Energy and the environment in beet sugar production

The beet sugar industry has improved its energy efficiency over the last 50 years, from using 250-300 kWh fuel per tonne of beet to 170 kWh for a good factory excluding pulp drying. This has been achieved through integration of the processes and good energy management, though without involving the pulp drying. Drum drying of the pulp requires 98 kWh/t beet. Therefore, the resulting total is 268 kWh/t. In order to reduce the energy use it is useful to divide the different processes in the factory into energy "users" and energy "transformers". The juice evaporator train is a "transformer". When designed correctly all ingoing energy will leave the evaporator to be used elsewhere. Drum drying of pulp and the sugar house are "users", as most energy supplied cannot be recovered. To save energy requires attention to the "users", and the "transformers" shall be adapted to fit into the system, so they are only transformers. Examples of this are given. In doing so, it is possible to come down to approximately 140-150 kWh supplied energy as fuel. This includes making sugar into white sugar, molasses with a purity of around 60%, and drying all the beet pulp. Energy saving offers reduced CO2 emission. Half of all the VOC (volatile organic compounds) leaving a sugar factory comes from the drum drying of pulp. Steam drying, however, produces no VOC and no dust emission to the atmosphere at all.