Saturday, August 26, 2017

Textile Drying Machine and Drying Process in Textile Industry

Drying Machine:
In wet processing industry drying machine is used after de-watering of fabric. In textile finishing unit; dryer uses for dry the knit, woven fabrics and dyed yarn. We can define drying as a process where the liquid portion of the solution is evaporated from the fabric.

Objects of Drying Machine:

  1. To dry the fabric with help of steam
  2. To control the shrinkage
  3. To prepare for next subsequent process
  4. To dry tubular and open width fabric without tension
Dryer Machine Specification:
Tensionless Dryer Machine
No. of the machine
02
Manufacturer name
Lk &LH.co
Country
Taiwan
Heating arrangement
Steam
Maximum width capacity
330 cm
Used Utilities
Water Electricity, Compressed Air
Speed range
8.8 m/min
Heating range
110-150 0C
Chamber
04
Table: Machine specification of Tensionless Drying machine

Fabric path diagram of textile dryer:

Fabric path Dryer
Fig. Fabric path Dryer
Main parts of the machine:
  1. Heating chamber (2)
  2. Blower
  3. Synthetic blanket as a conveyor
  4. Folder
  5. Exhaust fan
Heating arrangement:
  • Heating chamber: 2
  • Heating system: Gas fired
Function of Textile Dryer:
  1. In case of Tensionless dryer, drying of fabric is carried in relaxed/tensionless state, which is suitable for Knitted fabric.
  2. Two mesh conveyors are placed length wise to the chamber named upper & bottom conveyor and they are endless and made of taflon,under the bottom conveyor there is a vibrator which makes the fabric more relaxed.
  3. There is a steaming zone which causes more shrinkage of fabric, hot air is circulated by fans .
  4. To control the shrinkage
  5. To prepare for next subsequent process
Utility:
  1. Gas (to make fire)
  2. Electricity (to rum the machine)
  3. Compressed air (to spread the fire)
Remarks: If moisture content of air is less, more energy is required to heat up the atmosphere and vice versa. So optimization of moisture of air is needed, by controlling the speed of Fabric or Fan.

Drying process in textile industry:
Drying is very essential in textile industry to eliminate or reduce the water from the fibers, yarns and fabrics following wet processes. Drying happens when liquid is vaporized from a product by the application of heat. Drying, in particular by water evaporation, is a high-energy-consuming step although overall consumption may be reduced if re-use/recycling options are adopted.

Drying methods:
Fiber, yarn or fabric can be dried with mechanical or thermal process. Mechanical processes are used in general to remove the water which is mechanically bound to the fiber. This is aimed at improving the efficiency of the following step. Thermal processes consist in heating the water and converting it into steam. Heat can be transferred by means of:
  1. Convection
  2. Infrared radiation
  3. Direct contact
  4. Radio-frequency
Drying techniques depend on packages. Loose fiber can be dried in three ways:
  • Centrifugal extraction
  • Mangling
  • Evaporative drying
In other way, hanks may be dried by employing a dehumidifying chamber. Moisture is recovered by condensation, using conventional de-humidification equipment. In comparison to evaporative dryers, yarn residence time tends to be longer, but energy consumption is lower.

Yarn packages drying:
The moisture of dyed packages is initially reduced by centrifugal extraction. Specially designed centrifuges, compatible with the design of the dyeing vessel and yarn carriers are employed.

Fabric drying:
The drying process for fabric usually involves two steps: the first one is aimed at removing water which is mechanically bound to fibres, while the second one is necessary to dry completely the fabric.
  1. Hydro-extraction by squeezing
  2. Hydro-extraction by suction
  3. Centrifugal hydro-extractor
  4. Stenter process