Vessel diameter and manhole
The pad diameter follows the vessel, but the manhole decides how it is delivered. Tell us both and we specify one piece or segments with overlap — assembled inside the vessel, never cut to fit on site.
dwg AVX-1801 · Produits
Demisters & mist eliminators
Every micron engineered. Every millisecond protected.
Définition
A demister is a knitted wire mesh pad fitted in a vessel or column that removes entrained liquid droplets from a rising gas or vapour stream. The gas passes through; droplets impinge on the wires, coalesce into larger drops and drain back against the flow. Because separation is mechanical, a demister keeps working as long as the pad stays clean and the gas velocity stays inside its design window.
Également appelé: mist eliminator · demister pad · knitted mesh pad · droplet separator · vapour-liquid separator
Carry-over is rarely a mystery. It is a pad that was sized for a different duty, a pad that has blinded with solids, or a pad that was replaced with whatever fitted the flange. Each of those shows up downstream as a fouled compressor, a wet product or a column that will not hold its spec.
We supply demister pads cut to your vessel, in the alloy your process demands, with the support grids and hold-down bars that keep them in place. Send the vessel diameter, the operating pressure and temperature, the gas rate and the liquid load. If the drawing exists we work from it; if it does not, we draw it.
Pads for vessels larger than the manhole are supplied in segments with an overlap, so the pack can be carried in and assembled inside without cutting on site. Grids, rings and hold-downs are supplied in the same alloy as the pad unless the specification says otherwise.
Où il est utilisé
- Separator vessels and knock-out drums
- Distillation and absorption columns
- Evaporators and flash vessels
- Scrubber outlets and vent stacks
- Compressor suction protection
- Steam and gas conditioning
| Propriété | Valeur |
|---|---|
| 100–300 mm (standard range) | |
| 0.10–0.28 mm | |
| 80–192 kg/m³ | |
| 97–99 % | |
| typically from 3–5 µm — confirmed per application | |
| 0.07–0.11 m/s (Souders–Brown) | |
| typically < 250 Pa | |
| one piece or sectioned for manhole entry |
Values shown are standard industry ranges for knitted mesh demister pads, not a commitment. The exact specification — pad style, wire diameter, density, thickness and alloy — is confirmed per application after technical review of your process data.
Ce qu’il faut préciser
Gas velocity window
A demister has a working band. Below it, droplets slip through untouched; above it, the pad re-entrains what it just captured. Give us the gas rate and density and the sizing follows from the Souders–Brown relation rather than from the previous pad's dimensions.
Liquid load and fouling
A high liquid load or a dirty service wants a coarser wire and a more open pad; a demanding separation wants a finer one. If the current pad blinds, the answer is usually a change in specification, not a like-for-like replacement.
Alloy and temperature
316L covers most duties. Chlorides, sour service and higher temperatures move the choice to Duplex, Inconel, Monel or Hastelloy. State the medium and the design temperature — the alloy is a consequence of those, not a preference.
Matériaux & variantes
Standard in 304 and 316L. Also supplied in Duplex, Inconel, Monel, Hastelloy and, for lower-temperature or corrosive duties, in polypropylene or PTFE. Support grids, rings and hold-down bars are matched to the pad alloy. Availability and lead time for the higher alloys are confirmed at quotation.
Questions fréquentes
What is the difference between a demister and a mist eliminator?
In practice, none. "Demister" and "mist eliminator" describe the same knitted wire mesh pad. Vane packs and cyclones are also called mist eliminators, so if the distinction matters in your specification, say which construction you mean.
How do I know my demister pad has failed?
Two signatures. Rising pressure drop across the pad with no change in throughput points to blinding. Liquid appearing downstream at unchanged pressure drop points to re-entrainment or a bypass around the pad, usually a hold-down that has worked loose.
Can you supply a pad for a vessel that is larger than the manhole?
Yes. The pad is supplied in segments with an overlap and assembled inside the vessel. Give us the manhole diameter with the vessel diameter and the segmentation is worked out before anything is made.
Which alloy should I specify?
316L is the default. Chlorides, sour gas or higher design temperatures usually move the choice to Duplex, Inconel, Monel or Hastelloy. Send the medium, concentration and design temperature and we come back with an alloy and the reason for it.
What data do you need for a quotation?
Vessel and manhole diameter, operating pressure and temperature, gas flow and density, liquid load, and the alloy or the service that decides it. A sketch of the existing pad and its support ring helps; a drawing helps more.
Do you also supply the support grid and hold-down bars?
Yes, as one scope. Pad, support grid, hold-down grid and the fixings are supplied together in matching alloy, so nothing on site has to be improvised during a shutdown.
How fine a droplet can a demister remove?
Knitted mesh pads typically start to work from around 3–5 µm, with the achievable figure depending on gas velocity, liquid load and pad style. The rating for your duty is confirmed per application — a number quoted without the process data behind it is not worth much.
RFQ
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