Vacuum salt brine preheated with condenser heat
How a 15 tonne-per-day vacuum salt plant can preheat its feed brine with a water-source heat pump running on vapour-condenser water, and what it saves against a biomass-fired steam boiler.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Feed brine enters cold. Brine from storage enters at ambient, and the first effect uses live steam just to bring it up to boiling.
- Condenser heat is dumped. The last-effect condenser rejects a large amount of heat at 40–50 °C to a cooling tower.
- Steam cost per tonne. Steam is the biggest cost in vacuum salt production after brine itself.
- Losses between fuel and process. Burning briquettes 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 makes about 15 tonnes a day of refined vacuum salt in a multiple-effect evaporator. It runs round the clock, purifying saturated brine before evaporation and washing the salt in centrifuges.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Feed brine preheat | 30 → 75 °C | 45,000 L/day saturated brine, ρ 1.2, cp 3.3, 30 → 75 °C | 2,228 |
| Brine purification tank | 30 → 60 °C | 15,000 L/day, ρ 1.2, cp 3.3, 30 → 60 °C | 495 |
| Centrifuge salt wash water | 30 → 70 °C | 5,000 L/day, 30 → 70 °C | 232 |
| Storage and pipework standing losses | – | about 5% | 148 |
| Total useful heat | 3,102 | ||
Averaged over 20 running hours, the heat pumps need about 155 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
- 6 × SE-WWUHT-27 (162 kW total) (SE-WWUHT water-source, R245fa) delivering 85 °C, covering the day's 3,102 kWh in about 19.2 running hours.
- A 5,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: last-effect vapour-condenser water at about 45 °C. Cooling the vapour-condenser water lowers last-effect pressure, which helps the vacuum system and the cooling tower.
- The biomass-fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water leaving the last-effect condenser at about 45 °C passes through the heat pump evaporator before returning to the tower.
- The heat pump supplies 85 °C water to a titanium brine preheater, the purification tank coil and the wash water exchanger.
- The existing steam preheater stays in series to bring brine from 75 °C to first-effect temperature.
Selected equipment
| Model | SE-WWUHT-27 × 6 |
|---|---|
| Heating capacity | 27 kW each, 162 kW total |
| COP | 2.93 estimated for a 45 °C source (the data sheet is rated on a 60/55 °C source) |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 85 °C |
| Storage | 5,000 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 starts the heat pump below 80 °C and stops it at 85 °C. TIC-201 holds feed brine at 75 °C leaving PHE-201, and the steam preheater trims the rest. TIC-202 and TIC-203 hold the purification tank and wash water. The condenser cooling tower takes any heat the heat pump does not use.
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 salt | – | – |
| CO₂ per year | – | – |
06Benefits
Less live steam
Brine arrives at the first effect much hotter, so the boiler supplies less steam per tonne of salt.
Condenser helped
Taking heat from the condenser water lowers its temperature, which helps last-effect vacuum.
Better purification
Warm brine settles impurities faster in the purification stage.
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
- Salt output per day and brine concentration
- Number of effects and first-effect temperature
- Condenser cooling water flow and temperatures
- Steam consumption per tonne of salt
- 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
- Brine corrosion. Use titanium plates or tubes on all brine-side exchangers.
- Scaling. Calcium sulphate scale forms faster as brine gets hotter. Purify brine before the preheater and plan regular acid cleaning.
- 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.
- 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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Vacuum salt brine preheated with condenser heat
How a 15 tonne-per-day vacuum salt plant can preheat its feed brine with a water-source heat pump running on vapour-condenser water, and what it saves against a biomass-fired steam boiler.
▶Video: Waste-heat recovery heat pumps
V10 · 2–2.5 minLifting warm water from condensers, effluent and process cooling to useful heat
Video coming soon01Problem statement
- Feed brine enters cold. Brine from storage enters at ambient, and the first effect uses live steam just to bring it up to boiling.
- Condenser heat is dumped. The last-effect condenser rejects a large amount of heat at 40–50 °C to a cooling tower.
- Steam cost per tonne. Steam is the biggest cost in vacuum salt production after brine itself.
- Losses between fuel and process. Burning briquettes 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 makes about 15 tonnes a day of refined vacuum salt in a multiple-effect evaporator. It runs round the clock, purifying saturated brine before evaporation and washing the salt in centrifuges.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Feed brine preheat | 30 → 75 °C | 45,000 L/day saturated brine, ρ 1.2, cp 3.3, 30 → 75 °C | 2,228 |
| Brine purification tank | 30 → 60 °C | 15,000 L/day, ρ 1.2, cp 3.3, 30 → 60 °C | 495 |
| Centrifuge salt wash water | 30 → 70 °C | 5,000 L/day, 30 → 70 °C | 232 |
| Storage and pipework standing losses | – | about 5% | 148 |
| Total useful heat | 3,102 | ||
Averaged over 20 running hours, the heat pumps need about 155 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
- 6 × SE-WWUHT-27 (162 kW total) (SE-WWUHT water-source, R245fa) delivering 85 °C, covering the day's 3,102 kWh in about 19.2 running hours.
- A 5,000 L insulated storage tank decouples the heat pumps from the process peaks.
- Heat source: last-effect vapour-condenser water at about 45 °C. Cooling the vapour-condenser water lowers last-effect pressure, which helps the vacuum system and the cooling tower.
- The biomass-fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water leaving the last-effect condenser at about 45 °C passes through the heat pump evaporator before returning to the tower.
- The heat pump supplies 85 °C water to a titanium brine preheater, the purification tank coil and the wash water exchanger.
- The existing steam preheater stays in series to bring brine from 75 °C to first-effect temperature.
Selected equipment
| Model | SE-WWUHT-27 × 6 |
|---|---|
| Heating capacity | 27 kW each, 162 kW total |
| COP | 2.93 estimated for a 45 °C source (the data sheet is rated on a 60/55 °C source) |
| Rating | water or steam to 120 °C, R245fa |
| Supply temperature | 85 °C |
| Storage | 5,000 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 starts the heat pump below 80 °C and stops it at 85 °C. TIC-201 holds feed brine at 75 °C leaving PHE-201, and the steam preheater trims the rest. TIC-202 and TIC-203 hold the purification tank and wash water. The condenser cooling tower takes any heat the heat pump does not use.
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 salt | – | – |
| CO₂ per year | – | – |
06Benefits
Less live steam
Brine arrives at the first effect much hotter, so the boiler supplies less steam per tonne of salt.
Condenser helped
Taking heat from the condenser water lowers its temperature, which helps last-effect vacuum.
Better purification
Warm brine settles impurities faster in the purification stage.
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
- Salt output per day and brine concentration
- Number of effects and first-effect temperature
- Condenser cooling water flow and temperatures
- Steam consumption per tonne of salt
- 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
- Brine corrosion. Use titanium plates or tubes on all brine-side exchangers.
- Scaling. Calcium sulphate scale forms faster as brine gets hotter. Purify brine before the preheater and plan regular acid cleaning.
- 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.
- 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.