Note: Descriptions are shown in the official language in which they were submitted.
~ W094/11472 2 ~ a 9 2 4 ~ PCT/NO93/00]67
Method and equip,ment _or hardening oi~lL fat and fatty acids ;
The present inventio~ concerns a~method and equipment for
h~drogenating or hardening oil, fat a~d ~fatty acids by adding
hydrogen and using a catalyst. ~,`
.~,
I~ an existing method for hardening and stabilising oil, fat or
fatty acids, a large, ~closed tank or container with a stirring
device is used. The oil or fat is treated in batches by adding
hydrogen in an eddy current which~is created~by a ~mechanical
stirrer designed;as a rotor with several sets of propeller blades
or as a screw.
It i~ obvious that the~hydrogenation~e~fficiency of such a system
is very low becaus~e~the~contact area between the gas, liquid and
catalyst is small and;the ~turbule~ce is~poor. ~
This is also conflrmed~by~the results obtained~in practice where
the reaction speed defined as~the iodine reduction (~I) per time
unit is low, for example 0.3 I/min. ~
With a~low reaction~speed~;large, ~space-consuming~and costly
processing equipment is required to~abtain~the~desired processing
càpacity. Another~fundamental weakness of batch systems is that
the consumptian af~hydrogen~ls very irregular. In the first'phase~
af the proces~s the~consumptian~of~hydrogen~is high~but gaes~down;~
radically as the praportion of unsaturated~molecules,~in~the oil
batch~beaomes law.'~
In~some cases;the consumpt~ion of~hydrogen in the first half hour~
can be approximately~80 ~'of the~total consumption,~while it can
take 4-6 hours far the hydragenation to be completed.
Other ~disadvantages~are~that~it ~is~dlfficult to~cantral~the
pracess~ in~a~large~autaclave~where temperature differences and~
;di-f~erent ~hardening ~processes~from~ place to place in the
aut'oclave will~ aa~cur. 'The energy~cansumption for mechanical
stirring will ~also ~be relatively high and~optimal stirring can
usually nat be~jusCifled an~accaunt~af the~energy consumptlan,
WO94/11472 PCT/NO93/00167 ~ , -
21~92'-18; 2
Equipment of the above, existins type is discussed in more detail ..
in the publication INFORM:, Vol. 3, No. 7, July 1992.
,~
Another existing system of the batch type is the Sullivan system ' .
(Alfa-haval). Generally speaking, it works in~the same way as the
above system, but: a~ higher reaction~gpeed is obtained by ~
recirculating the hydrogen which flows~ to the top of the ~
autoclave by means of a compressor throush a per~orated ring back 1.-
to ~he base of the tank. :~
The reaction speed in the Sull:ivan~system is:stated as 1.5 - 2
I/min., but apart from this impro~ement~:the~:weaknesses of the
system are the same as~for the convent~ional~bat~ch process.~ ,
It has therefore been an aim of the present invention to create ~:
a solution for hardening or hydrogenating fat or oil which is, in: ~:
its entirety, consideràbly more efficient~ than existing sol-:
utions.
The aim has been to~achieve :~
:- higher reaction~speed~
regular hydrogen consumption :
- ` simple, xeliable;process control~
- selective hydrogenation
-~ low catalyst :consumption
: reduction oe~energy con~umpt~o~(kW)~
In accordance with the present invention~the~ stated objectives
were achi.eved by a:procedure for:hardening~oll or fat which is .
characterised by a semi-continuous or continuous process in which .
,
the catalyst is mixed~with preheated fat ~or oil in::a:mixi~ng
device, whereby~thè~mixture~is passed~ through a: preferably
sexpenti~e-like,~:vertically-moun;ted pipe loop~ or one: or more
stat~ic mixers for~the addition of~hydrogen~and, possibly, inert
gas 90 ~that~ a turbulent co-c~rrent~flow~ achieved,~the mlxture
is cooled:~during hydrogenation~and, po~ssiblyj~:the oil, catalyst,
nert: gas. and :excess;hydrogen gas are rec~irculated after the
hardening proces~s.;~
. ..... ~
~ W094/11472 2 1 a ~ 2 ~ ~ PCT/N093/00167
Furthermore, the present invention comprises processing equipment
for the hardening of oil or fat which i5 characterised by feed
and mixing devices for the addition and mixing of oil and a
catalyst, a prefe~ably serpentine-like, vertically-mounted pipe
loop, or one or more static mixers and cooling devices with feed
devices for hydrogen gas and, possibly, inert gas, and devices
for collecting the oil, separating and recirculating any inert
gas and the supply, separation and, possibly, recirculation of
used hydrogen gasj as well as a possible separation and
recirculation of the catalyst.
The dependent claims 2-3 and 5-12 define the advantageous
features of the present invention.
.
The present invention shall now be defined in further detail by
means of examples and with reference to the attached drawings in
which Fig. 5 shows a continuous process ~equipment for the
hardening or hydrogenation of oil or fat~and Fig. 2~ shows
alternative equipment which, for example, can be used as a
retrofit in existing hydrogenation systems. The equipment
comprises, as Fig. l shows, a feed~ and~mixing device A), a
serpentine-like pipe loop B), and devices~C)~for separating and
recirculating a ~atalyst, supply and~recircu1ation of any inert
gas, and supply and recirculation of any excess hydrogen gas. The
feed and mixing device A) consists of a holding and recirculation
tank l with a stirring~devlce 2 f~r catalyst suspension, a heat
e~changer 3 and a feed and~stirring tank 4 f~or the oil or fat,
and pumps 6, 7 with appropriate plpes 9, lO for the transporta-
tion of the oil and the catalyst suspension respectively to a
mixing point lO where thei pipes 8, 9 meet. The catalyst is
preferably of Ni, deposited on carriers of minerals or plastics
in the form of grain-like part~icles~and the purpose of the
stirring device 2 in the tank l is to keep this suspension
homogeneous and prevent the deposition of catalyst particles on
the base of the tank. In~a similar way another purpose of the
stirring device 5 is to keep a regular temperature in-the oil or
fat in the tank 4.
. :
.
WO94/11472 ` PCTJNO93/00167
21~!~24~8
The oil, fat or fatty acid, depending on what is to be hardened,
is ~ed from a storage tank or simiIar (not shown) via pipes 8, -
first through a heat exchanger 3, where it is heated, and
subsequently to the~stirring tank 4. From tank 4 the oil can be
recirculated through the heat exchanger 3 by means of the pump 6.
.. ~
During the hydrogenation process the oil is pumped from tank 4 on ;'~
to the mixing point 10 where it is mixed with the catalyst ~''
suspension from the holding tank l. From here the mixture is ~'
transpor~ed through~a~serpentine-l~ike pipe loop lI into the
hydrogenation system B). Hydrogen~in the quantities required is
supplied~ to the~pipe loop ll at several points 12 via supply t~
pipes ~13 and flows with the oil ~in a turbulent co-current
(bubble-flow), at the same time~as;~the reaction wlth the oil j!,.
takes place.
,
In a corresponding manner any inert~gas, for example nitragen, is t~-'
added at differen~ point~s 14 via supply pipes~l5. ' j'
The addition of ~any~ inert gas is intended to -regulate the ~:
hydrogen cover of the~catalyst and th~ereby;cont;rol the reaction~
speed~and obtain~selective hydrogen~$ion,~at the same time as
maintaining the eurbulent gas-liquid current.
Moreover, one~or more coolers or heat exchangers~21 are~mounted~ "
in the pipe loop~. The purpose of~these is to gradually remove the
heat'generated during;the exo~hermic haxdening process and keep
the optimum reaction~temperature~. ~This~heat can be expediently
used~to preheat untreated oil~which~ s~to be~fed into~part A) of
the processing system. This produces a considerable reductlon in
energy consumption.
From ~the~ pipe l~oop~, the~oil,~catalyst and~gas mixture goes to ~ '~
part C);of the ~processing system,~;~which~comprises a collection
tank 16 with~a~ stirring device~;17,~a~pipe system 18 with a -
~compressor 19 for recirculating~the~exces~s inert and hydrogen
gas~,~ a~well as~;a~ pipe~system ~20,~ possibly with a centrifuge~
and/~or;filter or~s;imilar~;built~in to separate and recirculate~the ~`
catalyst~slurry.~
~ W094111472 21 4 9 2 ~ ~ PCT/N093/00167
,
The purpose of the stirring device 17 in the collection tank 16
is to prevent the catalyst being deposited on the base. Other-
wise, the collection tank works like a gas separator and the
collected gas is extracted from the top of the tank by means of
the compressor l9. In this connection it should be noted that the
gas which is extracted from the tank 16 may, depending on the
reaction process, be pure inert gas~or a mixture of inert gas and
hydrogen and this gas is mixed with hydrogen from the hydrogen
supply (not shown) via the~pipe l8. The gas~which is supplied to
the pipe loop ll through points 12 is thus a mixture of hydrogen
and inert gas and~the mixture ratio;may, as stated earlier, be
regulated in a precise manner to~ obtain the desired hardening
speed and degree of hardening.
The oil/catalyst mixture is~fèd from the base of the tank 16 and,
possibly, through a centrifuge or;similar. The hardened oil is
fed to a storage tank (not shown) via the pipe 22 while the 1;
catalyst is fed back to the holding tank l via the pipe 23.
Otherwiss regarding;Fig.~ 1 it should be noted that the present
invention as it is described in the claims is not limited to the
this~solution. Thus the squipment shown may be used~without the
use of inert gas. ~ ~
Furthermore, instead of two separate tanks~l and 4, a joint tank
for the catalyst and; oil may be used, whereby the catalyst is
recirculated to tank 4~ instead of tank l.~ Moreover, it may be
practical to not recirculate the~catalyst after hydrogenation but
to have it dischargsd through the outlst pipe 22 together with
the oil for later separation
~Fig. 2 shows~an alternative~;processing system in accordance with
the present invention which~can easily be used for converting
conventional batch systems but which;can also be used for new
systems. This~solutlon can be~described as semi-continuous as the
oil is~fed into the~a~toclave or container 24 in batches while
the actual hydrogenation~takes~place continuously. j ,`
wn 94/11472 PCT/NO93/00167
214~2~
More precisely, Fig. 2 shows a large, closed container 24 which
is designed to contain a certain quantity of oil plus a calcu-
lated quantity of catalyst, preferably Ni catalyst. A base
stirrer ensures that the catalyst, which is mainly in the oil in
the lower part of the container, is kept in suspension and is not
deposited on the base of the container. The oil mixed with the
catal~st is pumped out~of the tank~by means of a pump 26 via a
pipe system 27 through a serpentine pipe system as described for
the continuous hydrogenation system or through a set of static
mixers/heat exchangers back to the top of the tank;and out into
it via a diffuser 29 which~ slows the speed and distributes the
oil/gas flow.
The hydrogenation takes place in exactly th~ same way as with a
continuous system such as that described earlier. Excess hydrogen
and inert gas are extracted ~rom the top of the tank and
recirculated as in the continuous system. In the system shown in
Fig. 2 the tank has no built-in heating device.
'~
;
When the hardening process is to~ be set in train, the heat
exchangers in the combined static mixerlheat exchanger are used
to heat up the oil in the container but as soon as the tempera-
ture is sufficiently high (about 160C) and the hardening Frocess ~-
has started, the heat exchangers are used to cool the oil.
Reference numbers 32 and 33 show, respectivel~y, the inlet and the
outlet for the heat exchanger's heat exchange medium which may be
steam during heating and may be water during cooling.
During the hardening process the catalyst particles will sink i-
towaxds the base in such a way that the catalyst concentration
will be highest;~in the area where the stirring takes place.
Moreover, the stirring is concentrated in the base volume so that
it does not a~fect the oil above (above the dotted Iine). This
means that the hardened oil which is~ returned to the container
through the diffuser 29 will sink relatively quickly towards the
base. In this way it will be possible to use a much smaller
catalyst charge~than~with conventional batch systems.
~, WO94/11472 21~ 9 ~ PCT/NO93/00167
When the hardening process has been completed, the oil can be
pumped out and the container emptied through the discharge pipe
34. New, unhardened oil and ~catalyst are added to the container
through the filling pipes 35, 36.
In the two previous examples, Fig. l and Fig. 2, a serpentine-
like pipe loop and static mixers~ were used respectiveLy. The
present invention is, however, not limited~to these two examples
as, instead of a pipe loop as shown in Fig. l, static mixers may
be used and, instead of the static mixers shown in Fig. 2, a pipe
loop with separately arranged heat exchangers may be used.
~ The length of the pipe loop~or the number ~and length of the
static mixers and heat exchangers can be adapted to the hydroge-
nation process to give optimal operating conditions.
The two examples shown are thus~alternatlves which are kept at
the desired temperature by means of built-in heat exchangers/
coolexs in the loop 8.
Exam~le
180 l refined soya oil was t~reated ~in a small system in a
continuous process generally speaking like that described above.
The oil was heated up to 160C by~ means o~ an e~tra heating
element in the stirring tank 4 under an inert atmosphere of
nitrogen. The catalyst was added in the~same tank.
: . : : ~: : :
324 g of Ni catalyst o~ type Pricat 9910 with 2~0 % Ni~was used as
the catalyst. The quantity corresponds to~0.04 % Ni in the oil
which is the normal catalyst quantity when hardening soya oil in
a batch reactor.~ The supply of~hydrogen~was 3 x 44 Nl/min. and
~the pressure in the~pipe loop~wa~s~;~8 bar. ~
The test was carried out ouer 45 minutes. The mean oil flow was
3.8 kg/mln. and the~mean dwell time for the oil in the pipe batch
was 7 minutes.
WO94/11472 21 ~ 9 2 ~ 8 PCT/NO93/00167 ~ 1"
The so-called iodine value (IV) before hardening was measured at -
12~ and after hardening at 59.7, i.e. a difference of approxi-
mately 70 AIV.
:
With a mean dwell time of 7 minutes this produces a reaction
speed of approximately lO ~IV/min. Compared with the best - -
conve~tional systems this represents a reaction speed 5-6 times l;
faster. ~ ~
However, with the present invention not only is the efficiency
improved but also important conditions such as considerably lower t~
investment costs~ better and more precise process control, lower
energy consumption,~ simpler and more cost-effective operation,
lower cata~yst consumption, regular hydrogen consumption and the ;-
possibility of obtaining bettèr product quallty.
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