Generally, rapeseed oil only have 30% of oil extraction rate in vegetable oil processing. If you use the following methods can help you increase 25% oil extraction rate more than before.
Remove the sand by sieve before vegetable oil processing because sand will absorb oil to reduce oil extraction rate of rapeseed.
Well control the fire of cooker. In general, flat bottom cooker is employed to roast rapeseeds and spill all cooked rapeseeds out from cooker at one time. Every time there is 1.5 to 2 kg rapeseeds paste at the bottom of cooker. As a result, when rapeseeds medium cooked, open upside cover, seal downside wind inlet, to control fire of cooker. The detailed way is to built activity tank in the wall of stokehole with an active iron plate embedded. When need big fire, put the iron plate up to seal the stokehole. When need small fire, put the iron plate down to seal the wind inlet.
Change worm shaft of rapeseed oil press. If you use model 95 horizontal oil press, change No.5 worm shaft into old No.6 worm shaft. In this way, the insdie pressure can be increased. The oil extraction section can be pushed 8-10cm after. Only this change can get more 1-2kg oil per 100kg rapeseeds.
Hot material to press becasue oil molecule is most active in high temperature. After cooked, the rapeseeds is just 108 ℃, at this time to press material can extract more oil. As a result, the quantity per batch of cooker had better be controlled in 40-50 kg with no material left to ensure hot mateiral to press.
Limited bran added in rapeseeds can increase oil extraction rate. After adding pressured in press chamber, the flow will be more fast that the oil in rapeseeds have not all extracted when oil cake get out of oil press. So every 100kg rapeseeds can add 5-7kg bran. Good quality rapeseeds add bran more and bad quality rapeseeds add less. The bran should be fresh and no impurities, removing dust by screen. Add bran can make the flow of material slower so extract more oil from rapeseed. After extracted, the oil residue can mix with bran to add into rapeseeds for pressing, which can also increase oil extraction rate.