Catalytic device with internal heat exchange

Abstract

The invention relates to a catalytic device with internal heat exchange that among other things can be used for vehicles with an internal combustion engine or for stationary engines where there is a certain amount of unburned gas components in the exhaust that can be converted in the catalyst. By the invention it is obtained that the maximum temperature in the catalyst is always nearly constant whatever the inlet temperature. Hereby, the catalyst can be designed to work at a very specific temperature, by which it is possible, partly to ensure a better and safer burnout of the unburned components, and partly to save expenses for catalyst materials. The exhaust gas is guided through the catalyst by at least three passage sections that have a mutual internal heat exchange. In the main reaction passage section there are catalytic materials of one or several kinds, in which the gas can react, and in which the gases heat exchange with the succeeding main heat transfer passage section passage.

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to a method for treatment of a fluid quantity including chemical reacting means such as combustible materials and a catalytic device according to the preamble of claim 5. [0002] Most of the known catalysts for cleaning of exhaust gasses from internal combustion engines contain no internal heat exchange. This means that the maximum temperature in the catalyst depends on the inlet temperature in said catalyst. If the unburned gas components by combustion e.g. can increase the temperature in the catalyst by 200° C. an inlet temperature of 300° C. will result in a maximum temperature of 500° C., an inlet temperature of 400° C. will result in a maximum temperature of 600° C., etc. However, an inlet temperature of 200° C. does not necessarily result in a maximum temperature of 400° C. as the temperature at that time is too low for the reactions to take place and the catalyst will be wholly or partly inactive. [0003] However, catalys...

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Benefits of technology

[0012] Further, by the invention is it obtained that the maximum temperature in the catalytic device is always nearly constant whatever the inlet temperature, but assuming a certain minimum inlet temperature and minimum amount of combustible material. Hereby, the catalytic device can be designed to work at a very specific temperature, as an example at 600° C., by which it is possible, partly to ensure a better and safer burnout of the unburned components, and partly to save expenses for catalytic materials as a catalyst that is designed for a certain temperature can be made from materials that are less expensive than the materials for a catalyst that has to work over a large temperature range.

[0062] The different aspects of the invention make the catalytic device and especially the heat exchange more efficient the slower the chemical reactions in the catalyst are, and vice versa. Therefore, the catalytic device will, by itself, set itself for the right temperature so that all reactions precisely can be completed in the catalytic device.

Problems solved by technology

However, an inlet temperature of 200° C. does not necessarily result in a maximum temperature of 400° C. as the temperature at that time is too low for the reactions to take place and the catalyst will be wholly or partly inactive.

However, the heat exchange is not enough to achieve satisfying and stabile temperature conditions inside the catalyst in the heating-up periods and thus, the catalyst comprises temperature regulating means in opposite ends of the container.

The means may for example be electric coils connected to an electric power supply positioned outside the catalyst with the disadvantage of the electric energy use.

Further, the connection for the electric coils is a significant disadvantage due to the price, complexity and vulnerability of the coils and the connections.

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