US1978794A - Dehydrator having gas pocket - Google Patents

Description

Oct. 30, 1934. w F, VAN c NE 1,978,794

DEHYDRATOR HAVING GAS POCKET Original Filed Feb. 18, 1929 /5 f 20 22 /4 Z5 45 4 I 1 I /r I [1 /EJ\/ TO B WILL/HM f. VHN L OENEN, 5r

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Patented Oct. 30, 1934 UNITED STATES PATENT OFFICE DEHYDRATOR HAVING GAS POCKET of California Application February 18, 1929, Serial No. 340,942

Renewed December 16, 1932 22 Claims; (Cl- 204-24) My invention relates to.treaters, and more particularly to an electric treater having a dielectric barrier of gas in the treating space thereof.

One application of my invention is in the petroleum industry. and it is in this capacity that it will be particularly described. It should be understood that I am not limited to this use nor to the exact construction shown.

Petroleum as it comes from the well is often associated with water or other undesirable substances which can ordinarily be separated therefrom by the action of an electric field. Electric treaters are widely used for separating the phases of such an emulsion of oil and water. As this emulsion passes through the electric field the water particles or other undesirable substances are agglomerated into masses of sufiicient size that they will separate from the clean petroleum by the action of gravity. Such an electric field is ordinarily formed between a pair of electrodes, and if the potential between these electrodes is made sufiiciently great, a short-circuit will occur, due probably to the lining up of the agglomerated water particles in the field. The instant this short-circuit occurs, the potential difference between the electrodes is decreased practically to zero, and further treatment in the field is impossible.

The current consumption is at this time very high. If the electrodes are separated a further distance, or if the potential difference therebetween is decreased, these permanent short-circuiting chains are not as readily formed, especially where the emulsion in the field is travelling at a high velocity or when this emulsion is agitated.

I have found that the best dehydrating conditions occur when the emulsion is subjected to an electric field of quite high intensity. If the'emulion fills the space between a pair of electrodes, the permissible field intensity therebetween is limited by the formation of the short-circuiting chains previously mentioned. This is especially true if the intensity of the field is relatively uniform, or if, in other words, the voltage gradient is substantially constant in the space between the electrodes. Obviously. if the voltage gradient were uniform throughout the treating space an increase in field intensity would invariably produce short-circuiting chains which could be broken only with difliculty. However, by utilizing electrodes of different areas. a non-uniform voltage gradient is established in the electric field therebetween. The maximum voltage gradient occurs, of course; adjacent the electrode of smaller area, and my invention comprehends the pass-.

ing of a fluid envelope of emulsion in contact with this smaller electrode, the remaining space between the electrodes being filled with a. dielectric gas.

Whether or not the treating space between the electrodes is filled with an emulsion, or with contacting bodies of emulsion and a dielectric gas, I have found that if the field produced is sufficiently strong to dehydrate the emulsion, this field acts upon the material or materials in the treating space, and effects the separation of charged particles therefrom which are moved due to the instantaneous difference in polarity of the electrodes. The electric field is ordinarily produced by applying a high voltage alternating potential to the electrodes. The charged particles are thus alternately attracted and repelled, and apparently vibrate at the frequency of thealternating potential supplied to the electrodes. These particles thus bombard adjacent particles and cause an agglomeration thereof due both to this physical bombardment and to the attraction existing between two particles which might be differently charged. Thus, the dielectric gas is ionized and the ions formed thereby bombard the water particles of the emulsion, thus tending to coalesce these particles into globules of suflicient size to gravitate from the oil. The degree of ionic bombardment is determined by the intensity of the field. Inasmuch as I pass the emulsion in a fluid envelope around a small electrode, this emulsion is subjected to a very intense electric field, as is also the gas immediately surrounding this envelope of emulsion. A very effective dehydrating action thus takes place. and the current necessary is relatively small.

It is an object of my invention to provide a treater having a gas barrier between the electrodes thereof.

A further object of my invention is to provide a treater in which the short-circuiting of the electrodes is impossible.

A further object of my invention is to provide a treater in which the continuous successful treatment of a fluid is not dependent upon the velocity of the fiuid to be treated nor upon the agitation of this fluid.

The absence of such agitation and high velocities makes it possible to provide a quiet settling space in the lower portion of the treater of my invention.

It is an object of my invention to provide a treater which provides a quiet settling zone therein.

A. iurther object of my invention is to provide treater in which a maximum desirable difference of potential may be maintained across the electrodes thereof without regard to the per cent of water or other foreign substances in the fluid to be treated.

Still another object of this invention is to i e;-

vide a. novel method of treating emulsion by passing this emulsion through an electric field in contact with a dielectric barrier of gas.

Further objects and advantages of my inveri tion will be made evident hereinafter.

Referring to the drawing:

Fi 1 is a vertical sectional view of the ferred form-of my treater.

Fig. 2 is a sectional view taken along the line 22 of Fig. 1.

Fig. 3 is a vertical sectional view of an alternate form of my invention.

Fig. 4 is a sectional view of the nozzle utilized in my invention.

Referring particularly to Fig. 1, the treater 10 of my invention is enclosed in a shell 11 formed of a tank 12 closed at its lower end by a conical base 13 and at its upper end by a cover 14.

Extending through the cover 14 is an insulator or bushing 15 of smaller cross-sectional area at its lower end than at its upper end and which supports a primary electrode 16 inside the shell 11. This primary electrode is preferably cylindrical in shape and formed concentric with the axis of the tank 12, there being a conductor extending through the insulator 15, and thus through the cover 14, this conductor supporting the primary electrode so as to in effect form a part of this electrode.

Extending centrally through the primary electrode 16 but not in contact therewith is a secondary electrode 17, there being a treating space 18 between the primary and secondary electrodes. The secondary electrode in the form shown in Fig. l is formed of a pipe or solid rod supported by a bracket 20 on the cover 14 and extending downward to a point substantially midway between the cover 14 and the base 13. Formed at the upper end of the secondary electrode 17 is a nozzle 22 whichAs in ppen communication with an intake pipe 23. The fluid to be treated is forced through the intake pipe, and the nozzle 22 is adapted to direct this flow outward and down ward around the secondary electrode 17, as best shown in Fig. 4, in a direction indicated by the arrows 25. The nozzle 22 is so formed that this fluid passing downward over the secondary electrode completely surrounds this electrode. In following the path indicated by the arrows 25, the fluid to be treated clings to the outer periphery of the secondary electrode 17 and forms a fluid envelope therearound.

Referring again to Fig. 1, extending downward from the cover 14 and surrounding the primary electrode 16 is a shield 30 which is preferably cylindrical in shape. This shield extends a distance below the lower edge of the primary electrode 16 but preferably does not extend below the secondary electrode 17. The interior of the shield 30 comprises a gas chamber 32 which .is

pre-

throughthe gas supply pipe 33.

be entrapped'in the upper portion of the gas adapted to receive a suitable gas through a gas supply pipe 33, this flow of gas being controlled by a valve 34.

The operation of my invention is as follows:

"the tank 11 may be completely filled with dry oil.

At this time asuitable dielectric gas is introduced This gas will chamber'32 and will force the oil level therein ,downward. Sufficient gas is allowed to enter the gas chamber 32 so that the oil level is lowered to a surface substantially as indicated by the numeral 40, this surface being near the lower edge of the shield 30. A pipe 41 closed by a valve 42 communicateswith the interior of the gas chamber near the lower portion thereof and may be utilized for determining when the surface 40 reaches the position indicated in Fig. 1.

This gas introduced into the gas chamber 32 is of such a nature that it hasa high dielectric strength, and is relatively stable. Its function is to form a dielectric barrier in the treating space 18 when an electric field is established therein by means of a transformer 45 having a secondary 46 connected between the primary and secondary electrodes. This gas may be renewed from time to time if desired by forcing a new supply of gas through the pipe 33. However, the gas generated by the treating action which takes place between the electrodes is ordinarily suflicient to more than fill the gas chamber 32. As the fluid to be treated is forced through the intake pipe 23, the nozzle 22 directs this stream outward and downward around the peripheral surface of the secondary electrode 17 in the manner previously described. Inasmuch as the gas chamber 32 is completely filled with gas, and inasmuch as the treating space 18 comprises a portion of the gas chamber 32, it follows that the outer portion of the treating space 18 defined between the primary electrode 16 and the fluid passing downward around the secondary electrode 17 will be at all times filled with gas. This gas will prevent any short-circuiting between the primary and secondary electrodes, but will permit the setting up of an electric field of high potential in this treating space.

As the fluid passes downward in an envelope through the treating space 18, clinging to the walls of the secondary electrode 17 and contacting the gas, the electric field acts in a manner to coalescethe particles of water or other substances therein so that when this fluid reaches the level 40 and unites with the oil in the shell, these coalesced particles will settle downward as indicated by the" arrows 51 until they reach a settling chamber 52 in the lowermost portion of the shell 11, whence they may be withdrawn through a pipe 53 in communication therewith. The dry and purified oil rises, being of a lower specific gravity than the water and other foreign substances, and follows a'path indicated by the arrows 54, reaching the topof the shell 11, whence" it is withdrawn surface to short-circuit the primary and secondary electrodes 16 and 1'7 due to the fact that there will be a gas barrier between the surface 40 and the lower edge of the primary electrode 16. The gas chamber 32 may be initially filled with gas or may be intermittently or continuously supplied therewith. I prefer to initially charge this chamber with the correct amount of gas, and find that the small amount of gas released from the fluid being treated, when this fluid is a crude petroleum oil, is sufiicient to maintain the gas pressure in the chamber 32. Any excess of gas forming in this chamber will, of course, lower the surface 40 to the lower edge of the shield 30 and will then be released from the gas chamber and bubble upward through the oil and will pass out through the clean oil pipe 55.

It is a comparatively easy matter to separate this gas from the dry oil by means of a suitable trap, not shown.

The secondary electrode 1'7 is made relatively small so that a high intensity field will be set up immediately therearound due to the non-uniform voltage gradient across the treating space. This non-uniform field is due to the shape of the electrodes and I have found that best results are obtained if the emulsion or other fluid is passed through that portion of the field which is of greatest intensity, this portion corresponding to that portion of the field having the highest voltage gradient. The fluid to be treated passes through this high intensity field and is subjected to a very strong treating action which could not otherwise be obtained due to the difficulty of short-circuiting the electrodes. The fundamental idea of passing the emulsion through only that portion of the field which is of greatest intensity is not per se a part of the present invention, but is shown and claimed in copending applications of Harmon F. Fisher, Serial No. 135,804, now Patent No. 1,838,924, and Serial No. 203,253, now Patent No. 1,838,928, the present method and apparatus being an improvement over those disclosed in these applications.

Not only is this fluid subjected to the high intensity field, but also the gas immediately surrounding the fluid envelope is highly ionized and the ions formed thereby act to bombard the particles of water or other foreign substances in the fluid to be treated. The nozzle 22 directs the fluid to betreated over the surface of the electrode 1'7 in a relatively thin envelope so that the gas is separated only a small distance from the surface of this electrode, thus increasing the ionization of the gas, and the degree of bombardment between the ions and the emulsion. I

The treater of my invention is adapted to operate continucusly, and will handle a volume of fluid which is not dependent upon the amount of foreign substances present nor upon the conductivity of these foreign substances inasmuch as there is no danger of forming short-circuiting paths between the electrodes. In using the treater of my invention, a maximum difference of potential may be maintained across the electrodes without regard to the amount of impurities in the fluid being treated.

The gas in the gas chamber not only prevents the oil from reaching the insulator 15 but itself surrounds this insulator thereby effectively protecting this insulator from electric breakdown. It is also important to notice that the shield 30 is surrounded by a body of oil which is at substantially the same temperature as the gas in the gas chamber 32 and thus acts as a means preventing heat transfer through the shield 30. This is advantageous in view of the fact that it prevents condensation taking place in the gas chamber and thus prevents sweating of the walls of this chamber and which would otherwise lower the dielectric strength of the gas. Positioning the gas chamber 32 inside the tank 12 also acts to lower radiation losses and provides a simple and easily manufactured structure.

It is, however, not essential that a shield 30 be used. Fig. 3 shows a modified form of the treater of my invention in which such a shield is absent. In Fig. 3 the primary electrode 16 has a cover 60, and the secondary electrode 17 extends upward into the primary electrode 16 and is supported by an intake pipe 61. The upper end of the secondary electrode is provided with a suitable cap or nozzle 62 which directs a flow of fluid passing upward through the secondary electrode in such a manner as to cause this fluid to flow downward around the secondary electrode, this fluid clinging to the surface thereof, as previously described. In operating this form of my invention, the shell 11 is first filled with a dry oil, and the dielectric gas is forced through the pipe 61 until it completely fills the treating chamber 18 and until the oil level 65 is lowered to a point substantially adjacent the lower edge of the primary electrode 16.

This form of my invention is open to the objection that short-circuiting paths are liable to form between the primary and secondary electrodes at the level 65 of the oil. To decrease this tendency, the lower end of the electrode 16 is flared, as best shown in Fig. 3, so as to increase the spacing of the electrodes 16 and 17 at the surface indicated by the numeral 65. During the operation of this type of treater a certain amount of gas is given oif in the treating space 18, this gas being entrapped by the electrode 16 and elim-v inating any tendency for the level 65 to rise in the treating space 18.

I claim as my invention:

1. In an electrical treater, the combination of: a primary electrode; a secondary electrode extending into said primary electrode, there being 120 a treating space between said electrodes; means surrounding said primary electrode and providing a gas chamber around said primary electrode; andmeans for introducing a fluid to be treated into said treating space in such a manner that said gas prevents any short-circuiting of said electrodes.

2. In an electrical treater, the combination of: a shell; a primary electrode supported in said shell; a secondary electrode extending into said primary electrode, there being a treating space between said electrodes; a shield surrounding said primary electrode; means for introducing a gas into said shield; and means for introducing a fluid to be treated into said treating space in such a manner that said gas prevents any shortcircuiting of said electrodes.

3. In an electrical treater, the combination of: a shell; a primary electrode supported in said shell; a secondary electrode extending into said 1 0 primary electrode, there being a treating space between said electrodes; a shield surrounding said primary electrode and extending downward to a point below said primary electrode; means for introducing a gas into said shield; and means 145 for introducing a fluid to be treated into said treating space in such a manner that said gas prevents any short-circuiting of said electrodes.

4. In an electrical treater, the combination of primary and secondary electrodes providing a 150 gas-filled treating space therebetween; means for setting up in said treating space an electric field of non-uniform voltage gradient; and means for introducing the emulsion to be treated into that portion of said field which is of the highest voltage gradient, the remainder of said treating space being filled with the gas.

5. A method of dehydrating emulsion, which comprises: filling a treating space with a gas; setting up an electric field of non-uniform intensity in said treating space; and passing said emulsion through only that portion of said field which is of maximum intensity, said emulsion being in contact with said gas in passing through said treating space.

6. A method of treating a petroleum emulsion by the use of a primary electrode of large surface and a secondary electrode of much smaller surface, which includes: flowing a thin stream of said emulsion over the surface of said secondary electrode; maintaining a gas in contact with said stream of said emulsion; and impressing a potential diflerence between said electrodes of sufficient value that said gas immediately contacting said stream of emulsion is ionized, said film being sufiiciently thin to permit such ionization,

7. In an electric treater, the combination of walls forming a gas chamber open at its lower end and thereby communicating with a liquid the surface of which is prevented from rising in said gas chamber by the gas therein; means for setting up an electric field in said gas chamber, said means comprising a pair of electrode surfaces one of which extends below said liquid level; and means for flowing a stream of the fluid to be treated along one of said electrode surfaces and into said body of liquid.

8. In an electric treater, the combination of: a primary electrode of sleeve form; a secondary electrode extending into said primary electrode and cooperating therewith in defining 'a treating space; walls defining a gas chamber around said primary electrode and filled with-a body of gas whereby gas has free access to both ends of said treating space; nozzle means for introducing a film of liquid into said treating space immediately around and in contact with said secondary electrode; and means for setting up an electric field between said electrodes.

9. In a treater, the combination of: walls defining a chamber containing a gas; a sleeveshaped electrode mounted in said chamber so as to be completely surrounded by said gas; nozzle means for flowing a stream of emulsion axially through said sleeve electrode; and means for setting up an electric field in said sleeve to which said stream of emulsion is subjected.

10. In a treater, the combination of: an outer electrode; an inner electrode extending into said outer electrode and cooperating therewith in defining a treating space: means for building up an electric field between said electrodes; nozzle means associated with said inner electrode for flowing a fluid envelope of emulsion therealong; and means for maintaining a body of gas between said envelope of emulsion and said outer electrode.

11. In a treater, the combination of: walls defining a gas chamber, the lower end of which is exposed to a surface of liquid; a rod extending downward through said gas chamber and ex.- tending below said surface of liquid; means for flowing a fluid envelope of emulsion downward along the surface of said rod and into said liquid; and means for building up an electric field around said rod and through emulsion passes.

12. In a treater, the combination of a central electrode; a nozzle discharging adjacent the surface of said central electrode and flowing a fluid envelope of emulsion therealong; a surrounding electrode around said central electrode and insulated therefrom to define a treating space which is only partially filled by said fluid envelope, the space around said fluid envelope and inside said surrounding electrode being filled with a gas; a

which said envelope of cover extending across the upper end of said surv rounding electrode and above the upper end of said central electrode in a manner to entrap a body of gas in said treating space; and means for establishing a difference of potential between said central and surrounding electrodes.

13. A combination as defined in claim 12 in which said surrounding electrode is submerged in liquid, the liquid level extending between said electrodes at the lower end of said surrounding electrode, and in which the lower end of said surrounding electrode is fiared outward away from said central electrode.

14. In combination in an electric dehydrator: a tank containing a liquid having a cover which slopes from the center downward to define the upper end of a gas chamber; a skirt depending from said cover forming a wall of said chamber;

means for supplying gas to said gas chamber whereby the liquid is prevented from rising in said gas chamber; an insulator extending through said cover and into said gas chamber whereby that portion of said insulator which lies in said gas chamber is surrounded by said gas; an electrode supported inside said tank by said insulator; and means for setting up a potential diflerence between said electrode and said tank.

15. In combination in an electric dehydrator: tank means including a cover which slopes from its center downward to define the upper end of a gas chamber and including a wall depending from said cover to form a wall of said gas chamber, said tank means containing a liquid; means for supplying gas to said gas chamber whereby said liquid is prevented from rising in said gas chamber; an insulator extending through said cover and into said gas chamber whereby thatportion of said insulator which lies in said gas chamber is surrounded by said gas; an electrode supported inside said tank means by said insulator; and means for setting up a potential difference between said electrode and said tank means,

16. In combination in an electric dehydrator; walls defining a gas chamber and containing a body of gas to preventa rise of liquid therein; an insulator extending into said gas chamber whereby that portion of said insulator which lies in said gas chamber is surrounded by said gas; electrode means supported by said insulator; and means for preventing excessive heat transfer through said walls of said gas chamber, said means including a body of material around said walls.

17. In combination in an electric dehydrator for treating emulsions of oil and water: a tank containing a body of separated oil at its upper end and providing a top wall; an insulating bushing extending downward through said top wall of said tank; a live electrode in said tank; conductor means extending through said insulator bushing and electrically connected to said live electrode to energize same; means for delivering the emulsion to be treated to said tank, said live electrode establishing an electric field in said tank which coalesces the water phase of said emulsion, the separated oil rising into said body of separated oil in the upper end of said tank; a bushing-protecting apron extending downward from said top wall around said insulating bushing to protect same and positioned entirely within said tank,,said apron being larger in diameter than said insulating bushing to provide a closed chamber therebetween, which chamber is entirely within said tank, said apron being smaller in diameter than said tank to provide a chamber therebetween filled with said separated oil; means for withdrawing separated oil from the upper end of said tank; and means for withdrawing water from the bottom of said tank.

18. An electrical dehydrator for oil and the like comprising a shell, an electrode extending into the shell, a bushing of insulating material surrounding the electrode adjacent the shell, and a shield disposed wholly within the shell having a closed top and an open bottom surrounding the bushing, said shield serving to confine an insulating' gas about the bushing to prevent short circuiting between the electrode and the shield. 19. An electrical dehydrator for oil and the like comprising a shell, an electrode extending into the shell, a bushing of insulating material surrounding the electrode adjacent the shell, and a shield disposed wholly within the shell having a closed top and an open bottom surrounding the bushing, said shield serving to confine an insulating gas about the bushing to prevent short circuiting between the electrode and the shield, said bushing being characterized by increasing in cross sectional area from bottom to top.

20. An electrical dehydrator for oil and the like comprising a shell, an electrode extending into the shell, a bushing insulating the electrode from the shell, and means providing an annular wall about the bushing in spaced relation to the bushing, said wall being disposed wholly within the shell; and serving to confine a as about the bushing to prevent short circuiting.

21. An electrical dehydrator for oil and the like comprising a shell, an electrode extending into the shell, a bushing insulating the electrode from the shell, means providing an annular wall about the bushing in spaced relation to the bushing, said well being disposed wholly within the shell, and serving to confine a gas about the bushing to prevent short circuiting, and a supply pipe for supplying the space between the wall and the bushing with gas.

22. In combination, in an electric dehydrator, walls'defining a gas chamber and containing a body of gas to prevent a rise of liquid therein, an insulator extending into said gas chamber whereby that portion of said insulator which lies in said gas chamber is surrounded by said gas, electrode means supported by said insulator, and means for preventing excessive heat transfer through said walls of said gas chamber, said means including a body of oil around said walls.

WILLIAM F. VAN LOENEN.

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