Hot gas generator

Abstract

A hot gas generator (1) having a longitudinal axis (L) comprises a burner (2), a combustion chamber (3) which is encased by an axially running flame tube (4), an axially running, tubular generator casing (8) which encases the flame tube (4), wherein a swirl channel (9) is formed between the generator casing (8) and the flame tube (4), and a feed line (14) for a gas to be heated, which feed line opens into a feed section (16) of the swirl channel (9). The feed section (16) extends over the entire width (Z) of the feed line (14) running in the axial direction. The generator casing (8) runs spirally around the longitudinal axis (L) in the feed section (16) such that the swirl channel (9) tapers in the feed section (16) starting from the feed line (14) and running around the flame tube (4).

Description

[0001] HOT GAS GENERATOR

[0002] The invention relates to a hot gas generator with a longitudinal axis, comprising

[0003] • a burner for generating flue gas,

[0004] • a combustion chamber surrounded by an axially extending, refractory-lined flame tube which is closed at one burner end, where the burner enters the combustion chamber, and open at one outlet end,

[0005] • an axially extending, substantially tubular generator casing, which extends from a supply end arranged in the direction of the burner end to a connection end projecting beyond the outlet end and opening into a connection opening, and thereby encloses the flame tube at least in sections, wherein a swirl channel is formed between the generator casing and the flame tube, extending from the supply end towards the connection end and enclosing the flame tube, and

[0006] • a supply line for supplying a gas or gas mixture to be heated or heated, which opens into a supply section of the swirl channel and whose line cross-section is aligned transversely, in particular orthogonally, to a tube cross-section of the flame tube.

[0007] Many technical processes require a warmed or heated gas or gas mixture. Hot gas generators are used for this purpose. Hot flue gases from a combustion chamber are mixed with the gas or gas mixture to be warmed or heated, in order to generate what is known as hot gas. The gas or gas mixture to be warmed or heated can be, for example, air, another gas or gas mixture, an exhaust gas or a flue gas. Possible applications for which a hot gas generator is required include: providing the "under air" for drying purposes, such as sewage sludge drying (in fluidized bed furnaces); providing hot gas for pre-drying ores before roasting the ores; reheating exhaust gases before feeding them to a DeNOx plant, e.g. after an RTO, wet scrubber, steam generator or filter. the flue gas heating after a steam boiler;

[0008] A hot gas generator typically has a combustion chamber in which a fuel (gas or liquid fuel) is burned via a burner, producing hot flue gas. The hot flue gas flows out of the combustion chamber at an outlet end. The combustion chamber is enclosed by a generator casing which extends beyond the outlet end and opens into a connection opening. The gas or gas mixture to be warmed or heated is introduced into the interior of the generator casing via a supply line which opens into the generator casing in the area of ​​the combustion chamber. The gas or gas mixture to be warmed or heated flows past the combustion chamber, mixes with the hot flue gas in the area of ​​the outlet end and, mixed with the flue gas, flows out of the connection opening of the hot gas generator as hot gas into downstream lines or into connected devices (e.g. consumers).

[0009] To produce the most homogeneous hot gas possible, static mixing elements, such as baffles or diverters, are typically provided in the generator casing. These ensure turbulence in the mixture of the gas or gas mixture to be heated and the hot gas, thus improving mixing in the hot gas. Depending on the required degree of homogenization, additional static mixing elements can be provided in lines connected to the hot gas generator and leading to additional devices.

[0010] Hot gas generators of this type are known, for example, from US 1,629,921 A, GB 1,034,213 A and EP 0 004 395 A1. Another hot gas generator, in which the supply line opens into the generator casing in the direction of the longitudinal axis of the hot gas generator and not transversely thereto, is known, for example, from DE 1 501 984 A.

[0011] Known disadvantages of conventional hot gas generators include the fact that a large installation area is required; that a high fan output must be provided due to pressure losses when supplying the gas to be heated; that a lot of effort is required to achieve the desired homogenization of the hot gas in the onward line, particularly when the distances between the hot gas generator and the devices requiring the hot gas are short; that the hot gas generator has to be oversized because a conventional hot gas generator usually has to be suitable for a wide variety of heating media and is not adapted to the individual fuel.

[0012] The invention is based on the object of providing a hot gas generator of the type mentioned above that does not have the disadvantages of the prior art. In particular, the aim is to provide a hot gas generator that is as compact as possible and that achieves a very high degree of homogenization of the hot gas despite its small size.

[0013] This object is achieved according to the invention with a hot gas generator having the features of claim 1.

[0014] Preferred and advantageous embodiments of the invention are the subject of the dependent claims.

[0015] According to the invention, it is provided that the feed section extends over the entire width of the feed line running in the axial direction and that the generator casing in the feed section runs spirally around the longitudinal axis, so that the swirl channel in the feed section tapers around the flame tube, starting from the feed line.

[0016] The spiral-shaped supply of the gas or gas mixture to be heated ensures that the velocity of the gas or gas mixture is (approximately) uniform across the entire circumference of the spiral supply. This ensures that the gas or gas mixture to be heated is distributed very evenly upon entering the swirl channel. This even distribution reduces the differential pressure, in contrast to an annular gas supply.

[0017] The supply line opens into the generator casing laterally or transversely to the longitudinal axis. The supply line preferably has a rectangular cross-section and, in particular, has a greater width (extending substantially in the axial direction) than height (extending substantially transversely to the axial direction).

[0018] The flame tube is lined with refractory concrete, fireclay, ceramic fiber, or another refractory material. The combustion chamber is smaller than the internal volume of the flame tube because the refractory lining has a certain wall thickness.

[0019] The burner leading into the combustion chamber can be, for example, a gas or oil burner.

[0020] A spiral course of the generator casing means in the context of the invention that the generator casing, seen in a cross-section through the hot gas generator along a cutting plane aligned orthogonally to the longitudinal axis, "screws" in a spiral shape around the longitudinal axis. This means that the casing, starting from the area in which the supply line opens into the swirl channel, continuously approaches the longitudinal axis as it circles the latter (whereby the width of the swirl channel - i.e. a distance between the generator casing and the flame tube - continuously decreases) until it meets the area again in which the supply line opens into the swirl channel and in which the supply section has the greatest width.

[0021] The fact that the flame tube is at least partially encased by the generator casing means, within the scope of the invention, that the supply end does not have to reach as far as the burner end of the flame tube, but can also be spaced apart from it in the direction of the longitudinal axis, so that not the entire flame tube or the entire combustion chamber bordered by the lined flame tube is encased by the generator casing. However, that part of the flame tube which extends in the axial direction between the supply end of the generator casing and the outlet end of the flame tube is encased (preferably entirely) by the generator casing.

[0022] The gas or gas mixture to be heated (hereinafter also referred to simply as "gas to be heated"), for the temperature increase of which the hot gas generator according to the invention is designed, is in particular air or another gas or gas mixture, an exhaust gas or a flue gas.

[0023] Within the scope of the invention, it is particularly preferred if the generator casing in the feed section runs in the form of at least part of an Archimedean spiral around the longitudinal axis (in particular in a complete spiral circumnavigation of the longitudinal axis). The course of an Archimedean spiral is sufficiently known and need not be described in more detail here. The Archimedean spiral shape (or screw shape) ensures that the speed of the gas to be heated is as precisely the same as possible over the entire circumference of the spiral-shaped feed.

[0024] Particularly preferably, guide vanes are arranged in a swirl section of the swirl channel running axially from the feed section towards the connection end, said guide vanes bridging the swirl channel radially. The guide vanes are arranged at an angle to the longitudinal axis and in a helical shape around the flame tube, so that between each two guide vanes arranged next to one another, a sub-channel is formed which screws or winds around the flame tube. The gas to be heated, flowing from the feed section through the swirl channel, flows through the sub-channels and is set into rotation around the flame tube. As a result, the gas flow of the gas to be heated at the end of the swirl channel not only has a movement component in the axial direction, but also a movement component in the circumferential direction.

[0025] In particular, the swirl channel in the swirl section, running around the flame tube, has a substantially constant width. This ensures the most homogeneous "swirling" of the gas to be heated. Within the scope of the invention, it can be provided that the generator casing is located in a space between the swirl channel and the

[0026] The constriction region arranged at the connection end tapers conically. This constriction region can connect directly to the swirl duct or to the connection end, but it can also be spaced apart from it. The inner diameter of the generator shell at the end of the constriction region is preferably a maximum of 90%, in particular a maximum of 80%, preferably a maximum of 70%, of the inner diameter of the generator shell at the beginning of the constriction region. The "constriction" of the flow consisting of the flue gas and the gas to be heated in the constriction region leads to a further increase in the homogeneity of the hot gas.

[0027] Within the scope of the invention, it is also possible for a funnel guide plate to be arranged inside the generator casing, which funnel guide plate runs around the longitudinal axis and is inclined at an angle of 20° to 70°, in particular of 30° to 60°, to the longitudinal axis. The funnel guide plate forms a funnel that tapers towards the connection end, with a wide end that adjoins the generator casing (all around and tightly) and a narrow end that projects freely into the generator casing. The funnel guide plate is arranged in particular after the swirl channel (i.e. between the swirl channel and the connection end), e.g. directly after it or at a distance from it, but can also be arranged in the swirl channel at least with its wide end. If a constriction region is present, the funnel guide plate is preferably arranged in the constriction region (at least with its wider end, but in particular entirely).The hopper baffle (like a constriction area) further increases the homogeneity of the hot gas and can be provided instead of a constriction area or in addition to it (to further constrict the gas flow). Such a hopper baffle is particularly suitable when the connection opening is relatively large, and a constriction area alone only leads to a slight "constriction" (since the inner diameter of the generator shell at the end of the constriction area would be only slightly smaller than at its beginning).

[0028] Within the scope of the invention, it is preferred that the swirl channel enclose at least 50% of the combustion chamber in the axial direction. However, the swirl channel can also enclose at least 75% or even substantially 100% of the combustion chamber. With such a long swirl channel, a particularly uniform distribution of the gas to be heated takes place toward the outlet end of the combustion chamber.

[0029] It is also preferred if the feed section extends in the axial direction over at least 60%, preferably at least 80%, of the swirl channel. Even such a long

[0030] Feed section, which results from a correspondingly wide feed opening, promotes the distribution of the gas to be heated in the swirl channel.

[0031] In particular, within the scope of the invention, an embodiment is preferred in which the swirl channel is delimited in the radial direction towards the longitudinal axis by an inner tube which is tightly connected to the flame tube in the region of the outlet end and extends as far as the inlet end. The inner tube preferably ends at the outlet end and does not protrude beyond the outlet end in the direction of the connection end. Likewise, the inner tube preferably ends at the inlet end and does not protrude beyond this. An annular flange can be provided for a tightly sealed connection all around the flame tube and the inner tube. A cooling gap enclosing the flame tube is formed by the inner tube between the flame tube and the swirl channel (which is delimited by the inner tube in the radial direction towards the flame tube). Ambient air can flow through or be flooded through this cooling gap.The axial length of the cooling gap preferably corresponds to the axial length of the swirl channel, since the inner tube is connected to the flame tube in the region of the outlet end. Even if the cooling gap is located between the swirl channel and the flame tube, the flame tube is nevertheless considered to be enclosed by the swirl channel within the scope of the invention.

[0032] In principle, the cooling gap serves to ventilate the flame tube from behind to prevent it from overheating. Since the flame tube is exposed to the high temperatures of the flue gas despite its refractory lining, it may expand more radially and axially than the generator shell, which is heated less by the gas being heated. The cooling gap thus prevents mechanical stresses from occurring in the hot gas generator due to the different, temperature-related expansions between the flame tube and the generator shell.

[0033] The cooling gap preferably has a substantially constant width around the flame tube, so that the flame tube can expand equally in all directions. The width of the cooling gap can be adapted to the respective operating conditions of the hot gas generator and can be, for example, between 2 mm and 200 mm, in particular between 5 mm and 100 mm. For example, the width of the cooling gap when the hot gas generator is not in operation can be approximately 5-10 mm for a "cooler" gas to be heated and approximately 50-100 mm for a "hotter" gas.

[0034] Within the scope of the invention, it can be provided that a separating web runs in the axial direction in the supply section. This separating web separates a region of the supply section into which the supply line opens and in which the swirl channel is at its maximum width (i.e. in which a radial width of the swirl channel is at its greatest) from a region of the supply section in which the swirl channel is at its maximum tapered (i.e. a region in which a radial width of the swirl channel is at its smallest and which is arranged directly next to the region with the maximum width). The separating web preferably separates the two regions from one another in a tightly sealed manner, but it can also have gas passages. The separating web extends in particular over the entire axial length of the supply section.The separator prevents the gas to be heated from the supply line from flowing directly into the area of ​​the swirl channel with its maximum taper. This forces the gas to be heated to flow around the flame tube after entering the supply section in the direction in which the swirl channel continues to taper, i.e., in which the radial width of the swirl channel continues to decrease as it flows around it. This leads to a uniform distribution of the gas to be heated in the swirl channel (or, if applicable, in the swirl section of the swirl channel) and ultimately to improved hot gas homogeneity.

[0035] Further details, features, and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. It shows:

[0036] Fig. 1 shows a conventional hot gas generator in a lateral sectional view along a sectional plane running vertically and in the direction of a longitudinal axis of the hot gas generator,

[0037] Fig. 2 shows the hot gas generator shown in Fig. 1 in a front view,

[0038] Fig. 3 shows a hot gas generator according to the invention in a lateral sectional view along a sectional plane running vertically and in the direction of the longitudinal axis of the hot gas generator, Fig. 4 shows a sectional view through the hot gas generator shown in Fig. 3 along the sectional plane III-III,

[0039] Fig. 5 shows the hot gas generator according to the invention in a partially sectioned isometric view,

[0040] Fig. 6 shows the hot gas generator according to the invention according to a further embodiment in a lateral sectional view along a sectional plane running vertically and in the direction of the longitudinal axis of the hot gas generator,

[0041] Fig. 7 shows a detail of the hot gas generator shown in Fig. 6.

[0042] Fig. 1 shows a conventional hot gas generator 1, wherein the hot gas generator 1 in Fig. 1 is shown cut along a sectional plane which runs vertically and along a longitudinal axis L of the hot gas generator 1.

[0043] Fig. 2 shows the hot gas generator from Fig. 1 in a front view.

[0044] The known hot gas generator 1 has a burner 2 for generating flue gas, which opens into a combustion chamber 3.

[0045] The combustion chamber 3 is surrounded by a flame tube 4 which has a lining 5 made of a refractory material, for example refractory concrete or ceramic fibers.

[0046] The flame tube 4 has a closed burner end 6, at which the burner 2 opens into the combustion chamber 3, and an open outlet end 7.

[0047] The flame tube 4 is arranged within a tubular generator casing 8 which has an inner diameter which is larger than an outer diameter of the flame tube 4, so that an annular gap, namely the swirl channel 9, is formed between the generator casing 8 and the flame tube 4.

[0048] The tubular generator casing 8 extends from a supply end 11, which terminates at the burner end 6, to a connection end 12, which opens into a connection opening 13. Further lines leading to devices (not shown) requiring hot gas can be connected to the connection opening 13.

[0049] From the side, i.e. transversely to the longitudinal axis L, a supply line 14, the line cross-section of which is aligned orthogonal to a pipe cross-section of the flame tube 4 or the generator casing 8, opens into the swirl channel 9. Through this supply line 14, a gas or gas mixture to be heated (hereinafter: "gas to be heated") can be introduced into the generator casing 8, which flows along the swirl channel 9 and mixes with the flue gas flowing out of the combustion chamber 2 at the outlet end 7 of the flame tube. The supply line 14 of the hot gas generator 1 shown has a circular line cross-section.

[0050] The hot gas formed from the mixing of flue gas and the gas to be heated flows through a static mixing element 15 arranged in the generator casing 8 toward the connection end 12 and exits the hot air generator 1 via the connection opening 13. The static mixing element 15 has, for example, free-standing or interconnected webs and plates that form a forced guide for the hot gas flow and ensure better mixing, so that the mixed temperature of the resulting hot gas is homogenized.

[0051] In Fig. 3, a hot gas generator 1 according to the invention is shown in a lateral sectional view, wherein the sectional plane runs vertically and in the direction of the longitudinal axis L of the hot gas generator 1.

[0052] Fig. 4 shows a cross section through the hot gas generator 1 according to the invention along a sectional plane II I- III shown in Fig. 3.

[0053] In Fig. 5, the hot gas generator 1 according to the invention is shown in a further embodiment in a partially cut-away, isometric view.

[0054] The hot gas generator 1 according to the invention has a similar structure to the conventional hot gas generator 1 shown in Figs. 1 and 2. Therefore, the same reference numerals are used for identical and similar components and elements.

[0055] In the hot gas generator 1 according to the invention, the combustion chamber 3 with the burner 2 opening into it is also surrounded by the lined flame tube 4 with the closed burner end 6 and the open outlet end 7 and does not differ from the combustion chamber 3 of the conventional hot gas generator 1 shown in Fig. 1.

[0056] In the hot gas generator 1 according to the invention, the generator casing 8 also encloses the flame tube 4, so that the swirl channel 9 is formed between the generator casing 8 and the flame tube 4. The supply end 11 of the generator casing 8 in the illustrated hot gas generator 1 according to the invention is spaced from the burner end 6 of the flame tube 4, so that the flame tube 4 or the combustion chamber 3 is not completely enclosed by the generator casing 5 and the swirl channel 9, but only partially. The swirl channel 9 of the hot gas generator 1 according to the invention is divided into a supply section 16 adjoining the supply end 11 (in the illustrated embodiment) and a swirl section 17 adjoining the supply section 16 and extending to the outlet end 8.

[0057] The supply section 16 of the hot gas generator 1 according to the invention extends over the entire axial width Z of the supply line 14, which in the illustrated embodiment has a rectangular line cross-section.

[0058] As can be seen in Fig. 4, the generator casing 8 runs in the feed section 16 in a spiral shape (in the form of part of an Archimedean spiral) around the longitudinal axis L and also around the flame tube 4. A radial width B of the swirl channel 9 is greatest in a first region 18 of the feed section 16, into which the feed line 16 opens, and decreases continuously around the flame tube 4. In a second region 19 of the feed section 16, which directly borders on the first region 18, the radial width B of the swirl channel 9 is smallest.

[0059] A separating web 21, which runs axially along the flame tube 4 in the supply section 16, separates the first region 18 from the second region 19. The gas to be heated, which enters the swirl channel 9 via the supply line 14, therefore flows counterclockwise around the flame tube 4 in the illustrated embodiment. Likewise, the swirl channel 9 tapers counterclockwise starting from the first region 18 (i.e., from the supply line 14), i.e., it becomes increasingly narrower and has an increasingly smaller radial width B.

[0060] The arrows shown in Fig. 4 indicate that the gas to be heated flows around the flame tube 4 from the supply section 16 with uniform pressure into the swirl section 17 of the swirl channel 9.

[0061] In the swirl section 17, guide vanes 22 are arranged which radially bridge the swirl channel 9 (i.e. run from the generator casing 8 to the flame tube 4). The guide vanes 22 are evenly distributed around the flame tube 4 and are arranged or inclined at an angle to the longitudinal axis L, so that they run helically around the flame tube 4 (or along the flame tube 4). Each individual guide vane 22 runs only around a part of the circumference of the flame tube 4 and not around the entire flame tube 4. The guide vanes 22 extend over the entire axial length of the swirl channel 17.

[0062] In Fig. 5, the flame tube 4 together with the associated lining 5 is "cut free" in a lower area in order to better illustrate the helical course of the guide vanes 22 of the mixing element 15 in the vortex area 17.

[0063] Between the outlet end 7 of the flame tube 4 (or the swirl channel 9) and the connecting end 12, the generator casing 8 has a constriction region 23 in which the generator casing 8 tapers toward the connecting end 12. An inner diameter I of the generator casing 8 decreases from the beginning of the constriction region 23 to its end.

[0064] Unlike the conventional hot gas generator 1 shown in Figs. 1 and 2, the hot gas generator 1 according to the invention does not require an additional mixing element 15 arranged downstream of the swirl channel 9. Due to the optimized pressure distribution of the gas to be heated and the swirling of the gas to be heated that already occurs in the swirl region 17 (without the need for an additional mixing element), the overall length (assembly length) of the hot gas generator 1 according to the invention can be significantly shorter than with conventional hot gas generators 1.

[0065] Fig. 6 shows the hot gas generator 1 according to the invention according to a further embodiment and Fig. 7 shows a detail D from Fig. 6 in an enlarged view.

[0066] The hot gas generator 1 according to the invention shown in Figs. 6 and 7 differs only in the following details from the hot gas generator 1 according to the invention shown in Figs. 3 and 4:

[0067] On the one hand, the swirl channel 9 (in particular the supply section 16 of the swirl channel 9) in the hot gas generator 1 shown in Fig. 6 is shorter than in the hot gas generator 1 shown in Figs. 3 and 4.

[0068] Secondly, in the hot gas generator 1 shown in Fig. 6, an inner tube 25 is arranged between the generator casing 8 and the flame tube 4, which inner tube delimits the swirl channel 9 inwards, i.e. towards the longitudinal axis L. The inner tube 25 runs from the supply end 11 of the generator casing 8 to the outlet end 7 of the flame tube 4 and is tightly connected, e.g. welded, to the flame tube 4 at the outlet end 7 via an annular flange 26.

[0069] In detail D shown in Fig. 7, it can be seen that a cooling gap K is formed between the inner tube 25 and the flame tube 4, through which ambient air can flow or be flushed from the supply end 11. The cooling gap K preferably has a constant width (seen in the radial direction) around the flame tube 4.

[0070] Of course, the invention also includes

[0071] Hot gas generators 1 are conceivable which comprise a combination of the features of the above-described embodiments of hot gas generators 1 according to the invention.

[0072] Reference symbol list

[0073] 1 hot gas generator

[0074] 2 burners

[0075] 3 combustion chamber

[0076] 4 flame tube

[0077] 5 Lining

[0078] 6 burner end

[0079] 7 Exit end

[0080] 8 Generator casing

[0081] 9 Swirl channel

[0082] 10

[0083] 11 Feed end

[0084] 12 Connection end

[0085] 13 Connection opening

[0086] 14 Supply line

[0087] 15 Mixing element

[0088] 16 To drove off cut

[0089] 17 vertebrae section

[0090] 18 first area

[0091] 19 second area

[0092] 20

[0093] 21 Divider

[0094] 22 guide plate

[0095] 23 Constriction area

[0096] 24

[0097] 25 inner tube

[0098] 26 Flange

[0099] L Longitudinal axis

[0100] Z Width supply line

[0101] B radial width of swirl channel

[0102] I Inner diameter generator casing

[0103] D Detail

[0104] K Cooling gap

Claims

Claims:

1. Hot gas generator (1) with a longitudinal axis (L), comprising • a burner (2) for generating flue gas, • a combustion chamber (3) which is surrounded by an axially extending, refractory-lined flame tube (4) which is closed at a burner end (6) at which the burner (2) opens into the combustion chamber (3) and open at an outlet end (7), • an axially extending, substantially tubular generator casing (8) which extends from a supply end (11) arranged in the direction of the burner end (6) to a connection end (12) projecting beyond the outlet end (7) and opening into a connection opening (13), and thereby enclosing the flame tube (4) at least in sections, wherein a swirl channel (9) extending from the supply end (11) in the direction of the connection end (12) and enclosing the flame tube (4) is formed between the generator casing (8) and the flame tube (4), and • a supply line (14) for supplying a gas or gas mixture to be heated or heated, which opens into a supply section (16) of the swirl channel (9) and whose line cross-section is aligned transversely, in particular orthogonally, to a tube cross-section of the flame tube (4), characterized in that the supply section (16) extends over the entire width (Z) of the supply line (14) running in the axial direction, and in that the generator casing (8) in the supply section (16) runs spirally around the longitudinal axis (L), so that the swirl channel (9) in the supply section (16) tapers around the flame tube (4) starting from the supply line (14).

2. Hot gas generator according to claim 1, characterized in that the generator casing (8) in the supply section (16) extends spirally around the longitudinal axis (L) in the form of at least part of an Archimedean spiral.

3. Hot gas generator according to claim 1 or 2, characterized in that guide plates (22) are arranged in a swirl section (17) of the swirl channel (9) extending axially from the supply section (16) in the direction of the connection end (12), wherein the guide plates (22) radially bridge the swirl channel (9) and are arranged at an angle to the longitudinal axis (L) and helically around the flame tube (4).

4. Hot gas generator according to claim 3, characterized in that the swirl channel (9) in the swirl section (17) extending around the flame tube (4) has a substantially constant width (B).

5. Hot gas generator according to one of claims 1 to 4, characterized in that the generator casing (8) tapers conically in a constriction region (23) arranged between the swirl channel (9) and the connection end (12), wherein an inner diameter (I) of the generator casing (8) at the end of the constriction region (23) is a maximum of 90%, in particular a maximum of 80%, preferably a maximum of 70%, of the inner diameter (I) of the generator casing (8) at the beginning of the constriction region (23).

6. Hot gas generator according to one of claims 1 to 5, characterized in that inside the generator casing (8), in particular after the swirl channel (9), a funnel guide plate is arranged which runs around the longitudinal axis (L) and is inclined at an angle of 20° to 70°, in particular of 30° to 60°, to the longitudinal axis (L), so that it forms a funnel tapering towards the connection end (12), which connects to the generator casing (8) with a wide end and projects freely into the generator casing (8) with a narrow end.

1. Hot gas generator according to one of claims 1 to 6, characterized in that the swirl channel (9) encloses at least 50%, preferably at least 75%, in particular substantially 100%, of the combustion chamber (3) in the axial direction.

8. Hot gas generator according to one of claims 1 to 7, characterized in that the supply section (16) extends in the axial direction over at least 60%, preferably at least 80%, of the swirl channel (9).

9. Hot gas generator according to one of claims 1 to 8, characterized in that the swirl channel (9) is delimited in the radial direction towards the longitudinal axis (L) by an inner tube (25) which is tightly connected all the way around to the flame tube (4) in the region of the outlet end (7) and extends to the supply end (11), so that a cooling gap (K) surrounding the flame tube (4) is formed between the flame tube (4) and the swirl channel (9).

10. Hot gas generator according to one of claims 1 to 9, characterized in that a separating web (21) runs in the axial direction in the supply section (16), which separates a first region (18) of the supply section (16), into which the supply line (14) opens and in which the swirl channel (9) is maximally wide, from a second region (19) of the supply section (16), in which the swirl channel (9) is maximally tapered, preferably in a sealing manner.

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