Improved dirt removal bottle washers

Bottle washers rank among the most cost-intensive pieces of equipment in a line, which is why their availability, their resistance to malfunctions and their efficiency are vital considerations. In order to improve the efficacy of the dirt removal function, Krones AG, Neutraubling, Germany, has developed a new pre-soak concept.

Given a typical line size of 60,000 bottles an hour, about 1 g of dirt is brought in per bottle (excluding labels). That’s 60 kg an hour, which with a weekly constant running time of 150 hours adds up to 9 tons. Before starting development work, Krones asked itself the fundamental question: what’s the best way to cope with such a conglomeration of sand, beverage residues, crowns, cigarette ends, glass fragments and bits of dress. Mechanical systems, such as sieving-conveyor removal systems or rotating cullet scrapers, are susceptible to malfunctions. And because of where they are installed, they are concomitantly difficult to clean and maintain.

Hydraulic solution

For this reason, the solution adopted was a hydraulic one: a propeller pump with a recirculation rating of about 500 m³/h ensures a flow across the machine. The recirculated flow is taken from the filtered side of a small label removal unit, pumped through a pipe extending over the width of the machine, and fed back into the machine again. This flow energy is sufficient to convey all the dirt and dress residues through the pre-soak channel into the sieve case.

In the specially shaped lower section of the sieve case, the heavier parts, like glass or sand, settle to the bottom under gravitational force. The lighter substances, like label paper, are carried along on the surface and taken out of the machine on the sieving conveyor removal unit. The glass fragment collecting tank is connected to a removal lock with a vertical pipe. The valves are controlled and the lock emptied in dependence on the amount of glass fragments collected. With this new pre-soak concept, Krones has significantly improved the cleaning performance capabilities of its bottle washers.