Beer clarification - Use of centrifugal separators and decanter centrifuges in the production of beer

Centrimax supplies used, factory-rebuilt, refurbished centrifugal separators and decanter centrifuges from manufacturers such as GEA Westfalia Separator, Alfa Laval and Flottweg for the brewing industry. During a complete general overhaul service, these beer centrifuges are supplied with new control systems (Siemens S7) and thus, can be easily integrated into the production. After a successful test run, our separators and decanters are shipped out including a warranty for all mechanical parts.

Centrifugal separation technology

Centrifugal separators and decanter centrifuges have been the main machines in the manufacture of beer for decades. In the decisive steps of the process, they ensure economical operation and a high quality of beer. Following numerous solutions for the use of centrifugal separators and decanter centrifuges in breweries are presented as examples.

Self-cleaning centrifugal separators

Self-cleaning centrifugal separators can be optimally integrated in the operative processes of breweries. The solids separated in the separator bowl are ejected periodically from the bowl. Because this occurs at operating speed, a fully continuous operation is ensured. The advantages are separation of the finest solid particles possible by the increased centrifugal acceleration, substantial reduction of costs for filter aid, reduced use of kieselguhr filtration and improved taste of the beer by separation of unlike protein complexes and sensory stability.

Hot wort separator

During boiling the wort, the hot trub is precipitated. The hot wort filtration is inefficient. Centrifugal separators are more efficient and environmentally friendlier. The application of the whirlpool and centrifuge for clarification of the wort also meets the needs of the users for a continuous mode of operation and greater economy. The clarifier can be installed either direct after the wort kettle or the intermediate wort receiver. Which of these is the best solution depends on several factors and should be determined for the individual application. For example, hot wort holding times (isomerisation of the hops, coloration etc.) must be maintained and not exceeded.

Trub wort separator

The whirlpool is employed especially to clarify the entire hot wort. Because it is not always possible to achieve a good separation of the trub due to the fluctuating quality of raw materials and different types of beer, the separator is an appropriate supplement. The trub cone produced often collapses when the wort is drained. This phenomenon causes the residual turbidity of the clarified wort to be too high and/or the losses to be very high due to the inadequate thickening of the trub. Whilst the wort is rotating in the whirlpool, the separating process can begin from the bottom. The recovered wort is then cooled.

Cold wort separator

Some breweries clarify also the cold wort. The hot trub is already separated before cooling. The clarifier therefore separates only the remaining quantity of cold trub. The cold trub consists largely of small, colloidal protein particles. The viscosity of the cold wort is relatively high. Cold wort separation has differing significance in the individual breweries. A certain quantity of cold break is desired in the fermentation process, but no hot trub must be carried over under any circumstances.

Green beer separator

The high cell count of e.g. 70 million yeast cells/ml in the main fermentation is not desired in subsequent storage. Traditionally, green beer is clarified by sedimentation of the yeast and other turbid substances. The beer is then transferred with as little yeast and sediment as possible. To obtain a controlled, rapid secondary fermentation and maturing of the beer in storage, it is appropriate to transfer with a defined number of living yeast cells. This can be achieved by using a centrifugal separator. The yeast is fed into a collecting tank or the beer recovery process and the green beer is separated. The optimum process for beer recovery is the addition of the surplus yeast and the tank bottoms in a separator during the clarification of the green beer. The advantage is the consistent product quality.

Clarification of beer prior to kieselguhr filtration

Frequently the beers fed to filtration still contain large quantities of yeast, making kieselguhr filtration difficult. Kieselguhr filtration itself is not problem-free. Means are available either to replace the kieselguhr filtration or at least to reduce the consumption of kieselguhr. By employing a separator to pre-clarify the beer, the required degree of filtering can be drastically reduced. The result is not only a reduction of a filter aid, but also an increased period of operation. Of course, the centrifuges are also suitable for pre-clarifying with other filter systems.

Beer recovery from surplus yeast and tank bottoms

Varying amounts of yeast and tank bottoms are produced, depending fermentation and storage of beer. In most cases, a substantial proportion of beer is still contained which must be recovered in economically managed processes. This improves their cost-effectiveness without changing the beer quality. Indeed, the yeast and tank bottom volume accounts for approximately 4 percent of total annual output, and of this figure approximately 60% can be recovered in the form of beer. In a brewery with an output of one million hectoliters, this corresponds to a volume of 24,000 hectoliters.

Decanter centrifuges in breweries for trub wort separation or beer recovery from surplus yeast

Decanter centrifuges are solids oriented industrial centrifuges with a solid-wall bowl. A conveyor screw conveys the solids to the outlet, through which they are continuously discharged. Decanter centrifuges are used mainly for clarification of liquids with high solids content. Fluctuating solids content in the feed product has little effect on the degree of clarification or separation.

Decanter centrifuges and polisher

It is possible to further improve beer recovery by means of a decanter by combining a decanter centrifuge and centrifugal separator or connecting a decanter centrifuge and centrifugal separator in series. The yeast is initially concentrated by the decanter to a maximum dry matter of 25 to 28%, thus achieving an optimum yield. The beer which is recovered from the decanter centrifuge is then processed further in a small polisher from around 1 million cells per milliliter to fewer than 1000 cells per milliliter. The beer which is treated in this way is solids-free.

Turbidity adjustment with centrifugal separators

Particularly in the manufacture of German “Hefeweizenbier“(wheat beer), it is important to present the customer a product with a consistent quality of the turbidity. Problems occur particularly in high storage tanks because the yeast concentration varies due to sedimentation. The use of centrifugal separators is suitable in this case to compensate the concentration. The stored beer is separated. Simultaneously, unseparated beer is added through a bypass to ensure constant turbidity values throughout the entire production cycle. For this purpose, the turbidity is measured at the outlet of the centrifugal separator and after mixing. The control valve in the bypass pipe is then controlled by these two values and the nominal value.

Beer recovery with nozzle separators produces clear beer

The design of these centrifugal separators makes them so powerful that they can process the relevant yeast and tank bottom volumes with relatively low machine costs. This results in amortization periods which were previously unthought-of with new machines in this special application area. The nozzle separator processes the yeast which is additionally internally diluted with water. This makes it suitable also for small or medium-sized breweries depending on the yeast economy. In addition to the nozzle separator, a yeast collecting tank is required where the yeast or tank bottoms are stored homogenously. In the tank, the yeast, possibly with already degassed water, is set to the original wort value or mixed “inline” on the way to the separator. The separator then continuously separates this supply into a flow with yeast of around 80 percent by volume. Using this technological trick of “washing out yeast“, a nozzle separator can achieve extract yields of 90 percent. The recovered extract is likewise diluted in this case. This makes the nozzle separator process particularly suitable for “high gravity“ brewing since the recovered extract is ideal for cutting the original beer to the desired strength for sale.

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