CO₂ capture solvent regenerated with heat-pump steam
How a plant capturing 3 tonnes of CO₂ a day from boiler flue gas can supply its stripper reboiler with low-pressure steam from a heat pump running on stripper cooling water, and what it saves against a furnace-oil fired steam 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
- Regeneration is the main energy cost. Stripping CO₂ from the solvent takes most of the energy in capture, usually supplied as steam from a fired boiler.
- Heat leaves through the coolers. The stripper overhead condenser and lean-amine cooler reject heat at 55–70 °C to the cooling tower.
- Burning fuel to capture CO₂. A fuel-fired boiler for the reboiler adds CO₂ of its own, which cuts the net capture.
- 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 captures about 3 tonnes a day of CO₂ from its boiler flue gas for food-grade and industrial CO₂ sales. It uses an advanced amine solvent that regenerates at 105–110 °C and runs round the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Stripper reboiler duty | 105–110 °C | 3 t CO₂/day × 2.8 GJ/t | 2,333 |
| CO₂ dryer regeneration gas heating | Gas 30 → 110 °C | 150 m³/h × 1.9 kg/m³ × 0.85 kJ/kg·K × 80 K × 8 h | 43 |
| Storage and pipework standing losses | – | about 5% | 119 |
| Total useful heat | 2,495 | ||
Averaged over 20 running hours, the heat pumps need about 125 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 2,495 kWh in about 18.5 running hours.
- Heat source: stripper overhead condenser and lean-amine cooler water at about 58 °C. Cooling the stripper overhead and lean amine is a by-product, which cuts cooling-tower load and solvent losses.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water from the stripper overhead condenser and lean-amine cooler, at about 58 °C, feeds the steam-generating heat pump evaporator.
- The heat pump makes 2 bar steam at about 120 °C for the stripper reboiler and the CO₂ dryer regeneration heater.
- The existing boiler steam header stays connected through a pressure-reducing station as standby.
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
The heat pump holds steam header pressure at 2 bar, and the boiler PRV is set slightly lower so it opens only if the heat pump cannot keep up. The reboiler controller sets steam flow to hold stripper bottom temperature. The cooling tower stays on the overhead condenser to take 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 CO₂ | – | – |
| CO₂ per year | – | – |
06Benefits
Higher net capture
Less fuel burnt for regeneration means less new CO₂ to capture.
Heat recycled in the loop
Heat from the overhead condenser and lean-amine cooler is returned to the reboiler.
Smaller cooling tower load
The overhead and lean-amine coolers send less heat to the tower.
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
- CO₂ capture rate and solvent type
- Reboiler temperature and steam use
- Overhead condenser and lean-amine cooler duties and temperatures
- Boiler fuel use for the capture plant
- 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
- Solvent choice sets the limit. Heat-pump steam at about 120 °C suits solvents that regenerate at 105–110 °C. Confirm reboiler temperature with the solvent supplier.
- Amine on the source side. Keep an isolating exchanger between amine coolers and the heat pump so no amine reaches the heat pump.
- 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
CO₂ capture solvent regenerated with heat-pump steam
How a plant capturing 3 tonnes of CO₂ a day from boiler flue gas can supply its stripper reboiler with low-pressure steam from a heat pump running on stripper cooling water, and what it saves against a furnace-oil fired steam 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
- Regeneration is the main energy cost. Stripping CO₂ from the solvent takes most of the energy in capture, usually supplied as steam from a fired boiler.
- Heat leaves through the coolers. The stripper overhead condenser and lean-amine cooler reject heat at 55–70 °C to the cooling tower.
- Burning fuel to capture CO₂. A fuel-fired boiler for the reboiler adds CO₂ of its own, which cuts the net capture.
- 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 captures about 3 tonnes a day of CO₂ from its boiler flue gas for food-grade and industrial CO₂ sales. It uses an advanced amine solvent that regenerates at 105–110 °C and runs round the clock.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Stripper reboiler duty | 105–110 °C | 3 t CO₂/day × 2.8 GJ/t | 2,333 |
| CO₂ dryer regeneration gas heating | Gas 30 → 110 °C | 150 m³/h × 1.9 kg/m³ × 0.85 kJ/kg·K × 80 K × 8 h | 43 |
| Storage and pipework standing losses | – | about 5% | 119 |
| Total useful heat | 2,495 | ||
Averaged over 20 running hours, the heat pumps need about 125 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 2,495 kWh in about 18.5 running hours.
- Heat source: stripper overhead condenser and lean-amine cooler water at about 58 °C. Cooling the stripper overhead and lean amine is a by-product, which cuts cooling-tower load and solvent losses.
- The furnace-oil fired steam boiler stays connected behind a normally closed valve as standby.
- Cooling water from the stripper overhead condenser and lean-amine cooler, at about 58 °C, feeds the steam-generating heat pump evaporator.
- The heat pump makes 2 bar steam at about 120 °C for the stripper reboiler and the CO₂ dryer regeneration heater.
- The existing boiler steam header stays connected through a pressure-reducing station as standby.
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
The heat pump holds steam header pressure at 2 bar, and the boiler PRV is set slightly lower so it opens only if the heat pump cannot keep up. The reboiler controller sets steam flow to hold stripper bottom temperature. The cooling tower stays on the overhead condenser to take 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 CO₂ | – | – |
| CO₂ per year | – | – |
06Benefits
Higher net capture
Less fuel burnt for regeneration means less new CO₂ to capture.
Heat recycled in the loop
Heat from the overhead condenser and lean-amine cooler is returned to the reboiler.
Smaller cooling tower load
The overhead and lean-amine coolers send less heat to the tower.
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
- CO₂ capture rate and solvent type
- Reboiler temperature and steam use
- Overhead condenser and lean-amine cooler duties and temperatures
- Boiler fuel use for the capture plant
- 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
- Solvent choice sets the limit. Heat-pump steam at about 120 °C suits solvents that regenerate at 105–110 °C. Confirm reboiler temperature with the solvent supplier.
- Amine on the source side. Keep an isolating exchanger between amine coolers and the heat pump so no amine reaches the heat pump.
- 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.