Now Knit RMG (Ready made garment) is the highest foreign currency earning sector of Bangladesh. For knit fabric processing its involves many chemical process, so drying is an important operation. The production of various mechanical finishes on knitted fabric involve conditioning of the material to a certain moisture content and then drying by different means.

2. The application of various chemical finishing and dyestuff
generally involves impregnation of textile materials with
aqueous solutions. This impregnation is followed by removal of
excess water (by padding) then drying. Finally, if required,
curing/backing is done. Now Knit RMG is the highest foreign
currency earning sector of Bangladesh. For knit fabric
processing its involves many chemical process, so drying is an
important operation. The production of various mechanical
finishes on knitted fabric involve conditioning of the material to a
certain moisture content and then drying by different means.
Various Drying System:
Cylinder drying
• Float dryer/ Loop dryer
• Tensionless dryer/Shrink dryer
• Stenter machine
Hot air dryer
Radio frequency dryer
Pressure dryer
Infra-red dryer

8. General remarks on drying techniques
• The drying process aims at eliminating
exceeding water and achieving the natural
moisture content of the fibre. Excessive drying
can negatively affect the final appearance and
the hand of the textile. When choosing a drying
technique, the cost efficiency of the drying
system must be carefully evaluated.
• The cost-efficiency of a drying process
includes many factors such as:
 The quantity of steam and energy required to evaporate
one kilogram of water
 The evaporation capacity of a machine, expressed in
kilograms of water evaporated in one operating hour.

9. Heating of the drying unit
The drying units are usually heated by
means of:
o Steam with an average thermal efficiency of
about 64%.
o Better thermal efficiency is granted by
dryers heated with thermal fluid (about
80%).
o Highly efficient heating is obtained by
means of direct gas combustion, with an
efficiency of almost 95%. The operating
temperature can be reached in very short
times and heating can be done
simultaneously.

10. Drying systems
The water dispersed in a textile material by chemical-physical
process is generally eliminated by the action of hot air, which
makes the water evaporate; during the drying process, it is very
important to carefully consider the way heat is directed on the
fabric. The drying process can be carried out:
- By heat convection
- By contact with heated metal surfaces
- By infrared radiation
- By means of microwaves or high-frequency waves e.g. fabric
and yarn package dryer
- By combustion
Yarns and textile materials in bulk are generally dried inside hot
air compartments. For the drying of piece fabrics, manufacturers
have designed different drying units, which apply different
principles, briefly described here below.

11. Drying by heat convection
The heat diffusion
onto the wet fabric is
carried out by means
of hot air circulating
inside the drying unit.
Employment:Relax
dryer for knit fabric,
Stenter.

12. Contact drying
By this system, the fabric moves forward arranged on
several heated drums or cylinders. The drying temperature
ranges between 120-130° C and the cylinders are heated
by means of steam at a pressure of 1-3 atm. This efficient
and low-cost drying system is particularly suitable for flat
fabrics, which cannot be easily affected by tension during
feeding.
Employment: For Woven Fabric.

13. Infrared radiation drying
Infrared radiation (near and medium infrared field) can be
absorbed by the fabric and transformed into heat which
helps in drying of fabric.
Employment: Woven fabrics and Yarn package drying

14. Microwave drying
By means of radio frequency waves, heat develops inside the material
in a quantity that is proportional to the water dispersed in it. Radio
Frequency penetrates to the core of the product and heat every part
evenly to dry the product especially used for yarn in package form.
Employment: Yarn Package drying.

15. DMS 05 Jumbo Air Relax Dryer
• Origin: Dilmenler Textile
Machinery Co. Istanbul, Turkey
• DMS 05 Jumbo Air Relax Dryer is
economically and ergonomically
designed with latest technological
achievements and it is with up to
72 - 85% of calorific efficiency.
• Process: Drying after dyeing and
impregnating process from wet or
dry fabric
• Working width: 1600-4200 mm,
knitted and woven fabric.
• No of Chamber: min 2 - max 6
chamber
• Heating system: Natural gas,
thermic oil, steam.
• Production speed: 5-80 m/min

16. Variations in Design:

18. DynAir 6500- Relaxation Dryer
Origin: Monforts Fong’s Textile Machinery Co., Ltd. ("Monforts Fong’s") is the joint venture of
the leading German textile machinery manufacturer, A. Monforts Textilmaschinen GmbH & Co.,
KG Mönchengladbach and Fong’s Industries Co., Ltd., Hong Kong established in January
1999.
• Modular Design: The Montex DynAir relaxation drier is designed for both woven and knitted
fabrics with feed either open/wide or tubular form. The models,available in the common nomi-
nal widths, are of modular design. Up to 15% higher drying performance because of higher
number of nozzle elements. Also suitable for integration of a heat recovery unit.
• DynAir 6500 S:
o Single fabric passage
o Fabric inlet from the front
o Fabric delivery to the rear
o Fabric feed in either open/wide or tubular form with one or more webs
• DynAir 6500 D:
o Double fabric passage
o Fabric inlet and delivery at the front
o Fabric feed in either open/wide or tubular form with one or more webs

19. Heating Options
Energy input as required
• Direct gas heating
• Indirect gas heating
• Circulating oil heating
• Steam heating
• Combined electric/steam heating
• Hot water heating
• Electric heating
Nozzle System
“Lay-on-Air” fabric supporting properties
with bulking effect through increased volume.
Advantages
 Attractive cost / benefit ratio is possible due to
faster air transport with microtumbler effect
 Higher evaporation rates
 Continuous fabric support even at the chamber
transition points.
 Reduced energy input
 Gentle heat treatment

20. CADstreamE
The air outlet openings of the nozzles can be adapted
in steps to the fabric width to be treated. Adjustment is
controlled manually or automatically from the central
control desk.
CADstream Slot:
Combined round and slot nozzles. The new
slot nozzle system for high-pile and terry cloth
fabrics. Also suitable for dyeing processes on
the stenter.
Figure: Slot and round
nozzles
Figure: CADstreamE
Conticlean
Circulating air filter system
Belt sieve with automatic suction system and high-
pressure cleaning for constant optimum air
circulation conditions. No energy-consuming air
resistance with increasing sieve soiling. For
constantly high drying capacity, even at high fabric
speeds and extreme linting. For further relief of the
operating personnel from maintenance work and for
lower energy consumption. Figure: Conticlean

21. Lint filter
The lint filters can be removed and cleaned while
the unit is operating.
Integrated heat recovery
With the new integrated heat recovery system,
Monforts is once again underlining its pioneering role
with innovative concepts for more economy and more
ecology. The waste heat produced in the thermal
process and contained in the exhaust air is
discharged via the exhaust air ducts directly into the
air/air heat exchanger. The new Monforts heat
exchanger of space-saving rectangular design
(Koenig system) is integrated into the roof
construction of the stenter. The exhaust air heat is
converted in the heat exchanger to heat up the
process air. The heated fresh air enters the fresh air
inlets of the stenter via integrated fresh air ducts. Up
to 60% of the fresh air required by the stenter can be
preheated in this way. The energy saving lies
between 10% and 30%, depending on the production.
The fans for exhaust and fresh air have variable-
frequency motors.

22. Dryer/Puisetronic
effect
(Bulking phase)
Improvement of the
fabric hand with pulsed
air currents, variable
from 1 to 30 pulses
Fabric transport and counter-holding belts
Twenty to 80 mm stepless setting of the nozzle
and belt distance by motor in each drying
compartment (optional).
With fabric transport belt and driven counter-
holding belt for skew-free fabric transport with
multi-web fabric feed, particularly with tubular
materials.
Special features
Standard design with teflon-coated glassfibre belts. Optionally with special
transport and counter-holding belts and special belt control for particularly delicate
fabrics such as e.g. lace, bobbinet, open Jacquard fabrics.
Advantages
All belt guide systems and the drive and control rolls are located outside the hot
treatment chamber. They are housed in separate frames in front of and behind the
treatment chamber.