EP3156733B1 - Mobile solid fuel firing assembly and method of use - Google Patents

Description

The invention relates to a mobile solid fuel combustion system with a combustion chamber, a hot air plate heat exchanger with a sheet metal duct with two flat sides formed from sheet metal and a cooling air duct and a hot gas duct, the hot gas duct running lengthwise through the plate plate duct and the cooling air duct running in the width direction around the plate plate duct and the flat plate sides facing each other Height direction opposite, wherein a turbulator with a swirl element is arranged in the sheet metal channel in the hot gas guide, which is arranged between the flat metal sides.

A stationary solid fuel combustion system with a hot air plate heat exchanger is out of the US 4664180 known. To clean the flue gas flues, chains are attached to them that strike the heat exchanger plates, so that soot and fly ash are knocked down.

Firing systems with tubular heat exchangers are out of the GB 2087064 A and the FR 2294403 A known. Vortex elements are attached to the inside of the pipes carrying the flue gas for swirling or braking the flue gases.

A mobile solid fuel combustion system is, for example, from the EP 2541141 A2 known. It can be used to dry hay, to dry a building, to heat a tent or building, or for similar purposes. For this purpose, the solid fuel combustion system is driven to its place of use, parked there and put into operation. After the end of the intended operation, the solid fuel combustion system is returned to a warehouse or to a next operating location hazards. Solid fuel is burned in the combustion chamber for operation, the heat released being fed to a heat exchanger with the flue gas. To cool the heat exchanger, this can be flowed through by a cooling air flow which removes the heat from the heat exchanger and conducts it in an air flow into the building, the tent, a hay drying room or the like.

To operate the mobile solid fuel combustion system at changing locations, it is loaded onto a vehicle, driven to the location and unloaded there. The system is exposed to high mechanical loads.

It is an object of the present invention to provide a mobile solid fuel combustion system that is particularly light.

This object is achieved by a mobile solid fuel combustion system of the type mentioned at the outset, in which the swirl element is designed as a sheet metal strip and is mounted in the sheet-metal plate channel so as to be able to move in a pendulum manner.

A hot-air plate heat exchanger allows large volumes of cooling air to be passed through and along thin sheet metal walls, so that the hot-air plate heat exchanger can be made relatively small and light in relation to the cooling air volume.

The hot air plate heat exchanger is expediently a flue gas-air heat exchanger with a vertical or horizontal hot gas duct and a horizontal cooling air duct through the heat exchanger. The directions refer to a solid fuel combustion system that is parked on a flat, horizontal plane and is ready for operation.

The sheet metal duct channels the hot gas and shields the cooling air duct from the hot gas duct. It runs in the longitudinal direction, the direction of flow of the hot gas expediently running in the longitudinal direction through the sheet metal plate channel. The direction of flow of the cooling air around the sheet metal plate channel is at least in the area of the sheet metal flat sides in the width direction, that is, in the direction of the width of the sheet metal plate channel. The height direction is in the direction of the thickness of the sheet metal channel and runs perpendicular to the length direction and perpendicular to the width direction.

The firing system is a mobile firing system, which is therefore intended to be transported to its place of use by a vehicle, operated there and later operated again at another location. For this purpose, the firing system expediently comprises a supporting structure and a lifting element which is prepared for lifting the entire firing system on the lifting element with the aid of a lifting device. The lifting element can be a slot for a forklift, an upper attachment for a cable suspension of a crane or the like, so that the firing system can be raised and placed on a loading surface, for example. In particular, slots for standardized forks of a forklift are advantageous. The supporting structure expediently comprises a supporting frame with supports on which side walls are fastened in the manner of a housing. It is also possible for the supports to be formed by folds of wall plates forming the housing. In order to achieve easier movement of the furnace on site, it is advantageous if the furnace has its own driving unit with wheels. Four wheels are useful. For a safe stand during operation, wheels are only sufficient on one side of the system, e.g. two wheels, not connected to one rolling support unit, e.g. a wheelless support foot. The firing system can easily be moved manually with one or more hand movements, for example a holding bracket on the ambient air inlet side.

The solid fuel combustion system is expediently a combustion system prepared for the combustion of a biofuel, that is to say a non-fossil fuel. A wood firing system is particularly advantageous for operation with, for example, wood chips or pellets. Correspondingly, the solid fuel burner is made for burning solid matter, in particular wood, and comprises a fuel supply with an automatic feed unit for the automated supply of fuel into the combustion chamber, e.g. on the burning floor. A feed motor of the feed unit can be controlled by a control unit, in particular depending on a combustion parameter, such as the combustion temperature, the exhaust gas temperature and / or the warm air temperature.

The solid fuel combustion system comprises a hot gas duct in which the hot flue gas is guided from the combustion chamber through the hot side of the hot air plate heat exchanger to a gas outlet. Furthermore, the solid fuel combustion system is expediently a warm air system for heating ambient air and comprises an ambient air duct from an ambient air inlet in the housing of the furnace, through the cold side of the hot air plate heat exchanger to an ambient air outlet. The ambient air blower, which pushes the ambient air into and out of the housing of the firing system, is expediently arranged in the ambient air inlet - or at a distance of up to a blower radius from it. The ambient air duct expediently runs at least laterally around the combustion chamber in order to cool it as well. The ambient air inlet and the ambient air outlet are expediently arranged in opposite sides of a housing of the furnace.

A turbulator with a swirl element, which is arranged between the flat metal sides, is arranged in the hot gas duct in the sheet metal plate channel. This detail of the invention is connected with the consideration that a laminar hot gas flow can form in a plate heat exchanger with essentially parallel flat sheet sides, the internal flow of which comes into contact with the sheet metal of the two flat sheet sides only to a very limited extent. The laminar flow severely limits the heat transfer from the hot gas through the flat metal sides to the cooling air.

This heat transfer can be significantly increased if the laminarity is broken up and the hot gas is swirled. This can be achieved by the swirl element arranged in the sheet metal plate channel. The heat transfer can be improved and thus the size of the hot air plate heat exchanger can be reduced overall, so that further weight can be saved.

In order to keep the vortex element stable in a desired orientation in the hot gas flow, it is advantageous if it is held or suspended at at least two locations, in particular at exactly two locations. As a result, it can be oriented transversely to the hot gas flow with its at least predominant length, in particular over its entire length, and can be held stable there.

The vortex element expediently extends at least over more than half the width direction of the interior of a sheet metal plate channel. It is also advantageous if it extends over more than half the height direction of the interior of a sheet metal channel.

The swirl element is designed as a sheet metal strip or comprises a sheet metal strip. This is expediently arranged obliquely to the length direction and in particular also obliquely to the width direction. It can be parallel to the height direction. The helix angle is advantageously between 5 ° and 30 ° to the width direction and between 60 ° and 85 ° to the length direction. In general, you can use an element with a flat side that is oriented in the specified direction. The surface side can be flat. The hot gas flow hits the swirl element and is deflected by it at an angle to the length direction. In this way, an initial swirling can already be achieved in a simple manner.

A particularly good swirling of the hot gas within the sheet metal plate channel can be achieved if the swirl element is arranged at a distance from one of the two sheet metal flat sides and in particular from both sheet metal flat sides. There is therefore a gap between the swirl element and the flat metal side or sides through which the hot gas can flow between the flat metal side and the swirl element. This creates a hot gas jam on the vortex element, which is discharged in a vortex next to and behind the vortex element.

When carrying hot flue gas from a solid fuel combustion, large amounts of fly ash usually get into the heat exchanger. This settles in corners, edges and crevices, so that heat transfer from the hot side to the cold side is greatly reduced or even prevented. A setting of fly ash on the swirl element can be counteracted if the swirl element by one Longitudinal inner groove of the sheet metal plate channel, in particular spaced apart from the two longitudinal inner grooves of the sheet metal plate channel arranged opposite one another. The longitudinal inner groove can in this case be arranged on the inside of a leading edge or trailing edge of the sheet-metal plate channel to which the cooling air flows or from which the heated cooling air flows out again. The gap or air space between the swirl element and the longitudinal internal groove can prevent the fly ash from becoming stuck in this area and thereby causing a flow backlog and reduced heat transfer.

In a further advantageous embodiment of the invention, the turbulator has a plurality of swirl elements which are arranged one behind the other in the longitudinal direction. The swirling can be repeated several times in the course of the hot gas flow through the sheet metal plate channel, so that an effective swirling is achieved. The vortex elements are expediently offset from one another in the width direction, for example alternately offset from one another. In this way, the hot gas is forced to flow past the vortex elements on one side and on the other side, so that an S-shaped gas flow is achieved for at least part of the hot gas flow. In addition to swirling, this can also cause the hot gas to be circulated so that hot gas is pressed from the inner region of the sheet-metal plate channel to the outer region and thus to the flat metal sides.

It is also advantageous if the turbulator has a plurality of vortex elements which are arranged one behind the other in the longitudinal direction and tilted differently to the width direction. The tilting can be alternating, for example, so that the hot gas flowing in the longitudinal direction is deflected from the vortex elements in one direction and in the other direction. This also favors an S-shaped flow.

Very fine fly ash tends to stick to smooth surfaces along which the hot gas flow flows. In this way, heat transfer to these surfaces can be reduced. Cleaning such an area is therefore desirable. This can be achieved if the swirl element is movably supported in the sheet metal channel. The movement of the vortex element can strip or knock fly ash off a surface or inner edge and thus keep it clean.

Movable mounting of the swirl element can be achieved in a simple manner if the swirl element is mounted in the sheet-metal plate channel so as to be movable in the longitudinal direction and / or in the vertical direction, in particular in a pendulum manner. This is particularly useful in the case of a vertical longitudinal direction, that is to say a vertically oriented heat exchanger.

In a particularly simple form, several vortex elements with at least two metal rods can be held between the flat sides of the sheet metal plate channel. These can be arranged in the longitudinal direction and are in particular parallel to one another. With such a construction, mobility of the swirl elements can also be easily achieved, for example, in that the metal rods are suspended over an upper edge of at least one of the two flat sheet metal sides. For assembly or cleaning, the swirl elements on the metal rods can easily be pulled up out of the sheet metal channel.

As an alternative to the metal rods, the swirl elements can be suspended on at least two metallic ropes between the flat metal sides, e.g. Steel cables. Metallic ropes have the advantage that the turbulator is less easily trapped between the flat metal sides. Due to large temperature fluctuations between operating and idle times, metal bars can warp, so that the turbulator is clamped between the flat metal sides and is no longer movable. When hanging on ropes, the turbulator does not twist, so that the vertebral elements remain mobile.

A cleaning effect of the flat sheet metal sides by the swirl elements can be further improved if a drive for rhythmically moving an element of the sheet metal channel. One possibility is a drive for moving the turbulator, for example in the longitudinal direction. The vortex elements move along the sheet metal plates and clean them. The drive can be a motor drive, for example an eccentric drive, which raises and lowers the turbulator rhythmically. A drive for moving a sheet metal plate, for example for vibrating the sheet metal plate, is also possible. Fly ash can hereby be shaken off the sheet metal plate or its flat sheet side.

A simple assembly of the turbulator can be achieved if the vortex elements hang on one or more supports, e.g. a metal bar or rope attached to a crossbar. The crossbar can rest on an upper edge of the sheet metal channel, so that the turbulator is suspended from above in the sheet metal channel. The crossbar can engage positively in one or both sheet metal plates, e.g. into a recess or recess so that undesired slipping is counteracted.

An increase in the flow resistance in the hot gas duct or the cooling air flow can be compensated for by a stronger fan in the respective flow, so that a satisfactory gas flow is achieved. However, this is associated with increased energy consumption and also increased noise. However, since the cooling air flow flows through the plate heat exchanger with a considerably larger volume and faster, an increase in flow resistance there is particularly disadvantageous.

The flow resistance can be kept low if the sheet metal channel forms a leading edge for cooling air flowing in the width direction in the cooling air duct and the Sheet metal channel in the cooling air flow behind the leading edge widens in a wedge shape in the width direction, i.e. becomes thicker in the height direction. The cooling air flow is separated by the wedge and diverged. The wedge-shaped separation means that turbulence on the cooling air side and thus flow resistance can be kept low. It is also streamlined if the sheet-metal plate duct in the cooling air duct forms a leading edge for cooling air flowing in the width direction and widens on both sides in the cooling air flow behind the leading edge, so that the cooling air flow is guided on both sides, in particular symmetrically on both sides.

The hot gas emits heat due to the flow of the hot gas through the sheet metal plate channel, so that the hot gas cools and contracts. A uniform flow rate and thus a low flow resistance within the sheet metal plate channel can be achieved if the flow cross section of the hot gas duct in the sheet metal plate channel decreases in the longitudinal direction. The direction of flow of the hot gas expediently runs in the longitudinal direction. Since the flow rate of the hot gas through the sheet metal channel is greatest during full load operation of the mobile solid fuel combustion system, it is advantageous if the decrease in the flow cross section is equal to the decrease in the temperature of the hot gas flowing through the sheet metal channel during full load operation. The temperature is here to be understood in Kelvin.

A reduction in the flow cross section can be produced by narrowing the channel walls, which approach one another in the flow direction in the course of the channel. It is also advantageous if the flow cross section through a Plate plate channel arranged vortex element is reduced. The vortex element can be an element of the turbulator.

When the cooling air in the heat exchanger heats up, it expands. A uniform cooling air flow can be achieved if the cross section of the cooling air duct increases as the cooling air heats up. It is particularly advantageous here if the cooling air duct is guided between two sheet metal plate channels and has a flow cross section between these sheet metal plate channels which increases in the width direction, that is to say in the flow direction of the cooling air flow.

Both sheet metal flat sides of the sheet metal plate channel can each be formed by a sheet metal, which are connected to one another at a leading edge and / or a trailing edge, for example by welding. The manufacturing cost of the plate heat exchanger can be reduced if the sheet-metal plate channel has a sheet forming both sheet-metal flat sides with an edge, which in particular forms a leading edge or trailing edge of the sheet-metal plate channel in the cooling air duct for cooling air. There is no need to weld two sheets to one edge.

In order to avoid a build-up of fly ash on the inside in a very sharp bend, it is advantageous if the leading edge and its surroundings or the trailing edge and its surroundings have several at least substantially parallel folds, in particular three such folds. The edge directions of these folds are expediently the same, so that the edges are aligned parallel to one another.

Just as an intensification of the contact of the flue gas or hot gas from the inside with the sheet metal plates is desired is an intensification of the contact of the cooling air from the outside with the sheet metal plates is advantageous. This can be achieved by routing cooling air around the sheet metal duct to direct cooling air in an S shape around the sheet metal duct. The flow path of the air along the plates is increased and the air can also be swirled around the plates. The cooling air duct can have sheet metal elements between two sheet metal plate channels, which direct the air in an S shape.

In particular with such a cooling air duct, the sheet metal duct is exposed to strong mechanical loads. When connecting the two flat sheet metal sides or their sheet metal edges to one another, care must therefore be taken that this connection remains gas-tight even in the event of strong thermal expansions, so that no flue gas passes from the hot gas side of the heat exchanger into the cold gas side. Such a connection can be achieved completely along the connection by longitudinal welding. However, the production of gas-tight weld seams is complex.

This effort can be reduced if the two sheet metal flat sides lie against each other with their sheet metal edges and are folded into each other in such a way that a first sheet metal flat sheet is folded by 180 ° and the second sheet metal flat sheet by 180 ° around the first sheet metal flat sheet and again by 180 ° into the Groove is formed, which is formed by the fold of the first sheet metal flat side. With such a five-layer structure, the connection is so firm and gas-tight that spot welds are sufficient, as in FIG 6 can be seen that prevent movement of the two sheet edges in the longitudinal direction. There is no need for gas-tight longitudinal welding.

This connection is particularly useful in an S-shaped cooling air duct in which a sheet metal duct end is exposed to large temperature differences.

An even stronger connection can be achieved if the five-layer sheet metal structure is folded over again, so that a seven-layer sheet metal structure is created.

At the start or end of operation of the mobile solid fuel system, the plate heat exchanger heats up or cools down. This causes the flat sheet metal sides to expand or contract. Here, sheet metal surfaces move from a plane into a curved surface or from a curved surface into a plane or a surface with at least one straight line. This can lead to an undesired hitting or popping of the sheet in question.

Such undesirable noise generation can be avoided if at least one of the flat metal sides has a surface bend through the flat metal side. The surface bend expediently runs obliquely to the width direction and obliquely to the longitudinal direction. At least two bends in the sheet metal flat side are particularly advantageous, in particular at least two intersecting surface bends. The edge angle of such surface folds is expediently small and is below 10 °, in particular below 5 °.

In the presence of a cooling air duct, one or more elements of the cooling air duct can counteract beating by connecting them to a sheet metal plate in such a way that they stiffen them.

Furthermore, the invention is directed to a method for heating ambient air in a hot air plate heat exchanger of a mobile solid fuel combustion system, in which flue gas resulting from the combustion of solid in a combustion chamber of the mobile solid fuel combustion system is passed through a sheet metal plate duct which at least partially forms the hot side of the hot air plate heat exchanger. For better heat utilization, it is proposed that the flue gas flows around a vortex element of a turbulator and is swirled by it.

Mobile solid fuel combustion systems are driven on vehicles from a storage location to a location or from location to location. Here, they are moved and shaken on the vehicle, so that fly ash is partially shaken off on a sheet metal plate in the sheet metal plate channel. This effect can be intensified if, due to the travel movements, a swirl element strikes at least one sheet metal plate of the sheet metal plate channel and thereby flies down fly ash which has accumulated on the sheet metal plate during a previous operation. In this way, sufficient cleaning of the sheet metal duct can be achieved, so that manual cleaning between two operational uses can be avoided.

It is also advantageous if a swirl element is moved during operation by flue gas flowing past in such a way that the swirl element against at least one sheet metal plate of the sheet metal channel strikes and thereby flies down fly ash. A suspension of the swirl element on a metal cable is particularly expedient for this.

The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, become clearer and more clearly understandable in connection with the following description of the exemplary embodiments, which are explained in more detail in connection with the drawings.

FIG 1

eine mobile Festbrennstofffeuerungsanlage mit einer Brennkammer, einem Wärmetauscher und einer Rauchgasabführung in einer schematischen Darstellungsweise,

FIG 2

den Wärmetauscher in einer schematischen Schnittdarstellung von der Seite,

FIG 3

den Wärmetauscher in einer schematischen Schnittdarstellung von oben mit mehreren Blechplattenkanälen,

FIG 4

einen der Blechplattenkanäle in einer seitlichen Schnittdarstellung mit einem innenliegenden Turbulator,

FIG 5

den Blechplattenkanal aus FIG 4 von oben mit einer Draufsicht auf den Turbulator und

FIG 6

einen der Blechplattenkanäle in einer Seitenansicht mit einer Luftführung zum Führen der Kühlluft in einer S-förmigen Bahn.

Show it:

FIG. 1

a mobile solid fuel combustion system with a combustion chamber, a heat exchanger and a flue gas discharge in a schematic representation,

FIG 2

the heat exchanger in a schematic sectional view from the side,

FIG 3

the heat exchanger in a schematic sectional view from above with several sheet metal channels,

FIG 4

one of the sheet metal plate channels in a lateral sectional view with an internal turbulator,

FIG 5

the sheet metal channel FIG 4 from above with a top view of the turbulator and

FIG 6

one of the sheet metal channels in a side view with an air duct for guiding the cooling air in an S-shaped path.

FIG. 1 shows a schematic representation of a mobile solid fuel combustion system 2, which is prepared for a transport to several different locations. The furnace 2 comprises a combustion chamber 4 and a hot air plate heat exchanger 6, which are mounted in a frame 8 which has lifting elements 10 in the form of insertion openings at its lower end for inserting a fork of a forklift truck. Laterally and above, the transport frame 8 is formed by folding the lateral side plates or the system ceiling, which together with the floor form a transport-stable and weatherproof outer housing or system housing 12.

In order to ensure good mobility on site, the system 2 is equipped with a wheel system with four wheels 14, of which the two rear wheels 14 have a swivel mechanism 16 for rotating the wheels 14 about a vertical axis. For pushing or pulling the solid fuel combustion system 2, a handle 18 is provided above an ambient air blower 20, which preferably extends over the entire width of the rear wall of the outer housing 12.

FIG. 1 shows the solid fuel combustion system 2 in a highly simplified and schematic manner, in which operationally essential elements, which are however not essential for the explanation of the invention, have been omitted for the sake of clarity. In this exemplary embodiment, the mobile solid fuel combustion system 2 has a nominal output of 150 kW and can be fired with solid fuel 22, in particular wood, such as wood pellets. For this purpose, a fuel store (not shown) can be connected to the solid fuel combustion system 2 via a solid fuel channel, through which the solid fuel 22 arrives at a delivery unit 24, which is shown in FIG FIG. 1 is only indicated schematically. The conveyor unit 24 comprises a screw conveyor, through which the fuel 22 - controlled by an electrical control unit and driven by a motor - is automatically conveyed into the combustion chamber 4.

The hot flue gases resulting from the combustion of the solid fuel 22 are discharged upwards from the combustion chamber 4 and fed from above through a hot gas guide 26 to a hot side of the hot air plate heat exchanger 6. The hot gas is flue gas from the combustion and is passed through the hot side of the hot-air plate heat exchanger 6 from top to bottom and then arrives at a suction fan 28. The flue gas cooled in the heat exchanger 6 is discharged by the latter through a flue gas discharge 30 from the solid fuel combustion system 2 blown out. Within the hot gas guide 26 - and thus also within the hot gas guide 26 or hot side of the hot air plate heat exchanger 6 - there is therefore a negative pressure relative to the surroundings of the combustion system 2.

To remove the heat of combustion from the hot gas stream 32, a cooling air stream 34 is guided in a cooling air duct in a countercurrent duct to the hot gas stream 32 through the solid fuel firing system 2, i.e. it first hits cooler system parts and then hotter system parts, so that the air heated on the cooler system parts on the hotter system parts is reheated. The cooling air is extracted as outside air or ambient air by the ambient air blower 20 directly from the surroundings of the system 2 and blown into the outer housing 12 of the combustion system 2. The ambient air blower 20 is arranged at an ambient air inlet 36 of the outer housing 12. Within the outer housing 12 - and thus also within the cold side of the hot air plate heat exchanger 6 - there is therefore an overpressure relative to the surroundings of the combustion system 2.

The ambient air is blown from the ambient air inlet 36 in a cooling air duct to the cold side of the heat exchanger 6, passed through it in a cooling air duct and heated there. It then flows around the outer shell of the combustion chamber 4 and is further heated there before it leaves the combustion system 2 in the further course of the cooling air through a warm air outlet 38. The heated ambient air blown out of the warm air outlet 38 is available with a maximum nominal output of 150 kW, for example for drying buildings, heating a tent or for drying hay. The combustion chamber 4 is driven by the cooling air flow 34 cooled so that their outside temperature remains relatively cool and suitable for mobile use.

FIG 2 shows the hot air plate heat exchanger 6 in a schematic sectional view from the front along the section line II-II FIG. 1 and from FIG 3 , Six sheet metal plate channels 40 can be seen, the hot air plate heat exchanger having 6 further sheet metal plate channels 40, which are not shown in the figures for the sake of clarity. The line of sight in FIG 2 corresponds to the cooling air flow direction, the cooling air flowing between the sheet metal plate channels 40 in cooling air channels 42 through the heat exchanger 6. The hot gas stream 32 flows from top to bottom through the sheet metal plate channels 40, as shown by three dotted arrows in FIG FIG 2 you can see. The hot gas flows in the longitudinal direction L and the cooling air in the width direction B through the heat exchanger 6 (see FIG 3 ). A height direction H is perpendicular to the length direction L and the width direction B.

FIG 3 shows the hot air plate heat exchanger 6 in a schematic plan view from above along the section plane III-III FIG 2 , The sheet metal plate channels 40 can be seen, which are surrounded by the cooling air channels 42, so that the cooling air flow 34 flows around the sheet metal plate channels 40 from the outside. Each of the sheet metal plate channels 40 is formed by a sheet metal, which is folded over at the leading leading edge 44 at an angle <90 °, so that the sheet extends from the trailing trailing edge 46 to the leading trailing edge 44 and from there back to the trailing edge 46. The sheet metal plate thus forms both sheet metal flat sides 48 of its sheet metal plate channel 40 in one piece.

As in FIG 4 can be seen, the sheet is brought together at the rear trailing edge 46 and welded together, so that a gas-tight trailing edge 46 is formed. In this embodiment the sheet is placed on one side around the other side and welded with a weld seam, so that the three sheet thicknesses are connected to each other in a gas-tight manner. As can be seen from the fine-dotted lines, this weld seam is supplemented by two further weld seams along the sheet ends, so that the gas-tightness of the sheet forming the sheet-metal channel 40 is guaranteed even under high mechanical loads. The weld seams are, for example, roll seams, that is to say the weld is a roll seam weld, other continuous welds also being possible and advantageous.

FIG 5 shows an alternative connection of the two sheet edges of the sheet. Both edges are placed on top of each other with an offset so that a sheet edge lies further in and a sheet edge protrudes further out. Then the sheet edge protruding further outwards is folded 180 ° around the other edge, so that a connection is created, as in FIG 3 is shown. Then both sheet edges are folded over by 180 ° in the same direction of rotation, so that five sheet layers are now on top of each other, as in FIG 5 is shown. These are pressed against each other by pressure so that they lie close together. This is in FIG 5 Not shown. There, the sheet metal edges or sheet metal sections on the sheet metal edges are drawn slightly apart from one another in order to make the multilayer structure visible. In addition, a spot weld with several welding spots can be placed in the throat of the laminated core facing the sheet metal plate channel 40.

Long-term trials have shown that this connection is so strong that there is no need for continuous, gas-tight welding. It has been shown that when the solid fuel combustion system is heated and cooled, such strong thermal movements in the sheet metal plates on its Sheet metal edges lying on top of each other arise that a connection with a three-layer structure, as in FIG 3 shown, in the course of many operating cycles due to the thermal movements diverge and lose their gas tightness, so that continuous welding is useful. This is over with the five-layer structure FIG 5 not the case. Although thermal movements also take place there, in particular in the width direction B, the two sheet metal edges or sheet metal plate sections on the sheet metal edges remain firmly connected to one another due to the mutual interlocking, so that sufficient gas tightness is maintained even after a long service life.

FIG 2 shows the fastening of the sheet metal plate channels 40 to a top plate 50 and a base plate 52 of the hot air plate heat exchanger 6. The base plate 52 is also in FIG FIG 3 can be seen and surrounds the sheet metal plate channels 40 completely, so that they are held in the base plate 52 as in a frame. This is in FIG 2 only shown in simplified and schematic form, since only the webs of the top plate 50 and the base plate 52 between the sheet metal plate channels 40 are shown and the further representation of the two plates 50, 52 has been omitted for the sake of clarity.

The sheet metal of the sheet metal plate channels 40 is guided to the outside at both ends of the sheet metal flat sides 48 in a type of collar which bears against the head plate 50 or the foot plate 52 and is welded to the corresponding plate 50, 52. Here, the base plate 52 lies on the lower collars of the sheet-metal plate channels 40, so that it does not come into contact with condensate from the sheet-metal plate channels 40 that occurs downward. The top plate 50 can also be placed around the sheet metal plate channels 40, analogously to the base plate 52, wherein in FIG 2 the head plate 50 placed on the collars of the sheet metal plate channels 40 and is welded to them, so that a slightly different geometry than that of the foot plate 52 is shown.

During the operation of the solid fuel combustion system 2, hot flue gas flows through the heat exchanger 6 and specifically through the sheet metal plate channels 40, in this example from top to bottom. It is also possible to see the plate heat exchanger 6 rotated through 90 ° so that the hot gas flows horizontally through the heat exchanger 6. In any case, it is advantageous if the cooling air flow 34 is guided horizontally or at least essentially horizontally through the heat exchanger 6. In this way, the horizontal flow of cooling air or ambient air through the solid fuel combustion system 2 can largely be maintained without large deflections, so that the flow can take place with a low flow resistance.

During the flow through the sheet-metal plate channels 40, the hot gas cools down and contracts due to the temperature reduction essentially in proportion to the temperature reduction — measured in Kelvin. With a uniform flow cross section of the sheet metal plate channels 40, the flow velocity within the sheet metal plate channels 40 would be reduced in accordance with the temperature or volume reduction. In order to reduce this braking of the hot gas flow 32, which increases the flow resistance, the flow cross section of the hot gas guide 26 in the sheet metal plate channel 40 is continuously reduced, as shown in FIG FIG 2 you can see. The reduction here corresponds to the decrease in temperature of the hot gas through the sheet metal channel 40 during full load operation of the solid fuel combustion system 2. The hot gas thereby flows essentially at a continuous speed through the heat exchanger 6 or through the corresponding sheet metal channel 40.

With the same reasoning, the flow cross section of the cooling air duct between the sheet-metal plate channels 40 increases in the flow direction of the cooling air flow 34. This is in FIG 3 indicated by the cooling air channel 42 which widens continuously in the width direction between the sheet metal flat sides 48 of adjacent sheet metal plate channels 40. This increase in the flow cross section also corresponds to the temperature increase of the cooling air during its flow along the sheet metal flat sides 48 of the two sheet metal plate channels 40, likewise measured in Kelvin.

In order to keep the flow resistance of the cooling air flow 34 around the sheet metal plate channels 40 low, the sheet metal of the sheet metal plate channels 40 widens in a wedge shape from the leading edge 44 in the width direction or flow direction of the cooling air flow 34, as shown FIG 3 you can see. The sheet forming a sheet metal plate channel 40 thus comprises the front edge of the leading edge 44 symmetrically around the two leading edges 44 around the leading edge 44, each of which is designed with an angle> 90 °. This creates the wedge shape of the front section of the sheet-metal plate channel 40, against which the cooling air flow 34 flows.

The rear part of each sheet metal channel 40, at which the cooling air flow 34 leaves the sheet metal channel 40 at the trailing edge 46, is constructed in an analogous manner and comprises two parallel folds which bring the sheet in a wedge shape together at the trailing edge 46 or a little beforehand to enable this of the parallel sheet metal sections for welding. This also reduces the flow resistance of the cooling air flow 34 when it flows out of the sheet metal plate channels 40.

In contrast to the cooling air flow 34, which is guided at a relatively high speed by the powerful ambient air blower 20 through the heat exchanger 6, the hot flue gas flows much more slowly in the hot gas flow 32 through the hot gas guide 26, which is formed within the heat exchanger 6 through the sheet metal plate channels 40. The risk of a very laminar flow of the hot gas within the sheet metal plate channels 40 is therefore much higher than with the faster cooling air flow 34 around the sheet metal plate channels 40. However, the more laminar the flow, the lower the heat transfer from the hot gas to the cooling air.

In order to break up the laminarity of the hot gas flow 32 in the interior of the sheet metal plate channels 40, a turbulator 54 is arranged in each case in the interior of the sheet metal plate channels 40. A turbulator comprises several, here four, vortex elements 56, which are each fastened to two carriers 58. Carrier 58 may be a metal bar or rope, such as a steel rope. The two supports 58 are each fastened to a cross bracket 59 which is suspended over the upper edge of the sheet forming the sheet metal channel 40, as in FIG FIG 5 can be seen in the top view from above. In FIG 4 it can be seen that a crossbar 59 is positively attached to a recess in the sheet metal, so that slipping in the width direction B is avoided.

FIG 5 shows a metal plate channel 40 from above in a plan view, the upper and lower collars for fastening the metal plate channel to the head plate 50 and foot plate 52 being omitted for the sake of clarity. It can be seen that the carrier 58 has at its upper end a crossbar 59 which is hung on both sides over the upper edge of the sheet metal forming the sheet metal plate channel 40. In this way, the two carriers 58 together are four Points stored so that the turbulator 54 is stably supported within the sheet metal channel 40. The turbulator 54 can be inserted in a simple manner from above into the interior of the sheet-metal plate channel 40 and can thus be suspended there.

The hot gas flow 32 is forced past the vortex elements 56 by the four vortex elements 56. How from FIG 4 can be seen, the vortex elements 56 are arranged obliquely or inclined relative to the width direction B and to the length direction L. Relative to the height direction H, i.e. perpendicular to the paper plane FIG 4 , The vortex elements can be tilted, ie parallel to each other and aligned with the height direction H. The hot gas flow 32 is deflected in three ways by the vortex elements 56. The slope of the hot gas flow from the length direction L is partially deflected in or against the width direction B. How from FIG 4 can be seen, the vortex elements 56 are arranged one behind the other in the longitudinal direction L and are arranged tilted alternately to the width direction. In this way, the hot gas flow 32 is first deflected against the width direction B, then a bit in the width direction B, then through the third swirl element 56 again against the width direction B and finally again a bit in the width direction B. This results in a slight meandering Flow guidance of the hot gas stream 32. This is also achieved in that the vortex elements 56 are arranged alternately offset from one another in the width direction. Thus, every second vortex element 56 is arranged closer to the trailing edge 46 and alternately, every second vortex element 56 is arranged closer to the leading edge 44.

A second deflection takes place due to the spacing of the swirl elements 56 in the height direction H to the right and left of the sheet metal flat side 48 FIG 5 through the gap 60 between the respective sheet metal flat side 48 and the swirl elements 56. You can see the top vortex element 56 and the vortex element 56 underneath, which is shown in dashed lines both at the front and at the back for the sake of clarity, although it would be fully visible from the top towards the front, ie towards the leading edge 44. The hot gas flow 32 is guided past the swirl element 56 on both sides through this gap 60 and is thus swirled significantly, so that a good heat transfer from the hot gas to the flat sheet side 48 or its sheet and thus to the cooling air flow 34 is transmitted.

A third deflection of the hot gas flow 32 takes place at the front and rear of the vortex elements 56. There is a distance between this and the front and rear ends of the sheet metal plate channel 40, that is to say the inner throat of the leading edge 44 and the inner throat of the trailing edge 46 within the sheet metal plate channel 40, and thus a cross section capable of flowing through the hot gas. The hot gas is also forced through this so that an ash deposit in the two throats is counteracted. The hot gas is also swirled particularly well there.

Due to the distance of the turbulator 54 or its vortex elements 56 on both sides in the corresponding direction, i.e. on both sides in the height direction H through the gap 60 and on both sides in the width direction B due to the distance to the respective throat, the vortex elements 56 are movably mounted in the sheet metal plate channel 40. A force is exerted on the vortex elements 56 by the hot gas flow 32, by means of which they can easily swing on the supports 58. This also counteracts ash deposits on the inner walls of the sheet-metal plate channel 40. This swinging is promoted when the carriers 58 are designed as ropes.

Transporting the solid fuel combustion system 2 on or in a vehicle has a particularly effective cleaning effect. As a result of the accelerations and jerky movements when driving, the vortex elements 56 are moved back and forth and strike the inner walls of the sheet-metal plate channel 40, so that fly ash attached to the inner walls is thereby knocked off. In this respect, it is advantageous if the solid fuel combustion system 2 is moved to a different location by a vehicle after a large number of operating hours, for example more than 200 operating hours.

Cleaning can also be carried out by moving the vortex elements 56 past the inner walls of the sheet-metal plate channel 40 by lifting the turbulator 54, so that fly ash attached to them is scraped off. This can be done either by hand during maintenance or by a mechanical, automatic unit.

Such a unit in the form of a drive 62 is shown in FIG FIG 6 shown. FIG 6 shows the sheet metal plate channel 40 from the outside and does not represent the swirl elements 56. The drive 62 can comprise a motor with an eccentric drive, which rhythmically moves a connecting element 64, which firmly connects the two carriers 58 to one another. The movement can be a lift, as in FIG 6 is represented by the two arrows, the lowering can take place at the same speed as the lifting or by falling.

For this purpose, all turbulators 54 of all existing sheet metal plate channels 40 are expediently mechanically connected to one another so that they can be lifted together on a composite element. The composite element can be an extension of the connecting element 64 in the height direction. This can all sheet metal plate channels 40 are regularly automated or manually cleaned in a simple manner.

When the two sheet metal flat sides 48 heat up or cool down, their sheet metal expands or contracts. This can result in the sheet metal beating and, as a result, loud and undesirable noise. In order to counteract this noise development, the two sheet metal flat sides 48 are provided with a surface bend 66, in the exemplary embodiment from FIG 4 even two surface bends 66 are shown which cross each other. The two surface edges 66 have an edge angle of less than 5 ° degrees and each edge of the two sheet metal flat sides extends outwards to a certain extent, so that the gap 60 in the area of the edge crossing is somewhat larger than, for example, at the top and bottom of the sheet metal flat sides 48 a pulling of the sheet metal takes place through these surface folds 66 into the surface folds 66, so that the sheet metal surface does not hit when it cools or contracts.

FIG 6 shows a cooling air guide 68 outside the sheet metal channel 40, which directs cooling air 70 in an S-shape around the sheet metal channel 40. The cooling air guide 68 has two sheet metal elements 72, which are arranged in the width direction between two sheet metal plate channels 40 and in this respect limit the cooling air channel 42. They are supplemented by two outer sheets 74 which delimit the cooling air duct 42 in the width direction. The sheet metal elements 72 can be connected to the sheets of the sheet metal plate channel 40 in such a way that they serve as stiffening and the sheet metal strikes when the temperature changes, in particular in connection with an in FIG 4 prevent the bend shown.

LIST OF REFERENCE NUMBERS

2

Festbrennstofffeuerungsanlage

4

combustion chamber

6

Hot air plate heat exchangers

8th

frame

10

lifter

12

conditioning housing

14

wheel

16

swivel mechanism

18

Handle

20

Ambient air blower

22

solid fuel

24

delivery unit

26

Hot gas management

28

induced draft fan

30

Flue gas extraction

32

Hot gas stream

34

Cooling air flow

36

Ambient air intake

38

Hot air outlet

40

Tin plate channel

42

Cooling air duct

44

leading edge

46

trailing edge

48

Sheet flat side

50

headstock

52

footplate

54

turbulator

56

vertebral element

58

carrier

59

locking latch

60

gap

62

drive

64

connecting element

66

Flächenkantung

68

Cooling air flow

70

cooling air

72

sheet metal element

74

outer panel

B

width direction

H

height direction

L

length direction

Claims (12)

1. Mobile solid fuel combustion installation (2) with a combustion chamber (4), a hot air plate-type heat exchanger (6) with a sheet metal plate channel (40) with two flat sides (48) formed of sheet metal and a cooling air guide and a hot gas guide (26), wherein the hot gas guide (26) runs in the longitudinal direction (L) through the sheet metal plate channel (40) and the cooling air guide in the width direction (B) around the sheet metal plate channel (40), characterized in that the sheet metal flat sides (48) are opposed to each other in the height direction (H), wherein a turbulator (54) with a swirling member (56) that is placed between the sheet metal flat sides (48) is placed in the sheet metal plate channel (40) in the hot gas guide (26) and that the swirling member (56) is designed as a sheet metal strip and is mounted oscillatingly movable in the height direction (H) in the sheet metal plate channel (40).
2. Mobile solid fuel combustion installation (2) according to claim 1, characterized in that the swirling member (56) comprises a sheet metal strip that is placed obliquely to the longitudinal direction (L) and obliquely to the width direction (B).
3. Mobile solid fuel combustion installation (2) according to claim 1 or 2, characterized in that the swirling member (56) is placed spaced from both sheet metal flat sides (48) and from both longitudinal internal grooves of the sheet metal plate channel (40).
4. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized in that the turbulator (54) has several swirling members (56) that are placed the one behind the other in the longitudinal direction (L) and respectively alternately offset to each other in the width direction (B).
5. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized in that the turbulator (54) has several swirling members (56) that are placed the one behind the other in the longitudinal direction (L) and respectively alternately tilted to each other in the width direction (B).
6. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized in that the swirling member (56) is movably mounted in the sheet metal plate channel (40).
7. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized in that the turbulator (54) has several swirling members (56) that are hung to at least two metallic cables between the sheet metal flat sides (48).
8. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized by a drive (62) for the rhythmic movement of an element of the sheet metal plate channel (40) or of the turbulator (54).
9. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized in that the turbulator (54) has several swirling members (56) that are hung to a support (58) that is fixed to a transverse bow (59) that bears on an upper edge of the sheet metal plate channel (40).
10. Mobile solid fuel combustion installation (2) according to one of the preceding claims, characterized by a cooling air guide (68) around the sheet metal plate channel (40) for directing cooling air (70) in an S-shape around the sheet metal plate channel (40), wherein both sheet metal flat sides (48) respectively bear against one another with their sheet metal edge and are thus interfolded, that a first sheet metal flat side (48) is folded by 180° and the second sheet metal flat side (48) is folded by 180° around the first sheet metal flat side (48) and once more by 180° into the groove that is formed by the fold of the first sheet metal flat side (48).
11. Method for heating ambient air in a hot air plate-type heat exchanger (6) of a mobile solid fuel combustion installation (2) according to claim 1 for which flue gas arising from the combustion of solid fuel in a combustion chamber (4) of the mobile solid fuel combustion installation (2) is guided through a sheet metal plate channel (40) at least partially forming the hot side of the hot air plate-type heat exchanger (6), flows around a swirling member (56) of a turbulator (54) and is swirled by this member.
12. Method according to claim 11, characterized in that the mobile solid fuel combustion installation (2) is transported on a vehicle and a swirling member (56) hits against at least one sheet metal plate of the sheet metal plate channel (40) due to the movements during driving and fly ash that has accumulated on the sheet metal plate during a previous operation is struck down by this plate.

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