0 il Industry worldwide has come to rely heavily on oil as a result of cheap supplies available up to ten years ago. Conservation of this finite resource by i t s owners and the increasing cost of developing new sources will ensure a continual rise in i t s cost. Availability problems may become crucial in 25 to 50 years.

Gas Similar considerations apply, except that the time scale may be shorter. North Sea gas i s considered likely to cost four times as much as now, in real terms, within a relatively few years.

Coal This i s the fossil fuel with the greatest l i fe expectancy, much greater than that estimated for oil or for gas, whose avail- ability in the long term i s a matter for serious concern. Extensions of i t s use in industry can be visualized for raising steam, and in the manufacture of cement, bricks and some chemical products. However, even where a return to the use of coal is feasible, the necessary facilities for i t s storage, handling and burning have disappeared. The electricity generation industry i s the best placed for increasing the burning of coal, and the increased exploitation of coal as an energy source for industry appears to require i t s conversion to electricity.

Nuclear Energy Even with present technology, nuclear energy appears to have a l i fe expectancy of the same order as that of coal. Possible future technologies may extend this life, perhaps ewen by some centuries. For the present and for the foresee- able future i t s use appears to be limited to supplying elec- tricity to public distribution systems.

Alternative Energy Sources Every effort will be made to use currently unexploited energy sources (e.g. wind, solar, wave, geothermal, biomass, etc.) in the form in which, or close to the place where, they are captured. For example, solar energy i s finding outlets for domestic and small commercial space- and water-heating installations. The wind, once a major source of motive power,

could return in the future, e.g. for land drainage. Neverthe- less, whenever these energy sources are exploited on the large scale it is almost certain that the energy will be converted into electricity for distribution via the existing networks.

The Substitution of Electricity for Fossil Fuels in Industry For these reasons most forecasts for the use of energy in industry in the future assume an increase in the proportion supplied as electricity. Over the last decade the indices of electricity prices have, in many countries, risen more slowly than those of oil. Furthermore, events in the Middle East are repeatedly casting doubt upon the security of oil supplies. Although it may be necessary a t the present time to persuade industrialists of the importance of substitution, further changes in the relative prices of electricity and fossil fuels, or the appearance of real or artificial shortages of oil or gas, could reverse this situation. There are massive energy needs in industry, such as for space heating, steam raising and water heating which, with moderate capital investment, could be met by switching to electricity. Yet a sudden and extensive substitution of electricity for fossil fuels cannot be contem- plated; if it i s to be progressive, an appreciable period of time will be required for the construction of the generation and distribution equipment and for the motivation of customers.

CONCLUSIONS 1. Electricity consumers, large and small, would be well

advised to give some thought to the terms under which they buy it, and the ways in which they use it.

2. The electricity suppliers, the Area Boards, are very willing to give assistance, without charge, on both aspects.

3. Energy conservation can be very effective in reducing manufacturing costs, and anything saved i s equivalent to simple profit.

4. Electricity has a vital and steadily increasing role to play in the industries of the future, offering a versatile and efficient form of energy that can be generated from all the available sources of primary energy, according to their relative availability.

5. For i t s own reasons, each of the above four conclusions must be considered for action now, and taken account of in any plans for the future.

Publication Sponsored by the Society's Scarce Resources Committee - 10

1973 and R Freytag

Changes in Energy Consumption in the French Textile Finishing Industry between

1980 and P Viallier

Energy costs have escalated dramatically over the last few years and this hasmeant that consumers have been anxious to find ways of economizing. In France there is a unique situation since the Government made it mandatory for significant savings in energy to be made. Secondly, the Government has also decreed that a substantial pro- portion of the energy used should be electricity. This paper describes how the textile industry in France has dealt with these two factors and indicates a number of ways by which energy savings can be achieved.

INTRODUCTION Since 1973, oil prices have increased by a factor of nine and this has encouraged consumers to find ways of reducing energy consumption. France imports more than 70% of i t s energy, so the Government took steps t o encourage energy thrift to aid the balance of payments. By 1974 the French Government had already decided that a 20% saving in energy, based on 1973 figures, should be made.

In the textile finishing industry the Department of Industry declared that only 80% of the oil consumed in 1973 could

350 JSDC Volume 98 October 1982

be purchased a t normal prices and that above this a special tax would be levied. The textile finishing industry did not agree with this since each manufacturing plant hoped to increase the quantity of fabric dyed or to increase the quality of i t s production, both of which would require the use of more energy. After negotiation, the industry and the Department of Industry came to an agreement based not on the total energy consumption but on the specific energy consumption per tonne of fabric according to the processes used. An agreement was thus concluded in which the industry contracted to reduce the 1973 energy figure by 19% by 1980. The lnstitut Textil de France was asked to monitor that this contract was fulfilled and the Centre de Recherches Textiles de Mulhouse supervised the energy saving of the 14 finishing factories in Alsace.

REVIEW OF ENERGY USED Industry buys much of i t s energy as oil and therefore in this paper the energy unit used will be tonnes of oil equivalent (TOE). Taking into account the low efficiency of the power stations, it can be calculated that 250 g of oil are required for 1 kWh of electricity. In 1973, for the 14 Alsation fimsh- ing milts under review, the energy consumption for a total production of 51 995 tonnes of textiles was as follows:

28 814 (25.7%) TOE as coal 70 016 (62.5%) TOE as oil 1 593 (1.4%) TOE as gas

1 1 651 (10.4%) TOE as electricity equivalent to 46 604 MWh)

This corresponds to an average specific energy consumption of 2.16 TOE per tonne of textiles.

The specific energy consumption varies with the type of finishing, the figures for 1973 being:

3.03 TOE/tonne for printed fabrics 3.40 TOE/tonne for dyed wool fabrics 1.53 TOE/tonne for dyed cotton fabrics

POSSIBLE SAVINGS As long ago as 1974 an energysaving project was initiated by examining the most feasible methods of cost reduction.

TABLE 1

Energy Consumption in TOE

This began with an educational programme since it was important that energy consumers realized that these costs can amount to more than 10% of the total and can be higher than dye costs. In the dyehouse, action i s always taken to avoid waste of dye, so it is pertinent to ask why is the same not done for energy. A typical example of energy wastage i s openwidth washing, since it i s exceptional to find that the water and steam are turned off when the machine i s stopped. Insulation of steam pipes was an early priority, while a t the same time condensate return had to be considered. In many factories condensate was not returned and i f condensate returns did exist, these were not always insulated. In one case, a condensate-return pipe without insulation was found in the waste-water drain.

A further early saving was achieved by changing the opera- tion of openwidth washing machines according to the results obtained previously [I]. These machines work on a countercurrent principle and the hot water used has to be automatically adjusted to the amount of fabric entering the machine. The proper adjustment of these machines alone results in between 0.1 and 0.5 TOE/tonne of fabric being saved. Advice was also given regarding changes in some processes, e.g. in cotton bleaching where, increasingly, cold hydrogen peroxide is being used.

SAVINGS OBTAINED At each annual audit it was possible to record additional savings obtained by the individual factories and a comparison has been made between the energy used in 1973 and 1980. This data i s shown in Table 1.

The following conclusions can be drawn:

1. Production has increased by 23% 2. Despite this increase in production, the total energy

consumption has decreased by 16.2% 3. The use of coal is decreasing while the percentage con-

sumption of oil and electricity i s increasingly slowly; there is a much greater rate of increase for the amount of gas consumed

4. The mean specific energy consumption has been reduced by 32% so that the contract with the Government to save 19% was more than fulfilled.

~ ~~ ~

1973 1980

Total textile production (tonnes)

Consumption (and %) (TOE) Coal Oil Gas Electricity

Total Printed fabrics Dyed wool fabrics Dyed cotton fabrics

Specific energy consumption (TOE/tonne)

51 995

28 814 (25.7) 70 01 6 (62.5) 1593( 1.4)

1 1 651 (10.4)

2.16 3.03 3.40 1.53

64 015

14 825 (15.8) 60 563 (64.5) 6353 ( 6.8) 12 162 (12.9)

1 A7 2.17 2.43 1.10

JSDC Volume 98 October 1982 351

On a cost basis the situation is different; Table 2 compares energy costs for 1973 and 1980.

TABLE 2

Energy Costs in Francs

1973 1980

Total textile production in tonnes 51 995 64 015 Cost (Fr x lo6) of:

Coal 5.0 9.4 Oil 9.5 61.9 Gas 0.6 5.8 Electricity 4.9 13.0

Total cost (Fr x 1 06) 20.0 90.1

Specific costs (Frltonne) 382:67 1,407.48 Specific energy costs (FrITOE)

Coal 174 634 Oil 136 1,022 Gas 377 913 Electricity 1,223 3,107

An analysis of these figures leads to the following conch. sions:

1. Total energy cost increased by 350% for a production increase of 23%

2. Whereas in 1973 oil was the cheapest energy source, coal i s now the cheapest

3. The average specific cost of energy increased from 382.62 Frltonne to 1,407.48 Frltonne, i.e. by 268%, in spite of the energy saving of 32%. The average energy cost for particular materials i s given in

Table 3.

TABLE 3

Average Energy Costs (Fr/tonne)

1973 1980

Printed fabrics 478 2,003 Dyed wool fabrics 550 2,406 Dyed cotton fabrics 266 1,076

USE OF ELECTRICAL ENERGY In the long term there is a further problem for French industry. Despite the high investment cost, the French Government has decided to replace some conventional thermal power stations by nuclear power stations. Because of this, it has been decreed that by 1987 the consumption of electrical energy must increase to one third of the total energy consumed. Between 1973 and 1980 the relative electricity consumption has increased from 10.4 to 12.9%. This means that by 1987 it will be necessary to increase it by a factor of 3, with a corresponding decrease in oil con- sumption. To overcome these two problems, energy saving and the change in the type of energy used, industry can only proceed in a step-like manner.

It i s proposed that the following steps should be taken:

(a) Saving by process and machine changes (b) Saving in the area of drying (c) Saving by heat recovery (d) Replacing oil by electricity.

Process Changes Process and machine changes can result in significant sav- ings. For example, bleaching can be carried out using hydro- gen peroxide in the cold. If the energy used in a thermoset- ting process on a stenter i s measured, it i s found that only 5% efficiencies are obtained. This is due to the fact that 50 m3 of hot air are required to heat 1 kg of fabric and this hot air is only partly recirculated, or not a t all, in order to avoid the formation of condensation spots on the fabric. In this area research work is in progress in an attempt to purify the hot air for reuse without the need to cool.

In the dyehouse a choice can be made between hot- and colddyeing reactive dyes. Even though the dyes themselves are more expensive, a cold-dyeing process can be cheaper than a hot one. In batchwise dyeing it is becoming necessary to use the lowest possible liquor ratio. Winches and jigs must be enclosed to conserve heat and the lid must be closed and not kept open for the convenience of operatives. In certain cases dyeing can be carried out at 10-15°C below the boiling point to avoid evaporation and thereby waste of energy.

As mentioned earlier, open-width washing machines should operate with counterixrrent flow throughout, and the hot water supply should be automatically adjusted to the quantity of fabric entering the machine.

Drying As the second step, savings must be made in the area of dry- ing. A can dryer uses 40% less energy compared with a stenter and 20% compared with a hot flue. If there are no migration problems or if fabric width does not require to be controlled, a can dryer should be used. I f the damper setting in the chimney of a hot flue or of a stenter i s in- correct the energy consumption can be doubled.

Mechanical removal of water by squeezing, centrifuging or suction requires 40 times less energy than evaporative drying.

Water should be removed mechanically whenever possible. However, padders designed for dyeing should not be used for squeezing, since they are designed to leave enough water in the fabric for dyeing to occur and 80-9096 (0.w.f.) water is le f t in the fabric compared with 40-50% using an ade- quate pair of squeeze rollers. By reducing the water content to 40% compared with 80%, 80 kg of oil i s saved per tonne of fabric, or, alternatively, using the same equipment and the same amount of energy twice as much fabric can be dried. In this case the period required to recover the cost of a good mangle is very short.

Heat Recovery So far the recommendations which have been made are relatively easy to implement and the associated investment costs are quickly recovered. This is not always the case with the next step, which concerns savings by heat recovery.

(a) By using heat exchangers (b) By using heat pumps.

The former can recover heat from hot water or from hot air but the recovery is only useful where the temperature difference is a t least 20°C. unless a large and expensive ex- change surface i s employed. By using a heat exchanger, in- coming water can be heated from 10-15°C up to 40-50'C. In this way a 30% saving in the total energy consumption can bemade. The use of heat exchangers i s of interest but limited. If a higher heat recovery i s required, heat pumps should be used.

The principle of the heat pump is illustrated in Figure 1. In this equipment there i s closed circulation of a substance submitted to a thermodynamic phase modification. This sub-

Heat can be recovered in two ways:

352 JSDC Volume 98 October 1982

stance can be evaporated in the evaporator of the heat pump by introducing a hot liquid or gas waste (W) to obtain saturated vapour a t the temperature T I and a t the pressure PI corresponding to position 4 of the phase diagram shown in Figure 1. With a compressor (C) this vapour is compressed to a pressure P2 and the vapour is heated to temperature TK to obtain a dry superheated vapour corresponding to the position 1 in the phase diagram. In the condenser of the heat pump this superheated vapour i s cooled to temperature T2 a t which it begins to condense (position IS). At constant temperature and pressure (T2 P 2 ) the vapour i s changed into liquid (position 2) and the recovered energy is used to heat a liquid or a gas to a temperature higher than the temperature of the initial waste (W). Finally, the liquid is decompressed (position 3) before returning to the evaporator.

Wet steam

I

Entropy

W

............................... j P, T, 3 2

Heat pump

__ Steam Steam +water

........ Water

Figure 1

An everyday application of i..e ..eat pump i s in the domestic refrigerator. The evaporator i s inside the freezer a t a temperature of -2OOC atd the condenser i s outside a t a temperature of about 60C. The gas employed is Freon. Freon has the advantage that it will reach a high temperature difference T2 - Tl.for a small pressure increase P2 - P I and without an excessive overheating temperature TK- Unfortu- nately, with Freon the condenser temperature cannot exceed 100-llO°C, whereas it i s necessary in a dryer to work a t 15OoC to obtain correct drying speeds. For industrial use the

conclusion was reached that the Freon should be replaced in the heat pump by water and steam.

The pressure P2, corresponding to saturated steam a t 15OoC, i s a usual one which can easily be obtained with a conventional compressor. However, the phase diagram for water and steam shows that steam, contrary to Freon, induces a very high overheating temperature T,. Thus, i f saturated steam at 85OC is compressed to the pressure corres- ponding to saturated steam a t 150°C, an overheating tempera- ture T, of 34OoC results. Such a temperature i s not compat- ible with a conventional compressor. This can be overcome by injecting water into the compressed steam, but water injection leads to corrosion problems inside the compressor.

In collaboration with a textile machinery builder a new patented heat pump has been developed [2] using a rotary pump as compressor but filled with a water seal instead of the usual oil seal. In this case, the steam during compression is always in contact with the water seal and the overheating energy is used to evaporate water in the seal. The first full- scale hot flue utilizing this principle indicated that it was possible to evaporate 1 kg of water using only 1400 kJ instead of the 4000-5000 kJ required in a conventional well-adjusted hot flue.

This new dryer achieves two targets; a saving in energy is obtained and the heating medium is changed from oil to electricity. Thus, in the last step of the energy saving plan, replacement of oil by electricity, one method of doing this i s to use heat pumps to triple the electricity consumption during the next five years.

It i s also possible in boilers to replace oil burners with electrical resistances, but it is always necessary to take into account the heat losses which occur with boilers, such as in the pipes and in the exchangers.

Infra-red Heating Electrical energy can be used more effectively by converting it into one of the following forms of radiant energy: (a) Infra-red (b) High frequency (c) Microwave.

For several years work has been carried out at Muihouse in the use of infrared radiation but the effectiveness of such radiation depends on the wavelength used. This type of radiation can be divided into the following types: 1. Near infra-red with a maximum wavelength of 1 pm 2. Middle infra-red with a maximum wavelength of 2 pm 3. Far infra-red with a maximum wavelength of 3 pm.

The far infra-red radiation as obtained from gas burners, has very poor penetration into fabrics, which leads to surface drying, to the migration of dyes not a t that stage fixed and to an increase in depth of colour a t the expense of dye penetration, resulting in an inferior product.

The near infra-red penetrates fabrics well but as a large part of the radiated energy is in the visible part of the spect- rum the quantity of energy absorbed by the fabric depends on the colour of the fabric. This type of radiation cannot usually be employed since it is not possible to adjust the dryer according to the colour of the fabric and fabric damage will occur on multi-coloured or printed fabric.

The middle infra-red is not coloursensitive and penetra- tion into the fabric i s high enough for normal use. Pene- tration can be increased by the use of a slightly higher radia- tion density. Using selected reflectors, w'ith a cotton fabric an energy yield of 90% can be obtained if the moisture content is not less than 30%. Infra-red i s thus recommended for predrying and not for the total drying of the fabric. Compared with hot-airdrying, for a given rate of evaporation, it is cheaper to install the infra-red predryer and it uses less energy per kg of evaporated water. The construction of the

JSDC Volume 98 October 1982 353

first large-scale infra-red predryer, designed according to recommendations given by Mulhouse, was begun in June 1981.

High-frequency radiation can also be used to remove water from text i les [31.

CONCLUSIONS This paper has attempted to indicate the peculiar situation which exists in France and which faces the French textile finishing industry, both regarding the overall reduction in

Publication Sponsored by the

Qualit y-cont rol

energy consumption and the requirement to increase signi- ficantly the amount of electrical energy used. General methods by which energy consumption can be reduced have also been indicated.

RE FE R E NCES 1. Diemunsch e t al., Textilveredlung, 11 (1976) 381. 2. Freytag, Viallier and Marchall, C.R. 9 Congres Union

3. Hulls, J.S.D.C., 98 (1982) 251. lnternationale Electrothermiciens, Cannes (Oct 1980).

Adjacent Fabrics MI BeaI

Society’s Fastness Tests Co-ordinating Committee - 49

Procedures for SDC

Ciba-Geigy (ADP) Co. Clayton Manchester M I 1 4AR

The Adjacent Fabrics Subcommittee of the Society‘s Fastness Test Co-ordinating Committee has recently been reviewing i t s procedures for controlling the quality of the single-fibre and multifibre adjacent fabrics that are available through the Society.

At present, to ensure that every batch is of consistent quality, the staining characteristics and, where appropriate, the wettability, fluidity, pH and FBA content of each new delivery are checked. In the case of multifibre fabric these checks are carried out on the component yarns; the staining characteristics of each component are then rechecked in the woven fabric. Finally, before despatch to the purchaser the fabric i s visually inspected for physical flaws.

To improve quality with respect to staining properties, a tes t method has been adopted that allows the use of a wide range of dyes. T h i s test has been devised especially for monitoring the staining behaviour of adjacent fabrics in wash- ing tests, although it may be used for someother wet-fastness tests. When a new batch of material i s under tes t as an adjacent fabric, a sample of the standard reference material is subjected to the same staining t e s t a t the same time.

The washing test is carried out using the adjacent fabric,

such as the multifibre fabric, without any dyed or printed fabric being present Instead a small amount of dye solution is included in the liquor. The amount i s adjusted to give a staining of the standard adjacent fabric of about 3-4 on the grey scale for assessing staining, whilst ensuring that there i s dye left in the t e s t liquor a t the end of the test.

The staining of the fabric under tes t as an adjacent fabric is then compared with the staining of the standard reference material. The staining properties of the fabric under test is acceptable when the colour difference between the staining of the standard and that of the adjacent fabric under test i s not greater than half a point on the same grey scale as above.

This test has been used satisfactorily for the quality control of nylon and cotton, and i t s use could be extended to other fibres. By using a combination of different types of dye, a control procedure can be devised to assess ‘the staining behaviour of most or al l of the components of the multifibre simultaneously, although, as yet, each fibre in the multifibre fabric is being separately tested by this procedure.

The Adjacent Fabrics Subcommittee is confident that the above method of test will enable the Society to continue to supply materials of uniform and consistently reliable quality. Consequently, a l l current and future deliveries of multifibre fabric supplied by the Society will be accompanied by a guarantee that the fabric i s from a batch of tested quality.

354 JSDC Volume 98 October 1982