comprise one outlet or a plurality of outlets. A discharging pump (not shown) can be connected to the outlets for pumping out the dredged material through the outlets. The discharging pump can be adjusted, for example by adjusting a flow rate or output pressure of the discharging pump, in order to control the quantity of dredged material discharged through the outlet.

[0038] The plurality of sensors comprises pressure sensors 22 and density sensors 24. Pressure sensors 22 are used for measuring the pore water pressure or pore pressure of a column of dredged material above the sensor and is usually measured with respect to the atmospheric pressure (e.g. atmospheric pressure at sea level), For example, when pressure sensors indicate a positive value (i.e. pressure is more than the atmospheric pressure), there is an overpressure; and when pressure sensors indicate a negative value (i.e. the pressure is less than the atmospheric pressure), there is an underpressure. The pore water pressure relates to the stickiness of the dredged material to the bottom wall of the hopper. The stickier, the slower the dredged material is discharged. When the measurement of the pressure sensor is below a pressure threshold (i.e. there is an underpressure), there is no discharging flow flowing. When the measurement of the pressure sensor is above the threshold, such that there is no underpressure but instead overpressure, the discharging flow is efficiently flowing. Hence, the pressure sensors 22 provide information over a first state of dredged material (i.e. how loosely or densely packed is the dredged material), and a state of flow (i.e. well flowing or not).

[0039] Density sensors 24 (or concentration sensors) are used for measuring the amount of water in the dredged material column above the sensor. When the measurement of the density sensor is smaller than a density threshold and this measurement decreases or remains constant while discharging, the discharging flow is efficiently flowing, and when the measurement of the density sensor is greater than the threshold but this measurement increases or remains constant while discharging, the discharging flow is not efficiently flowing due to due to the packing of the submerged dredged. The density threshold is physically defined to be a density defined by the soil porosity, which is somewhere between the maximum and minimum porosity of the soil. Hence, the density sensors 24 provide information over a second state of the dredged material (i.e. how packed the dredged material is or volume concentration of solids). In the present invention it is considered that the discharging flow is efficiently flowing when density sensors measure between 50% and 65% of solid material (or between 35% and 50% of water or liquid material).

[0040] Table 1 shows a state of the dredged material based on information of the sensors. While discharging the dredged material through outlets, a hole is formed around the outlets with almost vertical slopes. When time passes these vertical slopes move away radially from the outlets, while the dredged material flows over a certain slope to the outlets. This process is known as breaching. When sensors indicate an underpressure and high density (or concentration), the dredged material breaches slowly, that is the dredged material is slowly discharged through the outlets. When sensors indicate an overpressure and high density (or concentration), the dredged material is fluidized, thereby breaching is faster and the dredged material is fast discharged through the outlets. When sensors indicate low pressure and low density (or concentration), there is no (or almost nothing) dredged material present in the hopper, thereby the hopper is (almost) empty.

TABLE-US-00001 TABLE 1 Underpressure Overpressure High Dredged material breaches Dredged material is density/concentration slowly fluidized Low Hopper is not completely Hopper is emptied density/concentration emptied

[0041] Referring back to FIGS. 2 and 3, the hopper 10 comprises at least one water jet valve 30 for fluidizing the dredged material while discharging. The water jet valves 30 are placed in a mirror symmetry arrangement on the two bottom walls 14, that is, the arrangement of water jet valves 30 on one on the bottom walls 14 is identical to the arrangement of water jet valves 30 on the other bottom wall 14 with respect to the discharging area 16. A distance between adjacent water jet valves in a row is 1 m or more. Alternatively, water jet valves 30 can be placed in an asymmetric arrangement on the two bottom walls 14. Optionally, water jet valves 30 can be also be placed on the lateral walls 12 of the hopper. Alternatively, each sensor or pair of sensors is grouped with a water jet valve 30. Optionally, more than one sensor or pair of sensors can be grouped with the same water jet valve.

[0042] The water jet valves 30 can be connected through a pipeline (not shown) to a jet pump (not shown) for controlling the quantity of water flowing out of the water jet valves 30, in which the quantity of water flowing out of the water jet valves 30 is based on the acquired information from the plurality of sensors. Water flowing out of the water jet valves 30 fluidizes the dredged material, thereby improving its fast discharging through the outlets 26. Since the plurality of sensors provide information of the dredged material (or the state of the dredged material) continuously while the dredged material is being discharged, the jet pump can be adjusted, and thus the water jet valves 30, such that the quantity of water flowing out of the water jet valves 30 is continuously controlled, avoiding then that too much water or too low water is present in the dredged material. The jet pump can be easily adjusted (e.g. increasing/decreasing the revolutions per minute, r.p.m.) so a flow pressure of water flowing out of the water jet valves is adjusted, and as a result, the quantity of water (or volume flow rate) flowing out of the at least one water jet valve can be also easily controlled or adjusted. Therefore, the dredged material can be efficiently discharged, and as a consequence the time for emptying the hopper is reduced. If the hopper is emptied faster, more cycles of dredging material, transporting and discharging can be performed, reducing then the dredging costs, lowering the fuel consumption and, in turn, leading to less CO2 emissions. Furthermore, since quantity of water is controllable and water is only flowing out of selected water jet valves based on sensor measurements, then the quantity and pressure of water used for emptying the hopper is minimized, which align with a possible water scarcity or shortage in the vessel.

[0043] The water level 19 in the hopper as shown in FIG. 1 may change during operations. The water level will affect the hydrostatic pressure at a pressure sensor in the hopper. The discharging system may comprise a water level measurement system (not shown). The water level measurement system is configured for acquiring a water level information of a water level 19 within the hopper 10. As a result, the acquired information from the plurality of pressure sensors can be corrected for a hydrostatic pressure based on the water level information. The water level 19 within the hopper can be measured by a radar, and then the pressure sensor measurements can be corrected using the water level measurement. The water level within the hopper can alternatively be measured using an optical sensor, a conductivity sensor, a float switch, an ultrasonic sensor, and the like.

[0044] Water flowing out of each water jet valve 30 are provided at a close proximity or at a distance from the sensors, such that, on each bottom wall 14, the position of each sensor 22,24 is not in-line with a direction of the water flowing out of each water jet valve 30. Such arrangement of the sensors and water flowing out of the water jet valves, avoids any influence of the water flowing out over the measurement of the sensors. If sensors are in-line with the direction of the water jets, the water jets might influence the measurement of the sensors, or clear the dredged material so quickly that there is nothing to measure above the sensor, leading then to a wrong assessment that the hopper is empty. As shown in FIGS. 2 and 3, a row of water jet valves 30 is placed closer to the discharging area 16 than any row of sensors and a row of water jet valves 30 is placed closer to the lateral wall 12 than any row of sensors. Optionally, rows of water jet valves 30 can be places at any distance from the discharging area 16 and/or the lateral wall 12.

[0045] Alternatively, the water jet valves 30 and plurality of sensors 22,24 can be arranged in sections. Each section can be controllable in a different way (e.g. quantity of water flowing out of water jet valves within a section can be different than a quantity of water in another section). Each section can comprise at least one water jet valve and at least one sensor or pair of sensors. Optionally, sections can be separated by walls. Optionally, sections can be emptied at different time.

[0046] As shown in FIG. 3, each bottom wall 14 has a slope . A bottom wall 14 with e equal to 0 degrees is essentially similar to a horizontal wall. The slope of each bottom wall 14 is substantially equal to 30 degrees or less. The two bottom walls 14 are arranged such that the two bottom walls 14 slope downwardly to the discharging area 16. Alternatively, each bottom wall 14 can have different slopes. By having a slope of equal to 30 degrees or less, the volume of the hopper can be maximized, thereby allowing more dredged material to be stored within the hopper 10. Furthermore, the center of gravity of the vessel (e.g. the TSHD 2) is lowered when fully loaded, leading to a positive effect on the stability of the vessel (e.g. avoiding the vessel to capsize).

[0047] FIG. 4 shows a front view of a hopper 10 according to an alternative embodiment. The hopper 10 of this alternative embodiment comprises two opposite bottom walls 14. The bottom walls 14 slope towards the outsides of the hopper 10 and the dredged material is discharged to the outlets 26. A plurality of sensors (e.g. pressure sensors 22 and density sensors 24) and water jet valves 30 is placed on the bottom wall 14 of the hopper in a similar way as describes for the embodiment shown in FIGS. 1, 2 and 3.

[0048] FIG. 5 shows a control system 80. The control system 80 obtains information, from the plurality of sensors 20, i.e. the pressure sensors 22 and the density sensors 24, over the dredged material present in the hopper 10, and, based on the information, outputs signals for controlling the quantity of water flowing out of the water jet valves 30 based on the information. Based on these signals (e.g. on a display), a dredger master or operator can manually control the water jet valves 30. Alternatively, the control system can automatically control of the water jet valves. By automatically controlling the water jet valves, time needed for controlling the water jet valves is believed to be optimized. The control system 80 can also obtain information related to the water level within the hopper in order to correct sensor measurements, information related to the pumps (i.e. the jet pump and/or the discharging pump), information related to a quality of the dredged material (e.g. homogeneity of the dredged material on the bottom walls).

[0049] Optionally, the control system 80 can comprise a memory (not shown) for storing the information acquired from the sensors, a processor (not shown) and/or controller (not shown) for determining whether the quantity of water flowing out of the water jet valves 30 need to be adjusted and for outputting command for controlling the water jet valves 30 and/or jet pump, although reference may be made to a control system, this is equally intended to cover and include a unit, module, and the like.

[0050] These aspects may, however, be embodied in many different forms and should not be construed as limiting; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and to fully convey the scope of all aspects of the disclosure to those skilled in the art. Like numbers refer to like elements throughout the description.