Note: Descriptions are shown in the official language in which they were submitted.
2 ~ i~ 7 ~ ~ ~
Process and appar~tus for decaffeindting l~qu~d,
especlally aqueous raw coffQQ extracts
D e s c r 1 ~ t ~ o ~ :
The invention relates to a process for decaffeinating
liquid, especially aqueous raw coffee extracts, in which
the caf-feine is adsorbed from the extract by means of an
adsorbing agent. The invention further relates to an
5 apparatus for decaffeinating liquid, especially aqueous raw
coffee extracts.
Different decaffeination methods are already in frequent
use. Decaffeination can for example be conducted with
0 activated carbon acting as an adsorbing agent for caffeine.
For this purpose, the activated carbon has to be pretreated
in a specific way to obta~n the required adsorbing pro-
perties. In such a decaffeination process, an aqueous raw
coffee extract is usually prepared and then contacted with
the pretreated activated carbon for decaffeination.
- 2 ~
Such a decaffeination process is relatively complicated and
expensive, especially because of the pretreatment of the
adsorbing agent.
s The invention is therefore based on the object to propose a
process for decaffeinating raw coffee extracts, which can
be conducted in a more simple and economical manner. Accord-
ing to the ;nvention, this object is attained, ;ndependent-
ly of one another, by the features of cla;ms 1 and 19.
An apparatus accord;ng to the ;nvention for decaffeinat;ng
l;quid coffee extracts, preferably for conducting the pro-
cess according to the invention, is character;zed by the
features of claim 19.
For the process accord;ng to the ;nvent;on for de-
caffeinating raw cofFee extracts, a molecular sieve is used
wh;ch ;s selective for caffeine. In an adsorption process,
an extract of the coffee which is to be clecaffeinated is
20 contacted with this molecular sieve. The process according
to the invention furthermore advantageously provides that
the adsorbing agent is regenerated, especially by being
liberated from the adsorbed caffeine, so that the adsorbing
agent is re-usable for a following adsorption process.
Suitable adsorbing agents are molecular sieves, especially
zeolites and particularly Y-zeolites. It is of advantage to
use an aqueous raw coffee extract with a caffeine content
of approxirnately 5 9/1.
The decaffeination process according to the invention is
particularly economical to conduct, because practically no
adsorbing agent is used. Instead, the adsorbing agent
employed according to the invention is reprocessed after
35 the decaffeination of caffeine, so that it can be used
almost indefinitely.
-- 3 --
The adsorb;ng agent is regenerated by being liberated from
the adsorbed caffeine. This desorbed caffeine can be
isolated as a by-product of the decaffeination process
according to the invention and can for example be used in
5 pharmaceutical products. This also reduces the costs of the
decaffeination process according to the invention in an
expedient way.
In the process according to the invention and according to
o preferred embodimentsl the adsorbing agent can be re-
generated at low costs, since the desorbing agents are
easily and cheaply obtainable and the expenditure con-
cerning the required apparatus installation is low.
15 Preferably, the adsorbing agent charged with caFfeine is
first rinsed with an eluting agent, for example with water,
to elute extract constituent substances - apart from
caffeine - i.e. coffee residuals. The eluate obtained there-
with con-tains extract constituents and can be used as a
20 swelling agent - which also reduces the costs - for pre-
swelling or extracting raw coffee beans, so that the
aqueous coffee extract which is to be decaffeinated can be
economically prepared with this eluate.
25 After eluting the non-caffeine-constituents from the
molecular sieve, the caffeine is desorbed from -the
molecular sieve. For this purpose, a desorbing agent pre-
ferably composed of 80% alcohol and 20% water is expedient-
ly used. Passing the desorb;ng agent through the charged
30 adsorbing agent results in a solution of caffeine in the
desorbing age~t. The desorbing agent and the caffeine can
be separated to a large extent by d;stillation, so that the
desorb;ng agent can be re-used for further desorption pro-
cesses and ca~feine or aqueous caffein solution remains.
According to a further feature of the invention, desorption
of caffeine ;s followed by a clean;ng step, in which
residuals of the desorbing agent are displaced From the
~ ~ ~ 7 ~
- 4 --
adsorbing agent by means of a cleaning agent, preferably
water or water vapor. Since the desorb;ng agent preferably
also contains water, the desorbing agent and the cleaning
agent can preferably be distilled off in a common
5 distillation process and be separated from the caffeine for
reclaiming the desorbing agent and separating an aqueous
caffeine solution.
The essent;al processes o~ the method according to the
o invention are preferably conducted at a temperature ranging
from between 50 and 100C, for example at about 75C.
~hen such an adsorbing agent is used, a pretreatment of the
adsorbing agent, especially with regard to the selective
15 adsorptive capacity for caffeine, is advantageously not
requ;red. Consequently, the decaffeination process
according to the invention can be conducted in a more
simple and economical way in this regard as well. Moreover,
a molecular sieve can be used for a particularly long
20 period by way of reprocessing same. Furthermore, the
adsorbed caffeine can be desorbed ;n a simple manner and
with cheap desorbing agents.
The decaffeinating process or processes according to the
25 invention are thus particularly economical. Moreover, the
process according to the invention can be automatized and
conducted continuously in a particularly simple manner.
Separate protection is additionally claimed for a preferred
30 embodiment of the decaffeinating process according to the
invention in which the process stages of the process are
conducted in steps which are separate as regards the
apparatus and are preferably identically designed. It is
particularly advantageous to use individual steps or groups
35 of one or more steps simultaneously with adsorbing agents
for difFerent process stages, but with each individual step
passing in chronological succession through different pro-
cess stages. The individual steps or groups of steps are
- 5 -
preferably passed to the same respective process stage in
cyclic continuation.
This means that an adsorption process can expediently be
5 conducted with some of the steps while simultaneously the
adsorbing agent of the other steps is reprocessed. And the
steps working in the reprocecessing stage can be in
different phases at one time, for ;nstance some of them in
the eluting phase, some in the desorbing phase or the
o cleaning phase. Each of these steps passes through all
existing stages in chronological succession.
If several steps are used in the same process stage, for
example a group oF steps in the adsorption process, pre-
15 ferably not all of these steps are passed to a followingprocess stage simultaneously, but rather in succession. It
is for example preferred to use ten steps out of sixteen
steps simultaneously for adsorption. As the adsorption
process continues, only one of the ten adsorption steps is
20 taken out of the adsorption process and transferred to the
reprocessing stage. This removed step is then replaced, pre-
ferably cyclically, by a freshly reprocessed step.
The coffee extract which is to be decaffeinated is pre-
zs ferably passed through all adsorption steps successively,first passing through the adsorpt;on step which out of all
the involved steps has been in the adsorption process the
longest and therefore has the lowest capacity to absorb
caffeine, so that at the end the last remainder of caffeine
30 in the coffee extract to be decaffeinated is removed, i.e.
adsorbed by the most effective and freshly reprocessed
adsorption step particularly efficiently. This ensures a
particularly efficient and complete decafFeinat;on of the
coffee.
An apparatus according to the invention for deca-Ffeinating
liquid, especially aqueous raw coffee extracts comprises at
least one chamber (process step) with a fixed bed of ad-
- 6 -
sorb;ng agent, preferably of molecular s;eve, arranged
there;n, and through wh;ch the l;quid or gaseous substances
can be passed. Said chamber also comprises feed and drain
connections for ;ntroduc;ng and w;thdrawing raw coffee ex-
5 tract and at least one further agent for regenerating theadsorbing agent.
The chamber ;s preferably a column. Preferably, there ;s a
f;xed bed of a molecular s;eve (for example 2 kg) located
o ;n such a column through which the respective liquid or
gaseous agent can be passed or is passable. The feed and
withdrawal of the different agents used can be conducted in
a particularly specific way by providing separate
connections and l;nes for these agents, with preferably
s several chambers in this line system being connected
parallel to one another. It is preferred to use closed
circuit lines with Forward and return flow.
Herew;th, the apparatus accord;ng to the ;nvent;on has the
20 part;cular advantage that the chambers ;tself do not have
to be moved for conduct;ng ;nd;vidual processes of the
decaffe;nat;ng process. The chambers and the adsorb;ng
agent located therein do expediently not change location.
Instead, d;fferent agents are introduced to the chambers in
25 a spec;f;c way.
A group of chambers ;s preferably connected ;n ser;es for
conducting the adsorption process or other processes. The
agent needed for this process is then success;vely passed
30 through the chambers of sa;d group (from chamber to
chamber).
Further advantageous embodiments of ~he process according
to the invention and the apparatus according to the
35 invention follow from the subclaims.
- 2 ~
-- 7
Exemplary embodiments which present further features of the
invention are shown in the drawings, in which:
Fig. 1 shows a block diagram to illustrate the prin-
s ciple structure of a decaffeinating apparatus
according to the invention and the operation of
the decaffe;nating process according to the
;nvention,
o Fig. 2 shows a schematic side view of several apparatus
steps of an apparatus according to the invention
in the form of columns,
Fig. 3 shows a perspective side view of the columns
according to Fig. 2,
Fig. 4 shows a circuit of a first embodiment of a de-
caffeinating apparatus according to the in-
vention,
Fig. 5 shows the circuit of a second embodiment of an
apparatus according to the invention,
Fig. 6 shows the circu;t of a third embodiment of an
apparatus according to the invention and
Fig. 7 shows a top view of an example of a principle
arrangement of the apparatus steps of a de-
caffeinating apparatus according to the in-
vention.
Fig. 1 shows a block diagram of the principle structure of
an embodiment of a decaf~einating apparatus according to
the invention and for the operation of an example of a de-
35 caffeinating process according to the invention.
-- 8 --
Field 10 in the block diagram represents the preparat;on ofa liqu;d, espec;ally an aqueous raw coffee extract wh;ch ;s
to be decaffeinated, i.e. it represents an extraction.
5 The raw coffee extract prepared in this way is fed to an
adsorption process according to f;eld 11, in which the
caffeine is removed from the raw coffee extract with an
adsorbing agent. The adsorbing agent is preferably a
molecular s;eve, namely a zeolite, preferably a Y-zeol;te,
which is suitable for a selective adsorption of caF-feine.
The raw coffee extract may pass through t~e adsorption pro-
cess several times for decaffeination. After adsorption,
the decaffeinated raw coffee extract is withdrawn and
s further processed, which is not shown in Fig. 1.
The adsorbing agent used in adsorption 11 is reprocessed
after the adsorption process so it can be re used in a
following adsorption process 11. For this purpose, several
20 chronologically successive processes are conduc-ted, namely
an elution process 12, a desorption process 13 and a clean-
ing process 14.
Water is preferably used for the elution process, which is
25 to remove the raw cof~ee extract remainders or residuals
from the adsorb;ng agent. Th;s water ;s passed through the
adsorb;ng agent, ;f necessary several t;mes. The water,
wh;ch is containing coffee extract residuals after the
elution 12, can be used as swelling water for swelling the
30 raw coffee beans in the extraction process 10.
In the desorption 13, wh;ch follows the elut;on 12, a de-
sorbing agent ;s passed through the adsorb;ng agent charged
with caffe;ne. This desorb;ng agent ;s preferably composed
35 of 80% alcohol and 20% water. In th;s desorpt;on process
13, the desorb;ng agent may be repeatedly passed through
the adsorb;ng agent as well.
2 ~
- 9 -
The desorbing agent desorbs the caffeine from the adsorbing
agent, i.e. the adsorbing agent is liberated from caffeine.
The desorbing agent withdrawn from the desorption process
13 contains caffeine. The desorbing agent and the caffeine
5 or aqueous ca~feine solution are separated by means of a
distillation process 15. After reprocessing, the desorbing
agent, separated from the caffeine by means oF
distillation, can be re-used in a following desorption pro-
cess. After the distillation process 15, the aqueous
caffeine solution is wi-thdrawn and fed to a caffeine pro-
cessing process 16 to obtain caffeine as a b~-product o~
the decaffeinating process.
A cleaning process 14 is conducted after the desorption
process 13 in order to liberate the adsorbing agent from
residuals of the desorbing agent. Preferably water vapor or
water is used as cleaning agent. The desorbing agent is
displaced from the adsorbing agent by means of this water
vapor. After the cleaning process, a desorbing agent/clean-
20 ing agent mixture is withdrawn and also fed to thedistillation process 15. Since water vapor or water is used
as cleaning agent, the alcohol and water composition of the
liquid which is fed to the distillation process 15 is not
changed qualitatively. The quant;tative composition of the
25 reclaimed desorbing agent can be controlled via the para-
meters of the distillation 15.
The sequence of processes 11..14 in the block diagram
according to Fig. 1 is to be understood chronologically.
30 But at the same time, fields 11..14 in the hlock diagram
also represent the arrangement of chambers containing ad-
sorbing agents. Each of the chambers employed passes in
chronological succession through the processes 11..14. Con-
sequently, the block diagram according to F;g. 1 can also
35 be understood spatially insofar as some of the chambers are
operating in one of the process stages according to pro-
cesses 11..14 simultaneously and spatially side by side. I-t
follows that while some of the chambers and the adsorbing
- 10 -
agent located therein conduct the adsorption process 11,
the adsorbing agent of other chambers ;s at the same t;me
reprocessed with the three processes 12..14, some chambers
being in the elution process 12, some already in the de-
5 sorption process 13 and others already in the cleaning pro-
cess 14. Preferably sixteen chambers with adsorbing agent
are used for the decaffeinat;ng process, w;th ten chambers
being simulateneously in the adsorption process 11, one
chamber in the elution process 12, four chambers in the
o desorption process 13 and one chamber in the cleaning
process 14.
~hen the cleaning process 14 is completed in the latter
chamber, i.e. when the last stage in the process of repro-
cessing the adsorbing agent is completed, this chamber is
again transferred to the adsorption process 11. At the same
time, the chamber which has been in the adsorption process
11 the longest is transferred to the elut;on process 12,
the chamber prev;ously used for the elut;on process 12 ;s
20 transferred to the desorption process, and the chamber
wh;ch has been in the desorption process 13 the longest is
transferred to cleaning process 14. Consequently, the
chambers cyclically pass from one process to the o-ther,
such that the number of chambers in any process advantage-
25 ously always remains constant.
As a result, the chambers used in the adsorp-tion process 11
ha~e for example been in this process for different lengths
of time. Preferably, the adsorption process of fresh raw
30 coffee extract ;s started in that chamber wh;ch has been in
the adsorption process the longest, i.e. which has an
adsorbing agent which is charged the most w;th caffeine and
is therewith the least capable of receiv;ng or adsorbing
caffeine. In the course of the adsorption process, the raw
35 coffee extract ;s passed through all (ten) chambers, and
finally through the chamber which has been freshly trans-
ferred from the cleaning process 14 -to the adsorption pro-
cess 11, i.e. which has the adsorhing agent with the
highest capacity of adsorbing caffeine. Consequently, even
the last res;dual of caffeine is effectively removed from
the raw coffee extract.
5 It is an advantage that the chambers do not ha~e to change
locat;on for being transferred from one process to the
next. Instead, the chambers remain in a fixed location and
only the agents needed for the respect;ve process are intro-
duced to the chambers. Consequently, each chamber ;s
o connected to the appropriate substance lines of the re-
spective process. The apparatus for conducting the process
only has to provide a parallel connection of the chambers
and a suitable valve control.
I5 Preferably 20 l/h of raw coffee extract is fed to the
adsorption process 11, using preferably aqueous raw coffee
extract with 5 g/l caffeine. Taking into account the pro-
cess sequence, the adsorbing agent of each individual
chamber is thus charged with 100 9 caffeine during the
20 adsorption process 11.
The individual processes 11..14 have to be in chronological
coordination. The elution process 12 can For instance be
conducted in three steps o~ 10 min each, so that the whole
elution process 12 takes 0.5 h. Altogether 6 l eluting
agent are for instance used in this process. After el~tion,
the eluted chamber can remain on stand-by for ~7.5 h before
being transferred to the desorption process 13. The de-
sorp-tion process may take 1 h for each chamber. Thereafter,
the chamber is transferred to the cleaning process 14. The
actual cleaning ;n the cleaning process 14 may for instance
take 0.5 h. This may also be followed by a stand-by period
of 0.5 h. Accordingly, in 1 h of adsorpt;on process 11,
other chambers go through the elution process 12 (;ncluding
a stand-by period3, the desorption process 13 or the
clean;ng process 14 (including a stand-by period). Sub-
sequently, one chamber from one process ;s cyclically trans-
ferred -to the following process. The adsorpt;on process 11
A ~
- 12 -
can thus be conducted near enough continuously with only
short ;nterrupt;ons for d;sconnect;ng and connecting a
chamber.
s Fig. 2 shows a schemat;c side view of chambers with ad-
sorbing agents, as they can be used for the processes
11..14 accord;ng to F;g. 1. F;g. 2 shows three of pre-
ferably altogether s;xteen chambers.
o Perpend;cularly or;ented columns 17 are used as chambers.
These columns are filled w;th zeolite (for example 2 kg)
act;ng as adsorbing agent, approximately up to a level 18.
The zeolite in the column 17 rests on a permeable sieve
bottom 19 and forms a solid bed of adsorbing agent on th;s
sieve bottom 19. The successive columns 17 are connected to
one another via connection lines 20, such that agents are
introduced to a column 17 from above, withdrawn from the
column 17 at the bottom and introduced to the following
column 17 again from above. Each connect;on l;ne 20 has an
20 actuable shutoff valve 21 to d;sconnect the preced;ng
column 17 from the follow;ng group of columns ;f required.
The agents are moved in the connection l;nes 20 w;th pumps
22. Samples can be withdrawn via sample valves 23.
25 Each column 17 has a double wall 24 by means of which the
wall of the column 17 is heatable by a heat;ng med;um. Such
a heat;ng medium may be passed through the double wall Z~,
as indicated by the arrows 25. The heating medium can be
passed through the double wall in counterflow to the sub-
30 stance lines through the columns 17. The columns l7 arepreferably heated to temperatures of 60 to ~0C, pre-
ferably to approx;mately 75C. The temperature can be ad-
justed to optimize -the respective process to be conducted
or ;t may be relevant as regards for example prevent;ng the
35 raw coffee extract from spo;lage.
2 ~
- 13 -
Fig. 3 shows the three columns 17 accord;ng to F;g. 2 ;n a
schemat;c perspect;ve v;ew.
F;g. 4 shows the c;rcuit according to a -First embodiment of
5 a decaffeinating apparatus according to the invention.
In Fig. 4 and the following figures, sim;lar structural
elements are designated by the same reference numerals as
in Fig. 2.
Fig. 4 shows several columns 17. To simplify matters, only
five out of preferably sixteen columns are shown. The
columns 17 are connected to one another in a circuit via a
connection line 20a and further connection lines 20.
Each of the columns 17 has connections for agent feed lines
26a..29a and for drain lines 26b..29b. The columns 17 are
connected in parallel with respect to these agent lines
26..29. A by-pass line 30 is provided to by-pass a de-
zo fective column 17 or to reverse the direction of flow ofthe agents through the columns 17.
Adjacent columns 17 can be connected or disconnected from
one another by means of the shutoff valves 21, so that
25 groups of one or more columns 17, which are separated from
one another, can be formed. Each culumn 17 can be connected
to one of the substance lines 26..23 by means of four for-
ward flow valves 31 and four return flow valves 32, with
the columns 17 of one column ~roup being connected to the
30 same substance line 26..29.
Raw coffee extract which is to be decaffeinated is provided
in a raw coffee tank 33. The raw coffee extract can be
passed through defined columns 17 via the line 28 and can
35 be withdrawn after decaffeination in the direction in-
dicated by arrow 34. For an adsorp~ion of the caffeine from
the raw coffee extract, a ~roup of preferably ten colums 17
is used as an adsorbtion group and is interconnected via
~ 3
- 14 -
the connection lines 20 or shutoff valYes 21, and at the
same time shut off from the other columns 17. Only the
first column 17 of this adsorpt;on goup ;s connected to the
feed line 28a for the extract and only the last column 17
5 is connected to the drain line 28b for the extract. Thus,
the extract to be daffeinated enters the first column 17 of
this group and passes through each following column 17 via
the connection lines 20 tfrom column to column) up to the
last column 17 and from there into the dra;n line 28b.
lG
After such a run of the extract through the group of ad-
sorption columns, the column 17 which has been in this
adsorption group the longest is disconnected from this
adsorption group by shutting off the preceding and the
15 following shutoff valve 21. The forward Flow and return
flow valves 31, 32, which also belong to the line 28, are
shut off as well. By open;ng the valves 31, 32 to line 29,
this column 17 is connected to the elution cycle to conduct
an elution process. The elut;ng agent feed line 29a is
connected to a tank 35 w;th eluting agent. The eluting
agent is withdrawn from this eluting agent tank 35 and
passed through the column 17 which is to be eluted. After
elution, the eluting agent which has passed through the
column 17 and which is enriched with the extract con-
25 stituent substances can be introduced to a second elutingagent tank 36. This eluting agent from -the eluting agent
tank 36, which contains extract constituents separated from
the adsorption agent, can be used for a second elution and
can be finally withdrawn in the direction indicated by
30 arrow 37. The elut;ng agent, containing extract con-
stituents separated from the adsorbing agent, can be re-
used as a swell;ng liquid for swelling raw coFfee beans, to
prepare a raw coffee extract from raw coffee beans. This
raw coffee extract is used for decaffeination and intro-
35 duced to the raw coffee extract tank 33.
The column 17 which has passed through an elution is dis-
connected from the line 29 by means of operat;ng the valves
31, 32 accordingly and is connected to the desorbing agent
line 27. Preferably four columns are always ;n the de-
5 sorption process at any time. The desorbing agent is storedin a desorbing agent tank 38 connected to the desorbing
agent line 27 and could flow through the columns 17 of the
desorption group via connection lines 20 simultaneously or
success;vely. AFter the desorbing agent has passed through
~o the columns 17 of the desorption group, it reaches an inter-
mediate tank 40 via the desorb;ng agent drain line 27b and
a cooler 39. From this tank it is fed to a distillation
unit 42 by means of a pump 41. The withdrawn desorbing
agent contains the desorbed caffeine which has been
15 desorbed from the adsorbing agent o-F the columns 17 of the
desorption group. The desorbing agent ;s separated from the
caFfeine in the distillation unit 42 by being distilled off
and cooled down with a cooler 43. A pump 44 re-turns the
reclaimed and cooled desorbing agent into the desorb;ng
20 agent tank 38 via a return line 45. An aqueous caffeine
solution rema;ns in the lower port;on o~ the d;st;llat;on
un;t 42. This solution can be concentrated by means of a
circulation evaporator 46 and can be withdrawn via a drain
line 47.
Preferably four columns 17 are s;multaneously in the de-
sorption process 17, and in a deF;ned success;on one column
17 From the preceding elut;on is connected to the de-
sorption group and simultaneously one already desorbed
30 column 17 is disconnected from the desorption group so the
number of columns 17 in this group remains constantly four.
Via a pump 48 and a heat exchanger 49, Fresh desorbing
agent is pumped from the desorbing agent tank 38 into the
column 17 of the desorption group which has been desorbed
35 the most. For example 4 l desorbing agent is pumped for
40 min into this column 17. At the same time, used-up de-
sorbing agent is pumped out of the column 17 of the de-
sorption group which belongs to the desorption group the
- 16 ~
shortest and into which the desorbing agent from the (now)
oldest desorption column is introduced via the connection
lines 2~. The used-up desorbing agent is pumped into the
distillation unit 42. The column 17 provided with fresh
desorbing agent is meanwhile completely desorbed and is
pumped empty within a period of 20 min, with the desorb;ng
agent be;ng fed to the following column 17 of the de-
sorption group. Thereafter, the desorbed column 17 is dis-
connected from the desorpt;on group. The column 17 leav;ng
o the elution process is connected to the desorption group
and receives the desorbîng agent from the preceding
desorpt;on group column 17 wh;ch desorbing agent ;s ;n the
end d;splaced therefrom by the relatively fresh desorb;ng
agent com;ng from the column wh;ch has just been dis-
s connected from the desorpt;on group. Thus, each column
rema;ns ;n the desorpt;on group for four hours.
The column disconnected from the desorpt;on group is
connected to the cleaning agent line 26 as a single column
after being shut off from the other columns by the shutoff
valves 21.
Water vapor is used as a clean;ng agent and ;s fed into the
cleaning agent feed line 26a ;n the direction indicated by
arrow 50 and passed through the column 17 which i5 to be
cleaned. The vapor which has displaced the last residual of
desorbing agent from the cleaned column 17 is withdrawn
from this cleaned column 17 via the cleaning agent drain
line 26b and, together with this desorbing agent residual,
reaches, via a cooler 51, -the intermediate tank 40 which
also receives used-up desorbing agent. Accordingly, a
desorb;ng agent/water vapor mixture wh;ch contains dis-
solved caffeine is reprocessed in the distillat;on unit 42
and separated ;nto fresh desorb;ng agent and aqeuous
caffeine solution.
~,9
- 17 -
After the clean;ng process, the adsorbing agent of the
cleaned column 17 ;s again adsorptive and can be re-connect-
ed to the adsorption group of ten columns. The place of
this column in the elution is taken by the adsorption
5 column which is used-up the most.
Consequently, there are always ten out of sixteen columns
in the adsorption process, one column in the elution pro-
cess, four columns in the desorption process and one column
o in the cleaning process, with only one column of one group
being cycl;cally transferred from one group to the next in
an intermittent manner. This ;s made possible by a simple
control of the valves 21 and 31, 32.
~5 A complete cycle, in which one column passes through all
possible process stages, from the youngest adsorption
column to the oldest adsorption column, to the column in
the cleaning process, from ~he youngest desorption column
to ttle olded desorption column and finally to the cleaning
20 column, takes 16 h. Each switching cycle, in which one
column is cyclically transferred to the following group of
columns takes 1 h.
Fig. 5 basically shows a circu;t like that of Fig. ~, the
25 only difference being an additional third eluting agent
tank 52 in the circuit of Fig. 5.
Coming from the first elut;ng agent tank 35, fresh eluting
agent passes through the column 17 of the elution process
30 and into the second eluting agent tank 36. From this second
tank, eluting agent is withdrawn for a second elution of
the column 17 and is passed through the column 17 and into
the third eluting agent tank 52. The eluting agent from the
third eluting agent tank 52 is used for a th;rd elut;on and
35 thereafter is w;thdrawn ;n the direction indicated by arrow
37. The eluting agent circuit comprises a pump 53 and heat
exchangers 54, 55.
2 ~ êJ~
- 18 -
F;g. 6 shows a c;rcuit s;m;lar to those of F;gs. 4 and 51
especially of Fig. 5. F;g. 6 add;tionally shows a vapor
tank 56 and tanks 57 and 58 for used-up elut;ng agent and
decaffeinated extract. Two intermediate tanks 40a and 40b
5 are provided instead of just the one ;ntermediate tank 40.
The distillation unit 42 is followed by a caffeine pro-
cessing unit 59.
Fig. 7 shows a schemat;c top plan v;ew of s;xteen columns
o 17. These columns 17 are distributed essent;ally evenly
over the per;phery of a rectangle by means of column
holders 60. Fig. 7 also ind;cates that the columns 17 are
connected to a closed c;rcuit system via lines 20, 20a and
26..29.
