U.S. patent number 3,857,764 [Application Number 05/381,693] was granted by the patent office on 1974-12-31 for electrochemical processing of inner surfaces of large vessels.
Invention is credited to John F. Jumer.
United States Patent |
3,857,764 |
Jumer |
December 31, 1974 |
ELECTROCHEMICAL PROCESSING OF INNER SURFACES OF LARGE VESSELS
Abstract
A portable electrode assembly is disclosed for passage through
restricted openings and convenient set-up within relatively large
vessels for the purpose of electrochemically processing or treating
the inner surface of the vessel without removing the vessel from
its associated permanent support structure. In preferred
embodiments, high density electrolyte solutions are used with
electrode assemblies which include means for displacing substantial
quantities of the electrolyte while providing support for the
electrode elements.
Inventors: |
Jumer; John F. (Elmhurst,
IL) |
Family
ID: |
26869315 |
Appl.
No.: |
05/381,693 |
Filed: |
July 23, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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173581 |
Aug 20, 1971 |
3772163 |
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Current U.S.
Class: |
205/132; 204/212;
205/668 |
Current CPC
Class: |
C25D
7/04 (20130101) |
Current International
Class: |
C25D
7/04 (20060101); C23b 005/56 (); C23b 005/68 () |
Field of
Search: |
;204/26,129.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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455,810 |
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Oct 1936 |
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GB |
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915,006 |
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Jan 1963 |
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GB |
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193,875 |
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Aug 1967 |
|
SU |
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Primary Examiner: Tufariello; T. M.
Attorney, Agent or Firm: Lockwood, Dewey, Zickert &
Alex
Parent Case Text
This is a division of application Ser. No. 173,581, filed Aug. 20,
1971, now U.S. Pat. No. 3,772,163.
Claims
I claim:
1. A method of electroprocessing the electrically conductive
interior surface of a stationary large capacity upright vessel of
uniform cross section having at least one top and one bottom
opening therein which openings are relatively small compared to the
girth of said vessel, comprising: securing anchor means in said
bottom opening; attaching to said anchor means inflatable buoyant
electrolyte displacer means having a uniform cross-sectional shape
when inflated corresponding generally to that of the interior side
wall of said vessel but having a height when inflated that is
substantially shorter than the height of said vessel and inflating
said displacer means until the exterior side wall surface thereof
is adjacent to said interior side wall surface with approximately
uniform space therebetween; covering the exterior side wall surface
of said inflated electrolyte displacer means with an endless
electrode, operatively connecting position control means with said
inflated electrolyte displacer means so as to permit raising and/or
lowering thereof through at least one said top opening; introducing
and maintaining an electrolyte in substantially the entire space
separating said exterior surface of said electrolyte displacer
means from said interior surface of said vessel, the actual amount
of electrolyte in said vessel being substantially less than the
capacity thereof, and the combined volumes of said electrolyte and
said submerged electrolyte displacer means being substantially
equal to said vessel capacity; passing an electrical current
through said electrolyte between said electrode and said interior
surface; and, raising and/or lowering said inflated electrolyte
displacer means to electroprocess all of said interior side wall
surface.
2. The method called for in claim 1 wherein the shape of the
exterior bottom surface of said electrolyte displacer means when
inflated is substantially the same as that of the inner surface of
the bottom of said vessel, covering said bottom surface of said
inflated displacer means with an electrode, and passing an
electrical current through said electrolyte between said bottom
electrode and said inner bottom surface of said vessel when said
inflated electrolyte displacer means is in its lowermost operating
position so as to also electroprocess said inner bottom
surface.
3. The method called for in claim 2 wherein the shape of the
exterior top surface of said electrolyte displacer means when
inflated is substantially the same as that of the inner surface of
the top of said vessel, covering said top surface of said inflated
displacer means with an electrode, and passing an electrical
current through said electrolyte between said top electrode and
said inner top surface of said vessel when said inflated
electrolyte displacer means is in its uppermost operating position
so as to also electroprocess said inner top surface.
Description
This invention relates to innovations and improvements in the
electrochemical treatment of interior surfaces of vessels which are
permanently mounted and fitted with relatively narrow manways. The
invention can be utilized for conveniently and economically
electroplating, electropolishing, anodizing, electrocleaning or for
other electroprocessing or electrotreating operations on the inner
surfaces of vessels.
Large vessels are widely used in industry as reactors or pressure
vessels and usually they are installed permanently secured on
associated support structures in a vertical or upright position.
Many such vessels are enclosed within buildings, and the operations
involved in removing such a vessel for processing its inner surface
are usually prohibitively expensive. Moreover, many such vessels
are installed with mechanical support structure which is only
adequate to safely accomodate fluids which have relatively low
specific gravities, e.g., 1.0 or less. Hence, it is often unsafe to
fill such equipment with a high density electrolyte, e.g., one
having a specific gravity of approximately 1.7, such as are
commonly used in connection with electropolishing, for example.
Furthermore, most tanks, reactors, and pressure vessels of the
class described are not provided with large removable lids or ends,
and the entrance openings, typically a manway, tend to be quite
small, relatively speaking. For example, a small manway with hinged
and bolted hatch or cover may serve a vessel of 5,000 gallon
capacity.
Moreover, because of the extremely large capacity of many upright
reactors, pressure vessels, and other vertical vessels widely used
in industry, it would be most undesirable to fill such vessels with
electrlyte solution to capacity in order to immerse the electrode
therein. After use in electrochemical processing, generally,
electrolyte solutions are recovered for salvage of metal values,
and in any event, are generally not discharged into sewers because
of potentially adverse impact on municipal sewage treatment plants,
streams, and the like. The large volume of electrolyte to be
recovered and reclaimed, if such large vessels were filled to
capacity, would make such an operation undesirable.
It is an object of the present invention to provide a method and an
electrode apparatus by which vessels of the class described can be
processed in place by electrochemical processing. It is another
object of the present invention to provide an electrode assembly or
apparatus in which electrodes can be positioned singly or in
multiples fixed or movable, and with the active areas of the
electrodes juxtaposed and substantially uniformly spaced from the
interior surface of the vessel being processed for a period of time
necessary to adequately process the inside surface. Moreover it is
an object of the present invention to provide such an electrode
system for electrochemical processing of the inside of a relatively
large vessel using high density electrolyte solution even though
the vessel be designed for use in connection with relatively low
density fluid.
It is another object of the present invention to provide an
apparatus and a method for electrochemical processing of inner
surfaces of large vessels which achieve effective electrochemical
processing of the interior surface of said vessel without requiring
that the vessel be filled to capacity with high density electrolyte
solution.
Many upright tanks or pressure vessels have a domed bottom and a
domed top which can be referred to as heads, with central openings
or ports in the bottom for emptying, etc. and with central ports
and/or nozzles in the top. It is an object of the present invention
to utilize central top and bottom ports for the introduction and
operation of an electrode system which can be introduced through a
manway for the purpose of electrochemically processing the inside
surface of the vessel. It is a further object of the present
invention to provide an electrode system which can be adapted for
use to electrochemically treat only a portion of the total inside
area of the vessel at any one time, whereby power equipment and
conductor size is reduced to a conveniently practical level, and
also the problem of gas accumulation in the underside of the top
head is reduced or eliminated. It is a further object of the
present invention to provide an electrode system which can be
shaped to conform to standard top and bottom head configurations
whereby the top and bottom head of the vessels can be
electrochemically treated simultaneously with the substantially
cylindrical side walls of the vessel.
These and other objects are achieved in accordance with the present
invention, which is described in connection with preferred
embodiments, as well as in general terms in the following
description with the aid of the accompanying drawings in which:
FIG. 1 is a vertical sectional view with certain parts shown in
elevation, of a preferred embodiment of the invention as applied to
a large vertical permanently mounted vessel;
FIG. 2 is a top plan view of the structure illustrated in FIG.
1;
FIG. 3 is a sectional view taken on line 3--3 of FIG. 1;
FIG. 4 is a reduced scale cross-sectional view taken approximately
along the line 4--4 of FIG. 1;
FIG. 5 is an enlarged fragmentary detail sectional view taken on
line 5--5 of FIG. 3 showing the upper electrical connection with
one electrode element;
FIG. 6 is a fragmentary partially cross-sectional elevational view
of another embodiment of this invention in a large vertical
permanently mounted vessel;
FIG. 7 is a sectional view taken on line 7--7 of FIG. 6;
FIG. 8 is a partially sectional view of an alternative embodiment
of this invention; and
FIG. 9 is a partially sectional view of another alternative
embodiment of the present invention.
Referring to FIG. 1, a large vessel is generally indicated at 10.
For the purpose of simplifying and clarifying the illustration of
the invention, FIG. 1 does not show all of the conventional support
elements 11 for supporting vessel 10. It is to be understood that
vessel 10 is intended to illustrate any one of many well known
reactor or pressure vessels. These vessels commonly are enclosed
within a building, and may extend through one, two or more stories
of the building. Typically the vessels such as 10 are provided with
at least a manway in the top 12 and a bottom drain opening 14. The
manway 12 and drain opening 14 typically have flanges 16, 18,
respectively. It is to be understood that in a specific
installation vessel 10 may have one or more conventional inlet or
outlet connections which communicate with the interior 20 either
through domed top 22, domed bottom 24 or the side wall 26.
Typically manway 12 is accessible from a catwalk generally
indicated at 30 which is supported on vessel 10 or on other
conventional structural elements.
A preferred electrotreating apparatus for vessel 10 in accordance
with this invention is indicated generally at 32. The electrode
apparatus includes a pair of copper mesh electrodes 34, 36
supported on a large inflatable plastic liquid displacing bag 40
having a capped stem 42. Bag 40 is toroidal in horizontal section
and in exterior shape conforms generally to the interior of the
vessel 10. The bag 40 has a centrally located cylindrical
passageway 46, cylindrical inner wall 48, a number of reinforcing
dividers 50 connecting inner wall 48 and outer wall 52. Band 54
formed of stiffly resilient dielectric material passes around bag
40 near the lower end thereof and serves to reinforce the bag 40 in
the regions of insulated spacing rollers 56 and also provide
support for the rollers. It will be appreciated that three or more
of rollers 56 should be used around the circumference of band 54 to
maintain proper clearance between side walls 26 and electrodes 34,
36.
In the embodiment illustrated in FIGS. 1 through 5, electrodes 34,
36 include elongated curved wall portions 60, 61 respectively,
which conform to the inside laterial face 26, and two sector shaped
portions 62, 63 conforming to bottom 24, and top 22, respectively.
Referring to FIGS. 3 and 5, the respective radially innermost or
terminal ends of electrode 34, 36 are clamped between respective
clamping bars 64, 66 by nuts and bolts generally indicated at 68.
Clamping bars 64, 66 are electrically connected to each other by
means of electrically conductive cross bars 69. Electric lead 70 is
bolted to clamping bar 64 and provides uniform distribution of
current to both electrodes 34, 36. Cross bars 69 are clamped
between tightenable sections of a two-part collar 71, one part of
which is fixed to rod 72. Clamping bars 64, 66, and cross bars 69,
and collar 71 can be considered an electrode support assembly 73,
and an identical assembly 73' fastens the other ends of the
electrodes 34, 36. Collar 71 is formed of dielectric material so as
to insulate rod 72 from cross bars 69.
In assembling the apparatus 32 shown in FIG. 1, electrodes 34, 36
are passed through manway 12, and bag 40 is passed through manway
12 in collapsed condition. One or more bands 54 are passed through
manway 12 in open condition and ends are joined to provide
resilient annular structures 54. Rod 72 is then passed through
manway 12, and seated in socket 74. Collar 71 can be fastened to
rod 72 before its entry into vessel 10, and clamping bars 64, 66
and frame assemblies 73, 73', generally, can be attached, as
described hereinbefore, while inside vessel 10. Electrodes 34, 36,
are fasted to bands 54, and to clamping bars 64, 66. Bag 40 is
fastened to bands 54, while unfilled, and the assembler leaves the
vessel before spider 84 is secured.
In order to provide for accurate location and operation of the
apparatus 10 of this invention, rod 72 extends through passageway
46 and is secured at its bottom end in thrust bearing 74 of known
type capable of absorbing downward thrust resulting from the weight
of the electrodes 34, and 36, and liquid-displacing container or
bag 40. Thrust bearing assembly 74 is secured to end plate 76
which, in turn, is bolted to "T" 78 having valved side outlet 80.
The upper portion of rod 72 is supported in suitable thrust bearing
assembly 82 which is maintained centered in manway 12 supported in
the center of a spider 84. The thrust bearing 82 should be capable
of absorbing the upward thrust due to buoyancy of the
liquid-displacing container or bag 40. Handle wheel 86, and top and
bottom frame members 73, 73' are fixed with respect to rod 72.
Hence rotation of handle 86 causes rotation of rod 72 and, with it,
frame elements 73, 73' and the rest of the electrode assembly 32.
It will be appreciated from a consideration of FIG. 3 that the
electrodes 34, 36 cover a relatively small portion of the surface
area of the inflated bag 40. For example in the embodiment
illustrated in FIGS. 1 through 5 electrodes 34, 36 are each
approximately 50 inches wide and together cover approximately
28percent of the total exterior of displacer 40.
Thus in the embodiment illustrated in FIGS. 1 through 5, electrodes
34, 36 can be considered to be axially extending elongated strips
and the entire surface of the vessel 10 can be electrochemically
treated by rotated electrode assembly 32 around its elongated
vertical axis.
In operation of the invention a conventional electrolyte is pumped
into vessel 10, and a liquid-displacer such as water is charged to
bag 40 until vessel 10 and bag 40 are filled. Thus only a
relatively small amount of electrolyte is required.
During operation of the apparatus of the present invention, vessel
10 is electrically grounded and an electrical potential is applied
at electrical lead 72. Whether the lead 72 is made positive or
negative depends on whether electroplating, electropolishing, etc.
is to be performed. Handle 86 is turned as desired to rotate
assembly 32 to uniformly process the entire inner surface of the
tank.
An alternative embodiment is shown in FIGS. 6 and 7 in which an
electrode extends 360.degree. horizontally but extends along a
relatively short portion of the vertical length of the side wall of
the vessel the interior of which is to be electroprocessed. In this
alternative embodiment portions of the vessel and associated
structures correspond to those shown in FIGS. 1-5, and are
identified in FIGS. 6 and 7 by primed numbers.
The alternative electrode assembly is generally indicated by the
numeral 90 in FIGS. 6 and 7 and includes electrode 92. A
substantially toroidal bag 40' is positioned within closely
adjacent screen electrode 92 and, in the illustrated embodiment,
electrode 92 has relatively short laterally facing portions 94 and
end walls 96. Laterally facing portions 94 are maintained spaced
apart from inside lateral face 26' of vessel 10' by insulated
rollers 56' whose axles run horizontally, rather than vertically.
Bag 40' is equipped with a stem 42' for filling and emptying and is
toroidally shaped to provide vertically extending inner passageway
46'. A rope or cable 100 passes around drum 102, through passageway
46', around bottom pulley 104 and is fastened at connector 106 to
bag 40'. Bottom pulley 104 is fixed to plate 76' which, in turn, is
bolted to "T" 78'. The drum 102 is fitted with conventional ratchet
mechanism generally indicated at 107 whereby rotation of drum 102
can be controlled by applying forces to drum handle 108 to raise or
lower electrode mechanism 90, and the broken line silhouette marked
"A" in FIG. 6 is intended to indicate the top or upper position of
electrode assembly 90. It is noted that the end walls 96 of
assembly 90 are shaped to have approximately the same contour as
top wall 22' and bottom wall 24' of container 10'. A number of end
spacers 110 are provided to keep the distance between respective
end portions 96 and top wall 22' and bottom wall 24' a suitable
distance for electrochemically processing the inner faces of end
walls 22', 24'. Thus, the embodiment shown in FIGS. 5 and 7 is
similar to the embodiment illustrated in FIGS. 1-5 inasmuch as only
a small portion of the inner face of the vessel 10, 10' is in
operating association with the respective electrodes 24, 26, 92, 96
at any one time. The embodiment shown in FIG. 6, however, differs
from the embodiment shown in FIGS. 1-5 inasmuch as the entire
circumference of electrode assembly 90 is covered with electrode
92, and electrode 92 extends in an axial direction for only a
relatively small fraction of the axial dimension of side wall 26'
of vessel 10'. In the embodiment shown in FIG. 6 the electrode
assembly 90 is permitted to float upwardly, and is moved downwardly
by controlling cable 100. Thus line 100 is payed out to raise the
electrode assembly 90, and reeled in to lower it. A suitable biased
take-up reel generally indicated at 109 keeps electrical lead 72'
taut as electrode assembly 90 moves up and down within vessel
10'.
In the alternative embodiment illustrated in FIG. 8 an electrode
assembly is generally indicated at 110 and the details of its
construction are substantially identical to the construction
described in connection with FIGS. 1-5. However, inner lateral face
94' extends substantially the entire length of side wall 26' and
ends 96' are closely spaced apart from the top and bottom of vessel
10' which is identical to the vessels described in connection with
the other embodiments herein. In the latter embodiment it is
unnecessary to provide means for raising and lowering or for
rotating about a vertical axis since the entire inner surface of
the walls of vessel 10' have an electrode mesh closely adjacent
thereto, and in operating association therewith.
Although electrode 92 is shown with an integral electrode grid
around its entire circumference, it is contemplated that electrode
grid 92 can be assembled from a plurality of axially extending
strips, each similar to electrode 34, 36, placed side by side to
provide a complete 360.degree. electrode grid. In such an
embodiment the respective electrode strips, e.g., 34, 36, are
passed through manway 12 in a slightly folded condition and
displacement medium container 40 is positioned within the electrode
strip circle. Thereafter the upper portions of the respective
electrode strips 34, 36 are fastened, as illustrated in FIG. 5
herein, to a suitable framing element, e.g., 63, with appropriate
electrical connections being made thereto. As electrolyte 125 is
introduced into vessel 10, for example through valve line 80, a
suitable electrolyte displacing material is charged to container
40. If vessel 10 and its associated supporting structures (not
shown because conventional) have been designed to accomodate a high
density fluid, water or a relatively high density displacing fluid
can be added to container 10 to fill it out and provide a suitable
configuration for supporting the electrode grid, e.g., 34, 36.
However, if vessel 10 and its associated supporting structure has
been designed for use solely in connection with relatively low
density fluid, it is preferred that container 40 be filled with a
relatively low density material, and a particulate plastic capable
of being pneumatically conveyed, and capable of removal by
conventional vacuum conveyor, is preferred.
In another alternative embodiment, which is shown in FIG. 9,
elongated vertical electrode 34' is used along only one side of
container 40, and a counter weight 122 is suspended from the
opposite side of frame 63. This embodiment corresponds to that
shown in FIGS. 1-5, except that electrode 36 is replaced by
counterweight 122. In operation it is necessary to rotate the
electrode assembly 120, in order to electro-treat the entire inner
surface of vessel 10'.
In the operation of the invention, container 40 is filled with an
electrolyte displacing material, and the preferred density of the
material utilized within bag 40 will depend, to a great extent, on
the engineering details of the supporting structures of the
particular vessel 10 and on the safety factor used in designing
vessel 10. For example, in the case of a vessel which was designed,
along with its supporting structure, to contain and process a
relatively low density liquid, e.g., 0.8, it may well be advisable
to avoid filling such a vessel with a high density electrolyte,
e.g. one having a specific gravity of 1.7. In this instance, it
would be highly desirable and probably advisable to displace most
of the electrolyte with a relatively low density displacing
material for reasons of safety. It is contemplated that container
40 can be filled with a gas such as air, with a relatively low
density liquid such as water, or oil, etc., or with a solid, such
as discrete particles of low density plastic which can be charged
to container 40 and withdrawn therefrom by means of appropriate
conventional vacuum or gas stream conveying systems.
Also, it is contemplated that the displacing means used in this
invention could also be provided in the form of a self-contained
material such as one or more large, preferably elongated pieces of
relatively light weight solid material which are fastened to the
electrode assembly in place of container or bag 40. Elongated
blocks having the cross section of a truncated sector of a circle,
can be used, for example, to form a cylindrical body similar to bag
40 as shown in FIG. 4. Blocks of styrofoam, or polyurethane can
also be used.
It will be apparent that modifications and changes can be made with
respect to the specifically described illustrations herein without
departing from the spirit or the scope of the invention. For
example, although container 40 is described in connection with the
illustrated preferred embodiment has been referred to as a plastic,
it is contemplated that non-plastic, or even porous materials such
as screens or mesh can be used to confine larger low density
plastic spheres, for example, providing that the material which is
used for the container, and the electrolyte-displacement material
are both compatible with the electrical and chemical
environment.
As indicated above, it is most preferred that the respective
electrodes utilized in the invention be cooperatively associated
with a relatively small portion of the total interior surface of
the vessel 10. The main reason for this is the fact that such an
apparatus can provide the relatively high ampere per square foot
surface throughput, while requiring a total current supply which is
conveniently manageable. In a preferred method of operating,
utilizing the embodiment described in FIGS. 1-5 herein, it is
preferred that the rotation of the electrode assembly 32 around its
vertical axis is constant, and in the same direction. Constant
rotation in the same direction better assures uniform treatment of
the vessel. However it is not essential that the electrode assembly
32 be rotated only in a given direction, and back and forth
rotation is entirely satisfactory.
With respect to the other details of operation, e.g. the current
levels, etc. the operation of the present invention is governed by
well known electrochemical processing techniques and
principles.
The invention has been described in general terms, and in
connection with several preferred embodiments. However, the
specific examples provided herein are for illustrative purposes
only, and changes can be made without departing from the spirit or
scope of the invention. Hence, the invention is not limited to the
specific illustrations herein, and has the scope of the claims
appended hereto.
* * * * *