METHOD AND DEVICE FOR OPERATING A SCREEN WHEEL FILTER

摘要

The invention relates to a method and a device for operating a screen wheel filter for highly viscous melts having pressures >10 bar and temperatures >90° C. which shall be further developed in such a way that less of the highly viscous melt is wasted and that the operation of the screen wheel filter can be made more economical. For this purpose the screen wheel (3) according to the invention is rotationally driven at least one complete revolution, with respect to one of the screen inserts (12) located in the melt channel (10), before the particular screen insert (12) is replaced and/or backflushed, and wherein the drive speed and drive cycling for the screen wheel (3) are set in dependence on the thermal or oxidative decomposition behavior of the particular melt in such a way that, when the particular screen insert (12) reenters the melt channel (10) of the screen wheel filter (1), the melt remaining in the particular screen insert (12) has experienced thermal decomposition or oxidative decomposition of <3% cleaved molecular chains, preferably <1% cleaved molecular chains.

主权项

1. A method of operating a screen wheel filter for a high-viscosity melt having pressures >10 bar and temperatures >90° C., the screen wheel filter substantially comprising a screen wheel mounted in a housing and carrying a plurality of angularly offset screen inserts, the screen wheel filter having a melt passage offset from an insert backflushing station and/or insert changing station, the method comprising the steps of:
to rotationally indexing the screen wheel through at least one complete revolution with respect to one of the screen inserts located in the melt passage before one of the screen inserts is replaced in the insert changing station and/or backflushed in the insert backflushing station, and setting the drive speed and drive cycling for the screen wheel in dependence on the thermal or oxidative decomposition behavior of the particular melt such that, when any of the screen inserts reenters the melt passage of the screen wheel filter, the melt remaining therein has experienced thermal decomposition or oxidative decomposition of ≦3% cleaved molecular chains.