Precleaning
Precleaning is done in high-capacity machines with screens and aspiration channels to remove undesirable by-products from the harvest,
such as stems, straw, stalks, chaff, stones, loose hulls or other cereals and seeds.
Seed drying
- Beans are ideally dried to 10-10.5%
- Minimum 1% drying.
- Bean temperature: max.65°c
- Bean storage(tempering) after drying detaches hulls and equalizes moisture between beans.
Cracking
- Cracking of the beans is done to reduce the particle size.
- Set up of the rolls is extremely important:
- Maximizing slicing action
- Minimizing smashing action creating fines and wear
- Mills with corrugated rolls are used
Dehulling
Dehulling is necessary when producing Hi-Pro meal with following characteristics after extraction :
- Proteins : 48-50% (min 47.5%)
- Lipids : approx 1%
- Fibre : max 3,5%
- Moisture : 12-12.5%
Hi-pro meal is the most recommanded for poultry feed.
Conditioning
Heating up with enough residence time to increase the plasticity of the cracks, and make it possible to flake them.
Vertical stack cookers and horizontal, rotary cookers are both used.
Flaking
The seeds must then be flaked to break down the walls of the oil containing cells, making it possible for the solvent to penetrate the cells
and extract the oil.
The main points to watch are the steadiness of the feed to the unit, and the condition of the cylinder surfaces.
Expanding
As an option, the flakes can be expanded.
This is helping the extractibility and the desolventising of the flakes.
This apparatus is very often installed in the purpose of capacity increase of an existing plant.
Solvent Extraction
Flakes specifications:
| Oil content: |
18-22% |
| Bulk density: |
0.27-0.3 T/m3 |
| Moisture: |
10-11% |
| Foreign material: |
max 0.5% |
| Flake thickness: |
0.35-0.38 mm |
| Temperature: |
60-68°C |
| Over 2.4mm: |
min.80% sieve #8 |
| Through 0.84mm: |
max.3% sieve#20 |
Extracted Soymeal
- R.O.C. of meal: 0.5-0,7%
- Solvent loss: < 1kg hexane/Ton.
Desolventising-toasting-drying-cooling
Solvent is removed from the meal in the desolventizer-toaster (DT).
The meal is then dried and cooled in the DC.
For soybean, the DTDC is a heavy utility consumer:
It uses 75% of the SEP steam for meal heating and solvent evaporation and stripping.
Also 75% of the SEP’s electrical power is used for the DC blower and the DT main drive.
The new Dimax® technology makes it possible to produce fully desolventized meal of high nutritional quality, with less steam and less power
consumption.
The soymeal is heated up from 57°C up to 107°C.
By evaporating part of the solvent before contact with the live steam, the predesolventizing trays reduce the meal peak moisture, and thereby
reduce the steam consumption for heating the dryer air and the DC blowers power.
The solvent in the meal is evaporated from an initial content of about 30% down to < 250 ppm.
The toasting in the DT desactivates the anti-nutrional factors(ANF) in the soybean meal:
- -Trypsin Inhibitor
- -Urease
Miscella distillation
In the first evaporator, 90% of the hexane is evaporated by using the vapor heat from the DT, increasing the miscella concentration from 25%
up to 80%.
Solvent content in products and effluents:
- In the oil < 100 ppm solvent
- In the air vented <10gr/m3 of air
- In the waste water < 20ppm.