Venturi scrubbers are primarily used for the cooling, condensation, and preliminary cleaning of hot gases. In wet-type gas cleaning systems, the scrubbing liquid is injected from a central nozzle or multiple nozzles in the inlet cone before the venturi throat.
Venturi scrubbers can be mounted vertically or horizontally. The cleaner operates with only a few millibars of pressure drop for the purpose of cooling and dust removal. The small pressure drop is achieved by matching the velocity of the injected scrubbing liquid with the pollutant-laden gas in the venturi throat.
During deceleration in the diffuser, the relatively higher mass of the scrubbing liquid causes an additional increase in gas pressure. Depending on the volume of the injected liquid, not only does the gas cleaner experience a pressure drop, but the gas pressure also increases. Conversely, when operating such a cleaner with a large pressure drop, the gas-to-dust mixture enters the cleaner zone at a higher velocity than the cleaning liquid.
As a result, the liquid droplets are accelerated by the gas flow, leading to a pressure drop.
As the velocity increases, the simultaneous increase in turbulence in the venturi achieves high separation efficiency, which is a prerequisite for effective particle collection. The scrubbing liquid flow rate, pressure, pollutant gas density, particle size, particle density, and gas temperature are important parameters for achieving high collection efficiencies. Therefore, as the gas velocity in the venturi throat increases, the pressure drop also increases.
While the design of a venturi scrubber may appear simple, it is actually quite complex and requires extensive experience.