UTILIZATION OF NITROGEN OXIDES FROM AMBIENT AIR

Abstract

Utilization of nitrogen oxides contained in the ambient air including a system and a method with which the nitrogen oxides can be utilized for the production of liquid or solid chemicals.

Claims

1-10. (canceled)

11. A method for the utilization of nitrogen oxides contained in the ambient air, comprising the adsorption of nitrogen oxides from the ambient air in a stationary adsorbent unit which contains an adsorbent material, removing the adsorbent material loaded with nitrogen oxides from the adsorbent unit, collecting and temporarily storing the adsorbent material loaded with nitrogen oxides at a collecting site, transferring the adsorbent material loaded with nitrogen oxides to a desorption module, desorption of adsorbed nitrogen oxides from the adsorbent material and conversion of the nitrogen oxides into liquid or solid nitrogenous compounds.

12. The method according to claim 11, wherein the adsorbent material comprises at least one zeolite.

13. The method according to claim 11, wherein the liquid or solid nitrogenous compounds comprise nitrates.

14. The method according to claim 13, wherein the nitrogen oxides in the reaction unit are first converted into nitrous acid and the nitrous acid is then converted into nitrates.

15. A system for the utilization of nitrogen oxides, comprising a stationary adsorbent unit which is adapted for the adsorption of nitrogen oxides from the ambient air, wherein the stationary adsorbent unit has a housing with at least one inflow and outflow opening in the housing wall, a filter module in the interior of the housing which is fluidly connected to the inlet and outlet opening so that an air channel is formed, and an air intake apparatus in order to draw air from the ambient air and to guide it through the filter module, and wherein the adsorbent unit contains an adsorbent material which is adapted to bind nitrogen oxides in an adsorptive manner, and the adsorbent unit is designed such that adsorbent material loaded with nitrogen oxides can be removed without destruction and replaced by unloaded adsorbent material, a collection site for the temporary storage of adsorbent material loaded with nitrogen oxides, a desorption module which is adapted to heat adsorbent material loaded with nitrogen oxides, optionally under reduced pressure, or to treat it with hot water vapor, hot gas or a liquid solvent and thus desorb nitrogen oxides from the adsorbent material, and a reaction unit which is adapted to convert the desorbed nitrogen oxides into liquid or solid nitrogenous compounds.

16. The system according to claim 15, wherein the adsorbent material comprises at least one zeolite.

17. The system according to claim 15, wherein the adsorbent unit comprises at least one replacement cartridge with adsorbent material.

18. The system according to claim 17, wherein the replacement cartridge comprises 300 to 400 kg of adsorbent material.

19. The system according to claim 15, wherein the adsorbent unit is designed for a nominal air flow of 10,000 to 30,000 m.sup.3/h.

20. The method according to claim 12, wherein the liquid or solid nitrogenous compounds comprise nitrates.

21. The system according to claim 16, wherein the adsorbent unit comprises at least one replacement cartridge with adsorbent material.

22. The system according to claim 16, wherein the adsorbent unit is designed for a nominal air flow of 10,000 to 30,000 m.sup.3/h.

23. The system according to claim 17, wherein the adsorbent unit is designed for a nominal air flow of 10,000 to 30,000 m.sup.3/h.

24. The system according to claim 18, wherein the adsorbent unit is designed for a nominal air flow of 10,000 to 30,000 m.sup.3/h.

Description

[0036] The invention will be illustrated below by means of an example embodiment and will be further described with reference to the example and the accompanying drawing. The following is shown:

[0037] FIG. 1 a schematic representation of an embodiment of the system of the invention for the utilization of nitrogen oxides;

[0038] FIG. 2a a frontal view of an embodiment of an absorbent unit in a schematic representation;

[0039] FIG. 2b a frontal view of another embodiment of an absorbent unit in a schematic representation;

[0040] FIG. 2c a longitudinal section of the adsorbent unit shown in FIG. 2a) in a schematic representation;

[0041] FIG. 3 schematic representations of a tunnel with road traffic without (left) and with (right) an embodiment of an adsorbent unit of the system of the invention.

[0042] FIG. 1 schematically shows an embodiment of the system 10 of the invention for the utilization of nitrogen oxides. An air flow 11 containing nitrogen oxides is guided through a stationary adsorbent unit 20 which is adapted for the adsorption of nitrogen oxides (NO.sub.x) from the air flow 11, for example in a replacement cartridge containing an adsorbent material.

[0043] During the operation of the adsorbent unit 20, NO.sub.x is adsorbed in the adsorbent unit 20. The adsorbent unit 20 is thus charged with NO.sub.x and can receive NO.sub.x up to the acceptance limit of the adsorbent unit.

[0044] The adsorbent material in the adsorbent unit 20 is exchanged upon reaching the acceptance limit at the latest, i.e. when the adsorbent material is fully saturated with NO.sub.x. Either a filter module of the adsorbent unit 20 is exchanged as a whole or the adsorbent material in the adsorbent unit 20 is replaced by new, unloaded material. The filter modules of the adsorbent unit 20 are therefore preferably designed as a replacement cartridge or allow the removal of the loaded adsorbent material and the replacement of the loaded material by unloaded adsorbent material without much mounting effort and in particular without destroying the adsorbent unit 20.

[0045] The material loaded with NO.sub.x can be collected at a collection site and temporarily stored in order to have larger amounts of the loaded material available for the next step and thus make the utilization step more efficient.

[0046] Filter modules of the adsorbent unit 20 or the loaded adsorbent material contained therein are then transferred to a desorption module 30. In the desorption module 30, the adsorbed nitrogen oxides are desorbed. In one variant the adsorbent material loaded with NO.sub.x is either treated with heat, hot vapor, hot gas or a liquid solvent (e.g. water). The NO.sub.x goes into the vapor or liquid phase, the adsorbent material remains unchanged. If necessary, the adsorbent material must be dried before reuse. During desorption and during drying moderate temperatures of not more than 200° C. should be used. The separated NO.sub.x is supplied to a reaction unit 40 for further conversion.

[0047] In the reaction unit 40, the desorbed nitrogen oxides are converted into liquid or solid nitrogenous compounds 41. For example, the NO.sub.x can be introduced into the production chain of nitrous acid, nitrates or non-aqueous solvents based on NO.sub.2.

[0048] In one variant the nitrogen oxides NO.sub.x in the reaction unit 40 are first converted into nitrous acid HNO.sub.3. The nitrous acid is then converted into nitrates which are for example used as a nitrogen fertilizer.

[0049] FIG. 2a schematically shows a frontal view of an embodiment of an adsorbent unit 20. The adsorbent unit 20 comprises a housing 21 on whose inflow opening an air intake apparatus, e.g. a blower 22, is arranged, which is configured to guide an air flow through the housing 21. Fixation elements 23 allow the stationary mounting of the adsorbent unit 20.

[0050] FIG. 2b schematically shows a frontal view of another embodiment of an adsorbent unit 20. The represented adsorbent unit 20 comprises several modules which each have a blower 22. In one embodiment each module has its own housing 21 and adjacent housings 21 are connected to one another by suitable means, e.g. screwed or welded together. In another embodiment all modules are mounted in a common housing 21 which has a plurality of compartments for individual modules.

[0051] FIG. 2c shows a longitudinal section of the adsorbent unit 20 shown in FIG. 2a) in a schematic representation. A granular adsorbent material 24 is arranged in the housing 21. The blower 22 guides an air flow 11 containing nitrogen oxides through the housing 21 with the adsorbent material 24. The adsorbent material 24 adsorbs nitrogen oxides from the air flow 11 and an air flow 12 depleted of nitrogen oxides exits the housing.

[0052] FIG. 3 schematically shows, on its left side, a tunnel 50 with road traffic. The emissions of nitrogen oxides of the vehicles are symbolized by NO.sub.x clouds. On the right side, a tunnel 50 with an embodiment of an adsorbent unit 20 of the system of the invention is schematically represented. The adsorbent unit 20 is mounted on the tunnel ceiling with fixation elements 23. The blower 22 draws an air flow 11 loaded with nitrogen oxides from the vehicle emissions through the adsorbent unit 20.

[0053] The legal limit value for the concentration of nitrogen oxides in the air currently is 40 μg/m.sup.3.

[0054] In a tunnel, concentrations of up to 1 mg/m.sup.3 (1000 μg/m.sup.3) can be reached in case of heavy traffic. With an air volume in the tunnel of for example 150,000 m.sup.3, 1 ppm NO.sub.x (1 mg/m.sup.3) corresponds to about 150 g NO.sub.x which can be removed from the air by the adsorbent unit 20. In an example embodiment the blower 22 of the adsorbent unit 20 has a fan power of 4 kW and the adsorbent unit 20 is designed for a nominal air flow of 20,000 m.sup.3/h. The adsorbent unit 20 contains a cartridge with 400 kg of adsorbent material 24. Within a period of about 8 h, an amount of air which corresponds to the total air volume in the tunnel is guided through the adsorbent unit 20 and the nitrogen oxide contained in the air flow 11 is adsorbed in the adsorbent material 24. Thus, about 450-500 g of NO.sub.x can be achieved per day. The adsorption limit of the cartridge is reached after about one month, by then the adsorbent material 24 has accepted about 15 kg of NO.sub.x. The cartridge is then replaced and the adsorbed nitrogen oxides are recovered.

REFERENCE NUMERAL LIST

[0055] 10 system

[0056] 11 air flow containing nitrogen oxides

[0057] 12 air flow depleted of nitrogen oxides

[0058] 20 adsorbent unit

[0059] 21 housing

[0060] 22 air intake apparatus/blower

[0061] 23 fixation element

[0062] 24 adsorbent material

[0063] 30 desorption module

[0064] 40 reaction unit

[0065] 41 reaction product (liquid or solid compounds containing nitrogen oxides)

[0066] 50 tunnel