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).

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

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 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 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.