Extraction Plants
The edible oil technology division at Harburg-Freudenberger develops and produces:
- oil mills or plant units, i.e. for refining,
- apparatus and machines for continuous solid/liquid extraction of oil seeds,
- apparatus and machines for mechanical and thermal process engineering according to proven and tested processes,
- engineering services, including installation and commissioning.
Benefit from our comprehensive experience. Our range of services includes:
- delivery of machines and apparatus for your facilities, from discharge systems for raw materials via meal and crude oil extraction as well as refining to filling and packaging of finished products,
- extensive experience with more than 400 facilities featuring capacities ranging between 50 and 4,000 tons/day,
- tate-of-the-art processes and components.
We offer optimal solutions including supervision of installation and commissioning.
Structure of a continuous solvent extraction
In addition to pressing, the extraction of oils with solvents is the most frequently applied industrial process for extracting edible oils. Significant benefits of solvent extraction are: high yields, reduction and prevention of protein denaturation as well as separability of valuable oil components such as lecithin.
The raw material to be processed (in particular its fat content), the planned throughput, intended application of semi-finished and finished products, as well as economic aspects determine whether processing through
- plain/pure pressing (full pressing),
- combined process including pre-pressing and subsequent extraction,
- or direct extraction without prior pressing is most suitable.
Depending on the unit design approx. 100 to several thousands tons of oleaginous seeds or fruits can be processed daily. For oil extraction on an industrial scale numerous materials are extracted using solvents including soybeans, sunflower seeds, rapeseed, cotton seed, palm kernels, copra, peanuts as well as wheat germs, olive pulp or corn germs, to name but a few.
Due to our extensive experience and the wide range of application of the solvent extraction process used for the extraction or removal of fats we are your reliable and professional partner.
Our employees will support you in planning, design and implementation of solvent extraction machines and apparatus.
Diagram of the standard solvent extraction facility including all components
Carousel extractor
The carousel extractor is the heart of every extraction facility and is characterised by:
- an optimal effective volume/total volume ratio by applying the carousel principle,
- compact cylindrical design,
- optional subsequent improvement of performance by adding further unit levels,
- shop-assembly for performances up to 4,000 t/24 h,
- ease-of-maintenance due to minimum wear parts,
- high operational safety due to minimum of moveable parts,
- high throughput with minor surface floor space,
- extraction material sliding above the stationary sieve bottom enables self-cleaning,
- high drive redundancy preventing extractor impairment in case one or two external drive units fail.
The carousel extractor is a continuous percolation apparatus with cross-flow/countercurrent operation. In percolation the extraction material is leached with solvents or miscella in varying concentrations in the individual extraction stages and the oil is removed.
By continuously adding solvents and discharging rich miscella, a constant liquid stream is generated running counter-currently with the solid material flow.
This countercurrent is superimposed on the cross-flow current in the individual extraction stages. In this process the miscella is recirculated via the solid material bed within the respective processing stage according to the percolation rate of the crude material.
At the end of the extraction process the solvent is fed to solid material already extracted to displace the miscella still contained in the solid material. Before the rich miscella is removed from the extractor it is filtered through the solid material bed. The solid material extracted is then passed through a draining zone where most of the bound solvent is drained off resulting in considerable energy savings in the subsequent desolventizing process.
Subsequent processing of the extracted meal from the extractor
Individual or integrated processing steps:
- Pre-desolventizing
- Desolventizing
- Toasting
- Drying and cooling
Material separated from fat in the extractor requires subsequent treatment. The solvent contained in the material must be recovered and thermal treatment increase the feed material quality (increase of digestibility by removing indigestive materials and eliminate contaminants). For meal storage the material must be dried and cooled.
Our technologies comprise the following steps:
Pre-desolventizing
Partial separation of solvents by heat supply via indirectly heated surfaces resulting in higher efficiency of the plant.
Desolventizing (Schumacher Licence)
Removal of the solvent to a few 100 ppm during steam distillation. Systematic vapour control enables low steam consumption.
Toasting
Hydrothermal meal processing (cooking process).
Drying
Removal of the excess water by pre-heated air utilising the meal's heat potential.
Cooling
Final cooling of the material by cooling air and partial water evaporation.
The benefits of these concepts are:
- All process steps integrated in one apparatus; hence conveying elements for the individual processing stages are not required.
- Decreasing the overall steam consumption with an upstream pre-desolventizing stage and controlled adjustment of material moisture - in particular for seeds with high initial moisture, i.e. soybeans.
- Further decrease of steam consumption by applying heat recuperation systems for utilizing the heat energy contained in the exhaust air.
- Savings in building expenses due to compact and space-saving design.
- High operational safety and reliable availability of the installation
Upon request, we supply any apparatus combination for further processing steps according to customer requirements, i.e. horizontal pre-desolventizers and additional drying and cooling systems.
"P-D-T-D-C"
Pre-desolventizer - Desolventizer - Toaster - Dryer - Cooler
The unit consists of a heated, cylindrical housing containing a number of heated trays with passage openings. Agitating arms stir the meal on the trays which runs uniformly through the unit from top to bottom. In the desolventizer/toaster section it is then subjected to an intensive countercurrent flow of steam. The solvent can be reduced considerably through this energy-saving operation.
At the end of the process the meal is processed hydrothermally to improve digestibility and to extensively eliminate indigestive or harmful substances. The drying and cooling zone is equipped with air distributing trays. Hot and cold air is drawn or pressed through the meal bed removing moisture and heat and simultaneously fluidizing the meal bed. Significant benefits of this combination compared with traditional separate processing steps are:
- Low initial costs as only one apparatus is required instead of three or four units.
- Conveying elements for meal transport between the individual processing steps are no longer required.
- Low steam consumption for drying by utilizing latent heat in the meal as well as by partial removal of solvents during the pre-desolventizing stage.
Flash Desolventizing System (FDS)
As a result of the global lack of animal proteins, protein production from extraction meal is gaining in importance. The flash desolventizing system is a flexible process to create soy flakes in the form of "white flakes" serving as raw material for the production of protein. This plant enables adjustment of the water-soluble protein proportion according to market and customer requirements.
In a spontaneous evaporation system the solvent-wet meal is pneumatically transported through superheated solvent gas and the superheat is used for evaporating the solvents with extremely short contact times.
In one of the downstream meal strippers the gaseous solvent remaining in the meal pores is removed by superheated steam under vacuum.
By appropriately controlling the parameters of pressure, steam addition, and tray or jacket temperature, PDI values ranging between 20 and 90% can be set depending on the raw material. The flash desolventizing system is also supplied with integrated drying and cooling systems. Numerous plants have been in operation for many years now, also for solvent removal from animal feed meals which do not require toasting. Hence the lowest steam consumption can be obtained compared with other desolventizer systems.
Protein Production
Soybean meals from the flash desolventizing system can either be used directly for producing ground and textured protein products or form the basis for the production of protein concentrates/isolates.
Distillation / solvent recovery / absorption
The individual components of the solvent-oil-mixture - the so-called miscella - leaving in the extractor must be separated. The solvent is recycled to the process.
The benefits of Harburg-Freudenberger's solutions are:
- highest product quality,
- highest energy utilisation,
- high operational safety,
- low environmental pollution,
- compact design ensuring minimal surface,
- comprehensive adaptability to customer requirements.
In the distillation process the crude oil is separated from the solvent through state-of-the-art rising-film evaporators and stripping columns. The use of different pressure levels ensures high efficiency and gentle product handling. The energy used for generating the vacuum as well as the vapours from the desolventizer-toaster are extensively utilized to concentrate the crude oil. The facility's efficiency is further increased by using a vapour contactor.
During the "solvent recycling" process, the condensed vapours are separated into water and solvent and released from entrained air. The virtually optimal temperature of the solvent enables recycling to the extractor.
Utilizing a water stripper for the waste-water as well as an absorption system for the exhaust air guarantee minimal environmental pollution through solvents.
The absorption system is operated with circulating mineral oil. It ensures effective cleaning of the exhaust air and generates a slight underpressure in the entire facility to prevent gas leakages.
Waste-water evaporation for waste-water-free extraction
Disposing industrial sewage increasingly impacts oilseed processing plants as environmental standards have become more stringent and the associated costs increase.
Thus we have developed a process for waste-water-free extraction which is characterised by:
- Waste-water is no longer discharged from the extraction process, but transformed into secondary steam for the Desolventizer-Toaster (DT),
- decreased live steam consumption by utilizing secondary steam in the desolventizer,
- cost savings in the sewage and boiler feed water processing,
- optimal utilization of heat flows in the system,
- waste-water-free extraction systems can easily be integrated in existing extraction facilities.
