Used Oil Recycling and Pretreatment Filtration Assembly

Abstract

A filtration system suitable for recovering base stock from used lubricating oil and other applications passes feedstock over nano-filtration membranes in a serpentine flow. Pressure boosters installed in the openings separating consecutive stacks serve to restore lost pressure of the feedstock. As pretreatment a knocking non-blinding filter separates particulates from a feedstock by a knocking action that dislodges particulate matter which has come to rest on the screen. Further pretreatment includes a vacuum evaporator for flash evaporation of volatile components from a liquid and effecting the extraction of water and glycol from used engine lubricating oil. The liquid is heated or cooled when flowing over some of the surfaces to adjust for heat lost or acquired during exposure of the liquid surface to a gas or vacuum. Liquid moves on the surface of the discs under centrifugal force or a wiper blade guides the liquid as it moves over the support surface.

Claims

1. A filtration system to produce a permeate from a feedstock comprising multiple permeable membrane support panels each carrying respective membranes, each support panel having a receiving space within to serve as a cavity for accepting permeate driven through the membranes by pressure applied to the feedstock and a permeate-receiving cavity outlet to drain-off permeate, wherein a) the multiple membrane support panels are mounted in a common pressure-containing vessel having a feedstock inlet and outlets for permeate and concentrate, and b) the pressure vessel contains at least one pressure-sustaining separator plate positioned between at least two adjacent membrane support panels, the separator plate having a flow-through opening at one end to allow fluid to flow from one membrane support panel to the next.

2. The filtration system as in claim 1 wherein the at least two adjacent membrane support panels are positioned on opposite sides of the separator plate so as to reverse the direction of feedstock flow over the consecutive membrane support panels on either side of the separator plate.

3. The filtration system as in claim 1 wherein: a) the support panels comprise two permeable panels mounted back-to-back with two respective membranes located on their outer-facing surfaces, and b) the two panels define between them the receiving space there within to serve as the cavity for accepting permeate driven through the two membranes by pressure applied to the feedstock, thereby constituting panel assemblies.

4. The filtration system as in claim 3 wherein, between separator plates, groups of panel assemblies are arrayed in a parallel configuration so that feedstock will flow in the same direction on both sides of the panel assemblies within the group, collectively the panel assemblies in a group constituting a stack of panel assemblies separated by the separator plates.

5. The filtration system as in claim 4 wherein the pressure vessel contains three or more stacks of panel assemblies, each consecutive stack being separated from an adjacent stack of panel assemblies by a pressure-sustaining separator plate, each separator plate having a flow-through opening at one end to allow fluid to flow from one stack of panel assemblies to the next.

6. A filtration system as in claim 5 comprising a pressure booster mounted in at least one separator plate flow-through opening to restore lost pressure between consecutive stacks of panel assemblies.

7. A filter system as in claim 6 comprising pressure boosters respectively mounted in the flow-through openings in every other separator plate.

8. A filter system as in claim 7 comprising pressure boosters respectively mounted in the flow-through openings in every separator plate.

9. A filter system as in claim 6 wherein the pressure booster is actuated by an electric motor.

10. A filter system as in claim 7 wherein the pressure boosters are actuated by respective electric motors.

11. A filter system as in claim 8 wherein the pressure boosters are actuated by respective electric motors.

12. A filter system as in claim 6 wherein the pressure booster is actuated by a rotating shaft driven from outside the pressure vessel.

13. A filtration system as in claim 7 wherein the pressure boosters are actuated by a common rotating shaft driven from outside the pressure vessel.

14. A filtration system as in claim 8 wherein the pressure boosters are actuated by a common rotating shaft driven from outside the pressure vessel.

15. A filtration system as in claim 13 wherein the common shaft penetrates intervening separator plate through a pressure seal.

16. A filtration system as in claim 5 comprising respective frames within which each membrane panel assembly is mounted, the frames, when the membrane panel assemblies are combined to form stacks, serving as part of the walls of the pressure containment vessel, wherein the frames provide a manifold connected to the permeate outlets of the permeate receiving cavities of each membrane panel assembly for collection of permeate for delivery to an external storage vessel.

17. A filtration system as in claim 16 wherein separator plates interspersed between the stacks of panel assemblies and serving as part of the walls of the pressure containment vessel are respectively provided with conduits connected to the manifolds of the frames to receive and convey permeate out of the pressure containment vessel.

18. A filtration system as in claim 4 wherein the permeate-receiving cavity outlets of each panel assembly in a stack are connected to a stack manifold that is connected to deliver permeate to a back-pressure control valve having an associated pressure sensor and valve control system for establishing the pressure within the permeate-receiving cavity.

19. A filtration system as in claim 4 wherein the permeate-receiving cavity outlets of each panel assembly in a stack are connected to a stack manifold that is connected through passageways formed in a separator plate at the end of the stack to deliver permeate to a back-pressure control valve having an associated pressure sensor and valve control system for establishing the pressure within the permeate-receiving cavity.

20. A knocking non-blinding filter for extracting a filtrate from a feedstock comprising: a. a resiliently supported frame in turn supporting a durable, permeable screen or mesh that is oriented at a flow-supporting downwardly inclined angle, b. an entry region for receiving the feedstock at the upper end of the frame from which the feedstock will flow down the inclined screen to the base end of the frame, c. a catching container positioned beneath the screen for capturing the filtrate passing through the screen, and d. an actuator coupled to the frame to apply a force with a component for displacing the frame in a generally horizontal direction, or in a direction aligned with the upward incline of the screen, with a knocking action whereby the force applies a rapid onset of acceleration to the screen that assists in dislodging non-penetrating particulate material resting thereon.

21. A filter as in claim 20 a return displacement mechanism for causing the filter to thereafter return to its original location after the frame has been displaced by the knocking action.

22. A filter as in claim 20 wherein motion of the screen is cyclical and the actuator applies an acceleration to the screen at one stage in the cycle wherein the acceleration so applied is greater than the absolute value of any other acceleration or deceleration occurring during the cycle.

23. A filter as in claim 20 wherein the applied acceleration is at least 1.5 times the absolute value of any other acceleration or deceleration occurring during the cycle.

24. A filter as in claim 20 comprising an actuator coupled to the frame to generate the accelerating force, such actuator being selected from the following class: a) an electrical solenoid b) a hammer carried on a rotating support c) mechanical linkages coupled to a rotating drive d) an off-center mass carried by a rotating drive.

25. A filter as in claim 21 wherein the return displacement mechanism comprises one or more springs or resilient elements to return the displaced screen to its original location.

26. A filter as in claim 20 wherein the filter is a filter of steel mesh.

27. A filter as in claim 26 wherein the filter is a stainless steel mesh with openings smaller than 200 microns.

28. A filter as in claim 20 wherein the force accelerating the screen achieves an acceleration of 0.3 g to 5 g over at least a short length of its travel.

29. A filter as in claim 20 wherein the force applied to the frame oscillates with a frequency of 1 per 5 seconds to 20 per second.

30. A gas-liquid exchange interface apparatus for effecting chemical or physical exchanges between a gas and a liquid or evaporation of gas from the liquid comprising: a) a containment for maintaining inner components in a gas-tight, pressure controlled environment; b) a liquid inlet to the containment for introducing the liquid into the containment; c) a segmented, vertical cascade of support surfaces positioned within the containment in the form of a column of segments 220 wherein a first support surface within each segment is positioned: i) to receive the liquid from the liquid inlet onto a central region of the first support surface, and ii) to allow the liquid, when present and so deposited, to flow radially outward from the central region to and beyond the periphery of the first support surface; and iii) to expose liquid flowing over the first support surface for release of volatiles or for carrying-out a gas-liquid reaction; Liquid flowing over the second support surface is uncovered for exposure to release volatiles or carry-out a gas-liquid reaction. d) each segment providing a peripheral receiving surface and transfer passageway to transfer such liquid leaving the first support surface for deposition onto a second support surface for further inward radial flow over such second support surface towards the central area of the second support surface; e) a central opening in the central area of the second support surface positioned to direct the liquid onto the central region of the first support surface of the next consecutive segment, f) a gas outlet on the containment for introducing or evacuating gases present therein or volatile components evaporated from the liquid, g) a liquid outlet from the containment for evacuating a residual portion of the liquid, h) a liquid distributor means within each segment for inducing liquid deposited on the central region of the first support surface to flow radially outward from the central region, i) a liquid gathering means for the second surface to draw liquid towards the central region of the second support surface, and j) a thermal control source positioned within at least some of the segments for heating or cooling the liquid passing over the second surface.

31. An apparatus as in claim 30 wherein the thermal control source is positioned between the first and second surfaces within the segments for heating or cooling the liquid passing over the second surface.

32. An apparatus as in claim 30 wherein the thermal control source comprises electrically insulated electrical resistance wires in thermal connection with the second support surface.

33. An apparatus as in claim 31 wherein the thermal control source comprises tubing in thermal connection with the second support surface for carrying a heat transfer fluid to either heat or cool the second surface and liquid flowing thereon, when present.

34. An apparatus as in any one of claim 30, 31, 32 or 33 comprising: a) a temperature sensor positioned within at least some of the segments having a thermal control source to detect the temperature of the liquid, when present, as it passes through the segment, and b) a temperature controller coupled to the temperature sensor and connected for controlling the rate of delivery of heat transfer by the thermal source to such segments.

35. An apparatus as claim 34 wherein the controller operates to transfer a differing quantity of heat to at least one segment than to another segment in the column.

36. An apparatus as claim 34 wherein the controller operates to deliver greater heat to lower segments in the column to raise the temperature therein.

37. A process of using the apparatus of claim 34 wherein, by sensing the temperature of the liquid in at least two segments of the column while the liquid proceeds through the column the controller controls the rate of transfer of heat to or from the second surfaces of such segments to provide heat flow at different rates to the respective segments.

38. An apparatus as in claim 30 wherein within at least some of the segments the liquid distributor means comprises a rotatable central shaft having a central axis connected to the first support surface for rotating the first support surface within the containment and thereby inducing radial flow of the liquid when deposited thereon,

39. An apparatus as claim 38 wherein each segment comprises: a) the first support surface being in the form of a spinable disc with a circumferential perimeter, the discs in the respective segments being mounted on the rotatable central shaft, and b) the peripheral receiving surface and transfer passageway include an upright circumferential liquid catching sidewall connected to and serving as an upright sidewall for the second surface and serving to deliver liquid to the second support surface.

40. An apparatus as in claim 38 or 39 wherein in at least some of the segments of the first support surface are perforated to allow fluid to pass there through and travel radially outwardly on the underside of such first support surface while being held in place by surface tension.

41. An apparatus as in claim 38 or 39 wherein in at least some of the segments the first support surface comprises a screen portion that is permeable to permit liquid to pass there through and travel radially outwardly on the underside of such surface while being held in place by surface tension.

42. An apparatus as in claim 41 wherein the first support surface is conically shaped and oriented to be opening upwardly so as to bias liquid to pass through the screen for outward travel on the underside of such surface.

43. An apparatus as in claim 30 wherein within at least some of the segments the liquid distributor means comprises a wiping blade mounted on a central rotating shaft having a central axis for rotating the wiping blade to sweep over the first support surface and induce outward radial flow of the liquid when deposited thereon.

44. An apparatus as in claim 30 wherein within at least some of the segments the liquid distributor means comprises a wiping blade mounted on a central rotating shaft having a central axis for rotating the wiping blade to sweep over the second support surface and induce inward radial flow of the liquid when deposited thereon.

45. An apparatus as in claim 38 wherein within at least some of the segments the liquid distributor means comprises a wiping blade mounted on the central rotating shaft for rotating the wiping blade to sweep over the second support surface and induce inward radial flow of the liquid when deposited thereon.

46. An apparatus as in claim 45 wherein the wiping blade is mounted on the central rotating shaft through a speed reducing connector.

47. An apparatus as any one of claim 44, 45 or 46 wherein the portions of the second support surface conveying the liquid towards its central region are downwardly inclined and generally conically formed to induce the inward radial flow of the liquid, when present, over the second support surface towards the central area of the second support surface.

48. An apparatus as in claim 30 in combination with a gas evacuation pump connected through the gas outlet to maintain the pressure controlled environment within the containment at a sub atmospheric pressure level.

49. An apparatus as in claim 30 wherein the containment comprises a gas inlet for injecting reaction gas or sweep gas into the containment.

50. An apparatus as in claim 30 wherein the containment comprises a liquid level sensor positioned to detect the level of liquid accumulated within the containment in combination with a liquid level controller connected thereto and further operatively connected to a liquid extraction pump for intermittent removal of liquid from the containment in accordance with the status of the liquid level in the containment.

Description

SUMMARY OF THE FIGURES

[0102] FIG. 1 is a schematic cross-sectional view through a nano-membrane over which is flowing in cross-flow a feedstock which provides a permeate that passes through the membrane. This figure is intended only as a conceptual introduction and is marked as Prior Art.

[0103] FIG. 2 is a schematic cross-sectional depiction of the layout of a pressure vessel and external supporting components, indicating the flow of feedstock through multiple chambers divided by separator plates in the context of a used oil recycling operation. Membrane support panels in FIG. 2 are depicted schematically as lines for clarity of depiction.

[0104] FIG. 3 is a face view of a basic membrane panel with its individual frame assembly.

[0105] FIG. 3A is a cross-sectional side view through FIG. 3.

[0106] FIG. 4 is a cross-sectional schematic view of a stack of membrane panel assemblies of the type as in FIG. 3 in an expanded state before compression to form a pressure vessel.

[0107] FIG. 5 shows a further schematic exploded cross-sectional view of a stack of membrane panel assemblies as in FIGS. 3-4 showing the flow of feedstock and permeate. In this figure the feedstock follows a parallel path over the membrane surfaces of two membrane panel assemblies before being recirculated. Details of the permeate manifold and exit passageways are shown in FIG. 8.

[0108] FIG. 6 is a schematic exploded cross-sectional view of a bank of four stacks of membrane panel assemblies as in FIGS. 3-5 with permeate manifold passageways top and bottom.

[0109] FIG. 7 is a further view as in FIG. 6 having additionally present pressure boosters in the form of multiple turbine blades mounted on a common shaft within the respective flow-through openings of two of the separator plates.

[0110] FIG. 8 is a face view of a separator plate showing the permeate collection structure.

[0111] FIG. 8A is cross-sectional edge view of FIG. 8.

[0112] FIG. 8B is a further cross-sectional view of FIG. 8 showing a mirror image arrangement of the permeate collection structure of FIG. 8.

[0113] FIG. 9 is a face view of a modified separator plate having a perforated membrane support panel on one side.

[0114] FIG. 9A is cross-sectional edge view of FIG. 8.

[0115] FIG. 10 depicts a side schematic view of a knocking filter for removal of solid and semi-solid grease particles and solids that are larger than the mesh rating of the filter screen from a feedstock.

[0116] FIG. 11 is a perspective bottom end view of the resiliently mountable frame and screen portion of the apparatus of FIG. 1 depicting two support grids for supporting the filter screen, the frame also carrying the knocking anvil.

[0117] FIG. 11A is a cross-sectional side view through FIG. 11.

[0118] FIG. 12 is a side view of the apparatus of FIG. 10 showing the actuator mechanism that delivers the knocking action through a hammer and anvil arrangement.

[0119] FIG. 13 is a schematic depiction of a first basic flash evaporator for processing oil using spinning discs showing three segments of a column of segments and external support components.

[0120] FIG. 14 is a schematic variant of FIG. 13 having four segments in column format and two different modes of heating.

[0121] FIG. 15 is a further schematic variant of FIG. 13 showing three segments with three liquid distribution arrangements, spinning and wiping and a combination, and a fourth segment with various heating arrangements.

[0122] FIG. 16 shows a diagrammatic perspective view of an insulated electrical heating wire wrapped in a crimped tube.

[0123] FIG. 17 depicts a spinning disc with perforations to allow liquid to pass there through and travel radially outwardly on the underside surface.

[0124] FIG. 18 depicts a spinning disc with a screen portion that is permeable to permit liquid to pass there through and travel radially outwardly on the underside of such surface.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0125] In FIG. 1 a pressure containment vessel 10 contains feedstock 11 flowing under pressure 12 from an inlet 13 to an outlet 14 where it exits as a concentrate 15 depleted of permeate 25. Inside the vessel 10 a membrane 20 is carried by a permeable, e.g. perforated, support 22 shown schematically as wire mesh 22 but in a preferred variant is a perforated metal panel. The membrane 20 has a skin 23 and a spongy sub-layer 24. Permeate 25 that has passed through the membrane 20 into a permeate collection cavity 26 exits through a permeate outlet 27. The membrane 20 may be cast onto a supporting scrim or carrier sheet (not shown) to give it improved dimensional stability.

[0126] The cavity 26 may contain a permeable cavity propping structure 61 (shown in FIG. 5) to minimize deflection of the support 22. This can optionally be in the form of a further wire mesh that occupies the cavity 26 and supports the membrane support 22.

[0127] Membranes suitable for use with the invention in a used lubricating oil application are believed to be available from:

[0128] Koch Membrane Systems, Inc.

850 Main Street

Wilmington, Mass.

[0129] 01887-3388

USA

[0130] EMD Millipore Corporation

290 Concord Road

Billerica

Massachusetts 01821

United States of America

[0131] U.S. Pat. No. 4,818,088 also describes a nano-membrane for use with aliphatic hydrocarbon liquids suitable for incorporation into the invention described herein in such application.

Filtration System Layout

[0132] In FIG. 2 a holding tank 30 contains a supply of appropriately pre-treated feedstock 11. A heater 29 adjusts the temperature of the feedstock 11 in the tank 30 to preferably around 90 C., e.g. 80-110 C. in the lube oil application. Feedstock 11 is then delivered by a feedstock delivery and pressurizing pump 32 to a loop system 33 that extends through a containment vessel 35 bounded by end plates 38. The feedstock 11 within the loop system 33 is circulated and kept pressurized by a circulating pump 34 until the desired amount of permeate has been extracted.

[0133] Feedstock 11 enters the containment vessel 35 bounded by end plates 38 at an inlet 13. This inlet 13 is fitted with an inlet diffuser 42 to distribute the flow amongst the membrane panel assemblies 41 within the containment vessel 35. Initially the hot feedstock 11 heats the apparatus while being circulated at low speed. Then the circulation rate and pressure within the loop 33 can be increased to process the feedstock 11 more rapidly.

[0134] The containment vessel 35 includes a series of individual membrane panel assemblies 41 (depicted schematically as lines 41 in FIG. 2) around which the feedstock 11 passes in a serpentine flow path 37. In this schematic figure, four stacks 45 of membrane panel assemblies 41 are depicted as being exposed to liquid flow. Each stack 45 is separated from adjacent stacks 45 by a pressure-supporting separator plate 46. Aligned with the passageways 50 (in FIG. 3) in the membrane panel assemblies 41 are flow-through openings 68 (in FIG. 3A) in the separator plates 46 allowing the feedstock 11 to pass from stack 45 to stack 45.

[0135] At the outlet collector 42 partially concentrated feedstock 11A exits from containment 35 to flow around the loop 33. Eventually a loop outlet pump 43 extracts more fully depleted concentrate 15 from the loop 33 through a back-pressure control valve 43 for delivery to a processed-concentrate holding tank 44.

[0136] As shown in FIG. 3 a membrane panel assembly 41 has two perforated panels 47 for supporting respective membranes 20 (not shown in this figure) on their outside surfaces. The perforations 48 optionally terminate before reaching the ends of the assembly 41. Circular passageways 50, shown as an exemplary three at each end, penetrate the two panels 47 near their respective ends where the panels 47 are preferentially pressed into contact with each other. Clamping circular sealing rings 54 bound the passageways 50 ensuring the integrity of the collection cavity 26 (in FIG. 3A) between the two panels 47. Permeate conduits 58 along the panel perimeter at the collapsed ends allow permeate 25 to flow from the collection cavity 26 along the periphery of the panel-pair 47 (in FIG. 3A) to exit through permeate outlets 27 at one or more of the ends of the panels 47 and into permeate manifold 27A.

[0137] As best shown in FIG. 3A, pinched between the two panels 47 along their outer peripheries is a stiffening frame 52, preferably of welded steel and of rectangular cross-section. This frame 52 stiffens the panels 47. The frame 52 also acts as a spacer between panels 47 and provides part of the wall of the containment vessel 35. The outer edges of a membrane 20 (not shown in FIG. 3 but shown as a line in FIG. 3A) on each panel's 47 outer boundary is also pinched between panels 47 and frames 52 under the compressive force of exterior bolts 56 when everything is assembled. Such bolts 56 (in FIG. 4) extend between the end plates 38 around the periphery of the containment vessel 35.

[0138] In FIG. 3A the membrane 20 is pinched around the passageway 50 by the sealing rings 54. The inside cavity 26 receives permeate from the feedstock 11. This pinching seal may be enhanced by the use of a gasket (not shown) which will not only isolate the inner permeate collection cavity 26 from the feedstock flow 11 but will also help pinch the membrane 20 in place under the sealing ring 54.

[0139] Permeate conduits 58 can run adjacent to the inner portion of the frame 52 to carry permeate 25 to the ends of the membrane panel assemblies 41.

[0140] In FIG. 4 a single stack 45 of individual membrane panel assemblies 41 is located within the containment of the pair of end plates 38 held together by bolts 56. Collectively, these end plates 38 and the peripheries of the membrane panel assemblies 41 define the containment vessel 35.

[0141] Individual panel assemblies 41 have passageway openings 50, also shown in plan view in FIG. 3, to allow parallel flow of feedstock 11 to be distributed in the spaces or gaps 53 between panel assemblies 41. These gaps 53 provide a headspace for feedstock over the membrane 20. Conveniently, in FIGS. 4-7 these passageway openings 50 are shown as aligned openings in the panel assemblies 41 to accommodate a feature described further below.

[0142] The height of the headspace provided by the gaps 53 has an important effect on the operation of the system. As this headspace 53 gets narrower, the pressure drop along a given length of membrane 20 will increase. If higher feedstock pressures are used, then, for a given gap height 53, the feedstock 11 flow rate will be higher. This flow rate will help scrub non-passing feedstock matter off the surface of the membrane 20, reducing membrane blockage. At the same time, such over-pressure can affect concentration polarization on the surface of the membrane. This has the consequence of thickening the boundary layer of fluid flow over the membrane, which will reduce permeate flow. For this reason trans-membrane pressure should not be allowed to become excessive.

[0143] FIG. 5 shows the path of flow of feedstock 11 and permeate 25 in between and around a pair of panel assemblies 41. Also as shown in FIG. 5, the cavity 26 contains a permeable cavity propping structure 61 to minimize deflection of the panel 47.

[0144] In FIG. 5 permeate 25 is shown as flowing through the permeate outlet 27 penetrating the frame 52 at the upper end of the individual panel assemblies 41. The permeate 25 is gathered through tabs 57 into a manifold 27A of tubes for eventual further disposal as shown in FIG. 8.

[0145] Permeate 25 exiting from each stack 45 of panels eventually passes through a back-pressure control valve 71 that is adjusted to maintain the pressure drop across the membrane 20 in the associated stack 45 of panel assemblies 41.

Serpentine Flow

[0146] In FIG. 6 multiple sets or stacks 45 of panel assemblies 41 are assembled to permit direction-reversing flow of feedstock 11 through consecutive stacks 45. As in FIGS. 4-6, end plates 38 of the containment vessel 35 are shown but, for convenience of depiction, the membrane panel assemblies 41 are shown as being separated before the bolts 56 apply a compacting force. In actual use, the bolts 56 are tightened with the frames 52 dimensioned at the boundaries of the panel assemblies 41 to allow the bolts 56 to draw the panel assembly ends together. This action also secures the membrane 20 in position on the pair of associated panel assemblies 41, pinching these components together while providing the spacing between panels that establishes the inter-panel gap and headspace 53.

[0147] In FIG. 6 separator plates 46 are present between consecutive stacks 45 of membrane panel assemblies 41. As shown in FIG. 8 the perimeter 72 of a separator plate 46 is shaped and dimensioned similarly to that of the membrane panel support assemblies 41 to ensure the integrity of the pressure containment volume 35. Within this perimeter 72 the face surfaces 73 of the separator plates 46, as with the end plates 35, may be slightly inwardly displaced to provide headspace 53 for the membrane 20 on adjacent panel assemblies 41.

Pressure Boost

[0148] In FIG. 7 the flow-through openings 68 in the separator plates 46 are penetrated by a rotating shaft 64 passing there through. Mounted on such shaft 64 in the flow-through opening 68 in every second separator plate 46 is a pressure booster 65 in the form of a fluid impeller. The seal 69 where the shaft 64 pierces the intermediate separator plate 46 is intended to be pressure-tight.

[0149] The shaft 64 is turned through a transmission 67 by an external electric motor 66. Thus, as the feedstock 11 passes from stack 45 to stack 45 in the bank of stacks, its pressure is boosted, making-up for the pressure loss incurred by flowing in a cross-flow over the surface of the membranes 20. The motor 66 may be a variable speed motor to control the amount of the pressure boost. Although a common shaft 64 is shown as actuating the pressure boosters 65, each pressure booster 65 could have its own individual electric motor.

[0150] As depicted in some of the Figures so far for the individual membrane support panel assemblies 41 and separator plates 46, reference has been made to an opening, (in the form of a passageway 50 (in FIG. 4) or flow-through opening 68 (in FIG. 7)), respectively formed therein near their ends. In fact multiple such openings 50, 68 may be present side by side to support a high flow rate through such openings 50, 68. Singly or collectively such openings qualify as a passageway 50 or a flow-through opening 68. In the case of multiple openings, multiple pressure boosters 65 should occupy the openings to maintain the pressure boost.

[0151] In FIG. 7 the multiple impellers 65 are positioned at the bottom of the first and third, and in expanded variants, in all odd numbered separator plates 46. The second separator plate and all even numbered separator plates 46 each have a penetration with a pressure-tight bearing 69 for the shaft 64, or multiple shafts 64 in the case of multiple openings 50, 68.

[0152] In configurations where the pressure drop within the flow of feedstock 11 is significant, e.g. the length of cross-flow along the membranes 20 in one or more stacks 45 is considerably extended or the feedstock 11 is viscous as in the case of heavy oil, a second set of pressure boosters 65 may be installed at the other end of the separator plate 46. Thus further multiple impellers 65 may be positioned at the top of the second, fourth and all even numbered separator plates 46. In this separate array of pressure boosters 65, all odd numbered separator plates 46 would have appropriately aligned pressure-tight bearings 69. This second shaft, or set of shafts, would have its own drive mechanism 66, 67 and speed control. For such long panels, the unit could beneficially be positioned on its side.

Trans-Membrane Pressure Control

[0153] To dispose of permeate 25 each stack 45 is provided with a first permeate outlet manifold 27A (in FIG. 5) that delivers permeate 25 to a proximate separator plate 46. As shown in FIG. 8 such plates have aligned permeate reception tabs 90, 91 corresponding to tabs 57 in FIGS. 3 and 5 and blind recesses 92 (in FIGS. 8A and 8B) that receive the permeate manifold 27A and divert permeate 25 out of the pressure containment vessel 35 through permeate pressure control valves 71. Thereafter permeate 25 flows at near atmospheric pressure for accumulation outside the pressure vessel 10. Only one permeate reception tab 90 is needed for a separator plate 46 but by providing two such tabs 90, 91 as mirror arrangements the separator plates 46 can be more versatile, avoiding the need to have left and right plates 46 on assembly. Each plate 46 can thereby receive permeate 25 from the stacks 45 on both or either side.

[0154] By providing each back-pressure valve 71 (in FIGS. 8, 8A, and 8B) with a pressure sensor 84 and individual valve controller (not shown), the controller can receive signals from the sensor 84 and deliver signals to control the valve 71. This allows different back pressures to be established for various stacks 45 through which the feedstock 11 is passing at progressively decreasing feedstock pressures 12 if there is no inter-stack pressure boost. The pressure of the feedstock 11 around each stack 45 can be interpolated by knowing the inlet 13 and outlet 14 pressures in order set back-pressure valves 71 to create the preferred trans-membrane pressure differential.

[0155] Drain tabs 93 (in FIGS. 8, 8A, and 8B) at the other end of the separator plate 46 can be fitted with manual valves 82 for use when permeate 25 is to be drained from the panel assemblies 41 on disassembly.

[0156] The permeate back-pressure control system as described is suitable for providing a preferred trans-membrane pressure when feedstock 11 is delivered to the containment vessel inlet 13 at a significantly elevated inlet pressure level 12. The consecutive pressure-boosting provisions for the individual consecutive stacks 45 described previously as part of this invention can obviate the need to deliver feedstock 11 to the container inlet 13 at an elevated inlet pressure 12. Nevertheless, in order to maintain trans-membrane pressures at reasonable values in either such cases, the permeate back-pressure control system as described can be used to set or fine-tune the trans-membrane pressure for individual stacks by adjusting the pressure of the associated membrane collection cavities 26.

Hybrid Separator Plate

[0157] The separator plate 46 need not be an independent component. FIGS. 9, 9A show a hybrid separator plate 46A and single membrane support panel 47. A perforated metal panel 47 is mounted on a modified separator plate 46A. Permeate 25 flows directly to the blind recess 92 through the permeate conduit pathway 58 in the modified separator plate 46A. The hole 50 in panel 47 is ringed by a modified sealing ring 54A that engages flow-through opening 68 in the modified separator plate 46A. This modified ring 54A and a shaped portion 52A of the plate 46A configured as a frame 52 position the membrane 20 in place. The modified separator plate 46A has a perimeter on one side, shaft penetration 61 and pressure seal 69 as before.

[0158] In this variant the lightly built perforated metal panel 47 is supported and stiffened by the pressure-sustaining modified separation plate 46A providing effectively a stiffened membrane panel support assembly 41 with a separator plate 46 embedded therein. If desired the modified separator plate 46A may also be perforated although this may prove costly for a thickened plate.

Number of Panels in Each Stack

[0159] As the feedstock 11 passes through a series of stacks 45, its pressure will be progressively reduced. At the same time, a portion of its volume will be carried-away in the permeate 25 that passes through the membranes 20. This loss of volume, after a number of stacks 45 have been passed-through will reduce the rate of feedstock 11 flow across membrane 20 surfaces.

[0160] To maintain the cross-flow fluid velocity at a desired level, the number of membrane support panels 41 in later stacks 45 in the series can be reduced. Thus, for example, where the initial stack count includes twenty membrane panels, then after, say, ten stacks in the series, the twenty first stack may have its panel count reduced to nineteen. This process can be repeated if the number of stacks in the series is extended substantially. The values in the example given will vary with the viscosity of the feedstock 11, the length of panel assemblies 41, the number of stacks in the system and other parameters.

Mounting of Membrane Support Panels

[0161] When finally assembled, the membrane support panels 41 and separator plates 46 which provide a portion of the boundaries of the pressure containment vessel 35 are held rigidly in place by the compressive force of the end plates 38 that are drawn towards each other by tightening the peripheral arrangement of bolts 56. This compressive force is high and the integrity of the arrangement once assembled is secure.

[0162] During initial assembly, temporary rails may be provided between the two end plates 38 to align individual panels being positioned there between in respect of their vertical position. Spacers located alongside side bolts 56 can ensure proper alignment in the horizontal direction.

[0163] In most applications where a pure base stock is required for producing fresh lubricating oil, the permeate 25 may be subject to a final treatment by passing it through a commercially available Polishing Unit that relies on activated clays. It is not represented that the output from the filtration system as describe is absolutely ready for use as a base stock for preparing lubricating oil.

[0164] While the above description has focused on an apparatus for recovering base lube oil stock from used lubricating oil, the invention and the apparatus hereinafter claimed is equally applicable to any suitable liquid filtration process that relies on a membrane as the filtering medium.

Knocking Filter

[0165] In FIG. 10 a supported screen frame 108 is carried by resilient supports 111 such as rubber posts or coiled springs that are seated on a stationary support structure 107. The resilient supports 111 serve as a return displacement mechanism for causing the assembly of supported components to thereafter return to its original location. While the resilient supports 111 described hereafter carry the weight of the supported assembly, an arrangement based upon sliding rails to carry the weight of the assembly and separate springs to restore the assembly to its starting location would perform equivalently, and would be understood to also constitute a resilient support.

[0166] The resilient supports 111 may be in tension or compression but their base ends 113 are anchored to the stationary support structure 107. The opposite ends 114 of the supports 111 are optionally connected to the screen frame 108 through couplings 115 that allow rotation. The function of these resilient supports 111 is to allow the screen frame 108 and its contents to be displaced as part of the knocking action, and then return the screen frame 108 with its contents to substantially return to its original position prior to a subsequent cycle.

[0167] In FIG. 11 the screen frame 108, preferably made of powder painted steel angle iron or channel, supports and carries multiple layers of steel wire support grids 134 (two only support grids only are shown in FIGS. 11 and 11A). These grids may typically have respective square openings of 2 inches, inch, and 30 mesh or 0.0232 inches. The filtration screen 123 rests upon the finest mesh support grid 134.

[0168] The resilient supports 111, screen frame 108 and inner grids 134 are positioned to orient the screen 123 at a flow-supporting upwardly inclined angle, e.g. between 5 and 20 degrees to the horizontal for a lube oil feedstock. This angle is preferably adjustable by a tilt control actuator 140 to control residence time for the feedstock on the screen 123.

[0169] In FIG. 12 a supply source feed pump 100 delivers feedstock 103 through the feed pipe 102 to a diffuser 106 for deposit onto the upper end of the screen frame 108. The feedstock 103 then flows under gravity down the inclined filter screen 123, towards the base end 128 of the screen frame 108. In the treatment of used lube oil that has previously gone through a settling stage, the length of the screen 123 can be chosen to allow 90% or moreup to 98-99%of the potential permeate to penetrate the screen 123. Appropriate dimensions for the screen 123 that have been found effective are approximately 1 m in length and m in width. Beneath the screen 123 a catching surface 120 gathers permeate for delivery through drain 124 to a permeate catching container 134 for capturing the permeate passing through the screen 123. A permeate recovery pump 139 empties the permeate catching container 134.

[0170] Upon reaching the base end 128 of the screen frame 108 the residual portion of the feedstock 103 passes off of the filter screen 123 through conduit 140 into a sludge tank 130. A sludge pump 131 empties the sludge tank 130 periodically.

[0171] As seen in FIGS. 11, 11A and 12 a yoke 112 spanning between the two lateral sides of the screen frame 123 has an anvil 110 positioned centrally there between. The yoke 112 and anvil 110, respectively, are preferably approximately mounted along the 2 vertical planes of reference passing through the center of mass of the components carried by the resilient supports 111. The yoke 112 is therefore approximately aligned transversely with the vertical plane crossing the width of the supported assembly of components, and the anvil 110 is aligned with the vertical plane that includes the longitudinal centerline of the screen frame 108.

[0172] FIG. 12 shows the detail of the actuation system that creates the knocking effect by applying a rapid onset of acceleration to the assembly of supported components. This is the action that assists in dislodging non-penetrating particulate material resting on the screen 123.

[0173] A motor (not shown) turns a plate 117 with an off-centered pin 119 that serves as a crank handle. Linked to the crank handle pin 119 is a connecting rod 116 and short link 116A. The connecting rod 116 may optionally be constrained by linear bearings (not shown). At the end of the connecting rod 116 is a hooked end 114 which serves as a hammer 114 for striking the anvil 110. The connecting rod 116, link 116A and hooked end 114 are preferably dimensioned and positioned so as to cause the hammer 114 to strike the anvil 110 when the crank handle pin 119 is moving fastest in its rotary cycle. The link 116A effectively creates slop in the connecting rod 116, link 116A connection to the crank handle pin 119. Once set in motion by the fastest pulling effect from the crank handle pin 119, these links and the hammer can continue in motion for a short moment thereafter, long enough for the hammer 114 to strike the anvil 110, while the erstwhile pulling effect from the crank handle pin 119 declines due to its rotary motion.

[0174] This slop is also present when the hammer 114 is forced to retire from the anvil-hitting location. The hammer 114 may even bounce-back slightly on hitting the anvil 110. Effectively, the hammer 114 is thrown intermittently in both directions. The related components are dimensioned and positioned to provide the regular knocking effect for the system.

[0175] Blows are preferably struck by the hammer 114 to the anvil 110 at intervals sufficient to ensure that the supported assembly of components has largely come to rest, although this is not essential. The direction of the blow struck by the hammer 114 need not be precise. The anvil 110 and supported assembly of components will move in the direction constrained by the resilient supports 111.

[0176] The actuation system of FIG. 12 may be replaced by an electrically driven solenoid mounted on the stationary support structure 107 of the assembly. Electrical impulses supplied to the solenoid from an electrical current generator are preferably synchronized to cause the solenoid shaft to strike anvil 110 once it comes substantially to its rest position. The restoring force based upon the spring constant of the resilient supports 111 and the damping factor inherent in such supports 111 can be selected to allow the solenoid to strike the anvil 110 as often as the frame 108 comes to rest.

Vapour Removal

[0177] In FIG. 13 containment 210 is in the form of flanged pressure tank 210 of a size suitable to accommodate the required number of segments 220 for the system flow rate.

[0178] This containment 210 has at least a liquid inlet 211 for introducing liquid 212 into the containment 210, a liquid outlet 273 for evacuating a residual portion 212A of the liquid 212, and a gas outlet 215 on the containment 210 for introducing or evacuating gases 216 present therein or extracting volatile components 216 evaporated from the liquid 212. A vacuum line 260 connected to the gas and vapor outlet 215 evacuates the pressure tank 210 gaseous contents to a condenser 254.

[0179] The containment 210 is preferably wrapped with an external heater (not shown) and thermal insulation (not shown) to maintain internal heat and prevent condensation on the inside surfaces.

[0180] If a sweeping gas were desired then CO.sub.2, N.sub.2 or other appropriate gas 270 or mixed gas stream could be introduced through gas inlet 219 to assist in sweeping out gases 216 and vapors through gas outlet 215. Entrained vapors may be collected in an externally located condenser 254 for removal as liquid through the positive displacementPD pump 255 that is isolated from the vacuum environment by a normally closedNC solenoid vapor valve 256. The sweep gas 270 may be vented or reused if of sufficient purity.

[0181] Within the containment 210 is a segmented, vertical cascade of support surfaces 221, 222 positioned in the form of a column 219 of segments 220. FIG. 13 shows two segments. FIG. 214 shows 4 segments of differing types. Any number of segments 220 can be used. A convenient number has been found to be 10-12.

[0182] As shown in FIG. 13, in the first segment 220 the liquid 212 being treated is poured constantly onto the central region 223 of the first support surface 221 by a supply tube 272 connected to the liquid inlet 211 of the containment 210 vessel. Metering valves (not shown) control the rate of flow of the liquid 212. The liquid 212 being processed passes progressively downwardly from segments to segment within the column 219. In each subsequent segment 220 the first support surface 221 is positioned to receive the liquid 212 from the prior segment 220.

[0183] Once deposited on the upper support surface 221 of a segment 220 the liquid 212 flows radially outward from the central region 223 to and beyond the periphery of the first support surface 221. This advantageously forms an expanding film as the liquid 212 proceeds outwardly.

[0184] Each segment 220 is also provided with a peripheral receiving surface 224 and transfer passageway 225 to transfer such liquid 212 leaving the first support surface 221 for deposition onto a second support surface 222 located below. The peripheral receiving surface 224 can be an internal cylinder 224 within the containment 210 that holds the second support surfaces 222 in place. Or it can be a rim on a second support surface 222 within each segment 220 to form a kind of stationary catch pan 226.

[0185] Liquid 212 deposited on the second support surface 222 undergoes inward radial flow towards the central area 227 of the second support surface 222. In one variant the liquid 212 is gathered by its conical shape or its flow may be caused by or assisted by assisted by a liquid gathering means 232 shown as an appropriately angled wiper blade 232. A central opening 230 in the central area 227 of the second support surface 222 is positioned to direct the liquid 212 onto the central region 223 of the first support surface 221 of the next consecutive segment 220.

[0186] In FIG. 13 the liquid distributor 231 that induces liquid 212 deposited on the central region 223 of the first support surface 221 to flow radially outward from the central region 223 is a spinning disc 245. As well, the liquid gathering means 232 for the second surface that draws liquid 212 towards the central area 227 of the second support surface 222 is its conical slope in one sample segment assisted by a wiper blade 232 as shown in another segment 220A.

Heater/Chiller Features

[0187] Additionally, a thermal control source 233 is positioned within at least some of the segments 220 for heating or cooling the liquid 212 passing over the second surface. In FIG. 13 electrical heating wires 234 lie on the underside of the catch pan 226. The thermal control source 233 can either heat or chill liquid 212 flowing over the second surface.

[0188] As shown in FIGS. 14 and 15 the thermal control source 233 can be positioned between the first and second surfaces within the segments 220 for heating or cooling the liquid 212 passing over the second surface 222. In the heating case the thermal control source 233 can be in the form of suitably insulated electrical resistance heating wires 234. In either the heating or cooling case the thermal control source 233 can be in the form of tubing 235 carrying a heating or cooling fluid 236 that, by radiation, conduction and/or convection, either heats or cools the second surface 222 and liquid 212 flowing thereon. Alternately, the thermal control source 233 can be located beneath the second surface 222 on its underside. In such case the tubing 235 or electrical wires 234 can in thermal connection with the second support surface 222 or catch pan 226 from below.

[0189] Either or both surfaces 221, 222 in a segment 220 may be heated or cooled as described above if they are both stationary. FIG. 15 shows dual stationary surfaces. Not every surface or segment 220 need be heated or cooled. But a sufficient number should be provided with a heat transfer to maintain an optimal reaction without risking denaturing of the liquid 212 by over-heating or quenching the reaction with over-cooling.

[0190] When heating for the catch pans 226 is provided by electrically insulated electrical resistance wires 234 thermally coupled to the underside surfaces of the catch pans 226, care should be taken that the wires 234 that are nowhere exposed to the vacuum as electrical leakage may occur through a vacuum. Electrical connections may be insulated by high temperature epoxy adhesive such as that provided by Cotronics Corp of Brooklyn, N.Y., USA 11232:

https://www.cotronics.com/vo/cotr/ea_ultratemp.htm Alternately such connections may be sealed in air-containing sleeves.

[0191] In order to improve the thermal connection between insulated electrical resistance wires 234 and the bottom surface of the catch pan 226 providing the second support surface 222, the catch pan 226 may be made of aluminum. Further, as shown in FIG. 16, the insulated electrical wires 234 (high temperature insulation) may be wrapped or enclosed in an aluminum sheet or tube 240 which is tightly crimped shut in order to provide a higher degree of physical contact between the outer insulation of the wires 234 and the aluminum tube 240. The wires 234 so contained in the crimped aluminum tube 240 may then be readily welded by aluminum welding to an aluminum catch pan 226 with appropriate aluminum filleting to improve thermal conductivity.

[0192] Optionally but preferably temperature sensors 241 are positioned within at least some of the segments 220 that have a thermal control source 233 present. The sensors 241 serve to detect the temperature of the liquid 212, when present, as it passes through the segment 220. A temperature controller 242 coupled to a typical temperature sensor 241 is also connected to the source of hot or cold fluid 236 or electricity for the thermal control source 233 and is configured for controlling the rate of delivery of heat transfer by the thermal source to or from the segments 220 so equipped.

[0193] Where conditions require, such as where the liquid 212 being processed is increasing in viscosity as it is being processed, the temperature controller 242 may be arranged to operate by transferring a differing quantity of heat to at least one segment 220 than to another segment 220 in the column 219. Thus in the example given greater heat can be transferred to one or more segments 220 to reduce an increase in viscosity of the liquid 212. Such segments 220 in the case of evaporation of volatiles are more likely to be located in the lower portion in the column 219. This controller 242 can be also be used to accommodate the heat effects of exothermal or endothermal reactions that may arise when a gas-liquid reaction is occurring.

Top Surface Liquid DistributingSpinning

[0194] In FIG. 13 a rotatable central shaft 243 having a central axis 214 runs through the column 219. This shaft 243 can be square for ease of engagement and is connected to the first support surface 221 for rotating the first support surface 221 within the containment 210. This will enhance the radial flow effect. The first support surface 221 in such case can be in the form of a spinable disc 245 with a circumferential perimeter, the discs 245 in the respective segments 220 being mounted on the same rotatable central shaft 243.

[0195] As shown in FIG. 14 an external motor 256 or internal magnetic drive mechanism (not shown) for shaft 243 supporting the discs 245 can turn the discs 245 at a convenient 120 rpm as the most advantageous speed for typical fluid viscosities. Use of a magnetic drive is preferable as this will remove the need for having inefficient and leaky shaft seals. When an external motor 256 is driving the shaft 243 a pump type gas-tight seal 273 can be employed where the shaft 243 enters the containment 210 vessel.

[0196] As shown in FIG. 17 in this spinning disc variant at least some of the segments 220 of the first support surface 221 can be provided with perforations 246 to allow liquid 212 to pass there through and travel radially outwardly on the underside of such first support surface 221 while being held in place by surface tension. The size of the openings provided by the perforations 246 is dimensioned to support this surface tension effect.

[0197] A similar effect can be achieved by providing or forming the first support surface 221 within such segments 220 with a screen portion 251, FIG. 18, that is permeable to permit liquid 212 to pass there through and travel radially outwardly on the underside of such surface. The screen portion 251 can be based upon a wire screen mesh or other woven or fibrous format that will serve as a permeable screen portion 251 and permit liquid 212 to pass there through. The screen 251 should be of a material and configuration that will cause the liquid 212 to cling to and flow over its underside surface through surface tension. In either arrangement the first support surface 221 can be conically shaped and oriented to be opening upwardly, or downward as shown in FIG. 15 so as to bias liquid 212 to pass through the screen 251 or holes 246 for outward travel on the underside of such surface.

Top & Bottom Surface Liquid DistributingWiping

[0198] As an alternate variant to the use of spinning discs the liquid distributor 231 for the first surface can be, as shown in FIG. 13, based upon a rotating wiping blade 252 mounted on a central rotating shaft 243 having a central axis 244. This shaft 243 serves to rotate the wiping blade 252 and sweep it over the first support surface 221, now fixed to the peripheral wall 224, thereby inducing outward radial flow of the liquid 212 when deposited thereon. The blade 252A can itself be fixed to the peripheral 224 wall and mounted over a spinning disc 245, as shown in FIG. 15, to further guide and direct liquid 212 flow.

[0199] Such a wiping blade 252 can be employed in a similar manner in respect of the second surface 222 as shown in FIG. 13. This arrangement for the second surface 222 can be employed whether the first surface 221 is spun or swept at least in respect of some or all of the segments 220 in the column 219. In such case a wiping blade 252 operates to support or induce inward radial flow of the liquid 212 when deposited thereon.

[0200] When the first surface 221 is being spun the wiping blade 252 can be mounted on the same central rotating shaft 243 that rotates the first surface, connected through a speed reducing connector 253. One suitable connector 253 can incorporate a sun-and-planet gear arrangement to achieve speed reduction. In this manner the upper surface can be spun at a higher speed while the lower surface can be wiped at rates suitable for the respective surfaces.

[0201] While for a given segment 220 the rotating wiper 252 of the first support surface 221 has been described as spreading liquid 212 outwardly and a second wiper 252 drawing liquid 212 inwardly on the second support surface 222, these may be reversed. Thus the rotating wiper 252 of the first support surface 221 can draw liquid 212 inwardly and the second wiper 252 spread the liquid 212 outwardly.

[0202] The second surface 222 need not be wiped at all. The presence of a liquid distributor 231 for the second surface can include a configuration where the portions of the second support surface 222 conveying the liquid 212 towards its central area 227 are downwardly inclined and generally conically formed to induce the inward radial flow of the liquid 212 over the second support surface 222 towards the central area 227 of the second support surface 222 under gravity. This constitutes one further example of a liquid gathering means 232.

[0203] Other parts include bottom residual oil exit outlet 273, external drain pump 262 and bottom liquid level sensor 263. The liquid level sensor 263 is positioned to detect the level of residual liquid 212A accumulated within the containment 210. The pump 262 effects intermittent removal of liquid 212 from the containment 210 in accordance with the status of the liquid level in the containment 210. This allows the bottom of the containment 210 to be intermittently purged of treated liquid 212A, protecting the drain pump 262 from being run in a dry condition.

[0204] In all variants liquid 212 may be passed through the system repeatedly until the desired chemical or physical reaction is complete.

[0205] A prototype based on this spinning disc configuration included features as follows: [0206] i. 1212 stationary pans 226 with attached 500W heaters 234 on their undersides and dished downwardly towards their center areas 227 had 2 diameter openings 230 in the catch pans 226 around the central shaft 243. These openings allow flow-through into the next segment 220 below. [0207] ii. Electric wires 234 serving as catch pan heaters were connected to the outside through connectors that isolate the wires 234 from the vacuum. [0208] iii. The temperature in the interior was regulated to around 65 C. via a thermocouple 241 in the upper section of the pressure vessel 210 and a controller 242 connected to both the thermocouple 241 and the heaters 234. The temperature of individual catch pans 226 can and preferably are specifically sensed by individual thermocouple sensors 241 and may be individually regulated. [0209] iv. The stationary pans 226 are supported by a rigid cylindrical frame 224 that sits on the bottom of the pressure vessel 210. [0210] v. Top 2 Vacuum line 260 was equipped with a packed Stainless Steel wool mist eliminator 264 that started at a 15 angle and then went horizontal to a sanitary fitting, proceeded through a 90 elbow and down to a tube in shell chilled (water cooled) condenser 254. [0211] vi. Condensate proceeded down through a T 265. One side of the T branched to a bottom vacuum line 268. The other side was directed down to a float activated gear pump 266 having a 100 ml/min. capacity with protecting N.C. solenoid, to a reservoir 267 for solvent/fuel recovery. Condensates such as glycol or hydrocarbons that can be used as fuel have value while water needs to be decontaminated of dissolved hydrocarbons for environmental disposal. [0212] vii. Volatile-depleted liquid 212A collected at the bottom of the containment 210 was pumped out of the chamber intermittently as required.

CONCLUSION

[0213] The foregoing has constituted a description of specific embodiments showing how the invention may be applied and put into use. These embodiments are only exemplary. The invention in its broadest, and more specific aspects, is further described and defined in the claims which now follow.

[0214] These claims, and the language used therein, are to be understood in terms of the variants of the invention which have been described. They are not to be restricted to such variants, but are to be read as covering the full scope of the invention as is implicit within the invention and the disclosure that has been provided herein.