Oil extraction method is using solvent to dissolve the grease, through the wet permeability, molecular diffusion and convective diffusion, to extract oil in the seeds.
Oil extraction method is using solvent to dissolve the grease, through the wet permeability, molecular diffusion and convective diffusion, to extract oil in the seeds.
Take soya for example: cleaning→ crumble→ soften(steam conditioning)→ flaking→ extrusion→ solvent extraction→ evaporation→ steam stripping→ soya crude oil
Ⅰ. Cleaning
Raw material will mixed with some impurities in harvest, transport and storage. So after it goes into workshop should cleaning once time. Cleaning method as follows:
1. Screen: use sieve to remove bigger or smaller impurities;
2. Air classification: to remove light impurities and dust, also can use for remove stone and metal these heavy impurities.
3. Gravity method to remove stone
4. Magnetic method to remove metal.
5. Cleaning for side by side mud
6. De-dust.
Ⅱ. Crumble
In order to meet requirement of crumble, water content of material must be controlled. Such as soya, its suitable moisture is 10～15%。
Commonly used crumble equipments: rod-toothed crusher, hammer crusher, disc sheller.
Soya normally use rod-toothed crusher, and crumble to 4～6pcs.
Ⅲ. Soften(steam conditioning)
Softening is through the adjustment of material’s moisture and temperature, improve its elastic plastic, so that it can get best condition for flaking, ensure the quality of flake. Softening mainly use for low oil/water content, high shell content, poor plasticity, hard texture material. Such as soya.
Ⅳ. Flaking
Flaking mean use machine to roll material from pellet to flake. It can damage cells and make oil easy flow out; oil seeds rolled into flake, surface area is increased, oil area also increased, and greatly shorten distance of oil from flake. Generally, the thinner flake is, the more tissue damage is, the better the effect of oil extraction is. Soya flake thickness should be under 0.3mm.
Ⅴ. Extrusion
Extrusion is a kind of high temperature and short time process. After high temperature and hot extrusion processing, the oil seeds can reach the following goals:
1) Cooking denatures protein and starch paste, expand can rapidly and completely destroy the cellular structure, so easy for extraction.
2) A variety of enzymes will be inactivation, especially fatty enzyme, oxidase inactivation rate more than 95%
3) Raise oil yield, reduce solvent loss.
Ⅵ. Solvent Extraction
Oil extraction method is using solvent to dissolve the grease, through the wet permeability, molecular diffusion and convective diffusion, to extract oil in the seeds. Then separate the mixture of solvent and oil, recover solvent and get crude oil. Also, the solvent recovery of soybean meal can be obtained.
Ⅶ. Evaporation
With indirect steam heating, evaporate solvent in the mixture of solvent and oil.
Ⅷ. Steam stripping
Solvent can’t completely separate by heat evaporation, so it must be combined with steam stripping. Under 110～115℃ temperature, through direct steam(0.2～0.5kg/cm2), a small amount of solvent in the mixture will be carried away with steam, so that to remove the residual solvent.
Ⅸ. Crude oil
Crude oil generally refers to oil which extraction from the extraction or pressing process, it contain some impurities which not suitable for human eating. Soya crude oil need refining then can eat.
