The dry method extracts corn germ mechanically without moisture adjusting. This method has a simple process, low power consumption and no pollution. It is mainly used for producing corn flour.
2. Wet Method
Wet method is used in starch industry. The cleaned corn is soaked in sulfurous acid solution and then crushed. Adopt hydrocyclone the corn germ is separated. The corn germ has high moisture content and is dried before storage. This method has high efficiency of 85%-95%and high corn germ purity above 70%.
3. Half-wet Method
Half-wet method is suitable for fermentation industry. The cleaned corn is moistened and crushed. Adopt winnowing equipment, the bran is separated. Adopt gravity separator, the endosperm is separated from the mixture of corn germ and endosperm. The mixture enters the roller-crushing mill. The germ is flattened while the endosperm is crushed. Then by using plansifter, the germ and endosperm are separated. The corn germ is dried by pipe bundle drier and then enters the oil pressing workshop in the corn oil plant. High efficiency above 85%, low power consumption, no pollution, low cost.
corn germ→cleaning→softening→flaking→cooking→prepressing→pressed crude corn germ oil
Major Equipment: vibrating screen, magnetic separator, softening equipment, flaking roll, vertical cooker, screw oil press.
The corn germ extracted contains starch which can affect the oil yield and oil quality. Corn oil processing plant adopts vibration screen to remove the starch and bran in the corn germ to improve the purity. Adopts magnetic separator to remove the metal impurities to protect the equipment.
The cleaned corn germ enters the softening equipment to adjust the moisture content and temperature to increase the plasticity.
The softened corn germ enters the flaking roll in the corn oil processing plant to be made into 0.3-0.4 mm flakes. Flaking is to destroy the cell wall, which is good for oil yielding.
The corn germ flakes enter the vertical cooker for the cooking process. Cooking can denature the protein and make it solidify, agglutinate the oil and reduce the viscosity, which is good for oil pressing.
The cooked corn germ flakes enter the screw oil press which integrates adjusting cooker to adjust the moisture content and temperature of the cooked materials. The crude oil is filtered to remove the impurities and then enters the refining workshop. The pre-pressed cake is sent to the solvent extraction workshop for oil extraction.
Corn germ cake solvent extraction workshop uses the organic solvent to extract oil from the corn germ cake through soaking or spraying methods. There is only less 1% oil content in the meal after solvent extraction. This section includes corn germ oil extraction, wet meal desolventizing, miscella evaporation and stripping, solvent condensation and vent gas recovery.
oil extractor, D.T.D.C desolventizer-toaster, evaporator, stripping tower, condenser, mineral oil system.
- The corn germ cake from the prepressing workshop enters the oil extractor, where the solvent is used to extract oil from the cake. The wet meal discharged from the oil extractor is sent into the desolventizer to remove the solvent. The dried meal obtained is sent to the meal warehouse for packaging. The mixed vapor discharged from the desolventizer enters the shell pass of the first evaporator as the heat source.
- The miscella from the oil extractor is pumped into the first evaporator, the second evaporator and the disk stripping tower in the corn oil extraction plant to remove the solvent. The crude extracted oil obtained enters the refining workshop.
- The solvent vapor in the corn oil plant enters the condenser. The condensate enters the water separator. The solvent separated enters the solvent holding tank. The water separated is boiled to recover the solvent.
- The vent gas in the extraction workshop enters the last condenser. The vent gas from the last condenser enters the mineral oil system in the corn oil extraction plant to recycle the solvent.
Corn oil refinery is to remove the unneeded and hazardous substances such as phospholipids, free fatty acids, wax, pigment and unpleasant smell in the crude corn germ oil to obtain qualified refined oil.
Corn Germ Oil Refining Process
crude corn germ oil→degumming→deacidification→decolorization→dewaxing→deodorization→finished oil
degumming tank, nentralizing tank, decolorizing tank, crystalizer, deodorization tower, centrifuge, filter, vacuum pump, heat conducting oil furnace.
- The filtered crude corn germ oil is preheated and mixed with phosphoric acid in the corn oil refinery. The colloids such as phospholipids absorb water and expand to form the emicelle which are precipitated to be removed.
- The degummed oil enters the alkali refining tank and alkali liquid is added which reacts with free fatty acid to form soapstocks. The soapstocks are precipitated to be removed. Part of the impurities like pigment, phospholipids, protein and mucus are also adsorbed on the soapstocks to be removed.
- The neutral oil is heated and soft water is added for water washing. Then the oil is centrifuged to remove the wastewater.
- The water washed oil enters the decolorizing tank and is heated and dried under vacuum. The oil is then fully mixed with bleaching clay.After bleaching, the mixture is filtered to remove the waste clay. The decolorized oil enters the crystalizer in the corn oil processing plant and filter aid is added. Then the oil is cooled rapidly for crystallization. The mixture is filtered to remove the wax.
- The dewaxed oil enters the deaerator to remove the air and then enters the deodorization tower for deodorization.The deodorized oil is filtered to obtain the refined corn germ oil.