Clean and green washing machines

Traditionally, industrial washing operations, especially in the food sector, have had a significant environmental impact, but it needn’t be so, says Carl Hollier, md of Industrial Washing Machines

The T2000 tray and dolly washer

When designing a washing machine for a specific application, the top priority is always to ensure that it meets the customer’s requirements. If that sounds too obvious to be worth saying, think again. Naturally, the customer will want the machine to achieve a certain level of cleaning performance, but these days that is far from the only requirement.

The machine must also be economical to run and, in particular, its usage of costly water and energy must be minimised, not only to keep costs under control, but also to reduce its environmental impact. Achieving these objectives simultaneously is a significant challenge that requires a high level of expertise to produce a viable solution.

The measures needed to achieve such a solution divide into two categories: improvements to the basic design of the equipment on the basis of on-going research and development, and application-specific measures that may relate only to the project in hand.

The intelligent application of new technologies, instead of relying on traditional solutions, is providing opportunities for many improvements to the basic design of the machines.

Water level control

For example, precise and dependable control of the water levels in the machine’s tanks can be achieved by using electronic sensors to monitor the level and solenoid valves to control the water feed. This is a big improvement over the ball valve and float systems that are traditionally used, and significantly reduces water usage by eliminating tank over-filling and minimising overflows.

Modern control systems also make it possible for designers to interlink operations on the machine. For example, in machines where the items being washed are transported on a conveyor through a rinse tunnel, provision can be made to automatically cut off the supply of rinse water whenever the conveyor stops. This prevents water being unnecessarily spent to drain.

Automation can, of course, help in other ways, and it is often perfectly possible to incorporate sensors that detect whether particular functions of the machine, such as the conveyor system, are currently being used. If the functions have not been used for a preset length of time, arrangements can be made for them to be automatically turned off or put into a dormant energy- and water-saving mode.

Not all of the measures that can be taken to enhance environmental efficiency relate to automation, however. Some are facets of the basic machine design, such as ensuring that water tanks are correctly sized. The entire tank capacity of the machine will always need to be drained down at intervals as part of the normal machine cleaning routine. It is important, therefore, to use the minimum size of tank that it is consistent with efficient washing.

Further water savings can be achieved by recovering water from a fresh water rinse and using this to top up the tanks. Even something as seemingly unrelated to water usage as filtration can have a significant effect, since specifying the correct filtration reduces the frequency with which the tanks need to be drained.

Turning now to application-specific measures, these naturally vary from project to project, so it is only possible to give a few general examples of possibilities.

Water reuse

In applications where the items to be washed are likely to be heavily soiled, the use of pre-wash stage is often beneficial. Usually operating at ambient temperature, the pre-wash will remove most of the soiling before the heated detergent process completes the clean. As a result, the detergent wash can be shorter and less intensive, which means that less energy is needed to heat the wash water, and less detergent is needed because the wash tank remains fresher for longer.

In some cases, it is even possible for the overflow from the fresh or final rinse sections to be plumbed back into the pre-wash tank, thereby re-using the water and diluting the pre-wash water to keep it fresh. Depending on the application, tanks and sumps can also be provided to recover fresh water rinse water.

While all the measures discussed so far have been largely the responsibility of the machine manufacturer, users of industrial washing machines also have their part to play in achieving energy efficiency and protecting the environment.

Without doubt, the most important requirement is to keep the machine clean and properly maintained. It doesn’t take much insight, for example, to see that a heating element covered with scale will operate very inefficiently and use a lot more energy than a clean element. And running a machine with worn out or defective components is a sure way to increase running costs and environmental impact.

The best washing machine suppliers will, of course, supply detailed information and training on how best to look after their machines, and users are strongly recommended to take advantage of these options.

It is also well worth considering a regular service contract with the manufacturer, as this is the best guarantee that the machine will be maintained in tip-top condition and that it will always be operating at peak efficiency.

As noted here, the environmental impact of a modern industrial washing machine – provided it is well designed and properly matched to the application – is far less than that of its older counterparts. For this reason alone, it is often worth replacing older washing plant, but there are other very sound reasons for taking this step.

Remember, for example, that reducing water and energy usage doesn’t just protect the environment, it also means lower running costs. And modern machines are invariably smaller and more reliable than their predecessors. Now might, therefore, be a very good time to consider a review of your washing requirements, and to seek advice from an experienced supplier, such as Industrial Washing Machines, about the ways in which combining clean with green could deliver benefits for you.