HT jet dyeing preheated with recovered heat
How a polyester dye-house processing 2,000 kg a day can preheat its HT jet machines to 95–110 °C with heat pumps running on jet cooling water, against a PNG-fired boiler.
▶Video: Heat pumps for textile and leather processing
V03 · 2–2.5 minDyeing, pre-treatment and tanning, with heat recovered from hot drain water
Video coming soon01Problem statement
- Heating and cooling every cycle. Each HT cycle heats the liquor to dyeing temperature and then cools it through the machine cooler, throwing away the heat into cooling water.
- Long cycle times. Heating from cold fill water takes up a large share of the cycle and limits machine output.
- High steam demand peaks. Several jets heating at once create peaks that the boiler struggles to meet, which drags out heating gradients.
- Losses between fuel and process. Burning PNG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit dyes 2,000 kg of polyester and blended fabric a day on high-temperature jet machines, with reduction clearing after dyeing. It runs three shifts.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| HT jet dyeing, preheat stage | 30 → 110 °C | 2,000 kg fabric × 1:6 liquor = 12,000 L/day | 1,115 |
| Reduction clearing | 80 °C | 12,000 L/day, 30 → 80 °C | 697 |
| Storage and pipework standing losses | – | about 5% | 91 |
| Total useful heat | 1,902 | ||
Averaged over 20 running hours, the heat pumps need about 95 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 4 × SE-WWUHT-27 (108 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,902 kWh in about 17.6 running hours.
- A 3,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: HT jet cooling-water return and hot drain at about 60 °C. Cooler return water speeds up the jet cooling phase and lightens the cooling tower load.
- The PNG-fired steam boiler stays connected behind a normally closed valve as standby.
- Warm water from the jet coolers and hot drops at about 60 °C is collected in an insulated buffer tank and used as the heat pump source.
- The heat pumps charge a pressurised tank at up to 120 °C, which brings each jet to 110 °C through its own exchanger.
- The final stage above 120 °C and the dyeing hold stay on the existing steam supply.
Selected equipment
| Model | SE-WWUHT-27 × 4 |
|---|---|
| Heating capacity | 27 kW each, 108 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 36.8 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Storage | 3,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 112 °C and stops them at 120 °C. TIC-201 on each jet follows its programmed gradient on hot water up to the changeover point, then hands over to the steam valve. The boiler remains standby for the full duty.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| Cost per tonne of fabric | – | – |
| CO₂ per year | – | – |
06Benefits
Cooling heat reused
Heat removed in the cooling phase becomes the source for heating the next batch.
Shorter cycles
Fast preheating from stored hot water cuts heat-up time on each batch.
Smaller steam peaks
The boiler supplies only the last stage, so simultaneous heat-ups no longer overload it.
Lower energy cost
Each kWh of electricity delivers about 2.9 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Number and capacity of HT jets
- Dyeing programmes and liquor ratio
- Cooling-water flow and temperature during cooling phases
- Steam or PNG use per day
- Present cycle times
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Pressure rating. Water at 110 to 120 °C needs a pressurised loop. Check the design pressure of each jet exchanger and fit relief valves on the secondary loop.
- Oligomers and fouling. Polyester liquors deposit oligomers on hot surfaces. Keep the recovery exchanger on clean cooling water where possible, and make it easy to open.
- Source balance. Cooling-water return is available only during cooling phases. Size the buffer tank so the heat pumps have source water across the whole cycle.
- Electrical. About 37 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
Talk to us
HT jet dyeing preheated with recovered heat
How a polyester dye-house processing 2,000 kg a day can preheat its HT jet machines to 95–110 °C with heat pumps running on jet cooling water, against a PNG-fired boiler.
▶Video: Heat pumps for textile and leather processing
V03 · 2–2.5 minDyeing, pre-treatment and tanning, with heat recovered from hot drain water
Video coming soon01Problem statement
- Heating and cooling every cycle. Each HT cycle heats the liquor to dyeing temperature and then cools it through the machine cooler, throwing away the heat into cooling water.
- Long cycle times. Heating from cold fill water takes up a large share of the cycle and limits machine output.
- High steam demand peaks. Several jets heating at once create peaks that the boiler struggles to meet, which drags out heating gradients.
- Losses between fuel and process. Burning PNG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference unit dyes 2,000 kg of polyester and blended fabric a day on high-temperature jet machines, with reduction clearing after dyeing. It runs three shifts.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| HT jet dyeing, preheat stage | 30 → 110 °C | 2,000 kg fabric × 1:6 liquor = 12,000 L/day | 1,115 |
| Reduction clearing | 80 °C | 12,000 L/day, 30 → 80 °C | 697 |
| Storage and pipework standing losses | – | about 5% | 91 |
| Total useful heat | 1,902 | ||
Averaged over 20 running hours, the heat pumps need about 95 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 4 × SE-WWUHT-27 (108 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,902 kWh in about 17.6 running hours.
- A 3,500 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: HT jet cooling-water return and hot drain at about 60 °C. Cooler return water speeds up the jet cooling phase and lightens the cooling tower load.
- The PNG-fired steam boiler stays connected behind a normally closed valve as standby.
- Warm water from the jet coolers and hot drops at about 60 °C is collected in an insulated buffer tank and used as the heat pump source.
- The heat pumps charge a pressurised tank at up to 120 °C, which brings each jet to 110 °C through its own exchanger.
- The final stage above 120 °C and the dyeing hold stay on the existing steam supply.
Selected equipment
| Model | SE-WWUHT-27 × 4 |
|---|---|
| Heating capacity | 27 kW each, 108 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 36.8 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Storage | 3,500 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 starts the heat pumps below 112 °C and stops them at 120 °C. TIC-201 on each jet follows its programmed gradient on hot water up to the changeover point, then hands over to the steam valve. The boiler remains standby for the full duty.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| Cost per tonne of fabric | – | – |
| CO₂ per year | – | – |
06Benefits
Cooling heat reused
Heat removed in the cooling phase becomes the source for heating the next batch.
Shorter cycles
Fast preheating from stored hot water cuts heat-up time on each batch.
Smaller steam peaks
The boiler supplies only the last stage, so simultaneous heat-ups no longer overload it.
Lower energy cost
Each kWh of electricity delivers about 2.9 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Built-in redundancy
Several machines share the load. If one is serviced, the others and the storage carry most of the day, with the existing heater in reserve.
07Engineering pointers
Site data to collect
- Number and capacity of HT jets
- Dyeing programmes and liquor ratio
- Cooling-water flow and temperature during cooling phases
- Steam or PNG use per day
- Present cycle times
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
Design notes
- Pressure rating. Water at 110 to 120 °C needs a pressurised loop. Check the design pressure of each jet exchanger and fit relief valves on the secondary loop.
- Oligomers and fouling. Polyester liquors deposit oligomers on hot surfaces. Keep the recovery exchanger on clean cooling water where possible, and make it easy to open.
- Source balance. Cooling-water return is available only during cooling phases. Size the buffer tank so the heat pumps have source water across the whole cycle.
- Electrical. About 37 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Source stream. The source must give up roughly two-thirds of the heat delivered. Confirm its flow and temperature over a full production day, and filter it before the evaporator.
- Water quality. Scale forms quickly above 60 °C. Use softened make-up and keep the heat pump loop closed, with process fluids on the far side of an exchanger or coil.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.