Manufacture of Sugar and for similar Purposes.
Year: 1886

page_text: :
Date of Appoliation, 25th Nov., 1886.
Complete Left, 5th Jan., 1887.
Complete Accepted, 8th Feb., 1887.
Manufacture of Sugar and for similar Purposes.
We, JULIUS HORNUNG and CARL RABE, both of Sangerhausen, Prussia,
Manufacturers, and FRANZ JOSEPH WEISS of Basle, Switzerland, Civil Engineer do
hereby declare the nature of this invention to be as follows:-
Our invention relates to multiple effect evaporating apparatus such as is used in
sugar, chemical and other factories for concentrating liquids within a partial vacuum.
The object of the invention is to provide novel means for producing in a con-
trollable manner, and maintaining automatically, the necessary descent in pressure
and temperature from one evaporator to the next evaporator of the multiple-effect
system, (without resorting for the purpose to the use of vapour-pumps, receivers and
the like, as heretofore) by means of a peculiar and novel arrangement of pipes in
accordance with simple hydrostatic principles. At the same time the water of con-
densation forming in the heating pipes of the several evaporators, is led off
automatically and continuously, and, if desired, can be collected separately.
The said invention, therefore, consists essentially in producing and automatically
maintaining any desired pressure, and any desired boiling-temperature, in the several
evaporators of the so-called "multiple effect evaporating-apparatus," by connecting
by means of pipes, the lower ends of the several heating systems, or coils of the
several evaporators with standing pipes terminating at their lower ends below the
level of water and connected at their upper ends with the condenser.
The connection of the connecting pipes with the said standing pipes is made so
that they communicate at predetermined heights above the low-water level, the said
pipes at the same time serving the further purpose of educting continuously and
automatically the water of condensation forming within the said heating systems, as
well as any excess of uncondensed steam and air or other gases.
In some cases we provide, in combination with such arrangement, back pressure-
valves within the said connecting pipes, and combine with them an arrangement of

page_text: connecting cocks between the several distinct evaporators and the condenser, the
object of this combination being to produce a vacuum within all the said evaporators
before commencing to boil again.
Sometimes we propose to use with multiple effect apparatus constructed in
accordance with our present invention, narrow perforations or, in lieu thereof, air
inlet-valves applied to the said several and distinct evaporators for the purpose of
rendering the back-swell of the water of condensation in the several heating coils
impossible in cases where the dimensions of the several heating surfaces are not
properly chosen and where, simultaneously, the evaporating apparatuses are absolutely
air-tight and do not contain any permanent gas.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicants.

page_text: Improvements relating to Evaporating Apparatus for Use in the
Manufacture of Sugar and for similar Purposes.
We, JULIUS HORNUNG and CARL RABE, both of Sangerhausen, Prussia and FRANZ
JOSEPH WEISS of Basle, Switzerland, 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 :-
Our invention relates to improved multiple effect, evaporating or distilling
apparatuses for evaporating liquids under a partial vacuum and of the class applied in
sugar and chemical manufactories, salt works, and the like.
Multiple effect evaporating apparatus comprises as is well known a number of
evaporating chambers connected with each other by a system of pipes and arranged
in line in such a manner that only the first evaporating chamber is heated by steam,
taken either direct from some boiler or from the exhaust of an engine, while the
second evaporating chamber is, in turn, heated by the vapours generated in the first
chamber, the said vapours being made to pass through the heating pipes of the second
chamber, and so on, the vapours of each successive chamber heating the contents of
each adjacent chamber until the vapours of the last of the series of evaporating
chambers are ultimately collected in a condenser in which the requisite vacuum is
produced and maintained by means of an air pump and in which the said vapours are
ultimately condensed.
In order to cause the vapours generated in each chamber to heat and to evaporate
the contents of each successive chamber, it is necessary that the vapours generated in
one chamber should in each case have a higher temperature than that of the liquid to
be evaporated in the next chamber, or in other words, a successive descent or decrease
of temperature should prevail in each successive chamber so as to cause the contents
of each distinct evaporating chamber to be evaporated.
Since, however, the pressure under which a liquid commences to boil, always bears
a fixed physical relation to the temperature of such liquid, it is also necessary to
provide for a successive descent, decrease or diminution of pressure from one
This successive
evaporating chamber to the next or in each successive chamber.
decrease of pressure, and hence also of temperature, was heretofore, always secured
by different means, one of which consisted in the use of a certain style of pumps, for
instance the so-called vapour-pumps, by means of which the water of condensation
together with the air was sucked out of the heating pipes of the several chambers,
while, in other cases, special receivers for the pipes of the several chambers were
provided and connected in a peculiar manner with the main air pump and condenser,
and so on.
The object of the present invention is to provide novel means for producing and
automatically maintaining the said successive decrease of pressure and temperature in
each successive chamber of a series in a controllable manner, and without resorting
for the purpose to any pumps or receivers or similar devices.
This invention, therefore, consists in a peculiar and novel arrangement of pipes

page_text: according to simple hydrostatic principles, the action of the improvements being at
the same time such that the water of condensation being formed within the heating
pipes of the several evaporating chambers is automatically and continuously led off
or carried away and may, if desired, be collected separately.
In order to render the principle of the said invention more clearly understood we
will now describe the same with reference to the accompanying drawings in which
Figures 1 to 5 inclusive are vertical sectional views showing the principle of the
said invention as applied in different modified forms to the improved apparatus.
Referring to Figure 1, suppose S to designate a vertical (or inclined) straight (or
bent) stand pipe communicating at the top, with a closed chamber C, and on one side,
by means of the pipe D communicating with the closed chamber V, the lower end of
the stand pipe S being immersed in water. At first all the pipes, chambers, and
connections are filled with air of mean atmospheric pressure down to the water
level F G.
The short pipe E is connected with a suitable pump by means of which air is
sucked out of chamber C through the said short pipe E. The air throughout the
entire system of pipes and connections is thereby rarefied and, yielding to the
pressure of the outer atmosphere, water will rise in the stand pipe S. After the
rarefaction of air (which is the same in all the spaces V; D, S, and C) has reached a
certain degree, corresponding to the absolute pressure p³, we will suppose the water
level in the stand pipe S to have risen as far above the original water level F, G as the
vertical height h¹ so as just to close the mouth of the branch pipe D. If the rarefac-
tion of air in the chamber C is still further increased, then the pressure in chamber C
will be still further decreased until it reaches, say the pressure p, and the water in the
stand pipe S will rise still higher, say as far as the height above the original water
level. Water will thereby be prevented from entering the chamber V, by the pressure
of air prevailing therein. Thus in rarefying the air in chamber C still further, the
pressure p' in chamber V, will not be changed but will remain at its standard p².
This air pressure p¹ is equal to the pressure of the column of water (h, h¹) plus the
(air) pressure p, and the total of both of the last named pressures plus the pressure
of the column of water ¹ is, in turn, equal to the pressure of the outer atmosphere.
Therefore, this pressure p¹ is equal to the pressure of the outer atmosphere minus the
pressure of the column of water h¹, that is to say :-always presuming the pressure of
the outer atmosphere to remain constant, the pressure p will likewise always remain
constant when the height h¹ remains constant, no matter whether the rarefaction of
air in chamber C is carried on to any extent, or the pressure p is reduced as far as
desired, if only p has once become smaller than pl. Mathematically speaking, and
presuming B to signify the barometrical height for water (in Meters: = 10.33 m) und
the pressure p, to be expressed in atmospheres, the law above referred to may be
expressed as follows, that is to say,
'h² = B. (1-p¹)
If, therefore, a constant air pressure p = 0.3-Atmospheres is to be maintained
in the chamber V, for instance, then it will be necessary to make h¹ = 10.33
(1-0.3) 7.23 m. In order to allow of making the constant pressure p³ as small as
may be desired the vertical length of the stand pipe S should be at least equal to the
barometrical height for water B.
=
It has been shown that, after the water level in the stand pipe S has once risen
above the height h³, the pressure p¹ will not be reduced any further even when air is
continually pumped out of chamber C. If, on the other hand, air is allowed to enter
the chamber V by opening the small cock T, Figure 2, this also will not cause the
pressure p¹ to rise, as the air thus admitted simply passes under the lowest down-
wardly projecting vertex of the connection between pipe S and chamber V and then
rises in the stand pipe S in the shape of bubbles, as shown in Figure 2, and is
ultimately sucked away by the air pump acting at the point E. The essential point
from which the height h must be calculated downwardly is always the lowest situated
downwardly projecting vertex of the connection between the chamber V and the stand
pipe S.

page_text: Un may also be expressed muus:
h¹
p² = 1 - B.
It is evident that the constant pressure p¹ depends solely upon the height 1 being
properly chosen. If it should be desired to change the said pressure p¹ while the
apparatus is in operation it will only be required to change the height of the column
of water h¹.
This may be effected by a number of mechanical means which are
readily understood by those acquainted with the art. The simplest way is to make the
height of the water level adjustable, either by constructing the vessel in which the
lower end of the stand pipe is iminersed adjustable as to its height, by suspending it
on movable chains, as in Figure 5, or by making this vessel stationary and providing
means for regulating the height of the overflow and thus also raising and lowering the
water lever F, G, as shown in Figure 3. A raising of the water level F G causes a
rise in the absolute pressure p¹ and consequently also a rise of the boiling temperature
of a liquid contained in chamber V, while a lowering of the water level F-G is
followed by the opposite effect.
The application of the principle, forming the basis of this invention, to evaporating
apparatuses is shown in the subsequent Figures of the drawings. Figure 3 shows an
evaporating apparatus of double effect. The original heating steam is introduced into
the evaporating chamber I through the pipe O, in which it communicates its heat to
the liquid to be evaporated therein, by means of the sides of the said pipe, in the
present instance shown in the shape of a serpentine.
The water of condensation formed in the said heating pipes is removed in a suitable
manner at P. The vapours generated in the evaporating chamber I, are by means of
pipe Q, introduced into the evaporating chamber II where they in turn cause the
liquid therein to boil. The water of condensation here forming in the heating tubes,
together with any steam that may not have been condensed and with air that may
have entered through leaks, passes into the stand pipe S through pipe D, the said
pipe S corresponding exactly to the stand pipe S already described with reference to
Figures 1 and 2. The distilled water flows down in pipe S, and is discharged at M
where it may be collected for use. The air entering the stand pipe S at s bubbles up
in the same and passes into the condenser through the pipes Land W whence it is
sucked away by the air pump acting at the point E. Any steam that may not have
been condensed also enters the stand pipe at's whence it rises in the shape of bubbles,
being thus partly condensed and is ultimately also carried into the condenser through L
and W being there further condensed.
The vapours generated in the chamber II are introduced into the condenser C
through the pipe W, the said condenser being supplied with cooling water from pipe R,
and an air pump being connected at E which produces the required vacuum in the
said condenser and all parts communicating therewith. The condenser shown is con-
structed of the principle of the common siphon, in which the warm water is
automatically sucked away through pipe A (of more than 10 meters in height) and
discharged at N so that the air pump at E has nothing but gases (air and a little
water steam) to suck away, and may, therefore, be a "dry" air-pump.
It may be stated here that for the purposes of this invention it is not at all necessary
to have this kind of condenser with siphon-pipe, as any other kind of condenser with
a so-called "wet" air-pump, which sucks away from the condenser both air and warm
water, will also answer the purpose. In this case, as well, it will simply be necessary
to connect the upper part of the stand pipe S with the condenser by means of a
tube L.
It is evident, after what has been previously stated that, in the arrangement here
shewn in diagram, the pressure p in the second chamber II (p = 1-1) must be less
than the pressure p' in the first chamber I (p' 1 1) since h is greater than h¹. It
follows that the temperature t¹ in the first chamber must be higher than that (t) in
=
-

page_text: the second chamber, and therefore the liquid in the second chamber may indeed be
brought to boiling by the vapours from the said first chamber. As long as the
height h¹ is left unchanged the pressure p' (and hence also the temperature t¹) will
remain constant, and it makes no difference to what extent h¹ varies so long as it
becomes less than h.
It now remains to explain the use and purpose of the following parts shewn in
Figure 3, that is to say, firstly of the valve K in pipe D and the connecting cock J
between the pipes Q and W or in other words between the two evaporating chambers
and the condenser and air pump, and secondly of the small cock T.
In proceeding to evaporate certain chemical products it is often found desirable,
before starting to boil, to remove as far as possible, the air from every evaporating
chamber. This is effected by means of the connecting cock J which at the commence-
ment of the operation is opened for a while before allowing the steam to enter at O,
but after the air pump has been started. This produces the same rarefaction of air in
the chamber I as in the chamber II and the condenser C, that is to say the air
contained in the chamber I is as much as possible removed on starting.
If as shewn in Figure 3, the highest point of the connecting pipe Q is not at least
as high above the water level M as the height h of the column of water being drawn
up, then water will be drawn into the chamber I through the pipe D, the heating coil
in chamber II and pipe Q. In order to prevent this, a valve K opening towards the
pipe S is inserted in pipe D, which valve renders it impossible for the water to re-enter
chamber I under the circumstances named. On subsequently closing the cock J and
admitting heating steam at O, the liquid in the chamber I will commence to boil under
the (lower) pressure p and (lower) temperature t. The pressure, however, and with it
the temperature will rise continually until the normal heights p¹ and t¹ have been
attained by the former and the latter, respectively, whereupon the valve K will open,
thereby causing the whole apparatus to again operate in the manner before described,
as if the cock J and valve V were not employed.
In boiling substances where the pressure of air is of no moment, the valve K and
cock J may be dispensed with. Any air that may, at first, be contained in the
apparatus will soon be carried away by the steam into the condenser and will thence
be taken away by the air pump.
As regards the purpose of the small cock T, it will be understood that, if the
evaporating chamber I is absolutely tight so as not to admit the least particle of air,
and if further the condensing surface of the heating pipes in chamber II is unduly
large, the water of condensation, after once all the air originally contained in chamber I,
and the serpentine heating pipe or coil within chamber II has been carried away, will
accumulate to such a height in this heating coil that the heating surface remaining free,
will barely suffice to condense the vapour coming from chamber I. In consequence of
such an accumulation or back swell of the water within the serpentine heating pipe in
chamber II the height of the column of water h¹ acting upon the chamber I will be
increased and the pressure p³, and with it the boiling temperature t¹, will be diminished
in a manner not intended. To prevent this the cock T is provided on chamber I. By
partially opening this cock T a small quantity of air may be continuously admitted
which will suffice to press the water level within the heating coil in chamber II down
to the proper heights and, thereby, produce and maintain the desired pressure p³ and
boiling temperature t¹.
From what has been stated it will be seen that this cock T is not, by any means, a
so-called regulating cock, it being immaterial, so far as its purposes are concerned
whether the sectional area of its opening is made say 1 or 100 square millimeters the
only objection in the latter case being that the air pump would have so much more
air to suck away from the condenser than in the former case. As a regulation by
means of the said cock T is not required it may, if desired, be replaced by a small
aperture or perforation in the wall of chamber I which would also admit a small
current of air into the said chamber. As a rule this small cock T or an aperture will
not be required, since the evaporating chambers and connections are generally
not so thoroughly air-tight as not to admit the least particle of air.

page_text: In such cases where it is not found of importance to suck up the distilled
water (or water of condensation) from the heating pipes separately, and where
at the same time the condenser of the distilling apparatus is one of the kind
which discharges its water by means of a barometrical water drop pipe, the
separate stand pipe S may be dispensed with, and the end of the serpentine pipe, that
is to say the pipe D, may communicate directly with the said drop pipe A of the
condenser, as shewn in Figure 4, the distilled water in this case being discharged at N
together with the warm water in the condenser, while the air and such vapours as may
not have been condensed, rise in said pipe A passing thence into the condenser in the
same manner as previously described with reference to the stand pipe S.
In the same manner as in evaporating or distilling apparatuses of double effect the
principle of this invention may also be applied in apparatuses of triple, quadruple,
quintuple, or other multiple effect.
Figure 5 is a diagram showing the arrangement as applied to an apparatus of
quadruple effect. To render Figure 5 at once understood it only remains to be stated
that U designates the cold water pump, X the air pump, C the condenser, Y a pump
for conveying the distilled water collected in a sort of cistern to the places where it is
to be used; and Z a steam trap for removing the water of condensation from the first
serpentine heating pipe which may have been fed with steam of a higher than
atmospheric pressure.
An example will best serve to render the further details well understood.
Let it be supposed, for instance, that by means of the combined action of a good air
pump X and an equally good counter steam-condenser C a vacuum could be obtained
within the last chamber IV, the said vacuum being found by the absolute pressure
p=0.094 atmospheres, and let it be further supposed that the pressure and boiling
temperature of the liquid to be evaporated be the same as in the case of water, then
the boiling temperature in the fourth chamber IV, in accordance with the pressure p,
will be t=45° Celsius (according to Regnault's Steam Tables). Supposing, further,
that the original heating steam entering the first chamber through pipe O have a
temperature of 105° Celsius (hence an absolute pressure of 1.20 atmospheres) then the
entire descent or diminution of temperature throughout will be
105-45-60°
Assuming the heating surfaces in the several evaporating chambers to be of equal
size, the essential condition for a maximum development of evaporating capacity on the
part of the apparatus will be this, that the entire diminution of temperature of 60°
be divided into four equal parts (the assumption-though only an approximately
correct one-being that the latent heat of steam under different pressures be the same
throughout) that is to say the division will have to be such that in chambers I II III IV
boiling temperatures of t¹-90° t²=75° t=60° -45° respectively are maintained
constant. Thus according to Regnault's Steam Tables, the absolute steam pressures in
the respective chambers would have to be p=0.691, p=0.380, p³=0.196, p*=0.094.
Atmospheres absolute.
These pressures are obtained by arranging the pipes D' D³ and D' conveying the
water of condensation, air, etc. into the stand pipe S, so as to enter the said stand pipe
at such heights h¹ h³ ³ above the water level of the discharge of the said stand pipe as
to make these heights conform to the general formula.
h=B (1-p)
or,
applying the meter standard
The action haigher in this
h=10.33 (1-p).
L

page_text: interference or regulation, and thus also is the evaporating capacity of the several
evaporating chambers maintained constant at their maximum.
If, however, the heights h³ ³ are changed, say by raising or lowering the over-
flow vessel M in which the lower end of the stand pipe S is immersed, then the
pressures p¹ p² p³, and hence also the boiling temperatures t' t t in the first three
evaporating chambers, will be changed in accordance therewith. The pressure p and
the boiling temperature in the last chamber will not be influenced thereby, provided
that the action of the air pump and condenser remains unchanged, and the height h in
the stand pipe likewise remains unchanged. The upper water level in the stand pipe S
is raised and lowered in exactly the same manner as the lower water level at M.
If all the pipes D' D2 D as shown in the diagram Figure 5, communicate with the
same stand pipe S, any change of one of the three heights h¹ h³ h³ in consequence of a
raising or lowering of the over flow vessel M will also cause a change in the two
remaining heights. In order to make each of the three heights h h h adjustable, or
capable of being regulated or changed, independently of the two others, and thereby
to make each of the three boiling temperatures t¹ t t variable in accordance therewith,
it would be necessary to let each of the three pipes D' D' D³ discharge into a separate
stand pipe, each of these stand pipes, in turn, being connected with a condenser at the
top and immersed in water below. If desired, such an arrangement would also allow
of not only collecting the distilled water per se but even the distilled water from each
system of heating coils of each evaporating chamber separately.
If it should be desired, before the commencement of each new process of boiling, to
remove the air from each of the chambers as thoroughly as possible, it would simply
be required to insert connecting pipes with cocks J between the pipes Q1 Q3 Q³ and W
(as previously shown with regard to Figure 3) the said cocks being left open for a
while before the commencement of such process of boiling. Unless, in such case, the
highest points of the pipes Q1 Q2 Q³ were at least as far above the discharge water level
at M as the entire height of suction (in Figure 5 they are as high as this) then the
pipes D1 D2 D3 would have to be provided with back pressure valves K as previously
shown with regard to Figure 3, so as to prevent the water from being sucked back into
the chambers I, II, and III from M, when the connecting cocks J are being opened.
If on the other hand, it were desired to evaporate such liquids as would not be
influenced by the pressure of air-and if one were sure that the dimensions of the
several heating surfaces had been chosen exactly right, according to the respective
degrees of diminution of temperature and, besides, presuming the evaporating chambers
to be absolutely air-tight; and if, in consequence, there might be reason to fear that
back swell or accumulation of water of condensation as already referred to with regard
to Figure 3, might occur which, in turn, might cause an unintentional variation of the
heights h¹³ ³ and hence also of the pressures p² p³p and boiling temperatures t¹² t³,
it would simply be necessary to allow a small amount of air to enter each of the
chambers I, II, III either by means of special small cocks T or by small apertures in
the walls of such chambers, as shown already with regard to Figure 3.
Again, if in applying the arrangement shown in principle in in figure 5, it should
not be considered of importance to have the quantities of distilled water sucked away
separately then the stand pipe S might be dispensed with, the pipes D' D³ D³, in such
case, being made to discharge directly into the pipe A of the condenser as previously
shown in Figure 4.
Of course, it is understood that what has been said above with regard to an
apparatus of quadruple effect also applies to any other apparatus of multiple effect with
the necessary alterations as will be readily understood without further explanation.
Haying now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is
First The method of producing and automatically maintaining any desired
pressure and any desired boiling temperature within each distinct chamber of the
severat evaporating chambers of so-called multiple effect evaporating or distilling
apparatus by arranging the lower ends of the several systems of heating pipes to

page_text: communicate by means of pipes D¹, D², D³, with stand pipes S or A at the sides thereof
and at certain predetermined variable or non variable heights h¹, h³, ³, above the
lower water level, the said pipes S or A being immersed in water at their lower ends
and communicating, at their upper ends, with the condenser, the water of condensation
forming within the heating systems as well as non-condensed steam, air or other gases
being educted continuously and automatically through the said pipes D and S or A,
substantially as described and for the purpose set forth.
Second In multiple effect evaporating apparatus as herein described, the combina-
tion, with back pressure valves K within the pipes D, of connecting cocks J between
the several evaporating chambers and the condenser, for producing a vacuum in all of
the evaporating chambers before the commencement of each boiling process,
substantially as described and for the purpose set forth.
Third-In multiple effect evaporating apparatus as herein described, the combination,
with the several evaporating chambers, of the cocks T or the equivalent small perfora-
tions, for preventing any undue accumulation of water of condensation in the several
heating systems in case of incorrect dimensions, of the heating surfaces, the several
apparatuses being absolutely air-tight and no permanent gas or gases prevailing.
substantially as described and for the purpose set forth.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicants.