Liquid purification or separation – With gas-liquid surface contact means
Patent
1987-02-04
1988-05-10
Miles, Tim
Liquid purification or separation
With gas-liquid surface contact means
55234, 2102421, 261 35, 261 81, 261120, 261 641, B01F 304
Patent
active
047433671
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a fundamental problem in many processes of a biological, chemical and physical nature, namely how to arrange a contact/reaction surface between a gas and a liquid to optimize process efficiency between the two media versus cost of running and maintenance.
As examples of such biological processes can be mentioned aerobic bacteria processes such as nitrification or fermentation, where a contact surface exposed to water, nutrients and exchange of oxygen and carbon dioxide, acts as a carrier of active bacteria films.
Another biological/chemical process can involve treatment of straw in aerobic conditions, either by chemical means or by means of bacteria. In this example the straw material in itself constitutes the contact surface.
Physical processes may include heat and vapour exchange between a gas flow and open liquid films, distributed over a contact surface, processes such as heat exchange, evaporation, condensation or diffusion.
Another example of physical nature is the scrubbing of a gas flow from solids by close contact with a wetted surface.
In most applications the contact surface material is inert and acts primarily as means for spreading a liquid flow to thin liquid films, exposed to a gas flow. Obviously, the main technical object is in the best manner possible, costwise and maintenancewise, to provide large surface areas and a high quality of wetting and flow conditions.
Well known are the following types of contact apparatus, grouped according to working technique: through the contact body. contact body. in a gas.
All these techniques are characterized by continous flows of one or both media. For groups "A" and "B" this fact results in the establishment of stable, stratified media flows, which furthermore tend to collect in certain preferred flowpaths, thus twofold offsetting process efficiency. For group "A", preferred for large scale operations, the pumping and uniform sprinkling of liquid can also be problematic, especially for contaminated or highly viscous liquids.
For group "C" stable, stratified liquid flows are avoided by the inherent, intermediate dipping action of the contact body in the liquid bath, resulting in excellant wetting and transfer conditions. A drawback of this type of contact apparatus is a high mechanical load on the contact body and a corresponding high cost. Therefore it is limited in use to small scale operations.
The present invention relates to a contact apparatus comprising a contact body of spaced surface material, means for wetting said body with a liquid and means for exposure of the wetted body to a gas.
The object of the invention is to provide a contact apparatus, which can operate in a wide span of both scale and mode of operations and which offers many improved qualities in efficiency, reliability and cost, as listed below:
Excellent heat/mass transfer due to unstable, unstratified flow conditions.
Complete, uniform wetting of the contact body, even for contaminated or highly viscous liquids.
Straight, vertical flowpaths in the contact body at a minimum of flow resistance.
A very high ratio between contact body surface and contact body volume can be used, without offsetting wetting properties or inducing prohibitable flow resistance.
Extremely large amounts of liquid are periodically exposed as liquid films with very small mechanical efforts and power requirements.
Simple, reliable mechanics, operated solely by low pressure pneumatic means.
The above listed objects and other objects mentioned below may be obtained by a contact apparatus of the type referred to above, which according to the invention is characterized in that said apparatus also comprises an open bath of said liquid, chambers partly immersed in said bath, said chambers enclosing said contact body, chamber openings for liquid communication between said bath and a free space of said chambers and said body and a driving device for cyclically forced injection respectively ejection of gas to and from said free space through gas conduits.
The mechanical system can ac
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Brown Laurence R.
Mangels Alfred J.
Miles Tim
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