Rimless Teller Rosette

A Teller rosette is a random packing shaped like a flower rather than a ring. It was invented by the American engineer A. J. Teller in 1954, which is where the name comes from; in China it is usually called 花环, the flower ring, and sometimes the plum-blossom ring or the Tellerette. The piece is made from a run of small curved loops set side by side and bent round radially, so together they form a flat, open rosette, much like a coil spring wound into a flattened ball. In this rimless version there is no outer ring closing the loops in, so the flower sits completely open. That open, looping form is light, very high in void and, as we will see, good at both holding liquid and shrugging off blockage.

The Teller rosette is above all a scrubbing packing. It fills gas-washing and purification towers, acid-mist scrubbers, and the waste-gas systems of chemical plants, and it also serves in wastewater treatment. What draws engineers to it for these jobs is that it does not block: dirty, particle-laden or scaling gas that would clog a denser packing passes through the open flower without trouble. At the same time it carries a large gas and liquid load at a low pressure drop, so a scrubber stays efficient without a big energy penalty. Wherever a gas is fouling, corrosive or simply high in volume, the rosette is a natural fit; it is less used for fine distillation, where other packings suit better.

The rosette is made across a wide range of plastics, and the choice follows the chemistry and temperature of the gas. The common body is polypropylene, with glass-reinforced PP for extra stiffness; PVC and CPVC cover cool-to-warm chlorinated and acidic streams; PVDF and PFA are the fluoropolymer grades for hot or strongly corrosive service; and HDPE is on hand where its toughness helps. Across these the media temperature runs about 60 to 150 degrees. All of them are corrosion-resistant, which is why the rosette holds up in the acid mists and aggressive vapours it is often asked to scrub. Tell us the gas, its temperature and any particulates, and we will point to the right grade and size.

Two things set the rosette apart, and both come from its open, looping shape. First, it does not clog. There is no closed wall and no tight internal cage to trap solids; the gas threads through the gaps between the loops, so scale, dust and biological growth wash through instead of building up, which is why it is favoured for dirty and fouling gas. Second, and less obviously, the many little loops and the spaces between them hold on to a fair amount of liquid — the packing has a high liquid holdup. Because the liquid lingers longer in the bed, gas and liquid stay in contact for longer, and that extra contact time raises the amount of scrubbing or mass transfer done per metre of tower. So the rosette combines two qualities that usually pull against each other: it stays open and unblocked, yet it holds liquid well. Send us the duty and we will confirm it suits.