Title:
SHIP'S CARGO TANK CLEANER
United States Patent 3747854


Abstract:
Apparatus employing rotating nozzles to distribute jets of a cleaning fluid throughout the interior of a ship's cargo tank wherein the speed of rotation of the apparatus is regulated by using opposed jets of controllably different orifice sizes to produce a turning force less than that which would occur if the jets were not opposed to each other and at the same time permitting the use of a jet size which will effectively perform the cleaning operation. The apparatus is designed to be installed permanently within the cargo tanks of oil tankers and provision is made to permit appropriate operating orientation of the apparatus while accommodating supply lines for the cleaning fluid which may be distributed on the top side, the bottom side, or the side walls of the tank.



Inventors:
ANDERSON C
Application Number:
05/206115
Publication Date:
07/24/1973
Filing Date:
12/08/1971
Assignee:
CHEVRON RES CO,US
Primary Class:
International Classes:
B05B3/06; (IPC1-7): B05B3/00
Field of Search:
239/227
View Patent Images:
US Patent References:
3255970Tank cleaning apparatus1966-06-14Saad
2947482Tank washing apparatus1960-08-02Lione
2078568Apparatus for washing tanks1937-04-27George
2074052Apparatus for cleaning the interior of tanks1937-03-16George



Primary Examiner:
King, Lloyd L.
Parent Case Data:


This is a continuation, of application Ser. No. 77,084, filed Oct. 1, 1970.
Claims:
I claim

1. In a ship's cargo tank cleaner which employs rotating nozzles to project jets of a cleaning fluid against the interior walls of a cargo tank and in which the force to rotate said nozzles is supplied by the reaction from the jets of fluid which issue from said nozzles,

2. Apparatus in accordance with claim 1 wherein said first set of nozzles is a first pair of said nozzles and said second set of nozzles is a second pair of said nozzles,

3. Apparatus in accordance with claim 1 including,

4. Apparatus in accordance with claim 2 wherein

5. Apparatus in accordance with claim 1 including,

6. Apparatus in accordance with claim 1 including,

7. Apparatus for distributing a cleaning fluid on the interior walls of a ship's cargo tank comprising,

8. Apparatus in accordance with claim 7

9. Apparatus in accordance with claim 8 including,

10. A tank cleaner apparatus for distributing a jet of cleaning fluid by means of a rotating nozzle arrangement comprising

11. Apparatus in accordance with claim 10 including

12. In a ship's cargo tank cleaner which employs rotating nozzles to project jets of a cleaning fluid against the interior walls of a cargo tank and in which the force to rotate said nozzles is supplied by the reaction from the jets of fluid which issue from said nozzles,

13. Apparatus in accordance with claim 12 including,

Description:
BACKGROUND OF THE INVENTION

The present invention is directed to cleaning the interior walls of a ship's cargo tank, particularly such a tank as has been used to carry petroleum products. Such cleaning is desired when the type of cargo to be loaded into the tank is different from that which it previously carried, particularly if the new cargo is one which would be put off grade by residuals of the former cargo. Such cleaning may also be required when the ship is being put into a shipyard for maintenance or repair.

DESCRIPTION OF THE PRIOR ART

The use of apparatus employing rotating nozzles to project jets or sprays of a cleaning fluid against the inner walls of a ship's cargo tank is known to the art. Also, it has been recognized that it is desirable to control the speed of rotation of the nozzles so that the jet of cleaning fluid will impinge upon the wall of the tank a sufficient time to perform the cleaning operation. The art has recognized that if the nozzles are appropriately placed on the device it is possible to employ the reaction of the body of the nozzle from the jet issuing from it as the source of power to rotate the apparatus. The prior art devices of which I am aware required relatively complex apparatus to properly perform these functions. The present invention is designed to perform these functions by apparatus which is rugged and relatively simple in construction so that the apparatus can operate dependably for long periods of time without the necessity of retrieving it frequently from within the cargo tank for repair or adjustment.

SUMMARY OF THE INVENTION

In the apparatus of the present invention the speed of rotation is regulated primarily by using two distinct sets of nozzles, one set of which is designed to project the principal jets of cleaning fluid and to supply the energy required to operate the device, and the other set of which is designed to supply a turning force opposing that of the first set of nozzles and at the same time project auxiliary jets of cleaning fluid. The nozzles are proportioned so that there is an effective resultant turning force derived from the reaction to the jets from the principal or driving nozzles over that from the secondary or retarding nozzles, and provision is made for adjusting the size of the exit orifice of selected nozzles so that this resultant force can be controlled in an amount to give the desired speed of rotation of the apparatus.

An additional feature of the invention is the provision of means for permitting the connection of a supply line of cleaning fluid to the apparatus, either through its top end or through its bottom end while maintaining a preferred operating orientation of it. Thus the same device may be interchangeably connected to cleaning fluid supply lines which enter the cargo tank from these various directions, avoiding the requirement of providing different noninterchangeable heads to accommodate the different orientations of the various supply lines.

Other modifications and advantages of this invention will become apparent as the description of it proceeds in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the device in elevation and shows a preferred disposition of opposing sets of nozzles.

FIG. 2 is a view in sectional elevation taken along the line 2--2 of FIG. 1.

FIG. 3 is a view in sectional elevation of a portion of the device taken along the line 3--3 of FIG. 2 and shows the interior construction of the nozzles.

FIG. 4 is another view in elevation illustrating the opposite side of the device from that shown in FIG. 1 to display more clearly a gear arrangement.

FIG. 5 is a detail in section of a modification of an exit orifice of a nozzle.

FIG. 6 is a detail in section illustrating an alternate position within the device of a diverting element for the incoming stream of cleaning fluid.

FIG. 7 illustrates in elevation a modification of the device related to the disposition of the opposing sets of nozzles.

FIG. 8 is a schematic representation in elevation and partly in section of the disposition of a plurality of tank cleaning assemblies permanently installed within a ship's cargo tank.

DESCRIPTION OF A PREFERRED EMBODIMENT

FIGS. 1 and 2 illustrate the rotary head assembly 10 of a preferred embodiment of the ship's cargo tank cleaner. The assembly is constructed on a cylindrically-shaped conduit member 12 which has an axial passage 14 extending through it and terminating at each end in a means, such as screw threads 16 and 18, respectively, to connect either end selectively to a source of cleaning fluid under pressure. In these figures, the phantom lines 20 indicate a cleaning fluid supply pipeline connected to the top end of the conduit member 12. A housing 22 circumferentially surrounds a portion of the cylindrical member 12 and is mounted for rotation in a plane at right angles to the cylindrical member. A projection 24 extends radially from the housing 22 and is disposed in a plane at right angles to the cylindrical member. This projection supports a nozzle carrier 26 which is mounted on it for rotation in a plane at right angles to the longitudinal axis A--A of the projection. Hence, the nozzles are disposed to rotate in a plane parallel to the longitudinal axis B--B of the cylindrical member 12. A fluid passage 28 extends through the projection 24 with one end of it in communication with the passage 14 in the cylindrical conduit member 12, and with the other end of the passage in communication with the nozzles of the device, the construction and disposition of which will be described in more detail hereinafter.

The nozzle carrier 26 has disposed on it a set of principal or driving nozzles and an opposing set of secondary or retarding nozzles. In the illustrated embodiment, each set contains a pair of nozzles. However, as the description of the invention proceeds, it will become apparent that the sets are not limited to pairs of nozzles but that sets may include other numbers of nozzles than two without departing from advantageous operating features of this invention.

As illustrated, the nozzles 30 and 32 comprise the principal nozzles. These nozzles are mounted on the carrier 26 with the individual nozzles of the pair placed respectively on opposite sides of, and spaced similarly circumferentially about and radially apart from the central axis of rotation A--A of the nozzle carrier. Thus the nozzle 30 is mounted on and projects laterally from a side 34 of the nozzle carrier while the nozzle 32 is mounted on and projects laterally from the opposite side 36 of the carrier. The nozzles are positioned and directed so that their reaction will produce equal and balanced forces on the nozzle carrier which will induce it to rotate smoothly about its axis of rotation A--A.

The secondary nozzles are mounted on the nozzle carrier in a manner such that the forces of reaction from them will oppose the reaction forces which occur from the principal nozzles. In the illustrated embodiment of the invention, the secondary nozzles are directly complementary to the principal nozzles and each of the secondary nozzles is mounted on the nozzle carrier in a position colinear with but opposing a respective principal nozzle. Thus the nozzle 38 is mounted on the carrier 26 on the side 36 in line with but directed oppositely from the principal nozzle 30. Likewise, the secondary nozzle 40 is mounted on the side 34 of the carrier to directly oppose the action of the principal nozzle 32.

The nozzle carrier 26 is supported on the projection 24 on bearings 42 and 44 which permit it to rotate with respect to the projection. Packing means such as 0-rings 46 and 48, respectively, are incorporated in the bearings to prevent the leakage of fluid from the device. Low friction thrust bearing washers 50 and 52 are placed at the respective axial ends of the nozzle carrier and the sub assembly is retained in position by a cap means 54 which is securely fastened to the end of the projection 24 as by the screw elements 56. A bevel gear 58 is securely affixed to the nozzle carrier sub assembly and may be held in place by a keeper 60 which is screw threaded onto the end of the nozzle carrier to capture the bevel gear between it and the guard element 62. The bevel gear rotates with the nozzle carrier in a unitary manner.

Still referring to FIG. 2, a circumferential projection 64 extends radially outwardly from the lower portion of the cylindrical conduit member 12. This projection provides a radially extending circumferential shoulder 66, the outer circumferential portion of which is formed as an axially upwardly extending secondary shoulder means 68 to thus form a channel designed to hold a low friction thrust bearing washer 70. A complementary radially extending circumferential shoulder 72 is formed on the lower end of the housing 22 to rest on the top of the bearing washer 70 to support the housing on the conduit member 12 while permitting relative rotation between these elements. A retainer ring 74 is secured to the conduit member 12 adjacent the top end of the housing 22 and a low friction washer 76 is placed between the retainer ring and the top end of the housing to hold the housing in axial position on the conduit while permitting easy rotation of it. A packing means such as the 0-ring 78 is placed between the inner circumferential wall of the housing adjacent its top end and the outer circumferential wall of the conduit member to prevent the leakage of fluid from this area of the device.

A bevel gear 80 is securely affixed to the lower end portion of the conduit member 12 in a stationary manner and is located to mesh with the complementary bevel gear 58 on the nozzle carrier. The bevel gear may be captured between the projection 64 and the guard element 82 and held in place by the retaining nut 84 which engages appropriate screw threads on the outer circumferential wall of the lower end 86 of the conduit member 12.

It will be apparent from the structure described thus far that as the nozzle carrier 26 rotates around the axis A--A of the projection 24 the interengaged bevel gears 58 and 80 will cause the housing 22, the projection 24 and the nozzle carrier 26 mounted on it to traverse a circumferential path about the axis B--B of the cylindrical member 12. Thus the jets of cleaning fluid projected from the nozzles will be directed toward all of the interior surfaces of a cargo tank to perform their cleaning function. It is desirable to place different numbers of teeth on each of the respective bevel gears so that the jets of cleaning fluid will not repeat identical paths on sequential complete cycles of the apparatus. Thus if the bevel gear 80 is formed with 51 teeth and the mating bevel gear 58 is formed with 50 teeth, the projection 24 will be displaced circumferentially one-fiftieth of a revolution about the axis B--B of the cylindrical member 12 each time the nozzle carrier makes a complete revolution, and as the next cycle of the apparatus is started the jets of cleaning fluid impinging on the tank wall will be displaced a like amount from the paths taken by the jets in the previous cycle so that eventually all of the interior surface of the tank will be acted on by direct impingement of the jets.

The passage 14 through the conduit member 12 is formed with a portion 88 of reduced cross section. Openings 90 formed through the wall of the conduit member in this area permit fluid flow from the passage 14 into the passage 28 of the projection 24. Openings 92 through the wall of the projection 24 provide communication between the passage 28 and the interior chamber 94 of the nozzle carrier 26. A fluid flow diverter 96 is positioned at the radially outer end of the projection 24 and within the passage 28 to provide a smooth and efficient flow of fluid from the passage 28 into the chamber 94 of the nozzle carrier. A similar diverting element 98 is placed within the passage 14 of the conduit member to divert the stream of cleaning fluid smoothly into passage 28. The diverting element 98 is detachably mountable within the passage 14 for a reason to be explained hereinafter.

As noted previously, a packing means such as the O-ring 78 placed between a conduit member 12 and the housing 22 prevents leakage of fluid out of this section of the apparatus. However, at the lower section of the assembly the bearing washer 70 is exposed to the pressure of the fluid in the passage 14. The operating pressure of this apparatus may be increased from a lesser amount up to 150 to 200 pounds per square inch. Increasing the pressure can cause the washer to press with increased force against the shoulder surfaces engaging it or can cause the washer to function as a piston which pushes the housing 22 upwardly with increased force against the washer 76. In either case, the increased pressure of the cleaning fluid on the washer 70 increases the friction experienced by the housing member 22 in rotating about the axis of the conduit member. This friction is controlled by forming fluid passages 100 in the washer 70 and by placing radially disposed holes 102 through the secondary shoulder portion 68 of projection 64 to provide relief passages for the pressure of the fluid in the environment of the thrust bearing washer 70. The size and disposition of the passages 100 and particularly of the holes 102 are selected to control the amount of pressure imposed on the bearing washer 70 by the pressure of the cleaning fluid stream, and hence this arrangement functions as governor or brake to assist in controlling the speed of rotation of the apparatus.

As best illustrated in FIG. 3 and using the nozzle 30 as illustrating some features common to all of the nozzle structures, the nozzles are mounted on the nozzle carrier by a screw threaded connection 104. These connections preferably are of the same size for each of the nozzles so that the nozzles can be interchanged in position on the nozzle carrier. As explained heretofore, in the presently described embodiment of the invention the nozzles 30 and 32 are of identical size including each having the same sized exit orifice 106 and 108, respectively. The secondary nozzles 38 and 40 also are identical to each other and each has the same size of exit orifice 110 and 112, respectively. However, the exit orifice of a secondary nozzle is smaller in diameter than that of a principal nozzle.

The interior chamber 114 of each nozzle is in fluid communication with the interior chamber 94 of the nozzle carrier and each nozzle is exposed to the same pressure of cleaning fluid. The nozzles of each set preferably are proportioned to have maximum efficiency of fluid transmission in accordance with the size of their respective exit orifice, and vanes 116 and 118 are placed within the nozzle passage of the respective sets to reduce turbulence and loss of energy in the streams of fluid passing through the nozzles. It follows from this construction that a greater mass of fluid per unit time and hence a more forceful jet stream is ejected from a principal nozzle than from a secondary nozzle. In the embodiment of the invention illustrated in FIGS. 1 and 3, each of the nozzles is spaced the same radial distance from the center of rotation of the nozzle carrier. Thus as the several nozzle structures simultaneously react from the force of the jets issuing from them there will be a resultant turning force on the nozzle carrier in a direction away from that of the tangential path of the principal jets. This resultant force not only provides the energy required to rotate the nozzle carrier about the axis A--A but also provides the force which causes the nozzles to traverse a circumferential path around the axis B--B.

The speed of rotation of the nozzles around both of the above described axes is regulated by controlling the effective turning force placed on the apparatus by the net reaction of the nozzle sets. At a particular working pressure, as the force of the jets issuing from the secondary or retarding set of nozzles is made smaller in relation to that of the jets issuing from the principal or driving nozzles, the effective turning force and hence the speed of rotation of the nozzles about both axes is increased. Conversely, as the force of the jets from the second set of nozzles approaches that from the first set, the net effective turning force is decreased. In accordance with this invention, provision is made for changing the size of the exit orifice of each nozzle to provide the jet size and the speed of rotation of the apparatus best suited for a particular cleaning operation in a manner to be described hereinafter.

An important result of the nozzle arrangement of this invention follows from using the difference between the forces of reaction from the principal jets and the secondary jets as the effective operating force for the apparatus. Both sets of jets will be affected in a similar manner by any change in the pressure of the cleaning fluid in the supply line 20 and the reaction force at both sets of nozzles will increase or decrease simultaneously as the supply line pressure increases or decreases. Hence, the resultant difference between these forces will not increase or decrease to the degree that the pressure of the fluid in the supply line changes. Since the speed at which the nozzles rotate and revolve is regulated primarily by the net resultant force of reaction from the jets, this speed will remain relatively constant while the pressure in the fluid supply line varies. Therefore, once the appropriate orifice sizes for the sets of jets are selected for a particular cleaning operation, this apparatus will operate within the desired range of speed even though there is considerable variation in the pressure of the cleaning fluid supply line.

FIG. 5 illustrates the end portion 120 of a nozzle in which the exit orifice 122 is formed in a tip element 124 which is detachably connected to the end of the nozzle as by screw threads 126. A selection of pairs of nozzle tips having discharged orifices of different internal diameters are calibrated for the reaction force produced by the nozzle and tip combination for various pressure and temperatures of the cleaning fluid. Thus particular sets of the tips may be preselected for use on the principal and on the secondary nozzles to produce an appropriate size of cleaning jet and a desired speed of rotation of the apparatus. It will be noted particularly that this control means does not require that the principal jets be decreased in force or volume below the amount desired for adequate cleaning action since speed regulation can be obtained by increasing or decreasing the size of the exit orifice of the secondary jets while maintaining the optimum size of the cleaning jets from the principal nozzles. An additional advantage of this invention is that the secondary nozzles also will produce jets of cleaning fluid which will supplement and aid the cleaning action of the principal jets.

FIG. 7 illustrates a modification of the apparatus which can be applied particularly when the operating pressure of the cleaning fluid is standardized on a particular vessel. In this modification all of the nozzles of both sets are similar in size and construction including having the same size of exit orifice and can be interchangeably mounted one for the other in any position on the nozzle carrier 26. The net effective turning force on the apparatus is obtained by locating the principal nozzles 30 and 32 at a greater respective radial distance from the center of rotation A--A of the nozzle carrier than that of the secondary nozzles 128 and 130 and this distance is selected in accordance with the size of the jet orifice and the preselected standardized pressure of the cleaning fluid to produce a net turning force which will regulate the turning speed of the apparatus to a desired value. However, if the operating pressure of the cleaning fluid should be changed appreciably from that for which this modification of the device was designed, it can be adjusted by applying to it the modification described in relation to FIG. 5 to regulate the jet size and speed as appropriate for the changed conditions. It is also within the concept of this invention that the interchangeability feature of the nozzles as described for FIG. 7 can be applied to the modification of the apparatus illustrated in FIG. 1 and that the net effective turning force on the apparatus can be regulated by placing on the sets of nozzles selected tips of appropriate exit orifice size as described for the modification illustrated in FIG. 5.

Referring again to FIG. 2, as described heretofore the housing 22 rests on the thrust bearing washer 70 and is held in axial position on the conduit member 12 by the retaining ring 74 and the bearing washer 76. The preferred operating position for the apparatus is as thus illustrated and described with the axis B--B of the conduit member 12 in a vertically oriented position and with the thrust bearing washer 70 and the bevel gear 80 placed at the lower end of the combination. Also, as described heretofore, the apparatus is made to accommodate the connection of a cleaning fluid supply conduit 20 to either the top end or to the bottom end of the conduit member 12.

When the supply conduit is connected to the top end of the conduit member 12 the fluid stream diverting element 98 is mounted within the passage 14 at a position on the downstream side of the openings 90 through which the stream of fluid is diverted into the passage 28 in the projection 24. In the illustration of FIG. 2 the diverting element 98 is detachably mounted on the shoulder 132 which is formed to extend a short distance radially inwardly into the passage 14, a screw threaded connection 134 between the diverting element and the shoulder being used for this purpose. A similar screw threaded shoulder 136 is formed on the axially opposite side of the openings 90 and the diverting element 98 may be dismounted from the location illustrated in FIG. 2 and remounted on the shoulder 136 in the position illustrated in FIG. 6 to divert the stream of cleaning fluid into the passage 28 from a supply conduit connected to the bottom end of the conduit member 12. By thus providing a means to accommodate the connection of the cleaning fluid supply conduit to either end of the apparatus while maintaining the preferred vertical orientation of it the structure of the apparatus is standardized so that the same rotating head can be connected to supply conduits extending vertically downwardly or vertically upwardly within the cargo tank by adjusting the position of the diverting element 98.

FIG. 8 illustrates schematically a plurality of rotary head assemblies 10 placed within a cargo tank 138 of a large oil tanker. The devices of this invention are designed to operate dependably for long periods of time without requiring adjustment or other attention. Therefore, it is feasible to place these devices within the cargo tank as substantially permanent installations disposed throughout the tank in the optimum locations to provide a thorough cleaning of it. The use of multiple rotating heads provides effective cleaning jets impinging on the inner walls throughout a large cargo tank while using a pressure of cleaning fluid readily available from apparatus normally aboard ship.

As illustrated, the permanently installed head assemblies 10 may be connected in various combinations through a manifold 140 and pipes 142 to permit particular portions of the cargo tank to be exposed for a longer or a shorter time to the cleaning action of selected jets. This figure also illustrates an arrangement for treating the cleaning fluid which will be directed to the jets by passing it through a pump 144 to increase the pressure in the fluid to the desired operating pressure for effective jet action, thence passing it through a heat exchanger 146 which can increase the temperature of the fluid through a range preferably up to approximately 200°F. In accordance with the present invention the cleaning fluid is then passed into the manifold 140 from which it can be directed by means of valves 148 to some or all of the rotating head assemblies 10 as described heretofore.

Since the apparatus of the present invention is adaptable for connection to permanently installed cleaning fluid supply lines 142 entering the cargo tank from different directions it is possible to construct the supply lines into the structure of the tank at positions where the pipes will be least exposed to damage while at the same time locating the head assemblies where they will most effectively accomplish the cleaning operation.

From the foregoing specification various other modifications of this invention will become apparent to those skilled in the art, and all such modifications falling within the scope of the appended claims are intended to be included therein.