Textile - BEP

Introduction

During the 1970's and 80's, the textile industry has endured a period of traumatic changes. Many long established plants have closed, and those remaining have perforce had to become more efficient. New textile plants have opened, in many cases at locations close to the source of their raw materials. The new plants too must constantly seek improved performance and efficiency if they are not in their turn to fail. A rapid response to changing consumer preferences is essential - as is the containment of manufacturing costs. A flexible and efficient use of steam can play a vital part in meeting these needs - and Spirax Marshall has the products and specialized knowledge and experience in this field.

Which products are useful in what process of production?

Sizing

The size is mixed and steam heated in special vessels for which control and trapping equipment will be required. Temperature control of the size tank on the machine will also be necessary. For trapping, Steam Trap Modules are the best choice, including Strainers, Float Traps, Spiratec and Isolating Valves.

The steam heated cylinders are often limited to a pressure of 4 bar and there will be a temperature gradient along the machine. Pneumatic controls can be used but considerable success has been achieved with Pressure Reducing Valves (DP17R) on individual, or group of cylinders.

Mercerizing

Some of the used tanks will be steam heated by coils or direct injection and Self Acting Temperature Control equipment will be required. Squeeze rolls between each tank will be pneumatically controlled, and equipment for conditioning the compressed air (Compressed Air Service Units) is essential.

Scouring

Self Acting Temperature control and trapping equipment will be required for each wash tank. Squeeze rolls between each tank will be pneumatically controlled, and again equipment for conditioning the compressed air (Compressed Air Service Units) are needed.

Washing

Self Acting Temperature Control equipment will again be required for the hot water tanks, while Strainers in process lines can help prevent blocking of spray nozzles and valves, minimizing down times.

Drying

Drying is carried out by passing the cloth over banks of steam heated drying cylinders. A temperature gradient is often maintained across them and are ideal for this application. Draining of the cylinders will be through siphon pipes and steam lock release traps, like System Units with Steam Float Trap with Thermal Vents and Steam Lock Release will be required.

Dyeing Process

Typical Processing of the polyester content consists of passing the fabric through a tank of dye followed by partial drying by gas fired infra red dryers (gives more even drying than steam cylinders) followed by a final drying over steam heated cylinders typically controlled and trapped by DP17R Pressure Reducing Valves and Float Traps.

Energy Monitoring

Textile mills taking necessary steps to maximize use of available steam, may consider monitoring their usage for any given area or machine.

The Spirax Marshall Steam Meter installed in the main steam header or in branch lines will provide metering flexibility, so that a close watch can be kept on any or all areas of mill steam usage.

Support Systems

Hot water is required in many process areas. Water is generally heated with steam and stored in volume at high temperatures. Hot water storage tanks are often scattered around mill buildings near major areas of use. Each provides application needing Pressure / Temperature Controls, condensate return and accessories (PPPPU).

Packaged Plant Room System and Textile waste heat recovery units are best systems for compact hot water generation systems.

Compressed Air

Compressed Air is used mainly as a motive force to actuate the process control valves and machines in a textile mill. Efficient operation requires that the system be free of dirt, oil and water. Strainers,Separators and Air Drain Traps should be installed in front of control valves and process machinery. Compressed air receivers inter and after coolers also require moisture drainage. There is also need for Spirax self-operated control valves to modulate the compressor jacket cooling the water.

Space Heating and Humidification

The need for space heating is met with forced air duct type systems or individual unit heaters generally supplied with low pressure steam. They may be on/off thermostatically controlled.

Humidification is usually essential in this industry. Constant fibre characteristics require control of air temperature and humidity. Duct type or room type Steam Humidifiers installed in process and bulk storage areas assure good fabric sizing, fabric bonding and size.

Condensate Return and Flash steam Recovery

Flash steam recovery is effective where there is a large demand for low pressure steam. Medium pressure condensate returned from dryers, heat exchangers, tank coils, etc. to Flash Vessels produces more than enough flash steam of adequate pressure for unit heaters, process and domestic hot water heaters, wash and bleach tanks, etc.

Mill managers should be encouraged to recover as much condensate as possible to reuse valuable treatment chemicals and water as well as make fullest advantage of remaining latent heat found in the hot condensate. These savings are compounded, of course, if plants are using the Pressure Powered Pump with its trouble-free maintenance saving design and low cost of operation, using readily available steam or air as motive force.

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Steam Generation Steam Distribution Steam Utilization Condensate Recovery