EP1106918A1 - Wasserhitzer und verfharen zum Umleiten von Verbrennungspasen darin. - Google Patents

Wasserhitzer und verfharen zum Umleiten von Verbrennungspasen darin. Download PDF

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Publication number
EP1106918A1
EP1106918A1 EP00660225A EP00660225A EP1106918A1 EP 1106918 A1 EP1106918 A1 EP 1106918A1 EP 00660225 A EP00660225 A EP 00660225A EP 00660225 A EP00660225 A EP 00660225A EP 1106918 A1 EP1106918 A1 EP 1106918A1
Authority
EP
European Patent Office
Prior art keywords
combustion space
primary
boiler
connection
gas
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.)
Withdrawn
Application number
EP00660225A
Other languages
English (en)
French (fr)
Inventor
Veijo Koivuranta
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.)
Turun Muurausurakointi Oy
Original Assignee
Turun Muurausurakointi 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 Turun Muurausurakointi Oy filed Critical Turun Muurausurakointi Oy
Publication of EP1106918A1 publication Critical patent/EP1106918A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23M—CASINGS, LININGS, WALLS OR DOORS SPECIALLY ADAPTED FOR COMBUSTION CHAMBERS, e.g. FIREBRIDGES; DEVICES FOR DEFLECTING AIR, FLAMES OR COMBUSTION PRODUCTS IN COMBUSTION CHAMBERS; SAFETY ARRANGEMENTS SPECIALLY ADAPTED FOR COMBUSTION APPARATUS; DETAILS OF COMBUSTION CHAMBERS, NOT OTHERWISE PROVIDED FOR
    • F23M9/00—Baffles or deflectors for air or combustion products; Flame shields
    • F23M9/02—Baffles or deflectors for air or combustion products; Flame shields in air inlets
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B5/00—Combustion apparatus with arrangements for burning uncombusted material from primary combustion
    • F23B5/04—Combustion apparatus with arrangements for burning uncombusted material from primary combustion in separate combustion chamber; on separate grate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
    • F23B7/00—Combustion techniques; Other solid-fuel combustion apparatus
    • F23B7/002—Combustion techniques; Other solid-fuel combustion apparatus characterised by gas flow arrangements
    • F23B7/007—Combustion techniques; Other solid-fuel combustion apparatus characterised by gas flow arrangements with fluegas recirculation to combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B5/00—Combustion-air or flue-gas circulation in or around stoves or ranges
    • F24B5/02—Combustion-air or flue-gas circulation in or around stoves or ranges in or around stoves
    • F24B5/028—Arrangements combining combustion-air and flue-gas circulation

Definitions

  • the invention relates to a boiler for burning a fuel, such as wood, and a method for conducting gases in such a boiler, as defined in the preambles of the independent claims below.
  • the combustion process of solid fuels such as wood comprises many stages. With a rough division of the process, the heated fuel first dries, i.e. any water present evaporates, and then part of the fuel is gasified forming burning gases, which subsequently burn with a flame after having been brought into contact with oxygen. The fuel leaves carbon as a solid residue, which, when further heated, is also gasified and burns, and non-combustible components, i.e. ashes. In conventional combustion, for instance when wood is burnt in a fireplace, the gasified wood constituents, called volatile constituents, will contact oxygen and burn almost immediately after their gasification.
  • combustion based on gasification of fuel is that the fuel is heated in an oxygen-free space, or at least with such a small amount of oxygen that the combustion remains incomplete.
  • the fuel is transformed into unburned flue gases, which are subsequently burnt in a space separate from the gasification location.
  • US patent specification 5,564,348 discloses a fireplace, in which partly unburned gases produced in the fuel bed in the primary combustion space are circulated upwards in a duct formed in the wall of the primary fire box, further across the firebox cover, then downwards in a duct formed on the second wall, and finally back to the fuel bed.
  • primary air can be added to the circulated gas in order to maintain fuel combustion, on the one hand, and further heating the fuel bed to maintain gasification, on the other hand.
  • the partly unburned gases are mixed with secondary air, and the gas mixture thus produced is conducted to the secondary combustion space, where secondary air and primary gases react by burning into flue gases, which are subsequently evacuated from the fireplace.
  • the structure becomes complex and thus difficult to clean due to the ducts of the primary combustion space.
  • cool air is mixed with the circulated gas, thus retarding the fuel gasification.
  • the object of the present invention is to provide a boiler and a method that minimise the prior art problems mentioned above.
  • a special object of the invention is to provide an efficient low-emission method and boiler suitable for burning solid fuels.
  • the boiler of the invention for burning a fuel such as wood is characterised by comprising a jacket and a primary combustion space defined by first walls and a secondary combustion space defined by second walls, both formed within the jacket.
  • the primary and secondary combustion spaces are connected by a primary gas connection, through which gases are conducted from the primary combustion space to the secondary combustion space. At least the following connections penetrate through the boiler jacket:
  • the boiler also comprises a gas circulating connection for conducting gas to the primary combustion space.
  • said air inlet connection opens in the secondary combustion space, in the vicinity of the wall of this space, and the gas circulating connection extends from the vicinity of the mouth of said air inlet connection to one or more circulating gas inlet connections extending through the first wall, in order to circulate gas from the secondary combustion space to the primary combustion space.
  • a boiler implies the device of the invention for burning a fuel.
  • the primary combustion space is the part of the boiler where fuel is gasified. Such gases are also burnt to some extent in the primary combustion space of the invention. This primary combustion reaction is controlled i.a. by the amount of oxygen entering the primary combustion space.
  • the secondary combustion space is the part of the boiler where the unburned gases derived from the primary combustion space are burnt in a reaction called the secondary combustion reaction.
  • the primary gas connection connecting the primary and secondary combustion spaces is any pipe, opening or other tube, through which gases are conducted from the primary combustion space to the secondary combustion space.
  • the boiler preferably also comprises a separate connection for the removal of ashes from the primary combustion space.
  • the secondary combustion space may have any shape, provided that it allows for efficient and pure gas combustion.
  • part of the air introduced into the secondary combustion space passes at least occasionally to the gas circulating connection, and through this to the primary combustion space to work as primary air.
  • the gas flows in the secondary combustion chamber are very turbulent and strong, and hence the circulating gas must be taken in the vicinity of the mouth of the air inlet connection, as mentioned above. Otherwise the gas flows in the secondary combustion space may capture all of the introduced air, and then only unburned primary gas or already burnt flue gases would pass to the gas circulating connection.
  • Collection of circulating gas in the vicinity of said air supply location means that circulating gas is collected in the same part of the secondary combustion space to which air is introduced.
  • the gas circulating connection may be any duct or pipe.
  • the circulating connection may consist of a masonry duct encircling the primary combustion space on one or more sides and having a width equal to the entire primary combustion space.
  • the gas circulating connection is disposed within the jacket in its totality. This allows pipes or similar running outside the boiler to be avoided, and heat insulation and transfer of heat energy between the circulating connection and the remaining structure is easier to control.
  • a substantial section of the gas circulating connection is preferably located between the outer surface of the first wall and the inner surface of the boiler jacket.
  • a substantial section of the gas circulating connection communicates with the outer surface of the first wall. This design allows maximally efficient heat exchange between the circulating gas mixture passing in the gas circulating connection and the primary combustion space.
  • the gas circulating connection extends directly from under the mouth of said air inlet connection, from the vicinity of the wall of the secondary combustion space, downwards at least to the bottom level of the secondary combustion space.
  • Such a design allows air to be efficiently guided to the circulating connection and the circulating gas mixture to be conducted to the level of the fuel bed at the bottom of the primary combustion space.
  • a preferred solution further comprises one or more gas circulating inlet connections opening in the lower part of the primary combustion space, preferably at the bottom of the primary combustion space, where for instance a fuel bed of solid fuel is located.
  • the boiler comprises one or more circulating gas inlet connections, which open in the upper part of the primary combustion space.
  • the primary gases will mix with the circulating gases sufficiently well to ensure proper combustion.
  • the secondary combustion space of the invention is located substantially above the primary combustion space and the primary gas connection extends from the upper part of the primary combustion space to the secondary combustion space.
  • At least part of the second walls defining the secondary combustion space are formed substantially hood-like or dome-like above the primary gas connection. Then the walls of the secondary combustion space will efficiently collect the naturally ascending hot gases, conducting them towards the exhaust connection.
  • part of the second walls may consist of any other part than the hood-like part mentioned above.
  • the boiler jacket may act as the wall of the secondary combustion space, for instance over the section between the primary combustion space and the hood-like wall portion. The air required for combustion, which is led from the air inlet connection to the secondary combustion space, may then be conducted for instance adjacent to said wall portion formed by the jacket, between the jacket and the hood-like wall portion.
  • the method of the invention for leading gases in a boiler for burning a fuel such as wood is characterised by
  • the circulating gas mixture is conducted to the fuel bed in the primary combustion space along the outer surface of the wall of the primary combustion space, so that indirect heat transfer occurs between the circulating gas mixture and the primary combustion space by the intermediary of the wall.
  • the air required for combustion is introduced into the secondary combustion space in the vicinity of the wall, and the circulating gas mixture is collected substantially directly below said air supply location.
  • solid fuel is fed into the primary combustion space, so that a fuel bed is formed at the bottom of the primary combustion space.
  • a chief advantage of the boiler and the method of the invention is that the heat required for fuel gasification is supplied directly from the gas mixture derived from the hot secondary combustion space.
  • a second major advantage of the boiler and the method of the invention is that fuel combustion in the boiler is easy to control by controlling the amounts of fuel, primary and secondary air, and circulating gas mixture, respectively.
  • a further vital advantage of the boiler and method of the invention is that the combustion process easily achieves the high temperatures required for pure combustion, because in the boiler of the invention, the combustion spaces are not necessarily cooled directly, but the energy produced in combustion is recovered only from the flue gases, after the secondary combustion process.
  • An advantage of the boiler and method of the invention is that the gas flow in the primary combustion space can be reduced by control to such an extent that the flue gases entrain hardly any ashes or sooth at all. Thus emissions are reduced, the need for cleaning chimneys is reduced and no hot material will escape through the chimney.
  • FIG 1 shows the boiler 1 of the invention and figure 2 gas flows within this boiler.
  • the primary combustion space 4 of the boiler 1 is supplied with fuel from a fuel connection, which is not shown in the figure.
  • the fuel connection may be for instance an openable hatch formed in the first walls 3 defining the boiler jacket 2 and the primary combustion space 4, through which split billets, wood chips or any other suitable fuel is fed to the bottom 9 of the primary combustion space 4.
  • the fuel is heated so as to be gasified into primary gases A, however, due to the small amount of primary air, i.e. oxygen, the gases will burn only partly in the primary combustion space 4. Even this partial combustion heats the fuel and thus maintains gasification.
  • the partly unburned primary gases A are led through the primary gas connection 7 located in the upper part 16 of the primary gas space 4 into the secondary combustion space 6, where the primary gases A are contacted with the secondary air C, whereby the unburned primary gases A burn.
  • the hot flue gases D thus formed are led to the exhaust connection 10.
  • the energy contained in the flue gases D can be recovered for instance by heating the water in a hot water tank.
  • the air B required for combustion is taken from air inlet connection 8 in-between the jacket 2 and the hood-like wall 5 of the secondary combustion space 6, adjacent to the wall 5a of the secondary combustion space 6 formed by the jacket 2, from where the turbulent gas flow captures the secondary air C required for the secondary combustion reaction.
  • the circulating gas mixture E contains a large amount of relatively cool air B, it is probably cooler than the outer surface 13, whereby the gas mixture E naturally tends to flow down in the gas circulating connection 11, while being preheated before being fed into the primary combustion space. If on the other hand, the circulating gas mixture E contains a large amount of flue gases D, the gas is probably warmer than the outer surface 13 of the primary combustion space 4, whereby the circulating gas mixture E heats the fuel to be gasified indirectly. The primary air contained in the circulating gas mixture E feeds the combustion in the primary combustion space 4, and if the circulating gas mixture E is sufficiently warm, it will transfer its inherent heat directly to the fuel.
  • One crucial idea of the invention is that, with the dimensions of boiler 1, the fuel, its supply and the other conditions correctly designed, the amounts of primary and secondary air, respectively, will be balanced according to the cycle described below. If there is an increase in gasification, the secondary combustion reaction accelerates, a greater portion of air B is used for secondary combustion, the amount of primary air decreases, the primary reaction decelerates and the gasification decreases.
  • the combustion process can be brought to the desired output level.
  • gas flows, temperatures, pressures and concentrations can be measured at different locations of the system, and these values will then allow e.g. control of the fuel and air supply.
  • a fan may be fitted e.g. in the gas circulating connection 11 in order to increase the flow of circulating gas mixture E if desired.
  • FIG 3 shows a second exemplifying boiler 1 of the invention.
  • the boiler is otherwise similar to those of figures 1 and 2, with the exception that the upper part 16 of the primary combustion space extends further up towards the exhaust connection 10.
  • the circulating gas connections 12 extend from the circulating gas connection 11 through the walls 3 to the upper part 16 of the primary combustion space.
  • arrow E illustrates the flow of circulating gas mixture in the boiler of the figure.
  • the gas flows are identical to those shown in figure 2 in principle.
  • the boiler of the invention may have other dimensions than those exemplified in the figures. It may vary in size, from a fireplace for heating e.g. a single-family house to a boiler of a large power plant.
  • the boiler may be made of various materials, such as tiles or metal. Any gasified fuel, such as wood pellets, wood chips or split billets, is suitable as the fuel of the boiler.
  • An automatic device for feeding pellets, wood chips, split billets or any other fuel has preferably been connected to the boiler.
  • the boiler of the invention can be combined with a conventional oil burner, allowing the benefits of both the methods of combustion.
  • the primary and secondary combustion spaces may be in any relationship other than on top of each other, and they may be spaced from each other.
  • the fuel may be supplied to the boiler of the invention in batches or continuously.
  • the primary combustion space may be equipped with an additional separate primary air feed connection.
  • secondary air may be introduced into the secondary combustion space at different locations of the secondary combustion space, for instance at the primary gas connection, or only at the trailing end of the secondary combustion space.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Solid-Fuel Combustion (AREA)
EP00660225A 1999-12-07 2000-12-07 Wasserhitzer und verfharen zum Umleiten von Verbrennungspasen darin. Withdrawn EP1106918A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI992624 1999-12-07
FI992624A FI107352B (fi) 1999-12-07 1999-12-07 Kattila kiinteän polttoaineen polttamiseksi ja menetelmä kaasujen johtamiseksi siinä

Publications (1)

Publication Number Publication Date
EP1106918A1 true EP1106918A1 (de) 2001-06-13

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EP00660225A Withdrawn EP1106918A1 (de) 1999-12-07 2000-12-07 Wasserhitzer und verfharen zum Umleiten von Verbrennungspasen darin.

Country Status (2)

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EP (1) EP1106918A1 (de)
FI (1) FI107352B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102927558A (zh) * 2012-11-12 2013-02-13 青岛艳阳天环保锅炉有限公司 燃煤全自动气化燃烧锅炉
CN103776159A (zh) * 2014-02-15 2014-05-07 魏银先 立体燃化烟长行程传热式燃煤锅炉

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4210995A (en) * 1977-09-12 1980-07-08 Heimburg Richard W Method of constructing a burner
WO1981002620A1 (en) * 1980-03-07 1981-09-17 Lindstroem Ab Olle Procedure for two stage combustion of wood,peat and related fuels
US4404953A (en) * 1981-05-04 1983-09-20 Thulman Robert D Stove for burning combustible solid fuels
EP0176232A2 (de) * 1984-08-23 1986-04-02 The Stack Manufacturing Company Limited Ofen
FR2603686A1 (fr) * 1986-09-05 1988-03-11 Olmotti Humbert Marin Appareil de chauffage universel
US4766876A (en) * 1987-07-24 1988-08-30 Aladdin Steel Products, Inc. Wood stove
US5564348A (en) 1992-04-08 1996-10-15 Gr+E,Uml O+Ee Schl; Rupert Process and a device for regulating the combustion of solid fuels in a combustion plant

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4210995A (en) * 1977-09-12 1980-07-08 Heimburg Richard W Method of constructing a burner
WO1981002620A1 (en) * 1980-03-07 1981-09-17 Lindstroem Ab Olle Procedure for two stage combustion of wood,peat and related fuels
US4404953A (en) * 1981-05-04 1983-09-20 Thulman Robert D Stove for burning combustible solid fuels
EP0176232A2 (de) * 1984-08-23 1986-04-02 The Stack Manufacturing Company Limited Ofen
FR2603686A1 (fr) * 1986-09-05 1988-03-11 Olmotti Humbert Marin Appareil de chauffage universel
US4766876A (en) * 1987-07-24 1988-08-30 Aladdin Steel Products, Inc. Wood stove
US5564348A (en) 1992-04-08 1996-10-15 Gr+E,Uml O+Ee Schl; Rupert Process and a device for regulating the combustion of solid fuels in a combustion plant

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102927558A (zh) * 2012-11-12 2013-02-13 青岛艳阳天环保锅炉有限公司 燃煤全自动气化燃烧锅炉
CN103776159A (zh) * 2014-02-15 2014-05-07 魏银先 立体燃化烟长行程传热式燃煤锅炉

Also Published As

Publication number Publication date
FI107352B (fi) 2001-07-13

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