Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Patent
1985-08-16
1987-07-07
Marcus, Michael S.
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
165 8, 422178, 422180, 422206, B01J 810
Patent
active
046786430
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method and apparatus for selectively eliminating the oxides of nitrogen in the exhaust gases of furnace systems by introducing chemical compounds into the exhaust gases emerging from the furnace system for reaction with the oxides of nitrogen and by then passing the exhaust gases through a catalytic converter in order to accelerate and/or initiate the reaction, as well as to an apparatus for performing the method.
To selectively reduce the oxides of nitrogen, it is already known to meter out ammonia (NH.sub.3) in vapor form, in a mixture with air and dissolved in water either with or without pressure, into the flow of exhaust gas emerging from the furnace system. By means of a blending section having appropriate fixtures, the object is to develop a uniform distribution of ammonia and a uniform temperature distribution inside the flue gas conduits attached thereto. The mixture is then passed through a catalytic converter connected to the inlet side of a rotary regenerative heat exchanger intended for transmitting the heat of the exhaust gas to the combustion air that is supplied to the furnace. The catalyst is embodied as a fixed-bed reactor, the flow of which is preferably directed vertically downward. A honeycomb structure with a vanadium compound as its catalytically active substance is contained in the reactor. The pressure loss of the fixed-bed reactor is taken into account when dimensioning the flue gas blower. The vertically downward flow in the reactor is intended to counteract solid contaminant deposits in the reactor, or to keep such deposits within limits. The deposits that do occur are intermittently removed by blowing, using compressed air or steam. Depending on the boiler, the mode of operation, and the composition of the coal that is used for fuel, the catalytic converters inside the reactor have a service life of over two years.
Based on the recognition that the conversion of the oxides of nitrogen, which occur in proportions of approximately 95% nitrogen monoxide and approximately 5% nitrogen dioxide, into molecular nitrogen and water does not depend solely upon the ratio of the quantity of ammonia that is introduced to the content of nitrogen oxide in the exhaust gases and upon the temperature level of the exhaust gases, but instead is substantially affected by the efficiency of the catalytic converter as well, it is the object of the invention to devise a method and an apparatus for selectively eliminating the oxides of nitrogen in furnace exhaust gases using a catalytic converter, in which the catalytic properties of the catalyst elements used are maintained over relatively long periods of operation.
SUMMARY OF THE INVENTION
With a method of the general type described at the outset above as the point of departure, this object is attained in accordance with the invention in that the catalytic converter experiences, in different zones, a flow of the exhaust gases that are to be catalytically treated and a flow of at least one cleaning gas, the latter preferably in countercurrent, and that the location of the catalyst segments through which the exhaust gases and the cleaning gas, respectively, flow is varied continuously or intermittently. Because the cleaning gas flow is continuously effective, the contaminants that settle out of the exhaust gas flow onto the surfaces of the catalyst element, especially in the vicinity of its inlet, and are carried along by the flow of the exhaust gas are removed from these surfaces again continuously; as a result, the efficiency of the catalytic converter remains unimpaired over substantially longer travel periods. A method in which the cleaning gas flow is moved in countercurrent to the exhaust gas entering the catalytic converter is particularly effective. The efficiency of the catalytic compound is apparently maintained because of the fact that poisoning of the catalysts depends directly on the length of time the contaminant is in contact with the catalyst elements, and that the proposed contin
REFERENCES:
patent: 3362783 (1968-01-01), Leak
patent: 3607133 (1971-09-01), Hirao
patent: 3755534 (1973-08-01), Graham
patent: 3780498 (1973-12-01), Wenner
patent: 3997294 (1976-12-01), Kritzler
patent: 4003979 (1977-01-01), Kanno
patent: 4039478 (1977-08-01), Cull et al.
patent: 4129176 (1978-12-01), Heyn et al.
Marcus Michael S.
Svenska Rotor Maskiner Aktiebolag
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