Energy efficiency: Urgent actions to address sky high costs

Crunch time has come and much of the world is now having to deal with potentially catastrophic increases in energy prices. Now is not the time to put our heads in the sand or to limit your reaction to trying to negotiate large price increases with customers who are understandably grumpy and uncooperative. Support from national governments is unlikely to mitigate the problem significantly or long-term. However, there is much that can be done within every textile care operation serving the textile rental and contract laundering market. The essential immediate steps require team effort and careful thought, but they need not demand substantial investment (other than in man hours) and they have been proven to produce substantial reductions in energy demand, with corresponding financial savings, which will be particularly useful in the current climate. Don’t lose hope until you have read and acted upon our review of recommendations.

Collection and delivery

Most operations use scientific methods for collection and delivery route planning, but if you do not do this then now is the time to conduct a critical analysis. You need to minimise mileage and driver hours by programming your schedules so that you only leave your premises with a full load of deliveries and return with a full load of soiled. This might require very patient negotiation with each customer, but when you explain your reasoning and the associated benefit of keeping your price increases to a minimum, you should get a better reaction than might have been the case twelve months ago. You might need to reduce the frequency of pick-up and delivery, for example, to achieve economies here.

If your contract laundering customers have to purchase more stock, then so be it. This will ultimately benefit the profit and loss accounts for both of you. If you are running a rental business, an increase in stock is mainly an asset increase, whereas doubling of your fuel cost is a major loss. You might find that with this approach you can take one or more vehicles off the road, with consequent staff savings as well. We are living in hard times.

Sorting

Avid followers of Material Solutions will be familiar with our earlier recommendations regarding load weight (right up to the maximum recommended by the machine maker every time) using weigh scales which are calibrated regularly. However, not everyone is following best practice with the load weight for soiled towels. Regular checks have shown that these come in with a surprisingly uniform moisture content (in, for example, a 60kg load) in the range 15 to 25%! By increasing the safe load weight to allow for this, there are corresponding reductions in water, chemicals, wash energy and drying energy, with welcome increases in towel throughput and machine capacity. What’s not to like?

If you only have one CBTW and are processing white and coloureds, it is common practice to run with two, three or even four empty pockets after the coloureds to minimise colour transfer to the whites. This is no longer affordable on a frequent basis and future planning needs to limit this component of energy, water and chemicals wastage to only one or two times per shift. Quality and throughput will both improve with this component of your energy reduction plan.

It is still possible to observe ‘tumbler holds’ in a large number of CBTW-based operations, which occur when there is no tumble dryer available for the next load to discharge from the membrane press. The entire washing line idles whilst this effect of poor sequencing plays out, losing time, water, chemicals and heat energy. There are two straightforward solutions to this, neither of which is difficult to achieve . Some operators schedule a fixed number of loads for ironing in between each ‘full dry’ load. Others have a dedicated tumbler to break up each load for ironing within the CBTW cycle time, so that the risk of tumbler holds is greatly reduced and only occurs when all of the other tumblers are full of towels and yet another towel load comes forward.

Washhouse

National suppliers deliver commercial washer extractors to all parts of a region, knowing that water quality varies widely amongst their customers. They make sure that they work anywhere by gearing the rinse cycles to areas with the poorest water quality, usually defined by the highest natural alkalinity. So, with customers happy and suppliers happy, what could possibly be wrong? Gearing to the poorest quality usually means that anyone with better quality water will be demanding an unnecessarily high rinse water consumption and extended cycle time. Optimising the rinse dips may require titrations of progressive samples of last rinse liquor, for which you should consult your detergent supplier. Leading suppliers may well have done this when you started with them, so a check is all that may be needed. The financial saving in water and effluent volume charges will help to offset the increases in gas and electricity tariffs.

Optimum wash dips vary with machine capacity, so you should consult your manufacturer’s manual. Too high a wash dip wastes heat energy and reduces quality; too low creates unwanted pressure creases and reduces quality, especially for polycotton garments.

Low temperature washing down to as low as 40C is now possible for most classifications, using modern, specially developed detergents containing low temperature accelerators, emulsifiers and sometimes enzymes (geared to give the same quality as older, 70C processes). Trials with these are essential if meaningful reductions in energy demand are to be achieved.

You are unlikely to be able to separate loads by customer in future, because this almost always requires regular underloading, which is increasingly unaffordable in the present climate. This might require modest investment in labelling and post-sorting for delivery, but the savings in energy, water and chemicals, in particular, make the financial benefits irresistible.

De-watering

Removal of excess moisture after washing remains one of the key areas of potential saving, because this single mundane factor can offer some of the greatest savings in energy and productivity in many plants. This is because it takes fifteen times more energy to evaporate one litre of moisture in the tumble dryer than it does to spin it out in the washer extractor or squeeze it out in the membrane press. Modern ironers are more efficient, but even they use five times more energy than spinning or squeezing.

It is important to train staff to measure moisture retention as a percentage of bone-dry weight. The technique is as follows, with a worked example:

1. Tare your scales with an empty trolley.
2. Weigh a full load of textiles = 151.5kg, say.
3. Dry the textiles to bone dry in a tumble dryer.
4. Weight of bone-dry textiles = 98.3kg.
5. Moisture retention = (Weight of moisture removed) ÷ (Bone dry weight) x 100%
6. So, for this example: Moisture retention = [(151.5 – 98.3) ÷ (98.3)] x100 = 54.1%.

This is not particularly good, and a modern membrane press, properly tuned, should achieve a lower retention. Cotton rich sheeting will deliver even better results. You need to know first what the moisture retention is for each of your main classifications.

Then you can get to work on your spin speeds (maximum speed will give the best result) and spin times. The optimum time is when spinning for another 30 seconds gives no further improvement. Optimising the membrane press requires maximising the time at full pressure, so make sure the pressure gauge is working correctly and be prepared to adjust the ‘wait times’ in the computer sequence if necessary.

Tumble drying

Your work on minimising moisture retention should now be paying dividends at the dryers, especially with reduced cycle times for towelling and other full dry work. You need to adjust cycle times so that you don’t take every load to bone-dry. This is an unnecessary waste, because bone-dry towels immediately start to pick up moisture from the atmosphere when they come out. Set the dryers to give just a few per cent moisture, which will save even more energy (and tumbler minutes) and deliver whiter towels, with increased throughput. This is so important that if you cannot achieve it every time, then consider investing in automatic cycle terminators, which would probably have paid for themselves at the old gas tariffs within 12 months and will return their cost even more quickly now.

Ironers

Many ironers in the industrial laundry sector suffer from neglect in tuning and maintenance for the following typical reasons:

1. The clothed rolls are not a perfect fit for the semi-cylindrical beds, because of compacted clothing or incorrect clothing thickness from installation.
2. The roll-to-roll stretch is wrong, because of incorrect adjustment, incorrect clothing thickness or incorrect speed differential.
3. The bed temperature is not uniform, because of cold spots caused by intermittently wet steam, variable steam pressure or deposits on the heating surfaces.
4. The roll vacuum is too weak because of wrongly set dampers or wax deposits in the clothing , on the fan blades or in the ductwork.
5. The management of the ironer is not achieving high bed coverage and much of the heated surface is not doing any drying for some of the time.

Modern ironers are usually capable of high output with high thermal efficiency, but this is lost if the tuning points listed are not acted on.

Conclusion

Modern laundry management is not for the faint-hearted, but the scope of the opportunities set out in this month’s Material Solutions is indicative of the wide range of improvements generally possible. For those who ask, “How can some laundries achieve consumption figures as low as 1.0 kWh total energy/kg clean textiles sold?” we have tried to provide some immediate answers!

Good hunting!

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