Title of Invention

IMPROVED METHOD FOR SEPARATING GASES FROM A GAS MIXTURE AND DEVICE FOR APPLYING SUCH A METHOD

Abstract Improved method for separating gases from a gas mixture, whereby the gas mixture to be treated is led through a membrane separator (3) by means of a compressor installation (2) and whereby the compressed gas mixture to be treated is cooled in the compressor installation (2), among other in other to separate condensate from the gas mixture, after which, as it leaves the compressor installation (2), it will be re heated before it ends up in the membrane separator (3), characterized in that, in order to re-heat the gas mixture to be treated as it leaves the compressor installation (2), use is made of the recuperation heat of the compressor installation (2) itself.
Full Text IMPROVED METHOD FOR SEPARATING GASES FROM A GAS MIXTURE AND DEVICE FOR APPLYING
SUCH A METHOD
The present invention concerns an improved method for
separating gases from a gas mixture.
The invention also concerns a device applying such a
method for separating gases from a gas mixture.
More particularly, the invention concerns a known method
for separating gases from a gas mixture, for example for
separating nitrogen and/or oxygen from air or for
separating water vapour from a gas stream or the like,
whereby use is made of a membrane separator • and whereby
the gas mixture to be treated is led through the
membrane separator by means of. a compressor installation,
and whereby the compressed gas mixture is usually cooled
in the compressor installation in order to dry and filter
the gas mixture by means of condensation techniques.
It is known that the output of the separation of gases, by
applying such a method whereby use is made of a membrane
separation, can be improved by re-heating the gas mixture
that was cooled in the compressor installation before
sending it through the membrane separator.
A higher output implies a higher selectivity of the
separation process, a greater purity and less losses of
the separated gases and a higher permeability of the
membrane separator for the same aimed purity of the
separated gases.
Re-heating the gas mixture to be treated after it has left
the compressor installation was done xmtil now by means of
heat coming from an external heat source such as an
electrical resistance, a steam circuit or the like.
A disadvantage of such an external heat source is that
re-heating the gas mixture to be treated requires
extra energy, which is of course disadvantageous to the
production costs and the cost price of the separated
gases.
The present invention aims to remedy the above-
mentioned and other disadvantages by providing an
improved method for separating gases from a gas mixture,
whereby the gas mixture to be treated is led through a
membrane separator by means of a compressor installation
and whereby the compressed gas mixture to be treated is
cooled in the compressor installation, among others in
order to separate condensate from the gas mixture,
after which, when leaving the compressor installation, it
is re-heated before it ends up in the membrane separator,
and whereby, in order to re-heat the gas mixture to be
treated as it leaves the compressor installation, use is
made of the recuperation heat of the compressor
installation itself.
An advantage of such an improved method according to the
invention is that the re-heating of the gas mixture to be
treated in order to maximize the output of the membrane
separator does not lead to any extra energy costs, so
that the aimed separation of gases can be done more
selectively and at a favourable cost price.
Preferably, in order to re-heat the gas mixture to be
treated, use is made of the heat of the compressed gas
mixture at the exit of a compressor element of the
compressor device, whereby more particularly the heat will
be used which is drawn from the gas mixture to be treated
at the exit of a compressor element during the cooling for
separating condensate as mentioned above.
When more particularly a compressor element with liquid
injection is used, whereby the injected liquid is
separated in the known manner at the exit of the
compressor element concerned and is subsequently
carried back to the compressor element so as to be
injected again, use can also be made, for re-heating the '
gas mixture to be treated as it leaves the compressor
installation, of the heat of the separated liquid.
If the compressor installation is equipped with a cooler
which makes use of a cooling medium, for example for
cooling one or several compressor elements, the
recuperation heat of said cooling medium can be used in an
energy-saving manner in order to re-heat the gas
mixture to be treated as it leaves the compressor
installation.
It goes without saying that, in order to re-heat the gas
mixture to be treated, the heat of the compressed gas
mixture and/or the heat of the recycled injection liquid
and/or the heat of the cooling medium of a cooling
circuit or the like can be used simultaneously and in
combination.
The compressed gas in the compressor installation is
preferably dried and filtered before being led in the
membrane, in order to remove liquid drops,
specks of dirt and other impurities from the
gas mixture which could stop up or damage the membrane
separator.
The invention also concerns an improved device for
separating gases from a gas mixture according to the
above-described method, which device mainly consists of
a compressor installation with an inlet and ein outlet for
the gas mixture to be treated and a membrane separator
whose entry is connected to the above-mentioned outlet
of the compressor installation via a supply line,
characterised in that a radiator is incorporated in
this supply line through which the gas mixture to be
treated, flows and which is part of at least one heat
exchanger of the compressor installation itself.
In order to better explain the characteristics of the
invention, the following preferred embodiment of an
improved device according to the invention for
separating gases from a gas mixture is given as an
example only without being limitative in any way, with
reference to the accompanying drawings, in which:
figures 1 to 7 schematically represent different
variants of an improved device according to the
invention.
The improved device 1 from figure 1 mainly consists of a
compressor installation 2 and a membrane separator 3 which,
is connected to this compressor installation 2.
The compressor installation 2 in this case consists of a
compressor element 4, more particularly an oil-free
compressor element, whose inlet is connected, via a
suction filter 5, by means of a suction line 6, to the
inlet 7 of the compressor installation 2, whereas the
outlet of the compressor element 4 is connected to the
outlet 9 of the compressor installation 2 by means of a
compressed air line 8.' ¦
In the compressed air line 8 is provided a heat exchanger
10 which is composed, in the known manner, of two radiators
placed opposite . each other, 11 and 12 respectively,
whereby the radiator 11 is incorporated in the above-
mentioned compressed air. line 8 towards the outlet 9 of
the compressor installation 2.
Behind the radiator 11 is incorporated a water
separator 13 in the same compressed air line 8.
Opposite to the heat- exchanger 10 is provided a fan 14
v/hich is directed onto the heat exchanger 10.
The above-mentioned membrane separator 3 has an entry 15
which is connected to the above-mentioned outlet 9 of
the compressor installation 2 by means of a supply
line 16, whereby the above-mentioned second radiator
12 of the heat exchanger 10 of the compressor-
installation 2 is incorporated in this supply line 16.
The membrane separator 3 is in this case provided with
two exits, 17 and 18 respectively, but it may also have
several exits.
The working and use of the device 1 for separating
gases from a gas mixture is very simple and as follows.
The gas mixture to be treated, for example ambient air, is
sucked in by the compressor installation,, as represented
in figure 1, via the inlet 7 and the filter 5, and it
is compressed by the compressor element 4 and forced via
the compressed air line 8 through the radiator 11 and the
water separator 13, and subsequently led via the supply
line 16 through the radiator 12 and the membrane separator
3, whereby in this membrane, separator 3, the gas mixture
is separated into two or more components in the known
manner, for example nitrogen and oxygen, which are
collected at the respective exits 17-18.
The relatively cold flow of air which is generated by
the fan 14 successively flows through the meshes of
the radiator 11 and through the meshes of the radiator
12 of the heat exchanger 10, as a result of which the
hot gas mixture to be treated flowing directly out of the
compressor element 4 through the radiator 11 will be
cooled and then, after further cooling in the water
separator 13, will be re-heated in the radiator 12 before
flowing to the membrane separator 3 .
In the water separator 13, water vapour from the
gas mixture to be treated is separated by means of
condensation or the like, as a result of which is
prevented that the membrane separator would be
saturated by water, which would be disadvantageous to the
good working thereof.
As the gas mixture to be treated, after it has left the
compressor installation, is re-heated before flowing
through the membrane separator, the gas separation in the
membrane separator will be more efficient. ¦
Although in the given example of figure 1, the entire
output of the compressor element 4 flows through the
membrane separator, it is not excluded that, according to
a variant, only a part of this output will be led through
the membrane separator via a branching of the compressed
air line 8 or the like.
Figure 2 represents a variant of figure 1, whereby a
two-stage compressor is applied in this case with two
compressor elements 4 placed in series behind each other
and which are connected to each other via an intermediate .
line 19 in which are incorporated an intermediate cooler
20 and an extra water separator 13 for the intermediate
cooling and drying of the gas mixture to be treated.
The heat exchanger 10 is not an air-cooled heat
exchanger as in figure 1 in this case, but it is cooled
by a separate cooling circuit 21 with an extra cooling
radiator 22 and a cooling liquid which absorbs heat from
the radiator 11 and gives this heat back at the height of
the radiator 12 to thus re-heat the gas mixture to be
treated as it leaves the compressor installation 2.
Figure 3 represents a variant, whereby in this case, as
compared to the device from figure 2, an additional drye^r
23 is provided which is filled with a desiccant, whereby
this dryer 23 is incorporated behind the water separator
13 in the above-mentioned compressed air line 8 and which
provides for an extra drying of the gas mixture to be
treated.
If required, the compressor • installation 2 can be
equipped with the necessary features which make it
possible to regenerate the saturated or partly saturated
desiccant in the known manner.
Figure 4 represents a variant whereby an extra cooler 24
is applied between the heat exchanger 10 and the water
separator 13 which allows for extra cooling of the gas
mixture to be treated so as to be able to separate more
water by means of condensation in the water separator 13.
It is clear that also the recuperation heat of this
extra cooler 24 can be used for re-heating the gas
mixture to be treated.
Figure 5 represents another variant of a device 1
according to the invention.
In this case, a compressor element 4 with liquid
injection is applied whereby a liquid separator is
provided at the exit of the compressor element 4 in the
compressed air line 8, and whereby the exit of this liquid
separator 25 is connected to the liquid injection system
2 7 of the compressor element 4 via a return line 26,
whereby a radiator 28 is provided in the return line 26
which is part of a heat exchanger 29 comprising a second
radiator 30, which second radiator 3 0 is incorporated
in the supply line 16 to the membrane separator 3.
The heat exchanger 29 is equipped with a fan 31.
In the compressed air line 8, after the oil separator
25, is provided a cooler 24 which is followed by a water
separator 13 and which is in turn followed by a filter 32
or by a set of filters and adsorption elements.
The fan 31 blows relatively cool ambient air through the
reidiators 27-29 concerned, as a result of which there
is a heat transfer between the hot injection liquid in
the first radiator 27 and the gas mixture to be treated
flowing through the second radiator 29, such that this
gas mixture, as it leaves the compressor installation
2, will be re-heated before being led in the membrane
separator 3, and a better output of the membrane
separator 3 is obtained.
Thanks to the filter 32 or set of filters which are
erected at the coldest point in the compressed air line,
vapours, specks of dirt and other impurities from the gas
mixture to be treated w^ill be filtered by means of
adsorption, condensation or the like.
The device according to figure 6 differs from the device
in figure 5 in that in the compressed air line 8, between
the water separator 13 and the filter 32, is provided an
additional cool dryer 33 consisting of a heat exchanger
34, a heat exchanger 36 connected to a cooling circuit 35
and an additional water separator 13, whereby in the heat
exchanger 34 of the cool dryer 33, the gas mixture to be
treated, after having been cooled in the heat exchanger, is
re-heated and whereby this gas mixture, after it has"
passed through the filter 32, is further heated in the
heat exchanger 29 before it ends up in the membrane
separator 3.
Figure 7 represents another variant of the device from
figure 5, whereby a by-pass line 3 7 is in this case
provided in the return line 26 which bridges the above-
mentioned radiator 2 8 and in which an adjustable valve
3 8 is provided which is part of a control circuit 39
with a temperature sensor 40 which is erected in the
supply line 16 at the entry 15 of the membrane separator
3.
In this case, as a function of the position of the
valve 38, the output of the injection liquid is split in a
part going through the radiator 2 8 and a part flowing
directly to the injection system 27 via the by-pass line
37, such that the heat transfer in the heat
exchanger 29 is a function of the position of the valve
38.
The control circuit 3 9 makes sure that the opening of
the valve 3 8 is controlled such that the temperature of
the gas mixture to be treated is constant at the
entry 15 of the membrane separator 3 and equal to a
set target value.
An additional cooling radiator 41 in this case makes
sure that when the valve 38 is entirely open, the
injection liquid will still be sufficiently cooled in
order to prevent any damage to the compressor element 4.
It is clear that the above-described method and devices
can be applied with good results on all types of
membrane separators 3, either with or without applying a
gas to wash the separated gases.
The present invention is by no means restricted to
the embodiments given as an example and represented
in the accompanying drawings; on the contrary, such a
method and device according to the invention can be
made according to different variants while still
remaining within the scope of the invention.
WE CLAIM

1 . - Improved method for separating gases from a gas
mixture, whereby the gas mixture to be treated is led
through a membrane separator (3) by means of a compressor
installation (2) and whereby the compressed gas mixture
to be treated is cooled in the compressor installation
(2) , among others in order to separate condensate from
the gas mixture, after which, as it leaves the
compressor installation (2), it will be re-heated before
it ends up in the membrane separator (3), characterised_
in that in order to re-heat the gas mixture to be
treated as it leaves the compressor installation (2) ,
use is made of the recupajration heat of the compressor
installation (2) itself.
2-- Improved method as claimed in 1, wherein
in that in order to re-heat the gas mixture to be
treated, use is made of the heat of the compressed gas
mixture at the exit of a compressor element (4) of the
compressor installation (2).
3. - ¦ Improved method as claimed in claim 1 or 2
where in that in order to re-heat the gas mixture
to be treated, use is made of the recuperation heat
which is drawn from the gas mixture to be treated
while cooling the gas mixture as mentioned above,
among others in order to separatte the condensate.

4.- Improved method as claimed in any one of the precedincg
claims, where in that the compressor
installation (2) comprises a compressor element (4) with
liquid injection whose injected liquid is separated at
the exit of the compressor element (4) concerned by a
liquid separator (25) , whereby the heat of the separated
liquid is used to re-heat the gas mixture to be treated as
it leaves the compressor installation (2) .

5. - Improved methpd as claimed in any one of the precedina
claims, where in that the compressor
installation (2) is equipped with a cooler in which a
cooling medium is applied and whereby the recuperation
heat of this cooling medium is used to re-heat the gas
mixture to be treated as it leaves the compressor
installation (2) .
6 . - Improved method as claimed in any pne of the
preceding claims, wherein that after the'
cooling of the gas mixture to be treated in the
compressor installation (2) as mentioned above, the
gas mixture is led through a dryer (23-33) .
7.~ Improved method as claimed in claim 6, wherein
in that ¦ the gas mixture is led through a dryer (23) on the
basis of a desiccant.
8.- Improved method as claimed in claim 6, wherein
in that the gas mixture is led through a cool dryer
(33).

9. - Improved methpd , as claimed in any one of the precedina
claims, wherein that after the cooling of the
gas mixture to be treated in the compressor
installation (2) as mentioned above, the gas mixture
is led through a filter (32) or through a set of filters
and adsorption elements.
10.- Improved device for separating gases from a qas
mixture as claimed in method of any one of the preceding
claims, which device (1) mainly consists of a compressor
installation (2) having an inlet (7) and an outlet (9)
for the gas mixture to be treated and a membrane separator
(3) whose entry (15) is connected to the above-mentioned
outlet (9) of the compressor installation (2) via a
supply line (16), characterised in that a radiator (12-
30) is incorporated in this supply line (16) through
which the gas mixture to be treated flows and which is
part of a heat exchanger (10-34-29) of the compressor
installation (2) itself.

11.- Improved device as claimed in claim 10, wherein
in that the above-mentioned heat exchanger (10-34) is
incorporated in a compressed air line (8) between the
exit of a compressor element (4) and the exit (9) of
the compressor installation (2) .
12 . Improved device as claimed in claim 11,

wherein that the above-mentioned heat exchanger
(34) is a cooler which is part of a cool dryer (33) of the
compressor installation (2).
13.Iproved device as claimed in claim10,
wherein that the compressor installation (2)
comprises a compressor element (4) with liquid injection
and a liquid separator (25) incorporated in the above-
mentioned compressed air line (8) at the exit of the
compressor element (4) concerned and whose exit is
connected to the liquid injection system (27) of the
compressor element (4) via a return line (26) , and
whereby the above-mentioned heat exchanger (29) is
incorporated in said return line (26) .

14.- Iproved device as claimed in claim 10,
where that the compressor installation (2) is
equipped with at least one cooling circuit (21) and in
that the above-mentioned heat exchanger (10) in the
supply line (16). to the membrane separator (3) is part
of this cooling circuit (21) .


Improved method for separating gases from a gas mixture, whereby the gas mixture to be treated is led through a membrane separator (3) by means of a compressor installation (2) and whereby the compressed gas mixture to be treated is cooled in the compressor installation (2), among other in other to separate condensate from the gas mixture, after which, as it leaves the compressor installation (2), it will be re heated before it ends up in the membrane separator (3), characterized in that, in order to re-heat the gas mixture to be treated as it leaves the compressor installation (2), use is made of the recuperation heat of the compressor installation (2) itself.

Documents:

00808-kolnp-2006-claims.pdf

00808-kolnp-2006-description(complete).pdf

00808-kolnp-2006-drawings.pdf

00808-kolnp-2006-form-26.pdf

00808-kolnp-2006-form1.pdf

00808-kolnp-2006-form2.pdf

00808-kolnp-2006-form3.pdf

00808-kolnp-2006-form5.pdf

00808-kolnp-2006-pct others.pdf

00808-kolnp-2006-pct-pamplate.pdf

00808-kolnp-2006-priority document.pdf

00808kolnp2006 abstract.pdf

00808kolnp2006 correspondence others.pdf

808-kolnp-2006-granted-abstract.pdf

808-kolnp-2006-granted-claims.pdf

808-kolnp-2006-granted-correspondence.pdf

808-kolnp-2006-granted-description (complete).pdf

808-kolnp-2006-granted-drawings.pdf

808-kolnp-2006-granted-examination report.pdf

808-kolnp-2006-granted-form 1.pdf

808-kolnp-2006-granted-form 18.pdf

808-kolnp-2006-granted-form 2.pdf

808-kolnp-2006-granted-form 26.pdf

808-kolnp-2006-granted-form 3.pdf

808-kolnp-2006-granted-form 5.pdf

808-kolnp-2006-granted-reply to examination report.pdf

808-kolnp-2006-granted-specification.pdf

808-kolnp-2006-granted-translated copy of priority document.pdf

808-KOLNP-2006-PETITION UNDER RULE 137.pdf

808-KOLNP-2006-REPLY TO EXAMINATION REPORT.pdf

808-KOLNP-2006-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf

abstract-00808-kolnp-2006.jpg


Patent Number 240549
Indian Patent Application Number 808/KOLNP/2006
PG Journal Number 21/2010
Publication Date 21-May-2010
Grant Date 17-May-2010
Date of Filing 03-Apr-2006
Name of Patentee ATLAS COPCO AIRPOWER, NAAMLOZE VENNOOTSCHAP
Applicant Address BOOMSESTEENWEG 957, B-2610 WILRIJK
Inventors:
# Inventor's Name Inventor's Address
1 VAN HOVE, BEN, PAUL KARL BALLAARSTRAAT 26 B-2018 ANTWERPEN
PCT International Classification Number B01D53/22; B01D53/26
PCT International Application Number PCT/BE04/000135
PCT International Filing date 2004-09-24
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 2003/0514 2003-10-01 Belgium