Apparatus to concentrate solutions and to recover solvents

Apparatus to concentrate solutions and to recover solvents, comprising a column (1) equipped with a heating body (2), a distributor (3) of the liquid to be introduced and treated in the column (1); means (4) effecting simultaneously the flow of the concentrated liquid and the introduction of a flow of gas into the column (1) and means (20) to insure the maintenance of the internal temperature of the column (1).

The object of the present invention is an apparatus and process to 
concentrate solutions and to recover solvents. 
More particularly, it is the object of the invention to provide an 
apparatus and process making it possible to prevent the accumulation of 
large quantities of solutions by concentrating the solutions at the rate 
at which they are introduced into the apparatus and pass through it, and 
to reuse the solvent. 
The apparatus of the present invention may be advantageously used during 
chromatography operations, particularly when these operations are on a 
semi-industrial or industrial scale. 
An essential advantage of the apparatus of the invention comprises the fact 
that the volume of the liquid may be reduced in order to obtain the degree 
of concentration desired (between all or nothing), in a continuous manner, 
by means of regulating the liquid stream, in particular, as a function of 
the flow rate of the chromatographic column. The different products 
contained in the solutions issuing from the chromatographic process remain 
chronologically spaced apart so that it is not necessary to have recourse 
to the intermediate storage of the solution and the collection of the 
concentrates containing the different products is effected without the 
risk of new intermixing and contamination. This advantage is fundamental 
in preparative chromatography and in all other physical or chemical 
processes involving the flow of a fluid, the composition of which varies 
with time. 
A further remarkable advantage consists of the fact that the evaporated 
solvent is recovered and may be recycled continuously to the beginning of 
the process, thereby appreciably reducing the volumes involved. 
Finally, the concentration treatment, effected under an inert gas, retains 
the solution for only a few seconds at the evaporation temperature which 
is a highly favorable condition in the treatment of thermolabile molecules 
.

The apparatus which is the object of the present invention comprises a 
column (1) equipped with an inlet for the liquid to be treated, a gas 
inlet, an outlet for the treated liquid and an outlet for the solvent 
vapors to be recovered. The column (1) is further equipped with a heating 
body (2), placed axially and heated by the circulation of a temperature 
control liquid inside the body, a distributor (3) of the liquid to be 
treated, means (4) to effect simultaneously the flow of the concentrated 
liquid dropping from the heating body and the introduction of a flow of 
gas in the column (1) and means (2) to insure the maintenance of the 
inside temperature of the column (1). The apparatus is further 
characterized by the following features: 
The heating body (2) has the configuration of a finger of a glove and the 
active part of its surface which receives the liquid to be treated 
contains a plurality of flow guides (5) so as to present an optimum 
contact surface to the liquid to be treated and assures regular 
distribution of the liquid over its surface; 
the distributor (3) of the liquid to be treated is in the form of an 
annulus, the inner diameter of which permits the passage of the inactive 
part (2') of the heating body (2), which is not equipped with flow guides 
(5); 
the means (4) which simultaneously insures the flow of the liquid dropping 
from the heating body (2) and the introduction into the column (1) of a 
flow of gas is a cylindrical body (14) in the form of a sink (15). 
The apparatus that is the object of the invention is also characterized by 
the following features: 
A portion of the surface of the internal circumference of the distributor 
(3) is hollow, this center cavity (7) communicates through the channel (8) 
with the inlet conduit (9) for the liquid to be treated and through the 
channel (10) with a rinsing channel (11) and places the liquid to be 
treated in contact with the flow guides (5) and the heating body (2); 
the distributor (3) is equipped either with axial channels (12) arranged in 
a circular manner, or with axial recesses (13) located on the external 
circumference of the distributor (3), or both; 
the cylindrical body (14) hollowed in the form of a sink (15) is placed 
axially in the column (1) and the cavity in the form of a sink (15) is 
capable of receiving the lower end of the heating body (2); 
the sink (15) extends into a conduit, the end (16) whereof passes through 
the part (17) closing the lower end of the column (1), with the inlet (18) 
for the flow of gas also being provided in said part (17). 
The apparatus of the invention will become more apparent from the following 
embodiments: 
The column (1) may be made in two or more parts in order to facilitate the 
assembly of the apparatus of the invention. 
The materials used for the construction of the elements of the apparatus 
are those usually employed in distillation columns, such as glass, 
stainless steel, plastic materials, such as teflon, polyethylene, 
polypropylene or the like. 
The flow guides (5) of the heating body (2) may be integral with the body 
or they may be applied to the heating body (2); they may consist of 
stainless steel, glass or a plastic material. Other types of relief 
favoring the flow and the distillation of the liquid to be treated may 
also be employed on the heating body (2). 
The circulation (6) of the temperature control liquid may consist of a 
descending helix to lead the said liquid and of an evacuating conduit (21) 
to remove the cooled liquid from the column (1). 
The temperature control liquid may consist of for example, water, glycol or 
an oil. 
The means insuring the heating of the heating body (2) may also consist of 
an electric device or a heating circulating gas, such as water vapor or an 
inert gas. 
The cylindrical body (4) which constitutes the means to insure the flow of 
the concentrated liquid from the column (1) may be held in place by 
retaining lugs placed in the column (1) and it may be made of glass, a 
plastic material or stainless steel. 
The column (1) may have, depending on the dimension of the installations to 
which it is attached, a length of 2 to 7 meters and a diameter from 80 mm 
to 350 mm, for flow rates of 3 liters/hour to 150 liters/hour. Smaller or 
larger dimensions are also applicable. 
The heating flue (20) of the column (1) may consist of a jacket equipped 
with a heating device such as an electric circuit, a temperature control 
liquid or a gas. This heating device may further be connected with the 
heating means of the heating body (2) and operate in series. 
The flow guides (5) of the heating body (2) are placed at a more or less 
acute angle with respect to the axis of said heating body (2). This angle 
is preferably very small to reduce the flow rate of the solution along the 
guides and to thereby facilitate the evaporation of the solvent. By 
choosing a small angle of inclination of the guides (5), the number of 
guides (5) over a given length of the heating body will be larger and the 
evaporation of the solvent is further improved. 
The channel (8) of the distributor and the channel (9) of the inlet conduit 
of the liquid to be treated may be joined by means of a connection 
provided for this purpose. In a variant, they may be replaced by a single 
channel passing through the column (1) and the distributor (3). The same 
is also true for the channel (10) of the distributor (3) which 
communicates with the rinsing channel (11). 
The length of the channel (8) and of the channel (10) of the distributor 
(3) is advantageously chosen so that the liquid to be treated and the 
rinsing liquid are conducted into the proximity of the heating body (2). 
In considering the drawings it may be seen that: 
(1) represents the column, 
(2) the heating body, 
(2') the inactive part of the heating body (2) which is not equipped with 
flow guides, 
(3) the distributor of the liquid to be treated, 
(4) the means for insuring simultaneously the flow of the concentrated 
liquid dropping from the heating body (2) and the introduction of a flow 
of gas into the column (1), 
(5) flow guides on the heating body in its active part intended to receive 
the liquid to be treated, 
(6) the means in the form of the circulation of a temperature control 
liquid effecting the heating of the heater body, 
(7) the center cavity of the distributor (3), 
(8) the channel of the distributor (3) communicating with the inlet conduit 
(9) of the liquid to be treated, 
(10) the channel of the distributor (3) communicating with the rinsing 
channel (11), 
(12) The axial channels of the distributor (3), 
(13) the axial recesses of the distributor (3) 
(14) the cylindrical body in the form of which the means (4) are embodied; 
(15) the sink in the form of which the cylindrical body (14) is hollowed 
out, 
(16) the end of the conduit by which the sink is extended, 
(17) the part closing off the lower end of the column (1), 
(18) the inlet in the column (1) for the gas, 
(19) the condenser to condense the solvent evaporated and entrained by the 
gaseous flow, 
(20) the heating flue, and 
(21) the conduit to remove the cooled temperature controlled liquid. 
The apparatus according to the present invention may be used in the manner 
described as follows: 
A solution to be concentrated and the solvent recovered are introduced by 
the channnels (9) and (8) into the center cavity (7) of the distributor 
(3). The solution may be from a chromatographic separation, for example. 
Once introduced in the center void (7), preferably in the proximity of the 
heating body, the solution enters into contact with the active part of the 
heating body (2), i.e. the part equipped with the flow guides (5). 
Once this contact is established, the liquid commences to descend along the 
heating body (2) by following the flow guides (5) of the latter (2). 
During its descent, the solution is heated and under the combined action 
of the heating and the gas rising in the column (1), the solvent 
evaporates and is entrained by the gaseous flow introduced in the column 
(1) through the inlet (18), toward the top of the column (1). 
When the vapors have passed through the distributor (3) by way of the axial 
recesses (13) and/or the axial channels (12), they travel to the condenser 
(19) where they are condensed and the outlet (19), where the solvent is 
recovered. 
The concentrated solution is collected in the sink (15) and conducted 
through the conduit (16) to further processing. 
An inert gas, such as nitrogen, is used preferentially as the gas. 
The flow rate and the temperature of the gaseous flow play an important 
role in the evaporation of the solvent. 
They depend: 
on the nature of the solvent to be evaporated, 
the flow rate of the liquid injected in the column, 
the temperature to which the solution may be exposed, in view of the very 
short time during which the solution is exposed to this temperature. 
As a general rule, the temperature will be controlled at a point slightly 
lower then the boiling point of the solvent to be evaporated and the 
gaseous flow is controlled so as to obtain the concentration ratio 
desired. 
The heating flue (20) makes it possible to maintain the temperature 
prevailing within column (1) and thus preventing the condensation of 
vapors of the solvent on the walls and consequently the accumulation of 
the condensate formed in the lower end of the column (1) and its 
penetration into the inlet (18) reserved for the flow of gas. 
The apparatus of the present invention is not limited to the specific 
embodiments described, but all variants are included.