Contact Video Poster Gallery About WMC Home
SEARCH











Subscribe Quarterly News Letter for latest development & news. Just fill your E-mail Address :
send your artciles



CASE STUDIES- 1

CLEANER PRODUCTION CASE STUDY TEXTILE PROCESSING

1. INTODUCTION

2. PROCESS DESCRIPTION
- Fabric Purification:
- Dyeing:
- Printing:
- Finishing:

3. STUDY FOCUS AREAS


4. CP OPPORTUNITIES THAT REDUCED ENVRIONMENTAL LOAD AND ACCRUED ECONOMIC BENEFITS:





1. INTRODUCTION

M/s. Tirupur Arora is a Textile Processing Pvt. Ltd. company located in Tirupur. The unit engaged in the processing of cotton hosiery, with a processing capacity of about 2500 tons per annum (including printing- 80% and dyeing-20%). This case study outlines the results of the Cleaner production study.


2. PROCESS DESCRIPTION
The main operations carried out in the unit include:

- Fabric pre-treatment
The fabric purification is carried out in the modern softflow machines as well as conventional winches. Fabric purification is done mainly to remove the oily substances, nitrogenous compounds, waxes and proteins and natural coloring material from the fabric by treating it with hot alkaline liquors containing other required chemicals like wetting agent, defoamer, detergent, stabiliser etc.

Initially machine is filled with required quantity of water after which fabric is loaded. After loading scouring chemicals (water softener, wetting agent, defoamer, NaOH) are added at ambient temperature. The temperature of the liquor is raised by addition of indirect steam. When the temperature reaches 50oC bleaching chemicals (Hydrogen peroxide and brightening agent) are added. The temperature is then raised to 96oC and maintained for 40 minutes at the same temperature followed by indirect cooling to 80oC by fresh water. The spent bleach liquor is discharged alongwith a fresh water rinse. The fabric is then subjected to 2 hot water washes. Resulting wash water is drained out. In order to remove residual alkalinity the fabric is given acid (acetic acid) treatment in cold conditions. The spent acid liquor is drained out.
As of now slitted fabrics are not being used, hence, the dried fabric is re-rolled and printed on the reverse side of the tubular fabric.
Dyeing:

After fabric purification, dyeing is carried out in the same machine. Machine is filled with fresh water. Initially, common salt, anti creasing agent and de-foamer are added. The temperature of the solution is raised to 50oC. Concentrated dyestuff solution is prepared separately and is added to the liquor over a period of 20 minutes. After Dyes addition, the temperature is raised to 95oC and is maintained at that temperature for 20 minutes, followed by indirect cooling to 80oC. At this temperature Soda ash (Dye fixing agent) is added, over a period of 20 minutes. After Soda addition the fabric is kept in motion inside the liquor for 45 minutes at the same temperature. Spent Dye liquor is discharged to the drain. In order to remove residual alkali and the dye stuff, the fabric is subjected to four washes in series, First and third with hot water, second with hot soap solution and final one with acid in ambient condition. Hot water wash is carried out at 70oC for 10 minutes duration while soap wash at 95oC and 15 minutes duration. Wash water from each of these stages is drained out.

After whitening/dyeing the fabric is unload from the machine and is first taken to the Hydro extractor where it is evenly wetted by means of stretching, ballooning by compressed air (and dipping in water containing finishing chemicals in case of final finishing) followed by squeezing between the rollers. The squeezed fabric is then dried in a relax drier. The fabric is then given the uniform width and compacted in layered form in calendaring machine. After calendaring the fabric goes to the roller section in which the compacted layers are put in a roll form. Next it goes to printing or despatch (in case printing is not needed).

Printing:

The fabric after bleaching/dyeing is taken for printing. The rotary screen printing machine used in the unit has provision for printing 8 colors simultaneously. The color print paste prepared is fed into the screens from which it is transferred to the fabric fed in. The fabric after print paste transfer is passed through a drying chamber at 145oC. The dried and printed fabric is taken for further processing.
As of now slitted fabrics are not being used, hence, the dried fabric is re-rolled and printed on the reverse side of the tubular fabric.

Finishing:

After printing the fabric is subjected to the finishing treatments. The fabric is padded with water containing finishing chemicals followed by squeezing between the rollers. The squeezed fabric is then dried in a relax drier. The fabric is then given the uniform width and compacted in layered form in calendaring machine. After calendaring the fabric goes to the roller section in which the compacted layers are put in a roll form. Next it goes for despatch.

3. STUDY FOCUS AREAS

The unit has focussed on ways to reduce its pollutant load by optimising chemical consumption and substituting chemicals which generated lower load. The study outlines the results of the study.

4. CP OPPORTUNITIES THAT REDUCED ENVRIONMENTAL LOAD AND ACCRUED ECONOMIC BENEFITS:

The assessment study evaluated combustion efficiency by monitoring excess oxygen and analysing input and waste outputs and to evaluate resource loss and conducted literature surveys to identify alternate chemicals . Based on the study CP options were evaluated and the most significant CP opportunities that are implemented are as follows:

1. Reducing the quantity of acid from 1.5 to 1.2 Kg for soft flow and from 2.0 to 1.5 Kg for winch machine. The benefits of this option are :
Reduction in acid consumption = 13 tons/annum Savings due to reduced acid consumption =Rs 5,50,000/ per annum ( CH3COOH@ Rs 42/kg)

2. Reduction in use of salt dyeing by 15% has resulted in cost reduction, along with the reduction in pollution load to the environment.
Reduction in salt consumption = 70 tons/annum Savings due to reduced salt consumption= Rs 2,10,000/ lakhs/annum ( Salt @ Rs 3/Kg

3. Second hot wash water is used in the first hot wash of another machine and the results are Reduction in water consumption = 2500m3/annum Savings due to reduction in water consumption = Rs 75,000/ per annum (Water @ Rs 30/ m3)

4. Using last rinse (after dyeing) for scouring liquor preparation has led to reduction in water consumption as well as the corresponding waste water treatment cost. The option has led to a monetary saving of Rs.0.14 million

5. Avoidance/reduction of bleaching agent for those fabric going for darker shades
Apart from the above, a number of simple housekeeping & equipment modification measures have been identified during the study, which are listed below:
-Providing 5 minutes drag out time after every discharge
-Reuse of waste water from washing steps (before dyeing) for blanket wash
- Preparation of preventive maintenance schedule and maintain accordingly
- Recover the print paste by simple piston like device prior to washing
- Modification of fuel firing practices in boilers to optimise combustion and thus reducing in fuel consumption
The overall results achieved of the study are given in the following table.
S No Parameter Before CP(per annum) After CP(per annum % change
Acid consumption 57.5 tons 49 tons -15
Salt consumption 440 tons 370 tons -16
Water use 1,88,180 m3 1,85,600 m3 -2


News Letters| Case Exercises| Technical Case Studies| Achievements| Training| WMC Facilitators
FAQs| Govt. Statement Policies| Presentation-Slides| Information Sources
Home| About WMC| Poster Gallery| Video| Contact |Query/Feedback

Site is best viewable in 800 X 600 resolution