US3119344A

US3119344A - Hydraulic dredge

Info

Publication number: US3119344A
Application number: US663988A
Authority: US
Inventors: Richard T Hoffman
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-09-12
Filing date: 1957-06-06
Publication date: 1964-01-28
Anticipated expiration: 1981-01-28

Description

Jan. 28, 1964 M N 3,119,344

HYDRAULIC DREDGE Original Filed Sept. 12, 1947 INVENTOR.

fiTiR/VEYS United States Patent This invention relates to a hydraulic dredge that is particularly useful Where the dredged subaqueou's material is of such character that gases form or escape when suction is applied to the material. Collection of these gases hinders the dredging operation. The object of this invention is to obviate this hindrance to the dredging operation. The invention may be understood from the description in connection with the accompanying drawing, in which FIG. 1 is a side view partly in section showing an illustrative embodiment of the invention;

FIG. 2 is a side View partly' broken away showing a modification; and

FIG. 3 is a similar view showing another modification.

In the drawings, reference character 1 indicates a rotary type of dredge pump that may be installed on a dredge, a portion of the wall of the hull of which is shown at 1'. The impeller 2 of this pump is driven by a shaft 3 from any convenient source of power. The suction pipe 4 of the dredge has a curved portion 5 extending into a portion 5' which is adapted in the usual way to reach the material that is to be dredged. As is shown in FIG. 1, the curved portion 5 may be rotated to twist the suction pipe 4 so that the end of portion 5' will be elevated or lowered. Dredged material is discharged through a discharge pipe 7. A hydraulic dredge, as is well known, is a dredging machine, usually floating, using a centrizfiugal pump and suction pipe to draw subaqueous material, such as mud or saturated sand from a channel, or the like, and to discharge it on the shore, or elsewhere.

When dredging subaqueous material of high gaseous content, gas which forms due to the reduced pressure produced by the dredge pump 1, ordinarily collects in a space 6 in the suction pipe 4 and the pump impeller 2, causing failure of the dredging operation.

An ejector 8, which may be operated by steam or air, is regulated by an inlet valve 9. An outlet from the ejector 8 is provided so that it may extend downwardly to any desired extent as indicated at 10". A suction pipe 11 extends from the ejector '8 to the space 6 where gas collects, and removes the gas, thus returning the dredge pump 1 to proper operating condition. A cut-off valve 12 is provided in the suction pipe 11.

In FIG. 2 reference characters that are provided with a prime indicate parts that correspond to those in FIG. 1. A rotary type of vacuum pump 14 is provided to produce a vacuum in a gas chamber 15. The gas chamber 15 is connected to the space 6 where gas collects as it escapes from the pumped material due to the decreased pressure on the material.

A chamber 16 is provided, to the upper portion of which the vacuum pump 14 is connected by a suction pipe 17. An inlet pipe 19 carries water for flushing a screen 18 in the chamber 16. A suction pipe 20 leads from the lower end of the chamber 16 to the gas chamber 15. An

3,119,344 Patented Jan. 28, 1964 2 inlet pipe 21 is provided for air and is connected to the suction pipe 20. A valve 22 is provided in the inlet pipe 21.

A float chamber 23 containing a float 27 has its upper and lower ends connected to upper and lower portions of the gas chamber 15 by two

pipes

24 and 25. An inlet pipe 26 for flushing water is connected to the float chamber 23.

A connecting rod 31 has one end connected to an arm 31 which operates the valve 2 2, and its other end connected to an arm 29 pivoted at 28- which is operated by the float 27. A valve 12' corresponds to the valve 12 of FIG. 1. The suction pipes 17 and 20 correspond to the suction pipe 11 of FIG. 1.

In the modification shown in FIG. 2 the operation is similar to that of FIG. 1. When the valves in the water and

air inlet pipes

19, 21 and 26 are closed, the rotary vacuum pump 14 is used instead of the ejector 8.

Means are provided to prevent damage to the vacuum pump 14. These means comprise the float 27 operating the valve 22-, 'and the chamber 16 containing the screen 18. When the gas which escapes from the material is insufiicient in volume to satisfy the requirements of the vacuum pump 14, material will rise in the gas chamber 15. Material which rises in the gas chamber 15 causes operation of the float 27, thereby opening the valve 22 to permit air to enter through the inlet pipe 21 in sufficient quantity to satisfy the requirements of the vacuum pump 14, thus preventing further rise of material in the suction system of the vacuum pump. Water is continually introduced through the inlet pipe 26 to keep the pipe 25 clear and permit the float 27 to operate without interference by the material. The chamber 16 is provided with the screen 18 to prevent passage of particles that might damage the vacuum pump 14.

In the modification shown in FIG. 3, a water pipe 34 is connected to the suction pipe 4" near where it enters the dredge pump 1" so as to introduce water near the entrance of the pump impeller. Water entering through the water pipe 34 forces collected gas through the dredge pump and also mixes with the material being pumped and reduces its viscosity. Preferably, the water passing through the gas collection space adjacent the suction side of the dredge pump via pipe 34 should be flowing before a volume of gas collects which is sufiic-ient to materially reduce the discharge rate of dredged material, such as illustratively indicated at 6 in FIGURE 1. A valve 36 is provided in the water pipe 34. The valve 36 is operated by an arm 3-7 provided with Ia slot 38. A connecting rod 39 extends from the slot 38 to an arm 40 pivoted at 41. An extension 42 on the arm 40 at pivot 41 is attached by a rod (indicated by the line in the center of spring 43) to a diaphragm 45 to regulate the quantity of water entering through the water pipe 34 in accordance with the pressure in the discharge pipe 7" which varies with the viscosity of the material in the discharge pipe '7". A spring 43, in a chamber 44 which contains the dia phragm '45, presses the diaphragm 45 against the pressure in the discharge pipe 7". An inlet pipe 35 is provided for introducing flushing water to keep the diaphnagm 45 free of interference by the material.

In the modification shown in FIG. 3, since the pressure in the discharge pipe 7" increases with the increase of the viscosity of the material being discharged, the in- 3 creased pressure against the diaphragm 45 operates the lever 48 which operates the lever 37 to admit a greater quantity of water through the water pipe 34 which mixes with the dredged material entering the dredge pump from the suction pipe 4" and reduces its viscosity.

This application is a division of application Serial No. 773,565, filed September 12, 1947, now Patent No. 2,795,873, granted June 18, 1957, for Hydraulic Dredge.

What is claimed is:

1. Hydraulic dredging apparatus for dredging mud and saturated sand comprising a centrifugal pump having an entrance and a discharge pipe, a suction pipe coupled to said entrance, said pump and said pipes being constructed so that all dredged mixture which passes through said pump is discharged from said pump only once, a water supply device connected to said suction pipe adjacent said entrance to reduce the viscosity of material being dredged by admitting auxiliary Water into said suction pipe, auxiliary water emitted from said water supply device into said suction pipe adjacent said entrance of said pump and into the stream of dredged material, a valve operatively connected to said device to regulate the rate of admission of said auxiliary Water, and means controlled by changes in pressure within said discharge pipe to control the position of said valve to admit said auxiliary Water to prevent gas accumulation adjacent said entrance during pump operation.

2. Hydraulic dredging apparatus for dredging gas containing mud and saturated sand com-prising a centrifugal pump having an entrance side and a discharge pipe, a suction line connected to said entrance side, space within said suction pipe adjacent sm'd pump entrance in which said gas released from said dredged mud and sand accumulates and means responsive to changes in pressure within said discharge pipe for preventing gases "from collect-ing adjacent said entrance side of said pump and reducing the viscosity of the material being dredged, comprising a water supply device in communication with said suction line adjacent said entrance side of said pump, auxiliary Water emitted from said Water supply device through said gas collection space and into the material being dredged.

3. Hydraulic dredging gas containing apparatus for dredging material such as mud and saturated sand comprising a centrifugal pump having an entrance side and a discharge side, a rotatably mounted suction pipe communioa-ting with said entrance side, a gas accumulation space within said suction pipe adjacent said entrance side of said pump in which gas emitted from said dredged material accumulates, and means for preventing said gases from accumulating in said gas accumulation space comprising an auxiliary water supply device communicating with said gas accumulation space within said suction pipe, auxiliary water emitted from said auxiliary Water supply device into said suction pipe during operation of said pump to reduce the viscosity of the dredged material, said auxiliary water supply device directing substantially all flow of said auxiliary water through said gas accumu lation space.

4. A hydraulic dredge comprising a centrifugal pump having an entrance and a discharge, a suction pipe and a discharge pipe coupled respectively to said entrance and said discharge of said pump, a gas accumulation space within said suction pipe adjacent said entrance side of said pump in which gas emitted from said dredged material accumulates, means introducing additional Water into said suction pipe throughsaid gas collection space, and a valve operatively coupled to said means and responsive to changes of pressure within said discharge pipe for controlling the amount of said additional Water introduced.

5. A hydraulic dredge for use in dredging gas containing materials comprising a suction pipe, a discharge pipe, a centrifugal pump having an entrance land discharge communicating respectively with said pipes, a gas accumulation space within said suction pipe adjacent said entrance side of said pump in which gas emitted irom said dredged material accumulates, said suction pipe having an opening adjacent said pump entrance and communicating with said gas accumulation space for introducing additional water, means for supplying additional Water through said opening and into said suction pipe and through said gas accumulation space during operation of said pump, a valve communicating with said opening for controlling the flow of said additional water therethrough, a pressure responsive device mounted and connected to respond to changes of pressure Within said discharge pipe and operatively connected to said valve for controlling the flow of said additional water.

6. A hydraulic dredge comprising a suction pipe, a discharge pipe, a centrifugal pump having an entrance and a discharge respectively coupled to said suction pipe and said discharge pipe, means introducing additional Water into said suction pipe and into the material being dredged during operation of said pump, a valve operatively connected to said means for controlling the flow of said additional water, a pressure responsive device connected through a pressure connection to respond to changes of pressure Within one of said pipes, said device being operatively connected to said valve to control the position of said valve which controls the flow of additional water, and means comprising a connection for continu-.

ously introducing auxiliary fluid into said pressure connection to said device, said auxiliary fluid flowing con tinuously away from said device through a portion of said pressure connection to prevent any dredged solids from reaching said device.

7. A method of dredging gas containing material which comprises hydraulically dredging said material by a centrifuga-l pump having a discharge pipe, adding auxiliary Water .to said dredged material prior to passage through said pump and during operation of said pump, controlling the addition of said axuiliary water in response to changes in discharge pressure of said pump and increasing the addition of auxiliary water when the pressure within said discharge pipe falls below a predetermined pressure.

8. A method of dredging subaqueous material which comprises hydraulically dredging said material by a centrifugal pump having a discharge pipe, adding auxiliary water to said material before it passes through said pump, and controlling the addition of said auxiliary water by the pressure within the discharge pipe of said pump.

9. A hydraulic dredge for use in dredging gas containing materials, comprising a suction pipe having a lower end for input of said dredged materials, a discharge pipe, a centrifugal pump having an entnance and discharge communicating respectively with said suction and discharge pipes, a gas accumulation space within said suction pipe in which gas emitted from said dredged material accumulates, said suction pipe having an auxiliary water inlet therein located closer to said pump entrance than to said lower end of said suction pipe for introducing additional Water, means for supplying additional Water through said inlet and into said suction pipe during operation of said pump to reduce the viscosity of the dredged material within said suction pipe, a valve commuuioating with said inlet for controlling the flow of said additional water therethrough, a pressure-responsive device mounted and connected to respond to changes of pressure within said discharge pipe and openatively connected to said valve for controlling the flow of said addi tional Water.

References Cited in the file of this patent UNITED STATES PATENTS 790,683 Harris May 23, 1905 790,702 Nash May 23, 1905 906,234 Jackson Dec. 8, 1908 1,147,401 Huttner July 20, 1915 (Utlier references on following page) UNITED STATES PATENTS 2,466,812 Jacobsen .Apr. 12, 1949 Le Blane Aug 17 Nagl" PJOV' 30 1,684,490 Henderson Sept. 18, 1928 FOREIGN PATENTS 1,804,987 Hopson May 1 93 104,002 Australia June 2, 1938 1,890,126 Moore Dec.6,1932 5 286,965 France Mar. 18, 1899 1,890,317 Durdin Dec. 1 471,581 Germany Jan. 24, 1929 1,891,201 HOE D 0- 1 1 32 503,120 Germany Aug. 1, 1930 1,971,441 Broadhurst Aug. 28, 193 6,421 Great Britain Apr. 15', 1889 2,019,968 Holloway Nov. 5, 1935 9,039 Great Britain Apr. 29, 1899 2,380,924 Carpenter Aug. 7, 1945 381,531 Great Britain 00:. 6, 1932 2,458,607 Lauchenauer Jan. 11, 19 9 421,780 Great Britain Dec. 31, 1934