US1646698A - Fractional distillation process and apparatus - Google Patents

Description

H. KOPPERS Oct. 9

FRACTIONAL DISTILLATION PROCESS AND APPARATUS Filed July 6. 1921 l Patented Oct. 25, 1.927.

Unir-ED srarss Pifrulaivvr ori-fics.

HEINRICH KOPPERIS, 0F ESSEN-EUHR. GERMANY, ASSIGNOR T0 THE KOPPERS DE- VELOPMENT CORPORATION. A CORPORATION v.OF PENNSYLVANIA.

FRAC'IONAL DISTILLATION Application led July 6, 1921, Serial No.

In processes for decomposing natural or artificial liquid mixtures, for instance, 1n the treatment of crude petroleum, or the distillation of brown coal or coal tar, the usual method is to transfer the quantity to be distilled at any one time, possibly fifty tons, to a vessel which is then suitably heated, after which the vapors are separated into fractions by means of cooling and reflux cooling. The different fractions are separated by either raising the temperature or subjecting them to a graduated vacuum, or by Subjecting them to both the raised temperature and the graduated vacuum. This customary process may have the advantage of being so simple that it can be operated by ordinary workmen, but the preliminary treatment of a large quantity of the substance results 1n a number of objectionable features. On account ofthe lack of local uniformity in the supply of heat, no sharply defined separation of the fractions is obtained, and the liquid is or may be overheated and decomposed, which may also cause considerable wear and tear on Athe vessel. )To this must be added the danger of local boiling which may easily occur particularly in connection with larga quantities, and entails detrimental conscquences in the way of violent over-boiling. The treatment of such large quantities by stepwise operation also involves the danger of fire and explosions. Attempts have been madeto remove objectionable.features of the stepwise processby subjecting these liquid mixtures to constant treatment by conducting them in an uninterrupted current' through a number of vessels which are regulatedpas regards their temperature' and the pressure, for the expulsion of the different lfractions, the latter being obtained in as many coolers by re-liquefying. However efficient such an uninterrupted process may be. both the arrangement and the operation become so complicated. that ordinary workmen are no longercapable and supervision by specially trained 'attendants becomes necessary. For that reason, this process has not been adopted to the extent which might. have been expected, on account of the above mentioned objectionable Vfeatures of uninterrupted or continuous operation. l

The present invention relates toa process and arrangement for .the stepwise distillation of any desired liquid mixtures, combining the advantages of the present 11n- PROCESS AND APPARATUS.

482,804, and in Germany April 22, 1918.

interrupted operation and the constant distillation," while excluding the disadvantages, this being accomplished by conducting the quantity to be distilled at any time 1n a constant current through a single dlstillation apparatus, in which the distillatlon, with the aid of refiux cooling, is divided 1nto two sharply separated fractions. In connectlon therewith, the residue of the first distilledl charge, by properly regulating the temperature and the vacuum in this distillation apparatus and the reflux cooling, is again subJected to distillation and in this connection the distillation is again divided into two fractions. Then in this manner by suitable repetition a complete distillation of the first quantity separated has been accomplished, al new liquid quantity is subjected to the same process. The arrangement suitably psed for this process consists of the distillation apparatus proper and two receptacles which can be alternately connected in such a way that, 'during one operating stage, one of them contains the quantity to be distilled and the other one receives 'the resultant residue, while, by setting the apparatus for thesecond operating stage, the task of the two receptacles is reversed, the first one now 'receiving the residue remaining after the distillation and the second one containing the mixture to be distilled. In order to enable this residue and the two fractions obtained by liquefying to fio'w back freely, in View of the possibly greatly increased vacuum, the distillation device, thc. dephlegmating column with reflux c ooler and the final cooler are placed at so high a point that a free fiowing back into the low level storage or catching receptacles is rendered possible at any time.

In order to make the invention more clearly understood there is shown in the accompanying drawing-means for carrying the Asame into practical effect, the invention not to belimited to the particular embodiment which is herein used for illustration and explanation. In'said drawing is shown an elevaton of an apparatus for stepwise distillation according to my invention.

The lo'w receptacles, 10 and 11, are connectedwith each other by pipes 12 and 15 and may be, each respectively, connected, by means of the three-Way cock 13, to the conduit 14 and by the three-way cock 16 to the pump 17, which latter, by Wag, of e by-pass 18 and a regulating device 19 raises the liquid tothe distilling device proper through conduit 20. Said device consists of the H at trays or pans 21 which are connectedin series by the over-How pipes 22 to prov1de a worm path in which a zig-zag route 1s also imposed on the liquid by means of ribs. The heating takes place in this connection by pipe coils 32 located in the liquid or cast into the bottom and operated with water under pressure. Through the conduits 423 the trays above the same have coils 31 cast into'thejacket through which steam or water liows in order to make it possible accurately to regulate the temperature in the lower and the upper parts, for the purpose ot separating at anytime two different liquids of given properties; in order to maintain the continuity of action automatic regulators can be applied. rIhe dephlegmator as such is insulated since it is merely supposed to be a washing device. y

The liquid quantity subjected to treatment at any tlme is iilled into one of the receptacles yfor instance, 11, which isl closed against conduits 12 and 14 by means of the cock 13, while connecting with the pump 17 through cock 16.

The liquid is conducted, in a quantity Aregulated per time unit by the by-pass 18,

through the trays21 where the temperature and pressure conditions are so adjusted that the group of ingredients boiling rst is ex` pelled. The reflux cooling for the dephlegmating column 24 is also adjusted with reference to these conditions so -that a separar 'tion into two parts is obtained which reach the receptacles 28 and 30. The resultant residue of the distillation of the mixture in the receptacle 11 which remains during this first stage 'goes through conduits 14 and 12 into the receptacle 10. When the entire quantity which was' contained in the receptacle 11 has been treated, the cocks 13 and 16 are reversed, while at the Asame time the temperature and pressure conditions inthe distilla-` tion device 21 and the/redux cooling column 24 are regulated for the next fraction. In this manner, complete distillation ot this originally dividedquantity is possible under conditions which can .be regulated and observedfwith accuracy, in which connection the apparatus can be operated without any diiiiculty and with perfect safetyby ordinary workmen. Since only a comparatively small quantity is subjected to distillation at any one time,all local inequalities which are unavoidable in heating large quantities can be ol'iated, which renders possible a sharp separv tionof the fractions and precludes the possibility of local over-heating with decomposition and deposits. The small quantity in l conjunctionV with the constant movement ot the liquid through the distillation device also does away with the local boiling and thus the over-boiling. and also a `high degree of safety in regard totire is attained. vAt the same .time the exceptionally important structural advantage is obtained for the arrangement that the distilling trays can be made ot' cast iron to protect them against undue Wear, which would be impossible in connection with a large vessel which is subjected'alternately to heating and cooling and subject to a yhigh vacuum. The manner ot' treatment described also permits of a. further improvement: the raw material to be expelled frequently contains acids or salts; thusl certain oils eliminate` muriatic acid at high temperatures, while other oils or tars contain ammonium chloride. Now, so that corrosion or obstruc-` tions by salts may be avoided, a layer of carstallation and the operation, since the wear is very slight.

1. An apparatus for the stepwise distillation of natural or artificial liquid mixtures of ingredients which have dierent boiling points. .having in combination: storage receptacles, a series of vaporizing devices connected thereto an'd arranged one above another, pressure means arranged to deliver a quantity of the liquid mixture from said storage receptacles to the uppermost otsaid vaporizing devices, and means .for conducting the residue of said liquid mixture from the lowermost of said vaporizing devices to said storage receptacles, each of said vaporizing devices consisting` of a fiat cast iron tray through which the liquid flows in'a thin layer, an'd provided with heating means.

2. A process for the stepwise distillation of natural or artificial liquid mixtures ot' ingredients which have different boiling points, for separating the ingredients at different boiling points, one group i ingredients at a time, whlch consists in: passing a quantity of such mixture in a constant ingredient of the group to be eliminated; passing the eliminated ingredients -into a dephlegmator Whose temperature is regulated for separating one fraction; passing the remainder of the eliminated ingredients to a cooler Whose temperature is regulated to take off the other fraction: discontinuing the elimination of such group of ingredients and regulating the temperature and pressure conditions in the vaporizing device and regulating the temperature. in the dephleglnator and in the final cooler for the elimination of another higher boiling point group; and then passing the remainder of said quantity of said mixture through the same Vaporizing device and passing the ingredients vaporized therein into the same dephlegmator and into the saine cooler.

3. A process for the stepwise distillation of natural or artificial liquid mixtures ot ingredients which have different boiling points, for separating the ingredients at ditferent boiling points, which consists in: passing a quantity of such mixture in a constant current through a vaporizing device Whose temperature and pressure conditions are regulated to distill off a group of ingredients having diterent boiling points, said vaporizing device being regulated with reference to the highest boiling point ingredient of `that group; passing only the vap-orized ingredients from the vaporizing device to a dephlegmator and cooler, the

temperature of said dephlegmator and said cooler being regulated with reference to the fractions being eliminated; discontinuing the elimination of such group from said quantity of such mixture and regulating the temperature and pressure conditions of the same vaporiziug device and the temperature of the same dephlegmator and of the same cooler with reference to 'another group of ingredients having dilerent boiling points all of which are higher than the boiling points of the preceding eliminated group; then passing the remainder of said quantity of such mixture through the same vaporizing device and passing only the gredients from the vaporizing same dephlegmator and cooler.

'HEINRICH KOPPERS.

vaporized indevice to the

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