Case Study: Demister Rebuild
·4 min read
How SMI rebuilt a corroded demister pad in a chemical plant, restoring separation efficiency and extending service life.
Background
A chemical processing plant reported carry-over of liquid droplets from a scrubber stack, causing downstream fouling and lost product. Inspection showed the existing demister pad—originally galvanised steel—had corroded and channelled.
Assessment
- Service: acidic vapour, 65 °C, 1.2 m/s superficial velocity.
- Existing pad: galvanised steel, 150 mm thick, badly corroded after 4 years.
- Vessel diameter: 1 800 mm.
- Problem: liquid carry-over > 5 % above design.
Solution
SMI specified a 316L stainless steel knitted mesh pad with co-knitted multifilament for fine droplet capture, mounted on a 316L support grid. Density was tuned to balance separation efficiency and pressure drop.
Results
- Carry-over reduced to below 0.1 %.
- Pressure drop within design limits.
- Projected service life increased from 4 to 10+ years.
- Downtime for rebuild: 1 shift.