s with most of the develop ments shown at the recent ITMA innovation in the drying equipment *sector

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1 Process contro12a*n energy effi ciency 0 A look at recent technological developments in textile dying equipment Five chamber Monforts Montex Stenter with Opti-Scan system installed at Apprets et Teinture de Paris (ATP), France., A s with most of the develop ments shown at the recent ITMA innovation in the drying equipment *sector was largely -. evolutionary. Stenters Stenter developments revolved around improved control of the drying process, and better energy efficiency. Low maintenance features were also prominent, with most companies showing long-life and low/zero maintenance stenter chains. Monforts latest stenter, the 4560, is a completely new design with much better chamber insulation, making it more energy efficient, and better access through larger doors. It is constructed from modular units, combined according to the requirements of the user. The 4560 offers the possibility of integrating the exhaust air ducts into the - machine. This saves secondary installations and prevents heating-up the factory. The system of separating polluted exhaust air from that containing only water vapour is retained. Also featured was Megatherm - a heater element over a chamber length of 6m. Monforts has a variety of air circulation systems on offer, the most technically advanced being the Twin-Air system. This has two fans per stenter chamber. Each fan has an individual pressure chamber forming a single unit with the upper or lower nozzles. The result is completely independent control of airflow to the top and bottom nozzles. It is also available with separate temperature settings for the top and bottom nozzles. Control systems were a key part of last year s ITMA. Monforts showed a Windows-based touch-screen control system on its stenters. The overall architecture of the Monforts systems comes under the heading Qualitex 2000 and encompasses a host of system features: automatic set-up, process optimisation, exhaust air minimisation, and a range of monitoring devices - including the new Opti-Scan. Opti-Scan enables the operator to monitor fabric position in the stenter and thus ensures that fabric passes through the machine at the correct position between the upper and lower nozzle system, over the full width of the frame, without touching. This prevents irreversible overstretching of the fabric caused by an imbalance in the airflow. Optical sensors (pulsed light beam) detect the fabric position in each chamber. These measurements are then displayed as bar graphs on the system monitor, showing the operator which of 9

2 the independent upper and lower nozzles need adjusting. Monforts also incorporated the INTERBUS S technology for controlling drives, fans, etc. This high speed digital data transfer technique dramatically cuts the amount of wiring on the machine and is more precise and reliable. Control systems also played a big part in Babcock's ITMA exhibits. Two versions of its Dasy-Tex system are available: Dasy-Tex M and Dasy-Tex D. Dasy-Tex M is a compact system for simple, practical stenter operation.. Its principle features include: simplification of range operation, process visualisation, complete monitoring, automatic operation at optimal speed, and exhaust air control for best energy efficiency. Dasy-Tex D is a more advanced version offering full computerised control via a menu driven control system featuring customer-specific colour graphic displays Bafxock's Seco-Rad infra-red gas radiation dryer. (1) sealed dryer housing, (2) Fresh/exhaust air convection, (3) exhaust, (4 and 5) IR emitters, (6) coded burner housings, (7 and 8) driver and selfcleaning rollers, (9) fabric run. L. Babcock stenter with Dasy-Tex M control system. of the range. It also incorporates production data logging. Babcock's patented Star-Jet nozzle system and Econ-Air flow control has been applied to a new stenter for knitted fabrics. This stenter also features a new fabric guiding concept with integrated straightening unit, a novel high-performance selvedge dryer, non-stop winder, and lubrication-free vertical chain. Another very impressive, but unrelated, development from Babcock was the Seco-Rad infrared gas radiation dryer for use in paddry and pad thermosol dyeing processes. This featured a new generation of emitter mat based on a 'virtually-massless' fibre material. The result is very rapid heating and cooling allowing the dryer to dispense with complicated mechanisms for protecting the fabric in the event of a machine stop. In operation, the mat heats up from ambient, about 20 C, to 800 C in three seconds. It cools from 800 C back to ambient in about two seconds. Burner fans remain on when the gas supply is cut off in order to help cool the emitters. The result is no fabric burns during machine standstill. The dryer has a modular design with sealed housings. Emitter mats are placed on either side of the fabric drying from both sides simultaneously. Fresh air enters the housing evenly and tangentially across the width of the fabric through an opening at the bottom of the housing. This enhances the drying effect through an exhaust air convection effect. Bruckner's ITMA exhibit of drying equip ment included its new VNE-P multi-layer stenter and heat setting machine. This combines the proven design features and ancillaries of Bruckner's single layer VN type machine with a multi-layer capability to give a compact machine with a large capacity. Available in three- and fivepass versions, automatic control is provided in the form of the new PVS system. A unique system of infra-red electric heating panels which provide a 25% reduction in power consumption are among the outstanding features on the latest version of the Bates HE Mini Stenter. The infra-red heating technique, using panels that have a reflected heat efficiency of 98%, controls the temperature of the fabric itself not the air in chamber. This enables energy consumption to be kept to a minimum - power usage is usually only 1Kw per 20m of fabric throughput, says Bates. A temperature control system enables the infra-red wavelengths to be set to suit the type of fibre being processed. Rapid cool-down of the infra-red panels is provided to protect the fabric in the event of a machine stop. Fabric speed is 11

3 controlled independently and the required full speed can only be obtained when the correct processing condition has been achieved. This unique fail-safe system reduces fabric and energy wastage to an absolute minimum. Two automatic heating systems are available: one raises or lowers the temperature, according to the type of fabric, at a fixed speed, the other keeps energy input constant and varies the machine speed to suit the fabric temperature. In addition, it is possible to raise the fabric temperature from ambient to maximum: (usually 200 C) in about 15 seconds - and reduce it back to ambient in just 10 seconds. Constructed in four sections (fabric presentation, edge control and pinning, heat setting and cooling, fabric removal and strip return), the HE Mini Stenter can be supplied in versions with 2, 3, 4, 5 or 6 heating bays, for knitted and light woven fabrics of up to 2.4m wide. Production speeds up to 30m/min. depending on the nature of the fabric under process, are possible. Wet fabrics are usually processed at production speeds of 3-6 m/min., dry fabrics at 6-15 m/min. Tumble dryers A recent development from Danish company Henriksen is the SoftSet Combi - a versatile tumble dryer. The same machine can be used for one drying passage or several softening passes. Both thin knitted goods and heavy woven fabric (up to 800g per running metre) can be dried and softened making the SoftSet a very efficient and versatile machine, says Henriksen. The SoftSet Combi has eight tubes. When fabric needs one passage through all eight tubes it is fed in by an entrance winch at the front of the machine over a magnetic seam detector and then travels the complete length of the machine before being deposited in the first of the eight scrays. During the drying/tumbling process the fabric proceeds through each of the eight tubes/scrays in turn before exiting through the end of the machine close to the entrance port. The front and sides of the machine are made up of doors for easy access to the internals of the dryer. This feature enables easy intervention should it be Above: Fabric transport through Monforts DynAir Relaxing Dryer. Right: Arioli s new Model AFR conveyor dryer. required and excellent access for maintenance. According to Henriksen the machine is not prone to fabric tangle and knot formation. The content of e-ch fabric scray is measured and mai d by sensors giving a signal to the..,dividual frequency controlled motors to ensure a constant loading in each fabric compartment scray. This ensures a smooth running of the fabric and an even high impact output. The SoftSet Combi is equipped with an automatic air filter. The air is recycled inside the machine through a drum in the back whereby lint is deposited on the outside of the drum. A vacuum system continuously removes the lint from the drum and transports it to a compactor, where it is packed together and discharged. The machine operates at a maximum 140 C and a fabric velocity up to 300m/min. Its maximum evaporation rate is 160kg/hr. and productivity is about 320kg/hr. of fabric. As detailed last month in the first of International Dyer s ITMA reports, many manufacturers of fabric piece dyeing equipment have developed tumbling/ drying options/models to their machines. These included: Thies roto-tumbler, Then Airflow AFS+T and the Krantz Aero- Dye. These machines are visually very similar to a conventional jet dyeing machine but have the added capability of a hot air blower system, achieved by various means. The Thies roto-tumbler is a spin-off of the well-known eco-soft dyeing machine. It is intended for fabric surface effect and enzyme treatments. The machine operates in pressurised condition increasing air density and resulting in faster and more efficient heating, thus reducing process time. Temperatures up to 130 C are possible and fabric speeds up to 1000m/min. during tumbling. Thies says that the roto-tumbler offers considerable savings in steam (50%), power (30%), and process time (30%) over conventional tumble dryers. Then added the +T (tumbling) module 12

4 to its Airflow AFS dyeing machine. The tumbling module comprises a heavy duty air heater and controls, and a series of valves to alternate the airflow in the blower circuit. Tumbling at temperatures up to 140 C is possible, as is steaming, moistening and chemical finish application. Krantzs Aero-Dye machine is available with either a tumbling option, which involves only a small amount of conversion work, or a drying and tumbling option which necessitates substantial alteration to the dyeing compartment. IR both cases the configuration of the dyeing machine is not altered so its dyeing characteristics are unchanged. Tensionless dryers The recently launched Krantz Syncro is intended for knitted and woven fabrics, in both tubular and open-width form. It is designed to assure controlled shrinkage and, in combination with a tumbler zone, develop volume and improve feel, says Krantz. Fabric passes through the machine on a screen belt. A low tension take-up and infeed can be adjusted to provide an overfeed of up to 200%. Fabric is dried continuously-by heated air as it passes through the machine. Circulating air is fed simultaneously into the nozzle 4 Krantz synchro dryer. systems above and below the fabric web. - ishing lines. The machine uses Babcock s patented Star-Jet stepped nozzle design and its Econ-Air air flow control system. It can switch between rebound-jet or permeation drying depending on the type of fabric being finished. Heating comes from a fan-assisted gas burner. By continuously adjusting the intensity of air delivery the dynamics of the fabric movement in the dryer can be controlled. This offers the versatility of a combination of dryer and tumbler: the Syncro dryer in the first drying section and a Syncro tumbler in the second. Here, the first drying zone produces a certain shrinkage effect at a high evaporation rate. Whilst in the tumbler field, fabric is moved by a special circulating-air control system. This results in lower residual shrinkage, increased fabric volume and a noticeably softer feel to the product. The speed of this tumbler process is adjustable. Monforts showed its DynAir 4565 Relaxing Dryer for the first time at the ITMA in Milan. Described by the company as a new generation of pulsed dynamic relaxation dryer it is intended for comfort-finishing of knitted fabrics in either tubular or open-width form. A special air guidance system means that the Bisio/Stalam Vapodry RF/T fabric drying machine. fabric travels through the dryer in a sine wave pattern. The strength of the pulsec air jets beats the fabric against the Imer transport belt and the upper restraining belt. This strong movement brief11 loosens the thread crossing points ana achieves optimum relaxation and shrinkage results in both the longitudinal and transverse direction. DynAir is available in a range of single and multi-layer configurations. It can also be combined with other Monforts finishing equipment to form continuous fin- Arioli presented its new Model AFR con veyor dryer at the recent ITMA. This tensionless dryer is suitable for woven and knitted fabrics (including tubular knits) says Arioli. The machine has a modular construction with a fan, easy clean air filter and one heat exchanger in each 2m section. Each section is individually temperature controlled via a digital system. It has a high drying capacity of 150kg of water per 2m section. Fabric runs between an upper and lower conveyor. An air percussion technique through both the upper and lower conveyor undulates the fabric. This achieves the maximum possible shrinkage of the fabric, says Arioli. The conveyor belts are made of a polyester net with some Teflon coating. The machine can be heated with either: steam, diathermic oil or direct gas burners. A double passage model is also available. This has an evaporative capacity up to 800kg/hr. Optional extras include: exhaust air humidity control, an infra-red fabric residual humidity detector which can be used as a feedback device to control the conveyor speed, and a gas detector which prevents high concentrations of dangerous gases building up when the machine is used for polymerisation of resins. Radio frequency One of the most significant develop ments in Radio Frequency (RF) drying technology to come out of the recent ITMA in Milan was the Vapodry RF/T - a RF system for fabric drying produced in collaboration by Italian companies Stalam and Bisio.. According to Bisio, the Vapodry RF/T combines an efficient but gentle low 14

5 temperature drying action. This dries fabric thoroughly without affecting its natural softness. In addition to this the system also envelopes the usual energy efficiency advantage of the RF technique. Drying is perfectly uniform, tension-free and maintains the clarity and brightness of any dyed shade, says Bisio. The machine is very compact and its modular construction means that it can be built to suit any production requirement. The unit can be used on its own or in combination with conventional dryers. t Strayfield Ltd. has recently launched a new compact RF drying system, the PS12T BatchDryer. Capable of the same flexibility and pre cision as Strayfield s higher capacity conveyorised dryers, the PS12T is equally low on energy consumption and is aimed at the smaller dyehouse. Controlled by the company s MAC 40+ Automatic Operator System, it requires no operator supervision other than loading and unloading. The MAC system is capable of immediately identifying any fault in the system and providing a list of check items to rectify it, and also of prompting the operator when routine maintenance is required. New developments to air flow and moisture extraction systems ensure the Fastran PAG6O CoolDry RF dryer at Colourflex, UK. J -1 Strayfield s new PSl2T Batch Dryer.. PS12T performs to full efficiency even in extreme climates. In addition to carrying the CE Health and Safety mark of compliance, it meets the strictest radio frequency emission regulations, namely CISPR11, AS2064 and FCC, says Strayfield. Although RF drying of yarn and tops is now well established, there has always been the problem of heat bhild-up within a product subjected to a conventional radio frequency drying, says Fastran Ltd. To get around this problem, Fastran s new Cool Dry system maintains product temperatures of 60 C and less during the drying cycle, eliminating heat build-up problems whilst providing all of the advantages associated with radio frequency drying. The system also affords a number of additional benefits. No centrifuging is required before the drying process, since the packages or tops are loaded directly into the CoolDry from the dyeing machine, eliminating possible package distortion and yarn damage during the centrifuge operation and leading to greater efficiency during back-winding, weaving and knitting. On bleached whites, optical whites or pastel shades there is no yellowing or discolouration, as is often the case with low temperature processing, says Fastran. There is also no dye migration, and the continuous movement of air through the product gives it greater loft and ultimately a better handle. A traditional back-washing range incorporated into the process route for drying tops is unnecessary with the CoolDry, allowing a further cut in costs to be made. In CoolDry, packages and tops are loaded by means of a twin tray shuttle arrangement which allows one batch to be dried as the next is being loaded for automatic transfer into the dryer. Initial moisture content is removed by a positive displacement vacuum prior to the dual application of both radio frequency and vacuum for the remainder of the process. The company has recent installed CoolDry machines in the UK, USA, Turkey, China, Malaysia, South Korea and Vietnam.0 16