Vertical scrubbers are recommended for surface treatment or chemical applications, depending on the products treated and the concentration of gases to be extracted. They are particularly appreciated for their compact size, low-pressure loss and high efficiency.
The process involves establishing maximum contact between liquid and gas using a fine, intense spray with a high-efficiency exchange screen separating each section. The scrubber is equipped with a mist eliminator at the top, which removes most of the mist produced by the spraying. The scrubber is supplied complete, with spray circulation, circulation pump, recirculation tank, automatic water supply and level controls.
The mass transfer, and therefore efficiency of a scrubber, depends on the gas solubility, gas/liquid exchange area, contact time, and the gas speed through the scrubber. Chemical scrubbing, via a pH adjusted scrubbing solution, may be required as well.
Depending on the incoming exhaust gas properties, two types of vertical scrubbers are used: a spray gas scrubber or a packed scrubber.
A spray gas scrubber is a cost effective solution, has a low-pressure loss, but has a lower efficiency than a packed scrubber. The packed scrubbed has a higher removal efficiency, but there is a risk of clogging the random or structured packing inside the scrubber.
Which scrubber to choose depends on the pollutants, required efficiency, pressure loss, and the solid content in the exhaust air. Often, a combination of the two types are used in a two or three stage arrangement. If a high solid content (dust) is in the exhaust air, a venturi scrubber may be included in the system configuration.