EP2175197B1 - Method for cleaning exhaust gases through regenerative postcombustion - Google Patents

Description

The present invention relates to a method for purifying exhaust gases by generative afterburning. An oxygen-free exhaust gas with combustible impurities, such as occurs in hardening shops, is incinerated without prior heating or heat exchange in a combustion chamber and the resulting exhaust subsequently cleaned in a catalytic purification stage. Furthermore, an apparatus for carrying out the method is presented.

In the prior art, a number of methods are known for purifying exhaust gases containing combustible impurities such as hydrocarbons or hydrogen. For the purposes of this application, the term "exhaust gas" is to be understood as meaning not only the exhaust gas of a combustion but also a pollutant-laden exhaust air from installations.

The simplest method is burning in a torch. Here, the exhaust gases to be cleaned are fed to an open flame and burned the ignitable components there. This method is characterized by a simple and inexpensive device that quickly reaches operational readiness during commissioning. However, this is offset by the disadvantages that the exhaust gas must be ignitable, the process is not regulated and compliance with the limit values for pollutants in the exhaust gas is not always guaranteed.

An improvement of the method is known as thermal afterburning (TNV) method. Here, the exhaust gases are heated depending on the composition of the components to be removed to temperatures of 750-1000 ° C and burned in a combustion chamber. To comply with explosion protection regulations, the exhaust gases must first be diluted with enough air to ensure that the concentration of the combustible components remains constant of less than 25% of the lower explosive limit. Since the combustion takes place in a simple burner, the TNV is also a simple device. The hydrocarbons of the exhaust gas are safely converted and the limits for pollutants in the exhaust gas thus reliably maintained. Also in this system, the operational readiness is reached quickly. However, the TNV has the drawback of a very high energy consumption, since the large amount of added air to heat a much larger amount of gas than the original exhaust gas to very high temperatures. By downstream heat exchanger, which in turn can preheat the exhaust gas before entering the combustion chamber, the efficiency can be improved, but since the preheating may only be so high that no reaction takes place in the heat exchanger, is still a considerable amount of energy to spend. Likewise, the production costs of a TNV plant are higher, as higher material costs are incurred due to the high process temperatures (eg for high temperature resistant steels). In addition, there is a greater effort by the need for the use of explosion-proof valves.

Exemplary of the innumerable thermal post-combustion plants described in the technical and patent literature are here DE 2 026 237 A1 and WO 87/05090 A1 called. In DE 2 026 237 A1 a method and apparatus for thermal post-combustion of exhaust air from industrial plants is described, in which the exhaust air is preferably preheated under elevated pressure through one or more heat exchangers, then introduced into a combustion chamber, there first flows through another heat exchanger and then burned in a burner becomes. The hot combustion gases then pass through the heat exchangers in reverse order before being released into the open. Part of the amount of exhaust gas burned is returned in the combustion chamber to increase the degree of conversion of the impurities. In WO 87/05090 A1 discloses a method and a device for the thermal burning of oxidizable constituents in a process gas, which is characterized in that the exhaust gas is preheated by a heat exchanger, which is traversed by the purified exhaust gas and then by means of a burner in a combustion chamber, wherein the exhaust gas to be purified before the entry into the afterburner in addition to the required fresh air and an amount of purified exhaust gas is supplied, that the concentration of oxidizable constituents in the incoming gas stream is kept constant.

An advancement of the TNV is the catalytic afterburning (KNV). In this case, the temperature required for the safe conversion of the hydrocarbons is lowered by the use of a catalytic purification stage. Depending on the exhaust components to be removed and the catalyst used, the exhaust gas to be cleaned is heated to 250-400 ° C. with the aid of heat exchangers and optionally an auxiliary heater or an additional burner. Again, to comply with the requirements of explosion protection, dilution of the supplied exhaust gases with air to a concentration of the combustible constituents of less than 25% of the lower explosion limit must be carried out again. The advantages of the KNV are the same as those of the TNV, whereby the energy consumption is significantly lower. By downstream heat exchanger and recovery of the heat of reaction can even be achieved autothermal operation of the system. The disadvantage, however, is that the amounts of exhaust air generated are just as high as in the TNV, whereby a fairly high energy input is necessary especially in the case of expected concentration peaks of hydrocarbons in the exhaust gas. In addition, an autothermal operation is possible only from average hydrocarbon concentrations. Below is a support fire with additional exhaust or additional heating necessary. Another disadvantage is the sensitivity of the catalyst to certain catalyst poisons, such as. As halogens, silicones, phosphorus, sulfur and heavy metals, which must be safely excluded from the exhaust gas to be cleaned. Furthermore, the degree of conversion at the catalyst bed is somewhat lower than in the TNV.

Regenerative afterburning (RNV) is a TNV or KNV with "integrated" heat recovery. The heat content of the purified waste gas is stored in a heat storage mass, which is located directly in the oxidation zone, and is therefore directly involved in the oxidation process to disposal. As a rule, ceramic packed beds are used for this, which enable a good efficiency of heat transfer with low pressure loss. In the case of thermal afterburning, the bed is filled with inert bulk material while the catalytic afterburning unit is charged with an appropriate catalyst charge. At least two such beds are operated in cyclic alternation, wherein a hot bed for preheating the exhaust gas is flowed through by this and thereby cools and the second cold bed is heated by the oxidation of the exhaust gases. The oxygen in the cooling air, which is supplied in the catalyst, in this case participates in the reaction. Due to the good heat recovery within the system, an autothermal mode of operation can be achieved in catalytic systems even at low concentrations of hydrocarbons. However, this advantage is associated with a high expenditure on equipment with a correspondingly large space requirement. In addition, the use of valves that lock hot gases, requires increased maintenance. Due to the long heat-up time, which require the heat storage, the operational readiness of such a system is reached only slowly. Therefore, these systems are unsuitable for sporadic or short-term use and useful only in continuous operation.

An example of the regenerative afterburning can be found in the DE 196 11 226 C1 , where a device for thermal exhaust gas treatment, in particular of oxidizable carbonization gases, is presented, which comprises a regenerator unit with at least two regenerators each having a heat storage and a heating zone arranged between the regenerators and a buffer cell. The exhaust gas stream to be cleaned can be fed alternately from one side of a series arrangement of at least two regenerators, wherein the remaining during the switching uncleaned in the regenerators exhaust gas in a buffer cell, which is heated by the purified exhaust gas stream is stored, and after completion of the switching operation the input current again is added.

Furthermore, from the US Pat. No. 7,273,366 B1 a burner unit for the combustion of harmful vapors and exhaust gases is known, which is characterized by its construction of two concentric nested burner elements. The gases to be combusted can either be burned directly in the inner burner or preheated in the annular gap between the inner burner and the outer burner tube. The fuel gas routing and mixing is influenced by possibly perforated or slotted cones. To improve the oxidation performance, a catalyst unit can be connected at the end of the burner. A particular field of application of this technology are exhaust gases with low oxygen contents and high proportions of non-combustible or hardly combustible components.

From the disadvantages of the known in the art exhaust and Abluftreinigungsverfahren the object of the present invention is to provide a method for exhaust gas cleaning available, the cleaning of oxygen-free exhaust gases in a compact design with low space requirements with minimal energy consumption high concentrations of combustible components, such as those incurred in exhaust gases from hardening shops. The concentration of combustible constituents can be up to 100% by volume in these. For the purposes of the invention, oxygen-free exhaust gases are to be understood as those exhaust gases which contain no oxygen, which is ensured by a permanent oxygen analysis.

1. a. Zuführen der zu reinigenden Abgase;
2. b. Ausgleichen von Druck- und Mengenschwankungen in den zu reinigenden Abgasen;
3. c. Mischen eines ersten Gasstroms, bestehend aus den zu reinigenden Abgasen, mit einem zweiten Gasstrom, bestehend aus Erdgas, wobei die zugemischte Menge an Erdgas abhängig ist vom Gehalt der brennbaren Bestandteile in den Abgasen und ausreichend ist, um eine stabile Verbrennung zu gewährleisten;
4. d. Einleiten der gemischten Gasströme und eines dritten Gasstroms bestehend aus Verbrennungsluft in einen Brenner wenigstens einer Brennkammer;
5. e. Verbrennung der vereinigten Gasströme in der Brennkammer bei so hohen Temperaturen, dass unerwünschte, brennbare Gasbestandteile durch Oxidation entfernt werden, wobei die bei der Oxidation aus dem Energieinhalt der Abgase gewonnene Wärmeenergie direkt zur Erhitzung der Abgase eingesetzt wird;
6. f. Katalytische Reinigung der oxidierten Abgase zur Umsetzung darin verbliebener Verunreinigungen in einer katalytischen Reinigungsstufe am Ausgang der Brennkammer;
7. g. Einleiten von Kühlluft in die Brennkammer zum Einstellen der erforderlichen Temperatur für die katalytische Reinigung in der katalytischen Reinigungsstufe.

The object is achieved by the inventive method for purifying oxygen-free exhaust gases by generative afterburning, wherein the exhaust gases have fractions of combustible constituents of up to 100% and the energy content of the exhaust gases is used directly for heating the exhaust gases, including the steps

1. a. Supplying the exhaust gases to be cleaned;
2. b. Compensation of pressure and volume fluctuations in the exhaust gases to be cleaned;
3. c. Mixing a first gas stream consisting of the exhaust gases to be cleaned with a second gas stream consisting of natural gas, the added amount of natural gas being dependent on the content of the combustible constituents in the exhaust gases and sufficient to ensure stable combustion;
4. d. Introducing the mixed gas streams and a third gas stream consisting of combustion air into a burner of at least one combustion chamber;
5. e. Combustion of the combined gas streams in the combustion chamber at such high temperatures that unwanted, combustible gas constituents are removed by oxidation, which in the oxidation of the energy content of the exhaust gases obtained heat energy is used directly for heating the exhaust gases;
6. f. Catalytic purification of the oxidized exhaust gases to react therein residual impurities in a catalytic purification stage at the exit of the combustion chamber;
7. G. Introducing cooling air into the combustion chamber to adjust the required temperature for the catalytic purification in the catalytic purification stage.

The exhaust gases to be treated may consist of 100 vol .-% of combustible constituents, contain in a preferred embodiment of the invention, however, at least 0 vol .-%, preferably at least 10 vol .-%, more preferably at least 20 vol .-% combustible fractions.

If the proportion of combustible gases in the exhaust gas is less than 100% by volume, the exhaust gases are mixed with natural gas before combustion in the burner in order to promote oxidation. The amount of natural gas added depends on the content of the combustible components in the exhaust gas.

Particularly preferably, the addition of the natural gas by means of an automatic control, which ensures that a temperature is maintained in the combustion chamber, which is high enough for the subsequent catalytic purification stage. Likewise, preferably, an automatic control of the cooling air supply into the combustion chamber, via which the temperature can be kept below the maximum, which corresponds to the maximum operating temperature of the catalyst.

The flame temperature of the burner is preferably maintained in the range of 600-1200 ° C, more preferably in the range of 800-1000 ° C. The catalytic purification stage is preferably operated at 300-650 ° C., more preferably at 400-530 ° C.

In a particularly preferred embodiment, the regulation of the natural gas supply into the burner takes place as a function of the temperature in the combustion chamber and / or the temperature at the inlet into the catalyst. Decreases at a constant supply of combustion air and cooling air, the temperature in the combustion chamber or at the catalyst inlet, the natural gas supply is increased because less combustible components are present in the exhaust gas. If the temperature rises, less natural gas is added accordingly.

A device for carrying out the method according to the invention, which in the flowchart in Fig. 1 is shown with its essential functional elements, characterized in that it comprises an exhaust gas supply line (1), a natural gas supply line (2), an air supply line (3), one or more combustion chambers (7) with a burner connected thereto (6), an am Output of the combustion chamber installed catalytic purification stage (8) and has monitoring devices for the course of the combustion.

The air supply line (3) is connected directly to the burner (6) and the mixing of exhaust gas and / or natural gas with the combustion air takes place only immediately in the burner (6).

In a preferred embodiment, a separate safety distance is provided for increasing the safety in the gas supply line for natural gas and the exhaust gas.

The exhaust gas supply line is particularly preferably equipped with a gas buffer container (9), so that pressure and volume flow fluctuations in the exhaust gas stream to be cleaned can be compensated and not transferred to the burner (6). This ensures a more even combustion.

In a further preferred embodiment, the natural gas supply line (2) and the exhaust gas supply line (1) are brought together before entering the burner in a mixing chamber (33). Thereby, the mixing can be ensured even at higher inert gas in the exhaust gas.

In another embodiment, the burner is a blower burner with two fuel gas inlets. This allows the exhaust gas to be cleaned and the natural gas also supplied unmixed to the burner and only be mixed directly in the burner.

The combustion air supply is preferably via a fan (in the air blower (34)) and / or via a valve (35) adjustable. Depending on the required flow rate, the control takes place via a valve or at higher throughputs via a fan. If necessary, both are adjustable for fine tuning.

The monitoring devices are particularly preferably integrated into a total control with transducers. This enables efficient centralized control and monitoring.

The components of the device are preferably transported separately as individual modules and can be built on site with connecting pipes and connections to the entire system. For this purpose, the connecting pipes are preferably equipped with a quick coupling system.

In a particularly preferred embodiment, the entire device can be transported as a compact unit in the build-up state. This makes it possible to make the emission control system quickly ready for use and, if necessary, to connect to an exhaust gas generating plant. Due to the compact design, this can also be done in confined spaces.

Due to the modular design, in several embodiments, several exhaust gas generating plants with their exhaust gas supply lines (1) to a correspondingly sized burner (6) can be connected. Furthermore, the exhaust gases of several combustion chambers (7) of a correspondingly dimensioned common catalytic purification stage (8) can be supplied. As a result, the system concept can be flexibly adapted to local conditions and further space can be saved through shared system components.

In the methods described in the prior art usually for reasons of explosion protection, a dilution of the exhaust gases to be cleaned with air to a concentration of the combustible components of less than 25% of the lower explosion limit. As a result, very large quantities of gases have to be transported and heated. These methods are therefore rather unsuitable for exhaust gases with very high levels of combustible gases. By contrast, the present invention is particularly directed to such exhaust gases with high levels of combustible gases of up to 100%. Such exhaust gases come z. As in hardening shops in the metalworking industry, the workpieces cure in the absence of air using hydrocarbons in closed furnaces. An exhaust gas purification of such exhaust gases is currently not taking place.

Due to the restriction to such oxygen-free exhaust gases and the absence of preheating the exhaust gases, the requirements for explosion protection are much lower. The quantities of gas to be transported advantageously remain small and the heating of the exhaust gases to the temperatures required in the catalytic purification stage (8) is predominantly due to the high heat of combustion of the exhaust gas due to the high concentrations of combustible gas constituents. Air is supplied for this purpose only in approximately stoichiometric amount for the combustion. If the proportion of flammable components in the exhaust gas decreases, natural gas is mixed in if necessary to ensure constant combustion temperatures. The essential difference to the known methods with heat recovery is that the energy content of the exhaust gas is used directly for heating. Therefore, the method of the present invention is also referred to as "generative afterburning" (GNV), in contrast to regenerative afterburning.

In the burner (6) all flammable under the given conditions flammable gases are burned. As a result, about 98% of the impurities are removed from the exhaust gas. For further purification then joins a catalytic purification stage (8). By a controlled admixture of cooling air into the combustion chamber, the process temperature for the subsequent catalytic purification set. Therefore, it is possible to keep the flame temperature in the burner at such high temperatures that there already burns a large part of the impurities. The catalytic post-purification then ensures complete conversion of the hydrocarbons, which were not or incompletely reacted in the burner. After leaving the catalyst stage via the outlet (5), the purified waste gas can be cooled by means of heat exchangers (not shown in the drawings) and the energy recovered from this via thermal oil and / or steam can be made available to other processes, since they are not suitable for preheating the exhaust gases to be cleaned is needed.

The described method has several advantages: It allows very compact systems because of the small volume flows, since the admixture of air to the exhaust gas is eliminated. The air is first supplied to the burner, so that there is no explosive mixture before. Therefore, there are only minor requirements for explosion protection. Furthermore, this results in low system costs, low energy consumption and low maintenance costs. The operational readiness of the system can be achieved within a few minutes. The GNV works independently of the concentration of carbon dioxide in the exhaust gas.

In the following, the presented method is based on the flow chart of a system in an advantageous embodiment in Fig. 2 be explained in more detail.

Via the exhaust gas supply line (1), the exhaust gas laden with combustible components passes via the solenoid valve (11) into the gas buffer container (9). The exhaust gas supply line (1) has a diameter of 25 mm in this embodiment. The exhaust gas has a maximum temperature of about 50 ° C and a pressure of about 130 kPa (1.3 bar). To ensure that there is no oxygen in the exhaust gas, a permanent oxygen analysis (15) is performed. The gas buffer (9) is used to compensate for pressure and volume fluctuations in the exhaust gas. Pressure monitoring by means of the PS + pressure switch (18) on the gas buffer tank (9) ensures that when a certain minimum pressure is reached by opening the solenoid valve (12), the exhaust gas to be cleaned the burner (6) is supplied. When a maximum pressure is exceeded, the excess pressure is reduced by opening the solenoid valve (10) and discharging the exhaust gas directly through the emergency outlet via the roof (4). The corresponding outlet line is secured with a check valve (16). Since the gas buffer container (9) after initial construction of the system is still filled with air, in front of the gas buffer container (9) is a purge gas supply line (13) with a manual inlet valve for an oxygen-free purge gas, usually nitrogen attached. The corresponding Spülgasauslass (14) with manual outlet valve is after the manual pressure control valve (17) behind the solenoid valve (12), which is the guarantee of constant pressure conditions for the burner (6) arranged. Thus, you can first manually rinse the gas buffer tank (9) and its inlets and outlets perform at the first startup of the system before the introduction of the exhaust gas to be cleaned to produce the oxygen-free and thus the explosion protection.

Before being fed into the burner (6), the gas pressure is reduced by a pressure reducer (25) and kept constant. Before entering the burner (6) is mixed with an amount of natural gas, which is sufficient to ensure stable combustion. Prior to mixing, which can take place either in a mixing chamber (33) or directly through a pipe junction depending on the gases contained and volume flows through, both gas strands each pass through their own safety fittings section consisting of a pressure switch and redundancy reasons two solenoid valves (27, 28 and 29 , 30).

The quantities of gas introduced into the mixing chamber (33) or the burner (6) are controlled by motor valves (19, 20) which are connected to the exhaust gas line by means of the pressure switches PS- (31) and PS + (32) and the natural gas line via the temperature regulator ( 23) which is arranged at the inlet of the catalytic purification stage (8). The engine valve (19) thus additionally ensures that the pressure is kept constant in the range set at the pressure switches (31) and (32). Especially when opening the solenoid valves (27, 28) so peaks in the energy input into the burner can be avoided. A corresponding safety circuit allows the opening of the solenoid valves (27, 28) only when the engine valve (19) is in its minimum position.

The necessary for the combustion of the exhaust gases (oxidation of impurities) combustion air is metered in via the air supply line (3). At the valve (35), the amount of air is adjusted so that it supplies the oxygen in approximately stoichiometric amount for the combustion of the design gas mixture to be expected from natural gas and exhaust gas. If the system is designed for larger throughputs, alternatively or in addition to this, the regulation of the air supply can also take place via the fan of the air blower (34). An automatically controlled supply of cooling air into the combustion chamber (7) takes place via the engine valve (21). The temperature controller (23), which measures the inlet temperature at the catalytic purification stage (8), correspondingly controls the engine valves (20, 21) to ensure stable combustion and the required inlet temperature for the catalyst. For additional monitoring of the burner in the combustion chamber (7) of the temperature switch (22) is mounted, which measures the temperature in the burner tube before mixing with the cooling air.

During combustion in the burner (6) already about 98% of the impurities are removed from the exhaust gas. To complete the implementation of the remaining impurities, the catalytic purification stage (8) adjoins the combustion chamber (7). The cleaned flue gas leaves the unit via the outlet (5), which has a diameter of 200 mm, with a maximum pressure of approx. 105 kPa (1.05 bar) and a maximum temperature of approx. 530 ° C. This can either be directly followed by a chimney or one or more heat exchangers for the recovery of heat energy for other processes, which is not shown in the drawing.

The control process by the temperature controller (23) is carried out as follows: When commissioning the system, the amount of air calculated for the stoichiometric combustion of the exhaust gas / natural gas mixture is set at the valve (35). The engine valve (21) is adjusted so that a minimum amount of air in the burner (6) passes. Subsequently, the solenoid valves (29, 30) of the safety route are opened and the system initially operated in standby mode with natural gas. The engine valve (20) is accordingly fully open. If the predetermined minimum pressure is present at the gas buffer container (9) and the temperature at the inlet of the catalytic purification stage (8) has reached its minimum value, the solenoid valves (27, 28) of the exhaust gas line are opened and the system operates in the disposal mode. When the air supply is initially unchanged, the temperature regulator (23) throttles the engine valve (20) in order to keep the inlet temperature at the catalyst in the intended range. If the engine valve (20) reaches its minimum position and the temperature in the combustion chamber (7) is still too high, then the temperature controller (23) also controls the engine valve (21) and thus opens the cooling air supply into the combustion chamber (7). If the content of combustible constituents in the exhaust gas and thus the temperature in the combustion chamber decreases, the temperature regulator (23) restricts the engine valve (20) again and optionally further opens the natural gas supply via the engine valve (20). As a safety function, the temperature switch (24) is mounted at the outlet of the catalytic purification stage (8), which monitors the maximum operating temperature of the catalyst. If this temperature is exceeded, the temperature switch (24) triggers the emergency shutdown of the system by closing the solenoid valves (11, 12) and opening the solenoid valve (10). The exhaust gas is then safely discharged through the emergency outlet via roof (4).

The catalyst used in the catalytic purification stage (8) is an oxidation catalyst, which in this example consists of a 1: 1 mixture of palladium and platinum, present in an amount of 40 g / 28,316.846592 cm ³ (40 g / ft ³ ) is applied to a carrier of cordierite honeycombs with 100 cells per 6.452 cm ² (100 cpsi).

Claims (19)

1. A method for the purification of oxygen-free exhaust gases by means of regenerative post-combustion, wherein the exhaust gases comprise portions of combustibles up to 100 % and the energy content of the exhaust gases is directly used for heating the exhaust gases,
   including the steps of:

   a. Supplying the exhaust gases to be purified;

   b. Compensating pressure and quantity fluctuations in the exhaust gases to be purified;

   c. Mixing a first gas stream consisting of the exhaust gases to be purified with a second gas stream consisting of natural gas, wherein the amount of natural gas mixed depends on the content of the combustibles in the exhaust gases and sufficient to ensure a stable combustion;

   d. Introducing the mixed gas streams and a third gas stream consisting of combustion air into a burner (6) of at least one combustion chamber (7);

   e. Combustion of the unified gas streams in the combustion chamber (7) at such high temperatures that undesired, combustible gas portions are removed by oxidation, wherein the thermal energy obtained from the energy content of the exhaust gas during oxidation is directly used for heating the exhaust gases;

   f. Catalytic purification of the oxidized exhaust gases for reacting remaining impurities in a catalytic purification stage (8) at the outlet of the combustion chamber (7);

   g. Introducing cooling air into the combustion chamber (7) for adjusting the temperature required for the catalytic purification in the catalytic purification stage (8).
2. The method according to claim 1, characterized in that the exhaust gases to be treated contain at least 0 vol.-%, preferably at least 10 vol.-%, particularly preferably at least 20 vol.-% combustible portions.
3. The method according to claims 1 and 2, characterized in that the supply of natural gas in the burner (6) for maintaining a combustion temperature, which is sufficient for the subsequent catalytic purification, is controlled automatically.
4. Method according to claims 1 to 3, characterized in that the supply of cooling air for adjusting the sufficient temperature required for the catalytic purification is controlled automatically.
5. The method according to claims 1 to 4, characterized in that the flame temperature of the burner (6) is between 600 °C and 1200°C, preferably between 800°C and 1000°C.
6. The method according to claims 1 to 5, characterized in that the temperature in the catalytic purification stage (8) is between 300°C and 650°C.
7. The method according to claims 1 to 6, characterized in that the control of the supply of natural gas into the burner (6) is controlled depending on the temperature in the combustion chamber (7) and/or the temperature at the inlet of the catalyst.
8. A device for performing the method of claims 1 to 7, comprising an exhaust gas supply line (1), a natural gas supply line (2), an air supply line (3), one or multiple combustion chambers (7) having a burner (6) connected thereto, a catalytic purification stage (8) installed at the outlet of the combustion chamber (7) and monitoring devices for the combustion process, wherein the air supply line (3) is directly connected to the burner (6) and mixing of exhaust gas and/or natural gas with the combustion air is effected not until directly in the burner (6).
9. The device according to claim 8, characterized in that at least one safety section is provided in the supply lines for the natural gas (2) and the exhaust gas (1).
10. The device according to claims 8 and 9, characterized in that the exhaust gas supply line (1) is equipped with a gas buffer container (9).
11. The device according to claims 8 to 10, characterized in that the natural gas supply line (2) and the exhaust gas supply line (1) are brought together in a mixing chamber (33) prior to the introduction into the burner (6).
12. The device according to claims 8 to 11, characterized in that the burner (6) is a fan burner having two combustion gas inlets.
13. The device according to claims 8 to 12, characterized in that the supply of the combustion air can be controlled by means of a ventilator (34) and/or by means of a valve (35).
14. The device according to claims 8 to 13, characterized in that the monitoring devices are integrated in an overall control with measurement value sensors.
15. The device according to claims 8 to 14, characterized in that the connecting pipelines are equipped with a quick coupling system.
16. The device according to claims 8 to 15, characterized in that the component parts of the device are transportable as separate individual modules and installable at the site of operation by means of connecting pipelines and connections to the overall installation.
17. The device according to claims 8 to 16, characterized in that the entire device is transportable as a compact unit in the installation state.
18. The device according to claims 8 to 17, characterized in that the overall installation comprises multiple exhaust gas supply lines (1), which are fed to a common combustion chamber (7) having a burner (6).
19. The device according to claims 8 to 18, characterized in that the overall installation comprises multiple combustion chambers (7) having a burner (6), the exhaust gases of which are fed to a common catalytic purification stage (8).

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