March 11, 2008

Cabinet Yarn Dyeing - Sequence of operations

Generally in cabinet yarn dyeing machine, cotton, acrylic, jute, flax and coarse natural fibers can be processed in hank form.

For Cotton yarn processing, the general sequence of operations are as below:

(1) Load the machine with yarn -> (2) Scouring and bleaching -> (3) Hot wash -> (4) Cold wash -> (5) Neutralization -> (6) Peroxide kill -> (7) Cold wash -> (8) Dyeing -> (9) Cold wash -> (10) Neutralization -> (11) Cold Wash -> (12) Soaping at boil -> (13) Hot wash -> (14) Cold Wash -> (15) Softening Treatment -> (16) Unload.

Out of the 16 operations, the (1) and (16), do not consume water. The other 14 operations mean, 14 times the machine has to be filled with fresh water. If for example, we dye a 100 kgs batch at 1:15 liquor ratio, then the water consumption will be 1500 liters per bath and for 14 baths, it will be 14 x 1500 = 21000 liters. That mean, for processing 1 kg of yarn, it requires 210 liters of water. This is a very high volume, in these days of water scarcity. So the following measures are being adopted in this industry.

  • Wherever possible, the dyeing units have started disposing off the old, high liquor ratio machines and buy new low liquor machines. Now 1:12 MLR cabinets are widely used everywhere in this industry. Straightaway 20% water saving is achieved.

  • Wherever possible, the dyeing masters have implemented reduced number of baths, with new auxiliary chemicals. For example, bio scouring and bio-peroxide killing is new emerging process, where you need not do separate cold and hot washes after scouring and there is no need for separate bath for residual peroxide removal. This process eliminates almost 3 baths with a saving of again a 20% water.

  • Using suitable good soaping of agents of anionic nature, one can easily acquire the soft feel and finish required by the end user. This also reduces one more bath.

This high volume of water consumption, not only adds to the water cost, but also to many other indirect costs like energy cost - steam to heat the water and power to pump in the water, extra dosage of dyes and chemicals to maintain the bath concentration and effluent treatment of excess water that is being let out.

1 comment:

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