Tunnel washers

Cutting water, energy and labour costs

25 March 2010

The efficient use of resources is the major influence on modern tunnel washer design. Tony Vince reports on current developments

The need to make more efficient use of labour, water, energy and chemicals continues to be the main influence on the laundry market and this has a significant effect on the choice of tunnel washer.

One year ago LCNi reported on how the recession was affecting purchases in the laundry sector. According to Jordi Martinez, product manager for Girbau’s heavy-duty division, the tunnel washer market is one of the sectors that has been least affected by the economic downturn. He says that one of the most significant advantages of tunnel washers is that they reduce labour costs.

“Currently, customers with a medium capacity are considering the installation of medium size tunnel washers, ranging from six to 10 modules,” he says. Even at the industrial end of the market, Martinez believes that customers with large outputs “are considering installing tunnel washer systems to reduce costs for labour, energy and water”.

Girbau developed its TBS50 tunnel washer to respond to modern laundry demands and adapt to the future requirements. The modular system of the TBS50 allows it to be adapted to many installation types, including hotels, hospitals and industrial laundries.

The tunnel washers use a double outer-drum that guarantees greater control of the temperature both throughout the process and during the disinfection and descaling of the machine. Martinez adds that Girbau also observes that many middle capacity laundries are interested in tunnel washer systems and it aims to provide them with systems that will meet their needs at an affordable cost. Some small and medium industrial laundries are benefiting from a move to sub-contracting and are investing in tunnel washers to become more competitive, he says.

Martinez says the trend going into 2010 is for laundries to achieve a more efficient use of resources. He reveals that, as part of the company’s ongoing commitment to continually improving wash processes, Girbau is developing an energy efficient drain-intercooler.

Martinez also says that Girbau is currently working on the filtering systems that will provide more efficient recycling of water and so achieve water savings.

“We will work to continuously improve our products and we employ a highly qualified team of engineers devoted exclusively to the tunnel washer project.”

Jensen is another company that is committed to product development that optimises energy efficiency for the entire laundry. Energy saving is a significant trend not only for the tunnel washer line but throughout the laundry.

The company also notes that laundries will continue to become more specialised to achieve greater cost reductions whilst improving productivity and quality in their strategic business field. According to Kathrin Scheffel, Jensen’s director of garment technology, there are more and more larger laundries handling a high volumes in each operation and that have a more specialised production. Jensen has responded by developing machines for specific requirements, she says.

To meet the demand for tunnel washers that can handle these large batches, the company has developed its Senking MaxiLine for batch sizes up to 120kg and an hourly capacity of around 5,000kg. Jensen has also produced machines for dedicated linen categories. These include the HighLine tunnel washer, which has a rotational drum that can be switched from a swivel action for lightly-soiled loads to a rotating action for heavily-soiled loads such as industrial workwear, dustmats, mops and kitchen linen.

In addition, the SilverLine tunnel washer is ideal for lightly-soiled loads such as hotel linen.

Scheffel points out that Jensen is also seeing smaller laundries, which have traditionally usedwasher-extractors, begin to invest more and more in tunnel washers “to reduce costs and to improve the production flow”. The company developed the Senking CompactLine for a production capacity of up to 600kg/hour. This system has bath separation that provides greater flexibility and improved recycling.

In the longer term, Jensen believes there will be even more demand for energy and water saving technologies, especially given rising energy prices and the unstable economic situation in many countries. Recognising this, Scheffel says that Jensen’s most significant product development has been its CleanTech system: the integration of tunnel washers into a decentralised energy supply, either steam-free with gas-fired heaters or by means of decentralised steam generators. To date, Jensen has delivered 15 CleanTech tunnel systems and expects to install more in 2010, says Scheffel.

Switching to gas

The Jensen CleanTech concept is aimed at switching the various laundry equipment components from steam to direct gas heating.

The company has worked closely with industry partners such as Ecolab and Christeyns on developing steam-free laundry applications.

Ecolab has developed the Aquaheater, a gas-fuelled boiler that can be used for fresh water and also, when combined with a filter system, for heating process water. This allows the tunnel washer’s wastewater to be filtered and recycled.

Steam-free operation is offered as an option on Jensen’s Universal, Universal SL and HighLine tunnels. The tunnel washers are equipped with the Aquaheater, which heats up the process water in the compartments that were previously injected with steam. In this way, the same amount of energy is supplied to heat the process water up to the required temperature.

Maximum energy savings are obtained by combining a low-temperature wash process with Jensen’s integral Spiraliser tube-in-tube heat-exchanger. Depending on the process temperature, this can save as much as 0.15kWh/kg of energy.

Detergent suppliers recommend operating the tunnel washer at lower temperatures. By washing at approximately 60C to 65C using the special low-temperature process, energy consumption can be reduced by 0.1kWh/kg compared with conventional wash programs that operate at 85C.

At the Ardennes & Meuse Laundry (A&M Blanchisserie Basse Meuse) in Belgium, the Broers family have built an automated, energy-efficient laundry where steam is reduced to an absolute minimum. One small steam boiler is now all the laundry requires.

It operates two Jensen Senking Universal P5013 tunnel washers, set up in conjunction with ten Senking DT60 dryers and ironers supplied by Lapauw, all of which are gas-heated.

Bed linen and towels are washed in the gas-heated tunnel washers using a low-temperature (60C) process developed by Christeyns. Table linen is washed at higher temperatures in A&M’s steam-heated tunnel washer.

Pellerin Milnor, the New Orleans- based international manufacturer that has made tunnel washers one of its main lines, reports that in many regions of the USA environmental impact charges for new laundries are very expensive. Therefore modern laundry designs employ water-saving features, including the use of recycled water.

Save more water

Milnor has now developed and patented a water flow configuration that is designed to generate even more water savings beyond those already obtained by its established CBW tunnel washers.

Karl Schubert, general manager, says Milnor has continued to develop its tunnel systems to reduce water consumption.

“The Milnor CBW tunnel washer has been used for more than 20years to wash industrial workwear and dustmats as well as normal hotel- and hospital linen and continuous roller towels,” he says. He adds that because the machines are easily adapted for every task, a laundry can wash any item in Milnor CBW washers.

An example of a Milnor installation can be found at Brady Linen Services. This family-owned and operated linen supply company has been serving the Las Vegas area since 1999, processing over 320,000lb of linen per day and over 100million lb of linen per year.

The company has expanded by opening larger premises that effectively doubled its original capacity to almost 450,000lb per day.

Brady installed two 16 module Milnor 76039 CBW tunnel washers each with a 150lb capacity, in addition to a Milnor 50bar press, 13 Milnor 64058 natural gas dryers and the Mildata Computer Network. According to Brady Linen, the product finish achieved by the Milnor CBW tunnel is of higher quality than that produced by a washer-extractor.

In addition, wash times in a Milnor CBW tunnel washer are reduced to less than 18minutes compared with a washer-extractor where the typical wash cycle for sheets would have been a 45 – 50minutes.

Looking ahead, Schubert says that while the economic downturn had an effect during 2009, with demand down by at least 25%, there has been a significant upturn during the final quarter of last year that seems to have continued into 2010.

“The most significant development for our CBW tunnel washer system in 2009 has been the invention and development of the company’s patented PulseFlow. The PulseFlow technology achieves as much as 70% water savings without employing extensive recycling systems,” he says.

PulseFlow technology, which has been in development for two years, takes advantage of Milnor’s top transfer design and employs high velocity pulse rinsing to achieve very low water consumptions. A standing bath increases the effectiveness of wash chemicals.

PulseFlow reduces the water consumption to around 2.3litre/kg for 100% cotton and 1.25litre/kg for polyester/cotton adds Schubert. He adds that this system has also been applied to the small CBWs that are becoming increasingly popular, not only in smaller plants, but also in big plants that require a machine for handling special items.

Milnor continues to develop energy-and water-saving systems for CBWs, and also for washer-extractors.

Controlling costs

According to Kannegiesser in Germany, modern laundries can take greater control of their costs by integrating the separate functions of washing, rinsing and extracting in one unit.

Kannegiesser designed its PowerTrans tunnel washer for various applications – as a bottom transfer machine with oscillating wash action, and as a top transfer machine with rotating wash action.

The company says that better usage of the wash liquor, which is usually adsorbed in the linen, is an increasingly important factor in the wash process. It explains that the aim should be to remove this liquor prior to the rinse process and then re-use it in following wash processes and to improve dilution during rinsing. A conventional washer-extractor can extract the adsorbed wash liquor by pre-spinning before the rinse process, which was something that a tunnel washer couldn’t do.

Kannegiesser’s development of the Jet system now allows PowerTrans batch washers to pre-extract the free and adsorbed main wash liquor, with the main wash liquor extracted at up to 800G. Like a squeezed sponge, the compressed textiles will adsorb the fresh water from the following rinse process in an extremely short time.

In most cases, 3litres of fresh water per kg loading is sufficient to dilute the remaining adsorbed liquor – the dilution factors are considerable better than with conventional rinse processes.

Black and White of Germany produces tunnel washers ranging in load size from 36 – 100kg and five to 20 compartments long – the large 20 compartment 100kg tunnel can process up to 4,000kg per hour. The machines can be adapted to suit most applications – with flow, standing bath or counter flow – to provide the most suitable wash/mechanical action for high quality results whilst minimising energy and water costs.

Changes in design

Black and White machines are available in the UK through Broadbent Laundry Systems, where Chris Leeper says that the last two years have seen several changes in tunnel washer design, aimed primarily at reducing manufacturing costs and at introducing innovative design for water flows.

After the early basic single drum design “counterflow machines” of the early 1980s, there was a move to a double-skin construction that provided more flexibility in process control, bath exchange and direct heating.

In the 1990s manufacturers significantly reduced production costs by returning to a single skin with the simple “with flow” or standing bath design for the pre-wash and main wash. However, the design had a mixed reception amongst European launderers, particularly those requiring high quality wash results, says Leeper.

To reach the wider market and provide equipment for the complete spectrum of laundry types, some manufacturers of the double-skin machines introduced design features that improved mechanical action, provided more efficient rinsing and higher levels of rinse and press water recovery as standard.

Three flow types

Black and White’s latest range of continuous tunnel washing machines combine the three types of water flow arrangement with the same basic design. Its latest Smartline washers can be manufactured in standing bath or counterflow design. They are built with either single-skin or double-skin construction to meet all market requirements. The dual heavy-duty inverter-controlled motor provides a smooth reciprocating action to maximise mechanical action.

Bath level control and an efficient recovery system provide economical water consumption, even for heavily-soiled classifications, whilst the Smartline drum is constructed so that the gap between inner and outer shell is no more than 20mm, so ensuring that most of the wash liquor and heat is kept with the linen.

The double-skin construction and standing bath design of the Smartline Deluxe model can process very heavily soiled linen and is able to release the soiling continuously as the linen transfers through the machine, so reducing problems with redeposition and improving the final rinse efficiency.

Heating can be added in any compartment to suit the customers’ process requirements. Incoming fresh water is pre-heated by built-in heat-exchangers whilst recycled water is cooled to prevent stain setting.

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