This invention relates to a wet gas scrubber for removing solid and/or liquid particles from gases with a Venturi zone adjustable with respect to the flow cross-section, comprising a plurality of Venturi channels through which a mixture of the gas to be cleaned and the cleaning liquid droplets injected into the gas stream through a nozzle is guided.

Various types of wet gas scrubbers for removing solid and/or liquid particles from gases are known, including those which utilize the so-called Venturi effect. The inlet gas stream to be cleaned here is utilized to decompose the cleaning liquid into extremely fine droplets which capture particle- and droplet-shaped impurities from the gas stream to be cleaned and can thus be discharged.

Simple Venturi gas scrubbers have a central throat region with constant cross- section, to the inlet side of which a cone narrowing in flow direction is adjoined and to the outlet side of which a cone expanding in flow direction is adjoined. Therefore, such gas scrubbers can only be used effectively over a not too large range of gas flow rates. For this reason, more expensive Venturi gas scrubbers have already been proposed, in which the cross-section of the throat region can be varied for different gas flow rates, in order to maintain the cleaning effect.

It is the object of the present invention to obtain an adjustable Venturi cleaning zone in a wet gas scrubber as mentioned above, in which a uniform gas velocity and consequently a uniform pressure drop is effected in a simple way, even if the flowing gas volume fluctuates, so that a uniform cleaning effect can always be achieved. In accordance with the invention, this object in particular is solved in such wet gas scrubber in that the Venturi channels are formed between two substantially parallel Venturi plates provided with segments preferably arranged in a star shape, which engage in each other while the Venturi channels are kept free. The vertical gas stream is deflected horizontally, wherein gas and liquid in the Venturi channels undergo a strong acceleration. This results in the generation of a large number of extremely fine droplets and an intensive, thorough mixing with the particles.

In accordance with a particularly preferred aspect of the invention, the Venturi plates can be adjusted in their distance relative to each other. In this way, a constantly high cleaning effect can be achieved even with greater fluctuations of the volumetric gas flow, because by relative adjustment of the coaxial Venturi plates the Venturi channel cross-sections can synchronously be adjusted and hence the total Venturi channel cross-section can be adjusted.

Advantageously, the adjustment of the Venturi Plates relative to each other preferably can be controlled automatically in dependence on the changing difference of the gas pressure before and after the Venturi zone, i.e. between inlet cone and outlet cone of the Venturi zone.

To direct the stream of the gas to be cleaned in a preferred direction, the Venturi channels formed between the Venturi plates extend substantially radially and are curved in the same direction in accordance with a particular embodiment of the invention. They are distributed over the Venturi plates in a star shape at the same angular intervals, in order to achieve a uniform flow pattern.

For a simple construction and easy handling of the wet gas scrubber of the invention the two Venturi plates advantageously lie one above the other, and preferably the lower Venturi plate is fixed and the upper Venturi plate is vertically adjustable.

In accordance with the invention, a reliable control of a uniform pressure drop in the Venturi zone can be achieved in that the one Venturi plate substantially has the negative shape of the second Venturi plate.

An even more complete cleaning of the gases with the wet gas scrubber of the invention can be achieved in that the gas leaving the Venturi zone enters a second cleaning zone constituting a cyclone with a spin, in which second cleaning zone the solid and/or liquid particles from the gas are captured by the injected cleaning liquid droplets, guided to the housing wall of the cyclone and discharged from the same for instance due to gravity.

For this purpose, the mixture of gas to be cleaned and cleaning liquid droplets is introduced into the Venturi zone preferably vertically from the top to the bottom, so that it can leave the Venturi zone horizontally into the cyclone. Carry-over of droplets into the cleaned gas stream is minimized.

The cleaned gas then can be guided out of the housing of the cyclone, which the captured solid and/or liquid particles leave in downward direction, through a central upper outlet.

The measure that the two cleaning zones are accommodated in one and the same housing serves for a compact protected construction of the wet gas scrubber.

Further developments, advantages and possible applications of the invention can be taken from the following description of an embodiment and the drawing. All features described and/or illustrated form the subject-matter of the invention per se or in any combination, also independent of their inclusion in individual claims or their back-reference.

In the drawing:

Fig. 1 schematically shows a vertical section through an embodiment of a wet gas scrubber including the invention,

Fig. 2 shows a partial section through a modified version of the wet gas scrubber as shown in Fig. 1 , and

Fig. 3A-D show the Venturi plates used for example in the wet gas scrubber in an enlarged representation as compared to Figures 1 and 2 in perspective, side and top views.

The wet gas scrubber shown in the drawing serves to remove solid and/or liquid particles from water-saturated gases with constantly high cleaning efficiency. An adjustable Venturi cleaning zone, formed by two horizontally arranged Venturi plates 5, 6 adjustable in their relative distance to each other, ensures the uni- form cleaning efficiency in that a uniform gas velocity and consequently a uniform pressure drop is achieved with a fluctuating gas volume.

The adjustable Venturi zone includes a plurality of curved Venturi channels 9, 9 ¹ which extend from radially inside to radially outside between correspondingly designed protruding segments 10, 10' of the Venturi plates 5, 6.

Via a nozzle 7, cleaning liquid is injected into the gas to be cleaned, which is introduced into the wet gas scrubber from above, before it reaches the Venturi zone. The mixture of gas to be cleaned and cleaning liquid droplets then gets into the horizontal, but curved Venturi channels 9, 9', whose flow cross-section can be varied simultaneously by adjusting the distance of the Venturi plates 5, 6. The mixture flows out of the Venturi zone with a spin along the outer periphery and gets into a second cleaning stage which is formed as a cyclone cleaner 11. The two cleaning. zones are accommodated in a common housing 1.

In the cyclone region, the solid and/or liquid particles are captured by the cleaning liquid droplets and precipitated on the housing wall 8, where they are downwardly discharged from the conical outlet 2. In the modified embodiment shown in Fig. 2, the housing has a flat bottom. The solid and/or liquid particles then can be withdrawn, e.g. also through a non-illustrated lateral outlet.

The cleaned gas flows upwards in the housing 1 , gets into a central gas outlet 4 via outlet slots 4' and exits to the outside.

In operation, as shown in the drawing, the water-saturated gas and the injected cleaning liquid initially flow vertically into the Venturi zone, which is formed by the Venturi plates 5, 6 equipped with curved Venturi channels 9, 9'. A stationary lower Venturi plate 5 equipped with protruding segments 10, which together with an upper vertically adjustable Venturi plate 6 equipped with protruding segments 10' forms a plurality of Venturi channels 9, 9', deflects the gas/liquid mixture into the horizontal. The vertical gas/liquid stream gets into the horizontal star-shaped Venturi channels 9, 9', where it is accelerated. The high velocity in the small throat region of the individual Venturi channels 9, 9' of the Venturi zone generates a large number of very fine liquid droplets. The particles contained in the gas are intensively mixed with the mist of these tiny liquid droplets. Due to the high relative velocity between droplets, particles and gas, the particles are captured by the droplets.

Even with a fluctuating gas flow, the gas pressure drop is kept constant by regulating the total flow cross-section of the Venturi channels 9, 9'. The adjust- ment of cross-section is effected with the second Venturi plate 6, which represents a negative shape of the lower, stationary Venturi plate 5, so that the two plates 5, 6 can plunge into each other more or less, in order to determine the Venturi cross-section of the Venturi throat. This adjustment can be effected automatically, controlled by setpoints of the gas pressure difference across the Venturi zone.

The mixture of gas and cleaning liquid droplets emerging from the Venturi zone receives a spin due to the horizontal star-shaped and curved design of the Ven- turi channels 9, 9', i.e. it enters the cyclone cleaner 11 with a spin. The liquid droplets, the particles and the gas are caused to rotate due to a centrifugal force along the housing wall 8 thereof. This force causes an additional agglomeration of particles and liquid droplets. Due to the helical movement of the mixture of gas and liquid droplets, the latter and the particles are separated and collected in the cone-shaped outlet 2 of the housing 8, whereas the cleaned gas flows upwards into the central outlet 4 and to the outside.

Therefore, the invention substantially is characterized by an infinitely variably adjustable four-channel Venturi cleaning zone. The flow cross-section and the shape of the entire Venturi cleaning zone are adjustable proportional to the pressure gradient, so that the gas flow model remains unchanged for each cross-sectional size. The adjustment of the individual Venturi channels is effected synchronously. Due to the curved Venturi outlet diffuser, an additional cyclone effect is obtained. The Venturi cleaning zone and the cyclone cleaning zone are combined in one and the same housing.

An automatic control is effected via the pressure drop, so that in the case of fluctuating gas flows the cleaning efficiency remains the same. There are no uncontrolled turbulences and a carry-over of droplets is minimized. Furthermore, certain cleaning effects can be preselected. The adjustment of the cleaning effect can be accomplished from outside.

List of reference numerals:

1 housing

2 outlet

3 gas inlet

4 gas outlet

4 ¹ outlet slots

5 lower Venturi plate

6 upper Venturi plate

7 nozzle

8 housing wall

9. 9 ¹ Venturi channels

10, 10' segments

11 cyclone cleaner