SEI Contreras Engineering has the design technology and experience for the construction of gas scrubbers.
The main function of these equipments is to eliminate or to retrieve fines particles suspended in the drying air gaseous current from a flash or spray dryer by means of a thin water spray. Gas scrubbers are placed after the separating cyclons of the dryer. While the cyclons separate most of the solids in a gaseous flow, the scrubber only retain the fines the escape them. The air usually has a low fines content of between 0,1 % and 1% of the dry product exiting the dryer and can be considered a polluting agent especially in the case of toxic products (i.e: herbicides). Fines particles are suspended in the water droplets and are retained when they are contacted. The resulting solution can be reprocessed or sent to a waste treatment plant, while the clean air is sent to the atmosphere.
The water used in a gas scrubber can contain chemical additives that increase the retaining effect of the equipment by forming salts with the product.
A very commonly used equipment for this operation is a Venturi Scrubber, which allows a very close contact between fines and cleaning solution due to its unique design that increases air speed just before entering the equipment, generating a strong turbulence inside it and increasing contact with the water. In these type of scrubbers it is critical to generate a very intense and fine spray of cleaning liquid in order to increase the product-liquid interface area.
Another type of equipment used is a scrubber column, which consists in a vertical cylinder filled with plastic, ceramic or steel o-rings or similar components. The air circulates through the filling material in a countercurrent configuration with the cleaning liquid, and the filling increases the air liquid interface area, retaining the fines.