Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
  • B08B9/08—Cleaning containers, e.g. tanks
  • B08B9/093—Cleaning containers, e.g. tanks by the force of jets or sprays
  • B08B9/0936—Cleaning containers, e.g. tanks by the force of jets or sprays using rotating jets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
  • B08B9/08—Cleaning containers, e.g. tanks
  • B08B9/093—Cleaning containers, e.g. tanks by the force of jets or sprays
  • B08B9/0933—Removing sludge or the like from tank bottoms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B3/00—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements
  • B05B3/02—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements
  • B05B3/04—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements driven by the liquid or other fluent material discharged, e.g. the liquid actuating a motor before passing to the outlet
  • B05B3/0409—Spraying or sprinkling apparatus with moving outlet elements or moving deflecting elements with rotating elements driven by the liquid or other fluent material discharged, e.g. the liquid actuating a motor before passing to the outlet with moving, e.g. rotating, outlet elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/04—Cleaning involving contact with liquid
  • B08B3/10—Cleaning involving contact with liquid with additional treatment of the liquid or of the object being cleaned, e.g. by heat, by electricity or by vibration
  • B08B3/14—Removing waste, e.g. labels, from cleaning liquid; Regenerating cleaning liquids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
  • B08B9/08—Cleaning containers, e.g. tanks
  • B08B9/0804—Cleaning containers having tubular shape, e.g. casks, barrels, drums
  • B08B9/0813—Cleaning containers having tubular shape, e.g. casks, barrels, drums by the force of jets or sprays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
  • B08B9/08—Cleaning containers, e.g. tanks
  • B08B9/093—Cleaning containers, e.g. tanks by the force of jets or sprays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B57/00—Tank or cargo hold cleaning specially adapted for vessels
  • B63B57/02—Tank or cargo hold cleaning specially adapted for vessels by washing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
  • B05B15/60—Arrangements for mounting, supporting or holding spraying apparatus
  • B05B15/62—Arrangements for supporting spraying apparatus, e.g. suction cups
  • B05B15/625—Arrangements for supporting spraying apparatus, e.g. suction cups designed to be placed on the ground
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B15/00—Details of spraying plant or spraying apparatus not otherwise provided for; Accessories
  • B05B15/60—Arrangements for mounting, supporting or holding spraying apparatus
  • B05B15/68—Arrangements for adjusting the position of spray heads
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B2230/00—Other cleaning aspects applicable to all B08B range
  • B08B2230/01—Cleaning with steam

Definitions

• the invention concerns a method, a system as well as an arrangement for cleaning the interior of a storage tank, and particularly for removing the residue of a medium that was previously stored in the storage tank.
• the inside wall of the storage tank is washed by help of a washing liquid which is sprayed at high pressure onto the wall from at least one nozzle which is rotatably arranged in the storage tank.
• the invention can be applied in connection with cleaning and washing the interior of storage tanks adapted for storing liquid, such as liquid petroleum products, bio- oils and other industrially used chemicals in ports or industrial plants. Many of these chemicals are viscous in an unheated state and leave residue on the wall and on the bottom of the storage tank. Most of them are insoluble in water and are therefore difficult to dissolve and remove from the surfaces onto which they adhere.
• the invention is particularly useful for cleaning of a storage tank that was previously used for storing of a hydrophobic substance which adheres to the tank wall, and which leaves a bottom layer sediment on the tank floor that is difficult to dissolve.
• the invention is however not limited to this use, but is obviously useful also for cleaning of tanks for storing other kinds of chemicals, also including chemicals which are soluble in water.
• the storage tanks referred to are mostly of large dimensions, having a diameter dimension in the order of 10-25 m and a height dimension of similar size. For security reasons it is necessary to clean the tanks for inspection of weld seams each 6 th or 12 th year, depending on the structure of the storage tank. A thorough cleaning is usually required also in connection with a change to another product for storing in the tank. Inside cleaning of the storage tank is conventionally performed by personnel that enter into the tank for manual shoveling out of viscous and sticky bottom layer sediments. If also the wall is to be cleaned, a scaffold is thereafter raised against the wall from which the personnel cleans the wall manually with help from solvents and tools, such as brushes and spraying nozzles.
• the object of the present invention is thus to provide a method and a system for cleaning the interior of storage tanks, focused on improved health for personnel, on less environmental stress, and on enhanced security.
• the object is met in a method for cleaning the interior of storage tanks, according to which procedure the inside wall of the storage tank is washed with washing liquid that is sprayed onto the wall at high pressure from at least one nozzle which is arranged rotatable in the storage tank, wherein water steam is introduced in the storage tank for heating the tank wall and the residue of a stored medium which adheres to the tank wall, such that the water steam can condensate on the tank wall to run off from the wall for accumulation on the tank floor together with washing liquid and heated residue of the stored medium, where after the heated residue, washing liquid and condensate water is fed out to a mobile buffering tank.
• the present invention provides a cleaning method which is based on a closed system wherein washing liquid is collected in a mobile buffer tank together with the residue of the stored medium which has been removed from the wall of the storage tank after heating to run off from the wall together with the condensate water. It is preferred that the washing liquid is recycled to the storage tank from the buffer tank in the washing procedure, and more precisely returned via a heat exchanger that is driven by a mobile steam generator.
• One embodiment of the invention thus teaches recycling of the washing liquid between the storage tank and the mobile buffer tank in a closed system from which used washing liquid, condensate water and residue of the washed-out medium can be transported for after-treatment in the form of destruction, deposition, processing and re-use, e.g.
• the bottom layer sediment in larger storage tanks can amount to quantities in the order of about 100 to 150 tons, e.g., which in use of the present invention can be returned to production to a large extent, and more precisely, as it has shown by experience, to an extent in the order of 50-80 %, it will be appreciated that the invention provides not only reduced stress on the environment but also improved production profits.
• Residue of a hydrophobic medium previously stored in the tank can be fed out in a separate step of the procedure, separated from condensate water and washing liquid, by being sucked in from the surface of the accumulated amounts of washing liquid and condensate water on the storage tank floor.
• the steam required in the process is produced by means of a mobile steam generator.
• a steam generator for this purpose preferably has a steam producing capacity in the order of a few tons, such as about 3-5 tons of water steam per hour for feeding into the storage tank.
• a high capacity is required since one step of the procedure teaches that water steam is to be fed into the storage tank to an amount sufficient to fill out a substantial portion of the enclosed volume of the tank, and at least an upper third of the tank volume.
• the purpose of using water steam is thus not to successively treat local areas of the tank wall, but rather as previously mentioned, to fill out a substantial portion of the tank volume in order to heat the tank wall and the residues of previously stored medium which adhere to the tank wall, such that this residue can be more easily removed with the aid of a washing liquid that is sprayed onto the wall from the rotating nozzle.
• the washing liquid which is fed to the rotating nozzle by means of pumps, on its way passes a heat exchanger wherein the washing liquid is heated by absorbing heat from the water steam on its way between the steam generator and the storage tank.
• the water steam is fed into the storage tank by means of a pump able to generate a pressure in the order of 10- 12 bars, having a pump capacity in the order of 30-40 m 3 per hour.
• a pump able to generate a pressure in the order of 10- 12 bars, having a pump capacity in the order of 30-40 m 3 per hour.
• the buffer tank which is mounted on a vehicle, may suitably have a volume in the order of 10- 15 m 3 .
• a level control is arranged with communication to the storage tank to permit return of excessive liquid if necessary.
• the mixed substance which is fed into the buffer tank will separate into a fatty or hydrophobic surface layer, consisting of residue from the storage tank, floating on top of a watery phase consisting of washing liquid and condensate water. Incrustations, such as flakes of rust and hard rest products, will sink to the floor in the buffer tank.
• the watery phase will be pumped via a filter from the buffer tank to the rotating washing robot. In this connection a pump having a capacity of 30-40 m 3 per hour is suitably used, at a pressure in the order of 10- 15 bars.
• the pump which supplies the washing robot is preferably a displacement pump, such as a progressive cavity pump, e.g.
• the cleaning system further comprises pipes and conduits for supplying the washing robot and the steam sprayer via the manhole to the storage tank, as well as lances or beams insertable through the manhole and by which the washing robot and steam sprayer can be rigged at suitable height above the floor in the storage tank.
• the mechanical parts of the system can be chosen and adapted to the current needs and to the subject storage tank.
• the present invention further provides an arrangement which is particularly adapted for implementation of the tank washing method.
• the arrangement comprises an elongate stand which is insertable into the storage rank via the manhole, the stand carrying a first channel for liquid running horizontally in the length direction of the stand and connectable to an external liquid supply, as well as a second channel for liquid which is pivotally connected to the first channel for liquid and which in relation thereto can be raised/ lowered, the second channel in a free end carrying a rotary sprayer head.
• the stand can be arranged to rest on legs which are arranged in pairs, at least one pair of legs being equipped with skid rails.
• the first channel for liquid is a conduit which is inserted and anchored in a U-beam.
• the second channel for liquid is a hollow boom which is, via a swivel joint, pivotally connected to an end of the conduit that projects from the U-beam in axial direction.
• a raising and lowering mechanism may be arranged to operate between the hollow boom and the U-beam.
• This mechanism may be equipped with a hydraulic or a pneumatic piston/ cylinder unit, or a gear rack, e.g., that operates a linked mechanism.
• a yoke element is preferably arranged on the hollow boom, the yoke arranged axially below the sprayer head for connection to a wire used in raising and lowering of the boom by means of a winch.
• a winch to operate the boom can be mounted on the roof of the storage tank, by insertion of a wire via a hole that is opened temporarily through the roof of the storage tank.
• Fig. 1 shows a system for implementation of the method according to the invention
• Fig. 2 shows an arrangement for implementation of the method, viewed from the side, and
• Fig. 3 shows the arrangement of Fig. 2 as viewed from an end of the arrangement.
• a mobile system 1 for cleaning the interior of storage tanks comprises a number of vehicle mounted units, such as a buffer tank 2, a filter 3, a steam operated heat exchanger 4, a steam generator 5, as well as pumps 6 and 7.
• the steam generator 5 is supplied water from an external water supply, which needs no further specification, in Fig. 1 indicated only by means of the supply conduit 8.
• Steam which is generated in the steam generator 5 is fed via the heat exchanger 4 and the steam feeding conduit 9 to a steam spreader 11 installed in a storage tank 10. Steam is generated to an amount sufficient to fill out a substantial portion of the volume of the storage tank. In Fig. 1 this is illustrated by a dotted line defining a plume 12 of steam which fills out an upper third of the internal volume of the storage tank, at least.
• the steam generator 5 has a capacity for steam generation in the order of 4 tons of steam per hour.
• the washing robot comprises rotatable nozzles 15 which are driven in rotation through the pressure and flow rate /velocity of the supplied water.
• the washing robot is thus effective for directing water jets 16 towards the wall of the storage tank, as indicated by broken lines in Fig. 1.
• the washing robot is of type that includes two or more nozzles arranged to rotate in a vertical plane while a sprayer head, carrying the nozzles, is simultaneously rotating in a horizontal plane. This way, the washing robot will successively treat the complete inside surface of the storage tank from the top to the bottom.
• a layer of hydrophobic rest products may be formed, which is heated from the steam and loosened from the tank wall to flow off the wall together with condensate and washing water. If the layer of rest products is built up to a thickness that permits sucking in, the rest products can be returned to production in a way illustrated in Fig. 1 by means of the pump 17 and conduit 18. Alternatively, the rest products can be transferred for destruction or deposition.
• Suitable pumps, steam driven heat exchangers, steam generators and filters are available on the market.
• the choice for the pump 6 preferably include displacement pumps having a pump capacity of 30-40 m 3 per hour.
• the choice for the pump 7 is a pump which provides a corresponding capacity and generates a pressure in the order of about 10- 16 bars.
• a type of progressive cavity pump can be a suitable choice.
• steam generators suitable for the purpose are diesel driven units such as tube boilers or fire tube boilers, e.g. Produced steam can be distributed to several discharge points in the system via a steam table.
• suitable heat exchangers is the plate heat exchanger in which a number of plates are assembled to separate steam and washing liquid and to transfer heat from the steam to the washing liquid.
• a suitable filter can be a filter of the basket filter type with exchangeable baskets. The filter should be able to handle pressure in the order of 20-25 bars.
• the system can be arranged for recycling of washing liquid that by-pass the buffer tank 2.
• a valve 1 can be arranged to direct the washing liquid from the storage tank directiy to the heat exchanger 4 via a conduit 20.
• Fig. 1 it can further be seen that in operation all supply lines reach into the storage tank 10 via a manhole arranged in the tank wall.
• the washing robot and the steam sprayer are likewise insertable through the manhole for installation in the storage tank 10.
• the arrangement 30 comprises a supporting stand 31 which can be introduced via a manhole.
• the stand 31 rests on a forward end pair of legs and a rear end pair of legs 32 and 33 respectively, of which the forward end pair of legs is equipped with skid rails 34 by means of which the stand can be pushed into the storage tank while sliding on the tank floor.
• the stand 31 has a length that corresponds substantially to the radius of the tank such that the forward end 35 reaches to the center of the tank when the arrangement 30 is installed in the storage tank.
• the stand 31 has a length in the order of 10- 15 m.
• the stand 31 comprises a U-beam, the open side of which is facing upwards, although other alternatives would be conceivable.
• the arrangement 30 further comprises a first channel 36 for liquid in the form of conduit 36 carried in the stand.
• the conduit 36 In an outer and rear end the conduit 36 is arranged with a coupling 37 for connection to an external liquid supply.
• the liquid supply referred to is the buffer tank 2.
• the conduit In the inner and forward end of the conduit 36, the conduit is pivotally connected to a second channel for liquid 38 in the form of a hollow boom 38.
• the boom 38 can be raised from a position substantially in parallel with the conduit 36 to the upraised position shown in Figs. 2 and 3.
• the boom can connect to one end of the conduit 36 which projects from the stand 31, and coupled thereto via a flange coupling 39, a tube bend 40, a pivot joint 41 , another tube bend 42 and a flange coupling 43.
• the free end of the boom 36 carries a sprayer head with nozzles 15 of a type mentioned above with respect to the system.
• a mechanism arranged for operation between the stand 31 and the boom can be installed for raising and lowering of the boom.
• This mechanism can include a hydraulic, pneumatic or gear rack driven link mechanism, e.g.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Ocean & Marine Engineering (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Cleaning In General (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=51867569

Family Applications (1)

Country Status (3)

Cited By (3)

Citations (4)

Family Cites Families (2)

• 2013
  • 2013-05-06 SE SE1350547A patent/SE537220C2/sv not_active IP Right Cessation
• 2014
  • 2014-04-30 WO PCT/SE2014/050536 patent/WO2014182223A1/en active Application Filing
  • 2014-04-30 EP EP14794470.6A patent/EP2994250A4/en not_active Withdrawn

Patent Citations (4)

Non-Patent Citations (1)

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