Crude oil extraction

Introduction

Oil means crude oil, unrefined, it can be obtained by 2 methods:

• Physics: For the application of pressure
• Chemical: For solvent extraction.

Extraction pressure

There are two types of extraction processes pressure: The batch process and continuous process. The first process uses hydraulic presses type Marseillaises, Anglo American or cages. The second method uses mechanical presses usually composed of two worms, the first screw leads seeds into a perforated cylinder and the second allows the extraction of oil pressure.

The oil obtained by pressure is called pressure first. Rejected the cake still contains a part more or less important of the residual oil. The latter can be extracted by solvent or pressure after heating the cake, this oil is commonly called second oil pressure.

Batch processes for hydraulic press

The hydraulic presses are no longer used in some cases and for almost artisanal productions. Among these presses, there are several types.

• Presses Marseillaises:

The seeds are enclosed in bags called scourtins. These bags are stacked on each other and separated by metal plates. Under pressure, which can reach 250-300 kg / cm², the oil filter through scourtins and flows on the lower shelf and then in a container. This produces a so-called first oil pressure.

The operation was completed, the scourtins are removed, the cake is crushed and milled and after heating, issued in scourtins and subject to a 2^ndpressure.

b) Anglo-American Press:

Like Marseille presses, these presses are open, they have however the advantage of using simple filter surface on the folded product to be treated and which are easier maintenance than scourtins.

c) presses cages:

These presses are closed and they can reach pressures of about 500 kg / cm². The material is received in large cylindrical metal containers (cages), whose bottom is closed by the lower plate of the hydraulic press and whose walls are formed by vertical metal bars and closely juxtaposed, or by an envelope continues metal perforated with a multitude of small holes.

Continuous

Continuous processes (Figure 4) are now almost the only oil used in industry. To this end, it employs presses metal cages filter. The crushed seed is introduced and is compressed by a combination of worm called regressive step "arrangement" turning speed typically slow.

A cone, which can adjust the position, defines the end of the annular cage a more or less narrowed by which the fate cake. The setting of the cone, the choice of the arrangement, the rotational speed are key determinants of the degree of exhaustion of cake.

A cage of modern press is divided into sections. The bars are separated from each other by small sized steel shims. The spacing between the bars is the same for the various sections of the cage. It also varies depending on the nature of the crushed seed and how to work the press.

The provision of these elements between them, and also the choice of screw pitch and speed of rotation of the tree, dependent on performance of the press and use.

Processing of fruit pulp

The main oleaginous fruits that are commonly deals are the fruit of the palm and olive trees.

a) Extraction of palm oil:

First, it is worth noting the fragility of the product and its conservation difficult. Palm schemes should be sterilized as soon as possible to avoid enzymatic hydrolysis of the oil they contain. This is done in autoclaves heated with steam at a scale of 100 ° C for 30 minutes.

After cooking-sterilization, the plans can be stored without alteration for 12 hours. Then they go on a égrappeur between fruit waste roundups. It then proceeded to extract the oil.

Two cases may arise:

• If the shell of the nucleus is thick enough, we proceed to the extraction of oil through a hydraulic press or a press continues. The result is an emulsion of oil and water formed a mass of fibers and cellulosic debris which will separate the kernels.
• If the shell of the nucleus is thin and may break it can extract the oil by centrifugation. The oil obtained is better rid of solid particles in the previous cases. This method of treatment is ideal for small and medium productions.

It remains to point out that there is a process of extracting the oil palm by
shredding of the pulp and training of the oil by washing with hot water. The fruits are introduced into a kneader heated with steam at 100 ° C. The flesh is torn and oil escape. Then introduced to the hot water washing the residual fiber.

b) Extraction of olive oil:

There are different varieties of olives: olives and table olives for oil. The oil content of the latter varies from 15 to 25% with a moisture content of 40 to 50%.

The quality of the product obtained depends on the speed of treatment. It is therefore necessary to store shortly after fruit harvest. We must also avoid shock or wounding fruit during collection, handling and manipulation. Any shock or injury is likely to negatively affect the quality of the oil enclosed.

In general the pattern of production is as follows:

• sorting and washing of fruits;
• milling;
• mixing;
• oil and
• separation of phases.

Solvent extraction

The solvent extraction of oils and fats is mainly carried out industrially by connecting the oleaginous matter to deal with an appropriate solvent. This produces a solution of oil in the solvent or miscela whose concentration varies depending on the quality of the solvent and the oil wealth of oilseeds Treaty.

This miscela after filtration and concentration, is subject to the action of heat in an evaporator and then in a vacuum column finisher with an injection of steam to the total elimination of last traces of solvent. The vapors produced are condensed in conventional devices and the resultant oil is cooled and stored until processing.

The condensed solvent is collected in a separator where it is rid of water from the injected steam and humidity of treated products.

Flour extraction still retain a quantity of solvent enough, that we get into appliances dryers. Again, the last traces of solvent are hunted by using live steam or vacuum more or less pushed.

Solvents

Among the solvents used, we can identify several types: petroleum, chlorinated solvents and alcohols. However, the use of one or the other may be allowed or prohibited by regulation in certain countries. In Europe, the use of solvents as processing aids governed by Directive 88/344/EEC of 13 June 1988 on the approximation of Member States on extraction solvents used in the manufacture of foodstuffs and food ingredients

a) derived from petroleum:

The most widely used solvent is hexane, apolar molecule. This extraction is based on the following principle: apolar compounds such as fats are insoluble in polar compounds like water, but soluble in apolar solvents such as hexane.

The point of evaporation of hexane was less than that of fat extract, it is very easy to separate these two compounds by heating the mixture.

b) The chlorinated solvents:

Oil unfortunately the disadvantage of being flammable, and give with air, explosive mixtures. It was therefore sought for the treatment of certain seeds or cakes, various non-flammable chlorinated solvents, among them the boiling trichlorethylene at 87 ° C under normal pressure was used. The effectiveness of this solvent was superior to that of hexane for temperatures of 55 ° C. In return for this advantage, it should be noted that trichlorethylene dissolves not only fat but still very large quantities of gums, mucilages, phosphatides and color pigments, contained in oilseeds. Its boiling point is also much higher than that of hexane, which requires more heat during the distillation of Miscell.

It follows that the oils extracted with this solvent are generally darker than those obtained by hexane. They are often very difficult to bleach and refining losses are therefore higher.

On the other hand, most chlorinated solvents such as trichlorethylene, must be stabilized before use because the vapors present dangers of corrosion that does not escape the same material made of stainless steel.

c) The alcohols:

Alcohol has been used industrially primarily for the extraction of soybean oil but despite the advantages presented by this solvent, it is little used because of administrative and fiscal.

The isopropanol can also be used but its relatively high price compared to other solvents such as hexane limits their application.

Discontinuous extraction

a) Extractors fixes:

These fixed extractors consist of a vertical cylindrical tank with a watertight floor filter at the bottom, a port of loading to the upper part and a buffer discharge laterally situated just at floor level filtering. An injection of steam under the floor to filter through the mass of exhaust product allows the recovery of solvent and drying of the flour.

Some of these devices are still in operation but are no longer used for small productions. They have the disadvantage of the irregular rate of depletion due to the creation of preferential passages of the solvent in the mass treatment, and require, in addition to handling difficult unloading.

b) rotary:

These devices consist of a cylindrical tank resting on horizontal tread rollers allowing the rotation of the device and its contents.

The interior filter elements consisting of tubes covered with filter cloth. The linkage of the device avoids the disadvantages of fixed extractors, as well as clogging up too quickly filter surfaces.

A heating double jacket and inner tube heater ensures the drying of the meal after extraction.

Extraction

The principle of extraction is to ensure, in a device, movement of the subject matter and the solvent, so that this matter getting regular oil, while the solvent is transformed into more and miscela more concentrated. This is achieved by a march against the current.

a) Apparatus immersion:

Among the immersion apparatus, it may be noted first of all the apparatus' Hildebrandt ', which was practically one of the earliest continuous extractors (Figure 5).

This machine consists of two vertical cylindrical towers equipped internally, each of a screw conveyor. The two towers are connected by the base with another screw. These screws are perforated and rotate at a steady speed.

The seeds are introduced by a distributor in the tower and the lowest are driven slowly down through the screw. The lower screw takes the material and direct it downwards. The solvent is introduced at the base of the spine and covers it from top to bottom-enriched oil while the subject matter, the summit brought down by gravity in getting progressively. The base of the column is in communication with an elevator that goes up the waterproof material to a height above the level of the head of the column, allowing it to drain before being introduced into the tubes dryers. The fresh solvent is required, using a pump, just below the exit of the lift of the solvent. He completed the extraction down by gravity against the current of the material before entering the bottom of the column.

b) Apparatus percolation:

These extractors were constructed of a metal casing 15 to 20 m in height in which slow-moving perforated baskets large.

In these extractors to extract the material is brought successively in each
basket and subject, without leaving its container, to the action of the solvent until its discharge after draining.

The miscelles different concentrations are collected at the bottom of the extractor, which is divided into 7 compartments of variable horizontal section. Their movement is done using pumps and watering ramps, so that the miscela of any compartment will have to ramp watering above the adjacent compartment in the direction opposite to the movement of cells. It performs a movement against the current.

c) The process FILTREX

This process proceeds by filtration and extraction. The operation is conducted in two phases, first in a blender, then against the current in a horizontal rotary filter operating in a vacuum.

In the 1^sttime, the cylindrical extractor which includes an inwardly providing agitation and a moderate progress of the subject matter is brought into contact with a part miscela from the rotary filter. The muddy mixture out of this device is poured continuously on the surface of the rotary filter. This surface consists of a wire screen mounted on a turntable regularly within a sealed envelope and whose lower part is divided into several sectors.

The evacuation of the matter is out with a screw disposed scraping along the radius of the device. The drainage of the area between each wash and the end of the operation is facilitated by using a slight vacuum (pressure ranging from 75 to 460 mm Hg). The miscela final, generally contains about 30% oil.

Recovery of oil miscela

Whatever the type of equipment used, we find ourselves at the end of operation in the presence of a hand, a miscela more or less rich in oil and, on the other hand, a meal of extraction still imbued with any solvent that must be recovered.

Regarding the miscela begins with the filter or through a device specific to the extraction apparatus itself or in a filter miscela specially designed and characterized by an effective seal and an automatic cleaning.

Miscela The filter is then distilled in an apparatus to one or more effects, the crude oil obtained is sent finisher in a column in which it is free of the last traces of solvent by the action of vacuum and a steam injection water.

After draining, flour extraction is sent in a series of tubes dryers in which flows against the current or an inert gas or steam. A release from the column, the cakes are sent to a drying tube complement that reduces the water content to normal.