RotoClone® W Takes The Heat

Our client is a world leading specialist in the field of heat treatment and annealing of metal products. The annealing process uses controlled heating and cooling to change the metallurgy of the product. Usually the treatment is done to change the metals ductility typically to make it more workable.


In this case our client was involved in upgrading a heat treatment process for a strip steel mill in Italy. As part of the upgrade, it was decided to improve both the in-house environment and reduce emissions to the atmosphere. This was to be done by installing an extraction system to draw away the pollutants - dust, mill scale and steam - and discharge them to atmosphere after cleaning the gas flow by passing it through a suitable air cleaning device. Because of the mix of mill scale, dust, hot air and water vapor, the only choice would be a wet scrubber.


The facility to be upgraded had very little space free for bulky new equipment and a traditional scrubber can be large and often have ancillary equipment such as a fan, mist eliminator, settling tank, pumps and piping. The RotoClone® W requires none of these ancillaries and is renowned for handling very large air flows in a small lightweight package. The RotoClone® has fully irrigated internal surfaces and therefore can be relied upon to keep itself clean. Furthermore the collected material is continuously sluiced away either to drain off to a remote water treatment plant - ideal in a steel mill which has extensive cooling water systems.


The client required a variable flow rate which could be as high as 60,000 Am3/hr. This would normally require a large sized filtration package but the space available to fit a scrubber, fan set, droplet eliminator etc. was extremely limited. There was no space for a settling tank and the end user wanted a solution that imposed no additional routine tasks such as regular removal of collected sludge. Finally the new equipment had to achieve a clean emission whilst being reliable and quiet in operation.


AAF selected the RotoClone® W, size 36 with a space saving elbow outlet which conveniently provides a vertical discharge. The flow rate was variable as the client provided a variable speed control for the RotoClone® motor. The maximum flow rate was 60,000 Am3/hr which is remarkable for such a small scrubber. In fact, the RotoClone® is hardly any bigger than a centrifugal fan sized for the same duty. The RotoClone® employs a “once through” water system and works without problems on a grey water supply provided the supply water is free from grit. The used water, containing collected dust, mill scale and condensed water vapor is piped away to the facility’s water treatment plant.


The client was delighted with the outcome. The RotoClone® achieved the required flow and coped well with the inlet loading of dust, mill scale and water vapor. The emission is minimal and well within statutory limits. Because the RotoClone® W is a self-contained wet scrubber which is also an air mover no separate fan was required. This was key in allowing the scrubber package to fit within the limited space available. The RotoClone® has only one major moving part - the rotating impeller. In this case the speed of rotation is quite low and coupled with the oversize shaft and bearings this promises long term reliability. Routine servicing consists of inspection and lubrication.