Note: Descriptions are shown in the official language in which they were submitted.
106Z6Q6
This application is a dlvisional application of
Copending application No. 137,812 filed March 22, 1372.
The present invention relates to improvements in dual
temperature exchange systems for concentrating a desired material
by exchanging, at different temperatures, said deslred material
.
with another material between chemically different lighter and
heavier fluids, e.g. gas and liquid, which are physically
separable from each other and whlch are each capable of contalning
each of said materials.
In such dual temperature exchange systems, for instance,
as disclosed in my prior U.S. Patents ~o. 2,787,52~ issued
April 2, 1957; No. 2,895,803 issued July 21, 1959; and No.
3,142,540 issued July 28, 1964, a system is employed which
comprises one or more stages of hot and cold tower pairs for
contacting of said lighter and heavier fluids in countercurrent
relationship. In such known systems one of the two fluids is
supplied from an external source and is fed to the first tower
of the first stage pair of towers, enriched in the desired
material to be concentrated by preferential exchange therein,
impoverished in the said desired material in the second tower
of said pair to a concentration of the desired material less
than that of said feed supply fluid, and discharged from the
system. The other fluid is continuously circulated through
the pair of towers to become enriched in the desired material
in the second tower of said pair and to become impoverished in
that material in the first tower of said pair. Such a system
may comprise a plurality of similar or different concentrating
stages of known species, and a portion of the flow of one or
., - I
both of the enriched fluids being passed between said towers
30 in a stage other than the last is also impoverished in the des-
ired material during such passage by sub~ecting it to extraction
of desired material therefrom in the following stage or other
concentrating treatment. A portion of the enriched flow of one
,-
, - 1 -
.
~0626~)6
of the fluids is withdrawn as product from that part of the
system in which its concentration of the desired material
is high.
Also, in such dual temperature exchange systems, as
is shown by the above mentioned prior patents, various provisions
are made for moving the process fluids and adjusting the
temperatures thereof as required by the process, which employ
- fluid pumping means, heating and cooling means, and indirect
and/or direct contact heat exchange means provided to meet
the particular requirements of the system.
; The present invention, severally and interdependently
in various combinations, improves productivity when the feed
supply fluid is abundantly available at relatively low cost
and/or to reduce equipment costs when the character of the
feed supply fluid would impose costly requirements for the
` equipment in contact therewith in dual temperature exchange
systems; minimizes the area of contact of the equipment with
..,
such feed supply fluid; isolates such feed supply fluid in such
~ minimized area and excludes it from mixing with other similar
~ 20 process fluids in the system; and/or increases the fraction of
the desired material extracted from the feed supply fluid in
an economical manner; each of which increases the operating
efficiency and/or decreasing the overall cost of the system
per unit quantity of product.
To this end the improvements of the present invention
are concerned with the inter-relationship of the flow paths of
''
the auxiliary fluid and the fluids contacting the same in any
stage of such a system, particularly in a first stage or a single
::i
; stage system. The principles of these improvements are typically
exemplified by their application to the concentration of deuter-
. , .
; ium by countercurrent exchange reactions between the isotopés of
hydrogen at appropriate low and high temperatures, in hydrogen
-- 2 --
;2606
sulfide gas (H2S) and water (H20), and wherein water is the feed
supply and hydrogen sulfide is the auxiliary fluid employed in
the process. In such application the heating and cooling and
pumping of the fluids being passed through the cold and hot
temperature towers may be accomplished in any suitable manner,
e.g. in the manners disclosed in the aforesaid prior patents,
or in any other manner herein disclosed or known to those
skilled in the art, and the improvements of the present
invention pertaining to the inter-relationship of flow paths
in the said first stage are for the most part independent of the
particular manners of so moving and conditioning the process
fluids. In embodiments of the present invention, and in the
prior art, the flow path of the total flow of the auxiliary
fluid (e.g. H2S) passes through the entire extent of both the
hot and cold towers of the pair of tower-s, and in accordance
with the prior art the flow path of the total flow of the
other fluid (e.g. water) does likewise in countercurrent
relation to the auxiliary fluid. In accordance with the
.~ present invention, however, the flow path of the feed supply
fluid ~e.g. water) does not pass through the entire extent of
the first and second towers of the pair. Thus: i
`~ (a~ In a first embodiment of the present invention
the feed supply fluid (e.g. feed water) passes only through
the lower portion of the second (e.g. hot) tower wherein it
transfers the entire production quantity of the desired material
(e.g. deuterium) to the auxiliary fluid (e.g. H2S) and is then
discharged from the system, the auxiliary fluid (e.g. H2S) thence
undergoing the exchange reactions with a separate circulation
of other fluid (e.g. water) in the remainder of its flow path.
(b) In a second embodiment, modifying said first
embodiment, two feed supplies to the system are employed, one
thereof is utilized as in said first embodiment, and the other
-- 3
., ~
1~6Z606
thereof is employed in lieu of the separate circulation of
said first embodiment to contact the auxiliary fluid in the
; remainder of its flow path and is then discharged from the
system.
~c) In a third embodiment, further modifying said
second embodiment, the two feed supplies are handled as in
said second embodiment except that the second feed supply
fluid after contacting the auxiliary fluid in said remainder
of its flow path is combined with the first feed supply fl~id
passing in contact with the auxiliary fluid in said lower
portion of the second tower and is discharged from the system ~ ~
therewith. ?
(d) In a fourth embodiment, the arrangement is 7
similar to said third embodiment except that the second feed
supply fluid is not combined with the first feed supply fluid,
and said lower portion of the second tower is divided into two ~ ;
separate flow sections in which said first and second feed
supply fluids are separately contacted with parallel branches
of said flow of auxiliary fluid.
(e) In a fifth embodiment, the arrangement is similar ¦
to that of said first embodiment except that the separate
i circulation of other fluid (e.g. water) which contacts gaseous
;3~ auxiliary fluid in said remainder of its flow path is supplied
~ ~ with additional other fluid, either as feed supply fluid or as
.
condensate from the cooling of the hot saturated auxiliary fluid,
and the surplus of other fluid thus provided is combined with
said first feed supply fluid as in the third embodiment.
(f) In a sixth embodiment the arrangement is similar j~
to that of the fifth embodiment except that the surplus of other
t~' 30 fluid is not combined with the first feed supply fluid as in the 1
third embodiment, but instead is separately contacted with a
branched flow of auxiliary fluid as in the fourth embodiment.
. ,; .
l~Z60f~
(g) In a seventh embodim~t, the arrangement is
similar to the prior art system except that instead of the
entire feed supply fluid stream being discharged from the
stage after passing through the second tower, a portion thereof
is recirculated to the first tower, where it is mixed with the
incoming supply of feed fluid. The said stream after passing
through the second tower has a concentration of the desired
material lower than that in the incoming feed fluid supply
delivered in the first tower. Thus, in this embodiment, by
recirculating a part of said impoverished feed supply fluid
and mixing it with the incoming feed fluid supply the concen-
tration of the desired material in the feed supply fluid at
the top of the first tower is less than in the incoming feed
fluid, thereby reducing the concentration of the desired
material in the auxiliary fluid passing from the first tower ¦ -
; to the second tower, and in turn reducing the concentration of
the desired material in the feed supply fluid stream being
discharged from the second tower, thus increasing the fraction
of the desired material extracted from the incoming feed fluid.
(h) In an eighth embodiment the arrangement is
similar to the seventh embodiment except that the incoming
supply of feed fluid is introduced at the level in the first
tower at which the recirculated feed supply fluid stream has
become partially enriched to substantially the same concentration
of the desired material as that of the incoming feed fluid.
(i) In ninth and tenth embodiments, the arrangement
~ is similar to the third embodiment except that a portion of the
J~, feed supply fluid stream being discharged from the second tower
is recirculated to the top of the first tower and combined with
incoming supply of feed fluid as in the seventh embodiment or as
in the eighth embodimenti and similar modifications of the fourth,
fifth and sixth embodiments are also contemplated by the invention.
. .
1()6Z606
(j) In further embodiments of the invention, the
arrange~ents are similar to the sixth embodiment further
modified as in the ninth or tenth embodiments except that
the feed supply fluid stream recirculated to the top of the
first tower is derived from the surplus of other fluid which
was kept isolated from said first feed supply fluid and
separately contacted with a branched flow of the auxiliary
fluid.
In copending parent application No. 137,812 there is
disclosed in a method for producing a fluid containing
a first material concentrated therein, by exchanging at two
different temperatures said first material with a second -
.,, :
. material between chemically different first and second fluld
,7' phases which are physically separable from eacn other and -:
which are each capable of containing each of said materials, ~:
said materials being isotopic, said method being of the type
in which
~ (a) said second fluid phase is passed through each
:~ of the second and first units, in that order, of a pair of
.~ .
exchange units, and in which
(b) flows of said first fluid phase are passed in ~ -
` countercurrent contact with said second fluid phase in said .
~ first and second units of said pair,
:~ (c) said first and second units being maintained at
different temperatures to cause said second fluid phase to
become enriched in said first material in passing through said
second unit, and to become impoverished in said first material
in passing through said first unit of said pair, and to cause
~ the first fluid phase to become enriched in said first material
in passing through said first unit and to become impoverished in
, .. .
said first material in passing through said second unit of said
pair of units, and in which a part of at least one of the
-- 6
~.
0~
enriched fluids
passing between said units is withdrawn; the improve-
ment which comprises:-
(d) delivering a first flow of said first fluid
phase containing said materials from a source thereof and
passing said flow in countercurrent exchange with said impov- e
erished second fluid in a first delivery-to-discharge path
through a portion only of said second unit proximate to its
end at which said fluids are most impoverished in said first
material, and
~e). passing a second flow of first fluid phase in a
second delivery-to-discharge path exclusive of said first path
in countercurrent exchange with said second fluid phase in
other portions of said first unit and second unit of said pair
of units and as an enriched flow between said units. The
above cope~din~ application also disclosed and claimed improved
apparatus for producing a fluid containing a first material . .
concentrated therein, by exchanging at two different temperatures .
said first material with a second material between chemically
different first and second fluid phases which are physically .
separable from each other and which are each capable of contain-
ing each of said materials; said apparatus being of the type
which comprises:
(a) a pair of exchange lmits and means connected there-
to for passing said second fluid phase through each of the second
and first units of said pair in that order, and for also passing
flows of said first fluid phase in countercurrent contact with
~aid second fluid phase in said first and second units of said ~.
pair, :
~; 30 ~b) means for maintaining said first and second units
at different temperatures to cause said second fluid phase to
become enriched in said first material in passing through said
' .
, ~ 7 ~ ! ~
.
~ . . , ,. . , - ~ ~
. , ~
106Z~06
second unit, and to become impoverished in said first material
in passing through said first unit, of said pair, and to cause
the first fluid phase to become enriched in said first material
in passing through said first unit and to become inpoverished
in said first material in passing through said second unit of
: said pair of units, and .
~c) means connecte~ to said units for withdrawing a :~
part of at least one of the enriched fluids passing between :~
said units;
and the improvement comprising, in combination with the fore-
going:
(d) first means including conduits connected to said
second units for delivering a first flow of said first fluid
' phase containing said materials from a source thereof and
. passing said flow in countercurrent exchange with said impover-
s ished second fluid in a first delivery-to-discharge path through
~ a portion only of said second unit proximate to its end at .
~ which said fluids are most impoverished in said first material, and
'd (e) second means comprising conduits connected to
. 20 said units for passing a second flow of first fluid phase in a
~ second delivery-to-discharge path exclusive of said first path
in counterucrrent exchange with said second fluid phase in other
.. A portions of said first unit and second unit of said pair of units
and as an enriched flow between said units.
~ The present invention provides in an integrated system
!
.~ for concentrating a desired material exchangeable between two
:;~,, ,
separate fluid substances containing said material and another
material exchangeable therewith, at least one of said fluid
:~j substances being in liquid phase, said system including
(a) a first enrichment section comprising a first stage
. operating system hauing at least one pair of dual temperature
;
exchange hot and cold towers and a prescribed feed supply of one
. .
-- 8 --
', : ' ' ,~: '
~06Z606
of said fluid substances,
(b) an intermediate enrichment section comprising
an operating system of at least a second stage of dual
temperature exchange hot and cold towers, and
~c) a final enrichment section comprising a system for
further enriching at least one of the enriched fluids from
said intermediate enrichrnent section to a prescribed final
product concentration,
the improvement which provides for modification to increase the
quantity of final product output without physical alteration of
~; the intermediate and final enrichment sections, wherein
(1) the hot and cold towers of the first enrichment
section include countercurrent contact exchange elements
sufficient to provide that when the volume of enriched fluids
withdrawn from said first enrichment section and delivered to
, j/J7/ern7ed/~ 7~
sald~enrichment section is fractionally reduced, such reduced
quantity will transport to the intermediate enrichment section
substantially the same amount of the desired material at an
increased concentration, and
(2) the final enrichment section is of sufficient
capacity to produce a final product of the prescribed concentra-
tion when said volume of enriched fluids delivered to said
i~7ter~e~ e
sccend enrichment section is not so fractionally reduced.
In the accompanying drawings: -
, Fig. 1 is a simplified diagram of a typical prior art
arrangement of the hot and cold towers Tl and T2 of a single
stage dual temperature exchange system or of the first or a
following stage of a plural stage dual temperature exchange system
wherein: the fluids between the towers are enriched in the
desired material; the inter-tower fluids processing system, e.g.
pumps, valves,heating and cooling means, with or without addition-
al concentrating means, is indicated by single brackets for
: ~ _ g
.
:'',
1~260~;
simplicity; and tne withdrawal of product fluid Lrom the
system is indicated by the arrow P;
Flgs. 2 through 8 are slmilar diagrams of systems
employing various typical embodiments of the invention;
Figs. 5a and ~a are similar diagrams of modified
physical embodiments of the systems of Figs. 5 and 8, being
,
~ the same as Figs. 5 and 8 above the planes A-A and B-B,
`` respectively;
Figs. 9 and 9 (alt), are abbreviated and extended
process flow diagrams of the same first stage of a system accor~
ding to the invention, in which the hot and cold towers may be
a single given diameter tower or a plurality of lesser diameter
towers in parallel, such parallelism being indicated in Fig. 9
by the bracket-like "gang" symbols, indicating that allpartsbetween7
:,
. .
... . . .. .. .
. . .
:'
.;", .
: , ,
'"
~I ~
.~ .
'''
~ .~
.: :. ~ , . ~ ~ . . .
:, ; . .
- - . . : .
; .. . . . . . . : - . ,
,;,', . .: : - : . - : , .
: ~. . , : , . -
, ,- : . . ~ . : :
106Z606
the oppositely facing brackets may be present in multiple
parallel relation, as more completely illustrated in Fi~. 9
~alt~; and
Fig. 10 is a similar process flow diagram of the
second and third stages of an enrichment system, which may be
fed from, and dischar~e to, the first stage of Fig. 9 or 9(alt);
and may in turn feed, and receive discharge from, further con-
centrating and product finishing stages, which may be as set
forth in any of my aforesaid prior patents.
Referring to the drawings, as above noted, Fig. 1
is typical of the prior art systems using the dual temperature
process, wherein enrichment of the desired material by counter-
current direct contact exchanges between a feed supply fluid
and an auxiliary fluid is effected. The feed supply fluid ,t
(e.g. water) is delivered at al to the tower Tl which is kept
a~ a temperature (e.g. cold) to effect enrichment of the feed
supply fluid and impoverishment of the auxiliary fluid AFl
(e.g. H2S) in a desired material (e.g. deuterium) and thence
passes via bl to the intertower fluids processing system cl
from which the product P is withdrawn and from which the main ¦feed supply fluid flow passes via dl to the tower T2 which is
kept at a temperature (e.g. hot) for impoverishment of the feed
supply fluid and enrichment of the auxiliary fluid, and thence fdischarged at el. Thus both fluids passing from the towers to
the system cl are enriched in the desired material. In Fig. 1,
assuming the fluids concerned are liquid water and gaseous
hydrogen sulfide, and that the water is the feed supply fluid, ~ -
the solid line flow path would indicate the water and the broken ¦~
line flow path would indicate the auxiliary fluid. With the same
~ 30 fluids, if H2~ were assumed to be the feed supply fluid, and
- water the circulating auxiliary fluid, then the significance ofthe solid and broken lines would be reversed, with corresponding
-- 11 --
106Z606
reversal of the ends and temperatures of the towers Tl and T2.
In Fig. 1, the valve symbols, fl~ gl and hl, are included to
indicate that the auxiliary fluid may be recirculated in full
` or in part or not at all, between the towers, depending on the
particular species of system being employed and whether the
illustrated stage is a single stage or the first or subsequent
stage of a system.
The quantity of the desired material which may be
extracted from the feed supply fluid in a system according
to Fig. 1, is limited (in the ideal case) according to the
following relationship: Q = (l-Kl/K2), where Q is the maximum
fraction of the desired material in the incoming feed substance
which may be extracted, Kl is the equilibrium distribution of
the desired material between the phase comprising the feed
; substance and the phase comprising the auxiliary substance at the
first temperature zone conditions, and K2 is the e~uilibrium
distribution between said phases at the second temperature zone ¦
conditions.
Fig. 2 illustrates a first embodiment of the present
invention which is particularly useful where the character of
the feed supply fluid would impose costly requirements for the
apparatus, i.e. for expensive materials of construction of the
parts in contact therewith, e.g. where said feed supply is a
corrosive solution such as sea-water. This embodiment minimizes
, the area of such contact, confines the said feed supply fluid
to such minimized area, and prevents mixing of said feed supply
-~ fluid with other process fluids of the system except in such
confined area. To this end, in the embodiment of Fig. 2, the
feed-to-disposal path ~is confined to the lower portion only
of the tower T2, entering the same via a2 at a level below the
partitioning device s2 extending across the tower which permits
passage only of the auxiliary fluid AF2, the other fluid
-- .
1062606
exchanging with the auxiliary fluid AF2 in the upper section
of tower T2, being withdrawn from above the partitioning device
s2 for recirculation through the tower Tl via conduit m2. In
this Fig. 2 embodiment if a secondary non~corrosive feed supply
source is available (e.g. essentially pure water or water free
. .
of corrosive contaminents) a feed F therefrom may be added to
the fluid being recirculated via m2, as indicated by the valve r
j2 in line a 2, in which case an amount equivalent to that added
will be withdrawn from the circulation, as via the conduit with
valve k2. This withdrawn quantity, as shown, may be combined
with the primary feed supply fluid supplied at a2, and may pass
I therewith through the lower part of the tower T2 and to discharge
:~ via e2. When the total flow of feed fluid phase passing through
the lower part of the tower T2 to discharge D is greater than
the flow thereof passing through the upper part of tower T2, the j~
augmenting by the combination of the flow of feed fluid phase
improves the efficiency of the lower portion of the tower T2
by making available for exchange with the auxiliary fluid phase
a larger quantity of the desired material (e.g. deuterium).
20 The valves f2, g2, and h2 have the same significance in this
L
figures as do the correspondingly lettered valves in Fig. 1. ~ ;
Thus by this combination a greater productivity may 1~ -
be obtained with a given tower size, and/or for a given pro~
j ductivity the relative size of the lower section of the tower T2
~, may be reduced. Except when otherwise stated, the descriptions
;~ herein refer to steady state conditions.
In a modified mode of operation of the system of Fig. 2,
t' ' the flow of the secondary non-corrosive feed supply fluid phase
through the lower portion of tower T2 may be eliminated ~e.g. by `- -
. 30 closing the valve k2), the introduction of the secondary feed
fluid may be effected in the section c2 ~e.g. by condensation of
feed supply fluid vapors from the auxiliary fluid flow therein),
-- 13 --
. . .. - ~ . . : : :
:. . : ,
10f~ ;06
and in such case the excess of secondary feed fluid phase
delivered f~om tower T2 by way of conduit m2 over the quantity
thereof to be introduced into the tower T1, may be discharged
from the system by way of conduit a'2 controlled by valve j2.
The embodiment of Fig. 3 is quite similar to that
of Fig. 2, and includes corresponding parts designated by
corresponding letter symbols with the ascribed symbol "3".
As again, the primary feed supply fluid may be confined to the
lower portion of the tower T2 between a3 and e3 and may contact
the auxiliary fluid AF3 only therein, the auxiliary fluid AF3
partially enriched by this contact, then passes through the
segregator s3 and contacts the secondary feed supply fluid in
the upper portion of the tower T2 and in the other portions of
the system. In this Fig. 3 arrangement, the secondary feed
supply fluid enters the stage at a 3, this feed supply fluid
` phase leaving tower T2 via m3 may be delivered from the stage,
as through valve n3, or may be combined with the primary feed
supply fluid by way of valve k3. When the primary and secondary
feed supply fluids at a3 and m3 have the same concentration of
the desired material, and have the same flow rates, then the
system of Fig. 3 will effect er.richment in substantlally the same
manner as that of Fig. 1, with the improvement that the primary
feed fluid from a3 is confined to the circuit a3-e3, and (in
the case of sea-water, for example) does not contact other parts
of the apparatus. In this embodiment also, when the flow from
a3 to e3 is in greater ~uantity than that through m3, an increase
in efficiency of the por~ion of the tower below the separator s3
is obtained.
The embodiment of Fig. 4 is adapted for use under
conditions in which the primary feed supply fluid entering at
a4 is of a quality comparable with that of the secondary feed
supply fluid introduced at a'4, and in this case no segregator
- 14 -
1(~6Z606
corresponding to the separator s3 is required. Thus in this !
instance the primary feed supply i5 introduced directly into
the tower T2--through a conventional distributor (not shown)
to prevent channelling--and augments the flow of feed fluid
phase in the lower portion of the tower T2 for improving the
efficiency thereof. In this instance, the flow in the lower
portion of the tower T2 is essentially equal to the sum of the
flows in a4 and a'4, and the amount of feed fluid phase intro-
duced through a4 may be varied up to several times the quantity
supplied at a 4, in accordance with the degree of augmented flow
desired in the lower part of the tower T2 and the capability
I of the contacting equipment to accommodate the fluid flows,
bearing in mind that the fluid exiting at c4 may not become
impoverished to less than the equilibrium value determined by
the concentration of the auxiliary fluid AF4 entering the tower
T2, and that the auxiliary fluid AF4, when it reaches the level
a4, cannot have attained a concentration greater than that
corresponding to equilibrium with the feed supply fluid phase
at that level. '
; 20 The embodiment-of Fig. 5 is similar to that of Fig. 2
but the lower portion of the tower T2 is divided into separated
parallel sections x5 and y5, in which the two feed supply fluids 1,~
are separately contacted with branched parts of the auxiliary
fluid`AF5, which parts are then combined above the separator
s5, the primary feed supply fluid from a5 being confined to the
region within x5 by the separator s5. By this arrangement,
impoverished secondary feed supply fluid which has entered the
system either by way of a 5 or otherwise, e.g. by condensation
; from the auxiliary fluid AF5 in the systems c5, may be withdrawn
via r5 (at minimum concentration of the desired material, e.g.
equal to that in e5), for appropriate use, e.g. for precondition-
ing the auxiliary fluid AF5 by use of heating and humidifying
- 15 -
106Z606
provisions as set forth herein and in the patents above.
The same result as that accomplished in the embodimel-t
of Fig. 5 may be attained with the modified construction of
Fig. 5a wherein all parts above the plane A-A are the same
as those above said plane in Fig. 5, and the corresponding
parts below the plane are designated by corresponding letter ~ -
symbols with their own ascribed designations. This Fig. 5a
construction is desirable, especially where the flow r5a is a
minor quantity as compared to the flow e5a. The valved by-
pass q5a is provided for the purpose hereinafter described
in connection with Fig. 9; and may be provided for corresponding
flows in the other embodiments.
Fig. 6 illustrated another modification of the system
', of Fig. 1 the use of which is particularly advantageous where
1 the available supply of the feed substance is restricted and/or ~ ,-
where the cost of treatment of the feed supply for use in the
system is significant. By extending the exchange path of the
circulating auxiliary substance in both of said different temper-
ature zones and by recirculating a portion of the fluid phase
, 20 comprising the feed substance through said exchange path
according to this modification it is possible to increase the t
.,.~ , j' '.
fraction of the desired material which may be extracted from ~ -
the feed supply over that afforded by the system of Fig. 1.
In the embodiment of this improvement as illustrated
in Fig. 6, a fluid phase comprising the supply of feed substance
~;i is passed in a feed-to-disposal path (F-D) through both said
3 different temperature towers Tl and T2 in countercurrent contact
:;~
exchange relation to the auxiliary fluid phase AF6, said path
traversing at least a part of the first temperature tower Tl
for enriching the feed substance in said desired material and then
the second temperature tower T2 for depleting the so enriched
J
.; ,
- 16 ~
1(~6~606
feed substance of said desired material; said supply of feed
substance i9 delivered to tower Tl; and said feed fluid phase
leaving the second temperature tower is divided, a part thereof
being recirculated via m'6 to said first temperature tower Tl,
said recirculated feed fluid phase traversing the entire counter-
current contact exchange path of said auxiliary substance in both
of said different temperature towers. In the preferred embodiment
of this modification, said supply of feed substance is delivered
to said first temperature tower from a6 via valve j'6 and is
10 mixed with said recirculated feed fluid phase from m'6 at the
place where the concentration of the desired material in the feed
fluid phase in tower Tl is partially enriched to about the same
concentration of the desired material as that in the feed supply
fluid delivered via a6.
The fraction of the desired material which may be
extracted from the feed supply fluid from a6 by use of this
modification is independent of the limltations of the system
of Fig. 1 and is expressed substantially by the following
relationship: Q = (l-Xw/Xf), where Q is the fraction of the
desired material in the feed substance supply which may be
Z extracted, Xf is the concentration of the desired material in
.~ . !
the feed substance supply, and Xw is the concentration of the
desired material in the feed substance which passes from said
second temperature zone. Variation in prescription of the
fraction of the desired material to be extracted is reflected
in variable apparatus requirements as effected by the ratio
of the quantities of feed substance recirculated via m 6 and
~:. I
feed substance supplied to the system via a6.
.,~ ,
In an alternative to the preferred Fig. 6 arrange- ¦
ment, the feed supply fluid from a6 may be commingled with
the more impoverished feed supply phase fluid recirculating
via m 6, and both these fluids may be introduced into the
- 17 -
~6Z6~6
top of the tower Tl. While this arrangement may be advantage-
ous in certain circumstances, it is not wholly independent of
the limitations of Fig. 1, above discussed, and in effect is a
compromise between the Fig. 1 arran~ement and that of the pre-
ferred embodiment of Fig. 6.
~s is also illustrated in Fig. 6, when the auxiliary
fluid recirculation AF6 is provided with a feed for additional
auxiliary fluid partially enriched in the desired material as
compared with the recirculated portion AF6, it is preferred to
; 10 introduce the latter by way of valve h'6 to the level in the
tower T2 where the fluid AF6 has been partially enriched to
substantially that of the added supply of auxiliary fluid.
However, with less independence from the limitations of Fig. 1,
such added auxiliary fluid may be introduced through valve h6
to be mixed with the recirculated fluid AF6 before it enters the ii
tower T2. In either embodiment a quantity of the auxiliary fluid,
equivalent to that added, is withdrawn as via valve g6.
The embodiment of Fig. 7 combines advantages of those
of Figs. 6 and 4, i.e. it affords the advantages of augmented
flow of feed supply fluid in the lower portion of tower T2, with ~,
the advantage of recirculation of feed supply fluid via m 7 and 6;
introduction of secondary feed supply fluid via j'7 to a point t
of substantially equal concentration in the tower Tl. ~'
; The embodiment of Fig. 8 combines advantages of the
embodiment of Figs. 7 and 5. The auxiliary fluid AF8 circulates
through the entire extent of the towers T2 and Tl . The feed
' supply fluid path F-D is confined to the tower portion x8 by the
separator s8, and the flow of auxiliary fluid AF8 is branched i;~
and divided between the tower portions x8 and y8. The feed supply
fluid phase passing in tower T2 is in part recirculated via m8
.~ i,
between levels in towers T2 and Tl, where its concentration is ,~
substantially equal to that of feed supply a8 which is greater
r
. .
106;2606
than the concentration of the feed supply fluid phase in r8
and e8, and in other part passed throuyh the tower portion y8.
The more impoverished feed supply fluid phase thus obtained from
r8 is recirculated via m'8 to the top of tower Tl, wherein it
is partially enriched to the concentration of the secondary feed
supply, which is introduced via valve j'8 if available and used,
in which case substantially the same quantity of feed fluid ~-
phase is withdrawn from the recirculation via k8 or via u8.
The same result as that accomplished in the embodiment
of Fig. 8 may be obtained with modified constructions, e.g. as ~h
exemplified in Fig. 8a, wherein all parts above the plane ~-B
are the same as those above that plane in Eig. 8, and the '~
corresponding parts below that plane are designated by corres-
ponding letter symbols with their own ascribed designations.
This Fig. 8a combination locates the tower portion x8a externally
of the main tower T2 leaving the lower part of the main tower
T2 for portion y8a. This arrangement is desirable especially
when the flow e8a is to constitute only a minor amount as com- ~i
pared to the flow r8a. The withdrawal to m8 in Fig. 8a is from
a suitable collector s'8, which separates that part of the fluid
phase to be withdrawn from the other contacting phase in the
tower. It will be appreciated that instead of locating the
tower portion x8a externally, it may be located internally of
the main tower and the tower portion y8a may be located ex~er-
: nally following the scheme of y5a in Fig. 5a, and that the structure
schemes of Fig. 5a or 8a may also be applied to any of the
embodiments of Figs. 2, 3, 5 and 8 hereof.
In Fig. 9 -- or Fig. 9 (alt) -- there is shown the
process flow diagram of the first stage of a system according
to the invention, in which the hot and cold towers of the pair
are each made up of a plurality of lesser diameter towers in
parallel, such parallelism in Fig. 9 being indicated by the
19 ~
.. ,- . . - - - , :
- . . . . . . .
;Z606
bracket-like "gan~" symbols, indicating that all parts between
the oppositely facing brackets may be present in multiple
parallel relation, as more completely illustrated in Fig. 9 (alt).
These figures and Fig. 10 illustrate the first, second
and third stages of a heavy water plant of the dual temperature
hydrogen sulfide water-type, embodying the invention. Such
heavy water plant comprises a feed and effluent treatment section,
which provides a treated water, e.g. sea-water which has been
cleaned, deaerated, decarbonated, heated, and saturated with --
hydrogen sulfide at the hot tower temperature and pressure,
e.g. 130 C and 325 p.s.i., and thereby also provided with a
dissolved salt component of hydrosulfide and sulfide ions. As
shown in Fig. 9, this feed-water is delivered by pipe 55A to the
feed section lower portion of the hot tower, corresponding to
portion X5a of Fig. Sa above, from which the effluent sea water~
impo~erished in deuterium content, is discharged via pipe 34A
to the effluent treatment section of the system above mentioned,
wherein heat is recovered from the effluent for in part heating
., I
the said feed water being supplied via pipe 55A, and dissolved
hydrogen sulfide gas is recovered from the effluent and return-
ed via pipe 42A for reuse as auxiliary fluid in the system.
Still referring to Figs. 9 and ~ (alt), since the
~ first stage equipments are duplicated in parallel, only one of
.~
them need be described. This one comprises cold tower TC-101-2
" and hot tower T~-101-2, with accessory equipment. Between the
cold and hot towers is a dehumidification system, shown as
constructed integral with the cold tower, wherein water is
condensed and heat is recovered from the hot H2S gas, the heat
recovery being effected at a plurality of consecutively lower
temperatures by separate branches of a cyclic flow of water and
condensate hereinafter more fully described.
The enrichment systems shown in Fig . 9 or 9 (alt) and
:
,, ~ . . . ` ,, ~ ! ` . , -
. ': : , ` ` ' ` - ` '
.- ~ . ' , .
':`
lg6~606
10, are those directly involved in the initial concentration
of deuterium ox1de in natural water e.g. sea-water, from about
0.015 mol % to approximately 7 mol percent, as D~O, when
provided with the two parallel stage 1 hot and cold tower
pair units as shown in Fig. 9 (alt); and to approximately
15 mol percent when four such parallel units are provided.
Stage 1, Figs. 9 and 9 (alt), contains a set of towers, F
or a plurality of sets of towers operating in parallel. Each
; set consists of a hot tower TH-101-2 operating at the hot
temperature, e~g. 130 Cr a cold tower TC-101-2 operating at
the cold temperature, e.g. 30 C, and a recycle tower T-102-2
which corresponds to the lower hot tower section ySa in Fig. 5a.
Inside all towers are countercurrent contacting elements, e g.
perforated plates called sieve trays, which provide intimate
countercurrent contact of the liquid and gas streams. Each set
of towers operates with its own H2S compressor, C-101-2, process
water pumps, heat exchangers and gas separators, as shown.
` The said stage 1 cold tower vessels in this embodiment
are vertical pressure vessels approximately 20 feet in diameter L
and approximately 185 feet high. Each said vessel comprises,
in the form shown, a cold tower or water enriching exchange
section and a dehumidification section for hydrogen sulfide gas
:, !
cooling constructed therebelow.
~he said stage 1 hot tower vessels are vertical
pressure vessels approximately 22 feet in diameter and approx-
imately 200 feet high. Each said vessel, in the form shown,
comprises a hot tower or water impoverishing exchange section
; which includes the sea-water feed section and the parallel
external recycle section; and a humidlficatlon section for gas
heating and humidifying is constructed in the lower part of the
vessel.
Each of the said exchange sections of the stage 1
.
- 21 -
1062606
hot and cold tower pairs in this illustrative embodiment, for
the purpose hereinaft~r described, is provided with a total of
130~ of the calculated number of plates that would be employed
if the illustrated two tower pairs in Fig. 9 (alt~ were to be
operated at output rates to effect a 3-fold enrichment of
deuterium content of the water delivered to the second stage
as compared to the sea water feed supply.
Seal trays are provided at the bottom and at the
top of the feed sections in the hot towers. As indicated in
connection with the separator sSa in Fig. 5a, gas can pass
upward through the seal trays, but water cannot pass through
them to the other sections of the tower. The feed section is
equipped with a mist eliminator and a wash tray (not shown)
to remove entrained sea-water spray from H2S process gas
ascending through the seal tray.
The stage 1 recycle towers T-102-2 corresponding
to elements y5a in Fig. 5a, are vertical pressure vessels
approximately ll feet in diameter and approximately 50 feet
high, provided with trays for countercurrent exchange between
the fluids as in the other sections of the towers.
All tower shells are made of carbon steel. The
hot tower sea-water feed sections are internally clad with
Inconel (trademark). All sieve trays are made of stainless
steel except in the hot tower feed sections where the trays
are also made of Inconel (trademark). The lower portion of
the hot tower, comprising the parallel feed section and recycle
tower section as shown, accounts for about 20~ of the total
number of theoretical trays or contacting elements in the hot
tower.
Gas from the top of stage 1 cold tower TC-101-2, via
41A, which also receives via 42A a stream of H2S from the
effluent system as above noted, passes via 38A from the discharge
- 22 -
' - ;
.
1~6Z6()6
of the stage 1 gas compressor C-101-2 to the bottom of the
humidification section of the stage 1 hot tower TH-101-2, where
it flows upward through the humidification section in counter-
current direct contact with a cyclic flow of hot water, and is
thereby heated and humidified by evaporation of ~Jater from said
cyclic flow. Steam injected via 114A into the hot tower at the
top of the humidification section further heats and humidifies
the gas to hot tower conditions. A portion of the hot gas is
withdrawn via 56A for use in the feed water saturator above
mentioned, where accumulations of inert gases are also purged
; from the process gas of the system. A minor portion of the so
heated and humidified gas via 58A is passed to the recycle
tower T 102-2, thereby bypassing the feed section of the hot
tower. This gas enters the bottom of the recycle tower and passes
upward, stripping deuterium from the countercurrent flow of
process water therein. This deuterium-enriched gas leaves the
top of the recycle tower and reenters the hot tower via 59A,
at the bottom of the process water impoverishing or deuterium r ~ ~ ,
stripping section, above the feed section.
Parallel to the recycle tower flow most of the heated
., ~
and humidified gas continues upward through the seal tray at
the bottom of the sea-water feed section of the hot tower and
through said feed section, stripping deuterium from the sea-
water feed. This enriched gas continues upward to the stripping
section through the seal tray at the top of said feed section,
mingling with additional gas recycled via 59A fromthe gas separa-
tors associated with the liquid heating elements of the system and
from said recycle tower. The gas stxips more deuterium from the
process water in the stripping section and then leaves the top
of the hot tower via 39A.
Said yas flow via 39A is split between the stage 1
cold tower and the stage 2 hot tower. One part thereof enters
the dehumdification section under the stage 1 cold tower via
- 2~ -
06
4OA and passes upward, becoming cooled and dehumidified by the
countercurrent cold water flows. The cooled, dehumidified gas
continues upward through the water enrichiny section of tower
TC-101-2, transferring deuterium to the process water therein.
Additional gas returning from the stage 2 cold tower, via ~lB,
Fig. 10 and 51A, Fig. 9, enters the bottom of the cold tower Ç
of stage 1 where it joins the gas flow from the dehumidification
section. The gas leaves the top of the cold tower via 41A, and
is returned to the bottom of the hot tower by the stage 1 gas
compressor C-101-2. 3
Feedwater (e.g. treated sea-water) is pumped from
the feedwater H2S saturate by pump P-003-2 and via 55A enters ?
the top of the feed section of the stage 1 hot tower~ and
deuterium is stripped therefrom by the countercurrent flow of
~ H2S gas passing therethrough. The deuterium depleted feedwater
: then discharges via 54A and 8A to the effluent treating system
referred to above. In the illustrative embodiment of Fig. 9
and 9 (alt) the quantity of sea-water delivered via 55A to the
feed section is about 115% of the quantity of process water
~0 delivered via 9A to the cold tower.
` A portion of the water discharged via lOA from the t~
dehumidification section below the stage 1 cold tower is pumped
by the hot tower feed pump P-108-2 to the top of the stage 1
- hot tower via llA. This water f lows downward in the hot tower,
transferring deuterium to the countercurrent flow of hot process
gas therein, and is thus withdrawn from the bottom of the strip-
ping section of the hot tower above the upper seal tray of the
feed section via 107A, and is split into three streams. The
main stream via 37A, 46A and 9A is returned to the cold tower
as process water. The second stream via 103A, 104A enters the
recycle tower. The third stream via 103A, 105A is ~elivered to
serve as wash water for gas entrainment elimination in the hot
i,
24
; ,~
,. :
~06Z60~;
tower feed section as a~oresaid, and then mixed with sea-water
feed supply. In this illustrative embodiment the total quantity
of water passincJ through the parallel sections of the lower
portion of the hot tower is almost 150~ o~ the quantity of
water passing through the cold tower.
The water entering the recycle tower from 104a passes t
downward, transferring deuterium to the countercurrent flow of r
hot humidified gas supplied via 58A, is discharged from the
bottom of the recycle tower, and is pumped by the pump P-106-2
via 102A to the top of the humidification section to provide
water for humidification of the gas recirculating from the cold ~`
tower to the hot tower.
Process water entering the top of the stage 1 cold
tower via 9A is supplied from process water withdrawn from above
r
the feed section of the hot tower via 107A as aforesaid. This
, water is pumped by pump P-105-2 via 37A through a recycle heat
.:, , ,- ,
exchanger train E-105- and two recycle coolers E-116- and E-106-
before entering at the top of the cold tower via 9A. It is t
joined by a recycled impoverished water s-tream withdrawn via 23A, ~`
24A, 113A from the bottom of the humidification section. This
. ~.,.
recycled stream not only serves to prevent the buildup of
dissolved salts from the water evaporation in the humidification
section, but also in part may provide means for effecting a re- ;~
duction in the concentration of deuterium in the fluids at the
.. ~ ~.
top of the cold tower and in turn at the bottom of the hot tower
whereby a greater degree of recovery of the deuterium from the
feed supply may be achieved as described above for the system
- of Fig. 8.
Another aspect of the present invention is the by-
pass pipe preceding the intake of the feedwater pump P-003-2
which extends thereto from the discharge pipe 8A for recycling
through the feed section all or part or none of the sea-water
'. ' , ,
.
5~ . -- : . ~ . . , " `
- - ' ' ' ' ' . : '~ . :
~06Z606
discharge via pipe 8A. Suitable valves for control thereof
are provided. Use of this by-pass is particularly advantageous
to avoid shutdown of operation of the entire system when the
feed supply becomes wholly or partially unavailable for delivery
to the system. Shutdown is costly in that the enriched fluids
in the towers drain and mix with the depleted fluids requiring
an extensive and costly period to resume operations and to
reestablish the steady state enrichment gradients in the towers.
Since both the sea-water feed and discharge flows to and from
- 10 the feed section are at substantially identical conditions,
except as to enrichment, no further treatment is required for
such recycling to maintain the entire system in stable operation,
inasmuch as the other flows of the process water and gas through
the towers comprise circulations operating independently of the
feed supply. In addition, the sea-water recycle provides ad-
vantages during normal operation of the system to effect an
increased extraction of the deuterium contained in the feed
- which may be utilized to increase the productivity of the 1
system or to reduce the quantity of sea water to be treated for
delivery to the system or both. Use of the sea-water recycle ¦~
serves to lower the concentration of the sea-water supply to
the feed section, which in turn reduces the enrichment attained
by the gas at the top of the feed section, which in turn effects
a greater impoverishment in the process water recycling from the
hot tower via 107A to the cold tower via 9A and in turn effects
greater impoverishment of the gas recirculating from the cold
tower to the hot tower, whereby the water discharging from the
bottom of the hot tower, e.g. sea-water from the bottom of the
..
feed section, is more impoverished with a resultant increase in
the extraction of deuterium per unit quantity of the sea-water
feed supplied to the feed section.
The relation of the by-pass preceding the intake
... .
,
~0~i260~i
of the ~eed-water pump P-003-2 corresponds to the valved by-
pass q5a shown in Eig. 5a.
The process water flows downward throuyh the cold
tower and is enriched with deuterium as it contacts the
countercurrent flow of deuterium enriched H2S gas therein.
This cold deuterium enriched water, mixed with the cooled
recycling water flows from 14A, 17A and 20A, is heated in
the dehumidification system below the cold tower and is dis-
charged therefrom,together with the condensate formed by
cooling of the hot humidified gas from 40A, via 10A. One
part thereof via llA is uassed to the top of the stage 1 hot
tower as heated process water; and a second part thereof via r
12A is passed to the branched heat exchanger train E-101-,
E-102-, E-103- wherein it is differentially cooled and returned
in the three streams 14A, 17A and l9A-20A to the levels of
corresponding temperature in the dehumidification section.
The water flows to the humidification section under
the hot tower TH-101-2 consist of the flow via 102A from the
recycle tower and the flow via 31A of circulated water of the
4 branches 35A, 3~A, 43A and 24A of the second cyclic flow ~!".' ' '
:~ r~ -
system, which branches are withdrawn from the countercurrent f;
,.~ - t
humidification section in three streams, upper, middle and
lower, by the pumps, P-104-2, P-103-2 and P-102-2.
, .
- The discharges from these pumps pass through the
indirect contact heat exchangers E-101-, E-102-, E-103- and
E-105- in differential series, as shown, to recover heat from
~I the above described branched cyclic flow associated with the
;' dehumidification section and from the process water being
recycled from the hot tower to the cold tower via 107A. In
the course of the heating in these several heat exchangers,
H2S gas is evolved from the water. The heated streams are
therefore passed through gas separators D-101-, D-102-, D-103-
2~ -
. .
~ . - , :
.
106Z6V6
and D-105- ~rom which the collected gas is returned via 59A to
the hot tower. Parts of the water in 35A, 34A and 43~ pass
to corresponding differential heat exchangers in stages 2 and 3
in parallel arranyement to those in stage 1, and the combined
heated streams return via 31A to the humidification section
below the stage 1 hot tower.
Deuterium enriched process water passing through the
dehumidification section from the cold tower TC-101-2 cools and
dehumidifies the countercurrent gas stream from 40A. The water
is withdrawn from the bottom of the dehumidification section
via lOA and a part thereof is passed, via pump P-107-2 and 12A,
to the heat exchanger means E-101- as above described. A portion
of the discharge from such heat exchanger means is returned to
the dehumidification section via 13A and 14A as the lower dehumid-
ification stream. The remainder passes via 13A and 15A through a
second heat exchanger means E-102- and a portion is delivered
via 16A and 17A as the middle dehumidification stream. The rest
of the dehumidification water via 16A and 18A passes through a J
third heat exchanger means E-103- and two coolers E-114-2 and
; 20 E-104-2. A portion of this water, via 20A, is passed to the
dehumidifier section as the upper dehumidifcation stream; the ,~
rest is pumped to the top of the cold tower of stage 2 via 52A
and 9B.
Stage 2, Fig. 10, operates with one set of towers;
a hot tower TH-201 and a cold tower TC-201. The stage 2 hot
tower is a vertical pressure vessel consisting only of a water
- impoverishing or deuterium stripping section. It is approximately18 feet in diameter and approximately 130 feet high. The cold
tower is part of a pressure vessel approximately 16 feet in
diameter and approximately 195 feet high which includes the
cold tower water enriching section over a hydrogen sulfide gas
dehumidification section. Both towers are made of carbon steel
2~
'-' ' ' : '
lQ62606
and use stainless steel sieve trays.
There are no sea-water feed sections or gas
humidification sections in stages subsequent to stage 1.
Hot humidified H2S gas from stage 1 via 38s supplies the process
gas for higher numbered stages.
Deuterium enriched H2S gas from the stage 1 hot towers
via 38B enters the bottom of the stage 2 hot tower and passes
upward therein stripping more deuterium from the countercurrent
flow of process water. The deuterium enriched gas leaves the
stage 2 hot tower via 39B and is split into two streams via 38C
and 40B. The flow via 38C passes to the bottom of the stage 3
hot tower TH-301; the flow via 40B is delivered to the bottom
of the dehumidifier section below the stage 2 cold tower TC-201.
The gas passes upward in this dehumidification section in
countercurrent direct contact with a branched cyclic flow of
cooling water and the water from the cold tower TC-201. In this
dehumidification section the hot gas from 40B is coo~ed and de-
' humidified and then passed into the cold tower where it merges
with the gas recycled from stage 3 via 41C. The gas transfers
its deuterium to the countercurrent flow of water and then
leaves the cold tower via 41B, from which it was pumped to the
cold tower of stage 1 by the stage 2 gas compressor C-201, via
51A, Figs. 9 and 9 (alt), above described.
Deuterium enriched process water from the stage 1
cold towers via 52A and gs is delivered into the top of the
stage 2 cold tower TC-201, where it becomes further enriched
by picking up deuterium from the countercurrent flow of process
gas therein. This deuterium enriched water enters the stage 2
dehumidification section where it mixes with the recirculating
branched flow of cooling water and with the condensate formed
from the cooling of the hot gas therein.
The heated water withdrawn from the bottom of the
., .
:
. .. ~ :
- . - . . .. .. .... .:
i~62~;06
stage 2 ~ehumidifier section via lOB is split into two streams,
one of which is pumped via 12B through branched circuits com-
prising heat exchanger means E-201, E-202, E-203 and is returned
at differential temperatures to corresponding temperature levels
of the stage 2 dehumidification section via 14B, 17B and l9B-
20B; the other being pumped by the pump P-208 to the stage 2
hot tower via llB.
Process water recycled ~rom stage 3 via 23C joins
the process water stream from llB to the top of the hot tower
TH-201 and these combined streams flow downward in the tower TH-
201 and are stripped of deuterium by the countercurrent flow
of H2S gas therein. The process water is discharged from the -
bottom of this hot tower via 23B and is returned to the stage 1
hot towers by pump P-201.
The greater part of the process water withdrawn
via lOB from the dehumidification section at the bottom of the
stage 2 cold tower is recycled via 12B. This water is cooled
and introduced into the dehumidification section below the cold
tower TC-201 in three streams, as above described. In more
detail, the pump P-202 pumps the water via 12s through the heat
recovery exchanger means E-201, cooling the water. A portion
of the so cooled water via 13B and 14B passes to the dehumidifi-
cation section as the lower stream thereto; the rest is pumped
by the pump P-204 to the heat recovery exchanger means E-202,
and a portion of the further cooled water therefrom via 16B and
17B becomes the middle dehumidification steam; the remainder
thereof via 16B, 18B passing through heat exchanger means E-203
and thence through two coolers E-214 and E-204. A portion of the
stream of cold water from E-204 passes via pump P-303 and 9C to
the top of the stage 3 cold tower TC-301 as process water; and
the remainder enters the top of the stage 2 dehumidification
section via 2OB.
- ~ 30 -
- : , , .~ . .
- : - i ~
106:2606
Stage 3, following stage 2 in Fig. 10, is essentially
a repetition of stage 2 operating at a higher degree of enrich-
ment and with relatively smaller volumes of fluids in correspond-
ingly smaller apparatus, and the arrangement of the like ele-
ments of stage 2; the items of equipment being designated by
the same reference numerals in a "300" series as compared to
those in a "200" series in stage 2 and a "100" series in stage 1;
and the corresponding piping of the stages being designated by
like numerals but with the ascribed "C" for stage 3, "B" for
stage 2, and "A" for stage 1.
As indicated in connection with the stage 3 diagram,
Fig. 10, this stage may be followed by one or more further
enrichment stages. As there indicated such may be of the dual
temperature exchange type employed in the earlier stages, but
;~ the invention is not limited in this regard and further enrich~
, ment may be effected in any appropriate way. Since the stages
t
herein described may effect some 500 to 1000 fold enrichment
representing more than 90% of the total capital and operating
costs to achieve a final product concentrate of 99.8 mol percent
D2O, the type of system utilized for the final enrichment whether
it be of any of the known dual temperature types, water distill~
ation types, or electrolytic types, or combinations thereof, is
not of major importance and forms no part of the present
invention.
Another aspect of the present invention indicated in
Figs. 9 and 10, resides in improvements which enable a multiple
stage plant to be established for the production of final product
at one rate, e.g. 200 tons per year, with provision for a reduct-
` ion or expansion of its capacity by addition or subtraction of
: ~ .
parallel first stage hot and cold tower pair systems, withoutneed for altering the volumetric equipment in the following
. .
stages.
. . .
- 31 -
,
. . :
Z606
In Figs. 9 (alt) and 10, the illustrated stages
comprising a first stage having two identical parallel tower
pair systems and second, third and fourth stages of one pair
each are capable of enriching material sufficient to yield 200
tons per year of final product; by effecting a 3-fold enrich-
ment of the deuterium content of the process water delivered
via 9B (Fig. 9 (alt) and Fig. 10) to the second stage cold tower, t
as compared to the sea-water feed entering the first stage via
55A; followed by a further 9-fold enrichment in stage 2, a
further 16.2-fold enrichment in stage 3, leaving only a 16.1
fold enrichment to be imparted by the final enrichment system
to achieve the approximately 7,000-fold enrichment constituting
the final product.
According to the expansion concept of the present
~ invention, by adding two additional sets of stage 1 sections
; connected between the "gang" symbols of Fig. 9, and maintaining
the same total volume flows from stage 1 to the following stages,
i.e. halving the volume flows from each of said tower pairs
of stage 1 to the second stage, the former 3-fold enrichment in
the first stage is increased to a 6-fold enrichment, without
adding any additional equipment in the subsequent stages. To
achieve this result the tower pair sections of the first stage
are constructed with sufficient trays in the hot and cold towers
to accommodate a 6-fold enrichment at half the contemplated
volumetric withdrawal rate of fluids to the second stage, and
`' until such time as the third and fourth parallel sections are
installed, the withdrawal rates from the first and second
parallel sections are set at twice the rates contemplated for
the 6-fold enrichment, thus delivering four units of volume at
30 3-fold enrichment rather than two units of volume at 6-fold enrich-
ment, at a nominal sacrifice of optimum tower efficiency. Thus
when the third and fourth ganged sections are installed, the
_ 32 _
~06;2606
total withdrawal to the second stage previously supplied from
two first stage sections, is divided between the four first ~'
stag~ sections, thus reducing the withdrawal rate per section
to that at which each section affords a 6-fold enrichment at
full efficiency as originally contemplated. When gas is
transferred between the first and second stages as shown, jl
the reduced withdrawal of gas from the individual sections ~ -
of the first stage results in about a 25% increase in the gas
flows in each of the dehumidifying sections below the cold towers
of the first stage. Thus when third and fourth tower pair units
are added, the heat recovery exchangers E-101-, E-102-, and ¦~
E-103 , have their capacities increased proportionately by
added parallel units thereof as indicated at XE-101-, XE-122-,
and XE-123-, with similar increase in the coolers E-114- and
E-104- as indicated at XE-124, to condition the increased gas
flow.
Conversely, with the first stage consisting o~ ¦
"ganged" parallel sections it becomes possible to shut down
for maintenance, or otherwise, less than all of the "ganged"
sections of the first stage, provided the ultimate size of 5
` the final enrichment treatment (by whatever method) is con-
structed to accommodate substantially the same volume of input, 5
but at a reduced concentration proportionally corresponding to
the minimum concentration to be delivered to the second stage
from the first stage at such time. In light of the quite small
quantities of fluids to be handled by the final enrichment
system for the ultimate product, the cost of providing it with
such capability is essentially nominal. With such arrangement
. the enrichment multiplication factor of the intermediate stage-s
. I
remains substantially constant with constant volume total input
~ from the parallel first stage sections and constant volume output
;; to the final enrichment system. Also with this arrangement,
:'
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I .,
-
1062606i
during such partial shutdown there is no need to reduce the
extra capacities of the heat recovery exchangers XE-101-, etc.,
as the excess capacit~ thereof actually increases the overall
efficiency of the heat recovery system in such circumstances,
with consequent reduction in the quantity of steam required
to be supplied via 114A.
Thus by this improvement of the present invention the
limited additional capital investment of 25%, more or less,
of the exchange portions of the hot and cold towers of the
first stage only of the initial plant, with no significant
added investment in any other part of the initial plant,
provides a plant which can be expanded to double its initial
product output capacity at only a fraction of the cost of
duplicating a plant without such improvement; and similar
; advantages may be obtained in other embodiments of this invention
contemplating other capacity expansions, e g. from a single pair
of first stage towers to two, three, four or even more pairs
thereof as contemplated by the "gang" symbols in Fig. 9, for
which purpose, the extra plates required to be installed in the
initial plant to provide for multiplications of the enrichment
by stage 1 in such proportions progressively decrease as the
. .
degree of enrichment increases.
As an alternative of this aspect of the invention, the
tower units of the initial construction may be constructed with-
out the additional plate capacity, and may be extended by the
connection of further tower sections in series therewith to pro-
vide said additional capacity at the time the further first stage
- tower units are connected in parallel therein.
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~ '
34_
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