Ciba-geigy Corporation

Jurg Schneider

Volker Fattinger

A gas scrubbing tower is described which has a top region, a sump region and at least two washing stages between these regions. The tower comprises gas entry means between the the sump region and the lowermost of the washing stages; gas exit means in the top region; a first washing stage, in the direction of gas flow through the tower, constituted by a layer of packing elements resting on supporting means in a cross-sectional plane; a first circulating line for wash liquid from the sump region to the layer of packing elements; a second, packing-free washing stage above the first washing stage; a second circulating line for conducting wash liquid through the second washing stage; a sludge separator, and conduit means for introducing water from outside the tower into a washing stage or into the sludge separator of the tower. A process for operating the scrubbing tower is also described.

Gas scrubbing tower

A process for purifying the off-gases from industrial furnaces and especially from waste incineration plants is described in which process the off-gases which contain acid, neutral and/or basic pollutants in the gaseous or solid form or in the form of a mist, are treated in an evaporative cooler and then in a dry purifier, in which they are freed from at least a substantial portion of the solid pollutants, and finally in a scrubber by means of a wash liquid. The temperature of the off-gases in the evaporative cooler is kept above the dew point, and the wash liquid in the scrubber is cycled through a slurry separator, from which suspension or solution of pollutants is withdrawn from the sludge separator and fed into the evaporative cooler and mixed in a mixing space in the latter with the hot off-gases. Those walls of the evaporative cooler which come into contact with the mixture of off-gases and recycled suspension or solution of pollutants and which consist of a material that can be corroded by the said mixture at room temperature are heated from the outside to a temperature above the dew point. As a rule the pH value of the liquid phase in the sludge separator and in each of the gas wash stages of the scrubber directly upstream of the said separator is kept below 4.

Process for purifying the off-gases from industrial furnaces, especially

A gas scrubbing plant having a gas scrubbing stage, a washing liquid separating stage and a stage for washing out suspended matter therebetween. This latter stage includes a plurality of gas baffles which accelerates the gas and then decelerates it while liquid is introduced into the gas baffles as the gas passes therethrough. Each baffle has an inner conical member surrounded by an outer member to define therebetween an annular passage with diverges at an angle of between 10.degree. and 90.degree. from the inlet adjacent the apex of the conical member to the outlet from the baffle, the cross-sectional area of the annular passage decreasing in the direction of gas flow and then increasing towards the outlet. A liquid feed tube is mounted in the conical member and a disc mounted at the outlet of the tube opposite the apex to the conical member so that the liquid fed into the tube is deflected and produces a rotationally symmetrical jet up into the annular passage in the direction of gas flow from the inlet to the outlet.

Gas scrubbing plant and baffles therefor

Apparatus for the wet purification of gases, in which a wash liquid is sprayed into a gas to be purified and the gas is then forced or drawn through a separating wall having passage slots. The gas flow is divided up by pairs of such slots into pairs of sub-flows inside the wall, the sub-flows of each pair being rapidly accelerated to at least 30 m per second and then made to rebound on one another in a zone which is common to a pair of slots which causes them to be sharply deflected after which they separate and are decelerated. The sub-flows are accelerated by the passage slot construction which narrows inwardly from the exterior of the wall. Preferably two pairs of slots are provided, one pair converging into the wall and another pair diverging from the wall, both pairs opening into the common zone which is in the form of an X, the narrowest points of the slots being in said zone. The total area of the zones relative to the area of the wall is at maximum 15%. The separating wall is constructed from individual profiled bars which are spaced apart to form the passage slots between them. The wall preferably consists of at least two sub-walls which are interconnected by a hinge.

Apparatus for the wet purification of gases

A drop trap for a gas scrubbing plant, the trap having a plurality of parallel spaced apart corrugated plates forming channels through which gas flows and baffles at the downstream side of the corrugated plates to impart a downward velocity to liquid particles entrained in the gas flowing through the channels. Further baffles may be located at the upstream side of the corrugated plates to deflect the liquid particles downwardly to flow over the corrugated plates as they are separated from the gas as it passes through the channels. A method is also disclosed of rinsing the corrugated plates by intermittently spraying a predetermined quantity of liquid over the upstream side of the plates.

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Muttenz, Switzerland

Jurg Schneider