A Review of Energy Consumption in Five Main Production ... · PDF fileAn energy audit team visited the textile plants to investigate ... Energy Index, Specific Energy Cost, Textile

The 2nd Joint International Conference on “Sustainable Energy and Environment (SEE 2006)” E-017 (O) 21-23 November 2006, Bangkok, Thailand

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1. INTRODUCTION

Textile industry is one of the oldest and largest industries in Iran and has employed about 16 % of all workers in manufacturing [1]. Textile share of the total industrial production of the country was around 6 % in the period from 3/21/2002 to 3/20/2003. In spite of the fact that textile industry is a huge industry in the country; it does not play a major role in exports. Only 0.9% of total exports ( except crude oil ) contains textile products and the import of textile and clothing products are about 1.2% of total industrial products imported in the above period [2]. Energy consumption in Iran textile industry is highly inefficient, with huge possibility for improvement [3]. Since the total cost of textile products in Iran is high, this industry is facing the serious problem to compete with the other countries. As a result, it is very important to minimize the specific energy consumption (energy consumption/production) for textile industry to reduce the cost and compete. In general, energy in the Iran textile industry is used in the forms of heavy fuel-oil, gas-oil, LPG, natural gas as a fuel especially for steam generation and electricity as a common power source for machinery, air conditioning system, lighting, office equipment, etc. Spinning, weaving and wet processing sectors have the highest share of energy consumption in Iran textile industry [4].

Iranian textile industry is increasingly seeing the need for accurate data on current and previous energy consumption. These data can be used to (1) determine trends in energy consumption within textile industry as a method of determining the impacts of changes in technology, processes or attitudes about energy, (2) compare Iran textile industry performance to other countries to evaluate competitiveness, and (3) to monitor environmental impacts of energy consumption in textile industry, such as levels of greenhouse gas emissions. However, the status of energy consumption in Iran textile industry is not known. In this study a survey has been carried out to show the specific energy consumption (energy consumption/production) and the specific energy cost (cost of energy/ production) for fifteen factories from five main sectors of Iran textile industry which are located in different provinces of Iran.

2. METHODOLOGY 2.1 Scope of the study

The textile industry is characterized by different kinds of substrates, including many blends, different main process types (continuous, semi-continuous, and discontinuous) and different process steps (fiber production, spinning, weaving, knitting, pretreatment, dyeing/printing, and finishing). Thus there is a high degree of diversity of processes. As a result, process variations leading to an enormous range of different products. Nevertheless, regarding to the product, the processes can be classified into a comparatively small number of groups. The aim of this study was to cover the following activities to find the status of energy consumption and energy cost in these five sectors of textile industry since these sectors are the primary contributors to Iran textile industry. Furthermore, since each sector was homogeneous, it would be possible to select a few sample units in each sector, make assessments and extrapolate the results over the entire sector with a good approximation. These five sectors are as follow:

1. Spinning 2. Weaving 3. Pretreatment, dyeing/printing, and finishing of cotton or polyester fabrics or blended fabrics (cotton/polyester,

polyester/viscose, etc.) 4. Worsted fabric manufacturing 5. Carpet manufacturing

Corresponding author: [email protected]

A Review of Energy Consumption in Five Main Production Sectors of Iran Textile Industry

Ali Hasanbeigi 2,*, Abdollah Hasanabadi3, Ali Ghoba4 and Mohammad Abdorazaghi1

1 Textile Engineering Department, Amirkabir University of Technology, Tehran, Iran

2 The Joint Graduate School of Energy and Environment, King Mongkut’s University of Technology Thonburi, Bangkok, Thailand 3 Textile Engineering Department, Isfahan University of Technology, Isfahan, Iran

4 Shayanik Engineering Company, Tehran, Iran

Abstract: Textile industry is one of the oldest and largest industries in Iran and employed about 16 % of all workers in manufacturing. Energy consumption in Iran textile industry is inefficient, with huge possibility for improvement. For future planning, it is important to know the current energy index (energy consumption/production) and the specific energy cost (cost of energy / production) in order to estimate future energy consumption for the textile sector. However, the status of energy usage in Iran textile industry is not known clearly. In this study, a survey has been carried out to show the current status of energy consumption such as energy index and specific energy cost in some sample plants from five main production sectors of Iran textile industry including: spinning, weaving, wet processing, worsted fabric manufacturing, and carpet manufacturing. An energy audit team visited the textile plants to investigate the condition of energy consumption in these plants and to complete questionnaires which were designed for the purpose. The energy index (specific fuel consumption and specific electricity consumption) and specific energy cost was calculated for each plant. Then, results of the plants in each sector were compared together and analysis for variation in energy consumption was carried out. Keywords: Energy Consumption, Energy Index, Specific Energy Cost, Textile Industry, Iran


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2.2 Methodology To carry out this survey, an energy audit team consists of experts from different engineering background such as textile engineers,

mechanical engineer and electrical engineer was formed. A comprehensive questionnaire was designed for the purpose, consists of information regarding type and amount of products, types of energy being consumed and the amount of energy consumption (electricity, fuels), information about process machinery, utilization and process flow diagram. Over 50 companies from different sectors of textile industry which mostly were big and well known companies with the high production capacity received the questionnaire, yet just a few companies answered the questionnaire completely and properly. As a result, the energy audit team decided to visit textile plants and fill out the questionnaire onsite.

Four spinning plants which three of them (factories A, C, and D) were ring spinning and one (plant B) was Open-End spinning were visited. Therefore, a comparison between energy consumption in ring and Open End spinning which are the most common spinning systems in textile industry was conducted. Two weaving plants with the production capacity more than 6000 (ton/year) of cotton, polyester or blended fabrics (cotton/polyester, polyester/viscose, etc.) were visited. Both of these factories have the preparation (warping and sizing) and weaving sectors. Three dyeing, printing, and finishing plants which processing cotton, polyester or blended fabrics (cotton/polyester, polyester/viscose, etc.) were also studied. Two of them (factories G and H) have the printing process, while another one (plant I) does not have printing process. Furthermore, it worth to mention that in factories G and H the process of preparation and finishing on the fabric were more completed than those of in plant I. Hence, the quality and price of the products of plant G and H is higher than those of in plant I. In worsted sector of textile industry, three plants were visited which are the most famous and biggest worsted factories in Iran. All these plants were complex. In other words, they have all spinning, weaving, dyeing, and finishing sectors.

In case of carpet sector, unfortunately we could not visit more than one plant, yet the good point is this plant is one of the most famous factories in Iran. In this plant in addition to weaving and finishing sector for the carpet, it has fiber dyeing and spinning sectors, as well. According to the data which were obtained from the survey, the energy index (specific electricity consumption and specific fuel consumption) and specific energy cost for each plant was calculated and are presented in this paper for the year 2002 except in case of worsted and carpet sectors which the data were available for 2003. It should be mentioned that in all cases, the specific energy cost is calculated according to the prices of electricity and fossil fuels in Iran in 2003. For electricity, the price is not involving the demand cost, while for natural gas the price is involving the demand cost. Moreover, some practical energy conservation comments were given to the factories to improve their energy efficiency, yet it is not presented in this paper.

3. RESULTS AND DISCUSSION 3.1 Spinning

As mentioned before, four spinning plants were studied. Three of them were ring spinning (plants A, C, and D) and one was Open-End spinning (plant B). All these plants have short staple spinning system which is producing cotton carded yarn, polyester yarn, or blended yarn (cotton/polyester, viscose/polyester, etc.). In all ring spinning plants, part of the production were double ply yarns. Doubling was being done by Tow-For-One (TFO) machines. Just in plant C a small portion of production was being dyed in package dyeing machines.

The type of energy used, annual energy consumption and energy cost for electricity and fossil fuels, and annual production for each plant in 2002 are given in Table 1. Moreover, in Fig. 1 the specific energy consumption for electricity and fossil fuels and in Fig. 2 the specific energy cost is presented.

Table 1 Annual energy consumption, energy cost, and production for spinning plants in 2002

Annual energy cost Energy type Annual energy consumption (US$)* (%)

Annual production (Ton)

Electricity(kWh) 13290450 265809 97 Heavy fuel oil (Lit) 626050 6887 3 Plant A Total 272696 100

2003

Electricity(kWh) 8860300 177206 97 Heavy fuel oil (Lit) 500840 5509 3 Plant B Total 182715 100

2448

Electricity(kWh) 37309000 746180 95 Heavy fuel oil (Lit) 3922300 43145 5 Plant C Total 789325 100

6687

Electricity(kWh) 38584206 771684 98 Heavy fuel oil (Lit) 784692 8632 1 Natural gas(m3 ) 677397 8806 1

Plant D

Total 789122 100

8140

*: 1US$ ≈ 8000 Rials

As can be seen from Table 1, in all spinning plants, the huge amount of electricity was being used which is mostly for machinery, air conditioning system, and lighting and its cost’s share from the total energy cost is more than 95%. However, the small amounts of fossil fuels are used for steam generation. The steam was used in air conditioning system for heating in cold seasons.

Figure 1 shows that specific electricity consumption in plant B is significantly less than other factories. The reason could be that plant B has Open-End spinning system which has the shorter process in comparison with ring spinning system (factories A, C, and D). In addition, the production capacity of Open-End spinning machine is higher than ring spinning machine. Furthermore, because of


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the fact that in Open-End spinning system, we have shorter process with less machinery, the volume of spinning building which requires air conditioning is smaller. As a result, the load on air conditioning system will be less and the energy will be consumed less.

The specific fuel consumption in plant B is less than factories A and C. The reason is related to less air conditioning load. Despite the fact that plant B is Open-End spinning and plant D is ring spinning, there is not too much difference between specific fuel consumption in plant B and D. It can be described as, plant D is located in a city which has a hot weather and there is just four cold months, but other plants are located in cities which have about six cold months. As a result, in plant D, steam required for heating is used in a shorter period of time during a year.

Another important point which can be seen from Fig. 1 is that in plant C, the specific fuel consumption is surprisingly higher than others. As mentioned before, in plant C, part of the yarn produced was being dyed in package machines. Since dyeing process consumes the high amount of steam, it causes increase in specific fuel consumption in plant C. The specific energy cost in plant A is higher than others since the amount of electricity used in this plant is higher than others and, as it is shown in Table 1, the portion of electricity in total energy cost is significantly higher (more than 95 percent in all cases) than the portion of fossil fuels. The specific energy cost in plant B is less than others because for producing one ton of yarn, both electricity and fuel were consumed less in Open-End spinning system in comparison with ring spinning systems.

3.2 Weaving

Two weaving plants were producing cotton, polyester or blended fabrics (cotton/polyester, polyester/viscose, etc.) and both of them have the preparation (warping and sizing) and weaving sectors. The portion of electricity in total energy cost is significantly higher (about 90 percent in both cases) than the portion of fossil fuels (Table 2). In weaving plants, fuels were used for producing steam which was consumed in sizing machine and also in air conditioning system in cold months. In Fig. 3 the specific energy consumption for electricity and fossil fuels and in Fig. 4 the specific energy cost are shown.

Table 2 Annual energy consumption, energy cost, and production for weaving plants in 2002

Annual energy cost Energy type Annual energy consumption (US$) (%)


Electricity(kWh) 13290450 265809 90 Heavy fuel oil (Lit) 2629410 28924 10 Plant E Total 294733 100

6027

Electricity(kWh) 7420040 148401 88

Heavy fuel oil (Lit) 959068 10550 6 Natural gas(m3 ) 748701 9733 6

Plant F

Total 168684 100

6299

Fig. 1 Specific energy consumption for spinning plants in 2002

Fig. 2 Specific energy cost for spinning plants in 2002

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Fig. 3 Specific energy consumption for weaving plants in 2002 Fig. 4 Specific energy cost for weaving plants in 2002

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Figure 3 shows that the specific electricity consumption in plant F is less than E. One reason could be that in plant F, the weaving machines were projectile and consume less electricity in compare with rapier weaving machines used in plant E, in a same production condition. In addition, it was seen that, in plant F, the efficiency of the weaving machines was higher than that of in plant E and with fewer weaving machines the capacity of production in plant F was higher. In plant F, the average width of fabrics produced on weaving machines was higher than average width in plant E. This can cause reduction in energy index since the amount of fabric in kilogram produced in specific number of peaks on weaving machine can be higher. The specific fuel consumption in plant F is also less than E. In addition to higher efficiency in plant F, another important reason can be that plant F is located in hot area which has about four cold months, but plant E is located in an area which has about six cold months. Furthermore, since there are less weaving machines in plant F and building is smaller, less steam is required in air conditioning system for heating. 3.3 Pretreatment, dyeing/printing, and finishing

For this sector, three plants were studied. The types of fabrics being processed in these plants were cotton, polyester or blended fabrics (cotton/polyester, polyester/viscose, etc.). Therefore, different kind of dyestuff and chemical auxiliaries and various types of machines were being used in these plants.

Table 3 Annual energy consumption, energy cost, and production for dyeing/printing and finishing plants in 2002



Electricity(kWh) 8860300 177206 59 Heavy fuel oil (Lit) 8764700 96412 32 Gas oil(Lit) 1279200 24305 8 LPG(Lit) 104400 3028 1

Factory G

Total 300950 100

3531

Electricity(kWh) 3462685 69254 52 Heavy fuel oil (Lit) 2615640 28772 22 Natural gas (m3) 2139147 27809 21 LPG(Lit) 228000 6612 5

Factory H

Total 132447 100

2296

Electricity(kWh) 2553000 51060 76 Heavy fuel oil (Lit) 895400 9849 15 Gas oil(Lit) 352900 6705 10 Factory I

Total 67615 100

1200

From Table 3, it can be concluded that in this sector, in contrast with spinning and weaving sectors, fossil fuels have a significant

portion of energy cost since most of the processes in these plants need steam or other kind of heating source like hot oil.

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Fig. 5 Specific electricity consumption for dyeing/printing and finishing plants in 2002

Fig. 6 Specific fuel consumption for dyeing/printing and finishing plants in 2002

Fig. 7 Specific energy cost for dyeing/printing and finishing plants in 2002

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Plant G has the highest specific electricity consumption and plant H has the lowest (Fig 5). Comparing with other plants, the machines and equipment in plant H were newer and most of motors in machineries have inverters and they have high efficiency. However, Fig. 6 shows that specific fuel consumption in plant I is the lowest one. As it is mentioned before, plants G and H have the printing process, while plant (I) does not have printing process. In addition, in plants G and H the process of preparation and finishing are more completed than those of in plant I. As a result less thermal energy which is the main consumed energy in this kind of process is required in plant I. In plant G, the average width of fabrics was less than that of in plant H and I. This could result energy waste in some machines. For instance in cylinder dryer, the more the width of fabric is less than the width of machine that can be used; the more energy will be wasted.

3.4 Worsted fabric manufacturing

In worsted sector as well as dyeing and finishing sector, three plants were visited. All these plants were complex; they have spinning, weaving, dyeing, and finishing parts. The worsted fabric typically contains 45% wool fiber and 55% polyester fiber. These two fibers were being blended in spinning. The weaving machines in all plants were rapier type. There was a variety of machines in dyeing and finishing part of these plants from different companies. However, generally, the dyeing and finishing machinery in plant J were more modern than those of in other plants. In contrary, spinning and weaving machinery in plants k and L is newer than plant J Since they reinstall new machinery for these sectors. Table 4 shows the annual energy consumption, energy cost, and production in each worsted plant in 2003.

Table 4 Annual energy consumption, energy cost, and production for worsted plants in 2003


Annual production (m2)


Heavy fuel oil (Lit) 3212295 35335 9 Gas oil(Lit) 244025 4636 1

Factory J

Total 382753 100

4122395


Natural gas(m3 ) 5632247 73219 20 Factory K

Total 362498 100

4149787


Natural gas(m3 ) 2001719 26022 24 Factory L

Total 108189 100

1094179

Since spinning and weaving are the main electricity consumers in worsted factories and plants K and L have the newer spinning

and weaving processes, the share of electricity price from the total energy price in these two plants is significantly lower than that of in plant J. One we should add here is that since in plant J dyeing and finishing machinery are modern, for producing a unit of product the fuel consumption in these processes is less in compare with the other plants.

Plant L has the highest specific fuel consumption since machinery in dyeing and finishing sector in this plant is older than other plants and the efficiency of them is not as high as other plants. In addition, the amount of redyeing in plant L is high. However, specific energy cost in plant K is the lowest one. Despite of the fact specific fuel consumption in plant K is more than plant J, the specific energy price in this plant is lower since the specific electricity consumption in plant K is lower and the cost of electricity has the major impact on the specific energy cost. 3.5 Carpet manufacturing

The plant that was visited in carpet sector has fiber dyeing, spinning, weaving, and finishing parts. Acrylic fibers were dyed in dye house. In spinning, the double ply acrylic yarn with yarn count Nm=10/2 was produced. In weaving, in addition to acrylic yarn used as pile in carpet, jute yarn with yarn count Nm= 4.8 was used as weft and the blend cotton/polyester yarn (35/65) was used as warp yarn. Several finishing process such as primary control, brushing, shearing, darning, etc. were done on the carpet. The size of carpets considered for calculating energy index and specific energy cost is 12 m2. Table 5 shows the annual energy consumption, energy cost,

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Fig. 8 Specific energy consumption for worsted plants in 2002

Fig. 9 Specific energy cost for worsted plants in 2002


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and production for this carpet manufacturing plant in 2003. The specific electricity and fuel consumption and specific energy cost are presented in Table 6. Despite the fact that specific fuel consumption is about four times more than specific electricity consumption, about 75 % of annual energy cost in this plant is electricity cost. This is because the higher price of electricity in compare with gas oil.

Table 5 Annual energy consumption, energy cost, and production for carpet manufacturing plant in 2003

Annual energy cost Energy type Annual energy consumption (US$) (%) Annual production (Carpet)

Electricity(kWh) 4918640 98373 76 Gas oil(Lit) 1638000 31122 24 Total 129495 100

31252

Table 6 Specific electricity and fuel consumption and specific energy cost for carpet manufacturing plant in 2003

specific electricity consumption (GJ/Carpet)

specific fuel consumption (GJ/Carpet)

specific energy cost (US$/Carpet)

0.6 2.3 4.1

4. CONCLUSION

For future planning, it is important to know the status of energy consumption in textile industry. In most of the plants which were visited in this survey, the energy efficiency was very low. It was predicted that at least 10-15% energy savings would be achievable in these plants without further investment. In weaving, wet processing, worsted fabric, and carpet sectors the share of thermal energy consumption is considerably higher than electricity consumption, whereas in spinning the share of electricity consumption is higher than thermal energy consumption.

Since in Open-End spinning system, in compare with ring spinning system, the process is shorter, energy required for the process machinery is less and the volume of spinning building which requires air conditioning is smaller and the load on air conditioning system will be less. In the same production condition, the production capacity of Open-End spinning machines is also higher than ring spinning machines which will cause reduction in energy index. Therefore, according to the end use of the product an appropriate spinning system should be installed in spinning plants. The type and efficiency of weaving machines are two important factors affecting the energy index in weaving plants. The type of machines used in weaving, dyeing/ printing and finishing is also important that can affect energy index. The use of new and modern machines and also optimum use of them is the key to optimize energy consumption in a plant. In a complex worsted plant, electricity is mainly used by spinning and weaving sectors and thermal energy is mainly used by dyeing and finishing sector in the plant. By optimizing the control on the process specially in dyeing, we can reduce reworking which will cause energy waste

For further study the number of the factories should be increased to get more extensive results. Since the number of the plants in this survey is limited, the values could not reflect the exact status of energy consumption in textile industry. However, they can give approximate values about specific energy consumption and specific energy cost in main sectors of Iran textile industry.

5. ACKNOWLEDGMENTS

This survey was performed by the support of Iranian Fuel Conservation Organization (I.F.C.O) and cooperation of Shayanik

Engineering Company. The authors would like to thank staff of Shayanik Engineering Co for their kind cooperation and comments. The authors furthermore wish to acknowledge the contribution of Ms. Elhambakhsh, the staff of IFCO, in this survey. Special thanks to all companies that participated in this survey and those who helped us to complete this survey.

6. REFERENCES

[1] ISC, Iranian Statistics Center, Statistics of industrial manufacturing, 2002, 1st edition. Vol. 1, 2. [2] The customhouse, statistic and data processing bureau; a brief review on Iran’s foreign trade statistics in 2000-2003, pp. 5-7. [3] Iran Energy Efficiency Organization (IEEO), 1999, Project report: Energy optimization in Iran textile industry,

http://www.saba.org.ir [Accessed: September 10, 2006] [4] Iranian Fuel Conservation Organization (I.F.C.O), Industrial sector, http://www.ifco.ir , [Accessed: September 5, 2006]

Documents

A Review of Energy Consumption in Five Main Production ... · PDF fileAn energy audit team visited the textile plants to investigate ... Energy Index, Specific Energy Cost, Textile