Helping Brink Mist Eliminator clients achieve trouble free mist eliminator installation and operation is our goal.
MECS is the expert on all types of mists, be they in process gases, indoor air quality (metalworking systems) or air pollution. Effective troubleshooting begins when Brink fiberbed elements are first installed and operated. This involves assuring a proper installation and operating at design process conditions
Installation/Maintenance: Proper mist eliminator installation and maintenance is as important as designing the right mist eliminators for the job. An effective installation requires proper gasket selection, flat mounting surfaces, correct bolt tightening procedures, and proper liquid seals.
For maximum trouble-free service, it is important to select the proper gasket for the specific process. Also a proper installation includes a correct bolt tightening sequence. Using the tightening method as outlined in MECS IMI (Installation & Maintenance Instructions) will assure proper gas tight seals. The MECS bolt tightening method assures gaskets are compressed uniformly. Using power tools with improper tightening may distort element flanges especially
when stiffer/thicker gaskets are used.
After installation, a smoke test is recommended for large installations with high efficient diffusion fiberbeds to assure proper installation of gaskets and liquid seals. Details for the smoke test can be provided.
For a proper installation, liquid and gas seals need to be established. It is emphasized that the Installation & Maintenance Instructions (IMI’s) be given to the right people to encourage reading.
It is important to detect and correct problems early with mist eliminator installations before they become severe and out of control.
Four typical problem areas for mist eliminator installations include:
High pressure drop (or abnormal pressure drop)
Opacity (visible stack plume)
High measured exit loading
Example of Visible Opacity
A number of testing or troubleshooting methods can be used to evaluate the installation:
Monitoring pressure drop and flow rate
By far the most important “trouble-shooting” or “trouble-prevention” involves monitoring mist eliminator performance on a regular basis and if undesirable symptoms occur, conducting an evaluation to correct problems before they become severe. Monitoring mist eliminator performance involves maintaining accurate and complete operating records. Records should include inlet process conditions: gas flow rate, temperature, and pressure along with element
pressure drop and liquid drain rate from the mist eliminator vessel.
Monitoring element pressure drop and gas flow rate over time verifies operation is in the correct range. Any significant deviation in pressure drop is likely to be accompanied by a deviation in collection performance. A plot of normalized pressure drop (pressure drop corrected to design gas flow rate) versus time should be maintained.
The pressure drop is measured by connecting a U-tube manometer filled with water (not mercury) between a pressure tap on the inlet (upstream) side of the mist eliminator and a pressure tap on the outlet (downstream) side of the mist eliminator. Typical element pressure drops will range from 4 to 20 inches water column gauge (100 to 500 mm water column). Make sure pressure taps are open.
Avoid measuring pressure drop by comparing the static pressures on both sides of the mist eliminators since small inaccuracies in readings are magnified when calculating the difference. (e.g., A 10% error in reading static pressure of -80 inches water column gauge (-2000 mm wc) translates into a 60% error in calculating a 12"wcg (~300 mm wc) mist eliminator pressure drop.)
Pitot tube stack readings using EPA test methods 1 and 2 can provide an acceptable measure of gas flow if a suitable location can be found in the ductwork.
Example sampling train used to measure mist particle size distribution
Information on using other troubleshooting methods is available on request.
If simple tests and/or an inspection do not identify the problem, a mist sampling program may be necessary. The sampling method must include the separation of mist from any vapors in the process. This needs to be reviewed with the sampling company.
Other test equipment that can be used includes optical aerosol monitors and Dwyer flowmeters. Test laboratories are often used to evaluate condition of the fiber packing (see Fiber Analyses).