Cutting the carbon tax

2 April 2001



Richard Neale explains how laundries can reduce the burden of the climate change levy.


In April 2001 users of electricity and fossil fuels will enjoy (if that is the right word) a further taxation levy to encourage economy.

The laundry sector is an intensive user of energy which with water and effluent accounts for up to 10% of turnover in some plants. In order to remain in business and to remain profitable every organisation needs a strategy for addressing the problems which the new ‘carbon tax’ will bring.

Members of the Textile Services Association (TSA) will be aware of the energetic work being undertaken by the directors to ensure fair treatment for the sector, but this will not be a substitute for sensible and progressive economies in every plant at every level.We look here at what is involved.

Organisation

Companies need to recognise that they have a problem which can be minimised if tackled sensibly. Firstly it is essential to identify how much energy (in kilowatt hours) is being used per kg of work processed and how much water is being consumed (in litres per kg) and effluent produced.

By comparing your plant figures with established norms you can see immediately how much you have to go for. In theory a plant processing all its work through a continuous batch washer with well tuned drying and finishing equipment will require 8 l/kg and 2.4 kwh/kg.

In practice no laundry is achieving a figure as low as 8 because even processing 20% of your work through a washer-extractor at 25 litres per kg will raise the average to a figure nearer 12 litres per kg. That is a reasonable starting target for most plants in this area.

The suggested target of 2.4 kwh/kg is in fact being beaten by many laundries in the UK and there is no reason why it should not be achieved by virtually every one.

Most laundries take sufficient readings weekly to enable monitoring of these key ratios and that is absolutely vital. Monitoring should start immediately before any improvements are put in so that the energy team get encouragement from achievements week by week. There is no reason to be afraid of publishing poor initial figures and delaying the calculation until you have made some basic improvements because the delay will become perpetual.

Picking the team

Who do you need in your energy team? Someone from production, engineering and accounts will make a good start because this gives control over equipment, operating procedures and monitoring achievements. Team members need to be empowered and inspired and this a task for the general manager.

Most water inlet valves and steam inlet valves to washer extractors leak slightly, as do those on a tunnel washer.As the leaks are internal they are not noticed, but cumulatively they represent a considerable loss because many of them continue 24 hours per day throughout the year.

Careful handling of incoming work removes some of the worst staining caused by floor marking and this together with careful operation will reduce the re-wash. All pipes at steam temperature need proper insulation (resin impregnated fibreglass with aluminium backing foil) which is dry and secure.

Dips and temperatures on washing machines need checking accurately on a regular basis. It is amazing how many washer-extractors do not have accurate or properly zeroed and legible dip gauges! These are an early essential.

The cheapest processing route through a washer-extractor involves a load factor of 100-105% of the manufacturer’s designed loading for that machine. Any lower and the water consumption per unit weight goes up dramatically. If it is any higher the re-wash will increase with a similar speed.

Once the dips have been established at what the soap supplier says they should be, they should be challenged progressively 5 or 10mm at a time. There is nothing sacrosanct about a 15 inch rinse dip, especially when water quality varies so much throughout the UK. Good water equals fewer rinses or lower dips.

Even more important are the wash dips because too high a level not only wastes heat but usually reduces mechanical action and over dilutes the detergency. Good energy management carries with it some surprising side benefits, particularly as regards wash quality and machine productivity!

Workhorse

On a continuous washer line, the key workhorse is the hydro extraction press. If the moisture retention from the press is more than 1 or 2% above what it should be, this will slow down the tumble dryers and the calenders. Slowing the tumblers will introduce periodic ‘waits’ whilst the line halts until a tumbler becomes available. Yet despite this, many plants do not measure moisture retention on a regular basis or seek to improve this to the design figure. The problem tends to be worst where stage times have been progressively reduced to improve machine output resulting in wet work going forward to the tumbler and general mystification as to why this should be!

The same thing here applies to the calenders. Minimum cost rental operation calls for correct hydro-extraction in the press, a minute or so in the tumbler to break the cheese, and then direct feeding into the calender edge to edge. Many companies do not press sufficiently, then waste seven or eight minutes in the tumbler on unnecessary conditioning and then feed the work into a fast running calender with at least half a sheet width between every item. On many plants this results in installation of a third calender where two should be quite adequate.

Once the press is delivering correctly and reliably (and a modern 47bar press will achieve well under 50% moisture retention) then attention should be turned to the tumble dryers and calenders which need to be tuned individually and methodically. The task may well take six to nine months but it cannot be skimped.

Productivity

So the first unexpected result of the work of the energy team is usually a significant increase in machine productivity at every stage. The work-flow becomes smoother with fewer interruptions. The maximum water is squeezed out of the work, so greying and variable drying tend to reduce. Energy savings accompany these benefits as well and in those plants with the biggest opportunities the net effect is a substantial reduction in cost per piece. In the competitive middle-market sector, it is frequently much easier to trim one penny off the cost of a piece rather than raise the price by the same amount and risk losing the customer.

Training sessions with groups of laundry engineers frequently brainstorm the subject of tumble dryer tuning. How do you get nearly new performance out of a ten year old dryer with variable steam quality, a very ‘iffy‘ condensate system and 14 hour day working?

Most engineers can come up with four or five techniques for reducing drying cycle times but when they work together the list increases rapidly, usually running to over 25 items. Not every item produces benefit in every plant but in most plants it is possible to identify those four or five improvements that are always possible. Sometimes these come from improvements on the steam side, sometimes from changes in battery maintenance, sometimes from improvements in trapping, frequently from improvements to air flow and elimination of leakage,the list goes on.

The same is true of calenders. A calender will only work properly if the heating system is correct, the mechanical alignment and roll diameters are correct and the clothing resilience and air flows are properly set up. With attention to detail a 20year old ironer will still produce very close to its original design drying performance, whereas in practice across the industry units producing much more than 65% of theoretical are quite rare.

Investment comes a long way down the line. With good leadership the energy team will need many months to implement the basics before starting to think about investment schemes. By then the key water and energy flows will have been reduced to such an extent that recycling schemes that might have seemed hopelessly expensive at the outset will gradually become affordable.

Most plants still fail to make full use of the heat in the condensate main which represents 17% of the fuel account. About half of this can be recycled successfully to the boiler feed-tank and recovered but many companies waste the other half and see up to 10% of the fuel value being vented to atmosphere as unused flash.

Previous issues of LCN have given various options for utilisation of flash and we shall be returning to this in future issues. but for the time being, the greatest savings will come from good housekeeping, intelligent production management and skillful maintenance in equipment tuning.

Do not let the energy team’s time and energy be diverted into fancy capital investment schemes until you are confident you have achieved the bulk of the basic benefits.

They will not have time to do both and if everyone pins their hopes on the return on investment there will be much disappointment.

What about heat recovery? Most laundries have two options: hot effluent from washing and hot air from drying. The trend to tunnel washers means that there have been significant problems in successful recovery because final discharge temperature is quite low and because recovering heat on a tunnel washer generally leads to higher front end temperatures with a greater incidence of stain setting as a result. New washing systems being trialled in various parts of the country offer some hope that much higher levels of heat recycling in tunnel washer lines will be possible and these need to be followed in detail by the energy team. There is much potential suddenly being realised here.

As far as tumble drying is concerned, plate heat-exchangers on dryer exhausts recycling heat into the inlet air stream only work properly if they are maintained very carefully. Experience to date indicates that this is unfortunately not always the case so tumble dryer heat recovery has so far brought more disappointment than success. For the time being the energy team will probably want to put this on the back burner.

Recycling

So where does this leave water recycling? Water and effluent costs are still rising at a rate much greater than that of inflation and are causing real pain in budgeting. It is rapidly becoming apparent that there are two main contenders for investment in water recycling. If your plant is based on washer extractors then final rinse recovery for use in wetting out first wash and main wash offers a 30% reduction in water consumption (with some reduction in effluent costs) for relatively modest outlay.

Even higher financial returns are obtained if last rinse recovery is combined with flash steam utilisation to create hot recovered water. The water saving is not quite as great but the total saving of water and energy gives by far the best pay-back available - often under twelve months.

As far as continuous batch washing is concerned, recovered water must be used on the rinse so it must be virtually as pure as raw water, preferably more so. This really points to reverse osmosis as being the only viable technique designed to take out hardness ions, alkali, micro organisms and the whole range of other contaminants which will give rise to poor wash quality. Reverse osmosis involves very serious capital investment (typically £50,000 - £150,000) and is not for the faint hearted or the incompetent. It should only come on to the agenda when all the other economies have been realised and the organisation is consistently hitting or beating the targets set out at the beginning of this article. Good luck



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