BALLAST
United States Patent 3559609
Water borne vessels are ballasted using a substantially liquid free composition containing a weighting agent such as barite or a weighting agent coated with a hydrophobic agent such as stearic acid. The composition can contain at least one clay to adjust the bulk density to a predetermined value and at least one desiccant.
Inventors:
Sydow Jr., Charles H. (Houston, TX)
Van Dyke, Orien W. (Houston, TX)
Van Dyke, Orien W. (Houston, TX)
Application Number:
04/787584
Publication Date:
02/02/1971
Filing Date:
12/27/1968
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Export Citation:
Assignee:
Dresser Industries, Inc. (Dallas, TX)
Primary Class:
International Classes:
B63B3/14; B63B3/00; B63B43/06
Field of Search:
114/125,74
Primary Examiner:
Blix, Trygve M.
Claims:
We claim
1. A method of ballasting a waterborne vessel having ballast tanks comprising introducing into said tanks an effective ballasting amount of a substantially liquid free composition consisting essentially of at least one subdivided mineral weighting agent, said weighting agent being subdivided sufficiently to render same fluidizable with a gas and transportable in the fluidized state and coating said weighting agent with at least one hydrophobic agent in a an amount sufficient to render said composition substantially water repellent.
2. The method according to claim 1 wherein said weighting agent is one of barite, galena, ferrophorous, speiss, calcite, limestone, dolemite, magnetite, hematite, celestite, witherite, pyrite, silica, quartzite and mixtures of at least two thereof, including the additional step of subdividing said weighting agent to substantially all pass a 200 mesh screen, and the hydrophobic agent is one of saturated or unsaturated fatty acids, metal salts of said fatty acids, and mixtures of at least two thereof.
3. The method according to claim 2 wherein said coating step produces a composition containing from about 0.1 to about 1.5 weight percent hydrophobic agent,
4. The method according to claim 1 including the additional step of adding to said composition at least one clay in an amount sufficient to lower the bulk density of the composition to a predetermined value.
5. The method according to claim 4 wherein said clay is added in amounts sufficient to give said composition a bulk density of from about 75 to about 200 lbs. per cubic foot.
6. The method according to claim 4 wherein said clay is one of kaolin, bentonite, attapulgite, sepiolite and mixtures of at least two thereof. 7The method according to claim 1 including the additional step of adding to said composition at least one desiccant in an amount at least
1. A method of ballasting a waterborne vessel having ballast tanks comprising introducing into said tanks an effective ballasting amount of a substantially liquid free composition consisting essentially of at least one subdivided mineral weighting agent, said weighting agent being subdivided sufficiently to render same fluidizable with a gas and transportable in the fluidized state and coating said weighting agent with at least one hydrophobic agent in a an amount sufficient to render said composition substantially water repellent.
2. The method according to claim 1 wherein said weighting agent is one of barite, galena, ferrophorous, speiss, calcite, limestone, dolemite, magnetite, hematite, celestite, witherite, pyrite, silica, quartzite and mixtures of at least two thereof, including the additional step of subdividing said weighting agent to substantially all pass a 200 mesh screen, and the hydrophobic agent is one of saturated or unsaturated fatty acids, metal salts of said fatty acids, and mixtures of at least two thereof.
3. The method according to claim 2 wherein said coating step produces a composition containing from about 0.1 to about 1.5 weight percent hydrophobic agent,
4. The method according to claim 1 including the additional step of adding to said composition at least one clay in an amount sufficient to lower the bulk density of the composition to a predetermined value.
5. The method according to claim 4 wherein said clay is added in amounts sufficient to give said composition a bulk density of from about 75 to about 200 lbs. per cubic foot.
6. The method according to claim 4 wherein said clay is one of kaolin, bentonite, attapulgite, sepiolite and mixtures of at least two thereof. 7The method according to claim 1 including the additional step of adding to said composition at least one desiccant in an amount at least
Description:
BACKGROUND OF THE INVENTION
Heretofore liquids have been employed for ballasting waterborne vessels such as cargo ships. Ballasting comprises introducing a relatively heavy material into a lower portion of the vessel, e.g., has ballast tanks on the bottom of the vessel, thereby lowering the center of gravity of the vessel and any cargo therein. The ballast adds stability to the vessel particularly when the vessel's cargo is placed so that a high center of gravity results, e.g., when containerized cargo is transported.
The use of liquids as ballasting materials is advantageous in that ballasting tanks are normally relatively inaccessible to anything but a hoselike conduit, and liquids can readily be pumped into and pumped from these ballast tanks. However, liquid ballasts which use water as the suspending medium have certain inherent disadvantages. One disadvantage is possible bacterial growth after extended periods of time unless the ballast fluid is pumped out and the bacteriostatic agent replenished. Another disadvantage is a strong likelihood for corrosion at the air-water interface and the mud-water interface. Another disadvantage is a strong likelihood for excessive gellation to occur thereby making removal of a liquid ballast difficult. Yet another disadvantage is the possible settling of the weighting agent into a hard packed layer. It is extremely difficult to adjust the rheological properties of a ballast liquid to prevent settling of the weighting agent and still remain pumpable for easy removal from the ballast tanks.
SUMMARY OF THE INVENTION
According to this invention there is provided a ballast composition which can be made to flow into ballast tanks much like a liquid but which is substantially liquid free thereby eliminating corrosion, bacteria, gellation, and settling problems. The ballast composition of this invention can be pumped into the ballast tanks and substantially forgotten since there is no need to check for bacteria, settling, excessive gellation or corrosiveness of the ballast even after long use. The ballast of this invention is therefore essentially inert and does not change with time.
There is also provided a method of a ballasting a vessel by introducing into the ballast tanks of that vessel an effective ballasting amount of a substantially liquid-free composition containing a subdivided weighting agent or a subdivided weighting agent and a hydrophobic agent which renders the composition substantially water repellent.
There is further provided the combination of a vessel whose ballast tanks contain the substantially dry composition of this invention.
It is therefore an object of this invention to provide a new and improved method of ballasting waterborne vessels. It is another object of this invention to provide an a new and improved combination of waterborne vessels and substantially dry ballast.
Other aspects, objects, and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention there is provided a ballasting method comprising introducing into the ballast tanks of a vessel and an effective ballasting amount, i.e., an amount sufficient to lower the center of gravity of the vessel, of a composition formed from comminuted or otherwise subdivided mineral weighting agent. The weighting agent can be substantially coated with a water-insoluble hydrophobic agent in an amount sufficient to render the composition substantially water repellent.
The weighting agent can be any mineral which can be used in a major amount, i.e., from about 50 to about 100 weight percent based on the total weight of the composition, to produce a composition having a bulk density of from about 75 to about 200, preferably from about 125 to about 150, lbs. per cubic foot. Suitable minerals include barite, galena, ferrophosphorous, speiss, calcite, limestone, dolemite, magnetite, hematite, celestite, witherite, silica, quartzite, volcanic ash, clay minerals, and mixtures of at least two thereof.
The weighting agent is subdivided sufficiently to render same capable of being fluidized with a gas such as air and then transported in the fluidized state. This allows the composition to be transported and pneumatically introduced into and removed from the ballast tanks of a vessel. Generally, the weighting agent will be subdivided so as to substantially all pass a 200 mesh screen (standard Tyler series). Depending upon the particular weighting agent or agents employed, finer grinding such as to substantially all pass a 325 mesh standard Tyler screen may be necessary but this will be obvious to one skilled in the art with the ultimate goal of rendering the composition substantially free flowing by fluidizing with a gas such as air.
The hydrophobic agent can be any material which is insoluble in water and which can be coated on the weighting agent particles in an amount suffice sufficient to render the composition substantially water repellent. Particular hydrophobic agents include saturated or unsaturated fatty acids containing from 10 to 31, inclusive, carbon atoms per molecule, water insoluble metal salts of these fatty acids, particularly calcium and magnesium salts, and mixtures of at least two thereof. Useful fatty acids include stearic acid and palmitic acid.
The weighting agent can be coated with a hydrophobic agent or agents in any conventional manner such as by forming a liquid solution or slurry of the hydrophobic agent, adding same to the weighting agent with mixing to form a homogeneous mixture, and drying resulting mixture. Substantially dry weighting agent and hydrophobic agent can be mixed with one another by grinding in the normal manner that the weighting agent would be ground without the coating agent. This affects the coating results without the use of a liquid and is the preferred method.
The amount of hydrophobic agent employed will vary widely depending upon the hydrophobic agent selected and the weighting materials to be treated as well as the desired degree of moisture repellency. However, generally the composition will contain from about 0.1 to about 1.5 weight percent hydrophobic agent based upon the total weight of the composition, the remainder of the composition being essentially weighting agent.
The composition of this invention can additionally contain, as an optional ingredient, at least one clay in an amount sufficient to lower the bulk density of the composition to a predetermined value and enhance the ability of the composition to resist hard packing over extended periods of time. The clay or clays can be added in an amount sufficient to give the composition the desired bulk density of from about 75 to about 200 lbs. per cubic foot. Suitable clays include kaolin, bentonite, attapulgite, sepiolite and the like, kaolin or attapulgite being preferred, and mixtures of at least two thereof.
Desiccants which are substantially inert to the weighting agent and any hydrophobic agent that may be present can, if desired, be mixed with the composition of this invention in an amount at least sufficient to substantially absorb moisture of condensation. The amount of desiccant used will vary widely but can be from about 1 to about 5 weight percent based on the total weight of the composition. Suitable desiccants include silica gel, calcium hydroxide, calcium oxide, magnesia, dolomite, activated montmorillonite clay, and the like, and mixtures thereof.
The clays and/or desiccants can be added to the weighting agent before, during, and/or after coating of the weighting agent with the hydrophobic agent. Conventional mixing techniques can be used to obtain a homogeneous mixture of the clay and/or desiccant with the ballast composition.
The resulting ballast composition can then be fluidized so as to render same substantially free flowing by conventional fluidizing techniques, e.g., passing a large amount of air into the composition using conventional fluidizing equipment. The thus fluidized composition can be transported into a ballast tank just as a liquid would be pumped thereinto after which the transporting air escapes from the ballast tank leaving a compact layer of the dry, noncorrosive ballast composition of this invention in the ballast tank. This layer will not slosh or shift due to the motion of the vessel.
Removal of the ballast composition from the ballast tanks need never be effected since the ballast is inert and is not corrosive nor attacked by a bacteria. However, should removal be desired for other reasons, such as inspection of the ballast tanks, the composition can be fluidized by the introduction of air and removed from the ballast tanks in substantially the same manner in which it was introduced into the ballast tanks.
In this invention the terms "dry," "substantially dry," "substantially liquid free," "substantially and the like encompasses the presence of no more than 5 weight percent water based on the total weight of the composition.
EXAMPLE I
A ballast composition is prepared by grinding 2,000 lbs. of barite, and 10 lbs. of stearic acid, together in a 54 inches Raymond roller mill.
The resulting mixture has a bulk density of about 140 lbs. per cubic foot and is substantially water repellent.
This ballast composition is fluidized by introducing compressed air under approximately 15--20 p.s.i.g. into the container containing the ballast. The air is introduced through a false bottom which is a 10 inches canvass air slide. This aerates and fluidizes the ballast and the air flowing through a discharge hose carries the ballast, in this fluidized condition, into a ballast tank for ballasting the vessel containing the tank.
EXAMPLE II
Barite in the amount of 250,000 pounds was ground with 875 lbs. (about 3.5 weight percent based on the total weight of the composition) of stearic acid in a 66 inch Raymond roller mill. Grinding was carried out at a rate of about 17 tons per hour and until a homogeneous mixture was obtained in which the stearic acid substantially coated the barite particles. The mixture had the following properties:
Specific gravity, grams/cubic centimeter 4.25
Bulk density, lbs. per cubic foot 127
Water Wettability Nonwettable
Percent Passing 200 mesh Tyler screen 92
Percent Passing 325 mesh Tyler screen 78
This mixture was transported to a cargo ship by way of a barge and the mixture transferred to a bottom hold of the ship using an air compressor and a conventional pneumatic conveyor known as an "air bazooka." The pneumatic conveyor was composed of a hopper, an air compartment, and a 2 foot long screw conveyor extending from the bottom of the hopper to the air compartment.
The hopper of the pneumatic conveyor was filled with the barite-stearic acid mixture. The mixture was then fed to the air compartment by the screw conveyor and fluidized in the air compartment using compressed air at 15 p.s.i.g. (about 30 p.s.i.a.).
The fluidized mixture was transported by the compressed air moving through the air compartment into a 4 inch diameter rubber hose. The outlet end of the rubber hose was placed in the hold of the ship to be filled. The hold of the ship was then filled in this manner with the entire mixture.
The ship was thereby ballasted in an a manner and with an ease similar to that of ballasting with liquid ballast. However, the ballast mixture of this example need not be checked in future years for corrosion, bacterial attack, and the like.
Further, in rolling seas the ballast of this example did not shift back and forth in the hold as would a liquid ballast thereby adding an extra dimension of stability to the ship. The extra stability that is routinely enjoyed when using the ballast of this invention is not normally attainable with liquid ballast absent special and costly precautionary procedures such as maintaining the hold liquid full at all times.
Reasonable variations and modifications ate possible within the scope of this disclosure without departing from the spirit and scope of this invention.
Heretofore liquids have been employed for ballasting waterborne vessels such as cargo ships. Ballasting comprises introducing a relatively heavy material into a lower portion of the vessel, e.g., has ballast tanks on the bottom of the vessel, thereby lowering the center of gravity of the vessel and any cargo therein. The ballast adds stability to the vessel particularly when the vessel's cargo is placed so that a high center of gravity results, e.g., when containerized cargo is transported.
The use of liquids as ballasting materials is advantageous in that ballasting tanks are normally relatively inaccessible to anything but a hoselike conduit, and liquids can readily be pumped into and pumped from these ballast tanks. However, liquid ballasts which use water as the suspending medium have certain inherent disadvantages. One disadvantage is possible bacterial growth after extended periods of time unless the ballast fluid is pumped out and the bacteriostatic agent replenished. Another disadvantage is a strong likelihood for corrosion at the air-water interface and the mud-water interface. Another disadvantage is a strong likelihood for excessive gellation to occur thereby making removal of a liquid ballast difficult. Yet another disadvantage is the possible settling of the weighting agent into a hard packed layer. It is extremely difficult to adjust the rheological properties of a ballast liquid to prevent settling of the weighting agent and still remain pumpable for easy removal from the ballast tanks.
SUMMARY OF THE INVENTION
According to this invention there is provided a ballast composition which can be made to flow into ballast tanks much like a liquid but which is substantially liquid free thereby eliminating corrosion, bacteria, gellation, and settling problems. The ballast composition of this invention can be pumped into the ballast tanks and substantially forgotten since there is no need to check for bacteria, settling, excessive gellation or corrosiveness of the ballast even after long use. The ballast of this invention is therefore essentially inert and does not change with time.
There is also provided a method of a ballasting a vessel by introducing into the ballast tanks of that vessel an effective ballasting amount of a substantially liquid-free composition containing a subdivided weighting agent or a subdivided weighting agent and a hydrophobic agent which renders the composition substantially water repellent.
There is further provided the combination of a vessel whose ballast tanks contain the substantially dry composition of this invention.
It is therefore an object of this invention to provide a new and improved method of ballasting waterborne vessels. It is another object of this invention to provide an a new and improved combination of waterborne vessels and substantially dry ballast.
Other aspects, objects, and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
According to this invention there is provided a ballasting method comprising introducing into the ballast tanks of a vessel and an effective ballasting amount, i.e., an amount sufficient to lower the center of gravity of the vessel, of a composition formed from comminuted or otherwise subdivided mineral weighting agent. The weighting agent can be substantially coated with a water-insoluble hydrophobic agent in an amount sufficient to render the composition substantially water repellent.
The weighting agent can be any mineral which can be used in a major amount, i.e., from about 50 to about 100 weight percent based on the total weight of the composition, to produce a composition having a bulk density of from about 75 to about 200, preferably from about 125 to about 150, lbs. per cubic foot. Suitable minerals include barite, galena, ferrophosphorous, speiss, calcite, limestone, dolemite, magnetite, hematite, celestite, witherite, silica, quartzite, volcanic ash, clay minerals, and mixtures of at least two thereof.
The weighting agent is subdivided sufficiently to render same capable of being fluidized with a gas such as air and then transported in the fluidized state. This allows the composition to be transported and pneumatically introduced into and removed from the ballast tanks of a vessel. Generally, the weighting agent will be subdivided so as to substantially all pass a 200 mesh screen (standard Tyler series). Depending upon the particular weighting agent or agents employed, finer grinding such as to substantially all pass a 325 mesh standard Tyler screen may be necessary but this will be obvious to one skilled in the art with the ultimate goal of rendering the composition substantially free flowing by fluidizing with a gas such as air.
The hydrophobic agent can be any material which is insoluble in water and which can be coated on the weighting agent particles in an amount suffice sufficient to render the composition substantially water repellent. Particular hydrophobic agents include saturated or unsaturated fatty acids containing from 10 to 31, inclusive, carbon atoms per molecule, water insoluble metal salts of these fatty acids, particularly calcium and magnesium salts, and mixtures of at least two thereof. Useful fatty acids include stearic acid and palmitic acid.
The weighting agent can be coated with a hydrophobic agent or agents in any conventional manner such as by forming a liquid solution or slurry of the hydrophobic agent, adding same to the weighting agent with mixing to form a homogeneous mixture, and drying resulting mixture. Substantially dry weighting agent and hydrophobic agent can be mixed with one another by grinding in the normal manner that the weighting agent would be ground without the coating agent. This affects the coating results without the use of a liquid and is the preferred method.
The amount of hydrophobic agent employed will vary widely depending upon the hydrophobic agent selected and the weighting materials to be treated as well as the desired degree of moisture repellency. However, generally the composition will contain from about 0.1 to about 1.5 weight percent hydrophobic agent based upon the total weight of the composition, the remainder of the composition being essentially weighting agent.
The composition of this invention can additionally contain, as an optional ingredient, at least one clay in an amount sufficient to lower the bulk density of the composition to a predetermined value and enhance the ability of the composition to resist hard packing over extended periods of time. The clay or clays can be added in an amount sufficient to give the composition the desired bulk density of from about 75 to about 200 lbs. per cubic foot. Suitable clays include kaolin, bentonite, attapulgite, sepiolite and the like, kaolin or attapulgite being preferred, and mixtures of at least two thereof.
Desiccants which are substantially inert to the weighting agent and any hydrophobic agent that may be present can, if desired, be mixed with the composition of this invention in an amount at least sufficient to substantially absorb moisture of condensation. The amount of desiccant used will vary widely but can be from about 1 to about 5 weight percent based on the total weight of the composition. Suitable desiccants include silica gel, calcium hydroxide, calcium oxide, magnesia, dolomite, activated montmorillonite clay, and the like, and mixtures thereof.
The clays and/or desiccants can be added to the weighting agent before, during, and/or after coating of the weighting agent with the hydrophobic agent. Conventional mixing techniques can be used to obtain a homogeneous mixture of the clay and/or desiccant with the ballast composition.
The resulting ballast composition can then be fluidized so as to render same substantially free flowing by conventional fluidizing techniques, e.g., passing a large amount of air into the composition using conventional fluidizing equipment. The thus fluidized composition can be transported into a ballast tank just as a liquid would be pumped thereinto after which the transporting air escapes from the ballast tank leaving a compact layer of the dry, noncorrosive ballast composition of this invention in the ballast tank. This layer will not slosh or shift due to the motion of the vessel.
Removal of the ballast composition from the ballast tanks need never be effected since the ballast is inert and is not corrosive nor attacked by a bacteria. However, should removal be desired for other reasons, such as inspection of the ballast tanks, the composition can be fluidized by the introduction of air and removed from the ballast tanks in substantially the same manner in which it was introduced into the ballast tanks.
In this invention the terms "dry," "substantially dry," "substantially liquid free," "substantially and the like encompasses the presence of no more than 5 weight percent water based on the total weight of the composition.
EXAMPLE I
A ballast composition is prepared by grinding 2,000 lbs. of barite, and 10 lbs. of stearic acid, together in a 54 inches Raymond roller mill.
The resulting mixture has a bulk density of about 140 lbs. per cubic foot and is substantially water repellent.
This ballast composition is fluidized by introducing compressed air under approximately 15--20 p.s.i.g. into the container containing the ballast. The air is introduced through a false bottom which is a 10 inches canvass air slide. This aerates and fluidizes the ballast and the air flowing through a discharge hose carries the ballast, in this fluidized condition, into a ballast tank for ballasting the vessel containing the tank.
EXAMPLE II
Barite in the amount of 250,000 pounds was ground with 875 lbs. (about 3.5 weight percent based on the total weight of the composition) of stearic acid in a 66 inch Raymond roller mill. Grinding was carried out at a rate of about 17 tons per hour and until a homogeneous mixture was obtained in which the stearic acid substantially coated the barite particles. The mixture had the following properties:
Specific gravity, grams/cubic centimeter 4.25
Bulk density, lbs. per cubic foot 127
Water Wettability Nonwettable
Percent Passing 200 mesh Tyler screen 92
Percent Passing 325 mesh Tyler screen 78
This mixture was transported to a cargo ship by way of a barge and the mixture transferred to a bottom hold of the ship using an air compressor and a conventional pneumatic conveyor known as an "air bazooka." The pneumatic conveyor was composed of a hopper, an air compartment, and a 2 foot long screw conveyor extending from the bottom of the hopper to the air compartment.
The hopper of the pneumatic conveyor was filled with the barite-stearic acid mixture. The mixture was then fed to the air compartment by the screw conveyor and fluidized in the air compartment using compressed air at 15 p.s.i.g. (about 30 p.s.i.a.).
The fluidized mixture was transported by the compressed air moving through the air compartment into a 4 inch diameter rubber hose. The outlet end of the rubber hose was placed in the hold of the ship to be filled. The hold of the ship was then filled in this manner with the entire mixture.
The ship was thereby ballasted in an a manner and with an ease similar to that of ballasting with liquid ballast. However, the ballast mixture of this example need not be checked in future years for corrosion, bacterial attack, and the like.
Further, in rolling seas the ballast of this example did not shift back and forth in the hold as would a liquid ballast thereby adding an extra dimension of stability to the ship. The extra stability that is routinely enjoyed when using the ballast of this invention is not normally attainable with liquid ballast absent special and costly precautionary procedures such as maintaining the hold liquid full at all times.
Reasonable variations and modifications ate possible within the scope of this disclosure without departing from the spirit and scope of this invention.