Environmental Issues & Solution for the Textile Sector

Transcription

1 Orientation Programme for GPCB on Environmental Issues & Solution for the Textile Sector July 06, 2013

2 Presentation on Overview of Opportunities for Improvements in Textile Sector Nitesh Patel Junior Advisor GIZ-IGEP, Gandhinagar

3 Transformation of raw textile product to final usable form involves four different stages. 1. Fibre production 2. Intermediate dry processes like spinning, weaving and knitting 3. Intermediate wet processing like slashing, desizing, kiering / scouring, bleaching, mercerising and dyeing and 4. Finishing like printing, cutting, stitching, packing etc. Note: Source of major environmental issues - intermediate wet processing carried out on yarn or fabric

4 Inputs to wet processes Sizing Desizing Scouring Polyvinyl alcohol, Carboxy methyl Cellulose, Oils, Waxes, Adhesives, Urea, Diethylene glycol, etc. Enzymes, Sulphuric acid, Detergents and Alkali Sodium hydroxide, Sodium Carbonate, surfactants, chlorinated solvents Bleaching Hypochlorite, hydrogen peroxide, acetic acid. Mercerization Sodium hydroxide, surfactants, acid, liquid ammonium Dyeing Dyestuffs, auxiliaries, reductants, oxidants Printing Chemical finishing Dyes (acids or alkalis), pigments, kerosene, binders, ammonia, xylenes. Formaldehyde, phosphorus, ammonia, silicone, fluorocarbon resins, toluene, zircon salts etc.

5 Unfixed Dyes for Various Processes Fabric Dye type Unfixed dye (percentage) Acid dyes/reactive dyes for 7 20 Wool and wool Nylon Pre-metalized dyes 2 7 After chromes 1 2 Azoic dyes 5 10 Reactive dyes Cotton and Direct dyes 5-20 viscose Pigment 1 Vat dyes 5 20 Sulphur dyes Polyester Disperse 8 20 Acrylic Modified basic 2 3 Polypropylene Spun dyed N/A Source: Water and Chemical use in the Textile Dyeing and Finishing Industry (GG62 Guide) (

6 Finishing Industry (Textile wet processes) - Waste Water & Solid Waste Process Input material Function (purpose) Desizing Scouring Bleaching (for natural fibres) Singed fabric, Enzymes, Acids (Sulphuric) Knitted or desized woven fabric, Alkaline or solvent Solutions Scoured fabric, hydrogen peroxide, Hypochlorite To remove size material from woven fabric Cleaning fabric from impurities Eliminating unwanted colour matter decolorizing colour Impurities Product Effluent Fabric free from size Clean fabric White bleached fabric BOD from sizes, lubricants, biocides, antistatic Compounds High BOD and temperature very high ph, fats, waxes, detergents, size mix residues, solvent residues Solid wastes Fibre lint, yarn waste, cleaning materials Little or no residual waste Low to moderate BOD, high ph and Little or temperature, bleach more and additives Residues

7 Process Mercerizing Dyeing Printing Input material Woven or knitted cotton fabric, Caustic soda (15-20%), Acid Woven or knitted fabric, dye stuffs, auxiliaries, reductants and Oxidants Woven or knitted fabric, pigments and dyes, acids or alkalis, softener, binder, emulsifier Solvents Function Product (purpose) To give lustre, Mercerized more strength, woven or and higher knitted affinity for Dyes fabric Add colour and intricacy to fabrics Printing colour and patterns on Fabric Dyed fabric Printed fabric Effluent Very high ph, dissolved solids, some, BOD, NaOH Depending on type of dye, dissolved solids, COD, heavy metals causing toxicity, BOD High COD and salt content solvents toxic metals BOD, foam, heat Solid wastes Little or none Chemical residues, fabric scrap Chemical residues Source: Self-Monitoring Manual, Textile Industry, Egyptian Pollution Abatement Project, Ministry of State of Environmental Affairs

8 Water Consumption & Effluent Discharge from Wet Processing Activities Water consumption (Litres/100 kg) Variation Average Effluent Variation (Litres/100 kg) Sizing / Slashing Desizing Kiering / Scouring Bleaching Yarn (Hypochlorite) Yarn (Hydrogen Peroxide) Cloth (Hypochlorite) Cloth (Hydrogen Peroxide) Mercerising Dyeing Yarn (Light and Medium Shades) Yarn (Dark Shades) Yarn (Vary Dark Shade) Cloth (Light and Medium Shades) Cloth (Dark Shades) Cloth (Very Dark Shade) Source: Data computed from Manivasakam (1995) and MSE Study (1998)

9 The drying process

10 Challenges and solutions in the drying process Challenges: Rotating at rpm Normally industries insulate with glass/mineral wool Water resistance very low Insulation peel off within 2-3 month Promote corrosion Solution: Resin bounded mineral wool slabs Water vapor resistance factor: 1 Chemically neutral, neither cause nor promote corrosion

11 Economic savings and payback time Drying Drums, Nos 38, Ø1.5m, No 1, Ø 4.5m Total not insulated area: 128 m 2 Temperature: 120 C What is the impact if this drums were insulated up to the latest standards: Investment: Rs. 500,000 Cost Savings: Rs. 1,200,000/ Year Payback time: 5 Month

12 Waste Heat Recovery from Jet Dyeing Machines The drained water from jet machines is passed through one side of the shell and tube heat exchanger and cold water to be heated on other side

13 Case Study of Surat Cluster S. No. Parameter Units Details 1. Quantity of hot water drained available liters/day Average quantity per day (80%) liters/day Temperature of hot drain water 0 C Quantity of heat can be recovered kcal/day Present Boiler efficiency %age Calorific value of fuel kcal/kg Fuel savings per day kg/day Operating days per annum days Fuel saving per annum Tonne/annum Fuel cost Rs./tonne Monetary savings per annum Rs. In lakh Investment for tank, heat exchanger and Rs. In lakh 3.11 pumping system 13. Payback period Year 1.08

14 Exhaust Control from Stenter Machines Stenters are mainly used in textile finishing for heat-setting, drying, thermosol processes and finishing. In fabric finishing, each textile substrate is treated on average 2.5 times in a stenter. Stenter happens to be the largest Energy Consuming Machinery available in a textile Dyeing and Finishing Industry. Thermal Energy required for stenters is supplied by Thermopac. The hot thermal fluid at a temperature of 235 C to 300 C Energy consumption of energetic optimized stenters is in the range of kj per kg of textile (1-1.5 kg of coal). Manual control of exhausts is generally very difficult since the expected airflow patterns and the ones found in practice vary considerably Hence the tendency to leave them fully open Optimisation of exhausts can be achieved by controlling the exhaust humidity to between 0.1 and 0.15 kg water/ kg dry air

15 Typical Sankey diagram for a stenter having Energy Conservation Measures Typical Sankey diagram for a stenter having no Energy Conservation Measures

16 Investment: Rs. 3,50,000 Cost Savings: Rs. 2,00,000/ Year Payback time: 21 Month

17 Thermal Energy Recommendations Implemented by the process house unit situated in Mumbai Installation of automatic blowdown control system at boilers; about 50% blowdown quantum reduced. Repair of pressure reducing valves in 14 steam supply lines. Attending malfunctioning steam traps (32 Nos.) Closing trap by-pass line valves (13 Nos.) Providing individual trapping system instead of group trapping system at 3 drying range machines.

18 Thermal Energy Recommendations Implemented by the Unit Replacing/repairing punctured/leaking condensate lines in Finishing section. Installation of heat recovery system from hot effluents available from initial washes in Open Width Bleaching Range. Installation of automatic control valves in the drying range machines Plugging steam leakages (75 Nos.). Thorough cleaning and tuning of Thermopac No.1, its thermal efficiency improved from 75 to 79%.

19 Fuel Saving (FO) : 380 KL (Rs.40 lakhs)/annum. Fuel saving as % of consumption : 3%

20 CONSERVATION OF WATER IN TEXTILE Sources for Waste Water Generation in Textile Industries BLEACHING in Preparatory Section Of Processing. COOLING WATER for the Jet Dyeing Machine / Rubber Belt AFTER WASH is one of the MAJOR waste water generating Source In Dyeing MORE THAN 7 TIMES WATER is used in After Wash than in Dyeing Process WASHING UNIT WATER of Printing M/C Blanket & Washing Of Screen Most of the Waste Water is COLOURED HOW TO REDUCE THIS?

21 WATER CONSERVATION OPPORTUNITIES IN BLEACHING 1. Re-use of Collected Water from Various Bleaching Processes Waste Water Source Waste water from acid wash Waste water from chemick wash Re-use Destination Raw water for chemick wash Raw water for kier wash & de-size wash 2. A- counter current system in washing m/c. 3. Water Saving in Bleaching by Continuous Bleaching Range (C.B.R.) Conventional Bleaching Water requirement 20 To 25 liters per Kg. of fabrics Economical if per day production is lesser than 5,000 Kg Or 50,000 meters Continuous Bleach Range Water requirement 10 To 12 liters per Kg. of fabrics Economical if per day production is more than 10,000 Kg Or 1,00,000 meters

22 4. Resource Saving by Bio Scouring Process (Newly Developed Process) Parameters Conventional Process Bio-Scouring Process Difference Total turns turn Batch time 18 Hrs 10 Hrs - 8 Hrs No. of drains Drains Water consumption 3900 lit / batch 2400 lit/ batch lit/ batch Chemical cost Rs./kg Labor cost Rs./kg Electricity kw/kg Steam kg/batch No Caustic Boil as well as No Chlorine used

23 WATER CONSERVATION OPPORTUNITIES IN DYEING 1. After wash is required to remove the un-fixed dyes from the fabrics this generates colored effluent 2. If the dye is more fixed on the fabrics the requirement of after wash can be reduced 3. Use of bi / poly functional dyes can reduce the water consumption and waste load in effluent 4. Change of the process of dyeing can help in water conservation

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26 Minimum two after washes saved 800 liters per batch per jigger of 1000 meters 800 liters x 2 washes = 1600 liters water per batch of 1000 meters if we have dyed / printed 10,000 meters of the fabrics with bi-poly functional dye 1600 x 10, = liters of water can be saved

27 COLD PAD BATCH DYEING 1. Significant cost and waste reduction as compared to conventional method 2. Total elimination of the need for SALT and other specialty chemicals like anti migrants, leveling agents [Reduces chemical cost, waste load in effluents 3. Optimum utilization of dyes. 4. Excellent wet fastness properties. 5. Cuts energy cost (no steam required), Temperature is not required for fixation 6. Cuts water consumption due to low bath ratio 7. Uniform dye quality achieved with even colour absorbency and fastness 8. No batch to batch variation of shade (like exhaust dyeing)

28 SELECTION OF JET DYEING MACHINE NEW L-SHAPE AIR FLOW M/C

29 LONG TUBE DESIGN AIR FLOW

30 RECENT DEVELOPEMENTS ELECTROCHEMICAL DYEING TECHNOLOGY PLASMA TECHNOLOGY FOR DYEING SUPER CRITICAL CARBON DIOXIDE FULID TECNOLOGY

31 Particulate Control COMBUSTION & AIR POLLUTION Pulse Jet Fabric Filter (PJFF) Electrostatic Precipitators (ESPs) Upgrade/Enlarge ESP Add flue gas conditioning Wet ESP Wet Venturi Scrubber Electrified Filter Bed (EFB) Recyclone

32 Acid Gas Controls Dry Scrubber Spray Dry Absorber (SDA) Circulating Dry Scrubber (CDS) Wet Scrubber Direct Sorbent Injection (DSI) Wet ESP Wet Venturi Scrubber

33 CO/VOC Controls Oxidation Catalyst Regenerative oxidation catalyst SCR- to maintain NOx compliance Thermal Oxidizer Upgrade air system Install high energy burners

34 Resource Efficiency is not a question of latest technology but of Best Technique!