WO1996009874A1

WO1996009874A1 - Oil/sludge separator

Info

Publication number: WO1996009874A1
Application number: PCT/GB1995/002291
Authority: WO
Inventors: John Keith Tooley
Original assignee: John Keith Tooley
Priority date: 1994-09-27
Filing date: 1995-09-27
Publication date: 1996-04-04
Also published as: GB2294218A; GB2294218B; GB9519702D0; AU3570795A; GB9419418D0

Abstract

Apparatus for separating oil and sludge comprising a cylindrical vortex tank (26) having a tank inlet (24) for sludge bearing oil, the tank inlet (24) being arranged to permit swirling of the sludge bearing oil to form a vortex (28) within the vortex tank (26). Sludge outlet means (20a) are provided in the cylindrical vortex tank (26) for the outlet of centrifugally separated sludge to a sludge drying-extraction vessel (12) having dryer means (41) and a dried sludge discharge outlet (20b).

Description

Title - Oil/Sludσe Separator

This invention relates to a method and apparatus for separating oil and sludge and particularly relates to improvements in the type of apparatus disclosed in my prior British Patent application no 2 249 502.

British Patent application No 2 249 502 describes and claims an apparatus for separating oil and sludge etc., comprising a cylindrical tank, one end of the tank possessing an opening which leads into an elongate chamber, a plurality of hollow cones situated towards the end of the chamber remote from the tank, each cone being situated within but spaced from its neighbour, the apex of each cone being towards the end of the chamber remote from the tank, the cone nearest the tank and every alternate cone therefrom being open at the apex, the base edge of each open cone extending to the walls of the chamber and the base edge of the remaining cones being spaced from the walls of the chamber, a reservoir extending from the base of the space between each adjacent pair of cones at the exterior of the elongate chamber and an oil outlet pipe extending from the end of the chamber remote from the tank.

My prior patent application also describes and claims a process for separating oil and sludge etc. using such an apparatus, comprising pumping the oil/sludge mixture into the cylindrical tank under pressure so that the force of the impact of the mixture against a wall of the tank causes the mixture to spin in a vortex, providing a body of water in the lower portion of the elongate chamber which is adjacent the cylindrical tank such that oil passing to the centre of the vortex will rise from the centre of the vortex through the body of water and continue to rise until it reaches the plurality of cones, allowing the oil to pass between the cones and removing the oil from the end of the elongate chamber remote from the cylindrical tank.

Although the present invention was particularly devised by way of improvement of the apparatus and process described in my Patent Application no 2 249 502, certain aspects of the present invention may be more generally applied to other forms of oil/sludge separator.

It is an object of the present invention to provide a new or improved apparatus and a new or improved process for separating oil and sludge.

Viewed from a first aspect, the invention provides an apparatus for separating oil and sludge comprising a cylindrical vortex tank having a tank inlet for sludge bearing oil, the tank inlet being arranged to permit swirling of the sludge bearing oil to form a vortex within the vortex tank, sludge outlet means being provided in the cylindrical vortex tank for the outlet of centrifugally separated sludge, a sludge drying-extraction vessel having a dryer inlet communicating with said sludge outlet to receive the centrifugally separated sludge and having dryer means therein, the sludge drying-extraction vessel having a dried sludge discharge outlet.

The sludge drying-extraction vessel may conveniently be disposed vertically below the cylindrical vortex tank so as to be gravity fed with centrifugally separated sludge through said communicating sludge outlet and dryer inlet.

The drying-extraction vessel will generally be provided with means for drying the separated sludge. A preferred form of such means is steam injection. The drying-extraction vessel may also be provided with suitable means for the filtering and/or chemical treatment of materials fed into, or extracted from, the vessel, and may also be provided with agitator means.

The dried sludge discharge outlet may communicate with conveyor means or may discharge directly into a receptacle such as a skip.

Viewed from a further aspect, the invention provides an apparatus for separating oil and sludge comprising a cylindrical vortex tank having a tank inlet for sludge bearing oil, the tank inlet being arranged to permit swirling of the sludge bearing oil to form a vortex within the vortex tank, an elongate upright oil/water separator chamber having an outer wall, the lower portion of the separator chamber having an inner tubular wall communicating and co-axial with the cylindrical vortex tank, a plurality of hollow cones being provided in the upper portion of the oil/water separator chamber above said inner tubular wall, each cone being situated within but spaced from its neighbour, the apex of each cone facing upwardly, the cone nearest the cylindrical vortex tank and every alternate cone therefrom being open at the apex, the base edge of the remaining closed cones being spaced from the outer wall of the chamber, and the base edge of each open cone having at least a portion spaced from the outer wall of the chamber to permit downward drainage of water, reservoir means for the downwardly drained water being afforded between the outer wall and said inner tubular wall at the lower portion of the separator chamber and oil outlet means extending from the upper end of the oil/water separator chamber.

The cones are preferably disposed in such a manner as to facilitate drainage of water to a point at the base of each cone. Most preferably the cones are tilted.

The cones are preferably apertured to permit oil to pass upwards through the plurality of cones. For example, each cone may be provided with a plurality of equally-sized holes spaced around the central axis of the cone. The oil outlet means will generally be provided with exhaust vent and overflow/condenser means.

Preferably, the reservoir into which the water drains communicates with the oil/water separator chamber.

The invention further provides a process for separating oil and sludge using apparatus as set out in accordance with either of the preceding aspects of the invention, the process comprising the steps of pumping the sludge bearing oil tangentially into the cylindrical vortex tank to cause the sludge bearing oil to swirl into a vortex, providing a body of water in the lower portion of the elongate upright oil water separator chamber such that the centre of the vortex communicates with the body of water, allowing the oil/water mixture to percolate through the plurality of cones and removing the oil from the top of the oil/water separator chamber.

The sludge bearing oil is preferably pre-heated before its introduction to the vortex tank, e.g. by being passed through a heat exchanger.

Apparatus embodying the invention will now be described in more detail by way of example only with reference to the accompanying drawings, in which

Figure 1 is a vertical sectional view through an apparatus for separating oil and sludge;

Figure 2 is a more detailed sectional view of an upper portion of the apparatus of Figure 1;

Figure 3 shows plan views of cones forming part of the apparatus of Figure 1; and Figure 4 is a view of an upper portion of an alternative embodiment of an apparatus for separating oil and sludge.

Crude oil, a mixture of oil with sludge and water, is pumped by a feed pump 14 through a heat exchanger 5 and is introduced at 24 through a tangential inlet into a cylindrical vortex chamber 26. The forcible injection of the crude oil causes swirling in the cylindrical vortex chamber and a vortex generally indicated at 28 is formed centrally around a co-axially provided tubular wall 31, this tubular wall extending the full vertical length of the cylindrical vortex chamber 26. The top part of the tubular wall 31 has numerous large vertical slits around its circumference, the bottom part being of smaller diameter and having no such slits.

The swirling and vortex created in the top of the cylindrical vortex chamber 26 by the forcible injection of the crude oil is maintained at constant momentum by the direct input of steam through a tangential inlet 25a. The steam also improves the separation of the crude oil mixture.

The top of the cylindrical vortex chamber has a co-axially provided tubular wall 29, connected directly above the tubular wall 31, which forms an inner wall of an upright oil/water separator chamber 6. The latter also has an outer wall 30 which is cylindrical in shape. Within the oil/water separator chamber 6, an array of cones is provided at 32. The lowermost cone has an open apex as shown at

33 (see Figure 3a) . The next cone has a closed apex as shown at

34 (Figure 3b) and the open and closed apex cones alternate through the array of cones. The cones are tilted to one side of the oil/water separator chamber.

The cones 34 have closed apexes and have their outer edges spaced as at 35 from the outer wall 30 of the oil/water separator chamber.

In the prior Patent Application no 2 249 502, the cones having open apexes are connected at their outer lower edges with the outer wall 30 of the oil/water separator chamber. However in the present invention, at least part of the periphery of the cones is not connected to the wall 30 so as to leave at least a partial space for water to drain downwardly.

Additionally in the present invention the cones 33 and 34 contain a number of equally sized holes equally spaced from the centre axis of the cones.

It has been found that the banks of pipes which were previously used for receiving the downwardly drained water are not necessary and can be omitted, the water draining into a calm area 36 which co-axially surrounds the inner wall 29 of the separator chamber. The calm area is defined between the inner and outer walls 29 and 30 but is in full communication with the remainder of the oil water separation chamber 6. A water level sensor is provided at 1 to sense the full water level and at 2 to sense a low water level, automatically opening a water outlet 37 to empty the body of the oil/water separator chamber up to the lower level 2.

In use, oil is the predominant constituent of the vortex 28 and passes through the large vertical slits of the inner tubular wall

31 and upwardly within the inner tubular wall 29 into the assembly of cones, which permit the oil gradually to separate from the water, eventually reaching the top of the oil/water separator chamber 6. An outlet for oil is provided at 38. A pipe (not shown) is connected to the outlet 38 and leads to an oil storage tank. Material passing from the top of the oil/water separator chamber 6 is received in an overflow/condensor 7 fitted with exhaust vents 18.

In the alternative embodiment shown in Figure 4, material passes out of the top of the oil/water separator chamber 60 under pressure and via an exit pipe 61 and is fed tangentially into a further vortex chamber 62. Gas and vapours are drawn off at the top of the further vortex chamber 62 through an exhaust pipe 63 which leads to a condenser 64. Vacuum is applied to the base of the condenser 64 by a vacuum pump 9 (see Figure 1), the condensed gas and vapours being fed to a suitable waste storage tank (not shown) . Meanwhile, oil settles at the base of the further vortex chamber 62 and passes via an outlet pipe 65 to an oil storage tank (not shown) .

The separation and removal of the oil from the oil/water mixture has now been described but it will be appreciated that the spinning crude oil deposits the relatively heavier sludge by centrifugal force at the peripheral wall of the cylindrical vortex chamber 26. The sludge slides downwardly to the bottom of the cylindrical vortex chamber 26. The outlet from the cylindrical vortex chamber 26 has an outlet valve 20a communicating with a drying-extraction vessel 12. The outlet from the cylindrical vortex chamber has a tangential inlet for steam injection 25b, above the outlet valve 20a, the steam injection causing further swirling of the sludge before it enters the drying-extraction vessel. A second vortex, generally indicated at 39, is formed centrally around co-axially provided inner tubular wall 31, which as described earlier has no slits at the bottom of the cylindrical vortex chamber. The inner tubular wall 31 communicates with a further inner tubular wall 40 of similar diameter immediately below the outlet valve 20a. The inner tubular wall 40 has a deflector plate connected to its end furthest from the cylindrical vortex chamber. The deflector plate allows any oil/water separated from the sludge by the steam injector 25b to travel upwardly without obstruction via the inner tubular walls 40 and 31.

The drying-extraction vessel 12 is provided with steam injection points 41 connected to a manifold 13, a chemical dosing tank 17, filter boxes 21 and the vacuum pump 9 and vacuum breaker 19, to dry the sludge and clean the water. The dried sludge cake can be discharged as necessary by opening an outlet valve 20b at the base of the drying-extraction vessel. The water is sucked out by the vacuum pump 9 through the filter boxes 21 into a vacuum tank 15 fitted with a condensation vessel 15. A water level sensor is provided at 3 to sense the full water level and at 4 to sense a low water level, automatically starting the vacuum pump 9, to empty the body of the drying-extraction vessel 12 to the lower level 4. The vacuum tank 15 and the drying-extraction vessel 12 are provided with hinged manways 23a, 23b for maintenance access etc.

A pressure relief 22 links the drying-extraction vessel 12 to the cylindrical vortex chamber 26 to prevent over-pressurisation of the drying-extraction vessel 12.

The water outlet 37 from the upright oil/water separator chamber may supply water via a recirculating pump 11 to the chemical dosing tank 17, where chemicals may be added by a chemical mixer 8 and dosing pump 10 before the water is introduced to the drying-extraction vessel.

The filter box 21 may be loosened to allow the filter to be self- cleaned.

The dried sludge cake may be discharged by conveyor means or directly into a skip.

The apparatus according to the invention may be erected on a permanent site, or may be adapted for transportation and rapid erection on a temporary or semi-permanent site. For example, the apparatus may be adapted for transportation on a lorry or trailer.

Claims

1. An apparatus for separating oil and sludge comprising a cylindrical vortex tank having a tank inlet for sludge bearing oil, the tank inlet being arranged to permit swirling of the sludge bearing oil to form a vortex within the vortex tank, sludge outlet means being provided in the cylindrical vortex tank for the outlet of centrifugally separated sludge, a sludge drying-extraction vessel having a dryer inlet communicating with said sludge outlet to receive the centrifugally separated sludge and having dryer means therein, the sludge drying-extraction vessel having a dried sludge discharge outlet.

2. Apparatus as claimed in claim 1, wherein the sludge drying- extraction vessel is disposed vertically below the cylindrical vortex tank so as to be gravity fed with centrifugally separated sludge through said communicating sludge outlet and dryer inlet.

3. Apparatus as claimed in claim 1 or claim 2, wherein the drying-extraction vessel is provided with steam injection means for drying the separated sludge.

. Apparatus as claimed in any preceding claim, wherein the drying-extraction vessel is provided with means for the filtering and/or chemical treatment of materials fed into, or extracted from, the vessel.

5. Apparatus as claimed in any preceding claim, wherein the dried sludge discharge outlet discharges directly into a receptacle such as a skip.

6. Apparatus as claimed in any preceding claim, further comprising an elongate upright oil/water separator chamber having an outer wall, the lower portion of the separator chamber having an inner tubular wall communicating and co-axial with the cylindrical vortex tank, a plurality of hollow cones being provided in the upper portion of the oil/water separator chamber above said inner tubular wall, each cone being situated within but spaced from its neighbour, the apex of each cone facing upwardly, the cone nearest the cylindrical vortex tank and every alternate cone therefrom being open at the apex, the base edge of the remaining closed cones being spaced from the outer wall of the chamber, and the base edge of each open cone having at least a portion spaced from the outer wall of the chamber to permit downward drainage of water, reservoir means for the downwardly drained water being afforded between the outer wall and said inner tubular wall at the lower portion of the separator chamber and oil outlet means extending from the upper end of the oil/water separator chamber.

7. Apparatus as claimed in claim 6, wherein the cones are tilted.

8. Apparatus as claimed in claim 6 or claim 7, wherein the cones are apertured to permit oil to pass upwards through the plurality of cones.

9. Apparatus as claimed in any one of claims 6 to 8, wherein the reservoir means communicates with the oil/water separator chamber.

10. A process for separating oil and sludge using apparatus as claimed in any one of claims 6 to 9, the process comprising the steps of pumping the sludge bearing oil tangentially into the cylindrical vortex tank to cause the sludge bearing oil to swirl into a vortex, providing a body of water in the lower portion of the elongate upright oil water separator chamber such that the centre of the vortex communicates with the body of water, allowing the oil/water mixture to percolate through the plurality of cones and removing the oil from the top of the oil/water separator chamber.

11. Method as claimed in claim 10, wherein the sludge bearing oil is pre-heated before its introduction to the vortex tank by being passed through a heat exchanger.