Reuse of water from cooling drums

 

Technical description

 

At most of the continuous woven fabric machines of the textile finishing industries, wet fabric is first dried at drum dryers and then cooled through cooling drums so that it could be handled easily. Figure 1 and Figure 2 show a drum dryer where the last drum is cooled with fresh water for reducing the fabric temperature. These cooling drums are provided with fresh water circulation inside. After getting heat of the hot fabric, this warm water is discharged as wastewater. This is a clean and warm water stream.

Figure 1: Drum dryer where the last drum is cooled with fresh water to reduce the temperature of the fabric

Generally cooling drums are attached with the following:

  • Continuous pretreatment machines
  • Mercerization machines
  • Curing machines
  • Pad steam dyeing machines
  • Pad steam dyeing machines attached with Thermosole
  • Stenters
  • Pad dryers

This clean warm water can be collected in a storage tank and reused in the process. In some industries, this cooling water is not a raw water but a treated water (soft water or RO treated water) which is of a very good quality and very expensive.

Figure 2: Cooling drums attached with pad steam dyeing machine

Achieved environmental benefits

  • Water conservation
  • Reduction in thermal energy (warm water will require less steam for heating, in case if this water is used at hot washes)
  • Reduction in greenhouse gases 
  • Reduction in hydraulic load of wastewater treatment plant

 Operational data

Cooling water quantity varies from industry to industry. Its quantity can be up to 482 m3/day or 168,700 m3/yr (large textile industry). The cost of this water is USD 56,000/yr (Rs. 8.4 million/yr).

The implementation cost would be USD 23,330 (Rs. 3.5 million) for underground water collection tank of 20 m3 capacity, piping and pumps. 

Cross media effects

No relevant cross media effect is known.

Technical considerations relevant to applicability

This measure is applicable to all the woven fabric processing industries where hot fabric is cooled at cooling drums after drying. This measure does not require any major intervention in the process, no major infrastructure development and no technical human resource requirement. The cooling water from the cooling drums will be collected in an underground storage tank (preferably underground tank but over ground tank can also be used by constructing a small holding pit and pump).

Note: the cooling water supply in the cooling drums should be synchronized with the operation of the machines. The cooling water supply should be stopped when machine is stopped to avoid its unnecessary wastage in case of machine stoppage. In most of the cases, cooling water keeps on running and wasted even the machine is stopped due to various reasons (maintenance, change over etc.).

Economics

Capital cost = USD 23,330 (Rs. 3.5 million)

Annual saving = USD 56,000 (Rs. 8.4 million)

Annual O&M cost = USD 3,330 (Rs. 500,000)

Simple payback period = 5 months

Additional benefit will be the reduction in hydraulic load and treatment cost of wastewater treatment plant

Driving force for implementation

  • Financial benefits
  • Resource conservation
  • Sustainability of textile business

Reference industry

This measure is relevant for all the woven fabric processing industries where cooling drums are used to cool the fabric.


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