AT508921A4 - METHOD AND APPARATUS FOR RELIEVING SMOKE GASES - Google Patents

Description

1

The invention relates to a method for denitrification of carbon monoxide and / or gaseous organic substances containing flue gases by selective catalytic reduction of nitrogen oxides in at least one Entstickungskatalysator, wherein the flue gases are heated to a catalytic reaction temperature before the catalytic reduction by heat exchange of the recovered residual heat of the denitrified flue gases.

Furthermore, the invention relates to a device for denitrification of carbon monoxide and / or gaseous organic substances containing flue gases, with at least one denitrification catalyst for the catalytic reduction of nitrogen oxides, and at least one heat exchanger for heating the flue gases from recovery of the residual heat of the denitrified flue gases before the catalytic reduction to a catalytic reaction temperature.

The present invention relates in principle to the denitrification of any flue gases containing carbon monoxide and / or gaseous organic substances, for example flue gases, which are produced in cement clinker production, in the brick production, glass industry, insulation industry or in sintering plants in the steel industry.

Advantageously, the selective catalytic denitrification is arranged after dedusting. The exhaust gases usually have a temperature below the reaction temperature of the catalyst and therefore must be reheated. For a catalytic denitrification, reaction temperatures of at least > 160 ° C to > 300 ° C necessary. For example, at 10 mg / Nm3 SO2, the exhaust gases must be heated to at least 240 ° C. This heating of the flue gases is standard by a heat exchanger or regenerator, which extracts the heat from the denitrified flue gases and feeds the flue gases before the catalytic reduction. The heat losses of the heat exchange in the recuperative or regenerative denitrification are compensated by the supply of additional energy. This additional energy can be supplied for example by a gas burner or an electric heater. 2

The AT 505 542 Bl describes, for example, a system for Rei nigung the flue gases in cement production, the flue gases with at least one combustion device for power generation, such as a gas turbine or a gas engine, or which is operated in particular with natural gas, are heated.

The object of the present invention is to provide a method and an apparatus of the above type, by which the use of external energy can be minimized or avoided, and yet a high degree of denitration can be achieved. Disadvantages of known methods or devices should be reduced or avoided.

The object of the invention is achieved in terms of the method in that the losses of the heat exchanges are at least partially offset by catalytic oxidation of carbon monoxide and / or gaseous organic substances. The invention thus provides that the carbon monoxide and / or the gaseous organic substances in the flue gases are oxidized by means of an oxidation catalyst. The heat of reaction released during this oxidation can be used to increase the temperature of the flue gases to the catalytic reaction temperature. In addition to the energy-saving form of heating the flue gases for the catalytic reduction, the carbon monoxide contained in the flue gases and / or the gaseous organic substances are also reduced. The necessary amount of energy, for example in the form of thermal or electrical energy, can be considerably reduced by the method according to the invention, or the supply of external energy is only necessary when starting up and shutting down. The cost of implementing the method according to the invention is relatively low and the method thus cost feasible. In the present invention, the flue gases are thus not only de-embroidered, but also reduces their carbon monoxide content and their content of gaseous organic substances. By reducing the gaseous organic substances, in particular organic compounds of so-called "Volatile Organic Compounds". (VOCs), the odor load from the flue gases can be reduced. For regenerative processes 3

Ren work in addition to the actual heat storage masses and the catalysts used as a heat exchanger, since they also include ceramic or mineral materials.

According to one embodiment variant of the method according to the invention, it is provided that the flue gases are directed in an alternating direction through at least one channel with at least two heat storage masses arranged therein and at least one oxidation catalyst arranged between the heat storage masses and at least one defrosting catalyst arranged between the heat storage masses. In this variant of the denitrification according to the invention heat storage masses, oxidation catalyst and Entstickungskata lysator for catalytic reduction in a channel combined and the alternating direction of the flue gases, the flue gases are heated regeneratively to the temperature required for the catalytic reduction. Due to the oxidation, the process can proceed with sufficient contents of carbon monoxide and / or organic compounds without external energy supply. The temperatures in this embodiment of the denitrification catalyst are usually between 160 ° C and 600 ° C, preferably between 200 ° C and 600 ° C and the temperatures of the oxidation catalyst between 150 ° C and 700 ° C, preferably between 200 ° C and 600 ° C. ,

According to a further embodiment, the flue gases are passed through the at least one channel with the at least one oxidation catalyst and at least one denitrification catalyst having at least one heat storage mass between the at least one oxidation catalyst and the at least one denitrification catalyst. In this embodiment, a heat storage mass is provided between each of the catalysts, so that they work at different temperature levels.

The temperatures in this embodiment of the denitrification catalyst are usually between 160 ° C and 600 ° C, preferably between 200 ° C and 500 ° C and the temperatures of the oxidation catalyst between 150 ° C and 700 ° C, preferably between 350 ° C and 600 ° C. ,

As an alternative to the separate oxidation and denitrification catalysts, the flue gases can also be conducted in an alternating direction through the at least one channel with at least one combined oxidation and denitrification catalyst for combined catalytic oxidation and denitrification.

According to a further embodiment variant, the catalytic oxidation is carried out in a channel in at least one oxidation catalytic converter downstream of the at least one denitrification catalyst. The flue gases are brought through a heat exchanger, such as plate heat exchanger, to the necessary reaction temperatures of 160 ° C to 550 ° C, preferably 250 ° C to 450 ° C.

In one variant of the method, the flue gases are passed into a channel with at least one oxidation catalyst and at least one denitrification catalyst arranged therein, and the flue gases are recuperatively heated by the purified flue gases through a heat exchanger, for example a plate heat exchanger.

According to a further embodiment, the organic substances contained in the flue gas are at least partially removed from the flue gas by means of adsorption before the catalytic oxidation. In the flue gas contained organic substances cause the catalyst used for the catalytic oxidation is relatively quickly inoperative. By providing an adsorption stage, these interfering organic substances can be removed from the flue gas before the catalytic oxidation, whereby the usability of the oxidation catalyst can be advantageously increased. The adsorption stage may contain, for example, activated carbon as the adsorbent and thus prevents the entry of the organic compounds which would poison the oxidation catalyst or block the active sites.

According to a further embodiment variant, the flue gases can also be catalytically oxidized and deesterified in at least one combined oxidation and denitrification catalyst.

To start and / or maintain the catalytic reaction temperature external heat energy can be supplied. This external heat energy can be supplied, for example, by combustion 5 of petroleum or natural gas or by electrical energy.

To increase the energy which can be obtained during the post-oxidation, according to a further embodiment of the present invention, the content of carbon monoxide and / or gaseous organic substances in the flue gases can be purposefully increased by control measures. For example, in cement production by reducing the air supply in the rotary kiln, the content of carbon monoxide can be increased and thus the energy production by the post-oxidation can be improved.

The object of the invention is also achieved by an above-mentioned device for denitrification of carbon monoxide and / or gaseous organic substances containing flue gases, to compensate for the losses of heat exchange at least one oxidation catalyst for the catalytic oxidation of carbon monoxide and / or gaseous organic substances is provided. The advantages of the device according to the invention can be taken from the abovementioned advantages of the denitrification process.

In one embodiment variant of the device according to the invention, the at least one oxidation catalytic converter and the at least one denitrification catalyst are arranged in at least one channel with at least two heat storage masses arranged therein and a control device is provided for guiding the flue gases in an alternating direction through the at least one channel.

Alternatively, the at least one oxidation catalyst and the at least one denitrification catalyst can be arranged separately between the at least two heat storage masses arranged in the at least one channel, wherein at least one heat storage mass can be arranged between the at least one oxidation catalyst and the at least one denitrification catalyst.

Alternatively, at least one combined oxidation and denitrification catalyst may be used for the combined catalytic oxidation.

- 6 - dation and denitrification may be provided in the at least one channel.

According to an alternative embodiment variant, the at least one oxidation catalytic converter can be connected downstream of the at least one denitrification catalytic converter.

As already mentioned above, a stage for the adsorption of organic substances from the flue gases can be provided. For adsorption, e.g. Activated carbon can be used. According to a further feature of the present invention, the use of a bag filter with a supply line for a corresponding adsorbent is also conceivable.

Also in the variant without alternating flow of the flue gases through the channel, at least one combined oxidation and denitrification catalyst for the combined catalytic oxidation and denitrification can be provided.

The at least one oxidation catalyst may be formed, for example, by a metal-doped zeolite catalyst.

The at least one denitrification catalyst can be formed, for example, by a vanadium-tungsten-titanium oxide catalyst.

The oxidation catalyst, the denitrification catalyst or the combined oxidation and denitrification catalyst can be formed, for example, by a zeolite catalyst, for example doped with copper or iron, having a catalytic reaction temperature in the range from 160 ° C. to 700 ° C.

The heat storage masses of the regenerators are preferably formed by ceramic honeycomb bodies. The catalysts are preferably likewise of honeycomb construction.

According to a further feature of the invention, a device for supplying external heat energy for starting and / or maintaining the catalytic reaction temperature is provided. As already mentioned above, the external heat energy can be dissipated by thermal energy, e.g. Natural gas or petroleum or generated by electrical energy.

By means of deliberately increasing the content of carbon monoxide and / or gaseous organic substances in the flue gases, the energy yield of the post-oxidation can be increased.

As already mentioned above, these agents can be used to specifically increase the content of carbon monoxide and / or gaseous organic substances, for example by means of a throttle for reducing the air supply in an oven in which the flue gases are generated. As a result of these deteriorated combustion conditions in the furnace, the carbon monoxide content and / or the content of gaseous organic substances can thus be increased with little technical outlay.

The control device for the alternating conduction of the flue gases can be formed by corresponding flaps.

The present invention will be explained in more detail with reference to the accompanying drawings. Show:

Fig. 1 is a schematic view of a first embodiment of a device according to the present invention;

Fig. 2 is a schematic view of a second embodiment of a device according to the present invention;

Fig. 3 is a schematic view of a third embodiment of a device according to the present invention;

Fig. 4 is a schematic view of a fourth embodiment of a device according to the present invention; and

Fig. 5 is a schematic view of a fifth embodiment of a device according to the present invention.

Fig. 1 shows a first possible embodiment of the device according to the invention. In this embodiment, the flue gases A in an alternating direction by at least one channel 7 with arranged therein heat storage masses 1, 2 and arranged therebetween oxidation catalyst 4 for post-oxidation of carbon monoxide CO and / or gaseous organic substances and denitrification 3 for the catalytic reduction of nitrogen oxides of the flue gases A. directed. Due to the alternating flow direction, the heat storage masses 1 during the upward flow of the flue gases A, the thermal energy periodically withdrawn, which is required to bring the flue gases A to the reaction temperature TR Entstickungskatalysatoren 3 and the oxidation catalyst 4. After reaching the necessary reaction temperature TR and the chemical reactions that take place, the flue gases, when flowing downwards, periodically release the heat energy to the heat accumulator 1. The flow direction is alternated periodically and so the regenerators can never over cool or overheat. Via an external heating, the additional necessary heat can be supplied, which is indicated by the line 5. Gaseous fuel, for example natural gas, can be supplied via a line 5a. Via appropriate lines 6, the required for the catalytic reduction in the denitrification catalysts 3 ammonia-releasing compounds, preferably ammonia water, are added. The control of the alternating flow direction is effected by appropriate control means, which are realized here by flaps 8-11. The heat storage masses 1 may be formed by ceramic honeycomb body. In this variant, the denitrification catalysts 3 and oxidation catalysts 4 operate at a similar temperature level.

Fig. 2 shows another possible embodiment of the device according to the invention. This embodiment variant is similar to the first embodiment variant according to FIG. 1 and differs by the additional heat storage masses 2. In this variant, the denitrification catalysts 3 and the oxidation catalysts 4 operate at distinctly different temperature levels - 9 - • · «« · ···· · · »« »T * m ···« · * * * level. For example, the inlet temperature of the oxidation catalysts 4 may be 100 ° C. to 200 ° C. higher than the inlet temperatures of the denitrification catalysts 3.

A third embodiment of a device according to the invention is shown in FIG. According to this embodiment, the flue gases A are directed in an alternating direction through a channel 7. In channel 7, in turn, two heat storage masses 1 are arranged and provided therebetween a combined Entsti-ckungs- or oxidation catalyst 12.

A fourth embodiment of the device according to the invention is shown in FIG. The flue gas A is freed by an adsorber 14 from the organic compounds and then, as described in Fig. 1, further treated.

A fifth embodiment of the device according to the invention is shown in FIG. The flue gas A is brought by means of heat exchanger 13 through the hotter, purified flue gas to a temperature level which corresponds approximately to the reaction temperature TR. The heat exchanger 13 may be formed by a plate heat exchanger or tube bundle heat exchanger. The necessary further increase of the temperature level to the reaction temperature TR can be carried out partly or completely by the oxidation of the carbon monoxide CO and / or the gaseous organic compounds. Should the concentration of carbon monoxide in the flue gases A not be sufficient to carry the rest of the temperature increase in full, additional thermal or electrical energy must be supplied via line 5. Via line 5a in turn fuel can be supplied. For denitrification, ammonia-releasing compounds, for example ammonia water, are introduced via the line 6 into the channel 7. After the ammonia feed, the flue gases A flow through the denitrification catalyst 3 and subsequently through the downstream oxidation catalyst 4.

The hotter purified flue gas B then releases the heat energy in the heat exchanger 13 to the colder uncleaned flue gas A.

Claims (26)

1. A method for denitrification of carbon monoxide (CO) and / or gaseous organic substances containing flue gases (A) by selective catalytic reduction of nitrogen oxides (NOx) in at least one Entstickungskatalysator (3), wherein the flue gases (A) before the catalytic reduction by heat exchange of the recovered residual heat of the denitrified flue gases (A) are heated to a catalytic reaction temperature (TR), characterized in that the losses of heat exchange at least partially by catalytic oxidation of carbon monoxide (CO) and / or gaseous organic substances in at least one oxidation catalyst (4) are compensated. 2. The method according to claim 1, characterized in that the flue gases (A) in an alternating direction by at least one channel (7) with at least two arranged therein heat storage masses (1) and at least one between the heat storage masses (1) arranged oxidation catalyst (4) and at least one between the heat storage masses (1) arranged Entstickungskatalysator (3) are passed. 3. The method according to claim 2, characterized in that the flue gases (A) through the at least one channel (7) with the at least one oxidation catalyst (4) and at least one Entstickungskatalysator (3) with at least one heat storage mass (2) between the at least one Oxidation catalyst (4) and the at least one Entstickungskatalysator (3) are passed. 4. The method according to claim 2, characterized in that the flue gases (A) in an alternating direction through the at least one channel (7) with at least one combined oxidation and Entstickungskatalysator (12) are passed. 5. The method according to claim 1, characterized in that the catalytic oxidation in at least one of the at least one denitrification catalyst (3) downstream of the oxidation catalyst (4) is performed. 11 • · • · 6. The method according to claim 1, characterized in that the flue gases (A) in a channel (7) arranged therein with at least one oxidation catalyst (4) and at least one Entsti-ckungskatalysator (3) are passed and the flue gases (A) through the cleaned flue gases (B) by a heat exchanger (13) are heated recuperatively. 7. The method according to any one of claims 1 to 6, characterized in that in the flue gases (A) contained organic substances are at least partially removed by means of adsorption before the catalytic oxidation. 8. The method according to any one of claims 5 to 7, characterized in that the flue gases (A) in at least one combined oxidation and Entstickungskatalysator (12) are catalytically oxidized and de-nitrogenized. 9. The method according to any one of claims 1 to 8, characterized in that for starting and / or for maintaining the catalytic reaction temperature (TR) external heat energy is supplied. 10. The method according to any one of claims 1 to 9, characterized in that the content of carbon monoxide (CO) and / or gaseous organic substances in the flue gases (A) is specifically increased by control measures. 11. An apparatus for denitrification of carbon monoxide (CO) and / or gaseous organic substances containing flue gases (A), comprising at least one denitrification catalyst (3) for the catalytic reduction of nitrogen oxides (NOx), and at least one heat exchanger for heating the flue gases (A) Recovery of the residual heat of the denitrified flue gases (A) before the catalytic reduction to a catalytic reaction temperature (TR), characterized in that to compensate for the losses of heat exchange at least one oxidation catalyst (4) for the catalytic oxidation of the carbon monoxide (CO) and / or the gaseous organic substances is provided. 12. Device according to claim 11, characterized in that the at least one oxidation catalytic converter (4) and the at least one denitrification catalytic converter (3) are arranged in at least one channel (7) with at least two heat storage masses (1, 2) arranged therein, and one Control device for guiding the flue gases (A) in an alternating direction by the at least one channel (7) is provided. 13. The apparatus according to claim 12, characterized in that the at least one oxidation catalyst (4) and the at least one Entstickungskatalysator (3) are arranged separately between the at least two heat storage masses (1, 2) in the at least one channel (7). 14. The device according to claim 13, characterized in that between the at least one oxidation catalyst (4) and the at least one Entstickungskatalysator (3) at least one heat storage mass (2) in the at least one channel (7) is arranged. 15. The apparatus according to claim 12, characterized in that at least one combined oxidation and Entstickungskatalysator (12) for the combined catalytic oxidation and Entsti-ckung in the at least one channel (7) is provided. 16. The apparatus according to claim 11, characterized in that the at least one oxidation catalyst (4) is connected downstream of the at least one Entstickungskatalysator (3) and a heat exchanger (13) for recuperative heating of the flue gases (A) by the purified flue gases (B) as a heat exchanger. is arranged. 17. The apparatus according to claim 16, characterized in that a step (14) for the adsorption of organic substances from the flue gases (A) is provided. 18. The apparatus according to claim 17, characterized in that the adsorption stage (14) is formed by a bag filter with a feed line for the adsorbent. 19. Device according to one of claims 16 to 18, characterized thereby • fr ···································· I in that at least one combined oxidation and denitrification catalyst (12) is provided for the combined catalytic oxidation and denitrification. 20. Device according to one of claims 11 to 19, characterized in that the at least one oxidation catalyst (4) is formed by a metal-doped zeolite catalyst. 21. Device according to one of claims 11 to 20, characterized in that the at least one Entstickungskatalysator (3) is formed by a vanadium-tungsten-titanium oxide catalyst. 22. Device according to one of claims 11 to 21, characterized in that the at least one oxidation catalyst (4) and / or the at least one Entstickungskatalysator (3) and / or the at least one combined oxidation and Entstickungskatalysator (12) by a zeolite Catalyst, for example doped with copper or iron, having a catalytic reaction temperature (TR) in the range of 160 ° C to 700 ° C is formed. 23. Device according to one of claims 11 to 22, characterized in that the heat storage masses (1, 2) are formed by ceramic honeycomb body. 24. Device according to one of claims 11 to 23, characterized in that a device (5) for supplying external heat energy for starting and / or maintaining the catalytic reaction temperature (TR) is provided. 25. Device according to one of claims 11 to 24, characterized in that means are provided for selectively increasing the content of carbon monoxide (CO) and / or gaseous organic substances in the flue gases (A). 26. Device according to one of claims 12 to 15, characterized in that the control device for the alternating line of the flue gases (A) by flaps (8-11) is formed.