INTERMEDIATE OR POST-CRYSTALLIZER FOR USE IN COMBINATION WITH TUBULAR COOLERS WITH SCRAPERS FOR THE CRYSTALLIZATION OF MOLTEN OR EMULSIFIED FATS

Abstract: In a crystallizer for use as described, comprising a statio­ nary cylinder (1) with a shaft (2) rotating therein, the cylinder and the shaft being provided with radial rods (3, 4, 5) engaging between one another, each of the rods is provided at its free end with a trans­ verse rod (10, 11, 12) which extends axially along the surface of the shaft and the cylinder, respectively, and thereby keeps these surfa­ ces clean. The radial rods (3, 4, 5) can therefore be arranged at a so great mutual distance that the stirring effect can be reduced with­ out jeopardizing the cleaning.

Description: The invention relates to an intermediate or post-crystallizer for use in combination with tubular coolers with scrapers for the crystallization of molten or emulsified fats, said crystallizer comprising a stationary cylinder with a shaft rotating therein, the cylinder being provided in a number of axial positions with inwardly directed rods extending to the vicinity of the surface of the shaft, the rotating shaft being provided in axial positions displaced from those previously mentioned with outwardly directed rods extending to the vicinity of the inner wall of the cylinder. The reason for using intermediate or post-crystallizers in plants of the kind referred to is that in many cases it is not possible to obtain a satisfactory crystallization, by which a molten fat or an emulsion of a fat in water is converted to a solid, semi-solid or pla­ stic or high-viscous product, by means of tubular coolers alone. E. g. this will often be the case in the crystallizing treatment of butter, palm butter, lard, margarine and mayonnaise. In order to start the crystallization process a shock cooling in a tubular cooler is required, but if the mass is allowed to remain too long in the tubular cooler, it is likely to become under-cooled, because the formation of crystals and thereby the liberation of crystallization heat cannot keep pace with the cooling. The mass is therefore fed forward to an intermediate or post-crystallizer of the kind referred to, in which it is intended to allow the crystallization process to continue without any external influence, apart from the stirring which is required to keep the mass homogeneous and to avoid the formation of cavities. It is, however, also necessary to prevent the mass from depositing on the inner surface of the cylinder or the surface of the shaft, and in the known crystallizers the rods have therefore been arranged so close together that in their combined effect they sweep the said surfaces so to speak in their whole extension. Hereby there is a risk that the product is excessively worked, which may impede the crystallization. The effect of the crystallizer is therefore considerably less than was to be expected from its volume, and the product is likely to be excessively worked. It is the object of the invention to remedy this drawback, and with this in view, according to the invention, the rods of the cy­ linder are provided at their ends with transverse rods extending along the surface of the shaft at a small distance therefrom between the axial positions of the rods of the shaft, while the rods of the shaft are similarly provided at their ends with transverse rods extending along the surface of the cylinder at a small distance therefrom between the axial positions of the rods of the cylinder and between the posi­ tions of the outermost ones of the rods of the cylinder and the end walls of the cylinder. Hereby the advantage is obtained that each of the rods cleans an area of a size corresponding to the length of the transverse rod so that the number of rods required will be much less, and the working of the product will be considerably reduced. The crystallizer therefore becomes more efficient. The invention will in the following be explained in further detail with reference to the drawing, which shows a longitudinal sec­ tion through a crystallizer according to one embodiment of the inven­ tion with the shaft in a certain angular position relative to the cylin­ der. In the drawing, 1 is a cylinder having end walls 6 and 7. In the cylinder there is mounted a shaft 2, which is coupled to a driving mechanism, not shown, by means of which the shaft is caused to rotate at low speed. The product to be crystallized is supplied through an opening 8 in the end wall 6 and is discharged through an opening 9 in the end wall 7. On the inner wall of the cylinder a number of stationary rods 5 are arranged, each of which is provided with a transverse rod 10 extending along the surface of the shaft 2 at a short distance therefrom. On the shaft 2 a number of rotating rods 3 and 4 are arranged, each being provided with a transverse rod 11 and 12, respectively. The rods 3 are located immediately adjacent the end walls 6 and 7, respectively, of the cylinder, and their transverse rods 11 extend along the inner surface of the cylinder at a short distance therefrom over a length from the end wall 6 and 7, respectively, substantially to the axial position of the next one of the stationary rods 5. The transverse rods 12 of the rods 4 extend substantially between the axial positions of two successive ones of the stationary rods 5. The transverse rods 10 of the rods 5 extend substantially between the axial positions of two successive ones of the rotating rods 3 and 4, respectively. As will be seen, the transverse rods 10, in their combined effect, sweep the rotating surface of the shaft 2 in practically the whole of its length, while the transverse rods 11 and 12 of the rotat­ ing rods 3 and 4 sweep the inner surface of the cylinder practically in the whole of its length. Thereby the inner surface of the cylinder and the surface of the shaft are kept clean in an efficient manner by means of a very small number of rods so that it becomes possible to limit the stirring of the mass caused by the rods to exactly the mini­ mum, which is required to keep the mass homogeneous and devoid of cavities.

Claims: Intermediate or post-crystallizer for use in combination with tubular coolers with scrapers for the crystallization of molten or emul­ sified fats, said crystallizer comprising a stationary cylinder (1) with a shaft (2) rotating therein, the cylinder (1) being provided in a number of axial positions with inwardly directed rods (5) extending to the vicinity of the surface of the shaft (2), the rotating shaft (2) being provided in axial positions displaced from those previously mentioned with outwardly directed rods (3, 4) extending to the vicini­ ty of the inner wall of the cylinder (1), characterized in that the rods (5) of the cylinder (1) are provided at their ends with transverse rods (10) extending along the surface of the shaft (2) at a small distance therefrom between the axial positions of the rods (3, 4) of the shaft, while the rods (3, 4) of the shaft are similarly provided at their ends with transverse rods (11, 12) extending along the surface of the cylinder at a small distance therefrom between the axial positions of the rods (5) of the cylinder and between the posi­ tions of the outermost ones of the rods (5) of the cylinder and the end walls (6, 7) of the cylinder.

Inventors: LANGE, CHRISTIAN
Applicants: GERSTENBERG & AGGER A/S
Application year: 1986
Main classification: A23D3
IPC codes: A23D9, B01D9, A23D7