Wire mesh mist eliminator

Filters for mists and droplets have more open area than those used for dry parhcles. If a filter is made of many fine, closely spaced fibers, it will become wet due to the collected liquid. Such wethng will lead to mathng of the fibers, retenhon of more liquid, and eventual blocking of the fiter. Therefore, instead of fine, closely spaced fibers, the usual wet filtrahon system is composed of either knitted wire or wire mesh packed into a pad. A looser filtrahon medium results in a filter with a lower pressure drop than that of the filters used for dry parhculates. The reported pressure drop across wire mesh mist eliminators is 1-2 cm of water at face velocihes of 5 m sec T The essenhal collechon mechanisms employed for filtrahon of droplets and mists are inertial impachon and, to a lesser extent, direct intercephon. 

Figure 4-21. Typical wire mesh mist eliminator pressure drop curves for one style of mesh at three different liquid loadings. Others follow similar pressure drop patterns. By permission, Otto H. York Co., Inc.

The nitric acid evaporated from the high-level waste concentrator is too dilute and contains too much entrained radioactivity to be recycled without additional treatment. This acid, together with dilute acid waste streams from the uranium and plutonium purification solvent extraction systems, is decontaminated in the nitric acid evaporator. Entrainment can be suppressed by providing partial reflux through a few bubble-plate or perforated-plate trays, backed up by wire-mesh mist eliminators. 

S O. H. York and E. W. Poppele, Wire Mesh Mist Eliminators. Chem. Eng. Prog., 59, 6 (fane... 

Two special requirements for the effective use of structured packing are efTiciem mist eliminators and uniform iiquid distribution. Kean et al. (1991) recommend a vane type eliminator with a 3- to 4-in. mesh pad face to minimize carry-over. A simple wire-mesh mist eliminator is not considered adequate at the high gas velocities employed with structured packing. They also recommend that a high-efficiency drip-type distributor be used with typical matrix dimensions of 4 in. by 4 in. and the peripheral drip points iocated no more than 2 in. from the wall. The distributor must be installed as close as possible to the packing to ensure good distribution and minimize carry-over. 

Figure 3 A typical wire mesh mist eliminator. [Courtesy of Amistcoj... 

Figure 5 Performance of wire mesh mist eliminator usirig different size wires- [2]...

For vane mist eliminator, there is also a vapor velocity operating range for it to perform well. But vane mist eliminator is less susceptible to le entrainment and flooding than wire mesh mist eliminator. Therefore, it can operate at higher vapor velocity (30 to 40%) higher. Vane mist eliminator tumdown ratio is also about 4 to 1. 

Others Both wire mesh and vane mist eliminators will perform better, If the difference between liquid and vapor density is larger, or vapor viscosity is low. The reason is these effects will help wire or vane plate to capture liquid droplets. Bither wire mesh pad or vane pad can be installed horizontally or vertically. In general, vane mist eliminator is more expensive than wire mesh mist eliminator. 

Efficiency of the mist eliminator The efficiency of a wire mesh mist eliminator is defined as [3]... 

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