The purpose of a reheater is to heat up the massecuite which you just cooled down in the crystallisers. You cooled the massecuite in the crystallisers in order to grow the crystals by depositing sucrose in the mother liquor onto the crystals created in the pan.
The reason you now reheat the massecuite is to reduce the viscosity of the massecuite to make the separation of the crystal from the mother liquor in the centrifugal easier. If the crystallisers have been doing their work properly the massecuite will be at about 40°C. In order to be free spinning the massecuite should be heated to about 55°C. The hot water water temperature should not exceed the massecuite outlet temperature by more than 2 or 3°C.
C-massecuite specific heat capacity, in the above temperature range, is about 1.7 to 1.8 kJ/kg/K. The overall heat transfer coefficient (OHTC) for a reheater can be as low as 0.011 kW/m2/K but with careful design this can be increased significantly. The flow velocity of water in the finned tubes should be in the range 1.5 to 2 m/s, in order to achieve the required OHTC. Care must be taken to ensure that the number of water passes and length of each pass ensures the correct flow velocity without causing excessive pressure drops in the water circuit due to friction. The frictional head loss through the reheater heating bank must be carefully calculated to ensure proper design of the reheater.
The Sugar Engineers can provide a very cost effective and rapid design for a reheater for your factory. The design features of the Sugar Engineers massecuite reheater are:
You can do an online preliminary design for your factory using our Rapid Design service