CA1073432A - Method of regenerating used active carbon - Google Patents
Method of regenerating used active carbonInfo
- Publication number
- CA1073432A CA1073432A CA250,446A CA250446A CA1073432A CA 1073432 A CA1073432 A CA 1073432A CA 250446 A CA250446 A CA 250446A CA 1073432 A CA1073432 A CA 1073432A
- Authority
- CA
- Canada
- Prior art keywords
- electrodes
- particles
- holes
- active carbon
- used active
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/30—Active carbon
- C01B32/354—After-treatment
- C01B32/36—Reactivation or regeneration
- C01B32/366—Reactivation or regeneration by physical processes, e.g. by irradiation, by using electric current passing through carbonaceous feedstock or by using recyclable inert heating bodies
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Inorganic Chemistry (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for regenerating used active carbon which comprises: (a) introducing particulate used active carbon into a generally perpendicular column having electrode plates provided therein at or adjacent its upper and lower end, the surface of said electrode plates being uniformly provided with a plurality of holes large enough to allow the particles of said used active carbon to pass therethrough; and (b) letting said particles of said used active carbon flow down through said column whilst maintaining the space in said column between said electrodes filled with said particles, and at the same time applying a voltage to the electrode plates to effect direct electrical heating of said particles.
A method for regenerating used active carbon which comprises: (a) introducing particulate used active carbon into a generally perpendicular column having electrode plates provided therein at or adjacent its upper and lower end, the surface of said electrode plates being uniformly provided with a plurality of holes large enough to allow the particles of said used active carbon to pass therethrough; and (b) letting said particles of said used active carbon flow down through said column whilst maintaining the space in said column between said electrodes filled with said particles, and at the same time applying a voltage to the electrode plates to effect direct electrical heating of said particles.
Description
`` 1073432 FIELD OF THE INVENTION:
The present invention relates to an advantageous method of regenerating used active carbon, and more particularly, it pertains to a novel method which lncludes heating the used active carbon by applying an electric current thereto.
BACKGROU_D OF THE INVENTION:
In order to regenerate or reclaim used active carbon, it is known to heat the active carbon by passing an electric current therethrough, since the active carbon i8 electrically conductive. In prior art processes utilizing direct heating, the heat treatment has been carried out usually by one of three methods. The first method involves gradually accumulating the used active carbon betwéen two vertical electrode plates arranged face to face and then applying an electric current thereto (Accumulation Method). The second method involves ~ -continuously passing the particles between the two electrode pla~es whilst maintaining the spac-e between the plates filled with the particles and at the same time applying an electric current thereto (Method Using A Particle-Moving Layer). The 20 third method involves providing several further vertical --electrodes in a horizontal section of the particle-flow passage.
These prior art processes have several disadvantages.
- For example, in the Accumulation Method, the only possible operation is a batch type operation, which is unsuitable for continuous cyclic use of the active carbon. Additionally, the desorption of the materials adsorbed onto the active carbon is accompanied by a complicated procedure in which the applied voltage must be controlled, because the electric resistance of the particles suffers a change as the material is desorbed.
The Accumulation Method has the further drawback that it is difficult to establish a voltage control system capable of
The present invention relates to an advantageous method of regenerating used active carbon, and more particularly, it pertains to a novel method which lncludes heating the used active carbon by applying an electric current thereto.
BACKGROU_D OF THE INVENTION:
In order to regenerate or reclaim used active carbon, it is known to heat the active carbon by passing an electric current therethrough, since the active carbon i8 electrically conductive. In prior art processes utilizing direct heating, the heat treatment has been carried out usually by one of three methods. The first method involves gradually accumulating the used active carbon betwéen two vertical electrode plates arranged face to face and then applying an electric current thereto (Accumulation Method). The second method involves ~ -continuously passing the particles between the two electrode pla~es whilst maintaining the spac-e between the plates filled with the particles and at the same time applying an electric current thereto (Method Using A Particle-Moving Layer). The 20 third method involves providing several further vertical --electrodes in a horizontal section of the particle-flow passage.
These prior art processes have several disadvantages.
- For example, in the Accumulation Method, the only possible operation is a batch type operation, which is unsuitable for continuous cyclic use of the active carbon. Additionally, the desorption of the materials adsorbed onto the active carbon is accompanied by a complicated procedure in which the applied voltage must be controlled, because the electric resistance of the particles suffers a change as the material is desorbed.
The Accumulation Method has the further drawback that it is difficult to establish a voltage control system capable of
2 ~
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coping with the fluctuations in the amount of materials adsorbed onto the used active carbon and the fluctuations in the amount of carbon to be treated.
The above-mentioned Method Using A Particle-Moving Layer is suitable for continuous cyclic use of the active carbon, but it has the drawback that the electric current is applied at right angles to the direction of flow of the particles, which results in non-uniform application of the current to the particles present between the electrode plates. This is due to the fact that the electric resistance of the particles under-goes a change during the course of desorption of the adsorbed materials. To explain this in more detail, the apparent electrical resistance of the adsorbed material-containing particles in the moving layer of the active carbon has a higher value than that of the particles containing no adsorbed materials or of the regenerated active carbon. Therefore, the ele~ctrical resistance distribution in the layer of particles i of carbon between the two electrode plates has a high value on the upper side of the electrode plate and a low value on the lower side. When voltage is applied to the electrode plates, therefore, the electric current is biased towards the particles low iQ resistance on the lower side of the electrode plate.
As a reeult, heat generatioQ takes place only OQ the lower side of the electrode plates so that effective heat transfer is only produced w thin a narrow range. Therefore, iQ order to uniformly desorb the adsorbed carbon, the electrode plates must be of a considerable length and for this reason, the apparatus must be increased iQ size. This is why this method is not considered to be very useful in prastice.
Finally, the method for heating the used active carbon by providing a plurality of further vertical electrodes ...
in a horizontal section of the particle-flow passage and then applying an electric current to the particles passing among these electrodes, is often effective when a small experimen-tal device sufficient to uniformly heat the whole sectional area is used. This is because the particle-flow passage has } a comparatively narrow sectional area, but as previously explained, this method has the defect that the flow of elec-? tric current becomes non-uniform and unstable, and the same phenomenon as in the previous method is observed.
10 SUMMARY OF THE INVENTION:
An object of the present invention is to provide a method for advantageously reclaiming and treating used active carbon.
According to one aspect of the invention, there is pro-vided a method for regenerating used active carbon which comprises: (a) providing a generally vertical column containing at least two generally horizontal, vertically spaced electrodes, said electrodes having a plurality of - holes large enough to allow passage of the used active carbon particles therethrough and the total open area of said holes 20 in said electrodes being at least 25% of the total surface area defined by said electrodes; (b) introducing the used active carbon into the top of said column above the upper -electrode and allowing the used activated carbon to flow downwardly through said electrodes; and (c) applying a voltage between said electrodes to cause an electric current to flow through the carbon particles thereby heating said carbon to effect desorption of adsorped materials.
According to another aspect of the invention, there is provided apparatus for regenerating used active carbon 30 particles, comprising a generally vertical hollow column containing at least two generally horizontal, vertically ~ _ 4 _ C
- . , .. : ~;- .. :.
` 1073432 - spaced electrodes, said electrodes having a plurality of holes large enough to allow passage of the used active carbon therethrough, the total open area of said holes in said electrodes being at least 25% of the total surface area defined by said electrodes.
, ' - 4a -.r~, 107343~
The invention is based on the finding that, when electrodes are provided at the top and bottom of a perpendicular column and the space between these electrode plates is charged with used active carbon and a voltage is applied; then the flow of electric current through the carbon is uniform.
The term "used active carbon" as used in the present invention means active carbon which has lost its activity through use and is synonymous with the so-called "adsorbed carbor." i.e. carbon having materials adsorbed thereon.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION:
The primary feature of one embodiment of the method of the present invention is that the problem of heat generation resulting from a biased flow of electric current, which is a disadvantage of the above-mentioned prior art processes, has been solved by applying an electric current parallel to the flow direction of the moving layer of used active carbon particles.
The used active carbon particles are introduced into a perpendicular column having a pair of upper and lo~er electrode plates provided in the entrance and exit, respec-tively, of the column. The electrode plates have holes large enough to let the particles of the adsorbed carbon pass there-through, the holes being uniformly distributed over the surface of each plate. When a voltage is applied to the electrode plates, an electric current flows through the carbon and produces direct heating as the carbon flows do-~n through the column. Advantageously, the total open area of the electrode plates should account for at least 25 % of the total ;~
- . . ~ .
" 107343Z
surface area of the plates, and the holes may be of any sectional shape.
The reason why heat is generated in the particies of carbon when an electric current is applied directly thereto is that Joule effect heat is generated by electrical resistance mainly at the contact points between the particles. According-ly, in order to obtain stable heat generation, it is necessary not only to maintain contact between the particles and elec-trode plates, but also to maintain contact between the particles themselves. Further, in order to let the particles flow down through the perpendicular column whilst fully retaining these contacts, the total area of the holes in the electrode plates made at right angles thereto should be at least 25 % and preferably more than 40 % of the total surface area of the electrode plates, and furthermore, it is preferred that the holes be uniformly arranged in the electrode plates.
If ~he electrode plates have a lower percentage hole area than 25 %, a cone-like cavity may form which corresponds to the angle of repose of the particles, so that there become in-sufficient contacts between the particles and the electrodeplates, which causes non-uniform heat generation to take place in the particles. On the other hand, if the holes are too large, sometimes no electric current flows in a part of the particle layer, whereby the heat generation in the particles also becomes non-uniform. Further, such a tendency is conspicuously observed if the distance between the two elec-trode plates is too shor,. Such defects can largely be improved, for example, by making the lower part (i.e. the exit side) of the holes in a tapered shape having a wider angle of elevation than the angle of repose of the particles to avoid formation of the cone-like cavity. Alternatively, instead of providing a pair of upper and lower electrode plates of ldentical ~hape in a completely symmetrical position, the pl~tes may be provided in slightly different positions from the symmetrical position to improve uniformity of current flow. Basically, however, these defects can be remedied by using flat plate-like electrodes in which the holes are large enough for the particles of the used active carbon to pass therethrough and are uniformly arranged over the surfaces of the electrode plates, the total area of the openings of the holes being at least 25 % of the total surface area of the electrode plates.
By using electrode plates having the above-mentioned construction features, a stable process for continuously heating ehe used active carbon particles can be provided which is free from the defects of prior art processes. That is, a very efficient procesæ for heating used active carbon by continuously applying an electric current thereto can be provided, wherein the above-mentioned electrode plates are positioned at the upper and lower ends of a perpendicular column through which the used active carbon flows. Voltage is applied to the electrode plates, and an electric current flows parallel to the cirection of movement of the particles, whereby the electric current is uniformly applied over the whole of the :` moving passage to cause uniform heating of the moving particles.
This method of heating used active carbon is par-ticularly effective when it is applied to used carbon particles ; of spherical shape. In the case of spherical particles, the apparent electric resistance of the particles in a dense layer shows a fixed value with good reproducibility which is main-tained even when pressure is applied to the layer because the number of contact points among the particles, more specifically the contact point density, is constant. On the other hand, .
the apparent electric resistance of crushed carbon, or the like, suffers a comparatively great change, because the contact point density varies according to the manner of filling the column with the particles. Therefore, the reproducibility becomes poor. Spherical particles, however, have stable resistance `to electric current, stably flow down the column and show less change in the charged condition. From the technical and economical view-points, therefore, it is advan-tageous to use spherical particles in the present invention.
The electrical heat treatment of the used active carbon may be carried out in two heating stages: i.e. a pre-heating stage and a desorption heating stage. Alternatively, when several kinds of materials having different desorption temperatures are separately to be desorbed and recovered from the used active carbon, these materials may be recovered by controlling the voltage applied to a plurality of electrode plates distributed in several stages.
According to one embodiment of the present invention, a very efficient compact apparatus can be obtained as a reclamation unit, ior example, for use in the gas treatment apparatuses or the like that use active carbon continuously.
In the drawings which illustrate this invention:
FIG. 1 is a schematic explanatory diagram illustrating one example of a vertical column for reclaiming used active carbon according to the present invention;
FIG. 2 is a plan view illustrating one preferred embodi-ment of perforated electrode suitable for use in the invention;
FIG. 3 is a similar plan view to FIG. 2 but illustra-ting another preferred perforated electrode;
In FIG. 1, reference numeral 1 indicates a vertical column, 2 indicates used active carbon, 3 indicates an electrode ' .
, .. . . . .
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and 4 a hole in said electrode. The shape of the electrode 3 is not important but the electrode may be, for example, rectangu-lar or circular as shown in FIG. 2 or FIG. 3. In F~IG. 2, 5 denotes a rectangular electrode and 6 a hole in said electrode.
In FIG. 3, 7 denotes a circular electrode and 8 a hole in said electrode.
The present invention will be explained below in ~
more detail by way of example, bu~ the present invention shall not be limited to the example.
EXAMPLE
A carbon electrode plate having a thickness of 5 mm, -a length of 96 mm and a width of 96 mm was installed at the lower end of a square column made of hard glass. The carbon -`
` plate was provided with 61 holes each having a diameter of 8 mm arranged uniformly over the surfaceiof the plate. The square column had a height of 300 mm and an inner section side length of 100 mm. Another similar electrode plate was installed at a position 90 mm from the top of the lower electrode plate.
The column had a bottom portion having the shape of a converse ~ 20 pyramid type funnel. Particles (having an average grain size of 650 ~) of used spherical active carbon containing carbon tetrachloride adsorbed in an amount of 500 grams per kg of active carbon were fed into the top of the column at a velocity of 5 kg/hr. An alternating current of 100 V was applied to the above-mentioned electrode plates and when the temperature in - the center of the column reached 130C, a valve provided at the bottom portion of the column was opened to let the particles flow down and at the same time, air heated to 80C was fed into the column from a nozzle provided at the bottom portion. The `30 air served as a carrier stream for transportation of desorbed - components.
.
_ g _ ~' ' -, .~ . , .
The amount of undesorbed carbon tetrachloride in the reclaimed active carbon discharged from the column bottom was examined. The examination showed that the amount was 30 g, or below, per kg of reclaimed carbon.
For comparison, the same electrodes as used above were installed in two opposite walls inside the square column.
A voltage of 100 V was applied to these electrodes to heat the particles at right angles to their direction of movement. The amount of undesorbed carbon tetrachloride in the resulting reclaimed carbon was 80 g or more per kg of active carbon. In this case, the temperature in the center of the column was 105C to 120C. It was observed that a reduction in desorption efficiency was caused by a decline in temperature.
~, 1 ;. . .
SUPPLEMENTARY DISCLOSURE
. _ The principal disclosure relates to the application of an electric current to used active carbon particles in the direction of movement of said particles through the space between two or more perforated electrodes. In this supple-mentary disclosure, further information is provided about the perforated electrodes and specific electrode types are described in connection with the accompanying drawings, in which:
FIG. 4 is a sectional view of one type of perforated electrode, illustrating the shapes of the holes therein;
FIG. 5 is a similar view to FIG. 4 but illustrating holes of different shape; and FIG. 6 is a similar view to FIG. 4 but illustrating in addition to holes, a number of hollow legs in communication with the holes.
In FIG. 4, 9 denotes an electrode and 10 a hole therein having taper 11 at the upper part thereof. In FIG. 5, 12 denotes an electrode plate and 13 a hole therein having a taper 14 and a taper 15 at the upper and lower parts thereof, respectively. If desired, only the lower parts of the holes may be tapered outwardly towards the lower electrode surface.
The electrodes may have a number of hollow legs ~
or tubular extensions on the undersides thereof in communication with the holes therein, as shown in FIG. 6. Each of the legs ordinarily has a length in the order of 300 mm. In FIG. 6, 16 denotes an electrode and 17 denotes a leg in communication with a hole in the electrode. The electrodes having a number of hollo~ legs on the undersides thereof are preferred in the present invention, because the mobility of the used active carbon flowing through the holes in the electrodes can be increased when such electrodes are used.
` ~07343Z
coping with the fluctuations in the amount of materials adsorbed onto the used active carbon and the fluctuations in the amount of carbon to be treated.
The above-mentioned Method Using A Particle-Moving Layer is suitable for continuous cyclic use of the active carbon, but it has the drawback that the electric current is applied at right angles to the direction of flow of the particles, which results in non-uniform application of the current to the particles present between the electrode plates. This is due to the fact that the electric resistance of the particles under-goes a change during the course of desorption of the adsorbed materials. To explain this in more detail, the apparent electrical resistance of the adsorbed material-containing particles in the moving layer of the active carbon has a higher value than that of the particles containing no adsorbed materials or of the regenerated active carbon. Therefore, the ele~ctrical resistance distribution in the layer of particles i of carbon between the two electrode plates has a high value on the upper side of the electrode plate and a low value on the lower side. When voltage is applied to the electrode plates, therefore, the electric current is biased towards the particles low iQ resistance on the lower side of the electrode plate.
As a reeult, heat generatioQ takes place only OQ the lower side of the electrode plates so that effective heat transfer is only produced w thin a narrow range. Therefore, iQ order to uniformly desorb the adsorbed carbon, the electrode plates must be of a considerable length and for this reason, the apparatus must be increased iQ size. This is why this method is not considered to be very useful in prastice.
Finally, the method for heating the used active carbon by providing a plurality of further vertical electrodes ...
in a horizontal section of the particle-flow passage and then applying an electric current to the particles passing among these electrodes, is often effective when a small experimen-tal device sufficient to uniformly heat the whole sectional area is used. This is because the particle-flow passage has } a comparatively narrow sectional area, but as previously explained, this method has the defect that the flow of elec-? tric current becomes non-uniform and unstable, and the same phenomenon as in the previous method is observed.
10 SUMMARY OF THE INVENTION:
An object of the present invention is to provide a method for advantageously reclaiming and treating used active carbon.
According to one aspect of the invention, there is pro-vided a method for regenerating used active carbon which comprises: (a) providing a generally vertical column containing at least two generally horizontal, vertically spaced electrodes, said electrodes having a plurality of - holes large enough to allow passage of the used active carbon particles therethrough and the total open area of said holes 20 in said electrodes being at least 25% of the total surface area defined by said electrodes; (b) introducing the used active carbon into the top of said column above the upper -electrode and allowing the used activated carbon to flow downwardly through said electrodes; and (c) applying a voltage between said electrodes to cause an electric current to flow through the carbon particles thereby heating said carbon to effect desorption of adsorped materials.
According to another aspect of the invention, there is provided apparatus for regenerating used active carbon 30 particles, comprising a generally vertical hollow column containing at least two generally horizontal, vertically ~ _ 4 _ C
- . , .. : ~;- .. :.
` 1073432 - spaced electrodes, said electrodes having a plurality of holes large enough to allow passage of the used active carbon therethrough, the total open area of said holes in said electrodes being at least 25% of the total surface area defined by said electrodes.
, ' - 4a -.r~, 107343~
The invention is based on the finding that, when electrodes are provided at the top and bottom of a perpendicular column and the space between these electrode plates is charged with used active carbon and a voltage is applied; then the flow of electric current through the carbon is uniform.
The term "used active carbon" as used in the present invention means active carbon which has lost its activity through use and is synonymous with the so-called "adsorbed carbor." i.e. carbon having materials adsorbed thereon.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION:
The primary feature of one embodiment of the method of the present invention is that the problem of heat generation resulting from a biased flow of electric current, which is a disadvantage of the above-mentioned prior art processes, has been solved by applying an electric current parallel to the flow direction of the moving layer of used active carbon particles.
The used active carbon particles are introduced into a perpendicular column having a pair of upper and lo~er electrode plates provided in the entrance and exit, respec-tively, of the column. The electrode plates have holes large enough to let the particles of the adsorbed carbon pass there-through, the holes being uniformly distributed over the surface of each plate. When a voltage is applied to the electrode plates, an electric current flows through the carbon and produces direct heating as the carbon flows do-~n through the column. Advantageously, the total open area of the electrode plates should account for at least 25 % of the total ;~
- . . ~ .
" 107343Z
surface area of the plates, and the holes may be of any sectional shape.
The reason why heat is generated in the particies of carbon when an electric current is applied directly thereto is that Joule effect heat is generated by electrical resistance mainly at the contact points between the particles. According-ly, in order to obtain stable heat generation, it is necessary not only to maintain contact between the particles and elec-trode plates, but also to maintain contact between the particles themselves. Further, in order to let the particles flow down through the perpendicular column whilst fully retaining these contacts, the total area of the holes in the electrode plates made at right angles thereto should be at least 25 % and preferably more than 40 % of the total surface area of the electrode plates, and furthermore, it is preferred that the holes be uniformly arranged in the electrode plates.
If ~he electrode plates have a lower percentage hole area than 25 %, a cone-like cavity may form which corresponds to the angle of repose of the particles, so that there become in-sufficient contacts between the particles and the electrodeplates, which causes non-uniform heat generation to take place in the particles. On the other hand, if the holes are too large, sometimes no electric current flows in a part of the particle layer, whereby the heat generation in the particles also becomes non-uniform. Further, such a tendency is conspicuously observed if the distance between the two elec-trode plates is too shor,. Such defects can largely be improved, for example, by making the lower part (i.e. the exit side) of the holes in a tapered shape having a wider angle of elevation than the angle of repose of the particles to avoid formation of the cone-like cavity. Alternatively, instead of providing a pair of upper and lower electrode plates of ldentical ~hape in a completely symmetrical position, the pl~tes may be provided in slightly different positions from the symmetrical position to improve uniformity of current flow. Basically, however, these defects can be remedied by using flat plate-like electrodes in which the holes are large enough for the particles of the used active carbon to pass therethrough and are uniformly arranged over the surfaces of the electrode plates, the total area of the openings of the holes being at least 25 % of the total surface area of the electrode plates.
By using electrode plates having the above-mentioned construction features, a stable process for continuously heating ehe used active carbon particles can be provided which is free from the defects of prior art processes. That is, a very efficient procesæ for heating used active carbon by continuously applying an electric current thereto can be provided, wherein the above-mentioned electrode plates are positioned at the upper and lower ends of a perpendicular column through which the used active carbon flows. Voltage is applied to the electrode plates, and an electric current flows parallel to the cirection of movement of the particles, whereby the electric current is uniformly applied over the whole of the :` moving passage to cause uniform heating of the moving particles.
This method of heating used active carbon is par-ticularly effective when it is applied to used carbon particles ; of spherical shape. In the case of spherical particles, the apparent electric resistance of the particles in a dense layer shows a fixed value with good reproducibility which is main-tained even when pressure is applied to the layer because the number of contact points among the particles, more specifically the contact point density, is constant. On the other hand, .
the apparent electric resistance of crushed carbon, or the like, suffers a comparatively great change, because the contact point density varies according to the manner of filling the column with the particles. Therefore, the reproducibility becomes poor. Spherical particles, however, have stable resistance `to electric current, stably flow down the column and show less change in the charged condition. From the technical and economical view-points, therefore, it is advan-tageous to use spherical particles in the present invention.
The electrical heat treatment of the used active carbon may be carried out in two heating stages: i.e. a pre-heating stage and a desorption heating stage. Alternatively, when several kinds of materials having different desorption temperatures are separately to be desorbed and recovered from the used active carbon, these materials may be recovered by controlling the voltage applied to a plurality of electrode plates distributed in several stages.
According to one embodiment of the present invention, a very efficient compact apparatus can be obtained as a reclamation unit, ior example, for use in the gas treatment apparatuses or the like that use active carbon continuously.
In the drawings which illustrate this invention:
FIG. 1 is a schematic explanatory diagram illustrating one example of a vertical column for reclaiming used active carbon according to the present invention;
FIG. 2 is a plan view illustrating one preferred embodi-ment of perforated electrode suitable for use in the invention;
FIG. 3 is a similar plan view to FIG. 2 but illustra-ting another preferred perforated electrode;
In FIG. 1, reference numeral 1 indicates a vertical column, 2 indicates used active carbon, 3 indicates an electrode ' .
, .. . . . .
`` 107343Z
and 4 a hole in said electrode. The shape of the electrode 3 is not important but the electrode may be, for example, rectangu-lar or circular as shown in FIG. 2 or FIG. 3. In F~IG. 2, 5 denotes a rectangular electrode and 6 a hole in said electrode.
In FIG. 3, 7 denotes a circular electrode and 8 a hole in said electrode.
The present invention will be explained below in ~
more detail by way of example, bu~ the present invention shall not be limited to the example.
EXAMPLE
A carbon electrode plate having a thickness of 5 mm, -a length of 96 mm and a width of 96 mm was installed at the lower end of a square column made of hard glass. The carbon -`
` plate was provided with 61 holes each having a diameter of 8 mm arranged uniformly over the surfaceiof the plate. The square column had a height of 300 mm and an inner section side length of 100 mm. Another similar electrode plate was installed at a position 90 mm from the top of the lower electrode plate.
The column had a bottom portion having the shape of a converse ~ 20 pyramid type funnel. Particles (having an average grain size of 650 ~) of used spherical active carbon containing carbon tetrachloride adsorbed in an amount of 500 grams per kg of active carbon were fed into the top of the column at a velocity of 5 kg/hr. An alternating current of 100 V was applied to the above-mentioned electrode plates and when the temperature in - the center of the column reached 130C, a valve provided at the bottom portion of the column was opened to let the particles flow down and at the same time, air heated to 80C was fed into the column from a nozzle provided at the bottom portion. The `30 air served as a carrier stream for transportation of desorbed - components.
.
_ g _ ~' ' -, .~ . , .
The amount of undesorbed carbon tetrachloride in the reclaimed active carbon discharged from the column bottom was examined. The examination showed that the amount was 30 g, or below, per kg of reclaimed carbon.
For comparison, the same electrodes as used above were installed in two opposite walls inside the square column.
A voltage of 100 V was applied to these electrodes to heat the particles at right angles to their direction of movement. The amount of undesorbed carbon tetrachloride in the resulting reclaimed carbon was 80 g or more per kg of active carbon. In this case, the temperature in the center of the column was 105C to 120C. It was observed that a reduction in desorption efficiency was caused by a decline in temperature.
~, 1 ;. . .
SUPPLEMENTARY DISCLOSURE
. _ The principal disclosure relates to the application of an electric current to used active carbon particles in the direction of movement of said particles through the space between two or more perforated electrodes. In this supple-mentary disclosure, further information is provided about the perforated electrodes and specific electrode types are described in connection with the accompanying drawings, in which:
FIG. 4 is a sectional view of one type of perforated electrode, illustrating the shapes of the holes therein;
FIG. 5 is a similar view to FIG. 4 but illustrating holes of different shape; and FIG. 6 is a similar view to FIG. 4 but illustrating in addition to holes, a number of hollow legs in communication with the holes.
In FIG. 4, 9 denotes an electrode and 10 a hole therein having taper 11 at the upper part thereof. In FIG. 5, 12 denotes an electrode plate and 13 a hole therein having a taper 14 and a taper 15 at the upper and lower parts thereof, respectively. If desired, only the lower parts of the holes may be tapered outwardly towards the lower electrode surface.
The electrodes may have a number of hollow legs ~
or tubular extensions on the undersides thereof in communication with the holes therein, as shown in FIG. 6. Each of the legs ordinarily has a length in the order of 300 mm. In FIG. 6, 16 denotes an electrode and 17 denotes a leg in communication with a hole in the electrode. The electrodes having a number of hollo~ legs on the undersides thereof are preferred in the present invention, because the mobility of the used active carbon flowing through the holes in the electrodes can be increased when such electrodes are used.
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for regenerating used active carbon which comprises:
(a) providing a generally vertical column containing at least two generally horizontal, vertically spaced electrodes, said electrodes having a plurality of holes large enough to allow passage of the used active carbon particles there-through and the total open area of said holes in said elec-trodes being at least 25% of the total surface area defined by said electrodes;
(b) introducing the used active carbon into the top of said column above the upper electrode and allowing the used activated carbon to flow downwardly through said electrodes;
and (c) applying a voltage between said electrodes to cause an electric current to flow through the carbon particles thereby heating said carbon to effect desorption of adsorped materials.
(a) providing a generally vertical column containing at least two generally horizontal, vertically spaced electrodes, said electrodes having a plurality of holes large enough to allow passage of the used active carbon particles there-through and the total open area of said holes in said elec-trodes being at least 25% of the total surface area defined by said electrodes;
(b) introducing the used active carbon into the top of said column above the upper electrode and allowing the used activated carbon to flow downwardly through said electrodes;
and (c) applying a voltage between said electrodes to cause an electric current to flow through the carbon particles thereby heating said carbon to effect desorption of adsorped materials.
2. The method according to the claim 1, wherein the particles of said used active carbon are generally spherical.
3. Apparatus for regenerating used active carbon particles, comprising a generally vertical hollow column containing at least two generally horizontal, vertically spaced electrodes, said electrodes having a plurality of holes large enough to allow passage of the used active carbon therethrough, the total open area of said holes in said electrodes being at least 25% of the total surface area defined by said electrodes.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
4. Apparatus according to claim 3, wherein the upper portions of said holes are outwardly tapered towards the upper electrode surface.
5. Apparatus according to claim 3, wherein the lower portions of said holes are outwardly tapered towards the lower electrode surface.
6. Apparatus according to claim 3, wherein the upper and lower surfaces of said holes are outwardly tapered towards said upper and lower electrode surfaces respectively.
7. Apparatus according to claim 3, wherein the electrodes have hollow projections extending from the lower surfaces thereof, said projections defining passages communicating with said holes.
8. A method according to claim 1, wherein the particles are allowed to flow downwardly through electrodes in which the holes have upper portions which taper outwardly towards the upper electrode surfaces.
9. A method according to claim 1, wherein the particles are allowed to flow downwardly through electrodes in which the holes have lower portions which taper outwardly towards the lower electrode surfaces.
10. A method according to claim 1, wherein the particles are allowed to flow downwardly through electrodes in which the holes have upper and lower portions which taper outwardly towards the upper and lower electrode surfaces respectively.
11. A method according to claim 1, wherein the particles are allowed to flow downwardly through electrodes having hollow projections extending from the lower surfaces thereof, said projections defining passages communicating with said holes.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP50048301A JPS51122691A (en) | 1975-04-21 | 1975-04-21 | Process for thermal regeneration of used active carbon by applying ele ctricity directly |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1073432A true CA1073432A (en) | 1980-03-11 |
Family
ID=12799602
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,446A Expired CA1073432A (en) | 1975-04-21 | 1976-04-20 | Method of regenerating used active carbon |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS51122691A (en) |
| CA (1) | CA1073432A (en) |
| DE (1) | DE2617176C3 (en) |
| FR (1) | FR2308589A1 (en) |
| GB (1) | GB1494162A (en) |
| IT (1) | IT1062068B (en) |
| NL (1) | NL176249C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2438850B (en) | 2006-04-28 | 2010-04-21 | Univ Manchester | Liquid treatment apparatus |
-
1975
- 1975-04-21 JP JP50048301A patent/JPS51122691A/en active Granted
-
1976
- 1976-04-20 CA CA250,446A patent/CA1073432A/en not_active Expired
- 1976-04-20 DE DE2617176A patent/DE2617176C3/en not_active Expired
- 1976-04-20 NL NLAANVRAGE7604138,A patent/NL176249C/en not_active IP Right Cessation
- 1976-04-21 IT IT22504/76A patent/IT1062068B/en active
- 1976-04-21 FR FR7611720A patent/FR2308589A1/en active Granted
- 1976-04-21 GB GB16212/76A patent/GB1494162A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS51122691A (en) | 1976-10-26 |
| DE2617176B2 (en) | 1978-04-27 |
| FR2308589B1 (en) | 1980-06-20 |
| DE2617176A1 (en) | 1976-10-28 |
| NL176249C (en) | 1985-03-18 |
| NL7604138A (en) | 1976-10-25 |
| JPS5619286B2 (en) | 1981-05-07 |
| FR2308589A1 (en) | 1976-11-19 |
| DE2617176C3 (en) | 1979-02-01 |
| NL176249B (en) | 1984-10-16 |
| GB1494162A (en) | 1977-12-07 |
| IT1062068B (en) | 1983-06-25 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |