Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1994-10-06
1996-07-30
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60286, F01N 320
Patent
active
055400477
ABSTRACT:
The method reduces the nitrogen oxide concentration in the exhaust of an internal combustion engine. A noticeable reduction in the NO.sub.x emission of a diesel motor can be achieved by applying the Selective Catalytic Reduction (SCR) method. In this method, ammonia is injected into a catalyzer through which the exhaust gas flows, this ammonia reacting with nitrogen monoxide or, respectively, nitrogen dioxide to form nitrogen and water. Since the exhaust gas should contain neither nitrogen monoxide nor excess ammonia, suitable methods are required for regulating the metering of NH.sub.3. For controlling the amount of urea added to the exhaust gas as a reduction agent, the NO and NH.sub.3 concentration is measured using a detector located in the exhaust systems following the SCR catalyzer. The detector contains a vanadate layer manufactured on the basis of a specific sputtering method as a sensitive element. The electrical resistance thereof is highest when the conversion of nitrogen monoxide to form nitrogen and water occurs stoichiometrically.
REFERENCES:
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patent: 5357749 (1994-10-01), Ohsuga
patent: 5367875 (1994-11-01), Aboujaoude
patent: 5369956 (1994-12-01), Daudel
patent: 5410873 (1995-05-01), Tashiro
"Verhalten von SCR-Katalysatoren im dieselmotorischen Abgas", Dr.-Ing. Gerhard Lepperhoff and Dr.-Ing. Joachim Schommers, Motortechnische Zeitschrift 49 (1988) pp. 17-21.
"Untersuchung der NO.sub.x -Reduzierung im Abgas von Dieselmotoren durch SCR-Katalysatoren", Dr-Ing. Gerhard Lepperhoff and Dr.-Ing. Georg Huethwohl, Motortechnische Zeitschrift 54 (1992) p. 310-315.
"Moeglichkeiten der Stickstoffoxidminderung Durch SCR-Anlagen", J. Becker, Grummersbach, Fachreport Rauchgasreinigung, Umwelt, 1986, No. 1, pp. 19-25.
"Sensors and Actuators", Letter to the Editors, Elsevier Sequoia/Printed in The Netherlands, (1989) pp. 259-265.
Sensors and Actuators, vol. 19, No. 3, Sep. 1989, Tatsumi Ishihara et al, "The Mixed Oxide Al.sub.2 O.sub.3 -V.sub.2 O.sub.5 as a Semiconductor Gas Sensor for NO and NO.sub.2 ", pp. 259-265.
Dahlheim Christian
Fleischer Maximilian
Meixner Hans
Hart Douglas
Siemens Aktiengesellschaft
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