Gas separation – Means within gas stream for conducting concentrate to collector
Patent
1986-08-19
1988-03-29
Nozick, Bernard
Gas separation
Means within gas stream for conducting concentrate to collector
55 98, 55269, 55512, 55 90, 55233, 55487, 435262, 435264, 435266, B01D 4600
Patent
active
047341114
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a process and an apparatus for cleaning or purifying spent or exhaust air, which is polluted with vapours, such as solvent vapours and especially those of styrene, methylene chloride, etc. occurring during plastic processing.
Polluted spent air, such as in the form of a mixture of monostyrene and/or methylene chloride and air e.g. occurs during the production and processing of glass fibre-reinforced plastics based on unsaturated polyester resins. The spent air is distributed in the working areas and must be removed by suction and cleaned.
It is known to clean styrene-polluted spent air by the physical absorption of the styrene, specifically on active carbon filters. The spent active carbon is e.g. regenerated by means of water vapour, the styrene being chemically separated therefrom. This known spent air cleaning process and the necessary apparatus are expensive. Firstly the material costs of the active carbon are relatively high and secondly it is frequently necessary to regenerate the active carbon, which is costly to carry out, particularly due to the necessary water vapour, its production and process control requiring the use of special equipment. In another styrene-polluted spent air cleaning process, the styrene is oxidized, but this process is particularly complicated and therefore very expensive.
During the production of oil or fat in animal carcass elimination plants, it is known to remove odours by reducing the natural odorous substances formed through biological filters of compost or the like.
The problem of the present invention is to provide a process and an apparatus of the aforementioned type, which uses a simple process and apparatus, thereby permitting less expensive cleaning of spent air polluted with chemical solvents.
According to the invention, this problem is solved in that the spent air is removed by suction and humidified and is then passed through a filter of bark having microorganisms, the filter being subject to an artificial temperature control. It has surprisingly been found that the solvents are cleaned by such a filter in such a way that they are decomposed and reduced therein by bacteria and also fungal culture. It has in fact been found that the filter mass contains substantially no decomposed solvents and the like. Admittedly biofilters with refuse compost or fibrous peat - brushwood mixtures are known per se. However, they are used for avoiding smells, particularly in connection with factory farming and animal body utilization plants, as well as in refuse compost plants. The known equipment are constructed in the manner of a settler. The result achieved by the invention could not have been expected in the case of the known filtering of natural odours by such filters.
It is advantageous that the filter is less expensive than the active carbon filters hitherto used for physical absorption purposes and that the biofilter also at least partly decomposes the sorbed system under the action of the microorganisms present on the filter, so that is is much less rapidly consumed giving high retention times. Regeneration by simple aeration is possible. Thus, the costs for regeneration with water vapour are obviated. When the inexpensive filter has become used up, it is merely replaced by a new one. The spent filter can then be removed as refuse in a conventional manner.
The process according to the invention can be performed in a relatively simple apparatus having a flow-through container, in which the filter is positioned in such a way that the spent air to be cleaned flows through it. A fan is provided for the forced delivery of the spent air, whilst a sprinkler for humidifying the spent air is positioned between fan and filter. The filter has bark provided with microorganisms and a heater is provided for the temperature control of the filter. There are no means for the production and process control of water vapour.
In preferred constructions of the inventive process, spruce bark is used as the filter. A very high cleaning action is obtained with this part
REFERENCES:
patent: 2200581 (1940-05-01), Pruss et al.
patent: 3216905 (1965-11-01), Baptist
patent: 4045192 (1977-08-01), Eckstein
patent: 4225381 (1980-09-01), Ishikawa et al.
Valten-Treatment of Problematic Waste Water, 1979, 35(2), pp. 138-142.
Hanisch Gunter
Hoffmann Rainer
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