Improvements in or relating to Apparatus for Evaporating or Concentrating Liquids.
Year: 1897

page_text: Date of Application, 11th Oct., 1897
Complete Specification Left, 11th Aug., 1393-Accepted, 24th Sept., 1898
DEPUTATION.
Improvements in or relating to Apparatus for Evaporating or
Concentrating Liquids.
We, PERCY RUSKIN ALLEN, Mechanical Engineer, of 113, Greenway Road,
Runcorn, Cheshire, and JoHN BROOKES CHADWICK, Salt Works Manager, of 1,
Norman Road, Runcorn aforesaid, do hereby declare the nature of this invention
to be as follows;-
During the evaporation or concentration of liquids containing substances in
solution a scum or crust is liable to form on the surface of the liquid that seriously
interferes with the evaporating or concentrating operation. This is particularly
the case in the manufacture of certain grades of salt from brine where the par-
ticles of salt produced at the surface of the brine during evaporation tend to ad-
here together and rapidly form over the surface of the liquid an impervious scum
or crust that would prevent or retard the evaporation of the brine and thus arrest-
ing. for the time being the production of salt. Heretofore it has been usual to
break up this scum or crust by agitating it with a rake or paddle worked by
hand, or by causing the brine entering the evaporating pan to impinge upon it in
the form of jets, but these expedients are only partially effective.
Now this invention has for object to remove in an automatic and continuous
manner scum or crust produced at the surface of a liquid undergoing evaporation
or concentration. For this purpose there is used in conjunction with the evapo-
rating pan or vessel mechanical skimming apparatus so constructed arranged and
operating as to pass over the surface of the liquid and remove therefrom the
scum or crust as soon as it is produced.
Skimming apparatus for this purpose can be constructed in various forms.
According to one arrangement, as applied to an ordinary rectangular evaporat-
ing pan, the skimming apparatus comprises chains or their equivalent mounted
to travel over a suitable guide pulley and transversely arranged skimming devices
that are carried by the chains or equivalent and caused thereby to travel continu-
ously in one direction first over and in contact with the surface of the liquid, and
then back clear of the evaporating pan and liquid. The skimming devices are
preferably so made that they will float on the surface of the liquid while passing
over it. They may however if desired, be partially or wholly supported by means
of rollers mounted to run on rails or guides, and they may be suitably stiffened
to resist bending. They may consist of battens or boards pivoted or jointed to the
endless chains of which there may be a pair arranged one at each side of and
above the evaporating pan.
In another arrangement the skimming devices are made of flexible tubing suffi-
ciently buoyant to float on the surface either naturally or by means of artificial
inflation. It has been found that by using tubing of india rubber, or of a like
substance having a smooth surface, the scum or crust does not adhere to it, and
as. it is not necessary to stay or stiffen it, as being elastic, it yields to the surface
friction of the liquid, it can be made very light.

page_text: In another arrangement suitable for use with circular evaporating pans, one or
more floating skimmers is or are conveniently attached to one or more arms or
to a frame, carried by a vertical shaft and mounted to revolve about a vertical
axis placed centrally with the pan.
In the case of salt pans where the salt is drawn or removed by being raked to
one side or end of the pan and lifted out, it is convenient to make the framework
carrying the chains or equivalent with skimming devices, independent of the pan
itselt, so that it can be moved out of the way while the salt is being withdrawn.
When endless chains are used for carrying and operating the skimming devices
over a rectangular pan, the guide pulleys over which the lower horizontal portions
of the chains travel may be carried by pendulum rods that can, when desired, be
swung towards one or other end of the pan and so raise the said lower portions
of the chains and the skimming devices carried thereby well above the surface of
the liquid so as to admit of the convenient removal of the salt from the pan.
The skimming apparatus may be driven by any suitable motor.
In cases where
the liquid to be treated is supplied under pressure, as is generally the case with
brine used for salt making, it is preferred to use the incoming liquid to actuate
a suitable motor for driving the skimming apparatus.
Improvements in or relating to Apparatus for Evaporating or
Concentrating Liquids.
We, PERCY RUSKIN ALLEN, Mechanical Engineer, of 113, Greenway Road,
Runcorn, Cheshire, and JOHN BROOKES CHADWICK, Salt Works Manager, of 1,
Norman Road, Runcorn aforesaid, 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:-
-
During the evaporation or concentration of liquids containing substances in
solution, a scum or crust is liable to form on the surface of the liquid that seriously
interferes with the evaporating or concentrating operation. This is particularly
the case in the manufacture of certain grades of salt from brine, where the par-
ticles of salt produced at the surface of the brine during evaporation, tend to ad-
here together and rapidly form over the surface of the liquid an impervious scum
or crust that would prevent or retard the evaporation of the brine and thus arrest,
for the time being, the production of salt. Heretofore it has been usual to
break up
this scum or crust by agitating it with a rake or paddle worked by
hand, or by causing the brine entering the evaporating pan to impinge upon it in
the form of jets, but these expedients are only partially effective.
Now this invention has for object to remove in an automatic and continuous
manner, scum or crust produced at the surface of a liquid undergoing evaporation
or concentration. For this purpose there is used in conjunction with the evapo-
rating pan or vessel mechanical skimming apparatus so constructed arranged and
operating as to pass over the surface of the liquid and remove therefrom the
scum or crust as soon as it is produced.
Skimming apparatus for this purpose can be constructed in various forms.
Figs. 1, 2 and 3 of the accompanying illustrative drawings show respectively in

page_text: cross section, longitudinal section and plan, an ordinary rectangular evaporating
pan provided with one arrangement of skimming apparatus according to this inven-
tion.
In this arrangement the skimming apparatus comprises two endless chains 1, 1ª,
or their equivalent, mounted to travel over and under suitable guide pulleys 2,2"
and transversely arranged skimming devices 3 that are carried by the chains and
caused thereby to travel continuously in one direction first over and in contact
with the surface of the liquid 4 in the evaporating pan 5, and then back clear
of the evaporating pan and liquid. The skimming devices are preferably so made
that they will float on the surface of the liquid while passing over it.
In the arrangement now being described, the skimming devices 3 are made of
flexible tubing sufficiently buoyant to float on the surface of the liquid, either
naturally or by inflating it with air under. pressure. It has been found that by
using tubing of india rubber, or of a like substance having a smooth surface, the
scum or crust does not adhere to it, and as it is not necessary to stay or stiffen it,
as being elastic it will yield to the surface friction. of the liquid, it can be made
very light.
Fig. 4 shows, partly in central section and partly in side elevation, and Fig. 5
in plan, part of an endless chain such as may be used for operating the skimming
devices 3 which are attached to inward extensions of the chains.
One of such extensions is shown at 1b. The said chains, which
are arranged one at each side of. and above the evaporating pan 5, may be
driven in any convenient manner, as for example by endless chains 6 that pass
over chain wheels attached to two of the pulleys 2, 2" and are driven from
other chain wheels on a common shaft 7 driven by belting: 8 or otherwise. In
cases where the liquid to be treated is supplied under pressure, as is generally the
case with brine used for salt making, it is preferred to use the incoming liquid to
actuate a suitable motor for driving the skimming apparatus.
Fig. 6 is a plan showing an arrangement of this kind in which the brine supplied
under pressure through a pipe 9 is passed on its way to the evaporating pans 5
through a turbine 10 which, through suitable means such as worm gearing 11,
shaft 12 and bevel gearing 13, is used to drive the shaft 7 from which the skim-
ming apparatus of the several evaporating, pans are operated.
Figs. 7 and 8 show respectively in end view and part longitudinal section, a
modified arrangement in which the chains 1, 1ª instead of being wholly supported
by pulleys 2 over and under which they run, are provided with rollers 2b by
which they are partially supported by fixed rails 14, the said chains. being con-
nected across at intervals by means of light truss arrangements each of which
may conveniently be made of piping 15, struts 15", and wire tension members 15b.
Figs. 9 and 10 show respectively in side elevation and plan, part of one of such
chains with a roller 2b to a larger scale than Figs. 7 and 8. The skimming
devices are in this arrangement. shown as of flexible tubing, as in Figs. 1 to 4
inclusive, but they might obviously be made of battens or boards pivoted or
jointed to the endless chains and suitably stiffened to resist bending.
Figs. 11 and 12 show respectively in side elevation and plan, a circular evapo-
rating pan with skimming apparatus according to this invention. In this case
there are two floating skimmers 3, though there may be only one or more than
two, each of them being attached to an arm 16 carried by a vertical shaft 17
that is mounted in a frame 18 so that it can be rotated about a vertical axis coin-
ciding with the centre of the pan, the shaft 17 being driven from a counter-
shaft 19 through a belt 20 led over a guide pulley 21.
In the case of salt pans where the salt is drawn or removed by being raked to
one side or end of the pan and lifted out, it is convenient to make the framework
carrying the chains or equivalent with skimming devices, independent of the pan
itself, so that it can be moved out of the way while the salt is being withdrawn.
In the arrangement shown in Figs. 11 and 12, the frame 18 is for this purpose
mounted to turn about a vertical axis at 18% so that it can be swung to one side

page_text: clear of the pan, as shown in Fig. 13, when necessary. When endless chains are
used for carrying and operating the skimming devices over a rectangular pan, as
in Fig. 1 to 8 inclusive, the guide pulleys 2, 2ª over which the lower horizontal
portions of the chains 1, 1ª travel, may be carried by pendulum rods, as indicated
at 2 in Fig. 2, that can, when desired, be swung towards one or other end of
the pan and so raise the said lower portions of the chains and the skimming
devices carried thereby, well above the surface of the liquid so as to admit of the
convenient removal of the salt from the pan.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. The combination with an evaporating pan or vessel, of mechanical skimming
apparatus arranged and operating substantially as herein before described for the
purpose specified.
2. The combination with a rectangular evaporating pan, of endless chains or
their equivalent arranged one at each side of and above the pan, means for sup-
porting, guiding and driving the said chains or equivalent, and skimming devices
carried by the chains or equivalent and caused thereby to travel first over and in
contact with the surface of the liquid and then back clear of the pan and liquid,
substantially as described.
3. The combination with a circular evaporating pan, of skimming apparatus
comprising one or more floating skimmers attached to one or more arms carried by
a vertical shaft mounted to revolve about a vertical axis above the centre of the
pan, substantially as described.
4. In skimming apparatus for use with an evaporating pan or vessel as herein
described, a skimming device made of flexible tubing sufficiently buoyant to float
on the surface of the liquid being evaporated, substantially as herein described.
5. Skimming apparatus for use with evaporating pans, constructed, arranged
and operating substantially as herein before described, with reference respectively
to and shown in Figs. 1 to 6 inclusive; in Figs. 7 to 10 inclusive; and Figs. 11
to 13 inclusive of the drawings annexed.
Dated this 11th day of August 1898.