Impregnation



Hot impregnation offers several advantages because the Lye penetrates faster & more evenly into yarn core and requires shorter impregnation time of 25 to 30 seconds & ensures even & uniform mercerising effect across the entire width & thickness. Main tank is of robust construction. One of main feature of Dhall design is bottom stainless steel buyoant drums, floating in the liqour & this offers several advantages such as :

• Far superior mercerising effect because displacement / weight ratio of 520 TW caustic liqour imparts a buyoant load of about 50% more than conventional systems.
  
• Since nip line is full sbmerged inside the caustic liqour hence impregnation is always uniform.
  
• No spray pipes are required.
  
• Very little maintenance needed since there are no bearings inside the liqour for the bottom buyoant drums.
  
• Those lower buyoant drums are continuously in touch with top rubber rolls due to their floating condition.
  
• A heavy duty 8 tonnes NIP pressure pneumatic mangle is provide after the impregnation tank.
• Indirect heating system for hot mercerising.
  

Following automation is provided on the impregnator tank (on request) :

• Automatic level control.
  
• Automatic temperature control.
  
• Automatic lye concentration control.
  
• Chiller for cold mercerising.
  
• Wet on wet mercerising system.
  

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Stabilisation

After Caustic impregnation, it is extremely important to carry out stabilising process effectively. Stabiliser section is exactly similar to impregnation section in design and construction i.e. buyoant drums principle. Stabiliser is enclosed to enable attain higher temperature, so that bath viscosity goes down giving better washing efficiency. Suitable filters are provided in the liqour circulation system. Due to positive guidance of the fabric on rolls from start of impregnation up to exit of the fabric from the stabiliser section mangle width loss is minimised. Circulating pumps are arranged alternately to the Io1t & right for effective & uniform lye removal from the fabric during stabilising. This result in optimum dimensional stability of the fabric. Stabiliser section is followed by 8 tonnes NIP pressure pneumatic mangle.

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Recuperation, Washing & Neutralising

For Pre-Wash. Final Wash & Neutralisation, Highly Efficient closed type washing compartments are used. Number of compartments are finalised depending upon each individual production requirements, types & weight of the fabric to be processed etc. Each closed compartment has following salient features : Totally steam tight design to attain high temperature. Top rolls positively driven to minimise fabric tension. Large glass windows provided for easy access & observation of fabric run. Direct/Indirect system heating arrangement. Totally manufactured from stainless steel. Large dia guide rolls for creaseless fabric run. Serpentine flow inside each guide roll in the tank. Counter current flow provided between closed washing tanks. Acetic acid added in the last but one tank or last tank for neutrlisation. Automatic pH controller with acetic acid dosing pump and tank provided for neutralisation (on request). Curved bar expanders are provided before & after each mangle NIP for creaseless fabric run. Each closed washing tank is followed by magale NIP, 2T/ 4TNIP pressure & Last NIP of 6T / 8T NIP pressure. Direct steam injection or fabric.

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