Physical refining process

There are two principal continuous refining processes physical refining and chemical refining. Three other continuous refining techniques used in the sunflower oil industry are improved modifications of the above processes. These include the cold chemical refining process, the modified chemical refining process and the modified physical refining process. 

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Characteristics of Palm Oil Refinery Effluent. Table 38 shows the characteristics of the effluent from a typical palm oil refinery employing a physical refining process. The effluent is slightly milky and is acidic in nature. It can be seen that the characteristics of the effluent vary quite widely. Nutrient (N and P) contents seem to be sufficient for biological process according to BOD N P of 100 5 1 ratio. It contains low suspended solids and fatty matter, which are mainly dirt and free oil from washwater and oil spillage. 

Physical refining process is fairly simple and is environmentally friendly and more economical for palm oil, coconut oil, and palm kernel oil. The process may not remove the trace impurities if the bleaching step is not done properly. 

Organic Refining Process (ORP ) by IPH, a citric-acid-based physical refining process. 

The phospholipid content of fully refined sunflower oil must be low. The oil processing industry uses phosphorus (P) as a measure of phospholipids, because of the specific molecular relationship between phosphorus and phospholipids. It is not difficult to reduce the phospholipid content of sunflower oil by chemical or physical refining process, which will be discussed in Sections 5.10 and 5.11. 

Degummed oil can be taken straight to the chemical or physical refining process. 

The oil is then heated for bleaching to the same temperature condition as described earlier under the physical refining process. 

This process is based on the fact that a certain amount of soap is required for the hydrated silica to adsorb phospholipids from the oil. Since no caustic is used in physical refining process (Section 5.10), hydrated silica becomes ineffective in the physical process and does not remove any amount of phospholipids from the oil. In the modified physical refining process, the oil is analyzed for ppm of phosphorus. The required amount of caustic solution is added to the oil to produce soap. The concentration of soap produced (ppm) must match the ppm of phospholipids in the oil. The oil and caustic solution are mixed in a high shear mixer. Hydrated silica is added to the oil in a vacuum vessel. The remainder of the process is similar (bleaching, and so forth) to the physical refining process. 

Modified physical refining process also eliminates effluent discharge but removes more phosphorus and trace metals than the physical refining process. 

Both the modified chemical and modified physical refining processes were first introduced by the W. R. Grace Company, the inventor of the hydrated silica, Trysil. Other companies later introduced their versions of similar refining techniques. 

In the physical refining process (Cmolik and Pokomy, 2000), phospholipids are efficiently eliminated, and the degummed oil is thoroughly bleached and deodorized. Free FA are distilled off with other volatiles during the deodorization step. 

Physical Refining Process (Solution of the Environmental Problem). VFT realized the advantage of preventing the production of waste materials by removing the impurities in naphthalene simply by repeated appUcation of a physical separation... 

In the next step, fatty acids are separated from the oil by neutralisation (deacidification or afkahne refining) with sodium hydroxide solution (which is also effective in the removal of toxic gossypol from cottonseed oil see Section 9.11). The free fatty acid content varies widely within 0.5-1.5% in seed oils from raw materials grown in a temperate zone. After neutrahsation, the fatty acid content falls below 0.1%. The resulting soaps are separated as soap stock and typically used in animal feed. Tropical oils, such as palm and coconut oils, contain 3-7% free fatty acids. It is therefore preferable to separate the free fatty acids together with volatiles by distillation in the end stage of physical refining process. In this case, the main components of the distillate are free fatty acids. 

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