In certain cases cooling tower drift (mist) can overwhelm conventional lower efficiency chevron mist eliminators. This paper explores an alternative strategy to control drift in those cases. The author uses a case history to illustrate conditions that can be expected to cause uncontrolled drift and to discuss a solution.
The author acknowledges that the information presented is anecdotal, specific to the particular case and has not been tested for the general case in a laboratory environment. On the other hand the monetary results are confirmed by the customer as accurately representing the before and after operating results.
Most processes encountered in the refining and chemical and energy industries require the rejection of waste heat. One economical and effective means of accomplishing this is through the use of cooling towers. In cooling towers, the latent heat of vaporization of water can be transferred by convection and evaporation (mass transfer) using direct contact of atmospheric air and the process water. Another result is a significant environmental concern - DRIFT.
As illustrated by the case study certain conditions lead to many conventional lower efficiency chevron drift control mechanisms being overwhelmed with resultant problems of water and chemical loss, and damage to structures outside of the cooling tower. The author is proposing a solution that has been successful in controlling excessive drift at a number of locations with a resulting reduction in chemical loss and damage that has lead to clear economic benefits for the operator.
While the solution has not been tested in laboratory conditions that mimic cooling tower applications, the author notes that mist collection in cooling towers is essentially the same as the general case for mist collection in many industrial applications where similar solutions have been proven and documented.