Chemistry of inorganic compounds – Modifying or removing component of normally gaseous mixture – Organic component
Patent
1994-09-02
1996-11-05
Langel, Wayne
Chemistry of inorganic compounds
Modifying or removing component of normally gaseous mixture
Organic component
422171, 422180, B01J 800, B01J 802
Patent
active
055714919
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention related to a method of purifying gases which are polluted by hydrocarbons and the like. The invention also relates to an apparatus which is usable for carrying out the method.
2. Description of the Prior Art
Authorities and the public have lately strongly increased the demands for a reduction of outlets of substances polluting the environment. Such substances can be hydrocarbons in solvents which are admixed to the ventilation air from an industrial plant.
There is today in the market an apparatus for purifying gases, for instance ventilation air having an admixture of hydrocarbons, the purification being made by catalytic combustion so that the hydrocarbons damaging for the environment are transformed to carbon dioxide and water. This apparatus comprises two reactors, each of which having a catalyst bed and a ceramic bed. The combustion reaction is exothermic, i.e. it emits heat. If the concentration of pollutions, i.e. in this case the content of hydrocarbons, is high enough, the combustion process becomes self-supporting, which means that no external energy needs to be supplied.
Heat emitted during the combustion reaction increases as the content of pollutions increases in the gas that shall be purified. This means that the temperature in the purification apparatus can be so high that the material is damaged. Owing to that the apparatus known in the market has limitations regarding the possibility to manage purification of gases having high contents of pollutions.
According to known technique there has been an attempt to solve this problem by making possible to take out gas to atmosphere at an area between the two reactors (see for instance EP-337 143). In order that this shall be acceptable from an environmental point of view, however, such a channel going out to the atmosphere has to be provided with a separate catalyst. This solution is of course both complicated and expensive.
This invention intends to offer a solution of the problem of purifying gases having high contents of pollutions, which solution is uncomplicated, relatively spoken, and attractive from an expenditural point of view. This has been made possible by a method of the kind mentioned by way of introduction, which is characterized by the moments mentioned in the claims.
SUMMARY OF THE INVENTION
This invention relates to a method of and apparatus for purifying gases which are polluted by hydrocarbons and the like. The apparatus has two reactors, each reactor comprising a catalyst bed, a ceramic bed and a border layer lying between the two beds. According to the invention, the gas that shall be purified is forced to stream alternately through the first reactor and the second reactor (clock-wise streaming) and the second reactor and the first reactor, respectively (counter clock-wise streaming). The gas is purified when the hydrocarbons in the gas are oxidized to carbon dioxide and water in the catalyst beds. The temperature of the gas streaming through the upper portion of the reactors is measured and when the temperature exceeds a certain level, a portion of the gas is taken out from the apparatus during the passage over the border layer of the second reactor if the gas is streaming in a clock-wise direction, and a portion of the gas is taken out from the apparatus during the passage over the border layer of the first reactor if the gas is streaming in a counter clock-wise direction.
A preferred embodiment of an apparatus according to the invention, useable for carrying out the method shall be described more closely below with reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a schematic of the dual reactor embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawing is shown there the new apparatus. This one comprises two reactors 1, 2 which are placed at a distance from each other and are preferably cylindrical. The two reactors 1, 2, which are preferably vertically arranged, are at their upper por
REFERENCES:
patent: 2946651 (1960-07-01), Houdry
patent: 3361531 (1968-01-01), Erb et al.
patent: 3870474 (1975-03-01), Houston
Langel Wayne
MoDo-Chemetics AB
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