Suchergebnisse

The processing of sugar beet, in particularly the purification of the extracted raw juice, can be significantly hindered by the presence of polysaccharides like pectin and dextran in the extracted juice. The origin of these polysaccharides in beet processing, as well as how their presence in the raw juice affects processing will be explained. Preventive and process control measures can be applied in order to largely limit the risk that the content of these polysaccharides gets at a level where they adversely affect beet processing.

The initial thin juice pH value usually changes during juice evaporation. As long as the pH value of the final thick juice differs maximal ±0.5 pH units, preferably ±0.2 pH units, from that of thin juice, the thin juice is considered thermostable. The observed change of the juice pH value depends on the ratio between dissolved ammonia and carbon dioxide in thin juice. During the juice concentration both volatile components will evaporate at which they have opposite effects with respect to the pH value change. Ammonia is dissolved as ammonium ion in the juice and leaves a proton in the juice upon evaporation, whereas carbon dioxide is dissolved mainly as bicarbonate and delivers alkali upon evaporation.

This paper explains why a thermostable thin juice is crucial for the effectiveness of the following process steps evaporation and crystallization. Details about the origin of ammonia and carbon dioxide will be presented, as well as possible ways to control the thin juice thermostability by influencing the ammonia to carbon dioxide ratio.

Removal of the insoluble solids from the carbonatation juices in juice purification is often the bottle-neck in the beet slicing capacity of a beet sugar factory. It is crucial to produce good filterable precipitates in the different steps of juice purification, which in fact depends on the achieved particle size and particle size distribution of the formed precipitates. The principle of filtration will be described wherein permeability and thickness of the filter cake, as well as the juice viscosity are the most important parameters.
The most likely causes of problems in the filtration of the 1st carbonatation, respectively 2nd carbonatation slurry will be presented. In addition, recommendations are given on how filtration problems can be solved. Some alternative ways of processing in order to get around particular filtration problems will be mentioned too.

The raw juice as obtained by juice extraction of sugar beet cossettes contains dissolved and insoluble impurities (nonsugars) which need to be removed as much as possible to enable a cost-effective production of the wanted quality of white crystal sugar. The most commonly used purification approach of beet raw juice is the so-called classical liming process. The aim and principles of the different successive process steps in juice purification will be outlined in this paper. The purification principles comprise several chemical-physical reactions of particular nonsugars in the juice which are initiated at first by the addition of milk of lime to the raw juice in preliming and main liming. Through injection of the carbon dioxide produced in the lime kiln in the 1st carbonatation calcium ions precipitate as calcium carbonate, which is then used as filter aid to remove by sedimentation and/or filtration the formed slurry. The remaining surplus of lime salts are finally removed in the 2nd carbonatation which after filtration results in a clear thin juice.

The stability of the sucrose molecule and the firmness of the tissue structure in the cossettes are of major concern when optimizing the operating conditions for the extraction system. For a given extraction system the retention time is more or less fixed, but the actual pH values and temperatures to be set across the system largely determine the extent to which both sugar gets lost by hydrolysis and the cossette structure deteriorates, particularly by dissolution of pectin. Furthermore, potential sugar loss by microbial infection in the extraction system needs to be controlled too. The influence of the pH value and temperature on these undesirable chemical and microbial reactions will be outlined in this paper, including the consequences for the subsequent processing steps. It can be concluded that the recommended optimal pH values and temperatures for operating the extraction system are a compromise between good and bad.

The beet sugar industry is facing several challenges for the future. The climate change is requiring a transition from the traditional fossil fuel to a greenhouse gas neutral energy source. The available possibilities for this purpose will be outlined in this paper. The recent EU sugar market reform has markedly increased the competition between sugar companies and the resulting lower sugar price has a significant impact on the profit margin of sugar production. In order to keep up with these challenges it is key to make an appropriate use of the available opportunities to improve the cost-efficiency of sugar beet processing. The different means to advance the sugar business are better asset utilization, continuous process improvement, introducing innovative process technologies and further developing a sugar factory into a biorefinery with a further valorisation of (co-)products and wherein synergy is obtained between different on-site process operations. Why and how these different available tools can improve the competitiveness of sugar factories will be discussed in detail. A proper combination and choice of the suggested changes and opportunities will enable sugar factories to get prepared for the future.

Each sugar factory needs appropriate guidance to produce the desired white sugar product and co-products in their installed process equipment from the received sugar beet in a cost-effective way. Based on the generally known principles of sugar technology and supported by the extensive experience in beet sugar processing, this paper provides an overview of important key performance indicators (KPIs) which a factory could use as targets to optimize their beet processing. The recommended technological process set-points, which are required to fulfil the defined KPI targets, will be covered too. The theoretical background of sugar process technology is at the basis for the determination of the recommended process control parameters and will be used to explain the preferred choices of KPIs and process set-points.

This paper describes the different methodologies which can be used to deal with the technological impact of deteriorated beet on processing. The procedure developed by EU sugar beet research institutes to protect long-term stored beet against the outside weather conditions is considered a necessary preventive measure to limit beet deterioration. In addition, a wide range of process measures is available to handle incoming deteriorated beet material in beet sugar manufacture. The specific dextran processing problems associated with frost-damaged beet cannot normally be solved by the usual process measures and require the addition of the rather expensive enzyme dextranase. A few alternative processes which could either improve or even enable the processing of deteriorated beet are briefly discussed. The financial consequences of processing deteriorated beet on the manufacturing costs of white sugar are outlined. Finally, the point is explained at which processing of very badly affected beet is supposed to be technologically as well as economically unacceptable.