US2240495A - Apparatus for coalescing foam - Google Patents

Description

May 6,1941. L. DLLLON Em 240,495

APPARATUS FOR COALESCING FOAM Filed Sept. l2, 1936 v K INVENITORS LyZezZZozz Edwardgaz Patented May 6, wel

APPARATUS FOB COMESCING FUAM Lyle millon and Edward G. Ragatz, Los Angeles,

Calif., aneignen: tollnion Oil Companyof Caliiornla, Galliornia Los Angeles, Galli., a corporation or This invention relates to foam coalescence and particularly'to the coalescence of hot foamy oil to form a gas-free liquid.

. Oil, such as a heavy residual petroleum oil fraction or the like, when heated as when it is intr'oduced into a vaporizer or fractionating column where vaporization and agitation takes place. often forms a gassy foam which persists for long Periods of time without coalescence. When it is necessary totransport such ioamy oil rapidly and in. large quantities from one point to another through pipe lines while hot, diiliculties in the fornrof loss of suction on the pipe lines to the pumpand 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 diiculties associated with pumping hot foamy oil or oil carrying entrained gas, by providing apparatus for rapidly coalescing the foam and freeing the gas.

It has been discovered that oil foam or froth can be rapidly coalesced by subjecting it to th influence of an intense electric field.

The invention accordingly resides in apparatus for coalescing foam whereby the foamy body is subjected to an intense electric ileld to break the foam and release the gas to form a relatively gasfree pumpable liquid body. The invention resides more specically in apparatus for subjecting hot foamyoil to the influence of an intense ionizing electric held whereby the foam bubbles are rapidly broken, the gas released and the oil coalesced to forma gas-free liquid body which may be readily and eiciently pumped.

Other objects and novel 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 sectionalelevations of alternative embodiments of the invention.

Fig. 5 is a plan section taken on line 5 5 of Fig. 2.

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

The apparatus is as follows:

Fig. lpdiagrammatically illustrates a convenrod-shaped electrodes il are supported by means- I. of the lead-in insulator bushing iii. These v`rodtional hydrocarbonoil fractional distillation system employing recirculation of bottoms or partially strippedmaterial. The main units of this system are as follows:

H is a 'tubular heater adapted tc-heat the 'hydrocarbon oil feed prior to its introduction into the intermediate vaporizing zone of the fractionating column C. A is the foam ooalescing 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 com-V prising 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 verti cal gas-tight cylindrical tank i0 having a large foamy oil inlet pipe ii, gas outlet pipe i2 and a coalesced oil outlet pipe i3 at the bottom. At an intermediate section of the coalescing chamber cylinder a horizontal coalescing tray ifi is provided which partially divides the chamber into upper and lower sections which communicate with one another only through the opening i5 Where the tray does not extend entirely across the cylindrical section. In the upper section ofthe coalescing chamber a plurality oi vertical shaped electrodes which are constructed of pointed wires or rods approximately 1x6" in diameter and approximately on 3 centers are suspended with their lower pointed ends directed toward the upper surface of lthe coalescing tray A liquid level operated float 2li is provided to operate the valve 2i to maintain the coalesced liquid-level within the coalescing chamber approximately at the liquid level line as shown at 22. The liquid level operated oat 2li thus operates the valve 2| to open it when the liquid level 22 rises above the line 22 to allow coalesced oil to flow out through the line i3 and to close the lvalve 2i when the liquid level falls below the line 22.

In Fig. 3, which is an alternative arrangement of rthe 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 25 is supported by the rod 26 through the lead-in insulator bushing i8. The foamy oil inlet system comprises pipe Il which leads to an internal cir- .the coalescingtray intense ionizing electric iield from the pointed, 75

cular distributing manifold 21 which carries from its lower surface a plurality of4 nozzles 2l adapted to direct the foamy oil downward inthe form of relatively small streams or sprays which impingeupon 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 nozzlel a rod electrode-29 is provided attached to `electrode 25. The foamy ,oilv inlet makes con. A nection with the inside o f the launder 3|.

The'operationisias follows; v

ends of theelectrodes il. The effect of this ionizing electric field is to cause a rapid calescence of the foamy oil and freeing of gas so that the materiali passing from the top of the coa- 'lescing tray I4 and falling to the lower section ,of the coalescing chamber through the passageway I5 is a substantially gas-free liquid. Thatl portion .of the oil passing through th'e passage- I the inside of th nozzle at 30 and extending coaxially through the orifices thereof to way which still remains 'foamy issoon coalesced upon standing in the lower portion of the coalescing chamber.

the oil ,Aare .returned to the fractionating column through the gas return line I2.

' ,-The 'substantially vgas-free. oil is withdrawn from the lower section of the coalescing chamber through the oil outlet I3 and forced Aby means of pump Pinto .the heater H where it commingles with the feed material passing through the heater tubes.`

The liquid level iloat control 20, as described -.hereinbefore, operates the, liquid level control The hydrocarbonll feed to be distilled is suplplied to the heater H at the feed inlet 35V and after being heated jto a vaporizin'g temperature is introduced into the intermediatevyaporizing section V of the fractionating column C through.

the line 36. The unvaporized oil from the vaporizing section of the fractionating column passes downwardly through the stripping section S thereof in' countercurrent contact with stripping steam introduced at the bottom at 31.- The comb ined vapors from the oil feed and the stripping section of the column pass upward through the fractonating section F of the column in countercurrent contact with reflux condensate to produce overhead fractionated vapors in the conventional' manner.

It is now common practice to withdraw unvaporized oil from the bottom or from an intermediate zone of the stripping section of the fracvalve 2|. to maintain the liquid level vwithin 'the coalescing chamber at approximately the line Y22.

The electrodes l1 are individually adjusted in 4 height so that the spacing between the lower ends thereof and theupper surface of the o oalescing tray I4 which vconstitutesrthe electrode of opposite polarity will be just suilicient 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. A

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 potentionating column and to recirculate this wthdrawn oil to the heater to act as a heat storage medium to convey additional heat of vaporization for the feed material to the vaporizing section of f the fractionating column. Heretofore, this withdrawn material has been pumped directly from the draw-off point below the vaporlzing 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 oi the fractionating column, to be recirculated, contained-a large proportion of entrained gas and foam, which resulted in a material reduction in the volumetric efiiciency 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 hasno opportunity prior to its withdrawal from the column to coalesce into .a gas-free liquid which.

could'be readily and eiiiciently handled by the pumps. Moreover, the foamis found even upon standing to persist for long periods of time so thatmspecial means are necessary to effect its cqalescnce. Y. A

in the.' present invention, therefore, the withdrawnpbtottoms material from the lower portion of the fractionating column is introduced through a large line 39 into a coalescing chamber A. Here, asvshownl in Fig. 2, the foamy oil 'entering,the coalescing chamber is distributed in a layer over I4 where it i's subjectedt the tial transformer T, the output of which is rectiliedl by means of the mechanical rectifier R to produce high potential pulsating unidirectional current which is conducted through the lines 4|) and 4| to the lead-in insulator connection to the electrodes Il and to the coalescing chambershell IU respectively.

In Figs; 8 and Il alternative arrangements of the electrodes and foamy oil distributors within the coalescing chamber are illustrated. In Fig. 3 the foamy oil enters the A coalescing chamber through the supply line in to the circular distributor manifold 21. The foamy oil is projected from the manifold through the nozzles 28 in the forms of streams 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 ileld formed around the lower point of the rod electrode 29. As the thus charged foamy oil lmpinges upon the electrode 25 the bubbles are rapidly broken and gas freed to form a coalesced, substantially .gas-free oil4 which may be readily pumped from the bottoml 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 theupper surface of the disc electrode 25.

While the apparatus of this invention for coalescing foamy oil has been shown in Fig. 1 by way of illustration, as applied to a conventional fractional distillation system employing recircu- 1 lation of bottoms material, it is obviously applicable to any other system where the coalescence The gases thus freed from of foam is advantageous. Moreover, the method and apparatus of the invention is not limited to the coalescence 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 liquid comprising a tank, a at electrode in said tank, means to pass the foamy liquid onto said electrode to form a layer thereon, a second electrode in the upper part of the tank adjacent to the surface of said flat electrode, means to charge said electrodes to a high electric potential diierence, a settling chamber in the lower portion of the tank, and means to separately withdraw gas and coalesced liquid from said tank. l q

2. Apparatus for coalescing foamy liquid comprising a tank, a flat electrode in an intermediate portion of said tank, a pointed electrode in the upper portion of said tank, means to pass the foamy liquid over said iiat electrode and under said pointed electrode, means to transfer foamy oil from said at electrode to the lower portion of said tank and means to separately withdraw the gas and coalesced liquid from said tank.

LYLE DILLON. EDWARD G. RAGATZ.

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