Nozzles for Gas Scrubbing
Engineering consideration - Gas direction and velocity
The smaller the droplet size the lower the impact and reach of the spray. In a moving gas flue this can mean that very fine sprays will not reach all required areas. If the full area of the flue is not covered then channels of untreated gas can escape, thus reducing the efficiency of the scrubber. So whilst the smallest droplet size will give greater abstraction it might not be optimum. The low velocity fine mists will need to be balanced against the throw and coverage achievable by the spray system.
This balance can often be achieved by careful nozzle selection. For example, the spiral design of nozzle is often found to improve performance in gas scrubbing applications. This design of nozzle produces relatively fine droplets when compared to other common designs of full cone nozzle but it also has a broader spectrum of droplet sizes. So whilst the average droplet size is smaller there exists within the mix some heavy droplets. These heavy droplets tend to converge in rings within the spray cone and they actually help carry the whole spray to areas where it would normally be blown off course.