US1722322A - Continuous rectification of liquids at high boiling point - Google Patents

Description

E. A. BARBET July 30, 1929.

CONTINUOUS RECTIFICATION OF LIQUIDS AT HIGH BOILING POINT Filed June ll, 1923 Patented July 30,11929.

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EMILE AUGUSTIN BARRET, OF PARIS, FRANCE.

CONTINUOUS RECTIFIATION 0F LIQUIDS AT HIGI BOILING IOINT.

Application filed June i1, 1923, serial NQ.

This invention relates to the continuous rectification of hydrocarbons and other liquids containing constituents of high boiling point.

In performing the continuous rectification of hydrous alcohol no dificulties are encountered in producing an'intensi've ebullition in the base of the apparatus, and thereby obtaining at the upper part of the rectifier gradation) liquid for refining the alcoholic vapours.` y

In the treatment of hydrocarbon and otherV liquids of high boiling point, such as heavy benzenes, petroleum andA the like, difficultiesare experienced in securing this result. It is,lhowever, in the treatment of such liquids highly desirablev to employ rec-I tification as by the passage of bubbles of vapour through the refiux in a plate column a much sharper fractionation can-besecured Cil ythan by mere condensation.

kAccording to the invention these difficulties are overcome by supplying the rectilication apparatus With the material in the form of vapour instead of in the form of liquid and for this purpose the rectification apparatus employed vis combined with a vaporizerin which the initial material is completely or as far as possible vaporized in two stages by the employment of saturated steam in the first stageand of superheated steam in the second stage.

It is 'known to combine distillation apparatus with vaporizers but in' the known cases this is done only in connection with distilling as distinguished from rectifying apparatus, that is to say an apparatus in which the fractionation is effected not by rectification but merely by condensation. In rectification apparatus such evaporators are not employed.

It is desirable to push the rectification to such a degree that fractions having a high degree of homogeneity, such as a rectifying column alone is capable of producing, are obtained. As a matter'of fact, only a plate column working upon previously condensed refluxes, iscapable of effecting an accurate separation of the components, and thusv pro-r ducei relatively light oils (spindle oils), medium oils (machinery oils), and heavy oils (valvoline) for lubrication atvery high temperatures.

Apparatus for achieving the above-stated plates an abundance of reflux (retro- ..l-

644,774, and in France December 11, 1922. Y

drawing. l

A sepa-rate column might be provided for the continuous treatment of the oils, but the apparatus shown in the drawing comprises only one'plate column for effecting the eX- traction of the lighting oils in its upper part, and for effecting `the fractionation of the three classes of oilA in its lower part.

Only the initial vaporizer `M must not be relied upon for vaporizing lubricating oils. For this purpose a much hotter steam is required, namely, superheated steam.

In general superheated steam is not an advantageous means for heatingto high v temperatures with the interposition of a heating surface, because it is nothing more nor less thanl a gas, 'and gases have small specific heat and a bad coefficient of heat transmission to heating surfaces.

But in the present case, on the one hand the specific heat of Water vapour is more advantageous than that of air, and on the other hand the-liquids to be heated and vaporized have very low coeflicients of specific heat and latent heat of vaporization. Moreover, in the case of a raw petroleum of the American type, the preliminary extraction of the petrols (gasolines)`A and lighting oils has already reduced the liquid to about 30% of its initial volume. IAll these circulnstances render'the use of superheated steam quite effective.

In view of the foregoing, the working of the apparatus shown in the drawing will be readily understood. j

Instead of the petrol (gasoline) vapour and the non-vapourized products being sent all together into the rectifying column, the liquid and the vapour are carefully separatd. Only the vapour enters the column at The liquid oils kept back by the separating flask O descend by way of a Siphon-pipe into the second vaporizer M which is heated by highly superheated steam. This second vaporizer is very carefully insulated against heat-loss. y'

The mixture of vaporized oils and oils that are refractory to vaporization passes into the lower part of the rectifyi'ng column bling-up through the reuxes of the upper plates. The three cocks P1 P2'and P3 draw e off respectively the above-referred to three qualitiesof oilsy in the liquid state, whilst the lighting oils pass out as before through the cocks P4 and P5.

' All these extractions pass into cooling worms and enter sheet-metal containers under vacuum. v The circulation of the superheatedsteam in the second vaporizer must 'be assured.

i heat, that is to say, steam which is sufliciently'superheated, since this source of heat is much less harsh than the heatof a direct fire, and is therefore less destructive to ythe lubricating properties of lubricating oils.

All which has been stated respecting pe- `tr'oleum oils, applies equally for all the other l jethylenic7 cyclic, hexano-cyclic hydrocarbons, as well forphenols, cresols, chlorobenzenes, nitro-benzenes (nitro-benzols) &c., all of which are productsthat can be-fractionated very properly by means of .steam and the use of vacuum,i provided however that the rectifier shall no longer be fed with the hydrocarbons in the liquid 'state -as is generally done, but on the contrary shall be fed with hydrocarbons which have undergone/*preliminary vaporization7 carried as far'as possible,v either by means of saturated steam under high pressure,e or by means of superheated steam.l

The improved lprocess is also 'applicable tothe extraction of benzene (-benzol) from lthe heavy oils .used for extracting benzene (benzol) vapour from coke oven gases. What I claim is Process 'for'thecontinuous rectification of hydrocarbons and other liquids of high boiling lpoint which comprises subjecting the" material to the indirect action of saturated steam whereby a portion of its constituents is vaporized, subjecting the residual unvaporized liquid material to the indirect action of superheated steam whereby the same is mainly vaporized and'bringing the vapours arising in both of the said treatments into intimate Contactin a single rectifying column witha reflux of condensates arising from said vapours and withdrawing the condensed material as af plurality of sharply defined fractions boiling within different temperature ranges.

In testimony whereof I have signed my `name to this specification.

EMILE AUGUSTIN BARBET.

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