U.S. patent application number 15/555535 was filed with the patent office on 2020-10-01 for used oil recycling and pretreatment filtration assembly.
This patent application is currently assigned to Mempore Corp. The applicant listed for this patent is Mempore Corp. Invention is credited to Liubomyr KUTOWY, Oleh KUTOWY.
Application Number | 20200306697 15/555535 |
Document ID | / |
Family ID | 1000004888785 |
Filed Date | 2020-10-01 |
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United States Patent
Application |
20200306697 |
Kind Code |
A1 |
KUTOWY; Oleh ; et
al. |
October 1, 2020 |
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.
Inventors: |
KUTOWY; Oleh; (North Gower,
CA) ; KUTOWY; Liubomyr; (Kemptville, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mempore Corp |
North Gower |
|
CA |
|
|
Assignee: |
Mempore Corp
North Gower
ON
|
Family ID: |
1000004888785 |
Appl. No.: |
15/555535 |
Filed: |
March 2, 2016 |
PCT Filed: |
March 2, 2016 |
PCT NO: |
PCT/CA2016/000058 |
371 Date: |
June 18, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14997143 |
Jan 15, 2016 |
9993775 |
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15555535 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 61/12 20130101;
B01D 2311/14 20130101; B01D 63/082 20130101; B01D 2319/022
20130101; B01D 2311/04 20130101; B01D 2313/08 20130101; B01D
2313/143 20130101; B01D 61/08 20130101; B01D 2311/06 20130101; B01D
2319/025 20130101; B01D 2313/18 20130101; B01D 2313/146 20130101;
B01D 61/027 20130101; B01D 2315/10 20130101 |
International
Class: |
B01D 63/08 20060101
B01D063/08; B01D 61/12 20060101 B01D061/12; B01D 61/08 20060101
B01D061/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 3, 2015 |
CA |
2883468 |
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
FIELD OF THE INVENTION
[0001] The invention relates to an apparatus for separating fluid
mixtures by filtration membranes which are arranged into membrane
stacks in a supporting frame. More specifically this invention
describes equipment and procedures using nano-filtration membranes
for cleaning used oil to bring it back to a starting base stock for
possible reuse. The invention also has applications in other fields
where a filtrate or permeate is to be extracted from a feedstock.
This includes, for example, dewatering food-containing liquids to
produce concentrates and the purification of gelatin to high
standards. Other applications include separating lighter
hydrocarbons from heavier hydrocarbons in the petroleum
industry.
[0002] Prior to membrane treatment the feed stock typically
requires pre-treatment to remove interfering impurities and
undesirable components.
[0003] This invention also describes equipment and procedures for
reacting a liquid with a gas, particularly in cases where the
liquid has to be progressively heated or cooled to sustain the
reaction. Particularly it addresses physical reactions whereby
volatile components are evaporated from a liquid. More generally
this invention addresses an apparatus and process based upon
processing a liquid through a stacked array of segments formed as a
column wherein a chemical or physical reaction and a heat transfer
process occur in consecutive stages.
[0004] "Vacuum" as used herein does not necessarily mean a high or
hard vacuum but includes below atmospheric absolute pressures that
are conducive to promoting vaporization. "Distilland" means the
liquid undergoing treatment in such application.
[0005] Other applications include the reaction of a gas with a
liquid by a chemical process which may be endothermic or exothermic
where providing multiple stages of heat transfer to the liquid is
conducive to sustaining the reaction.
[0006] As a further feature for pretreating feedstock this
invention describes equipment and procedures for filtering
particulates from a liquid or a flowable mass of larger particles.
More specifically, it is applicable to a stage in the processing of
used lubrication oil to recover a starting base stock for possible
reuse. The filter which is agitated by "knocking" in order to
improve its filtration performance.
BACKGROUND TO THE INVENTION
[0007] A useful technology for recovering usable base stock from
used lube oil can employ nano-filtration membranes. Colloquially, a
process based upon use of open osmosis membranes can be referred to
as "nano-filtration". However use of such membranes is
distinguishable from "filtration" in the following respects:
separation of fluids takes place at the membrane surface based on
attractions and repulsions of specific dissolved chemical moieties;
this is not a filtration of solid particles in the traditional
sense. This is instead analogous to reverse osmosis.
[0008] Accordingly, although the expressions "nano-filtration",
"micro-filtration", "ultra-filtration", "hyper-filtration",
"filtrate", "permeate", "filtering medium" may be used in the
course of this disclosure, these expressions are actually intended
to extend to the case where there is a separation of two a stream
into a permeate and a concentrate by any analogous process. The
invention is not limited to the use of a specific type of
membrane.
[0009] Lubricating (lube) oils consist of a starting base stock and
an additive package. The proportions vary by application and
supplier. In operation, the base stock generally remains unchanged
(unless overheated by a faulty engine to form some varnish) while
the additive package wears out in the process of doing its job to
prevent oxidation, level out viscosity, reduce wear and accommodate
combustion products. The base stock is, however, recoverable.
[0010] The inherent value of lube oil has led to many attempts at
reclaiming the base stock from used lubricating oil with varying
levels of success. One technique is to pass the used oil,
appropriately pre-conditioned, over a nano-filtration membrane.
[0011] Colloquially, a process based upon use of ultrafiltration
membranes can be referred to as "nano-filtration". However use of
such membranes is distinguishable from "filtration" in the
following respects: separation of fluids takes place at the
membrane surface based on attractions and repulsions of specific
chemical moieties; this is not a filtration of particles through
the membrane in the traditional sense; this is instead analogous to
reverse osmosis. Accordingly, although the expressions
"nano-filtration", "filtrate", "permeate", "filtering medium" may
be used in the course of this disclosure, these expressions are
actually intended to extend to the case where there is a separation
of two different fluid streams by any analogous process.
[0012] Attempts at using commercially available membrane
containment systems include the DDS (De Danske Sukkerfabrikker)
plate and frame equipment described in U.S. Pat. No. 3,872,015.
[0013] A previous patent to Kutowy et. al. U.S. Pat. No. 4,814,088
of Mar. 21, 1989 addresses a membrane-based ultrafiltration process
to clean mildly used lube oil as well as crude oil and other
chemicals. The contents of this and the following Kutowy US patents
are adopted herein by reference.
[0014] Other patents to Kutowy et. al., U.S. Pat. No. 5,002,667
Mar. 26, 1991, and U.S. Pat. No. 5,624,555, Apr. 29, 1997 describe
using a metallic plate and frame for membrane support. In
particular the latter patent describes a paired-membrane panel
assembly which incorporates two membranes each overlying a
respective perforated membrane support panel located adjacent to
the individual membrane's permeate or low pressure side. Such
paired membrane support panels are mounted in parallel exposing all
parallel membranes to feedstock flowing in the same direction.
[0015] Feedstock in a membrane system usually requires some
pre-treatment. Used lube oil becomes unfit for its purpose due to
physical contamination and chemical changes. Particles are present
as contaminants. Water and glycol exist in several forms in used
crankcase oil. It is desirable for such contaminants to be reduced
to a minimum before a feedstock is exposed to a nano-filtration
membrane.
[0016] The presence of water and glycol in particular poses a
problem to base stock reclamation through small pored membranes
such as nano-filtration membranes. This is because of the formation
of emulsions that tend to stick and block pores in membranes. Water
and glycol have to be virtually completely removed for a
nano-filtration membrane-based process to be most effective. Thus
the feedstock for a nano-membrane filter should be "membrane
compatible" and "feedstock" as used herein is so intended.
[0017] Use of nano-membrane filters gives rise to a number of
structural requirements for the membrane support structure.
[0018] In order to provide a useful quantity of permeate when
exposing liquid feedstock to a membrane, the membrane is normally
supported to carry a substantial trans-membrane pressure, e.g. on
the order of 100 psig. Further, passing a flow of feedstock as a
working fluid over a membrane surface under pressure is preferably
done in a confined space, e.g., a depth that is preferably only a
moderate multiple of the thickness of the membrane and/or the
membrane and its supporting perforated panel. This confined space
has a preferred depth to maximize the quantity of working fluid
that comes into contact with the membrane surface and to maintain
flow velocity. ("Fluid" as used herein refers to a liquid unless
the context indicates otherwise.) Establishing the correct flow
rate over a membrane helps keep the membrane surface clean.
[0019] As a consequence of this narrow confinement the working
fluid will suffer a pressure drop as it passes as a cross-flow
along the length of a membrane. Over a distance of, say, 2 meters
in length, the pressure drop could be on order of 10 psig for used
lubricating oil, depending on the depth and viscosity of the
flowing feedstock layer.
[0020] If the working fluid is to be exposed to an extended surface
area of membrane, e.g., past multiple supported membrane surfaces
connected in series, this cross-flow pressure loss will accumulate.
All along the membrane surfaces the pressure must be kept above a
minimum pressure, for example 100 psig, to sustain effective
permeation. Therefore the entry pressure of the working fluid as it
is exposed to the first membrane must, according to one solution,
be high enough to accommodate the subsequent pressure losses for
the flowing working fluid to maintain the minimum, e.g. 100 psig,
pressure needed to force permeate through the membrane at a
reasonable rate.
[0021] To contain high pressure fluid requires strong frames,
sealing plates and seals. Typically these are made of steel. As the
requirement for strength goes up (to accommodate higher pressures)
the weight of such supporting assemblies increases. This places
higher demands on the handling apparatus as well as imposing
increased cost.
[0022] It would therefore be desirable to provide a support
assembly for filter membranes having minimized weight and strength
requirements. Correspondingly, the input pressure of the working
fluid should be limited to the extent practically possible. This
invention addresses such objectives.
[0023] Used oil acquires or contains substantial particulates
generated during lube oil use. It is highly desirable for these
particulates to be removed to enable further processing of the lube
oil feedstock, particularly in the case where nano-filtration is to
be employed.
[0024] The constituents of used lube oil before treatment are: base
stock, some varnish (if the oil was overheated), water from cooling
systems or from other sources, glycol from cooling systems (due to
faulty seals or mixed-in during oil changes), suspended solids from
air, particles arising from wear in the engine, emulsions of oil in
water, emulsions of water in oil and dissolved species in the
additive package or from other sources. The solids can be denser
that the feedstock, or essentially the same density as the
feedstock and, to a lesser degree, lighter than the feedstock.
[0025] The first and last of the components can largely be removed
in a settling tank and optionally but preferably a centrifuging
treatment. This invention addresses separating the middle
category--similar density components--from used lubricating oil by
filtration prior to presentation of the permeate for further
treatment and presentation to a nano-filtration membrane. Examples
of particles in this category include lint that may have originated
from paper or rag material added to the feedstock in handling or
from deteriorating filters.
[0026] Thus this invention addresses the use of a
liquid-particulate filter as a stage in preparing used lube oil for
exposure to nano-filtration polymeric membranes. While described
with respect to this particular application, the invention relates
to any procedure by which particulates are to be separated from a
liquid or a flowable solid by using a filter screen.
[0027] Vacuum evaporation is a known technique for extracting
volatile components from a liquid. An example would be the removal
of water and glycol from used engine lubricating oil for purposes
of recycling the oil. Water and glycol exist in several forms in
used crankcase oil: water (with associated glycol) with oil
dissolved in it; water with an oil-in-water emulsion (where water
is the continuous phase); water and glycol in oil emulsion (where
oil is the continuous phase), and finally dissolved water and
glycol in oil.
[0028] While the extraction of glycol and water from used engine
oil is used as an example herein, the invention applies, inter
alia, to any case where a volatile component is to be removed from
a liquid employing the apparatus as described. Advantageous
applications include purifying used transmission, hydraulic and
transformer oil. Further applications arise, amongst others, in the
food industry where water or volatiles are to be evaporated from
products such as alcoholic beverages and fruit juices. The features
which are presented in respect to the purification of engine oil
herein are intended to be exemplary of what can be done in all such
fields.
[0029] In the process of vacuum evaporation a thin film of liquid
is exposed to a vacuum allowing for the release of a target
volatile component into the vacuum as a gas. As the process of
evaporation lowers the temperature of the liquid, it is appropriate
to reheat the liquid as it loses its volatile components, thus
maintaining the rate of evaporation. Reheating may also be relevant
to control the viscosity of the distilland. For example, as a
distilland loses diluent its viscosity may rise. This trend may be
resisted, at least in part, by appropriate reheating.
[0030] A key factor affecting the rate at which this process can be
advanced is the amount of surface area of the liquid exposed to a
vacuum. In falling film evaporators, the liquid is arranged to fall
in a thin sheet down a vertical surface within a vacuum containment
structure that provides heating to the liquid as it progressively
drops towards lower levels. In other arrangements, a thin film is
caused to flow across a support surface which is regularly wiped to
maintain the thinness and completeness of coverage of the surface
by the liquid being treated.
[0031] While reference has been made to the transfer of a gas out
of a liquid in a vacuum environment, the invention is equally
applicable in applications where a sweep gas is substituted for, or
used in conjunction with a low-pressure, below atmospheric
condition. When a sweep gas is employed, its pressure need not
necessarily be related to atmospheric pressure in a specific
manner.
[0032] It is known to evaporate volatiles from a liquid deposited
on a spinning disc: Spinning disk evaporator US 20050145474 A1;
also IRMH Processtech, Flanders FOOD Technology Day 2010,
http://www.flandersfood.com/sites/default/files/ct
bestand/10/10/21/5%20FFTD %20Henderson %
20[Compatibiliteitsmodus].pdf
[0033] However this design would involve complications if it were
desired to effect heating of a spinning disc.
[0034] It is also known to provide a column of rotating cones or
rotating discs to serve as a counter-current vapour-liquid
contacting device. A reference of this type is U.S. Pat. No.
4,995,945, issued Feb. 26, 1991 on an invention by Craig. Further
references in this genre include the prior references cited in this
patent and the subsequent references referring back to this patent,
including in particular, U.S. Pat. Nos. 6,379,735 and 6,287,681.
The present application adopts by reference and incorporates herein
all of the above disclosures. All of these references have, as an
object, the presentation of a large surface area over which a
gas-liquid, chemical or physical reaction may occur.
[0035] Reference is also made to US patent issued Mar. 7, 1995 to
Al-Hawaj et al entitled "Rotary Apparatus for combined multi
flashing and boiling liquids". In this reference the liquid is not
exposed for evaporation of the top surface of a spinning disc.
[0036] It would be advantageous to construct a gas-liquid reactor,
and more particularly a flash evaporator that exposes a large
surface area of liquid in the form of a thin film to a vacuum while
being compact in its overall relative dimensions. It would also be
convenient to provide a configuration wherein heating can be
provided to a distilland, or heat transfer effected for a reacting
liquid, while the liquid flows over a supporting surface that
provides, or is part of an apparatus that provides, the referenced
large surface area. It particular it would be desirable for the
heat transfer to or from a reaction to be adjusted and controlled
while the distilland or reacting liquid proceeds through the
system.
[0037] This invention addresses the use of a mechanical
configuration for supporting a liquid in a vacuum evaporation
system or gas reaction enclosure which allows for a more compact
design of the containment vessel combined with provision for
effecting heat transfer.
[0038] The invention in its general form will first be described,
and then its implementation in terms of specific embodiments will
be detailed with reference to the drawings following hereafter.
[0039] These embodiments are intended to demonstrate the principle
of the invention, and the manner of its implementation. The
invention in its broadest and more specific forms will then be
further described, and defined, in each of the individual claims
which conclude this Specification.
SUMMARY OF THE INVENTION
Membrane Separator
[0040] According to one variant, the invention addresses a
filtration system suitable for recovering base stock from used
lubricating oil by passing such feedstock over a nano-filtration
membrane surface. The invention may also be employed for processing
other feedstocks.
[0041] In order to produce permeate from a feedstock at least two,
i.e. multiple, membrane supports carry respectively membranes, each
support having a receiving space within to serve as a cavity for
accepting permeate driven through the membranes by pressure applied
to the feedstock, each support also having a permeate-receiving
cavity outlet to drain-off permeate. The multiple membrane supports
are mounted in a common pressure-containing vessel having feedstock
inlets and concentrate outlets. The pressure vessel contains at
least one pressure-sustaining separator plate positioned between at
least two adjacent membrane supports, the separator plate having a
flow-through opening at one end to allow fluid to flow from one
membrane support to the next.
[0042] The separator plates allow different pressures to develop in
consecutive chambers defined by the separator plate(s) that contain
the membrane supports, avoiding exposing the membrane supports to a
pressure differential that would otherwise arise due to a drop in
the pressure of the feedstock as it flows through the system.
[0043] The support panels are preferably formed from two permeable
panels mounted back-to-back with two respective membranes located
on their outer-facing surfaces. The two panels define between them
the receiving space to serve as the cavity for accepting permeate
driven through the two membranes. Collectively these components
constitute a "panel assembly". In normal usage the feedstock flows
in the same direction when passing over the two membranes carried
on the respective outer sides of a membrane support panel
assembly.
[0044] Optionally and preferably the respective permeable panels
are formed of thin material to reduce weight. Rolled steel sheeting
that has been pressed into shape and has been perforated over the
greater part of its surface to make it permeable has been found
suitable. Use of lightly built panel assemblies is complemented by
the structural integrity of the pressure-sustaining separator
plates.
[0045] While reference is made to the word "panel" this expression
is intended to include any form of support, such as a braced mesh,
that performs in a similar manner.
[0046] Preferably the panel assemblies are themselves assembled in
groups as a stack of panel assemblies, all membranes within the
stack experiencing parallel flow within the chamber defined by an
associated separator plate. On exiting a first stack of membranes,
the feedstock passes through an opening in one end of the separator
plate to flow past a second stack of membranes. In a preferred
arrangement the flow through the second stack is in the reverse
direction to the flow through the first stack, being located
adjacent to the first stack but separated therefrom by the
separator plate.
[0047] The stacks of membranes can all share a common pressure
containment vessel. A system can be arranged to rely upon the
serpentine flow of feedstock through multiple stacks of membranes
within that vessel. As a further feature of the invention pressure
boosters installed in the flow-through openings of separator plates
separating consecutive stacks can serve to restore lost pressure of
the feedstock and maintain effective permeation of permeate through
the membranes.
[0048] The two panels of a panel assembly define between them the
receiving space for accepting permeate driven through the two
membranes by outside pressure, e.g., 100 psig. This
permeate-receiving cavity, which serves as a permeate collection
chamber, has an outlet to drain-off permeate ensuring that the
membrane has a low or limited back-pressure. This cavity may
contain spacer members that function as a strut support to minimize
deflection of the panels. Collectively these components constitute
the membrane panel assembly.
[0049] This structure can be further incorporated into the
following useful configurations.
Multiple Membrane Panel Assemblies
[0050] Generally, a filtration assembly to produce a permeate from
a feedstock in accordance with the invention may comprise the
following features: [0051] a. multiple membrane panel assemblies
are mounted in a common pressure-containing outside vessel with the
panel assemblies arrayed in a parallel configuration. The feedstock
flows in the same direction on both sides of the panel assemblies
for the lengths of the multiple membrane panel assemblies.
Collectively the multiple membrane panel assemblies constitute the
"stack" of panel assemblies. [0052] b. at one entry end of the
stack all individual panel assemblies receive feedstock from an
inlet mounted on the pressure vessel. The distribution of the flow
of feedstock around individual panel assemblies is facilitated by
passageways within the pressure vessel that ensure relatively equal
distribution. These passageways may be in the form of sealed
penetrations through the membrane panel assemblies at their ends.
The sealing around such passageways confines permeate to the
permeate-receiving cavity. At another exit end of the stack,
feedstock exiting through similar openings after exposure to the
membranes of all panel assemblies in the stack is ultimately
delivered to an outlet mounted on the pressure vessel for transfer
to the next stage of processing.
[0053] This parallel arrangement reduces the net pressure drop
between the inlet and the outlet portions of the stack.
[0054] The permeate which penetrates through the membranes into the
respective individual permeate collection chambers exits through a
permeate outlet from each panel assembly into a manifold connected
to all such collection chambers in the stack. This manifold
collects and delivers the permeate from the filtration assembly to
an external storage vessel. The manifold may be built onto the
bordering portions of an assembly of frames into which individual
membrane panel pairs are mounted. The manifold may terminate at a
separator plate which provides an outlet to the external
environment.
[0055] To locate the panel assemblies within the pressure vessel,
each panel assembly can be constructed so that it is bounded by an
individual frame. The frames are then positioned side by side with
the perimeters of their respective membranes pinched there between.
The frames are then clamped tightly together by exterior bolts.
This provides a portion of the outer wall of the pressure vessel.
This assembly of the frames secures the membranes in place. The
thickness of these peripheral frames also determines the
inter-panel assembly spacing which defines the depth of feedstock
passing over the membrane surfaces.
Series Flow
[0056] A filtration assembly may contain more than a single stack
of parallel membrane panel assemblies. Such stacks can be arranged
in series to form a bank of such stacks.
[0057] Instead of each stack in a bank having its own pressure
vessel, they may all share a common pressure vessel, each
consecutive stack being separated from an adjacent stack of
membrane panel assemblies within the pressure vessel by a
pressure-supporting separator plate. Each separator plate has a
flow-through opening at one end to allow fluid to flow from one
stack of membrane panel assemblies to the next. This opening will
be proximate to the exit end of a first stack and positioned next
to the inlet end of the next stack. In this arrangement the
direction of feedstock flow is reversed in consecutive stacks.
[0058] By assembling a bank of at least two stacks of membrane
panel assemblies in this manner, a series flow of feedstock over
membrane surfaces in each stack may be achieved. The number of
stacks of membrane assemblies so connected may be increased along
with inclusion of further separator plates so long as the
trans-membrane pressure drop is sufficient to support adequate
filtration. Conveniently the feedstock may flow in a serpentine
manner through three or more stacks in a bank so configured.
Pressure Boosting
[0059] In the configuration as described there will be a cumulative
pressure loss for the working fluid as it passes along the length
of consecutive stacks of membranes within a bank. This would
normally require that a high pressure be maintained at the inlet to
the bank of filters. Operating containers at elevated pressures
have strength requirements and sealing problems that are
inconvenient to address.
[0060] Advantageously to address this problem, the separator plate
flow-through opening(s) may be provided with an inter-stack
pressure booster mechanism to restore lost pressure. This pressure
booster can be in the form of propeller or turbine-like blades or
other form of impeller that is mounted in the flow-through
opening(s) in one or more separator plates. Such openings may be
dimensioned to be close-fitting to the periphery of the impeller,
i.e. being circular, to support the pressure differential being
formed. The pressure boosters may be actuated by individual
electric motors or they may be mounted on one or more rotating
shafts that are driven from outside the pressure vessel.
[0061] In a case where a bank of membrane stacks contains three or
more stacks with the consecutive stacks separated by two or more
separator plates, multiple pressure boosters may be installed in
the flow-through openings in each of the respective separator
plates. However, consecutive separator plates need not necessarily
be so equipped. Optionally only every second separator plate may be
provided with a pressure booster at one end. This arrangement
facilitates mounting consecutive pressure boosters on a single,
shared rotating shaft.
[0062] In order for individual pressure boosters to be mounted on a
common rotating shaft, the respective flow-through openings in such
separator plates should be aligned. The penetrations of the shaft
through the wall of the pressure vessel, and the consecutive
intervening separator plates where such plates are penetrated,
should all contain seals that will limit pressure leakage.
[0063] In this manner an indefinite number of sets of membrane
stacks may be arranged in series without the necessity of raising
the inlet pressure to inconvenient levels.
Permeate Back-Pressure Control
[0064] An important consideration when assembling multiple stacks
of membrane panels in respective chambers all connected in series
within a common pressure containment vessel, is to control the
pressure differential across the membranes. Typically membranes
have a preferred range of trans-membrane pressure, e.g., about 100
psi.
[0065] If, in order to accommodate progressive pressure loss as the
feedstock passes through multiple stacks of membrane panels
connected in series, it is elected to provide feedstock to the
pressure vessel inlet at a moderately elevated pressure, e.g. 130
PSI, then it may be practical to have feedstock flow through a few,
e.g., 2 or 3, stacks with the feedstock pressure dropping
consecutively from stack to stack. The membranes in the initial
stack will be exposed to an elevated trans-membrane pressure, but
this may be at a level that is tolerable. However, when a larger
number of stacks are employed in a series arrangement it is
preferable to maintain the trans-membrane pressure at its preferred
operating level. In cases where the inlet feedstock pressure is
particularly elevated, it may be necessary to protect the membranes
from exposure to an excessively elevated feedstock pressure.
[0066] An arrangement with this objective is to control the
back-pressure within the permeate collection chambers of at least
some of the stacks of membrane support panels.
[0067] In the proposed configuration, the permeate outlet from each
membrane support panel in a stack delivers permeate to a stack
manifold that collects the permeate drainage from the individual
panels. Conveniently this collection system may deliver permeate to
a separator plate at the end of the stack. This separator plate
then provides a passageway for the permeate to exit the pressure
vessel. The outlet from this separator plate can be provided with a
back-pressure control valve having an associated pressure sensor
and valve control system. This valve can adjust the back-pressure
in the permeate collection chambers within the associated stack,
placing the trans-membrane pressure for all panels within the stack
within a desired range.
Pretreatment--Particle Removal
[0068] According to e+e another aspect of the invention removal of
particulates from a liquid is effected using a preferably
non-disposable, non-blinding filter, to be described as a
"knocking" filter.
[0069] In accordance with one feature of the invention, the
preferably pre-treated, e.g. settled, particulate-containing
feedstock is passed through a continuous and non-blinding filter to
remove solid particulates that may be in suspension or be slow to
settle.
[0070] A preferred apparatus for this purpose is a "knocking",
non-blinding filter to produce a filtrate that is substantially
reduced in particles above the mesh size that would otherwise be
present in the liquid, particularly those particulates that would
remain in suspension. The apparatus next described is suitable for
treating flowable solids as the feedstock as well as liquids. Such
a system can comprise: [0071] a. a resiliently supported frame in
turn supporting a durable, permeable filter screen or mesh that is
oriented at a flow-supporting downwardly inclined angle, e.g.
between 5 and 30, more preferably 5 to 20 degrees from the
horizontal for a used lube oil feedstock, [0072] 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, [0073] c. a catching container positioned beneath
the screen for capturing the filtrate, also referred-to as the
"permeate", passing through the screen, [0074] d. an actuator
coupled to the resiliently supported frame to apply a force with a
component for displacing the frame with a component 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,
and, optionally, [0075] e. a return displacement mechanism for
causing the filter to thereafter return to its original
location.
[0076] The filter media in the used oil application can be a
non-disposable steel mesh, preferably a stainless steel mesh with
openings on the order of 300 mesh size, e.g., approximately 50
micron opening size, but optionally smaller than 200 microns, more
preferably smaller than 100 microns and even more preferably 50
microns but larger than 40 microns. Beneath the mesh is a catching
container that is liquid-accommodating when a liquid is being
treated. At the lower end of the filter station that supports the
frame a receiving container is positioned to collect material that
fully transits the length of the filter.
[0077] In the treatment of used lube oil that has previously gone
through a settling stage, the length of the screen can be chosen to
allow 90% or more--e.g. up to 98-99% of the potential permeate, to
penetrate the screen. The non-penetrating particulate component
therefore rises in its concentration as it proceeds towards the
base of the screen. Near the base end it can virtually form a
sludge if allowed to accumulate. The effect of the "knocking"
action is to encourage such particulate matter to proceed towards
and off the base end of the screen. Conveniently a chute may direct
this sludge into a sludge bucket that serves as the receiving
container.
[0078] The chute surface, made of a low friction material, is
preferable more downwardly inclined than the screen, e.g. 15-30%
more. Optionally but preferably at least a portion of the chute
narrows from its upper to its lower end. This chute is carried by
the resiliently supported frame and experiences the same
acceleration cycles as that imposed on the frame and screen by the
knocking action.
[0079] The same knocking action serves to dislodge particles in the
higher, initial, portion of the screen from blocking screen
openings. The knocking action tends to loft the particles back into
the fluid flow thereby clearing the screen openings within which
they were lodged. Once so lofted the particles are swept, even
momentarily, towards the base end of the screen. In this manner
virtually all non-pass-through particulates will eventually be
conveyed to the base end of the screen.
[0080] The "knocking" effect arises from applying a force to
accelerate the screen from underneath particles lodged thereon. For
this purpose it is suitable to expose the filter screen to a cyclic
motion which includes stages of acceleration and deceleration.
These stages are not necessarily symmetrical. In a preferred
variant of the invention, the level of acceleration during the
"knocking" action is a factor greater than the absolute value of
any other acceleration or deceleration stage occurring in the
cycle. As a preferred example, this maximum rate of acceleration is
more than twice, more preferably over three times the absolute
value of any other acceleration or deceleration occurring during an
agitation cycle.
[0081] For example, the frame and its accompanying screen, as well
as the liquid and particles supported thereon can be exposed to an
acceleration of 0.3 g to 5 g, more preferably 1 to 3 g, over at
least a short length of its travel, tending to displace the
particles that have lodged on the surface of the screen so as to
return them into the flow of feedstock descending down the face of
the screen.
[0082] The force applied to the frame can be periodic, for example,
with a frequency of 1 per 5 seconds to 20 per second. An actuator
such as an electrical solenoid can generate the accelerating force.
Mechanical linkages connected to a rotating off-center mass that
imposes a non-sinusoid motion to the screen can achieve the same
effect, including optionally returning the screen to its original
position to complete the cycle if the frame for the screen is not
otherwise so provided. The return displacement mechanism can be
based on a spring or other resilient element to cause the frame and
filter screen to return resiliently to their original location. In
the latter case the knocking effect can be achieved through a
hammer action.
[0083] The described filter of the invention is not necessarily
intended to be the final stage in a liquid clarifying process. For
example, the filtrate may be subsequently transferred to a
centrifuge which simulates enhanced gravity and completes the
substantial removal of suspended solid matter and emulsions that
can be managed in this manner. And the filtration stage of the
invention can be conveniently placed ahead of flash evaporators
which remove dissolved liquid components in the feedstock such as
water and glycol.
Pretreatment--Removal of Volatiles
[0084] According to one aspect of the invention a gas-liquid
exchange interface apparatus for effecting chemical or physical
exchanges between a gas and a liquid, or evaporation of volatile
from the liquid, comprises a containment for maintaining inner
components in a gas-tight, pressure controlled environment. This
containment has at least a liquid inlet for introducing the liquid
into the containment, a liquid outlet from the containment for
evacuating a residual portion of the liquid, and a gas outlet on
the containment for introducing or evacuating gases present therein
or extracting volatile components evaporated from the liquid.
[0085] Within the containment is a segmented, vertical cascade of
support surfaces positioned in the form of a column of segments.
The liquid being processed passes progressively downwardly from
segment to segment within the column. In each segment a first
support surface is positioned to receive the liquid from the liquid
inlet onto a central region of the first support surface. From
there the liquid will flow radially outward from the central region
to and beyond the periphery of the first support surface. This
advantageously forms an expanding film as the liquid proceeds
outwardly. In so flowing the liquid passes over the top wetted
surface of the spinning disc which is open upwardly and uncovered
for exposure to release volatiles or carry-out a gas-liquid
reaction.
[0086] Each segment is also provided with a peripheral receiving
surface and transfer passageway to transfer such liquid leaving the
first support surface for deposition onto a second support surface
located below. Effectively, the second support surface with its
peripheral side surface serves as a kind of catch pan with an
encircling rim to serve as the peripheral receiving surface and
transfer passageway. Liquid so deposited undergoes inward radial
flow over the second support surface towards the central area of
the second support surface. A central opening in the central area
of the second support surface is positioned to direct the liquid
onto the central region of the first support surface of the next
consecutive segment.
[0087] Liquid flowing over the second support surface is uncovered
for exposure to release volatiles or carry-out a gas-liquid
reaction.
[0088] According to a further feature of the invention a liquid
distributor means within each segment induces liquid deposited on
the central region of the first support surface to flow radially
outward from the central region. As well, a liquid gathering means
for the second surface draws liquid towards the central region of
the second support surface. Additionally, a thermal control source
is positioned within at least some of the segments for heating or
cooling the liquid passing over the surfaces therein.
Heater/Chiller Features
[0089] The thermal control source can be positioned between the
first and second surfaces within the segments for heating or
cooling the liquid passing over particularly the second surface. In
the heating case the thermal control source can be in the form of
suitably insulated electrical resistance heating wires. In either
the heating or cooling case the thermal control source can be in
the form of tubing carrying a heating or cooling fluid that, by
radiation, conduction and/or convection, either heats or cools the
second surface and liquid flowing thereon. When positioned between
the surfaces some heat transfer can occur with respect to the first
surface. Alternately, the thermal control source can be located
beneath the second surface. In such case the tubing or electrical
wires can in thermal connection with the stationary second support
surface or catch pan from below.
[0090] In order to improve the thermal connection between insulated
electrical resistance wires and the bottom surface of the catch pan
providing the second support surface, the catch pan may be made of
aluminum. Further, the electrical insulated electrical wires may be
wrapped or enclosed in an aluminum sheet or tube which is tightly
crimped shut in order to provide a higher degree of physical
contact between the outer insulation of the wires and the aluminum
tube. The wires so contained in the crimped aluminum tube may then
be readily welded by aluminum welding to an aluminum catch pan with
appropriate aluminum filleting to improve thermal conductivity.
[0091] Optionally but preferably temperature sensors are positioned
within at least some of the segments that have a thermal control
source present. The sensors serve to detect the temperature of the
liquid, when present, as it passes through the segment. A
controller coupled to a typical temperature sensor is also
connected to the source of hot or cold fluid or electricity for the
thermal control source and is configured for controlling the rate
of delivery of heat transfer by the thermal source to or from the
segments so equipped.
[0092] Where conditions require, such as where the liquid being
processed is increasing in viscosity as it is being processed, the
controller may be arranged to operate by transferring a differing
quantity of heat to at least one segment than to another segment in
the column. Thus in the example given greater heat can be
transferred to one or more segments to reduce the increase in
viscosity of the liquid. Such segments in the case of evaporation
of volatiles are more likely to be located in the lower portion in
the column.
[0093] By sensing the temperature of the liquid in at least two
segments of the column while the liquid proceeds through the column
the controller can control 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. This can be used to
accommodate not only an increase in the viscosity of the liquid as
it proceeds downwardly through segments of the column but also
compensate for the heat effects of exothermal or endothermal
reactions that may arise when a gas-liquid reaction is
occurring.
Top Surface Liquid Distributing--Spinning
[0094] As an aid to promote the radially outward flow of liquid
from the central region to and beyond the periphery of the first
support surface, the invention may include a liquid distributor
means in the form of a rotatable central shaft having a central
axis running through the column. This shaft is connected to the
first support surface for rotating the first support surface within
the containment and thereby enhancing the radial flow effect. The
first support surface in such case can be in the form of a spinable
disc with a circumferential perimeter, the discs in the respective
segments being mounted on the rotatable central shaft. The "discs"
may or may not be slightly conic. The increasing centrifugal force
impressed on the liquid as it nears the periphery of the disc tends
to overcome increased viscosity which may arise from the loss of
volatile fractions. In this spinning disc variant in at least some
of the segments of the first support surface can be 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. The size of the openings provided by the
perforations is dimensioned to support this surface tension
effect.
[0095] A similar effect can be achieved by providing or forming the
first support surface within such segments with a screen portion
that is permeable to permit liquid to pass there through and travel
radially outwardly on the underside of such surface. The screen
portion can be based upon a wire screen mesh or other woven or
fibrous format that will serve as a permeable screen portion and
permit fluid to pass there through. The screen should be of a
material and configuration that will cause the liquid to cling to
and flow over its underside surface through surface tension. In
either arrangement the first support surface can be conically
shaped and oriented to be opening upwardly so as to bias liquid to
pass through the screen or holes for outward travel on the
underside of such surface.
Top & Bottom Surface Liquid Distributing--Wiping
[0096] As an alternate variant to the use of spinning discs the
liquid distributor means for the first surface can be based upon a
wiping blade mounted on a central rotating shaft having a central
axis. This shaft serves to rotate the wiping blade and sweep it
over the first support surface thereby inducing outward radial flow
of the liquid when deposited thereon.
[0097] Such a wiping blade can be employed in a similar manner in
respect of the second surface. Such arrangement can be employed
whether the first surface is spun or swept at least in respect of
some or all of the segments in the column. In such case a wiper
blade operates to support or induce inward radial
flow--gathering--of the liquid when deposited thereon. When the
first surface is being spun or even being wiped the wiping blade
for the second surface can be mounted on the same central rotating
shaft that provides rotation for the first surface, optionally
connected through a speed reducing connector. One suitable
connector 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.
[0098] The second surface need not be wiped at all. The presence of
a liquid distributor means for the second surface includes a
configuration where 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 over the second support surface towards the
central area of the second support surface under gravity. However,
a wiped surface can be less conically inclined.
[0099] The above description applies to effecting both air-liquid
chemical reactions and effecting physical processes such as
evaporating a volatile from a liquid. The preferred embodiment
described below uses the separation of water and glycol from used
engine oil as an example. The structure and process of the
invention can be used in other cases where a mass transfer occurs
at a gas-liquid interface as well as when a volatile component is
to be extracted from a liquid.
[0100] The foregoing summarizes the principal features of the
invention and some of its optional aspects. The invention may be
further understood by the description of the preferred embodiments,
in conjunction with the drawings, which now follow.
[0101] Wherever ranges of values are referenced within this
specification, sub-ranges therein are intended to be included
within the scope of the invention unless otherwise indicated or are
incompatible with such other variants. Where characteristics are
attributed to one or another variant of the invention, unless
otherwise indicated, such characteristics are intended to apply to
all other variants of the invention where such characteristics are
appropriate or compatible with such other variants.
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.degree. C., e.g. 80.degree.-110.degree. 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, 1/2 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 more--up 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 1/2 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 displacement--PD pump 255 that is isolated from the
vacuum environment by a normally closed--NC 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 Distributing--Spinning
[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 Distributing--Wiping
[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. 12.times.12'' 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.degree. 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.degree. angle and then went horizontal to a
sanitary fitting, proceeded through a 90.degree. 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.
* * * * *
References