Evaporator steam made from evaporator waste heat
How a triple-effect falling-film evaporator removing 5,000 kg of water a day can take its first-effect steam from a heat pump fed by its own condensate, 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
- Steam in, warm water out. The evaporator takes in steam at the first effect and rejects nearly the same heat as warm condensate and condenser water.
- Cooling tower load. The last-effect vapour condenser loads the cooling tower, and vacuum suffers on hot days.
- Feed preheat also on steam. Bringing feed to 95 °C adds a second steam user that runs for the whole campaign.
- 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 runs a triple-effect falling-film evaporator for milk concentrate, with campaigns of fruit juice and tomato paste. It evaporates about 500 kg of water an hour over a 10-hour run, followed by CIP. Feed is preheated to about 95 °C before the first effect.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| First-effect steam | Steam 2 bar, ~120 °C | 5,000 kg/day water removed ÷ economy 2.6 = 1,920 kg steam × 0.62 kWh/kg | 1,190 |
| Feed preheating | 60 → 95 °C | 6,900 L/day feed at 12.5% solids | 272 |
| Storage and pipework standing losses | – | about 5% | 73 |
| Total useful heat | 1,535 | ||
Averaged over 12 running hours, the heat pumps need about 128 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
- 5 × SE-WWUHT-27 (135 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,535 kWh in about 11.4 running hours.
- Heat source: evaporator condensate and vapour-condenser water at about 55 °C. Cooling the vapour-condenser water reduces cooling tower load and improves last-effect vacuum.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Condensate from the calandrias and water from the vapour condenser are collected at about 55 °C and fed to the water-source heat pump.
- The heat pump makes 2 bar steam for the first-effect calandria, taking over from the boiler during the run.
- The feed preheater is moved to the same steam header.
- For new or larger lines, mechanical vapour recompression (MVR) is the natural next step and can be studied separately.
Selected equipment
| Model | SE-WWUHT-27 × 5 |
|---|---|
| Heating capacity | 27 kW each, 135 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 46.0 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 the first-effect temperature through the existing steam valve. TIC-202 holds feed at 95 °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 1,000 L feed | – | – |
| CO₂ per year | – | – |
06Benefits
Evaporator feeds itself
Heat leaving in condensate and condenser water is returned to the first effect.
Better vacuum
Cooling the vapour-condenser water helps the last effect hold vacuum on hot afternoons.
Smaller boiler duty
The boiler is needed only for start-up and standby during the run.
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
- Evaporation rate and number of effects
- Steam consumption and pressure at the first effect
- Condensate and condenser water flows and temperatures
- Feed rate, solids in and out
- Campaign and CIP hours
- 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
- Condensate quality. Vapour condensate can carry product traces. Use it only as a heat source through an exchanger, never as boiler feed without checks.
- Steam pressure. Confirm the first-effect calandria works at 2 bar supply. Most falling-film first effects run well below this.
- Start-up. Use boiler steam to bring the evaporator to temperature until enough condensate is available as a source.
- Electrical. About 46 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
Evaporator steam made from evaporator waste heat
How a triple-effect falling-film evaporator removing 5,000 kg of water a day can take its first-effect steam from a heat pump fed by its own condensate, 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
- Steam in, warm water out. The evaporator takes in steam at the first effect and rejects nearly the same heat as warm condensate and condenser water.
- Cooling tower load. The last-effect vapour condenser loads the cooling tower, and vacuum suffers on hot days.
- Feed preheat also on steam. Bringing feed to 95 °C adds a second steam user that runs for the whole campaign.
- 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 runs a triple-effect falling-film evaporator for milk concentrate, with campaigns of fruit juice and tomato paste. It evaporates about 500 kg of water an hour over a 10-hour run, followed by CIP. Feed is preheated to about 95 °C before the first effect.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| First-effect steam | Steam 2 bar, ~120 °C | 5,000 kg/day water removed ÷ economy 2.6 = 1,920 kg steam × 0.62 kWh/kg | 1,190 |
| Feed preheating | 60 → 95 °C | 6,900 L/day feed at 12.5% solids | 272 |
| Storage and pipework standing losses | – | about 5% | 73 |
| Total useful heat | 1,535 | ||
Averaged over 12 running hours, the heat pumps need about 128 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
- 5 × SE-WWUHT-27 (135 kW total) (SE-WWUHT water-source, R245fa) delivering 120 °C, covering the day's 1,535 kWh in about 11.4 running hours.
- Heat source: evaporator condensate and vapour-condenser water at about 55 °C. Cooling the vapour-condenser water reduces cooling tower load and improves last-effect vacuum.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Condensate from the calandrias and water from the vapour condenser are collected at about 55 °C and fed to the water-source heat pump.
- The heat pump makes 2 bar steam for the first-effect calandria, taking over from the boiler during the run.
- The feed preheater is moved to the same steam header.
- For new or larger lines, mechanical vapour recompression (MVR) is the natural next step and can be studied separately.
Selected equipment
| Model | SE-WWUHT-27 × 5 |
|---|---|
| Heating capacity | 27 kW each, 135 kW total |
| COP | 2.93 at the data sheet's rated condition (60/55 °C source water) |
| Power input | about 46.0 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 the first-effect temperature through the existing steam valve. TIC-202 holds feed at 95 °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 1,000 L feed | – | – |
| CO₂ per year | – | – |
06Benefits
Evaporator feeds itself
Heat leaving in condensate and condenser water is returned to the first effect.
Better vacuum
Cooling the vapour-condenser water helps the last effect hold vacuum on hot afternoons.
Smaller boiler duty
The boiler is needed only for start-up and standby during the run.
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
- Evaporation rate and number of effects
- Steam consumption and pressure at the first effect
- Condensate and condenser water flows and temperatures
- Feed rate, solids in and out
- Campaign and CIP hours
- 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
- Condensate quality. Vapour condensate can carry product traces. Use it only as a heat source through an exchanger, never as boiler feed without checks.
- Steam pressure. Confirm the first-effect calandria works at 2 bar supply. Most falling-film first effects run well below this.
- Start-up. Use boiler steam to bring the evaporator to temperature until enough condensate is available as a source.
- Electrical. About 46 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.