An Improved Process of and Apparatus for Evaporating or Concentrating Saccharine and other, Liquids.
Year: 1894

page_text: Date of Application, 25th Aug.. 1894
Complete Specification Left, 23rd May, 1895-Accepted, 29th June, 1895
PROVISIONAL SPECIFICATION.
An Improved Process of and Apparatus for Evaporating or
Concentrating Saccharine and other, Liquids.
I, ALEXANDER CRERAR of 9 Fenchurch Avenue in the City of London, West
India Merchant, do hereby declare the nature of this invention (a communication
to me from Walter Rodwell Boon of Wingfield Manor, St. Kitts, West Indies,
and E. A. Hancock of Basseterre, St. Kitts, aforesaid) to be as follows :—
This invention relates to an improvement in the process of evaporating liquids
generally, but has more especially for its object to enable saccharine liquids to be
concentrated at a lower temperature and more speedily than is now possible with a
vacuum pan or otherwise, and thereby to reduce to a minimum the inversion of
sucrose which it is of such importance to avoid.
The process consists essentially in drawing air or other gas, preferably heated,
through the liquid, so as to absorb and carry off the vapor as it is generated.
The invention also consists in apparatus whereby the process may be carried
into effect, constructed substantially as follows:-
The apparatus consists of a closed pan or vessel of iron or copper, &c. provided
with a double bottom and communicating at its lower part with an air inlet, and
at its upper part with an outlet connected with any suitable exhausting apparatus.
The inner bottom, which is preferably of conical form to facilitate the discharge
of the contents of the pan, is perforated with a number of small holes by which
communication between the interior of the pan and a chamber enclosed between
the outer and inner bottoms, is established. The outer bottom is also preferably
coniform, a chamber, as already mentioned, being left between the two bottoms.
The angle of the apex of the outer cone would, in practice, usually be made more
acute than that of the inner, so that the distance between them would increase
from the top where the cones meet, downwards to where a series of branch pipes
radiate outwards from the chamber. These pipes establish communication between
the chamber and an annular tube encircling the bottom of the pan and serve to
deliver air to the chamber from an air supply pipe to which the tube is connected.
The pan is provided at top with a goose neck" outlet pipe attached to the
suction pipe of the exhaust apparatus, and with a collector or save-all to retain and
return to the pan any liquid brought over, and at bottom has a discharge valve.
The pan is also furnished with means for the introduction of liquid at any period
of the operation, sight glasses, proof-sticks, thermometers, and all the necessary
and usual fittings.
66
The combined area of the holes in the inner bottom of the pan should be less
than that of the radiating air inlet pipes, so as to allow the accumulation of a
greater air pressure in the chamber between the two bottoms, than exists above
the surface of the liquid in the pan, and thus to prevent the passage of any liquor
into the chamber.
The air which is drawn in through the perforations in the inner bottom when
the exhaust is operated, permeates the liquid under treatment, maintaining it in a
state of constant agitation and rapidly carrying off the vapor generated.
Dated this 25th day of August 1894.
A. M. & WM. CLARK,
53, Chancery Lane, London, Chartered Patent Agents.

page_text: COMPLETE SPECIFICATION.
An Improved Process of and Apparatus for Evaporating or
'Concentrating Saccharine and other Liquids.
I, ALEXANDER CRERAR, of 9, Fenchurch Avenue, in the City of London, West
India Merchant, do hereby declare the nature of this invention (a communication
to me' from Walter Rodwell Boon, of Wingfield Manor, St. Kitts, West Indies,
and Ernest Albert Hancock, of Basseterre, St. Kitts aforesaid;) and in what
manner the same is to be performed, to be particularly described and ascertained in
and by the following statement:-
"This invention relates to an improvement in the process of evaporating liquids
generally, but has more especially for its object to enable-saccharine liquids to be
concentrated at a lower temperature, and more speedily, than is now possible.
Hitherto the methods employed to evaporate saccharine liquids. consisted in
either beating in an open vessel or pan; boiling in a vacuum pan; forcing air,
either heated or not, through the liquid; or passing the liquid over a heated plate,
as in Fryer's concretor. None of these methods, however, produce the best
results.
The process of this invention, which is designed to be an improvement on all
former methods, consists essentially in drawing air or other gas, preferably heated,
through the liquid undergoing evaporation in the vacuum pan, so as to absorb and
carry off the vapour as it is generated.
The invention also comprises the apparatus whereby the process may be carried
into effect, constructed substantially as hereafter described with reference to the
accompanying drawings, forming part of this Specification, in which
Figure 1 is an elevation of the evaporating apparatus.
Figure 2 is a sectional elevation of the lower part only of the pan.
Figure 3 is an underside view.
The same letters of reference denote like parts in all the figures.
The apparatus consists of a closed pan or vessel A. of iron or copper, etc.,
provided with a double conical bottom B, C, the air space D intervening between
the inner and outer bottom communicating with an air inlet E.
The inner
bottom B, which is preferably of conical form to facilitate the discharge of the
contents of the pan, is perforated with a number of small holes 6 by which the
air supplied to the intervening air space D passes into the pan and up through
the liquid contained therein. The inner bottom B communicates with a discharge
spont closed by a valve, which passes through the outer bottom C. The latter
is also coniform and preferably rather more acute than the inner bottom so that
the cones meet at their junction with the body part A of the pan and diverge
in the downward direction to the point where radial branch pipes G establish
communication between the air space D and an annular encircling tube G', to
which the air supply pipe E is connected. This pipe E should be connected to an
air heater, not shewn in the drawing. The aggregate area of the holes 6 in the
inner bottom B of the pan should be less than that of the radial air inlet pipes, so
that the air pressure in the space D between the two bottoms will be so inuch
greater than that above the surface of the liquid in the pan as to prevent the
passage of any liquor into the space D. bare holes through which any drip may
pass into the discharge spout F.
The hood of the pan A is connected by a "goose neck" outlet pipe with a
collector or save-all H to retain any liquid brought over, which is returned to the
pan A through a discharge valve connecting the bottom of the save-all to the
top of the pan. To the save-all or collector H is attached the suction pipe of
the exhaust apparatus, and the pan A is furnished with means for the introduction

page_text: of liquid and also with sight-glasses, proof-sticks, thermometers, and all the necessary
and usual fittings.
The air which is drawn in through the perforations in the inner bottom B when
the exhaust is operated permeates the liquid under treatment, maintaining it in a
state of constant agitation, and rapidly carrying off the vapour generated. The
air, especially if it has first been raised to a proper temperature by the air heater,
abstracts the moisture very readily in passing upward through the liquid, leaving
the solid particles behind, and thus the liquid is gradually concentrated to the
required consistency by evaporation effected by upward currents of air drawn
through it by the force of suction of the exhausting apparatus.
This method of evaporation differs from any other at present in use and ensures
greater rapidity of evaporation at a much lower temperature, and with a less
expenditure of fuel, inasmuch as it combines the evaporative effect of the air drawn
up through the liquid with the reduction of pressure on the surface of the liquid
which has the effect of greatly hastening the evaporation and lowering the
temperature at which vapour given off. This is of vital importance in the case
of a saccharine liquid, because prolonged boiling and high temperature have a
tendency to invert the sugar, that is, to convert it into glucose. As only a partial
vacuum is required, an exhausting pump of the efficiency used with an ordinary
vacuum pan need not be used, but a suction apparatus, like a Root's blower, or an
exhaust fan, will be quite sufficient, and as there is no need of condensing the
resulting vapours, no condenser is needed, as with a vacuum pan; a saving is
consequently effected in respect of the use of water for condensing, which is a
drawback to vacuum pans where water is difficult to obtain.
The process enables sugar to be made of equal quality to that produced by the
vacuum pan and gives the same facility for building up the grain of the sugar, and
it will often be possible to do the whole of the evaporation by heating the air by
waste steam or by waste heat from the flue.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The herein described method of evaporating and concentrating saccharing
and other liquids, which consists in drawing air or gas in fine streams upwards
through the liquid by exhaustion, whilst the liquid is undergoing evaporation
in vacuo...
2. The herein described method of evaporating and concentrating saccharine
and other liquids, which consists in drawing heated air in fine streams upwards
through the liquid by exhaustion of the atmosphere above the liquid whilst the
liquid is undergoing evaporation.
3. In evaporating and concentrating saccharine and other liquids, the method of
combining the effect of heated air passing up through the liquid in fine streams
with that of lowering the boiling point by diminishing the pressure on the surface
of the liquid, as specified.
4. The apparatus for carrying out the above described method of evaporating
and concentrating liquids, consisting mainly of a vacuum pan or vessel with double
conical bottom, the inner bottom being perforated to allow air to enter the pan
from the intervening air space which is connected by pipes, as described, with an
air heater, substantially as specified.
Dated this 23rd day of May 1895.