EP4359690A1

EP4359690A1 - Device for controlling the flow of a cryogenic medium

Info

Publication number: EP4359690A1
Application number: EP22735894.2A
Authority: EP
Inventors: Emir Tebib; Denis Beil; Frank Gockel
Original assignee: Messer SE and Co KGaA; Messer France SAS
Current assignee: Messer SE and Co KGaA; Messer France SAS
Priority date: 2021-06-25
Filing date: 2022-06-24
Publication date: 2024-05-01
Also published as: WO2022269088A1; DE102021003302A1; US20240288085A1

Abstract

A process for cooling products is known in which a cryogenic medium, for example liquid nitrogen, liquid oxygen, or liquid carbon dioxide, is metered directly into a container which contains the product. In the event of damage to a fitting which conducts the cryogenic medium, parts of the material of the fitting can reach the product. While this can be quickly ascertained by metal detectors when using metal materials, a comparable verification can only be carried out with difficulty when using plastic parts. According to the invention, plastic elements contained in the device, such as seals for example, are made of a plastic which is mixed with metal additives. In the event of damage, particles originating from the plastic elements can thus also be reliably detected by metal detectors.

Description

Device for controlling the flow of a cryogenic medium

The invention relates to a device for controlling the flow of a cryogenic medium, having a fitting that is constructed from a plurality of functional elements that interact with one another, with at least one of the functional elements being designed as a plastic element.

In many industrial applications, especially in the field of food technology, cryogenic media, such as cryogenic liquefied gases, are used to cool or freeze liquid, pasty or solid products. The heat transfer takes place either indirectly on heat exchanger surfaces, i.e. without physical contact between the product to be cooled and the cryogenic medium, or by direct cooling of the product with the cryogenic medium. In the case of direct cooling, the product to be cooled is usually fed through a line or collected in a container and the cryogenic medium is introduced into the line or into the container via suitable nozzles or valves. In the following, the terms “line” and “container” are subsumed under the term “container”.

EC Regulation No. 1935/2004 regulates the placing on the market of materials and objects that are intended to come into direct or indirect contact with food. In particular, this regulation regulates the need for traceability of the materials, which must be guaranteed at all levels. Objects that are intended for conveying or controlling the material flows of cryogenic media often have components made of different materials. This makes it considerably more difficult to use them in the food sector, since the traceability required by law can only be guaranteed with correspondingly complex detectors that reflect the multitude of materials.

For example, devices for metering a cryogenic medium into a container are known from EP 1 867902 A2 and EP 2309 160 A1. These devices serve in particular to mix a food product located in a container, for example a mixer, by feeding it of the cryogenic medium, the supply preferably taking place in a lower area of the container, ie in that area of the container which is filled with the product to be cooled during the treatment. In this procedure, also referred to as "bottom injection" in technical jargon, care must be taken to ensure that the valve can be closed in order to prevent the product from penetrating into the interior of the device in phases during the treatment during which no cryogenic medium is introduced to prevent. In the devices known from EP 1 867902 A2 and EP 2309 160 A1, this is achieved in that the devices have a closure body which is arranged in a guide channel of the housing with limited axial movement against the action of a spring and is equipped with a closing plate. The spring causes the cryogenic medium to be supplied only above a predetermined positive pressure on the inflow side; if the pressure falls below this value, the closing disk is pressed against a valve seat on the housing in a flow-tight manner. Of course, this structure means that the devices are composed of several parts, between which a sealant ensures the required flow tightness. In the case of the objects of EP 1 867902 A2 and EP 2309 160 A1, as with other comparable fittings from the prior art, these sealants are often made of a flexible, low-temperature-resistant plastic such as PTFE, while the other parts of the fitting are made of are usually made of metal. For the above-mentioned reason, the use of these objects in the food sector leads to an increased effort in terms of fulfilling the legal obligation to provide evidence.

The object of the present invention is therefore to improve a device for controlling the flow of a cryogenic medium in such a way that the verification and compliance with the legal requirements for traceability is facilitated.

This object is achieved in a device of the type and purpose mentioned at the outset in that at least one plastic element is formed from a plastic mixed with metallic additives. The device according to the invention thus has a functional element or several functional elements which is/are made of plastic (referred to here as “plastic element” or “plastic elements”), which or at least one of which is formed from a plastic mixed with metallic additives /are.

Due to the metallic additives, plastic material coming from the device, in particular from plastic elements such as seals, can be made visible with metal-sensitive detectors, such as are already commonly used in food production. In the event that plastic particles get into the production process due to damage, these are detected during ongoing production and the damaged fitting can be withdrawn from use as a result. As a result, the requirements of EU regulation 1935-2004 with regard to the plastic parts in the device are satisfied in a simple manner.

The metallic additives are either mixed into the raw mass of the plastic during the manufacture of the plastic elements or applied to the corresponding element as a coating. The metallic additives are preferably small metal particles, in particular metallic nanoparticles, which are contained in a size between 10 nm and 1000 nm as a colloidal disperse phase in the plastic acting as the dispersion medium. The elastic and low-temperature-resistant properties of the plastic are not or only slightly impaired by such nanoparticles, and at the same time they can be easily detected using conventional metal detectors used in food production.

The plastic of the plastic elements to which the metal additives have been added is in particular PTFE, nylon or polyethylene, with PTFE being particularly preferred because of its particularly good low-temperature properties.

The fitting is preferably a valve that can be connected to a supply line for the cryogenic medium for metering in the cryogenic medium Medium in a container, which is constructed from a plurality of metal parts that are detachably connected to one another, with plastic elements being arranged between at least some parts, which plastic elements are made of a plastic mixed with metal additives. The plastic elements are in particular sealing means, for example sealing rings, made from a flexible but low-temperature-resistant plastic such as PTFE. The valve serves in particular to introduce precisely measured amounts of cryogenic medium directly into a product located in the container in order to cool it, and the sealing means serve in particular to prevent the cryogenic medium from escaping from the valve and/or product or ambient atmosphere from entering into the valve to prevent

In a particularly preferred embodiment, the valve is a device of the type described in EP 1 867 902 A2 or EP 2309 160 A1, to which express reference is made here. A device of this type has a valve housing which is made up of at least a front housing part and a rear housing part, between which a sealing means in the form of a sealing ring is arranged. A shut-off element is arranged in the valve housing and is equipped with a plate-shaped front section on the end face. The shut-off member is accommodated in the valve housing so that it can be moved to a limited extent against the action of a spring, with the movement preferably taking place towards the interior of the container in the opening direction. The restoring force of the spring determines a differential pressure above which the valve opens. For example, the differential pressure when using liquid nitrogen as the cryogenic medium is 2 to 2.5 bar, and when using liquid carbon dioxide it is 7 to 9 bar. In the closed state, the plate-shaped front section rests on a valve seat of the valve housing, with a sealing means made of a flexible and low-temperature-resistant material in the form of a sealing ring ensuring flow-tight contact. The sealing means is preferably attached to the plate-shaped front section of the shut-off element (on its side facing the valve seat) or in the valve seat, for example inserted in a groove running all around; however, sealing means can also be provided both in the front section and in the valve seat. According to the invention, the sealing means is between the two housing parts and/or the sealant between the plate-shaped front section and the valve seat made of a plastic mixed with metallic additives.

The container is, for example, a line or a container, in particular a container of a mixer or cutter. The valve can be arranged in such a way that it opens into a lower area of a container that is filled with product when the device is used. In such an embodiment, also known as "bottom injection", the cryogenic medium comes into direct contact with the product to be cooled, which means that special attention must be paid to the traceability of undesired materials that can be introduced into the food product via the cryogenic medium.

Cryogenically liquefied nitrogen or liquid carbon dioxide is preferably used as the cryogenic medium.

An embodiment of the invention will be explained in more detail with reference to the drawing. The single drawing (FIG. 1) shows schematically a device according to the invention for metering a cryogenic medium into a container.

The device shown in the drawing is used to introduce a cryogenic medium, for example a liquefied gas such as liquid nitrogen, liquid oxygen or liquid carbon dioxide or a cold gas, for example cryogenic gaseous nitrogen, into a substance to be cooled, which is about a gas , a liquid or a pasty, powdery or lumpy substance.

The device comprises a valve 1 which, in the exemplary embodiment, is mounted on a container 2 in which the substance to be cooled is stored or processed. The valve 1 has a valve body consisting of two housing parts 6 , 7 . The front housing part 6 is detachably fastened in a container wall 3 of the container 2 , for example screwed into a thread 5 , in such a way that the housing part 6 terminates at the front essentially flush with an inner surface 9 of the container wall 3 . The rear housing part 7 of the valve body is on Front housing part 6 is also detachably fastened, for example by means of a thread 8 , the front side of the front housing part 6 facing the rear housing part 7 protruding with an annular shoulder 10 inside the rear housing part 7 . On its end opposite the front housing part 6, the rear housing part 7 has a connection 4 for connection to a supply line (not shown here) for a cryogenic medium. The connection 4 is adapted to the type of feed line for the cryogenic medium and, in some cases, is designed to be pressure and/or low temperature resistant. For example, the connection 4 is a threaded connection or a flange.

Inside the essentially rotationally symmetrical housing parts 6, 7, a shut-off member 11 is accommodated in an axially movable manner, by means of which the valve 1 can be closed and opened. The shut-off member 11 comprises a substantially cylindrical inner section 12, on the end of which facing the container 2 there is a plate-shaped front section 13 with a conical cross-section, which is adapted in shape to a conically shaped valve seat 15 in the front housing part 6. On the side of the front section 13 of the shut-off member 11 facing the valve seat 15, a sealing ring 14 is arranged in a groove running all around, which is seated on the valve seat 15 when the valve 1 is closed. In the open state, on the other hand, the front section 13 with the sealing ring 14—as shown in FIG. 1—is at a distance from the valve seat 15 .

Another sealing ring 16 made of a flexible, low-temperature-resistant material is arranged between the front housing part 6 and the rear housing part 7 in corresponding all-round grooves in the housing parts 6, 7. The sealing ring 16 is intended in particular to prevent cryogenic medium from escaping in the area of the connection between the front housing part 6 and the rear housing part 7 during operation of the device.

On the side of the inner section 12 of the shut-off member 11 facing away from the container 2, an annular flinter section 17 is provided which is detachably mounted on a holding section 18 of the inner section 12, for example is screwed. The outer radius of the rear section 17 is larger than the inner diameter of the annular shoulder 10 of the valve body. When the valve 2 is opened, the annular shoulder 10 thus limits the axial displaceability of the shut-off member 11 towards the interior of the container 2; in the maximum opening state, the rear section 17 rests on the annular shoulder 10. In contrast, when the valve 2 is closed, the rear section 17 is arranged at a distance from the annular shoulder 10 . In order to ensure a flow connection inside the valve body on both sides of the rear section 17, even when the rear section 17 is in contact with the annular shoulder 10, the inner section 12 of the shut-off member 11 is provided with a central bore 25 which is approximately in the middle of the inner section 12 opens into a radial bore 26, which in turn ends radially on the outside on the inner portion 12 of the shut-off member 11.

A spiral-shaped closing spring 22 extends between the rear section 17 and a spring seat 20 on the front housing part 6 of the valve body around the inner section 12 of the shut-off element 11. The closing spring 22 is clamped between the spring seat 20 and the rear section 17 of the shut-off element 11 in such a way that it is already in the closed position of the valve 2 is under a certain pretension. As a result, the valve 1 only opens when there is a certain differential value (limit pressure), determined by the spring force of the closing spring 20, between the pressure inside the valve body and the pressure in the container interior of, for example, 2 to 9 bar. When the limit pressure is exceeded, the shut-off member 11 is displaced axially in the direction of the interior of the container against the action of the closing spring 22 due to the excess pressure acting on the plate-shaped front section 13 of the shut-off member 11 inside the valve body. An annular gap opens between the front section 13 of the shut-off member 11 and the valve seat 15 and thus opens a flow path into the interior of the container 2 .

The conical shaping of the front section 13 of the shut-off member 11 means that the cryogenic medium is deflected in the radial direction as it flows into the container 2 and is distributed very widely in the container 2 . The maximum advance of the shut-off member 11, determined by the distance between the rear section 17 and the annular shoulder 10 when the valve is closed is selected in such a way that the end face 24 of the front section 13 does not protrude any further into the interior of the container 2 than until it is arranged essentially flush with the inner surface 9 of the container wall 3 . An agitator or slide arranged in the container 2, which extends to the container walls, is therefore not impeded by the valve 1.

If the pressure in the interior 23 of the valve body falls below the limit pressure defined above, the valve 1 closes automatically in that the shut-off element 11 moves into its blocked position under the action of the closing spring 22, in which the plate-shaped front section 13 with the sealing element 14 on the valve seat 15 rests. No external control of the shut-off element 11 is required for this; the amount of cryogenic medium introduced into the container 2 is metered directly by changing the pressure in the supply line or in the interior 23 of the valve 1 no product from the container 2 penetrate into the interior 23 of the valve 1. This applies in particular in the event of a sudden, unforeseen drop in pressure in the supply line for the cryogenic medium. The device according to the invention is therefore also suitable for "bottom injection", ie for installing the valve 1 in an area of the container wall 3 which is wetted by the product to be cooled during use. Of course, the valve 1 can also be arranged in the head space of the container 2 or in a product-carrying line.

The housing parts 6, 7 of the valve body, shut-off element 11 and spring 22 are made of a material that takes into account the low temperatures and/or the high pressures of the cryogenic medium used, for example a suitable, low-temperature-resistant stainless steel. In the event of damage, where valve material can leak into the product in the vessel via the cryogenic medium, the process flow can be monitored using conventional metal detectors, such as an X-ray detector, in order to be able to detect metal particles originating from the valve in the event of damage. In order to enable detection of particles originating from the sealing rings 14, 16, these are made of a plastic mixed with metallic additives. As a result, material originating from the sealing rings 14, 16 can also be detected with conventional metal detectors. The plastic is, for example, PTFE, and the metal additives are, for example, metal microparticles or nanoparticles that were mixed into the liquid plastic mass during the production of the sealing rings 14 , 16 .

Since particles of all components of the valve 1 that get into the product can be easily recognized in the event of damage, the device according to the invention meets the high hygienic requirements in the production or processing of food, for example for cooling dough, flour, mash or meat mass Sausage production or when dosing a cryogenic medium into a line through which a gas or liquid flows, for example in the treatment of wine, juices or milk for cooling or sterilization purposes, as well as in the production or processing of pharmaceutical products, preliminary products and ingredients or biological ones Rehearse.

Reference character list

1. valve

2. container

3. container wall

4. Connection

5. Thread

6. front housing part of the valve body

7. rear part of the valve body

8. Thread

9. Inner surface (of the container wall)

10. ring shoulder

11. Shut-off member

12. Interior section

13. Anterior section

14. Sealing ring

15. Valve seat

16. Sealing ring

17. Posterior section

18. Holding section

19th -

20. Spring seat

21

22. Closing spring

23. Interior of valve body

24. Face

25. central hole

26. Radial bore

Claims

patent claims

1. Device for controlling the flow of a cryogenic medium, with a fitting which is constructed from a plurality of functional elements which interact with one another, wherein at least one of the functional elements is designed as a plastic element (14, 16), characterized in that at least one plastic element (14 , 16) is made of a plastic mixed with metallic additives.

2. Device according to claim 1, characterized in that PTFE, nylon or polyethylene is used as the plastic in the at least one plastic element (14, 16) mixed with metallic additives.

3. Device according to claim 1 or 2, characterized in that metallic nanoparticles are used as metallic additives in the plastic element (14, 16).

4. Device according to one of the preceding claims, characterized in that a connectable with a supply line for the cryogenic medium valve (1) for metering the cryogenic medium into a container (2) is provided as a fitting, which valve (1) from several detachable metal parts (6, 7, 13) connected to one another, at least one plastic element (14, 16) being arranged between the parts (6, 7, 13) and made of a plastic mixed with metal additives.

5. Device according to Claim 4, characterized in that the valve (1) comprises a valve housing and a shut-off element (11) equipped with a plate-shaped front section (13), the valve housing consisting of a front housing part (6) and a rear housing part (7 ) is constructed, between which a sealing means (14) is arranged, and the shut-off member (11) against the action of a spring (22) in one in the open state, but in the closed state of the valve (1) the plate-shaped front section (13) rests on a sealing means (16) which is in a valve seat (15) of the valve housing or in the front section (13) on which the valve seat (15 ) facing side, is arranged, wherein at least one sealant (14, 16) is made of a plastic mixed with metallic additives.

6. Device according to claim 4 or 5, characterized in that the container (2) is integrated in a mixing device for a product, in particular for a food product.

7. Device according to one of the preceding claims, characterized in that liquid nitrogen or liquid carbon dioxide is used as the cryogenic medium.