Metal heat-treat: flue-water buffer + HTHP flashes ~135°C steam
Anonymized heat-treat lines recover furnace flue heat to a ~70°C water buffer, then a high-temp heat pump produces ~140°C water for flash steam to bath heaters.
Engineering data
- Case type
- Anonymized field reference
- Data status
- anonymized_field_reference
- Industry
- Manufacturing
- Source temperature
- 65–75°C
- Sink temperature
- 135–140°C
- Temperature lift
- ≈ 60 K
- Heating or cooling duty
- Not disclosed
- Architecture
- Flue → water buffer → HTHP → flash steam, paralleled with legacy steam
- Result status
- Baths held near 90°C on flash steam; network steam opens only when HP steam is short
- Key risk
- Flue exchanger fouling; flash-steam stability; backup valve logic
- Existing system
- 4-bar network steam to wash / anneal / pickle / rinse baths (60–90°C)
- Refrigerant
- High-temperature HTHP fluid (site-specific)
- COP
- Illustrative value
- Annual savings
- Public note: legacy steam OPEX could exceed ¥3 M/y at full load before retrofit
- Estimated payback
- Cited in source; tariff-dependent
Project background
A metal-processing site ran four heat-treat lines whose baths needed 60–90°C holds. Network steam cost dominated OPEX, while furnace flue heat was available for recovery.
Source / inputs
Baths 60–90°C. Buffer ~70°C from flue. HP condenser water ~140°C flashing to ~135°C steam. Customer and city identifiers omitted.
Heat pump solution
Water recovers flue heat into a controlled buffer; a high-temp heat pump lifts that heat to ~140°C water; a flash vessel makes ~135°C steam tied into the steam header with a remote backup valve.
COP & savings
Source report focuses on architecture and steam displacement rather than a single COP number. Treat thermal ratings as site-design values.
Investment / ROI notes
Driven by steam tariff displacement on multi-line continuous duty; verify hours and steam price locally.