By combining a drum dryer with a fluidized-bed cooler, the advantages of both systems complement each other. The result is a design that is highly attractive in terms of energy efficiency and offers an excellent solution, no matter whether it is used for new plants or for expansion programmes.
Cooling tubes incorporated in the fluidized-bed cooler allow the air rate required for sugar cooling to be reduced to such an extent that the complete volume of exhaust air leaving the fluidized-bed unit can be utilized in the drying drum. While passing through the fluidized-bed cooler, this air reaches temperatures that are highly effective for drying purposes. The energy required to heat the drying air can thus be reduced substantially.
When it is reused in the drying drum, the exhaust air leaving the fluidized-bed cooler need not be freed from dust. The combined exhaust air volume produced by sugar drying and cooling can thus be reduced dramatically, resulting in far lower costs for exhaust air dedusting equipment, and smaller exhaust-air fans with lower power requirements. This energy saving effect makes the combined drum dryer / fluidized-bed cooler system a highly energy efficient option.
The addition of a fluidized-bed cooler fitted with cooling elements is also an excellent solution for improving the performance of existing drum dryer / cooler systems with inadequate cooling rates. In such a case, only the fluidized-bed cooler with a fan for the ingoing air needs to be installed. All exhaust air will be transferred to the existing drum-type cooling system, where it helps improve the drying capacity before being discharged through the available exhaust air piping.
- Reduced air rates for the processes drying and cooling
- Exhaust air from cooling system used for drying, without any additional dust dedusting equipment
- Thermal energy savings
- Sugar exposed to low temperature loads in the drying process
- Thermal / mechanical interaction on the crystal surface for optimum drying in the drum dryer
- Large drum volume helps produce uniform flow rates for all downstream equipment
- Sugar lumps or short periods of elevated sugar moisture are tolerated without any problems
- A central pipe can be installed for improved drying efficiency
- Effective cooling in the fluidized bed
- Adjustment of constant sugar outlet temperatures throughout 24-hour periods in systems of adequate capacity
- Compact plant design
- Separation of dust particles from sugar stream