Cyclone plate or baffle mist eliminator

In that case, where is the mist eliminator installed? I’ve seen several spray towers; it seems that the demisters are all inside the tower

Installed at the upper part of the tower; the baffle effect is significant when the flow velocity is 2 m/s or higher

As for baffle plates, they can be made workable with proper design, but I’m not sure what to do with swirl plates!

The tower mist eliminator is usually installed at the top of the tower. However, the size of the demister is often different from the diameter of the tower. Firstly, the size and structure of the demister are determined by various physical parameters related to the operating conditions, such as the temperature and pressure under which it operates, the flow rate of the gas phase, its composition, the eccentricity factor of the gas phase, its density, viscosity, as well as the amount of liquid carried along with it, the composition of the liquid phase, its density, viscosity, and surface tension. Additionally, technical requirements such as separation accuracy, separation efficiency, and operating pressure drop also play a role in determining these parameters. The structural dimensions of the demister, whether too large or too small, will significantly affect its demisting efficiency. Therefore, it is incorrect to arrange demisters on the tower cross-section according to the tower diameter; yet this is a method often used by unprofessional separation companies in China to get away with it by taking advantage of the owners and design institutes’ lack of understanding of demisting and separation technologies. Secondly, the placement location of the demister also needs to be determined based on the specific operating conditions and phase-related process parameters, taking into full account the dimensions and structure of the tower, as well as the locations of the air inlet and outlet structures. This is achieved through precise dynamic separation calculations and a configuration design system platform. Since the flow pattern of the air changes as it enters the tower through the inlet pipe, and such a change also occurs as the air exits the tower through the outlet pipe, if the mist remover is not installed in the proper position, it will inevitably result in part of the mist remover operating abnormally or even not functioning at all. This leads to a significant reduction in the efficiency and accuracy of mist removal, failing to meet the design requirements. Therefore, it is recommended that owners and design institutes entrust professional dynamic separation technology companies to develop the demisting solution, in order to prevent the actual performance of the demister from deviating too much from the design specifications.

Since their introduction abroad in the first half of the last century, baffle plates – with their structure and the performance characteristics resulting from that structure – have evolved from the first-generation Chevron flat-plate baffles to the vane-type internals we see today; this represents the fourth and fifth generations of such technology, bringing about a qualitative improvement in their structural performance. A swirl plate is a spirally shaped version of a baffle plate. Due to the need to achieve spiral deformation, its plate structure and gas flow path are much simpler and shorter compared to those of the baffle before deformation, resulting in a significant loss in separation performance. However, the swirl plate can be arranged in a spiral cone shape along the inner wall of cylindrical equipment with a simple structure; it is easy to manufacture and install, resistant to clogging, and results in low pressure drops. It is often used for the primary separation of heavy-phase carriers with sizes of 30–80 microns or larger, such as in the primary dust removal of exhaust gases from coal crushers or in the primary separation of gas, liquid, and solid phases in flash tanks and other similar applications. For applications with high requirements for separation accuracy and depth, cyclone plate mist eliminators cannot be used. I have seen some plant owners and design firms use swirl plate mist eliminators in the gas-liquid separators of methanol plants, as well as in the mist removal systems for flue gases exiting wash towers and exhaust gases; the separation performance of such systems inevitably fails to meet the required standards, resulting in penalties.