US1690380A

US1690380A - Sand-dredging vessel

Info

Publication number: US1690380A
Application number: US112773A
Authority: US
Inventors: Leathem D Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-06-01
Filing date: 1926-06-01
Publication date: 1928-11-06
Anticipated expiration: 1945-11-06
Also published as: GB272172A

Description

Nov. 6, 1928.

L. D. SMITH SAND DREDGING VESSEL Filed June 1, 1926 2 Sheets-Sheet l Nov. 6, 1928.

1,690,380 L. D. SMITH SAND DREDGING VESSEL 2 Sheets-Sheet 2 Filed June 1, 1926 fizz/677161) Leaf/zen: D Jm 65%,

y Wag Q Patented Nov. 6, 1928.

UNITED STATES PATENT OFFICE. T

LEATHEM 1). SMITH, OF STURGEON BAY, WISCONSIN.

SAND-DREDGING VESSEL.

Application filed June 1,

der conditions which will render the operation not only economical in cost but safe from from the hazard of overloading with water, as well as the hazard of shifting cargo when loading is done or the cargo is being transported in rough or unprotected waters. It has heretofore been the practice to pump sand or other material responsive to suction dredging, and pass the same, with a relatively large volume of water serving as a vehicle, through a flume provided at intervals with screens through which the water and finer material are allowed to pass, and to deliver the material with all of its vehicular water into the hold of the vessel, until by the accumulation of settled solid matter, the excess of water is caused to rise through the hatches and escape over the deck. But this method of loading necessitates a hull construction in which the gross capacity is sacrificed by the placing of bulkheads in maintaining buoyancy space and restricting the actual carrying capacity to dimensions which will insure remaining afloat when the cargo space is filled with water; moreover, the material goes into the hold in such a high state of fluidity that stability will be destroyed in rough water. One remedy proposed for this difliculty is to provide drainage space for the excessive volume of water admitted to the hold, and to constantly pump the water from the bilge in which it drains, but the quantity of water re quired to be pumped adds great expense to the operating cost.

The present invention proceeds upon the principle of automatically dewatering the pumped material at a stage in the operation which lies beyond the'screening point, but in advance of theadmission of the solid mate rial to the hold, this step being preferably performed by the overflow method of dewatering, carried on in a large number of dewatering units, preferably one for each screen, so that material admitted to the hold contains only the water occupying the voids between the grains or subdivisions of the ma- 1926. Serial No. 112,773.

terials, and while sufiiciently plastic to readily accommodate itself to hold spaces to which it may be delivered, has no such degree of fluid- 1ty as would endanger the stability of the ship by cargo-shifting in rough water; moreover, the hold itself is provided with means, such, for instance, as a central longitudinal barrier which retains the cargo in position on opposite sides of the keel, or a'plurality of such barriers which subdivide the cargo space into several longitudinal spaces; and these barriers are preferably constructed so that they serve as drainage spaces for that portion of the water which occupies the voids between the particles of subdivided material i and which gradually gravitates from the mass. The barriers may even be designed to serve as a means of access to the cargo, for instance, by making them in the form of tunnels of sufficient capacity to admit unloading apparatus, and having cant boards or the like which cause the material to gradually feed to such unloading tunnels.

An important feature of the invention consists in having the dewatering units which receive the water and material from the screens, so designed that by regulating escape valves inthe dewatering hoppers, the material, with its remanent water, will flow from the hoppers only at a predetermined rate,and Whenever the feed of material and water from the screen exceeds the rate of escape, the accumu lation will build up around the spout leading from the screen and check the inflow of further material at that particular unit, thus causing the material to pass to successive units until the obstructed unit automatically clears itself. This arrangement of controll'able valve dewatering units also aifords'con- 'venient means through which to insure distribution of the lading throughout the hold, it being merely necessary to restrict the opening or wholly close the valves in locations where an excess of loading becomes manifest,

in order to reduce loading at such points until the vessel regains an even keel by the process,

substantially dewatered state, and, therefore,

sufliciently immobile to prevent trimming the cargo by the natural flow of the material within thehold. 7

Located beneath the branches 4 of the fiume' and at regular intervals alongthe deck on either side of the center line of the hulh'are "de'watering hoppers 5, each of which is adapted to be fed through a spout 6 from a screen 7 in the bbttom'of the flume,-and

each'of whichis designedto discharge into the hold of the vessel through a port 8. In this way, the hoppers 5' will receive, along Withsufiicient Water to insure fluidity, such portions of the material' pumped into the fiume 4 as is intended to" be passed by the screens 7,.the ta ilings' or coarser material ultimately escaping at 9." 'Bu't material onte'ring a hopper 5 is restrained in its escape therefrom by means of a suitable valve, for

instance, a hemispherical valve 10 suspended by a flexible connector 11 from, the winding shaft 12 which'it reaches by way of the pulley 13, and in this way, each hopper will be kept normally filled with screened material to such a level as will cause surplus water to overfiow'the brim of'tliehopper while the materialis yet above deck andthus escape overboard by gravity and without the expen'se of pumping it,'jas would be thecase if the water could freely enter the holdalong with the material saved. "The spoutS beneathea'ch screen 7 terminatesin such close proximity to the horizontal plane of the brim of the hopper 5 that if the material flows through the screen at a greater rate than that at which it gravitates through the throat, which isconstrictedby the valve '10, the materialwill pile up andseal the lower end of thejspoutr by thenatuial angle of repose w sought 1 by the material, notwithstanding its contained water, andin this way the feed of material through the particular-screen which ZlSf thus temporarily blocked, will be interrupted until the hopper 5fautomatically clears "itself sufficiently to reinduce flow through the screen.

blocked, the material in the mine passes over hen a screen is thus itito screens'bcyond, and while the capacity of the flume and the pumpwhich feeds it, as

W well as the inclination ofthe flumeand other elements of design, will be suilicient to "supply all of'the screens simultaneously, the described method ofregulatingthe flow through eachparticular screen, at a rate predeter' mined by the adjustment of its valve 10, will serve to insure distribution of the cargo. Moreover, if it be found that the vessel is listing by reason of excessive accumulation on one side relatively to the other, or is down at the bow or stern, the operator will regulate valve openings or close the valves altogether of such numbers of screens as will be necessary to correct the inaccuracy of distri bution.

The material that enters the hold of the vessel will, of course, have trapped in it a proportion of water roughly mcasurcd by the capacity of the voids between the particles of the material, and ordinarily the material will reach the hold of the vessel in a soupy or mushy condition, which will adversely affect equilibrium of the vessel in case of roll-' ingin rough water, and to avoid this contingency, one or more. barriers 14 are erected within the hold. and extended from end to as will resist shifting of the load, at least to a degree which will leave the cargo relatively solid and immobile. In the drawings two such barriers are shown; and to adapt them to serve as escape channels for such water as issues from the loaded material by gravitatiomand deliver such water to the bilge pump 19, said barriers'arc in the form of tunnels with deflecting top walls'15 and screened side walls 16, and the bottom of the cargo space is defined by cant boards 17 and 18 which cause the water to flow into the tunnels. The tunnels 1d will preferably be of suflicient capacity to admit operatives as well as automatic or other unloading apparatusor implements, and their screens 16 will be removable so that after-it becomes safe to do so, the cargo may be allowed to gravitate into the tunnelsand thusrendered accessible for unloading. v

A loading system for dredged materials as herein described is very economical to operate by reason of the use of gravity for both preliminary and ultimate dewatering, as well as'for feeding the material toward a common unloading tunnel. The cargo is made safe against shiftingso long as it is in'amushy or mobile condition, by reason of contained water, and as long thereafter as maybe found necessary under extreme weatherconditions; A ship may be loaded to very much greater capacity by reason of separation of the greater portion of the water before the material enters the hold, and control of the load ing may be carried on with: regularity and economy by regulation of escape of the material fromthe hoppers in which it is received from the screen. I

1. A floating vessel for dredging and transporting material such as a sand, constructed with a storage hold lordredged ma until thewater can further escape by gravity tau terial and having mounted upon it means for pumping material, together with :1 vehicular constituent of water, from an overboard position and delivering such material to a position above the storage hold, a dewatering hopper also located above the storage hold in position to receive the material so delivered and discharge its contained water overboard, means for delaying escape of the material from the hopper until dewatering has proceeded to a desired degree. and means for delivering dewatered material from said hopper to the hold of the vessel.

2. A floating vessel for dredging and transporting material such as sand, constructed with a storage hold for dredged material, and having mounted upon it means for pumping thematerial from an overboard position and delivering it with a vehicular constituent of water to a point above the storage hold, means receiving the material so delivered and conveying it to a plurality of points of release, which are also above the storage hold, dewatering means receiving the material escaping at the several points of release and confining such material in positions which are above the storage hold and from which water escaping from the material may flow overboard by gravity, means delaying escape of material from said dewatering means until a desired proportion of its contained water has escaped, and a plurality of discharge spouts directing material from the dewatering means to distributed points within the storage hold.

3, A floating vessel for dredging and transporting material such as sand, said vessel being constructed with a storage hold and having mounted upon it means for pumping the material, along with a vehicular constituent of water, from an overboard position to a position which is above the storage hold, a flume located above the storage hold in position to receive the material and water pumped, said flume being constructed todeliver a restricted portion of the material and water, a dewatering hopper also located above the storagehold, in position to receive a restricted portion of material and water delivered by the flume and to release a desired proportion of the water for discharge overboard by gravity, means for delaying escape of the material from the hopper until the desired proportion of its contained water has escaped, and means delivering the dewatered material from said hopper to the storage hold.

4. A floating vessel for dredging and transporting material such as sand, said vessel being constructed with a storagehold and having mounted upon it means for pumping the material, along with a vehicular constituent of water, from an overboard position to a position which is above the storage hold, a fiume located above the storage hold in position to receive the material and water pumped, said flume being constructed to deliver a restricted portion of the material and water, a dcwatering hopper also located above the storage hold, in position to receive a restricted portion of material and water delivered by the flume and to release a desired proportion of the water for discharge overboard by gravity, means'directing the flow of material from the flume to the dewatering hopper constructed to arrest flow of material from the fluine when the accumulation in the hopper reaches a predetermined level, means for delaying escape of the material from the hopper until the desired proportion of its contained water has escaped, and means delivering the dewatered material from said hopper to the storage hold.

5. A floating vessel for dredging and transporting material such as sand, constructed with a storage hold for dredged material and having mounted upon it means for pumping material, together with a vehicular constituent of water, from an overboard position and delivering such material to a position above the storage hold, a dewatering hopper also located above the storage hold in position to receive the mate-rial so delivered and discharge its contained water overboard, means tor delaying escape of the material from the hopper until dewatering has proceeded to a desired degree, and means for delivering dewatered material from said hopper to the hold of the vessel; the last-named means being provided with an adjustable valve permitting flow of material from the hopper only at a predetermined rate.

6. A floating vessel for dredging material such as sand, said vessel being constructed with a storage hold and having mounted upon it means for pumping from an overboard position, to a position above the storage hold, material accompanied by a vehicular constituent of water, a flume above the storage hold in position to receive the material and water pumped, said flume being constructed with a plurality of screened discharge openings over which the material selectively flows and which permit the escape of water with restricted portions of the material, dewatering hoppers also above the storage hold located beneath the respective discharge openings of the flume and permitting the escapeof desired-portions of the water overboard by gravity, delivery means carried by the respective hoppers for directing the material to the storage hold, and independently adjustable valves for the respective delivery means adapted to retard escape of the material from the hopper to the hold until a desired proportion of the water has escaped from the material;

7. A floating vessel for dredging and transporting material such as sand, said vessel being constructed with a storage hold and having in said storage hold a fore and aft tunnel and a vehicular constituent of Water from an overboard position to a position above the storage hold, means also above the storage hold receiving the pumped material and water, fluxnes branching from said receiving means and extending fore and aft of the vessel above the storage hold and permitting the flow of material and water through them, lurality a l of means distributed along the lengtli of each flume for releasing water with restricted portions of lmaterial, dewatering hoppers also above the storage hold, in position to release water from the material and permit it to escape overboard by gravity, said hoppers being located beneath the respective releasing means of the flames, and means directing material from the respective hoppers to distributed points on opposite sides of and distributed along the length of the tunnel within the hold.

Signed at Sturgeon Bay, \Visconsin, this 25th day of May, 1926.

LEATHEM D. SMITH.