Sugar-factory centrifuge · stage 07 of 8 · schematic
One sugar beet
Point to a crystal, moisture or run-off in the centrifuge drum, then step back along the root's route until you see where it came from. The centrifuge creates nothing here.
- hexagon: sucrose crystal
- dashed outline: moisture
- dotted arrows: run-off
Without JavaScript there are no step-back buttons here. The gist stays in the text: sucrose crystals form in the vacuum pan (stage 06), and the centrifuge (stage 07) only separates them from the syrup. The full route of the three components is described in the table in the ‘Comparison’ section.
Tracing: Sugar (sucrose)
Stage 07 · Centrifuging
crystal
The crystals already exist. The drum screen holds them back while the syrup passes through the perforations. This is separation, not the formation of crystals.
The crystals formed earlier, in the vacuum pan (stage 06). This stage does not create them; it only separates or dries them.
What the machine does at this stage. A fast-spinning drum with a screen separates the crystals from the syrup. Sugar is not made anew here: the crystals already exist. The syrup still contains sugar; after further recovery, molasses remains.
The same route, three traces
Each stage shows the state of the component being traced. The three lines are three streams: the solid orange one is sugar, the dashed blue one is water, the dotted green one is the rest. The line of the selected stream is thick. The highlighted section is the route from the centrifuge to the stage you are at. Click a stage to jump to it.
Comparison: three streams side by side
This is the full explanation, with no clicking. The table also works without JavaScript; with JavaScript it highlights the stage and stream selected above.
| Stage and machine | Sugar (sucrose) | Water and steam | The rest: pulp, sediment, run-off, molasses |
|---|---|---|---|
| 01Washingwasher Water and the movement of the roots remove soil and other impurities from the surface. The cleanliness of the root changes, not its interior. |
in the cellsSucrose is dissolved in the cell sap of intact tissue. The washing water does not take it away: the sugar is in the root, but it cannot be seen. | in the tissueMost of the root's mass is its own water, inside the cells. The washing water is separate: it drains away with the impurities and is not part of the root's balance. | tissueThe rest of the root is fibrous tissue. Soil and sand come off the surface, but they are contamination, not a component of the root, so they lie outside the model's balance. |
| 02Slicingslicer The slicer cuts the washed roots into thin strips called cossettes. The shape makes the later extraction easier; slicing itself does not extract sugar. |
in the cellsStill in the cells, only in smaller pieces. The strips have a large surface through which, at the next stage, water will reach the sugar. | in the tissueThe cossettes retain the root's moisture. The water is still in the tissue. | cossettesThe tissue is cut into strips, not crushed to a pulp, so it forms a bed through which liquid can flow. |
| 03Diffusiondiffuser Hot water takes the soluble components from the cossettes. Two streams leave the diffuser: raw juice and beet pulp, that is, the extracted cossettes. |
in the juiceHot water carries sucrose from the cells into the liquid, producing raw juice. The sugar is dissolved together with other components; there are no crystals. | in the juiceThe added hot water acts as a solvent and, together with the root's water, forms the raw juice. Model A does not count this added water. | beet pulpAfter extraction the tissue leaves the diffuser as beet pulp. The dissolved non-sugars, by contrast, travel on with the sugar in the raw juice. |
| 04Juice purificationliming and carbonation Milk of lime is added to the juice, then carbon dioxide. The calcium carbonate that forms helps to capture impurities; once the sediment is removed, thin juice remains. |
in the juiceSucrose stays in the clear thin juice. It is other substances that are removed, not sucrose. There are still no crystals. | in the juiceThin juice is still mostly water. It will have to be evaporated at the next stage. | sedimentCalcium carbonate binds some of the impurities and forms a sediment, which is separated off. Some of the non-sugars remain in the juice. |
| 05Concentrationevaporators The evaporators drive off part of the water from the thin juice. The result is thick juice: the sugar is more concentrated but still dissolved. This is not yet the separation of crystals. |
in the juiceAs water is lost the sugar concentration rises, but the sucrose is still dissolved in the thick juice. Concentration does not form crystals. | steamMost of the water evaporates here, producing secondary steam, which can heat later sections of the plant. Thick juice remains. | in the juiceThe non-sugars stay in the thick juice together with the sugar: it is the water that evaporates, not they. The sediment was removed earlier. |
| 06Crystallisationvacuum pan In the vacuum pan the solution is concentrated further. Fine seed crystals that are added start the growth of crystals. The result is massecuite: crystals in thick syrup, which still have to be separated. |
crystalThe solid phase appears here: sucrose crystals grow from the seeds in a supersaturated syrup. Only part of the sugar crystallises; the rest stays in the syrup. | steamEvaporation takes place under reduced pressure, and therefore at a lower temperature. The syrup loses water and the crystals grow. | syrupSalts and colourants stay in the syrup around the crystals. Together, the crystals and syrup make up the massecuite. |
| 07Centrifugingcentrifuge A fast-spinning drum with a screen separates the crystals from the syrup. Sugar is not made anew here: the crystals already exist. The syrup still contains sugar; after further recovery, molasses remains. |
crystalThe crystals already exist. The drum screen holds them back while the syrup passes through the perforations. This is separation, not the formation of crystals. | moistureMost of the liquid drains away with the syrup. A thin film of moisture remains on the crystals. | run-offThe liquid that passes through the screen is the run-off. It contains non-sugars and uncrystallised sugar; after further recovery, molasses remains. |
| 08Drying and coolingdrying and cooling drum The separated crystals are dried and cooled, then go to storage and packing. This is where the traced route from root to dry sugar ends. |
crystalDry, free-flowing sucrose crystals. The end of the sugar's traced route. | steamWarm air carries off the remaining moisture from the surface of the crystals. | outside the sugarThe run-off and molasses have already left the centrifuge. How much of other components remains as traces in the finished sugar is not modelled on this page. |
Beet pulp is the cossettes after extraction. It can be pressed and dried; the producer in the V2 material describes its use as animal feed (American Crystal Sugar, to be checked).
Molasses is the final syrup after the crystals have been recovered. It still contains sugar and other components, so it is neither just water nor a waste product without sugar.
A broader description of the process line: ZPE, technologie stosowane w przemyśle cukrowniczym [Technologies used in the sugar industry] (a link from the V2 material, to be checked).
Option: where is the sugar you cannot see in the root
Model A divides the mass of a single root into five fractions. They always add up to the input mass. This is a teaching illustration with the assumptions below, not the result of any sugar factory.
139.4 gof sugar in crystals (at the assumed recovery)
The root contains 170.0 g of sucrose (17.0% of its mass), invisible because it is dissolved in the cell sap. In the model, 139.4 g (82%) ends up in the crystals and 30.6 g stays in the molasses.
The bar is 100% of the root's mass: 1000 g. Mass changes the grams in the table, not the shares; the shares are changed by the sucrose content and the recovery.
- Crystal sugar: 139 g (13.9%)
- Evaporated water: 665 g (66.5%)
- Beet pulp: 125 g (12.5%)
- Molasses: 61 g (6.1%)
- Sediment: 10 g (1.0%)
| Fraction | What it contains | Mass |
|---|---|---|
| Crystal sugar | Sucrose that ended up in the crystals (assumed recovery) | 139.4 g |
| Evaporated water | The root's own water removed as steam (evaporators, vacuum pan, drying) | 665.0 g |
| Beet pulp | Dry fibre (5%) and moisture (7.5% of the root's mass) | 125.0 g |
| Molasses | Uncrystallised sucrose, 60% of the non-sugars and moisture (1.5% of the root's mass) | 60.6 g |
| Sediment | 40% of the root's non-sugars (excluding the mass of added lime) | 10.0 g |
| Sum of fractions (input mass) | 1000.0 g | |
Without JavaScript the default values (A1) are shown.
- dry fibre 5.0% and non-sugars 2.5% of the root's mass; the root's own water is the remainder up to 100%;
- beet pulp carries 7.5% and molasses 1.5% of the root's mass as water; the rest of the root's own water evaporates;
- 60% of the non-sugars go to the molasses, 40% to the sediment; the pulp and sediment contain no sugar;
- omitted: water added in the diffuser, lime, CO2 and washing water.
Limits and sources
What this page does not claim
- The centrifuge diagram and pictograms are our own illustrative drawings. They are not photographs, not a plan of a plant and not to scale.
- The state words simplify: ‘in the juice’ covers raw, thin and thick juice. The turning point (e.g. 06 for the crystal) is a convenient shorthand; in a real plant crystallisation is a continuous process.
- A single root in model A does not confirm the yield of a whole sugar factory. Recovery is a parameter to be set, not a result.
- The technological content comes from the supplied V2 material. It was not verified again in an archive or online; items left for the editors to check include, for example, ‘most of the water evaporates in the evaporators’ and ‘secondary steam heats later sections’.
- Figures from V2 that cannot be justified here have been left out (diffusion temperature, the moisture percentage that causes caking).
What was removed compared with V2
- A quiz at each stage. The knowledge is now in the text and in the backward trace, without answers ‘for a grade’.
- Saving parameters in the browser (localStorage). The balance is optional; nothing needs to be remembered.
- Conversion to teaspoons and sugar cubes, and separate drawings of the eight machines.
- A remotely loaded USDA photograph. The link to the file stays in the sources, but the page works offline.
Sources
- ZPE: technologie stosowane w przemyśle cukrowniczym [Technologies used in the sugar industry] (process line)
- American Crystal Sugar: production stages and use of molasses
- Ministerstwo Rolnictwa i Rozwoju Wsi: Rynek cukru [Ministry of Agriculture and Rural Development: The sugar market] (context of cultivation)
- USDA ARS: photograph K11128-1
- Wikimedia Commons: SugarBeet.jpg (photograph from V2, not embedded here; rights status according to V2: USDA public domain, to be checked)
The links come from the V2 base material. They were not opened in this version; they are sources to be checked, not confirmation of facts.