Fish meal dryer air heated by heat pumps
How a fish meal plant processing 20 tonnes of raw fish a day can heat its 90–110 °C finishing dryer air and cooker feed with heat pumps, and what it saves against a furnace-oil fired air 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
- Scorched protein. Direct-fired hot-air dryers put flue gas and hot spots into the meal, which lowers protein digestibility and the meal's grade.
- Very high fuel use. Fish meal drying is the largest energy user in the plant, and furnace oil prices move with crude.
- Odour complaints. Hot, smoky dryer exhaust adds to the odour problems that bring fish meal plants into conflict with neighbours.
- Losses between fuel and process. Burning furnace oil 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 cooks, presses and dries about 20 tonnes of raw oil sardine and trash fish a day into meal and fish oil. A steam disc dryer brings press cake down to about 30% moisture and a hot-air rotary dryer finishes it to 10%.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Hot-air finishing dryer | Air 100–105 °C | Meal 30% → 10%: 1,270 kg water × 0.72 kWh/kg ÷ 0.65 dryer efficiency | 1,407 |
| Raw fish preheating before cooker | 15 → 60 °C | 20,000 kg/day raw fish × 3.4 kJ/kg·K × 45 K | 850 |
| Storage and pipework standing losses | – | about 5% | 113 |
| Total useful heat | 2,370 | ||
Averaged over 20 running hours, the heat pumps need about 118 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
- A SE-UHT air-source cascade, R245fa machine of about 120 kW, air-source cascade to 120 °C, sized per project.
- A 4,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The furnace-oil fired hot-air generator stays connected behind a normally closed valve as standby.
- Hot water at 118 °C feeds a finned coil on the finishing dryer air inlet, giving clean air at up to 105 °C without flue gas.
- A jacketed screw preheater warms raw fish to 60 °C before the cooker, which cuts cooker steam.
- The steam disc dryer and cooker remain on the existing boiler for the high-temperature duties.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 120 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 118 °C |
| Storage | 4,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the tank top calls the heat pumps on below 112 °C and off at 118 °C. TT-102 at the bottom starts a unit early before the dryer starts. TIC-201 holds dryer inlet air at 100–105 °C and TIC-202 holds the raw fish preheater outlet at 60 °C. The oil-fired air heater stays as standby.
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 raw fish | – | – |
| CO₂ per year | – | – |
06Benefits
Higher-grade meal
Indirect hot air avoids flue gas contact and hot spots, which protects protein digestibility.
Less cooker steam
Preheated fish reaches cooking temperature faster with less boiler steam.
Cleaner exhaust
No combustion products in the dryer exhaust makes odour treatment easier.
Lower energy cost
Each kWh of electricity delivers about 1.6 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.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Raw fish throughput and season
- Press cake moisture and meal moisture targets
- Finishing dryer airflow and inlet temperature
- Present fuel use per tonne of meal
- 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
- Corrosive air. Dryer air carries fish oil mist and ammonia. Use stainless or coated coils, an upstream filter and a cleaning routine.
- Pressurised loop. Water at 118 °C needs about 3 bar to stay liquid. Size the pressurisation set and relief valve for this.
- Biosecurity. Keep raw and finished sides separate. The preheater sits on the raw side and must not share drains with the meal side.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
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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Fish meal dryer air heated by heat pumps
How a fish meal plant processing 20 tonnes of raw fish a day can heat its 90–110 °C finishing dryer air and cooker feed with heat pumps, and what it saves against a furnace-oil fired air 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
- Scorched protein. Direct-fired hot-air dryers put flue gas and hot spots into the meal, which lowers protein digestibility and the meal's grade.
- Very high fuel use. Fish meal drying is the largest energy user in the plant, and furnace oil prices move with crude.
- Odour complaints. Hot, smoky dryer exhaust adds to the odour problems that bring fish meal plants into conflict with neighbours.
- Losses between fuel and process. Burning furnace oil 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 cooks, presses and dries about 20 tonnes of raw oil sardine and trash fish a day into meal and fish oil. A steam disc dryer brings press cake down to about 30% moisture and a hot-air rotary dryer finishes it to 10%.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Hot-air finishing dryer | Air 100–105 °C | Meal 30% → 10%: 1,270 kg water × 0.72 kWh/kg ÷ 0.65 dryer efficiency | 1,407 |
| Raw fish preheating before cooker | 15 → 60 °C | 20,000 kg/day raw fish × 3.4 kJ/kg·K × 45 K | 850 |
| Storage and pipework standing losses | – | about 5% | 113 |
| Total useful heat | 2,370 | ||
Averaged over 20 running hours, the heat pumps need about 118 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
- A SE-UHT air-source cascade, R245fa machine of about 120 kW, air-source cascade to 120 °C, sized per project.
- A 4,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The furnace-oil fired hot-air generator stays connected behind a normally closed valve as standby.
- Hot water at 118 °C feeds a finned coil on the finishing dryer air inlet, giving clean air at up to 105 °C without flue gas.
- A jacketed screw preheater warms raw fish to 60 °C before the cooker, which cuts cooker steam.
- The steam disc dryer and cooker remain on the existing boiler for the high-temperature duties.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 120 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 118 °C |
| Storage | 4,000 L insulated tank |
Capacity is sized from the heat demand above. COP is an estimate until Sunniva engineering confirms the design.
Control philosophy
TT-101 at the tank top calls the heat pumps on below 112 °C and off at 118 °C. TT-102 at the bottom starts a unit early before the dryer starts. TIC-201 holds dryer inlet air at 100–105 °C and TIC-202 holds the raw fish preheater outlet at 60 °C. The oil-fired air heater stays as standby.
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 raw fish | – | – |
| CO₂ per year | – | – |
06Benefits
Higher-grade meal
Indirect hot air avoids flue gas contact and hot spots, which protects protein digestibility.
Less cooker steam
Preheated fish reaches cooking temperature faster with less boiler steam.
Cleaner exhaust
No combustion products in the dryer exhaust makes odour treatment easier.
Lower energy cost
Each kWh of electricity delivers about 1.6 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.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Raw fish throughput and season
- Press cake moisture and meal moisture targets
- Finishing dryer airflow and inlet temperature
- Present fuel use per tonne of meal
- 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
- Corrosive air. Dryer air carries fish oil mist and ammonia. Use stainless or coated coils, an upstream filter and a cleaning routine.
- Pressurised loop. Water at 118 °C needs about 3 bar to stay liquid. Size the pressurisation set and relief valve for this.
- Biosecurity. Keep raw and finished sides separate. The preheater sits on the raw side and must not share drains with the meal side.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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.
- Performance figure. The COP on this page is an engineering estimate, not a data sheet value. Sunniva engineering will confirm it for the actual source and supply temperatures.
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.