DE3920159A1 - Heat generation by flameless combustion in gas flow - Google Patents

Abstract

The system generates heat by flameless combustion of fuel in a gas flow contg. oxygen. The gas flows through a heater (108), along a metering unit (107) for the fuel and a first catalytically active component (109). At least part of it passes through a loop (103) and along the catalytic component under the action of a first feed unit (106). Gas, contg. oxygen, is fed into the loop and part of the gas flow is tapped off from it.

Description

The present invention relates to a method for exploitation that in a catalytic conversion of a reaction mixture of air with fuel and / or convertible parts containing exhaust gas released energy for heating purposes, corresponding devices and their use for heating of motor vehicles.

According to the increasingly strict environmental regulations are increasingly motor vehicles with so-called catalysts equipped with the participation of a catalytically active Material not burned and / or harmful parts in the exhaust gas implement an internal combustion engine, with previously unused Energy is released.

Support bodies for catalytic material are made of, for example EP-C-00 49 489, EP-C-01 21 174, EP-C-01 21 175, the EP-A-02 45 737 and EP-A-02 45 738 are known.

It is also known to electrically heat catalysts in order to to achieve a faster response, for example in DE-PS-5 63 757 or DE-AS-22 30 663 is described. There are also further developments in which the metallic Carrier of a catalyst with a suitable electrical resistance stand manufactured and heated directly.

The catalytic conversion in motor vehicles released energy was previously only used to maintain the necessary reaction temperature in the catalyst and was  otherwise discharged unused with the exhaust gas or otherwise derived.

Modern vehicles have been and are being reinforced Made an effort at low outside temperatures to allow rapid heating of the interior to the To increase driving comfort and driving safety. Partially Vehicles also equipped with so-called auxiliary heaters, which are small burners that operate independently of the engine can be. So far, catalysts have been used as a heat source not considered, especially because of a known problem of the catalysts their slow heating at operating temperature is what a just in the starting phase Removal of heat energy did not appear reasonable. However, new concepts assume that a catalyst is used starting the engine of a motor vehicle electrically on the temperature necessary for a catalytic conversion is preheated so that immediately after starting the engine an exothermic reaction takes place in the catalyst. It depends on the composition of the catalyst Reaction mixture depends on how much energy is released in the catalyst becomes. It is therefore quite possible to go through the catalyst suitable air and fuel supply devices Feed reaction mixture, which is a rapid heating of the catalyst and the removal of heat.

Against this background, it is the task of the present Invention to provide a method by which the in a Catalyst-released heat energy is influenced and targeted Heating purposes can be used. In addition, should appropriate devices created and suitable Applications for this can be specified.

This task is solved by a method for taking advantage of the catalytic conversion of a reaction mixture from air with Exhaust gas containing fuel and / or convertible fractions  released energy for heating purposes, in which a honeycomb body, preferably of metal, with a variety of for a fluid permeable channels, at least in some areas with a is coated catalytically active material from which Flow reaction mixture, the honeycomb body as Heat exchanger used or with such in Flow direction is connected in series, whereby the released energy are transferred to a heat transfer fluid can. It is crucial for the present invention that the energy released in the catalytic converter via heat exchange surfaces is transferred to a heat transfer fluid. For this, the Catalyst, d. H. the one carrying the catalytically active material Honeycomb body, either designed as a heat exchanger or but be connected in series with a heat exchanger. Advantageous for a quick response of such a heater, that will matter for many use cases is if the honeycomb body is electrically or directly heated or at least can be preheated and only after reaching it a temperature necessary for a catalytic conversion is applied to the reaction mixture. This way you can reach a quick response of the heating and avoids at the same time the emission of unpurified exhaust gases in a starting phase.

Basically there are different ways to get one Train catalyst as a heat exchanger. As with the Drawing is explained in more detail, a heat exchange after the cross-flow principle, counter-current or direct current principle. In any case, the catalytically active Material bearing part of the honeycomb body, which with the reaction is applied in close thermal contact to one other part are, which of a heat transfer fluid is flowed through. For this purpose, the inside of the catalyst and / or its outside is provided with pipelines, or the catalyst can consist of intersecting groups of channels be built, of which a group from the reaction mixture and the other group is flowed through by a heat transfer fluid.  

To avoid electrical heating of the catalyst The energy content can have to be operated for a long time of the reaction mixture are adjusted so that one itself preserving catalytic conversion takes place, in which heat can still be removed as required. At a regulated three-way catalytic converter is the regulated admixture of Air usual anyway. Through additional injection of Fuel into the exhaust gas behind an engine or through Setting a particularly fuel-rich mixture in the Starting phase can the energy supply in the reaction mixture can also be increased.

Such a device can also be relatively easily the same operate early as auxiliary heating by using a blower Air is supplied to the catalytic converter and fuel into this air is injected. It makes sense to mix the mixture together add that it is not ignitable, but catalytically is feasible. This creates an explosion hazard in the system avoided and also that in the catalyst in the catalytic Resulting temperature kept much lower than at the small burners common in parking heaters. this in turn reduces the effort in terms of thermal insulation and enables a much easier extraction of the resulting Warmth because the materials used are not so high tempera doors have to withstand. According to these statements, the method according to the invention is also completely independent of the Presence of an engine and without the use of it Use exhaust gases for heating only. However, it will be advantageous generally be an existing catalyst for Use engine exhaust gases for heating purposes.

Both liquids, preferably, come as heat transfer fluid Water or coolant of an engine cooling circuit, as well as gas, preferably air. While a liquid is in a closed circuit must be carried out at Use of air as a heat transfer fluid also an open one  Circuit are used, d. H. the heated air can directly can be used as heating air. Incidentally, the integration of the circuit with the heat transfer fluid in the other systems of a motor vehicle possible in many ways. About one Another heat exchanger can generate hot air, for example be or a heat exchange or a direct connection with the cooling circuit of an internal combustion engine are possible. For the case that the engine and catalytic converter of a motor vehicle for belong to the same cooling circuit, the catalytic converter accelerates heating the engine to operating temperature and generally also speeds up the response of the Vehicle heating. The possible examples given here there are certainly other variants of integration into Air conditioning systems and existing heating systems for motor vehicles.

A device to take advantage of a catalytic Implementation of energy released from a reaction mixture A piping system, generally that, should be used for heating purposes usual exhaust system of a motor vehicle, for guiding the Reaction mixture with a honeycomb body arranged therein, preferably made of metal, containing a variety of for has a fluid-permeable channels and at least in Partial areas is coated with catalytically active material. An open or closed cycle with a Heat transfer fluid required. Finally, heat exchangers surfaces a transfer of the catalytic conversion of the reaction mixture resulting thermal energy from the Allow piping system on the heat transfer fluid. Common knowledge of gas / gas heat exchangers or gas / liquid Speed heat exchangers can be used here analogously. Provided the catalytic converter is not itself designed as a heat exchanger, but a series-connected heat exchanger is used is, its construction is taking into account the one Exhaust system prevailing conditions unproblematic, so that usual components can be used. Is the Catalyst itself designed as a heat exchanger, so it can  its outside or inside heat exchanger surfaces have, for example, by pipes, coils and the like are formed.

To change the catalyst from the beginning to one for the catalytic Implementation bring appropriate temperature, he should in particular, be directly or indirectly electrically heated. Direct heating means that the Catalyst carrier itself or at least one on it applied coating are electrically conductive, so that a Heating by ohmic heat of an electric current becomes possible. Indirect heating can, for example, in a ceramic honeycomb body through in the ceramic and / or in heating wires arranged in the channels can be reached. A indirect heating is also the heating of the fuel Air mixture itself.

The method according to the invention and the device described tions are particularly suitable for use as heating Motor vehicles, especially the possibilities of a Use as auxiliary heating or as trace heating in the Cold start phase should be emphasized. With separate parking heaters can their exhaust gases for additional cleaning the catalyst of the engine exhaust system are directed.

Essential principles, further details and execution Examples of the invention are described below with reference to Drawing explained. Show it

Fig. 1 is a schematic representation of an exhaust system with heated catalyst and a downstream heat exchanger,

Fig. 2, an exhaust system with a heated catalyst, which also serves as a heat exchanger,

Fig. 3 shows an exhaust system with a heatable pre-catalyst, a downstream not separately heated catalyst and a subsequent heat exchanger in a schematic representation and

Fig. 4 shows schematically the structure of a heating system according to the invention with additional devices.

Fig. 5 shows a suitable as a cross-flow heat exchanger honeycomb body, in

Fig. 6 shows the basic installation of such a honeycomb body.

Fig. 7 and Fig. 8 show different embodiments of catalysts with heat exchange function.

Fig. 9 shows a circuit with a catalyst as an auxiliary heating arrangement or additional heating.

Fig. 1 shows a pipe system 11 with a catalyst 12 having an electric heater. 13 This catalytic converter 12 is followed by a heat exchanger 14 , which can extract the heat generated during the catalytic conversion and, of course, possibly also residual heat from the engine from the exhaust gas. The catalyst 12 is acted upon by a reaction mixture which, in the case of a regulated three-way catalyst, contains exhaust gas with proportions of carbon monoxide and nitrogen oxides and air in a certain ratio.

Fig. 2 shows the basic structure of a pipeline system 21 with a catalyst 22 , which also serves as a heat exchanger 24 . Electrical heating 23 can also be provided in this case.

As shown in FIG. 3, an even more complex arrangement can be useful. In a pipeline system 31 , a catalytic converter 32 with electrical heating 33 , a non-heatable catalytic converter 35 and a heat exchanger 34 are arranged one after the other, wherein the heat exchanger 34 can also serve as a catalytic converter 36 at the same time, by providing the areas in contact with the exhaust gas with catalytically active material are coated. The electrical heating 33 of the first catalytic converter 32 causes the catalytic reaction to respond quickly, the heat of which in turn causes the second catalytic converter 35 to respond. The total heat generated can be coupled out with the heat exchanger 34 .

FIG. 4 again shows a schematic representation of the surroundings of the present invention, the arrangement shown also being suitable as an auxiliary heater. In a piping system 41 in succession an electrically heatable catalytic converter 43 and 42, a heat exchanger 44 are arranged, the latter can be catalytically active simultaneously. For the following, it does not matter which of the variants of catalyst and heat exchanger described so far is used. It is important that the arrangement has an air inlet 46 with a suitable regulating valve 47 and a device 48 for injecting fuel. A desired ratio between the concentrations of the individual constituents of the reaction mixture can be established by means of a sensor 49 a, preferably a lambda probe. It is important that no ignitable mixture is formed in the area in front of the catalyst 42 . The device can additionally be equipped with further sensors 49 b, which monitor the function of the catalytic converter 42 , possibly its temperature or other parameters. In principle, in the case of catalysts which can be heated directly, it is also possible to monitor the function by measuring the electrical resistance of the heating, since this resistance is directly proportional to the temperature in the catalyst.

Fig. 5 shows a honeycomb body which is suitable as a catalyst carrier body and cross-flow heat exchanger. This honeycomb body 52/54 consists of alternately layered smooth 56 and corrugated sheets 57 , 58 , the corrugations of the corrugated sheets 57 , 58 are arranged alternately parallel and perpendicular to the exhaust gas flow, so that a group of channels 59 is formed, the exhaust gas can be flowed through, and a second group of channels 60 , which do not communicate with those of the first group and can therefore be flowed through by a heat transfer fluid. The type of flow is indicated by arrows. The basic installation of such a honeycomb body 62/64 in a pipeline system 61 is shown schematically in FIG. 6. The arrangement has an inlet 65 for the reaction mixture and an outlet 66 for exhaust gas. Transversely to this is the flow of the heat transfer fluid, which is fed to the honeycomb body 62/64 at an inlet 67 and is discharged heated at an outlet 68 . Electrical connections 63 for heating the honeycomb body 62/64 are indicated. In the honeycomb body described in FIGS . 5 and 6, the smooth sheets serve as heat exchanger surfaces, while the corrugated sheets enlarge the upper surface for the catalytically active coating and also favor the heat transfer.

FIG. 7 shows a further variant for a catalyst designed as a heat exchanger, the actual catalyst 72 here being practically unchanged from known systems. It can consist of structured metal sheets and can be equipped with electrical heating 73 in a known manner. On its face 75 , the reaction mixture occurs and on the opposite face 76 exhaust gas emerges. The catalyst 72 is wrapped in a coiled tubing 74 which is in close thermal contact with its outer wall. This structure is particularly useful in the case of metallic catalyst carrier bodies, since these have a high thermal conductivity, so that significant heat dissipation via the outer surface is possible. The pipe coil 74 has an inlet 77 and an outlet 78 for a heat transfer fluid, the direction of flow of the coil taking into account thermal stresses and the average temperature distribution in the catalytic converter. Both a counterflow and a cocurrent with respect to the direction of the exhaust gas can be advantageous.

FIG. 8 shows another exemplary embodiment of a catalytic converter 82 arranged in a pipeline system 81 , which has heat exchanger pipes 84 in its interior, which are part of a circuit with heat transfer fluid. The individual heat exchanger tubes 84 , of which only two are shown here, are combined in the inlet area 85 of the reaction mixture to form a pipeline and are led outside, where they form the outlet 88 for the heat transfer medium. Also in the outlet area 86 of the exhaust gas, the heat exchanger tubes 84 are combined and led to the outside, where the inlet 87 for the heat transfer fluid is located. Again, the catalytic converter 82 can be equipped with an electrical heater 83 .

FIG. 9 shows an arrangement which is particularly suitable for auxiliary heating and additional heating in a motor vehicle, only the principle being shown schematically. A pipeline system 91 forms a circuit in which a catalytic converter 92 , a heat exchanger 94 and an electric heater 93 are connected in series. Because of the circular design, the order of these elements is not critical. Two or three of these elements can also be combined in a single component. The gaseous content is circulated in the circuit by means of a fan 95 . Air, which can optionally be preheated, can be supplied to the circuit via an inlet 96 . This air can be admixed with fuel in a metered manner via a fuel nozzle 98 . At a branch 99 , a small part of the exhaust gas is discharged from the circuit to an outlet 97 , which can, for example, open into the actual exhaust system of a motor vehicle. The arrangement described can be operated as follows: First, air is circulated in the circuit 91 by means of the fan 95 and heated by means of the electrical heater 93 to the extent necessary for the catalytic reactions in the catalytic converter 92 to start. Air is then fed in with admixed fuel, but in a non-ignitable mixture ratio, so that this mixture fed in is only converted in the catalyst 92 . The heat generated can be coupled out by means of the heat exchanger 94 . Only a small part of the exhaust gas is discharged directly, while the larger part is circulated via the fan 95 and enriched with a new air-fuel mixture. By regulating the opening at branch 99 and / or the amount of air fuel supplied, the output of this heating arrangement can be varied within wide limits without the process becoming unstable. This is particularly favorable for changing requirements in a motor vehicle heating system.

The present invention is suitable for using the in a heat of reaction arising, in particular for the heating of motor vehicles, however, is not due to this Application limited. The integration of a heat exchanger in a catalyst can also its thermal load decrease as temperature peaks through the heat exchanger can be prevented.

Claims (22)

1. A method for utilizing the energy released in a catalytic conversion of an exhaust gas containing a reaction mixture of air with fuel and / or convertible components for heating purposes, wherein a honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ; 92 ), preferably made of metal, with a plurality of channels permeable to a fluid, which is coated with a catalytically active material at least in some areas, through which the reaction mixture flows, and wherein the honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ; 92 ) is used as a heat exchanger or is connected in series with such a ( 14; 34; 44; 74; 94 ) in the flow direction, as a result of which the energy released can be transferred to a heat transfer fluid. 2. The method according to claim 1, characterized in that the honeycomb body is directly or indirectly electrically ( 13; 23; 33; 43; 63; 73; 83; 93 ) heated or at least preheated and only after reaching a temperature necessary for a catalytic reaction is charged with the reaction mixture. 3. The method according to claim 1 or 2, characterized in that a group of the channels ( 59 ) of the honeycomb body ( 52 ) is coated with catalytically active material and is acted upon by the reaction mixture and another group of channels ( 60 ) is flowed through by heat transfer fluid . 4. The method according to claim 1, 2 or 3, characterized in that the honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ; 92 ) is electrically preheated to the reaction temperature and then reacted with the reaction mixture, the reaction mixture from air, exhaust gas of a combustion engine and / or fuel is regulated so that a self-sustaining catalytic conversion takes place. 5. The method according to claim 4, characterized in that, especially for heating a motor vehicle when the engine is at a standstill or during operation, the honeycomb body ( 42 ; 92 ) with a reaction mixture of air and fuel and optionally additionally exhaust gas of an internal combustion engine, which is applied with respect to Concentration of the individual components is composed so that it is not ignitable but catalytically implementable. 6. The method according to claim 1, 2, 3, 4 or 5, characterized characterized in that the heat transfer fluid is a Liquid, preferably water or coolant Engine cooling circuit. 7. The method according to claim 1, 2, 3, 4 or 5, characterized characterized in that the heat transfer fluid Is gas, preferably air. 8. The method according to any one of claims 1 to 7, characterized characterized in that the heat transfer fluid in in a closed cycle, in which at least one further heat exchanger for heating the Interior and / or engine cooling circuit of a motor vehicle is included. 9. The method according to claim 7, characterized characterized in that the heat transfer medium is air is and in the open circuit the interior of a motor vehicle Heated stuff. 10. Device for utilizing the energy released in a catalytic conversion of a reaction mixture of air with fuel and / or convertible components containing exhaust gas for heating purposes

• a) a pipeline system ( 11 ; 21 ; 31 ; 41 ; 61 ; 81 ; 91 ) for guiding the reaction mixture with a honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ; 92 ) arranged therein, preferably made of Metal which has a multiplicity of channels through which a fluid can flow and which is coated at least in some areas with catalytically active material,
• b) an open or closed circuit with a heat transfer fluid,
• c) heat exchanger surfaces, which enable a transfer of the thermal energy generated during the catalytic conversion of the reaction mixture from the piping system to the heat transfer fluid.

11. The device according to claim 10, characterized in that the honeycomb body ( 12 ; 22 ; 36 ; 45 ; 52 ; 62 ; 72 ; 82 ) is itself designed as a heat exchanger and has inside and / or outside heat exchanger surfaces. 12. The apparatus according to claim 10, characterized in that with the honeycomb body ( 12 ; 32 , 35 ; 42 ), a heat exchanger ( 14 ; 34 ; 44 ; 94 ) is connected in series in the flow direction. 13. The apparatus of claim 10, 11 or 12, characterized in that the honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ; 92 ) directly or indirectly electrically heated ( 13; 23; 33; 43; 63; 73; 83; 93 ). 14. The apparatus according to claim 11, characterized by the following features:

• a) the piping system ( 11 ; 21 ; 31 ; 41 ; 61 ; 81 ) has at least one inlet ( 65 ; 75 ; 85 ) for the reaction mixture;
• b) the pipeline system ( 11 ; 21 ; 31 ; 41 ; 61 ; 81 ) has at least one outlet ( 66 ; 76 ; 86 ) for exhaust gas;
• c) the honeycomb body ( 12 ; 22 ; 32 ; 42 ; 52 ; 62 ; 72 ; 82 ) lies between the inlet ( 65 ; 75 ; 85 ) and outlet ( 66 ; 76 ; 86 ) and connects both through a variety of with catalytically active Material coated channels;
• d) the honeycomb body ( 22 ; 52 ; 62 ; 72 ; 82 ) is formed inside and / or outside as a heat exchanger with at least one inlet ( 67 ; 77 ; 87 ) and at least one outlet ( 68 ; 78 ; 88 ) for a heat transfer fluid.

15. The apparatus according to claim 14, characterized in that the honeycomb body ( 12 ; 22 ; 32 ; 52 ; 62 ; 72 ; 82 ) contains a metallic structure which directly with a via connections ( 13 ; 23 ; 33 ; 43 ; 63 ; 73 ; 83 ) supplyable electric current can be heated. 16. The apparatus of claim 14 or 15, characterized in that the honeycomb body ( 72 ; 82 ) by at least one tightly wrapping ( 74 ) and / or its interior ( 84 ), through which a heat transfer fluid flowable tube is designed as a heat exchanger. 17. The apparatus according to claim 14 or 15, characterized in that the honeycomb body ( 52 ) is designed as a cross-flow heat exchanger ( 54 ). 18. The apparatus according to claim 17, characterized in that the honeycomb body has two mutually non-communicating groups of intersecting channels ( 59 and 60 ), through one of which the heat transfer fluid and through the other of which the reaction mixture is conductive. 19. Device according to one of claims 10 to 18, characterized in that the piping system ( 91 ) forms a circuit in which a partial flow of air and fuel is introduced via an inlet ( 96 ) and from which a partial flow of exhaust gas via an outlet ( 97 ) can be derived. 20. The apparatus according to claim 19, characterized in that in the circuit ( 91 ) a honeycomb body ( 92 ) with a catalytically active coating, a heat exchanger ( 94 ) and an electric heater ( 93 ) are provided, two or three of these elements also in one unit can be united. 21. Application of a method according to one of claims 1 to 9 for heating motor vehicles, preferably in the Cold start phase or with the engine stopped. 22. Use of a device according to one of claims 10 to 20 for heating a motor vehicle, in particular as Auxiliary heating with the engine stopped or in the cold start phase.