Improvements in or connected with the Method and Means for Treating Wood and other Materials at High Temperatures whereby Heat may be More Effectively Utilized.
Year: 1892

page_text: Date of Application, 4th Aug., 1892
Complete Specification Left, 3rd May, 1893-Accepted, 2nd June, 1893
PROVISIONAL SPECIFICATION.
Improvements in or connected with the Method and Means for
Treating Wood and other Materials at High Temperatures
whereby Heat may be More Effectively Utilized.
We, JAMES BEVERIDGE, of Gravesend, in the County of Kent, Paper Maker,
and JAMES BINGHAM ALLIOTT, of Bloomsgrove Works, Nottingham, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention has reference to improvements in or connected with the method
and means for treating wood and other materials at high temperatures whereby
heat may be more effectively utilized; and it may be employed with advantage in
the manufacture of paper from wood, esparto grass and other like materials where
the material itself is first digested in an alkaline liquor at a high temperature, also
in other industries in which like conditions prevail.
In preparing wood for the manufacture of paper, the wood is digested for some
hours at a high temperature, steam at a pressure of 110 lbs. or thereabouts
corresponding to a temperature of some 330° to 340° F. being usually blown into
it, and the mass being raised to about this temperature to produce the desired
result.
When the process of digestion is finished it has been usual to blow away to waste
the steam from the digesters, and thus lose all the heat stored up in them.
Now according to our invention multiple evaporating apparatus is combined with
the digesters in such a way that the steam given off by them during the process of
reducing the pressure may be used entirely or in part for effecting the evaporation
in the multiple evaporator.
In the manufacturing of paper from wood pulp the steam thus obtained from the
digesters may be made to effect a great part of the evaporation needed to concentrate
the soda lye usually employed, and to prepare it to be passed into the special
furnace in which it is burnt into carbonate of soda for further use.
In some cases we make use of the heat generated in the special reburning
furnaces to heat the steam boilers required to produce the further amount of steam
needed to complete the evaporation of the soda lye; while, if necessary, further
heat may be supplied to these boilers, from other furnaces or by the use of
additional fuel, or an additional supply of steam may be obtained from some other
source.
In order that the nature of our invention may be the better understood, we will
describe the combination of the digesters with a quadruple evaporator, that is to
say, with an evaporator the first vessel of which is heated by steam taken from
some source outside the evaporator itself (such as a steam boiler, the exhaust of a
non-condensing steam engine, or the digesters with which we combine it) while the
whole of the steam given off during the process of evaporation in the first vessel is
employed (with or without the addition of other steam) in effecting evaporation in
the second vessel-the whole of the steam evaporated in the second vessel is in
like manner employed (with or without the addition of other steam) in effecting
evaporation in the third vessel; and the whole of the steam evaporated in the third
vessel (with or without the addition of other steam) is used to effect the evaporation
in the fourth vessel.
With the fourth vessel we consider it advantageous to combine a condenser and
air pump so as to maintain a good vacuum in it, and thus increase the range of
temperature between the steam employed in heating the first pan and the vapour
given off by the fourth, since this range of temperature determines the capacity of

page_text: the apparatus, and the number of evaporating vessels which can be usefully
employed.
It is obvious that the number of vessels employed may be varied as the range of
temperature available is greater or less, and according as saving in the cost of
apparatus, or economy in the use of heat, is the more important. Double, triple
or quadruple evaporators, or those having yet more vessels combined in a single
series can be used, according to circumstances.
If the digester full of alkaline liquor, pulp, &c. at a temperature of say from 3:30°
to 334° F. be connected directly to the first vessel of the evaporator, it is obvious
that the vapour given off will at first have a pressure corresponding to that at
which the alkaline liquor can boil or give off vapour freely at the temperature in
question, and that as steam is drawn off and heat abstracted the pressure and
temperature will gradually fall, until the temperature of the vapour given off is
too low to do useful work. Under these circumstances the work done by the
multiple effect would be very irregular, evaporation taking place very rapidly at
one time and very slowly at another, while the condenser and air pump which would
be right in size and arrangement at one part of the process would be either quite
inadequate or altogether too powerful at another.
It would also be impracticable under these circumstances to connect to the same
multiple effect both a digester partly exhausted of its heat and pressure and one in
which the work of digestion had just been completed but from which no vapour
had been withdrawn.
We therefore prefer to draw off the vapour from the digesters to the multiple
effect through diminishing valves, which enable it to be drawn off for a considerable
time at a constant pressure, and when the supply of vapour at a given pressure has
become exhausted or nearly so, the valve can be altered; or a second valve
arranged to draw off vapour at a lower pressure can be made use of, and this
vapour at this lower pressure, instead of being employed in the first vessel of the
multiple effect, inay be taken direct into the second or the third, or into that vessel
in the series in which the heating vapour corresponds with that being drawn off at
a diminished pressure from the digester. The number of diminishing valves, or of
separate connections to different vessels in the multiple effect may correspond with
the number of different pressures at which it is desired to employ the steam.
In this way the first vessel of the multiple effect may be heated by vapour from
a digester from which vapour is only just beginning to be drawn off (together with
such a quantity of steam from other sources as may be necessary to complete the
work), while the second will be heated by vapour from the first vessel and by that
from a second digester in which the pressure and temperature have considerably
fallen, and so on.
Furthermore, as each succeeding vessel of the triple effect will, under the
arrangements described, be heated by the whole of the vapour given off by the
preceding one plus an additional supply of vapour from a digester, the heating
surface for utilizing and condensing this increased supply of steam may be
proportionately increased.
If steam should be available at a higher pressure than the highest at which it is
convenient to draw off steam from the digesters for the purposes of evaporation,
such higher pressure steam may be used in a separate evaporator, the vapour given
off from which may be employed, together with vapour taken from the digesters,
to effect the evaporation in the first vessel of what (for the sake of distinguishing
it from this separate evaporator which may or may not be made use of) we will
call the multiple effect proper.
The liquor to be evaporated may be passed into the separate evaporator (where
there is one) thence into the first vessel of the multiple effect, thence into the
second, and so on to the last; or in some cases it may be advisable to reverse, or
partially reverse, this order, and pump back the liquor to be finished in the separate
evaporator or in the first vessel of the multiple effect, as the case may be.
In some cases we find it desirable to introduce save-alls or steam receivers

page_text: between the digesters and the multiple effect to prevent the carrying over of liquid
with the vapour into this apparatus.
Dated this 4th day of August 1892.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.Č., Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in or connected with the Method and Means for
Treating Wood and other Materials at High Temperatures
whereby Heat may be More Effectively Utilized.
We, JAMES BEVERIDGE of Gravesend, in the County of Kent, Paper Maker,
and JAMES BINGHAM ALLIOTT of Bloomsgrove Works, Nottingham, 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:-
This invention has reference to improvements in or connected with the method
and means for treating wood and other materials at high temperatures whereby
heat may be more effectively utilized; and it may be employed with advantage in
the manufacture of paper from wood, esparto grass and other like materials where
the material itself is first digested in an alkaline liquor at a high temperature, also
in other industries in which like conditions prevail.
In preparing wood for the manufacture of paper, the wood is digested for some
hours at a high temperature, steam at a pressure of 110 lbs. or thereabouts,
corresponding to a temperature of some 330° to 340° F. being usually blown into
it, and the mass being raised to about this temperature to produce the desired
result.
When the process of digestion is finished it has been usual to blow away to waste
the steam from the digesters, and thus lose all the heat stored up in it.
Now according to our invention multiple evaporating apparatus is combined with
the digesters in such a way that the steam given off by them during the process of
reducing the pressure may be used entirely or in part for effecting the evaporation
in the multiple evaporator.
In the manufacturing of paper from wood pulp the steam thus obtained from the
digesters may be made to effect a great part of the evaporation needed to con-
centrate the soda lye usually employed, and to prepare it to be passed into the
special furnace in which it is burnt into carbonate of soda for further use.
In some cases we make use of the heat generated in the special reburning
furnaces to heat the steam boilers required to produce the further amount of steam
needed to complete the evaporation of the soda lye; while, if necessary, further
heat may be supplied to these boilers from other furnaces, or by the use of
additional fuel; or an additional supply of steam may be obtained from some other
source.
In order that the nature of our invention may be the better understood, we will
proceed to explain the same by the aid of the accompanying drawing which shows
diagrammatically the combination of four digesters suitable for digesting wood or
esparto grass for use in the manufacture of paper with a quadruple evaporator or
multiple effect apparatus.
123 and 4 are the four digesters for digesting wood or other matter in a manner
well understood. These digesters which may each be provided with a save-all or
steam receiver 5 of ordinary construction to retain liquor and wood, esparto or
other matters passing over with the escaping steam are each connected with a steam
drum or vessel 6 that may advantageously be provided with a steam gauge. The
multiple effect apparatus comprises in the example shown four evaporating
vessels 7 8 9 and 10 that are of the usual well known construction, and each of

page_text: which is provided with the fittings, such as valves and gauges, etc. usually
applied to such vessels. 11 is another evaporating vessel hereinafter referred to.
12, 13 14 and 15 are four steam pipes common to the several digesters and
evaporators. These pipes are connected with each steam drum or vessel 6 by
branch pipes fitted with stop valves 16, 17, 18 and 19 respectively and with
diminishing or reducing valves 20, 21 22 23 respectively. Or instead of providing
each branch pipe with a diminishing or reducing valve, one such valve 20* may be
used that is capable of being adjusted from time to time for different pressures and
which is placed in the steam pipe connection between each steam drum or vessel 6
and the save-all 5. 24, 25, 26 and 27 are pipe connections whereby the steam
pipes 12, 13, 14 and 15 respectively can be placed in connection with the steam
supply pipes 28, 29, 30 and 31 respectively of the four evaporators 7, 8, 9 and 10.
The first vessel 7 of the evaporator is heated by steam taken from some source
outside the evaporator itself (such as a steam boiler, the exhaust of a non-condensing
steam engine, or the digesters with which, we combine it), while the whole of the
steam given off during the process of evaporation in the first evaporating vessel is
employed (with or without the addition of other steam) in effecting evaporation in
the second vessel 8, the whole of the steam evaporated in the second vessel is in
like manner employed (with or without the addition of other steam) in effecting
evaporation in the third vessel 9; and the whole of the steam evaporated in the
third vessel (with or without the addition of other steam) is used to effect
the evaporation in the fourth vessel 10.
With the fourth vessel 10 we consider it advantageous to combine a condenser
and save-all 32 and an air or vacuum pump 33 so as to maintain a good vacuum in
it, and thus increase the range of temperature between the steam employed
in heating the first pan and the vapour given off by the fourth, since this range of
temperature determines the capacity of the apparatus, and the number of
evaporating vessels which can be usefully employed.
It is obvious that the number of evaporating vessels employed may be varied as
the range of temperature available is greater or less, and according as saving in the
cost of apparatus, or economy in the use of heat, is the more important. Double,
triple or quadruple evaporators, or those having yet more vessels combined in a
single series can be used, according to circumstances.
The last vessel 10 of the quadruple effect apparatus may exhaust if desired direct
into the open air or the steam escaping from it may be utilized for heating water
or other liquor thus dispensing with the condenser and vacuum-pump but this will
lessen the range of temperature referred to and will therefore lessen the amount of
work done in an apparatus of a given size. When however a vacuum is produced
in the last vessel 10 the exhaust steam from the vacuum-pump may be utilized
either for heating water or liquor, or in one of the vessels of the quadruple effect
apparatus as may be desired, thus diminishing the cost in fuel for producing the
vacuum in the last vessel 10 of the quadruple effect apparatus.
If either of the digesters 1, 2, 3, 4 containing alkaline liquor, pulp, &c. at a
temperature of say from 330° to 334° F., be connected directly to the first vessel 7
of the evaparator, it is obvious that the vapour given off from the digester will at
first have a pressure corresponding to that at which the alkaline liquor can boil or
give off vapour freely at the temperature in question, and that as steam is drawn off
and heat abstracted the pressure and temperature will gradually fall, until the
temperature of the vapour given off is too low to do useful work. Under these
circumstances the work done by the multiple effect would be very irregular,
evaporation taking place very rapidly at one time and very slowly at another,
while the condenser and air pump which would be right in size and arrangement at
one part of the process would be either quite inadequate or altogether too powerful
at another. It would also be impracticable under these circumstances to connect
to the same multiple effect vessel both a digester partly exhausted of its heat and
pressure, and one in which the work of digestion had just been completed but from
which no vapour had been withdrawn.

page_text: We therefore prefer to draw off the vapour from each of the digesters to the
several evaporators of the multiple effect apparatus through diminishing or reducing
valves, which enable it to be drawn off for a considerable time at a constant
pressure, say through the reducing valve 20 or 20, and steam pipes 12 and 24 to
the first vessel 7 and when the supply of vapour at a given pressure has become
exhausted or nearly so, the valve 20 can be altered; if one diminishing or reducing
valve only be used for each digester or a second valve 21 arranged to draw off
vapour at a lower pressure can be made use of, and this vapour at this lower
pressure, instead of being employed in the first vessel 7 of the multiple effect, may
be taken direct through the pipes 13 and 25, or 14 and 26, into the second or the
third or into that vessel in the series in which the heating vapour corresponds with
that being drawn off at a diminished pressure from the digester the steam being led
through one or other of the pipes 13, 14 and 15 and corresponding connections
according to the evaporating vessel into which it is introduced. The number of
diminishing or reducing valves, or of separate connections to different vessels in the
multiple effect, may, as in the arrangement shown, correspond with the number of
different pressures at which it is desired to employ the steam.
In this way the first vessel 7 of the multiple effect may be heated by vapour from
a digester from which vapour is only just beginning to be drawn off, (together with
such a quantity of steam from other sources as may be necessary to complete the
work), while the second 8 will be heated by vapour from the first vessel 7 and by
that from a second digester in which the pressure and temperature have considerably
fallen, and so on.
As each succeeding vessel of the triple effect will, under the arrangements
described, be heated by the whole of the vapour given off by the preceding one,
plus an additional supply of vapour from a digester, the heating surface for utilizing
and condensing this increased supply of steam may be proportionately increased.
For this reason, the vessels 7 to 10 inclusive are shown in the drawings, as of
gradually increasing size.
If steam should be available at a higher pressure than the highest at which it is
convenient to draw off steam from the digesters for the purposes of evaporation,
such higher pressure steam may be used in a separate evaporator, indicated at. 11
in the drawing, the vapour given off from which may be employed, together with
vapour taken from the digesters through the pipes 12 and 24, to effect the
evaporation in the first vessel of what (for the sake of distinguishing it from this
separate evaporator which may or may not be made use of) we will call the
multiple effect proper.
The liquor to be evaporated may be passed into the separate evaporator (where
there is one) thence into the first vessel of the multiple effect, thence into the
second, and so on to the last; or in some cases it may be advisable to reverse, or
partially reverse, this order, and pump back the liquor to be finished in the
separate evaporator, or in the first vessel of the multiple effect, as the case
may be.
'
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The hereinbefore described improvement in means for the treatment of wood
and other materials at high temperatures which consists in combining multiple
evaporating apparatus with digesters in such a way that the steam given off by the
digesters during the process of reducing the pressure may be used entirely or in
part to aid in effecting evaporation in the said evaporating apparatus as set forth.
2. The connection of a digester or digesters or apparatus for treating wood or
other inaterials with liquid at a high temperature with multiple effect evaporating
apparatus in such a way that the steam from the digester or digesters can when at
its highest pressure and temperature be utilized in the first vessel of the multiple
effect apparatus and when the temperature and pressure in the digester (or digesters)

page_text: have fallen so that the steam therefrom can no longer be usefully employed in the
first vessel, it can then be used in the second, or some other vessel of the multiple
effect apparatus as circumstances may permit substantially as herein described.
3. Combined apparatus of the kind referred to in the preceding claim in which a
diminishing or reducing valve capable of adjustment for different pressures, or a
series of diminishing or reducing valves set for different pressures is introduced
between each digester and the multiple effect apparatus substantially as herein
described for the purpose specified.
4. The combined apparatus for treating wood or other materials at a high
temperature and utilizing the heat of steam produced comprising digesters, multiple
effect evaporating apparatus and pipe connections with valves constructed* &
arranged as herein before described and shown in the drawing annexed, whether or
not a condenser and air or vacuum pump, or a separate evaporating vessel 11 be
used, and whether or not the steam boiler used for supplying the further quantity
of steam required in the multiple effect apparatus be heated by the furnace
employed for evaporating to dryness the liquor concentrated in the said multiple
effect apparatus.
Dated 191 1... c AL 1000
JAMES B. ALLIOTT,
W. Lloyd Wise,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicants.