FI63055C - PROFESSIONAL EFFECTIVENESS FOR AVAILABILITY OF FAST PARTICLE FORMATED MATERIAL FREON FETTMATERIAL - Google Patents

Description

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M <11) UTLÄCGNINGSSKRIFT 6 3 O 5 5 ^ v ^ (51) K ».ik.3 / i« ta3 C 11 B 7/00 FINLAND — FINLAND CM) * ™ * λ **** ~ ημ * μλ * ttooo2 •. (22) H »k« ml * p * lv * - AiwOicniniKhf 03-01.77 '' ' [. r «fcimrih» lljtu. (+ t) P »*» nt- och r * gi * t * rttyr «Ia« i · Amok »utl> gd och utUkrtfMn M> Hnnd 31-12.Ö2 (32) (33) (31) * yyri« «Y« tuolk «u> ~ e« «ard prlorltat 08 -01.76

England-England (GB) 6 $ l / 76 Proven-Styrkt (71) Unilever NV, Burgemeester s'Jacobplein 1, Rotterdam, Holland-Holland (NL) (72) Hendrikus Jacobus van den Berg, Terheyden (N. Br), The present invention relates to a process for the separation of solid particulate matter from liquid fatty matter. The present invention relates to a process for the separation of solid particulate matter from liquid fatty matter. from the liquid fat material in which it is dispersed, using e.g. a centrifugal separator and a filter, which separation is obtained by mixing the dispersion in a chamber equipped with a concentric concentrator with the chamber.

Separation of the solid particulate matter from the liquid fat material in which it is dispersed is performed during the purification and fractionation operations. In the latter, certain fatty acids or glycerides of fats or glyceride oils can be precipitated as solid particles, usually by cooling and separated, for example, by filtration from other solid particles remaining in the liquid phase, which are sometimes present dissolved in solvents. The separation of the solid and liquid phases is often 63055 slow in these operations; the precipitate in the form of particles can be retained by adsorbing a large part of the liquid component of the fatty matter, and the drainage of the liquid phase components from it can be poor, even during centrifugation, especially in recrystallizations. The solid may need to be washed repeatedly to remove any adhering liquid, but this will take more time and an unreasonable amount of solvent. Thus, although more complete separation may be highly desirable to improve the quality of the solid phase or the yield of liquid, it is in any case time consuming and expensive and may even be impractical. In the process of the present invention, the particulate matter is converted to an aggregate form which can be more easily separated from the liquid phase by draining.

The method is characterized in that the agitator has a smooth and regular profile extending over the entire depth of the dispersion in the chamber and having a diameter of 1/3 to 2/3 of the chamber diameter, maintaining a homogeneous agitation at agitator speed until a substantial amount of particles are aggregated in the fat.

Mixing is homogeneous when the velocity gradient between any two particles of the mixture that are radially adjacent to each other is the same. As a result of the homogeneous mixing, the solid phase particles accumulate into agglomerates, from which the liquid phase attached to them can be drained much more easily in the subsequent separation steps.

Preferably, the chamber is at least as deep as the radial width of the fatty material remaining in the chamber between the walls of the chamber and the mixer.

The speed of the mixer should preferably be as slow as possible to achieve the desired effect, preferably 1 to 200, 3 63055 in particular 10 to 100 rpm, best corresponding to a radial speed gradient of 1-250 m / min / m, in particular 10 to 100 m / min / m. When aggregation is found to develop too slowly with a small mixer, this is best replaced with a larger mixer used at Selma speed or slower to accelerate aggregation.

The method is suitable for batch or continuous use, but in the latter case it is recommended that the chamber be good in terms of ring width in order to have several mixing steps in the fat-containing ring zone and to ensure good mixing with as much liquid-solid contact as possible.

The invention is particularly important when fractionally crystallizing fatty acids and their esters, especially fats. These include glyceride oils, which are normally liquid. Fractional crystallization can be applied to remove impurities or to separate specific fatty fractions with the desired melting properties, and can be carried out in the presence or absence of a fatty solvent, although the method is particularly valuable in so-called dry fractionation processes without substantially longer solvent. filtration times due to the higher viscosity of the liquid olein fraction. This can be separated by washing the crystals with an aqueous dispersion of a suitable surfactant, as in the so-called Lanza method. Suitable solvents for fat fractionation include acetone, hexane or nitropropane, and for fatty acids, methanol, which preferably contains some water. The amount of solvent may vary from 5: 1 to 1: 2 by weight based on the fat content. Other solvents known in the art may also be used.

Fractional crystallization is best performed in situ during homogeneous mixing, whereby the fatty material is cooled from a completely liquid or dissolved state until the crystallization of the fraction to be separated is complete, while mixing the material homogeneously. A device suitable for this purpose preferably comprises a mixing chamber fitted with a concentric mixer, each of which has a cylindrical shape and size, and a cooling device for cooling the contents of the chamber, preferably through the walls of the chamber and the mixer. There may be a lower limit to the rotor speed to ensure adequate heat transfer and to avoid excessive deposition of 63055 crystal growth on the cooling surfaces, which makes heat transfer difficult. Unlike many forms of crystallization equipment, the mixer should not scratch the walls of the cooling chamber. Such devices do not cause homogeneous mixing.

The temperature difference between the cooling surface and the grease also affects the cooling rate. Large temperature differences promote rapid cooling, but at the same time the formation of microcrystalline growth. On the other hand, small temperature differences produce larger crystals, but much more slowly.

The temperature differences shown in this specification are measured with respect to the center of the liquid and are preferably less than 10 ° C measured in the radial direction. A temperature difference of 5 to 20 ° C, most preferably 5 to 10 ° C, is best maintained between the coolant and the main body of the liquid to be cooled, at least until crystals appear. Thereafter, the temperature difference can be made larger, but preferably not above 25 ° C, especially between 10 and 20 ° C.

The invention is applicable to both edible and inedible vegetable, animal and sea fats, their fractions and hydrogenated and interesterified derivatives and their fatty acid components, for example tallow, palm, sunflower, safflower, peanut, soybean and lauric.

The invention is also useful in carrying out winter treatment. This is a form of fractional crystallization commonly applied to edible oils, such as palm or cottonseed oil, or soybean oil, slightly hydrogenated to improve its shelf life, intended for use as salad oils or frying oils. The purpose of the treatment is to prevent the onset of turbidity on standing at ambient temperatures due to the fractional crystallization of the high-melting stearin fraction in oil. In winter treatment methods, stearin is removed by filtration after cooling the oil, but conventional winter treatment methods can cause significant losses in separating olein and stearin fractions for the above reasons, and in any case a small amount of stearin even more oil is lost. The present invention provides an economical and efficient winter treatment method in which oil losses are kept to a minimum and which is as efficient as possible.

The invention is also effective when fractionating fatty matter to recover a substantial portion of the higher digestible solid fraction in a single fractionation, up to a quarter of the total weight of fatty matter. In normal practice, the solid fraction generally absorbs at least twice the lower fraction of the liquid fraction that melts below its own weight. The treated solid fractions of about a quarter of the total weight mentioned above therefore form slurries which are extremely difficult to separate into their liquid and solid fractional components, whether by filtration or centrifugation. According to the present invention, the crystals are aggregated together and retain a substantially smaller amount of liquid fraction.

The process according to the invention can be carried out, for example, at temperatures of -20 to 50 ° C. Temperatures are limited only by the physical limits of the solvents when they are used and the amount of solids removed, which is preferably not more than 35%. Separation of the agglomerated solid can take place, for example, by decantation or by gravity or pressure filtration or centrifugation.

The invention is particularly relevant when recovering fat fractions for use in the food industry which have the desired properties. For example, when formulating margarine fats, blends are often prepared from fats obtained by fractionation procedures to meet physical or chemical properties. For example, fats may have to meet defined digestibility properties, or high levels of polyunsaturated fatty acids are required for nutritional purposes. Fats meeting such requirements can be obtained by careful fractionation according to the invention. In the confectionery industry, hard butter species with the critical melting properties required of the fats used for this purpose can also be obtained by fractionation according to the invention, in particular palm oil and also other vegetable fats which may have been cured before or after fractionation.

Example 1

In the example, a cylindrical crystallization chamber with a cup-shaped bottom and a lid plate was used. The chamber was also equipped with a cylindrical rotor mounted on a vertical, chamber-extending rotor shaft rotated by a motor mounted on the deck and supported on bearings in the center of the chamber cover plate and the 6 63055 cup base.

The chamber was approximately half as deep as wide, and the rotor, which extended substantially over the entire depth of the chamber, was half as wide as the chamber. The chamber itself was provided with an external cooling jacket in which an aqueous solution of ethylene glycol cooled to a predetermined temperature could be circulated.

Soybean oil was slightly hydrogenated to iodine 110-112 using fresh, supported nickel catalyst. This improves the resistance of the oil to oxidative deterioration, but is due to the turbidity of the oil when standing due to the crystallization of the stearin fraction. This was removed from the oil according to the invention using the described device.

After removal of the catalyst, the oil was cooled to 36 ° C and fed into the crystallization chamber. The stirrer was rotated to give a velocity gradient of the liquid in the ring of about 15 m / min / m. The temperature of the aqueous ethylene glycol recycled in the cooling jacket was maintained so that a temperature gradient of 20 ° C / m measured radially through the oil with respect to the measuring point at the center of the vessel and rotor walls was obtained. Crystals appeared when the temperature dropped to 21 ° C, and the temperature difference was raised to 35 ° C / m until a final temperature of 3 ° C was reached. The oil was then filtered through a standard vacuum filtration unit to give 74% olein in 3 hours based on the weight of the hydrogenated oil. The olein remained clear at 0 ° C for at least 5 hours. In contrast, hydrogenated whole oil precipitated stearin crystals even when standing at 20 ° C.

In a comparative experiment using conventional fractional methods and an agitator in the vessel instead of a rotary stirrer and scrapers to remove crystalline material from the vessel walls, only about 60% yield was obtained when the conditions were adjusted to give a similar filtration time. In both cases, the olein product was suitable for use as a frying oil and remained clear when stored under ambient conditions.

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Example 2 63055

A series of experiments were performed by fractionating a similar hardened soybean oil fed at 30 ° C to a similar apparatus consisting of a chamber 60 cm in diameter and 1 meter in height fitted with a rotor mixer 30 cm in diameter. In the experiment, the effect of the fractionation temperature and the temperature difference, which was kept constant in all experiments, on the performance rate and the olefin frying was observed. In all experiments, the rotation speed was 42 rpm, which corresponded to a speed gradient of 264 m / h / m. The effect of "stabilization" was observed in the experiments by keeping the cooled fat for 2 hours at the fractionation temperature.

All experiments yielded olein, which remained clear at 0 ° C after 5 hours. Other details are presented in the following table.

Table Cooling conditions

Experiment Heat- Stabilization- End Time Olein- Filtration- space difference tertiary (hours) yield rate oc (hours) heat- 30oc. * M3 / m2 / h space _ _ f! Fi_ _ _ _ 1) -) 10 67, 6 5.2 la j 3-4 2 J 12 65.7 4.0 2)) 0 - 6 63.6 0.99) 10) 2a) 2 j 8 60.8 0.68 3 6 - -1, 5 7 61.3 0.63

Experiments 1 and 2 show that the filtration rate clearly decreases and the olein yield increases significantly as At decreases, at the same temperature. A comparison of Experiments 1 and 1a and 2 and 2a surprisingly shows that the "stabilization period" maintained at the fractionation temperature is detrimental in contrast to conventional fractionation practice. Finally, Experiment 3 also shows that a good olein yield can be obtained, compared to Experiment 2a, also at a lower temperature, i.e. -5.5 ° C, by maintaining a lower Δt and avoiding a long stabilization temperature.

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Example 3 63055

Palm oil (iodine number 53) was stirred at 100 rpm.

in a cylindrical vessel twice as deep as wide, fitted with a cooling jacket and a concentric cylindrical rotor extending substantially over the entire depth of the oil and half the diameter of the vessel, the oil was cooled from 50 ° C at a rate of 12 ° C per hour To 28 ° C, where it was kept for 5 1/2 hours with stirring, whereby NMR analysis of the samples showed 8% solids to form. the oil was filtered 3 2 at the same temperature with a flow rate of more than 10 m / m per hour and a filtration pressure of 0.5 atmospheres.

The filtrate contained 80% of the original palm oil, with the filter retaining 20% of the residue.

The example was repeated in a continuous apparatus of similar dimensions using a stirrer speed of 40 rpm. The result was 9% solids, and the filtrate again formed 80% of the original oil with an iodine value of 57 and a filtration rate of 6.5 m / m per hour. The residence time was 2 hours.

At a crystallization temperature of 13 ° C and a stirring speed of 80 rpm. a 45% yield of a liquid fraction with an iodine value of 63.2 at a filtration rate of 0.5 m / m per hour was obtained from a continuous apparatus. This is an excellent yield given the heavy residue to be removed. The residence time was 5 hours.

Example 4

The Malayan palm oil fraction (iodine number 58.4) obtained by dry fractionation of palm oil was mixed 4 times by weight with acetone and fractionated at 3 ° C by cooling from 50 ° C to 3 ° C in the batch apparatus described in Example 3 at a cooling rate of 12 ° C per hour while stirring at 300 rpm. After stirring at this temperature for 3 hours, the filtration was rapid, and the filter cake was washed four times, each time with 1 1/4 times the weight of the starting oil in acetone. After evaporation of the solvent, 36% of the residue was obtained (iodine number 41.3), giving a filtrate oil yield of 64% (iodine number 68.5) based on the starting oil.

Example 5 9 63055

Example 4 was repeated at -6 ° C. Cooling was at 30 ° C, the stabilization time was 5 hours, and an equal weight of hexane was used as the solvent. After washing the filtrate residue twice with hexane each time, the oil content of the starting oil and evaporating the solvent gave a filtrate oil having an iodine value of 67.8, 64.1% by weight of the starting oil, and a residue having an iodine value of 43. 2, 35.9%. ·

Example 6

Tallow fatty acids with an iodine value of 56 were dissolved in 1 1/2 times their weight in a mixture of 92% methanol and 8% water and fractionated with the apparatus described in Example 3 by cooling from 33 ° C to -7 ° C at a cooling rate of 18 ° C per hour and stirring at 200 rpm. Immediately thereafter, it was filtered as above and washed ‘twice as the same solvent, each time using 88% of the original weight of acid. After evaporation of the solvent, 56.1% of the filtrate with an iodine value of 95.2 and 43.9% of the filtrate residue with an iodine value of 5.8 were obtained as a free-flowing granular substance with 92% of the particles having a diameter of about 0.5 mm. .

Claims (15)

A method for enhancing the separation of a solid particulate matter from a liquid fat material in which it is dispersed using e.g. a centrifugal separator and a filter, which separation is obtained by mixing the dispersion in a chamber equipped with a concentric mixer with the chamber, characterized by a smooth profile which extends over the entire depth of the dispersion in the chamber and has a diameter of 1/3 to 2/3 of the diameter of the chamber, wherein a homogeneous mixing is maintained at the rotational speed of the mixer until a substantial amount of particles have aggregated in the fatty material. A method according to claim 1, characterized in that the chamber is at least as deep as the radial width of the fat material remaining in the chamber between the walls of the chamber and the mixer. Method according to Claim 1 or 2, characterized in that the stirrer is rotated at such a speed that a radial velocity gradient of 1 to 250 m / min / m is obtained. Method according to Claim 3, characterized in that the radial velocity gradient is from 10 to 100 m / min / m. Method according to one of the preceding claims, characterized in that the mixer is rotated at a speed of 10 to 100 rpm. Method according to one of the preceding claims, characterized in that the particles contain components of the fatty material which are selectively precipitated when the fatty material is mixed homogeneously. A method according to claim 6, characterized in that the fatty material is cooled to effect precipitation. . · I 11 63055 Method according to one of the preceding claims, characterized in that a temperature difference of less than 10 ° C measured radially is used to cool the fatty material. Process according to Claim 7 or 8, characterized in that the fat is kept at a constant temperature after cooling in order to stabilize the precipitate. Process according to one of Claims 6 to 9, characterized in that 5 to 35% of the fatty matter is blended. 10 63055 Process according to Claim 1, characterized in that the fat is palm oil or a fraction thereof. Process according to Claim 1, characterized in that the fat is soybean oil. Process according to one of the preceding claims, characterized in that a solvent for the fatty substance is present. Process according to one of the preceding claims, characterized in that the solvent is hexane, acetone or nitropropane. Process according to Claim 13, characterized in that the amount of solvent present is 1/2 to 5 parts by weight of the fatty matter. 63055 12