Sugar refinery

In the production of sugar, the sugar is from plants with high sugar content (sugar beet, sugar cane ) extracted and prepared in various forms and degrees of purity consumption capable.

Beet sugar production

Cleaning and crushing

The harvested sugar beets are washed in the first sugar factory, cleaned of adhering soil particles ( clay, sand, stones) and then immediately cut to " sugar beet ".

Leaching and precipitation of insoluble impurities

Mixture is then extracted by hot water extraction tower using the counter-current process, making use of the diffusion process, the raw juice and thus removed the sucrose to 99%. The resulting black-and- blue sugar thin juice with about 14% Rohzuckergehalt still contains many other organic and inorganic substances, which must be removed prior to the crystallization process. This is done by stirring in lime which neutralizes the acids and pH raises to about 11 in order to prevent invert sugar ( splitting of sucrose into fructose and glucose). In this case, about 35% of the polluting substances can be removed, for example fall many metal ions as a sparingly soluble metal hydroxides. The space required for lime burnt lime is burned directly in the factories, as well as the resulting carbon dioxide is needed to bind the remaining calcium ions to form calcium carbonate ( lime), although other foreign substances are mitgebunden. The lime is separated from the thin juice in candle filters and filter presses. The resulting lime is usually discharged to the surrounding farmers who raise him as carbolic lime on the fields for setting the pH value of the soil.

In the diffusion process as a by- product of the leached pulp, which are pressed into pulp presses mechanically to approximately 30-34 % dry matter. The press water is pumped back into the extraction tower, the chips are thermally dried to about 90 % dry substance and then pressed with the addition of molasses into pellets. These pellets are sold as cattle feed.

Evaporation station

The purified, now clear, light yellow thin juice is concentrated in the evaporator station in a multi-stage process. The exhaust steam from the evaporator station is used at several places in the factory for heating, for example, for the raw juice after the counter-current chip mash. In addition, the pans are heated in the sugar house with exhaust steam from the evaporator station. At the exit of the evaporator station of the thick juice has a solids content of up to 70%.

Crystallization

Then from the juice ( sugar content 65-80 % ) is obtained by repeated crystallization at elevated temperature and under pressure of the sugar. As an intermediate product formed as the magma mixture of juice and granulated sugar.

Refine

In the crystallization occurs in the " cookers " a crystal suspension. The pans are heated with vapors from the evaporation plant and under vacuum to provide an energy efficient evaporation of water at low temperatures. The crystal suspension from the vacuum pans contains about 50 % sugar crystals and is separated into specific, fully automatic centrifuges from the mother liquor, washed in the centrifuge, and then dried. The grain size of the crystals can be controlled. After drying, the refined sugar is stored in most cases in an air conditioned silo to shipping.

Previously, the sugar was packed directly after crystallization into sacks and stored in warehouses. In many factories in the third world, this is still happening today in this way. Brown raw sugar is a less pure form of sugar, it is colored brown by the remaining non-sugar substances.

As a byproduct of the molasses produced by a sugar content of about 50 percent, of which no more sugar can be crystallized, because no super-saturation is present. Molasses is used in the production of yeast, in the food industry, the pharmaceutical industry and in the production of rum. In addition, molasses is used as a "press aid with nutrient content " in the production of feed.

To improve the yield of the crystallization, the molasses is further processed. One of the most cost-effective method for this is the Quentin process. Here the molasses is treated with a cation exchanger which is loaded with magnesium ions. The sodium and potassium salts of the molasses are converted by ester interchange in magnesium salts. The crystallization rate, and thus the yield of sugar is increased thereby.

Sugar cane production

The harvested sugar cane is cut in the factory or with the crop. In most factories the cane is processed into sugar mills. In the mills, the juice is squeezed from the cane ( " press extraction " ), as residual material produced bagasse. In some factories, however, are already in use diffusers, extract the sugar by means of the diffusion process. The juice is fed to weanling. There are removed from the juice by gravity suspended solids. This simple type of juice purification is responsible for ensuring that cane sugar is often brown.

For a trip report of the mission doctor Dan Beach Bradley in 1840 we learn about the sugar production in Siam near the former Nakhon Chaisi:

" ... A single sugar factory had between 60 and 80 water buffalo, which grind the pipe, about 50 to 80 cords [1 cord = 3.62 m³ 's note Üb ] wood to heat the juice and between 100 and 150 workers for the various activities. "

The production of sugar cane juice runs after cleaning essentially the same as in the beet sugar production.

Energy in the sugar manufacturing

Sugar factories use in a rule, the combined heat and power:

In steam boilers, water is evaporated. The steam generated is conducted through a turbine, to which a generator is connected. The generated electricity is used for the electric motors present in the factory, for example, the pumps, the centrifuge, etc.

After the steam has passed through the turbine, it is used in the evaporation plant, to thicken the juice. The steam is used in several ways: In the first stage of the evaporation plant is caused by the evaporation vapors. The vapors from the first stage is used as heating steam for the second stage of the evaporation plant and so on. In modern beet sugar factories are up to eight- Verdampfstationen in use. Thus, the steam is used very efficiently.

The steam is also used for the crystallization and the warming of fluids. In modern beet sugar factories, the conservation of thermal energy in the past 20 years has been greatly advanced, because as a fuel are coal, gas or oil in use. In cane sugar factories, however, is the bagasse, ie the fibrous portion of the sugar cane, used as fuel. Since the other possibilities of the use of bagasse are limited (eg for the production of particle board ), the compulsion to save energy in most countries, sugar cane is currently not very pronounced.

Increasingly, however, use the factories excess bagasse to generate electricity for the national grid.

Automation in the sugar industry

As in many other industries, the automation has been greatly advanced in recent decades in sugar production. The production process is generally centrally controlled by process control systems, which control most of the machines and plant components directly. Only for certain special applications such as The centrifuges are used for safety programmable controllers.

Historical production of sugar

In emerging countries sugar is often still won with the steam drive technology of the early 20th century. On the main island of Indonesia, Java, in the regions of Central Java, Central Java and East Java are still about 50 sugar mills in operation, some of which are over 100 years old. Also on the Caribbean island of Cuba are still such old sugar mills in operation, but also dimensioned slightly larger.

Sugar from sugar beets was first produced in 1802 by the German scientist Franz Karl Achard in a (pre-) industrial processes. Through the Continental System of Napoleon in the early 19th century, the import of sugar to Western and Central Europe has been denied. The industrial production of sugar from sugar beets was now of great importance to compensate for this loss of imports. A result, the introduction of this new method has been greatly accelerated in the practice. 1813 for example, presented her already 23 companies in the lower Rhine beet sugar.

Environmental problems of sugar factories

Sugar factories have previously charged by inadequate sewage treatment waters with large amounts of organic material. Precisely the efforts to an ever more efficient use of the available quantities of beet but have resulted in ever larger proportions of the constituent sugars contained in the volumes of water used could be applied to a use yet, at the same time reduced for reasons of cost in modern facilities more and more, the use of fresh water, which also leads to a reduction in the amounts of waste water.

The problem, however, remains at sites in less developed countries, where there protecting the environment and the cost of water and material less attention.