EP1002993B1 - Boiler for liquid fuels - Google Patents

Description

The present invention relates to a boiler for liquid fuels with a Burner, heating surfaces and a flue gas outlet according to the Claim 1.

Boilers are known in which vertically arranged cylindrical heating surfaces are provided. Such boilers are operated with evaporator burners, which are arranged below the heating surfaces in their own combustion chamber are. The combustion air is introduced by a fan provided for this purpose. Between the combustion chamber and the one enclosed by the heating surfaces An annular guide member is arranged in space. With such a The heat is transferred from the flames or flue gas to the boiler Heating surfaces primarily by gas radiation and is therefore of moderate efficiency. Furthermore, with such boilers, at least at certain operating points Form areas in which there is no flow, so that the Heat transfer on the heating surfaces is further deteriorated.

Other boilers are operated with pressure atomizing burners, which are at the front are attached to the boiler, with the help of high oil atomization and blower dynamics a forced horizontal flame development occurs. Furthermore, it is known to arrange atomizer burners so that a vertical Flame formation from top to bottom is achieved.

Furthermore, boilers are known in which fuels before ignition and before actual start of combustion within a hollow body, a so-called Flame generator, mixed in gaseous state with combustion air are and exit through openings in this flame generator to be ignited and get burned.

DE 42 25 749 A relates to an evaporation burner. With this burner fuel is vaporized in a porous body and into a cylindrical one Mixing tube introduced. The mixing with the combustion air takes place in this mixing tube. A cylindrical body is concentric outside the mixing tube Redirection of the flames arranged. A boiler with heating surfaces or the like is in not described in this document.

EP 0 233 330 A discloses a boiler with a pressure atomizing burner with a nozzle that creates flames in the combustion chamber. A flame producer that is, a component within which there is a combustible mixture, that burns outside of it is not disclosed in this document, i.e. that this boiler is fundamentally different in design from the object of the present invention. The need for high pressure atomization by means of compressed air between 20 and 200 mbar in the known boiler not to use other burners without controllability and low pollution to deteriorate.

EP 0 347 797 A also relates to a pressure atomizing burner which is horizontal in a boiler is installed. Here too, what was said above about EP 0 233 330 A. Incidentally, it is noted that premix burners are usually only used for vertical installation work satisfactorily because of a homogeneous flame formation cannot be done with horizontal installation.

DE 42 25 749 A shows an evaporation burner. Like this one in the boiler is not described in this document. The same applies also for JP 61-099010 A. EP 0 745 805 A is ultimately a boiler known, which is also limited in terms of performance and exhaust emissions is.

The object of the present invention is the boiler described above to further develop that efficient heat transfer to the heating surfaces and thus high efficiency is achieved. Furthermore, the exhaust emissions, in particular nitrogen oxide emissions can be reduced. By achieving one high performance should allow a small installation space with high performance become. At the same time, maintenance and repair work should be easy and be possible without any problems.

This is indicated by that in claim 1 Measures solved.

It is important in the present invention that fuel and air are not only in a cylindrical mixing tube but already mixed in the evaporator unit be introduced into the flame generator in a mixed state become. This is therefore not with the mixing tube of the previously published burner comparable. In the case of a premix burner in the sense of the invention, the Fuel that is mixed with the air is released into the combustion chamber through openings. It is essential that temperatures inside the flame generator are below the ignition temperature of the combustible mixture. In addition, the flow rate of the mixture as it passes through the openings of the flame generator be greater than the burning rate, to avoid a burn back.

It is subsequently essential for the invention in which relation the Flame generator is arranged to the heating surfaces. A compact design can only be achieved by the arrangement according to the invention. It is also a very even outflow of the combustible mixture from the Flame generator required, which in practice only requires a premix burner is achievable.

The particularly advantageous solution of the invention is mainly achieved by that the essential part of the burner, namely the flame generator is located within the space enclosed by the heating surface. Thereby the heat transfer can not only by convection and gas radiation but also done by solid state radiation, resulting in a significantly higher efficiency leads.

It is particularly favorable if the premix burner is located below the flame generator is arranged, and detachable with a part containing the heating surfaces of the boiler is connected. In this way, the boiler according to the invention easy to dismantle to carry out inspection and maintenance work, so that the maintenance effort can be reduced.

The performance of the boiler according to the invention can thereby be improved be that a guide body is provided above the flame generator is formed essentially concentrically with the flame generator. By the narrowing of the cross section according to the guide body will accelerate the Flue gas flow reached, so that an improved heat transfer to the Heating surfaces can be reached.

A particular improvement in the flue gas flow can be achieved that a deflecting body is provided above the first heating surface, and that a further heating surface is arranged radially outside the first heating surface is. In this way it is caused that the flue gases initially on the inside of the first heating surface flow up over the top of the first Heating surface are deflected and continue on the outside of this heating surface stream. The speed can be reduced by suitably designed flow baffles the flow can be adjusted so that an optimal heat transfer is possible.

In a particularly preferred embodiment variant of the invention, that preferably a heating return in the upper area of the first heating surface flows tangentially. It is particularly preferred if the Heating return a main inflow opening in the first heating surface and a secondary inflow opening in a further heating surface outside the first Heating surface is arranged. With conventional boiler structures, the heating return usually introduced in the lower part of the boiler. At a Boilers of the construction according to the invention would, however, in certain Operating conditions lead to the formation of condensates. When initiating the Returning to the top of the boiler can cause condensation in all Operating conditions can be safely avoided. The is particularly favorable Generation of a tangential velocity component of the returned Boiler water to report local hypothermia. By the bulk of the return is introduced into the inner heating surface, the danger undercooling is further minimized by the fact that the heating surface is applied here is particularly large.

In many cases, two different heating circuits are served by one boiler, for example a heating circuit for underfloor heating and another Heating circuit for radiators. Such heating circuits must be on a clearly different one Temperature level can be regulated independently of one another. A mutual one Influencing can largely be ruled out by the fact that preferably the heating return a first return and another Return, which before entering the heating surface in the first return is introduced like a nozzle.

A further preferred embodiment variant of the invention provides that the first heating surface is designed as a cylindrical body on the outside is washed by boiler water, and that reheating surfaces are tubular above the first heating surface are arranged. Such a structure is particularly suitable for compact, wall-hung central heating boiler with or without an integrated Water heater. With such a solution, the vertical installation position in be advantageously used. Because such wall boilers primarily in the living area installed, come the special advantages of pre-evaporating Premix burner especially in terms of low noise emissions to carry.

Fig. 1

einen schematischen Schnitt durch einen erfindungsgemäßen Kessel;

Fig. 2

eine teilweise axonometrische Darstellung, die die Befestigung des Brenners zeigt, wobei Kessel und Brenner getrennt sind;

Fig. 3

eine Darstellung entsprechend Fig. 2 in zusammengebautem Zustand;

Fig. 4

einen teilweisen Schnitt im Bereich der Einmündung des Rücklaufs nach Linie IV-IV in Fig. 5;

Fig. 5

einen Schnitt nach Linie V-V in Fig. 4;

Fig. 6

einen Schnitt einer weiteren Ausführungsvariante der Erfindung; und

Fig. 7

schematisch ein Detail eines Vormischbrenners im Schnitt.

The invention is explained in more detail below on the basis of the exemplary embodiment illustrated in the figures. Show it;

Fig. 1

a schematic section through a boiler according to the invention;

Fig. 2

a partial axonometric view showing the attachment of the burner with the boiler and burner separated;

Fig. 3

a representation corresponding to Figure 2 in the assembled state.

Fig. 4

a partial section in the region of the confluence of the return line IV-IV in Fig. 5;

Fig. 5

a section along line VV in Fig. 4;

Fig. 6

a section of a further embodiment of the invention; and

Fig. 7

schematically a detail of a premix burner in section.

The boiler according to the invention consists of a frame 1 on which a premix burner is arranged, which consists of an evaporator unit 2 and one above arranged cylindrical flame generator 4 there. The evaporator unit 2 is via an air supply line 3 with combustion air and a Fuel line, not shown, supplied with a liquid fuel. in the A flange plate 6 is arranged in the upper section of the frame 1. A seal is designated 9.

2 and 3 is a preferred embodiment of the releasable connection between the frame 1 and the upper part 5 of the boiler shown. At the Flange plate 6 are attached to pressure hooks 7, which engage with casseroles 8 can be brought, which are attached to the boiler 5. This can. the flange plate 6 attached in the manner of a bayonet lock on part 5 of the boiler become. A seal that is not visible in FIGS. 2 and 3 is in a groove in the lower one Section of part 5 inserted. A locking screw 10 serves to to generate the necessary contact pressure, and an unintentional loosening of the To prevent burner.

In the upper part 5 of the boiler, a first heating surface 11 is provided, which is essentially is cylindrical and concentric with the flame generator 4th is arranged. Above the flame generator 4 is on the first heating surface 11 a guide body 12 is arranged, which is also cylindrical and arranged concentrically to the flame generator 4 and the first heating surface 11 is. The guide body 12 is made of a heat-resistant and insulating material manufactured. Radially outside and concentric to the first heating surface 11 is one further heating surface 13 arranged upwards through a deflecting body 14 is complete. In the gap 15 between the heating surfaces 11 and 13 are Flow baffles 16 arranged. On the outer circumference of the further heating surface 13, a flue gas vent 17 is attached.

The structure described above achieves the following function. The end the evaporator unit 2 flowing fuel-air mixture is in the Flame generator 4 completely evaporated and released to the outside and burned. The flue gases initially flow along the arrow 18 along the Inner surface of the first heating surface 11 upwards. Through the guide body 12 a narrowing of the flow cross-section and an acceleration of the flow reached. The deflecting body 14 deflects the flow towards the outside, so that this in the gap 15 between the first heating surface 11 and the other Heating surface 13 flows down. To facilitate service and maintenance work the upper deflector 14 is removable at the top of the other Heating surface 13 arranged. The baffles 16 force the flue gases to one up and down flow movement along the circumference of the heating surfaces 11, 13. Ultimately, the flue gases flow out through the flue gas outlet 17. The Boiler according to the present invention can be used both as a condensation boiler as well as a conventional low-temperature boiler. In the first case, the heating surfaces in the flue gas path are dimensioned so generously and made of corrosion-resistant material, so that condensation of the flue gas can be brought about, whereby the heat of condensation of the in the exhaust gases contained water is exploited. This will make the Fuel contained energy used up to almost the calorific value. The emerging Condensate is discharged at the lowest point of the flue gas path 18. In In such a case, the heating return is initiated at a low level Point of the heating surface. This ensures that the flue gases in the last part brought their flow path to the lowest possible temperature level so that a high degree of efficiency is achieved.

4 and 5 show the detailed structure of the mouth of the return in the case of a boiler in which condensation is avoided. Such a A boiler is easier and cheaper to manufacture than a condensation boiler.

The heating return has a first return connection 20 and another Return connection 21. These return connections 20, 21 are for example assigned to a floor heating circuit and a radiator heating circuit. The first Return is designed as a nozzle 22, around which an annular space 23 is concentric is arranged. The further return 21 opens into this annular space 23. In this way it is possible to use the circulation pumps for both heating circuits Arrange return, with a mutual influence of the two heating circuits is largely avoided. The united passes through a manifold 24 Return into a flow tube 25. The flow tube 25 opens in the first heating surface 11. From FIG. 5 it can be seen that the opening 26 of the Flow tube 25 is chamfered so that the backflow Heating medium has a tangential speed component along the Arrow 27 is granted. A smaller part of the Return medium introduced into the further heating surfaces 13. A boiler connector 29 envelops the flow tube 25. This configuration ensures that that the majority of the returned heating medium in the first heating surface 11 is introduced. A welded steel plate 33 in the area of The confluence of the flow tube 25 increases the thermal resistance and also prevents the occurrence of cold areas on the boiler wall, that could lead to condensation.

6 shows a further embodiment variant of the invention. Concentric a heating surface 11 is arranged for the flame generator 4. The heating surface 11 is closed at its top with a plate 31. Starting from this plate 31 reheating surfaces 32 are guided vertically upwards. By doing Inside the post-heating surfaces are flow obstacles bent in sheet metal used in a manner known per se, which extend the flow paths of the flue gases, to bring about an improved heat transfer. These missions are also referred to as turbolators 33. In addition to these components is a Service water tank 34 arranged. All of these components are in common Tub 35 arranged, the intermediate space 36 with heating medium is filled. Insulation 37 prevents excessive heat loss. The evaporator unit 2 of the burner is arranged below the tub 35, and can, as in the embodiment described above, easily be expanded downwards. The combustion air is at 38 either supplied from the environment or from a corresponding pipeline. The Flue gas connection is designated 39. Come with this variant the particular advantages of the solution according to the invention in particular Wear.

A premix burner is shown partially schematically in FIG. 7. On a Evaporator unit 2 is a flame holder 4, which has a variety of Has openings 40 in a network or grid-like structure. The interior 41 of the evaporator unit 2 is connected to the flame holder 4 via openings 42 in connection.

On a shaft 43, which protrudes through an opening 44 into the interior 41, is a Atomizer cup 45 attached upwards through an atomizer plate 46 is covered. Atomizer blades 47, which also rotate with the shaft 43, cause a further swirling of the fuel, which is via a line 48 is introduced into the atomizer cup 45, and upwards from this exit. The combustion air is supplied by a fan, not shown, which can also be driven by the shaft 43 via the opening 44 in the Blown interior 41. This ensures that through the openings 42 a finely divided fuel-air mixture is guided.

The burner according to the invention enables a very uniform temperature distribution be achieved so that high performance can be achieved and at the same time the nitrogen oxide emission can be reduced.

Claims (12)

1. A boiler for liquid fuel with a burner consisting of an evaporating unit (2) and of a cylindrical flame generator (4), with heating surfaces (11, 13) and with a flue gas exhaust port (17), the burner being configured to form a premixer in which the fuel is evaporated in the evaporating unit (2) and mixed with air to obtain an ignitable mixture and the mixture is fed into the flame generator (4), combustion taking place on the external side thereof, the flame generator (4) being substantially concentrically arranged within a cylindrical first heating surface (11), the premixer being preferably detachably connected to a portion (5) of the boiler that contains the heating surfaces (11, 13), a deflection member (14) being preferably provided above the first heating surface (11) and another heating surface (13) being arranged preferably radially outside of the first heating surface (11).
2. The boiler according to claim 1, characterized in that a guide member (12) is provided above the flame generator (4), said guide member being configured to be concentric with said flame generator (4) .
3. The boiler according to claim 1 or 2, characterized in that the deflecting member (14) is configured for removable mounting.
4. The boiler according to one of the claims 1 through 3, characterized in that flow guides (16) are arranged between the first heating surface (11) and the other heating surface (13).
5. The boiler according to one of the claims 1 through 4, characterized in that the flue gas exhaust port (17) is arranged on the outer circumference of the boiler.
6. The boiler according to one of the claims 1 through 5, characterized in that the lower edge of the flame generator (4) is located on the level of the lower edge of the first heating surface (11).
7. The boiler according to one of the claims 1 through 6, characterized in that the axis of the flame generator (4) and of the first heating (11) is vertically arranged.
8. The boiler according to one of the claims 1 through 7, characterized in that a heating return line preferably tangentially discharges into the upper area of the first heating surface (11).
9. The boiler according to claim 8, characterized in that the heating return line is provided with a main inflow port leading into the first heating surface (11) and an auxiliary inflow port leading into another heating surface (13) which is arranged outside of the first heating surface (11).
10. The boiler according to one of the claims 1 through 9, characterized in that the heating return line is provided with a first return line (20) and with another return line (21) that is introduced in the manner of a nozzle into said first return line (20) prior to entering the heating surface (11).
11. The boiler according to one of the claims 1 through 10, characterized in that the first heating surface (11) is configured to form a cylindrical body, boiler water flowing around the outer side thereof, and that postheating surfaces (32) are tubularly arranged above the first heating surface (11).
12. The boiler according to claim 11, characterized in that the first heating surface (11) is arranged, together with a service water tank (34), in a trough (35) flooded with boiler water.

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