US3073775A

US3073775A - Electric treater

Info

Publication number: US3073775A
Application number: US763650A
Authority: US
Inventors: Logan C Waterman
Original assignee: Petrolite Corp
Current assignee: Baker Petrolite LLC
Priority date: 1953-06-05
Filing date: 1958-09-26
Publication date: 1963-01-15
Anticipated expiration: 1980-01-15

Description

Jan. 15, 1963 L. c. WATERMAN 3,073,775

ELECTRIC TREATER Original Filed June 5', 1953 2 Sheets-Sheet 1 INVENTOR. Loan/v C. WHTRMHN BY HIS HTTORNEKS. HARRIS, K/ECH, Fos TER' a HfiRR/S Original Filed June 5', 1953 2 Sheets-Sheet 2 /N VENTOR. Lesa/v C. WHTERMHN BY HIS ATTORNEYS.

W428 Hn RR/s, K IECH, Fos TER 0Hnems United States Patent f 3,073,775 ELECTRIC TREATER Logan C. Waterman, Houston, Tex., assignor to Petrolite Corporation, Wilmington, Del., a corporation of Delaware Original application June 5, 1953, Ser. No. 359,795, now Patent No. 2,897,251, dated July 28, 1959. Divided and this application Sept. 26, 1958, Ser. No. 763,650

Claims. (Cl. 204302) My invention relates to the electric treatment of oilcontinuous dispersions and, more particularly, to a novel apparatus which will be illustrated as acid treatment of petroleum distillates. It should be understood, however, that the invention is not limited thereto, being applicable to the electrical treatment of various dispersions or emulsions in which the external or continuous phase is an oil or a fraction, distillation product or residuum obtained therefrom, whether or not containing a solvent or diluent. The internal or dispersed phase of the emulsion may be any liquid sufficiently immiscible with the external-phase material to exist therein as dispersed particles or droplets. The present application is a division of my application Serial No. 359,795, filed June 5, 1953, now Patent No. 2,897,251.

The invention relates to an electric treater of particular utility in the relatively new process for the super-treatment of dispersions, including emulsions. This super-treatment makes possible the removal of the dispersed-phase material to an extent not possible with older commercial processes.

In the electrical treatment of dispersions, it is often desirable to subject the dispersion to successive electric fields which may be of different character. It is an object of the present invention to provide a versatile treater in which this can be accomplished. In this connection, the invention includes among its objects the provision of an electric treater having unique arrangements of electrodes and electric fields by which a super-treating action can be eifected.

Unexpected results are obtained when advancing dispersions through relatively narrow side-by-side treating spaces in which are established high-voltage unidirectional electric fields. Thereby, it is often possible to reduce the residual dispersed material to values as low as a few hundredths of a percent or less. When treating lighter petroleum oils, it is often possible to reduce the residual material to less than a few thousandths of a percent and usually to obtain completely clear products. With heavy crude oils or lubricating oils, the residual material may be in the neighborhood of a few tenths of a percent. In all such instances, however, the residual material can be much less than would be the case if the dispersion were subjected to a treatment in an AC. field in a conventional electric treater.

Modern electric treaters of conventional design produce electric fields which are substantially more intense adjacent one electrode than adjacent the other. Such treaters also recirculate the constituents of the dispersion through the electric field for repeated treatment. In addition, such treaters have been designed to maintain a high degree of turbulence in the electric field. In the super-treatment of dispersions, including emulsions, it is desirable to employ fields of substantially uniform voltage gradient measured along paths joining the electrodes and to avoid both the promiscuous turbulence in the electric fields of prior art treaters and the recirculation of the constituents through the field. By proper design, a large stream of dispersion can be divided into a plurality of streams flowing through open-ended treating spaces disposed side-by-side. The how of the large stream can be straightened so that the smaller streams flow substanemployed in the Patented Jan. 15, less tially non-turbulently along the treating spaces wherein they are subjected to a unidirectional electric field.

The action in such unidirectional electric field is predominantly one of coalescing the dispersed particles or droplets into larger masses of sufiicient size to gravitate from the system, as contradistinguished from any proposal to remove the dispersed particles or droplets by electrophoretically depositing them on one of the electrode surfaces.

It is an important object of the present invention to provide an electric treater which can, if desired, be used in the super-treatment of dispersions. A further object is to provide a novel distribution system by which the dispersion is introduced into an entrance zone of the treater. A further object is to use such a distribution means in conjunction with a collector means in an exit zone of the treater for the purpose of establishing a uniform flow of the dispersion in a treating zone between the entrance and exit zones.

In one of its aspects the invention provides an improved means for advancing a passage-filling stream along a passage, such means including a dispersion-discharge means comprising a plurality of inverted buckets disposed around the axis of the passage and pipe means for discharging a stream of the dispersion into each of such buckets, each bucket providing an open end facing away from a zone of treatment containing electrode means for electrically treating the dispersion.

The invention includes also a plurality of electrode members having central portions secured to a support means, each electrode member providing first and second end portions extending oppositely from the support means and respectively substantially parallel to an axis, and first and second auxiliary electrode sets each comprising a plurality of substantially parallel electrode members spaced from each other distances substantially equal to the spacing of said first and second end portions, together with means for mounting the first and second auxiliary electrode sets with their electrode members respectively xtending into and substantially bisecting the unobstructed spaces of the first and second end portions to form first and second sets of treating spaces spaced along said axis in which electric fields are established and through which the dispersion stream flows in sequence.

Further objects and advantages of the invention will be evident to those skilled in the art from the following description of an exemplary embodiment, designed particularly for use in the acid treatment of distillates.

Referring to the drawings:

FIG. 1 is a vertical sectional view of one embodiment of the invention;

FIG. 2 is a horizontal sectional view line 2-2 of FIG. 1;

FIG. 3 is an enlarged vertical sectional view of one of the insulator housings of FIG. 1;

FIG. 4 is a diagrammatic view of a similar electric treater having a modified distribution system for the incoming dispersion;

FIG. 5 is a fragmentary view taken of FIG. 4; and

FIGS. 6 and 7 are fragmentary views of alternative distribution systems as viewed in the same plane as FIG. 4.

The electric treater of the invention is shown as including a vessel 10 of unique form having a relatively short cylindrical side wall 11, a domed cover 12 and a tapered lower section '13 ending in a well 14 from which separated acid sludge is withdrawn through a pipe 15, as will be described.

In the exemplified acid treating process, proportioning pumps 16 and 17 respectively deliver streams of distillate and acid under pressure to a mixer 18 of any suitable taken along the along the line 55 type. The resulting dispersion may be relatively stable or unstable but is continuously delivered through a valve 19 to a pipe 20 terminating in a manifold 21 disposed in an entrance zone 23 of the vessel 10.

Means is provided for distributing this dispersion in the entrance zone 23 so that it will flow upwardly as a large passage-filling stream through a treating zone 24 to an exit zone 25. It is desirable that the upward velocity at all radial positions in this large stream should be substantially uniform. The present invention accomplishes this by appropriately designed distribution and collection systems, the former including a plurality of pipes 26 radiating from the manifold 21 and providing up-turned nipples or nozzles 27 developing substantially no pressure drop when the dispersion flows therethrough. Each nozzle is covered by an inverted cup-like member or inverted bucket 29 having an open lower end 30 facing away from the treating zone 24. As a consequence, the stream of dispersion issuing from each nozzle 27 is deflected to flow downwardly around the lowermost lip of the corresponding inverted bucket 29. This method of distributing the incoming dispersion has been found to be very satisfactory, particularly if the centers of the inverted buckets 29 are at a radial position about two-thirds the radius measured from the central axis AA of the vessel to the cylindrical wall 11, e.g., at what may be called the median-volume radius of the cylindrical wall 11.

It is desirable that the passage-filling stream of the dispersion should move only once through the treating zone, as distinct from a design in which portions of the dispersion would be recirculated. To aid in accomplishing this, the invention is shown as including a withdrawal or collection means in the exit zone 25 comprising a plurality of perforated pipes 32, preferably six or eight in number, radiating from and communicating with a manifold 33 formed between inner and outer members 34 and 35 concentric with the axis AA. The members 34 and 35 are secured to a fitting 36 welded to the cover 12. It is preferred that the perforations in each pipe 32 be progressively closer together toward the outer end of the pipe. Preferably the area of all of the perforations in a particular radial zone will be proportional to the square of the radius of this zone. The volume of treated oil collected at any radial position Will then be substantially proportional to the square of the radius of such position, thus aiding in producing a rising column of liquid below the collector moving upwardly with substantially the same velocity at all radial positions.

The treated oil entering the perforations of the pipes 32 flows to the manifold 33 and is Withdrawn from the vessel 10 through a pipe 38 equipped with a valve 39. This valve is controlled to maintain an adjustable pressure in the vessel 10 as a back pressure against the pumps 16 and 17. This may be accomplished by transmitting the pressure from the pipe 38 upstream of said valve through a pipe 42 to a controller 43. The pressure in this pipe operates the controller 43 and adjusts the amount of compressed air entering the controller through the pipe 45 and delivered through a pipe 46 to a diaphragm unit 47 connected to the valve 39 to move same toward closed position upon increase in pressure in the pipe 42 and vice versa.

Similarly, the acid sludge separating in the vessel 10, as will be later described, is continuously or intermittently withdrawn through a valve 50 in the pipe 15, the valve being controlled to maintain the sludge interface 51 between predetermined limits. FIG. 1 shows the sludge interface 51 in substantially normal position, the

dotted lines

51a and 51b indicating the extreme uppermost and lowermost positions beyond which the interface should not move. A glass float 53 is internally weighted to sink in the liquid above the interface 51 and float in the sludge below the interface. This float 53 is carried by an arm 54 pivoted about an axis 55 and operates an air valve in a controller 56 to which air is supplied through a pipe 57. The effluent air, controlled by the valve, is delivered by a pipe 58 to a diaphragm unit 59 operatively connected to the valve 59. The relationship is such that a rise in the sludge interface will move the valve 50 toward open position and vice versa, thereby maintaining the sludge level substantially uniform in the lower end of the vessel 10.

The passage-filling stream of dispersion is electrically treated in the treating zone 24 by being subjected to appropriate electric fields which coalesce the acid sludge or other dispersed-phase material into masses of suflicient size to gravitate from the rising stream to collect in the lower end of the vessel 10. To establish these electric fields and also to straighten the flow of the rising passagefilling stream of dispersion, the invention employs a novel electrode means in the treating zone 24. This electrode means includes an intermediate electrode set 65, a first or lower auxiliary electrode section or set 66 and a second or upper auxiliary electrode section or set 67.

The intermediate electrode set is an electrode common to the sections or sets 66 and 67. It includes a plurality of cylindrical electrode members 63 having central portions perforated to receive a support means shown as including a plurality of radially extending narrow arms 69. These arms may be rectangular in cross-section and are preferably of greater height than Width and each arm is welded to each of the electrode members 63 at the junction. The innermost ends of these arms 69 are welded or otherwise secured to an innermost cylindrical electrode member 70 which, together with the other electrode member 68, is mounted concentric with the axis AA of the vessel 10. The outermost portions of the arms 69 rest on and are bolted to projections 71 Welded to the vessel 10 and through which the intermediate electrode set 65 is electrically connected to the vessel.

It will be observed that the arms 69 are mounted as cantilevers from the projections 71 and that there is no other vertical support for the innermost electrode member 70. The intermediate electrode set 65 should be rigid in a horizontal plane so as not to sag in its central portion. At the same time, the arms 69 should have a minimum width so as not to interfere with the rising stream of the liquid undergoing treatment. The arrangement shown permits the use of very narrow arms 69 while still obtaining a rigid structure. In this connection, each cylindrical electrode member 68 stiifcns each arm 69 at the welded junction thereof, particularly because the electrode member is curved. Tne welding of the inner ends of the arms 69 to the innermost electrode member 70 also rigidities the structure.

Each of the cylindrical electrode members 63 and 76 provides first and second or lower and

upper end portions

72 and 73 extending oppositely from the support means formed by the arms 69. The end portions 72 are respectively parallel to the axis AA, as are also the end portions 73 which are preferably continuations of the portions 72. The portions 72 are spaced from each other to define unobstructed spaces facing away from the support means, the same being true of the end portions 73. These spaces are of substantially equal width and face respectively downwardly and upwardly. The portions 72 include edges 74 facing upstream of the passagefilling stream of dispersion.

The first or lower auxiliary electrode set 66 is supported by a support means 75 to be described and comprises an interstitial framework 76 carrying tip-standing substantially parallel cylindrical electrode members '77 spaced apart substantially the same distance as the electrode members 68. The electrode members 77 extend respectively into the substantially unobstructed spaces between the end portions 72, substantially bisecting these spaces to form a set of lower treating spaces 78 between the overlapping portions of the

electrode members

68 and 77. Edges 79 at the bottom of the electrode members 77 serve as stream-splitting edges as do also the edges 74 of the end portions 72 of the electrode members 68. Portions of the

electrode members

68 and 77 re spectively adjacent these edges serve as flow-straightening means, tending to damp out transverse components of motion in the stream rising in the entrance chamber 23.

The second or upper auxiliary electrode set 67 includes a support means 82 to be described, an interstitial framework 83 and a plurality of cylindrical electrode members 84 radially spaced the same as the electrode members 77 but depending from the framework 83. The electrode members 84 substantially bisect the upwardly facing unobstructed spaces between the portions 73 of the intermediate electrode set 65 and cooperate in defining a second or upper set of treating spaces 85 in which the super-treatment of the dispersion is effected. The extreme ends of the electrode members 84 comprise edges 86 spaced from the arms 69. The same is true as to the extreme upper edges 87 of the electrode members 77. By the time the stream is passing through the treating spaces 85, it is moving with substantially laminar flow due to the flow-straightening action of all of the

electrode members

68, 77 and 84.

The support means 75 and 82 comprise means for respectively energizing the lower and upper electrode sets 66 and 67 to maintain a high-potential difference between these sets and the intermediate electrode set 65. The support means 75 and 82 also include novel arrangements of insulators, as Will now be described.

The support means 75 includes a member or rod 90 extending centrally through the innermost cylindrical member 70 and connected to the framework 76 by any suitable means. If desired, this means may be a plate 91 which substantially blocks upward flow of the dispersion through the innermost cylindrical member 70 or it may be foraminous to permit flow through such cylindrical member. suspending the member 90 and the lower auxiliary electrode set 66 is a conductor 92 which extends upwardly through the lower open end of an insulator housing 94 connected to the top of the fitting 36 and closed at its upper end by a closure plate 95. As best shown in FIGS. 1 and 3, a support in the form of a flange 96 is welded or otherwise secured in the housing at a position intermediate its ends. An insulator 98 formed of ceramic or other electrical insulating material is secured in fluid-tight relationship with the support 96 by a collar 99. The collar 99 may be separated from a neck of the insulator by a suitable sealing material 100 and may be separated from the support 96 by a gasket 101, thereby eifectively dividing the interior of the housing 94 into upper and

lower zones

102 and 103.

The insulator 98 is preferably supported at an intermediate position so as to provide an upper portion 104 exposed to the zone 102 and a lower portion 105 exposed to the zone 103. The insulator 98 is preferably a cylindrical member having a passage 107 extending longitudinally therethrough, this passage being substantially larger in cross-sectional area than the conductor 92. A flanged cap 108 engages the top of the upper portion 104 and provides an opening slidably receiving the conductor 92. The upper end of this conductor is threaded and receives a nut 109 which can be turned to adjust the vertical position of the lower auxiliary electrode set 66. The conductor 92, the cap 108 and the upper portion of the insulator 98 are sealed in fluid-tight relationship as by gaskets or washers. By this arrangement the

zones

102 and 103 are effectively sealed from each other. Also, any weight applied to the conductor 92 will result in compressive forces in the upper portion 104 of the insulator. Furthermore, the hollow insulator construction provides a very long leakage path between the cap 108 and the flange 96. This results in part from the conductor 92 being of substantially smaller diameter than the passage 107 and is desirable in preventing flash-over of the insulator 98.

The pressure in the vessel normally would tend to force the treated oil upwardly in the housing 94 to contact the lower portion of the insulator and fill an annular chamber 110 within the housing around such lower portion and around a portion of the conductor 92. This contact between the treated liquid and the insulator may give rise to surface contamination and electrical failure of the latter. The present invention provides for maintenance of a body of dielectric fluid, preferably a body of dielectric gas, in the annular chamber 110 under such pressure as will maintain the treated oil a distance below the lower portion 105 of the insulator 98. The dielectric fluid and the treated liquid will separate at an interface, indicated by the numeral 111, if they are immiscible. It is desirable that the position of this interface be main tained substantially constant by control of the amount or pressure of the dielectric fluid in the annular chamber 110. This is almost impossible to accomplish by use of an automatic valve responsive to level of an interface and serving merely to add an increment of dielectric fluid to a static body thereof to compensate for a deficiency in amount or pressure of such dielectric fluid. This is due in part to the fact that it is usually not possible to make such a valve close completely, thus permitting gradual leakage and destroying accurate control of the position of the interface. To solve this problem and to circulate the dielectric fluid through the annular chamber 110 to remove any material that might be transferred from the treated oil through a stagnant body of dielectric fluid to the surface of the insulator, I prefer to use a dynamic system in which a dielectric fluid continuously circulates through the annular chamber 110. This dielectric fluid is preferably a gas, e.g., compressed air or any inert gas such as helium, nitrogen, carbon dioxide or even an electro-negative gas such as sulphur hexafluoride. In commercial practice, compressed air has been found to be quite satisfactory where there is no explosive hazard.

A compressed gas, such as air, is derived from a pipe and is reduced in pressure by an adjustable constantpressure valve means 116 to maintain the pressure in a pipe 117 slightly above the pressure at which the

valves

39 and 50 are set. A valve 118 in the pipe 117 is controlled by a level responsive means 120 which includes a float 121 sensitive to changes in level of the interface 111 and operatively connected to the valve 118 to control the flow of the gas through a pipe 122 to a manifold 123. The level responsive means 120 is of any conventional form, being illustrated as including a housing 124 interconnected by pipes 125 and 126 to the interior of the housing 94 at levels above and below the desired position of the interface 111. A corresponding interface Will be present in the housing 124 and will control the position of the float 121. Any other level responsive means can be employed to control the valve 118 and thus control the flow and pressure in the pipe 122.

A pipe 127 conducts gas from the manifold 123 to the annular chamber 110. This pipe forms a part of a circulation means for continuously circulating the gas through the annular chamber, usually in laving relationship with the lower portion 105 of the insulator. An exit pipe 128 communicates with another portion of the annular chamber 110 and conducts the eflluent gas to a manifold 129. The gas normally flows through an adjutsable constant-pressure valve 130 which maintains the pressure in the manifold 129 at a set value. The escaping gas is discharged at atmospheric pressure into a sample box or funnel 132 which is connected to a sewer line and which permits inspection of any stream discharged into the funnel. A by-pass valve 133 is connected around the valve means 130 and is useful in initially filling the vessel.

The support means 82 of the upper auxiliary electrode set 67 includes three equally-spaced conductors 135 extending upwardly into respectively spaced housings similar to the housing 94. In FIG. 1 two of these housings are shown, indicated respectively at 136 and 137. A third housing, identical in construction with the housing 137, is omitted for purpose of clarity. The construction of these three housings will be apparent from the sec tional showing of the housing 136 of FIG. 1.

The housing 136 contains an insulator 138 of the form previously described. Compressed gas is circulated through an annular chamber 139, entering this chamber through a pipe 145? connected to the manifold 123 and leaving the chamber through a pipe 141 exhausting into the manifold 129 Similar pipes circulate streams of the compressed gas from the manifold 123 to each of the remaining two housings, the gas exhausting to the manifold 129. By controlling the gas flow in response to the requirements needed to maintain one interface at a constant level, e.g., the interface 111 in the housing 94, the flows through the remaining annular chambers will maintain the interfaces therein at substantially the same level.

In each of the four housings it is desirable that the outer zone 102 be filled with a dielectric fluid and that the pressure thereof be maintained substantially equal to the pressure in the corresponding annular chamber around the lower portion of the insulator. I prefer to fill each outer zone 10-2 with a dielectric liquid to surround and protect from flash-over the upper portion 164 of the insulator. To maintain the pressures in these outer zones equal to each other and to the pressure in the corresponding annular chambers, e.g., 110 and 139, each outer zone is connected by a pipe 145 with the manifold pipe 123. Each outer zone 102 may be filled with a dielectric liquid by removing a cap 146 of a fitting 147 to which the corresponding pipe 145 is connected. Alternatively, each outer zone 102 may be filled or flushed by use of

valved pipes

148 and 149 communicating with upper and lower portions of this zone.

The

housings

94 and 135 provide means for conducting high potentials to the lower and upper electrode sets respectively. This means includes a high-voltage inlet bushing 150 carried by the closure 95. Each inlet bushing includes a tube of insulating material 151 (see FIG. 3) connected at its upper end to the closure 95 by a suitable fitting 153 to which is also connected a high-voltage cable 154, the lead or conductor of this cable extending through the tube of insulating material 151 and being electrically connected to a terminal 155. This terminal engages and compresses the upper end of a spring 156 which electrically interconnects the terminal to the cap 103. The insulating liquid surrounds and protects against flash-over the exterior surface of the tube of insulating material 151.

The inlet bushings in the housings 94- and 136 are identical. The higlnvoltage cables 154' are connected to separate

potential sources

160 and 161 respectively. Each potential source includes one terminal which is grounded and which is correspondingly connected to the intermediate elect-rode set 65 through a ground connection 162 for the vessel 10. Each potential source has a high-voltage terminal connected through its respective cable to the respective electrode set.

To obtain a super-treating action in the treating spaces 85, it is essential that the potential source 161 be unidirectional. The electric fields in the treating spaces '78 may also be unidirectional, in which event the potential source 169 may be substantially identical with the source 161 or a unidirectional source of somewhat lower potential. However, the electric fields in the treating spaces 78 serve the primary function of preparing the dispersion for treatment in the treating spaces 85, as by coalescing an initial portion of the dispersed particles so that these can separate gravitationally before the residual dispersion enters the super-treating fields in the treating aces 85. In many instances alternating-current fields will sufi'ice in the treating spaces 78. In that event, the potential source 160 may be a high-voltage transformer. If its peak poundergoing treatment and the effluent materials.

tential is equal to the unidirectional potential of the source 161, the electrode arrangement produces a unique relationship of electric fields. The dispersion will first be subjected to an alternating field in the treating spaces 78. It will then be subjected to a double-voltage pulsating DC. field between the

edges

56 and 87. Finally, it will be subjected to the-uniform-gradient unidirectional electric fields in the treating spaces 85. This combination of fields has been found very efficacious in the treatment of certain distillates.

In considering the general operation of the treatcr, it will be apparent that the passage-filling stream of dispersion will be quite turbulent in the entrance zone 23. However, due to the flow-straightening action of the lowermost portions of the

electrode members

68 and 77, this turbulence will be substantially completely damped out and the flow will be essentially laminar in the treating

spaces

78 and 85, particularly in the latter where such flow is desirable to achieve a super-treating action. During the time the dispersion is between these sets of treating spaces, it is kept from reassuming excessive turbulent flow by the stream-separating central portions of the electrode members d8.

It is often desirable to be able to sample the material For this purpose the invention may provide a small valved line 19b conducting a sample of the incoming dispersion to the funnel 132. The condition of the dispersion at a position near the arms 69 can be determined by a valved sample line 191 which provides a portion 192 traversing several of the outermost electrode members 68. This sample line may provide a pressure gauge 193 showing the existing pressure in the vessel 10. A valved sample line 194 can deliver a sample stream of the separated acid sludge to the funnel 132 for observation. Similarly, a valved sample line 195, shown divided in FIG. 1, may conduct treated oil from the pipe 38 to the funnel 132.

In electrical distillate-treating processes, it is often of importance that the volume of the treating vessel be a minimum. In some processes, for example, it is important that the dispersed phase be removed from contact with the oil in a minimum of time. When shifting from one oil to another, it is also important that the treater volume be a minimum consistent with a desirably large throughput. The treater of the invention has many advantages in this connection. The compactness of the electrode structure, the relatively small space between the uppermost electrode unit and the cover 12, and the small volume of the vessel below the lowermost electrode unit are important. Minimum volume in the lower end of the vessel is made possible not only by the disclosed close spacing of the elements but also by the conical or tapered lower section 13. The latter minimizes the amount of sludge in the vessel and minimizes the area of the interface 51, leading to less degradation of the treated oil. Furthermore, the tapered lower section 13 is disposed at such an angle that a mass of acid sludge will slide or settle therealong to drain into the well 14 and thence into the pipe 15.

It is also desirable that the treater may be drained and refilled with a minimum of effort. Draining of the treater is ordinarily no problem but it is very desirable that the

housings

94, 136, 137, etc., should fill almost automatically and entrap bodies of gas in the respective annular chambers even before the gas or other dielectric fluid is circulated through the valves 116 and 130. This is particularly important when it is remembered that neither the interface 111 nor any of the corresponding interfaces should ever be allowed to rise into contact with or submerge the lower portions of the insulators. The following description will indicate superior features of the present invention in such respects.

As the vessel It is being initially filled, the incoming liquid will displace the gas in the upper end of the vessel through suitable vents. So long as any of the perforations of the collector pipes 32 remain not submerged, the gas 9 will escape therethrough, passing through the manifold 33 and out the pipe 38 through the now-open valve 39. When these perforations are submerged, the gas may escape for a period through a pipe 205 having its lower open end depending into the tank to a level BB. This pipe opens into a larger pipe 206 in which is disposed a housing 207 similar to the housing 124. The pipe 206 opens on the pipe 38 and discharges gas therein until the liquid level in the tank rises above the level B-B to submerge the lower end of the pipe 205. Thereafter, any gas entrapped in the upper end of the vessel can escape only through a weep hole 209 in the fitting 36, entering the housing 94 and displacing liquid which may already have started to rise therein or in the fitting 36.

The valve 130 being closed, the interfaces 111 will form and rise in the

respective housings

94, 136, 137, etc., as the pressure builds up in the vessel 10 to a value above atmospheric pressure. This rising pressure will compress the masses of gas entrapped in the housings. The internal volumes of the housings are so designed, with reference to the operating pressure in the vessel 10', that the interfaces will assume approximately their ultimate positions in their respective housings merely by bringing the interior of the vessel up to operating pressure. The system for circulating the dielectric fluid through the annular spaces of these housings can then be put into operation, the float 121 and the valve 118 controlling the continuous flow to adjust and maintain the interfaces in the desired positions.

It is also desirable to de-energize the electrode units should the level in the

housings

94, 136, 137 and 207 drop dangerously close to the upper end of the vessel 10. To accomplish this, a float 210 is disposed in the housing 207 and is operatively connected to float switches 211 and 212, respectively connected in the energizing circuits of the

potential sources

160 and 161. The housing 207 is positioned below the normal position of the interfaces 111. If an air-oil interface should form in the housing 207 and if this interface should drop sufficiently to lower the float 210, the

potential sources

160 and 161 Will be immediately de-energized to avoid any danger of explosion.

Another important feature of the invention is the manner in which the liquid is distributed to and withdrawn from the vessel to create a rising column which flows through the grid of'electrodes with substantially equal velocity at all radial positions. It has previously been proposed that the incoming dispersion should be jetted into the entrance zone 23, either from a central distributor or from a plurality of small holes in a perforated pipe system. The present invention proposes to introduce the dispersion at a limited number of positions in a narrow annular zone substantially at the median-volume radius of the entrance zone 23, usually at a radial position substantially two-thirds the distance from the axis A-A to the cylindrical wall of the treater. At the same time, the present invention contemplates use of a network of perforated pipes in the exit zone 25, typically the perforated pipes 32 previously described. Thus, while the incoming dispersion enters the entrance zone 23 in a rather narrow annular zone, the withdrawal of the treated oil from a pluarlity of radial positions and the passage of the intermediate vessel-filling stream through the annular treating

spaces

78 and 85 causes the rising stream to flow with substantially equal velocity at all radial positions. This action is assisted by the minute pressure drop from end to end of the electrode structure. Thus, even though the incoming dispersion is introduced primarily at the median-volume radius, the upward velocity of flow through the various treating spaces at different radial positions will be substantially equal. By medianvolume radius, I have reference to a radius such that the area inside the corresponding circle will substantially equal the area of the annulus around such circle within the cylindrical portion of the vessel.

These principles will be clear from the embodiment of FIG. 1 and also from the embodiment of FIGS. 4-7. In the embodiments of FIGS. 4 and 5, for example, the treated oil is withdrawn through the perforated pipes 32 and manifold 33 as before, but the incoming dispersion is introduced substantially at the median-volume radius of the vessel 10, e.g., at a radius about two-thirds the radial distance from the axis AA to the cylindrical wall of the vessel. This introduction of the dispersion is through side openings of pipe Ts 220 secured respectively to the outer ends of the pipes 26. The plane of the side openings of each T 220 is substantially horizontal and while short nipples or nozzles may be threaded into these side openings, I prefer to discharge the dispersion directly from the openings provided by the side arms of the pipe TS and with substantially no pressure drop due to flow through these openings. Ordinarily, six or eight pipes 26 will be used so that the incoming dispersion will be well distributed at different circumferential positions within the vessel.

Alternatively, the outer ends of the pipes 26 may provide elbows 222 each providing a single side opening, these side openings facing upwardly (FIG. 6) or downwardly (FIG. 7) or in some other direction.

It is very desirable that the dispersion-discharge open ings be relatively few in number, usually less than about sixteen, and that each of these openings be relatively large, usually not less than about 1 in diameter and typically 1-2, so as not to develop any substantial pressure drop. It is undesirable to jet the dispersion from the pipes 26 at high velocity both because this increases the turbulence in the entrance zone 23 and also because this requires a substantial pressure drop in the distribution system at the point of eflluence from the distributor. Such pressure drops have been found to induce clogging of the system, as by depositing foreign material in the.

discharge orifices so that they become progressively clogged. In prior practice, it has often been customary to employ a perforated-pipe distributor for the incoming dispersion, this distributor having a large number of small orifices. The pressure drop in such a system was in the neighborhood of 0.53 pounds per sq. in. In practice it has been found that materials from or carried by the incoming stream will tend to deposit in the distribution system, often acting progressively to block the discharge orifices and thus interfere with the previouslydesired introduction at a very large number of different radial positions. Also in prior practice, it has sometimes been proposed to withdraw the treated oil from a single outlet, there being very little pressure drop at this point.

In contradistinction, the present invention discharges the dispersion through a relatively small number of relatively large outlets or openings so that the pressure drop at this point is usually no more than a few ounces, being usually less than two ounces per sq. in. In the collector, formed by the perforated pipes 32, the pressure drop maybe in the neighborhood of 0.2-2.0 pounds per sq. in. (3.232 ounces per sq. in.), making the pressure drop in the collector at least about 1.646 times the pressure drop in the distributor largely as a result of the intentionally small size of the openings through which the treated oil passes. A pressure drop at this point is not detrimental and the concept of transferring the zone of pressure drop from the inlet zone 23 to the discharge zone 25 is important. Additionally, the distribution of orifices in the perforated pipes 32 makes entirely practicable the discharge of the incoming dispersion in a relatively narrow annular zone near the median-volume radius of the entrance zone of the treater.

Various changes and modifications can be made without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. A treating structure for the electrical treatment of oil-continuous dispersions, said treating structure including: a support means; a plurality of electrode members having central portions secured to said supportmeans, said central portions being formed of imperforate matcrial, said electrode members and said support means comprising an intermediate electrode set, each electrode member providing first and second end portions extending oppositely from said support means, the end portions of each electrode member being extensions of said central portion thereof, the first and second end portions of the electrode members being respectively substantially parallel to an axis and spaced from each other to define unobstructed spaces facing away from said support means; a first and second auxiliary electrode set each comprising a plurality of substantially parallel electrode members spaced from each other distances substantially equal to the spacing from each other of said first and second end portions of the electrode members of said intermediate electrode set; means for mounting said first and second auxiliary electrode sets with their electrode members respectively extending into and substantially bisecting said unobstructed spaces of said first and second end portions to form first and second sets of treating spaces spaced along said axis; means for flowing a stream of the dispersion through said sets of treating spaces in sequence; and means for applying a potential difference between said intermediate electrode set and each of said auxiliary electrode sets to establish electric fields in said sets of treating spaces.

2. A treating structure as defined in claim 1 in which all of said electrode members and said end portions of said intermediate electrode set are thin cylindrical members concentric with said axis, the electrode members of said first and second auxiliary sets providing edges facing but spaced from each other, the edges of said first and second auxiliary sets being on opposite sides of said support means and facing same.

3. A treating structure as defined in claim 1 in which the electrode members of said auxiliary electrode sets provide edges on opposite sides of said support means facing but spaced from each other, said support means comprising narrow widely-separated arms traversing and welded to said central portions of said electrode members of said intermediate electrode set so as to offer substantially no impedance to the flow of said stream of dispersion, said edges being spaced from said arms.

4. A treating structure as defined in claim 3 including means for electrically insulating each of said auxiliary electrode sets from said vessel and from each other, two potential sources each having a first terminal and a second high-voltage terminal, means for connecting said first terminals together and to said intermediate electrode set, and means for electrically connecting said high-voltage terminals respectively to said auxiliary electrode sets.

5. In an electric treater for oil-continuous dispersions,

the combination of: a closed vessel having infiuent andeifiuent means; an upper electrode set comprising a plurality of depending electrode members substantially parallel to an axis and spaced from each other, said depending electrodes having lower edges; a lower electrode set providing a plurality of tip-standing electrode members spaced from each other and substantially parallel to said axis, said upstanding electrode members being respectively below the electrode members of said upper electrode set, said tip-standing electrode members having upper edges spaced from said lower edges of said depending electrodes; means for electrically insulating each electrode set from said vessel; an intermediate electrode set comprising a plurality of electrode members of impervious material substantially parallel to said axis, each electrode member of said intermediate set providing an upper portion nested between the depending electrode members of said upper set to define an upper series of treating spaces, each electrode member of said intermediate set providing a lower portion nested between said electrode members of said lower set to define a lower series of treating spaces; mounting means for said electrode members of said intermediate set comprising arms of electrically conductive material extending from said vessel in the space between said upper and lower edges through aligned openings of the electrode members of said intermediate set in mounting relation; and means for establishing a potential difference between said electrode members of said intermediate set and said electrode members of both said upper and lower sets.

6. An electric treater as defined in claim 5 in which all of said electrode members are metal cylinders, and in which said intermediate electrode set includes an innermost cylindrical electrode, said arms providing inner ends terminating at and welded to said innermost cylindrical electrode.

7. An electric treater as defined in claim 5 in which all of said electrode members are metal cylinders concentric with a vertical axis, and in which the electrode members of said intermediate set include radially aligned openings of rectangular shape each greater in height than width, said arms being correspondingly rectangular in crosssection, said arms extending through said aligned openings and being welded to said electrode members of said intermediate set to rigidity said intermediate electrode set against sagging at its center.

8. In combination with spaced parallel electrodes defining upright side-by-side interelectrode treating spaces within a vessel of a high-voltage electric dispersion treater, the interelectrode treating spaces having high-voltage electric fields therein coalescing the dispersed-phase material of an oil-continuous dispersion containing a small percentage of such material dispersed in the oil phase of the dispersion, the coalesced material largely separating from the dispersion while in said electric fields and collecting as a body in the bottom of said vessel leaving a treated oil having a substantially smaller content of such dispersed-phase material rising in the upper ends of said interelectrode treating spaces, an arrangement for minimizing the pressure drop applied to the dispersion and inducing a substantial pressure drop on the treated oil to equalize the upward flows in said interelectrode treating spaces, said arrangement including: a dispersiondischarge pipe means in a lower portion of said vessel having a relatively small number of relatively largediameter dispersion-discharge openings communicating with the lower ends of said treating spaces; means for inducing a pressure drop on said treated oil at least about 1.6 l6 times the pressure drop across said discharge openings, said last-named means comprising a treated-oil collection means in an upper portion of said vessel, said collection means including a larger number of treatedoil-receiving exit openings in communication with the upper ends of said treating spaces and receiving said treated oil, said exit openings being of smaller crosssectional size than said discharge openings, said pressuredrop-inducing means including a pump means supplying the dispersion to be treated to said dispersion-discharge pipe means at a rate to create a small pressure drop across said dispersion-discharge openings and said pressure drop of at least about 1.6-16 times higher across said exit openings; means for conducting the thus-collected treated oil from said collection means to a position outside said vessel; and means for Withdrawing the coalesced and separated material from said body thereof.

9. A combination as defined in claim 8 in which the cross-sectional size of said discharge openings are such as to create a pressure drop of less than about 2 oz./sq. in. thereacross, and in which said exit openings are of a size to create a pressure drop about 2-2.0 lbs/sq. in. thereacross.

lO. A combination as defined in claim 8 in which each of said discharge openings is of a diameter not less than about 1 inch.

(References on following page) 13 References Cited in the file of this patent 2,033,167

UNITED STATES PATENTS V Harris June 2, 2 94 895 1,838,822 Gassaway Dec. 29, 1931 1,838,847 Lawrason Dec. 29, 1931 1,838,925 Fisher Dec. 29, 1931 472,511 2,033,129 Eddy Mar. 10, 1936 515,455

14 Worthington Mar. 10, 1936 Bailey Dec. 22, 1953 Stenzel Oct. 7, 1958 Turner July 14, 1959 FOREIGN PATENTS Italy June 23, 1952 Germany July 5, 1935

Claims

8. IN COMBINATION WITH SPACED PARALLEL ELECTRODES DEFINING UPRIGHT SIDE-BY-SIDE INTERELECTRODE TREATING SPACES WITHIN A VESSEL OF A HIGH-VOLTAGE ELECTRIC DISPERSION TREATER, THE INTERELECTRODE TREATING SPACES HAVING HIGH-VOLTAGE ELECTRIC FIELDS THEREIN COALESCING THE DISPERSED-PHASE MATERIAL OF AN OIL-CONTINUOUS DISPERSION CONTAINING SMALL PERCENTAGE OF SUCH MATERIAL DISPERSED IN THE OIL PHASE OF THE DISPERSION, THE COALESCED MATERIAL LARGELY SEPARATING FROM THE DISPERSION WHILE IN SAID ELECTRIC FIELDS AND COLLECTING AS A BODY IN THE BOTTOM OF SAID VESSEL LEAVING A TREATED OIL HAVING A SUBSTANTIALLY SMALLER CONTENT OF SUCH DISPERSED-PHASE MATERIAL RISING IN THE UPPER ENDS OF SAID INTERELECTRODE TREATING SPACES, AN ARRANGEMENT FOR MINIMIZING THE PRESSURE DROP APPLIED TO THE DISPERSION AND INDUCING A SUBSTANTIAL PRESSURE DROP ON THE TREATED OIL