EP2684001A1

EP2684001A1 - Heat exchanger for a mobile solid-fuel firing system

Info

Publication number: EP2684001A1
Application number: EP12714834.4A
Authority: EP
Inventors: Johannes LANDRICHINGER
Original assignee: Lasco Heutechnik GmbH
Current assignee: Lasco Heutechnik GmbH
Priority date: 2011-03-08
Filing date: 2012-03-08
Publication date: 2014-01-15
Anticipated expiration: 2032-03-08
Also published as: EP2684001B1; WO2012120369A1; DE202011103414U1; AT12584U1

Abstract

The invention relates to a heat exchanger (22) for a mobile solid-fuel firing system (2) comprising a hot gas connection (38) and an inner gas duct (32), a cooling gas connection (58) and an outer gas duct (34) and a wall (30) separating the gas ducts (32, 34) and conducting heat, for producing a heat transfer from the hot gas to the colder gas. Defined gas ducting and a low weight of the heat exchanger can be achieved if the wall (30) comprises a number of interconnected corrugated sheets (74), between which both gas ducts (32, 34) run.

Description

Heat exchanger for a mobile solid fuel firing system

description

The invention relates to a heat exchanger for a mobile solid fuel combustion system with a hot gas connection and an inner gas guide, a cooling gas connection and an outer gas guide and the two guides separating and heat-conducting wall for producing a heat transfer from the hot to the colder gas.

Mobile solid fuel firing systems are used to generate large amounts of heat for a limited period of time in one location. Possible applications are, for example, the generation of heat for drying hay, the heating of a building or a large tent or the short-term provision of heat for industrial processes. For this purpose, the solid fuel firing system is driven to the site, parked there and put into operation.

For operation, a solid fuel container may be connected to a combustion chamber of the solid fuel furnace by means of a fuel delivery mechanism. The solid fuel is burned in the combustion chamber, the heat released is a heat carrier, usually water, is fed, which is guided around the combustion chamber for receiving the heat.-Is. A heat exchanger transfers the heat to the place of use.

It is an object of the present invention to provide a heat exchanger which is particularly suitable for use in a mobile solid fuel burning plant. This object is achieved by the heat exchanger of the type mentioned, in which according to the invention, the wall comprises a plurality of interconnected corrugated sheets extending between the two gas passages.

The invention is based on the consideration that it is important for mobile use of the solid fuel combustion system that it is as light as possible. Thus, the entire solid fuel firing system - in the following simplified also called firing plant - with simple means, such as a forklift, be raised. In this regard, a conventional heat transfer from the combustion chamber or the flue gas to water is disadvantageous because here the water must be carried as a heat transfer medium in the furnace and thus contributes to its weight.

Significantly weight-saving, it is when the heat from the hot flue gas is delivered directly to the cooling gas, which is now available for further use, for example for hay drying or tent heating. Accordingly, the heat exchanger has a hot gas connection and a cooling gas connection, so that the heat is transferred directly from the hot gas to the cooling gas.

If flue gas is used as hot gas, which flows from the combustion chamber into the heat exchanger, the heat exchanger is exposed to extreme thermal loads. The wall for heat transfer should therefore be made of a very heat-resistant and chemically resistant steel in order to avoid a strong oxidation of the wall. Particularly suitable materials are very expensive. A cost-saving measure is to provide cheaper materials in a thicker wall thickness. These, too, satisfy the requirement of sufficient the longevity. However, a thicker wall causes the he ^¬ heblichen disadvantage of a high weight with in to the application in the mobile Festbrennstofffeuerungsanlage. The invention is based on the further consideration that noble steels are much cheaper available in sheets than in tube form. The use of sheet metal as the wall of the heat exchanger therefore makes it possible to resort to noble steels in a cost-effective framework, thereby enabling a thin design of the wall and thus a weight-saving construction of the heat exchanger. The disadvantage of higher costs is therefore offset by the advantage of weight savings, which is of considerable importance for mobile solid fuel firing systems. In addition, a large heat transfer area per weight can be achieved with metal sheets, so that a corrugated metal heat exchanger with the same transfer capacity and wall thickness is lighter than a tube bundle heat exchanger.

The use of stainless steel sheets as a wall for the heat exchanger, however, involves the difficulty that the mechanical stability of thin sheets is lower than that of thick pipes. This can be a problem especially in a mobile Feue ^¬ tion system, as they are exposed to particularly high mechanical stresses that go beyond the usual thermal stress. Thus, the firing system must survive a transport and associated jerking and bumping harmless and is especially in a hard settling on. Site exposed to a strong shock. In this respect, the heat exchanger must be made mechanically very stable in order to reliably prevent cracking or twisting. Due to the shape of the corrugated sheet can be a mechanical very. stable construction of the heat exchanger can be achieved, which is up to the high demands of mobile use. Therefore, by means of the invention a weight-saving, mechanically stable and sufficiently inexpensive heat exchanger can be provided.

The furnace is expediently a Holzfeuerungs ^¬ system for operation with wood chips, for example. The hot gas connection can serve as a flue gas connection, through which the hot flue gas produced in the combustion chamber of the combustion system is guided. The cooling gas connection can be an ambient air connection, through which ambient air is introduced for cooling the wall. The corrugated sheets may have flat surfaces or be executed purely with curved surfaces. They can be wavy or edged, eg with a trapezoidal wave, a rectangular wave, a triangular wave or in another, edges

^■ . r

having form. Even rounded edges are possible and advantageous.

The outer gas guide is expediently designed so that the outer gas flow guided in it flows around the inner gas guide. The internal gas guide is suitably arranged to shield the internal gas carried therein from the environment, at least until it reaches a predetermined state, e.g. has cooled sufficiently. Further, it is advantageous if the outer gas guide is applied at least predominantly transversely to the inner gas guide. As a result, a uniform cooling of the inner gas guide can be achieved.

The heat exchanger according to the invention is particularly suitable for use in a mobile solid fuel firing system, but its use is not limited to a mobile firing system, since its advantages can also be used in stationary furnaces. In an advantageous embodiment of the invention, the corrugated sheets are connected in pairs in such a way that convex. Inner surface portions of the corrugated sheets je ^¬ Weils pairs and concave inner surface portions of the corrugated ^¬ plates each pairwise opposite. In this way, a pair of corrugated sheets can form a number of tubes that form at least part of the inner gas guide, so that the Innengas- leadership runs through the tubes thus formed.

Conveniently, the corrugated plate pairs are connected to each other at the convex inner surface portions. Such a connection can be achieved by welding, e.g. with a roll seam welding process. The corrugated sheets of the pair of corrugated sheets can be placed on top of one another in such a way that the convex inner surface portions touch each other in a straight line so that a good directional guidance is created within the inner gas guide.

It is further proposed that the concave inner surface sections in pairs form a tube. This also allows a particularly good flow guidance in the Innengasfüh- tion can be achieved.

Conveniently, the corrugated sheets are placed on each other such that the tubes are formed so that their interiors in the region of their parallel course at least by juxtaposition of the sheets. are essentially separate from each other. This also allows a particularly good flow guidance of the inner gas guide can be achieved.

Advantageously, the inner gas duct runs as a hot gas duct through the tubes. For this purpose, the tubes are advantageously connected to the hot gas connection so that flows through this flowing hot gas and through the tubes. The Internal gas guide may be a flue gas duct and the Außengasfüh tion an ambient air. However, it is also mög ^¬ Lich the hot gas of the external gas supply and the cooling gas inside the gas routing to forward.

A further advantageous embodiment of the invention provides that in each case two pairs of plates are so angeord net to each other, that they form between them a wavy flow area as part of the outer gas guide. It can be a good mixing of the externally guided gas and thus a good heat transfer between hot gas and cold gas can be achieved.

Advantageously, several tubes are formed between pairs of plates, wherein the wave-shaped throughflow region can be traversed perpendicularly to the longitudinal direction of the tubes, in particular can flow through in a wave-like manner.

A compact design of the heat exchanger can be achieved if between two pairs of sheets a third pair of plates is arranged such that convex outer surface portions of the third pair of sheets come to rest between concave outer surface portions of the two surrounding pairs.

In particular, in the case of a crossing flow arrangement of the inner gas guide and the outer gas guide, the problem may arise that at least one of the gas guides from the gas guide section is short, which is not conducive to good heat transfer. This problem can be solved if the corrugated sheets form a plurality of parallel tubes and the outer gas guide crosses at least some of the tubes on the outside, is deflected in their direction and these tubes crosses a second outside. Through this deflection, a long contact of ^" outside and inside flow over the wall formed and so on good heat transfer can be achieved. The crossing is expediently carried out at an angle of at least 70 degrees, in particular of at least 80 degrees.

It is also advantageous if the corrugated sheets form a plurality of parallel tubes and the outer gas guide is guided by means of at least two baffles S-shaped through the corrugated sheets, so that it extends transversely and parallel to the tubes. This also allows a long combination of inner and outer gas guide formed and a good heat transfer can be achieved. Under parallel and transverse to the tubes is a parallel or transverse guide to the tube longitudinal direction understood, with a transverse guide is understood at an angle of at least 70 degrees, suitably at least 80 degrees and in particular perpendicular to the tube longitudinal direction.

A uniform heat transfer between the two gas ducts, it is also beneficial if the corrugated sheets form a plurality of parallel inner tubes, which are divided into two groups, each with a plurality of separate Außengas- Kanäien between which a mixing section is arranged, in which open the outer gas channels , In this mixing section expediently also the baffles, whereby a simple and stable construction of both the baffles and the heat exchanger is achievable.

Further expediently, the inner gas guide is guided successively through the two groups of the inner tubes, which are arranged in particular parallel to one another. This allows a long gas flow in a confined space can be achieved. Good heat utilization of the hot gas can be further assisted if the outer gas guide runs in a countercurrent flow to the inner gas guide _. , Cool external gas soon meets relatively cool internal gas, and later on hotter external gas encounters hotter internal gas, whereby the heat content of already cooled hot gas is still effectively used to preheat the cooling gas.

It is also advantageous if the corrugated sheets each have a collar on at least one end. This can be beneficial for. an attachment of the corrugated sheets to each other - directly or indirectly - be used. The attachment to each other may be via a retaining means, e.g. a head plate, a Fußblech or the like. The attachment can be done by welding, bolting, gluing, riveting or other methods.

In particular, the corrugated sheets are formed at least one end to a collar, so the collar is' formed from the corrugated sheet. For this purpose, the. Corrugated sheet can be bent to the collar. It is. also possible to first make the collar and then bring the corrugation in the corrugated sheet.

Conveniently, the collars are arranged transversely to the orientation of the waves. Under cross will be understood in the following an angle between 70 ° and 110 °. The orientation of the waves is parallel to the troughs or mountains.

It is further proposed that the holding means is a sheet metal transverse alignment of the shafts, and the collar are aligned flat parallel to the sheet .. This allows the collar to be easily and reliably attached to the holding means. The collars are expediently applied flat to the holding means, layers directly or indirectly via one or more intermediate ^¬.

A particularly strong attachment can be achieved when the collars are clamped between the holding means and a counter-element arranged between the corrugated sheets. The clamping is advantageously carried out by screwing or riveting. The counter element extends in particular between the corrugated sheets. For this, it can be tortuous in waveform.

In addition, the invention is directed to a solid fuel combustion system having a combustion chamber, a heat exchanger as described above and a combustion chamber connecting the combustion gas connection with the inner gas connection. It can thereby a thermally and mechanically stable. Unit, combined with a light weight, are formed inside the solid fuel burning plant.

Particularly good air heating can be achieved when the solid fuel firing system includes an ambient air inlet, a warm air outlet, an ambient air channel connecting the ambient air inlet to the outer gas port of the heat exchanger, and a hot air duct connecting an outer gas outlet of the heat exchanger to the hot air outlet. Ambient air can be brought into a heat contact with flue gas directly in the heat exchanger, whereby a good and effective heating of ambient air can be generated even in a high volume, which is particularly suitable for heating large rooms or large volumes of product.

Further, the invention is directed to a mobile hay drying plant with a transportable frame in which a solid fuel burning plant is arranged as described above. In particular, the frame also includes a solid fuel container, whereby a promotion of Festbrennstöff can be kept simple to a combustion chamber of the furnace.

The previously given description of advantageous embodiments of the invention contains numerous features, which are given in the individual subclaims partially summarized in several. However, those skilled in the art will conveniently consider these features individually and summarize them to meaningful further combinations. The same applies to the features of each embodiment of the follow ^¬ the figure description, the explicitly considered isolated and can be combined with the heat exchanger according to the invention.

Show it:

Fig. 1 is a schematic representation of a mobile and

air-cooled Festbrennstöfffeueranlage with a heat exchanger for heating air in a schematic representation,

2 shows the heat exchanger in a perspective view from above,

3 shows the heat exchanger in a schematic side view,

4 is a plan view of a head plate of the heat exchanger,

5 is a perspective view of a corrugated sheet pair of the heat exchanger,

Fig. 6 is a schematic sectional view through three

Corrugated plate pairs of the heat exchanger,

7 is a perspective view of a foot plate of

heat exchanger,

8 is a plan view of a baffle plate of the heat exchanger, a schematic representation of an 'air duct through the heat exchanger,

an alternative corrugated sheet metal pair in one

Top view,

the corrugated sheet metal plate pair of FIG. 10 in a perspective view,

a welded joint of the corrugated sheet metal plates on the longitudinal edge of the corrugated sheet metal plate pair in a

Sectional view

an alternative heat exchanger with a rectilinear external gas guide,

a schematic section through two corrugated metal sheets, which are welded at its head end with a holding means,

an alternative attachment of the corrugated metal sheets on

Holding means over a collar of the corrugated sheets, a rounded transition from the shaft portion to a

Collar area,

two corrugated metal sheets each with a collar bolted to a top plate,

two corrugated sheet metal plates each having a collar which is clamped between a top plate and a counter plate,

two corrugated metal plate pairs of FIG. 18 in one

Top view without the top plate and

the corrugated metal sheet pair. with the head plate.

1 shows a mobile solid fuel firing plant 2-also referred to as firing plant 2 in a simplified manner below-with a rated output of 250 kW and a solid fuel storage 4 in a schematic representation. The solid fuel storage 4 is mobile, so carried portable. For this purpose, both the solid fuel storage 4 and the combustion plant 2 are each indicated only schematically. indicated means of transport 6, 8 provided, by means of which at ^¬ the elements 2, 4 can be raised in each case, for example by a forklift. The transport means 6, 8 comprise a sturdy frame, which holds the other ^'components of the respective element 2; 4.

The solid fuel storage 4 is connected via a connection 10 with the furnace 2, which contains a joint or other angle compensation means, so that any unevenness in the installation of the two elements 2, 4 can be compensated. For this purpose, the connection 10 is additionally provided with a height compensation means for adapting a discharge unit 12. The discharge unit 12 is for example a screw conveyor and serves to transport solid fuel located in the solid fuel storage 4, for example wood chips, to the combustion plant 2.

To operate the furnace 2, this is driven to its place of use, for example, on a truck and parked there on a floor. The solid fuel storage 4 is also driven to the site and parked next to the furnace 2. Subsequently, the two elements 2, 4 connected to each other via the terminal 10 ^' . A positron adjustment of the two elements 2, 4 to each other is usually not necessary because the terminal 10 compensates for unevenness of the soil sufficiently. Now the solid fuel, such as wood chips, pellets or other suitable solid fuel, can be filled into the solid fuel storage 4, for example with a wheel loader. During operation of the furnace 2, the solid fuel is conveyed via the conveyor 12 and the connection 10 to the furnace 2.

In an alternative embodiment, the furnace 2 and the solid fuel in bearings 4 _^ are a contiguous Frame stored and transportable together. This solution is particularly advantageous for systems up to 500 kW, since the trans ^¬ port is facilitated and the connection of the two elements 2, 4 deleted each other.

After passing through a burn-back fuse 14, the solid fuel passes via another conveyor 16 designed as a stock auger into the combustion chamber 18 in the firing plant 2. There, the solid fuel is ignited and burns to ash over time. The resulting during combustion hot flue gases are fed to a first heat exchanger 20. There they are cooled from about 1200 ° C to below 1000 ° C. ' The thus cooled flue gases are then one _. second heat exchanger 22 is supplied and cooled there to about 150 ° C. Through the two heat exchangers 20, 22 is blown to cool the ambient air. This is heated in the heat exchangers 20, 22 and is now available for further use, for example for drying hay. The exhaust gases cooled in the heat exchangers 20, 22 are supplied to a spark separator 24, for example a cyclone separator. Larger installations can provide a plurality of cyclone separators which are operated in parallel. Deposited ash is collected in an ash container 26 and the purified waste gases are led up out of the furnace 2.

Fig. 2 shows the large heat exchanger 22 in a perspective view obliquely from above. For better explanation, the representation of the largest part of a housing 28 has been dispensed with, so that the view becomes free on the heat exchanging wall 30 between an inner gas guide 32 and an outer gas guide 34, which are indicated in FIG. 2 by thin or thick arrows. The heat exchanger 22 is a corrugated plate heat exchanger whose wall 30 is made of corrugated chen and is described in more detail below.

The heat exchanger 22 includes a flue gas inlet 36, which is designed in the embodiment shown as a distribution box for distributing the hot gas to many tubes. Into the flue gas inlet 36, the flue gases heated to between 900 degrees Celsius and 1000 ° C are sucked through connections 38 to the upstream small heat exchanger 20, as indicated by the first and downwardly pointing arrow of the Innengas- guide 32. The hot flue gases pass through a first train 40, reached from there a deflection chamber 42, where it is deflected upward again by 180 degrees, pres ^¬ fen the second train 44 and reach from there th a Sammelkas- 46. Then leave the cooled hot gases the

Heat exchanger 22 through a hot gas discharge 48, through which they are passed to the spark separator 24. Ashes accumulated in the deflection space 42 are fed to the ash tank 26 through an ash discharge 50.

While the inner gas guide 32 extend in a U-shape through the two slides 40, 44 of the heat exchanger 22, the outer gas guide 34 runs in an S-shape around the wall 30 of the two slides 40, 44, as shown in FIG. 3.

3 shows the two trains 40, 44 with the indicated housing 28 and the outer gas guide 34. During operation of the solid fuel combustion system 2, air is admitted through an ambient air inlet 54 with a fan 60. By a cooling gas connection 58, the ambient air is guided in an ambient air guide 62 to the heat exchanger 22, ie to the wall 30 of the second train 44. The housing 28, the wall 30 and two deflection means 64, 66 form the outer gas guide 34 and thus give the air flow of the Ambient air through the heat exchanger 22 before. The ambient air is passed as cooling air first around the wall 30 of the second train 44, then around the wall 30 of the first train 40, then around the wall 30 of the second train 44 and finally around the wall 30 of the first train 40 and leaves the heat exchanger 22 as warm air in a hot air duct 68. It passes through the first heat exchanger 20 in the hot air duct 68 and is blown out through the hot air outlet 72 of the firing system 2. The deflection means 64, 66 are designed in the form of intermediate plates, wherein each intermediate plate is guided around all plate pairs 76 of only one train 40, 44. The intermediate plates serve to guide the ambient air or the external gas in an S-arc through the heat exchanger 22.

Fig. 4 shows the wall 30 of the two trains 40, 44, which are designed in the form of many corrugated sheets 74. Two Plat a ^¬ tenpaar 76 forming corrugated sheets 74 are shown in Fig. 5 by way of example in perspective. Three such ^' plate pairs 76 of the first train 40 are shown schematically in Fig. 6 in a sectional view. At its head end, the corrugated sheets 74 are welded into a top plate 78, the wall 30 of the heat exchanger 22 after. closes up. The top plate 78 thus contains the outer contours of the plate pairs 76 of the two trains 40, 44 corresponding openings into which the plate pairs 76 are inserted. With one fillet weld each, the corrugated sheets 74 or plate pairs 76 are welded to the top plate 78. The corrugated sheet 74 of the plate pairs 76 is made. made of stainless steel, expediently a stainless steel, and has a wall thickness of 0.5 mm. For stable support of the plate pairs 76, the thickness of the top plate 78, which is made of structural steel, 5 mm. Also possible is stainless steel, which then thinner can be executed. Accordingly, the plate pairs 76 are welded to a foot plate 80 of the heat exchanger 22. The two deflecting means 64, 66, which are also manufactured as sheets, with the corresponding openings for passing through the plate pairs 76, can be welded in the same way, with a material-locking stapling of the deflecting plates 64,. 66 is already sufficient on the pairs of plates 76.

The plate pairs 76 consist of two corrugated sheets 74 which are welded together at their two longitudinal edges 82. The corrugated sheets 74 are deep-drawn stainless steel sheets, which are placed on top of each other and joined together to form a plurality of at least substantially longitudinal chambers in the form of tubes 84. The corrugation of the corrugated sheets 74 consists per wave phase essentially of two approximately 110 degree wide kreisbogenförmige.n segments 86, 88, which form an S-shaped wave phase. The cross-section of the longitudinal chambers or tubes 84 is substantially circular, delimited at the top and bottom by the two circular-shaped segments 86, and laterally deviating somewhat from the circular arc shape, wherein a circle with the radius of 20 mm can be placed in the cross section, the coincides with the two circular arc segments 86. The segments 88 touch each other in their central axis, which is parallel to the longitudinal axis of the tubes 84 and plate pairs 76. Due to the juxtaposition of the segments 88, the interior space of the tubes 84 is at least substantially separated from one another in regions of the parallel course. Opposite the segments 88 are convex inner surface portions which are joined together by welding. The outer segments 86 form concave inner surface portions that face each other in pairs and that form the major boundary of the tubes 84. The middle pair of plates 76 is outwardly represents ^¬ provided pairs of plates 76 between the two arranged so that convex outer surface portions of the segments 86 of the intermediate plate pair 76 of the two surrounding pairs of plates 76 come to lie between the concave outer surface portions of the segments 88th

From FIG. 6 it can be seen that the outer gas guide 34 is guided very precisely. This results in an advantage of a corrugated-plate heat exchanger 22 compared with a tube-bundle heat exchanger: The external gas or cooling gas has to travel a defined path along the wall 30, which can not be achieved with tube bundle heat exchangers, since the outside gas can flow around the tubes on both sides.

Because a gas-tightness. the tubes 84 against each other is not necessary, since the same hot flue gas flows through all the tubes 84, the contacting segments 88 need not ■ be continuous or not welded together. to

However, promoting the stability of the plate pairs 76, it is beneficial if the segments 88 are each partially welded along their central axis, wherein a welding between 10% and 50% of the total length of the central axis, advantageously distributed over many small welding distances, is conducive.

Per train 40, 44, the heat exchanger 22 is provided with a plurality of such, as shown in Fig. 5, pairs of plates 76 which are positioned vertically side by side. Depending on the size and design of the vertical heat exchanger 22, the corrugated sheets 74 and plate pairs 76 can be welded in any number at both ends of the tubes 84 in the top and bottom plates 78, 80. Between the plate pairs 76 is hereby by - as can be seen in Fig. 6 - the outer gas guide 34 is formed. The gas space 92 between the plate pairs 76 here is designed so that it assumes a waveform transverse to the longitudinal direction 90 of the tubes 84 and always has substantially the same thickness. The waveguide creates an intensive contact of the cooling gas with the wall 30, so that an intense heat transfer from the inner gas to the outer gas takes place. With regard to the thickness of the gas space 92 or the spacing of the plate pairs 76 from each other, care must be taken that the distance is not greater than half the radius of the tubes 84, otherwise the cooling air or the external gas need not extend the waves and the risk is that the cooling air forms air cushion in the bulges of the waves and the cooling air flows straight through between the plate pairs 76 without complete passage of the waves and comes only in limited contact with the plate pairs 76 and the wall 30.

The guidance of the gases can - depending on the application - be completely reversed, so that hot gas between the plate pairs 76 in the outer gas guide 34 and cooling gas in the tubes 84 is guided in the inner gas guide.

,

Through the S-shaped outer gas guide 34, this crosses the tubes 84 of the second train 44 and some of the tubes 84 of the first train 40, is then deflected by 180 degrees, so also runs a little way parallel to the tubes 84 of the first train 40 to then to intersect some tubes 84 of the first train 40 and some tubes 84 of the second train 44 will turn around

180 degrees deflected,. Thus, parallel to some of the tubes 84 of the second train 44, to then cross other tubes 84 of the second train 44 and all tubes 84 of the first train 40. By using corrugated sheet metal as the wall 30 between the outer gas guide 34 and the inner gas guide 32 can be dispensed with tubes of a tube bundle heat exchanger. This has the advantage of a much larger selection of materials, since sheets are available in much larger Matterialvariation than pipes. It is possible to resort to materials of higher quality than would be possible with pipes, for example a steel which is resistant to oxidation under high heat, a very heat-resistant steel or a metal with a preferred coefficient of thermal expansion. Accordingly, the wall thickness of the corrugated sheets 74 may be smaller than would be necessary for pipes, so that the heat exchanger 22 can be made easy to build and save weight. This is especially true in a mobile solid fuel burning plant 2 of. Advantage, since every weight saving facilitates transport.

The foot plate 80 is shown in a perspective view in FIG. 7 so that the openings 94 in the foot plate 80 are visible for connection to the plate pairs 76. The deflection means 64 is shown in a plan view in Fig. 8. Also there, the openings 94 are visible. The deflection means 66 is formed analogously to the deflection means 64, but the openings are shorter by one wave phase than the openings 94 of the deflection means 64.

The plate pairs 76 of the heat exchanger 22 are divided into two groups: the plate pairs 76 of the first train 40 and the plate pairs 76 of the second train 44. As can be seen from Figure 4, the plate pairs 76 of the first train 40 are those of the second train spaced by a region 96 without plates. This area. 96 serves to the flue gas introduction is simplified in the heat exchanger 22, since the introduction into the distribution box and the lead-out through the collection box 46 is spatially separated and one or two baffles are arranged in the region 46, which thus do not cut tube openings. The region 96 has a further advantage: Especially in obe ^¬ ren region of the two trains 40, 44 there is a considerable difference in temperature of the walls 30 of the two trains 40, 44. While the wall 30 of the first train 40 in the upper region at approximately 800 ° C is the temperature of the wall in the upper area of the second train 44 is only about 200 ° C. Therefore, a different temperature expansion, due to the thermal expansion of the corrugated sheet material, in the ^¬ trains 40, 44 instead. Due to the arrangement as separate plate pairs. 76 in the trains 40, 44 temperature tensions in the material of the corrugated sheets 74 can be kept low.

The arrangement of the outer gas guide 34 is such that it runs in a countercurrent flow to the inner gas guide 32. Namely, the outer gas guide 34 is arranged to first flow around the wall 30 of the cooler second train, and finally to the hottest area of the first train 40. In this way, efficient utilization of the heat of the flue gas is achieved. In the first heat exchanger 20, the warm air is reheated once more.

9 shows an alternative external gas guide 98. The air to be heated first flows into it over the entire length of the second train 44, is then deflected not laterally but laterally of the two trains 40, 44 by about 180 degrees, and then flows through the wall .30 of the first train 40. In this way, a countercurrent flow to the internal gas guide 32 is achieved. Such an outer gas guide 98 is particularly suitable for very high volume flows of air to be heated, since in each case the entire train 40, 44 can be used for Außengasumströmung in only one direction.

An alternative plate pair 100 of two corrugated sheets 74 is shown in FIG. The two corrugated sheets 74 are not connected in phase, as in the example of the plate pair 76 shown in FIG. 5, but are in phase and are therefore parallel to each other everywhere. It arises between corrugated sheets 74, a single longitudinal channel 102 which extends over the entire width of the corrugated sheets 74. Laterally, the two corrugated sheets 74 are welded again, so that the inner gas channel is closed on both sides and is only open at the front and rear, as shown in FIG. 11 can be seen. Fig. 11 shows the plate pair 100 in a perspective view obliquely from above.

It is also possible that the two corrugated sheets 74 are interconnected along their sides by means of two strip-shaped connector sheets. It is also possible to fold both corrugated sheets 74 toward one another or one of the corrugated sheets 74 toward the other, so that the connector sheets are omitted.

FIG. 12 shows an alternative longitudinal edge 104 to the longitudinal edge 82. At least one of the two corrugated sheets 74 · is bent along the longitudinal edge 104 around the other, so that a rounded flow edge is formed.

In order to produce this longitudinal edge 104, the two corrugated sheets 74 are on one longitudinal side with a wider, uncoated one

Provided sheet metal surface. The two identically shaped corrugated sheets 74 are placed on each other to produce a pair of plates 76 so that each of the corrugated sheets 64 the other ^' at one

Longitudinal side surmounted by the unwanted area. Then be the two corrugated sheets 74 welded to two parallel welds 106 which extend along the entire longitudinal edge 104. Subsequently, a part of the flat portion of the standing wave plate 74 is folded 180 degrees, as shown in FIG. 12. Subsequently, the resulting

Laminated core of three sheet metal layers with a third weld 108 completely welded, also along the entire longitudinal edge 104 and in particular directly on the sheet edge, so that the wave sheets 74 are closed at the edge welded together and, for. no pickling agent can run between the sheets 74.

This longitudinal edge 104 has two advantages. First, it forms a very secure composite of the corrugated sheets 74, which remains gas-tight even under extreme mechanical and thermal stress. The mechanical load is not only due to the _. Welded seams 106, 108 added, but also by supporting the corrugated sheets 74 to each other. A leakage of hot flue gases can be safely avoided. Second, the longitudinal edge 104 forms a rounded leading edge. If the outside gases flow very quickly into the heat exchanger 22, a sharp longitudinal edge 82 can lead to vibrations and thus to an undesirable noise. By the round longitudinal edge 10 ^' 4 a flutter and swing is avoided.

An alternative heat exchanger 110 is shown in FIG. It is the same except for the following details, as the heat exchanger 22: Especially at large firing capacities, a non-deflected outer gas guide 112 may be advantageous in order to be able to blow very large volumes of air per time through the heat exchanger 110. The deflection means 64, 66 can be omitted, so that the outer gas guide 112 is guided in a straight line through the heat exchanger 110, by all trains 40, 44th The heat exchangers 22, 110 are stationary heat exchangers, the inner gas duct 32 runs vertically through the ducts 40, 44. Also possible is the use of the pairs of corrugated iron sheets 76, 100 in a horizontal heat exchanger, in which the. Internal gas duct runs horizontally through the trains. Also oblique arrangements are conceivable.

The connection between the corrugated sheets 74 and the top plate 78 and / or the foot plate 80 is shown in FIG. The corrugated sheets 74 are brought with their upper or lower edge directly to the top plate 78 and foot plate 80 and welded to the ^¬ ser. In this way, the plate pairs 76 are very firmly connected. Instead of the top plate 78 or foot plate 80, another holding means may be used, wherein the top plate .78 or the foot plate 80 may also be referred to as holding means

An alternative connection between the holding means, eg head plate 78 or foot plate 80, and the corrugated sheets 74 is shown in FIG. The corrugated sheets 74 are passed through the holding means. _, After the implementation of the corrugated sheets 74 each have a collar 114 is arranged, which is formed in this embodiment of the respective corrugated sheets 74 by bending the outer portion of the corrugated sheet 74. Collar 114 and holding means lie flat one above the other and are firmly connected to each other, for example a weld, as shown in Fig. 15. In order to achieve a good gas tightness between collar 114 and retaining means, even if a weld should be faulty, a

Sealant between collar 114 and holding means are arranged, for example, a sealing layer. ^; In contrast to FIG. 15, FIG. 16 shows a rounded transition between collar 114 and the fuselage of the corresponding corrugated sheet 74. In this way, a hot gas flow can be low in turbulence and thus low in noise and with little pressure loss. be led. The width 116 of the rounded region in the collar direction is at least 10% of the greatest width 118 of a gas tube between the wave plates 74, in particular at least 20%. The rounding can be performed on all embodiments shown.

Another embodiment of attaching the collars 114 to the attachment means is shown in FIG. The collar 114 of two corrugated sheets 74, which form a plate pair 76, are designed to overlap. The overlap results in attachment, e.g. a screw or rivet, and connected to the retaining means, e.g. the top plate 78 or the foot plate 80. The overlap allows the use of a central attachment instead of two attachments side by side, as shown in Fig. 18. Between holding means and collar 114, a sealing paper 120 is placed in each case for sealing the hot gas duct against the cold gas guide or the environment. Between collar 114, sealing paper 120 and holding means 78 each air is drawn. This is only for better illustration. For attachment, the elements are directly adjacent to each other.

Fig. 18 shows narrower collars 114 which do not overlap one another. The collar 114 are clamped between the holding means and in each case a counter-element 122, as well as the

Sealant 120 between collar 114 and retaining means, so eg head plate 78 or base plate 80. The counter-element 122 is a arranged between the plate pairs 76 sheet metal, expediently in the strength of the holding means, for example 5 mm. It is in this embodiment snake-shaped, as shown in Fig. 19 can be seen.

For clamping, bolts 124 are secured to mating member 122, e.g. welded, suitably carry thread. Thus, the jamming can be achieved by a screw connection, e.g. can be achieved with a mother 128. Alternatively, riveting is possible, so that instead of the bolts 124 rivets are guided by the holding means and the counter-element 122.

The combination of plate pairs 76 with molded-on collar 114 of FIG. 18 and the counter-elements 122 is shown in Fig. 19 in a ^'plan looks. The retaining element and the sealing paper 120 are omitted in the illustration for the sake of clarity, so that the view falls directly on the collar 114 and the underlying counter-elements 122. The bolts 124 are inserted through holes in the collar. The counter-elements 122 respectively wind in a serpentine manner between adjacent plate pairs 76, except for the outer counter-elements, which only have an adjacent plate pair. 76 have.

In Fig. 20, the arrangement of Fig. 19 with the holding means, in this case the top plate 78, is shown. Through holes 126 in the top plate 78 can be seen from above into the tubes of the plate pairs 76. The bolts 124 are also inserted through the retaining means and bolted to the nuts 128, so that the collars 114 are clamped between the retaining means and the counter-element 122. 2 solid fuel firing system 4 solid fuel storage

6 means of transport

8 means of transport

'io connection

12 discharge unit

14 Backfire protection

16 subsidies

18 combustion chamber

20 heat exchangers

22 heat exchangers

24 spark arresters

26 ash containers

28 housing

^" 30 wall

32 internal gas duct

34 external gas guide

36 flue gas inlet

38 hot gas connection

40 train

42 deflection space

44 train

46 collection box

48 hot gas discharge

50 ash removal

54 ambient air intake

56 opening

58 cooling gas connection

60 blowers

62 Ambient air guidance

64 deflecting means

66 deflection 68 hot air duct

70 blowers

72 warm air outlet

74 corrugated iron

76 plate pair

78 top plate

80 foot plate

82 longitudinal edge 84 tube

86 segment

88 segment

90 longitudinal direction

92 gas space

94 opening

96 mixing range

98 external gas guide

100 plate pairs

102 inner gas chamber

104 longitudinal edge

106 weld

108 weld

110 heat exchanger

112 external gas guide

114 collar

116 width

118 width

120 sealing paper

122 counter element

124 bolts

126 holes

128 mother

Claims

protection claims

1. Heat exchanger (22) for a mobile Festbrennstofffeue- optimization unit (2) with a hot gas port (38) and a home ^{'nengasführung} (32), a cooling gas port (58) and an Au ßengasführung (34) and a the two gas ducts ( 32, 34) separating and heat conducting wall (30) for producing a heat transfer from the hot to the colder gas, ^■

characterized in that the wall (30) comprises a plurality of interconnected corrugated sheets (74), between which both gas passages (32, 34) extend.

2. Heat exchanger (22) according to claim 1,

characterized in that the corrugated sheets (74) are each connected in pairs in such a way that convex inner surface sections in pairs and concave Innenflä ^¬ chenabschnitte each pairwise opposite.

3. Heat exchanger (22) according to claim 2,

characterized in that the pairs of corrugated sheets (76) are connected to each other at the convex inner surface portions.

4. Heat exchanger (22) according to claim 2 or 3,

characterized in that concave inner surface portions each ^'in pairs form a tube (84).

5. Heat exchanger (22) according to claim 4,

characterized in that the tubes (84) are formed such that their interiors in the region of their parallel course, at least by the succession of the wave plates (74) are substantially separated from each other.

6. Heat exchanger (22) according to claim 4 or 5,

characterized in that the inner gas guide (32) as

Hot gas passage through the tubes (84) extends.

7. Heat exchanger (22) according to any one of claims 2 to 6, characterized in that in each case two pairs of plates (76) are arranged to each other such that they form between them a wave-shaped gas space (92) as part of the outer gas guide.

8. Heat exchanger (22) according to claim 7,

characterized in that between pairs of plates a plurality of tubes are formed and the gas space (92) perpendicular to the longitudinal direction of the tubes (84) can be flowed through.

9. The heat exchanger (22) according to any one of claims 2 to 8, characterized in that between two pairs of corrugated sheets (76) a third corrugated plate pair (76) is arranged such that convex outer surface portions of the third corrugated plate pair (76) between concave outer surface portions of the two surrounding corrugated iron pairs (76) come to rest.

10. Heat exchanger (22) according to one of the preceding claims,

characterized in that the corrugated sheets (74) form a plurality of parallel tubes (84), and the outer gas guide (34) at least some of the tubes (84) cross outside, is deflected in their direction and these tubes (84) a second time outside crosses.

11. Heat exchanger (22) according to one of the preceding claims,

characterized in that the corrugated sheets (74) form a plurality of parallel tubes (84) and the outer gas guide (34) 'with the aid of at least two baffles (64, 66) S-shaped through the corrugated sheets (74) is guided, so that they transversely and parallel to. the tubes (84) passes.

12. Heat exchanger (22) according to one of the preceding claims,

characterized in that the corrugated sheets (74) form a plurality of parallel inner tubes (84). which are divided into two groups each having a plurality of separate outer gas channels, between which is arranged a mixing portion (96) into which the outer gas channels open ,

13. Heat exchanger (22) according to claim 12,

characterized in that the inner gas guide (32) is guided one after the other through the two groups of inner tubes (84).

14. Heat exchanger (22) according to one of the preceding claims,

characterized in that the outer gas guide (34) extends in a counterflow to the inner gas guide (32).

15. Heat exchanger (22) according to one of the preceding claims,

characterized in that the corrugated sheets (74) are each formed at at least one end to a collar (114) arranged transversely to the orientation of the shafts, and the corrugated sheets (74) respectively to this collar (114) to a holding means for holding several corrugated sheets (74) are attached.

16. Heat exchanger (22) according to claim 15,

characterized in that the holding means is a sheet transverse orientation of the shafts, and the collar (114) are aligned flat parallel to the sheet.

17. Heat exchanger (22) according to claim 15 or 16,

characterized in that the collars (114) are clamped between the holding means and a counter element (122) arranged between the corrugated sheets (74).

18. Solid fuel combustion system with a combustion chamber, a heat exchanger (22) according to one of the preceding claims and a combustion chamber (18) with the hot gas connection (38) connecting the flue gas duct.

A solid fuel firing system (2) according to claim 18, characterized by an ambient air inlet (54), a hot air outlet (72), an ambient air duct (62) connecting the ambient air inlet (54) to the cooling gas manifold (58) of the

Heat exchanger (22) connects, and a hot air duct (68), the outer gas outlet of the heat exchanger (22) with the

Warm air outlet (72) connects.

20. Mobile hay drying plant with a transportable frame (6, 8) in which a solid fuel burning plant (2) according to claim 1.8 or 19, and in particular a solid fuel container (4) is arranged.