Moves to improve energy efficiency are driven by environmental awareness but perhaps even more by the need to operate more efficiently to improve the laundry’s cost-effectiveness.

Rudi Moors, corporate marketing director at Christeyns, points out that less waste equals more profit. The diagram supplied by Christeyns shows the distribution of thermal energy consumption in a modern laundry that has installed energy saving equipment.

The company says that with the help of specific wash processes and integrated water and energy management systems, energy consumption in the wash can be minimised and even reduced to zero.

The company has several technologies that will contribute to this goal. The company’s Heat-X Rotor and Heat-X Energo heat-exchangers are both designed to recover heat from wastewater. Heat-X Rotor is particularly suitable for use in an integrated solution for a single tunnel washer.

Heat-X Energo has proved suitable as an end of pipe solution for laundries that typically have a couple of tunnel washers and a line of washer extractors and therefore have larger flows.

With Steam-X and Heat-X Air technologies, the company can recover heat from condensate or waste exhaust air and so it can run a wash process without any extra energy input – hence its claim to achieve 0% energy in the wash.

For laundries that want to eliminate steam heating altogether Christeyn’s Zero steam technology can be applied to both tunnel washers and washer-extractors.

Tunnel washer

It applies an indirect heating concept. In a tunnel washer the approach works as follows.

Hot water (up to 94C) produced by the hot water generator flows inside the heat-exchanger in a closed, pressurised circuit. The main wash water is pumped from the tunnel washer into the heat-exchanger.

To achieve optimal heat exchange, the system creates turbulences in the liquids to heat water and main water flowing in opposite directions.

The heated main wash water (up to 75C) flows back under gravity to the tunnel.

In a washer extractor Zero Steam can be applied in this way.

Hot water is produced with gas-fired, high efficiency generators. This heated water (up to 94C) is stored under pressure in an insulated tank.

Frequency controlled pumps produce a stable flow through both hot and cold water lines and the desired wash temperature is achieved by mixing hot and cold water in the washer-extractor, reducing cycle time. A main wash temperature of 75C can be obtained.

The steam-free route has also been pursued by some equipment manufacturers.

Jensen Group’s CleanTech works by using direct gas heating and the company explains that this allows higher process temperatures that lead to shorter drying and finishing times, reducing energy use and increasing productivity.

The principle can be applied to individual machines, which can be installed and commissioned easily and quickly so the concept can be introduced gradually throughout the laundry.

The steam-free tunnel washer has an integrated gas-operated water heater which heats the process water in the compartments where steam was previously injected. Savings can be increased by adding a tube-in-tube heat-exchanger and using a low temperature wash.

Drying is the most energy intensive part of the laundry line and the group’s Senking gas dryer with i-r control and built-in heat-exchanger can reduce energy use here by up to 35% – as little as 0.2kWh to fully dry towels.

The EXPG ironer has several energy savings technologies. For example, it uses oil as the medium for transferring heat as oil can reach higher temperatures.

The high-grade carbon steel chest also optimises energy use as its heat conduction ability is four times that of stainless-steel.

High temperatures on the ironer bed increase the ironer’s drying capacity, especially on thick items such as duvet covers.

For laundries handling workwear, Jensen has also looked at energy saving in the tunnel finisher.

A separately adjustable gas burner has been built-into the centre of each drying chamber.

The circulated air is heated by a distribution tube that is directed at a high-temperature baffle.

Energy consumption is reduced by directing air from the drying and outlet zones into the inlet zone and this recirculated warm air heats incoming garments.

In recent years the Spanish manufacturer Girbau has been raising the profile of its heavy-duty laundry equipment and has developed its tunnel washer with water- and energy-saving features.

The Eco tunnel is claimed to use up to 70% less energy than a typical washer-extractor and up to 30% less energy than “other” tunnel washers.

The temperature is controlled individually in each module, including the pre-wash module and in the recovery tank. Steam is directly injected to the bath in each case and its intake is controlled by solenoid valve. It is therefore possible to control temperature at each stage including the rinse.

Probes in each module transmit temperature data to the PC throughout the process so accuracy can be monitored. The parameters for each batch are also recorded both for monitoring purposes and for future analysis. Following the recycling principle the Eco tunnel is equipped with a drain intercooler which recovers energy from water sent to the drain and uses it to pre-heat the incoming water, saving more than 30% of the energy used in the washer.

Kannegiesser’s “Green” laundry is based on two ideas. The first is to optimise water and energy use in each machine and then to integrate water and energy savings so that this optimisation is applied throughout the laundering process from washers to dryers to ironer lines and tunnel finishers.

One of the central technologies in this process has been the Jet principle introduced to the company’s tunnel washers. This pre-extracts most of the water used from the main wash before the rinse cycle starts so that absorption of the rinse water is more efficient and therefore less water is needed in rinsing. This in turn reduces the energy use. The Jet principle has now been extended to the company’s washer-extractors in the Favorit Plus series. This now includes Jet rinsing and also allows the extractor to achieve a pre-defined level of residual moisture, both features that contribute to energy efficiency.

The second stage is to look at the laundry as a whole and to see how the various stages in production relate to each other and how energy can be collected from the waste products of each process and then recycled in another. There are two main areas to examine here. In washer-extractors and tunnel washers recovery and re-use can be integrated using central process water tanks.

The finishing line is often overlooked as a source of energy-optimisation but energy can be collected from the exhaust air from the ironer and tunnel finisher using a combination of condensation heat-exchanger, isolated warm water tank and intelligent process controls.

Ecolab highlights not only the need to reduce energy in individual machines but also through housekeeping measures such as minimising re-wash.

As the next step the company has used its expertise in water and energy saving system to devise the three-stage PERformance system. PERformance Basis looks at the wash process and how it can be made more efficient.

PERformance Plus uses the process devised for the Basis system but then considers how to optimise energy from boiler house to washing and finishing processes.

It uses three systems. The Energy Optimiser takes energy directly from the wash. The Vent Optimiser collects exhaust steam from the boiler feed water tank to heat the fresh water stored in the warm water tank and re-use it in the rinse zone. The Aquavent heat-exchanger recovers energy from the ironer exhaust and uses it to provide warm water for re-use.

The final stage, PERformance Ultimate sets out a plan for a steamless system.

This year Ecolab developed PERformance Basis still further with PERformance 40, a process, claimed to be the first, that now allows a tunnel washer to achieve both washing and disinfection at just 40C.

Milnor’s PulseFlow system has received the Hohenstein Certificate of Innovation for its proven ability to reduce water use in a tunnel to as little as 2.5 – 3.5litre/kg whilst still achieving standard rinse and soil removal results. The company says a PulseFlow CBW tunnel washer has a direct effect on both water and energy use. In both respects, the company says PulseFlow produces savings from 25 – 50% compared with traditional and competitive models.

PulseFlow tunnels have also been used in steamless operations including a North Carolina laundry and in the first quarter of this year in a plant in Milwaukee.