The massecuite circulates in a loop within the evaporating crystallizing vessel. The massecuite flows upwards through the heating tubes. In the room above the calandria the massecuite flow changes its direction to radial inwards and then to vertical downwards. An impeller in the central tube forces the circulation. Below the calandria the main direction of flow is radially outwards until threads of the massecuite stream enter the heating tubes in upwards direction. Within the tubes heat is transferred to the massecuite. At low temperature differences between heating steam and massecuite and higher levels of the massecuite in the crystallizer vapor bubbles are not found in the tubes. Vapor bubbles can be formed at a massecuite level in the crystallizer where the temperature of the massecuite is higher than the local boiling temperature of water, which depends on the local pressure (including the static pressure of the massecuite at this point) and the boiling point elevation of the mother liquor. The surface tension of the liquid is a resistance against the bubble formation, which has to be overcome by the local superheating i.e. the part of the enthalpy of the massecuite exceeding the local boiling temperature. The formation and the flow of the bubbles change the density of the massecuite/bubbles mixture and has an influence on the massecuite flow. The formation of a vapour bubble is connected with a local drop of the massecuite temperature which changes the local supersaturation. Today the heat transfer into the magma is quite well known but the process of bubble formation is quite unknown. Some basic considerations about the formation of bubbles and its influence on local supersaturation based on calculation of heat and mass balances and models of bubble formation are be given and discussed. Experiments for basic investigations are proposed.

Biotechnological production of lactic acid has been studied in various ways, e.g. microorganisms, fermentation processes, down-stream processes, fermentation substrates, and fermentation nutrients. The problems for all processes still are high costs for feedstock and fermentation nutrients. The objective of this study is a general evaluation of sugar beet thick juice from Pfeifer & Langen GmbH & Co. KG, Germany as a substrate for lactic acid production. In a series of fermentation experiments the results based on thick juice were comparable to those obtained using cane raw sugar and even better than using conventional corn starch as a fermentation subtrate. The most important findings for a later technical application are the high volumetric productivity (up to 5.5g·L–1·h–1), and the optical purity of the lactic acid (>99% ee l-LA).

The formation of color during evaporation is influenced by the operation of juice purification, by the laws of physics and chemistry, the design and layout and by the operation of the evaporator station. The influence of the residence time, the residence time distribution, pH value and the temperatures is shown. In a short overview the influence of the juice constituents are explained. Some positive and negative experiences from the operation of the evaporator station are reported and their influence on the formation of color is discussed. By using a short checklist for troubleshooting in the case of color formation during evaporation examples of good practice during the beet processing steps are explained.

The paper is based on the results of international project entitled "Towards Sustainable Sugar Industry in Europe (TOSSIE)". 33 research topics of major importance to the sugar sector are listed and briefly described, and compared with research priorities of the European Technology Platforms: "Food for Life", "Sustainable Chemistry", "Biofuels", and "Plant for the Future". Most topics are compatible with the research themes included in the COOPERATION part of the 7(th) Framework Program of the EU (2007-2013). However, some topics may require long-term R&D with the time horizon of up to 15 years. The list of topics is divided into four parts: Sugar manufacturing, Applications of biotechnology and biorefinery processing, Sugarbeet breeding and growing, Horizontal issues. Apart from possible use of the list by policy- and decision makers with an interest in sugarbeet sector, the description of each research topic can be used as a starting point in setting up a research project or other R&D activities.

Vapor compressors are heat pumps used for evaporation processes. They can either be driven mechanically or by high pressure steam. The oldest installation of a vapor compressor in a sugar factory is still working in Aarberg, Switzerland. In the 1980s several sugar factories in France installed vapor compressors for recompression of crystallization vapors. A literature survey of these installations is given. Operation parameters of vapor compressors are explained and the possibilities of integrating these apparatus into sugar factories, especially under the conditions of a thick juice campaign, are discussed. A special attention is given to a so called vapor fans which have a lower pressure ratio performance than compressors but might be more economic.

For decades the impellers in evaporating crystallizers (vacuum pans) have been installed within the central draft tube of the calandria. The axial flow impellers - so called "Kaplan type" - are nowadays the standard impellers in evaporating crystallizers. In comparison with this standard type the performance of radial flow impellers installed below the heating chambers of two evaporating crystallizers at the Goslawice sugar factory was investigated during the 2004 campaign. The two evaporating crystallizers were operated continuously as the 3rd as well as the 2nd stage of B (raw sugar) and C (after product sugar) cascade crystallizers. The investigations included running each impeller at three different values of the rotational speed and measuring the power consumption of the agitator drive while determining the heat transfer coefficient in the respective evaporating crystallizer. In a similar manner, the performance of standard Kaplan impellers installed in the central tubes of the heating chambers of both evaporating crystallizers was investigated. In relation to Kaplan impellers, the radial flow impellers made it possible to attain markedly higher heat transfer coefficients at lower values of the rotational speed. By comparing their power consumption at similar levels of the heat transfer intensity, a comparison between the two impeller types with respect to the circulating efficiency was also made. In B3 evaporating crystallizer, the circulating efficiency of the radial flow impeller was higher than that of the Kaplan impeller by a factor of 2.8. In C2 evaporating crystallizer, the corresponding factor was 2.6.

Crop conditions - beet area - beet yield - sugar content - sugar yield - alpha-amino nitrogen content - technological data - length of campaign - energy consumption - color increase in the evaporator plant - boiler cleaning - capital investments - operating data collection - control room - preliminary screening - combined heat and power plant - industrial safety.

The tranport phenomena occuring at the solid-liquid separation in batch centrifugals are described. Problem which arise in centrifugal operation depend on the particle size distribution of the crystal suspension. The mean diameter and the wideness of the distribution determine the flow behavior of sugar crystal suspensions, too. In a tube viscosimeter deviations from Newtonian flow behavior were measured. The deviations that might concern a dependency on time or on shearing force were negligible but a so-called wall-slip was determined. That means the sugar crystal suspension is sliding on a film through the tube. This plug flow is super imposed by the normal parabolic velocity profile of a laminar flowing fluid. For separation in the centrifugal the permeability of the filter cake is the determining. This is influenced by interactions between crystal and the surrounding solutions. The solution is discharged through the void fraction of the particles. The resistance in the void fraction is determined by the mean diameter and the wideness of the crystal size distribution. Model calculations show that crystal size distributions which contain false grain have a significantly lower permeability than good crystal size distributions. The crystal yield of the centrifugal and the total performance of the centrifugal is determined by the quality of the crystal size distribution which is the result of thermal operation of crystallization.

In 2002, conditions for the infestation of beets with Rhizoctonia were particularly suitable in the Rhineland area. At the beginning of the campaign many black (rotten) beet had been delivered. Analysis of beet at different stages of decomposition showed serious changes in the constituents: In the last stage of rotting sucrose is converted into dextran. The agricultural procedures for sorting out the rotten beet are described. In two test series, sugarbeet were processed in the laboratory from raw juice to thick juice. In each series about 30 kg of sound and affected beet were processed. The juices from Rhizoctonia-affected beets had worse filtration characteristics, the juice hardness was higher and they needed more soda for alkalization. Additionally the thick juice colors were significantly higher and the estimated sugar losses molasses were also higher. Because the components which are used in the formula for the estimation the amount of "molasses sugar" are nearly equal the amount of molasses is underestimated in affected beet by the Braunschweig formula. The counter measures must be taken on the agricultural side: The occurrence of Rhizoctonia should be minimized and the severely affected beets should be sorted out before delivery.

Crop conditions - beet area - beet yield - sugar content - sugar yield - a-amino nitrogen content - technological data - length of campaign - energy consumption - beets affected by rhizoctonia juice purification - lime consumption - capital investments screening installation - block heating plant - mechanical beet soil dewatering - leaf press - pulp presses - industrial safety.

An obvious advantage of continuous evaporating crystallizers with stirring systems is the possibility to operate at very low temperature differences. This enables the design of equipment for a crystallization scheme providing a double-effect evaporation: The vapour from the evaporating crystallizers for raw sugar and after-product is the heating medium for the white sugar evaporating crystallizer. Model calculations are introduced and the consequences of such lay-outs for the evaporating station and the power plant of a sugar factory are described. Accordingly, the sole production of white sugar of EEC quality 2 results in operational steam requirements of 15.3 kg/100 kg beet.Just in time for the 1994 beet campaign such lay-outs and equipment for a crystallization with double-effect evaporation have been installed in the sugar factories of Gustrow and Klein Wanzleben. Gustrow sugar factory has already started operation during the 1994 beet campaign. The report gives a survey of the operating conditions and results.

The report is based on a co-operation of ZVM Klein Wanzleben sugar factory with the Braunschweig Sugar Institute and Siemens. At Klein Wanzleben sugar factory a computer system including the software tools NAHMAT-CIS by Siemens was installed in order to supply the factory's management with specific information about the process conditions. This information system is superior to the process control system. It offers the possibility to realize balances of mass flows, material flows and energy flows by combining data from the process control system with data from the laboratory record to new information.One part of the system is the balance of the evaporation crystallization. The programme for the evaporation crystallization tower (VKT) for the products white sugar, raw sugar and after-product calculates balances of mass flows, material flows and energy flows for the entire apparatus and for each chamber. The documentation by means of trends illustrates the performance drop of the apparatus caused by incrustrations. The second part of the programme com piles the input and output flows of the factory as a whole and of the main balance areas: beet processing, power station, drying, extraction, juice purification, evaporation crystallization with capacity control, and condensation. An extension of the system will also cover data from subordinated balance areas.

Evaporation drying in a fluidized bed is a novel system of pulp drying in sugar industry, contrary to the hot gas drying in drum driers. This new system has been installed in several sugar factories in eastern parts of Germany. The Braunschweig Sugar Institute has conducted performance tests and basic research on this new drier type.The performance tests covered both the operations with full load and with partial load. The operation with partial load could only insufficiently reduce the steam superheating due to the low level of pulp. An extended retention time of the pulp might improve the utilization of heating energy of the turbine bled steam. However, the quality of the product ''pulp'', which is sensitive to heat, has to be considered.Topics of the basic research are drying rates, drying periods and sorption isobars for the evaporation drying of beet pulp. Pulp samples taken from several cells of the drier were analized concerning their dry substance content. These values were compared with the course of the dry substance content supplied by an enthalpy balance for the circulating steam inside the separate cells.Further studies will concentrate on the determination of the equilibrium moisture of pulp depending on parameters of the superheated drying steam.