EP2629007A2

EP2629007A2 - Combustion apparatus

Info

Publication number: EP2629007A2
Application number: EP13155211.9A
Authority: EP
Inventors: Takehiko Kitanaka; Takumi Amano; Miwa Kitanaka; Takahiro Hotta
Original assignee: Northern Light Stoves Co Ltd
Current assignee: Northern Light Stoves Co Ltd
Priority date: 2012-02-14
Filing date: 2013-02-14
Publication date: 2013-08-21
Also published as: EP2629007A3; JP2013190195A; JP5410567B2

Abstract

Provided is a combustion apparatus, including: a fire chamber for combusting wood pellets; a thermoelectric power generation module disposed outside the fire chamber for generating power based on a temperature difference caused by heating with an internal temperature of the fire chamber and by cooling with an external temperature outside the fire chamber; and an electric drive means (an exhaust fan, a blast fan, a drum-type pellet supply system, an ignition heater, an air supply fan) which operates using, as a drive force, thermoelectric power generated by the thermoelectric power generation module.

Description

TECHNICAL FIELD

The present invention relates to a combustion apparatus having a combustion chamber, in particular, a combustion apparatus for combusting wood pellets as a combustion material in a combustion chamber.

RELATED ART

Conventionally, there has been known a pellet stove which uses, as fuel, wood pellets which are a type of alternative energy to fossil fuel such as petroleum oil. Wood pellets are made from lumber dust generated in the process of manufacturing lumber, or timber from forest thinning in the process of forest cultivation, which are shredded into powder and dried, and formed through compression molding into cylinder shapes each having a diameter of about 6 mm and a length of about 10 to 30 mm.
The wood pellets are renewable energy originating from biomass (botanical resources), which can combust without increasing carbon dioxide in the atmosphere, unlike in the case of fossil fuel. In other words, the amount of carbon dioxide emitted by combusted wood pellets is equal to the amount of carbon dioxide consumed during the growth of the material tree, so that the amount of carbon dioxide on the entire globe is balanced (which is based on a so-called carbon neutral concept). For this reason, the use of wood pellets has been brought into the spotlight lately as being effective in mitigating global warming.
A pellet stove using wood pellets as fuel includes a supply means for continuously supplying wood pellets to the origin of fire. As the supply means for supplying wood pellets, there is proposed, for example, a fuel conveying system using screws (see JP 2009-24983 A ). The fuel conveying system using screws has an upper screw and a lower screw arranged in two tiers with one above the other, the screws each being rotated by a drive force of a motor, so that wood pellets input into a fuel storage hopper are raked out to be dropped by the upper screw and the wood pellets thus dropped are pushed out by the lower screw toward the combustion chamber side so as to be conveyed inside the combustion chamber.
The fuel conveyor system using screws, which employs a motor for rotating the screws, obviously requires electric power to drive the motor, and has generally employed, as the power supply, a commercial power source supplied from an electric power company.

DISCLOSURE OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

However, in the case where a commercial power source is employed, the motor fails to be driven when power supply stops from the electric company due to a power outage or the like, which disables the fuel conveyor system, making it impossible to supply the wood pellets as fuel to the combustion chamber. As a result, the pellet stove, which is spared the need for electricity as the heat source by using wood pellets as the heat source through the combustion of the wood pellets as fuel, still cannot be used during a power outage because of being incapable of supplying fuel.
Further, in order to make the best use of the pellet stove which uses wood pellets originating from biomass (botanical resources) as renewable energy, it may be desired to be able to supply wood pellets without using, even for driving a motor, a commercial power source which is generated through the combustion of fossil fuel such as petroleum oil.
The present invention has an object to provide a combustion apparatus capable of reliably supplying fuel without using a commercial power which stops power supply due to a power outage or the like, and further, a combustion apparatus capable of contributing to mitigating global warming in terms of fuel supply.

MEANS FOR SOLVING THE PROBLEM

In order to attain the above-mentioned object, a combustion apparatus according to the present invention includes: a combustion chamber for combusting a fuel material; a thermoelectric power generation module for generating power based on a temperature difference caused by heating with a combustion temperature generated along with the combustion in the combustion chamber and by cooling with an external temperature outside the combustion chamber; and an electric drive means which operates using, as a drive force, thermoelectric power generated by the thermoelectric power generation module.
Further, the combustion apparatus according to another aspect of the present invention further includes an electric storage device for storing electricity using thermoelectric power generated by the thermoelectric power generation module, in which the electric storage device supplies power that is to be used as a drive force for driving the electric drive means.
Further, in the combustion apparatus according to further another aspect of the present invention, the electric drive means is at least one of a combustion material supply system for supplying the combustion material from a combustion material storage to the combustion chamber, a fan for supplying air to or exhausting air from the combustion chamber, and a fan for sending out air heated in the combustion chamber.
Further, the combustion apparatus according to still further another aspect of the present invention further includes a combustion temperature conducting means for conducting heat generated along with the combustion in the combustion chamber, to a heater of the thermoelectric power generation module.
Further, in the combustion apparatus according to still further another aspect of the present invention, the combustion material is wood pellets.

EFFECT OF THE INVENTION

According to the combustion apparatus according to the present invention, a thermoelectric power generation module generates power based on a temperature difference caused by heating with an internal temperature in the combustion chamber for combusting the combustion material and by cooling with an external temperature outside the combustion chamber, and electric drive means operates using, as a drive force, thermoelectric power generated by the thermoelectric power generation module, so that the fuel can be reliably supplied by supplying fuel by the electric drive means, without using a commercial power source which stops supplying power due to a power outage or the like, and further the present invention is capable of contributing to mitigating global warming in terms of fuel supply.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a sectional explanatory view schematically illustrating a configuration of a combustion apparatus according to a first embodiment of the present invention;
Fig. 2 is an explanatory view illustrating an exemplary case where a thermoelectric power generation module utilizes a temperature difference between a combustion temperature and an outdoor air temperature;
Fig. 3 is a sectional explanatory view schematically illustrating a configuration of a combustion apparatus including a screw-type pellet conveying system;
Fig. 4 is an explanatory view schematically illustrating, in a longitudinal section, a pellet stove according to a second embodiment of the present invention;
Fig. 5 is a partial explanatory view of a section taken along the line A-A of Fig. 4;
Fig. 6 is a partial explanatory view of a section taken along the line B-B of Fig. 4;
Fig. 7 is a perspective explanatory view illustrating a configuration of the radiator of Fig. 4;
Fig. 8 is an explanatory diagram illustrating a chimney in transverse section, the chimney having the thermoelectric power generation module mounted thereon;
Fig. 9 is an explanatory diagram schematically illustrating a method of conducting heat to a thermoelectric power generation module according to a third embodiment of the present invention; and
Fig. 10 is an explanatory diagram schematically illustrating another method of conducting heat to the thermoelectric power generation module.

BEST MODES FOR CARRYING OUT THE INVENTION

In the following, embodiments of the present invention are described with reference to the drawings.

(First Embodiment)

Fig. 1 is a sectional explanatory view schematically illustrating a configuration of a combustion apparatus according to a first embodiment of the present invention. As illustrated in Fig. 1, a pellet stove (combustion apparatus) 10 includes a stove main body 11 and a fuel storage 12. The stove main body 11 and the fuel storage 12 are each in a box shape or a cylindrical shape having an internal space, and arranged side by side via an adjacent space S therebetween while being coupled to each other via a fuel supply path 13, to thereby form the combustion apparatus 10.
The pellet stove 10 uses wood pellets P as fuel (combustion material), which are renewable energy originating from biomass (botanical resources). The wood pellets P are combusted inside the stove main body 11, so as to heat up a room or the like in which the stove main body 11 is installed.
A chimney 14 for exhaust is protrudingly formed on an upper end surface (top surface) of the stove main body 11, the chimney 14 communicating with the internal space of the main body while extending upward substantially vertically so as to open to external air. At the base of the chimney 14, an exhaust fan 15 is installed for blowing air toward the external air opening. In an upper end surface (top surface) of the fuel storage 12, a fuel input port 12a, which communicates with a hopper 16 provided in the upper part of the storage, is opened and a lid 17 for opening and closing the fuel input port 12a is also provided. The lid 17 is opened so as to allow the wood pellets P to be input into the hopper 16 through the fuel input port 12a, so that the wood pellets P are accumulated and stored in the hopper 16. A pellet discharge port 16a opens in the lower end of the hopper 16 so that the wood pellets P accumulated and stored in the hopper 16 automatically fall off the pellet discharge port 16a.
The stove main body 11 has an internal space partitioned, by a partition wall 18 provided in the lower part thereof, into two spaces, namely, an upper space serving as a fire chamber (fuel chamber) 19 and a lower space for storing an ash tray 20. The partition wall 18 is equipped with a fire grate 21 serving as a fuel shelf on which the wood pellets P are placed and combusted, the fire grate 21 being installed substantially in the center of the partition wall 18 in plan view at a position lowered relative to the surrounding area thereof. The fire chamber 19 as the upper space serves as a combustion chamber for combusting the wood pellets P therein, and the lower space serves as an ash tray storage chamber for placing the ash tray 20 which receives ash falling off the fire grate 21 after combustion of the wood pellets.
A hot air delivery chamber 22 is defined in the upper front side of the main body of the fire chamber 19. The hot air delivery chamber 22 communicates with the outside of the stove main body 11 via a blast port 22a which opens in the outer surface on the front side of the stove main body 11, and has a blast fan 23 installed therein for blowing out heated air in the fire chamber 19, from the blast port 22a to the outside of the stove main body 11.
A fire chamber port 13a opens at the lower back side of the main body of the fire chamber 19, that is, on the back side of the main body above the partition wall 18. The fire chamber port 13a serves as a communication port to the stove main body 11 from the fuel supply path 13 disposed as being downwardly-inclined from the fuel storage 12 to the stove main body 11. The fire chamber port 13a is provided with a pellet guide 24, which is an extension of the fuel supply path 13 and protrudes inside the fire chamber 19. The pellet guide 24 has the leading edge thereof approaching the fire grate 21 from above.
The fuel supply path 13, which communicates with the fire chamber 19 at one end thereof, has the other end thereof communicating with the inside of the fuel storage 12 via a fuel storage port 13b which opens on the fuel storage 12 side, and the fuel storage port 13b is positioned below the pellet discharge port 16a of the hopper 16.
A drum-type pellet supply system 25 is disposed between the fuel storage port 13b and the pellet discharge port 16a, which is positioned on the side of the fuel storage port 13b and below the pellet discharge port 16a so as to send the wood pellets P accumulated and stored in the fuel storage 12 to the fuel supply path 13. The drum-type pellet supply system 25 has a drum 25a as a rotating body, and the drum 25a is axially supported in an axially rotatable manner so as to move from the pellet discharge port 16a to the fuel storage port 13b with the outer periphery facing the fuel storage port 13b and the pellet discharge port 16a. The drum 25a has, in the outer periphery thereof, a concave portion formed as a receiver 25b for receiving a plurality of wood pellets P, at a plurality of points (four points are illustrated by way of example) spaced apart at regular intervals in a circumferential direction.
The drum-type pellet supply system 25 is motor-driven, for example, so as to be axially rotated about the drum shaft. Along with the rotation, a plurality of wood pellets P discharged from the pellet discharge port 16a are received by the receiver 25b below the pellet discharge port 16a, and the drum 25a proceeds toward the fuel storage port 13 while carrying the wood pellets P, so that the wood pellets P fall off the receiver 25b toward the fuel storage port 13b. The wood pellets P thus falling off make their way from the fuel storage port 13b to the fuel supply path 13, slide down the fuel supply path 13 along the inclination toward the fire chamber port 13, and are guided by the pellet guide 24 from the fire chamber port 13a so as to fall onto the fire grate 21. In this manner, the rotation dynamics of the drum-type pellet supply system 25 allows the wood pellets P accumulated and stored in the fuel storage 12 to be continuously sent along the fuel supply path 13 to the fire grate 21 installed inside the fire chamber 18.
An ignition heater 26 is disposed below the fire grate 21. The ignition heater 26 has the leading edge thereof projected on the upper surface side of the fire grate 21. When the ignition heater 26 is energized to be in a heating state, the wood pellets P accumulated on the upper surface side of the fire grate 21 as being laid over the leading edge are heated and thus the wood pellets P are ignited. Instead of bringing the ignition heater 26 into direct contact with the wood pellets P as described above, a blast fan (not shown) may be used to blow air to the ignition heater 26 which is energized and in a heating state, so that the wood pellets P are blown with heated air from the ignition heater 26, to thereby ignite the wood pellets P.
In the lower part of the stove main body 11, where the lower space serving as an ash tray storage chamber below the fire grate 21 is defined, there is provided an air supply port 27 which opens in the outer surface of the stove main body 11 and communicates with the lower space. Provided in the lower space is an air supply fan 28, which faces the air supply port 27, for drawing air from the outside of the stove main body 11 to the lower space so as to supply air to the fire grate 21
Then, a thermoelectric power generation module 29 is attached to the outer surface of the stove main body 11, on the outside of the fire chamber 19. The thermoelectric power generation module 29 is formed by using a thermoelectric conversion element based on the Seebeck effect for generating thermoelectric power due to a temperature difference given between a hotside and a coolside provided on the front surface and the back surface of the element, and generates thermoelectric power using a temperature difference between the outer surface temperature of the stove main body 11 heated by the combustion in the fire chamber 19 and the ambient temperature (installation site temperature) at a location where the pellet stove 10 is installed.
In other words, the thermoelectric power generation module 29 attached to the stove main body 11 generates, using a temperature difference obtained in the stove main body 11, drive power capable of driving all or part of electric drive means such as the exhaust fan 15, the blast fan 23, the fuel supply drum 25, the ignition heater 26, and the air supply fan 27, which are used in the pellet stove 10. Therefore, at least part of the electric drive means used in the pellet stove 10 uses thermoelectric power generated by the thermoelectric power generation module 29 which functions using the temperature of the pellet stove 10 itself obtained when the pellet stove 10 is in a heated state, as power for driving the electric drive means, that is, power for driving a motor and a heat source for an ignition heater.
One or a plurality of the thermoelectric power generation modules 29 necessary for a desired energy production are disposed, for example, on the outer surface of the stove main body 11 above the fuel supply path 13 in the adjacent space S between the stove main body 11 and the fuel storage 12 (as illustrated by way of example) or on the top portion of the stove main body 11, in such a manner that the hotside is closely adhered to the outer surface while the cool side is exposed to the adjacent space S (see Fig. 1). The thermoelectric power generated by the thermoelectric power generation module 29 is transferred to an electric accumulator 30 installed in the lower space inside the fuel storage 12 and stored therein.
The electric accumulator 30 is connected to an electric drive means to be driven by the output power from the electric accumulator 30, and the electric drive means is brought into conduction with the electric accumulator 30 through turning ON an operation switch (not shown) so as to be supplied with power from the electric accumulator 30 and driven. With the use of the electric accumulator 30, the ignition heater 26 for igniting the wood pellets P on the fire grate 21 and the drum-type pellet supply system 25 for sending the wood pellets P onto the fire grate 21 can be operated even when the thermoelectric power generation module 29 is yet to function at the start of operation of the pellet stove 10.
The thermoelectric power generation module 29 can be disposed anywhere as long as capable of ensuring a sufficient temperature difference enough to generate necessary power, between the hotside and the coolside of the thermoelectric power generation module 29. When a larger power is necessary, for example, a temperature difference between a combustion temperature inside the fire chamber 18 and an outdoor air temperature outside the building having the pellet stove 10 installed therein may be utilized. For this purpose, there are provided means for conducting the combustion temperature of the fire chamber 18 to the hotside and means for conducting the outdoor air temperature outside the building to the coolside.
Fig. 2 is an explanatory view illustrating an exemplary case where the thermoelectric power generation module utilizes the temperature difference between the combustion temperature and the outdoor air temperature. As illustrated in Fig. 2, a combustion temperature conductor (combustion temperature conducting means) 31 is installed inside the fire chamber 18, and an outdoor temperature conductor (outdoor temperature conducting means) 32 is installed outside the building having the pellet stove 10 installed therein. The combustion temperature conductor 31 and the outdoor temperature conductor 32 are both formed of members excellent in temperature conductivity, and the combustion temperature conductor 31 is disposed with the temperature detection end thereof in proximity to a combustion flame so that the pellet combustion temperature during the combustion of the wood pellets P is directly conducted while the outdoor temperature conductor 32 is disposed with the temperature detection end thereof exposed to external air so that the outdoor air temperature outside the building is directly conducted.
The combustion temperature conductor 31 is coupled to the hotside of the thermoelectric power generation module 29 and the outdoor temperature conductor 32 is coupled to the coolside of the thermoelectric power generation module 29, so that the pellet combustion temperature detected by the temperature detection end of the combustion temperature conductor 31 is conducted to the hotside while the outdoor side temperature detected by the temperature detection end of the outdoor temperature conductor 32 is conducted to the coolside. The combustion temperature conductor 31 and the outdoor temperature conductor 32 each may be used alone or in combination. When both are used in combination, the temperature difference becomes maximum.
Next, description is given of an operation of the pellet stove 10 configured as described above.
First, the lid 17 of the fuel storage 12 is opened to see the amount of the wood pellets P accumulated and stored in the hopper 16, and if necessary, the wood pellets P are additionally input from the fuel input port 12a so as to add the wood pellets P into the hopper 16.
Next, an operation switch (not shown) of the pellet stove 10 is turned ON, so as to start the operation of the pellet stove 10. Then, power is supplied from the electric accumulator 30, so that the exhaust fan 15 and the air supply fan 28 are brought into an operable state, together with the drum-type pellet supply system 25 and the ignition heater 26, where the drum-type pellet supply system 25 starts operating, the ignition heater 26 is brought into a heating state, and the exhaust fan 15 and the air supply fan 28 starts blowing air.
When the drum-type pellet supply system 25 starts operating, the wood pellets P in the hopper 16 are fed into the fire grate 21 through the fuel supply path 13 so as to be gathered on the fire grate 21. In this state, the ignition heater 26, which is in contact with the wood pellets P, is brought into a heated state, to thereby ignite the wood pellets P on the fire grate 21. At this time, the air supply fan 28 draws air into the lower space below the fire grate 21, to thereby supply air to the fire grate 21 from below.
After that, starting with a wood pellet P first ignited, a plurality of the wood pellets P gathered on the fire grate 21 are ignited, to thereby expand the combustion, which continues so as to maintain a stable combustion state. When the temperature inside the fire chamber 18 reaches a preset temperature, the blast fan 23 starts operating. Through the operation of the blast fan 23, air heated by the combustion of the wood pellets P in the fire chamber 19 is sent out from the hot air delivery chamber 22 toward the outside of the stove main body 11 through the blast port 22a.
Therefore, in the place where the pellet stove 10 is installed, heat generated along with the combustion of the wood pellets P is dissipated, as radiation heat from the stove main body 11, around the outside of the stove main body 11. In addition, heated air in the fire chamber 19 is sent out by the blast fan 23 through the blast port 22a toward the outside of the stove main body 11, with the result that a room in which the pellet stove 10 is installed can be efficiently heated.
It should be noted that the pellet stove 10 may use a screw-type pellet conveying system in place of the drum-type pellet supply system 25 in order to send the wood pellets P accumulated and stored in the fuel storage 12 to the fuel supply path 13.
Fig. 3 is a sectional explanatory view schematically illustrating a configuration of a combustion apparatus including a screw-type pellet conveying system. As illustrated in Fig. 3, the screw-type pellet conveying system 33 is formed of a rotating body having a spiral blade 33b continuously formed around a screw shaft 33a, and disposed as being inclined upward toward the fuel storage port 13b from the pellet discharge port 16a of the hopper 16 positioned below the fuel storage port 13b of the fuel supply path 13. With the use of the screw-type pellet conveying system 33, the pellet discharge port 16a can be positioned below the fuel storage port 13b (even at the bottom of the fuel storage 12 at the lowest), which can increase the amount of the wood pellets P that can be stored in the hopper 16 as compared to the case where the drum-type pellet supply system 25 is used.
The screw-type pellet conveying system 33 is, for example, motor driven to be axially rotated about the screw shaft 33a. Along with the rotation, a plurality of the wood pellets P discharged from the pellet discharge port 16a are received by the blade 33b below the pellet discharge port 16a, and the wood pellets P thus received are conveyed to the fuel storage port 13b so that the wood pellets P are caused to fall off the blade 33b at the fuel storage port 13b. The wood pellets P thus falling off make their way from the fuel storage port 13b to the fuel supply path 13, slide down the fuel supply path 13 along the inclination toward the fire chamber port 13, and are guided by the pellet guide 24 from the fire chamber port 13a so as to fall onto the fire grate 21. In this manner, the rotation dynamics of the screw-type pellet conveying system 33 allows the wood pellets P accumulated and stored in the fuel storage 12 to be sent along the fuel supply path 13 to the fire grate 21 installed inside the fire chamber 18.
As described above, power generated in the pellet stove 10 is capable of driving the drum-type pellet supply system 25 or the screw-type pellet conveying system 33 for supplying the wood pellets P to the fire grate 21, the air supply fan 28 for supplying air to the fire chamber 18, the exhaust fan 15 for air exhaustion, and the blast fan 23 for blowing air from the fire chamber 18. Further, the pellet stove 10 may also include a cleaning means for automatically cleaning the fire grate 21, and the cleaning means may also be driven by the power generated by the pellet stove 10. The automatic cleaning of the fire grate 21 removes, from the fire grate 21, remaining ash produced during the combustion, so as to allow continuous combustion in the fire chamber 18, to thereby allow 24-hour continuous operation of the pellet stove 10.
Further, the pellet stove 10 includes the electric accumulator 30, so as to provide power necessary for the initial operation of the pellet stove 10 and also to constantly perform stable operation of the thermoelectric power generation means used in the pellet stove 10 without being affected by fluctuation in the thermoelectric power generation resulting from the combustion state. Further, a 100V AC outlet may be provided in preparation for a power outage which may occur at the time of disaster, so that the pellet stove 10 can serve as a power source for supplying power to general electric appliances.
Alternatively, the stove main body 11 may be adapted to be capable of combusting firewood in the fire chamber 18, so that the pellet stove 10 may also be used as a wood stove.

(Second Embodiment)

Fig. 4 is an explanatory view schematically illustrating, in a longitudinal section, a pellet stove according to a second embodiment of the present invention, Fig. 5 is a partial explanatory view of a section taken along the line A-A of Fig. 4, Fig. 6 is a partial explanatory view of a section taken along the line B-B of Fig. 4, and Fig. 7 is a perspective explanatory view illustrating a configuration of the radiator of Fig. 4.
As illustrated in Figs. 4 to 6, in a pellet stove 40: the fuel storage 12 has a lower portion thereof integrally formed with the stove main body 11; a battery storage 41 is formed below the stove main body 11 and the fuel storage 12; and the thermoelectric power generation module 29 arranged in the fuel storage 12. The pellet stove 40 further includes a combustion temperature conductor 42 and a radiator 43 mounted to the thermoelectric power generation module 29. The pellet stove 40 has a fire chamber 44 which does not include the hot air delivery chamber 22 having the blast port 22a opened therein; and also includes: two fans, namely, a first blast fan 45 and a second blast fan 46, in place of the three fans, namely, the exhaust fan 15, the blast fan 23, and the air supply fan 28; and an air flow path 47 of the first blast fan 45. Other configurations are similar to those of the pellet stove (see Fig. 3) of the first embodiment.
The fuel storage 12 is integrally formed with the stove main body 11, below the partition wall 18 of the stove main body 11, and partitioned from the stove main body 11 by a wall 11a of the stove main body 11. The air supply port 27, which opens in a wall 11a partitioning between the stove main body 11 and fuel storage 12, communicates with the air flow path 47 disposed in the fuel storage 12, so as to serve as an opening of the air flow path 47 to the stove main body 11.
The battery storage 41 is integrally formed with the stove main body 11 and the fuel storage 12, with the stove main body 11 and the fuel storage 12 being placed thereon, and has an internal space, which is independent of the stove main body 11 and the fuel storage 12, for storing the electric accumulator 30.
The combustion temperature conductor 42 is formed of a plate-like member which is excellent in thermal conductivity, and surrounds, like a wall, the fire grate 21 of the fire chamber 44 as being in close contact with the lower surface of the fire grate 21 so that the combustion temperature can be efficiently conducted, while having both ends penetrating, as protrusions 42a, the wall 11a so as to be positioned inside the fuel storage 12 as being parallel to each other (see Fig. 6). Attached on each of the opposite surface sides of each of the protrusions 42a, 42a are, for example, two of the thermoelectric power generation modules 29 each having the radiator 43 mounted thereon, which are longitudinally arranged with the hotside (endothermic side) being in close contact therewith.
The combustion temperature conductor 42 conducts the temperature of the fire grate 21 heated through the combustion of the pellets P to the hotside (endothermic side) of the thermoelectric power generation module 29. When the combustion temperature in the fire grate 21 is so high that a temperature to be conducted via the combustion temperature conductor 42 to the thermoelectric power generation module 29 exceeds certain limits, for example, the combustion temperature conductor 42 may have a hole which is formed to penetrate through the front and back surface thereof, so that the temperature conducting capability of the combustion temperature conductor 42 may be adjusted to be low as necessary.
As illustrated in Fig. 7, the radiator 43 is formed by including, for example, three heat pipes 48 which are arranged side by side and incorporated in a radiator fin 49 with side surfaces of the heat pipes 48 in the longitudinal direction thereof being exposed, and is attached to the thermoelectric power generation module 29 in such a manner that the exposed surfaces of the heat pipes 48 are in close contact with the coolside (heat-radiation side) of the thermoelectric power generation module 29 in a vertical state where the heat pipes 48 are vertically arranged. The radiator 43 attached to the thermoelectric power generation module 29 has the heat pipes 48 and the radiator fin 49 protruded into the internal space of the battery storage 41 through the wall 41a partitioning the stove main body 11, the fuel storage 12, and the battery storage 41 (see Figs. 4 and 5).
The internal space of the battery storage 41, in which an approximately halves of the heat pipes 48 and the radiator fin 49 on the protruding side are positioned, is spaced apart from the fire chamber 44 across the space for storing the ash tray 20 below the fire grate 21, the space being partitioned by the partition wall 18 and the wall 11, and the internal space of the fuel storage 12, so that the combustion temperature is less likely to be conducted thereto. Therefore, a suitable environment is provided for bringing out the cooling function of the heat pipes 48 and the radiator fin 49, and the heat radiation effect of the radiator 43 can be effectively produced.
As described above, the thermoelectric power generation module 29 is disposed, via the combustion temperature conductor 42, inside the fuel storage 12 which is partitioned by the wall 11a from the fire chamber 44 in a combustion state, so that sufficient heating (endothermic) and cooling (heat-radiation) can be performed, to thereby allow efficient power generation. In other words, the thermoelectric power generation module 29 can be heated (absorb heat) by the combustion temperature via the combustion temperature conductor 42 disposed as being in contact with the fire grate 21 in a combustion state, while being disposed inside the fuel storage 12 which is partitioned by the wall 11a so as to be blocked off from the fire chamber 44 in a combustion state, so that the thermoelectric power generation module 29 can be cooled (dissipate heat) at a temperature in the fuel storage similar to the room temperature as an external temperature of the stove main body 11.
Further, the fuel storage 12 having the thermoelectric power generation module 29 disposed therein is partitioned by the wall 11a from the fire chamber 44 in a combustion state, and hence, a maximum temperature inside the fuel storage 12 may be set to be equal to or lower than the operating temperature limit which is low enough to prevent damage to the thermoelectric power generation module 29, to thereby stably ensure the use environment of the thermoelectric power generation module 29.
As illustrated in Figs. 4 to 6, the air flow path 47 is arranged between the radiators 43, 43 disposed as being opposed to the protrusions 42a, 42a of the combustion temperature conductor 42. The air flow path 47 has one end thereof communicating with the air supply path 27 which opens at the wall 11a of the stove main body 11, and has the other end thereof on the further inside of the fuel storage 12 than the radiators 43, 43. The first blast fan 45 is attached to the other end of the air flow path 47.
The first blast fan 45 is capable of blowing air toward the air supply port 27 via the air flow path 47, through the rotary operation of the fan. The air thus drawn inside the fuel storage 12 from the room where the pellet stove 40 is installed is fed into the fire grate 21 as combustion air. In this manner, the efficiency of combusting fuel (pellets P) on the fire grate 21 can be improved.
The second blast fan 46 is disposed in the vicinity above the radiator 43 in the fuel storage 12, that is, in the vicinity above the upper end of the radiator fin 49, and is capable of drawing in air inside the fuel storage 12, through the rotary operation of the fan, from the lower end side to the upper end side of the radiator fin through the radiator fin 49, as cooling air for the radiator fin 49 (see Fig. 5). Along with the operation of drawing in the cooling air, heated air around the stove main body 11 is discharged, together with air heated by the heat radiation effect of the radiator 43, as hot air to a room space where the pellet stove 40 is installed (see Fig. 5). In this manner, the radiator fin 49 can be cooled efficiently, and the room can be heated effectively by air heated along with the combustion in the fire chamber 44.
The second blast fan 46, which is disposed above the radiator 43, is not specifically limited thereto, and may be disposed below the radiator 43, that is, below the lower end of the radiator fin 49 inside the fuel storage 12. With this configuration, the drawing of cooling air can be similarly performed.
In the pellet stove 40 configured as described above, the temperature (for example, approximately 350°C) of the fire grate 21 in a combustion state, as well as a room temperature as an external temperature of the stove main body 11, is conducted to the thermoelectric power generation module 29 via the combustion temperature conductor 42, to thereby allow the thermoelectric power generation module 29 to perform power generation.
The thermoelectric power generation module 29 may be desirably installed at a point where a temperature difference of about 150°C to about 250°C can be obtained between the heating (endothermic) side and the cooling (heat-radiation) side. For example, under a condition where the heating (endothermic) side is about 280°C, the cooling (heat-radiation) side is about 30°C, and the temperature difference is about 250°C, an electric power of about 8V-24W can be supplied per one thermoelectric power generation module.
As described above, the combustion temperature conductor 42 for conducting the combustion temperature to the thermoelectric power generation module 29 is arranged on the periphery of the fire grate 29 which has a stable temperature and therefore allows easy control of temperature (see Figs. 4 to 6), so that a temperature of about 200°C can be reliably conducted to the thermoelectric power generation module 29 even in low-power operation setting with a smaller number of pellets P combusting, and the temperature of 200°C or higher can be reliably conducted in high-power operation with a larger number of pellets P combusting. In the above-mentioned embodiment, the heat of about 180°C to about 280°C is conducted to the heating (endothermic) side of the thermoelectric power generation module 29 through the combustion temperature conductor 42.
Further, the thermoelectric power generation module 29 is installed in the fuel storage 12 partitioned by the wall 11a from the fire chamber 44 in a combustion state (see Figs. 4, 6), and is mounted with the radiator 43 including the heat pipes 48 and the radiator fin 49 (see Figs. 4 to 7), so that the cooling effect on the cooling (heat-radiation) side can be increased. In addition, the power generated by the thermoelectric power generation module 29 is used to operate the second blast fan 46, to thereby increase the heat radiation effect of the radiator fin 49 so as to perform cooling on the cooling (heat-radiation) side with efficiency. As a result, the cooling (heat-radiation) side of the thermoelectric power generation module 29 may be cooled to 30°C or lower.
In other words, a temperature difference of about 150°C to about 250°C is necessary for allowing the power generation by the thermoelectric power generation module 29, and this temperature range is stably maintained at the periphery of the fire grate 21. For this reason, the combustion temperature conductor 42 is disposed on the periphery of the fire grate 21.
Power generated by the thermoelectric power generation module 29 is accumulated in the electric accumulator 30 of the battery storage 41 through a rectifier (not shown), and supplied as drive power, from the electric accumulator 30, to a drive means (for example, a drive motor) for driving the first blast fan 45 for combustion, the second blast fan 46 for cooling, and the screw-type pellet conveying system 33 for supplying fuel (pellets P), respectively.
Therefore, the number of the thermoelectric power generation modules 29 to be attached to the protrusions 42a of the combustion temperature conductor 42 may be adjusted, so as to ensure the electric power required as drive power (for example, an electric power of 96W at maximum with four modules). Further, power generated by the thermoelectric power generation module 29 is accumulated in the electric accumulator 30, so that the power can be stably supplied as drive power, in addition to being used for initial operation of the pellet stove 40 before starting combustion of the pellets.
The thermoelectric power generation module 29 may be attached, together with the radiator 43, to the chimney 14 for exhaust.
Fig. 8 is an explanatory diagram illustrating the chimney in transverse section, the chimney having the thermoelectric power generation modules mounted thereon. As illustrated in Fig. 8, the thermoelectric power generation modules 29 are each mounted via a mounting member 50 attached to the circumference of the chimney 14 at an arbitrary position in the height direction, the mounting member 50 having four planes intersecting with each other at right angles and surrounding the periphery of the chimney 14. Four of the thermoelectric power generation modules 29 in total are each mounted, for example, onto the four planes of the mounting member 50, respectively. The thermoelectric power generation modules 29 each have, for example, a combustion temperature conductor 51 formed of a bar-like member and the radiator 43 including the heat pipes 48 and the radiator fin 49, which are attached on the heating (endothermic) side and on the cooling (heat-radiation) side, respectively.
The combustion temperature conductor 51 has a protruding end protruded into the inner surface of the chimney substantially at right angle, which is positioned in the internal space of the chimney 14 serving as a smoke exhausting path, and the radiator 43 has the radiator fin 49 exposed outside the chimney. The thermoelectric power generation modules 29 each receive, on the heating (endothermic) side, the temperature of the exhaust smoke passing through inside the chimney 14, the temperature being conducted through the combustion temperature conductor 51, and also receives, on the cooling (heat-radiation) side, the temperature (a room temperature or an outdoor air temperature) conducted from a position where the chimney 14 is positioned, so that the thermoelectric power generation module 29 generates power.
The thermoelectric power generation module 29 may be installed at any point in the height direction of the chimney 14, as long as capable of obtaining a temperature difference between the heating (endothermic) side and the cooling (heat-radiation) side that is sufficient enough to allow the thermoelectric power generation module 29 to generate a required power.
In other words, the combustion temperature conductor 42 and the combustion temperature conductor 51 function as a combustion temperature conducting means for conducting, to a heater of the thermoelectric power generation module, heat generated along with the combustion in the combustion chamber.
As described above, the pellet stove 40 is also capable producing the same operation and effect as the pellet stove 10 of the first embodiment. That is, thermoelectric power generated in the pellet stove 40 may be used as a drive force to drive at least one of the drive means (for example, drive motors) of the first blast fan 45, the second blast fan 46, and the screw-type pellet conveying system 33, which serve as the electric drive means. Further, with the electric accumulator 30 thus provided, power necessary for the initial operation of the pellet stove 10 can be supplied.
It should be noted that, in the above-mentioned description, the pellet stoves 10, 40 are described by way of example of a combustion apparatus. However, the combustion apparatus is not limited to the pellet stoves 10, 40, and may be applied to a combustion apparatus such as a boiler or a water heater including a combustion function and a thermoelectric power generation module similar to those of the above-mentioned pellet stove. Specifically, at least part of the electric drive means used in a combustion apparatus including a boiler or a water heater may be driven by using a thermoelectric power generated by a thermoelectric power generation module which functions based on the temperature of its own when the combustion apparatus is in a heated state.

(Third Embodiment)

Fig. 9 is an explanatory diagram schematically illustrating a method of conducting heat to a thermoelectric power generation module according to a third embodiment of the present invention. As illustrated in Fig. 9, the thermoelectric power generation modules 29 are mounted on the periphery of a heat conduction pipe (combustion temperature conducting means) 53 serving as a feeding path of water vapor (saturated water vapor) generated in a boiler (combustion apparatus) 52, to thereby conduct heat generated along the combustion of, for example, a large-scale combustion apparatus used in a factory or the like, to the thermoelectric power generation modules 29.
The boiler 52 includes a water vapor generator 54 for generating water vapor, and, for example, water may be supplied to the water vapor generator 54 so that the water thus supplied can be stored and held therein. The water stored and held in the water vapor generator 54 is heated along with the combustion in the combustion chamber (furnace) (not shown), to thereby generate water vapor. The wood pellets P, which are renewable energy originating from biomass (botanical resources), are used as fuel (combustion material) to combust in the combustion chamber, but the present invention is not limited thereto and different fuel may also be used.
The heat conduction pipe 53 communicates with the water vapor generator 54 of the boiler 52, and water vapor (saturated water vapor) generated in the water vapor generator 54 is heated under pressure when passing through inside the pipe within the boiler 52 so as to be changed to saturated water vapor or superheated water vapor of a predetermined temperature (of about 200°C to about 300°C).
Here, the term "saturated water vapor" refers to water vapor evaporated at a boiling point, and the term "superheated water vapor" refers to steam obtained by heating saturated water vapor under a predetermined pressure.
A saturation temperature of, for example, 280°C can be obtained under gauge pressure of 6.32 Mpa. A necessary temperature can be obtained through pressure control, and therefore, the amount of water to be supplied to the water vapor generator 54 of the boiler 52 may be varied to thereby adjust the temperature of saturated water vapor or superheated water vapor to be generated.
The heat conduction pipe 53 has, in a portion outside the boiler 52, the thermoelectric power generation module 29 mounted thereon having the heating (endothermic) side of the thermoelectric power generation module 29 brought into contact therewith. When saturated water vapor or superheated water vapor generated by using high heat of the boiler 52 passes through, inside the pipe, the position where the thermoelectric power generation module 29 is mounted, the heat of the superheated water vapor or of the saturated water vapor is conducted to the heating (endothermic) side of the thermoelectric power generation module 29.
On the cooling (heat-radiation) side of the thermoelectric power generation module 29, there is attached a cooling device (not shown) such as the radiator 43 including the heat pipes 48 and the radiator fin 49.
As described above, when saturated water vapor or superheated water vapor of a predetermined temperature is used to conduct heat to the thermoelectric power generation module 29, substantially the same temperature can be conducted to the heating (endothermic) side of each of a plurality (three, for example) of the thermoelectric power generation modules 29 disposed in the longitudinal direction of the heat conduction pipe 53, by taking the advantage of the property of water vapor for allowing uniform conduction of heat. Power generated by the thermoelectric power generation modules 29 under the action of heat conducted thereto is accumulated in the electric accumulator 30, and supplied, from the electric accumulator 30, as power necessary for the combustion in the boiler 52 (drive power for a fuel supply system, an air supply/exhaust fan, and a cooling fan).
After passing through the positions in the heat conduction pipe 53 where the thermoelectric power generation modules 29 are mounted, saturated water vapor or superheated water vapor used for heat conduction may be subjected to heat dissipation and cooling to be devolatilized, so as to be reused as being supplied to the water vapor generator 54 of the boiler 52. Alternatively, the water vapor may be directly discharged in a room so as to be used for heating or drying of the room.
It should be noted that the present invention is not limited to the case where the saturated water vapor or superheated water vapor of a predetermined temperature is generated through direct heating by a heat source (not shown) of the boiler 52, and the water vapor may be generated through heating by exhaust air from the boiler 52.
Fig. 10 is an explanatory diagram schematically illustrating another method of conducting heat to the thermoelectric power generation module. As illustrated in Fig. 10, the water vapor generator 54 and a heat conduction pipe (combustion temperature conducting means) 55 for conveying saturated water vapor or superheated water vapor of a predetermined temperature are arranged inside an exhaust pipe 52a serving as an exhaust air path of the boiler (combustion apparatus) 52, in which the heat conduction pipe 55 is configured in a spiral form in the vicinity of a portion communicating with the water vapor generator 54 and has the thermoelectric power generation module 29 mounted thereon in a portion outside the exhaust pipe 52a. Other configurations and effects are similar to those of the case where the water vapor generator 54 is provided inside the boiler 52 (see Fig. 9).
The water vapor generator 54 disposed inside the exhaust pipe 52a is, for example, supplied with water, and the water thus stored in the water vapor generator 54 is heated by air discharged from the boiler 52 and passing through the exhaust pipe 52a, to thereby generate water vapor. When the water vapor thus generated is heated under pressure when passing through inside the exhaust pipe 52a within the heat conduction pipe 55, so as to be changed to saturated water vapor or superheated water vapor of a predetermined temperature (of about 200°C to about 300°C). With the heat conduction pipe 55 configured in a spiral shape, the heat conduction pipe 55 can be exposed to heat of the exhaust air from the boiler 52 along a long distance without losing the high temperature thereof, so that water vapor passing through the pipe can be reliably heated with efficiency.
When saturated water vapor or superheated water vapor generated by using exhaust air from the boiler 52 passes through, inside the heat conduction pipe 55, the position where the thermoelectric power generation module 29 is mounted, the heat of the superheated water vapor or of the saturated water vapor is conducted to the heating (endothermic) side of the thermoelectric power generation module 29.
As described above, a combustion apparatus including the pellet stoves 10, 40, the boiler 52, or a water heater, is capable of generating power necessary for the combustion in the combustion apparatus in the combustion apparatus in itself. In other words, at least part of the electric drive means used in the combustion apparatus can be driven by using, as drive power, thermoelectric power generated by a thermoelectric power generation module which functions using a combustion temperature generated by the combustion apparatus in itself when the combustion apparatus in a combustion state.

INDUSTRIAL APPLICABILITY

According to the present invention, fuel can be reliably supplied without using a commercial power source which stops power supply due a power outage or the like, and further, the present invention is capable of contributing to mitigating global warming in terms of fuel supply. Therefore, the present invention is suitably applied to a combustion apparatus having a combustion chamber, in particular, a combustion apparatus which uses wood pellets as a combustion material to combust in a combustion chamber.

DESCRIPTION OF SYMBOLS

10, 40: pellet stove
11: stove main body
11a: wall
12: fuel storage
12a: fuel input port
13: fuel supply path
13a: fire chamber port
13b: fuel storage port
14: chimney
15: exhaust fan
16: hopper
16a: pellet discharge port
17: lid
18: partition wall
19, 44: fire chamber
20: ash tray
21: fire grate
22: hot air delivery chamber
22a: blast port
23: blast fan
24: pellet guide
25: drum-type pellet supply system
25a: drum
25b: receiver
26: ignition heater
27: air supply port
28: air supply fan
29: thermoelectric power generation module
30: electric accumulator
31: combustion temperature conductor
32: outdoor temperature conductor
33: the screw-type pellet conveying system
33a: screw shaft
33b: blade
41: battery storage
41a: wall
42, 51: combustion temperature conductor
42a: protrusion
43: radiator
45: first blast fan
46: second blast fan
47: air flow path
48: heat pipe
49: radiator fin
50: mounting member
52: boiler
52a: exhaust pipe
53, 55: heat conduction pipe
54: water vapor generator
P: wood pellet
S: adjacent space

Claims

A combustion apparatus, comprising:
a combustion chamber for combusting a fuel material;

a thermoelectric power generation module for generating power based on a temperature difference caused by heating with a combustion temperature generated along with the combustion in the combustion chamber and by cooling with an external temperature outside the combustion chamber; and

an electric drive means which operates using, as a drive force, thermoelectric power generated by the thermoelectric power generation module.
The combustion apparatus according to claim 1, further comprising an electric storage device for storing electricity using thermoelectric power generated by the thermoelectric power generation module, wherein the electric storage device supplies power that is to be used as a drive force for driving the electric drive means.
The combustion apparatus according to claim 1 or 2, wherein the electric drive means comprises at least one of a combustion material supply system for supplying the combustion material from a combustion material storage to the combustion chamber, a fan for supplying air to or exhausting air from the combustion chamber, and a fan for sending out air heated in the combustion chamber.
The combustion apparatus according to any one of claims 1 to 3, further comprising a combustion temperature conducting means for conducting heat generated along with the combustion in the combustion chamber, to a heater of the thermoelectric power generation module.
The combustion apparatus according to any one of claims 1 to 4, wherein the combustion material comprises wood pellets.