Ink dryers and boiler feed heated by heat pumps
How a packaging plant running a rotogravure press, a flexo press and a corrugator can heat its ink-drying air and boiler feedwater with heat pumps, and what it saves against a diesel-fired thermic fluid heater.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Thermic fluid for low-temperature drying. Ink dryers need air at only 50–70 °C, but are heated by thermic fluid at 200 °C or more from a diesel heater.
- Large fresh-air volumes. Solvent safety requires a high fresh-air rate in dryers, so a lot of air must be heated from ambient.
- Cold feedwater to the corrugator boiler. Poor condensate return means the corrugator boiler is fed with cold make-up water, wasting fuel.
- Losses between fuel and process. Burning diesel 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 plant prints flexible packaging on an 8-colour rotogravure press and a flexo press, and makes corrugated boxes on a 5-ply corrugator. It runs two shifts, with a small steam boiler serving the corrugator.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Gravure press dryers | Air 35 → 70 °C | 8,000 m³/h fresh air × 1.15 kg/m³ × 1.005 kJ/kg·K × 35 K × 16 h | 1,438 |
| Flexo press dryer | Air 35 → 65 °C | 3,000 m³/h × 1.15 kg/m³ × 1.005 kJ/kg·K × 30 K × 16 h | 462 |
| Corrugator boiler make-up preheat | 30 → 80 °C | 12,000 L/day, 30 → 80 °C | 697 |
| Starch kitchen water | 30 → 40 °C | 6,000 L/day, 30 → 40 °C | 70 |
| Storage and pipework standing losses | – | about 5% | 133 |
| Total useful heat | 2,800 | ||
Averaged over 18 running hours, the heat pumps need about 156 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
- 2 × SE-SHT-110C (220 kW total) (SE-SHT cascade heat pump) delivering 85 °C, covering the day's 2,800 kWh in about 12.7 running hours.
- A 7,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired thermic fluid heater stays connected behind a normally closed valve as standby.
- Hot-water coils on the fresh-air intake of each press dryer heat air to 65–70 °C, ahead of the existing thermic fluid coils.
- A plate exchanger preheats corrugator boiler make-up water to 80 °C, and the same loop warms the starch kitchen water.
- Thermic fluid coils stay in series and trim only on jobs that need hotter air.
Selected equipment
| Model | SE-SHT-110C × 2 |
|---|---|
| Heating capacity | 110 kW each, 220 kW total |
| COP | 2.7 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 81.0 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 85 °C |
| Storage | 7,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pumps below 80 °C and stops them at 85 °C. TIC-201 and TIC-202 hold dryer air at set point and the thermic fluid valves trim only if the water coils fall short. TIC-203 holds boiler feed at 80 °C. Dryer coil valves close when the press stops.
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 | – | – |
| CO₂ per year | – | – |
06Benefits
Thermic heater mostly idle
Most drying jobs run on hot water alone, so the diesel heater runs far less.
Gentler drying
Steady air temperature helps avoid film distortion and blocking on heat-sensitive substrates.
Better boiler efficiency
Preheated feedwater cuts corrugator boiler fuel and helps deaeration.
Lower energy cost
Each kWh of electricity delivers about 2.7 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
- Dryer airflows and set temperatures for each press
- Corrugator boiler rating and condensate return
- Starch kitchen water use
- Monthly diesel use for the thermic fluid heater
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Solvent safety. Keep water coils in the fresh-air duct, outside classified zones, and keep the dryer LEL monitoring and exhaust rates unchanged.
- Feed pump NPSH. Hotter feedwater reduces available NPSH. Check the boiler feed pump before raising feed temperature to 80 °C.
- Electrical. About 81 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. The SE-SHT cascade gives about 80% of rated output at 7 °C ambient and still runs at −20 °C. Size on the coldest design day for northern sites.
- 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.
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Ink dryers and boiler feed heated by heat pumps
How a packaging plant running a rotogravure press, a flexo press and a corrugator can heat its ink-drying air and boiler feedwater with heat pumps, and what it saves against a diesel-fired thermic fluid heater.
▶Video: Hot air from heat pump hot water
V05 · 2–2.5 minAir coils for spray dryers, stenters, kilns, paint booths and ovens
Video coming soon01Problem statement
- Thermic fluid for low-temperature drying. Ink dryers need air at only 50–70 °C, but are heated by thermic fluid at 200 °C or more from a diesel heater.
- Large fresh-air volumes. Solvent safety requires a high fresh-air rate in dryers, so a lot of air must be heated from ambient.
- Cold feedwater to the corrugator boiler. Poor condensate return means the corrugator boiler is fed with cold make-up water, wasting fuel.
- Losses between fuel and process. Burning diesel 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 plant prints flexible packaging on an 8-colour rotogravure press and a flexo press, and makes corrugated boxes on a 5-ply corrugator. It runs two shifts, with a small steam boiler serving the corrugator.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Gravure press dryers | Air 35 → 70 °C | 8,000 m³/h fresh air × 1.15 kg/m³ × 1.005 kJ/kg·K × 35 K × 16 h | 1,438 |
| Flexo press dryer | Air 35 → 65 °C | 3,000 m³/h × 1.15 kg/m³ × 1.005 kJ/kg·K × 30 K × 16 h | 462 |
| Corrugator boiler make-up preheat | 30 → 80 °C | 12,000 L/day, 30 → 80 °C | 697 |
| Starch kitchen water | 30 → 40 °C | 6,000 L/day, 30 → 40 °C | 70 |
| Storage and pipework standing losses | – | about 5% | 133 |
| Total useful heat | 2,800 | ||
Averaged over 18 running hours, the heat pumps need about 156 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
- 2 × SE-SHT-110C (220 kW total) (SE-SHT cascade heat pump) delivering 85 °C, covering the day's 2,800 kWh in about 12.7 running hours.
- A 7,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired thermic fluid heater stays connected behind a normally closed valve as standby.
- Hot-water coils on the fresh-air intake of each press dryer heat air to 65–70 °C, ahead of the existing thermic fluid coils.
- A plate exchanger preheats corrugator boiler make-up water to 80 °C, and the same loop warms the starch kitchen water.
- Thermic fluid coils stay in series and trim only on jobs that need hotter air.
Selected equipment
| Model | SE-SHT-110C × 2 |
|---|---|
| Heating capacity | 110 kW each, 220 kW total |
| COP | 2.7 at A20 °C / W90 °C (data sheet T1) |
| Power input | about 81.0 kW total at rated conditions |
| Rating | cascade R410A + R515B, rated 90 °C, 95 °C maximum |
| Supply temperature | 85 °C |
| Storage | 7,000 L insulated tank |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TT-101 at the tank top starts the heat pumps below 80 °C and stops them at 85 °C. TIC-201 and TIC-202 hold dryer air at set point and the thermic fluid valves trim only if the water coils fall short. TIC-203 holds boiler feed at 80 °C. Dryer coil valves close when the press stops.
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 | – | – |
| CO₂ per year | – | – |
06Benefits
Thermic heater mostly idle
Most drying jobs run on hot water alone, so the diesel heater runs far less.
Gentler drying
Steady air temperature helps avoid film distortion and blocking on heat-sensitive substrates.
Better boiler efficiency
Preheated feedwater cuts corrugator boiler fuel and helps deaeration.
Lower energy cost
Each kWh of electricity delivers about 2.7 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
- Dryer airflows and set temperatures for each press
- Corrugator boiler rating and condensate return
- Starch kitchen water use
- Monthly diesel use for the thermic fluid heater
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Solvent safety. Keep water coils in the fresh-air duct, outside classified zones, and keep the dryer LEL monitoring and exhaust rates unchanged.
- Feed pump NPSH. Hotter feedwater reduces available NPSH. Check the boiler feed pump before raising feed temperature to 80 °C.
- Electrical. About 81 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
- Winter output. The SE-SHT cascade gives about 80% of rated output at 7 °C ambient and still runs at −20 °C. Size on the coldest design day for northern sites.
- 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.