US1838922A - Method of dehydrating petroleum emulsions - Google Patents

Description

Dec. 29, 1931. H. F. FISHER METHOD OF YDEHYDRATING PETROLEUM EMULSIONS Filed Aug. 30. 1926 I Jx EMTQE A AP/vaw F Fia /5e, .52

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74 TY'OEA/EX' The difficult -emulsions, as they are called Patented Dec. 29, 1931" UNITED STATES PATENT OFFICE HARMON F. FISHER, 0]? LONG BEACH, CALIFORNIA, ASSIGNOR TO PETROLEUM REGTIFY- IN G COMPANY OF CALIFORNIA, OF LOS ANGELES, CALIFORNIA, ,A CORPORATION OF CALIFORNIA METHOD OF DEHYDRATING PETROLEUM EMULSIONS Application filed august 30, 1926. Serial No. 132,376.

This invention relates to dehydration of oils and particularly petroleum oils.

Petroleum oil is o'ften obtained from the well in the form of an emulsion, the oil con- 5 taining fine particles of water which must be separated from the oil before it is of commercial value. Some emulsions are comparatively easy to separate into their constituent parts while others are very diflicult.

to It is common practice to dehydrate petroleum emulsions by use of electrical dehydrating apparatus in which the emulsion is subjected to the action of an electric field which is established between a pair of electrodes.

3 may be divided into two main divisions, namely, low voltage or short-circuiting emulsions and high voltage emulsions. The low voltage emulsions act as if they were of very low electrical resistance and draw an excessive current. By short-circuiting characteristics is meant that the'emulsion acts as if it were of low electrical resistance, thus forming short-circuits through which current may pass. The high voltage emulsions are those which possess little or no ,short-circuiting characteristics and which permit only a small current to pass through the treater, with a maximum voltage imea pressed and with a minimum gap between the electrodes. The present electrical dehy-.

dration processes and apparatus are designed particularly for and are generally satisfactory for the dehydration of the high voltage emulsion and are not entirely satisfactory or economical for treating the difficult low voltage emulsions. 2

T have found that the difiicult emulsions may be satisfactorily and economically treat- 40 ed by subjecting the emulsion to a series of treatments or steps, each step preparing the emulsion for the subsequent step of the process. In my process the emulsion is given a preliminary treatment by subjecting it to the action of an electric field produced by a.

comparatively low elfective voltage, preferably between 1000 and 1500 volts, and using a heavy current. Since the short-circuiting emulsions draw a heavy current with a low impressed voltage, this step of theoperat-ion will be more economical and efiicient than it would he were ahigher eflective voltage applied. Short circuiting emulsions are not completely dehydrated in this step but they are prepared and conditioned for the next step of treatment of the'process. It is intended that the first step of the process shall so alter the character of the emulsion to enable carrying a higher efi'ective voltage With a maximum field intensity in the next step. This higher voltage will usually be the voltage will usually be the voltage which is impressed in the standard dehydrators now in use, which ordinarily employ 11,000 volts. The second step in my process corresponds closely to the conditions. which are maintained in the standard equipment operating at normal voltage on easy emulsions. In the second step the emulsion is subjected to the action of an electric field produced by a normal voltage. Tn the case of high voltage emulsions these emulsions may be first subjected to a normal electric field and thereafter subjected to the action of an extremely high voltage electric field produced between electrodes which are preferably very close together or particularly adapted to very dry emulsions.

lit is accordingly an object of this invention to provide a process which is particularly adapted to dehydrating diificult oils.

It is a further object of this invention to provide an apparatus for accomplishing the process of this invention.

Other objects and notable advantages of my invention will he explained in the following description which is taken in connection with the drawings, illustrating an apparatus in which the process of my invention ma beconducted.

n the drawings. Fig. 1 is a sectional elea water outlet pipe 17. 19 represents a high voltage insulation bushing which extends into the upper end of the chamber 12. Projecting through the bushing 19 is a high voltage tube 20, the upper and outer end of which has a high voltage wire 21 connected'thereto. This wire is connected to one terminal of the high voltage secondary of a suitable transformer (not shown), the other terminal being grounded on the shell 11. The tube 20 projects a distance downwardly from the bushing 19, and the lower end thereof has'a high voltage electrode in the form of a plate 22 secured thereto. The electrode 22 is cylindrical, there being a space formed between the periphery thereof and the shell 11, and has openings 23 formed therein through which oil may pass. Projecting upwardly from the high voltage electrode 22 are vertical electrode posts 24. Secured to the shell 11 is a grounded electrode 26 which is situated directly above the electrode'22. The electrode 26 is formed to provide cylindrical openings 27 through which the upper ends of the electrode posts 24 extend. The electrode 26 has a central opening 28 through which the high voltage tube 20 extends.

Secured to the shell 11 directly below the high voltage electrode 22 is a grounded normal voltage electrode 29 which is supported from the shell 11 by brackets 31. The electrode 29 has a central opening 32. The inner wall of the high voltage tube 20 is provided with an insulation wall 33 and extending inside the insulation wall 33 is an upper part of a rod 35. The upper end of the rod 35 is threaded at 36 and a nut 37 is advanced thereonto by means of which the vertical position of the rod 35 may be adjusted. A wire- 39 is attached to the upper end of the rod 35. This wire is connected to one terminal of a normal voltage secondary of a transformer (not shown), the other terminal being grounded to the shell 11. The rod 35 extends through the opening 32 of the grounded normal voltage electrode 29 and secured thereonto directly below the electrode 29 is a normal voltage electrode 41, a screen type of electrode being shown.

Situated below the electrode 41 is an upper grounded low voltage electrode 43 which is supported from the shell 11 by brackets 44 and which has a central opening 45 through which the rod 35 extends. The lower end of the upper part of the rod 35 has a medial insulator 47 connected thereto, and connected to the insulator 47 is a lower part 48 of the rod 35. The lower part 48 of the rod 35 carries a low voltage electrode 50 which may be a screen type of electrode, as shown. grounded low voltage electrode 51 is supported below the electrode 50 by brackets 52 which connect it to the shell 11, the electrode 51 having an opening 53 formed therethrough through which the rod 35 extends. At the lower end of the rod 35 is a lower low voltage electrode 55 which is a screen type of electrode, as shown. Projecting through the upper partof the shell 11 is a low voltage insulation bushing 56 carrying a rod 57, the

.outer end of which rod 57 has a wire 59 connected thereto. The wire 59 is connected to one terminal of a low voltage secondary of a transformer (not shown), the other terminal of said secondary being grounded to the shell 11. The inner end of the rod 57 has a wire 60 connected thereto which extends as shown in the drawings, and connects to the lower part 48 of the rod 35.

The operation of my invention when treating .low voltage oils is as follows.

The low voltage emulsion is introduced into the lower part of the chamber 12, passing from the pipe 13 and being deflected by the deflector 14. The emulsion flows upwardly through and around the lower low voltage elertrode 55. A low electrical potential is impressed on the upper and lower low voltage electrodes 50 and 55 by means of the wire 60, the wire 59 and the low voltage secondary, and there is therefore a low voltage electric field or a low voltage gradient field set up between the pairs of low voltage electrodes 43 and 50, and 51 and 55. This voltage will probably be in the neighborhood of 1500 volts but it should be understood that the voltage mustbe such as to produce a field suitable for acting on low voltage emulsions. As the low voltage oil moves into these fields the particles-of water are coalesced into larger masses of water, there being a comparatively heavy flow of current.

The oil gradually moves upwardly around the pairs of low voltage electrodes into the central portion of the chamber 12 where it is subjected to the next step of the operation. The normal voltage electrode 41 is supplied with a normal voltage through the wire 39, this normal voltage current being of the same voltage as is employed in the ordinary dehydrators usedfor treating the easy oils, or, say, about 11,000 volts. An electric field of normal potential gradient is therefore established between the normal electrodes 41 and 29, that is, a field suitable for easy oils. When the oil reaches this zone of the chamber 12, it has been treated in the low voltage'field so that it is in proper condition to enable the carrying of normal voltage and to enable it to be satisfactorily subjected to the action of the normal electric field without short-circuiting. It

A lower may, therefore, be said that the low voltage .oils are prepared and conditioned in the first step of the process for further treatment in the second step thereof. The emulsion passes through and around the normal voltage electrode 41 and into the normal voltage or normal Voltage gradient field produced between the electrodes 41 and 291 The emulsion is further acted upon therein and water is precipitated therefrom to the lower part of the chamber.

Generally the subjecting of the low voltage oil to these two steps is sufiicient to produce a resultant oil which is comparatively dry, this dry oil flowing upwardly to the upper end of the chamber 12 and being withdrawn therefrom through the oil outlet pipe 16. Therefore, ordinarily the high voltage electrodes are not utilized. However .in some cases it may be desirable to subject the emulsion to a very high voltage field of an intensity of about 25,000 volts. High voltage is supplied to the high voltage electrode 22 through the high voltage wire 21. A high voltage or high voltage gradient field is therefore established between the high voltage electrodes 22 and 26. The field is established between the electrodes proper and also between the electrode posts 24 and the walls of the cylindrical openings 27. It should be noted that the distance between the high voltage electrodes '22 and 26 is much less than the separation used in the lower fields. They are shown close together because it is easier to obtain a high voltage gradient when the electrodes are close. It should be understood that the voltage and electrodes may be arranged to obtain a field suitable for dry oil. The emulsion, when using the high voltage step ofthe process, passes upwardly around the electrode 29 and through the opening 32 thereof and then flows into the high voltage field or high voltage gradient field produced between the electrodes 22 and 26. The emulsion may either flow around the edge of the electrodev 22 or through the openings 23 thereof. Since the emulsion has been subjected to two previous treatments, it will be quite dry and there will be but little short-circuit tendencies, so that only a minimum of high voltage current will be drawn. This step of the process is very eflective, since the voltage gradient is veryhigh. Theoil passes .from the high voltage field through the openings 27 in the electrode 26 and may thereafter flow from the tank 16.

The apparatus as shown in the drawings is very wellsuited for conducting the process 'of my invention, since it is embodied in onestructure and since the'various steps may be utilized or dispensed with as desired. This is a valuable feature since it permits the treating of different kinds of-oil, that is,

low voltage or high voltage or easy oil in the same dehydrator.

It is desirable that the low, normal, and

3, which employes' a high voltage transformer (a), a normal Voltage transformer (15), and a low voltage transformer (c). The secondaries of these transformers are each connected to the grounded shell 11 of the treater as shown at 71, 72 and 73, the other terminals being connected to the wires 21, 39 and 59 respectively. The low voltage primaries of the transformers (a), (b), and (c) are each connected to supply wires 7 5 through suitable control and protective devices not shown.

From the foregoing description it will be seen that myinvention will thoroughly,- economically and satisfactorily remove the water both from low voltage and high voltage diflicultoils. In the case of low voltage oils the preliminary treatment removes a large portion of the water economically, since -a very low voltage current is used, and predisposed in superimposed relation in said tank; live electrodes interspersed between said grounded electrodes; and means extending through said openings for supporting said live electrodes and imposing electric potentials between adjacent live and grounded electrodes, said potentials being unequal and increasing in a definite sequence.

2. In an electric dehydrator, the combination of: a tank; a plurality of grounded electrodes provided with central openings and disposed in superimposed relation in said tank; live electrodes interspersed between said grounded electrodes; means for passing the fluid to be treated through said tank; and a plurality of sources of high potential electrically connected to said electrodes to produce electric fields between adjacent live and grounded electrodes, the potential gradient of said fields increasing in the direction of i the passage of said fluid through said tank.

3. In an electric dehydrator, the combination of: a tank; a plurality of grounded electrodes provided with central openings and disposed in superimposed relation in said tank; live electrodes interspersed between said grounded electrodes; and means for imlive electrodes, the potential imposed upon each live electrode being independentl controllable from the exterior of said tan 4. In an electric dehydrator, the combination of: a tank; an electrode in said tank comprising a substantially fiat plate provided with a plurality of relatively small openings; a second electrode in said tank comprising a flat foraminous member from which a plurality of rods project, each rod extending into one of said openings; means for imposing a difference of potential upon said electrodes; and means for bringing the oil and water emulsion to be treated into the spaces between said rods and the Walls of said openings whereby agglomeration of the water particles takes place.

5. In an electric dehydrator, the combina tion of: a tank; an electrode in said tank comprising a substantially fiat plate PIOVlClQd with a plurality of relatively small openings, and a plurality of flanges formed upon said plate about said openings; a second electrode in said tank comprising a flat member from which a plurality of rods project, each rod extending into one of said openings; means for imposing a difference of potential upon said electrodes; and means for bringing the oil and water emulsion to be treated into the spaces between said rods and said flanges whereby agglomeration of the water particles takes place.

6. In an electric dehydrator, the combination of: a tank; a plurality of grounded electrodes provided with central openings and disposed in superimposed relation in said tank; live electrodes interposed between said grounded electrodes; a plurality of insulating members extending through the walls of said tank; a plurality of sources of electrical potential; and a plurality of electrical conductors extending through said insulators, each of said conductors being connected to one of said live electrodes and to one terminal of its individual source of high potential, the remaining terminals of said sources being interconnected and connected to said grounded electrodes.

7. In an electrical dehydrator, the combination of: a tank; a plurality of grounded electrodes in said tank; an insulator in said tank; a conducting tube extending through said insulator and connected to a primary source of electrical potential; a live electrodesecured to said tube and extending adjacent one of said grounded electrodes; an insulating wall extending through said tube; a rod supported in said tube and separated therefrom by said' insulating wall, said rod being connected to a secondary source of electrical potential; and a live electrode secured to said rod and extending adjacent another of said grounded electrodes.

8. A combination as defined in claim 7 in which said sources of electrical potential are of different voltages, and including means for varying the distance between one of said live electrodes and its adjacent grounded .electrode.

9. In an electrical dehydrating apparatus, the combination of a tank; means for introducing the emulsion to be treated into said tank; a plurality of grounded electrodes in said tank; a plurality of live electrodes in said tank and cooperating with said grounded electrodes in defining treating spaces, each live electrode being between ad acent grounded electrodes; and means for impressing potentials of difi'erent'magnitude between the electrodes defining said treating spaces whereby the voltages across said treating spaces are unequal.

10. In an electrical dehydrator, the combination of: a tank; a pair of solid-wall electrodes supported in said tank; an interstitial electrode between said pair of electrodes thus dividing the space between said solid-wall electrodes into upper and lower treating spaces in communication through the interstices of the interstitial electrode; and means for establishing a diflerence in potential between said interstitial electrode and said solid-wall electrodes.

11. In an electrical dehydrator, the combination of: a tank; a substantially fiat electrode extending substantially across said tank and having a plurality of relatively small openings therein; another substantially fiat electrode supported in said tank in spaced relationship relative to the first-named electrode and providing a plurality of rods, each rod extending into one of said openings; means for imposing a difierence in potential across said electrodes; and means for bringing the oil and water emulsion to be treated into the spaces between said rods and the walls of said openings whereby agglomeration of the water particles takes place.

12. In combination in an electric dehydrating apparatus: a grounded electrode; means including a live electrode for establishing an electric field of high potential thereacross on one side of said grounded electrode; and means including another live electrode for establishing an electric field of substantially lower potential on the other side of said grounded electrode.

13. In an electric treater, the combination of: a tank; an electrode extending substantially across the upper end of said tank and providing a plurality of openings; another electrode supported in said tank in spaced relationship with said first-mentioned electrode and providing a plurality of rods, one rod extending into each of said openings; means for establishing a difference in potential between said electrodes; means in said tank below said electrodes for introducing an emulsion of oil and water into said tank; means for withdrawing dry oil from said tank at a section above said electrodes; and

means for withdrawing water separated from said emulsion from the bottom of said tank.

14. In an electric treater, the combination of: a tank; an electrode extending substantially across the upper end of said tank and providing a plurality of openings; another electrode supported in said tank in spaced relationship 'with said first-mentioned electrode and providing a plurality of rods, one rod extending into each of said openings; means for establishing a difierence in potential be tween said electrodes; an emulsion inlet pipe below said electrodes and moving emulsion upward in said tank to be treated by said electrodes; a deflector plate for spreading said emulsion as it issues from said emulsion inlet pipe; means for withdrawing dry oil from said tank at a section above said electrodes; and means for withdrawing water separated from said emulsion from the bottom of said tank. v

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 24th day of August 1926.

RMON F. FISHER.

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