The core competencies of Pruess GmbH include the construction and commissioning of extraction plants and, where required, their qualification. The extraction plants in the food or pharmaceutical industry are mainly used for the extraction of a desired component from plant-based ingredients.
The variety of extraction plants that our engineers have been able to install so far ranges from the 50-litre pilot plant to industrial plants which are several cubic metres in size. Whether it is continuous or batch extraction, single-stage or multi-stage, we design each plant optimally and always take your ideas and requirements as well as the characteristics of the selected bio-materials into account.
Areas of Use of the Extraction
Extraction is the term used for separation processes in which one or several components are extracted from a mixture of substances or bio-material with the addition of a solvent. The end-product is a solution of the desired compound, such as oleoresins, colourings, flavourings or active ingredients. This extract can be processed further. In this context, a concentration by means of an evaporation plant which we can also design, and build is usual.
Alternatively, the extraction process is used to remove an undesired component from a solid such as tea, as is the case with decaffeination.
Depending on the proportion and solubility of the component to be extracted as well as the nature and quantity of the solid, different extractors are required. The most common forms are continuous and batch extraction.
In the case of batch extraction, the extractor is loaded with the raw product in several batches. Depending on the number of extractors, the extraction is carried out in a single- or multi-step procedure. According to the configuration of the procedure, the maceration can take place in a constant flow, in a counter-flow or on a simple basis.
The advantage of batch extraction lies in the lower costs of the plant. More personnel are required for the operations, however.
The decision on which system is better to use depends on several factors and must be considered individually for each application.
Pruess Extraction Plants
The batch extraction plants and extractors of Pruess GmbH are optimized for the highest functionality and consistently adapted to the respective application. On the one hand, the economic operation of the plants while achieving the best possible yield in the respective extraction process is guaranteed by the process which is adapted to the product, and on the other hand, by the automated, and therefore reproducible, process sequence.
The intelligent pipework in particular allows for the individual operation of the batch plants, which can also be easily adapted to other extraction parameters, such as the temperature and the solvent.
All Pruess extraction plants can be operated in different modes, i.e. either single-stage or multiple-stage and with or without the recirculation of the miscella. Their easy to clean and sterilization-capable design allows for a permanently hygienically flawless use of the extraction plants.
Last but not least, another advantage of the batch plants of the company Pruess is their qualification-capable design.
The growing necessity to process bigger quantities of the same raw product, such as tea or soya for example, has led to the development of continuous extraction plants. In recent decades, these plants, which are frequently used in the extraction of soya oil, have achieved a high degree of perfection and efficiency.
In fields with smaller volumes, it can also make sense to use continuous systems rather than batch designers. Depending on the costs of products, reagents and personnel, a continuous solution from 50 to 100 cubic meters per day can be considered. In this respect, the design of the extractor is essentially determined by the properties of the product to be extracted. It is naturally the case that the character and processing method of the raw product naturally have a major impact on the output and yield of any extraction plant.
The experts at Pruess GmbH will be pleased to assist you in deciding whether a batch or a continuous system is the more suitable solution for your particular application.
The Pruess Ring Extractor
These days, in continuous extraction plants, the vast majority of raw materials to be processed are extracted according to the percolation principle. The Pruess Ring Extractor also works according to this proven principle, with which most consumers are probably familiar from filter coffee. Its advantages include its compact, sophisticated and closed design, its limited requirement for space, as well as its ease of use, flexible mode of operation and last but not least, the easy cleaning of the extractor.
The Pruess Ring Extractor consists of a single unit rotor, the annular space of which is divided into cells by radial partition walls. Each cell is equipped with a bottom that folds away downwards and which caters for quiet pouring during the extraction process. The extracting agent percolates through the extraction material layer, accumulates with the components to be extracted, is simultaneously subject to self-filtration, passes through the screen tray, collects in chambers separated by weirs in the lower part of the extractor and is pumped upwards again onto the extraction layer of the next cell (counter-current principle). At the end of the cycle, supported in the case of some products by an additional pneumatically-operated forced emptying system, the extraction residue falls into a discharge chute through the automatic opening of the screen tray flap, and is continuously discharged by a screw conveyor.
Before a change of product, built-in washing nozzles clean the individual cells and screen tray flaps from adhering extraction residue. The base of the extractor is designed in such a way that no residue remains left behind. This means that different products can be processed in the plant in alternating order without the cleaning work leading to considerable downtimes.