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LENZING Technik
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Viscoseaufbereitung
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AC-Kühler
Alkali Zellulose Kühler
For cooling the AC down after ageing to the optimum xanthation temperature.
Features
- Low and stable outlet temperatures of AC to stop ripening and ensure stable process conditions
- Wide range of temperature of AC inlet and outlet temperatures possible
- Closed air circuit leads to
no reaction between carbon disulphide and AC to lower quality
nearly no moisture losses from the AC
- Fluidised bed heat exchanger for minimum temperature variations between particles of different sizes
In Detail
STRONG ARGUMENTS FOR USING AN AC COOLER
In order to slow down the depolymerisation reactions after ageing, as well as to achieve the correct, stable AC temperature for xanathation, it is recommended to cool down the AC. This takes place in a so-called alkalicellulose (AC) cooler, which is fed with AC by a screw conveyor.
CLOSED-LOOP AIR CIRCULATION
Chilled circulating air is blown in from the bottom side through a grating by two fans, where it forms a fluidised bed with the alkali cellulose particles. The alkali cellulose is continuously conveyed towards the outlet by the pressure of the material fed into the machine.
The AC is rapidly cooled and the air warmed up due to fluidised bed formation. Once cooled, the AC is continuously discharged by a screw conveyor at the outlet. The warmed up air is then filtered at the top of the cooler to prepare it for chilling with a heat exchanger. Because the warmed-up air is nearly saturated, minor quantities of condensate form at the heat exchanger. The remaining water is removed from the circulation air by a drop mister. After passing the heat exchanger, the chilled air is re-circulated by the fans at the bottom of the device.
CONTROL OF TEMPERATURE
Both the alkalicellulose inlet temperature in the inlet conveyor and the outlet temperature are measured. The circulation air temperature is controlled by the required alkalicellulose outlet temperature, which is at the best done with a heat exchanger using cold water or brine. We recommend the control of the temperature of the closed-loop cooling medium using a secondary heat exchanger also using either chilled water or brine.
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