DE102010012006A1 - Heat exchanger for thermal exhaust air cleaning system, has heat exchanger pipe, whose inner space is flow-throughable by inner fluid medium, where wall of heat exchanger pipe has turbulence-generating structure at its inner side - Google Patents

Abstract

The heat exchanger has a heat exchanger pipe (208), whose inner space is flow-throughable by an inner fluid medium. A wall (242) of the heat exchanger pipe has a turbulence-generating structure at its inner side (238) or at its outer side (240). The turbulence-generating structure has a structural element (251) which is extended around the longitudinal axis (246) of the heat exchanger pipe over a circumferential angle of 180 degree. Independent claims are also included for the following: (1) a thermal exhaust air cleaning system with a combustion chamber; and (2) a method for cleaning an exhaust air flow by a thermal exhaust air cleaning system.

Description

The present invention relates to a heat exchanger for a thermal exhaust air purification system comprising at least one heat exchanger tube, the interior of which can be flowed through by an internal fluid medium and on the outside of which an external fluid medium can flow.

In this case, the outer fluid medium may be, in particular, a crude gas stream contained in an oxidizable constituent which, after passing through the heat exchanger, is fed to a combustion chamber of the thermal exhaust air purification plant. In the combustion chamber, a clean gas stream is generated by at least partially oxidizing the oxidizable constituents of the crude gas stream, which then flows through the interior of the heat exchanger tube as an inner fluid medium, so that heat is transferred from the clean gas stream to the raw gas stream.

Alternatively, the raw gas may be used as the inner fluid medium and the clean gas as the outer fluid medium.

For the heat exchange between the raw gas stream and the clean gas flow of a thermal exhaust air purification system smooth tubes are used in the prior art.

Further, it is known to incorporate additional components, such as sheet metal strips twisted around their longitudinal direction, into such smooth tubes to create turbulence in the flow through the interior of the heat exchanger tube and thereby enhance the heat exchange between the inner fluid medium and the outer fluid medium. However, such incorporated in the heat exchanger tubes turbulence devices lead to increased manufacturing costs, increase the flow resistance and can lead to blockages by addition of solid particles from the inner fluid medium.

The present invention has for its object to provide a heat exchanger for a thermal exhaust air purification system of the aforementioned type, which allows a particularly efficient heat transfer between the inner fluid medium and the outer fluid medium.

This object is achieved in a heat exchanger for a thermal exhaust air purification system having the features of the preamble of claim 1 according to the invention in that the wall of at least one heat exchanger tube has on its inside and / or on its outside a turbulence generating structure.

The present invention is based on the concept of achieving an increased turbulence in the inner fluid medium flowing through the interior of the heat exchanger tube and / or in the outer fluid medium flowing around the heat exchanger tube in that the wall of the heat exchanger tube itself on its inside and / or on its Outside is structured so that in the turbulence generating structure flowing to the Fiuidströmung a strong turbulence is generated, which increases the heat transfer through the wall of the heat exchanger tube between the inner fluid medium and the outer fluid medium.

Characterized in that according to the invention the desired turbulence is generated by the surface structure of the wall of the heat exchanger tube itself, it is not necessary to introduce additional components in the heat exchanger tube in order to increase the turbulence of the flow and to improve the heat exchange.

As a result, the production and material costs for the heat exchanger according to the invention is reduced.

Furthermore, in the interior of the heat exchanger tube, a large flow-through cross section is obtained, which reduces the flow resistance and avoids blockages by the addition of solid particles from the inner fluid medium.

Preferably, the turbulence-generating structure comprises at least one structural element which extends over a circumferential angle of at least 180 ° about the longitudinal axis of the heat exchanger tube.

Characterized in that the turbulence generating structure comprises at least one structural element, which extends, preferably without interruptions, over a circumferential angle of at least 180 ° around the longitudinal axis of the heat exchanger tube, a more homogeneous temperature distribution along the tube circumference is achieved, as would be the case with structural elements which extend only over a smaller circumferential angle.

The more homogeneous temperature distribution along the circumference of the tube achieves more efficient heat transfer between the inner fluid medium and the outer fluid medium.

It is particularly favorable for achieving a homogeneous temperature distribution along the Pipe circumference, when the turbulence generating structure comprises at least one structural element which extends over a circumferential angle of at least 360 ° around the longitudinal axis of the heat exchanger tube around.

Furthermore, it can be provided that the turbulence-generating structure comprises a plurality of structural elements which extend over a circumferential angle of at least 180 °, preferably of at least 360 °, around the longitudinal axis of the tube.

In a preferred embodiment of the invention, all structural elements of the turbulence-generating structure extend over a circumferential angle of at least 180 °, preferably at least 360 °, about the longitudinal axis of the tube.

The at least one structural element can in particular be designed as a projection formed on the wall of the heat exchanger tube or a depression formed on the wall of the heat exchanger tube and preferably have a substantially linear shape.

Preferably, no additional components, in particular no components for generating turbulence, are present in the interior of the heat exchanger tube.

The turbulence-generating structure comprises as structural elements preferably on the inside and / or on the outside of the wall of the heat exchanger tube formed projections and / or depressions, which are in particular formed substantially linear.

The structural lines, along which these projections and / or depressions extend, are preferably oriented at least in sections obliquely to the longitudinal axis of the heat exchanger tube.

It is particularly favorable if the turbulence-generating structure comprises as structural element one or more projections on the inside of the wall of the heat exchanger tube and / or one or more depressions on the outside of the wall of the heat exchanger tube.

The structural lines, along which the projections or depressions extend, may in principle extend from an initial point to an end point over an arbitrary length or may also be of annular design.

Furthermore, it is possible that the projections or depressions extend at least in sections along helical structure lines on the wall of the heat exchanger tube.

In this case, the structural elements formed as projections or recesses extend over a circumferential angle corresponding to a multiple of 360 ° about the longitudinal axis of the heat exchanger tube.

In a preferred embodiment of the invention, it is provided that at least one heat exchanger tube of the heat exchanger is designed as a swirl tube.

Such swirl tubes are for example in the DIN 28178 (as amended in May 2009).

A swirl tube has a longitudinally extending along a helical path deformation of the wall, through which on the inside of the wall, a helical projection and corresponding thereto on the outside of the wall, a helical recess is formed.

The wall thickness of the wall is not substantially changed by this deformation.

The helical projection and the helical depression form structural elements of a turbulence-generating structure of the swirl tube.

A swirl tube can in particular be produced by an embossing process which is carried out on a smooth tube.

According to the invention, a single swirl tube can be used whose swirling has one or more line-shaped projections and one or more line-shaped depressions which wind in the same direction of rotation about the longitudinal axis of the swirl tube.

Alternatively, it can also be provided that at least one heat exchanger tube is designed as a cross-twist tube having at least two helical projections with opposite rotational direction about the longitudinal axis of the swirl tube and at least two helical depressions with opposite rotational direction about the longitudinal axis of the swirl tube.

In the case of a swirl tube, the angle at which the helical path of the swirl is inclined relative to a plane perpendicular to the longitudinal axis of the swirl tube is referred to as swirl angle α.

In the heat exchanger according to the invention can be provided that at least one heat exchanger tube has a helix angle α of about 10 ° to about 40 °, preferably from about 20 ° to about 30 °, in particular of about 25 °.

By using swirl tubes as heat exchanger tubes can be compared to the use of smooth tubes with the same heat transfer performance, a reduction of the required tube length by up to 15% for a cross-countercurrent principle working heat exchanger and up to 30% in a direct countercurrent principle working heat exchanger can be achieved.

If the tube length is maintained, the heat transfer performance of the heat exchanger increases correspondingly when using swirl tubes. The use of swirl tubes in the heat exchanger of a thermal exhaust air purification system thus reduces the required system size or increases the efficiency of heat transfer with the same size of the heat exchanger.

In order to achieve a good turbulence-generating effect of the turbulence-generating structure (be it with a swirl tube or with a differently formed turbulence-generating structure), it is favorable if the turbulence-generating structure has a radial extent which is at least 20% of the wall thickness t of FIG Heat exchanger tube is.

In the case of a swirl tube, the radial extent of the turbulence-generating structure corresponds to the swirl depth h, d. H. the difference caused by the twist between the largest outer radius of the heat exchanger tube and the smallest outer radius of the heat exchanger tube (in the region of the depression generated by the swirling).

In order not to impair the mechanical stability of the heat exchanger tube and not unnecessarily reduce the flow-through free cross section of the heat exchanger tube, it is also advantageous if the turbulence generating structure has a radial extent which is smaller than the wall thickness t of the heat exchanger tube.

Preferably, the radial extent of the turbulence-generating structure is smaller than half the wall thickness t of the wall of the heat exchanger tube.

In principle, the heat exchanger tube may be formed from any material which permanently has sufficient mechanical and chemical resistance at the highest temperature occurring in the inner fluid medium or in the outer fluid medium during operation of the heat exchanger.

It is particularly favorable when the wall of the heat exchanger tube is formed from a metallic material, preferably from a stainless steel material.

Suitable stainless steel materials include stainless steel grades 1.4301 (having a reduced carbon content of at most 0.045 weight percent), 1.4401 (having a reduced carbon content of at most 0.045 weight percent), 1.4541 and 1.4571 according to U.S. Pat DIN EN 10217-7 ,

In principle, the heat exchanger tube can have a flexible wall or a rigid wall.

In a preferred embodiment of the invention it is provided that the heat exchanger of the thermal exhaust air purification system comprises a plurality of heat exchanger tubes, which together form a heat exchanger tube bundle.

Such a heat exchanger tube bundle may in particular be substantially hollow-cylindrical, wherein the heat exchanger tubes are arranged in one or more layers about a longitudinal axis of the heat exchanger tube bundle and wherein the heat exchanger tubes of the same layer each have the same radial distance from the longitudinal axis of the heat exchanger tube bundle.

Preferably, the heat exchanger tubes of the same layer are distributed substantially equidistantly along the circumference of the heat exchanger tube bundle in the respective layer.

The heat exchanger tube bundle may comprise one or more layers of heat exchanger tubes, preferably two to four layers, in particular three layers.

The flow path of the outer fluid medium, in particular by mechanical deflection, be guided so that the outer fluid medium flows around at least one heat exchanger tube, preferably substantially all heat exchanger tubes of the heat exchanger at least in sections, preferably substantially everywhere, transversely to the longitudinal direction of the respective heat exchanger tube ,

Furthermore, in order to maximize the heat transfer, the mean flow direction of the outer fluid medium in the heat exchanger is preferably opposite to the mean flow direction directed to the internal fluid medium in the heat exchanger.

The heat exchanger according to the invention can thus be constructed according to the cross-countercurrent principle.

Alternatively or additionally, it can also be provided that the flow path of the outer fluid medium through the heat exchanger is guided so that the outer fluid medium at least one heat exchanger tube, preferably substantially all heat exchanger tubes, the heat exchanger at least in sections, preferably substantially everywhere substantially flows around parallel to the longitudinal axis of the respective heat exchanger tube.

Also in this embodiment of the flow path of the outer fluid medium is preferably provided that the mean flow direction of the outer fluid medium is directed through the heat exchanger opposite to the mean flow direction of the inner fluid medium through the heat exchanger.

The heat exchanger according to the invention can therefore also be designed according to the direct countercurrent principle.

By the interaction of the turbulence generating structure on the inside and / or on the outside of the wall of the heat exchanger tube and the direct countercurrent principle, a particularly effective heat transfer between the inner fluid medium and the outer fluid medium is achieved.

In order to enable a flow guidance for the external fluid medium according to the direct countercurrent principle, it is advantageous if the heat exchanger comprises at least one holding element on which at least one heat exchanger tube is held, wherein the holding element at least one passage opening for the passage of the outer fluid Having medium through the retaining element.

In this case, the outer fluid medium can flow through the passage opening in the holding element parallel to the longitudinal axis of the heat exchanger tube.

In contrast, it is preferably provided in a heat exchanger according to the cross-countercurrent principle that the heat exchanger comprises at least one holding element on which at least one heat exchanger tube is held, wherein the holding element has no passage opening for the passage of the outer fluid medium through the holding element, so that the outer fluid medium can not flow through the holding element, but is deflected by the holding element.

By using a plurality of relatively staggered retaining elements, a mechanical deflection device can be provided in this case, which forces the outer fluid medium onto a tortuous flow path through the heat exchanger.

The heat exchanger according to the invention is particularly suitable for use in a thermal exhaust air purification system comprising a combustion chamber and at least one heat exchanger according to the invention.

A thermal exhaust air purification system according to the invention preferably has a raw gas throughput of at least 1,000 Nm ³ / h, in particular of at least 10,000 Nm ³ / h (1 Nm ³ = 1 standard cubic meter).

Such a thermal exhaust air purification system can be used for the treatment of exhaust air, which comes from a variety of industrial production processes, for example from the painting of workpieces, in particular vehicle bodies, from the impregnation of cardboard or filter papers, from the production of rubberized conveyor belts, from the printing of Packaging materials, from the coating of credit card blanks, from wallpaper production, from the coating of lead strip, from the manufacture of seals or from the impregnation of woven glass.

A particularly compact design of the thermal exhaust air purification system results when at least one heat exchanger at least partially, preferably substantially completely, surrounds the combustion chamber of the thermal exhaust air purification system.

Alternatively or additionally, however, it can also be provided that at least one heat exchanger, which serves in particular for preheating the raw gas before it enters the combustion chamber, is arranged offset in the direction of the longitudinal axis of the combustion chamber relative to the combustion chamber.

In a preferred embodiment of the thermal exhaust air purification system according to the invention it is provided that the thermal exhaust air purification system comprises a clean gas duct through which clean gas generated in the combustion chamber flows from a clean gas outlet of the combustion chamber to a clean gas inlet of the heat exchanger, the clean gas duct at least partially, preferably substantially completely, the Combustion chamber surrounds and at least partially, preferably substantially completely surrounded by the heat exchanger. This makes it possible to guide the clean gas in the heat exchanger in countercurrent to the raw gas, without increasing the overall length of the unit of combustion chamber and heat exchanger.

In principle, the clean gas generated in the combustion chamber of the thermal exhaust air purification system can be used as an outer fluid medium or as an inner fluid medium.

Since the clean gas has a higher temperature than the fluid medium flowing through the secondary side of the heat exchanger, it is favorable if clean gas generated in the combustion chamber can be supplied to the interior of a heat exchanger tube, so that the clean gas is used as the inner fluid medium. In this case, the thermal insulation of an outer casing of the heat exchanger must be adjusted only to the lower temperature of the outer fluid to be heated by the clean gas, which is lower than the temperature of the clean gas.

The heat exchanger according to the invention can be used in the thermal exhaust air purification system to transfer heat from the pure gas generated in the combustion chamber of the thermal exhaust air purification system to the raw gas to be supplied to the combustion chamber, in order to preheat the raw gas before the combustion of the oxidizable constituents contained therein.

Alternatively or additionally, however, the thermal exhaust air purification system may also comprise at least one heat exchanger according to the invention, by means of which heat from a pure gas generated in the combustion chamber of the thermal exhaust air purification system can be transferred to a fluid medium which is different from the raw gas supplied to the combustion chamber of the thermal exhaust air purification system.

• – eine Flüssigkeit sein, aus welcher ein Dampf erzeugt werden soll;
• – ein zu erwärmendes Thermalöl sein;
• – ein Kaltwasser sein, aus welchem Heißwasser oder Warmwasser erzeugt werden soll; oder
• – eine Umluft oder Frischluft sein, welche erwärmt und einem durch erwärmte Zuluft zu beheizenden Raum zugeführt werden soll.

For example, this different from the raw gas fluid medium which flows through the heat exchanger on the secondary side,

• A liquid from which a vapor is to be generated;
• - be a thermal oil to be heated;
• - be a cold water from which hot water or hot water is to be generated; or
• - Be a circulating air or fresh air, which should be heated and fed to a heated supply air to be heated room.

The thermal exhaust air purification system may in particular comprise two or more heat exchangers designed according to the invention, by means of which heat can be transferred from the clean gas to a fluid medium different from the raw gas.

In particular, when the raw gas comes from a Lackierbereich, in which workpieces are painted, it is advantageous if the thermal exhaust air purification system comprises a heat exchanger, by means of which heat from the generated in the combustion chamber of the thermal exhaust air purification system clean gas is transferable to a supply air, the one Dryer is fed, in which the painted workpieces are dried.

• – Erzeugen eines Reingasstroms durch zumindest teilweises Oxidieren der oxidierbaren Bestandteile des Abluftstroms in einer Brennkammer der thermischen Abluftreinigungsanlage; und
• – Übertragen von Wärme aus dem Reingasstrom auf ein fluides Medium mittels mindestens eines Wärmetauschers.

The present invention further relates to a method for purifying an exhaust air stream containing oxidizable constituents by means of a thermal exhaust air purification system, the method comprising the following method steps:

• - Generating a clean gas flow by at least partially oxidizing the oxidizable components of the exhaust air stream in a combustion chamber of the thermal exhaust air purification system; and
• - Transferring heat from the clean gas flow to a fluid medium by means of at least one heat exchanger.

The present invention has the further object of providing a method of the aforementioned type, in which the heat transfer from the clean gas flow to the fluid medium takes place particularly efficiently.

This object is achieved in a method having the features of the preamble of claim 17 according to the invention in that at least one heat exchanger is used which comprises at least one heat exchanger tube whose wall has on its inside and / or on its outside a turbulence-generating structure.

By virtue of such a turbulence-generating structure, the turbulence in the heat exchanger tube and / or around the heat exchanger tube is markedly increased, without requiring the installation of additional components into the heat exchanger tube.

The turbulence-generating structure can be produced by machining the pipe surfaces without having to install additional components in the pipe or to attach them to the pipe.

The heat exchanger according to the invention can be connected directly to the combustion chamber of the thermal exhaust air purification system or be made downstream and be connected to the combustion chamber via a clean gas line.

Preferably, a bypass line is provided for at least one heat exchanger according to the invention, the thermal exhaust air purification system, by means of softer the clean gas can be fluidly passed to the respective heat exchanger over.

Such a bypass line preferably has at least one bypass flap in order to control or regulate the volume flow through the bypass line.

By using a heat exchanger according to the invention with a turbulence-generating structure on the inside and / or on the outside of the wall of at least one heat exchanger tube, the thermal efficiency of a thermal exhaust air purification system is increased.

The length of the heat exchanger can thereby be shortened and / or the number of heat exchanger tubes of the heat exchanger can be reduced.

The heat of the hot clean gas can, preferably in a heat exchanger according to the invention, be used for preheating the raw gas and / or for generating process heat and thus be recovered.

The primary energy requirement of the thermal exhaust air purification system is reduced by using the heat exchanger according to the invention.

Further features and advantages of the invention are the subject of the following description and the drawings of exemplary embodiments.

In the drawings show:

1 a schematic block diagram of a thermal exhaust air purification system with an integrated heat exchanger for heating a raw gas by a clean gas generated in a combustion chamber of the exhaust air purification system and with three other heat exchangers for steam generation, water heating and air heating by means of the clean gas;

2 a schematic longitudinal section through a combustion chamber and surrounding the combustion chamber clean gas raw gas heat exchanger;

3 a schematic cross section through the combustion chamber with integrated heat exchanger 2 in the area of a raw gas inlet;

4 a top view of the combustion chamber with integrated heat exchanger from above 2 and 3 , with the line of sight in the direction of the arrow 4 in 2 ;

5 a schematic cross section through the heat exchanger from the 2 to 4 ;

6 a schematic perspective, partially sectioned view of the combustion chamber with integrated heat exchanger from the 2 to 5 ;

7 a schematic longitudinal section through a heat exchanger tube designed as a swirl tube of the heat exchanger from the 2 to 6 ;

8th an enlarged view of the area I out 7 ;

9 a schematic longitudinal section through a designed as a cross-twist tube heat exchanger tube;

10 an enlarged view of the area II out 9 ;

11 a schematic longitudinal section through a second embodiment of a combustion chamber with integrated clean gas raw gas heat exchanger, wherein the raw gas flows through the heat exchanger in countercurrent antiparallel to the flow direction of the clean gas;

12 a schematic cross section through a heat exchanger tube holding element of the heat exchanger 11 ;

13 a schematic fragmentary view of an alternative heat exchanger tube retaining element for the heat exchanger from the 11 and 12 ;

14 a schematic diagram of a third embodiment of a combustion chamber with integrated clean gas raw gas heat exchanger, wherein the heat exchanger is arranged in the longitudinal direction of the combustion chamber behind the combustion chamber; and

15 a schematic diagram of a fourth embodiment of a combustion chamber with integrated clean gas raw gas heat exchanger, wherein the raw gas to be heated flows through the interiors of the heat exchanger tubes of the heat exchanger.

Identical or functionally equivalent elements are denoted by the same reference numerals in all figures.

One in the 1 to 10 shown as a whole with 100 referred thermal exhaust air purification system comprises a combustion chamber 102 , at the combustion chamber entrance 104 a burner 106 is arranged, over a Brennstomeitung 108 with a suitable fuel, such as natural gas, can be supplied.

The exhaust air to be cleaned is a gas mixture containing oxidizable components, such as volatile organic compounds.

The oxidizable components of the exhaust air are in the combustion chamber 102 , together with the added fuel, oxidized and thus rendered harmless.

That of the combustion chamber 102 supplied gas mixture containing the combustible components is referred to below as the raw gas.

That in the combustion chamber 102 The gas mixture produced by oxidation of the oxidizable constituents of the raw gas is referred to below as pure gas.

The raw gas comes from a in 1 purely schematically represented and with 110 designated raw gas source.

The from the raw gas source 110 the thermal exhaust air purification plant 100 supplied raw gas volume flow is preferably at least 1,000 Nm ³ / h (1 Nm ³ = 1 standard cubic meter), in particular at least 10,000 Nm ³ / h.

In a raw gas supply line 112 which the raw gas source 110 with a raw gas inlet 114 a recuperative clean gas raw gas heat exchanger 116 is a crude gas valve 118 for controlling or regulating the raw gas flow through the raw gas supply line 112 and a raw gas blower 120 arranged, which the raw gas from the raw gas source 110 to the combustion chamber 102 promotes.

Further, in the raw gas supply line 112 a fresh air supply line 122 open, via which oxidizing agent in the form of fresh air to the crude gas is immiscible.

The fresh air stream added to the crude gas stream is by means of a fresh air supply line 122 arranged fresh air damper 124 controllable or controllable.

The clean gas crude gas heat exchanger 116 , the structure of which will be described in more detail below, will be the secondary side of the raw gas and the primary side of which from the combustion chamber 102 flows through escaping clean gas.

A raw gas outlet 126 the clean gas raw gas heat exchanger 116 is with a raw gas entry 128 the combustion chamber 102 connected.

A clean gas outlet 130 the combustion chamber 102 is via a clean channel 132 with a clean gas entrance 134 the clean gas raw gas heat exchanger 116 connected.

To a clean gas outlet 136 the clean gas raw gas heat exchanger 116 is a clean gas line 138 connected by one or more downstream heat exchangers 140 , which are flowed through by the clean gas on the primary side, up to an exhaust chimney 142 leads.

From the clean gas channel 132 branches a bypass line 144 from which downstream of the clean gas outlet 136 the clean gas raw gas heat exchanger 116 in the clean gas line 138 empties.

Through this bypass line 144 can the downstream heat exchangers 140 at least part of the clean gas from the combustion chamber 102 bypassing the clean gas raw gas heat exchanger 116 be fed directly when the heat demand at one of the downstream heat exchanger 140 is particularly high.

The bypass current through the bypass line 144 is by means of one in the bypass line 144 arranged bypass flap 146 controllable or controllable.

Each of the downstream heat exchangers 140 is preferably also with its own bypass line 148 provided, which occurs before the clean gas 150 of the respective heat exchanger 140 from the clean gas line 138 branches off and after a clean gas exit 152 of the respective heat exchanger 140 again in the clean gas line 138 opens.

The volume flow through the respective bypass line 148 can by means of one each in the bypass line 148 arranged bypass flap 154 be controlled or regulated.

Furthermore, in the clean gas line 138 before each of the downstream heat exchangers 140 one heat exchanger flap each 156 arranged, by means of which the clean gas flow through the respective downstream heat exchanger 140 is controllable or controllable.

It is thus possible in particular, the clean gas flow completely to one of the downstream heat exchanger 140 to pass over when at the respective heat exchanger 140 on the secondary side no Heat demand exists by the associated heat exchanger flap 156 completely closed and the associated bypass flap 154 is opened.

The heat transfer from the clean gas to the respective downstream heat exchanger 140 Secondary fluid medium flowing through can be used in many ways, for example, for steam generation, thermal oil heating, hot water or hot water production or Umluft- or fresh air heating.

For example, it may be provided that a first downstream heat exchanger 140a is used to generate steam from a feedwater, wherein the feedwater enters a feedwater 158 of the heat exchanger 140a via a feedwater supply line 160 in which a feedwater pump 164 can be arranged, can be fed.

The in the heat exchanger 140a Steam generated from the clean gas due to the heat transfer is via a steam discharge line 162 going to a steam outlet 164 of the heat exchanger 140a is connected, supplied to a place of use.

A second downstream heat exchanger 140b can be used to produce hot water from a cold water entering a kaite water 166 of the heat exchanger 140b via a cold water supply line 168 is fed, in which a cold water pump 170 can be arranged.

That in the heat exchanger 140b hot water generated by heat transfer from the clean gas by heating the cold water is via a to a hot water outlet 172 of the heat exchanger 140b connected hot water discharge line 174 fed to a place of use.

The water temperature in the hot water discharge pipe 174 can by means of a temperature sensor 176 be measured.

Depending on the desired setpoint temperature can then by a (not shown) control device of the thermal exhaust air purification system 100 the clean gas flow through the heat exchanger 140b (by means of the heat exchanger flap 156 and / or the bypass flap 154 ) and / or the heat exchanger 140b supplied cold water flow (for example, via the pumping power of the cold water pump 170 ) are changed so that the desired set temperature in the hot water discharge line 174 is reached.

A third heat exchanger 140c can be used to heat fresh air or circulating air, which is a room to be heated, such as a dryer 178 , can be fed.

The fresh air to be heated or recirculated air is an air inlet 180 of the heat exchanger 140c via an air supply line 182 fed, in which a Zuluftgebläse 184 can be arranged.

The heat transfer from the clean gas in the heat exchanger 140c heated air is sent via an air outlet 186 of the heat exchanger 140c connected air discharge line 188 the place of use, for example the dryer 178 , fed.

In the air discharge line 188 Can the air temperature by means of a temperature sensor 190 be measured.

Depending on the in the air discharge line 188 measured temperature, the clean gas flow through the heat exchanger 140c (by means of the heat exchanger flap 156 and / or the bypass flap 154 ) and / or the supply air flow through the heat exchanger 140c (For example, by means of a change in the speed of the Zuluftgebläses 184 ) are changed so that the desired target temperature of the air in the air discharge line 188 is reached.

The combustion chamber 102 and the associated clean gas raw gas heat exchanger 116 the thermal exhaust air purification system 100 out 1 are in the 2 to 6 shown in detail.

In particular from 2 it can be seen that the combustion chamber 102 is formed substantially cylindrical, along a central longitudinal axis 192 from a burner-side end face 194 up to a burner 106 opposite end face 196 extends and from a hollow cylindrical combustion chamber wall 198 is limited.

The combustion chamber 102 is of the in this embodiment substantially hollow cylindrical clean gas raw gas heat exchanger 116 surrounded, which at its the combustion chamber 102 remote radial outer side through a cylindrical heat exchanger outer housing 200 and at its the combustion chamber 102 facing radial inside through a likewise substantially cylindrical heat exchanger inner housing 202 is limited.

The heat exchanger inner housing 202 is supported by support rings 204 at the combustion chamber wall 198 from.

Through the space between the combustion chamber wall 198 and the heat exchanger inner housing 202 is the clean channel 132 formed, which faces away from the burner end face 196 the combustion chamber 102 with the adjacent to the burner side end face 194 the combustion chamber 102 arranged clean gas inlet 134 the clean gas raw gas heat exchanger 116 combines.

In the space between the heat exchanger inner housing 202 and the heat exchanger outer casing 200 is a bunch 206 from a variety of heat exchanger tubes 208 arranged in which 2 are indicated by dash-dotted lines.

The heat exchanger tubes 208 all are substantially parallel to the longitudinal axis 192 and form, as best of the 5 and 6 it can be seen, several, for example three, cylindrical heat exchanger tube layers 210 in which the heat exchanger tubes 208 each with the same radial distance from the longitudinal axis 192 and are arranged distributed substantially equidistantly along the circumference.

How best 6 It can be seen, is any heat exchanger tube 208 at several, in the direction of the longitudinal axis 192 successive and preferably substantially equidistantly arranged holding elements 212 held, which, for example, as a substantially annular retaining plates 214 are formed.

The heat exchanger tubes 208 pass through openings in the holding elements 212 and lie with their outsides 240 fluid-tight to the holding elements 212 on, so that essentially no fluid in the outside of the heat exchanger tubes 208 lying areas by the holding elements 212 can pass through.

At both ends are the heat exchanger tubes 208 each with one of the retaining elements 212 cohesively connected, for example, welded.

In the direction of the longitudinal axis 192 follow inner holding elements 212a with a smaller inner radius and a smaller outer radius and outer retaining elements 212b with a larger outer radius and a larger inner radius than the inner holding elements 212a alternately on each other.

The inner holding elements 212a have an inner radius, which is substantially the radius of the outer side of the peripheral wall of the heat exchanger inner housing 202 corresponds, so that substantially no fluid between the radially inner edge of the inner holding elements 212a and the heat exchanger inner housing 202 can happen.

The inner holding elements 212a rely on sliding shoes 218 on the heat exchanger inner housing 202 but are not fixed to the heat exchanger inner housing 202 connected so that the inner retaining elements 212a to compensate for differential thermal expansions due to temperature gradients or due to differences in thermal expansion coefficients relative to the heat exchanger inner housing 202 in the direction of the longitudinal axis 192 can move.

The outer radius of the inner holding elements 212a is only slightly larger than the outer radius of the bundle 206 of heat exchanger tubes 208 so that between the outer edge 220 the inner retaining elements 212a on the one hand and the inside of the heat exchanger outer casing 200 on the other hand, an outer passage gap 222a remains, through which a fluid can pass.

The outer radius of the outer holding elements 212b corresponds substantially to the radius of the inside of the peripheral wall of the heat exchanger outer casing 200 so that the outer retaining elements 212b with its outer edge on the inside of the heat exchanger outer casing 200 abut and substantially no fluid between the outer support members 212b and the heat exchanger outer casing 200 can happen.

The inner radius of the outer holding elements 212a is only slightly smaller than the inner radius of the bundle 206 of heat exchanger tubes 208 so that between the inner edge 224 the outer retaining elements 212b and the heat exchanger inner housing 202 an inner passage gap 222b remains, through which a fluid can pass.

Thus, the inner holding elements form 212a and the outer retaining elements 212b in the radial direction of the longitudinal axis 192 offset from each other, a mechanical deflection and a labyrinth-shaped subdivision of the outside of the heat exchanger tube 208 remaining interior 226 the clean gas raw gas heat exchanger 116 , so in this interior 226 a winding flow path 228 is designed for a fluid medium.

This interior 226 the clean gas raw gas heat exchanger 116 is flowed through during operation of the preheated raw gas, which serves as an outer fluid medium in this embodiment.

As the raw gas through the retaining elements 212 a winding flow path 228 is forced, the raw gas flows around the heat exchanger tubes 208 in which the clean gas serving as internal fluid medium flows, mostly transverse to the longitudinal direction of the heat exchanger tubes 208 ,

Furthermore, since the mean flow direction 230 the clean gas in the heat exchanger tubes 208 from the burner side front 194 to the end facing away from the burner 196 is directed and the mean flow direction of the raw gas along the flow path 228 essentially antiparallel to the flow direction 230 the clean gas through the heat exchanger tubes 208 directed, works the clean gas raw gas heat exchanger 116 in this embodiment, essentially according to the cross-countercurrent principle.

The entry of the raw gas into the clean gas raw gas heat exchanger 116 takes place via a radial direction of the heat exchanger outer housing 200 protruding raw gas inlet 232 near the burner 106 remote end of the clean gas raw gas heat exchanger 116 in its interior 226 flows (see in particular the 3 and 4 ).

The outlet of the clean gas from the clean gas raw gas heat exchanger 116 takes place via a clean gas collection chamber 234 at the burner 106 remote end of the clean gas raw gas heat exchanger 116 , in which the clean gas downstream ends of the heat exchanger tubes 208 lead in (see in particular 2 ).

The clean gas collection chamber 234 forms the beginning of the clean gas line 138 through which the clean gas to the downstream heat exchangers 140 flows.

The bypass line 144 through which the clean gas on the primary side of the clean gas raw gas heat exchanger 116 can be passed over is in this embodiment by a so-called compensator 236 formed, which for example has the shape of a hollow cylinder and on the one hand in the burner 106 opposite end of the combustion chamber 102 and on the other hand into the clean gas collection chamber 234 flows (see in particular 2 ).

Further, the compensator 236 , For example, at its Sammelkammerseitigen end, with the bypass flap 146 provided, which allows the proportion of clean gas flow from the combustion chamber 102 set, which directly from the combustion chamber 102 in the clean gas collection chamber 234 enters, without first the clean gas raw gas heat exchanger 116 to happen.

To the effectiveness of the heat transfer from the clean gas to the raw gas in the clean gas raw gas heat exchanger 116 To increase, are the heat exchanger tubes 208 on the inside 238 and on the outside 240 their wall 242 provided with a turbulence generating surface structure.

In particular, it may be provided that the heat exchanger tubes 208 as swirl tubes 244 are formed.

Like from the 7 and 8th can be seen, has such a swirl tube 244 one along a helical path about the longitudinal axis 246 of the swirl tube 244 running deformation of the wall 242 on, through which on the inside 238 a helical projection 248 and accordingly on the outside 240 the wall 242 a helical recess 250 is trained.

The lead 248 and the depression 250 each form a structural element 251 the turbulence generating structure, which extends over a circumferential angle of a multiple of 360 ° about the longitudinal axis of the swirl tube 244 extends around.

The total wall thickness t of the wall 242 essentially does not change.

The spin of the swirl tube 244 can be made in particular by an embossing process, which is carried out on a normal hollow cylindrical smooth tube.

The twist depth h (see 8th ), ie the difference caused by the swirling between the largest outer radius of the tube and the smallest outer radius of the tube (in the region of the depression 250 ), is significantly smaller than the outer diameter D and also significantly smaller than the inner diameter d of the heat exchanger tube 208 such that the free cross-section of the heat exchanger tube through which a fluid, for example the clean gas, can flow 208 is reduced only slightly by the spin.

Preferably, the outer diameter D is a heat exchanger tube 208 in the range of about 20 mm to about 90 mm.

The wall thickness of a heat exchanger tube 208 is preferably in the range of about 1 mm to about 2 mm, more preferably about 1.5 mm to 1.6 mm.

The twist depth h is preferably in the range of about 0.3 mm to about 0.9 mm.

Preferably, the twist depth h is smaller than the wall thickness t, in particular smaller than half the wall thickness t.

On the other hand, to achieve a significant turbulence-generating effect by the swirl, the swirl depth h is preferably at least 20% of the wall thickness t.

The twist angle α (see 8th ), ie the angle about which the helical path of the swirl with respect to a perpendicular to the longitudinal axis 246 of the heat exchanger tube 208 extending level 252 is inclined, is preferably at least 10 °, in particular at least 20 °.

Furthermore, the twist angle α is preferably at most 40 °, in particular at most 30 °.

By the swirl of the heat exchanger tubes 208 In the area of the laminar boundary layer, geometric structures are generated which lead to a disturbance of the laminar boundary layer and thus to turbulence. These turbulences are also referred to as "turbulence bales" and are in 7 through the arrows 254 indicated.

Due to the mixing, wetting and flow of the turbulence bales over the entire tube, there is an increased contact between the molecules involved both with each other and with the limiting surfaces. The heat transfer increases more than the pressure loss. At the same time have swirl tubes by the self-cleaning effect less pollution.

By the swirl of the heat exchanger tubes 208 is a high turbulence of the flow within the heat exchanger tubes 208 and also the flow on the outside of the heat exchanger tubes 208 achieved, whereby the heat transfer between the medium on the inside and the medium on the outside of the wall 242 the heat exchanger tubes 208 is increased, without requiring additional components must be introduced into the interior of the tubes, which would significantly increase the flow resistance and also could lead to blockage of the pipes by the addition of solid particles.

When used in a bundle heat exchanger according to the cross-countercurrent principle, the tube length of the heat exchanger tubes 208 with the same heat transfer performance can be reduced by up to 15% compared to a design with smooth tubes.

With the same tube length, the heat transfer performance is increased accordingly when using swirl tubes.

The use of swirl tubes 244 thus reduces the plant size of the thermal exhaust air purification system 100 or increases the efficiency at the same size of clean gas raw gas heat exchanger 116 ,

The heat exchanger tubes 208 can optionally be designed as a cross-twist tubes instead of single-twist tubes.

Such a cross-twist tube is schematically in the 9 and 10 shown.

In a cross-twist tube 256 the tube is provided with two swirls, the helical paths with opposite directions of rotation about the longitudinal axis 246 follow the tube.

The on the outside 240 extending linear depressions 250 and those on the inside 238 extending linear projections 248 Therefore, the mutually opposing circulating swirls intersect at regular intervals (twist distance l _p ) in 9 ,

Incidentally, a cross-twist tube is right 256 with respect to the preferred dimensions, in particular with regard to the outer diameter D, the wall thickness t, the twist depth h and the twist angle α, with the single-twist tubes described above.

The wall of the heat exchanger tubes 208 is preferably formed of a metallic material, in particular of a stainless steel material.

• – der nichtrostende Stahl mit der Werkstoffnummer 1.4301 nach DIN EN 10217-7 (Kurzname: X5CrNi18-10), mit einem reduzierten Kohlenstoffgehalt von höchstens 0,045 Gewichtsprozent;
• – der nichtrostende Stahl mit der Werkstoffnummer 1.4401 nach DIN EN 10217-7 (Kurzname: X5CrNiMol7-12-2), mit einem reduzierten Kohlenstoffgehalt von höchstens 0,045 Gewichtsprozent;
• – der nichtrostende Stahl mit der Werkstoffnummer 1.4541 nach DIN EN 10217-7 (Kurzname: X6CrNiTi18-10); und
• – der nichtrostende Stahl mit der Werkstoffnummer 1.4571 nach DIN EN 10217-7 (Kurzname: X6CrNiMoTi17-12-2).

Suitable stainless steel materials which have sufficient and durable temperature resistance are, for example

• - the stainless steel with the material number 1.4301 after DIN EN 10217-7 (Short name: X5CrNi18-10), having a reduced carbon content of at most 0.045% by weight;
• - the stainless steel with the material number 1.4401 after DIN EN 10217-7 (Short name: X5CrNiMol7-12-2), having a reduced carbon content of at most 0.045% by weight;
• - the stainless steel with the material number 1.4541 after DIN EN 10217-7 (Short name: X6CrNiTi18-10); and
• - the stainless steel with the material number 1.4571 after DIN EN 10217-7 (Short name: X6CrNiMoTi17-12-2).

The in the 1 to 10 illustrated and described above embodiment of a thermal exhaust air purification system 100 works as follows:
The raw gas, possibly with through the fresh air supply line 122 admixed fresh air, passes through the raw gas inlet 114 in the interior 226 the clean gas raw gas heat exchanger 116 and flows along the tortuous flow path 228 through the passage column 222a . 222b in cross-counterflow along the heat exchanger tubes 208 and against the flow direction 230 the clean gas to a raw gas collection chamber 258 at the burner end of the clean gas raw gas heat exchanger 116 ,

From there, the raw gas, which is in the clean gas raw gas heat exchanger 116 heated from its initial temperature to a preheating temperature of, for example, about 620 ° C, optionally mixed with fuel from the fuel line 108 , through passages of the burner 106 into the combustion chamber 102 , There, the oxidizable constituents of the raw gas and the fuel are oxidized in an exothermic reaction, whereby a clean gas with a temperature of, for example, about 750 ° C is generated, which in the direction of the longitudinal axis 192 to the burner facing away from the front side 196 the combustion chamber 102 flows.

From there, the clean gas flows through the clean gas channel 132 against the flow direction 230 back to the burner end of the clean gas raw gas heat exchanger 116 where the clean gas into the burner-side ends of the heat exchanger tubes 208 the clean gas raw gas heat exchanger 116 passes and in the interiors of the heat exchanger tubes 208 along the flow direction 230 to the burner 106 remote end of the clean gas raw gas heat exchanger 116 flows.

There passes through, cooled by the heat transfer to the raw gas to a temperature of, for example, about 320 ° C, clean gas through the burner 106 opposite ends of the heat exchanger tubes 208 in the clean gas collection chamber 234 and from there by the clean gas line 138 to the downstream heat exchangers 140 , where the clean gas, with further cooling, heat to the feed water in the first downstream heat exchanger 140a , on the cold water in the second downstream heat exchanger 140b and on the supply air in the third downstream heat exchanger 140c transfers.

Then the clean gas is through the exhaust chimney 142 delivered to the environment.

Each of the downstream heat exchangers 140 can also be a bundle of heat exchanger tubes 208 comprise, whose wall has on its inside and / or on its outside a turbulence generating structure.

In particular, the heat exchanger tubes, at least one of the downstream heat exchanger 140a to 140c as swirl tubes 244 (and as a single-twist tubes or as a cross-twist tubes 256 ) to increase the heat transfer from the clean gas to the respective secondary-side fluid medium and / or to reduce the overall length of the respective heat exchanger.

Due to the lack of additional turbulence generating components in the interior of the heat exchanger tubes 208 Even then, there is no clogging of the heat exchanger tubes 208 if solid particles are carried in the clean gas.

This is particularly advantageous if the crude gas contains silicones, by their oxidation in the combustion chamber 102 Silica particles can arise.

One in the 11 to 13 illustrated second embodiment of a thermal exhaust air purification system 100 differs from the first embodiment described above only in that the pure gas raw gas heat exchanger 116 not on the cross-countercurrent principle, but instead works on the direct countercurrent principle.

To make this possible, the holding elements form 212 in the interior 226 the clean gas raw gas heat exchanger 116 no labyrinthine deflection structure, which has a tortuous flow path 228 of the raw gas forces.

Rather, the retaining elements 212 at which the heat exchanger tubes 208 are held in this embodiment, with passage openings 260 provided that allow a fluid medium, in particular the raw gas, the holding elements 212 essentially parallel to the longitudinal axes 246 and thus parallel to the lateral surfaces of the heat exchanger tubes 208 and antiparallel to the flow direction 230 the clean gas through the heat exchanger tubes 208 flows through.

This can, as in 12 represented, for example, take place in that each retaining element 212 as an open lattice structure 262 from two groups of oblique stripes 264a and 264b is formed.

For example, the strips may be formed from a flat steel material and preferably have a width (ie, an extent in the direction of the longitudinal axes 246 the heat exchanger tubes 208 ) of, for example, 20 mm to 30 mm.

The grid structure 262 can consist of several, for example twelve, substructures 263 with trapezoidal cross-section to a ring-shaped closed holding element 212 be composed.

The holding element 212 can over bridges 265 on the outer heat exchanger housing 200 be held.

The crossing stripes 264 form diamond-shaped pictures between themselves 266 out, in each of which a heat exchanger tube 208 is included.

Because the cross-sectional area of each shot 266 is significantly larger than the cross section of the heat exchanger tube received therein 208 , remain between the outer wall of each heat exchanger tube 208 and the inner walls of the respective associated recording 266 two openings each 260 for the passage of a fluid medium through the holding grid.

At an in 13 schematically illustrated alternative embodiment of the holding elements 212 are the retaining elements 212 as in the first embodiment, as substantially annular retaining plates 214 formed, but preferably over the entire space between the heat exchanger inner housing 202 and the heat exchanger outer casing 200 extend.

For each heat exchanger tube 208 is in the holding element 212 each a substantially circular recess 268 provided, from the edge of several, for example, three or more, substantially tongue-shaped projections 270 protrude radially inward so that they extend the circumference of each through the recess 268 passing through the heat exchanger tube 208 touch and the heat exchanger tube 208 between them.

The heat exchanger tubes 208 can with the tabs 270 cohesively, for example by welding, be connected.

The radius of the recess 268 is significantly larger than the radius of the associated heat exchanger tube 208 so that between the outside 240 of the heat exchanger tube 208 and the edge of the recess 268 in each case a plurality of passage openings 260 for the passage of a fluid medium, in particular of the raw gas, through the retaining element 212 remain.

The fact that when in the 11 to 13 illustrated second embodiment of a thermal exhaust air purification system 100 the raw gas in clean gas raw gas heat exchanger 116 in direct countercurrent to the clean gas within the heat exchanger tubes 208 is guided, but still by the turbulence generating structure on the inside 238 and on the outside 240 the wall 242 the heat exchanger tubes 208 sufficient turbulence is generated in both the clean gas flow and in the raw gas flow, the efficiency of the heat transfer from the clean gas is further increased to the raw gas, so that in this embodiment, a predetermined amount of heat can be transmitted at a heat exchanger tube length, which is up to 30% shorter is than with the use of smooth tubes in the cross-countercurrent principle.

At the same length, the amount of heat transferred increases when using swirl tubes 244 as heat exchanger tubes 208 according to the direct countercurrent principle, by up to 30% compared to the use of smooth tubes in the cross-countercurrent principle.

Incidentally, the right in the 11 to 13 illustrated second embodiment of a thermal exhaust air purification system 100 in terms of structure and function with in the 1 to 10 illustrated in the first embodiment, reference is made to the above description in this regard.

An in 14 illustrated third embodiment of a thermal exhaust air purification system 100 is different from the one in the 1 to 10 illustrated first embodiment in that the clean gas raw gas heat exchanger 116 not the combustion chamber 102 surrounds but in extension of the combustion chamber 102 , in the direction of the longitudinal axis 192 the combustion chamber behind the burner 106 opposite end face 196 the combustion chamber 102 , is arranged.

The combustion chamber 102 is in this embodiment only of a substantially hollow cylindrical raw gas duct 272 surrounded, through which the preheated raw gas from the raw gas outlet 126 the clean gas raw gas heat exchanger 116 to the combustion chamber entry 104 flows.

The clean gas crude gas heat exchanger 116 is substantially the same in this embodiment as in the first embodiment, but may have a smaller inner radius, since it is not the entire combustion chamber 102 but only a substantially cylindrical bypass management 144 surrounds which the burner 106 opposite end face 196 the combustion chamber 102 with the clean gas collection chamber 234 combines.

It is preferably the burner 106 opposite end of the bypass line 144 by means of a bypass flap 146 closable.

In this third embodiment, the tube length of the clean gas raw gas heat exchanger 116 of the length of the combustion chamber 102 independently, so that this tube length can be freely selected depending on the desired heat transfer from the clean gas to the raw gas.

Incidentally, the in 14 illustrated third embodiment of a thermal exhaust air purification system 100 in terms of structure and function with in the 1 to 10 illustrated in the first embodiment, reference is made to the above description in this regard.

Furthermore, even at the in 14 illustrated third embodiment of the clean gas raw gas heat exchanger 116 be formed according to the direct countercurrent principle, as in the in the 11 to 13 illustrated second embodiment. The retaining elements described in connection with the second embodiment 212 with passages 260 for a fluid medium are also usable in the third embodiment.

An in 15 illustrated fourth embodiment of a thermal exhaust air purification system 100 is different from the one in the 1 to 10 shown first embodiment in that not the clean gas, but the raw gas to be heated through the interiors of the heat exchanger tubes 208 the clean gas raw gas heat exchanger 116 to be led.

To make this possible, the raw gas inlet opens 232 in this embodiment, in a raw gas chamber 274 on the burner 106 remote end of the clean gas raw gas heat exchanger 116 is arranged.

Into this raw gas chamber 274 they open the burner 106 opposite ends of the heat exchanger tubes 208 , so that the raw gas from the raw gas chamber 274 in the interiors of the heat exchanger tubes 208 can flow in.

After flowing through the heat exchanger tubes 208 the raw gas passes through the burner-side ends of the heat exchanger tubes 208 in the burner 106 adjacent raw gas collection chamber 258 and from there into the combustion chamber 102 where the oxidizable constituents of the raw gas are oxidized and so the clean gas is generated.

The clean gas passes, as in the first embodiment, through the clean gas duct 132 , against the flow direction within the combustion chamber 102 , back to the burner end of the clean gas raw gas heat exchanger 116 where the clean gas but now not in the interiors of the heat exchanger tubes 208 flows in, but instead in the outside of the heat exchanger tubes 208 remaining interior 226 between the heat exchanger inner housing 202 and the heat exchanger outer casing 200 , This interior 226 is the same as in the first embodiment by staggered in the radial direction holding elements 212a and 212b divided so that the clean gas a tortuous flow path 276 through the interior 226 the clean gas raw gas heat exchanger 116 is imposed.

The clean gas flows around the outside 240 the heat exchanger tubes 208 which are flowed through in the opposite direction by the raw gas, that is, in this fourth embodiment in the cross-countercurrent principle.

From the burner 106 remote end of the clean gas raw gas heat exchanger 116 the clean gas enters the clean gas collection chamber 234 and from there, via the clean gas line 138 to the downstream heat exchangers 140 ,

Incidentally, the in 15 illustrated fourth embodiment of a thermal exhaust air purification system 100 in terms of structure and function with in the 1 to 10 illustrated in the first embodiment, reference is made to the above description in this regard.

Furthermore, it is also possible in this fourth embodiment, the clean gas raw gas heat exchanger 116 form according to the direct countercurrent principle, as in the in the 11 to 13 illustrated second embodiment. The retaining elements described in connection with the second embodiment 212 with passages 260 for a fluid medium can also be used in this fourth embodiment, in which case the clean gas through the passage openings 260 in the holding elements 212 flowing.

Furthermore, it is also possible, the clean gas raw gas heat exchanger 116 in the fourth embodiment in extension of the combustion chamber 102 behind the combustion chamber 102 , especially behind the burner 106 opposite end face 196 the combustion chamber 106 to arrange, as in the in 14 illustrated third embodiment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• DIN 28178 [0027]
• DIN EN 10217-7 [0044]
• DIN EN 10217-7 [0188]
• DIN EN 10217-7 [0188]
• DIN EN 10217-7 [0188]
• DIN EN 10217-7 [0188]

Claims (15)

Heat exchanger for a thermal exhaust air purification plant ( 100 ), comprising at least one heat exchanger tube ( 208 ), whose interior is permeable by an internal fluid medium and that on its outside ( 240 ) is flowed around by an external fluid medium, characterized in that the wall ( 242 ) at least one heat exchanger tube ( 208 ) on its inside ( 238 ) and / or on its outside ( 240 ) has a turbulence generating structure. Heat exchanger according to claim 1, characterized in that the turbulence generating structure at least one structural element ( 251 ) which extends over a circumferential angle of at least 180 ° about the longitudinal axis ( 246 ) of the heat exchanger tube ( 208 ) extends around. Heat exchanger according to one of claims 1 or 2, characterized in that at least one heat exchanger tube ( 208 ) as a swirl tube ( 244 ) is formed, which preferably has a helix angle (α) of 10 ° to 40 °. Heat exchanger according to claim 3, characterized in that at least one heat exchanger tube ( 208 ) as a cross-spin tube ( 256 ) is trained. Heat exchanger according to one of claims 1 to 4, characterized in that the turbulence-generating structure has a radial extent (h) which is at least 20% of the wall thickness (t) of the heat exchanger tube ( 208 ) and / or is smaller than the wall thickness (t) of the heat exchanger tube ( 208 ). Heat exchanger according to one of claims 1 to 5, characterized in that the heat exchanger ( 116 ) a plurality of heat exchanger tubes ( 208 ) comprising a substantially hollow cylindrical heat exchanger tube bundle ( 206 ) form. Heat exchanger according to one of claims 1 to 6, characterized in that the flow path of the external fluid medium through the heat exchanger ( 116 ) is guided so that the outer fluid medium at least one heat exchanger tube ( 208 ) at least in sections transverse to the longitudinal axis ( 246 ) of the heat exchanger tube ( 208 ) flows around. Heat exchanger according to one of claims 1 to 7, characterized in that the flow path of the outer fluid medium through the heat exchanger ( 116 ) is guided so that the outer fluid medium at least one heat exchanger tube ( 208 ) at least in sections substantially parallel to the longitudinal axis ( 246 ) Heat exchanger tube ( 208 ) flows around. Heat exchanger according to claim 8, characterized in that the heat exchanger ( 116 ) at least one retaining element ( 212 ), at which at least one heat exchanger tube ( 208 ) is held, wherein the retaining element ( 212 ) at least one passage opening ( 260 ) for the passage of the outer fluid medium through the retaining element ( 212 ) having. Thermal exhaust air purification system, comprising a combustion chamber ( 102 ) and at least one heat exchanger ( 116 ) according to one of claims 1 to 9. Thermal exhaust air purification system according to claim 10, characterized in that at least one heat exchanger ( 116 ) at least in sections, the combustion chamber ( 102 ) of the thermal exhaust air purification system ( 100 ) surrounds. Thermal exhaust air purification system according to one of claims 10 or 11, characterized in that the thermal exhaust air purification system ( 100 ) a clean channel ( 132 ), through which in the combustion chamber ( 102 ) generated clean gas from a clean gas outlet ( 130 ) of the combustion chamber ( 102 ) to a clean gas entrance ( 134 ) of the heat exchanger ( 116 ), wherein the clean gas channel ( 132 ) at least in sections, the combustion chamber ( 102 ) and at least partially from the heat exchanger ( 116 ) is surrounded. Thermal exhaust air purification system according to one of claims 10 to 12, characterized in that in the combustion chamber ( 102 ) Generated clean gas the interior of a heat exchanger tube ( 208 ) can be fed. Thermal exhaust air purification system according to one of claims 10 to 13, characterized in that the thermal exhaust air purification system ( 100 ) at least one heat exchanger ( 116 ) according to one of claims 1 to 9, by means of which heat from one in the combustion chamber ( 102 ) of the thermal exhaust air purification system ( 100 ) is transferable to a fluid medium from one of the combustion chamber ( 102 ) of the thermal exhaust air purification system ( 100 ) supplied raw gas is different. Process for purifying an exhaust air stream containing oxidizable constituents by means of a thermal exhaust air purification plant ( 100 ), comprising the following method steps: - generating a clean gas stream by at least partially oxidizing the oxidizable constituents the exhaust air flow in a combustion chamber ( 102 ) of the thermal exhaust air purification system ( 100 ); and - transfer of heat from the clean gas stream to a fluid medium by means of at least one heat exchanger ( 116 ; 140 ); characterized in that at least one heat exchanger ( 116 ; 140 ) is used, which at least one heat exchanger tube ( 208 ) whose wall ( 242 ) on its inside ( 238 ) and / or on its outside ( 240 ) has a turbulence generating structure.

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