Textile dyeing: cascade WHR + heat pumps supply 50–70°C dye-bath water
Anonymized dyehouse recovers hot effluent and condensate in stages—direct exchange first, then waste-heat heat pumps—for 50°C and 70°C process water.
Engineering data
- Case type
- Anonymized field reference
- Data status
- anonymized_field_reference
- Industry
- Textile
- Source temperature
- 20–60°C
- Sink temperature
- 50–70°C
- Temperature lift
- ≈ -10 K
- Heating or cooling duty
- 4400 kW
- Architecture
- Multi-stage cascade: HEX + waste-heat source heat pumps
- Result status
- Steam use reduced by cascading high-grade heat before heat-pump lift
- Key risk
- Fouling on effluent exchangers; controls for seasonality
- Existing system
- Steam-heated dye jets; hot wastewater and condensate dumped to pits
- Refrigerant
- Site-specific WHR heat-pump fluids
- COP
- Illustrative value
- Annual savings
- Peak-season heat recovery on the order of several MW thermal (HEX + HP combined)
- Estimated payback
- Not disclosed in excerpt
Project background
A dyehouse heated jet-dye baths with network steam while discharging hot wastewater and condensate. The retrofit targets maximum heat recovery before effluent leaves near ambient.
Source / inputs
Targets: 70°C and 50°C process water. Public design notes: peak HEX ~0.58 MW plus heat-pump contribution multi-MW class; drain toward 20°C. Customer omitted.
Heat pump solution
High-grade effluent goes through direct heat exchangers first; mixed mid/low-grade streams feed waste-heat heat pumps for 70°C and 50°C loops, with final make-up preheat before discharge.
COP & savings
Published peak-season figures combine HEX and heat-pump thermal output in the multi-MW range; off-peak output scales down. COP not emphasized in the excerpt.
Investment / ROI notes
Value is steam displacement and lower process energy cost; payback depends on steam tariff and seasonality.