Sugar

GEA Barr-Rosin has considerable experience in the drying and cooling of a variety of Sugars and Sweeteners. We can process:

Granulated Sugar

• beet sugar
• cane sugar
• dextrose, monohydrate
• dextrose, anhydrous
• fructose
• lactose
• specialty sweeteners
• proprietary formulations

We use two technologies:

Sugaronline - sugar industry news and prices

Rotary Dryer (or Granulator) For Sugars & Sweeteners

Rotary Dryer

Plant Description

The unit may be designed as a dryer (only), arranged for either co-current or counter -current operation, or as an evaporative cooler solely arranged for operation in counterflow. Evaporative cooling is normally employed when there is sufficient heat in the product for drying ie. generally at feed temperatures above 130oF (55­C).

The wet feed is delivered to the drying zone via an inclined feed chute (or screw). Helical vanes in the dryer inlet rapidly transfer the material away from this section and into a series of 'sawtooth' type lifters fitted throughout the dryer. The product lifted from the bed produces a cascade (or curtain) of falling material as the dynamic angle of repose is reached in each lifter during rotation of the dryer.

In the co-current dryer the filtered and heated air enters at the feed end, with both product and exhaust air leaving the discharge end.

In the case of the evaporative cooler, the product in contact with filtered ambient (or slightly heated) air exits the dryer (cooler) via a combined material discharge and air inlet hood.

The exhaust air (a mixture of drying air and water vapour) containing a small quantity of entrained 'fines', is passed to a self-induced spray type vertical venturi wet collector, via a centrifugal exhaust fan (and cyclone(s) if required). The water in the collector is recirculated, to achieve a concentration of approximately 15% solids, the sweetwater being returned to the Client's process.

The clean air is conveyed to atmosphere via an exhaust stack mounted directly above the wet collector.

The dryer normally operates on a balance draught system (with both FD and ID fans) whereby the air inlet is maintained under slightly negative pressure to prevent excessive air leakage.

Combined Rotary Dryer / Cooler For Sugars & Sweeteners

Plant Description

The combined unit is provided with drying and cooling zones, both arranged for operation in counterflow. This system is normally employed when there is insufficient heat in the product for drying (evaporative cooling) ie. generally at feed temperatures below 130oF (55­C) and when atmospheric humidity is high.

Filtered and heated drying air is introduced through an insulated central tube via the cooling section. Filtered ambient / conditioned cooling air is introduced directly into the discharge end of the drum. The heated air is mixed with the air leaving the cooling zone to provide the required temperature for drying, making full use of the heat gained from the cooling zone (thereby minimizing the additional thermal requirement and reducing the total air volume).

A small amount of moisture may be retained in the drying zone enabling a degree of evaporative cooling to take place as the hot product is subsequently cooled.

The wet feed is delivered to the drying zone via a feed chute (or screw). Helical vanes in the dryer inlet rapidly transfers the material away from this section and into a series of 'sawtooth' type lifters fitted throughout the drying and cooling zones. The product lifted from the bed produces a cascade (or curtain) of falling material as the dynamic angle of repose is reached in each lifter during rotation of the dryer/cooler.

The final product, in contact with ambient/conditioned air, exits the cooling zone via a combined material discharge and air inlet hood.

The exhaust air (a mixture of drying and cooling air and water vapour) containing a small quantity of entrained 'fines', exits the drying zone via a combined material feed and exhaust duct and is passed to a venturi wet collector (via cyclone(s) if required) and a centrifugal exhaust fan, the sweetwater and any collected dry material being returned to Client's process as necessary.

The clean air is conveyed to atmosphere via an exhaust stack mounted directly above the wet collector.

Two-Stage Dryer and Cooler For Sugars & Sweeteners

Plant Description

The system would comprise a counter-current Rotary Dryer/Cooler, followed by a secondary Fluidised Bed Cooler. This system is normally employed when the dry product is required at a temperature of less than 100-105°F (37-40­C).

The Rotary Dryer is designed to remove the majority of the moisture, while cooling the product to approximately 105oF (40­C) (wherever possible utilizing the evaporative cooling principle). A small amount of moisture may be retained for final removal in the fluid bed unit, which would reduce the product temperature to typically 68-85°F (20 -30­C) (according to ambient conditions).

The wet feed from the centrifuge is delivered to the rotary dryer via an inclined feed chute (or screw feeder). Helical vanes in the dryer inlet rapidly transfers the material away from this section and into a series of 'sawtooth' type lifters fitted throughout the dryer. The product lifted from the bed produces a cascade (or curtain) of falling material as the dynamic angle of repose is reached in each lifter during rotation of the dryer.

Filtered and heated ambient air is delivered to the Rotary Dryer/Cooler via a forced draught fan. The product in contact with the air in counterflow finally exits the dryer via a combined material discharge and air inlet hood.

The dried and partially cooled material leaving the Rotary Dryer/Cooler is then transferred to the secondary Fluid Bed Cooler, which operates on a balanced draught system to obviate the necessity for sealing.

Filtered, ambient cooling air is delivered to the fluid bed unit via a forced draught fan, resulting in the air being heated slightly by the fan prior to entry into the bed, thereby reducing the relative humidity. (The ambient air may also require conditioning according to the atmospheric humidity and temperature conditions).

The exhaust air from both the Rotary Dryer/Cooler and Fluid Bed Cooler, containing water vapour and a small quantity of entrained 'fines', passes to a self- induced spray type vertical venturi wet collector (or separate bag filter for the fluid bed cooler) and centrifugal exhaust fan(s). The water in the collector is recirculated, to achieve a minimum concentration of 15% solids, the sweetwater is then returned to the Client's process.

The clean air is conveyed to atmosphere via an exhaust stack mounted directly above the wet collector / bag filter.

Fluidised Bed Cooler For Sugars & Sweeteners

Plant Description

a) Two Fan System

The product enters the cooler via an inclined and divergent feed chute and flow horizontally in a shallow fluidised layer across the Fluid Bed, passing over a weir plate at the opposite end and into the discharge chute. This system ensures the best possible gentle handling and cooling of dried product and due to the inherent (and adjustable) de-dusting feature usually produces a clean bright crystal.

Sealing is not normally necessary, but rotary valves can be provided at the feed and discharge chutes if required.

The ambient cooling air is drawn from outside and then passed through a washable or automatic roll type filter (often followed by a disposable high efficiency filter). To avoid over-cooling the product when the ambient air is well below the design figure, or if the product throughput is reduced, a heater is included for raising the inlet air temperature. This is regulated automatically by a controller which senses the temperature in the fluidised bed of material, just before the weir.

Cooling air from a forced draught fan enters the bed (via a single or zoned plenum on the underside) which fluidizes and cools the product. The exhaust air would then pass to a venturi wet collector (or bag filter) which removes the small quantity of entrained particles, the sweetwater being returned to the Client's process. The fluidised bed operates under balanced draught conditions, ie. two fan system, which obviates the necessity for sealing at the inlet and outlet. Air is drawn through a wet collector (or bag filter) via an induced draught fan and exhausted to atmosphere.

b) Single Fan System

The basic system is as described above.

However, the single fan system requires the exhaust fan to draw the cooling air through the inlet, the filters, air heater, fluid bed cooler and wet collector/bag filter. In this case sealing at the inlet and outlet is required; the benefit of the system being that there is no heating of the ambient air by the forced draught fan, resulting in a reduced air flow and unit size.