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Sugar processing

Energy

What forms of energy does a sugar factory need?
Thermal and electrical energy are needed to process sugar. Both forms of energy are obtained in a combined heat and power plant. Thermal energy is needed to turn the water into steam. The water is heated using waste heat flows.

How much energy does a sugar factory need?
The energy requirement of a sugar factory depends on the number of beet processed per day: At 10,000 tonnes of sugar beet per day, the boiler will require about 1,750 MWh and drying the slices 750.5 MWh.

Is heavy oil or gas used to produce steam?
The factories can use both fuels in a bivalent firing process. The fuel that is used will depend on availability and market price.

Why is raw lignite also used?
Raw lignite is a local German fuel, whose use depends on availability and market price, as in the case of other fuels. Modern processes ensure that the process is environmentally friendly.

What is the contribution of electrical energy?
A works processing 10,000 tonnes of sugar beet per day on average will require about 250 MWh of electrical energy. The electrical energy required is generated by a combined heat and power plant located in the works themselves. Electricity is normally only bought in if there are malfunctions in the power plant or turbine.

Is waste heat used?
Thermal energy is generated in a sugar factory's own combined heat and power plant. The factory actually only requires heat at one point in the process: the first stage of the evaporation unit. The steam resulting from evaporation at this stage is re-cycled for evaporation and heating purposes. This principle is repeated 5 or 6 times, which means that about 75 % of a sugar factory's energy requirement is covered by waste heat. Heat flows (condensates) leave the factory at a temperature of between 30 °C and 50 °C. The utilisation of the heat flows is subject to technical and economic limits.

Wouldn't it be possible to also obtain energy from the steam that is released into the open air at a number of points?
These are waste gases that have been mixed with a large amount of steam. The temperature of the waste gases is less than 100 °C. The condensation temperature of steam is less than 70 °C. Significant amounts of thermal energy can only be recovered below this temperature. The technical cost of such a process would be very high, however. There are therefore technical and economic limits to the use of these heat flows.

What comes out of the drying tower?
Mainly steam, which results from the drying of the exhausted slices of sugar beet.

Why does the steam from the chimney smell?
Because it contains traces of organic substances that were contained in the beet itself or have been formed during processing.