Friday, September 15, 2017

Kier Boiling Process | Discontinuous Process of Scouring | Scouring of Cotton Fabric in Batch Process

Kier boiling:
Kier boiling is a scouring process for cotton and linen in which the fibers are treated for removal of impurities by boiling with a 1% solution of caustic soda. Its main purpose is to remove most of the natural impurities such as wax, wood fragments and oil stains. Kier boiling process of cotton is performed in a kier boiler and the fabric is scoured in rope form by alkali liquor. Kier is a large cylindrical iron vessel. The kier may be open one as closed one and horizontal or vertical.

Open kier: Open kier is not an air tight kier and scouring temperature is 100 oC for 24 hrs.

Closed kier: Closed kier is air tight. Scouring temperature is 120-130 oC for 6 hrs.

Kier capacity: 200 kg – 5000 kg but industrially 2000 kg kiering is very popular.

Standard recipe: The amount of different chemicals used in a kier boiling may vary according to,
  1. Hardness of water
  2. Quality / Quantity of cotton
  3. Fabric construction / texture, yarn twist etc.
But in generally the following amounts of the chemicals are used:
  • Caustic soda (Strong) → 2- 5% owf
  • Soda ash (mild) → 0.5 – 1.0%
  • Sequestering agent → 0.2-0.5%
  • Wetting agent + Detergent → 0.5-1.0%
  • M : L → 1:5 to 1:7
  • Temp → 100 oC – 120 oC
  • Time → 8 hr (100 oC) – 2 hr (120 oC)
Characteristics of kier boiler:
  • Heating is done by using high pressure steam, generated in an independent boiler instead of heating by direct boiler.
  • Iron and steel take the place of wood as the material of construction of kier.
  • Improvement in the handling of the goods by the use of automatic pilling device.
  • Improvement of the circulation of kier liquor through the material by the use of powerful pump.
  • Use of high pressure kier shorten the duration of boiling off and hence saves the cost of the steam, power etc.
Working procedure of kier boiling:
Kier boiling process
Fig: Kier boiling process
  1. Kier boiler is provided two tubes. One is at the bottom and another is top.
  2. There is one manhole for loading and unloading of sample.
  3. Preheater is also provided at the middle of these two tubes.
  4. The liquor is prepared into the mixing tank by above chemicals then it brought into the preheater and heated by the steam.
  5. The fabric is loaded in the machine by man hole and kept in rope form.
  6. Then the hot liquor is pumped and sprayed by spader plate onto the fabric which is packed into the kier.
  7. The temperature of the liquor is about 100 oC and boiling for 8 hrs. the excess liquor passes slowly over the packed cloth and percolates through the false bottom of the kier.
  8. Then this excess liquor is collect at the bottom of the kier and pumped into the auxiliary heater by a centrifugal pump and this cycle is repeat.
  9. Below the false bottom the liquor is free from the oxygen of air.
  10. After scouring, the fabric is washed with 80 oC water otherwise impurities on the fabric would not be removed.
  11. Then the fabric is neutralizing with 0.1%-0.055 acetic acid. And then cold wash.
Precaution:
  1. Kier should be clean.
  2. Material should be packed evenly.
  3. No air pocket should be formed.
  4. The fabric should be immersed in liquor completely.
  5. After boiling the liquor should be removed in absence of water.
  6. Before starting, all the joining parts should be checked.
  7. The joint parts should be leak proof.
  8. Before scouring, the fabric should be starch free.
Advantages of kier boiling process:
  • Material scoured well.
  • Remove most of the natural color and another adventitious.
Disadvantages of kier boiling process:
  • Failure of pressure gauge, boiler may be brust.
You can also like:
  1. Scouring Process in Textile
  2. Textile Bleaching | Bleaching Agent | Estimation of Bleaching Effect
  3. Textile Dyes and Dyeing
  4. Dyeing Defects and Their Remedies
  5. Desizing Process in Textile Industry