2INTRODUCTRY TO CHEMICAL ENGINEERING THE VEGETABLE OIL EXTRACTIONINTRODUCTRY TO CHEMICAL ENGINEERING
3EXTRACTIONExtraction is one of the most useful and widely used chemical seperation methods.There are two types of extraction process:Solid – Liquid ExtractionLiquid – Liquid Extraction
4Solid – Liquid Extraction Leaching generally refers to the removal of a substance from a solid via a liquid extraction media. The desired component diffuses into the solvent from its natural solid form.
5Some usage examples:Examples of leaching include the removal of sugar from sugar beets with hot water and the removal of nickel salts or gold from their natural solid beds with sulfuric acid solutions.
6Types of EquipmentsThere are many different types of equipment used for leaching. Most of these pieces of equipment fall into one of two categories:Percolation....."Liquid Added to Solids“The solvent is contacted with the solid in a continuous or batch method. This method is popular for in-place ore leaching or large scale "heap" leaching. Popular for extreme amounts of solids.Dispersed Solids....."Solids Added to Liquid“The solids are usually crushed into small pieces before being contacted with solvents. This is a popular leaching method when an especially high recovery rate can economically justify the typically higher operating cost (Ex/ gold extraction)
8Liquid – Liquid Extraction Liquid extraction (or solvent extraction) refers to an operation in which the components of a liquid mixture are separated by contacting it with a suitable insoluble liquid solvent which preferentially dissolves one or more components.In this operation, the separation of the components depends upon the unequal distribution of the components between the immiscible liquids. The feed solution represents one phase and the solvent to be used to effect separation represents the second phase. The mass transfer of the solute liquid takes place from the feed solution to the solvent phase.
9Basic StepsTypical liquid-liquid extraction operations utilize the differences in the solubilities of the components of a liquid mixture. The basic steps involved include: 1. Contacting the feed with the extraction solvent. 2. Separation of the resulting phases, and 3. Removal/recovery of solvent from each phase.
10Some Basic Steps & Extractor Design Typical liquid-liquid extraction operations utilize the differences in the solubilities of the components of a liquid mixture. The basic steps involved include: 1. Contacting the feed with the extraction solvent. 2. Separation of the resulting phases 3. Removal/recovery of solvent from each phase.
11LET’S START TO EXTRACT SOME OIL!!! Selecting the best system for type of oilOILSEED PROCESSINGRemoving tough outer shellsDECORTICATIONImprove the surface areaROLLINGRemoving dust,sand etc.SEED CLEANINGGetting your seeds into useful sizesSIZE REDUCTIONClean some mess outCONDITIONINGNeed some oil? EXTRACTIONGetting pure oilREFINING
12PREPERATION OF OIL EXTRACTION Oilseed processingDecorticationSeed cleaningSize reductionRollingConditioning
13Oilseed processingVarious small-scale techniques are available to enable people in rural areas to process their own oilseeds locally. Careful consideration is needed to select the system that will best suit the local circumstances. These circumstances include the scale of operation required, the availability of a power source, and a number of other factors.DecorticationSome oilseeds have a hard outer shell which must be removed before processing. This process is called decortication. Palm kernel is an example of a seed that must be decorticated prior to processing. The extraction of oil from other oilseeds which can be processed without decorticating them first, such as sunflower, may be aided by removing a proportion of the hulls before processing.
14Seed cleaningIt is essential to winnow and sieve oilseeds, prior to expelling, to remove as much dirt, dust, sand and small stones as possible. The presence of sand results in high wear on critical components of expellers such as cages, wormshafts and chokes. Using clean oilseed for expelling will greatly increase the time that the expeller can be used before replacement parts are needed.Size reductionGenerally, small oilseeds (such as sesame or rapeseed) can be processed directly, while larger seeds (such as copra or shea nuts) need to be ground before processing. At the domestic level, grinding is usually carried out with a pestle and mortar (Plate I) while larger quantities may be ground in a village maize mill (Plate II). Hand-operated meat mincing machines can also be used in certain circumstances. The most common type of powered mill used for small-scale operations is the hammer mill.
15RollingRolling a seed generally results in an improvement in oil extraction by increasing the surface area of the seed while at the same time retaining channels for the flow of oil. The flakes should be very fine and preferably thinner than 0.1 mm. Rolling before processing in a bridge press is said to increase oil yields by 10% for palm kernel, groundnut and sunflower.ConditioningOilseeds are nearly always conditioned before large-scale expelling. Small-scale expellers minimize the need for pre-treatment by using a relatively fast wormshaft speed which shears the oilseed as it passes through the expeller and produces frictional heating within the expeller barrel. This assists oil expulsion by raising the temperature of the oilseed.
16VEGETABLE OIL EXTRACTION The "modern" way of processing vegetable oil is by chemical extraction, using solvent extracts, which produces higher yields and is quicker and less expensive. The most common solvent is petroleum-derived hexane. This technique is used for most of the "newer" industrial oils such as soybean and corn oils.Another way is physical extraction, which does not use solvent extracts. It is made the "traditional" way using several different types of mechanical extraction. This method is typically used to produce the more traditional oils (e.g., olive), and it is preferred by most "health-food" customers in the USA and in Europe. Expeller-pressed extraction is one type, and there are two other types that are both oil presses: the screw press and the ram press. Oil seed presses are commonly used in developing countries, among people for whom other extraction methods would be prohibitively expensive. The amount of oil extracted using these methods varies widely.
17Wet extraction methods: In wet extraction methods water is used to extract oil from oilseeds. The distinction should be made between wet methods and water-assisted methods of oil extraction.Wet extraction methods involve the use of a relatively large amount of water so that the oilseed is suspended in the water and the extracted oil floats on the surface.
18WATER-ASSISTED METHODS Involve the addition of a small quantity of water to the oilseed before the oil is extracted by manual kneading. These methods are discussed later. They are not classified as wet methods because all the water used is absorbed by the oilseed and no separate water layer is apparent.
19HOT WATER FLOTATION (HWF) METHOD The hot water flotation (HOOF) method of edible oil extraction is traditionally used in the rural areas of many developing countries. Usually, decorticated oilseed is used. The oilseed kernels are heated and ground by pounding in a pestle and mortar. The ground seed is then suspended in boiling water and boiled for at least 30 min. Liberated oil floats to the surface. Further quantities of water are sometimes added after boiling to replace that lost by evaporation, and to encourage the oil to float to the surface. The oil is carefully scooped from the surface of the water using a shallow dish and is then heated over a fire to remove residual moisture.
20The advantage of the HWF method over other small-scale oilseed processing techniques, such as those using expellers or ghanis, is its simplicity. The equipment required (pestle and mortar, boiling pans, etc.) is readily available. However, oil yields tend to be low and the process can be time consuming and arduous. This is especially true if traditional pestle and mortar methods are used to grind the oilseed kernel. If long boiling times are used, fuel consumption will also be high.The above method may be applied to most oilseeds with varying degrees of success. Sources of oil, such as coconut and oil palm fruits, can be processed by traditional methods which make use of the water already present in the seed.TRY
24OIL EXPELLERSSeries of small scale oil expeller These small scale screw type oil expeller are advanced oil processing machinery, characterized by their high oil output rate with good quality, simple design, easy to use and continuous operation. They can use for various raw material, such as peanut, beans, rape and cotton seeds, sesame, olive, sunflower, coconut, grass seed etc
25Oil expellersExpellers are continuous in operation and work by grinding and pressing the raw material as it is carried through a barrel by a helical screw.The pressure inside the barrel, and hence the yield of oil, are adjusted using a ‘choke’ ring at the outlet. The equipment has higher production rates than similar sized presses but is more expensive to buy and operate.
26PRESS TYPES OF THE OIL EXTRACTION PROCESSES These presses are used in the rolling stage of the oil extraction. They help the extraction by widening the extraction surface area.Manual pressesThe wedge pressThe plank pressCage pressesCurb pressesBridge pressBridge-type Cage pressScissor pressHydraulic pressRam pressGhani
33INFORMATION ABOUT SOME TYPES OF OILSEEDS COCONUTSCoconuts grow in the coastal areas of the tropics.Major producing countries are: The Philippines, Indonesia, Malaysia, Sri Lanka, India, C’ote d'Ivoire, Mozambique, Tanzania, and the Pacific Islands.
34USAGE EXAMPLES OF COCONUT As a cooking oil and in the preparation of oil and fat blends for the food industry.Soap-making
35GROUNDNUTS:The groundnut is an annual plant.Varieties are grown as two types, either as a bushy bunch or as a runner.Groundnuts grow in tropical and subtropical regions, and in warm parts of temperate regions.
36USAGE EXAMPLES OF GROUNDNUTS Using a diesel-powered CeCoCo H54 expeller
37OIL PALMS:The oil palm requires a rainy tropical climatebegin to fruit after 10 yearsdo not give a full crop for about 20 years
38USAGE EXAMPLES OF OIL PALMS Used in commercial agriculture in the production of palm oil.
39RAPSEED & MUSTERDSEED: Rape and mustard are similar species and for the purposes of this manual can be treated as one oilseed. Rape is one of the most widely cultivated oilseed crops
40SUNFLOWER SEED:Sunflower is an annual plant that thrives in the tropics at medium and high elevations and, under suitable conditions, in temperate climates.
41SOYA:The soyabean, or soybean, is an annual, and with the selection of the appropriate variety, can be grown in a wide range of conditions