EP0389971A2 - Ceramic heat exchanger - Google Patents

Abstract

Provided for the purpose of recuperative heat exchange between a gaseous and a liquid material flow is a ceramic heat exchanger with a heat exchanger matrix which has adjacently arranged gas ducts 1 and liquid ducts 2 having a slot-shaped cross-section and extending parallel to one another. Let into the boundary walls of the heat exchanger matrix for the purpose of admitting and discharging the material flows are corresponding admission and discharge openings 3, 18, 19. In order to be able to configure the media connections independently of the dimension of the heat exchanger matrix that is required for the heat exchange, guide pockets 23, 24 which cover the boundary walls 20 on both sides of the heat exchanger matrix and whose cross-section widens starting from the liquid admission and discharge slots 18, 19 are provided on the liquid admission and discharge slots 18, 19 for the purpose of guiding the liquid material flow. Moreover, connecting openings 12, 13 which have connecting sockets 31, 32 for connecting liquid lines 41, 42 are arranged at the ends of the widened region of the guide pockets 23, 24. Webs 16, 17, 29 are inserted in the slot-shaped gas and liquid ducts 1, 2 for the purpose of guiding gas and liquid. …<IMAGE>…

Description

The invention relates to a ceramic heat exchanger for recuperative heat exchange between a gaseous and a liquid material flow in a heat exchanger matrix with slot-shaped gas channels and liquid channels running parallel to one another. The features of the ceramic heat exchanger from which the invention is based are specified in the preamble of claim 1.

Recuperative ceramic heat exchangers with slot-shaped flow channels for the media and correspondingly shaped inlet and outlet openings are known from DE-PS 27 07 290 and DE-PS 28 41 571. The dimension of these heat exchangers determines in the usual way the number of flow channels required for the heat exchange. In most cases, there is only a small area available for connecting media lines. Metallic connections for the media, which have to be connected to the ceramic heat exchanger for the supply and discharge of the media, are therefore difficult to accommodate and because of the level sealing surfaces required and because of the desired uniform flow through the heat exchanger matrix, especially in the liquid-carrying area, only with great effort to design that a secure seal of the connections is achieved even with higher media pressure.

From DE-OS 23 60 785 a metallic heat exchanger is known, the structure of which separates gas of a gas developing liquid involved in the heat exchange. Partition walls are provided in the liquid channels, which are intended to separate liquid and gas. The connections of the media lines on the heat exchanger take into account the desired media separation.

The object of the invention is to provide a ceramic heat exchanger that is easy to design media Connections regardless of the dimension of the heat exchanger matrix required for heat transfer, while at the same time promoting a uniform flow through the heat exchanger matrix, in particular in its area through which the liquid flows.

This object is achieved in a ceramic heat exchanger of the type mentioned by the features specified in claim 1. Thereafter, guide pockets are provided for guiding the liquid stream to the liquid inlet slots and away from the liquid outlet slots, which cover the boundary walls of the heat exchanger matrix in which the liquid inlet and outlet slots are arranged. The cross section of the guide pockets widens in each case starting from the liquid inlet or outlet slots, with connection openings with connecting pieces for the connection of liquid lines being arranged in the enlarged area. The flow guidance achieved by narrowing the cross-section of the guide pockets is supported by arranging webs in the liquid channels of the heat exchanger matrix. Flows for flow guidance are also provided in the gas channels. In this way, an optimal distribution of the media in heat exchange in their flow channels is achieved which is adapted to the desired heat exchange. Streaking is prevented.

For better liquid distribution, guide webs extending from the liquid inlet slots for introducing the liquid and at the liquid outlet in front of the liquid outlet slots are arranged in the liquid channels in the liquid channels. The deflection bars act in the liquid on the liquid A turbulent flow emerges, which significantly increases the heat exchange in this area of the heat exchanger matrix. In this way, the material temperature of the heat exchanger can also be kept low in the inlet area of the hot gas and the inflowing gas can be cooled rapidly immediately after it has entered the gas channels. The webs in the gas channels expediently run straight from the gas inlet to the gas outlet.

In a further embodiment of the invention according to claim 4, the guide pockets with the walls delimiting them and the heat exchanger matrix are integrated in the ceramic heat exchanger in such a way that the guide pockets and heat exchanger matrix form a uniform ceramic block. A simple structure of this block is obtained with a wedge-shaped design of the guide pockets, the liquid inlet and outlet slots are then expediently located in the area of the wedge tips of the guide pockets located on the inflow and outflow side of the heat exchanger matrix is achieved by slightly tilting the heat exchanger matrix in the heat exchanger. This results in an optimal use of space for the heat exchanger block, which is expediently cuboid.

The shape of the liquid pockets with a narrowing of the flow cross-section obtained on the one hand at the liquid inlet from the liquid inlet to the liquid inlet slots on the heat exchanger matrix creates a liquid accumulation which leads to a uniform liquid distribution in the heat exchanger matrix. On the other hand, on the The outlet side for the liquid from the liquid outlet slots to the liquid outlet in the guide pockets is an expansion of the flow cross section which favors the outflow of the liquid.

In order to connect metallic line connections for the liquid in the heat exchange in a simple manner with the connection openings of the heat exchanger, tie rods are provided on the guide pockets according to claim 6, which extend through the free space of the guide pockets between two opposite connection openings and have the screw connections on which Connection pieces for the liquid lines are to be fastened. For clear positioning of the connecting pieces, they are provided with anti-rotation locks and for watertight connection to the heat exchanger with insertable sealing rings. The liquid lines can be easily connected via an internal thread in the connecting piece. The connection pieces can also be closed with blind plugs.

To ventilate the liquid-carrying area of the heat exchanger matrix, closable ventilation devices are attached in the area of the wedge tips of the guide pockets. An automatic deaerator can also be easily connected to these ventilation devices.

In the case of a heat exchanger manufactured in a layered construction, it is expedient to use the layers forming the heat exchanger both to form the heat exchanger matrix and to form the guide pockets. For this purpose, wall layers and web layers of the heat exchanger have corresponding cutouts for forming suitable flow spaces, patent claim 8.

• Figur 1 Halbschnitt eines Wärmeübertragers gemäß Schnittlinie A/A nach Figur 2;
• Figur 2 Längsschnitt des Wärmeübertragers nach Figur 1 gemäß Schnittlinie B/B;
• Figur 3 Längsschnitt des Wärmeübertragers nach Figur 1 gemäß Schnittlinie C/C;
• Figur 4 Längsschnitt des Wärmeübertragers nach Figur 1 gemäß Schnittlinie D/D;
• Figur 5 Längsschnitt des Wärmeübertragers nach Figur 1 gemäß Schnittlinie E/E.

The invention is explained below with reference to an embodiment shown in the drawing. The drawing shows in detail:

• Figure 1 half section of a heat exchanger according to section line A / A of Figure 2;
• Figure 2 shows a longitudinal section of the heat exchanger according to Figure 1 along section line B / B;
• Figure 3 shows a longitudinal section of the heat exchanger according to Figure 1 along section line C / C;
• Figure 4 shows a longitudinal section of the heat exchanger according to Figure 1 along section line D / D;
• 5 shows a longitudinal section of the heat exchanger according to FIG. 1 along section line E / E.

As can be seen from FIG. 1, the heat exchanger shown in the exemplary embodiment is a ceramic heat exchanger produced in a layered construction. The heat exchanger consists of individual ceramic layers which have cutouts for the formation of flow spaces for the media in the heat exchange. The individual layers are put together in multiple layers, so that cavities delimited by partition walls arise through which the media in heat exchange can be passed. The layers are placed on top of each other in the green state of the ceramic and thereby fixed to one another. The green body of the heat exchanger formed in this way is then sintered and into a uniform ceramic block with gas-tight walls processed between the flow spaces of the media. Silicon carbide and silicon nitride are particularly suitable as the ceramic material for the production of the heat exchanger.

The sequence of the individual ceramic layers from which the heat exchanger is constructed are shown individually in FIG. 1 in the heat exchanger and in FIGS. 2 to 5.

Figure 1 shows a half section of a heat exchanger with gas channels 1 and liquid channels 2 for the media in heat exchange. In the exemplary embodiment, water is heated by hot gas. The hot gas as a heat carrier flows through the gas channels 1 from inflow openings 3 to outflow openings 4, which are each arranged on opposite end faces 5 and 6 of the heat exchanger, as can be seen from FIG. 5. The direction of flow of the gases in the gas channels 1 is indicated by arrows 7 in FIG. The slot-shaped design of the gas channels 1 can be seen from FIG.

The water to be heated is guided in the likewise slit-shaped liquid channels 2 through the inner part of the heat exchanger. This inner part, which is used for heat exchange between hot gas and water to be heated, forms the heat exchanger matrix. The direction of flow of the water as it flows through the heat exchanger is marked by arrows 8, which are entered in FIG. 1 and FIG. 3. In the exemplary embodiment, the water flows in the liquid channels 2 in countercurrent to the hot gas in the gas channels 1.

The water to be heated is supplied to and in the heat exchanger on the long sides 9, 10 of the heat exchanger dissipated, which run perpendicular to the end faces 5 and 6. Longitudinal walls 11 formed on these long sides 9, 10 are formed by joining together wall layers 12, one of which is shown in FIG. 2. The wall layer 12 has recesses for forming connection openings 13, 14 for supplying and discharging the water to be heated in the heat exchanger. The description of the connection of the water-carrying liquid lines to the heat exchanger is made again in the following section.

In the heat exchanger, the wall layers 12 are connected - in the exemplary embodiment, six wall layers 12 are stacked on top of one another to form the longitudinal wall 11 - multi-layer web layers 15 for forming the liquid channels 2 for the water. The web layers 15 are shown in FIG. 3. The web layers 15 have webs 16, 17 in the region of the heat exchanger matrix, namely guide webs 16 and deflection webs 17 for guiding the water to be heated in the liquid channel 2. The guide webs 16 start from liquid inlet slots 18 and serve for uniform distribution of the water over the cross section of the liquid channel 2. The deflection bars 17 are arranged in front of liquid outlet slots 19 for swirling the water and for improving the heat transfer into this area.

In addition to the guiding and deflecting webs 16, 17 which serve to guide the water, the web layers 15 are used to form both boundary walls 20 for the heat exchanger matrix and outer walls 21, 22 for the heat exchanger. The latter is, on the one hand, the formation of end walls 21 and, on the other hand, the formation of longitudinal walls 22.

Between the boundary walls 20 of the heat exchanger matrix and the longitudinal walls 22 there remain recesses for the formation of guide pockets 23, 24, via which the water to be heated is fed into or out of the heat exchanger matrix. In Figure 3, the arrows 8 already mentioned indicate the flow direction of the water. In the exemplary embodiment, the guide pockets are wedge-shaped, the liquid inlet or outlet slots 18, 19 being arranged in the region of wedge tips 25, 26 of the guide pockets 23, 24, respectively.

The web layers 15 shown in FIG. 3 - in the exemplary embodiment, three web layers 15 are placed one on top of the other to form a liquid channel 2 - are followed by a wall layer 27 when the ceramic heat exchanger is assembled, as shown in FIG. The liquid channel 2 is first covered with this wall layer in the area of the heat exchanger matrix. The heat exchange between the water to be heated and the hot gas takes place via the wall layer 27. The wall layer 27 forms the boundary wall between gas channels 1 and liquid channels 2. In its edge region, the wall layer 27 has recesses 28 which produce the necessary spatial connections for distributing the water in the guide pockets 23, 24. Between the recesses 28 there remain webs 29 which take up the mechanical loads in the wall area of the heat exchanger that arise due to the excess liquid pressure in the liquid pockets and introduce them into longitudinal walls 22 and boundary walls 20.

A web layer 30 for forming the gas channels 1 is shown in FIG. The web layer 30 has webs 30 'for guiding the hot gas, the webs 30' ver run straight. The gas flow is marked by arrows 7. In the edge region of the web layer 30 there are again recesses for the formation of the guide pockets 23, 24, via which the water to be heated is supplied or discharged. Since these areas of the guide pockets 23, 24 are directly adjacent to the gas channels, heat exchange between liquid and hot gases also takes place in this area. The outer parts of the web layer 30 again form the outer walls 21, 22 of the heat exchanger, namely the end walls 21 and the longitudinal walls 22.

A wall layer 27 (FIG. 4) follows again on the web layers 30, of which three web layers 30 are stacked on top of one another in the exemplary embodiment for forming the gas channels 1. This is followed again by web layers 15 (FIG. 3) to form the liquid channels 2 and finally a wall layer 27 is again applied.

If the formation of the prescribed number of gas channels 1 and liquid channels 2 for the heat exchanger has ended, wall layers 12 (FIG. 2) with connection openings 13, 14 for supplying and removing the water to be heated in the heat exchange follow again at the end of the heat exchanger. The wall layers 12 close the heat exchanger after stacking all the above-described wall and web layers on its long side 10 to form a further longitudinal wall 11, see FIG. 1. To form the longitudinal wall 11, six wall layers 12 are put together.

Due to the inclined position of the heat exchanger matrix with respect to the rectangular butting outer walls of the heat exchanger, the result when the layers are stacked Wall and web layers, the two guide pockets 23, 24 arranged on both sides of the heat exchanger matrix with a wedge-shaped design. This shape of the guide pockets enables a good distribution of the water in the inlet and outlet area of the heat exchanger. A coherent flow area for the water is created, through which the water can be introduced into the heat exchanger matrix or can be removed from the heat exchanger matrix after it has been heated.

In the connection openings 13, 14 formed in the guide pockets 23, 24, as is shown in FIG. 1, connection sockets 31, 32 with anti-rotation devices 33, 34 and sealing rings 35, 36 are inserted and sealed tightly by tie rods 37, 38 with screw connections 39, 40 the connection openings 13, 14 placed. The tie rods penetrate the free space of the guide pockets 23, 24 and are attached to the opposite connection openings 13, 14.

The respective opposite connecting pieces 31, 32 can either be connected on both sides to a liquid line or, as is the case in the exemplary embodiment, connected to a liquid line 41 or 42 on only one side, and closed on the other side by a blind closure 43, 44 will.

To vent the water-carrying area of the heat exchanger, venting devices 45, 46 are provided in the area of the wedge tips 25, 26 of the guide pockets 23, 24. In the exemplary embodiment, the venting devices 45, 46 are closed by screwed-in plugs 47, 48. However, automatically working ventilators can also be connected to the venting devices.

After stacking all the wall and web layers 12, 15, 27, 30 in the green state, the heat exchanger is sintered according to the ceramic material used and formed into a uniform gas and pressure water-tight ceramic heat exchanger block. Due to the design of the individual layers, the heat exchanger matrix and the guide pockets with their connections for the liquid lines are integrated in this block.

Claims (8)

1. Ceramic heat exchanger for heat exchange between a gaseous and a liquid material flow with a heat exchanger matrix with cross-sectionally slit-shaped, adjacently arranged and parallel gas channels and liquid channels with liquid inlet and liquid outlet slots in boundary walls of the heat exchanger matrix, the gas and liquid channels at the edge of the Cover slots,
characterized,
that guide pockets (23, 24) covering the boundary walls (20) are provided on both sides of the heat exchanger matrix for guiding the liquid material flow at the liquid inlet and outlet slots (18, 19), the cross-section of which starts from the liquid inlet and outlet slots (18 , 19), and that at the ends of the expanded area of the guide pockets (23, 24) connection openings (13, 14) with connection pieces (31, 32) for connecting liquid lines (41, 42) are arranged, and that in the slot-shaped gas and liquid channels (1, 2) webs (16, 17, 29, 30 ') are provided for guiding gas and liquid. 2. Ceramic heat exchanger according to claim 1,
characterized,
that guide webs (16) extending from the liquid inlet slots (18) for introducing the liquid and in front of the liquid outlet slots (19) are arranged in the liquid channels (2) deflecting webs (17). 3. Ceramic heat exchanger according to claim 1 or 2,
characterized,
that the webs (30 ') in the gas channels (1) from the gas inlet to inflow openings (3) to the gas outlet at outflow openings (4) run in a straight line. 4. Ceramic heat exchanger according to one of the preceding claims,
characterized,
that the guide pockets (23, 24) with the walls delimiting them and the heat exchanger matrix are integrated in a uniform ceramic heat exchanger block. 5. Ceramic heat exchanger according to one of the preceding claims,
characterized,
that the guide pockets (23, 24) are wedge-shaped. 6. Ceramic heat exchanger according to one of the preceding claims,
characterized,
that for the connection of liquid lines (41, 42) to the guide pockets (23, 24) tie rods (37, 38) are provided, which are attached to opposite connection openings (13, 14) on the guide pockets (23, 24) and by the guide pockets (23, 24) run through, and at the screw connections (39, 40) connecting pieces (31, 32) with rotation locks (33, 34) are connected liquid-tight, the connecting pieces (31, 32) with liquid lines (41, 42 ) or blind fasteners (43, 44) can be connected. 7. Ceramic heat exchanger according to one of the preceding claims,
characterized,
that the guide pockets (23, 24) in the area of the wedge tips (25, 26) have closable ventilation devices (45, 46). 8. Ceramic heat exchanger according to one of the preceding claims,
marked by
a layered structure, the ceramic layers (12, 15, 27, 30) forming the heat exchanger simultaneously forming the heat exchanger matrix and guide pockets (23, 24) and forming the flow spaces in wall layers (12, 27) and web layers (15, 30) Have corresponding recesses in flow spaces.

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