Improvements in Apparatus for Evaporating or Concentrating Alkaline or other Solutions.
Year: 1892

page_text: Date of Application, 3rd June, 1892
Complete Specification Left, 2nd Mar., 1893--Accepted, 22nd Apr., 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Evaporating or Concentrating
Alkaline or other Solutions.
I, Alfred ChaPMAN of 17 York Street, Liverpool, Engineer, do hereby
declare the nature of this invention to be as follows:-
I have found in heating alkaline and other solutions in order to evaporate or
concentrate them, and more especially the spent alkaline lyes from esparto and
straw boilings that not only does the boiling point become higher as the liquor,
becomes denser but also that the specific heat of the liquor becomes greater, and
when working with a multiple effect apparatus it is more difficult for example to
evaporate 100 gallons water from liquor at 40° Twaddell to reduce it to
60° Twaddell than it is to evaporate 100 gallons water from 5° Twaddell
to 6° Twaddell notwithstanding a greater difference of temperature between the
heating vapor and the boiling liquor in the first case than in the latter.
The object of my invention is to assist and quicken the evaporation in the last
vessel and for this purpose I add to it another or auxiliary vessel in such a manner
as to make a compound high and low pressure last evaporating vessel, which I
arrange and work in the following manner.
::
Assuming in the first instance that the last evaporating vessel of a multiple
effect apparatus is to be compounded, I place by its side and as near thereto as
convenient another similar vessel but of much smaller size, say about one-fourth
or one-sixth of its capacity, according to the nature of the liquor to be treated.
This smaller or auxiliary vessel I connect at the top to the original vessel to which
it is added or to the condenser, but in such a manner that the pressure in both the
vessels will be equal. The drum of the original vessel is supplied by vapor from
the next preceding vessel of the multiple effect, but I supply the drum of the new.
or auxiliary vessel with steam from the steam boiler; the feed of liquor into the
last vessel of the multiple effect is from the preceding vessel of the multiple effect ;
and this liquor having passed through the last vessel proceeds to the new or
auxiliary vessel where, as it is treated with steam of higher pressure and therefore
of higher temperature but under the same pressure or vacuum as in the last vessel,
there will be a far greater difference of temperature between the steam in the
drum and the boiling liquor; and moreover the steam in the drum will be denser
and therefore more active in heating quality. By this means liquor that has been
brought up to 40° Twaddell or thereabouts in the multiple effect apparatus will be
concentrated to 60° Twaddell or more in the additional vessel at a very slight
additional cost of direct steam, and I further utilize this additional steam by con-
veying it as quickly as condensed into the drum of the original vessel which has
been compounded as described above, or into the drum of one of the other
evaporating vessels.
Generally I prefer to make the apparatus as described in my prior Specifica-
tions Nos. 1752 of 1888 and 2511 of 1888, and in applying the present invention
to any existing apparatus not made according to my said prior Specifications I
would prefer to modify them as far as possible so as to work in the way described
in my said prior Specifications.
Dated this 3rd day of June 1892
:
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for Evaporating or Concentrating
Alkaline or other Solutions.
I, ALFRED CHAPMAN of 17 York Street, Liverpool, Engineer, 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:-
I have found in heating alkaline and other solutions in order to evaporate or
concentrate them, and more especially the spent alkaline lyes from esparto and
straw boilings, that not only does the boiling point become higher as the liquor
becomes denser, but also that the specific heat of the liquor becomes greater, and
when working with a multiple effect apparatus it is more difficult for example to
evaporate 100 gallons of water from liquor at 40° Twaddell to reduce it to
60° Twaddell than it is to evaporate 100 gallons of water from liquor at 5°
to reduce it to 6° Twaddell, notwithstanding a greater difference of temperature
between the heating vapor and the boiling liquor in the first case than in the
latter.
The object of my invention is to assist and quicken the evaporation in the last
vessel, and for this purpose I add to it another or auxiliary vessel in such a manner
as to make a compound high and low pressure last evaporating vessel, which I
arrange and work in the following manner :-
Assuming in the first instance that the last evaporating vessel of a multiple effect
apparatus is to be compounded, I place by its side, and as near thereto as convenient
another similar vessel, but of much smaller size, say about one-fourth or one-sixth
of its capacity, according to the nature of the liquor to be treated. This smaller or
auxiliary vessel I connect at the top to the original vessel, to which it is added or
to the condenser, but in such a manner that the pressure in both the vessels will be
equal. The drum of the original vessel is supplied by vapor from the next preceding
vessel of the multiple effect, but I supply the drum of the new or auxiliary vessel
with steam from the steam boiler; the feed of liquor into the last vessel of the
multiple effect is from the preceding vessel of the multiple effect; and this liquor
having passed through the last vessel proceeds to the new er auxiliary vessel, where,
as it is treated with steam of higher pressure and therefore of higher temperature,
but under the same pressure or vacuum as in the last vessel, there will be a far
greater difference of temperature between the steam in the drum and the boiling
liquor; and moreover the steam in the drum will be denser and therefore more
active in heating quality. By this means liquor that has been brought up to
40° Twaddell or thereabouts in the multiple effect apparatus will be concentrated to
60° Twaddell or more in the additional vessel at a very slight additional cost of
direct steam, and I further utilize this additional steam by conveying it as quickly
as condensed into the drum of the original vessel which has been compounded as
described above, or into the drum of one of the other preceding evaporating
vessels.
Generally I prefer to make the apparatus as described in my prior Specifica-
tions Nos. 1752 and 2511 of 1888, and in applying the present invention to any
existing apparatus not made according to my said prior Specifications I would
prefer to modify them as far as possible so as to work in the way described in my
said prior Specifications; my present invention can, however, be applied to existing
apparatus without modifying them so as to work in the way described in my said
prior Specifications.
The accompanying drawing illustrates by way of example how I can apply my
invention to evaporating apparatus constructed in other respects substantially on
the lines of the apparatus described in my said two prior Specifications.
Let A represent the last pan or vessel of an existing multiple effect apparatus

page_text: which it is. desired to compound according to my present invention. I add the
pan B, connecting the top of it to A by the pipe G as shown, or in any other
convenient manner, so that the pressures in A and B are always equal.
The liquor flowing into the pan A by the syphon pipe H from the preceding
pan C passes up the heating tubes I and flows off from top of tube plate by the
pipe D which conducts it to the bottom of the pan B, whence it flows up through
the heating tubes K of pan B and out at their tops, and then runs off by the
pipe E to the extracting pump or other apparatus for extracting the liquor from
the pan B.
The vapor from the pan C is carried by the pipe L to the drum M of pan A, and
heats the liquor passing up inside the heating tubes I of pan A, the condensations
from pan A going through the pipe N to an extracting pump or other apparatus
for extracting them without impairing the partial vacuum formed in the drum M.
The vapour given off in pan A goes to the condenser by the pipe P. The
liquor concentrated in pan A as already explained passes into pan B by the
pipe D, and here instead of being exposed to the slight heat of the vapor in the
drum M which has come from the liquor in the preceding pan C, it is exposed to
the heat of direct steam admitted by the valve F to the drum Q of pan B, which
steam may either be high pressure steam direct from the steam boilers, or may be
of the same pressure and temperature as the steam admitted into the drum of the
first pan of the series, and the condensations from the drum of pan B may be carried
either into the drum of pan A by the pipe R, or into the drum of
C or into any
of the preceding pans, as may be most convenient, provided that the pressure under
which the steam condenses in the drum of pan B must at least be greater than the
pressure at which the drum into which it is discharged is working. By this means
the heat in the condensation water will be utilized.
pan
It is obvious that in making a new apparatus according to my invention many
different ways of constructing the parts could be devised, and even in adapting my
invention to an existing apparatus each case would have to be treated on its merits
and the simplest way of carrying out the conversion would have to be devised, but
in all cases the liquor from the last pan should flow off the top tube plate uninter-
ruptedly to the bottom of the small or finishing pan B, and this finishing pan must
be supplied with much hotter steam than the steam or vapour that is supplied to the
drum of the last pan.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is :-
1. In evaporating or concentrating apparatus constructed and working on the
multiple effect system, an additional or auxiliary evaporating vessel so connected
with the last vessel of the series that the pressures in the two vessels are equal, and
that the liquor flows into the auxiliary vessel from the said last vessel, the drum of
the auxiliary vessel being supplied with steam direct from the steam boiler or of
higher pressure than that in the drum of the last vessel, whereby this last vessel is
as it were compounded, substantially as set forth.
. 2. The construction of apparatus substantially as hereinbefore described for
evaporating or concentrating alkaline or other solutions.
Dated this 2nd day of March 1893
Q
J. C. MEWBURN,
55 & 56, Chancery Lane, London, Chartered Patent Agent.