When a limestone-slurry FGD project proposes fine random packing for higher SO₂ removal, first evaluate solids concentration, gypsum formation, scale, support-grid plugging, abrasion, washing, and acceptable maintenance interval. Fine high-area packing can become a solids trap, and in heavy slurry service an open spray-contacting system may be more suitable than forcing the duty into a conventional packed bed.

For a seawater SO₂ scrubber, high circulation rate alone does not guarantee adequate removal. Natural alkalinity, pH, temperature, salinity, fresh-water dilution, recirculation fraction, fouling, material compatibility, and demister salt carryover should be included in the operating basis. The limiting factor may be chemical buffering rather than packing hydraulics.

Outdoor scrubbers with open vertical stacks should be reviewed for rain ingress, especially during shutdown. Rainwater can wet the demister from above, increase sump level, dilute reagent, load distributors and packing, and create restart carryover. Stack termination, drainage, storm liquid balance, and restart checks should be considered before blaming mist-eliminator performance.

Acidic and cyanide-containing plating exhausts should not be combined into one packed scrubber merely to reduce equipment count. Acidification of cyanide-containing material can generate highly toxic hydrogen cyanide, so gas ducts, liquid circuits, sumps, drains, maintenance procedures, and treatment stages require qualified process-safety review before packing or internals are selected.

When a mist eliminator drains correctly during atmospheric testing but fails under negative-pressure operation, check drain pressure balance, available hydrostatic head, seal-leg design, operating vacuum range, drain destination pressure, blockage, solids, and freeze protection before changing the separator media.