The present invention relates to processes employing water produced from wells that, after suitable purification steps, is processed to recover resources that can be used to treat other waste streams, such as flue gases and ashes from combustion of fossil fuels.

An exhaust gas cleaning system, comprising an active regenerable particulate filter and an SCR catalyst comprising a hydrothermally microporous stable zeolite having the AEI type framework and being promoted with copper, where the zeolite is SSZ-39.

Zeolite catalysts and systems and methods for preparing and using zeolite catalysts having the CHA crystal structure are disclosed. The catalysts can be used to remove nitrogen oxides from a gaseous medium across a broad temperature range and exhibit hydrothermal stable at high reaction temperatures. The zeolite catalysts include a zeolite carrier having a silica to alumina ratio from about 15:1 to about 256:1 and a copper to alumina ratio from about 0.25:1 to about 1:1.

The present invention pertains to new methods for generating energy and useful nitrogen compounds from captured carbon dioxide. It involves employing an osmotic engine, draw solution, and feed solution. An osmotic gradient between the solutions assists in generating energy and a solution of ammonium carbonate, ammonium bicarbonate or mixture thereof. This solution may be decomposed to form ammonia, carbon dioxide, a precipitate, or a mixture thereof.

A flue gas stream arising from fossil fuel fired sources containing nitrogen oxide contaminants is conveyed through an exhaust duct into a quencher. In the quencher aqueous medium is sprayed into contact with the flue gas stream. The quenched flue gas stream is mixed with ozone distributed at a high velocity in a sub-stoichiometric amount for partial oxidation of NO.sub.xto form NO.sub.2 and prevent the formation of N.sub.2O.sub.5. The flue gas containing NO.sub.2 is absorbed into an acidic medium of a wet scrubber to form nitrous acid. In the scrubber the nitrous acid is mixed with selected compounds of ammonia to decompose the nitrous acid for release of nitrogen. With this process the consumption of ozone and the operating costs associated therewith eliminate the requirement to dispose of nitrate recovered from the scrubber purge stream.

A method of reducing the concentration of NO.sub.x nitrogen oxides in tail gas obtained during the startup of a plant for preparation of nitric acid may involve heating the tail gas as a result of measures for preparation of nitric acid from a starting temperature T.sub.0, through a threshold temperature T.sub.G, and to an operating temperature T.sub.B at which steady-state operation of the plant can be effected (T.sub.0<T.sub.G<T.sub.B). The method may comprise passing the NO.sub.x-containing tail gas through a storage medium for NO.sub.x and storing at least a portion of the NO.sub.x in the storage medium for NO.sub.x while the temperature of the tail gas is lower than the threshold temperature T.sub.G. In some cases, the NO.sub.x stored in step may be released, preferably when the temperature of the tail gas has attained the threshold temperature T.sub.G. The method may further comprise combining the NO.sub.x with a reducing agent for NO.sub.x in the presence of an SCR catalyst after the temperature of the tail gas has exceeded the threshold temperature T.sub.G, but not before, which results in catalytic reduction of at least a portion of the NOR, preferably to N.sub.2.

A wet scrubber (10) useful for cleaning a process gas (F) comprising at least a first spray level system (40) and a second spray level system (48) arranged compactly vertically above the first spray level system (40) in a wet scrubber tower (14). Each spray level system (40, 48) is equipped with a plurality of atomizing flattened relatively wide spray angle nozzles (56) for atomizing an absorption liquid (AL) supplied thereto for contact and intermixing with the process gas (F) for removal of environmental pollutants therefrom.

A flue gas stream arising from fossil fuel fired sources containing nitrogen oxide contaminants is conveyed through an exhaust duct into a quencher. In the quencher aqueous medium is sprayed into contact with the flue gas stream. The quenched flue gas stream is mixed with ozone distributed at a high velocity in a sub-stoichiometric amount for partial oxidation of NO.sub.xto form NO.sub.2 and prevent the formation of N.sub.2O.sub.5. The flue gas containing NO.sub.2 is absorbed into an acidic medium of a wet scrubber to form nitrous acid. In the scrubber the nitrous acid is mixed with selected compounds of ammonia to decompose the nitrous acid for release of nitrogen. With this process the consumption of ozone and the operating costs associated therewith eliminate the requirement to dispose of nitrate recovered from the scrubber purge stream.

An assembly (10) for introducing a reducing agent into the exhaust pipe (12) of an exhaust system of an internal combustion engine, in particular of a motor vehicle, has a feed connector (14) which opens into the exhaust pipe (12) and includes a wall (16), a feed device (20) for reducing agents which opens into the feed connector (14), and a device (22) for generating a gas flow (G) which is additional to the reducing agent flow (R) and lines the wall (16) of the feed 10 connector (14). Furthermore, there is described a method of introducing a reducing agent into the exhaust pipe (12) of an exhaust system of an internal combustion engine, in particular of a motor vehicle.

An assembly (10) for introducing a reducing agent into the exhaust pipe (12) of an exhaust system of an internal combustion engine, in particular of a motor vehicle, has a feed connector (14) which opens into the exhaust pipe (12) and includes a wall (16), a feed device (20) for reducing agents which opens into the feed connector (14), and a device (22) for generating a gas flow (G) which is additional to the reducing agent flow (R) and lines the wall (16) of the feed 10 connector (14). Furthermore, there is described a method of introducing a reducing agent into the exhaust pipe (12) of an exhaust system of an internal combustion engine, in particular of a motor vehicle.