WO2011113732A1

WO2011113732A1 - Thermal exhaust air treatment plant

Info

Publication number: WO2011113732A1
Application number: PCT/EP2011/053551
Authority: WO
Inventors: Thorsten Gysin; Erhard Rieder
Original assignee: Dürr Systems GmbH
Priority date: 2010-03-15
Filing date: 2011-03-09
Publication date: 2011-09-22
Also published as: EP2547960A1; PL2547960T3; RU2554965C2; DE102010012005A1; EP2547960B1; HK1173206A1; CN102803853A; RU2012143690A; CN102803853B; DK2547960T3

Abstract

To provide a thermal exhaust air treatment plant, comprising a combustion chamber and a heat exchanger for transferring heat from a cleaned gas produced in the combustion chamber to an untreated gas to be supplied to the combustion chamber, wherein the heat exchanger comprises an inner heat exchanger chamber through which an inner fluid medium can flow and comprises an outer heat exchanger chamber through which an outer fluid medium can flow, which thermal exhaust air treatment plant permits regulation of the cleaned gas outlet temperature without a reduction in the cleaned gas quality, it is proposed that the thermal exhaust air treatment plant comprises a bypass device with a separating device by means of which a part of the outer fluid flow can be separated, as a bypass fluid flow, from an outer residual fluid flow, and with an admixing device by means of which the bypass fluid flow can be admixed to the residual fluid flow again after the residual fluid flow has passed through a section of the outer heat exchanger chamber.

Description

Thermal exhaust air purification system

The present invention relates to a thermal exhaust air purification system comprising a combustion chamber and a heat exchanger for transferring heat from a pure gas generated in the combustion chamber to a raw gas to be supplied to the combustion chamber, the heat exchanger having an inner heat exchange space permeable by an inner fluid medium and an outer heat exchange space fluid medium permeable outer heat exchanger chamber comprises.

The clean gas emerging from such a thermal exhaust air purification system is often used for further thermodynamic processes, which is why the clean gas outlet temperature must be regulated at the exit from the thermal exhaust air purification system.

To control the clean gas outlet temperature, an internal hot gas bypass valve is used according to the prior art. By opening or partially opening this flap is achieved that very hot clean gas, passed directly from the combustion chamber to the internal clean gas raw gas heat exchanger of the thermal exhaust air purification system and mixed directly to the clean gas exiting the clean gas raw gas heat exchanger exiting clean gas. The mixed stream from the hot clean gas, which originates directly from the combustion chamber, and the pure gas cooled in the clean gas raw gas heat exchanger then assumes a mixing temperature which corresponds to the desired clean gas outlet temperature.

However, such a hot gas bypass damper is arranged in thermal exhaust air purification systems in compact design due to the design of the combustion chamber and at the beginning of a reaction chamber, which is flowed through with closed bypass valve from the exhaust air from the combustion chamber. As a result, the residence time of the exhaust air to be cleaned is extended to the reaction temperature required for a complete conversion of the pollutants contained therein.

For all conversion reactions to proceed to completion, it is necessary to maintain a sufficiently long residence time, which is fixed for each thermal exhaust air purification plant, and is usually between 0.8 seconds and 1.2 seconds. In this case, the residence time of a gas molecule in the so-called reaction space is calculated as residence time, which is composed of the combustion chamber and a reaction chamber surrounding the combustion chamber. The residence time begins with the entry of the raw gas through the burner into the combustion chamber and ends with the entry of the clean gas into the clean gas raw gas heat exchanger, in which the clean gas is cooled by heat transfer to the raw gas.

Now, if a partial flow of the exhaust air is removed by the hot gas bypass valve, this partial flow no longer flows through the reaction chamber, but leaves the reaction chamber after the combustion chamber. As a result, the residence time for this partial flow of the exhaust air is shortened, and it can not run in this partial flow all the conversion reactions that are necessary for a complete pollutant destruction.

As a result, the quality of the discharged from the thermal exhaust air purification system clean gas is deteriorated.

A known remedy for this problem is to introduce a further deflection in the reaction chamber, which at least partially compensates for the shortening of the residence time for the withdrawn through the hot gas bypass valve partial flow of the exhaust air. The disadvantage of such a deflection chamber, however, is that due to its design, this reduces the residence time for the partial flow not drawn by the hot gas bypass flap. Around To compensate for this reduction in residence time, the thermal exhaust air purification system must be built longer and increased in volume, which increases the space requirement of the thermal exhaust air purification system.

The present invention has for its object to provide a thermal exhaust air purification system of the type mentioned, which allows a regulation of the clean gas outlet temperature, without reducing the clean gas quality.

This object is achieved in a thermal exhaust air purification system having the features of the preamble of claim 1 according to the invention that the thermal exhaust air purification system a bypass device with a separation device, by means of which a part of the outer fluid flow is separable as a bypass fluid flow of an outer residual fluid flow, and with an admixing device, by means of which the bypass fluid flow can be mixed again into the residual fluid flow after the residual fluid flow has passed through a section of the outer heat exchanger chamber.

The present invention is based on the concept of regulating the clean gas exit temperature of the thermal exhaust air purification system by bypassing a portion of the clean gas raw gas heat exchanger of the thermal exhaust air purification system, whereby the efficiency of the heat exchanger can be reduced in a controlled manner.

In this case, the external fluid flow may be the raw gas supplied to the heat exchanger or the clean gas supplied to the heat exchanger.

In contrast to the use of a hot gas bypass valve, the residence time of the exhaust air at the reaction temperature in the reaction space is in no case shortened by this division of the external fluid flow. The clean gas outlet temperature T _A can be regulated by means of the controllable pure gas raw gas heat exchanger according to the invention simply by varying the proportion of the bypass fluid flow to the total external fluid flow.

The greater the proportion of the bypass fluid flow in the entire outer fluid flow, the lower the efficiency of the clean gas raw gas heat exchanger, and therefore the higher is the clean gas outlet temperature at the clean gas outlet of the thermal exhaust air purification system.

In a preferred embodiment of the invention, it is provided that the admixing device, by means of which the bypass fluid flow is again immiscible into the residual fluid flow, comprises at least one admixing point which extends over at least half of the circumference of the flow path of the residual fluid flow. In this way, the most homogeneous admixture of the cold bypass fluid flow is achieved in the heated in the already passed portion of the outer heat exchanger space residual fluid flow.

It is particularly favorable if the admixing device comprises at least one admixing point which extends over at least two-thirds, in particular over at least 90%, of the circumference of the residual fluid flow.

It is particularly favorable if the admixing point extends substantially over the entire circumference of the residual fluid flow.

In a preferred embodiment of the invention it is provided that the admixing point extends annularly around the flow path of the residual fluid flow around.

By mixing the non-preheated bypass fluid flow over the entire circumference of the residual fluid flow or over a considerable part of this circumference, a very good mixing of the two partial flows is achieved. As a result, the disadvantages are avoided, which result in a only local admixture via a pipe, namely thermal imbalances and thus caused thermal stresses in the plant jacket, which have a negative effect on the life of the exhaust air purification system.

By mixing the bypass fluid flow in the residual fluid flow over a considerable part of the circumference of the residual fluid flow, a homogeneous mixing of the two partial flows also arises when the two partial flows have greatly different viscosities due to the different temperatures.

The high homogeneity of the total fluid flow mixed from the bypass fluid flow and the residual fluid flow improves the thermodynamic properties of the exhaust air purification system.

As an alternative or in addition to an admixing point which extends over at least half of the circumference of the residual fluid flow, the admixing device can also comprise a plurality of admixing points, wherein these admixing points are distributed over an admixing area which extends over at least half of the circumference of the remainder Fluid stream extends.

It is particularly favorable if the admixing region extends over at least two-thirds, preferably over at least 90%, of the circumference of the residual fluid stream.

In a preferred embodiment of the exhaust air purification system, the admixing region extends substantially over the entire circumference of the residual fluid flow. The mixture of the bypass fluid flow with the residual fluid flow preferably takes place at least partially, in particular predominantly, in a mixing space which does not contain a heat exchanger tube of the heat exchanger. This avoids that the cold bypass fluid flow directly applied to a heat exchanger tube, which could lead to high thermal stresses.

In particular, the mixing chamber can be arranged radially outside a heat exchanger tube bundle of the heat exchanger.

The bypass device may comprise a bypass channel, which the

Flow path of the residual fluid flow surrounds annular.

By means of such a bypass channel, the bypass fluid flow from the separation device to the admixing device.

The bypass channel preferably extends over part of the length of the heat exchanger, preferably over at least one third of the length of the heat exchanger, in particular over at least half the length of the heat exchanger.

In order to even out as much as possible the distribution of the bypass fluid flow through the bypass channel over the entire cross-sectional area of the bypass channel, the bypass device preferably comprises at least one

Throttling element in the flow path of the bypass fluid flow.

Such a throttle element may in particular be designed as a flow barrier with passage openings.

The bypass channel may in particular be formed substantially hollow cylindrical. A particularly good distribution of the bypass fluid flow over the passage cross section of the bypass channel is achieved if the total passage area of the passage openings in the flow barrier is 150% or less, in particular 125% or less, of an inlet cross-sectional area of the bypass device.

In order not to excessively increase the flow resistance of the throttle element, it is also advantageous if the total passage area of the passage openings in the flow barrier is 50% or more, in particular 75% or more, of an inlet cross-sectional area of the bypass device.

In a preferred embodiment of the invention it is provided that the admixing device is arranged upstream of an outlet of the outer fluid medium from the outer heat exchanger space. In this way, the mixing of the bypass fluid flow in the residual fluid flow is still within the clean gas raw gas heat exchanger, whereby it is achieved that the two partial flows are well mixed together before the outer fluid flow exits the heat exchanger (namely in the combustion chamber, if the raw gas is used as the external fluid, or in a clean gas passage when the clean gas is used as the external fluid).

In order to control or regulate the clean gas outlet temperature of the thermal exhaust air purification system in a simple manner, it is advantageous if the separating device has a bypass flap for controlling the entry of the bypass fluid flow into the bypass device and a heat exchanger flap for controlling the entry of the residual fluid flow in the Includes heat exchanger.

In this case, the bypass flap and the heat exchanger flap are preferably coupled to one another mechanically and / or by control technology (that is to say by coordinated activation by means of a control device of the thermal exhaust air purification system). This coupling is achieved, for example, by an adaptive flap mechanism.

The coupling of the two flaps is preferably carried out so that an opening movement of the bypass flap, through which the inlet cross section of the bypass device is increased, takes place simultaneously with a closing movement of the heat exchanger flap, through which the inlet cross section is reduced in the heat exchanger, and vice versa.

Due to the coupling of the bypass flap and the heat exchanger flap, the division of the entire outer fluid flow onto the bypass fluid flow and the residual fluid flow can preferably be carried out substantially continuously, whereby the efficiency of the heat exchanger and thus the clean gas discharge temperature can be controlled in a simple manner ,

The separation device is preferably arranged upstream of an inlet of the residual fluid flow in the outer heat exchanger space. As a result, the outer fluid flow is divided into the bypass fluid flow and the residual fluid flow before the residual fluid flow enters the heat exchanger and is heated or cooled therein. In a particular embodiment of the thermal exhaust air purification system according to the invention it is provided that the outer heat exchanger space can be flowed through by the raw gas zuzuführendem the combustion chamber. In this case, the raw gas is used as the external fluid.

Alternatively, it can also be provided that the outer heat exchanger space can be flowed through by clean gas generated in the combustion chamber. In this case, the clean gas is used as the external fluid.

The present invention further relates to a method for purifying a crude gas stream containing oxidizable constituents by means of a thermal exhaust air purification system, which comprises the following method steps: Supplying the raw gas stream to a combustion chamber;

Generating a clean gas stream by at least partially oxidizing the oxidizable constituents of the raw gas stream in the combustion chamber;

Transferring heat from the clean gas stream to the crude gas stream by means of a heat exchanger, wherein the heat exchanger comprises an inner heat exchanger chamber through which an inner fluid medium flows and an outer heat exchanger chamber through which an external fluid medium flows.

The present invention is based on the further object of providing a method of the type mentioned above, which allows a control of the pure gas outlet temperature without impairing the quality of the clean gas.

This object is achieved by a method having the features of the preamble of claim 15, which comprises the following further method steps:

Separating a portion of the outer fluid flow as a bypass fluid flow from an outer residual fluid flow by means of a separation device; and

Mixing the bypass fluid stream into the residual fluid stream by means of an admixing device after the residual fluid stream has passed through a portion of the outer heat exchanger space.

The inventive thermal exhaust air purification system is preferably designed as a recuperative exhaust air purification system with a recuperative clean gas Rohgas- heat exchanger. Since the clean gas outlet temperature can be increased if necessary by the controllable heat exchanger used in the thermal exhaust air cleaning system according to the invention when using the bypass device, it is useful, the operating point of the thermal exhaust air purification system not to the target outlet temperature of the clean gas, but to a slightly lower temperature, preferably to a lower by at least 10 ° C lower temperature, in particular to a lower by about 20 ° C temperature to interpret.

During operation of the thermal exhaust air cleaning system, a ^¬ can then be controlled by controlling the heat exchanger by means of the bypass flap and the heat exchanger cover the actually required clean gas outlet temperature T _A.

In phases of smaller heat loss through the thermal exhaust air purification system downstream heat exchanger, for example, in production breaks, can then be controlled to the lowest possible clean gas outlet temperature of the operating point to save energy.

In all control positions of the heat exchanger, the full residence time of the exhaust air is retained in the reaction space.

In the thermal exhaust air purification system according to the invention, the clean gas outlet temperature can be regulated without the use of a hot gas bypass flap.

Therefore, even such a hot gas bypass valve, through which hot clean gas from the combustion chamber passes directly to the clean gas outlet of the exhaust air purification system, omitted. In order to further increase the clean gas outlet temperature of the thermal exhaust air purification system, if necessary, but also a thermal exhaust air cleaning system according to the invention may be provided with such a hot gas bypass door in addition to the bypass device.

The residence time of the exhaust air to be cleaned in the combustion chamber and a reaction chamber following the combustion chamber or a clean gas channel following the combustion chamber always remains the same regardless of the control setting of the bypass device.

The primary energy demand of the thermal exhaust air purification system during break time is significantly reduced.

In particular, the concentric arrangement of the bypass device around the heat exchanger and the equalization of the bypass fluid flow through the bypass device by means of the throttle elements, a uniform mixing of the bypass fluid flow is achieved to the residual fluid flow in the heat exchanger.

As a result, the best possible efficiency of the heat exchanger and a uniform temperature distribution in the thermal exhaust air cleaning system is achieved, which is particularly important for increasing the life of the exhaust air purification system.

If the raw gas forms the outer fluid flow, which is divided into the bypass fluid flow and the residual fluid flow, these two partial streams are homogeneously mixed with each other before the entry of the raw gas into the burner, whereby a stable cleaning performance of the exhaust air purification system is achieved.

The uniform admixture of the bypass fluid flow over a considerable proportion of the circumference, preferably over the entire circumference, of the residual Fluid flow reduces the thermal stresses caused by temperature gradients to a minimum.

If the thermal exhaust air purification system is designed so that the design temperature at the operating point of the thermal exhaust air purification system is lower than the target outlet temperature of the clean gas, by means of the variable heat exchanger, the actual clean gas outlet temperature during operation of the thermal exhaust air purification system both to a temperature above the target outlet temperature as well as adjusted to a temperature below the target outlet temperature.

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 is a schematic block diagram of a thermal exhaust air purification system with a controllable clean gas Rohgas-Wärmetau- shear, in which a bypass fluid stream of the raw gas before entering the heat exchanger of a residual fluid stream of the raw gas is separated and the bypass fluid stream the rest - Fluid flow is reusable before exiting the heat exchanger;

2 shows a schematic longitudinal section through a combustion chamber, a clean gas raw gas heat exchanger surrounding the combustion chamber and a bypass device with separation device and admixing device of the thermal exhaust air purification system from FIG. 1; a schematic longitudinal section through a second embodiment of a combustion chamber, surrounding the combustion chamber clean gas raw gas heat exchanger and a bypass device with separation device and admixing device; an enlarged view of the area I of FIG. 3; an enlarged view of the area II of Fig. 3; a schematic plan view from above of the thermal exhaust air purification system of Figure 3 in the region of a raw gas inlet into the heat exchanger and a Rohgaseintritts in the bypass device, with the viewing direction in the direction of arrow 6 in Fig. 3. a schematic cross section through the thermal exhaust air purification system of Figure 3, taken along the line 7-7 in Fig. 3. a schematic representation of a multilayer heat exchanger tube bundle of pure gas raw gas heat exchanger of the thermal exhaust air purification system of Fig. 3; a schematic cross section through the thermal exhaust air purification system of FIG. 3, taken along the line 9-9 in Fig. 3; a schematic view of an annular throttle element in the bypass device of the thermal exhaust air purification system of FIG. 3; a schematic plan view from above of a separation device of the bypass device of the thermal exhaust air purification system of Fig. 3; Fig. 12 is a schematic front view of the separating device

Fig. 11, with the viewing direction in the direction of the arrow 12 in Fig. 11;

Fig. 13 is a schematic plan view of a drive device of

Separating device of FIGS. 11 and 12;

Fig. 14 is a schematic side view of the drive device for the

Separating device, with the viewing direction in the direction of arrow 14 in FIG. 13; and

Fig. 15 is a schematic block diagram of a third embodiment of a thermal exhaust air purification system with a controllable clean gas raw gas heat exchanger, wherein a bypass fluid stream of the clean gas from a residual fluid stream of the clean gas before the entry of pure gas in the clean gas raw gas heat exchanger can be separated and the Bypass fluid flow of the clean gas to the residual fluid flow of the clean gas before emerging from the clean gas raw gas heat exchanger is again mixed.

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

One in FIGS. 1 and 2, designated as a whole by 100 thermal exhaust air purification system includes, as can be seen from the schematic diagram of Fig. 1, a combustion chamber 102, at the combustion chamber inlet a burner 104 is disposed, via a fuel line 106 with a fuel valve 108 a suitable fuel, such as natural gas, and via a cooling air line 110 with a cooling air valve 112 cooling air for an ignition electrode, a sight glass and flame monitoring can be fed. 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 oxidized in the combustion chamber 102, together with the added fuel, and thus made harmless.

The gas mixture supplied to the combustion chamber 102, which contains the combustible components, is referred to below as raw gas.

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

The raw gas comes from a in Fig. 1 purely schematically illustrated and denoted by 114 raw gas source.

The raw gas volume flow supplied from the raw gas source 114 to the thermal exhaust air purification system 100 is preferably at least

1,000 Nm ³ / h (l Nm ³ = 1 standard cubic meter), in particular at least

10,000 Nm ³ / h.

The raw gas from the raw gas source 114 is supplied to a raw gas inlet 116 of the thermal exhaust air purification system 100 via a Rohgaszuführleitung 118, in which a Rohgasgebläse 120 is arranged, which promotes the raw gas from the Rohgasquelle 114 to the combustion chamber 102.

Furthermore, the Rohgaszuführleitung 118 may be provided with a differential pressure gauge 122, by means of which the differential pressure Δρ between the pressure side and the suction side of the Rohgasgebläses 120 can be determined.

Downstream of the raw gas inlet 116 into the thermal exhaust air purification system 100 is a separation device 124 of a bypass device 126 arranged, by means of which a part of the crude gas stream as a bypass fluid stream of a residual fluid stream of the raw gas can be separated and fed through a bypass inlet opening 128 a bypass channel 130 of the bypass device 126.

The residual fluid flow enters through a raw gas inlet 132 into the secondary side of a recuperative clean gas raw gas heat exchanger 134, which is flowed through on the primary side by the clean gas escaping from the combustion chamber.

The pure gas raw gas heat exchanger 134 comprises, as will be explained in more detail later, a heat exchanger tube bundle 136 of a plurality of heat exchanger tubes 138, the interiors together form a permeable by the clean gas inner heat exchanger chamber 140, while limited by a heat exchanger housing 142 outside the Heat exchanger tubes 138 forms a flowing through of the raw gas outer heat exchanger chamber 144.

Since the raw gas in this embodiment of a thermal exhaust air purification system 100 flows through the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134, the raw gas is used in this embodiment as an outer fluid medium.

The clean gas, which in this embodiment of a thermal exhaust air purification system 100 flows through the inner heat exchanger chamber 140 of the clean gas raw gas heat exchanger 134, serves in this embodiment as an inner fluid medium.

An admixing device 148 of the bypass device 126, by means of which the bypass fluid flow of the raw gas can be mixed again into the residual fluid flow of the raw gas, is arranged at a point located between the raw gas inlet 132 and a crude gas outlet 146 of the clean gas raw gas heat exchanger 134 the residual fluid flow of the raw gas between the separating device 124 and the admixing 148 lying portion 150 of the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134 has passed.

The admixing device 148 is designed such that the mixing of the bypass fluid flow into the residual fluid flow takes place over a considerable part of the circumference of the residual fluid flow, preferably over the entire circumference of the residual fluid flow, whereby a very good mixing of the two Partial flows (bypass fluid flow and residual fluid flow) to a combined total raw gas flow still within the clean gas raw gas heat exchanger 134 takes place.

Upon reaching the admixing device 148, the residual fluid flow has a higher temperature than the bypass fluid flow, since the residual fluid flow in the section 150 of the outer heat exchanger chamber 144 has already been heated by heat transfer from the clean gas flowing through the inner heat exchanger chamber 140.

By the uniform admixture by means of the admixing device 148, however, it is achieved that from the bypass fluid stream and the residual fluid stream of the raw gas, a combined total raw gas stream is formed, which has a substantially homogeneous temperature distribution, so that the boundary walls of the downstream of the admixing 148th lying and up to the raw gas outlet 146 extending end portion 152 of the outer heat exchanger chamber 144 are all acted upon by raw gas without large temperature gradient.

In Fig. 1, the pure gas raw gas heat exchanger 134 is shown purely schematically as if the outer heat exchanger space 144 is embedded in the inner heat exchanger space 140; However, this type of presentation was chosen only because so the bypass device 126 easier let represent. In fact, the inner heat exchanger space 140 is embedded in the same surrounding outer heat exchanger space 144.

The raw gas outlet 146 of the clean gas raw gas heat exchanger 134 is connected to a raw gas inlet 154 of the burner 104, through which the raw gas enters the combustion chamber 102.

The thermal exhaust air purification system 100 may be provided with a differential pressure gauge 156, by means of which the differential pressure Δρ between the combustion chamber 102 on the one hand and the Rohgasaustritt 146 from the pure gas raw gas heat exchanger 134 or the Rohgaseintritt 154 in the burner 104 on the other hand can be determined.

To a clean gas outlet 158 of the combustion chamber 102, a clean gas inlet 160 of the clean gas raw gas heat exchanger 134 is connected, via which the clean gas which has been produced in the combustion chamber 102 enters the inner heat exchanger space 140 of the clean gas raw gas heat exchanger 134.

To a clean gas outlet 162 of the clean gas raw gas heat exchanger 134, a clean gas line 164 is connected, which leads up to a (not shown) exhaust stack through which the clean gas is discharged into the environment.

The clean gas line 164 can be guided by one or more downstream heat exchangers, which are flowed through by the clean gas on the primary side.

Such downstream of the clean gas raw gas heat exchanger 134 further heat exchangers can be used to heat a fluid medium or to generate a vapor from a liquid medium. In particular, such downstream heat exchangers can be used for steam generation, thermal oil heating, hot water or hot water production or for circulating air or fresh air heating.

The thermal exhaust air purification system 100 may include a differential pressure gauge 166, by means of which a pressure difference Δρ between the clean gas line 164 and the Rohgaseintritt 116 can be determined in the thermal exhaust air purification system 100.

From a reaction chamber or a clean gas duct 168, which the clean gas inlet 160 of the clean gas raw gas heat exchanger 134 with the

A clean gas outlet 158 of the combustion chamber 102 connects, a bypass line 170 can branch off, which opens downstream of the clean gas outlet 162 of the clean gas raw gas heat exchanger 134 in the clean gas line 164.

By means of this hot-side bypass line 170, at least part of the clean gas from the combustion chamber 102 can be fed directly to the exhaust gas chimney or the downstream heat exchangers, bypassing the clean gas raw gas heat exchanger 134, in particular if the heat requirement at one of the downstream heat exchangers is particularly high.

The bypass flow through the hot-side bypass line 170 can be controlled or regulated by means of a bypass flap 172 arranged in the bypass line 170.

The combustion chamber 102 and the clean gas raw gas heat exchanger 134 associated therewith of the thermal exhaust air purification system 100 with the bypass device 126 from FIG. 1 are shown in detail in FIG. 2.

From Fig. 2 it can be seen that the combustion chamber 102 is formed substantially cylindrical, along a central longitudinal axis 174 from a burner-side end face 176 facing away from the burner 104 a End face 178 extends and is bounded by a hollow cylindrical combustion chamber wall 180.

The combustion chamber 104 is surrounded by the in this embodiment substantially hollow cylindrical clean gas raw gas heat exchanger 134, which on its combustion chamber 104 facing away from the radial outer side by a cylindrical outer heat exchanger housing 182 and at its combustion chamber 102 facing radially inside by a likewise in Substantially cylindrical heat exchanger inner housing 184 is limited.

The heat exchanger outer housing 182 and the heat exchanger inner housing 184 together form the heat exchanger housing 142, which limits the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134.

The heat exchanger inner housing 184 is supported on the combustion chamber wall 180 via support rings 186.

By the intermediate space between the combustion chamber wall 180 and the heat exchanger inner housing 184 of the clean gas duct 168 is formed, which connects the burner facing away from the end face 178 of the combustion chamber 102 with the adjacent to the burner side end face 176 of the combustion chamber 102 clean gas inlet 160 of the clean gas raw gas heat exchanger 134 connects ,

In the space between the heat exchanger inner housing 184 and the heat exchanger outer housing 182, the heat exchanger tube bundle 136 of the plurality of heat exchanger tubes 138 is arranged.

The heat exchanger tubes 138 all extend substantially parallel to the longitudinal axis 174 and form one or more, for example two, cylindrical heat exchanger tube layers 188, in which the heat exchanger tubes 138 each with the same radial distance from the longitudinal axis 174 and along the circumference are arranged substantially equidistantly distributed.

Each heat exchanger tube 138 is held on a plurality of, in the direction of the longitudinal axis 174 successive and preferably substantially equidistant from each other arranged holding elements 190 which are formed, for example, as a substantially annular retaining plates 192.

The heat exchanger tubes 138 penetrate passage openings in the holding elements and lie with their outer sides 194 in a fluid-tight manner on the holding elements 190, so that substantially no fluid can pass through the holding elements 190 in the regions lying outside of the heat exchanger tubes 138.

At its two ends, the heat exchanger tubes 138 are integrally connected to one of the holding elements 190, for example, welded.

In the direction of the longitudinal axis 174, inner holding elements 190a with a smaller inner radius and a smaller outer radius and outer holding elements 190b with a larger outer radius and a larger inner radius than the inner holding elements 190a follow one another alternately.

The inner support members 190a have an inner radius substantially equal to the radius of the outer side of the peripheral wall of the heat exchanger inner housing 184 so that substantially no fluid can pass between the radially inner edge of the inner support members 190a and the heat exchanger inner housing 184.

The inner support members 190 a are based on sliding shoes 196 on the heat exchanger inner housing 183, but are not fixed to the

Heat exchanger inner housing 184 connected so that the inner Holding members 190a to compensate for different thermal strains due to temperature gradients or due to differences in the thermal expansion coefficients relative to the heat exchanger inner housing 184 in the direction of the longitudinal axis 174 can move.

The outer radius of the inner support members 190a is only slightly larger than the outer radius of the heat exchanger tube bundle 136, so that between the outer edge 198 of the inner support members 190a on the one hand and the inside of the heat exchanger outer housing 182 on the other hand, an outer passage gap 200a remains, through which a fluid can happen.

The outer radius of the outer retaining elements 190b substantially corresponds to the radius of the inner side of the peripheral wall of the heat exchanger outer housing 182, so that the outer retaining elements 190b bear with their outer edge on the inside of the heat exchanger outer housing 182 and substantially no fluid between the outer retaining elements 190b and the heat exchanger outer housing 182 can pass.

The inner radius of the outer support members 190a is only slightly smaller than the inner radius of the heat exchanger tube bundle 136, so that between the inner edge 202 of the outer support members 190b and the heat exchanger inner housing 184, an inner passage gap 200b remains, through which a fluid can pass.

Thus, the inner support members 190a and the outer support members 190b, which are offset from each other in the radial direction of the longitudinal axis 174, a mechanical deflection and a labyrinth-shaped subdivision of the outer heat exchanger chamber 144 of the clean gas Rohgas heat exchanger 134, so that in the outer heat exchanger space 144, a tortuous flow path for a fluid medium is formed. This outer heat exchanger space 144 of the clean gas raw gas heat exchanger 134 is flowed through by the same in the operation of the preheated raw gas, which serves as an outer fluid medium in this embodiment.

Since the raw gas is forced by the holding members 190, a tortuous flow path, the raw gas flows around the heat exchanger tubes 138, in which the serving as an inner fluid medium clean gas flows, mostly transverse to the longitudinal direction of the heat exchanger tubes 138th

Since, furthermore, the mean flow direction of the clean gas in the heat exchanger tubes 138 is directed from the burner-side end face 176 to the end face 178 facing away from the burner, and the mean flow direction of the raw gas along the flow path in the outer heat exchanger chamber 144 is substantially antiparallel to the flow direction 204 of the clean gas through the heat exchanger tubes 138, the clean gas raw gas heat exchanger 134 operates in this embodiment substantially according to the cross-countercurrent principle.

The entry of the raw gas into the clean gas raw gas heat exchanger 134 via the radially projecting from the heat exchanger outer housing 182 separating device 124 of the bypass device 126, which at the burner 104 remote from the end of the clean gas raw gas heat exchanger 134 and preferably at the upper tip is arranged.

The separating device 124 comprises an inlet shaft 206, which is connected upstream to the Rohgaszuführleitung 118, downstream of the raw gas inlet 132 into the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134 opens and by means of a heat exchanger flap 208 is completely or partially closed.

Furthermore, the separation device 124 comprises a bypass shaft 210, which is also connected to the raw gas supply line 118 upstream, downstream flows into the bypass channel 130 of the bypass device 126 and by means of a bypass flap 212 is completely or partially closed.

The bypass flap 212 in the bypass shaft 210 and the heat exchanger flap 208 in the inlet shaft 206 of the clean gas raw gas heat exchanger 134 are mechanically and / or control technology (ie by means of coordinated control of the flaps by a control device of the thermal exhaust air cleaning system 100) coupled to each other such that they always be opened or closed in opposite directions.

Thus, when the bypass door 212 is brought into a position in which it releases a larger inlet cross section for the passage of the raw gas through the bypass shaft 210, by a coupled with the movement of the bypass flap 212 movement of the heat exchanger flap 208, the heat exchanger flap 208 simultaneously in a position brought in which it reduces the inlet cross section for the passage of the raw gas through the entrance shaft 206, and vice versa.

By the coupled operation of the bypass flap 212 and the heat exchanger flap 208 thus coming from the raw gas source 114 raw gas stream can be divided in any desired ratio in a bypass flap 212 passing bypass fluid flow and the heat exchanger flap 208 passing residual fluid flow.

Preferably, the volume fraction of the bypass fluid flow (measured in standard cubic meters) in the total supplied raw gas stream, in particular substantially continuously, at least in a range of about 20% to 80% controlled or regulated.

The bypass channel 130 is formed in this embodiment of a thermal exhaust air purification system 100 is substantially hollow cylindrical and surrounds a portion of the clean gas raw gas heat exchanger 134 annular. The bypass channel 130 is bounded on its radial inner side facing the clean gas raw gas heat exchanger 134 by the outer heat exchanger housing 182 and on its radial outer side facing away from the clean gas raw gas heat exchanger 134 by a cylindrical bypass outer housing 214.

The bypass channel 130 extends along the longitudinal axis 174 of the bypass shaft 210, where the bypass fluid flow into the bypass channel 130, over a portion of the length of the clean gas raw gas heat exchanger 134, preferably over at least one third of the length of the clean gas raw gas Heat exchanger 134, to the admixing device 148 of the bypass device 126, in which the bypass fluid flow is remixed to the residual fluid flow in the outer heat exchanger chamber 144.

The admixing device 148 comprises a bypass duct end wall 216, which closes off the hollow cylindrical bypass duct 130 at the end, and an annular passage gap 218 in the heat exchanger outer housing 182, through which the bypass fluid flow from the hollow cylindrical bypass duct 130 into the also hollow cylindrical outer heat exchanger chamber 144 of the clean gas Crude gas heat exchanger 134 may occur.

The passage gap 218 thus forms an admixing point 220 which extends over the entire circumference of the outer heat exchanger space 144 and thus over the entire circumference of the flow path of the residual fluid flow flowing through the outer heat exchanger space 144.

In order to even out as much as possible the distribution of the bypass fluid flow through the bypass channel 130, which only enters the bypass channel 130 at the top of the bypass channel 130 through the bypass shaft 210 over the entire circumference of the hollow cylindrical bypass channel 130, are in the Bypass passage 130 between the separating device 124 and the Zumischvor- direction 148 one or more throttle elements 222 are provided, each as a flow barrier with along the circumference of the throttle element 222, preferably substantially equidistantly, distributed passage openings 224 for the passage of the bypass fluid flow through the throttle element 222 are formed.

In this case, the total passage area of the passage openings 224 in such a flow barrier is preferably 150% or less of the maximum inlet cross-sectional area, which the bypass flap 212 in the

Bypass shaft 210 releases.

In particular, it can be provided that the entire passage area of the passage openings 224 in such a flow barrier is 125% or less, for example approximately 100%, of the maximum inlet cross-sectional area which the bypass flap 212 releases in the bypass shaft 210.

Furthermore, the total passage area of the passage openings 224 in such a flow barrier is preferably at least approximately 50%, in particular at least approximately 75%, of the maximum inlet cross-sectional area which the bypass flap 212 releases in the bypass shaft 210.

The throttle elements 222 may in particular be formed as a throttle plate with through openings 224, which may be integrally formed with one of the outer holding elements 190 b in the form of a holding plate 192.

The exit of the recombined from the bypass fluid flow and the residual fluid flow total fluid flow of the raw gas from the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134 takes place at the burner-side end of the clean gas raw gas heat exchanger 134 in a raw gas collecting space 226, which is in fluid communication with the Rohgaseintritt 132 of the burner 104.

The outlet of the clean gas from the inner heat exchanger chamber 140 of the clean gas raw gas heat exchanger 134 takes place in a clean gas collection chamber 228 at the end facing away from the burner 104 of the clean gas raw gas heat exchanger 134, in which open the downstream gas ends of the heat exchanger tubes 138.

At the clean gas collecting chamber 228, the clean gas line 164 begins, through which the clean gas flows to the optionally downstream heat exchangers and finally to the exhaust chimney.

The additional hot-side bypass line 170, through which the clean gas can be conducted past the primary side of the clean gas raw gas heat exchanger 134, is formed in this embodiment by a so-called compensator 230 which, for example, has the shape of a hollow cylinder and, on the one hand, the burner 104 opposite end of the combustion chamber 102 and on the other hand with the clean gas collecting chamber 228 is in fluid communication.

Further, the compensator 230, for example, at its Sammelkammersei- term end, provided with the bypass valve 172, which makes it possible to adjust the proportion of clean gas flow from the combustion chamber 102, which enters directly from the combustion chamber 102 in the clean gas collecting chamber 228, without previously to pass the clean gas raw gas heat exchanger 134.

In order to increase the efficiency of the heat transfer from the clean gas to the raw gas into the clean gas raw gas heat exchanger 134, the heat exchanger tubes 138 may be provided on the inside and on the outside of its wall with a turbulence generating surface structure. In particular, it may be provided that the heat exchanger tubes 138 are formed as swirl tubes.

Such swirl tubes are described for example in DIN 28178 (in the version of May 2009).

The heat exchanger tubes 138 may also be designed as smooth tubes.

The embodiment of a thermal exhaust air purification system 100 shown in FIGS. 1 and 2 and described above functions as follows:

The raw gas from the raw gas source 114 passes to the separating device 124 of the bypass device 126 and is there in the bypass fluid flow, which enters the bypass channel 130, and in the residual fluid flow, which directly into the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134 occurs, split.

The volume fraction of the bypass fluid flow and the residual fluid flow on the total raw gas flow depends on the respectively set position of the bypass flap 212 and the heat exchanger flap 208.

The larger the proportion of the bypass fluid flow, the lower the efficiency of the clean gas raw gas heat exchanger 134, and the higher the exit temperature T _A , at which the clean gas exits the clean gas Rohgas- heat exchanger 134.

The outlet temperature of the clean gas can thus be adjusted by means of the controllable clean gas raw gas heat exchanger 134 depending on the desired at the downstream heat exchangers clean gas temperature. A further increase in the outlet temperature of the clean gas can be achieved if the bypass flap 172 in the hot-side bypass line 170 is opened, so that clean gas can pass from the combustion chamber 102 directly into the clean gas line 164. By using the hot-side bypass line 170, however, the reaction time available for the oxidation of the combustible constituents of the raw gas is shortened because the clean gas entering the bypass line 170 does not pass through the clean gas duct 168.

The bypass fluid flow is very uniformly returned to the residual fluid flow by the admixing device 148, because the bypass channel 130 is designed as a hollow cylinder, which is arranged concentrically around the clean gas raw gas heat exchanger 134, and because the admixing point 220 extends over the entire circumference of the outer heat exchanger chamber 144 at the admixing point 201.

Furthermore, the throttle elements 222 arranged in the bypass channel 130 act as damper stages, which uniform the distribution of the bypass fluid flow over the circumference of the bypass channel 130.

The recombined from the bypass fluid flow and the residual fluid flow total fluid flow of the raw gas flows along the tortuous flow path through the passage gaps 200a, 200b in cross-counterflow along the heat exchanger tubes 138 and against the flow direction 204 of the clean gas to the raw gas collection chamber 226 on burner end of the pure gas raw gas heat exchanger 134th

From there, the raw gas, which has been heated in the clean gas raw gas heat exchanger 134 from its initial temperature to a preheating temperature of, for example, about 620 ° C, optionally mixed with fuel from the fuel line 106, passes through the raw gas inlet 154 in the Burner 104 and from there 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 having a temperature of, for example, about 750 ° C is generated, which faces away from the burner end face 178 of the combustion chamber 102 flows through the clean gas duct 168 against the flow direction 204 back to the burner end of the clean gas raw gas heat exchanger 134 where the clean gas enters the burner side ends of the heat exchanger tubes 138 of the clean gas raw gas heat exchanger 134 and in which through the interiors the heat exchanger tubes 138 formed inner heat exchanger chamber 140 along the flow direction 204 to the burner 104 remote from the end of the clean gas raw gas heat exchanger 134 flows.

Since in all control positions of the clean gas raw gas heat exchanger 134, the entire clean gas flows through the clean gas duct 168, the full dwell time of the exhaust air in the range from the combustion chamber 102 to the entry into the clean gas raw gas heat exchanger 134 remains in all these control positions without the exhaust air is cooled down here. As a result, a complete oxidation of the oxidizable constituents of the raw gas is achieved.

From the inner heat exchanger chamber 140 of the clean gas raw gas heat exchanger 134 passes through the heat transfer to the raw gas to a, depending on the control position of the clean gas raw gas heat exchanger 134, outlet temperature T _A cooled clean gas into the clean gas plenum 228 and from there the clean gas line 164 to the optionally downstream heat exchangers, where the clean gas, with further cooling, transfers heat to one or more other fluid media.

Subsequently, the clean gas is discharged through the exhaust chimney to the environment. The thermal exhaust air purification system 100 is structurally designed for a specific operating point with a certain clean gas outlet temperature T _A.

Since a thermal exhaust air purification system 100 is essentially a rigid, all-steel structure, this predetermination (at an input temperature of the raw gas specified by the raw gas source 114) essentially determines the height of the outlet temperature.

Since the outlet temperature of the clean gas can be increased as required by the bypass device 126 which is controllable in the manner described above, but can not be lowered, it makes sense to use the bypass device 126, the operating point of the thermal exhaust air purification system 100 not to the target outlet temperature of the clean gas, but to a slightly lower temperature, preferably to a lower by at least 10 ° C temperature, in particular to a lower by about 20 ° C temperature interpreted.

During operation of the thermal exhaust air purification system 100, the actually required clean gas outlet temperature T _A can then be adjusted by regulating the clean gas raw gas heat exchanger 134 by means of the bypass flap 212 and the heat exchanger flap 208.

In phases of smaller heat loss through the downstream heat exchangers, for example in production breaks, can then be controlled to the lowest possible clean gas outlet temperature of the operating point to save energy.

One in FIGS. 3 to 14 illustrated second embodiment of a thermal exhaust air purification system 100 agrees with respect to their basic structure and its operation with the first embodiment shown in FIGS. 1 and 2. In particular, the principal block diagram of FIG. 1 to the second embodiment of a thermal exhaust air purification system 100 too.

A difference of the second embodiment from the first embodiment is that in the second embodiment, the portion 150 between the raw gas inlet 132 at which the residual fluid flow enters the outer heat exchanger space 144 of the clean gas raw gas heat exchanger 134 and the admixing device 148 of the outer heat exchanger space 144 is longer than that between the admixing device 148 and the Rohgasaustritt 146, where the reunited total fluid flow of the raw gas exiting the outer heat exchanger chamber 144, lying end portion 152 of the outer heat exchanger chamber 144th

Thus, in the second embodiment, the bypass fluid flow is admixed only when the residual fluid flow already has a higher temperature than in the first embodiment.

The possible reduction in the efficiency of the clean gas raw gas heat exchanger 134 (and thus the accessible control range for the clean gas outlet temperature T _A ) is thus greater in the second embodiment than in the first embodiment.

In addition, the extension of the admixing point 220 of the admixing device 148 in the direction of the longitudinal axis 174 in the second embodiment is greater than in the first embodiment.

In particular, in the second embodiment, the extent of the passage gap 218 forming the admixing point 220 in the direction of the longitudinal axis 174 is greater than the average distance between two holding elements 190 of the clean gas-raw gas heat exchanger 134 which succeed one another in the direction of the longitudinal axis 174. The bypass passage end wall 216 in the second embodiment is not substantially circular-cone-shaped, as in the first embodiment, but is substantially annular.

In order to increase the mechanical stability of the bypass passage end wall 216 and the adjacent area of the bypass outer housing 214, reinforcing elements 232 are provided in the second embodiment, for example in the form of approximately triangular gussets which extend along the circumference of the bypass passage end wall 216, preferably substantially equidistant. are distributed and cohesively connected to both the bypass channel end wall 216 and the bypass outer housing 214.

Further, in the second embodiment, the edge 234 of the heat exchanger outer housing 182 facing the bypass duct end wall 216, which delimits the admixing point 220 on the upstream side, is provided with an annular fold 236 in order to stiffen the edge 234.

Due to the large extent of the admixing point 220 in the flow direction of the raw gas through the outer heat exchanger space 144, it is achieved that the mixture of the bypass fluid flow with the residual fluid flow predominantly lies in a region located radially outside the heat exchanger tube bundle 136

Mixing chamber 238 takes place.

This avoids that the cold bypass fluid flow acts directly on the heat exchanger tubes 138 in the region of the admixing point 220, which could lead to high thermal stresses, because the regions of the heat exchanger tubes 138 located downstream and upstream of the region of the admixing point 220 are in contact with raw gas of higher temperature. Due to the displacement of the mixing space 238 into the region lying outside of the heat exchanger tube bundle 136, however, the mixture of the bypass fluid flow and the residual fluid flow generated by the admixture only reaches the heat exchanger tubes 138, which has a higher temperature than the cold bypass. Fluid flow alone.

In order to shift the mixing process into the region outside of the heat exchanger tube bundle 136, it is further added that in the region of the admixing point 220 of the admixing device 148, an inner holding element 190a of the clean gas raw gas heat exchanger 134 and no outer holding element 190b is arranged, so that the Residual fluid flow is forced to pass on the radially outer side of the holding member 190 a.

The Fig. FIGS. 4 to 14 show details of the second embodiment of a thermal exhaust air purification apparatus 100 which are the same in the first embodiment or may be the same, but are not so clear from the single sectional view (FIG. 2) of the first embodiment.

Thus, FIG. 4 shows a vertical section through the radially inner region of an inner retaining element 190a with a sliding shoe 196 fastened thereto, which can slide on an outer side of the heat exchanger inner housing 184 in the direction of the longitudinal axis 174.

5 shows a vertical section through the burner-side ends of two heat exchanger tubes 138, which are materially connected, in particular welded, to a holding element 190 of the clean gas raw gas heat exchanger 134. FIG. 6 shows a top view from above of the end region of the thermal exhaust air purification system 100 facing away from the burner 104, from which in particular the separating device 124 with the bypass shaft 210 and the adjacent inlet shaft 206 can be clearly seen.

The cross section of the inlet shaft 206 through which the raw gas can flow is preferably larger than the cross section of the bypass shaft 210 through which the raw gas can flow.

FIG. 7 shows a vertical cross section through the thermal exhaust air cleaning system 100 in the region of the admixing point 220 of the admixing device 148.

From Fig. 7 and from FIG. 8, which shows a cross-section only through the heat exchanger tube bundle 136, it can be seen that in the second embodiment, the heat exchanger tube bundle 136 includes three heat exchanger tube layers 188, wherein the heat exchanger tubes 138 of different heat exchanger tube layers 188 have different radial distances from the longitudinal axis 174 ,

9 shows a vertical cross section through the thermal exhaust air purification system 100 in a region in which the bypass channel 130 of the bypass device 126 concentrically surrounds the section 150 of the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134.

From Fig. 9 and 10, which shows an annular throttle element 222 arranged in the bypass passage 130 alone, it can be seen that the throttle element 222 is provided with a plurality of circular passage openings 224, which follow each other along the circumference of the throttle element 222, preferably equidistantly. The ratio of the total area of the passage openings 224 in the throttle element 222 to the maximum throughflow cross-sectional area of the bypass device 126 can be selected in the same way as in the first embodiment.

Finally, FIGS. 11 to 14 show details of an embodiment for a separation device 124 of the bypass device 126, with a drive device 240 for driving a coupled adjustment movement of the bypass flap 212 and the heat exchanger flap 208.

As best seen in FIGS. 11 and 12, the bypass flap 212 and the heat exchanger flap 208 are pivotably mounted on the bypass shaft 210 and on the inlet shaft 206 respectively about a rotational shaft 242 and 244 between an open position and a closed position.

Best of Fig. 12 it can be seen that the bypass flap 212 is currently in its open position, in which it releases the maximum inlet cross section for the inflow of the bypass fluid flow into the bypass device 126, while at the same time the heat exchanger flap 208 is in its closed position, in which the heat exchanger flap 208 prevents the entry of raw gas into the section 150 of the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134.

In this position, the bypass flap 212 and the heat exchanger flap 208 so that the volume fraction of the bypass fluid flow in the entire raw gas stream, which enters the thermal exhaust air purification system 100, 100%.

The rotary shafts 242 and 244 are coupled to each other via a parallelogram linkage 246 shown in FIG. 14 so that the bypass damper 212 and the heat exchanger damper 208 perform opposite equal pivotal movements when the rotary shaft of the bypass damper 242 is driven to pivot. Such a pivoting movement is triggered by means of an electric drive motor 248, which generates a displacement of a rectilinear guided free end of a lever 249 via a rotary spindle assembly 250, which is articulated via a hinge 251 to a further lever 252, which in turn is non-rotatably connected to the rotary shaft 242 ,

If the bypass flap 212 in the in Fig. 12 shown pivoted open position due to a control signal of the control device of the thermal exhaust air purification system 100, the heat exchanger flap 208 is simultaneously moved by the coupling of the two flaps 212 and 208 via the parallelogram linkage 246 from its closed position to the open position.

By setting between the respective open position and closed position intermediate positions of the flaps 212 and 208 of entering the thermal exhaust air purification system 100 raw gas stream in the control of the clean gas outlet temperature T _A respectively required ratio to the bypass fluid flow and the residual fluid flow split become.

One in Fig. 15 shows a schematic block diagram of a third embodiment of a thermal exhaust air purification system 100 differs from that shown in FIGS. 1 and 2 illustrated in that the inner heat exchanger chamber 140 of the clean gas Rohgas-Wärmetau- shear 134 is traversed in the third embodiment not by the clean gas, but by the raw gas, while the outer heat exchanger chamber 144 of the clean gas raw gas heat exchanger 134th in this embodiment, the clean gas flows through it.

Thus, in this embodiment, the clean gas serves as the outer fluid medium and the raw gas as the inner fluid medium. Therefore, in this embodiment, the bypass means 126, by means of which a portion of the outer fluid flow past a portion 150 of the outer heat exchange space 144 of the clean gas raw gas heat exchanger 134 to reduce the efficiency of the clean gas raw gas heat exchanger 134, if necessary, not raw gas side, but arranged on the clean gas side.

Thus, in this embodiment, the bypass device 126 comprises a separating device 124 arranged at the clean gas inlet into the clean gas raw gas heat exchanger 134, by means of which part of the clean gas flow from the combustion chamber 102 can be separated as a bypass fluid flow from a residual fluid flow of the clean gas and via a bypass channel 130 a Zumischvorrich- device 148 can be fed, by means of which the bypass fluid flow is again mixed into the residual fluid stream of the clean gas, after this residual fluid flow has passed the portion 150 of the outer heat exchanger chamber 144 of the clean gas Rohgas heat exchanger 134.

In this embodiment, since the efficiency of the clean gas raw gas heat exchanger 134 can be reduced by passing an adjustable proportion of the total clean gas flow at the portion 150 of the outer heat exchanger space 144 of the clean gas raw gas heat exchanger 134 in a controlled manner, in this embodiment as well Regulation of the clean gas raw gas heat exchanger 134, a regulation of the clean gas outlet temperature T _A possible.

Incidentally, the third embodiment of a thermal exhaust air purification system 100 illustrated in FIG. 15 is identical in construction and function to the embodiment shown in FIGS. 1 and 2 illustrated first embodiment and also with the second embodiment shown in FIGS. 3 to 14, to the above description in this respect reference is made.

Claims

claims

Thermal exhaust air purification system comprising a combustion chamber (102) and a heat exchanger (134) for transferring heat from a clean gas generated in the combustion chamber (102) to a raw gas to be supplied to the combustion chamber (102),

wherein the heat exchanger (134) is one of an internal fluid

Medium permeable inner heat exchanger chamber (140) and an outer heat exchanger chamber (144) through which an outer fluid medium can flow, in that the thermal exhaust air purification system (100) has a bypass device (126).

with a separation device (124), by means of which a part of the outer fluid flow is separable as a bypass fluid flow from an outer residual fluid flow, and

with an admixing device (148), by means of which the bypass fluid flow can be mixed again into the residual fluid flow, after the residual fluid flow has a section (150) of the outer fluid flow

Heat exchanger room (144) has happened

includes.

Thermal exhaust air purification system according to claim 1, characterized in that the admixing device (148) comprises at least one admixing point (220) which extends over at least half of the circumference of the residual fluid flow.

3. Thermal exhaust air purification system according to claim 2, characterized in that the admixing point (220) extends annularly around the flow path of the residual fluid flow around.

4. Thermal exhaust air purification system according to one of claims 1 to 3, characterized in that the admixing device (148) comprises a plurality of admixing points (220), wherein the admixing points (220) are distributed over an admixing area which extends over at least half of the circumference of the remainder Fluid stream extends.

5. Thermal exhaust air purification system according to one of claims 1 to 4, characterized in that the bypass device (126) has a

Bypass passage (130) which surrounds the flow path of the residual fluid flow in an annular manner.

6. Thermal exhaust air purification system according to one of claims 1 to 5, characterized in that the bypass device (126) comprises at least one throttle element (222) in the flow path of the bypass fluid flow.

7. Thermal exhaust air cleaning system according to claim 6, characterized in that at least one throttle element (222) as a flow barrier with through openings (224) is formed.

8. Thermal exhaust air purification system according to claim 7, characterized in that the total passage area of the passage openings (224) in the flow barrier is 150% or less of an inlet cross-sectional area of the bypass device (126).

9. Thermal exhaust air purification system according to one of claims 1 to 8, characterized in that the admixing device (148) upstream of an outlet (146; 162) of the outer fluid medium from the outer heat exchanger space (144) is arranged.

10. Thermal exhaust air purification system according to one of claims 1 to 9, characterized in that the separating device (124) a

A bypass door (212) for controlling the entry of the bypass fluid flow into the bypass means (126) and a heat exchange door (208) for controlling the entry of the residual fluid flow into the heat exchanger (134).

11. Thermal exhaust air purification system according to claim 10, characterized in that the bypass flap (212) and the heat exchanger flap (208) are mechanically and / or control technology coupled together.

12. A thermal exhaust air purification system according to any one of claims 1 to 11, characterized in that the separating device (124) upstream of an inlet (132; 160) of the residual fluid flow in the outer heat exchanger space (144) is arranged.

13. Thermal exhaust air purification system according to one of claims 1 to 12, characterized in that the outer heat exchanger chamber (144) from the combustion chamber (102) zuzuführendem raw gas can be flowed through.

14. Thermal exhaust air cleaning system according to one of claims 1 to 12, characterized in that the outer heat exchanger space (144) of the combustion chamber (102) produced clean gas can be flowed through. Process for purifying a raw gas stream containing oxidizable constituents by means of a thermal exhaust air purification plant, comprising the following process steps:

Supplying the raw gas stream to a combustion chamber (102);

Generating a clean gas stream by at least partially oxidizing the oxidizable constituents of the crude gas stream in the combustion chamber;

Transferring heat from the clean gas stream to the raw gas stream by means of a heat exchanger (134), the heat exchanger (134) comprising an inner heat exchanger space (140) through which an inner fluid medium flows and an outer heat exchanger space (144) through which an outer fluid medium flows; characterized by the following further method steps:

Separating a portion of the outer fluid stream as a bypass fluid stream from an outer residual fluid stream by means of a separation device (124);

Mixing the bypass fluid stream into the residual fluid stream by means of an admixing device (148) after the residual fluid stream has passed through a portion (150) of the outer heat exchanger space (144).