WO2014096689A1

WO2014096689A1 - Device for generating ice, in particular in the form of flakes, using a dual-wall cylindrical exchanger with a plurality of connections

Info

Publication number: WO2014096689A1
Application number: PCT/FR2013/053145
Authority: WO
Inventors: Bruno GEFFROY; Didier NORJOUX
Original assignee: Gea Réfrigération France
Priority date: 2012-12-21
Filing date: 2013-12-17
Publication date: 2014-06-26
Also published as: FR3000184B1; FR3000184A1

Abstract

The invention relates to a device for generating ice, in particular ice in the form of flakes, comprising: a dual-wall exchanger (1) extending between an upper end (10) and a lower end (11), and having an inner wall (13) and an outer wall (12) between which a coolant fluid circulates, the inner wall (13) having a cylindrical shape; a mechanical assembly (2), (20), (21), (22), (23) mounted inside the exchanger, intended to unstick the ice formed on the inner wall, characterized in that said inner (13) and outer (12) walls are connected, between said upper (10) and lower (11) ends, by a plurality of connections (3) between which the coolant fluid circulates, the inner wall (13) being essentially smooth.

Description

Ice generating device, in particular in the form of flakes, using a double-walled cylindrical exchanger having a plurality of connections.

The field of the invention is that of the design and manufacture of heat exchangers, in particular those intended to produce ice. More specifically, the invention relates to a device for generating ice in the form of flakes, grains or bi-phasic, implementing a cylindrical exchanger (designated by the term "exchanger" in the following description) double wall defining a circulation space for a refrigerant or coolant.

According to a conventional design, a device for producing ice in the form of flakes comprises:

- An exchanger on the inner wall of which is flowing water which will freeze in contact with the inner wall; a mechanical assembly contained inside the exchanger, and intended to take off the ice formed on the inner wall.

Currently, the exchanger consists of a double wall, namely an inner wall and an outer wall. The two walls form between them an annular space on the height of the exchanger, inside which is circulated a refrigerant capable of sufficiently cool the inner wall so that the water is transformed into ice in contact with this wall.

The mechanical assembly is constituted by a milling cutter, mounted generally free to rotate on an axis carried by a frame rotatably mounted about a central axis, motor means being provided for rotating the frame continuously. The cutter has a height corresponding substantially to that of the inner wall. It is mounted to come off the ice formed on this wall.

According to such a design, a perfect operation of the device is obtained with an internal wall having the following characteristic:

the inner wall has a smooth surface; - The inner wall has a circular section of constant diameter over its entire height, thus providing it with a cylindrical shape.

With such an inner wall, an optimal effect of the milling cutter against the inner wall is obtained.

Of course, the exchangers of this type must also meet a number of requirements, including:

- involve a low charge of refrigerant or coolant;

- be consistent with food contact;

- comply with the regulatory texts in force, particularly the Pressure Equipment Directive;

- involve a service pressure compatible with the fluids commonly used in the cold industry;

- show high performance;

- can be easily manufactured, at low cost and in a short time.

Of course, the refrigerant or coolant used is critical in achieving the performance of the device.

Traditionally, the refrigerants used are halogenated or natural fluids (ammonia-NH3) which generate operating pressures of the order of 20 bars. The devices, in particular the exchangers, are therefore designed to have a mechanical strength adapted to such pressure.

However, the environmental constraints and the evolution of the refrigerants lead to the use of natural fluids (carbon dioxide) which cause much higher pressures, of the order of 40 bars.

However, degradations of the exchangers have been observed with the devices of conventional design, in particular under the effect of these pressures. In practice, it has been found that the inner wall deforms towards the inside of the exchanger, which hinders the proper functioning of the cutter.

There is therefore a need to satisfy this new constraint, and the objective of the invention is to provide an ice-generating device adapted to pressures of up to 40 bars and more.

The invention also aims to provide such a device that meets the conventional requirements, especially in that it can be easily manufactured at low cost and in short time.

These objectives, as well as others which will appear later, are achieved thanks to the invention which relates to a device for generating ice, in particular ice in the form of scales, comprising:

- A double-walled exchanger extending between an upper end and a lower end, and having an inner wall and an outer wall between which circulates a refrigerant or coolant, the inner wall having a cylindrical shape;

- A mechanical assembly mounted inside the exchanger for detaching the ice formed on the inner wall;

The device according to the invention is characterized in that said inner and outer walls are connected, between said upper and lower ends, by a plurality of connections between which the refrigerant or coolant circulates, said inner wall being substantially smooth and the inner wall having a resistance to deformation greater than that of the outer wall.

Thus, thanks to the invention, there is obtained a double wall heat exchanger adapted to withstand pressures generated by the refrigerant substantially greater than those supported by the exchangers of the prior art.

The distribution of the connections between the inner and outer walls makes it possible to obtain optimum circulation of the refrigerant between the two walls. In addition, the inner face of the exchanger can not deform inwardly since it is integral with the outer wall, this thanks to the plurality of connections according to the invention.

In addition, such a design does not take place to the detriment of the good circulation of the refrigerant. On the contrary, the surface temperature of the inner wall is homogeneously provided, which leads to the formation of a good quality ice and therefore to optimum performance of the device.

It is noted that these advantages are obtained thanks to the invention while overcoming the difficulty related to the operating principle of such a device, in that it retains an essentially smooth inner wall so that the mechanical assembly can act on this device. wall effectively when taking off the formed ice.

It has also been found another advantage of the invention: the double wall formed according to the invention can significantly reduce the volumes of refrigerant used, this of course for the same ice production capacity of the exchanger.

Moreover, the invention makes it possible to produce the double wall of the exchanger by a simple and inexpensive method, involving the deformation of the outer wall without the deformation of the inner wall (which remains smooth), as will be explained more in detail later.

According to a preferred solution, said bonds consist of soldering points.

According to another conceivable solution, said links are constituted by weld lines, which can be arranged according to one and / or the other of the following directions:

- horizontal;

- vertical;

- oblique.

Whatever the realization of the connection by welding (dots or lines), the connections between the two walls can be obtained by inexpensive and proven industrial techniques, allowing perform welds at high speeds, for example using welding robots.

Advantageously, said links are regularly distributed on the one hand on the circumference of the walls and / or on the other hand on the height of the walls.

Of course, the distribution of the links may vary as much as necessary, in particular depending on the capacity of the ice generating device and therefore the expected performance.

According to one conceivable alternative, said links are divided into zones of different densities so as to create different head losses.

According to a first conceivable variant, the links are aligned horizontally and / or vertically.

According to a second conceivable variant, said links are arranged in staggered rows.

In this case, the inner wall preferably has a thickness greater than that of the outer wall.

Other features and advantages of the invention will appear more clearly on reading the following description of two preferred embodiments of the invention, given by way of a simple illustrative and nonlimiting example, and the appended drawings among which:

- Figure 1 is a partial sectional view of an ice generating device of the type to which the invention applies;

- Figure 2 illustrates in section a double wall of a device according to a first embodiment of the invention;

- Figure 3 illustrates in section a double wall of a device according to a second embodiment of the invention;

- Figure 4 schematically illustrates an exchanger with a first example of distribution of the connections between the inner and outer walls; - Figure 5 schematically illustrates an exchanger with a second example of distribution of the connections between the inner and outer walls.

Referring to Figure 1, there is described a device for generating ice, in particular ice in the form of scales, of the type to which the invention applies.

As illustrated by this figure, an ice generating device comprises:

- A double-walled exchanger 1, extending between an upper end 10 and a lower end 11;

a mechanical assembly mounted inside the exchanger. The double wall of the exchanger comprises an outer wall 12 and an inner wall 13 between them a circulation space for a refrigerant.

The exchanger 1 is made so that its inner wall 13 has a cylindrical shape.

A conduit 140 constitutes a refrigerant inlet duct inside the circulation space 14 between the outer wall 12 and the inner wall 13. A duct 141 constitutes a refrigerant outlet duct from the space 14 of circulation.

Conventionally, the refrigerant is introduced into the space 14 via the conduit 140 in the liquid phase.

It circulates inside the space 14 by carrying out a heat exchange with in particular the inner wall 13 of the exchanger. This heat exchange causes the passage of the refrigerant from a liquid phase to a gas phase. The gaseous phase is recovered using the conduit 141.

The exchanger can be powered:

- refrigerant by pump or expander; - heat transfer fluid by pump.

The mechanical assembly inside the exchanger comprises: a helical cutter 2 mounted free to rotate on a vertical shaft;

- A support frame 21, carrying the shaft 20 and the mill 2, integral with a central shaft 22;

- Motor means 23 for rotating the frame 21.

The central shaft 22 of the mechanical assembly is mounted coaxially with the central axis of the inner wall 13.

The operation of such a device is as follows:

- The inner wall 13 of the exchanger 1 is sprayed with a liquid to be frozen;

- In contact with the inner wall, the liquid freezes;

- The ice formed by the liquid frozen on the surface of the inner wall 13 is peeled off by the cutter 2 (mounted so that it is flush with the inner wall 13);

- the ice, in the form of scales, drops by gravity at the base of the exchanger.

The invention therefore applies to a device of this type, with the difference that, contrary to what is illustrated in FIG. 1, the inner 13 and outer 12 walls are, according to the principle of the invention, interconnected. by a plurality of links.

These connections are provided between the upper end 10 and the lower end 11 of the exchanger. More specifically, these links are distributed over the height of the exchanger at which the refrigerant exerts a pressure. The connections between the internal exchanger 13 and the external exchanger 12 are therefore distributed over the height of the exchanger extending between the duct 140 and the duct 141.

It is noted that the double wall of the exchanger is made such that the inner wall 13 has a smooth or substantially smooth surface.

According to a first embodiment illustrated in FIG. 2, the double wall has an asymmetrical profile. According to this embodiment, the inner wall 13 is cylindrical in shape and has a smooth surface inside the exchanger. It also has a straight section in longitudinal section, whereas according to this same section, the outer wall 12 has a plurality of bends 120 extending between the connections 3 connecting the inner wall 13 and the outer wall 12.

According to the example illustrated in FIG. 4, the links 3 connecting the inner and outer walls define four to four substantially square zones within which the berms 120 are inscribed. The bumps communicate, of course, with each other so that the refrigerant can flow between the links 3 as illustrated by the arrows F1, F2 and F3.

According to the principle of the invention illustrated in FIG. 2, the inner wall has a greater resistance to deformation than that of the outer wall. To achieve this, the outer wall may have a thickness less than that of the inner wall.

As an indication, the inner and outer walls are both made of a stainless steel material.

It is of course possible to use other materials, for example for specific applications, such as titanium, carbon steel ...

To obtain the double wall heat exchanger as shown in FIG. 2, the procedure is as follows:

a sheet of stainless steel of a first thickness is disposed against a second stainless steel sheet of a second thickness smaller than the first, the two sheets being flat (the first sheet being intended to constitute the inner wall while the second sheet is intended to constitute the outer wall of the exchanger);

a plurality of connections are made between the two sheets, for example by a laser welding technique; the assembly obtained is rolled in the form of a cylinder, a welding operation being performed to maintain the shape of the cylinder;

the pipes connecting to the refrigerant circuit are then installed (which leads in practice to the establishment of the ducts 140 and 141 indicated in FIG. 1);

an inflation operation is then performed, consisting in injecting a liquid under pressure between the two sheets at a pressure sufficient to cause deformation of the thinnest sheet, causing the appearance of a plurality of bumps on the latter; (while the other sheet retains its shape).

Optionally, if necessary, a machining of the thick plate intended to constitute the inner wall of the exchanger can be performed in case of problem concentricity or surface condition of said wall.

Of course, the thicknesses of the sheets are determined to withstand the pressures exerted on the exchanger, due to the internal pressure generated by the refrigerant, and external linked to the mechanical assembly, and more specifically to the action of the cutter on the inner wall.

According to a second embodiment illustrated in FIG. 3, the inner and outer walls have a symmetrical sectional section.

In this case, the inner wall 13 and the outer wall 12 have the same thickness. In this case, the double wall is obtained in a manner similar to that described for the first embodiment (making the connections on flat plates placed against each other, and inflating so as to generate deformations of the two sheets according to present embodiment).

It is noted that with this embodiment, the space 14 for circulating the refrigerant has a greater exchange surface than that obtained with the asymmetric profile described with reference to FIG. However, according to this embodiment, the two inner and outer walls undergo the same or almost identical deformation, and therefore each have a series of bends.

It is therefore necessary, for the inner wall to have a smooth surface favoring the action of the mechanical assembly mounted inside the exchanger, to yield a material 130, by a molding technique or the like, so as to make an internal surface of the smooth exchanger.

According to different possible variants, the links may consist of:

- welding points;

- weld lines.

In the case of bonds made in the form of a line, they can be oriented horizontally, vertically or obliquely, or in a combination of these directions, being rectilinear or not.

In addition, the connections can be evenly distributed over the height of the walls and / or on the circumference of the walls.

The distribution of the connections can be made in such a way that the links are aligned horizontally or vertically or, conversely, arranged in a staggered arrangement.

The principle of the invention can be used regardless of the dimensions and capabilities of the device. As an indication, a double wall according to the invention may be implemented on exchangers ranging from 20 centimeters to 2 meters in diameter.

The connections between the inner and outer walls have three roles:

they improve the mechanical strength of the exchanger;

they allow, as a function of their distribution and in particular according to their density, to manage the pressure losses with a view to obtaining a relatively homogeneous heat exchange on the surface of the internal wall and therefore a uniform formation of ice on this surface; wall; - They can guide the flow of fluid and thus channel its path.

These last two roles are described by way of example by the exemplary embodiment illustrated in FIG.

As shown in this figure, the links can take different forms on the exchanger, in particular:

continuous lines 32 forming a kind of partitioning and confinement, channeling the flow towards the main exchange zone;

points 31, distributed at variable densities, to create local pressure drops in order to increase the time of presence of the fluid in the zone where the points are the densest;

dashed lines 30, distributed here along two lines, each of which tends to create a pressure drop, so that the fluid bypasses them increasing its time of presence before joining the outlet duct 141 of the exchanger.

Claims

A device for generating ice, in particular ice in the form of flakes, comprising:

a double-wall exchanger (1) extending between an upper end (10) and a lower end (11), and having an inner wall (13) and an outer wall (12) between which a refrigerant circulates, the internal wall

(13) having a cylindrical shape;

a mechanical assembly (2), (20), (21), (22), (23) mounted inside the exchanger, intended to take off the ice formed on the inner wall,

characterized in that said inner (13) and outer (12) walls are connected between said upper (10) and lower (11) ends by a plurality of links (3) between which the refrigerant circulates, the inner wall ( 13) being substantially smooth, and the inner wall (13) having a greater resistance to deformation than that of the outer wall (12).

2. Device for generating ice according to claim 1, characterized in that said links (3) consist of solder points.

3. Ice generating device according to claim 1, characterized in that said links (3) consist of weld lines.

4. Device for generating ice according to claim 3, characterized in that said weld lines are arranged in one and / or the other of the following directions:

- horizontal;

- vertical;

- oblique.

5. Device for generating ice according to claim 1, characterized in that said links (3) are evenly distributed over the circumference and / or the height of the walls.

6. Device for generating ice according to claim 1, characterized in that said links (3) are distributed in areas of different densities so as to create different pressure losses.

7. Ice generating device according to claim 1, characterized in that said links (3) are aligned horizontally and / or vertically.

8. Device for generating ice according to claim 1, characterized in that said links (3) are arranged in staggered rows.

9. Ice generating device according to claim 1, characterized in that the inner wall (13) has a thickness greater than that of the outer wall (12).