Solar Energy Vol. 42, No. 4. pp. 311-318, 1989 0038-092X/89 $3.00 + .00 Printed in the U.S.A. Copyright © 1989 Pergamon Press plc

SCOPE FOR SOLAR ENERGY UTILIZATION IN THE INDIAN TEXTILE INDUSTRY

SAN JAY GUPTA Department of Textile Technology, Indian Institute of Technology, Hauz Khas, New Delhi 110016

Abstract--A case is made out for the use of solar energy in meeting the energy requirements of the textile industry. The paper gives a brief review of the energy resources available in India and the re- quirements of the textile industry, and discusses the utilization potential of solar energy. Some case studies and details of the solar systems for textile processing are discussed.

1. INTRODUCTION

The Indian textile industry has gone through nearly two decades of fuel shortage resulting from energy crises. There is now widespread realization of need for energy conservation spurred by rising energy costs (Table 1).

The question arises as to how to conserve energy and reduce the increasing energy costs? In this re- gard, no revolutionary advancement in technology can be said to have been made. Apparently, energy con- servation will have to be achieved by stringent house- keeping and maintenance, using shortened and mod- ified process sequences and development of new plants and machinery[l] . It is expected that such means if used effectively can bring about 25-35% reduction in energy demands.

Modernization through plant and machinery de- velopment has proved very effective in reducing en- ergy consumption. This however involves huge cap- ital investment, which few mills can afford at the moment. Most textile mills will therefore be depend- ing on improved inhouse maintenance of their old machines. Reduction in energy consumption through process modification can at most be minimal. In most process modifications speciality chemicals are uscd to bring down the operating temperatures or time, thereby saving energy. However, what all is achieved is substitution of thermal energy by chemical energy, real energy savings being very small.

In countries beset with energy crises and slow rates of economic development, such as India and the de- veloping countries, energy savings to the extent of about 12-15% alone may be possible by using the above mentioned procedures. In such situations, uti- lization of the energy from the sun might be an ef- fective way of cutting further rises in energy costs. This point is brought out by the following discussion.

2. INDIA's C O M M E R C I A L ENERGY SOURCES[2]

The energy consumption pattern in India is given below to relate the needs of energy with energy sup- ply position. Presently, the four major commercial energy sources of Ind ia - -coa l , electricity, oil and gas - -accoun t for a little over half the total energy

used in the country with the industrial sector alone consuming about 57% of this commercial energy in the form of coal and electricity. Non-commercial re- sources such as cow-dung, fuelwood, and agricul- tural waste are not important for industry.

The total estimated resources of coal in India are 1.5 × 105 million tonnes. The reserves may amount to about 60,000 million tonnes. Current trends show that these resources may be sufficient for about 130 years.

Annual energy potential from hydroelectric re- sources has been estimated to be 472.15 TWh (bil- lion k w h units), i .e. , 89,830 MW at 60% load fac- tor. Although there is four-fold hydro potential, it may remain unharnessed due to ecological considerations.

Power generation through nuclear energy is being actively pursued as we have at present about 70,000 tonnes of uranium resources and thorium reserves ex- ceeding 3.6 x 105 tonnes, which when used in breeder reactors would be equivalent to 600 billion tonnes of coal. However, the expensive breeder technology is yet to be perfected. Further, when nuclear power be- comes available, it will be at certain centralized lo- cations; its distribution to remote areas is going to be difficult and expensive.

Oil and gas reserves have been estimated at 511 million tonnes and 504 billion cubic metres (as of 1985). These may last for about 15-20 years.

It is expected that when accessible oil resources are depleted the price of coal will rise. Thus the en- ergy supply position may become increasingly dif- ficult in future. Therefore, industry must increasingly rely on renewable energy resources such as solar energy.

Exploitation of solar energy can be quite effective in India, for there are about 95% clear sunny days with average daily incidence of solar radiation at 5000 Kca l /m2/day for 8 - 1 0 hrs a day over most of the calendar year (Fig. 1) [3].

3. UTILIZATION POTENTIAL OF SOLAR ENERGY IN TEXTILE INDUSTRY

The energy requirements of the textile industry is a small fraction (~2%) of the total energy require-

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312 S. GUPTA

Table I. Escalation in the cost of energy for textile production over the period 1973 to 1987 at two major centres

in India

Ahemadabad Bombay

Energy cost 1973 1987 1973 1987

1. Steam (p/kg)* 3-4 28-30 8 28-30 2. Power (p/kWh)* 25 100-125 25 100

Energy cost as % of the total cost of manufacture 3-4 15-16 4-5 19-20

*Here p stands for Paisa which is equal to about 0.0007 US$.

ments of India. In terms of coal equivalent, the re- quirement will be 4 .8 -9 .6 million tonnes of coal (3 .3- 6.6% of the total coal mined[4]). Wet processing of textiles alone consumes 80% of this energy. A typ- ical mill processing about 1.0 x 105 m (or 10,000 kg) of cloth per day requires about 2 million 1 of water and about 2 × I0 s Kcal of thermal energy (20 tonnes of oil or 50 tonnes of coal equivalent) per day. Average steam consumption per kg of cloth comes out to 25 -30 kg, out of which 18-24 kg is consumed in various wet processing units. The estimate of water and steam requirements of different units in a typical textile mill are listed in Tables 2 and 3, The tables show that, although process heat requirement span a

broad temperature range, almost 90% of heat is used at temperatures which can be provided by currently available commercial solar collectors.

The hot water requirement for soaping, washing, boiler feed, dyeing machines and low temperature processes can be provided by selectively coated flat plate collectors. Air heaters may be used in drying of yarn, processed and finished cloth. Solar concen- trations such as ovens, vacuum tube collectors and line focussing type may also be used to provide low pressure steam for starch preparation, heating, drying. and curing of processed or printed cloth, space heat- ing and humidification. Solar passive heating con- cepts may be used to design buildings with natural

",~,.(kk \ . ' ./"-<'~ / " ~ ~ " ,,. )., . . . . . . .," .~ • - .,..,...%

~ ~ ~ ,- ~.ok I "~ ~.s ",~,~-~,..---, I~'"

= ' ° ) ( ~ "?

Fig. 1. (a) Distribution of mean daily global solar radiation - annual (kWh/m-'/day). (b) Distribution of mean daily hours of sunshine - annual (hrs).

Solar energy in the Indian textile industry

Table 2. Specific hot water requirements in a textile mill

Machine

Temperature Requirement Requirement in l /kg of

(°C) fabric

1. Boiler 90 15-30 2. Sizing 90 2 3. Rope washing 50-60 10-17 4. Kier boil

(a) Open 50-90 3-8 (b) Pressure 50-90 5-10

5. Continuous bleaching (a) Saturator 50-70 1-2 (b) Rope washing 50-60 10-15 (c) Open width washing 50-60 10-15

6. Cloth mercerizing 50-60 10-15 7. Yam mercerizing 70 15 8. Jiggers

(a) Desize/bleach 50-80 5-8 (b) Dyeing 40-90 18-20

9. Winches: (a) Desize/bleach 50-80 45-60 (b) Dyeing 40-90 45-85

10. Package machine (a) Boil 50-90 10 (b) Dyeing 40-90 20-25

11. Beam dyeing (a) Scouring 50-80 30-40 (b) Dyeing 50-90 35

12. Jet Dyeing 80-90 25-30 13. Continuous dyeing 40-90 22-25 14. Open width soaper 60-80 10 15. Water mangle 50-60 3 16. Starch padding 90 2

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space heating by solar energy. Point focussing con- centrators are capable of providing very high tem- peratures and may be used for high pressure steam generation. To achieve these objectives suitable de- signing needs to be done.

4. CASE STUDIES

4.1. Solar Water Heating Systems (SWHS) Solar energy utilization for process hot water seems

to be the most obvious and efficient use of solar en- ergy in the textile industry. The first such system was installed in 1975 at La France Industries[5,6]. Sche- matic diagram of this system is shown in Fig. 2. It utilized 6000 sq. feet of high performance, high tem- perature solar collectors to provide 5000 litres of hot water for dyeing, at 80-90°C.

Subsequently, Department of Non-conventional Energy Sources (DNES) of the Ministry of Energy of Government of India has installed a number of water heating systems in various textile mills all over India. The details about a few of them are given in Table 4. These SHWS use selectively coated flat plate col- lectors to provide hot water within the range of 7 0 - 90°C. The hot water obtained from these system has been put to a variety of uses, including boiler feed, dyeing in j igger , kier and mercerizers. This

development has resulted in considerable savings (Table 4).

4.2. Solar Process steam producing systems A system each of this kind has been reported about

from U.S .A. and Germany. The details of these sys- tems are shown in Figs. 3 and 4. The system at West Point Papperell Mills, Atlanta (U.S .A.) uses 24 sin- gle-axis tracking parabolic trough concentrating col- lectors to heat water for its steam generator[7]. Steam generated is supplied to cylinder drying range of the slasher at 76 psi and 159°C. The plant in Shenan- daoh, Germany, uses 114 parabolic disk collectors to heat silicone oil to 750°C[8]. This oil is used to gen- erate high pressure steam, a part of which is used for knitwear processing and the rest is used to drive a turbine which meets 50% electrical energy require- ment of the Bleyle knitwear factory.

In India only one plant has been erected at a silk factory in Mysore as a demonstration project of DNES. It utilizes highly efficient, medium temperature line focussing concentrators for producing process steam at a rate of 100 kg /h and at a temperature of 150°C[9]. Performance details of this system are still awaited.

4.3. Solar Air Heating System Few solar air heating systems have been devel-

oped for textiles. The schematic diagram given in Fig.

314 S. GUPTA

Table 3. Steam consumption pattern of a typical textile mill

Steam consumption point

Steam Steam consumption Operational

pressure kg/kg of temperature kg/cm" product (°C)

1. Spinning/weaving (a) Space capacity 1.0-1.5 - - 30 (b) Sizing:

Cylinder 2.0-2.5 2.0 Hot air 6 .0-7.0 2.7 100

box 1.0-1.5 0.2 2. Yarn processing

(a) Scouring 1.5-2.0 1.0 60-80 (b) Dyeing 1.0-1.5 4.0 60-90 (c) Boiling 2.0-2.5 1.8 90 (d) Drying 4.0-6.0 3.0 100-120

3. Fabric processing (a) Desizing 1.5-2.0 0.1 40 (b) Pressure kier 2.0-3.0 1.5 130 (c) Open kier 2.0-3.0 0.5 60-80 (d) Jigger scouring 1.5-2.0 1.0 70-95 (e) Rope washing 1.5-2.0 0.5 60 (f) Jigger bleaching 1.5-2.0 1.0 70-95 (g) J Box saturator 1.5-2.0 0.2 60 (h) J Box caustic/peroxide 1.5-2.0 1.0 90-105 (i) Washer 1.5-2.0 0.2 50 (j) Drying range 3.0-5.0 1.8 100 (k) Mercerizing m/c 2.0-3.0 1.5 80

4. Dyeing (a) Jigger dyeing

-Reactive & Vat 1.0-2.0 2.0 50-75 -Sulfur & others 1.0-2.0 1.0 95-100

(b) Padding for dyeing 1.0-1.5 0.2 30-90 (c) Winch dyeing 1.0-2.0 6.0 50-75 (d) Winch washing 1.0-2.0 2.0 60 (e) Beam dyeing m/c 4 .0-6.0 5.0 120-130 (f) Jet dyeing m/c 4 .0-6.0 4.0 130-140

5. Printing (a) Polymeriser 6 .0-7.0 0.8 130-150 (b) Ageing 2.0-2.5 2.5 50 (c) Soaper 1.0-1.5 1.5 80 (d) Color kitchen

(per kg of color) 1,0-1.5 0.2 80 (e) Drying 1,0-2.0 2.0 100

6. Finishing (a) Stenter 6,0-7.0 2.2 130-150 (b) Calendar 2,0-2.5 0.4 90 (c) Float dryer 6 .0-7.0 2.4 125-150

• L_AJ °nger P . , . ' . . 4 ]_J exchanger J ~ I exch- ~ N

Existing steom line

Fig. 2. Solar dye beck heating system of La France Industries, South Carolina, U.S.A.

bec k

Solar energy in the Indian textile industry

Table 4. Solar water heating systems erected in various Indian textile mills

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Mill

Capacity and water

temperature Duration of

Installed Operative No. of Hot water operation Lpd °C Lpd °C collectors usage Days/yr hrs/day Net savings*

1. Indore Malwa 12000 85 I0000 80 191 Boiler feed 300 6-8 United Mills Ltd. water

2. Western India 6000 85-90 6000 80 96 Spinning and Mfg. Mills Bombay

3. Erode Textile 48000 70 35000- 70 560 Mills, Tamilnadu 40000

4. Muir Textile 6000 85 6000 70 96 Mills, Kanpur

5. Avanti Processors 15000 85 - - - - - - (Ujjain, MP)

Jiggers 200 6

Jiggers, kier mercerizers, & boiler feed Jiggers

Boiler feed

355 3

300 7

Rs. 39,000 p.a. (in terms of coal) Rs. 53,000 p.a. (in terms of fuel oil)

Rs. 1, 20,000 p.a. (in terms of coal) N.A.

Not yet installed.

*1 US$ = about Rs. 14

t

Slashers

Solor boiler

4.

Steom loop

t "1 I I

:- I 1 ~ I

Collector loop Fig. 3. Solar drying system of West Point PapperelI Mills, Atlanta, U.S.A.

Turbine for electricity

boiler Solar

Knitwear pressing

S t e a m loop

Collector loop Fig. 4. Solar total energy project in Shenandaoh, Germany.

316 S. Gu~A

Hot Qir " - ~

"o.'n'o. b I ~ \ / .

25~ . ~ ' % %~\\" soL.,-- / the oco[ rl /,:' ' ~ H ~ x . ~ \ :r / insulation ~ / / ~ - q ~ . ~ / aa /

H/ /

. . . . . ~ ~ blower

Fig. 5. Solar fabric dryer.

\ Booster mirror

j LOAD

G lazings Load or padded fabrics Absorber plate Glass wool insulation Fibre glass body

Fig. 6. Schematic diagram of the solar oven showing its various components and the path taken by the solar insolation.

6"Insulation

K ier 150 lit res

75 "c

"4 ',j

Xl Xj Xj

',j

X~ Xi

y

Solar energy in the Indian textile industry 317

.S. Heat xchonger

. ~

8s'c

2 3 / / / / / ~

Alternative h eat in 3 source

T

/ 9o'c / / / /

/ / / / / /

/ Pump

L M.S. Storage tank ( 2 0 0 Itrs. c a p a c i t y )

Select ive solar panels

10 metre

Pump

~- --Temperature probes

Flow meters m

Pump f low r a t e - - 900 litre /hour

Fig . 7. S c h e m a t i c d i a g r a m o f the so la r k ie r set*up.

5 provides details of a solar fabric dryer developed at Varanasi (India)[10]. This device is quite effective in that it utilizes air, heated by a solar air heater, and blowed by a modified blower to dry fabric 60-70 times faster than open sun drying.

5. EXPERII~IENTS AT T H E TEXTILE D E P A R T M E N T ,

l iT DELHI

A study at this Department aims at developing suitable technology for solarization of Indian Textile mills (solarization is supplementing fossil fuel with solar energy). The two solar processes that have been designed thus far are described below.

5.1 . S o l a r o v e n

It is a "hot box" type flat plate collector, inside which fabrics padded with chemicals is kept. A sche- matic diagram of this solar oven is given in Fig. 6. The double glass covers and the booster mirror pro- vided temperatures of about 130°C in summer and 100°C in winter. At the temperatures reached, batch- ing time required for fabric treatment was reduced to 2-3 h from 24 h. Resultant energy savings have been equal to about 100%, with only the electrical energy needed to drive the padding mangles[ 11,12].

It has been found that the oven when slightly modified can be used for curing of printed and fin- ished goods, especially by using low temperature cure

318

chemical formulation or by giving longer storage time in the oven.

5.2. Solar Kier

A conventional kier has been modified by inte- grating it with a SWHS through a heat exchanger. A Schematic diagram of the set-up is given in Fig. 7. Fabric padded in a chemical formulation containing a speciality chemical is piled inside the kier. Open kiering is then carried out for 5 - 6 hrs with the chem- ical solution being heated by the SWHS to 80-90°C. The fabric processed in this kier was comparable in quality to that produced conventionally, with the pro- cessing requiring only 1/5 the time and only a small amount of electrical energy[13]. One such plant of 20-kg capacity is already operational at East India Cotton Mfg. Co. , Faridabad, India, and another plant with a lO0-kg capacity is to be installed shortly.

6. FUTURE STRATEGY

It has been shown above that the utilization po- tential of solar energy in textile industry is signifi- cantly high and application of solar energy in textile industry is actually feasible. The experience already gained and the inferences from available data can provide grounds for future progress in the area.

Any treatment of problems and prospects about use of solar energy in textile industry has to deal with the specific parameters of organized and unorganized sector, separately. The organized sector industries re- quire large quantities of hot water, in the range of millions of litres of water per day. A SWHS for these mills means huge capital investment and a large space for putting up the collectors, which are prohibitive. In the mills where SWHS have been put up for partial fulfilment of hot water requirement, the savings achieved are quite small (Table 4). It can be argued that 4- to 5-fold more savings could have been achieved by conventional heat recovery equipment, without the added difficulties associated with main- tenance of such bulky systems. Now the question is whether to go for solarization. It is important to note here that three temperature levels exist in a textile mill: 65 °, 90 °, and 130°C. Optimum systems for these levels are not of single collector type. Instead of going in for full solarization, one should identify one type, assess total needs and arrange the distribution for best utilization. (Best utilization is when all consumption points are at the same place).

Clearly, it is the small textile units of unorganized sector, numbering in thousands and distributed all over the country, that can reap maximum benefits from solar energy technology. Their production per day is relatively low and so are the requirements for energy.

S. GUPTA

Furthermore, the units are usually located at isolated places with no electricity and /o r steam generation capacity. Decidedly, products like solar fabric dryers, solar ovens and solar kiers can prove useful to these small units, since such systems can work in isolation, without power, steam or any other fuel. In the im- mediate future, solarization effort should be targeted for small units of the unorganized sector.

7. CONCLUSION

Under present conditions, use of solar energy can herald enormous economic benefits for textile indus- try. There is need for research in this area to mould the available technology for its greater exploitation. There is also need for enterpreneurs to make popular the developed products, and for the government to support initial capital investments, because in initial stages solar energy will have to compete unfairly with coal-fired and electrical heating systems.

REFERENCES

1. S. M. Doshi and M. D. Dixit, Modem developments in wet processing. Proc. 25th Technological Confer- ence on Energy Conservation and Management in Tex- tile Industry, Bombay, India (1984).

2. Seventh Five Year Plan Document of Govt. of India. 3. A. Mani and S. Rangarajan, Solar radiations over In-

dia. Allied Publishers, India (1982). 4. M. L. Gulrajani and S. Gupta, Use of solar energy in

textile wet processing. Proc. ACTI Silver Jubilee Sem- inar on Economy, Energy and Environment in Textile Wet Processing, Ahemadabad, India, 7-27 (1987).

5. J. B. Trice, R. O. Spera, S. A. Haas. A. A. Koenig and R. L. McCarthy, Solar energy in textiles. Text. Industries, 140, 71-74 (1976).

6. J. B. Trice and A. D. Chen, Lafrance solar hot water points the way to industry programme. Amer. Dyest. Rep., 67(12), 43-48 (1978).

7. M. E. Beesing, Textile drying using solar process steam. Mech. Engg., 102(1), 40-42 (1980).

8. Anon, Solar collector field halves thermal energy losses. Text. Industries, 148(2), 64 (1984).

9. Annual Report Document of Department of non-con- ventional energy sources, Ministry of energy, Govt. of India (1987).

10. A. S. Myles, Design of a solar fabric dryer. Proc. Na- tional solar energy convention, India. paper 3.008 (1981).

11. M. L. Gulrajani and S. Gupta, Use of solar energy in combined desizing and scouring of cotton. Ind. J. Text Res., 12, 21-23 (1987).

12. M. L. Gulrajani and S. Gupta, A solar energy accel- erated process for combined desizing, scouring and bleaching of cotton fabric. Text Res. J., (in press).

13. S. Gupta and M. L. Gulrajani, Design and develop- ment of a solar powered kier for combined desizing, scouring and bleaching of cotton containing fabrics. Proc. Annual world conference of The Textile Insti- tute, Sydney, Australia (July 1988).