US2381578A

US2381578A - Apparatus and method for coalescing foam

Info

Publication number: US2381578A
Application number: US390280A
Authority: US
Inventors: Dillon Lyle; Edward G Ragatz
Original assignee: Union Oil Company of California
Current assignee: Union Oil Company of California
Priority date: 1936-09-12
Filing date: 1941-04-25
Publication date: 1945-08-07
Anticipated expiration: 1962-08-07

Description

L. tflLLoN ET AL APPARATUS'AND METHOD FOR COALESCING FOAM Aug. 7,: 1945.

Original Filed Sept. 12, 1936 m 2 um mm mm u n fl n Z a wa i m M v M M C v w: m

a K w a I an m k m 2 3 A r E. .lYzy/E Potential p/W Fig. '5.is .a plan Patented Aug. 7, 1945 Lyle Dillon, San Gabriel, and Edward G. Ragatz, San Marino, Califl, assignors to Union il Company of California, Los Angeles, Calif., a cor-.

. poration of California Original application September 12, 193 6, Serial No.

100,514. Divided and this application April 25, 1 1941, Serial No. 390,280

5 Claims.

This invention relates to foam coalescenceand particularly to the coalescence of hot foamy oil to form a gas-free liquid. our co-pending application Serial No. 100.514

' of September 12, 1936, now Patent No. 2,240,495,

granted.May 6, 1941.

Oil, such as a heavy residual petroleum oil fraction or the like, when heated as when it is introduced into a vaporizer or fractionating column where vaporization andagitation takes place, often forms a gassy foam which persists for long periods of time without coalescence. When it is necessary to transport such foamy oil rapidly and in large quantities from one point to another through pipe lines while hot, diiiicultiesin the form of loss of'suction on the pipe lines to the pump and hammering in the pumping system often are manifested, with attendant loss of pumping eiilciency and damage to pumping equipment. The object of this invention, therefore, is to eliminate the diillculties associated with pumping hot foamy oil or oil carrying entrained gas, by providing an apparatus for rapidly coalescing "the foamand freeing the gas.

It has been discovei'ed that oil foam or froth can be rapidly coalesced by subjecting it to the influence of an intense electric field.

This is a division of Fig. 6 is an enlarged cross section of one of the electrode jets of Fig. 3.

The apparatus is as follows:

Fig. 1 diagrammatically illustrates a conventional hydrocarbon oil fractional distillation system employing recirculation of bottoms or partially stripped material. The main units of this I system are as follows:

H is a tubular heater adapted to heat the hydrocarbon oil feed prior to its introduction into the intermediate vaporizing zone of the fractionating column C. A is the foam coalescing chamber. P is a pump adapted to recirculate the coalesced oil from the coalescing chamber to the heater. E is a high potential electrical supply for the electrodes in the coalescing chamber comprising a high potential step up transformer T and a synchronous rectifier R.

Fig. 2 is a sectional elevation of the coalescing chamber A which comprises preferably a vertical gas-tight cylindrical tank 10 having a large foamy oil inlet pipe i I, gas outlet pipe l2 and. a coalesced oil outlet pipe ii! at the bottom. At an intermediate section of the coalescing chamber cylinder 8. horizontal coalescing. tray 14 is provided which partially divides the chamber into upper and lower sections which communicate with one an- The invention accordingly resides in an apparatus for coalescing foam whereby the foamy 1 body'is subjected to an intense electric field to break the foam and releasethe gas to form a relatively gas-free pumpable liquid body. The invention resides-more specifically in an apparatus for subjecting hot foamy oil to the influence 1 of an intense ionizing-electflciield whereby the foam bubbles are rapidly broken, the gas released and the oil coalesced toform a gas-free liquid body which may be readily and eiilciently pumped, and particularly in the use of pointed electrodes.

"Other objects andnovel features'of the invention will be evident hereinafter.

In' the accompanying drawing wherein preferred embodiments of the invention are disclosed by way of illustration:

Fig. 1 diagrammatically illustrates a general arrangement. of the apparatus of the invention as associated with fractional-distillation of hydrocarbon oil.

Fig. 2 is a sectional elevation of one embodiment of the invention.

Figs. 3 and 4 are sectional elevations of alternative embodiinents of-the invention.

other only through the opening l5 where the tray does not extend entirely across the cylindrical section. In the upper section of the coalescing chamber a plurality of vertical rod-shaped electrodes I! are supported by means of the leadin insulator bushing l8. These rod-shaped electrodes which are constructed of pointed wires or rods approximately in diameter and approximately on 3" centers are suspended with their lower pointed ends directed toward the upper surface of the coalescing tray M.

A liquid level operated float 20 is provided to operate the valve 2| to maintainthe coalesced liquid level within the coalescing chamber ap-' proximately at the liquid level line as shown at 22. The liquid level operated float 20 thus operates the valve 2| toopen it when the liquid-level 22 rises above the line 22 to allow coalesced oil to flow out through the line l3 and to close the valve 2i when the liquid level falls below the line In Fig. 3, which isan alternative arrangement of the coalescing chamber, the apparatus is the same as that illustrated in Fig. 2 except for the electrode and the foamy oil inlet system. Here a disc electrode 25 is concentrically placed just upon the liquid level line 22 and partially closes the cylinder section 'at that point. This electrode is supported by the rod 25 through the lead-in insulator bushing Ill. The foamy oil inlet system comprises pipe H which leads to an internal circular distributing manifold 21 which carries from its lower surface a plurality of nozzles 28 adapted to direct the foamy oil downward in the form of relatively small streams or sprays which impinge upon the upper surface of the disc electrode 25.

Fig. 6 illustrates an enlarged sectional view of one of the distributing nozzles of Fig. 3. In each nozzle a rod electrode 29 is provided attached to the inside of the nozzle at 30 and extending coaxially through the orificesthereof to a distance of approximately 2 or 3 inches.

Fig. 4 illustrates another alternative arrangement of the foamy oil distributing system within the coalescing chamber. This system comprises a circular launder 3| supported from the walls of the upper section of the coalescing chamber. Along the lower inner edge of the launder is provided a plurality of pointed sheet metal electrodes 32 directed toward the upper surface of the disc electrode 25. The foamy oil inlet ll makes connection with the inside of the launder 3|.

The operation is as follows: v

The hydrocarbon oil feed to be distilled is supplied to the heater H at the feed inlet 35 and after being heated to a vaporizing temperature is introduced into the intermediate vaporizing section V of the fractionating column C through mediate zone of the stripping section of the fractionating column and to recirculate this withdrawn oil to the heater to act as a heat storage medium to convey additional heat of vaporiza-. tion for the feed material to the vaporizing section of the fractionating column. Heretofore, this withdrawn material has been pumped direct-' 1y from'the draw-off point below the vaporizing section of the column to the heater. This practice, however, has in many cases been unsatisfactory for the reason that the material withdrawn from .the lower portion of the fractionating column, to be recirculated, contained a large proportion of entrained gas and foam, which resulted in a material reduction in the volumetric efficiency of the circulation pumps and in serious hammering due to the presence of the gaseous material in the pump cylinders. Since the rate of recirculation of this material is generally much in excess of the feed rate, the withdrawn foamy oil has no opportunity prior to its withdrawal from the column to coalesce into a gas-free liquid which could be readily and eiilciently handled by the pumps. ,Moreover, the foam is found even upon standing to persist for long periods of time so that special means are necessary to effect its coalescence. V

In the present invention, therefore, material from a lower portion of the fractionating column is introduced through a large line H into a coalescing chamber A. Here, as shown in Fig.

2, the foamy oil entering the coalescing chamber is distributed in a layer over the coalescing tray M where it is subjected to the intense ionizing electric field from the pointed ends of the electrodes H. The effect of this ionizing electric field is to cause a rapid coalescence of the foamy oil and freeing of gas so that the material passing from the top of the coalescing tray [4 and falling to the lower section of the coalescing chamber through the passageway I 5 is a substantially gas-free liquid. That portion of the oil passing through the passageway 15 which still remains foamy is soon coalesced upon standing in the lower portion of the coalescing chamber. The gases thus freed from the oil are returned to the fractionating column through the gas return line I 2.

The substantially gas-free oil is withdrawn from the lower section of the coalescing chamber through the oil outlet l3 and forced by means of pump P into the heater H where it commingles with the feed material passing through the heater tubes.

The liquid level float control 20, as described hereinbefore, operates the liquid level control valve 2| to maintain th liquid level within the coalescing chamber at approximately the line 22.

The electrodes I! are individually adjusted in height so that the spacing between the lower ends thereof and the upper surface of the coalescing. tray II which constitutes the electrode of opposite polarity will be just sutllcient to prevent disruptive electrical discharges therebetween when the foamy oil. is normally flowing thereacross. Potentials which have been found satisfactory are from 50,000 to 75,000 volts.

This high potential may be supplied from a high potential generator or any other suitable supply such as for example the high potential supply system E which comprises a high potential transformer T, the output of which is rectified by means of the mechanical rectifier R to produce high potential pulsating undirectional cur rent which is conducted through the lines 40 and 4| to the lead-in insulator connection to the electrodes l1 and to the coalescing chamber shell II! respectively.

In Figs. 3 and 4 alternative arrangements of the electrodes and foamy oil distributors within the coalescing chamber are illustrated. In Fig. 3 the foamy oil enters the coalescing chamber through the supply line H into the circular distributor manifold 21. The foamy oil is projected from the manifold through the nozzles 28 in the forms ofstreams or sprays toward the upper surface of the disc electrode 25. As the foamy oil passes out of the nozzles over the rod electrodes 29 it is highly charged or ionized by the intense ionizing electric field formed around the lower point of the rod electrode 29. As the thus charged foamy oil impinges or falls upon the electrode 25 the bubbles are rapidly broken and gas freed to form a coalesced, substantially gasfree oil which may be readily pumped from the bottom section of the coalescing chamber as described hereinbefore.

In Fig. 4 another alternative arrangement of the foamy oil distributor system is illustrated employing a circular launder 3| over which the foamy oil spills and falls in finely divided streams from the downwardly directed points of the electrodes 32 to the upper surface of the disc electrode 25.

While the apparatus of this invention for coalescing foamy oilhas been shown in Fig. 1 by wa of illustration, as applied to a conventional fractional distillation system employing recirculation of bottoms material, it is obviously applicable to any other system where the coalescence of foam is advantageous. Moreover, the method and apparatus of the invention is not limited to the coalescense of foamy hydrocarbon oil but is equally applicable to the coalescence of animal and vegetable oil and any other similar material in which persistent foams may form for any reason.

The foregoing is merely illustrative of the apparatus of the invention and is not intended to be limiting. The invention includes. any apparatus which accomplishes the same results within the scope of the claims.

We claim:

1. Apparatus for coalescing foamy non-conducting liquids comprising a tank, a flat electrode in the intermediate portion of said tank, a nozzle including a slender rod electrode in the upper portion of said tank, means to project the foamy.

liquid in a stream from the nozzle electrode to the flat electrode surface, means to charge said electrodes to a high electric potential difference whereby the said foamy liquid stream is subjected to an intense electric field, a-settling chamber in the lower portion of said tank, and means to separately withdraw gas and coalesced liquid from said tank.

2. Apparatus according to claim 1 wherein the nozzle electrode is pointed.

'3. A process for coalescing foamy non-conducting liquids comprising projecting the foamy liquid in the form of a'stream from an electrode nozzle having a pointed member to an adjacent electrode of extended flat area and charging said electrodes to a high'electric potential difference, whereby the foamy liquid stream is subjected to an intense electric field and separating the resultant coalesced liquid from the foam.

4. Apparatus for coalescing foamy non-conducting liquids comprising a tank, an electrode of extended surface in said tank, a pointed electrode adjacent said electrode of extended surface. means to charge said electrodes to a high electric potential difference, means to flow the foamy liquid in contact with and from said pointed electrode to'the said electrode of extended area, a separating zone in said tank and means to separately withdraw gas and coalesced liquid.

5. In apparatus for coalescing foamy non-conducting liquids, the combination comprising a nozzle, a slender rod electrode coaxially extending through the outlet of said nozzle, an electrode of extended area adjacent the end of said rod electrode, and means for charging said electrodes to a high electric potential difference.

LYLE DILLON. EDWARD G. RAGATZ.