Acid Flushing of TSE Barrel Cooling Bores
Vol. 36 #3, Summer 2011
Liquid-cooled twin screw extruder barrels are heat exchangers, with the coolant bores that are subject to fouling from scale buildup. Most operators notice that the cooling performance of a new extruder is much better than after 3 or 4 years of running. This is because the new extruder barrel has smooth, shiny fresh-drilled cooling bores. The older machine has a layer of crusty mineral deposits lining the bores that act like an insulator.
If left unchecked, scale build-up leads to reduced cooling efficiencies. Eventually the cooling bores can become completely blocked, and zero water flow means a lack of cooling. If this happens, the only solution is to remove the barrels from the extruder and drill out all the cooling bores......a time consuming procedure.
There is a simple preventive maintenance procedure to avoid these problems and maintain cooling efficiencies. The recommended procedure is to circulate a scale removal chemical through the barrels periodically. With production extruders, this is recommended every 6 to 12 months or so. Many of the tower and chiller manufacturers make small, inexpensive re-circulating de-scaler units that are ideal for cleaning barrel bores.
- Charlie Martin, Leistritz
Figure 1: Twin screw barrel having clogged bores drilled out
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