Improvements in the Extraction of the Benzoles contained in the Heavy Oils, and in Classifying or Fractionating the several Hydro- carbons which accompany the Benzoles.
Year: 1898

page_text: Date of Application, 10th Sept., 1898-Accepted, 23rd Dec., 1898
Improvements in the Extraction of the Benzoles contained in the
Heavy Oils, and in Classifying or Fractionating the several Hydro-
carbons which accompany the Benzoles.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby
declare the nature of this invention (which has been communicated to me from
abroad by The Société Anonyme pour la Construction des Appareils Savalle, 93,
Avenue d'Orléans, Paris, in the Republic of France), and in what manner the
same is to be performed to be particularly described and ascertained in and by
the following statement:
According to this invention I volatilize the benzoles and the several hydro-
carbons accompanying the benzoles by the passage of a current of steam.
To work under the most economic and rapid conditions I have recourse to
continuous distillation.
According to the nature of the heavy oils I employ either cast iron bubbling
columns analogous to those used in the distillation of alcohol, or in order to
prevent the emulsion which might be produced with certain heavy oils I employ
plain distillatory columns provided with cast iron, stoneware or other material,
baffles, in which the hydrocarbons are carried over solely by intimate contact of
an ascending current of steam with a descending current of heavy oil which flows
in thin layers over the baffles.
This heavy oil is previously heated by the heat carried by the debenzinized
mixture of water and oil leaving the bottom of the column.
By the employment of a steam regulator, the temperature of the gaseous current
escaping from the top of the column is maintained between the limits of 97 to
98° C., which mixture is composed of steam, in large excess, and the vapours of
the hydrocarbon carried over.
Under these conditions, not only is benzene completely carried over, but also
the higher hydrocarbons up to and including naphthalene.
By merely condensing this mixture of vapours a very impure product would
be obtained.
In order to obtain almost all the naphthalene and the hydrocarbons more
condensible than toluene and consequently a relatively pure crude benzol which
will serve for certain industrial purposes, it is sufficient to employ an arrange-
ment, the action of which is based upon the existence of definite mixtures of
steam and hydrocarbons each boiling at a definite temperature and consequently
each condensing at a definite temperature at the ordinary pressure.
For example naphthalene which when pure boils at 2220 C. forms with steam
a mixture which distils at 98° C. and condenses at the same temperature; this
mixture is composed of 100 parts of water to 18 parts of naphthalene. As regards
benzene a mixture containing 100 parts of benzene and parts of water distils
and condenses at 67 to 68° C.
With toluene this mixture distils at 80° C.
It therefore the steam be slowly and progressively cooled maintaining a

page_text: temperature a little above 80° C. and if the condensed products be extracted
continuously as they are liquified almost the whole of the water, the naphthalene,
and the several higher hydrocarbons, will be eliminated, small quantities of
benzene and toluene only being lost, on account of their solubility in the con-
densed products. It will be further seen how to regain this small quantity.
The gaseous mixture which escapes condensation consists principally of benzene
toluene and a small quantity of steam, it is led to an ordinary refrigerator and
completely cooled.
It has been stated that the mixture of water, naphthalene and higher hydro-
carbons carries over small quantities of benzol.
There
This is recovered by leading the products collected in the hot condenser into a
small distillatory column traversed from bottom to top by the vapours from the
main column and communicating at the top with the hot condenser.
escapes then from the lower part of this small column a mixture of naphthalene,
higher hydrocarbons and hot water. The first being less dense than water at
this temperature floats. This being so the employment of a simple Florentine
receptacle with double effect enables the complete extraction of the several hydro-
carbons to be easily accomplished.
These are cooled and then pressed. There is obtained on the one hand crude
naphthalene in a solid state and on the other hand an oily matter containing all
the liquid hydrocarbons and the phenol retained by the hot condenser. then
proceed to rectify the crude products obtained in the following manner.
The two portions of liquids thus collected are submitted separately to the usual
processes of washing with sulphuric acid, water and soda, and then they are
rectified.
The vapours issuing from the rectifying column are led to a tubular condenser
shown in Figure 1 of the drawings which at first sight appears similar to the
condensers employed in the alcohol industry. It differs from them however in
that the energy of cooling should be made to vary, in unison with the appropriate
temperature of ebullition of the liquids which one is in course of collecting,
according to the phase of the operation and the latent heat of vaporization of this
liquid.
In the drawing A is the inlet of the vapours from the rectifying column. B is
the outlet for the non condensed vapours. C the pipe for the return of the con-
densed products to the rectifying column. D the inlet for the water. Fis a
removeable perforated vessel, distributing through its perforations, water into
the condenser tubes.
G is the outlet pipe for leading away the hot water from the condenser.
His the collector tube for the hot water.
I is a union which works when the whole surface of the condenser is utilized.
K K¹ K are cocks regulating the level of the water in the condenser.
In many apparatus this object is attained by varying the temperature of the
water in the condenser. This is very inconvenient if the temperature of the
liquid refrigerant ought to be above 100° C. I avoid this difficulty by allowing,
if I so desire, the temperature of the water to vary for so long as this is not
troublesome, but especially varying the contact surface of the water with the
vapours. To accomplish this the tepid water coming from the refrigerator
through the pipe D is regularly distributed in the upper portion of each tube.
The hot water thus displaced passes out of the lower portion of the condenser at
G and ascends by a vertical tube provided at different levels with discharge
cocks K K K³. According to the cock opened and even according to the amount
it is opened the level of water in the condenser may be maintained at the desired
height for effecting sufficient condensation and the required delivery to the test
vessel.
From the condenser the vapours pass through the pipe B to the tubular
refrigerator and from thence to the test vessel. Then I proceed to the rectifi-
cation. That of the light oils takes place as follows;
-

page_text: When, on finding either by density or boiling point of the products which pass
to the test vessel, that all the toluene has passed over, the operation is arrested
and the distilling vessel emptied; the residuum being transferred to the vat con-
taining the higher hydro carbons to be rectified. Of course, by means of cocks
upon the test vessel, there has been separated first a small quantity of benzene
contaminated with sulphide of carbon then pure benzene then a mixture of
benzene and toluene which is caused to be returned in a subsequent operation,
and lastly pure toluene.
The higher hydrocarbons are rectified as follows:-
They are rectified separately. The operation first furnishes small quantities
of a mixture of benzene and toluene which is added to the light oils to be rectified.
Soon the point of ebullition rises rapidly and the amount passing into the test
vessel diminishes. I then change the pressure of the steam serving for heating
and lessen the quantity of water passing to the condenser as well as the moistened
surface so as to collect by fractionated portions the hydrocarbons uncondensed in
the column until their point of ebullition becomes nearly 160° C. These latter
products are placed on one side for special use. The heating is then stopped, the
boiler emptied and its contents placed to cool, and to be pressed if necessary.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is:
-
The process of distilling heavy oils above described which consist:-
1. In causing them to fall in layers upon an ascending current of steam and in
separating the light oils and the higher hydrocarbons by a slow and fractionated
condensation at definite temperatures, from the mixtures of water and volatile
hydrocarbons by the steam during the distillation.
2. In rectifying the products so obtained, so as to extract the benzoles and
classify the several hydrocarbons accompanying them.
Total this Oth
1900