API vacuum dryers heated with stored hot water
How an API plant running rotocone and vacuum tray dryers at 60–110 °C can heat their jackets and shelves with heat pump hot water, against a diesel-fired boiler.
▶Video: Heat pumps for pharma, chemicals and FMCG
V04 · 2–2.5 minJacketed reactors, hot loops, cleanroom reheat and solvent recovery
Video coming soon01Problem statement
- Steam is too hot for jackets. Many APIs degrade above 60 to 80 °C, so steam is reduced to hot water through a set that hunts and overshoots.
- Long heat-up times. Hot-water sets fed by a distant boiler take time to come up to temperature at each batch change.
- Boiler running for small loads. On weekends and night shifts the boiler runs at low load just to keep dryers warm.
- Losses between fuel and process. Burning diesel 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 API block runs two rotocone vacuum dryers and four vacuum tray dryers around the clock. Together they remove about 700 kg of water and solvent a day from wet cake.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rotocone dryers, evaporation | Jacket 80–110 °C | 400 kg water and solvent/day × 0.6 kWh/kg incl. latent, +15% jacket losses | 276 |
| Vacuum tray dryers, evaporation | Shelves 60–80 °C | 300 kg water and solvent/day × 0.7 kWh/kg incl. latent and shelf losses | 210 |
| Vessel heat-up | 30 → 90 °C | 2 batches × 3,000 kg steel × 0.5 kJ/kg·K × 80 K | 67 |
| Storage and pipework standing losses | – | about 5% | 28 |
| Total useful heat | 581 | ||
Averaged over 20 running hours, the heat pumps need about 29 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
- A SE-UHT air-source cascade, R245fa machine of about 30 kW, air-source cascade to 120 °C, sized per project.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired steam boiler with hot-water set stays connected behind a normally closed valve as standby.
- The heat pumps charge a pressurised storage tank at up to 120 °C. Each dryer draws from the secondary loop through its own mixing valve.
- Jacket and shelf temperatures are set per product, so low-temperature APIs never see steam temperatures.
- The tank covers batch-change heat-up peaks, so the heat pumps run steadily.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 30 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 120 °C |
| Storage | 1,000 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 calls the heat pumps on below 110 °C and off at 120 °C, and TT-102 at the bottom stages the second unit. TIC-201 and TIC-202 hold each dryer's jacket or shelf inlet temperature with a three-way mixing valve. The existing steam hot-water set stays connected 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 batch dried | – | – |
| CO₂ per year | – | – |
06Benefits
Tighter product temperature
Mixing-valve control on hot water avoids the overshoot of steam-fed sets, which protects heat-sensitive APIs.
Ready at batch change
Stored hot water brings a dryer up to temperature without waiting for the boiler.
No idle boiler
Night and weekend drying runs on the heat pumps alone.
Lower energy cost
Each kWh of electricity delivers about 1.6 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.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Number, type and size of vacuum dryers
- Jacket and shelf temperature per product
- Water and solvent evaporated per batch
- Batch cycle times
- Present steam or hot-water set arrangement
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Hazardous area. Solvent dryers sit in classified areas. Keep heat pumps and tank outside, and bring only the water loop into the block.
- Pressurised water. Water above 100 °C needs a pressurised loop with expansion vessel and relief valves. Check the jacket design pressure of each dryer.
- Validation. Jacket heating medium is part of the validated process. Record jacket inlet temperatures during qualification runs.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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.
Talk to us
API vacuum dryers heated with stored hot water
How an API plant running rotocone and vacuum tray dryers at 60–110 °C can heat their jackets and shelves with heat pump hot water, against a diesel-fired boiler.
▶Video: Heat pumps for pharma, chemicals and FMCG
V04 · 2–2.5 minJacketed reactors, hot loops, cleanroom reheat and solvent recovery
Video coming soon01Problem statement
- Steam is too hot for jackets. Many APIs degrade above 60 to 80 °C, so steam is reduced to hot water through a set that hunts and overshoots.
- Long heat-up times. Hot-water sets fed by a distant boiler take time to come up to temperature at each batch change.
- Boiler running for small loads. On weekends and night shifts the boiler runs at low load just to keep dryers warm.
- Losses between fuel and process. Burning diesel 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 API block runs two rotocone vacuum dryers and four vacuum tray dryers around the clock. Together they remove about 700 kg of water and solvent a day from wet cake.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Rotocone dryers, evaporation | Jacket 80–110 °C | 400 kg water and solvent/day × 0.6 kWh/kg incl. latent, +15% jacket losses | 276 |
| Vacuum tray dryers, evaporation | Shelves 60–80 °C | 300 kg water and solvent/day × 0.7 kWh/kg incl. latent and shelf losses | 210 |
| Vessel heat-up | 30 → 90 °C | 2 batches × 3,000 kg steel × 0.5 kJ/kg·K × 80 K | 67 |
| Storage and pipework standing losses | – | about 5% | 28 |
| Total useful heat | 581 | ||
Averaged over 20 running hours, the heat pumps need about 29 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
- A SE-UHT air-source cascade, R245fa machine of about 30 kW, air-source cascade to 120 °C, sized per project.
- A 1,000 L insulated storage tank decouples the heat pumps from the process peaks.
- The diesel-fired steam boiler with hot-water set stays connected behind a normally closed valve as standby.
- The heat pumps charge a pressurised storage tank at up to 120 °C. Each dryer draws from the secondary loop through its own mixing valve.
- Jacket and shelf temperatures are set per product, so low-temperature APIs never see steam temperatures.
- The tank covers batch-change heat-up peaks, so the heat pumps run steadily.
Selected equipment
| Machine | SE-UHT air-source cascade, R245fa |
|---|---|
| Capacity | about 30 kW, built to duty |
| Concept | air-source cascade to 120 °C, sized per project |
| COP used | 1.6 (estimate) |
| Supply temperature | 120 °C |
| Storage | 1,000 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 calls the heat pumps on below 110 °C and off at 120 °C, and TT-102 at the bottom stages the second unit. TIC-201 and TIC-202 hold each dryer's jacket or shelf inlet temperature with a three-way mixing valve. The existing steam hot-water set stays connected 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 batch dried | – | – |
| CO₂ per year | – | – |
06Benefits
Tighter product temperature
Mixing-valve control on hot water avoids the overshoot of steam-fed sets, which protects heat-sensitive APIs.
Ready at batch change
Stored hot water brings a dryer up to temperature without waiting for the boiler.
No idle boiler
Night and weekend drying runs on the heat pumps alone.
Lower energy cost
Each kWh of electricity delivers about 1.6 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.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Number, type and size of vacuum dryers
- Jacket and shelf temperature per product
- Water and solvent evaporated per batch
- Batch cycle times
- Present steam or hot-water set arrangement
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Hazardous area. Solvent dryers sit in classified areas. Keep heat pumps and tank outside, and bring only the water loop into the block.
- Pressurised water. Water above 100 °C needs a pressurised loop with expansion vessel and relief valves. Check the jacket design pressure of each dryer.
- Validation. Jacket heating medium is part of the validated process. Record jacket inlet temperatures during qualification runs.
- Ambient correction. Ratings are at 20 °C air. Ask Sunniva for the correction at your site's winter design temperature.
- 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.