Patent Publication Number: US-8984709-B1

Title: No-entry bulk oil storage tank cleaning system

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     This invention relates to the cleaning of large storage tanks, and more particularly, but not by way of limitation, to the cleaning of a bulk oil storage tank and removing sediments from the bottom of the tank. 
     (b) Discussion of Prior Art 
     Heretofore, large bulk oil storage tanks, ranging in size from 400 to 40,000 plus barrels of crude oil, have been cleaned periodically to check the integrity of the tank structure and maintain usable capacity of the tank by removing sediments from the crude oil, such as sand, clay, water, heavy oil and sludge. Also the build up of the sediments in the tank can plug an oil discharge line, when oil is pumped out of the tank to be delivered to an oil refinery. 
     Currently during the bulk tank cleaning process, one or two workmen enter the inside of the large tank through a removable, manway door in the side of the tank. At this time, high pressure water is introduced through a water jet pipe or a water cannon into the sediment creating a water and sediment slurry. The water and sediment slurry is then vacuumed into a vacuum truck tank and carried to a disposal site. Inside the tank and during the mixing of the high pressure water with the sediment to create a water and sediment slurry, dangerous gases occur. The breathing of these gases can easily cause illness or death to the workman who fails to wear a self-contained breathing apparatus, provided by an oil tank, safety consultant. Because of the added expense, oil and gas companies may or may not hire the safety consultant with the required breathing equipment for their workmen. 
     The subject no-entry, tank cleaning system eliminates the need for one or two workmen to enter the inside of the storage tank and risk breathing dangerous gases. Also, the cleaning system eliminates the high cost of added water delivery trucks, an added water pressure pumping truck and having to hire the air safety consultant with air safety equipment. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing, it is a primary objective of the subject invention to provide a tank cleaning system which eliminates the need for workmen to enter the inside of a bulk oil storage tank and running the risk of breathing noxious gases, when removing sediment from the floor of the tank. 
     Another key object of the invention is the cleaning system greatly reduces the cost of removing sediments from inside the tank by eliminating the need for one or more water tank trucks, a water pressure pumping truck, and a tank air safety consultant with breathing equipment. 
     Still another object of the invention is the cleaning system greatly reduces the time to clean a bulk storage oil tank and reduces the cost of sediment disposal by eliminating the need for creating large amounts of a water and sediment slurry mixture using prior art water jets or water cannons. 
     The subject tank cleaning system includes a vacuum pipe connected to a vacuum truck via a flexible hose, a high pressure air line and a high pressure steam line connected to an air/steam mixing box. The mixing box includes an air nozzle connected to the air line, a steam nozzle connected to the steam line and a suction head of a vacuum tube. The vacuum hose includes a steering, guide rail mounted thereon for receiving a swivel wheel. The swivel wheel is attached to a door opening bracket. The door opening bracket is attached to opposite sides of a manway door opening in a side of the tank. The steering, guide rail pivots on the swivel wheel and allows an operator to move the mixing box back and forth, left and right for engaging and vacuuming up the sediment in the bottom of the storage tank. The system also includes a wheel mounted, finish suction head with high pressure air nozzles, high pressure steam nozzles and a suction head of the vacuum tube. The finish suction head is used to complete the cleaning of the remaining sediment left on the floor of the tank. 
     These and other objects of the present invention will become apparent to those familiar with the cleaning of sediment in large bulk oil storage tanks when reviewing the following detailed description, showing novel construction, combination, and elements as herein described, and more particularly defined by the claims, it being understood that changes in the embodiments of the disclosed invention are meant to be included as coming within the scope of the claims, except insofar as they may be precluded by the prior art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings illustrate complete preferred embodiments in the present invention according to the best modes presently devised for the practical application of subject tank cleaning system, and in which: 
         FIG. 1  is a perspective view of subject tank cleaning system in operation and received through a door opening in the side of a large, bulk oil storage tank. 
         FIG. 2  is a perspective view of an air/steam mixing box with high pressure, air and steam nozzles and an end portion of a vacuum tube centered in the front of the mixing box for receiving sediment loosened by an air and steam mixture. 
         FIG. 3  is a perspective view of a wheel-mounted, finish suction head, with high pressure air and steam nozzles and an end portion of the vacuum tube. 
         FIG. 4  is a perspective view of a swivel wheel mounted on a door mounting bracket. Opposite ends of the mounting bracket are attached to sides of the manway door opening. 
     
    
    
     While the invention has been particularly shown, described and illustrated in detail with reference to the preferred embodiments and modifications thereof, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope of the invention as claimed except as precluded by the prior art. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In  FIG. 1 , a perspective view of subject tank cleaning system is shown having a general reference numeral  10 . The cleaning system  10 , in this embodiment, is shown received through a door opening  12  in the side of a large, bulk oil storage tank  14 . A portion of the opening  12  and the tank  14  have been cutaway to illustrate sediment  16 , which may accumulate up to a foot in a bottom  18  of the tank. The door opening  12  is covered by a door, which can be a single door or a two-part door. In this drawing, the door has been unbolted from outwardly extending, threaded studs  19 , equally spaced along a length of the sides of the opening  12  and removed. A large fan  20  mounted on a stand  22  and disposed next to the door opening  12  can be used for added safety to circulate air into the tank and keep any potential gas vapors, generated by the cleaning system  10 , left inside the tank. Also and in the alternative, a suction hose can be attached to a vent in the top of the storage tank to vacate gas fumes, thus providing a positive, clean air induction at the door opening for further protection of the system&#39;s operator. 
     The cleaning system  10  includes a 4 inch, rail vacuum pipe  24 , a high pressure air line  26 , typically 110 psi, and a high pressure steam line  28 , typically operating at 110 psi and at 300 degrees F., connected to an 8 inch by 8 inch square, air/steam mixing box  30  with a handle  32 . The air line  26  is connected to an air compressor and the steam line  28  is connected to a steam generator. The rail vacuum pipe  24  is connected to a high volume, vacuum truck via a flexible hose. The high volume vacuum is typically 1200 cfm. The compressor, steam generator and vacuum truck aren&#39;t shown in the drawings. While the various dimensions, geometric configurations, pressure and temperature are mentioned above, it should be kept in mind that these features may vary without departing from the spirit and scope of the invention 
     A 2 inch, inverted “U” shaped, steering guide rail  34  is mounted along the bottom and a portion of the length of the rail vacuum pipe  24 . A two inch swivel wheel  36  is mounted on a door opening bracket  38 , having opposite flange ends  40  and  42 , shown in  FIG. 4 , bolted to the sides of the door opening  12 . The swivel wheel  36  rides in the guide rail  34  and allows a workman  44  to move the cleaning system  10  back and forth, as indicated by arrows  46  and sideways, as indicated by arrow  48 , for ease in manipulating the mixing box  30  and covering the bottom of the tank, when vacuuming the sediment inside the tank. 
     In operation and for example, the tank  14  may have from 10 to 24 inches and greater of the semi-solid, sediment  16  prior to cleaning. In this drawing, the air/steam mixing box  30  is used to loosen and vacuumed up the top 20 to 22 inches of sediment. The remaining 2 to 4 inches can be vacuumed up using a wheel mounted, floor finishing head. The finishing head is shown in  FIG. 3 . As the mixing box  30  moves inward from the door opening  12  into the tank  14 , the air/steam mixture dissolves the semi-solid sediment. The sediment then drops downwardly and is sucked into the mixing box leaving a “V” shaped pattern  50  in the sediment to be picked up during the next cleaning pass by the mixing box. The forward direction of the mixing box  30  is indicated by arrow  52 . As mentioned above, the mixing box  30  can be moved forward and side to side, as indicated by arrows  46  and  48 , and until the majority of the sediment  16  is removed using the air and steam mixture and the rail vacuum pipe  24  for removing the sediment from inside the tank  14 . 
     It should be mentioned that using, for example 750 cfm of high pressure air and steam, the mixture of air and steam to remove the sediment is far less expense and far more efficient then using steam alone, which takes up to 5 times longer. Also, using air alone takes longer and the air tends to create balls of sediment making it difficult to vacuum. Another advantage of the air and steam mixture is the sediment is reduced to small grains of sand and clay for ease in vacuuming. Further, the use of air and steam eliminates the high cost of using large volumes of water and the high cost of disposing of large amounts of the water and sludge slurry. 
     In  FIG. 2 , a perspective view of the air/steam mixing box  30  is shown in greater detail. In this drawing a portion of the top of the mixing box  30  has been cutaway to illustrate an air nozzle  54  and a steam nozzle  56 . The two nozzles are mounted in the rear of the enclosed mixing box, and connected to the air and steam lines  26  and  28 . The enclosed mixing box  30  creates an internal, air and steam mixing chamber  57 . The mixing chamber  57  is important in that it acts to regulate air and steam pressure should there be a pressure differential between the high pressure air and the high pressure steam coming out of the nozzles  54  and  56 . Also, the mixing chamber  57  provides for a mixture of the air and steam, shown as arrows  58 , which exits out a plurality of 1/16 inch wide, air/steam mixture slits  60 . The mixture slits  60  can be in a range of ½ to 1 inch in length and are disposed around a periphery of a square-shaped, concave-shaped front portion  62 . 
     The mixing box  30  also includes a mixing box vacuum tube  63 , similar in diameter to the rail vacuum pipe  24 , connected to a camlock coupling  66 . The coupling  66  is used for connecting the vacuum tube  63  to the rail vacuum pipe  24 . A suction head  67  of the vacuum tube  63  is centered in the concave-shaped front portion  62  for receiving the sediment  16 , as it&#39;s loosened by the high pressure air and steam mixture  58  and sucked into the vacuum tube  63 , as indicated by arrows  72 . 
     Further, the mixing box  30  includes a pair of Teflon pads  68  with screws  70  used for securing the pads to the bottom of the box. The Teflon pads  68  provide for ease in moving the mixing box  30  into the sediment  16  and prevent a potential spark ignition of gas fumes, that might be generated during the tank cleaning operation. 
     In  FIG. 3 , a perspective view of another embodiment of the subject tank cleaning system  10  is illustrated. In this drawing, a floor finishing head  74  is shown mounted on a pair of wheels  76 . As mentioned above, the finishing head  74  is used to remove the last 2 or 3 inches of sediment  16  on a tank floor  78  and prior to completing the tank cleaning operation. The wheels  76  help move the finishing head  74  back and forth on the cleaned tank floor  78  as the remaining sediment  16  is removed. 
     In this example, the air line  26  is connected to an air manifold  80  mounted on a top of a finishing head housing  82 . A pair of ends  84  of the air manifold  80  are attached to four air nozzles  54 , with the ends of the nozzles received through the housing  82  and angled rearwardly, typically at an angle of 45 degrees from the vertical, for directing the loosened sediment  16  toward the suction head  67  of a semi-flexible, vacuum hose  64  attached to the rear of the housing. 
     Also, the steam line  18  is connected to a steam manifold  86  mounted on top of the finishing head housing  82 . A pair of ends  84  of the steam manifold  86  are attached to four steam nozzles  56 , with the ends of the nozzles received through the housing  82  and angled rearwardly, also at a 45 degree angle from the vertical, for directing the loosened sediment  16  toward the suction head  67  of the semi-flexible, vacuum hose  64 . In this manner, the air and steam in combination, using a plurality of air and steam nozzles, can be used to remove the last few inches of the sediment  16  from the tank floor  78  and directing the sediment into the vacuum hose  64  attached to the rail vacuum pipe  24 , using another camlock coupling  66 . Also, an added feature of the floor finishing head is the steam line  28  can be turned off. At this time, the air line  26  can be used alone with the vacuum tube  63  for cleaning up any remaining steam turned to water or sediment left on the tank floor  78 . 
     In  FIG. 4 , an enlarged perspective view of a swivel wheel  36  and door opening bracket  38  are shown. In this drawing, stud holes  88 , in the opposite flange ends  40  and  42  of the mounting bracket  38 , are shown ready to be received around the outwardly extending, threaded studs  19 , equally spaced along the length of the sides of the door opening  12 . The mounting bracket  38  is the attached to the thread studs  19  using bolts  88 . The bracket  38  can have different configurations and attached to sides of the door opening, typically 1 to 2 feet above the tank floor  78  for ease in moving either the air/steam mixing box  30  or the floor finishing head  74  attached to the air and steam lines  26  and  28  and the vacuum pipe  24  inside the tank  14 . 
     While not shown in the drawings, the inside walls of the storage tank  14  can be cleaned using a bent 1 inch steam pipe with an insulated handle. The pipe can be held on top of a chain, with opposite ends of the chain attached to the sides of the door opening  12 . In this manner, the weight of the steam pipe rest on the chain and the operator can move the pipe back and forth on the chain for steam cleaning the tank walls. 
     While the invention has been particularly shown, described and illustrated in detail with reference to the preferred embodiments and modifications thereof, it should be understood by those skilled in the art that equivalent changes in form and detail may be made therein without departing from the true spirit and scope of the invention as claimed except as precluded by the prior art.