Loris Bellini
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CASTO Linen sliver scouring and bleaching plant

LINEN SLIVER SCOURING AND BLEACHING PLANT

Scouring and bleaching are basic steps in the linen spinning process; up to a few years ago, scouring was a separate process from bleaching. Primary scouring used to be done during spinning; for this reason hot spinning (at 65-80°C) was performed, while bleaching took place on conical packages of spun yarn in separate bleaching plants, i.e., in plant specializing in the wet treatment of textile fibres.
In Europe, chiefly Italy and France, this service was generally subcontracted to decentralized factories operating as commission dyers.

This traditional procedure involved a number of important disadvantages: wet spinning had to be performed at a high temperature (65-80°C), with consequent significant energy consumption for water heating. More important, the environment was ecologically endangered, and the very high temperature and humidity in the spinning department were almost unbearable to the workers. All the above spelled lower spinning output due to poor efficiency of in-line scouring and lower labour productivity due to poor environmental conditions.

Furthermore, a first time the yarn coming from the spinning frames had to be dried prior to cone winding and a second drying operation was required after bleaching in package form.
The full process therefore included two energy-intensive and costly drying stages.
Further cost items were packaging, handling and transport of spun yarn cones to the decentralized bleaching plant and labour intensive cone loading and unloading on the autoclaves carriers.
Another point not to be neglected is that decentralizing the various stages of the production process involved significant planning problems, hidden costs and generally longer manufacturing times.
A thorough technological research was made to overcome the problems connected to the traditional process by means of scouring and bleaching tests on the silver i.e., on the fibre in the intermediate stage between preparation and spinning, which yielded very attractive results.
When suitable treated in special scouring and bleaching machine with a suitable engineering of liquor circulation system characteristics, the sliver does not degrade; intensive removal of the natural fibre binders during scouring and bleaching improves wet spinnability and allows for a substantial reduction of wet spinning temperature from 65-80°C to cold spinning.

In order to exploit all the advantages of sliver scouring and bleaching while doing away with the disadvantages, Loris Bellini has developed the specialized linen scouring and bleaching plant ” CASTO 6 L”.

MODULAR CARRIERS

The machine can accommodate 6 modular carriers suitable for sliver cops
of various standard sizes. The carriers are lifted with a hoist and placed in the machine; they fit in seats prearranged on the vat bottom to close the hydraulic circuit for liquor circulation.
The seats are interconnected by a large cross-section manifold, which in turn is branched on a specially designed liquor
circulating pump.

CIRCULATION PUMP

The pump is specifically designed to operate at low head pressure and high flow rate.
A smooth and steady liquor circulation with a limited pressure drop is obtained: this means low
installed power.
The treatment vat also embodies an indirect heating coil to supply process heat; two overflow washing devices are installed on the upper side rims for continuous rinsing.

VARIABLE CAPACITY

When the rod is not completely filled, the treatment bath level is adjusted to preserve liquor ratio, thereby
safeguarding formulation validity and saving energy.
The liquor ratio is adjustable from 1:8 to 1:11.

Advantages:

  • Low Energy consumption thatnks to the cold spinning
  • Better ecological environment
  • Spinning machines are more efficient thanks to improved degumming and bleaching processes
  • Improved working conditions
  • No drying phase requie after bleaching will save Energy consumption
  • No external transportation
  • Elimination of high loading/unloading costs.
  • Very low consumption of electricity for bleaching by using special pumps