Oilseed Preparation
In mechanical preparation, the cell structure of the oil-bearing seed is ground in order to obtain access to the oil contained in the form of minute droplets in the seed. This grinding needs to be clearly defined because the cell structure obtained by grinding must be suitable to support the process of separation following preparation.
Thermal preparation serves for heating and drying seeds that are to be processed. Not only does heating reduce the viscosity to the oil, it also makes the seed softer, thus facilitating the process of rolling it into flakes. This applies particularly to soybeans. By thermal treatment of the seed, the composition of natural protein contained in the seed is positively influenced in consideration of possible pressing process. Furthermore, heating prevents enzymatic reactions taking place in the seed and being harmful to the quality of the product. And last but not least, the drying effect accompanying the heating process leads to an increase of the friction in screw presses and, consequently, a higher pressure and higher yields.
For mechanical preparation, the following machines are available at Harburg-Freundenberger’s edible oil technology division:
- Modular R300 cracking mill with one, two or three stage rolls and three different roll lengths for (pre-) crushing coarse-grained materials.
- The SZR300 cake breaker - a special R300 cracking mill design – features three different roll lengths for crushing press cakes prior to extraction or cooling/storage.
- The Q600 flaking mill with four different roll lengths for flaking finegrained or precrushed oilseeds.
- The high-performance Q800 flaking mill for flaking fine-grained or precrushed oilseeds.
Our thermal preparation range comprises the following:
- The TK conditioner with horizontal heating drum for indirect steam heating. The drum is available in three different sizes. Several drums of one size can be arranged one above the other, thus forming a cascade.
Cracking Mill
The R300 cracking mill consists of either one, two or three pairs of rolls arranged one above the other. The rolls are carried in pairs in a welded steel plate frame. The bearing assembly if one of the two rolls is integrated in the frame, the other roll is adjustable and spring-mounted in a rocker arm so that it can move aside if any foreign bodies (stones or other materials) are contained in the seed. The rolls rotate in different speeds in opposite directions. The fixed roll of each pair of rolls is separatively driven by an electric motor through V-belt transmission, whereas a reversing transmission unit with special V-belts effects the drive of the moveable roll.
The clearance between the rolls is easily adjustable by means of hand-wheels. A scale on each handwheel displays roll gap settings.
The rolls are made of chilled cast iron and are fitted with one-part steel axles. They are corrugated to ensure that the material is not rubbed or squeezed, but gently cut. Corrugation depends on the type of material to be crushed. In multi stage rolling mills the depth of corrugation reduces from the top downwards. The uniform roll diameter of 300 mm ensures a very good intake behavior even in case of difficult materials.
Uniform material supply into the cracking mill R300 is effected through an adjustable vibration chute arranged in the inlet hopper. The rolling mill is equipped with a permanent magnet for the protection against damages caused by iron particles.
Cake Breaker
The SZR300 cake breaker is a special version of the R300 cracking mill for crushing press cake prior to cooling / storage or solvent extraction.
Cake breaker SZR300 consists of a single-staged cracking mill R300 with an additional module in form of a pair of coarsely toothed rolls, that is incorporated between vibration chute and the pair of rolls. The pair of toothed rolls makes sure that the press cake is coarsely crushed. The pair of corrugated rolls serves for carefully granulating the material into grains of defined size with no extraordinarily high portion of fines. This kind of material is ideal for cooling or extraction.
Flaking Mill
The flaking mill consists of one pair of rolls with smooth surfaces. The rolls rotate in opposite directions. In the gap between the rolls the infeed material is rolled out to flakes, a material structure that has proved to be optimally suitable for the following processing steps. The variable flake thickness can be determined by the hydraulic contact pressure of the rolls. The typical flake thickness ranges between 0.25 mm and 0.35 mm.
The contact pressure of the rolls is generated by a hydraulic unit and transmitted by means of hydraulic cylinders to both journals of the movable roll. This ensures a uniform contact pressure over the entire length of the rolls.
The rolls of our flaking mills are made of chilled cast iron and provided with steel axles. On request, the rolls can also be manufactured from special alloys. Flaking mill Q600 rolls have different lengths, but standard roll diameters of 600 mm. Flaking mill Q800 rolls have a diameter of 800 mm with a length of 1,250 mm. The rolls are fitted with scrapers that are mechanically pressed against the rolls. Both rolls are driven at a very low differential speed.
The infeed to the flaking rolls is ensured by an adjustable vibration chute integrated into the roll frame. The electrical controls of the flaking mill must ensure that the contact pressure of the rolls is relieved immediately after an interruption of material supply in order to prevent the rolls from making contact and rotating on each other.
The Q800 Flaking Mill
The Flaking mill Q800 is the extremely heavy version of a rolling mill for the oilseed processing industry. One of its outstanding characteristics is its remarkable smoothness of running. Furthermore, the large roll diameter of 800 mm effects a very good intake behavior even in case of products with different grain sizes and increased oil content.
The Q 800 flaking mill consists of a sturdy base frame and two bearing supports laterally bolted to the frame. These frame components are made from cast iron. The bearings of one roll are fixedly mounted into the frame. The other roll is carried in movable floating bearings capable of moving aside in case of foreign bodies getting into the flaking mill. Both rolls are driven by separate electric motors through V-belts. To save space, the motors are mounted directly onto the machine.
The Q600 Flaking Mill
The flaking mill Q600 consists of a sturdy base frame made from cast iron and a prefabricated bearing support mounted onto the frame. One of the two rolls is integrated in the frame, the counterroll is adjustable and mounted on a rocker arm. The fixedly mounted roll is driven by an electric motor through special V-belts which, after being reversed, also drive the adjustable roll.
The Conditioner
Conditioners serve for thermally pretreating infeed material and, thus, have a decisive function within the oil extraction process as a whole.
Conditioner Type TK consists of one or several heating drums arranged one above the other, thus forming a cascade. The number of drums used depends on the heating surface required for heat transfer. The heating drums are designed as horizontal cylindrical pipes provided with a double jacket. For indirect heating and drying of the infeed product, the jacket space is heated with saturated steam (max. 10 bar overpressure). Product supply into the conditioner is effected by a variable-speed feed screw. The vapors produced by heating and drying are evacuated into an appropriate aspiration system through a vapor hood.
Each heating drum is equipped with a special horizontal agitator ensuring permanent mixing of the product as well as a uniform product level in the drum.
The agitator has no conveying function. Material is transported according to the overflow principle, whereby the level of the conditioner drums is controlled by adjustable overflow weirs.
The product parameters of temperature and moisture called for are primarily set by controlling the steam pressure for indirect heating. Injection nozzles for direct steam and water are further means for setting these parameters. In contast to vertical heating kettles, the design of conditioners allows a very uniform treatment of the individual product particles which is, on the one side, a result of the very intensive mixing of the product by the agitator, on the other side of the uniform transportation of the product through the apparatus. The material transportation can be considered as very uniform, plug-like flow with a very narrow retention time spectrum.
Harburg-Freudenberger manufactures conditioner drums in three different sizes. Drums of one size can be assembled as modules to form a conditioner. Agitator shafts of bigger drums are hollow and can, in addition, be heated by saturated steam and used as heating surface.
The conditioners are considered as pressure vessels and are, hence, manufactured in accordance with applicable international regulations. The agitators are separately driven by slip-on geared motors. To reduce heat lesses and provide protection against accidental contact, the conditioners must be insulated by the customer.
