Dryers

Speed and Efficiency

1 November 2010



Manufacturers must combine heat, airflow and tumble actionto produce the fastest and most efficient drying results


Increasing utility costs have spurred laundry equipment manufacturers to focus even more on efficiency in their designs. However, it is up to laundry managers to ensure that the dryers continue to operate efficiently after installation.

According to John Balman, senior director of sales in Europe for Alliance Laundry Systems, operating efficiency is now, and will remain, the main trend influencing buying decisions. He says that while customers will be concerned about purchase price, the savings that a highly efficient Alliance tumbler can produce over its lifespan far outweigh the purchase price.

“The other key trend that’s important to customers is low maintenance,” he says. “Buyers today want machines that are not only durable, but relatively maintenance-free. That means keeping tasks such as emptying lint drawers down to once a day, versus after every cycle, which keeps staff more productive.”

He says it is important for laundry managers to understand the value of balance in the drying process. Some might favour increased heat to obtain fast dry times as the most effective drying method. “However, any savings in time are quickly offset by higher utility costs,” he says. “The other side is a heavy emphasis on efficiency. Again, the trade-off to lower utility costs is a much longer drying time.”

Alliance reports far more interest in programmable microprocessor-controlled dryers. Balman says that mechanical timers can very often waste utilities by over drying loads, which also damages linens.

“Microprocessors enable managers to program the unit to dry to a set dryness level, which reduces operating costs and increases throughput,” he adds.

He says that health care, commercial laundries and laundries serving the hospitality sector are all equally focused on reducing operating costs. However, the hospitality sector also must maintain high standards of finish. Programmable controls give a huge advantage in drying to a set moisture level during conditioning before linens are run through an ironer. “With the high cost of linen replacement, especially with the high-thread-count linens used in many hotels today, operations cannot afford to damage pieces by over drying them,” says Balman.

“Having maximum control over the drying process enables managers to tailor cycles to the individual loads. Utility consumption is reduced because over drying is taken out of the equation. Likewise, linen life is prolonged because it is receiving much better care.”

Girbau

According to Marc Caralt at Girbau, one of the key factors to achieve savings in the drying process is to devote just the exact amount of time in each cycle. Girbau’s ST-100 dryer for high production laundries, for example, has a built-in infrared system that measures the residual humidity. This system measures continuously and senses when the desired humidity has been reached and stops the drying cycle at that point

Girbau says that although gas continues to be the most efficient heating source, not all customers can install gas in their laundries.

One trend the company has detected is the progressive growth of free standing washing machines over hard mount machines.

The cost of the energy consumed to operate a drum with a high extraction rate is lower than the cost of the energy consumed by a dryer to evaporate water.

Air circulation together with the linen movement inside the drum are the key factors to efficiency. Girbau believes that good design of the drum assembly is essential to improving the efficiency of the air flow circulating inside the dryer.

Girbau high capacity dryers include hot air recirculation systems that allow reuse of the previously heated air, so saving time and reducing energy costs.

Girbau’s Spirotilt system optimises the air flow circulation. The flaps and the tilted drum allow movement that creates more efficient air flow and improves the drying action (see the diagrams on page 25) and, at the same time, provide easier unloading.

Jensen

The DTX Dryer range from Jensen began as a response to requests from its North American customers for a range of large capacity, heavy-duty dryers that would be efficient, durable and easy to maintain.

Development began in April 2008 at Jensen’s manufacturing plant in Panama City, Florida, with the aim of having a working prototype ready by the end of the year.

Before the design work started, Jensen produced a design specification that was based primarily on input from customers, in particular Aramark.

The first prototype machine was the DTX 800, an 800-lb capacity dryer. This was produced on time and underwent extensive testing and fine tuning during 2009. Tests showed gas consumption figures in the region of 1,700BTUs per lb of water removed (a BTU or British thermal unit is a unit of energy used in the USA).

According to Jensen’s Gerda Gerschwiler, efficiency was not the company’s only design criteria. The machines would have to be extremely durable and easy to maintain in order to be successful in the North American market.

The prototype DTX 800 machine was installed at Aramark’s plant in Dallas in September 2009 and has been running successfully for two shifts since that time. Aramark has since ordered additional DTX 800 dryers with the low NOX option for its plant in Los Angeles. Jensen has also developed the DTX 450 dryer and the first 450lb capacity machine was installed at Admiral Linen in January 2010.

At the heart of Jensen’s DTX dryer range is an industrial PLC and a keypad/display unit for easy operator interface. A number of pre-selected dryer programs regulate the burner and control both the rotation and speed of the basket. A humidity algorithm determines the end of the drying cycle. In addition, Jensen’s service helpdesk is able to remotely monitor the dryer control via its internet connection for fault diagnostics and software support.

Kannegiesser

Kannegiesser constantly looks at ways to reduce energy and this effort has been recognised with an energy solution award from the Energy Solutions Centre in Washington DC for its energy- saving PowerDry gas-fired dryers.

Kannegiesser offers basically two types of dryers – the PowerDry transfer dryer series and the DC compact dryer series.

The PowerDry range, available in 45kg to 220kg capacities, provides high drying performance. This is achieved by heavy duty fans, generously dimensioned heat sources (steam or gas) and large drum diameters. A favourable ratio of drum diameter to drum depth, together with the automatic adjustment of the speed of rotation to the degree of drying, ensures optimum flow of hot air through the textiles.

The PowerDry also features the Eco heat recirculation system where a certain amount of the heated process air is re-used in the drying process. Energy consumption can be further reduced with two optional systems, Energy Air Control (EAC) and Energy Recovery System (ERS). The EAC provides an automatic adjustment of exhaust air during the drying process via an automatically controlled air flap. The ERS uses the exhaust air heat to warm up the incoming fresh air.

The company’s InfraTouch continuously measures the surface temperature of the textile via an integrated infrared sensor. The measured data then provides a regulation value for the energy control source (steam heated or gas burner). All fabric and machine-specific factors are considered, such as moisture retention, fabric type, loading quantity and machine efficiency. This special control system enables exact and specific drying of a wide variation of fabrics and so reduces the non-productive times to a minimum.

The DC compact dryers, available in batch sizes from 36kg to 100kg, have several similarities in terms of components and process technology with the PowerDry series. The DC can produce up to three batches an hour, depending on local conditions).

Miele Professional

According to Olaf Dietrich at Miele Professional, energy efficiency plays an increasing role in the purchasing decision, as consumers want to save money. Miele produces heat-pump dryers that combine low energy consumption and shorter program running times with reduced noise level, low evaporation losses and product quality. The company exhibited three heat-pump dryers at last month’s Expo Detergo. Each dryer has a closed drying circuit and does not require vent ducting. A large proportion of heat energy is reused in the drying process.

Miele’s range of DryPlus PT 8000 tumble dryers currently has five models and features control sets to suit all types of commercial laundry operations. The DryPlus series has drum volumes for load capacities from 10 to 40kg and all models feature Miele’s patented innovations such as the honeycomb drum, Air Recycling system and PerfectDry electronic residual moisture controls. The dryers are available in electric, gas or steam heated versions for sustainable, cost effective performance.

The Air Recycling system ensures efficient use of warmed air to provide faster drying. Heat is recuperated by recycling approximately 60% of the warmed air in circulation, so helping to reduce air emissions and saving energy costs.

Miele’s honeycomb drum provides gentle handling of fabrics by cushioning laundry on a thin pocket of air created by the hexagonal profiled drum pattern.

The PT 8000’s drum has rounded Softlift ribs that lift the laundry high, allowing it to be caught on currents of air as it tumbles to the bottom, enabling thorough and uniform drying results.

With less friction between fabric and the drum, laundry is smoother and less creased, so finishing is easier too.

The FlexPlus control unit allows the dryers to be adapted to most situations, including coin operation.

A door aperture of 52cm permits easier loading and unloading of bulky items such as duvets whilst integrated lighting ensures nothing is left in the drum after drying.

Also showcased at Expo Detergo was Miele’s first dryer-dryer stack, two dryers with a common set of controls. It complements the company’s washer-dryer stack launched in September 2010. The Octoplus stacks require only half a square metre of floor space and will be available in early 2011.




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