The mixture after cooking is a three-phase mixture of oil, water (broth), and solid residue (oil residue). Efficient and thorough separation of these three phases is crucial for obtaining high-purity oil and dried oil residue. The equipment configuration at this stage reflects the emphasis on separation efficiency.
Separation typically involves two steps. The first step is solid-liquid separation, often using a screw press or horizontal centrifugal screen. The screw press conveys and compresses the material via a screw shaft, achieving initial separation through filtration by a screen. Its performance hinges on the screw's compression ratio design and the screen's pore size and strength, directly affecting the oil content and processing capacity of the oil residue. The second step is oil-water separation, separating pure oil from the pressed oil-water mixture. This step often involves an oil separator or a settling tank. High-speed centrifugal oil separators utilize the density difference between oil, water, and trace solid impurities to achieve rapid and continuous separation in a centrifugal force field, offering high efficiency, but also requiring significant investment and maintenance. Separation tanks rely on gravity for natural settling. While simple to operate, they are time-consuming, and the purity of the separated oil is significantly affected by its melting point. They are suitable for applications where efficiency is not critical. The effectiveness of this separation process directly determines the water content, impurity content, and subsequent refining difficulty of the finished oil.
