EP0499883B1 - Heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger (1) having a primary chamber (2) for a primary medium and a secondary chamber (3) for a secondary medium. The two chambers are separated from one another by a gas-tight, thermally conductive wall (4). It is provided that the secondary chamber (3) is bounded by the wall (4) and by an outer casing sheet (5) spaced from this wall (4). The secondary chamber (3) is subdivided into an inner (3a) and an outer subchamber (3b) by a profiled sheet (6) arranged between the wall (4) and the outer casing sheet (5). The profiled sheet (6) is fastened, e.g., only at its upper end to the upper part of the heat exchanger (1) and hangs freely between the wall (4) and the outer casing sheet (5). This does not hinder its thermal expansions. The profiling of the profiled sheet (6) can hold the wall (4) and the casing sheet (5) at the same distance from one another. The secondary chamber (3) is subdivided into tube-like ducts by the profiled sheet (6). Expensive heating tubes are not required. <IMAGE>

Description

The invention relates to a heat exchanger with a primary space for a primary medium and a secondary space for a secondary medium, which is separated from the primary space by a gas-tight, heat-conducting wall and is laterally delimited by an outer wall and has a floor at the bottom.

A heat exchanger is used to transfer thermal energy from a hot primary medium to a cold secondary medium. However, the two media should not be mixed. Various embodiments of such a heat exchanger are known. One of these embodiments provides a container in which a plurality of pipelines connected in parallel are arranged. Webs are arranged as spacers between adjacent tubes. The parallel tubes are part of a secondary circuit that is passed gas-tight through the container wall. The interior of the tubes forms the secondary space through which the heat-absorbing secondary medium flows. The remaining interior of the container is part of a primary circuit. It forms the primary space through which a hot primary medium is conducted.

Such a heat exchanger can also be used in a smoldering furnace according to EP-PS 0 302 310. Thermal energy from hot flue gas is fed to the contents of a pyrolysis drum via a secondary medium. In such a use of a known heat exchanger, the pipes carrying the secondary medium must consist of material that is resistant to high temperatures. Then it can be necessary that the pipes are coated with a refractory mass. To do this, the pipes must be provided with metal pins, between which a refractory ceramic mass is then held.

Heat exchangers in which the secondary space is formed by parallel pipes can be produced with great effort and high costs. The pipes required are very expensive. Connecting the pipes by means of webs requires complex and expensive welding work.

When using such a heat exchanger having parallel pipelines in a smoldering furnace in which the primary medium is a hot flue gas, the pipe surfaces must be covered with a refractory mass. This is expensive because of the curved surfaces of the pipes. Even the welding of the required pins cannot be done mechanically due to the curved surface and requires expensive manual work.

From GB 2 065 861 A a heat exchanger is known in which the primary space is delimited on the inside by an inner tube and on the outside by a membrane. The space between the membrane and an outer stable housing forms the secondary space. This is extended downwards and limited by a floor. The membrane between the primary room and the secondary room is provided with knobs. These knobs are designed to improve heat exchange.

The invention has for its object to provide a heat exchanger that can be assembled quickly with simple, inexpensive means and that still works reliably. In particular, by different possible Thermal expansion of various components of the heat exchanger no material stresses or even destruction, such as welding, occur.

The object is achieved according to the invention in that the outer wall is a cladding sheet and that the secondary space is divided into an inner and an outer partial space by a profiled sheet.

The arrangement of the profiled sheet forms tube-like channels which serve as a secondary space. The heat exchanger according to the invention therefore requires only inexpensive profiled sheet metal and even cheaper unprofiled sheet metal for the outer jacket sheet for its production instead of expensive pipes. With this material, which can be obtained inexpensively, parallel channels for the secondary medium are constructed in accordance with the invention, the effect of which corresponds to the expensive parallel tubes connected by webs. This is true, although the channels are often not delimited from one another.

The arrangement of the profiled sheet in the space between the wall and the outer cladding sheet forms two partial spaces, each of which is divided into parallel channels by the profiled sheet. The channels of the inner sub-space are directly delimited by the wall that separates the secondary space from the primary space. Therefore, the secondary medium flowing in the inner subspace is first heated. This heated secondary medium can then release thermal energy via the profiled sheet metal to the secondary medium in the outer subspace. This two-stage heat transport largely avoids material stresses caused by thermal expansion.

For example, the profiled sheet is arranged in the direction of the flow of the primary medium and profiled in a plane perpendicular to the direction of flow of the primary medium.

The fact that the secondary medium can then be rectified through the inner channels or can flow in countercurrent to the primary medium ensures good heat transfer through the heat-conducting wall between the primary space and the secondary space.

The profiled sheet is arranged, for example, so that it alternately touches the wall that delimits the primary space and the outer cladding sheet, thereby forming subspaces and the outer cladding sheet is held at the same distance from the wall.

The profiled sheet can be clamped. Welded connections are advantageously not required.

The advantage is achieved that the wall, the profiled plate and the outer jacket plate assume a fixed position in the radial direction or perpendicular to the flow direction, while they can be freely moved in the direction of the axis of the heat exchanger or in the flow direction due to thermal expansion.

For example, the profiled sheet is only attached to its upper section and hangs down freely between the wall and the outer cladding sheet. This has the advantage that different thermal expansion of the jacket sheet, the wall and the profiled sheet can have no effect on the rest of the construction. Different thermal expansions of rigidly connected components could lead to bending or even cracks.

For example, the two subspaces of the secondary space are on one end, e.g. connected to each other at the foot of the heat exchanger. On the other end, e.g. at the head end of the heat exchanger, the outer part is connected to a feed line and the inner part is connected to a discharge line.

This allows the secondary medium to be guided through the secondary space, the secondary medium first in the outer subspace, e.g. in its channels, flows, is then deflected and then in the inner subspace, e.g. in its channels, flows back in the opposite direction. The outer subspace is connected to a supply line for the supply of the secondary medium. The inner part of the room is connected to a drain to discharge the secondary medium.

With this arrangement, the advantage is achieved that the same secondary medium is passed twice through the secondary space. Through the opposite direction of the secondary medium achieved the advantage that the warmer medium flowing in the inner part space can preheat the cooler medium flowing in the outer part space over the profiled sheet.

For example, the outer jacket plate is connected in a gastight manner through the floor to the wall of the primary space at one end of the heat exchanger and the profiled plate ends at a distance from the floor. With this construction, the subspaces of the secondary space are connected to one another and a gas stream can advantageously be passed around the end of the profiled sheet. The gas passes from one subspace to the other, for example from the outer to the inner subspace. However, it is ensured that no gas escapes from the secondary space.

The floor mentioned is, for example, elastic. This has the advantage that stresses due to different thermal expansions of the wall and the outer jacket sheet are compensated. Thermal expansion of the profiled sheet metal cannot lead to stress, since it ends at a distance from the floor and only needs to be fastened in its upper part.

On the end face opposite the floor, the head end of the heat exchanger, for example, the outer partial space of the secondary space is closed by a closure plate extending between the outer jacket plate and the profiled plate. A second collecting duct, which is open to the inner partial space and is connected to a discharge line, is arranged on the end face of the closure plate. A first collecting duct, which is open to the outer part space, is arranged on the other side of the closure plate. This first collecting duct is connected to a feed line.

This construction ensures that the secondary medium in the area of an end face of the heat exchanger only reaches the outer partial space of the secondary space. A distribution of the secondary medium on lower part spaces formed by the profiled sheet metal is ensured by the first collecting duct. This first collecting duct connects all the outer lower part spaces with each other. The secondary medium can thus get from the feed line via the first collecting duct into each individual outer lower part space. Since no further path is possible through the sealing plate, the secondary medium flows in the same direction between the profiled plate and the outer jacket plate. The direction of flow of the secondary medium is reversed on the floor, which connects the wall of the primary space to the outer casing sheet. It flows around the end of the profiled sheet and then flows between the profiled sheet and the wall of the primary space to the second collecting duct. The inner lower part spaces of the secondary space are connected to one another by the second collecting duct. As a result, the secondary medium arriving from all inner lower part spaces is collected and can then be discharged via the drain.

With this construction the advantage is achieved that after a short start-up time the secondary medium in the outer part space is preheated by the already heated medium in the inner part space as a result of heat exchange through the profiled sheet metal.

For example, the first collecting duct is placed on the outer surface of the casing plate, the outer casing plate having an opening continuously towards the first collecting duct. This embodiment ensures that all outer lower part spaces are also connected to one another by the first collecting duct when the profiled sheet metal touches the jacket sheet.

For example, the profiled sheet is only attached to its upper part hanging. It can be connected to the wall of the primary space via the second collecting duct. This provides a simple and effective construction and, since it is suspended like a curtain, the profiled sheet can expand downwards without tension or even cracks occurring in the material.

The profiled sheet has, for example, an angular profile. The profile can be rectangular or trapezoidal. It can then lie flat against the outer cladding sheet and / or against the wall of the primary space. The profile can also be triangular.

According to another example, the profiled sheet can be a corrugated sheet with a round, in particular sinusoidal, profile. Such a corrugated sheet is commercially available in the required form. With the use of a known corrugated sheet, the advantage is achieved that the costs for the heat exchanger can be further reduced. This is due to the fact that corrugated iron can be purchased at a low price, which is significantly lower than the price of pipes.

The profiled sheet and / or the cladding sheet and / or other parts of the secondary space are made of steel, for example. In this case, inexpensive steel is sufficient, since in the heat exchanger according to the invention the profiled sheet and the jacket sheet do not come into contact with the hot primary medium. The hot primary medium only hits the wall of the primary room. While in a known embodiment with tubes and webs all parts come into contact with the hot primary medium and therefore have to be made of heat-resistant material, the profiled sheet and the jacket sheet can consist of a simpler, less expensive steel in the heat exchanger according to the invention. This has the advantage that largely any commercially available corrugated iron can be used. Only the wall of the primary room has to consist of high temperatures, eg 800 ° C resistant material.

The wall between the primary space and the secondary space can, for example, be pinned on its side facing the primary space and covered with a refractory ceramic material. This ensures that corrosion of the wall by hot primary medium containing pollutants is excluded.

The arrangement of the pins on the wall can be done by automatic welding, since a flat or only slightly curved surface must be pinned. This is an additional advantage of the heat exchanger according to the invention compared to a known heat exchanger in which the surfaces of pipes must be pinned, which is only possible with elaborate manual work because of the high curvature of the pipe surfaces. The same applies to the coating of the pinned wall with ceramic mass.

For example, the primary medium is a hot flue gas, while the secondary medium is a heating gas. With the heat exchanger according to the invention, the thermal energy of the hot flue gas can be used via the heating gas for heating or preheating a substance.

For example, the primary medium is a hot flue gas from a combustion chamber of a smoldering furnace according to EP 0 302 310 and the secondary medium is a heating gas for heating a pyrolysis reactor of a smoldering furnace. A heat exchanger according to the invention can therefore be usefully used in a smoldering plant known as such. By working reliably and with simple means, quickly, inexpensively and reliably The heat exchanger to be built can direct heat energy from the very hot flue gas into the pyrolysis reactor for preheating the material to be smoldered there.

With the heat exchanger according to the invention, a heat exchanger is provided which can be operated with simple, commercially available and inexpensive means, e.g. Corrugated iron, is quick to assemble and works reliably. In particular, its function cannot be impaired by thermal expansion of its material.

FIG 1

zeigt perspektivisch einen Wärmetauscher;

FIG 2

zeigt einen Teilschnitt durch den Wärmetauscher.

A heat exchanger according to the invention is explained in more detail with reference to the drawing.

FIG. 1

shows in perspective a heat exchanger;

FIG 2

shows a partial section through the heat exchanger.

The heat exchanger 1 according to FIG. 1 consists of a primary space 2 in which a hot primary medium, for example hot flue gas R, flows, and a secondary space 3 in which a heat-absorbing secondary medium, for example heating gas H for a pyrolysis reactor, flows. The primary space 2 and the secondary space 3 are separated from one another by a wall 4. According to FIG. 1, this wall 4 forms a tube with a round cross section. However, any other cross section is also possible. The secondary space 3 is delimited by an outer cladding sheet 5 in addition to the wall 4. The secondary space 3 therefore forms an annular space around the primary space 2. The secondary space 3 is divided by a profiled sheet 6 into an inner partial space 3a and an outer partial space 3b. The profiled sheet 6 can be a self-contained corrugated sheet which alternately touches the wall 4 and the outer jacket sheet 5 in a sinusoidally curved manner. As a result, the inner sub-space 3a and the outer sub-space 3b of the secondary space 3 are each subdivided into subspaces and the profiled one Sheet 6 serves as a spacer for the wall 4 and the outer cladding sheet 5. An exchange of heating gas H may be possible between the respective lower part spaces, since the profiled sheet 6 is not gas-tightly connected to the wall 4 and the outer cladding sheet 5.

The two sub-rooms 3a and 3b are connected to one another on one end of the heat exchanger 1, in FIG. 1 on the lower end, and are closed off from the outside. This connection is provided by a floor 7. The profiled sheet 6 ends at a distance above the floor 7. The heating gas H can therefore reach the inner partial space 3a or vice versa via this distance from the outer partial space 3b.

A feed line 8 is provided for feeding heating gas H into the secondary space 3. This opens into a first collecting duct 9, which surrounds the heat exchanger 1. The first collecting duct 9 is open to the outer part space 3b. In FIG. 1, the outer partial space 3b above the first collecting duct 9 is closed by a sealing plate 10 arranged between the outer jacket plate 5 and the profiled plate 6. This ensures that the supplied heating gas H is always conducted downward in the outer subspace 3b. The heating gas H is distributed through the first collecting duct 9 to the lower part spaces of the outer part space 3b. Between the bottom 7 and the lower end of the profiled sheet 6, the direction of flow of the heating gas H is reversed and the heating gas H passes from the outer part space 3b into the inner part space 3a. There it flows upwards according to FIG. 1. At the upper end of the heat exchanger 1 there is a second collecting duct 11 which is open to the inner part 3a, but not to the outer part 3b. The second collecting duct 11 can be separated from the outer partial space 3b by the sealing plate 10. However, there may also be a separate sheet, so that an opening up to the profiled is provided between the collecting channels 9 and 11 from the outside Sheet 6 is enough. The second collecting duct 11 receives the heating gas H, which first flows from top to bottom in the outer part space 3b and then from bottom to top in the inner part space 3a. A discharge line 12 for the heating gas H is connected to the second collecting duct 11. The profiled sheet 6 is mechanically connected to the wall 4 by the second collecting duct 11. Instead, there can be another rigid connection on the upper section of the heat exchanger 1. The outer jacket plate 5 is connected to the profiled plate 6 by the first collecting duct 9 and the closure plate 10. The closure plate 10 can also be connected directly to the second collecting duct 11 instead of the profiled plate 6 or even be part of the second collecting duct 11.

The hot primary medium flows in the primary space, for example flue gas R, the temperature of which can be above 800 ° C. The primary space 2, like the secondary space 3, is connected to supply lines and discharge lines, not shown in FIG.

The wall 4 of the primary space 2 consists of a heat-resistant material. For example, it is pinned and covered with a refractory ceramic mass 14. All other parts of the heat exchanger 1 can consist of an inexpensive sheet, since they only come into contact with the cooler secondary medium, the heating gas H. The heating gas H has, for example, the temperature 250 ° C. in the feed line 8 and the temperature 600 ° C. in the discharge line 12.

FIG. 2 shows a radial section through the secondary space 3 of the heat exchanger 1 according to FIG. 1. The wall 4 of the primary space 2 is provided with pins 13 on the side of the primary space 2 and coated with a refractory ceramic mass 14. The pins 13 enable the ceramic mass 14 to adhere well. The secondary space 3 is delimited by the wall 4 and the outer jacket plate 5. Through the profiled sheet 6, its profiling Is not visible in the sectional view of Figure 2, the secondary space 3 is divided into an inner part space 3a and an outer part space 3b. Depending on the location of the radial cut, the profiled sheet 6 is struck directly on the wall 4, directly on the outer jacket sheet 5 or at any location in between. This is due to the fact that the profiled sheet 6 is profiled in a plane perpendicular to the plane of the drawing and perpendicular to the wall 4, the profile covering the entire width of the secondary space 3. The profile of the profiled sheet 6 can be an angular profile or a round, for example sinusoidal profile, but also any other type of profile. The outer jacket plate 5 is connected to the wall 4 by a base 7. This bottom 7 can be box-shaped. The bottom 7 can also be elastic to compensate for different thermal expansions. The profiled sheet 6 ends in the secondary space 3 at a distance above the floor 7. The outer partial space 3b is closed at the top by a closure sheet 10. Below the closure plate 10, the outer sub-space 3b is connected to a feed line 8. A first collecting duct 9 can be located between the feed line 8 and the outer sub-space 3b. This connects the individual sub-spaces of the outer sub-space 3b formed by the profiling of the profiled sheet 6. The inner compartment 3a is connected to a drain 12. Here, a second collecting duct 11 can be interposed, which first collects the secondary medium emerging from sub-compartments of the inner sub-compartment 3a. According to FIG. 2, the profiled sheet 6 is exclusively attached to the second collecting duct 11. It hangs similarly to a curtain in the secondary space 3. As a result, thermal expansions of the profiled sheet 6 can have no effects on other components of the heat exchanger 1. The first collecting duct 9 and the outer jacket plate 5 are held on the profiled plate 6 via the closing plate 10. The Primary medium, in particular flue gas R, flows through the primary space at, for example, 800 ° C. The secondary medium, in particular heating gas H, flows, for example at 250 ° C., through the feed line 8 and the first collecting duct 9 into the outer subspace 3b of the secondary space. There it flows downwards, changes its direction of flow in front of the floor 7 and then flows upwards in the inner part space 3a. From there, it reaches the discharge line 12, for example heated to 600 ° C., via the second collecting duct 11.

With the heat exchanger 1 according to the invention the advantage is achieved that only inexpensive material such as corrugated sheet is required to build the secondary space 3 instead of expensive pipes and that thermal expansion of the components of the heat exchanger 1 remain without affecting its stability.

Claims (17)

1. Heat exchanger (1) having a primary chamber (2) for a primary medium, and a secondary chamber (3) for a secondary medium which is separated by a gas-tight, heat-conducting wall (4) from the primary chamber (2) and which is bounded at the side by an outer wall and, at the bottom, by a base (7), characterised in that the outer wall is a jacket sheet (5) and in that the secondary chamber (3) is subdivided by a profiled sheet (6) into an inner partial chamber (3a) and an outer partial chamber (3b).
2. Heat exchanger (1) according to claim 1, characterised in that the profiled sheet (6) extends in the flow direction of the primary medium and is profiled in a plane at right angles to the flow direction of the primary medium.
3. Heat exchanger (1) according to claim 1 or 2, characterised in that the profiled sheet (6) alternately touches the wall (4) and the outer jacket sheet (5), forming compartmented partial chambers, and in that the outer jacket sheet (5) is kept at a constant distance from the wall (4).
4. Heat exchanger (1) according to one of claims 1 to 3, characterised in that the profiled sheet (6) is secured at its upper portion and hangs freely downwards between the wall (4) and the outer jacket sheet (5).
5. Heat exchanger (1) according to one of claims 1 to 4, characterised in that the two partial chambers (3a and 3b) are joined together at one end of the profiled sheet (6) and are closed to the outside, and in that at the other end the outer partial chamber (3b) is connected to a supply line (8), and the inner partial chamber (3a) is connected to a discharge line (12).
6. Heat exchanger (1) according to claim 5, characterised in that the wall (4) and the outer jacket sheet (5) are joined in a gas-tight manner at one front end of the profiled sheet (6) by the base (7), and in that there the profiled sheet (6) ends at a distance from the bottom (7).
7. Heat exchanger (1) according to claim 6, characterised in that the base (7) is elastic.
8. Heat exchanger (1) according to one of claims 6 or 7, characterised in that the outer partial chamber (3b) is closed at the other end by a closure sheet (10) which extends between the profiled sheet (6) and the outer jacket sheet (5), in that a second collecting conduit (11) open towards the inner partial chamber (3a) is disposed on the end of the closure sheet (10), wherein the second collecting conduit (11) is connected to the discharge line (12), and in that a first collecting conduit (9) open towards the outer partial chamber (3b) is disposed on the other side of the closure sheet (10), wherein the first collecting conduit (9) is connected to the supply line (8).
9. Heat exchanger (1) according to claim 8, characterised in that the first collecting conduit (9) is located on the outer surface of the outer jacket sheet (5), the outer jacket sheet (5) having a continuous opening leading to the first collecting conduit (9).
10. Heat exchanger (1) according to one of claims 8 or 9, characterised in that the profiled sheet (6) is secured by suspension only from its upper portion.
11. Heat exchanger (1) according to one of claims 1 to 10, characterised in that the profiled sheet (6) has a polygonal profile.
12. Heat exchanger (1) according to one of claims 1 to 10, characterised in that the profiled sheet (6) is a corrugated sheet with a sinusoidal profile.
13. Heat exchanger (1) according to one of claims 1 to 12, characterised in that the profiled sheet (6) and/or the jacket sheet (5) and/or other parts of the secondary chamber (3) are made of steel.
14. Heat exchanger (1) according to one of claims 1 to 13, characterised in that the wall of the primary chamber (2) is made of high temperature-resistant material, and the profiled sheet (6) is made of less expensive material.
15. Heat exchanger (1) according to one of claims 1 to 14, characterised in that the wall (4) is provided with pins (13) on its side facing the primary chamber (2) and is tamped with a fireproof ceramic material (14).
16. Heat exchanger (1) according to one of claims 1 to 15, characterised in that the primary medium is a hot flue gas, and the secondary medium is a heating gas.
17. Heat exchanger (1) according to claim 16, characterised in that the primary medium is a hot flue gas from a combustion chamber of a low temperature incineration plant, and in that the secondary medium is a heating gas for heating a pyrolysis reactor of a low temperature incineration plant.

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