US1838937A - Dehydrator having high resistance wall - Google Patents

Description

Dec. 29, 1931. c. w. GIRVIN 1,838,937

DEHYDRATOR HAVING HIGH RESISTANCE WALL Filed March 23. 1927 2 %2e M. R54

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Patented Dec. 29,. 1931 ATENT OFFICE CHAR-LES 1V. GIRVIN, OF LONG BEACH, CALIFORNIA, ASSIGNOR TO PETROLEUM RECTI- FYING COMPANY OF CALIFORNIA, F LOS ANGELES, CALIFORNIA, A CORPQRATION OF CALIFORNIA DEI-IYDRA'IOR HAVING HIGH RESISTANCE WALL Application filed. March 23, 1927. Serial No. 177,766.

This invention relates to the dehydration of petroleum emulsions. Petroleum often becomes associated with water, and an emulsion is formed. Before the petroleum is of connnercial value the water must be separated therefrom. It is common practice to accomplish separation by use of an electrical dehydrator in which the emulsion is subjected to the action of an elcctrictield. The electric lield is formed between a pair of low resistance electrodes made of wrought-iron, which electrodes are included in an electric circuit. The emulsion is ordinarily of comparatively high resistance so that the potential ditlcrcnce of the electrodes is great. Conditions arise, however, in the emulsion so that the electrical resistance thereof is greatly decreased locally, and this will permit a large fiow of current, causing a cor responding potential drop in the high potential electrode. This will reduce the electric field so that it is non-effective in coalescing the water particles of the emulsion.

It is an object of this invention to provide an electrical dehydrator in which a local rush of current through the emulsion is prevented and in which the potential difference of the electrodes will be maintained at all times.

It has been found in treaters having plain metal electrodes, these being ordinarily used, that the local rushes of current and the resulting heat actually break down the oil at that point, causing free carbon to be deposited. The particles of free carbon are, like all finely divided soluble substances, good emulsifying agents.

It is a further object of the invention to provide an electrical dehydrator in which no free carbon will be formed.

A still further object of the invention is to provide an electrical dehydrator in which high voltages can be held and smooth operation obtainedtand also a more complete dehydration of theemulsion than can be obtained with the ordinary electrical dehydrato'r.

Other objects and advantages of the invention will be made evident. hereinafter.

Referring to the drawings in which I illustrate a preferred embodiment of the invent1on:

Flg. 1 1s a vertical section through the 1nvcntion.

insulators 14c carry a bearing 15. Supported by the bearing 15 either rotatably or nonrotatably is a shaft IT-Which extends into the shell 11. The shaft 17 supports a secondary metal electrode'lS). A treating space 20 is formed between the electrodes 11 and 19. Emulsion is introduced into the treating space 20 by means of an emulsion inlet pipe 22 which is in the form of a perforated ring, emulsion being supplied to the ring by means of a pipe 23 which extends through the wall of the shell 11. The shell 11, which serves as a primary electrode, and the secondary electrode 19 are connccted'by conductors 25 to a secondary of a transformer 27. Vhen the transformer 27 is energized, an electric field is established in the treating space 20 between the electrodes of the invention.

The parts of the dehydrator which I have just described are standard construction.

The important part of the invention will now be described.

The inner face of the tank 1.1 is provided with a high resistance lining or wall 30; and the electrode 19 is provided with a high resistance coating or wall 31. The walls 30 and 31 are non-metallic and may be formed from a number of diifere'nt materials, such, for example, as a suitable concrete, Portland cement and sand, gypsum, calcium carbonate, and the like, selected 'to have the desired electrical resistance.

lows:

The emulsion to be treated is introduced into the treating space 20 near the outer elec- The operation of the invention is as foltreated emulsion is withdrawn from the lower end of the tank 11 by means of the pipe 12 which delivers it to a settling tank, not.

shown. It is necessary that a great potential difference be maintained between the electrodes so that a high intensity electric field may be maintained. During the treating of petroleum emulsion there is a tendency for the water particles to form into chains between the electrodes and serve as short-circuiting paths, through which electric current may pass from one electrode to the other. This reduces the potential difference and diminishes the electric field. It will be seen that when short-circuiting occurs the emulsion is not ellectively treated.

In my invention a high intensity electric field will be maintained at all times regardless of the condition of the emulsion passing through the treating space 20. The electrical resistance of the walls 30 and 31 is considerably greater than that of the metallic electrodes. The electrical resistance, in fact, should be substantially that of the petroleum emulsion when it is in a favorable de-emulsitying condition. When short-circuiting occurs, the resistance of the treating space 20 at the point where the water particles line up will be reduced, but because of the fact that the high resistance walls 30 and 31 are formed between the electrodes and the ends of the short-circuiting paths, there will be no heavy flow of current. It will be seen, therefore, that in my invention even though short-circuiting conditions occur in the emulsion, the potential difference of the electrodes will be maintained because of the high resistance walls 80 and 31 through which the electricity must pass.

It will also be seen that formation of carbon is prevented in view of the fact that there will be no heavy flow of current through the treating space 20 and consequently no localized overheating. My invention in its broadest conception consists in the electrical dehydrator having a pair of low resistance electrodes in combination with a high resistance wall placed between the electrodes.

I claim as my invention:

1. In combination in a dehydrator: a central electrode; a surrounding electrode, said electrodes providing a treating space; means for establishing an electric field in said treating space; a coating of high resistance conducting material applied directly to the suriace oi said central electrode and in said treating space; and means for passing emulsion through said treatin space.

2. In combination in aehydrator: a shell constituting a primary electrode and having a lining of high resistance material applied directly to its inner surface; a secondary electrode within said shell and insulated therefrom and having a coating of high resistance material applied directly to its outer surface; and means for passing emulsion through the space between said lining and said coatin In combination in a dehydrator: a tank comprising a primary electrode; a secondary electrode in said tank, there being a treating space between said electrodes; means for establishing an electric field in said treating space; a coating of material of high electrical resistance on one of said electrodes; and means for introducing emulsion into said tank adjacent and along said coating.

4. In an electric treater for electrically treating petroleum emulsions, the combination of: a primary electrode; a secondary electrode spaced from said primary electrode; a pair of walls, each wall being positioned adjacent the surface of one of said electrodes and covering the opposed surfaces of said electrodes; means for impressing a difference of potential between said electrodes to set up an electric field therebetween; and means for introducing the emulsion to be treated into said electric field and between the walls positioned adjacent said electrodes whereby said emulsion cannot bridge the space between the opposed surfaces of said electrodes.

5. In combination in a dehydrator: a primary electrode; a secondary electrode, there being a treating space between said electrodes; means for establishing an electric field in said treating space; a coating on one of said electrodes and formed of a material having an electric resistance substantially equal to the electric resistance of an equal volume of emulsion of similarshape which is in a favorable de-emulsifying condition; and means for introducing the emulsion to be treated into said treating space:

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 18th day of March, 1927.

CHARLES WV. GIRVIN.

I CERTIFICATE OF coaaecrlou.

Patent No. 1,838,937. Granted December 29, 1931, to

CHARLES aw. omvm.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 63, claim 1, for the word "coating" read wall; lines 63 and 64, same claim, strike out the words "conducting material applied directly tothe surface of" and insert instead material located adjacent to; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of April, A. D. 1932.

. M. J. Moore, (Seal) Acting Commissioner of Patents.

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