U.S. patent application number 15/301208 was filed with the patent office on 2017-01-26 for decomposition system on board of a vehicle and the use thereof.
This patent application is currently assigned to Plastic Omnium Advanced Innovation and Research. The applicant listed for this patent is Francois DOUGNIER, Beatriz MONGE-BONINI, Jules-Joseph VAN SCHAFTINGEN. Invention is credited to Francois DOUGNIER, Beatriz MONGE-BONINI, Jules-Joseph VAN SCHAFTINGEN.
Application Number | 20170022864 15/301208 |
Document ID | / |
Family ID | 50424082 |
Filed Date | 2017-01-26 |
United States Patent
Application |
20170022864 |
Kind Code |
A1 |
MONGE-BONINI; Beatriz ; et
al. |
January 26, 2017 |
DECOMPOSITION SYSTEM ON BOARD OF A VEHICLE AND THE USE THEREOF
Abstract
The system for use in a vehicle, comprises a decomposition unit
(20) for at least partial decomposition of a compound under
catalysis of a biological catalyst. The system is further provided
with a storage unit (30) for storage of biological catalyst, and
with a dosing device (31) for transferring biological catalyst into
the decomposition unit (20).
Inventors: |
MONGE-BONINI; Beatriz;
(Brussels, BE) ; DOUGNIER; Francois; (Hever,
BE) ; VAN SCHAFTINGEN; Jules-Joseph; (Wavre,
BE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MONGE-BONINI; Beatriz
DOUGNIER; Francois
VAN SCHAFTINGEN; Jules-Joseph |
Brussels
Hever
Wavre |
|
BE
BE
BE |
|
|
Assignee: |
Plastic Omnium Advanced Innovation
and Research
Brussels
BE
|
Family ID: |
50424082 |
Appl. No.: |
15/301208 |
Filed: |
March 12, 2015 |
PCT Filed: |
March 12, 2015 |
PCT NO: |
PCT/EP2015/055129 |
371 Date: |
September 30, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N 2240/40 20130101;
F01N 2610/12 20130101; F01N 2610/1406 20130101; F01N 3/20 20130101;
F01N 3/2896 20130101; Y02T 10/12 20130101; F01N 2610/02 20130101;
F01N 2240/25 20130101; F01N 3/2066 20130101; Y02T 10/24 20130101;
Y02A 50/2325 20180101 |
International
Class: |
F01N 3/20 20060101
F01N003/20; F01N 3/28 20060101 F01N003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2014 |
EP |
14163103.6 |
Claims
1. A system, comprising: a decomposition unit for decomposition of
a compound under catalysis of a biological catalyst, a storage unit
for storage of the biological catalyst, and a dosing device for
transferring the biological catalyst into the decomposition
unit.
2. The system as claimed in claim 1, wherein the dosing device is
configured for transferring a liquid composition of the biological
catalyst.
3. The system as claimed in claim 2, wherein the dosing device is a
pump or a sprayer.
4. The system as claimed in claim 1, wherein the dosing device is
configured for transferring a composition of the biological
catalyst in a solid form.
5. The system as claimed in claim 4, wherein the dosing device is a
mechanical distributor.
6. The system as claimed in claim 1, wherein the storage unit is
provided with a thermal conditioner for thermally conditioning the
biological catalyst at a predetermined temperature range suitable
for preservation of the biological catalyst.
7. The system as claimed in claim 1, wherein the storage unit is
provided with a refilling inlet for the biological catalyst.
8. The system as claimed in claim 1, further comprising: a buffer
tank for containing reaction product obtained in the decomposition
unit.
9. The system as claimed in claim 1, further comprising: a thermal
conditioner for thermally conditioning the decomposition unit at a
predefined temperature range corresponding to activation of the
biological catalyst.
10. The system as claimed in claim 6, wherein the thermal
conditioner is at least one of a heater, a resistive heater, a
Peltier effect cell, an insulating element, and a phase change
material.
11. The system as claimed in claim 1, further comprising: a
controller for controlling the dosing device.
12. The system as claimed in claim 1, wherein the decomposition
unit is provided with a sensor for sensing progression of the
decomposition.
13. The system as claimed in claim 1, wherein the decomposition
unit is configured for conversion of ammonia precursor into an
ammonia composition.
14. A vehicle, comprising: the system as claimed in claim 1.
15. A method of operating a system on board of a vehicle, the
method comprising: adding a biological catalyst stored in a storage
unit into a decomposition unit through a dosing device, and
converting a compound in the decomposition unit under catalysis of
the biological catalyst.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a system for use on board in a
vehicle comprising a decomposition unit for decomposition of a
compound, for instance an ammonia precursor.
[0002] The invention also relates to a method of operating a
vehicle for the decomposition
[0003] The invention further relates to a vehicle
BACKGROUND OF THE INVENTION
[0004] A decomposition unit for ammonia precursor under the
catalysis of a biological catalyst, more particularly an urease
enzyme, has been proposed in several non-prepublished applications
(patent application EP 13182919.4 and patent application EP
12199278.8) of the Applicant that are herein included by reference.
In further investigations into such a system, the present inventors
have come up with further improvements that enable that the system
with the biological catalyst may be used over a longer period.
SUMMARY OF THE INVENTION
[0005] Accordingly, according to a first aspect, the invention
relates to a system for decomposing a compound stored on board of a
vehicle, comprising (1) a decomposition unit for at least partial
conversion of a compound into reaction product under catalysis of a
biological catalyst, (2) a storage unit for storage of biological
catalyst(s), and (3) a dosing device for transferring the
biological catalyst(s) into the decomposition unit.
[0006] According to a second aspect, the invention relates to a
method of operating a system for decomposing a composition on board
of a vehicle, comprising the steps of adding biological catalyst
stored in a storage unit into a decomposition unit through a dosing
device, and converting a compound in the decomposition unit under
catalysis of the biological catalyst.
[0007] According to a further aspect, the invention relates to the
use of a composition of a biological catalyst in liquid (fluid)
form for supply to and storage in a storage unit within a vehicle,
particularly for use in the system of the invention.
[0008] According to again a further aspect, the invention relates
to the use of a composition of a biological catalyst in solid form
for supply to and storage in a storage unit within a vehicle,
particularly for use in the system for decomposition of the
invention.
[0009] According to another aspect, the invention relates to a
vehicle comprising the system for decomposition of the
invention.
[0010] According to a further aspect, the invention relates to the
combination of the system for decomposing a compound on board of a
vehicle and a composition of biological catalyst, preferably in
solid form, such as a capsule, and for instance loaded to a storage
unit.
[0011] One embodiment of the invention is based on the insight that
the biological catalyst may be stored in a storage unit separately
from the decomposition unit, in which the catalysed conversion
occurs. The catalyst may then be applied into the decomposition
unit via the dosing device. Such application may occur from
time-to-time and is suitably under the control of a system
controller.
[0012] This separate storage of the biological catalyst turns out
to have important advantages for the effective operation. First of
all, the biological catalyst may be stored in the form of a
composition that is more easily kept stable under conditions that
preserve the biological catalyst. Secondly, the biological catalyst
is not prone to conditions in the decomposition unit that are
imposed by the first composition. In case that the first
composition is a urea composition, the pH is for instance high
(alkaline), which limits the lifetime of the catalyst. Thirdly, the
use of an enzyme storage unit allows means for refilling the
storage unit with fresh composition of biological catalyst.
Therewith a practical and commercially viable solution is
obtained.
[0013] The biological catalyst used in the invention may be
supplied as a composition either in liquid form or in solid form.
As a liquid, the composition is suitably relatively concentrated
composition and is conditioned in the storage unit at a predefined
temperature range suitable for preservation, and moreover at a
predefined and suitable pH range. The temperature range is
preferably situated between 0-55.degree. C., and more preferably
between 4.degree. C. to 22.degree. C. The pH range is preferably
between 6 and 10, and more preferably between 7 and 8.5. The dosing
device suitable for dosing of a liquid composition is for instance
a pump or a sprayer.
[0014] As a solid, the composition is even a better form of
protection of the catalyst. Moreover, a solid form may be designed
to contain a predefined amount of the biological catalyst. This
simplifies a correct dosing, and also the dosing device may be
simply in its constitution and not sensitive for pollution,
contamination and the like.
[0015] The solid form may be a powder or a powder compressed into
one or more pellets, granules or beads. Alternatively, it is in the
form of capsules, pills. The solid form may further comprise a
hydrogel encapsulating the catalyst. The solid form may be chosen
to disintegrate after entering the decomposition unit, particularly
in combination with any liquid thereon, such as a first composition
of the chemical compound. This is particularly foreseen with
powder, pellets, granules or beads. Additives may be added to
support such disintegration. Alternatively, use can be made of
capsule or pills. Those capsules or pills may be designed so that
it will not, merely slowly or partially disintegrate after feeding
into the decomposition unit. Major advantages of capsules and pills
appear that these may be provided in dimensions that allow easy
transfer. Moreover, capsules and pills may be provided with
coatings to maintain integrity and also to avoid contamination of
biological catalyst and/or its composition.
[0016] Suitably, use is made of a solid substrate onto which the
biological catalyst is immobilized. One example of a suitable solid
substrate is for instance synthetic polymers such as polystyrene,
EVOH, nylon-6 and the like. Alternatively, use may be made of
carbohydrates, such as chitosan, dextran and agarose, and porous
nanoparticles, for instance of silica. The capsules and/or other
solid forms are preferably provided with a diameter in the range of
10 microns-10 cm, preferably 1 mm-1 cm, so as to handle them
individually. However, capsules may further be provided with a
liquid composition of biological catalyst inside.
[0017] Preferably, the dosing device is driven by a system
controller. The system controller may receive input on various
conditions inside or outside the storage and conversion system, and
is suitably configured to control the dosing device on the basis
thereof. Examples of conditions are the time lapsed since a
preceding dosing into the decomposition unit; the temperature
outside and/or the temperature inside the decomposition unit, the
chemical composition at an outlet of the decomposition unit and/or
an inlet of a subsequent reactor (i.e. unit), for instance a fuel
cell or an exhaust gas line. One or more sensors are suitably
present to provide such or other input to the system controller.
Furthermore, the system controller is suitably provided with a
clock and with a memory, wherein for instance, the concentration of
the biological catalyst in the storage unit may be stored. The
invention also encompasses a control method, wherein the dosing
device is controlled on the basis of input from such sensor and/or
other information, such as the loading of the decomposition
unit.
[0018] Preferably, the decomposition unit is provided with
distribution means for distribution of the biological catalyst with
the first composition. One example of such distribution means is
agitation means, such as a stirrer. Alternatively, the distribution
means are devices defining flow behaviour within the decomposition
unit, for instance a split into a first reactor for mixing and a
second reactor for continued reaction. Furthermore, use may be made
of a plurality of catalysts for catalysis of a multistep reaction.
The biological catalysts may herein be provided as a mixture, or
separately. The decomposition unit could comprise a first and a
second chamber that are provided in series, and wherein a first
catalyst for a first reaction step is provided in the first chamber
and wherein a second catalyst for a second reaction step is
provided in the second chamber.
[0019] In operating the storage and conversion system, the
biological catalyst may be added to the decomposition unit either
during operation of said decomposition unit, or alternatively
before operation of the decomposition unit is resumed, particularly
in the case of batch-wise operation of the decomposition unit.
[0020] In a preferred embodiment, the storage unit is further
provided with an inlet (also called refilling inlet) for a
composition of the biological catalyst. This inlet is particularly
intended for refill of the storage unit. In one embodiment, the
inlet is an inlet for manual addition of biological catalyst. Such
an inlet may be analogous to other inlets present in a vehicle,
such as for cooling liquid, oil and the like. The inlet may be
coupled to a pipe having an opening which is accessible from an
outside of a vehicle. In one further embodiment hereof, the storage
unit may be refilled with biological catalyst originating from a
tank that is located externally to the storage and conversion
system. Such tank may be present within the vehicle, but
alternatively the tank may be present outside the vehicle, for
instance as part of a petrol station. The external tank may herein
be provided with a pump and means for transfer of metered
quantities into the storage unit (or into a secondary enzyme tank
within the vehicle).
[0021] In again a further embodiment, the storage unit for the
biological catalyst or a composition thereof is provided with means
for thermally conditioning. Furthermore, in one embodiment, the
method of the invention comprises the step of thermally
conditioning the storage unit for the biological catalyst.
[0022] The conditioning means may comprise e.g. a heater and/or a
cooler. Suitably, the conditioning means furthermore comprise a
thermally insulating encapsulation, such that the temperature can
be most easily kept within the desired temperature range
independent of the outside temperature and/or the generation of
heat upon use of the combustion engine. Optionally, a cooler may be
present, so as to lower the temperature in the decomposition unit
in case the environmental temperature would be higher.
[0023] The heater comprises, in a particular implementation,
resistive heating elements, for instance in the form of metallic
heating filaments (wires), flexible heaters (i.e. heaters
comprising one or more resistive track(s) affixed to a film or
placed between two films, or any other type of resistive elements.
PTC (positive temperature coefficient) elements are more
particularly suitable for heating. Peltier effect cells constitute
another example.
[0024] In a further embodiment, heat may be transmitted to the
storage unit from heat sources within a vehicle, such as fuel
cells, internal combustion engine, exhaust line. Means for heat
transmission are known per se and include, for instance, heat
pipes, heat pumps, heat exchangers.
[0025] In one further implementation, the storage unit for the
biological catalyst is provided with a temperature sensor and the
system is provided with control means. The control means are herein
configured to control the conditioning means. The control means are
suitably configured, in one embodiment, to control the temperature
in the storage unit in a predetermined temperature range
corresponding to preservation of the biological catalyst. In one
specific implementation, the control means herein control that the
temperature in the enzyme storage unit remains above a minimum
temperature, for instance to prevent freezing of the biological
catalyst. In one implementation, the method of the invention
comprises the step of sensing a temperature in the vehicle, for
instance in or near the storage unit, and controlling the thermal
conditioning means on the basis of the sensed temperature.
[0026] In again a further embodiment, the decomposition unit is
also provided with means for thermal conditioning. Such means for
thermal conditioning may be principally the same, but with the
difference that the temperature in the decomposition unit will
typically be at another temperature range than in the storage unit
for biological catalyst. Furthermore, in one embodiment, the method
of the invention comprises the step of thermally conditioning the
decomposition unit at a predefined temperature range suitable for
activation of the biological catalyst. This temperature range is
suitably 30-70.degree. C., for instance from 40-60.degree. C.
[0027] The location of the decomposition unit and the storage unit
is open to further design. In a particular embodiment, the
decomposition unit can be suitably located in an upper part of the
tank or can be mounted on top of the tank. If the decomposition
unit is present in an upper part of the tank, it may be mounted on
a mounting flange. In another particular embodiment, the
decomposition unit can be suitably located in a bottom part of the
tank or can be present below the tank or adjacent to the tank. It
is deemed suitable that the decomposition unit and the tank
constitute a joint assembly in view of thereof that the
decomposition unit is effectively an accessory to the tank.
However, this is effectively not strictly necessary.
[0028] The storage unit for biological catalyst is suitably located
in an upper part or on top of the decomposition unit. However, in
view of the foreseen difference in temperature between the
decomposition unit and the storage unit, the storage unit is in one
suitable embodiment located externally to and at a distance from
the decomposition unit. For instance, the storage unit may be
mounted to an inlet pipe for the first composition, such as petrol
or an ammonia precursor. A connecting pipe will then be present
between the storage unit and the decomposition unit for supply of
the biological catalyst composition from the storage unit. The
dosing device may be located at any location between the storage
unit and the decomposition unit, for instance at an outlet of the
storage unit, but alternatively at the end of the connecting
pipe.
[0029] The decomposition unit may be operated batchwise or in a
continuous manner. Suitably, use is made of batch-wise operation.
Preferably, the control occurs by means of a time-control device or
a chemical sensor for control of the conversion. A time-control
device can be a clock or any timing mechanism driven by a motor, by
the vehicle electronic system or by another mean known by the
status of the art. A chemical sensor device can be for example a pH
sensor. When the conversion is complete, for instance, when 50% or
ideally 80% of the first composition is converted into product, the
resulting effluents may be transferred out of the decomposition
unit.
[0030] Furthermore, a buffer tank may be present for containing
reaction product of the biochemical conversion by means of the
biological catalyst. The size of the buffer tank may be chosen in
dependence on the specific application and the flow rate of
reaction product.
[0031] The system of the invention is suitably provided with a tank
for storing the compound to be decomposed prior to entry into the
decomposition unit. A fluid transfer device may be present for
transferring the compound or a composition thereof from the tank to
the decomposition unit. A fluid transfer device can be for example
a pump, valve, combination of both, gravity, gravity in combination
with a valve or a valve in combination with whatever system known
by the state of the art to transfer liquid. In one preferred
embodiment, the method of the invention thereto comprises the steps
of: transferring the compound and/or a composition thereof into the
decomposition unit according to an amount and/or flow rate, and
dosing the biological catalyst in dependence on the transferred
amount of the compound.
[0032] In one preferred embodiment, the compound is an ammonia
precursor, such as for instance urea. The ammonia precursor is
suitably present as a composition, such as an aqueous composition,
more particularly a concentrated aqueous composition. Suitably, the
composition is a concentrated urea solution of at least 10% urea.
In this embodiment, the reaction products may be for instance
ammonia or hydrogen suitable for use in either selective catalytic
reduction (SCR) methods for purifying exhaust gases or for fuelling
fuel cells operating on the basis of hydrogen. Suitable biological
catalysts are herein urease. In a further embodiment of the vehicle
of the invention, an outlet of the system is coupled to an exhaust
gas line for selective catalytic reduction (SCR) of exhaust gases.
In an alternative embodiment, an outlet of the system is coupled to
a unit for conversion of the ammonia composition into hydrogen for
fuelling a hydrogen fuel cell.
[0033] In an alternative embodiment, the compound is a hydrogen
precursor. Suitably hydrogen precursors include polysaccharides
such as cellulose, monosaccharides such as glucose or ammonia and
ammonia adducts such as ammonia borane. It is not excluded that the
decomposition involves a biochemical conversion of any other
compound present in a car so as to remove waste or modify any
composition. The biological catalysts are suitable enzymes, that
may be isolated or be present as part of living microorganisms that
are feasible of producing enzymes for the biochemical
conversion.
[0034] More particularly, the system of the invention is designed
for and use on board of a vehicle, including cars, trucks and
motors, using ether gasoline, diesel and optionally being a hybrid
type that can also be driven on fuel cells. The system of the
invention is thereto suitably coupled to an engine or to an SCR,
and is operative during use of the vehicle.
[0035] The invention further relates to the refilling of the
storage unit with a composition comprising the biological catalyst,
as well as a petrol station provided with a catalyst tank and
provided with means for refilling of a storage unit in a vehicle.
The petrol station may further comprise dosing device metering the
amount of the composition of biological catalyst provided to a
vehicle. The petrol station may further be provided with display
means for displaying the amount of the composition, as well as
means for transmitting the provided amount to a payment terminal.
The provision of a storage unit for the biological catalyst
composition allows efficient organisation of logistics for the
provision of the biological catalyst composition. In one suitable
embodiment, the refilling of the storage unit external to the
decomposition unit could be arranged in a petrol station, in a
manner corresponding to existing refilling of liquid compositions,
such as urea solutions and fuels. Alternatively, the refilling may
occur in a manner similar to the provision of motor oil.
[0036] In one embodiment, such means for refilling of the storage
unit with a biological catalyst composition may be coupled to means
for refilling a tank of the first composition, for instance an
ammonia precursor solution. The coupling is suitably a mechanical
coupling of a first filling pipe and a second filling pipe. This
reduces the number of different refilling operations needed by a
customer. Moreover, the amount of biological catalyst composition
may be defined on the basis of the amount of the other composition,
such as the urea composition. The vehicle is most suitably equipped
with filling means, such as a pipe exposed at an outside of the
vehicle.
[0037] The features set out above for the first aspect of the
invention may also be applied to the other aspects.
BRIEF DESCRIPTION OF THE FIGURES
[0038] The above and other advantages of the features and objects
of the invention will become more apparent and the invention will
be better understood from the following detailed description when
read in conjunction with the accompanying drawings, in which:
[0039] FIG. 1 shows a first embodiment of the system of the
invention;
[0040] FIG. 2 shows a second embodiment of the system of the
invention;
[0041] FIG. 3 shows a third embodiment of the system of the
invention;
[0042] FIG. 4-6 shows further implementations of the system of the
third embodiment;
[0043] FIG. 7 shows a fourth embodiment of the system of the
invention;
[0044] FIGS. 8(a) and (b) show a first and a second operation stage
in the operation of a fifth embodiment of the system of the
invention.
DESCRIPTION OF EMBODIMENTS
[0045] The figures are not drawn to scale, and of purely
diagrammatical nature and show the storage and conversion systems
according to various embodiments in schematical cross-sectional
views. Equal reference numerals in different figures refer to equal
or corresponding parts. The system of the invention will be
illustrated in the FIGS. 1-8 hereinafter in relation to
embodiments, wherein the tank is configured for containing an
ammonia precursor as the first composition. This ammonia precursor
is for instance an urea solution, more particularly a concentrated
urea solution of at least 25 wt % urea, more preferably a urea
solution of around 32.5 wt % urea. The term "urea solution" is
understood in the context of the present invention, to mean any,
generally aqueous, solution containing urea. The invention gives
particularly good results with eutectic water/urea solutions for
which there is a quality standard; for example, according to the
standard ISO 22241, in the case of the AdBlue.RTM. solution (a
commercial solution of urea), the urea content is between 31.8% and
33.2% (by weight), hence an available amount of ammonia between
18.0% and 18.8%. While the invention is further illustrated with
reference to an urea composition, this is merely a specific
example. The ammonia precursor may be different. Moreover, the
invention may also be applied to other compounds on board of a
vehicle that need conversion, such as the conversion of ammonia
and/or other hydrogen precursors into hydrogen for fuel cells.
[0046] Generally, such urea solution is stored in a container
mounted on the vehicle. The urea solution is injected in the
exhaust line, after which the urea will thermally decompose into
gaseous ammonia. However, in case of a cold start, the injection of
urea into the exhaust gas line does not function appropriately.
First of all, the urea may be frozen and it would take some time to
thaw it, even when using a heater. Moreover, in order to avoid
deposits in the exhaust pipe, aqueous urea solution should not be
injected into the exhaust pipe before the exhaust gases have raised
the temperature of the exhaust pipe to a sufficient temperature,
typically in the range of 180-200.degree. C. Therefore, the urea
solution is to be converted into ammonia, at least partly, so that
sufficient ammonia is available in case of a cold start and/or in
any other desired situation.
[0047] This ammonia precursor is converted into ammonia, in
accordance with the invention under catalysis of a biological
catalyst. The ammonia may be used in various applications, among
which selective catalytic reduction, also known as SCR, and the
conversion to hydrogen for fuel cells. Particularly in case of the
SCR application, the conversion of urea into ammonia may be
necessary only occasionally. Therefore, it is preferred that the
biological catalyst is stored in a manner which provides an
appropriate protection. This manner is most suitably provided by
means of the storage unit separately from the decomposition unit,
and even more preferably, by means of storing the biological
catalyst composition therein in a solid form.
[0048] This urea composition is transferred in liquid form to the
decomposition unit, which is thus a liquid reactor.
[0049] The system of the invention can be further used to convert
(i.e. decompose) fuel vapour. In this last example, the
decomposition unit operates as a gas converter, i.e. a gas
reactor.
[0050] However, the invention is not limited to the said
embodiments and variations and alternative applications may be
apparent to the skilled person.
[0051] FIG. 1 shows in cross-sectional schematical view a first
embodiment of the storage and conversion system of the invention.
The system is intended for incorporation into a vehicle. Such a
vehicle is suitably a so-called hybrid vehicle that is provided
with both a combustion engine and a fuel cell 51. However, the
system is not limited thereto.
[0052] The system of the first embodiment comprises a tank 10 for a
urea composition. For sake of simplicity, the tank 10 will
hereinafter also be referred to as urea tank 10. The system further
comprises a decomposition unit 20, a buffer tank 23, a conversion
unit 50 for conversion of ammonia into hydrogen and a fuel cell 51.
Fluid transfer devices FTD1, FTD2, FTD3 are present so as to
transfer the urea composition. The fluid transfer device FTD1 is
configured for transfer of liquid in particular. It is however not
excluded that the first composition may be contain solids and/or
vapour. The fluid transfer devices FTD2 and FTD3 are in this
embodiment configured for the transfer of gas or liquid, more
particularly ammonia or aqua ammonia (i.e. reaction product). In
the context of the present application, the term "aqua ammonia" is
to mean a mixture of effluents resulting from the decomposition of
an ammonia precursor. This mixture of effluents may contain
ammonium hydroxide (a fraction of which is ionized), residue of
ammonia precursor (i.e. part of the ammonia precursor that has not
been decomposed) and eventually other products (such as ammonium
bicarbonate).
[0053] In this and following embodiments, the decomposition unit 20
and the buffer tank 24 are present within the urea tank 10. This is
deemed a practical implementation, though this is not necessary. An
alternative assembly is for instance one wherein the urea tank 10,
the decomposition unit 20 and the buffer tank 23 are all part of a
common assembly, which may be in the form of a further shell, such
as a plastic shell of any suitable engineering material. While the
present FIG. 1 and any further figures show the size of the
decomposition unit 20 and the buffer tank as substantially equal
and of similar shape, this is not deemed necessary.
[0054] According to one preferred embodiment of the invention, a
storage unit 30 for a biological catalyst composition is provided.
The storage unit 30 is herein located on top of the decomposition
unit 20. It is provided with dosing device 31 at its outlet 39. The
storage unit 30 is further provided with an inlet 38 suitable for
filling and refilling the storage unit 30 with a storage form 101
of biological catalyst. In this embodiment, the storage form is a
liquid composition 101, more generally a dispersion. The liquid
composition 101 is suitably concentrated relative to the
concentration needed in the decomposition unit 20. The dosing
device 31 is in one implementation embodied as a liquid pump. A
liquid pump, possible with a nozzle such as used in inkjet printers
is deemed suitable. The dosing device 31 may be further provided
with an inlet for a diluting agent, suitably an aqueous diluting
agent. The addition of such diluting agent may be suitable for a
better dispersion of the biological catalyst, and may moreover be
beneficial in the prevention of stoppage at an outlet, particularly
any nozzle, of the dosing device 31. As a result of the dosing
device 31, a dispersed composition 102 of the biological catalyst
will be entered into the decomposition unit. While not shown in the
present FIG. 1, it is deemed beneficial if the decomposition unit
is provided with agitation means. The decomposition unit 20 is
furthermore provided with an inlet 28 at which the urea composition
will enter and an outlet 29. Thermally conditioning means 21, 22
are provided so as to arrange that the decomposition unit can be
held at or can be brought to a predefined temperature within a
temperature range suitable for activation of the biological
catalyst. The thermally conditioning means herein comprise a heater
21 and one or more further thermally conditioning elements 22. The
heater 21 is suitably provided in the form of a flexible wire. This
has the advantage that the heat may be distributed within the
decomposition unit 20. The at least one thermally conditioning
elements are in the present embodiment one or more layers of
thermally insulating material. While it is deemed most beneficial
that such thermally insulating material is present at all walls of
the decomposition unit 20, it may be sufficient when this layer 22
is present on the side, wherein the decomposition unit 20 is
potentially faced to a cold temperature, or rather a high
temperature. It is foreseen that these sides are the bottom side
(for the cold environment) and the side facing a combustion engine
(in case that this is located adjacent to the urea tank 10).
[0055] FIG. 2 shows in cross-sectional view a second embodiment of
the storage and conversion system of the invention. Herein the
storage unit 30 for biological catalyst is located separately from
the decomposition unit 20. Furthermore, thermal conditioning
elements 32 are present in the storage unit 30. These thermal
conditioning elements 32 suitably are embodied as thermally
insulating material, such as known per se. However, it is not
excluded that the thermal conditioning elements 32 also or even
alternatively comprise a heater, which may be also take the form of
a heat pump or the like. While the presence of thermal conditioning
elements 32 is highly preferred, their presence is not deemed
necessarily. For instance, any heating elements in the urea tank 10
may have the effect that the storage unit 30 is sufficiently warmed
so as to prevent destruction of the biological catalyst.
[0056] FIG. 3 shows in cross-sectional view a third embodiment of
the storage and conversion system of the invention. According to
this embodiment, the storage unit 30 for biological catalyst is
located outside the tank 10. A connecting pipe 35 is present for
connecting the outlet 39 of the storage unit 30 with the
decomposition unit 20.
[0057] FIG. 4-6 show further implementations and variations of the
third embodiment as shown in FIG. 3. Herein, the storage unit 30
for biological catalyst is mounted to a tank filler pipe 40.
Besides the advantage of a stable assembly, this mounting has the
advantage that the storage unit 30 may be filled and refilled close
to the filling entry for the urea composition. In one embodiment,
the refilling of the storage unit 30 may be carried out
simultaneously with the refilling of the tank 10 with the urea
composition. Thereto, refilling means may be provided with a first
pipe for the storage form of biological catalyst and with a second
pipe for the urea composition. The first pipe and the second pipe
may also be integrated into a single armature. In the FIGS. 4-6,
the enzyme filling pipe 33 is replaced by an enzyme access port 34,
with which the storage unit can be opened and closed. It will be
understood that a combination is feasible; i.e. the storage unit 30
could be located intermediate to the enzyme access port 34 and the
tank 10.
[0058] The embodiments of FIG. 4-6 differ in the location of the
dosing device 31. In FIG. 4, the dosing device 21 is provided
directly at the storage unit 30. A connecting pipe 35 connects the
outlet of the dosing device to the decomposition unit. This
implementation has the advantage that the storage form 101 of the
composition with biological catalyst may be diluted prior to its
transfer. As a result, there is a reduced risk that a major portion
of the biological catalyst ends up at the surface of the connecting
pipe 35 rather than in the decomposition unit 20.
[0059] In FIG. 5, the dosing device 31 is mounted to the tank 10,
and/or to the tank filler pipe 40. This has the advantage of
providing a stable assembly. Moreover, the mounting to the tank 10
and/or the tank filler pipe 40 allows the provision of any heating
means or the like to the dosing device 31. Warming up the dosing
device and the storage form 101 of the biological catalyst will
reduce the viscosity of the composition and prepares the biological
catalyst for its entrance into the decomposition unit 20. It is not
excluded in this embodiment that the first connecting pipe 351 to
the dosing device 31 is herein provided with an inlet for a
diluting agent, such as an aqueous solution. A second connecting
pipe 352 thereafter connects the outlet of the dosing device 31 to
the decomposition unit 20.
[0060] In FIG. 6, the connecting pipe 35 is connected into the tank
filler pipe 40 rather than into the decomposition unit 20.
Moreover, the tank filler pipe 40 is arranged to insert the urea
composition into the decomposition unit 20 directly. This
decomposition unit is moreover provided with a check valve 24, i.e.
with overflow means such that upon a predefined filling level of
the decomposition unit 20 with urea composition, this urea
composition will be transferred into the tank 10. Rather than a
check valve 24 (overflow means), the connection between the
decomposition unit 20 and the tank 10 could be embodied
differently, for instance in the form of a (conventional) valve
driven by a controller (not shown) such that when filling the tank
10, such valve will be opened, and otherwise it will be closed. The
operation of the system according to this embodiment is the
following: a sensor, such as a level sensor will detect a level of
urea composition in the decomposition unit 20. If the sensed level
exceeds a predefined level, a controller may provide a driving
signal to the dosing device 31, so as to introduce biological
catalyst into the decomposition unit 20.
[0061] FIGS. 7 and 8 show further embodiments of the storage and
conversion system of the invention, again in schematic
cross-sectional views, wherein the storage form of the biological
catalyst is a solid form 100. Such storage form 100 is highly
beneficial for the preservation of the biological catalyst. The
solid form is for instance a dry, powdered form. Alternatively, the
solid form may be a capsule. The term `solid form` is intended to
cover in the context of the present invention both capsules
encapsulating biological catalyst in solid form, as well as
capsules encapsulating biological catalyst in liquid form.
Capsules, powders, granules, pills are known solid forms well known
in the field of food and pharmaceuticals. Furthermore, even
detergents may be provided in solid forms. Carriers and processing
methods, as well as encapsulating materials are known per se. A
well known carrier is for instance microcellulose, while
alternatives such as starch, including modified starches, other
forms of cellulose, and other polysaccharides may be applied as
well. Additives such as glycerol may be added for optimum
processing. The solid material may be pressed or extruded.
[0062] FIG. 7 shows an embodiment, wherein the solid form 100 is a
powder, that may further be processed into granules, pills or the
like. The storage unit 30 is provided at its outlet 39 with a
dosing device 31 suitable for a powder. Such dosing device are
known per se. In addition to the dosing device 31, a dispersing
means 36 is present that is able to disperse and/or distribute the
biological catalyst into the biochemical convert 20. The dispersing
means may disperse the biological catalyst as a dispersion or
alternatively as a finely divided powder.
[0063] FIG. 8(a) and FIG. 8(b) show two phases in the operation of
a dosing device 31 for capsules. The dosing device 31 is herein
provided with a cavity 311 suitable to contain a predefined number
of capsules, in the present example 1 capsule. The dosing device 31
is further provided with means for rotating as known per se (not
shown). These rotating means allow the dosing device 31 to rotate
the cavity 311 from its top side (shown in FIG. 8(a)) to its bottom
side (shown in FIG. 8(b)). At the bottom side, the capsule 100 will
be released from the cavity and enter the decomposition unit
20.
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