Soy milk cooked with heat pump hot water
How a plant making 5,000 litres of soy milk a day for drinks and tofu can cook it with pressurised heat pump hot water instead of a diesel-fired boiler.
▶Video: Process hot water for food, dairy and beverages
V02 · 2–2.5 minPasteurisers, CIP, cooking and washing on stored hot water instead of boiler steam
Video coming soon01Problem statement
- Direct steam dilutes the milk. Steam injected into the cooker adds condensate, which changes solids content from batch to batch.
- Foaming and scorching. Soy slurry foams hard when boiled. Hot spots from steam coils scorch it and give a burnt taste.
- Hot grinding water. Grinding with water at about 80 °C reduces beany flavour, but it is another steam user.
- 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 grinds about 700 kg of soybeans a day with hot water to make 5,000 litres of soy slurry. The slurry is cooked at 98 °C, filtered, and used for bottled soy milk and about 1.2 tonnes of tofu. Presses, cloths and moulds are washed daily.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Hot grinding water | 30 → 80 °C | 3,600 L/day | 209 |
| Soy slurry cooking | 70 → 98 °C | 5,000 L/day, 10% cooker losses | 172 |
| Cloth, mould and CIP washing | 70 °C | 3,000 L/day, 30 → 70 °C | 139 |
| Storage and pipework standing losses | – | about 5% | 26 |
| Total useful heat | 547 | ||
Averaged over 14 running hours, the heat pumps need about 39 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 40 kW, air-source cascade to 120 °C, sized per project.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired steam boiler stays connected behind a normally closed valve as standby.
- Pressurised hot water at about 110 °C heats the cooker through its jacket or a tubular heater, so no steam enters the soy milk.
- Grinding water and wash water are heated from the same tank through plate exchangers.
- The cooker holds 98 °C for the set time using a jacket flow valve.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 40 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.7 (estimate) |
| Supply temperature | 110 °C |
| Storage | 1,500 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 starts the heat pumps below 104 °C and stops them at 110 °C. TIC-201 heats the cooker to 98 °C and then holds it for the set time. TIC-202 and TIC-203 hold grinding water at 80 °C and wash water at 70 °C. If the tank falls below 100 °C, the standby steam valve on the cooker opens.
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 1,000 L soy milk | – | – |
| CO₂ per year | – | – |
06Benefits
Consistent solids
No condensate is added, so soy milk solids and tofu yield are more consistent.
Less scorching
A moderate jacket temperature reduces burnt flavour and fouling.
Simple plant
Grinding, cooking and washing run from one hot-water loop.
Lower energy cost
Each kWh of electricity delivers about 1.7 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.
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
- Soybean use and soy milk volume per day
- Cooker type, size and cook time
- Grinding water temperature and volume
- Tofu output and whey volume
- Washing water use
- 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
- Foam control. Leave head space in the cooker and keep the heating rate moderate.
- Hot whey. Tofu whey drains at 60–70 °C. It can preheat grinding water through a small exchanger.
- Pressurised loop. Hold the hot-water loop above about 1.5 bar(g) at 110 °C.
- 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.
Talk to us
Soy milk cooked with heat pump hot water
How a plant making 5,000 litres of soy milk a day for drinks and tofu can cook it with pressurised heat pump hot water instead of a diesel-fired boiler.
▶Video: Process hot water for food, dairy and beverages
V02 · 2–2.5 minPasteurisers, CIP, cooking and washing on stored hot water instead of boiler steam
Video coming soon01Problem statement
- Direct steam dilutes the milk. Steam injected into the cooker adds condensate, which changes solids content from batch to batch.
- Foaming and scorching. Soy slurry foams hard when boiled. Hot spots from steam coils scorch it and give a burnt taste.
- Hot grinding water. Grinding with water at about 80 °C reduces beany flavour, but it is another steam user.
- 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 grinds about 700 kg of soybeans a day with hot water to make 5,000 litres of soy slurry. The slurry is cooked at 98 °C, filtered, and used for bottled soy milk and about 1.2 tonnes of tofu. Presses, cloths and moulds are washed daily.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Hot grinding water | 30 → 80 °C | 3,600 L/day | 209 |
| Soy slurry cooking | 70 → 98 °C | 5,000 L/day, 10% cooker losses | 172 |
| Cloth, mould and CIP washing | 70 °C | 3,000 L/day, 30 → 70 °C | 139 |
| Storage and pipework standing losses | – | about 5% | 26 |
| Total useful heat | 547 | ||
Averaged over 14 running hours, the heat pumps need about 39 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 40 kW, air-source cascade to 120 °C, sized per project.
- A 1,500 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired steam boiler stays connected behind a normally closed valve as standby.
- Pressurised hot water at about 110 °C heats the cooker through its jacket or a tubular heater, so no steam enters the soy milk.
- Grinding water and wash water are heated from the same tank through plate exchangers.
- The cooker holds 98 °C for the set time using a jacket flow valve.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 40 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.7 (estimate) |
| Supply temperature | 110 °C |
| Storage | 1,500 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 starts the heat pumps below 104 °C and stops them at 110 °C. TIC-201 heats the cooker to 98 °C and then holds it for the set time. TIC-202 and TIC-203 hold grinding water at 80 °C and wash water at 70 °C. If the tank falls below 100 °C, the standby steam valve on the cooker opens.
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 1,000 L soy milk | – | – |
| CO₂ per year | – | – |
06Benefits
Consistent solids
No condensate is added, so soy milk solids and tofu yield are more consistent.
Less scorching
A moderate jacket temperature reduces burnt flavour and fouling.
Simple plant
Grinding, cooking and washing run from one hot-water loop.
Lower energy cost
Each kWh of electricity delivers about 1.7 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.
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
- Soybean use and soy milk volume per day
- Cooker type, size and cook time
- Grinding water temperature and volume
- Tofu output and whey volume
- Washing water use
- 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
- Foam control. Leave head space in the cooker and keep the heating rate moderate.
- Hot whey. Tofu whey drains at 60–70 °C. It can preheat grinding water through a small exchanger.
- Pressurised loop. Hold the hot-water loop above about 1.5 bar(g) at 110 °C.
- 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.