US 2897251 A
Description (OCR text may contain errors)
.my 28, 1959l L. c. WATERMAN LEc'rRI vTHEATER 2 Sheets-Sheet 1 BY H15 HTTORNEYJ.
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United States Patent i ELECTRIC TREATER Logan C.'Waterman, Houston, Tex., assignor to Petrolite Corporation, Wilmington, Del., a 'corporation of Delaware Application `June 5, 1953 Serial No. 359,795
15 Claims. k(Cl. 174-16) My invention relates to the electric treatment of oilcontinuous dispersions and, more particularly, 'to a novel method and apparatus which will 'be illustrated as employed in the 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 residuurn obtained therefrom, whether cor not containing a solvent or diluent. The internal or dispersed phase of the emulsion may be any liquid suiciently immiscible with the external-phase material to exist therein as dispersed particles or droplets.
T he present invention relates to an electric :treater of particular utility in the relatively new process for the super-treatment of dispersions, including emulsions, `as disclosed and claimed in the -co-pending application of Richard W. Stenzel, Serial No. 281,541, now :Patent No. 2,855,35 6. This super-treatment makes vpossible 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 Vfields which may .be of different character. It is an object of the present invention to ,provide a versatile treater in 'which this can vbe accomplished. In this connection, the Vinvention includes -among its objects the provision of an electric treater having unique arrangements of electrodes and electric kfields by which a super-treating action can be effected.
As explained yin 'the co-'pendin'g application, supra, unexpected results are obtained when .advancing dispersions through relatively narow side-by-side treating spaces in which are established 'higliavoltage unidirectional electric iields. 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 tov reduce the residual material to vless than a few thousandths of a percent and usually to obtain completely clear products. Withheavy crude oils or lubricating oils, the residual material may 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 A;C. field in a conventional electric treater.
Modern electric treaters of conventionaldesign produce electric fields A,which are substantially more vintense adjacent one Aelectrode 'than adjacent the other. Such treaters also recirculate the constituents of the dispersion through the electric yield vrforrepeated treatment. In addition, such treaters have kbeen designed to maintain a high'degree offturbulence lin the electric field. As pointed out in the Stenzel application, supra, the super-treatment of dispersions, including emulsions, desirably employs eldsof substantially uniform voltage gradient measured along Vpaths Ajoining the yelectrodes 'and avoids both the ICC promiscuous turbulence in the electric elds -of prior art treaters and the recirculation of the constituents through the iield. By proper design, a large stream of dispersion can be divided into a plurality of streams flowing vthrough open-ended treating spaces disposed side-by-side. The flow of the large stream can be straightened lso 1that the smaller streams flow substantially non-turbulently along the treating spaces wherein they `are subjected to a unidirectional electric field.
The action in such unidirectional electric eld -is predominantly one of coalescing 'the `dispersed particles lor droplets into larger masses of suflicient size to gravitate from the system, as contradistinguished from 4any proposal to remove the 'dispersed yparticles or droplets by electrophoretically depositing them on one of the electrode surfaces.
It vis :an important object of the present invention to provide an electric treater which can, if desired, be used inthe super-treatment of dispersions. A further object yis .to provide a novel distribution system :by which `the dispersion is Aintroduced 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 ow of the dispersion in a treating zone between the `entrance and 'exit zones.
In the electrical treatment of certain dispersions, there is a distinct problem in introducing high potentials into the treater and protecting the insulators from Hash-over. In lconventional treaters, the insulators, which may comprise ksuspension insulators, inlet bushings, etc., are usually in contact with the treated liquid in the upper portion of the tank. It is an object of the present invention `to isolate the insulators from such liquid in a 'unique way.
A further object is to position each `insulator in a Vseparate housing, the treated liquid tending to `rise in lsuch housing, and to control the introduction of a uid to said housing to surround and protect the insulator rfrom the liquid in the treater. A further object is to maintain the liquid in the treater displaced from the insulator by use of a circulation of fluid, typically a dielectric gas, through the housing; also to control the pressure of such uid in the housing so as to maintain substantially constant in position any interface that is `present ybetween such Huid and the liquid in the treater.
A further object of the invention is to dispose an .upper portion of the insulator in an upper or outer zone of the housing sealed from the lower or inner zone of the housing which communicates with the interior of ,the .treater and which contains a lower portion of the insulator; also to protect this upper portion of the insulator, and if desired the inner portion of a high-voltage bushing extending into the upper zone, by filling such upper zone with clean oil or other dielectric fluid. A further object ofthe invention is to substantially equalize the pressures in suc'h upper and lower zones; also to provide a treater 4having a plurality of such housings and to .control 'the flow of a dielectric fluid to each housing in response to changes in position of the interface in a single housing.
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. l is a vertical sectional View of one embodiment of the invention;
Fig. 2 `is a horizontal sectional view taken along th line 2--2 of Pig. l;
Fig. 3 is an enlarged Lvertical sectional view-of one of the insulator housings of Fig. l;
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 along the line 5-5 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.
y In the exemplied acid treating process, proportioning pumps 16 and 17 respectively deliver streams of distillate and acid under pressure to a mixer 1S of any suitable type. The resulting dispersion may be relatively stable or unstable but is continuously delivered through a valve 19 to a pipe 2li 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 ow 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 iiow downwardly around the lowermost lip of the corresponding inverted bucket 2.9. 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 twothirds the radius measured from the central axis A-A 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 A-A. 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. l 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 oat 53 is internally weighted to sink in the liquid above the interface 51 and iioat in the sludge below the interface. This iioat 53 is carried by an arm 54 pivoted about an axis 55 and operates an air valve in va 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 50. 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-lling stream 4of 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 sufcient size to gravitate from the rising stream to collect in the lower end of the vessel 10. ToA establish these electric fields and also to straighten the flow of the rising passage-filling 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 set 66 and a second or upper auxiliary electrode set 67.
The intermediate electrode set 65 is a common grounded electrode. It includes a plurality of cylindrical electrode members 68 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 68 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 members 68, is mounted concentric with the axis A-A 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 stilfens each arm 69 at the welded junction thereof, particularly because the eletcrode member is curved. The welding of the inner ends of the arms 69 to the innermost electrode member 70 also rigidiiies the structure.
Each of the cylindrical electrode members 68 and 70 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 A-A, 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 passage-filling 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 up-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 Kunobstructed spaces between the end portions 72, substantially bisecting these spaces to form a set of lower treat-ing spaces 78 between the overlapping portions 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 respectively adjacent these edges serve as flow-straightening means, tending to damp out ytransverse 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 lis 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 65, 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 l 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 lthe fitting 36 and closed at its upper end by a closure plate 95. As best shown in Figs. l and 3, a support in the form of a ange 96 lis 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 effectively 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 E103. 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 lan opening slidably receiving the conductor 92. The upper end o'f this conductor is threaded and receives a nut 109 which can be turned to adjust lthe 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 iiuid-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 `10 normally would tend to force the treated oil upwardly in the housing 94 to contact the lower portion of the insulator and ll 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 elec* trical failure of the latter. The present invention pro` vides for maintenance of a body of dielectric fluid, preferably a body of dielectric gas, in the annular chamber 110 under such pressure as fwill 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 maintained substantially constant by control of 'the amount or pressure of the dielectric fluid in the annular chamber 110. This is almost impossible to accomplish lby 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 sys* tem in which a dielectric fluid continuously circulates through the annular chamber 110. This dielectric uid is preferably a gas, eg., compressed air or any inert gas such as helium, nitrogen, carbon dioxide or even an electro-negative gas such as sulphur hexauoride. 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 fioat 121 sensitive to changes in level of the interface 111 and operatively connected to the valve 118 to control the ow 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 inter face 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 ow 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 12S communicates with another portion of the annular chamber 110 and conducts the efiiuent gas to a manifold 129. The gas normally flows through an adjustable 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. l 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 sectional showing of the housing 136 of Fig. l.
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 `141] 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 elevel, e.g., the interface 111 in the housing 94, the fiows 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 152 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 lill each outer zone 102 with a dielectric liquid to surround and protect from ,flash-over the upper portion 1114 of the insulator. To maintain the pressures in these outer zones equal to each other and to the pressure in the corresponding annular chambers, eg., 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 136 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 ybushing 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 10S. The insulating liquid surrounds and protects against ash-over the exterior surface of the tube of insulating material 151.
The inlet bushings in the housings 94 and 136 are identical. The high-voltage 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 electrode 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 wlhich 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 spaces 85. In many instances alternating-ourrent fields will sufiice in the treating spaces 78. In that event, the potential source may be a thigh-voltage transformer. If its peak potential 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 7S. It will then be subjected to a double-voltage pulsating D.C. field between the edges S6 and 87. Finally, it will be subjected to the uniform-gradient unidirectional electric elds in the treating spaces 85. This combination of fields has been found very efiicacious in the treatment of certain distillates.
In considering the general operation of the treater, 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 lowerrnost portions of the electrode members 63 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 supertreating action. VDuring the time the dispersion is between these sets of treating spaces, it is kept from reassuming excessive turbulent fiow by the stream-separating central portions of the electrode members 68.
It is often desirable to be able to sample the material undergoing treatment and the efiiuent materials. For this purpose the invention may provide a small valved line conducting a sample of the incoming dispersion to the `funnel 132. The condition of the dispersion at a position near the arms 69 can lbe 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. l, 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 irnportant that the dispersed phase Vbe 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 Ithe 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 closed 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 lill 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 105 of the insulators. The following description will indicate superior features of the present invention in such respects.`
As the vessel 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 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 S having its lower open end depending into the tank to a level B-B. 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 ulti mate positions in their respective housings merely by bringing the interior of the vessel up to operating pressure. The system for circulating the dielectric uid 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 suficiently to lower the float 210, the potential sources 160 and 161 will be immediately de-enengized to avoid any danger of explosion.
Another important feature of the invention is fhe manner in which the liquid is distributed to and withdrawn from the vessel to create a rising column which ows 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 plurality 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 ow 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 median-volume 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. l and also from the embodiments 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 A-A to the cylindrical wall of the vessel. This introduction ofthe dispersion is through side openings of pipe Ts 220 secured respectively to the outer ends of the pipes 26. 'Ihe 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 ow 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 openings be relatively few in number, usually less than about sixteen, and that each of these openings be relatively large, usually not less than about l 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 efliuence 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 orices. The pressure drop in such a system was in the neighborhood of 0.5-3 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 previously-desired 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 may be in the neighborhood of 0.2-2.0 pounds per sq. in., resulting from 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.
l. In an electric treater the combination of: a closed vessel adapted to contain a liquid under pressure; an insulator housing connected to said vessel and providing an open lower end in open communication with the interior of said vessel, the liquid in said vessel tending to rise in said housing; an insulator; a conductor secured in fluid-tight relation to said insulator; means for connecting said insulator to said housing in substantially fluid-tight relationship, said insulator providing a lower portion exposed to the interior of said housing, said conductor extending into said vessel through said lower open end of said housing, there being an annular chamber within said housing around said lower portion of said insulator and around a portion of said conductor; and circulation means for continuously circulating a dielectric gas through said annular chamber and for maintaining a constantly renewed volume of gas therein around said lower portion of said insulator, said circulation means including a gas inlet pipe means communicating with said annular chamber at one position, a gas outlet pipe means communicating with said annular chamber at another position, and llow means for continuously delivering gas to said inlet pipe means and withdrawing gas from said outlet pipe means in substantially like volume, said flow means including control means for controlling the ilow of said gas through at least one of said pipe means.
2. An electric treater as defined in claim l including a necked in portion at the lower end of said insulator housing forming a restriction between said annular chamber and the interior of said vessel, said gas outlet pipe means communicating with said annular chamber at-a position above said restriction.
3. An electric treater as defined in claim 1 including means for regulating the pressure inside the vessel, and in which said control means includes two pressureregulating valves respectively controlling gas ilow through said inlet and outlet pipe means, said pressureregulating valves being set to maintain the pressure in said annular chamber substantially the same as the pressure in said closed vessel.
4. An electric treater as defined in claim l in which said volume of said dielectric gas maintained by said control means in said annular chamber is in contact with said liquid at an interface in said housing, and in which said control means includes a valve in one of said pipe means and means responsive to change in position of said interface to control said valve and maintain the position of said interface substantially constant.
5. An electric treater as defined in claim 4 in which said-valve is in said gas inlet pipe means, and in which said control means includes a float adjacent said interface and changing position with changes in position of said interface, and means for operatively connecting said float to said valve.
6. In an electric treater, the combination of: a closed vessel adapted to contain a liquid under pressure; an
insulator housing connected to said vessel and providing an open lower end in open communication with the interior of said vessel, the liquid in said vessel tending to rise in said housing, said housing providing a support intermediate the ends of said housing; an insulator; a conductor secured in substantially fluid-tight relation to said insulator; means for connecting said insulator in substantially fluid-tight relationship to said support, said insulator and support dividing the interior of said housing into upper and lower zones, said insulator providing a lower portion exposed to said lower zone and an upper portion exposed to said upper zone, said conductor extending into said 'vessel through said lower open end of said housing, there being an annular chamber within said housing around said lower portion of said insulator and around said conductor; means for supplying a dielectric gas to said annular chamber to form a body of gas therein around said lower portion of said insulator and around a portion of said conductor, said body of gas contacting said liquid at an interface in said lower Zone; means for maintaining said interface below said lower portion of said insulator; means for supplying a dielectric fluid to said upper zone to form a body of dielectric fluid filling said upper zone and being in contact with said upper portion of said insulator; closure means for closing said upper zone; a high-voltage inlet bushing for conducting a high-voltage potential through said housing into said upper zone to said conductor; and means for maintaining the pressure in said upper zone substantially equal to the pressure in said lower zone.
7. An electric treater as defined in claim 6 in which said closure means removably closes said upper zone, and in which said high-voltage inlet bushing is carried by said closure means, there being a second conductor extending through said bushing having a terminal within said upper zone, and means for electrically connecting said terminal to said conductor.
8. An electric treater as dened in claim 7 in which said inlet bushing includes a tube of insulating material, means for connecting the upper end of said tube to said closure means, a terminal carried by the lower end of said tube of insulating material, and a high-voltage cable providing a lead extending through said tube of insulating material and electrically connected to said terminal. 9. In an electric treater the combination of: a closed vessel adapted to contain a liquid under pressure; electrode means in said closed vessel, said electrode means defining a treating space in said vessel; a plurality of supporting means spaced from each other for supporting said electrode means, each supporting means including a housing providing a lower open end in open communication with the interior of said vessel, a conductor extending from said electrode means through said open lower end, and an insulator in such housing supporting said conductor, there being an annular chamber in each housing around a lower portion of the corresponding insulator, the liquid in said vessel tending to rise in all of said annular chambers; a gas intake manifold providing a plurality of gas intake pipes interconnecting said manifold and said annular chambers for supplying respectively thereto a dielectric gas from said manifold, each annular chamber containing a body of said-dielectric gas surrounding the lower portion of the respective insulator and contacting said liquid at an interface in the corresponding housing; a level responsive means associated with only pnelof said housings and responsive to change in position of the interface therein; a control valve controlling the supply of said dielectric gas to said gas intake manifold; and means for operatively connecting said level responsive means to said control valve to maintain the position of said interface in said one housing substantially constant, the interfaces in said other housings being indirectly controlled by said control valve.
l0. In an electric treater, the combination of: a closed vessel adapted to contain a liquid under pressure; an insulator housing connected to the top of said vessel and providing an open lower end in open communication with the upper interior of said vessel, the liquid in said vessel tending to rise in said housing, said housing providing a support intermediate its ends; an insulator providing upper, intermediate and lower portions; a conductor secured in substantially Huid-tight relationship to said insulator and extending therethrough; means for connecting said intermediate portion of said insulator in substantially lluid-tight relationship to said support, said insulator and support dividing the interior of said housing into upper and lower zones, the upper and lower portions of said insulator being respectively exposed to said upper and lower zones,`said conductor extending into said vessel through said lower open end of said housing, there being an annular chamber within said housing around said lower portion of said insulator and around said conductor; circulation means for circulating a dielectric uid through said annular chamber and for maintaining a body of such iiuid around said lower portion of said insulator contacting said liquid at an interface in said housing, said circulation means including fluid supply means communicating with said annular chamber, a liuid outlet means communicating with said annular chamber, a control valve in one of said fluid supply and fluid outlet means, a level responsive means responsive to changes in position of said interface, and means for operatively connecting said level responsive means to said control valve to maintain the position of said interface substantially constant at a position below said insulator; means for supplying a dielectric fluid to said upper zone to form a body of dielectric uid filling said upper zone and being in contact with said upper portion of said insulator; and a high-voltage inlet bushing for conducting a high-voltage potential through said housing into said upper zone to said conductor.
ll. In an electric treater, the combination of: a closed vessel adapted to contain a liquid under pressure; an insulator housing connected to the top of said vessel and providing a support intermediate its ends; aninsulator providing upper, intermediate and lower portions; means for connecting said intermediate portion of said insulator in substantially fluid-tight relationship to said support, said insulator and said support dividing the interior of said housing into upper and lower zones, the upper and lower portions of said insulator being respectively exposed to said upper and lower zones, the lower end of said housing being necked in to provide a restriction [forming the sole communication between said lower zone and the upper interior of said vessel, the horizontal cross-sectional area of said restriction being very substantially less than the horizontal cross-sectional area of said housing above said restriction, the liquid in said vessel tending to rise in said housing through said restriction to contaminate said lower portion of said insulator; a conductor extending through said insulator in fluidtight relationship and thence through said restriction into said vessel; means for maintaining a body of dielectric tluid in said lower zone around said lower portion of said insulator and above said restriction, said last-named means including pipe means communicating with said lower zone above said restriction; and a high-voltage inlet bushing extending into said upper zone of said housing for conducting a high-voltage potential to said conductor.
12. An electric treater as dened in claim 11, including means for maintaining a body of dielectric fluid in said upper zone in contact with said upper portion of said insulator, said last-named means including pipe means communicating with said upper zone for supplying said last-named dielectric fluid thereto.
13. In an electric treater, an arrangement for supplying a high-voltage potential to an electrode, said treater and arrangement including: a closed vessel adapted to contain a liquid under pressure; an insulator housing connected to said vessel having an opening at its lower end communicating with the interior of said vessel, said housing providing a support intermediate its ends; an insulator providing upper, intermediate and lower portions; means for connecting said intermediate portion of said insulator to said support in substantially Huid-tight relationship, said insulator and support dividing the interior of said housing into upper and lower zones, the upper and lower portions of said insulator being respectively exposed to said upper and lower zones; an electrode-energizing conductor extending in substantially fluid-tight relationship through said insulator and thence through said opening at the lower end of said housing into the interior of said vessel; means for maintaining bodies of dielectric fluids respectively in said upper and lower zones in contact with said upper and lower portions of said insulator; and means for maintaining the pressure in said upper zone substantially equal to the pressure in said lower zone, said last-named means including a supply pipe opening on said upper zone, a supply pipe opening on said lower zone, and means connected to said supply pipes for maintaining substantially equal the pressures therein.
14. In an electric treater, an arrangement for supplying a high-voltage potential to an electrode, said treater and arrangement including: a closed vessel adapted to contain a liquid under pressure; an insulator housing connected to said vessel having an opening at its lower end communicating with the interior of said vessel, said housing providing a support intermediate its ends; an insulator providing upper, intermediate and lower portions; means for connecting said intermediate portion of said insulator to said support in substantially uid-tight relationship, said insulator and support dividing the interior of said housing into upper and lower zones, the upper and lower portions of said insulator being respectively exposed to said upper and lower zones; an electrodeenergizing conductor extending in substantially fluid-tight relationship through said insulator and thence through said opening at the lower end of said housing into the interior of said vessel; means for maintaining bodies of dielectric lluids in said upper and lower zones in contact with said upper and lower portions of said insulator; and means for maintaining the pressure in said upper zone substantially equal to the pressure in said lower zone, said last-named means including passage means interconnecting said upper and lower zones for transfer of pressure therebetween.
15. An electric treater as defined in claim 14 in which said dielectric iiuids are identical and are supplied from a source thereof, said pressure-equalizing means including a control means comprising a valve interconnecting such source and said passage means and thus controlling the supply of such dielectric fluid from said source to said passage means, said passage means including supply pipes openly communicating respectively with said upper and lower zones whereby the Ivalve-controlled dielectric fluid is delivered to said zones at substantially equal pressure.
References Cited in the le of this patent UNITED STATES PATENTS 1,528,296 Harris Mar. 3, 1925 1,887,010 Cage Nov. 8, 1932 1,891,645 Howes Dec. 20, 1932 1,978,793 Hanson Oct. 30, 1934 2,099,063 Hedberg Nov. 16, 1937 2,393,328 Mahone Ian. 22, 1946 2,527,690 Turner Oct. 31, 1950 UNITED STATES PATENT OFFICE CERTIFICATEv 0F CORRECTION PatentNoL, 2,893,251 Jury 2ev9 1959 Logen. Co Waterman It ie hereby Certified that error eppeere in the printed specification of the above numbered patent requiring eorrreetion and that the seid Lettere Patent should reed as corrected below,J
Columnly line 56, forl "neighbor" reed neighborhood Column 5p line lo, eiter "members" insert 68 end. '77., Edges '79 et the bottom oi" tbe electrode members m3 column Sy line '735 for "closed" reed eloee ===0 Signed and sealed this 22nd dey of December 195% f (SEAL) At'est: n
KARL AXLNE y RoBEn'r c. wATsoN `Ai'lies'bingj Officer Conmissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent-N@ 2,897,251 July 289 1959 Logan C 0 waterman It isr hereby Certified that error appears in the printed specification of the above numbered patent requiring eorrreotion and that the said Letters Patent should read as Corrected below., A
Column rl, line 56, forl ."neighborn vreed m neighborhood m; column 5y line 16, after lmembers insert w 68 and '7'7 Edges '79 at the bottom of the electrode members n; column Sy line '7,3y for "Closed" read closel um.,
Signed and sealed this 22nd dey of December 19590 (sin) Attest: I y
@iL-INE ROBERT c.' wATsoN Attestingj Officer Conmissioner of Patents