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LENZING Technik
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Wet Churn
WET-CHURN
For batch xanthation of alkali cellulose.
Features
- Self-cleaning xanthator requires opening only once per year
- Superb seal performance provides optimum work-place conditions
- Fully automatic operation for most reliable and stable quality of viscose
- Reliable mechanical construction ensures highest possible availability and minimum maintenance
In Detail
The wet churn for xanthation is a horizontal cylindrical tank with a mixer inside. The tank is tilted by 7.5° to enable nearly complete discharge, minimising the volume of remaining lye or viscose. Before the beginning of the xanthation batch cycle, one batch of alkali cellulose has to be weighed in the weighing hopper and is fed through an upright branch pipe into the wet churn.
After evacuation of the tank, carbon disulphide is sprayed in through small pipes placed on the inner surface of the wet churn.
The tank is designed with a double jacket to enable slight heating for better drying of the inner surface at the end of each batch. Remaining caustic would definitely lead to restrictions in viscose quality.
The extremely narrow gap of only 4-6 mm between the mixer and the polished cylindrical inner surface demands highly sophisticated manufacturing procedures. But only the narrow and uniform gap provides the necessary self-cleaning action of the xanthation machine. This means that after finishing the batch cycle, the xanthator is be ready for the next batch and does not have to be opened for cleaning. Any remaining particles inside would lower the quality of the viscose.
As a result of the unique self-cleaning performance the wet churn has to be opened only once a year for inspection purposes. This leads to minimum emissions of carbon disulphides and the best possible working conditions in the xanthation area. Needless to say, Lenzing Technik uses advanced sealing technology to avoid any leakage between the mixer shaft and the casing.
We recommend the placing of the drives for the wet churn in a separate room to avoid the necessity of using more expensive ex-proofed motors.
At the end of xanthation the xanthate is dissolved in caustic lye, which is sprayed in through nozzles. After discharging the churn additional lye is sprayed in through the same nozzles to allow the cleaning of the inner surface.
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