Cryogenic crystallization process for oils and fats for applications in the food, cosmetics and pharmaceutical industries

Abstract

A process for manufacturing solid particles (13), from a liquid or semi-liquid composition (1), in particular from a composition of oil, grease, wax or other fatty compound, employing at least one device (2) for forming a liquid or semi-liquid jet of the product, then a step of total or partial freezing or crystallization of the jet thus formed, characterized by the implementation of the following measures: one or more streams (12) of the composition are produced using the forming device(s), entering the upper part of a reaction chamber (3) and circulating within this reaction chamber from top to bottom; the reaction chamber is supplied with cryogenic liquid (4) to create a cold gas atmosphere within the reaction chamber; the particles formed are recovered in the lower part (5) of the chamber;characterized in that a cutting device is used for the said product stream(s), with a wire or disc (14) rotating at a given and chosen speed, the passage of the wire or disc causing the cutting of substantially cylindrical particles of the product, which are transformed into spherical or substantially spherical particles during their fall within the chamber towards the lower part of the chamber where their recovery takes place (5°. Figure 3;

Description

Title of the invention: Process for the cryo-crystallization of oils and fats for applications in the food, cosmetics and pharmaceutical industries

[0001] The present invention relates to the field of processes and equipment dedicated to the cryo-crystallization of oils and fats or other liquid or semi-liquid fatty compounds, with a high melting point, for applications in the fields of agri-food, cosmetics or pharmaceuticals.

[0002] State-of-the-art cryo-crystallisation equipment is known to make it possible to transform an oil, a grease, a wax or other fatty compound containing a certain proportion of active ingredient into a set of solid particles in the form of powder or beads.

[0003] The following documents illustrate the very abundant and sometimes old literature that has been devoted to this question: EP-919 279, EP-0393 963, US-4 655 047, GB-2 092 880, WO99 / 33555, or US-4 982 577, or even EP-1 285 584.

[0004] In the context of the present invention, we are interested in so-called "mono-dispersed" or "monodispersed" particles, that is to say, particles whose size is substantially the same, not giving rise to the production of aggregations, double or triple particles, or even particles that are too small ("satellites"), particles that are too small which are a major drawback for certain applications, particularly pharmaceutical, and whose elimination is therefore a major issue.

[0005] This physical transformation (into particles) mentioned above is sought after in many fields such as nutrition, animal feed, cosmetics, and pharmaceuticals. It offers numerous advantages such as: • easier dosing of the ingredients in an industrial recipe, • improved product flow, • easy storage, • improved resistance to compaction and mass recovery, • as well as an increase in service life.

[0006] A cryo-crystallization process typically involves atomizing the molten product in a chamber cooled by a cryogenic fluid, typically liquid nitrogen. This causes the particles, which fall freely within the chamber, to cool rapidly until they reach the point of crystallization. The transformation is irreversible, and the collected product remains in a crystalline state as a powder or small beads, depending on the spray technology used in the apparatus.

[0007] The attached [Fig. 1] illustrates, by means of a partial schematic view, the different parts of a cryo-crystallization device typical of the state of the art.

[0008] Let us explain the operation of this equipment: the products previously melted and contained in the tank 1 are conveyed into the injection equipment 2 located in the upper part of an enclosure 3 cooled by means of a liquid nitrogen spray 4, in atomized form or in the form of drops according to the method which has been chosen to fractionate the product to be transformed.

[0009] Remarkably, the cooling energy developed by the liquid nitrogen allows for the almost immediate freezing of the grease particles as they fall into the cooling chamber. The resulting powder or beads are collected frozen in the lower part of the chamber in a collection device 5.

[0010] Two types of implementation of the injection of the molten product are generally distinguished, the choice of which depends on the type of transformation desired (types recalled in [Fig.2] attached).

[0011] The first process ((a) - pneumatic injection) is undoubtedly considered less qualitative than the second ((b), injection called "electro-spray") but allows for significant productivities, typically on the order of 1000 kg / h. On the other hand, the particle size distribution is wide with a non-negligible proportion of fine particles requiring careful filtration of the extracted gas stream, or even an "ATEX" classification of the production installation.

[0012] In demanding fields such as pharmaceuticals or cosmetics, transformation into monodisperse (or mono-dispersed) beads is often required. The formation of fine particles is then avoided by the preferred application of the second process, at the expense of productivity. Indeed, as mentioned, productivity is limited to approximately 200 kg / h, with growth potential limited to the maximum number of needles that can be implanted in the injection head. Furthermore, the system's productivity is sensitive to the surface tension of the product.

[0013] In the case of products with low surface tension, such as surfactants, the product flow rate is limited. This type of injection cannot process products with a surface tension greater than 0.07 N / m, corresponding to highly hydrated products. This sensitivity to the product's surface tension implies different configurations and productivity levels from one product to another, which can be very restrictive for production sites processing different types of products.

[0014] In the prior art, the production of mono-dispersed beads with higher productivity then involves the purchase of several machines, which can hinder investment decisions and the adoption of the technology by the manufacturer.

[0015] As will be seen in more detail below, the present invention proposes to replace the electro-spray device conventionally used until now in cryo-crystallization devices with a more productive device for generating monodisperse beads, while maintaining a high level of quality in the processed product.

[0016] We propose here to implement a process for cutting a liquid jet, for example from a nozzle or a syringe producing this jet, using a wire or rotating disc spinning at high speed (this is sometimes referred to in the industry as "jet cutting").

[0017] The attached [Fig.3] illustrates by means of a partial schematic view the principle of operation In the operation of such a wire cutting method, the following elements can be identified in [Fig.3]: 10: Arrival of the liquid product (composition) to be processed 11: an engine 12: the jet / stream of liquid produced 13: the particles produced downstream of the cutting disc or wire (14).

[0018] The passage of the wire or disc (14) through the liquid jet of product causes the cutting of cylinders which turn into spherical balls during their fall.

[0019] The typical range of ball diameters conceivable with this process typically goes from 0.2 mm to 3 mm, the quantity of balls generated per second depends on the rotation frequency of the cutting wire, generally from 5000 to 10,000 Hz but can go up to 25,000 Hz.

[0020] For example, for a diameter of 3 mm and at the maximum frequency of 25,000 Hz, productivity can reach 1200 kg / h, a value 5 to 6 times higher than that achievable in electro-spray.

[0021] Furthermore, this productivity is not affected by the surface tension of the product, nor by its density or dynamic viscosity. The stated performance can therefore be achieved even for products with very low surface tension, less than 20 mN / m for example for surfactants.

[0022] According to a preferred embodiment of the invention, the cutting device mentioned above is implanted in the upper part of a cryo-crystallisation apparatus, in particular between the tank containing the molten product and the cooling chamber, or in the upper part of this chamber.

[0023] The attached [Fig.4] illustrates by a partial schematic view an example of implementation of the invention with such an implantation of the cutting system within a cryo-crystallizer.

[0024] The nozzle is supplied at a constant flow rate from the pressurized product reservoir, ensuring, by the constant speed rotation of the cutting wire, a very tight ball size distribution.

[0025] Advantageously, as can be seen in [Fig.4], the system can be equipped with one, two or more nozzles for producing a jet 12 of liquid to be treated (cut), Preferentially fed with the same flow rate, the multi-nozzle system increases the number of balls generated per unit of time. The resulting productivity can be high even for ball diameters less than 3 mm.

[0026] The use, according to the invention; of wire or disc cutting in cryo-crystallization constitutes a notable progress compared to the state of the art; it allows the production of monodisperse beads of oils, greases, waxes or other compounds, of diameter greater than mm, in greater quantity and whose quality is at least equivalent to that obtained with prior processes.

[0027] Because indeed, the cooling power provided by the use of a liquid cryogen such as liquid nitrogen allows the complete crystallization of the product over a reduced height, typically around 2 m on state-of-the-art devices, compared to prior art systems equipped with conventional vapor compression refrigeration circuits whose height can reach 5 to 10 meters.

[0028] The present invention relates to a method for manufacturing solid particles from a liquid or semi-liquid composition, in particular from a composition of oil, grease, wax or other fatty compound, employing at least one device for forming a liquid or semi-liquid jet of the product, for example such as from a nozzle or syringe, followed by a step of total or partial freezing or crystallization of the jet thus formed, characterized by the implementation of the following measures: - one or more streams of the composition are produced using the formation device(s), entering the upper part of a reaction chamber and circulating within this reaction chamber from top to bottom; - the reaction chamber is supplied with cryogenic liquid, for example liquid nitrogen, to create a cold gas atmosphere within the reaction chamber; - the particles formed are collected in the lower part of the chamber;

[0029] characterized in that a cutting device for said product streams is implemented, using a wire or disc rotating at a given and chosen speed, the device positioned downstream of the exit of said product streams from said forming device(s), preferably positioned in the upper part of the chamber, the passage of the wire or disc causing the cutting of substantially cylindrical particles of the product, which are transformed into spherical or substantially spherical particles during their fall within the chamber towards the lower part of the chamber where their recovery takes place.

[0030] The present invention also relates to an installation for manufacturing solid particles from a liquid or semi-liquid composition, in particular in starting from a composition of oil, grease, wax or other fatty compound, comprising: - a reaction chamber; - at least one device for forming a liquid or semi-liquid jet of the composition, for example such as from a nozzle or a syringe, a device capable of producing one or more streams of the composition, entering the upper part of the reaction chamber and circulating within this reaction chamber from top to bottom; - means of supplying the reaction chamber with cryogenic liquid, for example liquid nitrogen, to create a cold gas atmosphere within the reaction chamber and thus enable the total or partial freezing or crystallization of the stream(s) thus formed; - means of recovering the particles formed in the lower part of the chamber;

[0031] characterized in that the installation includes a cutting device for said product streams, using a wire or disc capable of rotating at a given and chosen speed, the device positioned downstream of the exit of said product streams from said forming device(s), preferably positioned in the upper part of the chamber, the passage of the wire or disc causing the cutting of substantially cylindrical particles of the product, which are transformed into spherical or substantially spherical particles during their fall within the chamber towards the lower part of the chamber where they are recovered by means of said recovery means.

Claims

Demands

1. A process for manufacturing solid particles (13), from a liquid or semi-liquid composition (1), in particular from a composition of oil, grease, wax or other fatty compound, employing at least one device (2) for forming a liquid or semi-liquid jet of the composition, for example such as from a nozzle or syringe, then a step of total or partial freezing or crystallization of the jet thus formed, characterized by the implementation of the following measures: - one or more streams (12) of the composition are produced using the formation device(s), entering the upper part of a reaction chamber (3) and circulating within this reaction chamber from top to bottom; - the reaction chamber is supplied with cryogenic liquid (4), for example liquid nitrogen, to create a cold gas atmosphere within the reaction chamber; - the particles formed are collected in the lower part (5) of the chamber; characterized in that a cutting device is used for the said product stream(s), using a wire or disc (14) rotating at a given and chosen speed, the device being positioned downstream of the exit of said product stream(s) from said forming device(s), preferably positioned in the upper part of the chamber, the passage of the wire or disc causing the cutting of substantially cylindrical particles of the product, which are transformed into spherical or substantially spherical particles during their fall within the chamber towards the lower part of the chamber where their recovery takes place (5).

2. A plant for manufacturing solid particles (13), from a liquid or semi-liquid composition (1), in particular from a composition of oil, grease, wax or other fatty compound, comprising: - a reaction chamber (3); at least one device for forming a liquid or semi-liquid jet liquid of the composition, for example such as from a nozzle or syringe, capable of producing one or more streams (12) of the composition, entering the upper part of the reaction chamber and circulating within this reaction chamber from top to bottom; - means of supplying the reaction chamber with cryogenic liquid (4), for example liquid nitrogen, to create a cold gas atmosphere within the reaction chamber and thus enable the total or partial freezing or crystallization of the stream(s) thus formed; - means of recovery (5) in the lower part of the chamber of the particles formed; characterized in that the installation includes an apparatus (14) for cutting said composition streams, using a wire or disc capable of rotating at a given and chosen speed, apparatus positioned downstream of the outlet of said product streams of said formation device(s), preferably positioned in the upper part of the chamber, the passage of the wire or disc causing the cutting of substantially cylindrical particles of the product, which are transformed into spherical or substantially spherical particles during their fall within the chamber towards the lower part of the chamber where they are recovered by means of said recovery means (5).