Improved energy efficiency in the sugar house.
The energy input in the sugar house has a crucial influence on the energy demand for sugar production in the beet sugar factory. In view of the changing political and economic boundary conditions, concepts to increase the energy efficiency in the sugar house are being discussed. It suggests itself here to minimize the quantity of water to be evaporated in the sugar house area. There are also interesting concepts featuring continuous crystallization and mechanical vapor compression. Such considerations are geared to increasingly utilize renewable electric energy instead of thermal energy which today mainly comes from fossil fuels. In times of increasing energy costs, a low specific energy demand represents an economic advantage for beet sugar factories. The politically induced reduction of the use of fossil fuels also for sugar production boosts the discussion of feasible and necessary adaptations in the sugar production process. This paper focuses on the energy demand of the sugar house, which bleeds the largest part of vapor from the evaporators. Conventional and new concepts to minimize the energy demand required for crystallization and the separation of crystals and syrup will be presented. They will be discussed in the light of the new boundary conditions. Decisive quantities for the steam demand include the water intake from thick juice and the demand for melting B and C sugar, as well as the quantity of wash water used at the centrifugal machines. For several decades, various crystallization concepts have been applied to achieve an automatized and to a large extent reproducible crystallization process. Depending on the desired crystal size, one-stage or two-stage crystal seeding processes are often applied, which primarily serve to ensure a feed solution with maximum dry substance content. In this way, the process design allows for minimizing the water intake and thus the steam demand. The application of continuous crystallization plays a crucial role, especially in concepts that include mechanical vapor compressors. Here, the thermal energy supply (steam) to the sugar huse can be reduced by means of electric energy usage.