US20240110750A1

US20240110750A1 - Heat Exchanger for Controlling the Temperature of a Solid Substance

Info

Publication number: US20240110750A1
Application number: US18/554,326
Authority: US
Inventors: Nils Bornemann; Gottfried Rier
Original assignee: Gkn Sinter Metals Engineering Gmbh
Current assignee: GKN Powder Metallurgy Engineering GmbH
Priority date: 2021-04-06
Filing date: 2022-04-05
Publication date: 2024-04-04
Also published as: EP4320399A1; WO2022214118A1

Abstract

A heat exchanger includes a plurality of tubular, substantially parallel containers (1, 1 a) filled with a solid substance. The containers are immersed in a vessel that has openings (4) for letting a fluid flow in and out in order for the containers to be exposed to an oriented fluid stream. The containers are immobilized by means of a retaining plate (2) acting as a vessel closure and are supported by a plurality of guide plates (3).

Description

The invention relates to a heat exchanger designed as a vessel for influencing the temperature of a solid substance located therein, wherein a fluid flow in the vessel enables a transport of heat.
In process plant engineering, for example in the chemical industry, a wide range of differently constructed heat exchangers exists, which allow the transfer of heat energy across a barrier. This means that an energy transfer takes place within the heat exchanger, but a material transfer is prevented. As intended, the barrier thus prevents the substances involved from mixing; undesirable impurities or chemical reactions are thus excluded.
These heat exchangers can be divided into two categories, depending on whether the substances involved are exclusively fluids, or whether solid substances are involved in the process. The invention belongs to the second category: the first substance is a solid substance which comprises one or more metallic components and which permanently remains in the heat exchanger. The heat exchanger can be optimized structurally for the use of a specific solid substance. In addition, it is conceivable to introduce the solid substance already at the heat exchanger's production site, for example if the subsequent operating site is not identical to the production site.
The second substance is a fluid, which is guided in an oriented flow through the interior of the heat exchanger designed as a vessel. For this purpose, the vessel comprises a fluid inlet opening and a fluid outlet opening spatially spaced apart from the fluid inlet opening. The fluid can be a gas or a liquid. Preferably, water is a component of the fluid, to which an anti-freeze agent, such as a glycol compound, can be added for broadening the operating range.
Guide plates are arranged inside the vessel which influence the fluid flow. In particular, the guide plates can be arranged to block a direct, in particular a shortest possible, path between the fluid inlet opening and the fluid outlet opening. A lengthened path is thereby prescribed for the oriented fluid flow to increase the exchange of heat.
The heat exchange is effected by flowing the fluid around containers filled with the solid substance. The containers are tubularly elongated containers made of metal which are almost completely immersed in the vessel and around almost the entirety of which fluid can therefore flow. The containers are oriented substantially parallel to each other and are supported along their longitudinal extension in the vessel by a plurality of guide plates. In a preferred embodiment, the guide plates have openings through which the containers are each passed individually. Particularly preferably, these openings are dimensioned in such a way that their size corresponds approximately to the cross-sectional areas of the containers. From this it follows that the arrangement of the openings in the guide plates defines the distances of the containers to each other and that the guide plates obstruct a continuous, in particular laminar, fluid flow along the longitudinal extension of the containers.
The guide plates are supported at the edges on the inner wall of the vessel. Advantageously, recesses can be provided at the edges of the guide plates, through which the guide plates together with the inner wall of the vessel form passages through which a fluid flow can pass. To prevent a displacement of the guide plates along the longitudinal extension of the containers, the guide plates can be fixed in their positions relative to one another by spacers. The spacers can be realized with uninterrupted threaded rods running along the longitudinal extension of the containers, through which the guide plates are screwed together.
Applications are conceivable in which influencing the exchange of heat section by section is desirable. For example, it can be desirable to influence the temperature of the solid substance in the containers in one section of their longitudinal extension more strongly than in other sections. For such cases the vessel can comprise at least three spatially spaced apart fluid openings. Of these, either fewer fluid openings are used simultaneously than are present in total (then there can be vessel sections without an oriented fluid flow), or all fluid openings are used simultaneously. Potentially, several fluid flows in the vessel start from one fluid opening or run towards it. For example, one of at least three fluid openings is positioned approximately centrally with respect to the longitudinal extension of the vessel, towards which two oppositely oriented fluid flows run, starting from fluid openings positioned at both ends of the vessel.
A pressure difference between two fluid openings, caused by a device outside the vessel, for example a pump, can be used to trigger an oriented fluid flow. In this variant, the vessel wall is designed to be resistant to overpressure, for example it is designed for a fluid pressure >0.5 bar(g). Additionally, the vessel cross section can be designed in a pressure-optimized way, for example it can be circular in a plane perpendicular to its longitudinal extension.
Depending on the planned use of the heat exchanger, one of the design criterions can be the maximization of the amount of solid substance contained for given vessel dimensions, for example for a specified cross section. One solution for this is the arrangement of the containers in an arrangement schema optimized for a high filling degree within this cross-section, in other words, as much of the cross-sectional area of the vessel as possible is filled with the cross-sectional area of the containers. Which arrangement schema is suitable for this depends on the container geometry. In a preferred embodiment of the invention the containers are produced from pipes with circular cross-sections, in particular, a seamless pipe is used for the production of each container. At their end lying inside the vessel, the containers are closed; cap-like end pieces can be used for this purpose, which are attached to the pipe by a weld.
A high filling degree can be achieved by arranging the containers in such a way that the central axes of neighboring containers can be represented as vertices of a triangle in a cross-sectional view. In particular, each distance line between the axes of neighboring containers forms an edge of an equilateral triangle. Particularly preferably, the length of the angle bisector of a triangle is less than the pipe diameter of a container.
A further measure for increasing the filling degree is an arrangement schema in which container variants with two different pipe diameters are combined. Thus, remaining areas of the cross-sectional area can be used by placing containers with small pipe diameters there. Preferably, the ratio of the pipe diameters of the two container variants can correspond to a factor of 1.5 or greater.
Structurally, the arrangement schema is implemented by fixing the containers to a retaining plate. They protrude through this retaining plate at one end, while at the same time the retaining plate acts as a vessel closure. Consequently, one end of each container is outside of the vessel and/or heat exchanger, whereas the remaining part of the container is immersed in the vessel.
Through the fixation to the retaining plate, which is preferably formed by a welding seam on the outside of the vessel, a longitudinal displacement of the containers relative to the vessel is prevented; however, an expansion of the containers along their longitudinal extension into the vessel (for example when heated) is possible without hinderance, as the containers are not fixed to the guide plates through which they are supported along the longitudinal extension.
Sufficient free space for an elongation due to expansion of the containers within the heat exchanger is provided by manufacturing the vessel with a corresponding excess space relative to the containers on the side opposite to the retaining plate. The vessel can be closed on this side by a torispherical end (a Klopper head); likewise, an arrangement of a flat base plate is conceivable here. Preferably, an access into the vessel interior is provided for being able to reach the container ends for inspection or similar purposes, for example for a service life-relevant condition assessment of welding seams. An inspection opening could be inserted into a torispherical end (a Klopper head), a base plate could be designed to be detachable, for example through a screw connection with a flange formed on the vessel wall.
In a corresponding embodiment of the heat exchanger—as already explained above—all other welding seams can be arranged on the outside of the vessel, which makes assessing their condition easier. This aspect is significant because the containers of a heat exchanger according to the invention are designed to be at least gas tight. Preferably they are designed to be resistant to overpressure; particularly preferably the containers are designed for an operating pressure >5 bar(g) in their interior. With this the heat exchanger is subject to guidelines for the operation of pressure equipment, requiring regular condition assessments.
The containers are designed to be gas tight to allow a gas flow inside of them under full separation from the outside environment. Each container comprises a gas opening, which is comparable to the fluid openings on the vessel.
Just as the fluid flow within the vessel, the gas flow within the container also influences the temperature of the solid substance. Just as with the fluid flow within the vessel, a pressure difference also serves as a cause for initiating or maintaining the gas flow within the container. While, however, the fluid flow is initiated by an external means, with a suitable choice of materials the solid substance can cause a pressure change within the container by itself, inducing a pressure difference and thus a gas flow. For this, the solid substance is chosen to be able to bind gas by accumulating gas at its surface or by storing gas in its interior, this process being reversible. With the storage comes a reduction in pressure, while conversely a release of gas from the solid substance causes an increase in pressure. The gas flow is thus caused by a pressure difference between the exterior of the container and the interior of the container, which is why already one gas opening, as opposed to at least two fluid openings, is sufficient for the operability of a heat exchanger according to the invention.
Gases with a small nucleus are particularly well suited for this operation, as they exhibit both good heat transfer properties as well as being able to be incorporated into the crystal lattice structures of some metallic solid substances. Particularly preferably, the solid substance enables an accumulation or storage of a gas with a molecular weight <3 g/mol.
A surface of the solid substance that is as large as possible improves accumulation or storage properties. Therefore, the solid substance is preferably a shaped body which has been formed from powder by pressing. In particular, these shaped bodies consist predominantly of pressed metal powder. The shaped bodies are then introduced into the containers, for example as bulk material or as a collection, where a collection is to be understood here as a regular arrangement of shaped bodies (for example as a stack, or combined into blocks), as opposed to bulk material. Such shaped bodies combine the advantages of a large surface area of the solid substance with at the same time increased material density, hence a better filling degree of the heat exchanger.
The gas openings of the containers are arranged at their ends which protrude out of the vessel and are connected in a gas-conducting manner to bundle the gas flows of all containers into a single gas flow; this gas flow can be heated or cooled to influence the temperature of the solid substance after entering the containers. Preferably, the connection is provided by a pipe structure placed directly on the gas openings, which enables a compact design and short connecting distances. Particularly preferably, the pipe structure can be designed so that each container end is connected to every other by two disjoint conduit paths. This rule has the effect of equalizing the gas flows and increasing their volumetric performance.
Since the pipe structure comprises many connections to gas openings which are close to each other, the use of compensation means to reduce the mechanical stress which can act on the gas lines is conceivable. An intermediate part can be provided between the pipe sections of the containers and the gas line, which reduces the stress through elastic deformation. A cost-effective method for the construction of such intermediate parts is the use of one or more reducers.
Additionally, the containers can also all be connected to each other through a gas line by their end which is positioned within the vessel. The gas line can then be continued along the longitudinal direction of the vessel and exit through the retaining plate at the opposite end of the vessel.
Depending on the desired degree of detail of the measurement of the temperature situation within the heat exchanger, at least one or multiple temperature sensors are provided to be distributed in the various vessel sections in which the solid substance is embedded. For this purpose, the sensor can be designed as a probe which within a container is guided through the retaining plate into the interior of the vessel, so that its wiring can be performed outside the vessel.

EXAMPLE EMBODIMENT

Subsequently, an embodiment of the invention is described in more detail with the aid of some figures. All figures refer to the same embodiment, of which different details are shown in the individual illustrations.

FIG. 1 shows a heat exchanger in an overall view.

FIG. 2 shows a combination of guide plates.

FIG. 3 shows a detail of an arrangement schema.

FIG. 4 shows a pipe structure placed on the ends of the containers.

FIG. 5 shows an enlarged detail view in the area of the retaining plate.

FIG. 1 : a vessel contains containers in two variants 1 and 1 a, whose pipe diameters differ from each other. The containers are fixed to a retaining plate 2 and pass through twenty-three guide plates 3. At the end opposite to the retaining plate the vessel is closed by a Klopper head, wherein a distance to the container ends is provided to enable their unhindered expansion.
The vessel has three fluid openings 4, one is positioned approximately centrally to the vessel's longitudinal extension. To measure the temperature, respectively one probe TS is provided in two containers of the variant 1. The distance between sensor and container end is respectively less than a quarter of the container length.
FIG. 2 shows a schematic view in which two adjacent guide plates 3 are shown side by side for illustration purposes, instead of one behind the other as arranged in the vessel. The left half of the view further contains several measurement guide lines, as well as an arrangement schema composed of triangles. In the right half of the view a recess 5 is shown atop of the guide plate, in relation to the dashed circular contour; there, the passage for the fluid flow is thus positioned at the top in cooperation with the vessel wall. Adjacent guide plates are arranged in the vessel respectively rotated by 180° each, causing the changes in direction of the fluid flow and thus causing the flow around the containers to occur predominantly transversely to their longitudinal extension.
FIG. 3 illustrates the arrangement schema aimed at a high filling-degree by means of one of the equilateral triangles of which it is composed. In the present embodiment each triangle has at least two sides in common with one side of a neighboring triangle. The center points of the openings in the guide plates, and/or the central axes of neighboring containers, are correspondingly close to each other.
If one mentally superimposes the left and the right half of FIG. 2 , one obtains the complete arrangement schema according to which the containers are fixed to a retaining plate and/or according to which their ends pass through the retaining plate.
In FIG. 4 a pipe structure is shown which connects all containers of the heat exchanger in a gas-conducting manner. The gas openings of the containers are recognizable as dashed circles 6. The vessel contains thirty-eight containers in total. From each gas opening two distinct conduit paths (without a common section) lead to every arbitrary other gas opening. The pipe structure is also shown from the side on the far left of FIG. 1 as part of the illustration.
FIG. 5 is an enlarged detail view of the container ends in the area in which they pass through the retaining plate 2. Container variant 1 is provided with an intermediate member 7, which is arranged between the pipe section of the container and its gas opening. Both container variants contain an annular disk 8 and a filter disk 9 at the end of their respective pipe section (shown without reference signs for variant 1 a). The annular disk serves as a retaining means to prevent displacement of the shaped bodies introduced into the containers (the shaped bodies are not shown in the figures), for example during transport of the heat exchanger. The filter disk as a further retaining means prevents free particles, which may have become detached from the shaped bodies, from being ejected with the gas flow from the containers and thus from the heat exchanger.
Additionally, the position of a welding seam for fixing of a container to the retaining plate is indicated.

Claims

1. A heat exchanger, comprising:

a plurality of tubularly elongated containers (1, 1 a), which are substantially parallel to one another and which are filled with a solid substance containing a metallic component, a fluid being able to flow around the containers (1, 1 a) by the containers (1, 1 a) being almost completely immersed in a vessel which comprises a fluid inlet opening (4) and a fluid outlet opening (4) for the establishment of an oriented fluid flow in an interior of the vessel;

a plurality of guide plates (3) supported at edges on an inner wall of the vessel; and

a retaining plate (2) serving as a vessel closure, to which the containers are fixed and through which the containers protrude,

characterized in that the containers (1) are supported by the guide plates (3) along a longitudinal extension of the containers (1) in the vessel.

2. The heat exchanger according to claim 1, characterized in that the guide plates (3) have openings through which the containers (1, 1 a) are passed individually.

3. The heat exchanger according to claim 1, characterized in that the guide plates (3) obstruct a continuous, in particular laminar, fluid flow along the longitudinal extension of the containers (1, 1 a).

4. The heat exchanger according to claim 1, characterized in that the guide plates (3), together with the inner wall of the vessel, form passages (5) for enabling a fluid flow.

5. The heat exchanger according to claim 1, characterized in that several container variants (1, 1 a) with different dimensions, in particular with different pipe diameters, are combined with each other.

6. The heat exchanger according to claim 1, characterized in that the containers (1, 1 a) are all connected with each other via a gas line at ends of the containers (1, 1 a) which protrude out of the vessel.

7. The heat exchanger according to claim 1, characterized in that the solid substance in the containers (1, 1 a) is capable of storing gas in an interior of the solid substance.

8. The heat exchanger according to claim 1, characterized in that at least one of the containers is provided with a temperature sensor.

9. The heat exchanger according to claim 8, characterized in that the temperature sensor is designed as a probe which within the container is guided through the retaining plate into the interior of the vessel.