US1943822A - Method and apparatus for countercurrent washing - Google Patents

Description

Jan. 16, 1934. P. J. HARRINGTON 1,943,822

METHOD AND APPARATUS FOR CVOUNTERCURRENT WASHING Filed Oct. 20. 1930 Ago l if l2O b #ig/M1 5% t www om o ,ZM/150 PAUL J. Hmnmaron 5; ATTORNEY.

Patented Jan. 16, 1934 UNITED STATES METHOD hulllnnrrlngton,

Standard Oil AND APPARATUS FOR COUNTER.-

CURBENT WASHING Elizabeth, N. J., assigner to Development' Company Applicationootobet 20, 1930. Serial No. 9 Claims. (CL 21H9) I This invention relates to the counter-current treatment of iiuids. The invention will be fully understood from the following description taken in connection with the accompnyihs drawl ing, in which lather Fig. 1 is a longitudinal sectional view of one form of apparatus suitable for carrying out the invention;

Hg. 2 is a longitudinal sectional view of a 1 modified form of apparatus: and

Fig. 3 is a longitudinal sectional view of still another modified form of apparatus.

The invention is directed particularly to the counter-current treatment of immiscible liquids 15 of diiferent gravities and will be described in connection with the counter-current washing with water of mixed alcohol and naphtha.

Referring particularly to Fig. 1 of the drawing, there is shown a tower the shell of which N is designated by reference numeral 1. The shell is divided .vertically into sections by means of a plurality of perforated plates 2 which extend substantially horizontally across the tower. A drain pipe 4 extends downwardly from each perforated plate for a substantial distance sunlcient to permit the accumulation of a'layer of light liquid of sumcient thickness to provide a differential headwhich will give the spray effect and capacity desired. 'I'he relatively light 8 mixture or mpntna and alcohol is into the lowermost section through'a line 6 at a rate of ow controlled by any suitable means, not shown. The relatively light liquid flows upthrough the shell and is discharged from wardly u the uppermost section through a discharge line 8. The relatively heavy liquid such as water is introduced into the uppermost section through a pipe 9 at a rate of flow controlled by any sultable means, not shown. Pipe 9 preferably opens 4 into approximately the middle portion of the section. The relatively heavy liquid flows downwardly from one section 'to another through pipes 4 and is dischargedfromV the lowermost section through aline 10. llhe relatively light liquid 5 iiows upwardly from one section to another through the perforations in the plates. The means for controlling the feed of relatively heavy and relatively light liquids into the shell can be a proportional rate of flow controller if desired. 5 mtomanuedwitntneeounr-currenuy moving bodies of immiscible liquids of diii'erent gravities. The downwardly iiowingrelatively.

5 uneiowtnmumunuonmnqumabm each perforated plate in a layer of substantial thickne. This level is maintained by means of a regulating device which comprises a iloat 12 and members 13 which areconnected with a valve 14 in the outletv line 10. Any standard airdu actuated or direct acting duo-gravityliquid level control can be used. The depth of the body of water maintained above each perforated plate may for example 'be approximately 3-5 ft. for a tower 2 ft. in diameter.

The relatively light liquid flows upwardly through the tower in sumcient .volume to accumulate in a body underneath each perforated plate filling the space between the body of relatively heavy liquidin each section and the perforated '(0 plate. The depth of the body of mixed alcohol and naphtha below each plate can be approximately 3-5 ft. for a tower 2 ft. in diameter. Each bow of the relatively light liquid is of such thickness that there is sufficient differential head of liquid or driving head occasioned 'oy and proportional to the difference in gravity of the two liquids and the thickness of the lighter liquid layer with the corresponding column of heavy liquid in pipe 4 to cause the streams of relatively light liquid i'iowing upwardly through the openings of the plates 2 to break up into a myriad of very line drops forming a spray or mist. The head may be sufiiciently great so that with large gravity differences inl the liquids and low interface surface tensions betweenthe liquids an actual emulsion of more or less permanency will be formed. The small mist drops are formed whether the perforations of the plate are large or small. The perforations are o f such size that emcient commercial operation of the device, with large throughput. can be carried on. The number or size of the holes in the plates of the upper portion of the tower can be changed in'order to obtain finer bubbles of the relatively light liquid. 95

By the method described, transfer of material from one liquid to another is facilitated by the very small bubbles of the one liquid. which give more surface exposed to contact with the other liquid. vAlso.'the time of contact of the two liquids is at a-maximum, due to the fact lthat vthe .bubbles are of extremely small size, and therefore rise through the relatively heavy liquidmore slowly. Similarly, the presence of a relatively thick lave!!` of the heavy liquid providesa greater distance through which the lighter liquid-must pass while The towerinwhichthewashingis...

-iseontinuousandthereisasavingin labor, and water.

MwiNwHgJofthedrawi/ngamodifiedllo form of the apparatus is shown which comprises a shell 1 and perforated plates 2 as previously described. Drain pipes 16 extend upwardly from the perforated plates for a distance 'sufilcient to prevent overflow of the heavy liquid through the pipes, until a body of the liquid of relatively great thickness is accumulated on the plates. This distance can be sufilcient to permit the accumulation of a layer of heavy liquid of sumcient thickness to provide a differential head which will give the spray eiect and capacity desired. The relatively heavy liquid is introduced into the uppermost section through a conduit 17 which opens into the section at an intermediate portion of the section. The relatively heavy liquid is discharged from the lowermost section through a line 18. The relatively light liquid is introduced into an intermediate portion of the lowermost section through a line 19. The rate offfeed of the relatlvely'light and relatively heavy liquids into the shell is controlled as previously described in connection with Fig. 1.- The upwardly flowing lighter liquid accumulates under each perforated plate as previously described and flows through each drain pipe 16 into a body of the lighter liquid accumulating under an upper plate. The relatively light liquid is discharged from the uppermost section through a line 20. The descending water is forced to collect above each plate until there `is suillcient head to force the water through the plate holes in the form of drops of spray which fall through the naphtha layer and unite on the next lower plate to complete the cycle.

As a result of this construction, it is possible to re'duce the resistance of the liquid film of either liquid at will by making the other liquid the dispersed phase. 'I'he washing operatiox is a diffusional process depending for its rate of transfer of solute from one solvent to the other not only on the available concentration diilerence and surface exposed, but also on the resistance to diffusion of the films of liquid on each side of the liquid interface. 'I'he resistance of these films varies greatly Vwith the nature of the liquid sothat in many cases one lm offers much the greater resistance.

It will be understood that there can be com- A bined in one Shen the type or sect-,lon shown in Fig. 1 in which vdispersion of the relatively light liquid in the heavier liquid is effected and the type of section shown in'Fig. 2 in which dispersion of the relatively heavy liquid in the lighter liquid is effected. These sections can be combined in any number or combination to secure the desired result. For example they can `be dlSDOSed alternately, or with the type of section shown in Fig. 2 in the upper portion of the shell and the type of section shown in Fig. 1 in the lower portion of the shell. Any other desired arrangement can be used and some of the advantages of the invention will beretained. t l

Referring to Fig. 3 of the drawing a construction of washing tower is shown in which countercurrent passage of the liquids successively through each other in the form of a myriad of fine drops is effected. In this'deviee one or more sections are provided fin which the upper perforated plate is provided with an upwardly extending drain pipe 16 `as previously described. The lower perforated plate of the given section is provided with a downwardly extending drain pipe 4v as previously described. The relatively heavy liquid ilowsdownwardly through the sections and accumulates upon the upper perforated Y plate of- 'a given section and is discharged through the perforations in al myriad of nne bubbles one or both liquids which will change the surface tensions of, or interface surface tension between the liquids. For example, in the case given, soaps, alcohols or the like may be added to the fresh water in small amounts, reducing its surface tension and reducing the interface surface tension between naphtha and water. With the same head the energy available (due to loss of head in passing through the holes in the plate) will resultin the generation of greater surface,. or the formation of smaller droplets.

While the invention has been described as applied to the washing of mixed alcohol and naphtha with water, it will be understood that it can be used for washing naphtha with caustic, for treating distillates with acid .for extracting oils with phenol, or with liquid sulphur dioxide, or for any pther purposes in which a plurality of immiscible liquids of different gravities are to be washed. By the counter-current treatment described the best concentration differential or differential driving force possible can be obtained between the liquids involved. For example if y fresh water is contacted with fairly well-washed naphtha and water containing a good deal of alcohol with the naphtha alcohol mixture richest in alcohol, Ythere is maintained the best concentration diiferential or differential driving force possible. A t the same time aminimum of water ls used and there is produced a strong water al-.ll cohol solution and well washed naphtha;

Various changes may be made-within the scope of the appended claims, in which it lis desired to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. Counter-current apparatus which comprises a shell, substantially horizontally disposed perfo-- rated platesdividing the shell vertically into sections, and a drain pipe extending from each plate for a substantial distance toward an 'adjoining plate, the uppermost and lowermost sections having inlets and outlets.

2. Counter-current apparatus, which comprises a shell, substantially horizontally disposed perforated plates dividing the shell vertically into sections, and a drain pipe extending downwardly from each plate for a substantial distance toward an adjoining plate, the uppermost and lowermost sections having inlets and outlets.' I

8. Counter-current apparatuawhich comprises a shell, substantially horizontally disposed perforated plates dividing the shell vertically into sections, and a drain pipe-extending'- upwardly 1140 from each plate for a substantial distance toward an adjoining plate,l the uppermost and' lowermost sections having inlets and outlets.

4. Counter-current apparatus, which comprisesv j a shell. substantially horizontallydisposed perforated plates dividing the shell vertically into sections, and a drain pipe extending from each plate for a substantial distance into the adjoining section, the drain pipes ot at least one of the sections extending in opposite directions, the up- 15G permost and lowermost sections having inlets and outlets.

5. The method of countercurrent washing in superimposed zones separated by a perforated partition, which comprises passing a relatively heavy liquid into an upper zone, conducting the heavy liquid from said zone in a continuous confined stream directly into an intermediate portion of a lower zone at a rate to cause accumulation of a body of the heavy liquid above the perforated partition, passing a relatively light liquid non-miscible with the heavy liquid into the lower zone whereby the light liquid rises to the perforated partition and accumulates to form a body above the discharge of the confined stream and having sufcient head to flow upwardly through the perforations and through the body of heavy liquid in drops. f

6. The method of countercurrent washing in superimposed zones separated by perforated partitions, which comprises passing a relatively heavy liquid into the upper zone, conducting the heavy liquid from said zone in a continuous confined stream directly into an intermediate portion of a first lower zone at a rate to cause accumulation of a body of the heavy liquid above the perforated partition of the upper zone, withdrawing the heavy liquid from theiirst lower zone in a continuous conflnedstreamjdirectly into an intermediate portion of a second lower zone at a rate to cause accumulation of a body of the heavy liquid in the first lower zone, passing a relatively light liquid non-miscible with the heavy liquid into said second lower zone whereby the light liquid rises to the perforated partition at the bottom of the first lower zone and accumulates to form a body above the discharge of the confined stream and having sufflcient head to flow upwardly through the perforations and through the body of heavy liquid in drops, and

similarly accumulating the light liquid above the` heavier liquid in the rst lower zone in a body having sufficient head to flow upwardly through the perforations of the partition at the bottom of the upper zone. y

"7. The method of countercurrent washing in superimposed zones separated by a perforated partition, which comprises passing a relatively heavy liquid into an upper zone whereby the heavy liquid accumulates to form a body of the liquid upon the perforated partition and flows through the partition in streams to a lower zone,

a relatively light liquid non-miscible with the heavy liquid into the lower zone whereby the light liquid rises to the perforated partition to form a continuous body of the light liquid through which the streams of heavy liquid must pass, and conducting the light liquid from the last mentioned body in a continuous confined stream into a portion of the upper zone above the heavy liquid.

8. The method of countercurrent washing in a series of superimposed zones separated by perforated partitions, which comprises passing a relatively heavy liquid into the upper zone whereby the heavy liquid accumulates to form a body of the liquid upon theperforated partition at the bottom of the upper zone and iiows through the partition in streams to a rst lower zone, conducting the heavy liquid in a continuous confined stream from the first lower zone: directly into an intermediate portion of a. second lower zone at a rate to cause accumulation of a body of the heavy liquid above the perforated partition at the bottom of the first lower zone, passing a relatively light liquid non-miscible with the heavy liquid into the second lower zone whereby the light liquid rises to the last mentioned perforated partition and accumulates to form a body having a sufiicient head to fiow upwardly through the perforations through the body of heavy liquid thereabove in streams to accumulate in a body above the heavy liquid in the first lower zone, and conducting the light liquid from the last mentioned body in a continuous confined stream directlyk into an intermediate portion of the upper zone.

9. The method of countercurrent washing of non-miscible liquids of different specific gravities in an upper and lower zone separated by a perforated partition, which comprises passing the relatively heavy liquid into the upper zone at a rate .to cause accumulation of a body of the heavy liquid above the partition, passing the relatively light liquid into the lower zone to form a body of the light liquid beneath the perforated partiion, conducting one of the liquids from its zone in a continuous confined stream directly into an intermediate portion of the other zone, and conducting the other liquid from its zone through the perforations and through the body of liquid on the other side of the partition in drops.

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