AU2006203731B2 - Sludge removal apparatus - Google Patents

Abstract

The invention is a sludge removal apparatus 1 which includes a sludge feeder device 6, an active transfer mechanism 8 and a temporary storage area 14 where 5 the active transfer mechanism 8 is configured to move sludge from the sludge feeder device 6 to the temporary storage area 14. The invention provides a convenient and efficient method of removing sludge from, for example, the surface of a storage tank floor and allowing it to be then transferred to a transport or removal container located remotely from the sludge removal apparatus 1. dL

Description

Regulation 3.2 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: Ralph Calvert Actual Inventor: Ralph Calvert Address for Service: C/- MADDERNS, 1st Floor, 64 Hindmarsh Square, Adelaide, South Australia, Australia Invention title: SLUDGE REMOVAL APPARATUS The following statement is a full description of this invention, including the best method of performing it known to me.

TECHNICAL FIELD The present invention relates to a sludge removal apparatus. More specifically it relates to a sludge removal apparatus used for the mechanical collection, 5 containment, and pumping of sedimentary sludge deposits that accumulate over time on the bottom inside of large storage tanks, such as large crude oil storage tanks, or other large flat bottomed storage vessels. BACKGROUND ART 10 Over time sediment or sludge collects on the bottom of a large liquid storage tank which needs to be removed periodically. The usual procedure for sludge removal is to remove the tank's stored liquid (drained or pumped out) and gain access to the tank via manhole openings. The sludge is then removed as part of the tank 15 cleaning process. Tank cleaning is generally carried out for the inspection of the tank floor and to facilitate any follow up maintenance required. However, the need to remove sludge could be for any other reason. Current practice in New Zealand and still common elsewhere in the world is for the heavier sludge to be handled by manual methods. Lighter sludge's can be 20 moved across the tank floor by mops for conventional suction pump removal. The removal of the heavier sludge usually involves the shoveling of the sludge off the tank floor into appropriate bins which are then manually passed, carried or rolled on conveyors to a manhole. The bins are then emptied just outside the manhole into other forms of materials handling systems. The sludge material is handled 25 outside the tank to get the sludge into the next suitable container for transport to another location for further processing. This current practice is dangerous to the health of personnel involved with the tank cleaning as well as being labour intensive and slow, which increases financial costs to a tank owner or operator. 30 The health danger is associated with the sludge itself which has significant levels of toxic substances as well as creating slippery conditions on the inside of the 2 storage tank. In addition, personnel involved with tank cleaning can often suffer secondary health affects such as allergic reactions to the sludge. The financial cost of the tank cleaning process is not only due to the cost involved in payment of labor to clean the tanks but also due to lost revenue when the tank 5 is inoperative during the cleaning process. Another cleaning method common, but not practiced in NZ, is for large volumes of suitable fluids to be circulated above or sprayed at the accumulated sludge to 'sluice' it and entrain it to carry the sludge out of the tank. The fluid is then 10 processed appropriately outside the tank. A disadvantage of this cleaning method of storage tanks is the environmental risk involved in using large volumes of dispersant chemicals to chemically treat the sludge and the high energy requirements for the big volumes of fluids being handled. 15 Sludge removal apparatus for use in tanks have been built in the past. However there are a number of shortcomings with current commercially available pumps which include the inability for the pump to run dry without damaging the pump, the inability of the pump or other systems to self prime and the lack of 20 ability of the pump valves to handle entrained objects such as stones, cloth rags and the like. It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. 25 All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy 30 and pertinence of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein; this reference 3 does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. It is acknowledged that the term 'comprise' may, under varying jurisdictions, be 5 attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term 'comprise' shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term 'comprised' or 10 'comprising' is used in relation to one or more steps in a method or process. DISCLOSURE OF THE INVENTION According to a first aspect of the present invention there is provided a sludge 15 removal apparatus which includes: " a sludge feeder device; * an active transfer mechanism, and, 20 * a temporary storage area wherein the active transfer mechanism is configured to move sludge from the sludge feeder device to the temporary storage area. 25 According to another aspect of the present invention there is provided a sludge removal apparatus which includes: * a sludge feeder device; 30 * an active transfer mechanism and associated scraper; 4 . a temporary storage area; " at least one one-way valve to prevent back flow of sludge within the temporary storage area, 5 " a discharge outlet, and, * at least one pump to circulate sludge through the temporary storage area to the discharge outlet 10 wherein the active transfer mechanism is configured to move sludge from the sludge feeder device to the temporary storage area and the associated scraper is configured to deposit sludge from the active transfer mechanism into the temporary storage area. 15 Preferably, the sludge feeder device is a feed drum. More preferably, the sludge feeder device has a horizontally rotating feed drum. 20 More preferably still, the feed drum has profiling on the drum to channel the sludge into the centre of the machine. More preferably, the feed drum has an Archimedes screw profiling. 25 Such profiling achieves a pumping effect of the sludge from the storage tank floor to the centre of the machine. Preferably, the associated scraper is situated such that it can scrap sludge off the active transfer mechanism. 30 Preferably, the active transfer mechanism is a feed elevator. 5 Preferably, the active transfer mechanism is situated at an angle of between 00 and 900 from the tank surface. More preferably, the active transfer mechanism is situated at an angle of 5 substantially 450 from the feed drum. Preferably, the active transfer mechanism has a means to aid in the transfer of the sludge. 10 More preferably, the means consists of at least one of the group comprising, scrapers, chains, Archimedes screw arrangement. Preferably, the pump comprises three chambers consisting of: 15 0 a feed hopper chamber; * a pump chamber, and, * a discharge chamber 20 wherein the feed hopper chamber receives sludge from the active transport device and the discharge chamber is connected to the discharge outlet. Preferably, the pump chamber is separated from the feed hopper chamber by a one-way inlet valve. 25 More preferably, the inlet valve has two one-way opening flaps which move independently. More preferably, the inlet valve flaps provide a seal when in a closed position. 30 The inlet valve prevents back flow of sludge from the discharge pump chamber to the feed hopper pump chamber and is designed to provide minimum impedance to passing sludge when the valve flaps are open. 6 Preferably, the pump chamber houses the pump. More preferably, the pump is a hydraulic cylinder pump. 5 Preferably, the pump chamber is separated from the discharge chamber by a one way discharge valve. The discharge valve prevents back flow of sludge from the discharge chamber to 10 the pump chamber. Preferably, the discharge outlet is connected to a discharge hose. The discharge hose may discharge sludge to a remote storage unit. 15 Preferably, the sludge removal apparatus has at least one spray dispenser to apply a diluent to the sludge to aid its collection. More preferably, spray dispensers are situated between the sludge feeder device 20 and the feed hopper chamber. Preferably, the spray dispensers can be regulated to dispense a diluent at a preferred rate. 25 More preferably, a diluent is one of a group consisting of water, hydrocarbon, detergent solution. Preferably, the sludge removal apparatus has at least three support structures to support the sludge removal apparatus above the tank surface. 30 More preferably, the support structures comprise at least one of the following group consisting of drive units, wheels, skis, or the like. 7 Still more preferably, the support structures comprise drive units. Preferably the drive units consist of wheels and tracks. 5 More preferably, the sludge removal apparatus has two drive units either side of the sludge removal apparatus. Still more preferably, the drive units are independently driven. 10 More preferably, the sludge removal apparatus has a guide wheel. Still more preferably, the guide wheel is height adjustable and pivots on a vertical plane. 15 Preferably, the sludge removal apparatus may be dismantled. Dismantling of the sludge removal apparatus enables it to be passed through an access opening. 20 Preferably, the sludge removal apparatus is powered by a non-manual power source such as a engine driven hydraulic power pack. More preferably, non-manual power source is attached remotely to the sludge 25 removal apparatus. Preferably, the surface is a surface of a storage tank, storm water drain, culvert, sewer, conduit, pipe, or the like. 30 More preferably, the surface is the floor of a storage tank. One way the present invention can work is as follows: 8 Sludge from a tank surface is harvested with a rotating feed drum and channelled onto an elevator. The sludge is raised and deposited into a feed hopper chamber of a temporary storage unit with a cleaning scraper. The sludge passes down through a one-way valve into a pumping chamber and is channelled up into the 5 discharge chamber via a pump. The harvested sludge is then discharged to a remote storage tank external to the tank via a hose. The present invention is useful in industries where storage tanks must be cleaned on a regular basis. The apparatus has the advantage of: 10 0 reducing the number of persons required to be inside the storage tank to carry out the process of sludge removal; e being faster than the manual method of clearing sludge thereby reducing the exposure time within the storage tank; 15 e having the ability to clear sludge from a surface containing course material such as rags or bolts. * having the ability to maneuver over a layer of sludge. 20 e providing a mechanical method of sludge removal that is powered by a suitable non manual power source located remote from the sludge removal apparatus, which removes the repetitive and sometimes heavy labor activity and so reduces the likelihood of personal injury; 25 * providing a machine that contains the sludge in its pumping chambers while inside the storage tank and pumping the sludge out of the storage tank through suitable piping directly into a transport container for further processing which eliminates the spillages and dripping outside the storage 30 tank that happens with manually emptying the containers that were filled inside the tank; 9 * which provides a machine which decreases the overall environmental risks associated with previous methods of tank cleaning such as use of large volumes of dispersant chemicals; 5 * decreasing the overall cost of the sludge removal phase of the storage tank cleaning activity, and, * being easily dismantled to pass through a manhole door at the base of a 10 storage tank. The present invention addresses the problems identified in the prior art above of low efficiency of sludge removal from storage tanks in terms of time and costs, high risk of health and safety danger, high risk of environmental pollution and the 15 inability of current sludge removal apparatus to run dry, self prime and to handle entrained objects such as stones, cloth rags and the like. BRIEF DESCRIPTION OF DRAWINGS 20 Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1: shows a side view of one embodiment of a sludge removal 25 apparatus of the present invention, and, Figure 2: shows a plan view of the embodiment shown in Figure 1. BEST MODES FOR CARRYING OUT THE INVENTION 30 The invention is now described in relation to a preferred embodiment of the present invention as shown in Figures 1 to 2. It should be appreciated that the 10 invention may be varied from the Figures without departing from the scope of the invention. Referring to Figures 1 to 2, a sludge removal apparatus is shown generally 5 indicated by arrow 1. The sludge removal apparatus 1 has a body generally indicated by arrow 2. Which acts as a temporary storage area for the sludge 100. To move the sludge removal apparatus 1 around a tank floor 5 there is a set of driven drive units in the form of caterpillar tracks 3 mounted either side of the 1o sludge removal apparatus body 2. The caterpillar tracks 3 consist of wheels 3a and tracks 3b. The caterpillar tracks 3 carry the main weight of the pump body 2. They are driven by individual variable speed hydraulic motors (not shown) to enable full maneuvering as required to cut the swaths into the sludge on the tank floor. A rear wheel 4 is adjustable in height to vary the clearance of the elevator from the 15 tank surface 5. A sludge feeder device in the form of a feed drum 6 has an Archimedes screw profile 7a protruding from its surface 7b. The feed drum 6 is wider than the width of the body 2 of the sludge removal apparatus 1 to give a maximum operating 20 swath as the sludge removal apparatus 1 is driven across a tank floor 5. The feed drum 6 lies across the front of the sludge removal apparatus in very close proximity to the tank floor 5 and is the first component to start the handling of the sludge 100. As the sludge removal apparatus 1 is driven forward into the layer of sludge 100 on the tank floor 5 (in the direction a) the feed drum 6 agitates the 25 sludge to semi fluidize it and propels the sludge (in the direction b) behind it where it is next handled an active transfer mechanism in the form of a feeder elevator 8. Spray applicator nozzle 9, can spray a diluting liquid to aid the fluidizing of the sludge on to the rotating feeder drum 6. Spray applicator nozzle 9 is connected to a fluid source and pump (not shown). 30 A frame 10 shown in Figure 1 supports the feeder drum 6. The frame is attached to the front end of the feeder elevator 8 and may pivot at its point of attachment to 11 allow the feed drum to rise upwards and 'climb' over small objects on the tank floor or rise into sludge deposits that are too deep to feed from the bottom. The feeder drum 6 is driven from the feed elevator 8 by a feed elevator motor (not 5 shown). The feed elevator 8 has a set of scrapers 11 on a driven chain assembly 12 inside a trough like body 13. The feed elevator 8 is set at an angle up from the tank floor 7 and picks up the sludge on the floor that has been gathered behind the feed drum 6 and elevates the sludge up off the tank floor 9in the direction c) and then discharges the sludge into the pump hopper chamber 14. To aid the discharge of 10 the sludge off the feed elevator 8, a second fluid applicator 15 can spray diluting fluid down on to the feed elevator scrapers 11 as they exit the feed elevator 8. To further aid the movement of the sludge off the elevator into the body feed hopper chamber 14 of the sludge removal apparatus 2 (in the direction d) particularly when the sludge is of a sticky consistency, a second scraper 16 is positioned to 15 scrape sludge off the feed elevator 8. The sludge then falls off the second scraper 16 direct into the feed hopper chamber 14. The feed elevator 8 is driven by a variable speed hydraulic motor (not shown). The hydraulic power supply to the feed elevator drive motor is pressure controlled. This provides a level of safety if debris gets caught in the moving parts of the sludge removal apparatus 1, as there 20 is limited power available, and the parts stop moving. A pump 17 is powered by a hydraulic ram 18. The pump 17 has ability to self prime or run dry as the feeding of sludge occurs. A second important feature of the pump is in its arrangement of valves which allows it to pass significant solid 25 items e.g. stones which can be entrained in the sludge. The feed hopper chamber 14 receives sludge from the feed elevator 8. A one-way valve 19 allows sludge to be drawn from the feed hopper chamber 14 into the pump chamber 20 by the pump piston 21 in its suction stroke (in the direction e). 30 When the pump piston 21 moves in the power stroke direction, sludge is restricted from returning to the feed hopper chamber 14 by the suction valve 22 closing so it is discharged into the discharge chamber 23 (in the direction f) and 12 then into a discharge hose 24 via a discharge outlet 25 (in the direction g). The sludge 100 is then transferred via the discharge hose 24 to a remote storage tank (not shown). Sieves can be fitted into the feed hopper chamber 14 if required but the design of the pump 17 and one-way valve unit 19 are such that a level of 5 extraneous debris and items can pass through without undue disruption via independently spring loaded flaps which seal when closed. The hydraulic cylinder can be varied in cycle rate as required to match the flow of sludge off the elevator. 10 Handrails (not shown) at an effective height off the tank floor are fitted to the pump. These give the operators security and support as the operators move around the machine and aid its maneuverings across the tank floor. An emergency stop valve (not shown) is fitted into the hydraulic circuit to provide 15 total stop to all the hydraulic powered features. The emergency stop valve is spring loaded such that it can be tripped to immediately activate. A trip wire (not shown) is provided along the length of the sludge removal apparatus body 2 and a trip bumper type bar (not shown) is fitted across the front of the sludge removal apparatus body 2. 20 An air operated light (not shown) is mounted above the handrails. A general purpose container box (not shown) is mounted between the handrails. 25 Due to the restricted size of manhole openings for access into the tank, the sludge removal apparatus 1 can be dismantled to be of a size that can fit through the manhole opening. For the assembled sludge removal apparatus to function inside the tank it is connected to a hydraulic power pack outside the tank by flexible hoses (not shown) to power the sludge removal apparatus 1. In addition, the 30 sludge removal apparatus 1 is supplied with pressurized air to power a light system (not shown) (for use in potentially explosive atmospheres), water and or other liquids suitable to aid in the pumping of the sludge. A discharge hose 24 is 13 required as a conduit for the sludge to be delivered from the sludge removal apparatus inside the tank to a transport container located outside the tank. The discharge pipe is significantly larger in diameter to the other service hoses but like them it is flexible to permit the maneuverability of the sludge removal apparatus 5 inside the tank. The present invention provides a convenient and efficient method of removing sludge from the surface of a storage tank floor and pumping it inside the tank to a transport container located outside the tank 10 Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims. 14

Claims (21)

1. A sludge removal apparatus which includes: 5 * a sludge feeder device; e an active transfer mechanism and associated scraper; * a temporary storage area; * at least one one-way valve to prevent back flow of sludge within the temporary storage area; 10 e a discharge outlet; and * at least one pump to circulate sludge through the temporary storage area to the discharge outlet wherein the active transfer mechanism is configured to move sludge from the sludge feeder 15 device to the temporary storage area and the associated scraper is configured to deposit sludge from the active transfer mechanism into the temporary storage area, and wherein the associated scraper is situated such that it can scrape sludge off the active transfer mechanism. 20

2. A sludge removal apparatus as claimed in claim 1 wherein the sludge feeder device is a horizontally rotating feed drum.

3. A sludge removal apparatus as claimed in claim 2 wherein the horizontally rotating 25 feed drum has profiling on the drum to channel the sludge into the centre of the machine, and wherein the profiling includes an Archinedes screw profiling.

4. A sludge removal apparatus as claimed in any one of claims I to 3, wherein the active transfer mechanism is a feed elevator situated at an angle of between 0' and 90* from the 30 surface.

5. A sludge removal apparatus as claimed in any one of claims 1 to 4, wherein the active transfer mechanism has a means to aid in the transfer of the sludge which consists of at least one of the group comprising, scrapers, chains, Archimedes screw arrangement. 15

6. A sludge removal apparatus as claimed in any one of claims 1 to 5, wherein the temporary storage area comprises three chambers consisting of: 5 * a feed hopper chamber; * a pump chamber; and, * a discharge chamber wherein the feed hopper chamber receives sludge from the active transport device and the 10 discharge chamber is connected to the discharge outlet.

7. A sludge removal apparatus as claimed in claim 6 wherein the pump chamber is separated from the feed hopper chamber by a one-way inlet valve and, wherein the one-way inlet valve has two one-way opening flaps which move independently. 15

8. A sludge removal apparatus as claimed in claim 7 wherein the inlet valve flaps provide a seal when in a closed position.

9. A sludge removal apparatus as claimed in any one of claims 6 to 8 wherein the pump 20 chamber houses the pump, and wherein the pump is a hydraulic cylinder pump.

10. A sludge removal apparatus as claimed in any one of claims 6 to 9 wherein the pump chamber is separated from the discharge chamber by a one-way discharge valve, and wherein the discharge valve prevents back flow of sludge from the discharge chamber to the pump 25 chamber.

11. A sludge removal apparatus as claimed in any one of claims I to 10 wherein the discharge outlet is connected to a discharge hose, and wherein the discharge hose discharges sludge to a remote storage unit. 30

12. A sludge removal apparatus as claimed in any one of claims 1 to I1 wherein the sludge removal apparatus has at least one spray dispenser to apply a diluent to the sludge to aid its collection. 35

13. A sludge removal apparatus as claimed in claim 12 wherein the spray dispenser(s) are situated between the sludge feeder device and the feed hopper chamber. 16

14. A sludge removal apparatus as claimed in claim 13 wherein the spray dispenser(s) can be regulated to dispense a diluent at a preferred rate, and wherein the diluent is one of a group consisting of water, hydrocarbon, detergent solution. 5

15. A sludge removal apparatus as claimed in any one of claims I to 14, wherein the sludge removal apparatus has at least three support structures to support the sludge removal apparatus above the surface, and wherein the support structures comprise at least one of the following group consisting of drive units, wheels, skis, or the like. 10

16. A sludge removal apparatus as claimed in claim 15 wherein the support structures comprise drive units, and wherein the drive units consist of wheels and tracks which are independently driven. 15

17. A sludge removal apparatus as claimed in claim 15 or claim 16 wherein the drive units are situated either side of the sludge removal apparatus.

18. A sludge removal apparatus as claimed in claim 17 wherein the sludge removal apparatus has a guide wheel which is height adjustable and pivots about a vertical axis. 20

19. A sludge removal apparatus as claimed in any one of claims 1 to 18 wherein the sludge removal apparatus is dismantled.

20. A sludge removal apparatus as claimed in any one of claims 1 to 19, wherein the 25 sludge removal apparatus is powered by a non-manual power source such as engine powered hydraulic power pack and wherein the non-manual power source is attached remotely to the sludge removal apparatus.

21. A sludge removal apparatus as claimed in any one of claims 1 to 20, wherein a surface 30 for sludge removal includes a surface of a storage tank, storm water drain, culvert, sewer, conduit, pipe, or the like. 17