Starch liquefaction steam from flash-cooling heat
How a plant liquefying 10 tonnes of dry starch a day can make its jet-cooker steam with a heat pump fed from liquefact cooling water, instead of a furnace-oil boiler.
▶Video: Low-pressure steam from waste heat
V07 · 2–2.5 minWater-source R245fa heat pumps making 2 bar steam up to 120 °C
Video coming soon01Problem statement
- Heated and then cooled. The liquefact is cooled from about 95 °C to 60 °C for saccharification, and that heat goes to a cooling tower.
- Steady steam demand. The jet cooker draws steam continuously, so the boiler runs all day for one duty.
- Temperature control matters. Liquefaction below 95 °C leaves gelatinised starch that filters badly. Steam swings cause this.
- 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 converts about 10 tonnes of dry maize starch a day into glucose syrup. Starch slurry at 35% solids is preheated, jet-cooked to about 105 °C, held in liquefaction columns at 95–100 °C, then cooled to 60 °C for saccharification. It runs round the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Jet cooking | Slurry 60 → 105 °C | 28.6 t/day slurry (24,900 L at 1.15 kg/L), 35% solids | 1,217 |
| Liquefaction column hold | 95–100 °C | 3 columns × 3 kW losses × 20 h | 180 |
| Storage and pipework standing losses | – | about 5% | 70 |
| Total useful heat | 1,467 | ||
Averaged over 20 running hours, the heat pumps need about 73 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
- 3 × SE-WWUHT-27 (81 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,467 kWh in about 18.1 running hours.
- Heat source: liquefact cooling water at about 55 °C. Cooling the liquefact through the heat pump lowers cooling tower load.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water from the liquefact cooler, at about 55 °C, is the heat pump source.
- The heat pump makes 2 bar steam for the jet cooker and column tracing.
- Slurry preheating with flash vapour or a regenerative exchanger stays as it is, so the heat pump covers the final lift.
Selected equipment
| Model | SE-WWUHT-27 × 3 |
|---|---|
| Heating capacity | 27 kW each, 81 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 27.6 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Steam | 40 kg/h at 2 bar per SE-WWUHT-27 module |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
PT-101 on the low-pressure steam header controls heat pump capacity to hold 2 bar. TIC-201 holds jet cooker outlet at 105 °C. TIC-202 holds the columns at 95–100 °C. If header pressure falls below 1.6 bar, the boiler steam valve opens 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 dry starch | – | – |
| CO₂ per year | – | – |
06Benefits
Cooling heat reused
Heat removed before saccharification makes steam for the next batch of slurry.
Less cooling tower load
Cooling the liquefact through the heat pump reduces tower duty.
Steady liquefaction
A dedicated steam supply helps hold jet cooker temperature.
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
- Dry starch processed per day and slurry solids
- Jet cooker type and steam pressure
- Slurry temperature before the jet cooker
- Liquefact cooler flow and temperatures
- Current steam 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
Design notes
- Jet cooker pressure. Many jet cookers need steam well above 2 bar. Check the cooker, or use a low-pressure jet heater design.
- Feed water. Use softened and deaerated feed water for the heat pump steam generator.
- Enzyme dosing. Keep enzyme dosing linked to the jet cooker temperature as today.
- Electrical. About 28 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
Starch liquefaction steam from flash-cooling heat
How a plant liquefying 10 tonnes of dry starch a day can make its jet-cooker steam with a heat pump fed from liquefact cooling water, instead of a furnace-oil boiler.
▶Video: Low-pressure steam from waste heat
V07 · 2–2.5 minWater-source R245fa heat pumps making 2 bar steam up to 120 °C
Video coming soon01Problem statement
- Heated and then cooled. The liquefact is cooled from about 95 °C to 60 °C for saccharification, and that heat goes to a cooling tower.
- Steady steam demand. The jet cooker draws steam continuously, so the boiler runs all day for one duty.
- Temperature control matters. Liquefaction below 95 °C leaves gelatinised starch that filters badly. Steam swings cause this.
- 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 converts about 10 tonnes of dry maize starch a day into glucose syrup. Starch slurry at 35% solids is preheated, jet-cooked to about 105 °C, held in liquefaction columns at 95–100 °C, then cooled to 60 °C for saccharification. It runs round the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Jet cooking | Slurry 60 → 105 °C | 28.6 t/day slurry (24,900 L at 1.15 kg/L), 35% solids | 1,217 |
| Liquefaction column hold | 95–100 °C | 3 columns × 3 kW losses × 20 h | 180 |
| Storage and pipework standing losses | – | about 5% | 70 |
| Total useful heat | 1,467 | ||
Averaged over 20 running hours, the heat pumps need about 73 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
- 3 × SE-WWUHT-27 (81 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,467 kWh in about 18.1 running hours.
- Heat source: liquefact cooling water at about 55 °C. Cooling the liquefact through the heat pump lowers cooling tower load.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water from the liquefact cooler, at about 55 °C, is the heat pump source.
- The heat pump makes 2 bar steam for the jet cooker and column tracing.
- Slurry preheating with flash vapour or a regenerative exchanger stays as it is, so the heat pump covers the final lift.
Selected equipment
| Model | SE-WWUHT-27 × 3 |
|---|---|
| Heating capacity | 27 kW each, 81 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 27.6 kW total at rated conditions |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 120 °C |
| Steam | 40 kg/h at 2 bar per SE-WWUHT-27 module |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
PT-101 on the low-pressure steam header controls heat pump capacity to hold 2 bar. TIC-201 holds jet cooker outlet at 105 °C. TIC-202 holds the columns at 95–100 °C. If header pressure falls below 1.6 bar, the boiler steam valve opens 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 dry starch | – | – |
| CO₂ per year | – | – |
06Benefits
Cooling heat reused
Heat removed before saccharification makes steam for the next batch of slurry.
Less cooling tower load
Cooling the liquefact through the heat pump reduces tower duty.
Steady liquefaction
A dedicated steam supply helps hold jet cooker temperature.
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
- Dry starch processed per day and slurry solids
- Jet cooker type and steam pressure
- Slurry temperature before the jet cooker
- Liquefact cooler flow and temperatures
- Current steam 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
Design notes
- Jet cooker pressure. Many jet cookers need steam well above 2 bar. Check the cooker, or use a low-pressure jet heater design.
- Feed water. Use softened and deaerated feed water for the heat pump steam generator.
- Enzyme dosing. Keep enzyme dosing linked to the jet cooker temperature as today.
- Electrical. About 28 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.