Reuse of cooling water from different sources

 

Technical description

 

There are many equipment in the textile finishing industries where cooling water is applied. The purpose of supplying cooling water to this equipment is to keep them cool, to minimize undesired reactions (e.g. of reactive dyestuffs), or to prevent damage to their moving and rotating parts. This cooling water is not in direct contact with any media and remains uncontaminated. Only its temperature is increased. Generally, this warm water stream is ultimately discharged as wastewater. Cooling water is used at the following locations/machines:

  • Coal based boiler induced fan
  • Coal feeding gate of steam boilers
  • Coal feeding gate of thermal oil heaters
  • Thermosol padder’s hydraulic pump
  • Thermal oil pumps at thermal oil heaters (see Figure 1 as an example)    
  • Ager thermal oil pump
  • Calendar cooling water
  • Comfort cooling water
  • Gas-based thermal oil pump cooling water
  • Padders of continuous dyeing machines
  • Cooling for the water of high-temperature exhaust dyeing machines (loose material, yarn, knitwear, or woven fabric made of polyester or polyester blends) – see technique-8

The non-contaminated water can be collected and reused in the process wherever convenient for the industry.

Achieved environmental benefits:

  • Water conservation
  • Reduction in thermal energy
  • Reduction in a hydraulic load of the wastewater treatment plant

Operational data:

The quantity of cooling water varies from industry to industry, depending upon the number of sources where cooling water is applied. Its quantity can be in the range of 100 to 160 m3/day (32,300 – 51,680 m3/year). The value of this warm water is about USD 12,933 to 21,000/year (Rs. 1.94 to 3.15 million/year).

The implementation cost will vary from industry to industry, depending upon its quantity and point of use. The implementation cost will be USD 4,000 to 8,000 (Rs. 0.6 to 1.2 million) for storage tanks, pipes, valves, and pumps.

Cross-media effects:

No relevant cross-media effect is known.

Technical considerations relevant to applicability:

This measure is applicable to all types of textile finishing industries where cooling water is applied in different equipment. This measure does not require any intervention in the process, no major infrastructure development, and no technical human resource requirement. The cooling water will be collected in the storage tank and pumped to the process wherever required.

Economics:

Capital cost = USD 4,000 to 8,000 (Rs. 0.6 to 1.2 million)

Annual saving = USD 12,933 to 21,000 (Rs. 1.94 to 3.15 million)

Annual O&M cost = USD 2,000 to 3,330 (Rs. 300,000 to 500,000)

Simple payback period = 4 to 5 months

An additional benefit will be the reduction in hydraulic load and treatment cost of the wastewater treatment plant.

Driving force for implementation:

  • Financial benefits
  • Resource conservation
  • Sustainability of textile business

Reference industry:

All textile finishing industries


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