Detailed information of SWISS COMBI ecoDry system

Typical values for ecoDry drying:

  • drum inlet temperature of superheated steam 400 - 500°C
  • drum outlet temperature of superheated steam 120 - 130°C
  • Flue gas temperature 150 - 160°C
  • Heat consumption 2'700 - 2'900 kJ/kg of water evaporation

Comparison to conventional drum dryer:

The ecoDry system using superheated steam as the drying medium results in the fact that drying in a steam atmosphere is more efficient. The primary energy consumption is up to 11% lower in order to achieve the same amount of product output. 

Other typical emission reduction compared to conventional drum dryers:

Flue gas: 48% lower

NOx: 14% lower

TOC: 100% lower (almost 0)

Particulate matter: 100% lower (almost 0)

CO: 86% lower


Energy Recovery:

The ecoDry has an important advantage in terms of energy recovery. If energy needs to be recovered from the exhaust gas, there are two possibilities to recover. either from the flue gas or from the superheated steam cycle. roughly 25% of the fluid in the superheated steam cycle is constantly brought to the burner to be thermally oxidised. This fluid has a dew point temperature of up to 93°C which means that energy recovery can be achieved at this temperature level. A conventional drum dryer in comparison has a dew point temperature of roughly 65 to 70°C.

Most industries using ecoDry systems due to odor treatment also use evaporators in other process steps. The bleed off gas from the superheated steam cycle perfectly matches the energy requirement of evaporators. This means that the steam can be guided through the evaporator heat exchanger while condensing. The bleed off gas after the evaporator's heat exchanger again is thermally oxidised in the ecoDry burner.


Possibilities with the ecoDry system:

ecoDry systems are not only dryers but a complete process in terms of air treatment, product treatment and product handling. The ecoDry system requires one feeding point and has one outlet point where the product can immediately be processed for further refinement. Cooling, mixing of syrup and wet product together with dry product is integrated into the drying process.


Best product quality can be achieved by:

  • low exhaust temperatures
  • short residence time
  • evaporative cooling
  • smaller particles
  • turbulence
  • minimal contact with hot surfaces


Main cost drivers in drying:

  • High inlet temperature of the drying gas reduces airflow and increases drying efficiency
  • Heat loss to the atmosphere (exhaust gas temperature)
  • Electrical power demand
ecoDry with energy recuperation possibilities shown
ecoDry with energy recuperation possibilities shown

1. Gas or Fuel Burner
2. Combustion Chamber
3. Gas/Gas Heat Exchanger
4. Exhaust Gas Fan 
5. Exhaust Gas
6. Wet Product
7.  Syrup
8.  Dry Product
9.  Drum
10. Dry Product Separation
11. Main Fan
12. Cold Bleed-Off with or without Evaporator
13. Hot Bleed-Off
14. Exhaust Gas Recirculation
15. Product Cooler
16. Cooling Air as primary Air

E   Waste Heat Evaporator