Improvements in and Apparatus for Evaporating Solutions with Multiple Effect.
Year: 1896

page_text: Date of Application, 6th July. 1895.
Complete Specification Left, 6th Apr.: 1897-Accented, 15th May, 1997
PROVISIONAL SPECIFICATION.
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for Evaporating Solutions with
Multiple Effect.
We, THOMAS GLOVER, Works Manager and JOHN BROCK, Chairman, both
of The United Alkali Company Limited of G" Exchange Buildings Liverpool in
the County of Lancaster, do hereby declare the nature of this invention to be
as follows:-
In an ordinary multiple effect, evaporating apparatus advantage is taken of the
fact, that the boiling point of a solution is lowered by diminishing the pressure.
Hitherto a vacuum has been made use of in order to relieve the boiling liquid from
the pressure of the atmosphere.
The object of this invention is to obtain the benefit of multiple effect without
the use of a vacuum.
We will describe apparatus as we employ it for either the concentration of, or the
deposition of solid matter from solutions. The apparatus which may be consider-
ably modified in details without departing from the invention, consists of three
parts which are for what we will call, first, second, and third effects.
The part for the first effect may consist of an ordinary circular flat bottomed
wrought or cast iron pan, in which the solution is boiled, the pan being heated either
externally by means of a fire, or internally by means of a steam coil. This pan is
provided with a wrought iron cover so that the steam generated therein may be
collected for use in the second effect. This cover is made of less diameter than
the pan, in order to permit any solid matter, separating from the solution, being
removed by any well known means from the space between the cover and the
edge of the pan. The cover rests upon stays fixed below the level of the boiling
solution, and is provided with the necessary water-sealed openings to permit a
revolving shaft to pass down through the centre, to make the steam connection
with the second effect, and to provide for samples to be taken from the pan. In
order to remove the deposit of the solid matter from the bottom of the pan,
the revolving shaft passing through the centre of the cover is provided with arms
or the equivalents set so that the deposited matter is conveyed into the annular
space between the edge of the cover and the side of the pan from whence it is
removed.
The part for the second effect consists of a vertical cylindrical vessel divided by
horizontal partition plates, into three compartments. The lower compartment
communicates with the upper compartment by means of a large number of tubes.
The lowest compartment, the tubes and part of the upper chamber are filled with the
solution to be evaporated or concentrated. The middle compartment receives
the steam from the aforesaid pan, and heats the liquid within the pipes to a high
temperature, but not to the point of ebullition. For the purpose of obtaining the
effects of ebullition and circulation within the heating tubes, we force into the
lower compartment, by means of a pump, into and through the solution a current of
air, which may or may not be heated beforehand. In the evaporation of a solution
not depositing solid matter, it would be advantageous to force the air into a.
receptacle attached to the bottom of the lower compartment, the upper surface

page_text: plate of which is perforated, so that air passes in thin streams up the heating
tubes. However, when solid matter is deposited the perforated plate may be
dispensed with, and the air be forced into the lower compartment and distributed
by means of small tubes having their open ends turned downwards. The air
passing through the solution contained within the heating tubes for the second
effect, is in contact with the heating surface, and not only increases the heat
transmitting power of the tubes, but by the velocity of circulation prevents the
deposition of any solid matter thereon. In order to ensure that the air forced
through the solution may become saturated with vapour or nearly so before
leaving the surface of the solution, the upper compartment is provided with
several layers of superposed wire netting or the like so that the bubbles of moist.
air are subdivided. The saturation of the air depends upon the temperature of the
solution and the vapour tension of the liquid at that temperature. It is not advan-
tageous to use the saturated air for a third effect, if the solutions through which
the air passes have a vapour tension of less than 18 inches of mercury at the
temperature of the second effect.
The part for the third effect consists of a series of vessels provided each with a
coil of pipes through which the mixture of air and steam coming from the tubular
arrangement aforesaid is passed. The steam condenses and its latent heat is
utilized for either heating the liquid to be evaporated, or for concentrating a
portion thereof by surface evaporation.
Each of the parts for the several effects, should be provided with inlets and
outlets for charging and discharging the solution to be evaporated or concentrated,
and the apparatus should be covered externally with non-conducting material.
It is advantageous to evaporate in the second or air effect portion, the liquid
with the highest vapour tension so that the air may convey away the maximum
charge of steam.
In the evaporation or concentration of a saline solution like brine, the vapour
tension of which is constant, when salt commences to separate out, the circulation
of the liquid through the several parts of the apparatus is in the contrary direction
to that of the steam, that is, the liquor from the third effect portion feeds the
second effect portion, and the liquor from the second effect portion feeds the first
effect portion, but in the evaporation or concentration of a solution like caustic soda,
the vapour tension of which diminishes as concentration proceeds, the liquid would
circulate from the second into the third, and thence into the first effect portions.
Dated this 6th day of July 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for Evaporating Solutions with
Multiple Effect.
We, THOMAS GLOVER Works Manager and JOHN BROCK Chairman both of
The United Alkali Company Limited of G 11. Exchange Buildings, Liverpool in
the County of Lancaster, do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and
ascertained in and by the following statement:-
In an ordinary multiple effect evaporating apparatus advantage is taken of the
fact that the boiling point of a solution is lowered by diminishing the pressure.
Hitherto a vacuum has been made use of in order to relieve the boiling liquid from
the pressure of the atmosphere.

page_text: The object of this invention is to obtain the berefit of multiple effect without the
use of a vacuum.
We will describe apparatus as we employ it for either the concentration of
olutions, or the deposition of solid matter from solutions. The apparatus, which
may be considerably modified in details without departing from the invention,
consists mainly of three parts which are, for what we will call, first, second, and
third effects.
In order that the invention and the manner in which it can be performed may be
clearly understood we will describe it with reference to the annexed drawings
representing an apparatus for the evaporation of brine from which its other
applications will also be understood.
Figure 1 is an elevation, and Figure 2 a plan of the apparatus, and
Figure 3 is a sectional elevation and Figure 4 a plan of the parts of the apparatus
for the second or air effect.
The part for the first effect may consist of an ordinary circular flat bottomed pan.
which may be of wrought, or cast iron in which the solution is hoiled, the pan being
heated in any suitable way such as externally by means of a fire, or internally by
means of a steam coil. This pan is provided with a cover, say of wrought iron, so
that the steam generated therein can be collected for use in the part for the second
effect. This cover is made of less diameter than the pan, in order to permit any
solid matter, separating from the solution, being removed by any well known means
from the space between the cover and the edge of the pan. The cover rests upon
stays fixed below the level of the boiling solution and is provided with the
necessary water-sealed openings to permit a revolving shaft to pass down through
the centre, to make the steam connection with the second effect, and to provide for
samples to be taken from the pan. In order to remove the deposit of the solid
matter from the bottom of the pan the revolving shaft passing through the centre
of the cover is provided with arms or the equivalents set so that the deposited
matter is conveyed into the annular space between the edge of the cover and the
side of the pan from whence it is removed.
We prefer however to construct the first effect or pan as shewn in the drawing.
A is the flat bottomed pan provided with the agitator B, which agitates the solution
and by centrifugal or positive action propels the salts deposited into the pocket, or
elevator box C, which communicates with the pan A by an aperture in the
circumference or bottom of the said pan. From this pocket or elevator box C the
salts can be removed by elevaturs or otherwise. The steam produced in this
pan A passes off through the pipe D into the part of the apparatus for the second
effect.
The part for the second effect consists of a vertical vessel divided by horizontal
partition plates, into three compartments. The lower compartment communicates
with the upper compartment by means of a large number of tubes passing through
the mid compartment. The lowest compartment, the tubes, and part of the upper
compartment are filled with the solution to be evaporated or concentrated. The
middle compartment receives the steam from the aforesaid pan A and this beats
the liquid within the pipes to a high temperature, but not to the point of ebullition.
For the purpose of obtaining the effects of ebullition and circulation within the
beating tubes, we force, into the lower compartment, by means of a pump, and into
and through the solution therein, a current of air which may, or may not, be heated
beforehand. In the evaporation of a solution not depositing solid matter, it would
be advantageous to force the air into a receptacle attached to the bottom of the
lower compartment, the upper surface plate of which is perforated so that air
passes in thin streams up the heating tubes. When solid matter is deposited the
perforated plate may be dispensed with and the air be forced into the lower
compartment and distributed by means of small tubes having their open ends turned
downwards. The air, passing through the solution contained within the heating
tubes for the second effect, is in contact with the heating surface, and not only
increases the beat transmitting power of the tubes but, by the velocity of circulation,

page_text: prevents the deposition of any solid matter thereon. In order to ensure that the
air forced through the solution may become saturated with vapour, or nearly so,
before leaving the surface of the solution, the upper compartment may be provided
with several layers of superposed wire netting, or the like, so that the bubbles of
moist air are sub-divided.
We find it advantageous to construct the second effect as shewn in the drawings
and more especially on a larger scale in Figures 3 and 4. E' E2 E3 are the three
compartments for the second effect. The steam entering the compartment E
from the pan A by the inlet pipe D surrounds the tubes e which pass through tube
plates above and below and connect the lower compartment E' with the upper
compartment E3. The steam and condensed water leave the middle compartment E
by the outlet pipe F, and enter the water seal G (Figures 1 and 2) where the
steam passes through a column of water the height of which may be regulated by
the swivel pipe g, through which the condensed water flows out, whilst any
uncondensed steam passes through the pipe F to the part for the third effect. The
compartment E3 is elongated and provided with an agitator E. The brine to be
evaporated fills the lowest compartment E', and all the pipes in the compartment E
and enters the compartment E' to within say one-third of its height. The liquid is
heated in the compartiment E' but not to ebullition. The effects of ebullition are
obtained by forcing a current of air through the perforated air pipes H, entering
the compartment E. The air ascends through the pipes e e and through the liquor
in the upper compartment E3 and augmented by a second air supply entering at h
passes over the surface of the liquid and leaves the compartment E3 at I. The
agitator E projects liquid into the air and renews the surface of the liquid and
thus ensures that the air leaves the compartment approximately saturated with
vapour.
Salts which may be deposited in the compartment E3 fall partly through the
pipes e e, and partly through the pipe K into the pocket L from which they are
removed by the elevators 7 working in the casing K. The pipes ee are kept clear
of deposit by the agitation caused by the ascending air, the pipe K is kept clear of
adhering deposit by the scrapers k rotated or reciprocated by any suitable means.
The pipe K also serves to maintain a rapid circulation of the liquid, the cooler
liquid descending from the compartment E3 through the pipe K and ascending
again through the pipes e e.
The saturation of the air depends upon the temperature of the solution and the
vapour tension of the liquid at that temperature. It is not advantageous to use
the saturated air for a third effect if the solutions through which, or over which,
the air passes have a vapour tension of less than 18 inches of mercury at the
temperature of the second effect.
The part for the third effect consists of a vessel or a series of vessels provided
each with a coil of pipes through which the mixture of air and steam coming from
the compartment E3 aforesaid is passed. The steam condenses and its latent heat
is utilised for either heating the liquid. to be evaporated, or for concentrating a
portion thereof by surface evaporation.
As shewn in Figures 1 and 2, the part of the apparatus for the third effect
consists of a vessel M filled with brine and traversed by pipes m m, through which
the inixture of steam and air from the compartment passes by the pipe I and
wherein it is condensed. The brine in this vessel is heated, and concentrated, then
flows through pipe N into the compartment E3 where it is further concentrated and
evaporated, and leaves the compartment E3 by the pipe N and enters the pan A
where it is completely evaporated.
Each of the parts for the several effects should be provided with inlets and
outlets for charging and discharging the solution to be evaporated, or concentrated;
and the apparatus should be covered externally with non-conducting material.
It is advantageous to evaporate the liquid with the highest vapour tension in the
second, or air, effect portion, so that the air may convey away the maximum charge
of steam.

page_text: In the evaporation, or concentration, of a saline solution like brine (the vapour
tension of which is constant as soon as salt commences to separate out) the
circulation of the liquid through the several parts of the apparatus is in the
contrary direction to that of the steam, that is, the liquor from the third effect
portion feeds the second effect portion and the liquor from the second effect portion
feeds the first effect portion, but in the evaporation, or concentration, of a solution
like caustic soda, (the vapour tension of which diminishes as concentration proceeds)
the liquid would circulate from the second, into the third, and thence into the first,
effect portions.
Having now described the nature of our invention and the manner in which the
same is or may be used, or carried into effect, we would have it understood that we
do not confine or restrict ourselves to the precise details we have described or
referred to, as variations may be made therefrom without deviating from the
principle of our said invention, but what we consider novel and original and
therefore claim as the invention is :-.
1. In evaporating solutions with multiple effect, the improvement consisting in
forcing a. current of air through or over, or through and over, the solution whilst
being heated so as to obtain the effects of ebullition below the ordinary boiling
point of the solution constituting thus a second effect substantially as hereinbefore
described.
2. In apparatus for evaporating solutions with multiple effect, the improvement
consisting in the use of the mixture of air and steam obtained in the part for the
second effect, for heating and concentrating the solutions in a part for the third
effect substantially as hereinbefore described.
3. The combination of parts constituting an apparatus for multiple effect
evaporation as hereinbefore described and illustrated in the accompanying
drawings.
Dated this 6th day of April 1897.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.