Exhaust air filtration & Heat recovery for stenter frames

Exhaust Air Filtration & Heat Recovery for stenter frames

In textile manufacturing processes exhaust air purification can be seen as a particular challenge. Especially exhaust air caused by the application of stenter frames requires a highly efficient separation since the emerging waste air is odour-intensive and made up of wax, oil and fibre particles.

Depending on the production location textile producers are faced with strict regulations in terms of emission limits for stenter frames.

Energy costs account for a large share of production costs

The application of stenter frames is in the field of textile finishing for fabric heat treatment (woven to knitted fabrics) where the fabric is not only dried but also subject to thermo-fixation.

The operating temperature can be up to more than 200°C depending on the actual production mode and fabric. For its operation the stenter requires a high consumption of electrical energy (e.g. for motors and ventilators) as well as a high consumption of heat – as intake for the cost intensive gas and thermal oil heating.

When faced with polluted exhaust air derived from a stenter an unsuitable filter cell would wear out rapidly and entail high cost for filter exchange or replacement. In addition to that the exhaust air of the stenter frame contains valuable heat which can be utilised for subsequent processes.

KMA Filter are suitable for all kind of textile fabrics which are processed in a stenter frame:

  • natural fibers: wool, cotton
  • synthetic fibres: polyacrylic, polyamide, polyester
  • natural chemical fibres: viscose/ acetate

Clean Air. Save Energy.

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With the ULTRAVENT® exhaust air filter system KMA Umwelttechnik delivers an economical and energy efficient solution for stenter frame exhaust air purification.

KMA is pursuing three objectives:

1. Achievement of lowest clean gas values

The exhaust air is profoundly purified by the KMA electrical filter cells before being led into the atmosphere, to avoid nuisances and the emission of pollutants. The exhaust emissions of the production facilities are diminished and external nuisance resulting from air pollution is eliminated.
The strict European provisions and regulations serve as benchmark for minimised emission limits.

2. Reduction of energy costs

By means of the integrated heat recovery system the exhaust heat is efficiently recuperated for the utilization in subsequent processes.
The heat derived from the hot exhaust air can be utilized for the supply air heating which is feeding the stenter frame. Through this efficient heat recovery the operating costs of the stenter frame can be radically reduced due to lower expenses for the conventional heat supply (expensive gas and thermal oil heating). At the same time the recovered heat can be utilized for water heating employed in other production areas (dye house or laundry).

3. Long service life and low maintenance

The KMA exhaust air filter system operated with an integrated cleaning system. The automatic filter cleaning system allows for a regular cleaning of the filter modules while ensuring the full effectiveness of the filter and heat recovery modules.

Less energy consumption means less costs.

Stenter frames

Save up to 80% of your energy costs!

Less energy consumption means less costs.
KMA filter use the valuable heat out of the extract air and reduce the energy consumption of your production facility by means of heat recovery.

How to lower the energy costs of your stenter frame is explained in the following case study.

Filter sizes and modules

KMA ULTRAVENT® systems are available in three sizes with a filter exhaust air capacity of 10,000, 15,000, 20,000 and 30,000m³/h. For larger exhaust air volumes two or more KMA systems can be easily connected to each other.

The KMA exhaust air systems are assembled on a modular system, which combines several system´s components.Therefore ULTRAVENT® system allows a precise adaptation to the needs of the stenter. According to the customer´s request each system can be equipped with several heat exchanger modules. Thus, a KMA exhaust air system with three heat exchanger modules and two electrostatic filter stages is a common example.

Depending on the quantity of equipped module elements the height of the KMA system varies. With a fully equipped KMA ULTRAVENT® the maximum height can be up to 4.4 m. Is there not enough spatial height given in the plant, the tandem model can be selected instead of the KMA standard tower version. For the Tandem model the modular units are divided into two housings, which are connected to each other. In this case, the overall height of approximately 3.5 m is not exceeded. Here, both housings are sharing one automatic cleaning system.


Heat recovery for the heating of air & water

With the energy saving KMA tandem module the recovered heat can be utilized to heat up supply air and process water. As a result, the overall energy consumption of the stenter is reduced, since less energy from the cost intensive conventional heating methods such as gas or thermal oil heating is required.

KMA exhaust air filter in the tandem module are equipped with electrostatic filter cells for particle separation, heat exchangers for heat recovery, an automatic cleaning system for the cleaning of the filter modules and optionally UV-light for odour separation.


Heat recovery for energy saving water heating

The KMA tower module employs the recuperated heat from the exhaust air for the heating of process water. Consequently, the overall energy consumption for water heating used in the dye house or laundry facilities is decreased.

KMA exhaust air filter in the tower module are equipped with electrostatic filter cells for particle separation, heat exchangers for heat recovery and an automatic cleaning system for the cleaning of the filter modules.

Individual solutions for diverse requirements in the textile industry

Depending on the actual application KMA ULTRAVENT® exhaust air filter systems can be equipped with different modular components for the separation of smoke and aerosols and the desired method for heat recovery. According to the client’s desired modular components as well as the available space requirements it is determined which KMA ULTRAVENT® module will be realised. For the textile industry KMA provides two modules: the tandem and the tower module.

Pre-filtration – lint separation:

Processing rough materials from coarsely woven fibres usually create high amounts of lint ball particles. Here, a pre-filtration of the exhaust air is an imperative. Therefore, KMA offers in this case a lint filter. This consists of robust stainless steel wire mesh elements. The special shaping of the wire allows for a high separating capacity for coarse dust particles, for example lint balls.

Manuel cleaning of this modular component is possible. The exchange of the pre-filter is not necessary.

Particle filtration and oil recovery by high-performance electrostatic precipitators

ULTRAVENT® electrostatic filter cells assure the highly effective separation of smoke, dust, and fine mist.

The filter cells are characterized by the particularly robust design: frame and carrying bars made of stainless steel, insulators in oil-resistant ceramics, optimized design for the separation of liquid or viscous substances. These features make sure that the electrostatic filter is an economical and durable filter medium for many applications.
Thanks to the special design of the filter cells the separated oil can be recovered and often be reused.

Heat recovery by highly efficient heat exchanger

During the filtration of the exhaust air the recovery of process heat can be achieved by the integration of a heat exchanger. Industrial exhaust air contains often valuable heat, which can be used for follow-up processes (e.g. heating of supply air or process water). Depending on the actual application there will be choice for either an air-to-air or air-to-water heat exchanger.

Odour Separation – optional UV-Light

KMA offers an optional UV-light module for odour separation needed for particularly intense odours which occur due to the applied chemicals or special fabrics in the textile thermo-fixation.
Many malodorous VOC molecules can be oxidised by means of UV light. The result is a significant improvement of the odour situation. UV light needs like activated carbon a good pre-separation of dust or smoke in order to ensure that its effects are complete. After the UV oxidation state a reaction section is necessary for completing the oxidation process.

Low maintenance by automatic filter cleaning system (CIP)

An automatic filter cleaning system is available for many types of ULTRAVENT® emission control systems. It is suitable for cleaning all washable filter media such as demisters, electrostatic collection cells or UV light oxidation units.

The automatic ULTRAVENT® washing system is unmatched in terms of comfort and cleaning results – due to its movable nozzle bar that moves back and forth above the collection cells during the filter washing process. It allows the regular and labour-saving cleaning of the filter cells and thus ensures minimal maintenance requirements. The intelligent control of the washing system simultaneously reduces the consumption of water and of purifying agents.
The oil recovered in the washing tank is lead to a depot tank via a steam trap and can be reused or is available for sale.

KMA ULTRAVENT® Filters are characterised by following features:

  • Cost-effective operation through wear-resistant filters and low energy consumption
  • Minimised maintenance due to highly effective automatic filter cleaning
  • Flexibility through a modular system with many different sizes
  • Durability: filter housing and collection cells are made of stainless steel or aluminium

Due to the wide choice of filter media the KMA ULTRAVENT® System is very flexibly to use and is also suitable for high filter loading.

The KMA ULTRAVENT® exhaust system allows the highly efficient collection and separation of emissions like mist from release agents, oil mist, plasticizer fumes, and emulsion mist. Due to the special filter design liquid components (oil, emulsion, etc.) get discharged during operation. Adhesive substances can easily be removed by the optional automatic filter cleaning system.

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