GB2376471A

GB2376471A - Method and apparatus for dissolving crude oil sludge

Info

Publication number: GB2376471A
Application number: GB0203465A
Authority: GB
Inventors: William Benjamin Howe
Original assignee: TSORS Ltd
Current assignee: TSORS Ltd
Priority date: 2001-02-22
Filing date: 2002-02-14
Publication date: 2002-12-18
Anticipated expiration: 2022-02-14
Also published as: GB2376471B; GB0203465D0

Abstract

Apparatus comprises floats 1, or tractor (21, fig. 2), pump 2 connected by pipe 3 to rotor arms 5, camera 22 and lights 6. Spray nozzles 13 are attached to rotor arms 5. In use, the apparatus is placed in a tank and solvent is pumped into the tank. Pump 2 sucks dissolved sludge through inlet port 15. Sludge is forced along pipe 3, along spray arms 5 and through nozzles 13, which results in more sludge being dissolved. When the sludge reaches the desired viscosity it may be pumped from the tank. Lights 6 and CCTV 22 enable operators to control the operation from a remote location by controller 14.

Description

A METHOD OF, AND APPARATUS FOR, DISSOLVING CRUDE OIL SLUDGE Technical field and background art This Invention relates to a method of, and apparatus for, dissolving crude oil sludge held in containments such as bulk storage tanks or tankers or holes in the ground.

As crude oil becomes more viscous it can coalesce into what is generally referred to as sludge. The sludge represents value to its owner if it can be dissolved and incorporated into the owner's income-earning activities. Where sludge is contained in a receptacle such as a storage or settlement tank, the recovery of such sludge can be a hazardous operation particularly if operatives are required to wear full breathing and safety equipment to be able to enter the tank in order to spray dissolving-fluid at the sludge. To overcome these potential hazards and to be able to effect the dissolution of the crude safely the apparatus to be specified can be deployed in such environments with its activity being monitored and controlled from outside the hazardous area. As manway entry/exit points of storage tanks are of limited dimension the apparatus is capable of being packed in a foldaway form to facilitate egress through such entry/exit points and unfolded into its operating mode after entry into the area to be worked on.

Conventionally sludge is removed from tanks by a variety of methods which range from digging it out to pumping water or chemicals under pressure to create an emulsion which is then pumped out and disposed of. There are significant disadvantages to these methods which the present invention overcomes. The disadvantages are health and safety, environmental and economic. Health and safety, because of the need for operatives to work in tanks. Environmental because if the crude oil sludge cannot be recovered for use then it has to be disposed of in an environmentally friendly way.

Economic because the sludge represents value if the value of the sludge can be released and also whilst the sludge is in the tank it takes up valuable space.

Further, in order to clean the inside of tanks for, say, inspection, repair or change of use cleaning devices, referred to as spinners, are used which, because of their method of construction, do not allow for them to be operated at other than the speed designed by the factory setting. That"one model fits all" approach has limitations as it means that

the cleaning operation inputs-such as solvent or cleaning fluid and cleaning medium- and outputs-such as effluent-all have a cost which could be more easily controlled if the speed of operation could be accurately tailored to the job. To overcome this disadvantage and to be able to obtain the desired economies in operation apparatus to ho specified can he detoed in such environments It is an object of the present invention to provide a method of, and apparatus for, the dissolution of crude oil sludge and recovery of the oil and for, cleaning open-topped or enclosed containers such as bulk storage tanks or tankers for inspection, repair or change of use which alleviates the disadvantages of the above described proposals.

Statement of invention & advantages According to the present invention there is provided a method of dissolving crude oil sludge by pumping solvent at pressure into the mass of the sludge ; pumping the resulting mixture of solvent and dissolved sludge into the remaining mass of sludge until all the sludge is dissolved to a pumpable viscosity so that the oil contained in the sludge may be removed from the containment and recovered; monitonng and controlling the operation remotely and safely ; pumping the dissolved sludge from the storage/settlement tank to incorporate the oil into the owner's oil processing/trading activities, cleaning the inside of the storage/settlement tank for inspection, repair or change of use. Further according to the present invention there is provided apparatus for dissolving crude oil sludge which comprises means to support and transport the apparatus through the dissolved sludge mixture ; means for pumping the solvent and dissolved sludge mixture into the sludge ; means for monitoring and controlling the progress of the apparatus when used in these activities; means for removing the dissolved sludge from the storage/settlement tank or other area in which it is held ; means for cleaning the storage/settlement tank for inspection, repair or change of use.

The preferred solvent is a synthesis of extract from orange oils and mineral oils. When this solvent is pumped into sludge the sludge appears to dissolve immediately. The amount of solvent required depends on three factors, the pour-point temperature of the sludge, the % of wax contained in the sludge, and the maximum acceptable viscosity of dissolved sludge.

An integral part of the apparatus is a multi-nozzled rotor or spinner-which can be described as having three elements which controls its speed; a braking mechanism, the size of orifice in the nozzles through which the solvent or cleaning fluid flows, which provides power, and the angle at which the nozzles are set to create rotational motion. Included in the present invention there is provided a method by which the angle at which the nozzles are set can be varied in order to obtain optimum working of a particular rotor or spinner in a particular tank. Further according to the present invention there is provided a means of stopping the flow of cleaning fluid through one or more nozzles in order to allow the same basic rotor or spinner design to be usable in opentopped containers as well as enclosed containers and to avoid drenching the apparatus under the path of the jets of solvent or cleaning fluid which would otherwise flow through the nozzles as the rotor or spinner rotates.

The whole apparatus is summarized as a multi-nozzled rotor or spinner which is releasably secured to a pump and driven by a flow of solvent or solvent and dissolving sludge mixture or cleaning fluid pumped under pressure from a pump either releasably secured to a raft or tractor or sump-cone lowered onto the floor of the containment or as part of clean-in-place (CIP) setting to the tank to be cleaned or external to the tankdepending on circumstances applying at site of operation-so that the force of the solvent or solvent and dissolving sludge mixture or cleaning fluid delivered through outlet nozzles located at specific points and angles on, along or around the circumferance of a rotor block or outlet pipes attached to the rotor block causes the rotor block to rotate in a controlled manner; the inclusion of a releasably secured collar or shoulder within the rotor block will enable the directional flow through certain nozzles to be restricted or stopped for operational needs, such as being able to clean opentopped containers or to avoid drenching the apparatus under the path of the jets of solvent or cleaning fluid which would otherwise flow through the nozzles as the rotor or spinner rotates, is used to dissolve the un-dissolved sludge it comes into contact with and also causes the rotor or spinner to rotate in a controlled manner to increase the area of sludge to be dissolved and on a modified rotor block the rotor or spinner can be transformed into a paddle-wheel by the attachment of transverse flats to the rim of the rotor block which when properly located on the raft and activated by solenoid switches

is used to assist propulsion of the raft through the dissolved sludge in addition to sludge pumped directly to create such propulsion ; lights and CCTV camera releasably secured to a raft or tractor or sump-cone to illuminate and survey the area of sludge being dissolved and to be able to observe obstructions or other impediments to progress and sensors to be able to obtain trigonometric readings to be able to pin-point location of raft in tank; a raft consisting of several releasably connected floats to provide buoyancy to support the weight of the equipment; a tractor with wheels or caterpillar tracks powered by an electric motor; a sump-cone to create a pool of pumpable dissolved sludge ; a control box with appropriate software and means of two-way electrical or electronic communication with the different pieces of equipment to control the operation of the apparatus and ancillary equipment and devices such as generators, compressors, pumps, CCTV recording and play-back equipment as may be necessary to support the use of the apparatus when in operating conditions.

Drawings An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which : Figure 1 shows the apparatus in operating mode when attached to a raft.

Figure 2 shows the apparatus in operating mode when attached to a tractor.

Figure 3 shows the apparatus in operating mode when attached to a sump-cone.

Figure 4 shows the rotor block.

Figure 5 shows details of the spinner assembly.

Figure 6 shows modification to threaded rotor/drive connection to create a"shoulder".

Figure 7 shows modification to threaded rotor connection to create a"shoulder".

Detailed description of drawings Referring to the drawing the apparatus comprises buoyancy floats 1 or tractor 21 a pump 2 connected by flow-pipe 3 to a rotor 4 arms 5 CCTV camera 22 and lights 6; all releasably connected by, for example, flexible joints, circlips, unions or similar means (not shown). At convenient points on the raft 1 tractor 21 and sump-cone 20 cleats or similar devices (not shown) are fitted to facilitate securing or manoeuvring the apparatus by ropes or similar means (not shown). Figure 5 shows a spray nozzle 13 which comprises an open-ended cylindrical nozzle cap 31 into the wall of which has been

tapped a thread to allow a nozzle 13 with appropriate orifice size to be screwed to accommodate the desired flow rate and to provide the desired speed of rotation. The spray nozzle 13 is releasably attached to the rotor block 4 by a screw or bolt 35 or similar means (not shown) securing the nozzle cap 31. This rotor block 4 is connected to an outlet assembly which comprises the following components plus bearings 11B, seals 12B, washer 38 and locking nut 37; a threaded outlet-nut stop 32 and a threaded rotor connection 36, which joins the inlet assembly indirectly via an angle connector 30 to the rotor block 4.

The angle connector comprises an angle case 30.

The inlet assembly comprises a threaded inlet nut 7, a threaded inlet nut stop 8-which connects to the angle connector-and threaded rotor/drive connection 9 plus bearings 11A, seals 12A, washer 38 and locking nut 37. The rotor/drive connection 9 includes a bevel or other appropriate gear 33 to mesh with a bevel or other appropriate gear 34 attached to the rotor connection 36 to allow the rotary action of the rotor 4 to be transmitted to a different plane around the inlet nut 7.

Figure 6 shows setting where rotor 4 is connected directly to inlet nut stop 8 and the rotor/drive connection 9 - excluding bevel or other gear-is extended and profiled to create a shoulder 40 to allow one or more nozzles 13 to be closed off sequentially as rotor 4 rotates.

Figure 7 shows setting where rotor 4 is connected directly to rotor connection 36 and the outlet-nut stop 32 is profiled to allow a shoulder 40 to be releasably attached to allow one or more nozzles 13 to be closed off sequentially as rotor 4 rotates.

The rotor block 4 is connected to the flow-pipe 3 by an inlet assembly 10 which comprises three main components plus bearings 11 and seals 12; a threaded inlet nut 7, a threaded inlet-nut stop 8 and a threaded rotor connection 9 which joins the inlet assembly 10 to the rotor block 4. When spray arms 5 are used they removably connected to the rotor block 4. At intervals along the spray arms 5 are inserted spray nozzles 13 to provide a spray pattern which provides the greatest contact with the sludge to be dissolved and to provide the desired speed of rotation. The controls 14 to stop/start and monitor operations are maintained outside the tank but releasably

connected to the apparatus and other equipment being used, the control box and associated software is typical of CIP control equipment used in the dairy industry.

The Method The method for using the apparatus will now be described envisaging A. circumstances

when buoyancy from a raft is desirabie, B. circumstances when using a tractor or llr-li UWYIAIIY similar means of propulsion is desirable, C. circumstances when a static location is desirable, D. for cleaning the walls and bottom of an open-topped tank or use as a paddle-wheel, E. for cleaning all surfaces of an enclosed tank, F. for cleaning either the bottoms of tanks or Inside surface of a pipeline.

In each case sufficient solvent will need to be pumped into the tank to create a pool of solvent and sludge to be able to prime and operate the pump used with the apparatus.

Thus, with circumstance A after a pool of dissolved sludge is created the raft and attached apparatus as Figure 1 is placed in that pool ; the pump 2 is then in a position to suck the dissolved sludge in through inlet port 15 and force it along pipe 3 to the rotor block 4 along the spray arms 5 and out through the nozzles 13. The combined force and flow of solvent and dissolved sludge through the nozzles 13 causes more crude to dissolve thus increasing the size of the pool of dissolved sludge. As the pool size increases the raft will need to be moved in order to maintain contact with undissolved sludge. This movement is obtained from the thrust derived by diverting via valve 18 dissolved sludge from flow pipe 3 along pipe 16 to an outlet port 17, at which port may be located a rotor or spinner modified as a paddle-wheel to provide propulsion when diverted sludge cause such paddle-wheel to rotate. The viscosity of the pool of dissolved sludge can be maintained by adding more solvent using an externally located pump (not shown) and by using an agitating mechanism such as a slow-speed propeller (not shown) located in the pool to cause the dissolved sludge to circulate. When the pool of solvent has reached the desired viscosity required by the owner-as measured by in-line Viscometer (not shown)-it can be removed either by pumping it directly from the tank, or indirectly by pumping sufficient water into the tank to allow the oil to be floated out of the tank through the outlet ports in the wall of the tank into appropriate recovery vessels. In case the apparatus gets into difficulty and needs to be recovered,

the raft 1 has ropes attached to cleats (not shown) and connected to a winch (not shown) located outside the tank in order to winch the raft and apparatus to safety.

Whilst the apparatus is in operation the sludge being dissolved can be illuminated by lights 6 in order that human operators located outside the tank can observe the operations via CCTV camera 22 connected to a monitor screen (not shown) and through the control box 14 control operations.

With circumstance B after a pool of dissolved sludge is created the tractor 21 and attached apparatus as Figure 2 is placed in that pool ; the pump 2 is then in a position to suck the dissolved sludge in through inlet port 15 and force it along pipe 3 to the rotor block 4 along the spray arms 5 and out through the nozzles 13. The combined force and flow of solvent and dissolved sludge through the nozzles 13 causes more crude to dissolve thus increasing the size of the pool of dissolved sludge. As the pool size increases the apparatus will need to be moved in order to maintain contact with undissolved sludge. This movement is obtained by using an electric-motored tractor 21 which has been approved for use in this environment. The viscosity of the pool of dissolved sludge can be maintained by adding more solvent using an externally located pump (not shown) and by using an agitating mechanism such as a slow-speed propeller (not shown) located in the pool to cause the dissolved sludge to circulate. When the pool of solvent has reached the desired viscosity required by the owner-as measured by in-line Viscometer (not shown)-it can be removed either by pumping it directly from the tank, or indirectly by pumping sufficient water into the tank to allow the oil to be floated out of the tank through the outlet ports in the wall of the tank into appropriate recovery vessels. In case the apparatus gets into difficulty and needs to be recovered, the tractor 21 has ropes attached to cleats (not shown) and connected to a winch (not shown) located outside the tank in order to winch the tractor and apparatus to safety. Whilst the apparatus is in operation the sludge being dissolved can be illuminated by lights 6 in order that human operators located outside the tank can observe the operations via CCTV camera 22 connected to a monitor screen (not shown) and through the control box 14 control operations.

With circumstance C a pool of sludge needs to be created in a different fashion where the sludge is of such a depth that entrance into the tank through a man-way in the side

wall is not desirable or not possible and where entrance is only possible through the roof or floating membrane covering the sludge. In this case it may be first necessary to lower through a man-way a sump-cone 20 as Figure 3 which, because of its weight, will sink into the sludge and have the effect of allowing a pool of solvent and solvent sludge mixture to accumulate in the sump-cone 20 in order that the pump 2 can operate. The sump-cone 20 is supported by legs 19 and is in the shape of an inverted truncated cone with means for lowering/lifting it (not shown) and releasably securing (not shown) the pump 2 inside the space contained by the skin of the cone. After a pool of solvent or dissolved sludge is created in the sump-cone 20 the pump 2 is then in a position to suck the dissolved sludge in through inlet port 15 and force it along pipe 3 to the rotor block 4 along the spray arms 5 and out through the nozzles 13. The combined force and flow of solvent and dissolved sludge through the nozzles 13 causes more crude to dissolve thus increasing the size of the pool of dissolved sludge. The viscosity of the pool of dissolved sludge can be maintained by adding more solvent using an externally located pump (not shown) and by using an agitating mechanism such as a slow-speed propeller (not shown) located in the pool to cause the dissolved sludge to circulate. As the pool depth increases some of the dissolved sludge will need to be pumped out of the tank in order to allow the remaining sludge to settle into the space created. This process will then continue until such time that it is possible to deploy the apparatus attached to a raft 1 as described in Circumstance A.. When the pool of solvent has reached the desired viscosity required by the owner-as measured by in-line Viscometer (not shown)-it can be removed either by pumping it directly from the tank, or indirectly-when the side-wall man-ways are accessible-by pumping sufficient water into the tank to allow the oil to be floated out of the tank through such outlet ports in the wall of the tank into appropriate recovery vessels. Whilst the apparatus is in operation the sludge being dissolved can be illuminated by lights 6 in order that human operators located outside the tank can observe the operations via CCTV camera 22 connected to a monitor screen (not shown) and through the control box 14 control operations.

The apparatus comprises a raft 1 which is conveniently assembled from connectable plastic or other strong light-weight materials to provide sufficient buoyancy for the

weight of the raft and its equipment and capable of being easily assembled after entry into and disassembled before egress from storage/settlement tank through a man-way.

The tractor 21 is driven by an electric motor similar to tractors used in gas pipelines and as such warranted suitable for use in an explosive environment.

The pumping mechanism comprises pump 2 and rotor block 4 with spray arms 5 or nozzles 13 through which the solvent and sludge mixture is delivered and includes connecting pipework 3 and 16 and valve 18; the pump 2 is of a type suitable for hazardous environment; the rotor block 4 and the spray arms 5 have nozzles 13 to create flat jets so that as the rotor block 4 rotates the kinetic energy derived from the force of the jets of solvent and solvent-sludge mixture delivered through the nozzles 13 accelerates the dissolution of the sludge ; the pump 2 operates at a convenient pressure up to 5 Bar and the nozzles 13 will accommodate the flow rate delivered by the pump 2; the rotation of the rotor block 4 is achieved by the flow of fluid through the nozzles 13 and the speed of rotation is predicated by the location of the nozzles 13.

The sump-cone 20 is shaped as an inverted truncated cone in order that it will sink into the sludge more easily and the legs 19 provide stability.

The control and monitoring of the operations is achieved by mounting a CCTV camera 22 and lights 6 on the raft 1 or tractor 21 or sump-cone 20 and a control module 14 to stop or start the different functions involved with pumping, moving, scanning, recording, locating, measuring is connected electronically to the apparatus but located outside the tank.

With circumstance D to clean the walls and bottom of an open-topped tank or use as a paddle-wheel when transverse flats (not shown) have been added to the rim of the rotor block 4 the flow of fluid through some of the spray nozzles 13 will need to be stopped as the rotor block 4 rotates. This is achieved by ensuring that a shoulder 40 of appropriate dimension is releasably attached to or formed as part of the outlet-nut stop 32 and that the complete assembly is appropriately positioned in the tank to ensure the spray jet leaving spray nozzle 13 reaches the desired height up the wall of the tank. Thus, with a correctly positioned shoulder 40, fluid to nozzles 13 will be sequentially blocked as the outlet to nozzle cap 31 passes behind shoulder 40. As rotor block 4 rotates the flow through spray nozzle 13 is reinstated as the outlet to spray nozzle 13 clears shoulder

40. With more than one spray nozzle 13 rotation of rotor block 4 can be maintained providing the force from flow of fluid through unmasked spray nozzles 13 is sufficient to overcome the frictional resistance of the complete unit. The speed of rotation is determined by the direction of the jet of cleaning fluid leaving spray nozzle 13. There is no rotation when nozzle 13, screw 35 and centre point of rotor 4 are in a straight line (0 degrees). There will be maximum rotation if the nozzle cap 31 is turned 90 degrees.

An operator can set his angle of deflection-rotating the nozzle cap 31-between 0 degrees and 90 degrees to suit his operating requirement above the frictional resistance of the complete unit.

With circumstance E, to clean all surfaces of an enclosed tank cleaning fluid will need to flow through all of the spray nozzles 13 as the rotor block 4 rotates when rotor block 4 is attached to rotor connector 36. The speed of rotation is determined by the direction of the jet of cleaning fluid leaving spray nozzle 13. There is no rotation when nozzle 13, screw 35 and centre point of rotor 4 are in a straight line (0 degrees). There will be maximum rotation if the nozzle cap 31 is turned 90 degrees. An operator can set his angle of deflection-rotating the nozzle cap 31-between 0 degrees and 90 degrees to suit his operating requirement above the frictional resistance of the complete unit.

With circumstance F, to clean the bottom of a tank or inside surface of a pipeline cleaning fluid will need to flow through all of the spray nozzles 13 as the rotor block 4 rotates when rotor block 4 is attached directly to inlet nut stop 8. The speed of rotation is determined by the direction of the jet of cleaning fluid leaving spray nozzle 13. There is no rotation when nozzle 13, screw 35 and centre point of rotor 4 are in a straight line (0 degrees). There will be maximum rotation if the nozzle cap 31 is turned 90 degrees.

Claims

CLAIMS 1. A method of dissolving crude oil sludge by pumping solvent under pressure into the mass of the sludge ; pumping the resulting mixture of solvent and dissolved sludge into the remaining mass of sludge until all the sludge is dissolved to a pumpable viscosity so that the oil contained in the sludge may be removed from the containment and recovered; monitoring and controlling the operation remotely and safely ; pumping the dissolved sludge from the storage/settlement tank to incorporate the oil into the owner's oil processing/trading activities.
2. A method as claimed in Claim 1 for dissolving crude oil sludge on a continuous basis.
3. A method as claimed in either claim 1 or claim 2 which comprises pumping the solvent or the mixture of solvent and dissolved sludge through restricting nozzles in order to take advantage of the resulting kinetic energy to accelerate the speed at which the mass of crude dissolves
4. A method as claimed in any one of the preceding claims for controlling the operations of the apparatus outside of the containment in which the apparatus is operating.
5. A method as claimed in any of the preceding claims for controlling the speed of operation by adjusting the locations and sizes of the outlet nozzles on, around or attached to a rotor block.

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6. A method as claimed in any of the preceding claims for restricting sequentially the flow through specific nozzles as the rotor block rotates to provide the most effective spray pattern.
7 A method as claimed in any one of the preceding claims for creating a pool of pumpable solvent or the mixture of solvent and dissolved sludge before a pool of solvent or mixture of solvent and dissolved sludge is established in the containment.
8. A method of transporting the apparatus used in these claims on or through the mixture of solvent and dissolved sludge.
9. Apparatus for dissolving crude oil sludge which compnses means to support and transport the apparatus through the dissolved sludge mixture; means for pumping the solvent and dissolved sludge mixture into the sludge ; means for monitoring and controlling the progress of the apparatus when used in these activities; means for removing the dissolved sludge from the storage/settlement tank or other area in which it is held.
10. Apparatus for continuously dissolving crude oil sludge which comprises a means of pumping a solvent or mixture of solvent and dissolved sludge into the mass of crude oil sludge until the sludge dissolves.
11. Apparatus as claimed in claim 9 in which the outlet comprises a rotating block to which two or more nozzles can be removably fitted into or extended from ports equally-spaced around the circumference of the rotor block

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12. Apparatus as claimed in claim 9 in which the outlets comprise nozzles located in positions around or extended from a rotating block to produce the most effective spray pattern and effective speed of rotation of the rotor block.
13. Apparatus as claimed in claim 9 in which the outlets comprise nozzles located in positions around or extended from a rotating block are blocked sequentially to restrict flow and produce the most effective spray pattern and effective speed of rotation of the rotor block.
14. Apparatus as claimed in claim 9 in which the conduit between inlet pump and outlet rotor block includes a valve to permit diversion of some of the flow of the mixture of solvent and dissolved sludge to be used to propel the apparatus through the dissolved sludge.
15. Apparatus which can illuminate the sludge being dissolved
16. Apparatus which can monitor the operation of the apparatus when being used to dissolve sludge.
17. Apparatus to be able to locate the precise position of the apparatus remotely.
18. Apparatus to transport the equipment covered by claim 9 to claim 17 on and through the dissolved sludge.
19. Apparatus to control the operations covered by claim 9 to claim 18.
20. Apparatus to enable a pool of solvent or a pool of mixture of solvent and dissolved sludge to be created and maintained in the crude oil sludge to facilitate the operations of the Apparatus.