FR2482976A1 - PROCESS FOR TREATING VEGETABLE OILS TO ENHANCE THEIR COLD STABILITY - Google Patents

Abstract

A.PROCESS OF TREATMENT OF VEGETABLE OILS TO IMPROVE THEIR COLD STABILITY. B. THIS PROCESS IS CHARACTERIZED IN THAT IN A FIRST STAGE, THE OIL TO BE TREATED IN A COOLER 1 IS COOLED TO A CHOSEN TEMPERATURE OF MATERIAL TO ALLOW THE CRYSTALLIZATION OF THE COMPOUNDS TO BE ELIMINATED, THEN, IN A SECOND STAGE, THE '' OIL THUS TREATED IN A DECANTATION CONTAINER 5 AND IT IS SUBJECTED TO THE ACTION OF FINE BUBBLES OF A NEUTRAL GAS WHICH BOND TO THESE CRYSTALLIZED COMPOUNDS SO AS TO PRODUCE A FOAM OF LOWER VOLUME THAN THAT OF THE CONSTITUTED OIL BY A CRYSTAL-BUBBLE GAS COMPLEX WHICH RISES TO THE SURFACE 6 OF THE CONTAINER, THUS ALLOWING TO OBTAIN AT THE LOWER PART 7 OF THE LATTER, AFTER DECANTATION, A CLARIFIED OIL HAVING A CONTENT LESS THAN 30 PPM OF CRYSTALS AND WITH A YIELD GREATER THAN 90. C. THE INVENTION APPLIES TO THE TREATMENT OF VEGETABLE OILS.

Description

he 2482976

  The subject of the present invention is a process for treating

  * First of all, there is a need for them to improve their stability.

  cold weather. This process makes it possible to clarify (for example by de-

  waxing, wintérisation) of oils and in particular

  such as, for example, sunflower oil, maize,

or peanut.

  It is well known that certain edible oils become cloudy because of the presence of high-melting compounds such as partial waxes, glycerides, and the like.

  the presence of such compounds if it does not

  fecce in any way the quality of the oil, alters clearly

  its appearance, and thus diminishes its appeal to the consumer.

  Consequently, it is common practice to

  oils, before marketing them, a clarifica-

  cation, aimed at achieving the elimination of crystallized compounds. Polur perform this clarification operation, one

  usually uses two conventional methods.

  According to the first of these methods, the oil is cooled for a few hours to a suitable temperature, to obtain crystals that can be separated by filtration. Filtration aid is often used (eg filtering grounds). According to the second of these methods, after precipitation of the crystals as above, centrifugation of a mixture of this oil with an aqueous solution of wetting agent is carried out. In this way, we favor the passage of crystals

  in the aqueous solution, which separates from the oil by centrifugal

  fugation. However these processes are not without presenting

bad disadvantages.

  In fact, for the first process cited - the difficulty of obtaining filterable crystals requires cooling and maturation cycles of the desired duration, the production capacity is a function of the content:. It can decrease by about 20 to 30% when the crystal doubles, which is common practice in EI land

  costly filters which in addition give filter cakes

  can contain up to 60% o driven oil

  significant losses in refined oil. These cakes pose a

  pollution of the environment (danger of an inflammability

  spontaneous taint as a result of the oxidation of contained fats and

  pollution of the groundwater by fat by entrainment

  of this in rainwater).

  Furthermore, the second method cited requires the use of a large amount of wetting agent solution (5 to 10%) and the use of expensive separation equipment and requiring

high maintenance costs.

  The present invention aims to overcome these disadvantages by proposing a process for obtaining clear oils even from oils having significant levels

  of high melting constituents (waxes, glycerides,

  tics, etc.) without the use of filtration or centrifugation grounds. This process is characterized in that, in a first step, the oil to be treated is cooled to a chosen temperature

  in order to allow crystallisation of the compounds to be eliminated

  then, in a second step, the oil thus treated is brought into a settling vessel and subjected to the action of

  fine bubbles of a neutral gas that attaches to these crystal compounds.

  to produce a density foam of less than

  than the oil. The formed bubble-crystal gas complex rises to the surface of the container, thereby obtaining

  in the lower part of the latter, after settling, a -

  clarified oil having a content of less than 30 ppm of crystals

  and with a yield greater than 90%.

  The performance of such a process depends essentially on

  the formation of appropriately sized crystals, a sufficient quantity of fine gas bubbles, in the liquid, and

  of the adhesion of the bubbles on the solid particles.

  According to the invention, particular results have been obtained.

  interesting, by submitting at least some of

  oil cooled previously to quantitative precipitation

  crystals, at a pressure of 4 to 10 bars of neutral gas, and then at a pressure at atmospheric pressure. These conditions

  particulars make it possible to obtain gas bubbles, the quantity of which

  tity and diameter are such as to encourage training

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  quantitative determination of a bubble-density crystal complex

less than that of the oil.

  According to a variant of the process, it is added to the oil

  treat a small amount of clarifying adjuvant

  both to decrease the affinity of the crystals vis-à-vis the oily phase. According to another characteristic of the invention, the oil to be treated is a neutralized oil containing soaps, these

  the latter fulfilling the function of clarification adjuvants.

  Indeed, it has been found that the presence of water and

  active (soaps) promotes the adhesion of waxes to air bubbles.

  In a preferential manner, the pressurized gas-oil contact is effected with stirring for a period of time.

about 30 minutes.

  Furthermore, and according to another characteristic of the invention, the method comprises a step of reprocessing the

  waxes to recover the oils contained therein.

  The process which is the subject of the invention can

  continuous or discontinuous and will be described in more detail with reference to the attached figure which is a schematic diagram

continuous operation.

  According to the figure, the oil to be treated is fed according to the arrow A in a cooler 1 comprising a stirrer 2. In this cooler 1, the oil to be treated is brought to the appropriate temperature, chosen according to the type of oil to be treated. . At the outlet of this cooler, the oil is then brought to a maturator

  3 o it is kept at the same temperature so as to allow

  Quantitatively crystallize the compounds to be removed, under appropriate conditions depending on the type of oil. During this ripening stage, the oil is also subjected to

  stirring by means of an agitator 4.

  On leaving the maturator 3, the oil is brought along arrow D to the lower part of a settling vessel 5 and subjected to the action of fine bubbles of a neutral gas, which are fixed to the crystals at eliminate in order to produce a complex

  gas-crystals in the form of a foam of density

  less than that of the oil. This complex gathers in the zone 6 of the container, where it is removed by scraping according to the arrow C.

  The production of fine bubbles of neutral gas is ob-

  held by taking a fraction E of clarified oil which is fed into a saturator 8, where it is subjected to the action of a neutral gas such as air or nitrogen arriving according to the arrow F

  under a pressure of between 4 and 10 bar, before being

  due to the atmospheric pressure, the duration of the gas-oil contact in the saturator 8 being approximately equal to 30 min. Thus, in the fraction El, at the exit of the saturator 8, a formation of fine bubbles of air or nitrogen is produced.

  in the container 5, and are attached to the particles of

  lides suspended in the oil. According to a variant of the process, it is possible to pressurize all the oil leaving the maturator 3 by passing it through the saturator 8 before introducing it.

  in the lower part of the container 5.

  Thus, at the lower part 7 of the recipe,

  5, a clarified oil G of which a fraction E is recycled to the saturator 8. As indicated above, the flow rate of this fraction can be up to 300% of the flow rate of the oil to be treated

leaving the maturator 3.

  Moreover, after the destruction of the mosses by heating

  For example, about 1.5 to 5% of

1% waxes.

  This oil enriched in waxes can be treated by

  the process according to the invention or by usual methods (de-

  cantation, centrifugation, filtration).

EXAMPLE 1

  The starting raw material is a touring oil

  nesol containing 800 ppm of waxes. 3 kg of this oil, which has been subjected to a neutralization and contains 0.4% of water and 1080 ppm of sodium soap, are introduced into a 5-liter beaker equipped with a stirrer. all placed in a refrigerated chamber at 50C for a period of about hours with continuous stirring. This oil is transferred to a saturator of 4 liters equipped with a stirrer. We submit

  the saturator at a pressure of 10 bar.

  The contact time is 30 minutes under constant stirring, the temperature of the oil being maintained at 50C by a coil located inside the reactor. At the end

  this operation, the oil is expanded to atmospheric pressure

  by direct transfer to a 4-liter beaker. After -

  one hour of settling at + 50 ° C., a separation of two phases is obtained. In the inferior part of the container, approximately 2,850 g of the decanted oil, which contains only

  ppm wax and 0.1% water. At the top of the recipe

  approximately 150 g of a foam constituted by a wax-fine gas bubble complex is recovered. The decrepit oil can be either subjected to stages

  refining operations, is subject to a new processing cycle.

  to complete the dewaxing process.

EXAMPLE 2

  2 kg of dewaxed oil obtained according to Example 1 are treated in the same way as for Example 1. The oil entering the cycle contained 29 ppm of waxes, 0.1% of water and approximately ppm of soap . After decantation, an oil is obtained

  the wax content was lowered to 9 ppm. This oil is often

  at the next stages of refining (washing, drying).

EXAMPLE 3

  The starting raw material is a touring oil

  nesol containing 85 ppm of waxes. 3 kg of this previously neutralized oil containing 0.3% of water and 1400 ppm of sodium soap are taken. By applying the method of Example 1, a dechlorinated oil containing 7 ppxa of waxes, 0.05% of water is obtained

  and 52 ppm soap. The yield of decanted oil is 98.4%.

EXAMPLE 4

  The starting oil is a neutral sunflower oil

  bleached and discolored, containing 700 ppm of waxes, less than 0.05% of water and less than 2 ppm of sodium. The procedure is as in Example 1. A decanted oil containing about 60 ppm of residual waxes is obtained in a higher yield! 93 o. The decanted oil E7xEiMPLE 5: The starting oil is a crude oil of mals containing D50 p-om waxes, The procedure is as indicated in Example 1, ie, a decreed oil containing 50 ppiin of waxes. residual

  and whose suspended matter such as mucilage, parti-

  s solid, etc. o are at the same time partly eliminated. It goes without saying that these examples do not have a character ::? 'ifo This process can be applied to other types

  the stages of refining.

ji, i <ra !. qf30 -fcaon is.

  jo e; S, S, D-5, S, G, OSt

  therefore 95% and can be up to about 98.5%.

  Cold Stability of the Oils Obtained in Examples 1 to 5: The oils obtained in Examples 1 to 5 are subjected to conventional refining operations as the case may be, up to the stage before deodorization. The samples thus obtained are stored at + 50C

for 24 hours or more. -

  The results are shown in the table below: EXAMPLE 6: Treatment of foams An oil containing 1% of waxes from foams

  dewaxing obtained by the process according to the invention is cooled

  die at 25-300C overnight and then centrifuged. The heavy phase containing the waxes represents 12% of the oil thus treated. The light fraction represents about 88% of oil partially decried at 400 ppm of waxes, which can be recycled in mixture with

the oil to be treated.

  It can therefore be seen that by complementary treatment of the oils from the foams, the de-waxing efficiency can be improved.

EXAMPLES 1 2 3 4 5

  Initial wax content in ppm 800 29 85 700 300

Content in waxes

  in ppm 29 9 7 60 50 in refined oil Limpidity after 24 h Clear Limpide Clear Limpid Trouble Trouble Limpidity after 3 days Trouble Clear Limpid Trouble Trouble

R E V E N D -I C AT IO N S

  1 ') Process for treating vegetable oils for improving their cold stability, characterized in that, in a first step, the oil to be treated is cooled to a temperature chosen so as to allow the crystallization of the compounds to be eliminated. then, in a second step, the oil thus treated is brought into a settling vessel and subjected to the action of fine bubbles of a neutral gas which is

  attach to these crystallized compounds so as to produce a

  its density is lower than that of the oil consisting of a complex crystal-bubble gas that rises to the surface

  of the container, thus enabling the inferior part to

  of the latter, after decantation, a clarified oil

  having a content of less than 30 ppm of crystals and with a

more than 90%.

  Method according to claim 1, characterized in

  at least some of the pre-cooled oil

  lable until quantitative precipitation of the crystals at a pressure of 4 to 10 bars of neutral gas and then a relaxation at the

atmospheric pressure.

  3) Process according to any one of the claims

  1 and 2, characterized in that a small quantity of clarifying adjuvant is added to the oil to be treated, making it possible to

  to reduce the affinity of the crystals with respect to the oily phase.

  4) Process according to any one of the claims

  1 to 3, characterized in that the oil to be treated is a neutralized oil containing soaps, the latter filling the

  clarifying adjuvant function.

  Process according to any one of the claims

  1 to 4, characterized in that contact is effected by

  oil under pressure for a period of about 30 minutes.

  6) Process according to any one of the claims

  1 to 5, characterized in that all the differences are

  rentes stages at a temperature between 0 and 100C,

  preferably approximately 50C.

  7) Method according to any one of the claims

  1 to 6, characterized in that part of the clarified oil obtained at the bottom of the container is recycled to the treatment step with a neutral gas under a pressure of 4 to 10

bars.

  Method according to any one of the claims

  1 to 7, characterized in that it comprises a step of retirement-

  waxes to recover the oils contained therein.