Research on seeds compression‐structural damage and castor oil extraction mechanism with in situ observation

Abstract Castor oil has attracted large attention for wide applications, including lubrication oil and bioenergy resources. Castor seeds mechanical pressing is widely used for oil extraction. To better research castor seeds mechanical‐structural damage behavior and oil extraction mechanism during extrusion, a self‐developed mechanical pressing test setup combined with in situ observation is built for oil output behavior. Influencing factors of working pressure, speed, temperature and creep time on oil outflow were investigated. The results indicate that seeds squeezing extraction can be divided into three stages, preloading, oil discharging, compressing consolidation stage, matching with pressing cake structural evolution. As working pressure increases, oil yield shows an upper parabola relation with pressure. When pressure exceeding 25 MPa, castor oil yield increasing tends to stabilize, reaching 38%. Speed effect showed down parabola relation on oil yield, opposite to stress factor. Creep time promoted oil output with upper parabola within 720 s. When temperature below 120°C, a linear increasing relation on oil yield presents. Oil yield decreases when above 120°C. This research provides in‐depth theoretical guidance for industrial castor oil extraction. Practical Applications Castor seeds are rich in oil content. Extracted castor oil has been widely used for industrial applications such as biodiesel, lubricants, medicine. Mechanical extraction working parameters optimization can improve oil yield of castor seeds. The research provides a basic working optimization for castor seeds oil extraction. Castor oil has unique properties and has been proved to be a high promising renewable and independent energy sources. Compared with solvent oil extraction, mechanical oil pressing extraction method has higher oil quality and safety. The mechanical extracted oil is pure without organic solvent. In the research, castor seeds compression‐structural damage property and oil extraction mechanism were studied. Besides, the influence factors including compression pressure, speed, temperature and creep time are analyzed, working optimization for castor seeds oil extraction. The research provides important reference value for the mechanical pressing process and mechanical design of castor seeds in the practical applications.