US2551361A - Apparatus permitting a thermal transformation, particularly for isomerization of pinene into dipentene - Google Patents

Description

y 1, 1951 P. M. BOURDON 2,551,361

APPARATUS PERMITTING A THERMAL TRANSFORMATION PARTICULARLY FOR ISOMERIZATION OF PINENE INTO DIPENTENE Filed Feb. 8, 1949 [WE-Mm? Ham M1 051 Baa/1W4 Patented May 1, 1951 APPARATUS PERMITTING'A TRANSFORMATION, PARTICULARLY FOR ISOMERIZATION INTO DIPENTENE Pierre Marcel Bourdon, Paris, France, assignor to Manufacture de Caoutchouc Michelin (Puise'ux, Bculanger et Cie), Clermont-Ferrand,

France .OF PINENE Application February 8, 1949, Serial No. 75,274

In France February 12,. v19418 3 Claims.

The invention has for object to provide an apparatus permitting the thermal transformation under pressure of one product into another. It is particularly applicable for the continuous isomerisation of pinene into dipentene.

It has been known for some time that pinene can be isomerised into dipentene by heat in the liquid state under pressure.

This operation, carried out simply on a small scale, is complicated when it is desired to deal with considerable quantities because of the slowness of the heating and cooling periods and especially because of the difficulty of effectually controlling the temperature, the heat developed by the isomerisation tending to cause the temperature to rise spontaneously.

The apparatus embodying the present invention overcomes these difliculties. It consists of an autoclave having an annular cylindrical space for the downward circulation of the transformed liquid, a draw off device for the transformed liquid at the lower part of the said space, a coil pipe for "the upward circulation of liquid to be transformed and in course of transformation the coil being wound in the annular space aforesaid, a chamber at the upper part of the said annular cylindrical space into which the liquid in the coil discharges freely, and means for maintaining .the desired temperature and pressure in the said chamber.

In one example, the autoclave comprises two coaxial bells one within the other with a pipe coil disposed between them and open at its upper extremity, a heating device within the inner bell, a feed pipe for the product to be transformed connected with the lower end of the coil, a blow off pipe fitted with a cock and connected with the upper part of the outer bell for releasing therefrom any accumulated as or vapour, a draw-off orifice at the lower part of the outer bell for the transformed product, thermostatic means for maintaining the temperature at the desired value, and means for maintaining a desired pressure within the apparatus.

Apparatus in accordance with the invention enables continuous and entirely automatic working to be achieved and requires only a very small consumption of calorific energy.

The annexed drawing discloses a diagrammatic section illustrating, by way of example, one apparatus embodying the invention and as applied for the continuous isomerisation of pinene into dipentene.

Referring to the drawing, the body of the apparatus comprises two cylindrical steel bells I and 2 welded together coaxially' along the "rim I3. The outer bell I, as shown, is generally cylin drical, and has a closed upper end. The inner hell 2 or core is similar in shape but is shorter and is of smaller diameter than the bell I.

The initial cold essence (pinene a) supplied by a pump, not shown, enters at 3 at the base of the autoclave and flows through the coil pipe 4 wound helically in the annular space 5 between the two bells l and 2. This tube has an open upper end I2 communicating with the chamber Ii formed in the upper part of the bell I. The essence flowing upwards in the coil 4 is heated by contact of the coil with the hot isomerised essence (dipentene) which is in the space 5 and moves downwards in counter-flow'on the outside'of the coil 4. During this heating, the pine'ne is transformed into dipente'ne which es capes in cooled condition through a discharge valve l situated at the" bottomof the outer bell I.

The outer bell I is provided with a jacket containing heat insulating material 8. The apparatus is heated electrically by a heating coil'or resistance-9 near the top of the inner bell or coil 2. A thermostatic regulatormaintains the temperature in thechamber I2 at about'250. At I9 there is diagrammatically indicated'a thermometric device for actuating the thermostatic regulator.

The output of the apparatus is a function of its capacity. At the temperature conditions above specified, the essence should remain about two hours in the heated Zone. The useful capacity should therefore be twice the desired hourly output. It is possible to increase the output of a given apparatus by elevating the temperature to 260 or even more, but then the yield of the operation is lowered by reason of a more abundant formation of polymers.

It is advantageous to maintain in the autoclave a sufficiently strong over-pressure, 40 hectopizes for example, in order to keep in a liquid state the water that may be contained in the essence treated. As shown in the drawing, a container I5 filled with a fluid under pressure is connected to the autoclave through pipe I6 and gauge H. In all cases, the apparatus should comprise at the top a small blow-off cock II for the escape of gases which may accumulate there.

In order to give a better understanding of the functioning of the apparatus, two examples of practical utilization of the autoclave will be given.

EmampZeI An apparatus of three litres capacity conupper ends of said members, a helical pipe coll extending lengthwise of said space and wound around said inner member, said coil having an open upper end communicating with said chamher and a lower end through which liquid can be introduced for flow upwardly through said coil into said chamber and from the latter downthe lemon odour and is of the same density as the initial essence but its rotatory power is practically nil. It is composed of 80% dipentene practically free from non-transformed pinene and 20% of polymers non-entrainable by water vapour.

Example 2 The same apparatus is fed in the same conditions with essence of maritime pine having a rotatory power [a]589=29. The power required in continuous current is 125 watts. The rotatory power of the raw isomerised product is [al589=,10.5.". Theproportion of polymers is The differences as compared with Example 1 arise from the presence, in the essence of maritime pine, of nopinene which is not modified by the treatment.

Although the autoclave has been described as applied to the isomerisation of pinene, it is to be understood that the invention isnot limited to that application but can be employed for any reaction requiring a heating under pressure.

I claim:

1. An apparatus for thermal transformationof compounds, comprising a first elongated hollow cylindrical member having opposite closed ends, a hollow cylindrical core in said first member and formingtherewith a closed substantially annular space communicating at one end with an enlarged chamber between the ends of said hollow member and core, a pipe coil encircling the core and extending lengthwise thereof, said coil having an open end communicating with said chamber, means for introducing liquid into the opposite end of said coil remote from said chamber, meansfor discharging liquid at the end of said annular spaceremote from said chamber, and means within said hollow core to heat said chamber.

2. An apparatus for thermal transformation of compounds comprising an outer elongated hollow member having opposite upper and lower closed ends, a smaller elongated hollow member within andspaced from the sides and upper end of said outer member to form therewith a substantially annular elongated closed space communicating at its upper end with a large chamber between the wardly through said space, means for discharging liquid from the lower end of said space, and means within said inner member for heating liquid in the upper end of said coil and said chamber.

3. An apparatus for thermal transformation of compounds comprising an outer elongated hollow member having opposite upper and lower closed ends, a smaller elongated hollow member within and spaced from the sides and upper end of said outer member to form therewith a substantially annular elongated closed space communicating at its upper end with alarge chamber between the upper ends of said members, a helical pipe coil extending lengthwise of said space and wound around said inner member, said coil having an upper open end communicating with said chamber and a lower end through which liquid can be introduced for flow upwardly through said coil into said chamber and from the latter downwardly through said space, means to discharge liquid from the lower end of said space, means within said inner member for heating liquid in the upper end of said coil and said chamber, an escape and blow off valve at the upper end of said outer member to evacuate gases accumulated therein, thermostatic means responsive to the temperature of said chamber to control said heating means and maintain a desired temperature in said chamber, and means to maintain a predeter mined superatmospheric pressure within said chamber and said annular space.

PIERRE MARCEL BOURBON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date

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