WO2018046490A1

WO2018046490A1 - Vertically-extending curdling apparatus

Info

Publication number: WO2018046490A1
Application number: PCT/EP2017/072228
Authority: WO
Inventors: Stefano Tomatis
Original assignee: Cmt Costruzioni Meccaniche E Tecnologia Spa
Priority date: 2016-09-06
Filing date: 2017-09-05
Publication date: 2018-03-15
Also published as: IT201600089845A1

Abstract

A tank (12) adapted to be filled with milk and a coagulant accommodates a curd harp-slicer and agitator means which are supported by a first motorized vertical rotating shaft (26) which, in turn, is supported in an eccentric position by a second motorized vertical rotating shaft (28); the agitator means (38, 40, 46, 48) are supported so that they can move between an inactive position of reduced interaction with the material in the tank, with the first vertical shaft (26) rotating in a cutting direction, and an active position of greater interaction with the material in the tank, with the first vertical shaft (26) rotating in an opposite, agitation direction.

Description

VERTICALLY-EXTENDING CURDLING APPARATUS

The present invention relates to a vertically-extending curdling apparatus.

As is known, curd is obtained by adding rennet to heated milk, so as to cause the coagulation of particles of casein until a gelatinous mass is formed, in which bubbles of whey remain trapped.

In industrial production, typically the milk is coagulated in tanks that have a profile that extends about a vertical axis. In the tank there is normally a curd harp-slicer, which rotates about a vertical axis in order to break up the coagulated mass and free the whey trapped inside it. The curd, which is heavier, is deposited on the bottom while the whey, which is lighter, rises to the surface.

As is well known to the person skilled in the art, in order to prevent the onset of phenomena of stratification of the fats and proteins contained in the milk, which have different specific weights, it is necessary to limit the height extension of the tank. This evidently compromises the productive capacity of the apparatus, especially in consideration of the fact that only 10-20% of the milk is converted to curd, while the remaining part becomes whey.

In order to increase the productive capacity, horizontal coagulators are known, e.g., "cradle" coagulators like the one described in EP 0451373, or "cylindrical" coagulators like the one described in EP 0702893.

As will be easily grasped, the horizontal extension of conventional coagulators, such as those described above, is not satisfactory from a logistical point of view, because it does not allow efficient use to be made of the height space available in dairies.

Furthermore, as is well known to the person skilled in the art, with horizontally-extending coagulators there is often difficulty in extracting all the curd deposited on the bottom, with consequent losses of product and drawbacks from a hygienic point of view. Furthermore, in conventional apparatuses, once coagulation is complete, the curd mixed with the whey has to be transferred to an apparatus for draining and ripening. The latter can be constituted, e.g., by an array of drainer/ripeners, such as the one described in EP 1175826, or by a long motorized ripening belt, which slowly conveys the curd toward the kneading stations so that, during the travel, the curd ripens until it reaches the desired acidity level (pH) for the subsequent kneading operations.

However, the arrays of drainers/ripeners mentioned above are also very cumbersome, with further increase of the surface occupied by the system overall.

Motorized ripening belts also have the drawback that they are very cumbersome. Furthermore, since they have to transport great masses of material, their operation requires a high energy and mechanical cost. In addition, given the great length of the belts, which is required in order to receive all the production of curd and allow it to ripen for the necessary hours, the washing operations are very wasteful in terms of time and they consume a great deal of hot water by virtue of the extensive surfaces to be washed, with consequent increase of production costs.

In the past curdling apparatuses have been proposed which were provided with a vertically-extending cylindrical tank, in which a curd harp- slicer and agitator means were accommodated.

In some cases the curd harp-slicer and the agitator means rotated about respective fixed vertical axes, which were eccentric with respect to the axis of the cylindrical tank. In other cases, the curd harp-slicer and the agitator means both rotated about the axis of the tank.

However, the above mentioned vertically-extending curdling apparatuses have not achieved widespread adoption because the agitator means could not move and evenly mix all the milk present in the tank. As is well known to the person skilled in the art, uneven mixing leads to a non- homogeneous distribution of the fats and of the proteins in the curd, with associated problems of stratification.

The aim of the present invention is to provide a vertically-extending curdling apparatus that makes it possible to take full advantage of the height space available in dairies, while at the same time ensuring a homogeneous distribution of the fats and of the proteins in the coagulated mass so as to prevent phenomena of stratification.

Within this aim, an object of the present invention is to provide an apparatus in which the curd can also be left to ripen until the desired level of acidity is reached, so as to save the costs and the encumbrances of an external ripening apparatus.

The above aim and this and other objects, which will become clear from the description that follows, are achieved by the curdling apparatus having the characteristics recited in the appended claim 1, while the appended dependent claims define other characteristics of the invention which are advantageous, although secondary.

Now the invention will be described in greater detail, with reference to a preferred but not exclusive embodiment thereof, which is illustrated for the purposes of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a side view of the curdling apparatus according to the invention;

Figure 2 is a cross-sectional view of Figure 1 taken along the line II-

II;

Figure 3 is a cross-sectional view of Figure 2 taken along the line III- III;

Figure 4 is an axial cross-sectional perspective view of the curdling apparatus according to the invention;

Figure 5 is a perspective view of an isolated component of the curdling apparatus according to the invention;

Figure 6 is a side view of the component of Figure 5 in a first operating configuration;

Figure 7 is a side view of the component of Figure 5 in a second operating configuration.

With reference to Figures 1-7, a curdling apparatus 10 comprises a tank 12 that is adapted to be filled with milk and rennet. In a manner that is conventional per se, the rennet will make the milk ferment, turning it into a gelatinous, coagulated mass with bubbles of whey trapped inside it.

The tank 12 is provided with a perimetric wall 14 that extends around a vertical axis and is preferably cylindrical.

The perimetric wall 14 is closed by a bottom 16 at its lower end and by a lid 18 at its upper end, and rests on feet 20 welded to the bottom 16.

The bottom 16 has a profile that is substantially frustum- shaped, tapering downward and culminating in a slightly off-center drainage outlet 22 (Fig. 2). The lid 18 also has a profile that tapers upward.

The tank 12 accommodates a curd harp-slicer 25 supported by a first motorized vertical rotating shaft 26 which, in turn, is supported in an eccentric position by a second motorized vertical rotating shaft 28 arranged coaxially in the tank 12, by way of two radial arms 30a, 30b.

The curd harp-slicer is composed of two sectors of harp-slicer 32, 34 which protrude in the manner of a flag from the first shaft 26 in diametrically opposite directions.

Each one of the harp-slicer sectors 32, 34 comprises a group of oblique blades 32a, 34a which are welded to a frame 32b, 34b that, in turn, is clamped to the first shaft 26. Advantageously, the blades have a cutting edge and an opposite, non-cutting edge that operate alternately on the basis of the direction of rotation of the first shaft 26.

The harp-slicer carries integrally agitator means which, according to the invention, can move between an inactive position of minimum interaction with the material in the tank, with the first shaft 26 rotating in the cutting direction of the harp-slicer, and an active position of maximum interaction with the material in the tank, with the first shaft 26 rotating in an opposite, agitation direction.

In the embodiment described herein, the agitator means comprise a pair of lower paddles 38, 40 which are pivoted to the first shaft 26 below the harp-slicer 25 in diametrically opposite positions and in a configuration that protrudes on the opposite side from the rotary cutting direction of the first shaft 26, so as to swing between the inactive position and the active position by fluid-dynamic interaction with the material in the tank.

In the example shown here, the lower paddles 38, 40 rotate about respective lower pivoting axes A, B that are horizontal and, preferably, perpendicular to the plane on which the harp-slicer 25 lies.

In particular, in the embodiment shown here, the lower pivoting axes

A, B lie on a plane that contains the axis of the first shaft 26 and is perpendicular to the plane containing the harp-slicer 25.

Preferably, in the inactive position the lower paddles 38, 40 are inclined downward from 10° to 30° with respect to the horizontal (Figure 6), while in the active position they are inclined downward from 40° to 70° with respect to the horizontal, e.g. by 50° (Figure 7), such positions being delimited by respective limiters (not shown).

Advantageously, the lower paddles 38, 40 carry integrally respective rows of blades 42, 44 which are arranged so as to assume an operative position with the lower paddles in the inactive position, and a non-operative position with the lower paddles in the active position.

In this embodiment, the blades 42, 44 are deployed in a comb pattern and protrude downward from the lower pivoting axis A, B so as to swing on the opposite side of the harp-slicer 25 with respect to the lower paddles 38,

40.

Preferably, the lower paddles 38, 40 form, with the blades 42, 44 an angle comprised between 90° and 70°, advantageously 80°.

Therefore, with the lower paddles 38, 40 in the inactive position and the blades 42, 44 in the operative position, the latter protrude vertically downward and their cutting action is maximized (Figure 7); with the lower paddles 38, 40 in the active position and the blades 42, 44 in the non- operative position, the latter protrude obliquely on the opposite side from the blades and their cutting action is minimized (Figure 6).

The agitator means advantageously also comprise a pair of upper paddles 46, 48 which are pivoted to the first shaft 26 in diametrically opposite positions at an intermediate height of the harp-slicer 25 in a configuration that protrudes on the opposite side from the cutting direction, so as to swing between the inactive position and the active position by fluid- dynamic interaction with the material in the tank.

In the example shown here, the upper paddles 46, 48 rotate about respective upper pivoting axes C, D that are horizontal and parallel to the plane on which the harp-slicer 25 lies.

Preferably, in the inactive position the upper paddles 46, 48 are substantially horizontal (Figure 6), while in the active position they are preferably inclined downward from 10° to 70° with respect to the horizontal, e.g. by 20° (Figure 7), such positions being delimited by respective limiters (not shown).

The first vertical rotating shaft 26 is entrained in rotation about its own axis by a first gearmotor 50 mounted over the lid 18, by way of a chain transmission 52 (shown only schematically with a dotted line in Figure 5). The first gearmotor is provided with a hollow driving shaft 54.

The upper end of the second vertical rotating shaft 28 passes through the hollow driving shaft 54 and is functionally connected to a second gearmotor 56 mounted over the first.

The perimetric wall 14 is provided with an inspection hatch 58 located proximate to the lid 18 and with an inspection porthole 60 located proximate to the bottom 16. Furthermore, the perimetric wall 14 is provided with a lower milk loading inlet 62 arranged proximate to the bottom 16, an upper milk loading inlet 64 arranged on the lid 18, and a sweet whey offtake valve 66 arranged at an intermediate height between them.

The lid 18 is provided with a rennet loading conduit 68, preferably toroidal, which extends around the axis of the tank 12.

The milk-loading inlets, the sweet whey offtake valve and the rennet- loading conduit are shown only schematically in Figure 3 with dotted lines.

The perimetric wall 14 can be covered with a thermal shell constituted by a double wall with an interspace into which steam or hot water can be introduced, and one or more insulating layers. Such coverings are not shown here and are not described in further detail for the sake of simplicity, since they are in common use in the sector.

Operation of the apparatus described herein is based on alternating agitation phases and cutting phases, which are linked to the direction of rotation of the two shafts.

In particular, in the agitation phases the harp-slicer 25 rotates about the axis of the first shaft 26 in the opposite direction to the cutting direction (clockwise direction in Figure 2), with the paddles 38, 40, 46, 48 being positioned obliquely by fluid-dynamic interaction with the material in the tank (Figure 7), and also about the axis of the second vertical rotating shaft 28 in the same direction of rotation. In these steps, the oblique position of the paddles produces a mixing of the material in the tank, while the cutting action of the harp-slicer 25 and of the blades 38, 40 is substantially deactivated.

In particular, the first paddle 38 and the second paddle 40 prevent buildups of material at the bottom of the tank 12, while the third paddle 46 and the fourth paddle 48 perform a mixing action at an intermediate level.

In the cutting phases, the directions of rotation of the first shaft 26 and of the second shaft 28 are reversed (anticlockwise direction in Figure 2). In these phases, the paddles 38, 40, 46 and 48 are positioned more or less horizontally by fluid-dynamic interaction with the material in the tank (Figure 6), so that the mixing action is deactivated, while the harp-slicer 25 and the blades 42, 44, the latter being arranged vertically, perform a cutting action on the material.

Operation of the machine is preferably managed by a Programmable Logic Controller (PLC), not shown, the design of which is part of the normal knowledge of the person skilled in the art and therefore is not described herein.

Below is an example of use of the apparatus 10 according to the invention.

First, the milk is introduced into the tank 12 through one of the milk- loading inlets 62, 64.

After this, a first phase of agitation is carried out, so as to move the milk and evenly distribute the fats and the proteins contained in it, as well as any process additives such as enzymes and the like, thus preventing phenomena of stratification.

It needs to be emphasized that in the agitation phase the second shaft 28 could also rotate in the opposite direction with respect to what is described above, or it could perform an alternating rotation with agitation times and speeds that can be set by the PLC.

Therefore, rennet is added through the rennet-loading conduit 68, while the agitation phase is still active. Preferably, the agitation action continues until a few minutes before the rennet begins to take hold, e.g., 4 or 5 minutes; after such period, as is well known to the person skilled in the art, the risk of stratification has passed.

At this point, the agitation is stopped and the milk is left to coagulate fully until a gelatinous mass is formed, inside which bubbles of whey are trapped.

Once coagulation is complete, a cutting phase is carried out so as to break the gelatinous mass and free the whey which, being lighter than the coagulated milk, tends to rise to the surface. In this phase, the rotation speed of the shafts can be kept relatively low.

Thereafter, the rotation speed of the harp-slicer can optionally be increased until the desired granulometry is reached.

After this, a new phase of agitation is carried out, so as to mix the curd thus produced.

Once the solid mass has been separated from the whey, the level of the solid mass will be just below the whey offtake valve 66, while the level of the whey will be such as to fill the tank 12 almost completely. To extract the whey from the tank 12, the whey offtake valve 66 is opened.

Once the whey has been separated, the curd can be left to ripen inside the tank until the desired level of acidity for the subsequent kneading operations has been reached. Once the desired level of acidity has been reached, cold water can be introduced in order to stop the acidification, according to principles of chemistry that are well known to the person skilled in the art.

During the ripening, a new agitation phase can be carried out at low speed, so as to keep the mass in motion without further changing the granulometry.

The curd can then be extracted through the drainage outlet 22 by way of a conventional pump (not shown) and sent to draining and kneading stations downstream.

The height extension of the apparatus according to the invention entails considerable advantages in terms of logistics, since it makes it possible to efficiently use the volumes available in dairies.

At the same time, according to the set aims, the rotary/orbital movement of the harp-slicer and of the paddles inside the cylindrical tank makes it possible to uniformly mix all of the mass of curd and to therefore obtain an even distribution of the fats and of the proteins without the phenomena of stratification arising.

Furthermore, since the two rotating vertical shafts 26, 28 are moved by respective independent motors, the apparatus according to the invention offers a high flexibility of use in relation to the various process parameters.

Also, the possibility of allowing the curd to ripen inside the tank 12, without moving any material, entails a considerable saving in plant cost and in encumbrances.

A preferred embodiment of the invention has been described, but obviously the person skilled in the art may make various modifications and variations within the scope of protection of the claims.

In particular, the number of paddles and/or of harp-slicer sectors can be increased or reduced according to requirements. For example, the harp- slicer can be made up of three or more sectors, angularly spaced apart about the axis of the first shaft, optionally on different levels.

Furthermore, the lower and upper paddles can be arranged differently, e.g., with the axes slightly oblique instead of horizontal.

The disclosures in Italian Patent Application No. 102016000089845

(UA2016A006372) from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A curdling apparatus, comprising a tank (12) adapted to be filled with milk and a coagulant and accommodating a curd harp- sheer and agitator means supported by a first motorized vertical rotating shaft (26), which in turn is supported in an eccentric position by a second motorized vertical rotating shaft (28), characterized in that said agitator means (38, 40, 46, 48) are supported so that they can move between an inactive position of reduced interaction with the material in the tank, with the first vertical shaft (26) rotating in a cutting direction, and an active position of greater interaction with the material in the tank, with the first vertical shaft (26) rotating in an opposite, agitation direction.

2. The apparatus according to claim 1 , characterized in that said first vertical shaft (26) and said second vertical shaft (28) are turned by respective mutually independent drive means (50, 56).

3. The apparatus according to claim 1 or 2, characterized in that said agitator means comprise paddle means (38, 40, 46, 48) which are pivoted to said first shaft (26) in a configuration that protrudes on the opposite side from the rotary cutting direction so as to swing between said inactive position and said active position by fluid-dynamic interaction with the material in the tank.

4. The apparatus according to claim 3, characterized in that said paddle means comprise at least one lower paddle (38, 40) which is pivoted to the first shaft (26) below said harp-slicer (25) about a respective lower pivoting axis (A, B).

5. The apparatus according to claim 4, characterized in that said lower pivoting axis (A, B) is substantially horizontal.

6. The apparatus according to claim 4 or 5, characterized in that said lower pivoting axis (A, B) is substantially perpendicular to the plane on which the harp-slicer (25) lies.

7. The apparatus according to one or more of claims 4-6, characterized in that said lower paddle (38, 40) integrally supports a row of blades (42, 44) that are arranged so as to assume an operative position with the lower paddle (38, 40) in said inactive position, and a non-operative position with the lower paddle in said active position.

8. The apparatus according to claim 7, characterized in that said blades (42, 44) are arranged so as to swing on the opposite side of the harp- slicer (25) from said lower paddle (38, 40).

9. The apparatus according to one or more of claims 4-8, characterized in that it comprises a pair of said at least one lower paddle (38, 40), which are pivoted to said first vertical shaft (26) in diametrically opposite positions.

10. The apparatus according to claim 3, characterized in that said paddle means comprise at least one upper paddle (46, 48), which is pivoted to said first shaft (26) at an intermediate height of the harp-slicer (25) about a respective upper pivoting axis (C, D).

11. The apparatus according to claim 10, characterized in that said upper pivoting axis (C, D) is horizontal.

12. The apparatus according to claim 10 or 11, characterized in that said upper pivoting axis (C, D) is parallel to the plane on which the harp- sheer (25) lies.

13. The apparatus according to one or more of claims 10-12, characterized in that it comprises a pair of said upper paddles (46, 48), which are pivoted to said first vertical shaft (26) in diametrically opposite positions.