Making dryers more efficient and productive

Laundries are still big users of energy and at a time of rising prices and increased competition, they are trying to cut costs, particularly in the energy-intensive drying process. Equipment manufacturers and suppliers are responding to this demand.
"Without a doubt, energy consumption and machine quality are major drivers in the purchasing decision," says John Frank from Alliance Laundry Systems. "Both are related to the long-term cost of providing services and of the laundry's utility use.
But he adds that while most companies are attempting to reduce energy consumption, everyone must deal with the laws of physics. The amount of energy needed to evaporate and remove water is generally fixed. Considering the whole laundry and not just the individual stages helps to identify where improvements need to be made to increase overall efficiency.
"For example, a higher G-force extraction in washers reduces drying energy costs and intelligent controls will increase productivity and efficiency."
An Alliance survey carried out last year suggested that 79% of commercial laundry distributors and commercial laundry managers said they believed
on-premise laundries overdry by more than eight minutes per cycle.
He suspects that this number would now have reduced. "Alliance dedicates significant resources to educating distributors and service technicians about best practice. Demand for our Over-dry Prevention Technology has been terrific, proving that we continue to make an impact on the industry - one OPL at a time," says Frank.
The OPTidry Over-dry Prevention Technology on UniMac tumble dryers is a primary example of a technology that saves energy, reduces labour costs and maintains linen quality longer by shutting off the machine when the load reaches a user-selected dryness level.
Frank adds that managers now realise that the cost of current washing and drying equipment is justified by the higher costs of continuing to run older less efficient products.
Control systems, such as UniMac's UniLinc, offer specific cycles for various material types and programmable features to suit special processes such as wetcleaning. The graphic interface makes programming easy.
In addition, UniLinc's management features, such as networking equipment, recording downtime between cycles, interrupted cycle counts, error and service reporting, are significant drivers for early replacement.
Kannegiesser of Germany describes its high-capacity dryers in the PowerDry heavy-duty dryer range as the latest development in drying technology.
Joachim Rauschmaier, director of sales, says there are still thousands of old dryers in the worldwide laundry market but the need to reduce the sector's carbon footprint is leading laundry managers to question the consumption of such machines. The market is realising that some old dryers use more than double the energy that modern machines require.
Dryers have to work more hours, in shorter cycles to raise the plant's productivity, says Rauschmaier. He says that while the energy issue is not completely new, it has become more and more important for Kannegiesser's customers. He adds that some customer groups are even considering replacing dryers that are only 5 - 6 years old.
This is because the development of energy-efficient dryers has improved dramatically and so it may be seen as a reasonable investment to change now to a more efficient product and start enjoying the benefit of savings.
Kannegiesser has studied energy consumption and optimisation in the drying process, both in the lab and in the field. As a result, the company has launched the second generation of its PowerDry machines, the PowerDry D.II series. With nominal loading capacities of 40, 60, 85, 120, 175 and 220kg, and the option of gas or steam heated versions, the PowerDry D.II is said to meet requirements, in both new applications and existing laundries.
Radial airflow combined with the controlled drum speed guarantee an effective flow through the load. As standard, drum segments can be removed for cleaning and this allows consistent performance. The series also features Kannegiesser's Eco Air Circulation Heat Recovery as standard.
When the PowerDry D.II dryer is used in combination with the company's
Eco-2 Power package, energy consumption is reduced by 20% compared with that of the original series. With the Infra-Touch control, certain parameters are monitored continuously to determine the level of dryness. This allows accurate control of all functions across the entire drying process, individually batch-by-batch. The system minimises drying times by identifying the exact point when the linen is dry.
The Eco-2 package still represents the most modern feature on the present market, says Rauschmaier. "Customers who are using this feature are impressed by the performance, and also by the simplicity of machine maintenance."
PowerDry D.II machines offer several optional features to optimise the drying process and increase daily productivity.
The EAC (Energy Air Control) controls the timing and volume of the
built-in heat recovery system, making it even more efficient and helping to give a quick return on investment. The Accelerated Cool Down ensures that only cool air ends up in the inner drum, so accelerating the cooling process.
Plastic adhesion is a particular issue in healthcare laundries so Kannegiesser can also apply a non-stick coating to the inner drum.
James Thorpe, vice president of marketing and sales at Jensen USA says that buying a dryer for a new installation is easy - pick the most efficient, durable and serviceable machine with the shortest cycle time - but deciding when to replace an existing machine is much harder. Historically, replacement decisions were a reaction to the easily identifiable factors of rising maintenance costs and increased machine downtime. "This mindset is changing," says Thorpe. "Hidden costs are now the driving force. The decision process now begins with a gas meter and a performance study. How much gas is being used? How long is each drying cycle? How long does it take to carry out preventative maintenance?"
Thorpe says that although a drying cycle uses hundreds of cubic feet of gas, this cost is normally hidden in a large gas bill covering all gas-heated equipment, so it is difficult to use drying costs to justify capital purchase. Fitting a gas meter temporarily will establish the gas use. Weighing linen before and after drying allows laundries to calculate the gas used per pound of water removed. "This measurement can be compared to new machine consumption figures to calculate payback time."
Calculating the time to process each load can also provide useful information on wash-floor capacity and machine use. Establishing the current daily drying requirement and comparing it to new machine drying capabilities will allow the operator to calculate extra capacity.
Jensen's latest L-Tron DTX Dryers, with a capacity of 200 - 400kg, use axial airflow that delivers incoming air through the front and back of the drum rather than through the perforations. This will result in more efficient penetration of the linen. As the only air passing through the drum panel is "cold" outlet air, "hot" incoming air does not heat the drum panels. Preventing the drum from being heated to higher levels, saves energy and reduces the likelihood of plastic items melting in the drum. The optional RecoCross system
pre-heats incoming air with residual heat from the exhaust.
Having the right information regarding each individual cycle is also important. The control system on Jensen's DTX dryer allows the operator to make a visual analysis of the drying cycle and to make adjustments to improve efficiency.
At Girbau in Spain, Marc Caralt, product manager for the commercial division, agrees that close control and monitoring of the drying process is in line with the growing professionalism of the laundry sector. "Owners and managers need to know the consumption and production figures so they can adjust their margins and operating accounts effectively," he says.
Saving energy and time in drying, recognised as an intensive process, has a great impact on the income statement. Efficient drying also helps to prolong linen life, again resulting in big savings.
Caralt says that one of the keys to achieving a good balance between quality and energy savings is the ability to adjust settings according to the load.
The digital control on Girbau's latest ED Ecodryer series provides settings that minimise the impact of the process on fabrics. Temperature needs to be controlled at all times to prevent sudden spikes that heat the linen excessively. The ED dryer controls allow the input and output temperature to be set accurately and adjustments to be made during the cycle. In addition, the residual moisture sensor will identify when the linen is at the desired moisture level for stopping the process to avoid overheating.
ED dryer controls can also vary the rotation speed and direction of the drum, either manually or automatically, depending on the characteristics of the linen. Reversing the rotation of the drum encourages the movement of the load inside the drum, avoiding clumps of linen and ensuring faster, gentler drying. In addition the ED dryers have Girbau's Care Touch design, with the holes in the stainless-steel drum stamped out rather than perforated, so preventing sharp edges.
Caralt says that the Care Touch drum will dry delicate items without damaging the fabrics. "The ED drying process is extremely gentle and all dryers can be used for wetcleaned linen.
Girbau has implemented several ideas to encourage laundries to replace equipment both to help them become more competitive and to reduce their environmental impact. The guidelines for its social responsibility policy state that it will work to help the industrial laundry sector apply best practice. Caralt says that Girbau designs promotions that will make it easier for laundries to upgrade their dryers. The investment quickly pays for itself because of the considerable savings.
Electrolux Professional says that easy serviceability and flexibility in installation are important considerations and the company plans developments in this field. Ease of use and ergonomics is where the current trend is heading, says the company.
Electrolux adds that the CompassPro - fitted on the 6 - 37kg range of machines - has proved to be a real game changer, opening up a new world for customers in terms of flexibility and programmability. Having the same control on both washer-extractor and dryer makes the full process even easier and more customer-friendly, it says.
Domus has launched its Eco-Energy series of dryers, said to minimise drying time and achieve energy savings of up to 40%. The dryers are available in nominal loading capacities of 12, 18, 29, 37, 50, 67 and 83kg and are available with electric, steam or gas heating.
The Domus Eco-Energy dryer has a stainless-steel drum and features a frequency inverter as standard. All models offer a reverse drum action to allow clothes to move inside the drum.
To achieve the maximum energy savings, Domus has developed its patented Air Re-cycle recirculation system. This reintroduces expelled hot air into the machine directly through the back of the drum. The mixed axial-radial airflow provided by the Domus Double Flow system increases drying efficiency.
The dryers also feature the Efficient Dry humidity sensor, which Domus developed to allow precise moisture control and avoid overdrying.
The drying cycle will automatically stop when it reaches the set level of residual moisture. The drying system can automatically adapt the speed of the drum to the humidity level of the load. The drum then moves at the optimal speed to ensure maximum humidity extraction, so reducing both drying time and energy consumption.