Field of the Invention

The present invention relates to a fuel cartridge.

Furthermore the present invention relates to a catalytic heating system comprising a catalytic burner for fiameless catalytic combustion of a fuel gas in a combustion chamber, the catalytic burner comprising a tubular main catalyst with a first length, the main catalyst being in communication with a gas inlet of the combustion chamber for supply- ing a mixture of air and fuel gas to the main catalyst.

Background of the Invention

A catalytic heating system for fiameless catalytic burning of fuel gas in a combustion chamber is known from WO 2009/003481. The catalytic heating system comprises a catalyst which is in communication with a gas inlet of the combustion chamber. The catalyst is heated to a temperature sufficient for triggering the catalytic combustion of the fuel gas. The catalyst is located in a combustion chamber defined by a heating pipe. The fuel gas enters the combustion chamber in the central part of the heating pipe at a first end of the combustion chamber, and the exhaust emissions exit at the same end through an annular cavity between the inner wall of the heating pipe and the catalyst. During steady state catalytic combustion in the heating system of WO 2009/003481, a pronounced chimney effect is present. The chimney effect will cause the fuel gas to be sucked through the main catalyst and not reach the end of the main catalyst. This prevents complete combustion of the fuel gas. The speed of the fuel gas is increased by the chimney effect, and the amount of unburnt fuel gas and carbon monoxide is increasing due to the catalyst having a set capacity per area. In an embodiment of WO 2009/003481, the catalyst is a truncated cone, wherein the fuel gas is applied to the narrow end of the catalyst. The reduction of gas flow reduces the catalytic burning towards the narrow end of the catalyst, and an increase of gas flow will increase the catalytic burning towards the wide end. Although, this has been a successful means for controlling the heating effect of the catalytic heating system of WO 2009/003481, it has shown that the carbon monoxide emissions are too high for equipment to be carried by personnel and used in small spaces, for example, tents. A further disadvantage of the heating system of WO 2009/003481 is that the heating radiation will be concentrated at one end of the heating pipe. Therefore, the media to be heated may have to be stirred to be evenly heated. Furthermore, the condensed water, which is a by product of the catalytic combustion, may gather in the combustion chamber at and end opposite to the first end.

Object of the Invention

The objective of the present invention is to provide a catalytic heating system, wherein the catalytic combustion of the fuel gas is optimized such that carbon monoxide emissions are reduced.

Description of the Invention

According to the present invention, this objective is achieved by a catalytic heating system comprising a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber. The catalytic burner comprises a tubular main catalyst with a first length, the main catalyst being in communication with a gas inlet of the combustion chamber for supplying a mixture of air and fuel gas to the main catalyst. In addition, a non-catalytic gas distributor is arranged downstream of the gas inlet and inside the main catalyst for distributing the mixture of air and fuel gas inside the main catalyst. It is herewith achieved that the fuel gas can be distributed over the entire length of the main catalyst. Therefore, the area utilised for the catalytic combustion is maximised. Hence, the catalytic combustion of the fuel gas is more complete, because the same amount of gas is distributed across a larger area, which reduces the speed of the gas through the main catalyst. The catalytic combustion is more complete, reducing the amount of unburnt fuel gas and carbon monoxide emissions in the exhaust. Furthermore, the heat radiation from the catalytic burner is distributed along its entire length. A media to be heated by the heating system is, therefore, heated more effectively. As an even further advantage, the presence of condensate at the end of the com- bustion chamber opposite the exhaust is avoided.

Medias to be heated may include liquids, for example, water; liquids containing solids, for example, food rations or canned food; solids, for example, ice; or powder, liquid solutions containing, for example sugar, salt or other minerals and other additives, liq- uids for infusion into the body of a human or animal, blod. Furthermore, the heating system may be used for personnel heating.

The gas distributor, also, counteracts the negative effect of the chimney effect. The gas distributor ensures that the fuel gas reaches the end of the main catalyst, so that fuel gas is distributed across the entire area over the length of the catalyst. Thereby, the main catalyst has a higher combustion efficiency.

The gas distributor is non-catalytic, and, therefore, the fuel gas is not combusted until after it is released from the gas distributor. A suitable non-catalytic material may be stainless steel.

The gas distributor may have a constant or variable cross-section along its length. The cross-sectional shape may circular, polygonal, elliptical, or a combination; or it may have a variable cross-section along its length.

The main catalyst is arranged in a combustion chamber, which may be defined inside a heating pipe that is transparent to IR radiations. The heating pipe may then be submerged in a container containing the media to be heated. This is a very efficient way of heating the media, because less heat is dissipated outside the media. The heat dissipated outside the media is mainly the heat dissipating through the exhaust from the catalytic combustion. The container may have means for recirculation of the heated media in conduits outside the container. For example in a domestic heating system.

An exhaust cavity is defined between the catalytic burner and an inner wall of the com- bustion chamber. The exhaust is directed out of the combustion chamber through this exhaust cavity to an exhaust outlet. The exhaust outlet is, preferably, configured for directing the exhaust past the fuel gas supply. This is an advantage, if the fuel is stored as a liquid and evaporated on its way to the combustion chamber. The hot exhaust exchanges heat with the fuel gas supply, which is cold due to the energy required to evaporate the fuel gas. It is, herewith, achieved that the exhaust temperature is decreased, which will decrease the thermal signature and traceability of the heating system.

In a preferred embodiment, the gas distributor is a frusto-conical tube having a first, wide end and a second, opposite, narrow end, the wide end having a larger cross section than the narrow end. The wide end has a first opening facing the gas inlet. The gas distributor has a second length between the wide and the narrow ends. The distribution of the fuel gas is, preferably, even along the length of the main catalyst, such that the combustion is taking place evenly over the entire length of the main catalyst. In order to achieve this, the gas distributor has a plurality of openings along its length. Due to its frusto-conical shape, the cross-sectional area is decreasing towards the end of the gas distributor. Therefore, the gas is forced to flow out of the openings and is distributed along the length of the main catalyst. Alternatively or in addition to the openings along its length, the gas distributor may, optionally, have a second opening at the nar- row end for release of fuel gas. The speed of the fuel gas will increase towards the narrow end according to Bernoulli's theory. The inertia of the fuel gas is, therefore, increased, which will delay the chimney effect and allow the fuel gas to penetrate further into the main catalyst, before it is being sucked through the main catalyst.

According to a further preferred embodiment, the gas distributor is a mesh. This embodiment is designed for ease of manufacture in that it provides a simple way of manufacturing the gas distributor. In a preferred embodiment, the gas distributor is a frusto-conical mesh, for example, with a plurality of evenly distributed openings along its length. Optionally, it not only has a first opening at its wide end, but also a second opening at its narrow end. According to a further embodiment, the second length of the gas distributor is smaller than the first length of the main catalyst. It is, herewith, achieved that the fuel gas is distributed to the inside and not the outside of the main catalyst. It is, hereby, ensured that the fuel gas is combusted with high efficiency. According to a further embodiment, the main catalyst or the gas distributor or both have a circular cross-section. The circular cross-section provides an even heat radiation and flow inside the combustion chamber.

According to a further embodiment, the catalytic burner further comprises a slide bear- ing, wherein the slide bearing is a frusto-conical tube with a narrow end and a wide end, the narrow end being connected to the main catalyst, and wherein the wide end of the slide bearing is slidably arranged in the combustion chamber. Due to the catalytic reaction, the main catalyst will reach a temperature of 400 to 700 °C. This causes a thermal expansion of the main catalyst. The main catalyst may therefore be fixed to the structure of the heating system at one end and be slidingly supported at the other end to allow the thermal expansion of the main catalyst. The introduction of a slide bearing at the free end provides support of the free end of the main catalyst, such that it is resistant to shock and impact to the heating system. The heating system may, therefore, be used in rough conditions, for example, extreme sports, mountaineering, or military use.

This may also improve the reliability and life of a catalytic heating system used for stationary applications, for example a domestic heating system. The wide end of the slide bearing may be slideably abutting an inner tubular wall of the combustion chamber. Apart from taking up the thermal expansion, the slide bearing may also seal the end of the main catalyst, such that unburnt fuel gas is returned to the main catalyst and unable to reach the exhaust without passing through the main catalyst.

A slide bearing is also advantageous for other catalytic systems than the catalytic sys- tern described above. A slide bearing of this kind may be used for prior art systems, for example as disclosed in International patent application WO2009/003481. Thus, independently of the above catalytic system, an invention has been found in a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber, wherein the catalytic burner comprises a tubular main catalyst and a slide bearing in the form of a frusto-conical tube connected at its narrow end to the main catalyst. In addition, the wide end of the slide bearing is slidably arranged in the combustion chamber. Optionally, The wide end of the slide bearing may be slideably abutting an inner tubular wall of the combustion chamber. According to a further preferred embodiment, the heating system according to the invention is peculiar in that the catalytic burner further comprises a mixing chamber for mixing fuel gas and air. The mixing chamber has a mixing chamber inlet and a mixing chamber outlet and is arranged between the gas inlet and the gas distributor for guiding a mixture of fuel gas and air into the gas distributor. The mixing chamber ensures that the mixture of fuel gas and air is homogenous when it enters the gas distributor and main catalyst. This is important in order to achieve a complete combustion of the fuel gas.

It should be mentioned here that this mixing chamber for mixing fuel gas and air is not only advantageous for the catalytic system as described above but can also advantageously be incorporated in other systems, for example, as disclosed in International patent application WO2009/003481 or other prior art systems. Thus, independently of the above catalytic system, an invention has been found in a heating system that comprises a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber, the catalytic burner comprising a tubular main catalyst and a mixing chamber for mixing fuel gas and air. The mixing chamber has a mixing chamber inlet and a mixing chamber outlet, wherein the mixing chamber inlet is in communication with a gas inlet of the combustion chamber, and wherein the mixing chamber outlet is connected to the main catalyst for guiding a mixture of fuel gas and air into the main catalyst. A homogeneous mixture of fuel gas and air will provide a more complete combustion of the fuel gas. According to a further preferred embodiment, the gas inlet comprises a venturi system with a nozzle means, and wherein the nozzle means extend past the mixing chamber inlet into the mixing chamber. A venturi system comprises no moving parts; therefore, it is reliable in providing air and hence oxygen to the fuel gas for the combustion process. The nozzle extending into the mixing chamber allows the unburnt fuel gas to pene- trate further into the main catalyst.

According to another preferred embodiment, the mixing chamber comprises a thin- walled mixing chamber tube connected to the gas distributor and extending to the gas inlet for guiding a mixture of fuel gas and air from the gas inlet into the gas distributor. The term "thin- walled tube" is to be understood as a tube having a wall thickness to diameter ratio of approximately 1 : 300. An embodiment of the invention has a thin- walled mixing chamber tube with an inner diameter of 0 15 mm and a wall thickness of 0.05 mm. A preferred material is metal, for example stainless steel. A thin-walled mixing chamber tube will conduct less heat in a direction along the tube than a comparably thicker wall. Hence, a thin- walled tube will limit the heat conduction from the combustion chamber through the mixing chamber tube to the remainder of the heating system. This reduces the heating of the fuel gas prior to it entering into the main catalyst and thus, reduces the expansion of the fuel gas due to heating that would otherwise reduce the effect of the heating system

According to yet another embodiment, the heating system according to the invention is peculiar in that the catalytic burner further comprises a thin-walled insulation tube arranged about the mixing chamber and with a cavity between the insulation tube and the mixing chamber for providing thermal insulation of the mixing chamber. The thin- walled insulation tube, typically made of metal, for example steel, limits the heat transmission from the combustion chamber further upstream of the heating system. Furthermore, it limits the heat transmission from the exhaust cavity to the mixing chamber. It is preferable to avoid heating the fuel gas prior to it entering into the main catalyst, because the fuel gas will expand when heated and reduce the effect of the heating system. According to a further preferred embodiment, the heating system further comprises a starter system for initiating the catalytic combustion, the starter system comprises an electrically conductive starter-catalyst having an initiator portion and an igniting portion, and an electrical power source connected to the starter-catalyst, for causing electrical current to flow through the starter-catalyst and thereby heating the initiator por- tion to a temperature for triggering the catalytic combustion at the igniting portion and thereby heating the igniting portion to a temperature for triggering the catalytic combustion at the main catalyst, wherein the initiator portion is substantially smaller than the igniting portion, and wherein the igniting portion is substantially smaller than the main catalyst.

It is a problem with the electric starter systems of prior art catalytic burners that they are unable to heat the main catalyst sufficiently to achieve a temperature where the catalytic combustion will start in severe cold conditions. In such a case, it is necessary to increase the area of the starter-catalyst. However, this is at the expense of increased power consumption and a requirement for the starter system to supply a higher current. For a portable system with a battery, this causes a shorter life time of the battery and/or requires a larger battery adapted to the conditions.

This problem is solved by providing the starter system with a stepwise triggering starter-catalyst having two portions. Only a small part of the starter-catalyst, namely an initiator portion, needs electrical heating, whereas, the remaining part of the starter- catalyst, namely an igniting portion, is heated by the catalytic reaction at the initiator portion without the need for application of electrical power. Such a two-step starting system will, as a third step, be able to trigger the catalytic combustion at the main cata- lyst in severe cold conditions with low power consumption. The step wise ignition principle can be extended to further stages. Thus, in an alternative embodiment, the starter-catalyst comprises a plurality of igniting portions of a gradually increased size. It should be mentioned here that this stepwise starter system with an initiator portion and an igniting portion is not only advantageous for the catalytic system as described above but can also advantageously be incorporated in other systems, for example, as disclosed in International patent application WO2009/003481 or other prior art systems. Thus, independently of the above catalytic system, an invention has been found in a heating system that comprises a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber, the catalytic burner comprising a main catalyst, preferably tubular, and a starter system for initiating the catalytic burning. The starter system comprises an electrically conductive starter-catalyst having an initiator portion and an igniting portion and an electrical power source connected to the starter-catalyst for causing electrical current to flow through the starter-catalyst and thereby heating the initiator portion to a temperature for triggering the catalytic combustion at the igniting portion and thereby heating the igniting portion to a temperature for triggering the catalytic combustion at the main catalyst. The initiator portion is substantially smaller than the igniting portion, and the igniting portion is substantially smaller than the main catalyst. A starting system with a significantly improved capability to trigger the catalytic combustion at the main catalyst in severe cold conditions is achieved.

The igniting portion may comprise a tubular mesh, for providing omnidirectional heat radiation to the main catalyst. Furthermore the tubular mesh may be arranged inside the main catalyst. It is herewith assured that the catalytic combustion does not start unless fuel gas is present both for the starter-catalyst and the main catalyst. Furthermore, the starter-catalyst may assist in the catalytic combustion.

According to a further preferred embodiment, the starter-catalyst is arranged down- stream of the gas distributor. It is, hereby, possible to direct the fuel gas towards the starter-catalyst, such that the starter-catalyst may receive sufficient fuel gas for the catalytic combustion to start. According to a further preferred embodiment, the heating system further comprises a fuel cartridge for supplying fuel gas to the catalytic burner, said cartridge comprising a canister connected by an annular crimp channel to a valve cup with a valve arrangement. The crimp channel forms a shoulder of the valve cup in the direction towards the canister. The cartridge comprises a resilient adapter ring having an outer surface with a plurality of resilient protrusions each of which extends over a portion of the outer perimeter of the adapter ring and grips behind the shoulder by a clip action for releasably attaching the adapter ring to the cartridge. The adapter ring has a first fastening means for releasable connecting the cartridge to cooperating second fastening means of the catalytic burner.

It is a problem with fuel cartridges of prior art catalytic burners that they are connected to the heating system through a standard thread on the valve cup. There are two major disadvantages of this. Firstly, the valve may break off the fuel cartridge due to acciden- tal impact, potentially, causing a discharge of the cartridge and the risk of an explosion. Secondly, a non-certified fuel cartridge may be applied, also potentially, causing an explosion or, at best, a non-functional system.

With the releasably attached adapter ring according to the invention, it is achieved that an impact to the fuel cartridge will cause the adapter ring to release the fuel cartridge without causing damage to the fuel cartridge and, thus, avoiding the risk of explosion. Furthermore, the first and second fastening means may be a non standard connection, such that only a certified fuel cartridge can be used. It is a very important safety measure that the adapter ring gives way to release before the valve or the fuel cartridge dur- ing an impact.

The inventor has developed a modified Izod impact strength test. An Izod test is an American Institute for Testing and Materials (ASTM) standard that is developed by Edwin Gilbert Izod. In the Izod test, the test specimen is held in a cantilevered beam configuration in a fixture as opposed to, for example, the Charpy impact test where a three point beam configuration is used. A pendulum hammer that is released from a first height impacts the test specimen, which breaks off, such that the pendulum hammer continues past the test specimen fixture to reach a second height. The difference in between the first and second heights defines the work spend by the pendulum to break off the test specimen.

The modified Izod test developed by the inventor is used to measure the work to re- lease the fuel cartridge from the catalytic burner without damaging the valve cup. The test specimen fixture has second fastening means that are engaged with the first fastening means of the adapter ring for simulating the connection between the fuel cartridge and the catalytic burner. The fuel cartridge is thereby fixed in the test fixture in a canti- levered configuration during the modified Izod test in a way that represents a use situa- tion. The pendulum hammer is released from a first height where after it impacts the fuel cartridge that is released. The pendulum hammer continues to a second height that is recorded. It is hereby possible to establish the work required to release the fuel cartridge from the test specimen fixture, which is simulating the catalytic burner, based on the difference between the first and second heights.

The manufactures of such cartridges control the geometrical dimensions of the valve cup after it has been crimped onto the canister within very tight tolerances as a normal procedure during manufacture. Therefore, this can be used in combination with the modified Izod impact, which has been developed by the inventor, to establish the geo- metrical shape of the outer perimeter of the adapter ring and especially the protrusions, such that the work required for releasing the cartridge without damaging the valve or valve cup is controlled within a narrow range. Furthermore, the friction between the adapter ring and the valve cup and crimp channel shall be sufficient to enable the first and second fastening means to be engaged and disengaged without damaging said fas- tening means. For example, if the fastening means are a thread, the friction shall allow a user to turn the cartridge and the adapter ring without relative movement between the adapter ring and cartridge in a direction that tightens the thread to a level where the cartridge does not come loose. Further turning of the cartridge after the fastening means have properly engaged shall result in the friction being insufficient to prevent relative movement between the adapter ring and the cartridge, thus preventing damage to the fastening means. The friction shall be sufficient to enable the user to turn the cartridge and the adapter ring without relative movement in a direction that loosens the thread, such that the cartridge is released again. This also applies to other types of fastening means, for example bayonet mounts.

Hence, the work required for releasing the cartridge without damaging the valve or valve cup in combination with the correct friction between the adapter ring and the cartridge becomes design parameters for the geometrical shape and production tolerances of the adapter ring.

It should be mentioned here that this cartridge with the adapter ring is not only advan- tageous for the catalytic system as described above but can also advantageously be incorporated in other systems, for example, as disclosed in International patent application WO2009/003481 or other prior art systems. Thus, independently of the above catalytic system, an invention has been found in a heating system comprising a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber, the catalytic burner comprising a tubular main catalyst and a fuel cartridge for supplying fuel gas to the catalytic burner.

The fuel cartridge can be combined with a fuel gas consumer, specifically a fuel cell For example the fuel cell may be a solid oxide fuel cell (SOFC) or a proton exchange fuel cell. The fuel for the fuel cell may be stored and shipped in the fuel cartridge.

For example the fuel cartridge in combination with the fuel cell may be used for electric power generation in un-manned air vehicles (UAVs), communication systems, lighting systems, computer systems, battery chargers, emergency power supplies and hybrid systems comprising fuel cells and batteries.

In a SOFC the fuel from the fuel cartridge, said fuel being for example propane, is converted and reformed into hydrogen and by that drive the process in the SOFC, which in turn produce electrical power.

Thus, independently of the above fuel cartridge and catalytic heating system an invention has been found in a fuel cartridge in combination with a fuel cell. The fuel cell can be combined with a fuel gas consumer, specifically a catalytic heating system. Thus, independently of the above fuel cartridge and catalytic heating system an invention has been found in a fuel cartridge in combination with a catalytic heating system.

Said catalytic heating system comprising a catalytic burner for flameless catalytic combustion of a fuel gas in a combustion chamber, the catalytic burner comprising a tubular main catalyst and a fuel cartridge for supplying fuel gas to the catalytic burner.

Said cartridge comprises a canister connected by an annular crimp channel to a valve cup with a valve arrangement. The crimp channel forms a shoulder of the valve cup in the direction towards the canister. The cartridge further comprises a resilient adapter ring having an outer surface with a plurality of resilient protrusions each of which extends over a portion of the outer perimeter of the adapter ring and grips behind the shoulder by a clip action for releasably attaching the adapter ring to the cartridge. The adapter ring has a first fastening means for releasable connecting the cartridge to cooperating second fastening means of the catalytic burner. It is herewith achieved that the adapter ring gives way before the valve of the fuel cartridge during impact, which is a very important safety feature.

According to a further embodiment, the first and second fastening means are parts of a bayonet mount. It is, hereby, possible to quickly mate the fuel cartridge to the heating system, because a bayonet mount can be engaged in less than one turn. In an embodiment, the first fastening means comprises four coupling members in the form of protrusions equally spaced along the inner perimeter of the adapter ring. The mating is performed in less than a quarter turn. During severe cold conditions this is an advantage for the user.

According to a further embodiment, the adapter ring further comprises a rim extending over the crimp channel for covering the crimp channel. This rim may be used to provide a friction between the crimp channel and the rim. This friction allows a firm and tight mating of the first and second fastening means, because the friction will prevent the adapter ring from turning in relation to the cartridge. This further enhances the precision of the work required to free the fuel cartridge. According to an alternative embodiment according to the invention the adapter ring is adapted for providing friction between the inner periphery of the crimp channel, such that the friction will prevent the adapter ring from turning in relation to the cartridge when mounting the cartridge. Though use of the cartridge above has been explained above in connection with hand held, portable catalytic heaters, this is in no way limiting for the invention. Such a cartridge may be used as an aerosol cartridge as a substitution for prior art cartridges in the different fields of application. Furthermore a separate invention has been found in a catalytic heating system in combination with a power generator, for converting heat to electricity

The conversion may be performed by a power generator comprising thermoelectric modules.

The catalytic burner or combustion chamber is placed close to the thermoelectric modules, such that they are heated by the catalytic heating system by flameless catalytic combustion of the fuel gas. The catalytic heating system that is a gas consumer may be supplied with fuel gas from a fuel cartridge according to the invention.

This system is advantageously because the heating system may be used for heating purposes as well as generating electricity. This provides dual purpose equipment for off- grid or field applications.

The fuel cartridge may be used in combination with stationary or mobile gas consumers. The catalytic heating system may be used in stationary or mobile applications.

When used in connection with a catalytic heater, the application may extend into a heater for liquid in a water-tight flexible bag in order to heat up liquid in the bag by the heater. For example, a bag may be provided for heating water or other liquids, such as

- water for cleaning,

- medical infusion liquids,

- water used in body-tight circulation systems for heating human bodies, optionally incorporated in the garment/clothing of a person,

- general water provision by melting snow in a bag or other type of container.

Furthermore a separate invention has been found in a fuel cartridge in combination with a catalytic heating system comprising a main catalyst for flameless catalytic burning of fuel gas and a triggering system for initiating the catalytic burning, the triggering system comprising an electrical power source electrically connected to an electrically conducting, metallic catalyst portion for causing electrical current to flow through the catalytic portion and thereby heating the catalyst portion to a temperature necessary for triggering the catalytic burning at the catalyst portion.

In a further embodiment the combination as described above is peculiar in that metallic catalyst portion is substantially smaller than the main catalyst.

In a further embodiment the combination as described above is peculiar in that the me- tallic catalyst portion through which current flows has a width and a height and a length, each of which is smaller than 1 mm.

In a further embodiment the combination as described above is peculiar in that the main catalyst is a metallic mesh.

In a further embodiment the combination as described above is peculiar in that the main catalyst is a tubular mesh with varying diameter. In a further embodiment the combination as described above is peculiar in that the main catalyst is a tubular mesh in the shape of a truncated cone.

In a further embodiment the combination as described above is peculiar in that a ven- turi system is provided for mix of fuel gas and oxygen, the venturi system comprising a venturi nozzle with a nozzle exit, through which fuel gas is provided, and a channel around the venturi nozzle, the channel being formed between the outer wall of the venturi nozzle and a pipe portion surrounding the nozzle, the outer wall of the venturi nozzle being concave and the surrounding pipe portion being convex to form a smoothly bending channel towards the venturi nozzle exit.

In a further embodiment the combination as described above is peculiar in that the system is a portable system with integrated fuel tank and comprising a handle and an in extension hereof arranged heating pipe containing the catalyst, where the heating pipe is produced in a material that is transparent for infra-red radiation and fluid-proof for immersion in liquids.

In a further embodiment the combination as described above is peculiar in that the heating system further comprises a heat exchanger between a fuel tank and an exhaust pipe system for heat exchange between emission gas from the catalytic burning and a wall of the fuel tank.

In a further embodiment the combination as described above is peculiar in that the catalyst is surrounded by a fluid-proof, infra-red transparent enclosure immersed in a liquid tank for heating of liquid in the liquid tank by the infrared radiation from the catalytic burning by the catalyst.

Furthermore a separate invention has been found in a catalytic heating system in combination with a power generator, for converting heat to electricity.

For example the power generator comprises thermoelectric modules. The catalytic heating system is heating the power generator or thermoelectric modules that converts the heat into electricity.

Description of the Drawing

The invention will be explained in more detail below with reference to the accompany- ing drawing, where: fig. 1 shows a plan view of a catalytic heating system according to the invention, with a) the heating system being inserted into a container, b) the heating system ready for use and c) the heating system ready for transport,

fig. 2 shows the major internal components of the catalytic heating system of fig. 1, fig. 3 shows the major internal components of the starter system for the catalytic heating system of fig. 2,

fig. 4 shows a cross-section of the catalytic heating system of fig. 1, wherein the heating system is active,

fig. 5 shows a cross section of a canister and a valve cup of a fuel cartridge for the heating system of fig. 1,

fig. 6 shows a cross section of the fuel cartridge and an adapter ring,

fig. 7 shows a plan view of the adapter ring,

fig. 8 shows an illustration of a catalytic heating system in combination with a power generator.

Detailed description of the Invention

In the explanation of the figures, identical or corresponding elements will be provided with the same designations in different figures. Therefore, no explanation of all details will be given in connection with each single figure/embodiment.

Fig. la-c are plan views of a catalytic heating system 10, each showing different steps in the use of the heating system 10. The heating system 10 shown is a portable system for outdoor use suitable for severe climatic conditions ranging from extreme cold to extreme heat. The heating system 10 comprises a fuel cartridge 12 for storage of a fuel gas, a gas supply system 14 for controlling the supply of fuel gas, and a heating pipe 16 with a combustion chamber 18, see fig. 2, for catalytic flameless combustion of the fuel gas, and, optionally, a bespoke container 20 for holding a media to be heated and for pro- tecting the heating pipe 4 when the system is not in use. Additionally, the heating system 10 may also comprise a protective cap 24 to enclose the gas supply system 14 and protect it from damage and impact when the heating system 1 is not in use.

The fuel cartridge 12 for supplying gas with or without aerosols is a replaceable fuel cartridge 12, which may be non-refillable. The fuel cartridge is containing a mixture of butane and propane. The ratio of butane to propane is dependent on the temperature in which the heating system 10 is used.

The gas supply system 14 is regulating the flow of fuel gas to the catalytic combustion in the heating pipe 4. The gas supply system 14 and the protective cap 24 may be provided with co-operating fastening means, for example an internal/external screw thread 22 for fastening of the protective cap 24 to the gas supply system 3. The gas supply system 14 is provided with a regulating valve, which regulates the flow of fuel gas, such that the fuel flow is fixed within a chosen range independent of the pressure in the fuel cartridge 2. The gas supply system is further provided with a thermostat for interrupting the flow of fuel gas when a preset temperature of the media to be heated is reached. This is described in WO 2009/003481, which is incorporated here by reference. The fuel gas is provided to the heating pipe 16 for fuelling the catalytic combustion inside the combustion chamber 18, see fig. 2. The heating pipe 16 is composed of an IR transparent material, for example quartz glass or aluminium, and emits IR radiation from the catalytic combustion process, which takes place inside the heating pipe 4. A heat guard 28 may enclose the heating pipe 16 to prevent a user from direct contact with the heating pipe 4, which will be hot during use. The heat guard 28 is a pipe providing a cavity between the outside of the heating pipe 16 and the inside of the heat guard 28. The heat guard 28 has openings 30 for allowing liquid to flow into the cavity and be in direct contact with the heating pipe 4. The size of the openings 30 is chosen small enough to prevent the user from touching the heating pipe 4.

The container 20 may have different shapes or sizes than what is shown in fig. la-c. The container 20 and the gas supply system 14 may be provided with co-operating fastening means, for example, an internal/external screw thread 26 for fastening of the container 20 to the gas supply system 3. A gasket (not shown) may advantageously be provided between the container 20 and the gas supply system 14 to seal the container 20, such that it may be used for storage and transport of a media without leakage.

During heating of the media in the sealed container 20, the temperature and, hence, the pressure will rise. The heating system 10 is, therefore, provided with a safety valve, see fig. 4 for venting the container 20 and, thereby, protect it from damage. In a preferred embodiment, the screw thread 26 is a 63 millimetre wide mouth thread, which is a de-facto standard for outdoor equipment. This will allow the user to apply existing containers and bottles to the heating system 10. The safety valve, being part of the heating system 10 and not the container 20, will support this feature. In fig. la, the heating pipe 16 is partly inserted into the container 20, and in fig. lb, it is fully inserted, the screw thread 26 engaged, and the system ready for use. In fig. lc, the fuel cartridge 12 has been removed, and the protective cap 24 inserted.

The heating system 10 may also be used outside a container 20 for personal heating, for melting ice to gain access to fishing waters, for heating food in a casserole, etc.

Fig. 2 shows the major internal components of the catalytic heating system 10 of fig. 1. The heating system 10 comprises a fuel cartridge 12 containing fuel gas for the catalytic combustion, a gas supply system 14, and a heating pipe 16 with a combustion chamber 18. The fuel cartridge 12 is releasably connected to the gas supply system 14. The heating pipe 16 is attached to the gas supply system 14 and is not intended for being disconnected. The gas supply system 14 comprises an internal supply conduit 32 with a pressure regulating valve 34 and a thermostatic valve 36, for example as described in WO 2009/003481. The conduit 32 is connected to the fuel cartridge 12 at one end and to a nozzle 38, which is part of a venturi system 40, at the other end. Fuel gas will flow from the fuel cartridge 12 through the conduit 32 out of the nozzle 38 to a gas inlet 41 of the combustion chamber 18, as soon as the fuel cartridge 12 is connected to the gas supply system 14, unless the pressure regulating or thermostatic valves 34, 36 are closed. The venturi system 40 comprises the nozzle 38 and air inlet openings 43 connected to an air inlet duct 45 of the heating system 10. The nozzle 38 is arranged in the gas inlet 41 of the combustion chamber 18. As the gas exit the nozzle 38, air and, hence, oxygen is drawn into the gas inlet 41. A catalytic burner 42 for flameless catalytic combustion of a fuel gas is located in the combustion chamber 18. The catalytic burner 42 comprises a tubular main catalyst 44 with a first length. Said main catalyst 44 is in communication with the gas inlet 41 of the combustion chamber 18, such that the fuel gas and air mixture is supplied to the internal part of the main catalyst 44. The main catalyst 44 is a metallic mesh of a cata- lytic material; hence, the fuel gas and air mixture will pass through the sidewall of the main catalyst 44. In passing the main catalyst 44, provided that the catalyst is preheated to a temperature exceeding 350 °C, a catalytic reaction between the fuel gas and the catalytic material of the main catalyst 44 will take place. An exhaust cavity 46 between the catalytic burner 42 and an inner wall 47 of the combustion chamber 18 is provided to lead the emissions from the catalytic reaction to an exhaust outlet 48 of the heating system 10.

A non-catalytic gas distributor 50 is arranged inside the main catalyst 44 to for distributing the fuel gas inside the main catalyst 44, such that the fuel gas is optimally utilised. The gas distributor 50 is a frusto-conical tube made of a metallic mesh providing a plurality of openings along its length and having a first opening 52 at its wide end and a second opening 54 at its narrow end. The frusto-conical tube of the gas distributor 50 has a second length that is smaller than the first length of the main catalyst 44. Due to the catalytic reaction, the main catalyst 44 will reach a temperature of 400 to 700 °C. This causes a thermal expansion of the main catalyst 44. To take up the thermal expansion and to support the main catalyst 44 inside the combustion chamber 18, a slide bearing 56 is provided. The slide bearing 56 is a frusto-conical tube connected at its narrow end to the main catalyst 44 and with its wide end slideably abutting the inner wall 47 of the combustion chamber 18. The diameter of the wide end of the frusto- conical slide bearing 56 and the diameter of the inner wall 47 of the combustion chamber 18 are adapted to each other, such that the slide bearing 56 applies a slight spring force to the inner wall 47 of the combustion chamber 18. The slide bearing, therefore, also provides a seal between the end of the main catalyst 44 and the inner wall 47 of the combustion chamber 18, such that un-burnt gases that reach the end of the main catalyst 44 are returned to the main catalyst 44, where they react with the main catalyst 44 before entering the exhaust cavity 46.

A mixing chamber 58 for mixing fuel gas and air before it reaches the main catalyst 44 is located between the gas inlet 41 and the main catalyst 44. The mixing chamber 58 has a mixing chamber inlet 60, which is connected to the gas inlet 41, and a mixing chamber outlet 62, which is connected to the first end 52 of the gas distributor 50. As can be seen on fig. 2, the nozzle means 38 extend past the mixing chamber inlet 60.

The mixing chamber 58 comprises a thin- walled mixing chamber tube 64. A thin- walled insulation tube 66 is arranged about the mixing chamber 58 and providing an insulation cavity 68 between the insulation tube 66 and the mixing chamber 58 and, thereby, limiting the influx of heat from the hot exhaust in the exhaust cavity 46 to the fuel gas and air mixture in the mixing chamber 58.

The inner wall 47 of the combustion chamber 18, the main catalyst 44, the gas distributor 50, and the mixing chamber 58 all have a circular cross-section. A starter system 70 for preheating the main catalyst 44 to a temperature, where the catalytic reaction between the main catalyst 44 and the fuel gas may commence, is located inside the combustion chamber 18. The starter system 70 comprises an electrically conductive starter-catalyst 72 having an initiator portion 74 and an igniting por- tion 76 and an electrical power source 78, see fig. 3, connected to the starter-catalyst 72 for causing electrical current to flow through the starter-catalyst 72. The initiator portion 74 is substantially smaller than the igniting portion 76 and shaped such that the initiator portion 74 provides electrical resistance when electrical current is applied from the electrical power source 78, see fig. 3, to the starter catalyst 72. This will cause the initiator portion 74 to quickly heat up, after which the catalytic reaction between the fuel gas and the initiator portion 74 will commence. The electrical power source 78 may be disconnected as soon as the catalytic reaction at the initiator portion 74 starts. The heat developed at the initiator portion 74 will heat the igniting portion 76 by ther- mal radiation and conduction through the catalytic material of the starter-catalyst 72, after which the catalytic reaction between the fuel gas and the igniting portion 76 will commence without the need for additional electrical power. The main catalyst 44 will be heated by the radiation from the starter-catalyst 72, such that the catalytic reaction at the main catalyst 44 will commence. The catalytic reaction at the starter catalyst 72 will continue until the fuel gas supply is terminated.

In the embodiment shown in fig. 2, the starter-catalyst 72 is arranged inside the main catalyst 44. The igniting portion 76 is a tubular mesh arranged downstream of the gas distributor 50. The second end 52 of the gas distributor 50 has a diameter that is equal or substantially equal to the diameter of the starter-catalyst 72. The gas distributor 50 thereby ensures that fuel gas is provided to the starter-catalyst 72, such that the catalytic reaction may start promptly.

Fig. 3 shows the major internal components of the starter system 70 in the catalytic heating system 10, of fig. 2. An electrical power source 78 is connected to the starter system 70 for initiating the catalytic reaction.

The electrical power source 78 is a portable power source 78 comprising one or more batteries 80 contained in a housing 82. Each of the batteries 80 has two poles - a posi- tive 81 and a negative 83. In the embodiment shown in fig. 3, the electrical power source 78 has two batteries 80 arranged in series. Alternatively, the batteries 80 may be arranged in parallel. A positive pole 81 of the batteries 80 is in electrical contact with a first contact pin 84, which extend through the housing 82 at a first end of the housing 82. A negative pole 83 of the batteries 80 is in electrical contact with a first contact surface 90 at the first end of the housing 82 for providing a chassis ground. The batteries 80 are spring bi- ased towards the first end, such that a force is required to push the first contact pin 84 towards the housing.

The starter-catalyst 72 in the combustion chamber 18 is in electrical contact with a second contact pin 86, which extend through an end wall 88 of the combustion cham- ber 18/heating pipe 16, and second contact surfaces 92 on the outside surface of the heating pipe 16.

The first contact pin 84 and the first contact surfaces 90 make electrical contact with the second contact pin 86 and the second contact surfaces 92, respectively, when the electrical power source 78 is pushed towards the end of the combustion chamber 18. Current starts flowing through the electrical circuit now created, and the ignition process will now take place. The inventor has made a prototype heating system 10 in which the initiator portion 74 is heated sufficiently for commencement of the catalytic combustion at the initiator portion 74 and the igniting portion 76 and, following after that, the main catalyst 44 upon application of the electrical power source 78 for 1-2 seconds.

Fig. 4 shows a cross-section of a practical example of the catalytic heating system 10 of fig. 1, wherein the heating system 10 is attached to a container 20 with a media to be heated and a fuel cartridge 12 containing fuel gas, and wherein the heating system 10 is active. The major components of the catalytic heating system have already been described with reference to fig. 1, 2 and 3.

The flow path of the fuel gas is described in the following. The fuel gas, which is stored in a liquid state, evaporates as it exits the fuel cartridge 12 and enters the supply conduit 32 in the gas supply system 14. The pressure regulating valve 34 will regulate the pressure of the fuel gas to approximately 0,5 bar, as long as the pressure supplied by he fuel cartridge 12 is within the range of 1,5 to 4,0 bars. The gas fuel flow will be ap- proximately 1 gr. pr. min, which correspond to a thermal heating effect of the heating system 10 of approximately 500 to 600 watts.

The fuel gas continues through the supply conduit 32 to the thermostatic valve 36 comprising a bimetallic disc, which is calibrated to cut off the flow of fuel gas when the media inside the container 20 reaches a pre-set temperature.

The fuel gas, then, enters the venturi system 40 and exits through the nozzle 38. Air 94 is drawn into the mixing chamber 58 through the air inlet openings 43 and the air inlet duct 45, as indicated by white arrows in fig. 4. The air and fuel gas is mixed in the mixing chamber 58.

The air and fuel gas mixture 96 is provided to the gas distributor 50 at the first end 52 of the gas distributor 50. A first part 98 of the air and fuel gas mixture 96 is provided to the main catalyst 44 through openings along the length of the gas distributor 50. The first part 98 of the air and fuel gas mixture 96 is combusted when passing through the main catalyst 44. A second part 100 of the air and fuel gas mixture 96 is provided to the starter-catalyst 72, where it is combusted when passing through the starter catalyst 72. A third part 102 of the air and fuel gas mixture 96 may reach the end of the main catalyst, where it is returned by the sealing slide bearing 56 to the inside of the main catalyst 44 and combusted as it passes the main catalyst 44.

During combustion of the air and fuel gas mixture 96, thermal heat is developed by the exothermal reaction. The thermal heat is radiated through the heating pipe 16 to the media inside the container 20.

The exhaust 104 from the catalytic combustion enters the exhaust cavity 46 and is directed towards the exhaust outlet 48. The flow of the exhaust 104 towards the exhaust outlet 48 is aided by the general gas flow and the chimney effect.

The heating system further comprises a heat exchanger, which is hidden in fig. 4 because it is located in front of and behind the cross-sectional plane of fig. 4. Thermal heat is exchanged between the exhaust 104 exiting the heating system 10 and the air 94 entering the heating system 10. This decreases the temperature of the exhaust 104.

The exhaust 104 exits through an exhaust outlet 48 from where it is directed past the fuel cartridge 12 for further cooling of the exhaust 104 to thereby reduce the thermal signature of the heating system 10. The exhaust 104, in turn, provides heat to the fuel cartridge 12 to make up for the heat used to evaporate the fuel gas.

The container 20 is provided with a pressure relief valve 106 for releasing excessive pressure.

Fig. 5 shows a cross section of a canister 106 and a valve cup 108 of a fuel cartridge 12 for the heating system 10 of fig. 1. The canister 106 and the valve cup 108 are connected by an annular crimp channel 109. The crimp channel 109 forms a shoulder 110 of the valve cup 108 in the direction towards the canister 106. The crimp height 111 and the crimp diameter 112 are well defined geometrical properties of the fuel cartridge 12. These measurements are subject to quality control to verify the manufacturing process. Therefore, the shape of the shoulder 110 is also well defined and static. Fig. 6 shows a cross section of the fuel cartridge 12 and a resilient adapter ring 114, and fig. 7 shows a plan view of the adapter ring. The adapter ring 114 has an outer surface with a plurality of resilient protrusions 116, each of which extends over a portion of the outer perimeter of the adapter ring 114 and grips behind the shoulder 110 by a clip action for releasably attaching the adapter ring 114 to the cartridge 12.

The adapter ring 114 has a first fastening means in form of protrusions 118 for releasably connecting the cartridge 12 to cooperating second fastening means in the form of recesses 120, see fig. 4, in the catalytic burner (see fig. 4). The protrusions 118 and recesses 120, see fig. 4, are coupling members in a bayonet mount. The bayonet mount comprises four coupling members equally spaced along the inner perimeter of the adapter ring. Fig. 8 shows an illustration of a catalytic heating system 10 in combination with a power generator 122. A fuel cartridge 12 for supplying gas to the catalytic heating system 10 is attached to the catalytic heating system 10. The power generator 122 shown comprises thermoelectric modules 124.

When the catalytic heating system 10 is in use heat is applied to the thermoelectric modules 124. The will start producing electricity. A power cord 126 supplies electricity to an electricity consumer (not shown). For example the electricity consumer may be a communications system, a lighting systems, a computer system, a battery charger. Fur- thermore the electricity consumer may be an emergency electricity supply.