Column reboiler steam from overhead condenser heat
How a 2 KLPD rectification unit can raise reboiler steam from its own overhead condenser water, and what it saves against a briquette-fired 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
- Heat in at the bottom, out at the top. Almost all the reboiler steam leaves the column again in the overhead condenser at around 78 °C, and goes to the cooling tower.
- Boiler steam far hotter than needed. Column bottoms boil at 95–105 °C, but the boiler makes steam at 150 °C or more.
- Biomass supply and ash. Briquette quality and price vary by season, and the boiler needs ash handling and an attendant around the clock.
- 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 unit redistils purchased rectified spirit into 2,000 litres a day of extra neutral alcohol, running round the clock. It has a rectifier column and an aldehyde column, each with a steam reboiler and a water-cooled overhead condenser.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rectifier column reboiler | Bottoms 102–105 °C | 2,000 L/day ENA × 1.4 kg steam/L × 0.63 kWh/kg | 1,764 |
| Aldehyde column reboiler | Bottoms 95 °C | 2,000 L/day × 0.4 kg steam/L × 0.63 kWh/kg | 504 |
| Storage and pipework standing losses | – | about 5% | 113 |
| Total useful heat | 2,381 | ||
Averaged over 20 running hours, the heat pumps need about 119 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 2,381 kWh in about 17.6 running hours.
- Heat source: column overhead condenser water at about 58 °C. Heat taken from the overhead condenser water cuts the cooling tower duty by the same amount.
- The briquette-fired steam boiler stays connected behind a normally closed valve as standby.
- The overhead condensers are run warmer, returning water at about 58 °C, which becomes the heat pump source.
- The heat pumps make 2 bar steam at about 120 °C and feed it to both reboilers through the existing steam header.
- Column heat that used to leave through the cooling tower is returned to the reboilers.
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 steam header calls the heat pumps on below 1.8 bar and unloads them at 2.0 bar. TT-102 on the condenser water return stops a unit if the source falls below 50 °C. TIC-201 and TIC-202 keep column bottoms temperatures through the reboiler steam valves. The boiler stays on the header as standby and for start-up.
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 ENA | – | – |
| CO₂ per year | – | – |
06Benefits
Column heat recycled
Heat rejected at the top of the column is lifted and fed back to the bottom.
Smaller cooling tower duty
The overhead condensers send less heat to the cooling tower.
Stable column operation
Steady steam pressure from the heat pumps helps hold column profiles and product purity.
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
- Spirit throughput and steam per litre for each column
- Reboiler type, area and design steam pressure
- Overhead condenser area and cooling water flow
- Area classification drawing of the distillation house
- 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
- Reboiler area. 2 bar steam gives a smaller temperature difference in the reboiler. Check the reboiler area, or consider running the column under slight vacuum.
- Condenser temperature. Running the overhead condenser warmer needs enough condenser area to keep reflux and vent losses in limits. Check vent condenser performance.
- Flammable area. Locate the heat pumps outside the classified area of the distillation house and connect through water and steam lines only.
- 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
Column reboiler steam from overhead condenser heat
How a 2 KLPD rectification unit can raise reboiler steam from its own overhead condenser water, and what it saves against a briquette-fired 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
- Heat in at the bottom, out at the top. Almost all the reboiler steam leaves the column again in the overhead condenser at around 78 °C, and goes to the cooling tower.
- Boiler steam far hotter than needed. Column bottoms boil at 95–105 °C, but the boiler makes steam at 150 °C or more.
- Biomass supply and ash. Briquette quality and price vary by season, and the boiler needs ash handling and an attendant around the clock.
- 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 unit redistils purchased rectified spirit into 2,000 litres a day of extra neutral alcohol, running round the clock. It has a rectifier column and an aldehyde column, each with a steam reboiler and a water-cooled overhead condenser.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rectifier column reboiler | Bottoms 102–105 °C | 2,000 L/day ENA × 1.4 kg steam/L × 0.63 kWh/kg | 1,764 |
| Aldehyde column reboiler | Bottoms 95 °C | 2,000 L/day × 0.4 kg steam/L × 0.63 kWh/kg | 504 |
| Storage and pipework standing losses | – | about 5% | 113 |
| Total useful heat | 2,381 | ||
Averaged over 20 running hours, the heat pumps need about 119 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 2,381 kWh in about 17.6 running hours.
- Heat source: column overhead condenser water at about 58 °C. Heat taken from the overhead condenser water cuts the cooling tower duty by the same amount.
- The briquette-fired steam boiler stays connected behind a normally closed valve as standby.
- The overhead condensers are run warmer, returning water at about 58 °C, which becomes the heat pump source.
- The heat pumps make 2 bar steam at about 120 °C and feed it to both reboilers through the existing steam header.
- Column heat that used to leave through the cooling tower is returned to the reboilers.
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 steam header calls the heat pumps on below 1.8 bar and unloads them at 2.0 bar. TT-102 on the condenser water return stops a unit if the source falls below 50 °C. TIC-201 and TIC-202 keep column bottoms temperatures through the reboiler steam valves. The boiler stays on the header as standby and for start-up.
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 ENA | – | – |
| CO₂ per year | – | – |
06Benefits
Column heat recycled
Heat rejected at the top of the column is lifted and fed back to the bottom.
Smaller cooling tower duty
The overhead condensers send less heat to the cooling tower.
Stable column operation
Steady steam pressure from the heat pumps helps hold column profiles and product purity.
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
- Spirit throughput and steam per litre for each column
- Reboiler type, area and design steam pressure
- Overhead condenser area and cooling water flow
- Area classification drawing of the distillation house
- 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
- Reboiler area. 2 bar steam gives a smaller temperature difference in the reboiler. Check the reboiler area, or consider running the column under slight vacuum.
- Condenser temperature. Running the overhead condenser warmer needs enough condenser area to keep reflux and vent losses in limits. Check vent condenser performance.
- Flammable area. Locate the heat pumps outside the classified area of the distillation house and connect through water and steam lines only.
- 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.