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CA2777496A1 - A preheater for combustion air, and a power plant - Google Patents

A preheater for combustion air, and a power plant Download PDF

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Publication number
CA2777496A1
CA2777496A1 CA2777496A CA2777496A CA2777496A1 CA 2777496 A1 CA2777496 A1 CA 2777496A1 CA 2777496 A CA2777496 A CA 2777496A CA 2777496 A CA2777496 A CA 2777496A CA 2777496 A1 CA2777496 A1 CA 2777496A1
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CA
Canada
Prior art keywords
heat exchanger
air
flue gas
gas duct
supply area
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA2777496A
Other languages
French (fr)
Inventor
Timo Mero
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Valmet Power Oy
Original Assignee
Metso Power Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Metso Power Oy filed Critical Metso Power Oy
Publication of CA2777496A1 publication Critical patent/CA2777496A1/en
Abandoned legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23LSUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L15/00Heating of air supplied for combustion
    • F23L15/04Arrangements of recuperators
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D1/00Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
    • F28D1/02Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
    • F28D1/0246Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid heat-exchange elements having several adjacent conduits forming a whole, e.g. blocks
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D1/00Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators
    • F28D1/02Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid
    • F28D1/04Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits
    • F28D1/047Heat-exchange apparatus having stationary conduit assemblies for one heat-exchange medium only, the media being in contact with different sides of the conduit wall, in which the other heat-exchange medium is a large body of fluid, e.g. domestic or motor car radiators with heat-exchange conduits immersed in the body of fluid with tubular conduits the conduits being bent, e.g. in a serpentine or zig-zag
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/34Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Air Supply (AREA)
  • Chimneys And Flues (AREA)

Abstract

A preheating device (1 ) for combustion air in a boiler, the device comprising first heat exchanger structures fitted in a flue gas duct (2), for heating primary air (P), a first air supply area (5) in the wall of the flue gas duct (2), for supplying air to be heated to the first heat exchanger structures, second heat exchanger structures fitted in a flue gas duct (2), for heating secondary air (S), as well as a second air supply area (6) in the wall of the flue gas duct (2), for supplying air to be heated to the second heat exchanger structures. The first air supply area (5) is opposite the second air supply area (6). The invention also relates to a power plant.

Description

A PREHEATER FOR COMBUSTION AIR, AND A POWER PLANT

Field of the invention The invention relates to a device for preheating combustion air by flue gas in the boiler of a power plant. Furthermore, the invention relates to a power plant comprising a device for preheating combustion air to be supplied into a boiler by means of flue gas.

Background of the invention For preheating combustion air for a solid fuel boiler, flue gas air preheaters (LUVOs) are typically used, in which the heating medium, i.e. flue gas, flows outside heat exchanger pipes, and the medium to be heated, i.e. air, flows inside the heat exchanger pipes. The heat exchanger pipes are placed hori-zontally in the flue gas duct, and the heat exchanger units on different levels are connected to each other by air ducts outside the flue gas duct. There are also configurations, in which the flue gas flows inside the pipes and the pipes are vertical.
A typical combustion air preheating device 1 is shown in Fig. 1. This kind of a preheating device 1 comprises horizontal heat exchanger structures 3 placed in a flue gas duct 2 for heating primary air P, and heat exchanger structures for heating secondary air S. Separate air supply areas 5, 6 for both air circu-lations are provided on the wall of the flue gas duct 2, for supplying air to be heated into the heat exchanger structures 3, 4. In this configuration, the cou-pling of air ducts is made as advantageous as possible for the layout of the plant. Primary air P and secondary air S are supplied into the preheater 1 from the same side. This configuration causes a strong distortion in the tem-perature of the flue gases F, because all the cold air is supplied into the pre-heater 1 from one side, causing significantly stronger cooling of the flue gases on the air inlet side than on the opposite side. The strong cooling of the flue gases F on the air inlet side, in turn, causes a relatively low material temperature at the air inlet end of the pipe of the heat exchanger structure 3, 4 of the preheater 1, in spite of the relatively high average temperature of the flue gases. Thus, the dew point of flue gases is easily achieved at the surface of the heat exchanger structure 3, 4. The dew point, in turn, will cause strong corrosion in the cold heat exchanger structure 3, 4 and erosion in a short time, particularly with difficult fuels.

Brief summary of the invention Now, a solution has been found which enables a more uniform temperature distribution in the terminal part of the flue gas duct.

To achieve this aim, the combustion air preheating device according to the invention is primarily characterized in what will be presented in the independ-ent claim 1. The power plant according to the invention is, in turn, primarily characterized in what will be presented in the independent claim 8. The other, dependent claims will present some preferred embodiments of the invention.

The basic idea of the invention is to form a preheating device for the com-bustion air of the boiler by providing the flue gas duct with first heat exchanger structures for heating primary air and second heat exchanger structures for heating secondary air. The inlet of the first heat exchanger structure and the inlet of the second heat exchanger structure are placed substantially on the same level, the level being substantially perpendicular to the central line of the flue gas duct.

In an embodiment, the first heat exchanger structures and the second heat exchanger structures are staggered.

In an embodiment, the first heat exchanger structures and the second heat exchanger structures extend at their air supply areas to the central area of the flue gas duct provided with air flow deflecting structures for changing the direction of air flows of the heat exchangers. The deflecting structure may be, for example, a chamber or a bent pipe.

In an embodiment, the first heat exchanger structures and the second heat exchanger structures are formed of pipes by bending so that the straight portions of the pipes extend both parallel to the central line of the flue gas duct and perpendicular to the central line of the flue gas duct.

A power plant according to the basic idea of the invention comprises at least a boiler and a flue gas duct, into which the flue gases exiting the boiler are led. Furthermore, the plant comprises the above-described preheating device for heating the combustion air to be supplied into the boiler. In an advanta-geous embodiment, the flue gas duct is vertical, and the flue gases from the boiler are introduced from the upper part of the flue gas duct and discharged from the lower part.

In an embodiment, the first air supply area and the second air supply area are placed substantially at the same height.

In an embodiment, the first air supply area and the second air supply area are the lowermost parts of the preheater which are placed in the flue gas duct.

The different embodiments of the above-described configuration, taken sepa-rately and in various combinations, provide various advantages. A single embodiment may comprise one or more of the following advantages depending on its implementation:
- the distortion of the flue gases can be levelled out;
- the temperature difference between the flue gases and the combustion air can be made as great as possible even in the lowermost pipe rows, in both the front and rear parts of the preheating device;
- the material temperature of the pipe of the preheating device can be raised at the location of the air inlet flow;
- the duct arrangements of the plant are simpler than in conventional configurations;
- in the area of the bent pipe element, problems of vibration of the pre-heating device are possibly reduced, because in one embodiment, the pipes are tied together in the vertical portion;
- in one embodiment, the problems of vibration of the preheating device are reduced, because the bundle comprises a primary air pipe and a secondary air pipe adjacent to each other; vibrations possibly caused by blowers on the primary and secondary air side have different fre-quencies, wherein they do not amplify each other.

One advantageous embodiment has the advantage that the cold bundles of both primary air and secondary air are placed as a single lowermost bundle.
Thus, when replacing a damaged bundle is necessary, only a single bundle has to be replaced. Normally, when e.g. a corrosion problem occurs, it is usually necessary to replace both the lowermost primary and secondary air bundles according to a given schedule. It is particularly difficult to replace the lowermost bundle but one.

In an application according to one embodiment of the invention, an air deflecting chamber in the centre of the primary and secondary air bundles increases advantageously the flow rate of the flue gases at the end part of the flow gas duct, improving the heat transfer on the flue gas side. This con-tributes to raising the material temperature of the pipes of the preheating device in the most critical cold part and thereby reduces the risk of erosion of the pipes by the effect of the acid dew point.

In an advantageous embodiment, the heat transfer surface of the preheating device consists, in its entirety, of a pipe element extending from the bottom to the top. The elements are made, for example, on a bending line for super-heater pipes. Of the adjacent elements, one is for primary air and the other for secondary air. The sizes of the pipes may be equal or different, depend-ing on the reciprocal proportions of primary and secondary air. The pipe spacing may be, for example, typical 75 x 75 mm, or the spacing can be selected to provide a desired flue gas rate. In addition to the advantages pre-sented above, the structure provides, among other things, the following advantages to conventional configurations:
- the connecting channels between bundles on the air side are totally eliminated, providing significant cost savings in the manufacture of ducts;
- the elimination of the connecting channels saves space in the boiler room;
- the installation of the preheating device becomes faster, because there is no need to install connecting air channels;

- the preheater device is divided into installation units in the width direc-tion of the preheater device;
- the pressure loss on the air side is smaller than in a conventional pre-heater device, because the inflows and outflows of pipes between 5 bundles are eliminated;
- the single resistance coefficient on the 900 curve is lower than in inflow or outflow of the pipe. This saves the internal consumption of the boiler.

Description of the drawings In the following, the invention will be described in more detail with reference to the appended principle drawings, in which Fig. 1 shows a combustion air preheater of prior art in a principle view;
Fig. 2 shows a power plant in a princple view;

Fig. 3 shows a first embodiment of a preheater;
Fig. 4 shows a second embodiment of a preheater;
Fig. 5 shows a third embodiment of a preheater;
Fig. 6 shows a fourth embodiment of a preheater;

Fig. 7 shows a detail of the preheater of Fig. 8;
Fig. 8 shows a fifth embodiment of a preheater;
Fig. 9 shows a cross-section along line A-A in Fig. 8;
Fig. 10 shows a detail of the preheater of Fig. 9;

Fig. 11 shows a detail of the preheater of Fig. 12;
Fig. 12 shows a sixth embodiment of a preheater;

Fig. 13 shows a cross-section along line B-B in Fig. 12;
Fig. 14 shows a seventh embodiment of a preheater;
Fig. 15 shows an application of a preheater.

For the sake of clarity, the drawings only show the details necessary for understanding the invention. The structures and details that are not neces-sary for understanding the invention but are obvious for anyone skilled in the art have been omitted from the figures in order to emphasize the characteris-tics of the invention.

Detailed description of the invention Figure 2 shows, in a principle view, a power plant with a combustion air pre-heater 1 in a flue gas duct 2. In the example, the power plant comprises a circulating fluidized bed boiler 7, but the boiler may also be of another type.
As it can be seen in the figure, the flue gas duct 2 is between the boiler 7 and the stack 8. Furthermore, the flue gas duct may comprise superheaters and filters which are not shown in the figure.

In the example of Fig. 2, the lower part of the preheater 1 comprises air inlet areas 5, 6, through which the primary air P and secondary air S to be heated are supplied to the heat exchanger structures, that is, the heat transfer sur-faces, of the preheater. The air supply areas 5, 6 for primary air P and sec-ondary air S are placed on opposite sides of the flue gas duct 2, substantially on the same level.
The heat exchanger structures terminating in the air supply areas 5, 6 are, in the flowing direction of the flue gases F, the last ones of the heat exchanger structures of the preheater 1 placed in the flue gas duct 2. In the examples, the flue gas duct 2 is vertical, and the flue gases F flow downwards from an upper level so that the air supply areas 5, 6 are placed lowermost. In the beginning (that is, in the example, on the upper level), the flue gases F are hotter than in the end (in the example, on the bottom), so that the combustion air P, S can be made hotter when it is heated last before the outlet at the upper part of the preheater 1.

A basic idea of the configuration is that the air supply areas 5, 6 are perpen-dicularly facing each other on the opposite walls of the flue gas duct 2. In the horizontal flue gas duct 2, this means that the air supply areas 5, 6 are oppo-site each other, substantially at the same height. If the flue gas duct 2 is in another position, the air supply areas 5, 6 are in the same zone, which zone is perpendicular to the central line 2X of the flue gas duct 2.

The primary air P and secondary air S heated with the preheater 1 are guided with suitable channel structures from the upper part of the preheater into the boiler 7. In the example, the primary air P is supplied to the inlet of fluidized air and the secondary air S is supplied to the air supply level on the wall of the boiler 7. In the preheater 1, the combustion air P, S is heated to a temperature of about 150 to 250 C.

The heat exchangers of the preheater 1 consist of one or more units. In this context, a unit refers to an aggregate, in which the ends of the pipes extend from one wall of the flue gas duct 2 to another wall of the flue gas duct.
Pref-erably, a unit in a vertical flue gas duct 2 comprises 20 to 30 pipes on top of each other and about a hundred pipes adjacent to each other.

Furthermore, one unit may consist of one or more subunits connected to each other. Preferably, a unit consists of two or more subunits. The building up of a preheater to be assembled of several subunits is often easier than the building up of a preheater of a single large unit.

Figures 3, 4, 5, 8, and 12 show applications, in which the preheater 1 for combustion air consists of several units. The pipes of the heat exchanger structures which are primarily effective on the heat transfer are placed trans-versely to the flowing direction of the flue gases F in the flue gas duct 2.
In the configurations shown in Figs. 3, 4 and 5, the lowermost units 9 are for both primary and secondary air P, S. The lowermost units 9, to which the air to be heated with the preheater 1 is supplied from the air supply area 5, 6, are called cold units. In the configurations according to Figs. 3, 4 and 5, the uppermost units 10 have a structure similar to the units of a conventional preheater; that is, solely either primary air P or secondary air S is supplied into a single unit.
The pipes of the same air circulation can be adjacent to each other, wherein the structure is similar to that of Fig. 3. In the configuration of Fig. 3, the pipes of the primary air circulation P and the pipes of the secondary air circulation S are on opposite sides of the flue gas duct 2. The configuration can also be implemented in such a way that every other pipe element is for primary air P
and every other one is for secondary air S, wherein the structure is similar to that of Fig. 4.

In an application according to an embodiment of the invention shown in Fig. 5, an air deflecting chamber 11 is provided as a deflecting structure for the air flow in the centre of the primary and secondary air structures in the lowermost unit 9. The air deflecting chamber 11 comprises separate facilities for both the primary and the secondary air circulation. Preferably, the air deflecting chamber 11 that reduces the cross-sectional area of the flue gas duct 2 increases the flow rate of flue gases F at the terminal part of the flue gas duct, improving the heat transfer on the flue gas side. Furthermore, the embodiment of Fig. 5 is advantageous for the replaceability of the units, because the cold heat exchanger structures of both air circulations are placed lowermost of the units 9, 10 of the preheater. In the configuration of Fig. 5, the lowermost unit 9 consists of pipe portions 12 and deflecting cham-bers 11. The primary air circulation P comprises two sections 12 consisting of pipes and the space of a deflecting chamber 11 connecting the same. In a corresponding manner, the secondary air circulation S consists of two por-tions 12 consisting of pipes and the space of a deflecting chamber 11 con-necting them. As can be seen in the example, the inlets 5, 6 and outlets 13 of the air circulation of the lowermost unit 9 are on different levels. The outlet 13 is before the inlet 5, 6 in the flowing direction of the flue gases F. In this verti-cal flue gas duct 2, in which the flue gases F flow from an upper level down-wards, the outlet 13 is higher than the inlet 5, 6.
Figure 6, in turn, shows an application, in which the preheater 1 consists of a single unit 14. In the presented embodiment, the heat exchanger structures of the preheater 1 are implemented with continuous pipes extending from the cold end to the hot end. In this advantageous embodiment, the heat transfer surface of the preheating device 1 consists, in its entirety, of a pipe element extending from the bottom to the top. Also in this configuration, the pipes of the heat exchanger structures which are primarily effective on the heat transfer are placed transversely to the flowing direction of the flue gases F
in the flue gas duct 2. In an advantageous embodiment, one of the adjacent elements is for primary air and the other for secondary air. The sizes of the pipes may be equal or different, depending on the reciprocal proportions of primary air P and secondary air S. The diameters of the pipes can be selected according to the need, to be different for the primary and secondary air side P, S. The pipe spacing may be, for example, normal 75 x 75 mm, or the spacing can be selected to provide a desired flue gas rate. In an embodiment, the primary and secondary air circulations P, S are interleaved so that in a recurrent series, there are two pipes of the primary air circulation and two pipes of the secondary air circulation adjacent to them. In another embodiment, in turn, in a recurrent series, there are two pipes of the primary or secondary air circulation, and one pipe of the secondary or primary air cir-culation in between.

Figures 7 to 10 show an embodiment, in which the upper part 15 of the heat exchanger structure of the preheater is implemented with continuous pipes.
In the cold end of the heat exchanger structure, in turn, an air deflecting chamber 11 is used as a deflecting structure for the air flow in the centre of the primary and secondary air units. Figure 7 shows a partial enlargement of a detail in Fig. 8, showing how the pipes of the unit have two deflections of 900.
Figure 9 shows a cross-section of location A-A in Fig. 8. Figure 10 shows a partial enlargement of a detail in Fig. 9. From Figs. 9 and 10, it can be seen how the pipes of the unit are placed on different levels t1-t6 of the preheater 1. In the example of Fig. 10, the pipes of the primary air circulation P are shaded, and the pipes of the secondary air circulation S are unshaded. In this example, broken lines are used to indicate the correspondence of some pipes on different levels t4, t5.

Figures 11 to 13 show another embodiment, in which the upper part 16 of the 5 heat exchanger structure of the preheater 1 is implemented with continuous pipes. Also in this example, in the cold end of the heat exchanger structure, an air deflecting chamber 11 is used as a deflecting structure for the air flow in the centre of the primary and secondary air units. Figure 11 shows the two outermost pipes 16a of the upper part 16 of the primary air circulation P. It 10 can been seen in the figure that the heat exchanger structures have been made of pipes by bending so that the straight portions of the pipes are placed both parallel to the central line 2X of the flue gas duct 2 and perpendicular to the central line of the flue gas duct.

Preferably, the pipe sections parallel to the central line 2X of the flue gas duct 2 are connected to each other, for example by binding. Thus, possible dis-placement and vibration of the pipes is reduced, and thereby also problems of vibration of the preheating device 1 are reduced.

Figure 13 shows a cross-section of location B-B in Fig. 12. In the figure, it can be seen how the pipes of the unit are placed on different levels t1-t6 of the preheater. A substantial difference between the examples shown in Figs.
7 to 10 and in Figs. 11 to 13 is the density at which the pipes are connected to the upper part of the deflecting chamber. In the configuration of Figs. 11 to 13, the horizontal distance between adjacent pipes is substantially equal to the horizontal distance between adjacent pipes in the upper part of the pre-heater. In other words, the horizontal distance between adjacent pipes is substantially the same on all levels t1 to t6.

In the configuration shown in Figs. 7 to 10, the horizontal distance between pipes of the secondary air circulation S in the upper part t5 of the deflecting chamber 11 is substantially equal to the horizontal distance between pipes of the secondary air circulation in the upper part t1 t4 of the preheater 1.
Also, the horizontal distance between pipes of the primary air circulation P in the upper part t5 of the deflecting chamber 11 is substantially equal to the hori-zontal distance between pipes of the primary air circulation in the upper part t1 t4 of the preheater 1. In the lower part t6 of the deflecting chamber 11, the density of the pipes is the same as in the upper part t1-t4 of the preheater 1.
On the other side of the deflecting chamber 11, all the pipes of the lower part t6 are pipes of the primary air circulation P, and those on the other side are pipes of the secondary air circulation S.

Figure 14 also shows an embodiment, in which the upper part 15 of the heat exchanger structure of the preheater 1 is implemented with continuous pipes.
In this embodiment, a supply chamber 11' is used for supplying for the pri-mary and secondary air units at the cold end 9 of the heat exchanger struc-ture. The supply chamber 11' is placed in the centre of the lower part of the flue gas duct 2 where the air to be heated is introduced from the outside of the flue gas duct, preferably from the ends of the supply chamber 11'. The supply chamber 11' comprises both the first air supply area 5 and the second air supply air 6 for supplying the heat exchanger structures with air to be heated. The primary air P and the secondary air S are supplied from the sup-ply chamber 11' in different directions, and as it can be seen in the figure, the air supply direction in the first air supply area 5 is at an angle of 180 to the air supply direction of the second air supply area 6.
Furthermore, for cleaning and maintenance of the preheater 1, the device comprises other structures than the above-described units of the preheater.
The figures show sooting means 17, service hatches 18 as well as an ash removal opening 19. Furthermore, the device may also comprise other structures and parts which are not shown in the figures.

In the above-presented examples, the flue gas duct 2 is vertical, and the flue gases F flow downwards from an upper level, so that the air supply areas 5, 6 are placed lowermost. The flue gas duct may also be implemented in another way. For example, in Fig. 15, the flue gas duct 2 is vertical so that the flue gases F flow from the bottom upwards, wherein the air supply areas 5, 6 are placed uppermost. The flue gas duct may also be, for example, totally or partly horizontal, in which case the flue gases flow in the horizontal direction. At the beginning, the flue gases are hotter than at the end, and the combustion air can be made hotter when it is heated last before the outlet at the initial end of the flue gas duct.
By combining, in various ways, the modes and structures disclosed in con-nection with the different embodiments of the invention presented above, it is possible to produce various embodiments of the invention in accordance with the spirit of the invention. Therefore, the above-presented examples must not be interpreted as restrictive to the invention, but the embodiments of the invention may be freely varied within the scope of the inventive features pre-sented in the claims hereinbelow.

Claims (16)

1. A preheating device (1) for combustion air in a boiler, the device compris-ing:
- first heat exchanger structures fitted in a flue gas duct (2), for heating primary air (P), and - second heat exchanger structures fitted in a flue gas duct (2), for heating secondary air (S), characterized in that the inlet of the first heat exchanger structure and the inlet of the second heat exchanger structure are placed substantially on the same level, the level being substantially perpendicular to the central line of the flue gas duct.
2. The preheating device according to claim 1, characterized in that the first heat exchanger structures comprise a set of heat exchanger pipes forming a primary air circulation (P), primary air flowing in them, and the second heat exchanger structures comprise a set of heat exchanger pipes forming a sec-ondary air circulation (S), secondary air flowing in them.
3. The preheating device according to claim 1 or 2, characterized in that the device further comprises:
- the supply for the first heat exchanger structure, for supplying primary air to be heated to the primary air circulation (P), and - the supply for the second heat exchanger structure, for supplying secondary air to be heated to the secondary air circulation (S).
4. The preheating device according to any of the claims 1 to 3, character-ized in that the device comprises a first air supply area (5) in the wall of the flue gas duct (2), for supplying air to be heated to the first heat exchanger structures, and a second air supply area (6) in the wall of the flue gas duct (2), for supplying air to be heated to the second heat exchanger structures, and the first air supply area (5) is opposite the second air supply area (6).
5. The preheating device according to claim 4, characterized in that the first heat exchanger structures and the second heat exchanger structures extend at the air supply areas (5, 6) to the central area of the flue gas duct (2), having deflecting structures (11) for the air flow (P, S), for changing the direction of the air flows of the heat exchangers.
6. The preheating device according to any of the preceding claims 1 to 5, characterized in that the first heat exchanger structures and the second heat exchanger structures are staggered.
7. The preheating device according to any of the preceding claims 1 to 6, characterized in that the first heat exchanger structures and the second heat exchanger structures are formed of pipes by bending so that the straight por-tions of the pipes are placed both parallel to the central line (2X) of the flue gas duct (2) and perpendicular to the central line of the flue gas duct.
8. A power plant, comprising at least a boiler (7) and a flue gas duct (2), to which the flue gases (F) exiting the boiler are led; the power plant further comprising a preheating device (1) for heating the combustion air (P, S) to be supplied into the boiler, the preheating device comprising:
- first heat exchanger structures fitted in a flue gas duct (2), for heating primary air (P), and - second heat exchanger structures fitted in a flue gas duct (2), for heating secondary air (S), characterized in that the inlet of the first heat exchanger structure and the inlet of the second heat exchanger structure are placed substantially on the same level, the level being substantially perpendicular to the central line of the flue gas duct.
9. The power plant device according to claim 8, characterized in that the first heat exchanger structures comprise a set of heat exchanger pipes forming a primary air circulation (P), primary air flowing in them, and the second heat exchanger structures comprise a set of heat exchanger pipes forming a sec-ondary air circulation (S), secondary air flowing in them.
10. The power plant according to claim 8 or 9, characterized in that the pre-heating device further comprises:
- the supply for the first heat exchanger structure, for supplying primary air to be heated to the primary air circulation (P), and - the supply for the second heat exchanger structure, for supplying secondary air to be heated to the secondary air circulation (S).
11. The power plant according to any of the claims 8 to 10, characterized in that the preheating device of the power plant comprises a first air supply area (5) in the wall of the flue gas duct (2), for supplying air to be heated to the first heat exchanger structures, and a second air supply area (6) in the wall of the flue gas duct (2), for supplying air to be heated to the second heat exchanger structures, and the first air supply area (5) is opposite the second air supply area (6).
12. The power plant according to claim 11, characterized in that the first air supply area (5) and the second air supply area (6) are located substantially at the same height.
13. The power plant according to claim 11 or 12, characterized in that the first air supply area (5) and the second air supply area (6) are the lowermost parts of the preheater (1) placed in the flue gas duct (2).
14. The power plant according to claim 11 or 12, characterized in that the first air supply area (5) and the second air supply area (6) are the uppermost parts of the preheater (1) placed in the flue gas duct (2).
15. The power plant according to any of the preceding claims 8 to 13, char-acterized in that the flue gas duct (2) is vertical and the flue gases (F) from the boiler (7) are introduced into the flue gas duct from its upper part and removed from the lower part.
16. The power plant according to any of the preceding claims 8 to 12 or 14, characterized in that the flue gas duct (2) is vertical and the flue gases (F) from the boiler (7) are introduced into the flue gas duct from its lower part and removed from the upper part.
CA2777496A 2009-05-22 2010-05-21 A preheater for combustion air, and a power plant Abandoned CA2777496A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FI20095566 2009-05-22
FI20095566A FI20095566A (en) 2009-05-22 2009-05-22 Combustion air preheater and power plant
PCT/FI2010/050415 WO2010133773A1 (en) 2009-05-22 2010-05-21 A preheater for combustion air, and a power plant

Publications (1)

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CA2777496A1 true CA2777496A1 (en) 2010-11-25

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CA2777496A Abandoned CA2777496A1 (en) 2009-05-22 2010-05-21 A preheater for combustion air, and a power plant

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US (1) US20120060774A1 (en)
EP (1) EP2433055A1 (en)
CN (1) CN102439365A (en)
BR (1) BRPI1010943A2 (en)
CA (1) CA2777496A1 (en)
CL (1) CL2011002940A1 (en)
FI (1) FI20095566A (en)
RU (1) RU2011152388A (en)
WO (1) WO2010133773A1 (en)

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CN109185913A (en) * 2018-09-18 2019-01-11 北京质为科技有限公司 A kind of air preheater preventing clogging up device
CN109855442B (en) * 2018-12-29 2024-02-27 上海工程技术大学 Medium participation radiation heating gasification device
CN110118362B (en) * 2019-06-10 2024-02-23 西安热工研究院有限公司 Tubular air preheater capable of preventing ammonium bisulfate from being blocked

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BRPI1010943A2 (en) 2019-04-09
FI20095566A (en) 2010-11-23
EP2433055A1 (en) 2012-03-28
US20120060774A1 (en) 2012-03-15
CN102439365A (en) 2012-05-02
RU2011152388A (en) 2013-06-27
CL2011002940A1 (en) 2012-07-20
WO2010133773A1 (en) 2010-11-25
FI20095566A0 (en) 2009-05-22

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