A method for the removal of nitrogen oxides contained in exhaust gases of an optionally fluctuating composition with a temperature of 0°-600° C. by means of catalytic reduction at a preselected stoichiometric ratio between the concentration of reducing agent and the concentration of nitrogen oxide in which the reducing agent is dosed in a pulsed manner.

Method for the catalytic removal of nitrogen oxides from exhaust gases by means of a reducing agent

A reductant injection control strategy for controlling an amount of nitrogen oxide reducing agent injected upstream of a selective reduction catalyst uses a NOx sensor located downstream of the catalyst. An open loop injection quantity is first determined based on operation conditions. Nitrogen oxide conversion efficiency of the catalyst is controlled by controlling the reductant injection based on after catalyst NOx sensor reading and engine out nitrogen oxide concentration.

Emission control system

Process for selective catalytic reduction of exhaust gases from motor vehicle diesel engines with timed addition of NH3 or NH3-releasing substances, the timed superstoichiometric NH3 addition being controlled in such a manner that the addition, after its start, is only terminated when, at a defined site in the catalyst bed, a high NH3 concentration, which is established as a threshold value, is obtained in the gas phase and is only started again when the NH3 stored in the catalyst has been substantially consumed by the reaction, this time point being determined by calculation by approximation of the NOx, produced by the engine over the period since the beginning of metering or alternatively from the end of metering, from the engine characteristics and operating time and taking into account the average separation efficiency.

Process for selective catalytic reduction of exhaust gases from Diesel engines

Regenerative selective catalytic reduction (RSCR) systems and processes are provided whereby NO, and CO levels in gases are reduced by mixing the gas with a reactant and then introducing the gas into an RSCR apparatus for treatment that entails heating the gas, causing the gas to undergo one or more catalytic reactions, and then directing the gas through a heat transfer area, to which the gas provides heat for use in connection with successive cycles of the RSCR process.

Systems and methods for removing materials from flue gas via regenerative selective catalytic reduction

A method for controlling reductant injection into an exhaust stream upstream of a catalyst coupled to an internal combustion engine is disclosed. In the method, an ammonia sensor located downstream of the exhaust catalyst is used to determine ammonia concentration in the exhaust stream. The ammonia concentration is compared to an allowable threshold and an allowable fraction, i.e., a maximum limit on a fraction of ammonia in the exhaust stream compared with the ammonia supplied by the reductant injector. Additionally, based on a NOx sensor, it is determined whether NOx conversion of the catalyst has increased in response to an increase in reductant injection. If not, reductant injection quantity is reduced.

Method for adjusting a reductant used in an internal combustion engine to reduce NOx

A flue gas stream having passed a flue gas desulfurization plant 2 enters a reactor 6 flowing through an activated carbon bed. The flue gas entering the reactor continuously is discontinuously blended with ammonia, thereby achieving a low ammonia content of the flue gas leaving the reactor, while maintaining a high efficiency of nitrogen oxide removal. The duration of ammonia addition and the rate of flow at which ammonia is added to the flue gas stream are controlled as a function of the desired efficiency of nitrogen oxide removal and the ammonia concentration measured in the reactor.

Method of removing oxides of nitrogen from flue gas

Verfahren zum Abscheiden von Stickstoffoxiden aus Rauchgasen

Ein Rauchgasstrom wird nach Durchlauf einer Rauchgasentschwefelungsanlage (2) durch ein Aktivkoksbett in einen Reaktor (6) geleitet A flue gas stream is passed after passing through a flue gas desulphurisation plant (2) by a Aktivkoksbett in a reactor (6) Dem kontinuierlich in den Reaktor eintretenden Rauchgasstrom wird Ammoniak diskontinuierlich in periodischen Intervallen zudosiert, wodurch bei hohen NO x -Abscheidegraden niedrige NHs-Konzentrationen im Rauchgas hinter dem Reaktor erreicht werden The continuously entering the reactor flue gas flow is metered discontinuously at periodic intervals, whereby low NHS concentrations in the flue gas downstream of the reactor can be achieved at high NO x -Abscheidegraden ammonia Die Lange der NH 3 -Zugabeintervalle und die NH 3 -Mengenvaria- tionen werden nach dem Sollwert des NOx-Abscheidegrades und nach der im Reaktor gemessenen NHs-Konzentration geregelt The length of the NH 3 and the NH 3 -Zugabeintervalle -Mengenvaria- functions are controlled according to the target value of the NOx separation efficiency and after measured in the reactor NHS concentration

Helmut Ing. Grad. Weiler

Papers

Method of removing oxides of nitrogen from flue gas

Verfahren zum Abscheiden von Stickstoffoxiden aus Rauchgasen

Process for removing nitrogen oxides from flue gas