US3286675A - System for unloading tankers - Google Patents

Description

NOV. 22, 1966 R WE E SYSTEM FOR UNLOADING TANKERS Filed Aug. 5, 1964 EDDU FIG-.3

INVENTOR EDWARD R- WEBER BY M LZiAL/ ATTORNEY change pumps.

United States Patent 3,286,675 SYSTEM FOR UNLOADING TANKERS Edward R. Weber, Rowayton, Fairfield, Conn., assignor to Esso Research and Engineering Company, a corporation of Delaware Filed Aug. 3, 1964, Ser. No. 386,997 4 Claims. (Cl. 114-74) The present invention relates to an improved system for unloading tankers. It has particular application to large waterborne tankers such as are employed in hauling and transporting petroleum and similar oils, and various liquid refined products and residues which are obtained there from. Although the invention is primarily of use with large oil tankers, it is applicable, of course, to tankers used for other purposes and tankers of smaller sizes.

Because of the depth of commercial oil tankers, it has often been necessary with prior systems to locate the dischange pumps which unload the cargo in or near the bottom of the vessel. This is required. to secure the positive suction head needed for proper operation of the dis- From these pumps piping must be extended inside the vessel and up to or above the deck. At the deck end. of such piping, conventional flexible hose lines are attached, making it possible to connect the outlet lines to shore connections. Shore based pumps would often be more suitable in many respects but in deep .vessels they cannot be used in many cases because of the high suction lift requirements. Even with vessels of lesser depth, suction pumps mounted on the dock or pier are usually quite unsatisfactory and ineflicient. Hence, general practice has been to mount the pumps on the vessel and. usually at or near the bottom thereof. This is expensive and consumes valuable cargo space.

According to the present invention, a system has been devised to unload from pier based pumps, no matter how deep the vessel. This is based on using the outer hull piping connections on the vessel extending from points at or near the bottom of the ship. They are preferably located substantially below water level. The outlet lines,

including connecting lines of flexible hose, may be attached to outer hull of the ship, either forward, at midship, or aft. The free ends of the flexible hoses so connected normally will be extended and held above the water line or at deck level when the tanker is moving. When the vessel is moving through the water, the lines are preferably so mounted and arranged that they do not perceptibly increase the drag on the vessel. Also, they are mounted so as to protect them from damage due to abrasion, wave action, etc. Upon docking, however, the upper ends of the hoses are first connected above the water line, preferably, to matching flexible hose connections from the shore.

The shore hose or line connections of the prior art usually extend from the shore at or above deck level, or some equivalent position. According to the present invention, the flexible lines from the shore are attached to connections at a low level, i.e., .generally at a level near that of the bottom of the vessel or where the connections for the vessel flexible lines emerge. Hence the shore pumps must be located, according to the present invention, in a caisson or well at a depth which preferably is equivalent more or less to the depth of the ship, at least to a depth approaching that of the unloaded vessel. After connecting the flexible lines from ship to shore, the flexible line, e.g. heavy hose, connections may bs lowered to the bottom of the harbor at dock side, or at least to a depth which is more or less equal to that of the shore based discharge pumps. With such an arrangement, the vessel cargo provides a positive hydraulic head to the inlet or suction side of the shore pumps.

"ice I has several features of novelty. By locating the pumps at or somewhere near the level of the bottom of the ship but on the shore, positive discharge of the vessel is assured. Cavitation is avoided. By using two connectable flexible lines, e.g. jointed pipes and/or hoses, one connected to the ship and the other on the shore, the whole transfer lines may rest at low levels. The connecting lines, however, are preferably arranged so that their interconnection may be made above water. Thereafter they are lowered. With such an arrangement there is no difliculty in establishing the necessary connections between ship and shore. After connection has been made, the lines are simply dropped overboard or they may be lowered mechanically to a suitable depth approximately at the level of the shore pumps to provide the desired hydraulic head on the pump inlet.

By making the tanker discharge cargo piping external and at least part of it flexible, connecting it to the ship at or near the bottom, the discharge lines may be arranged either at the bow, at the stern, or at a midship location, or in any two or more of such locations.

While not always necessary, it is usually desirable to recess the flexible cargo piping into the side of the hull of the vessel so as to provide a relatively streamlined hull surface for the vessel during travel. Thus it is preferred, although not always or absolutely necessary, to provide suitable grooves, channels or depressions in the hull from the point where the discharge line emerges from the vessel to the deck. The flexible cargo piping is placed in these grooves or channels when the vessel is ready to travel. Also, prefer-ably, fenders or covers are provided over the lines. This gives protection to the piping during travel against external damage, wave action and the like. Preferably the cover plate is readily moveable into and out of .position so as to reduce friction or drag during movement of the vessel in water, being I moved away when the lines are to be used for cargo discharge. These flat cover plates which cover depressions in the hull are built into or integrated with the hose structure, as further explained below.

According to the present invention, several advantages are realized by the arrangement described. For example, cargo pumps, which are rather large and heavy, need not be installed, on the tanker vessel, except such as may be required. for. cargo transfer within the vessel or for emergency use. The shore pumps can be used more continuously or given maximum utilization since they canunload all vessels coming into a given terminal. This makes it unnecessary for individual tankers to carry large discharge pumps which would be used only a small percentage of the time. The pumping equipment which is used on shore may be used much more continuously as various tankers come in to unload at the dock.

Hence the conventional pump rooms provided aboard tanker vessels according to prior art practice can be greatly reduced or even eliminated in many cases. This saves a great deal of expensive mechanical equipment.

I It saves weight and secures increased safety as well as materially simplified. Most if not all deck-lines may be omitted as also may be most of the risers, the pumproom connections, the deck cross-overs and all the necessary and costly valving that usually attends such installations. Only suflicient piping is required on deck, or in tanks, to distribute incorning cargo to tanks.

By pumping from a low level, positive suction side pressure at the pump can be secured during all stages of discharge. If desired, the shore pumps may be installed a little lower than the vessel. bottom, of even a loaded vessel, so that positive suction pressure is insured at the pump under all conditions. As the ship rises on discharge, the short pumps tend to increase their pressure head on the inlet or suction side for the final states of discharge. Thus the pumps in the dock need not necessarily be installed at lower level than the discharge level at the bottom of the vessel.

The present invention also eliminates many difliculties which exist under current procedures. When ship pumps are used, under prior practices, to discharge cargo ashore, they must operate at relatively high outlet pressures in the lines which lead from vessel to shore. This is partly due to the high lift required. This gives high pressure, which in turn gives rise to hazards from broken or leaky connections, leaking gaskets and the like. It increases the fire hazard in the immediate area where lines pass from ship to shore. By using ship bottom connections and low pump levels, the pressure differentials between ship and shore .are greatly reduced. Possibility of leaka-ge, particularly in the open areas, on deck or on piers close to the vessel, is greatly reduced. These are the areas where ignition hazards normally exist.

Under the systems previously in use, ship pumps have often been quite limited in capacity :by the available space, the availability of power to drive them, and by their suction characteristics. Hence discharge rates have been drastically limited in many cases. By the use of shore pumps many of these disadvantages are overcome. Shore pumps, as noted above, can be made much larger than ship pumps if desired. They may be driven with greater power. The whole system, when properly installed, can greatly reduce the discharge time of tankers as compared with prior systems. Another advantage is that increased time is available for maintenance of boilers and other equipment, between voyages, since the maintenance people will not need to be operating or repairing the conventional pumping and unloading equipment on the vessel.

The invention will be more fully understood by reference to the accompanying drawings and to the detailed description of specific embodiments of the invention which follows.

In the drawings, FIG. 1 is a small scale view of a vessel equipped with flexible discharge lines connected near the bottom of the vessel.

FIG. 2 is a transverse sectional view, somewhat diagrammatic, showing a connection from ship to shore with a discharge pump located in the pier or dock at a low level.

FIG. 3 is an enlarged fragmentary detailed view, partly in section, showing a modification in ship hull structure for accommodating the discharge lines to reduce friction or drag when the vessel is in motion and to prevent damage to the discharge lines.

FIG. 4 is a plan view, somewhat diagramatic, showing the whole ship-shore system for unloading a tanker alongside a pier.

Referring first to FIG. 1, there is shown a conventional tanker 11 equipped with a plurality of discharge lines at various places along the bottom portion thereof. For example, at the bow of the vessel there are shown three lines 13, at midship there are shown three lines 15, and near the aft end of the vessel are two discharge lines 17. These are connected through the hull at their lower ends to master valves or piping leading to cargo compartments. The upper ends of the lines are brought up to or near the top of the deck to keep them from dragging while the vessel is in motion.

The lines 13, 15 and 17 may be attached in any suitable fashion, permanently or temporarily, at or near the bottom of the cargo compartments in the vessel. The storage compartments within the vessel of course may also be interconnected in any desired fashion. The discharge lines, however, are preferably flexible, i.e., they may be hoses, jointed pipes, or both. They are arranged so that they can be brought up alongside the vessel during its movements as shown in FIG. 1 and also in such a manner that they can be extended to connect toshore lines. Both ship and shore lines are arranged so that they can be lowered into the water, after connection is established, to a position near their outlet level in the vessel as shown in FIG. 2. Here the vessel 11 is shown as having a single outlet hose 13 connected through a coupling 21 to a flexible shore based line 23. The latter is connected, through a conventional coupling 25, to a pipe 27 which extends to the inlet of a pump 2-9. The pump is located below the water level in the pier, preferably to a depth which is more or less equal to that occupied by the bottom of the vessel, although it need not be at such extreme depth in many cases. In some cases it may be desirable to have it even deeper. In establishing ship-to-s'hore connections, line 23 normally is held above the water line and interconnection with any of the lines from the vessel is made above the water level. Thereafter, the flexible lines are lowered into the Water to rest either at the bottom of the harbor alongside the pier or at a suitable level approximately at or below the bottom of the cargo compartments in the vessel. This is done to insure a good head on the suction side pump. The pump is driven by suitable power means, such as motor 31 and its discharges to any desired level through pump outlet line 33. This obviously may lead to storage tanks, to refineries or to other points of storage, wherever the cargo from the tanker is to be delivered.

Preferably, the vessel or hull 11 is provided, as shown in FIG. 3, with a depression or groove as indicated at 41 to receive each of the flexible lines substantially within the general contours of the vessel wall. For a smooth streamlined hull surface it is desirable to provide a cover plate such as is indicated at 43, to enclose the line 11. This cover plate may be permanently attached to one side of the hose, or integrated to a bracket attached to the hose. Alternatively, it may be hinged to the hull of the vessel or it may be slidable into place, appropriate receiving surface being formed in the hull, as will be selfevident to those skilled in the art. It is particularly desirable to have such cover plates below the water line 50 on the vessel where connections are made at low level, as indicated in FIGS. 1 and 2.

As shown in FIG. 4, the vessel will be docked alongside the pier 60. The pier is provided with a plurality of pump wells 61 and 62. Any number of such wells may be provided, as may be required. The wells preferably extend to a substantial distance below the level of the water in which the vessel is floating. As shown also in FIG. 4, three lines from the bow of the vessel are indicated at 64, 65 and 66, respectively. These connect through conventional couplings to flexible shore based lines 67, 68 and 69, respectively. The latter lead to pumps 70A, 70B and 70C installed in well 61.

Likewise, from the stern of the vessel, two lines 71 and 72 connect through couplings 73 to the shore based lines 74 and 75. These, in turn, are connected to pumps A, 80B, etc., in the well 62. The pumps 70A, 70B, etc., and 80A, etc., are well below water level and preferably near the depth of the vessel or at least at about the level of its cargo compartments. It will be obvious that other connections may be made and that the number of pumps and lines used will depend on the capacity of the vessel, the rate of unloading desired, and the location,

elevation, etc., of shore facilities which are to be supplied with the liquid.

It will also be apparent that various and numerous modifications may be made in the system. The same system can be used for many other liquids besides petroleum and its products. Thus the system may be used for unloading fresh water, or for chemicals and other liquids as will be obvious to those skilled in the art. The provision of the hose recesses, as shown in FIG. 3, is not always necessary and can be dispensed with in appropriate cases, for example, for short-haul vessels and the like.

It will be understood that various other changes and adaptations may be made, within the spirit of the invention. It is intended by the claims which follow to cover such as broadly as the prior art properly permits.

What is claimed is:

1. Apparatus for discharging liquid cargo from a deep compartment in a Water-borne tanker having a hull, comprising a cargo outlet in said compartment below the water level, a flexible line connected to said outlet, a shore based discharge pump located below the water level, a flexible line connected to the inlet of said pump, a releasable coupling for interconnecting both said flexible lines, and means formed in the outer surface of the hull of said tanker for receiving and protecting the first mentioned flexible line during movement of said tanker through the water.

2. Apparatus according to claim 1 wherein a plurality of flexible lines is provided in the tanker.

3. Apparatus according to claim 1 wherein the pump is at a level at least as low as the cargo outlet.

4. Apparatus for loading and unloading liquid cargo from a deep compartment in a water-borne tanker having a hull, comprising a cargo outlet in said compartment below the water level, a first conduit connected to said outlet, a shore based discharge pump located below the water level, a second conduit connected to the inlet of said pump, a coupling for interconnecting both said conduits, and means formed in the outer surface of the hull of said tanker for receiving and protecting the first conduit during movement of said tanker through the water.

References Cited by the Examiner UNITED STATES PATENTS MILTON BUCHLER, Primary Examiner.

T. M. BLIX, Assistant Examiner.

Claims (1)

1. 4. APPARATUS FOR LOADING AND UNLOADING LIQUID CARGO FROM A DEEP COMPARTMENT IN A WATER-BORNE TANKER HAVING A HULL, COMPRISING A CARGO OUTLET IN SAID COMPARTMENT BELOW THE WATER LEVEL, A FIRST CONDUIT CONNECTED TO SAID OUTLET, A SHORE BASED DISCHARGE PUMP LOCATED BELOW THE WATER LEVEL, A SECOND CONDUIT CONNECTED TO THE INLET OF SAID PUMP, A COUPLING FOR INTERCONNECTING BOTH SAID CONDUITS, AND MEANS FORMED IN THE OUTER SURFACE OF THE HULL OF SAID TANKER FOR RECEIVING AND PROTECTING THE FIRST CONDUIT DURING MOVEMENT OF SAID TANKER THROUGH THE WATER.

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