JP2006207938A - Pulverulent fuel burner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pulverulent fuel burner using pulverulent fuel such as pulverized biomass fuel, and capable of achieving positive ignition and a high burning rate. <P>SOLUTION: It is composed such that a tubular first combustion chamber 1 and a second combustion chamber 2 are serially connected, swirling flame is formed in the first combustion chamber by blowing air and supporting fuel into the combustion chamber from a nozzle 6 provided facing a tangential direction of an inner wall face 1b, swirling a mixture of the air and the supporting gas, and igniting the mixture by an ignition plug 8, and combustion is carried out in the second combustion chamber 2 by blowing air and the pulverulent fuel into the combustion chamber from a nozzle 8 provided facing a tangential direction of an inner wall face 3b or in a slanted direction with respect to the tangential direction, swirling oxygen containing gas and the pulverulent fuel, and supplying the pulverulent fuel to the swirling flame moving from the first combustion chamber to the second combustion chamber. It is also favorable to blow in the pulverulent fuel along with air from a nozzle provided on a closed end face of the first combustion chamber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pulverized fuel burner using pulverized fuel such as finely pulverized biomass fuel as fuel for the burner.

  Biomass fuel produced from biomass such as wood from thinned wood and waste from construction sites is attracting attention as a renewable fuel. And as a conventional combustion method of biomass fuel, as shown in Patent Document 1 below, biomass fuel molded into pellets is supplied to a grate with a screw feeder and burned on the grate, As shown in Patent Document 2 below, there is a system in which combustible powder (powder fuel) obtained by finely pulverizing biomass or plastic is supplied to a burner in the axial direction while being swirled and burned.

  In addition, the following patent document 3 discloses a tubular flame burner using liquid fuel.

JP 2004-191016 A JP 2004-1000096 A Japanese Patent Application Laid-Open No. 11-281018

  However, since the method of the above-mentioned Patent Document 1 is grate combustion, the combustion load is small, and it is often used for small combustors such as household stoves, but it is not suitable for large high-load combustion furnaces. There are challenges. The method of the above-mentioned Patent Document 2 can be used when using a highly volatile high-calorie fuel such as plastic, but when using a low-calorie fuel such as biomass fuel, the flame temperature is low and the flame blows off at a high load. As a result, there is a problem that the flame holding performance is low, and there is a problem that unburned matter is often generated at high load. Biomass fuel is a fuel with a high water content (4-15%) and low calories (10-20 MJ / kg). In addition, the tubular flame burner of Patent Document 3 has excellent features such as high-load combustion and a wide adjustment range of the combustion amount, but it is not powdered fuel such as biomass fuel, but kerosene or light oil. Liquid fuel such as is used.

  Therefore, in view of the above circumstances, the present invention uses a powdered fuel burner that uses powdered fuel such as finely pulverized biomass fuel and can achieve reliable ignition (stable combustion) and a high combustion rate. The issue is to provide.

A powdery fuel burner according to a first aspect of the present invention that solves the above-described problem connects a tubular first combustion chamber and a tubular second combustion chamber in series, and closes an end surface on the first combustion chamber side, 2 Opening the end face of the combustion chamber side,
In the first combustion chamber, oxygen-containing gas and auxiliary fuel are introduced into the first combustion chamber from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. And the mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber, and the mixture is ignited by an ignition plug provided in the first combustion chamber. To form a swirl flame,
In the second combustion chamber, from one or a plurality of nozzles provided in the second combustion chamber toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas and the pulverized fuel are swirled in the second combustion chamber by blowing the oxygen-containing gas and the pulverized fuel into the second combustion chamber, and the pulverized fuel is turned into the first combustion chamber. It is configured to supply and burn the swirl flame that has moved from the chamber to the second combustion chamber.

The pulverized fuel burner of the second invention is the pulverized fuel burner of the first invention.
The nozzle provided in the second combustion chamber is set at an angle within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber.

The powdery fuel burner of the third invention connects the tubular first combustion chamber and the tubular second combustion chamber in series, and closes the end on the first combustion chamber side, while the second combustion chamber The side end is open,
In the first combustion chamber, oxygen-containing gas and auxiliary fuel are introduced into the first combustion chamber from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. And the mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber, and the mixture is ignited by an ignition plug provided in the first combustion chamber. To form a swirl flame,
In the second combustion chamber, from one or a plurality of nozzles provided in the second combustion chamber toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas is swirled in the second combustion chamber by blowing only the oxygen-containing gas into the second combustion chamber, and from one or more other nozzles provided in the second combustion chamber, The pulverized fuel is blown into the second combustion chamber together with the oxygen-containing gas so that the pulverized fuel is supplied to the swirling flame that has moved from the first combustion chamber to the second combustion chamber and burned. It is characterized by that.

Moreover, the pulverized fuel burner of the fourth invention is the pulverized fuel burner of any of the first to third inventions,
The first combustion chamber and the second combustion chamber are connected so that their pipe axes are on the same axis.

Moreover, the pulverized fuel burner of the fifth invention is the pulverized fuel burner of any of the first to fourth inventions,
An inner diameter of the second combustion chamber is larger than an inner diameter of the first combustion chamber;
The amount of the oxygen-containing gas blown into the second combustion chamber is larger than the amount of the oxygen-containing gas blown into the first combustion chamber.

The pulverized fuel burner of the sixth invention is the pulverized fuel burner of the fifth invention,
The first combustion chamber and the second combustion chamber are connected in series via a connection pipe having one end connected to the first combustion chamber and the other end connected to the second combustion chamber.
A taper in which the inner wall surface of the connecting pipe gradually increases from the one end having the same inner diameter as the first combustion chamber toward the other end having the same inner diameter as the second combustion chamber. It is characterized by the shape of the surface.

Moreover, the pulverized fuel burner of the seventh invention is the pulverized fuel burner of any of the first to sixth inventions,
The powdery fuel is blown into the first combustion chamber together with the oxygen-containing gas from the nozzle provided on the end face of the first combustion chamber, so that the powdery fuel is supplied to the swirling flame and burned. It is characterized by.

The powdery fuel burner of the eighth invention has a tubular combustion chamber in which one end face is closed and the other end face is opened,
In the combustion chamber, oxygen-containing gas and auxiliary fuel are blown into the combustion chamber from one or more nozzles provided in the combustion chamber toward the tangential direction of the inner wall surface of the combustion chamber. A mixture of gas and auxiliary combustion fuel is swirled in the combustion chamber, and the mixture is ignited by an ignition plug provided in the combustion chamber to form a swirling flame in the combustion chamber, and one of the combustion chambers The powdery fuel is blown into the combustion chamber together with the oxygen-containing gas from a nozzle provided on the end face of the gas, so that the powdery fuel is supplied to the swirling flame and burned.

The pulverized fuel burner of the ninth invention is the pulverized fuel burner of the seventh or eighth invention,
The inner wall surface of the nozzle provided on the end surface on the first combustion chamber side is a tapered surface whose inner diameter gradually increases so as to approach the end surface of the first combustion chamber, or one end surface of the combustion chamber The inner wall surface of the nozzle provided in the above is a tapered surface whose inner diameter gradually increases so as to approach one end surface of the combustion chamber.

Moreover, the pulverized fuel burner of the tenth invention is the pulverized fuel burner of any of the first to ninth inventions,
The first combustion chamber and the second combustion chamber are installed so that the tube axis directions are vertical.

Moreover, the pulverized fuel burner of the eleventh invention is the pulverized fuel burner of any of the first to tenth inventions,
The pulverized fuel burner, wherein the pulverized fuel is a pulverized biomass fuel.

  According to the pulverized fuel burner of the first invention, in the first combustion chamber, the first combustion is performed from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. The air-fuel mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber by blowing the oxygen-containing gas and the auxiliary fuel into the chamber, and the air-fuel mixture is ignited by an ignition plug provided in the first combustion chamber. A swirling flame is formed in the first combustion chamber, and in the second combustion chamber, the second combustion chamber is directed toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas and the pulverized fuel are swirled and supplied in the second combustion chamber by blowing the oxygen-containing gas and the pulverized fuel into the second combustion chamber from one or more nozzles provided. The flame formed by the combustion of the auxiliary combustion fuel Only along the inner wall surface of the combustion chamber flame is formed inside the expansion the combustion chamber wall surface rises while rotating. Finely pulverized fuel such as biomass also rises while rotating along the inner wall surface of the combustion chamber in order to receive a strong swirl. The powdery fuel is attracted to the surface of the inner wall surface by centrifugal force, enters the inside of the flame zone formed by the auxiliary fuel, and rises while accompanying the flame zone. This enables reliable ignition and stable combustion even in a low-grade powdery fuel such as a biomass fuel having a low calorie and a high water content, and enables flame holding in a relatively wide air ratio range.

  According to the pulverized fuel burner of the second aspect of the invention, the nozzle provided in the second combustion chamber is set at an angle within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber. The strength of swirling of the pulverized fuel becomes variable, and by setting the angle according to the particle size of the target pulverized fuel, the pulverized fuel can surely enter the swirling flame and be ignited reliably.

  According to the pulverized fuel burner of the third invention, in the first combustion chamber, the first combustion is performed from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. The air-fuel mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber by blowing the oxygen-containing gas and the auxiliary fuel into the chamber, and the air-fuel mixture is ignited by an ignition plug provided in the first combustion chamber. A swirling flame is formed in the first combustion chamber, and in the second combustion chamber, the second combustion chamber is directed toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas is swirled in the second combustion chamber by blowing only the oxygen-containing gas into the second combustion chamber from one or a plurality of nozzles provided, and the other one provided in the second combustion chamber Alternatively, powdered fuel is supplied into the second combustion chamber from a plurality of nozzles. Since the powdered fuel is supplied to the swirl flame that has been moved from the first combustion chamber to the second combustion chamber by being blown together with the element-containing gas and burned, the powdered fuel has a low calorie and a high water content. Even if low quality powdery fuel such as biomass fuel is used, reliable ignition and stable combustion are possible, and flame holding in a relatively wide air ratio range is also possible. Moreover, by providing a nozzle for blowing only oxygen-containing gas separately from the nozzle for blowing powdered fuel, a nozzle for blowing powdered fuel separately from the nozzle for blowing only oxygen-containing gas is provided. Since the mounting angle can be set arbitrarily, the swirling strength of the powdered fuel to be supplied is variable, and the swirling flame is set by changing the angle according to the particle size of the target powdered fuel. It is possible to ignite surely by letting it enter.

  According to the pulverized fuel burner of the fourth aspect of the invention, the first combustion chamber and the second combustion chamber are connected so that the mutual pipe axes are on the same axis, and therefore when the mutual pipe axes are shifted. In comparison, the swirl flame formed by the auxiliary fuel can be more reliably guided from the first combustion chamber to the second combustion chamber without being attenuated.

  According to the pulverized fuel burner of the fifth invention, the inner diameter of the second combustion chamber is made larger than the inner diameter of the first combustion chamber, and the amount of oxygen-containing gas blown into the second combustion chamber is blown into the first combustion chamber. Since the amount of oxygen-containing gas is larger than the amount of oxygen-containing gas, a large amount of powdery fuel can be burned with a relatively small amount of swirling flame of auxiliary combustion fuel to achieve high load combustion.

  According to the pulverized fuel burner of the sixth aspect of the invention, the first combustion chamber and the second combustion chamber are connected in series via a connecting pipe having one end connected to the first combustion chamber and the other end connected to the second combustion chamber. And the inner wall surface of the connection pipe has an inner diameter as it goes from the one end having the same inner diameter as the inner diameter of the first combustion chamber toward the other end having the same inner diameter as the inner diameter of the second combustion chamber. Since the tapered surface gradually increases, the swirl flame formed by the auxiliary fuel is attenuated as compared with the case where the inner diameter changes stepwise at the connection between the first combustion chamber and the second combustion chamber. Therefore, the first combustion chamber can be guided to the second combustion chamber more reliably.

  According to the pulverized fuel burner of the seventh invention, the pulverized fuel is formed with the auxiliary fuel by blowing the pulverized fuel together with the oxygen-containing gas into the first combustion chamber from the nozzle provided on the end face of the first combustion chamber. The powdery fuel is supplied to the base of the swirl flame formed by the auxiliary fuel, and the heat generated by the heat radiation from the swirl flame and the inner wall surface is powdered. Since the fuel is supplied to the fuel, reliable ignition and stable flame holding are possible even when a low-grade powdery fuel such as a biomass fuel having a low calorie and a high water content is used as the powdery fuel.

  According to the pulverized fuel burner of the eighth invention, in the combustion chamber, oxygen-containing gas and auxiliary fuel are introduced into the combustion chamber from one or a plurality of nozzles provided in the combustion chamber toward the tangential direction of the inner wall surface of the combustion chamber. And swirling the mixture of the oxygen-containing gas and the auxiliary fuel in the combustion chamber and igniting the mixture with an ignition plug provided in the combustion chamber to form a swirling flame in the combustion chamber, and Since the powdery fuel is blown into the combustion chamber together with the oxygen-containing gas from the nozzle provided on one end face of the combustion chamber, the powdery fuel is supplied to the swirling flame and burned, so it is formed by the auxiliary fuel. The powdered fuel is supplied to the base of the swirling flame and the heat generated by the heat radiation from the swirling flame and the inner wall surface is supplied to the powdered fuel. Even using a low-grade powdered fuel such as scan fuel, it is possible to reliably ignite a stable flame holding.

  According to the pulverized fuel burner of the ninth aspect of the invention, the inner wall surface of the nozzle provided on the end face on the first combustion chamber side is a tapered face whose inner diameter gradually increases as it approaches the end face of the first combustion chamber. Alternatively, since the inner wall surface of the nozzle provided on one end surface of the combustion chamber is a tapered surface whose inner diameter gradually increases so as to approach one end surface of the combustion chamber, the first combustion chamber, Alternatively, the pulverized fuel blown in with the air into the combustion chamber spreads sufficiently in the first combustion chamber or the combustion chamber without peeling along the inner wall surface, so that the swirl flame formed by the auxiliary fuel is surely The powdered fuel can be more reliably ignited and stably held.

  According to the pulverized fuel burner of the tenth invention, since the tube axis directions of the first combustion chamber and the second combustion chamber are set in the vertical direction, even if the unburned pulverized fuel falls due to gravity, Because the circulating flow of unburned powdery fuel is formed in the vertical direction by being blown up again by the swirling flame or air rising from below, the residence time of the powdered fuel in the combustion chamber is extended. Thus, stable combustion is possible even with a relatively coarse powdery fuel.

  According to the pulverized fuel burner of the eleventh aspect of the invention, the pulverized fuel is obtained by finely pulverizing biomass fuel. Therefore, the pulverized fuel burner is finely pulverized by obtaining the effects of the first to tenth aspects of the invention. A powdery fuel burner suitable as a burner for biomass fuel can be realized.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The pulverized fuel burner of the present invention can be widely used, for example, a burner for a rotary kiln, a burner for a direct reduction furnace, or a burner for a combustion furnace.

<Embodiment 1>
1A is a side view of a pulverized fuel burner according to Embodiment 1 of the present invention, FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A, and FIG. FIG. 1A is a cross-sectional view taken along line BB in FIG. 1A, and FIG. 1D is a cross-sectional view taken along line CC in FIG.

  As shown in FIGS. 1 (a) to 1 (d), the pulverized fuel burner of Embodiment 1 is a tubular (cylindrical) first combustion chamber 1 and a tubular (cylindrical) second combustion chamber. 2, and the first combustion chamber 1 and the first combustion chamber 2 are connected in series via a connecting pipe 3. The end face 4 on the first combustion chamber 1 side is closed, while the end face 5 on the second combustion chamber 2 side is open. The first combustion chamber 1 and the second combustion chamber 2 are connected so that their mutual pipe axes (center axes) are on the same axis. Of course, the pipe axis of the connecting pipe 3 is also on the same axis as the pipe axes of the first combustion chamber 1 and the second combustion chamber 2.

  Moreover, this powdery fuel burner is installed so that the tube axis direction of the 1st combustion chamber 1 and the 2nd combustion chamber 2 may turn into a perpendicular direction. However, the present invention is not necessarily limited to this, and the present powder fuel burner may be installed so that the tube axis directions of the first combustion chamber 1 and the second combustion chamber 2 are horizontal.

  Further, the inner diameter of the second combustion chamber 2 is larger than the inner diameter of the inner diameter of the first combustion chamber 1. This is because the amount of air blown into the second combustion chamber 2 in order to burn a large amount of pulverized fuel in the second combustion chamber 2 is made larger than the amount of air blown into the first combustion chamber 1 ( Details will be described later). In other words, it is for realizing high load combustion by burning as much powdered fuel as possible with a swirling flame (described later in detail) formed by a relatively small amount of auxiliary combustion fuel. In the illustrated example, the inner diameter of the second combustion chamber 2 is about three times the inner diameter of the first combustion chamber 1. The specific internal diameter of the second combustion chamber 2 is determined according to the specific amount of pulverized fuel injected into the second combustion chamber 2 and the amount of pulverized fuel injected. It is appropriately set according to the amount of typical air (oxygen-containing gas) blown.

The connection pipe 3 has one end (lower end) connected to the first combustion chamber 1 and the other end (upper end) connected to the second combustion chamber 2. The inner wall surface 3 a of the connecting pipe 3 has an inner diameter that increases from the one end having the same inner diameter as the first combustion chamber 1 toward the other end having the same inner diameter as the second combustion chamber 2. It has a tapered surface that gradually increases. The angle θ ₁ of the inner wall surface 3a with respect to the tube axis direction (vertical direction) of the combustion chambers 1 and 2 is an angle at which the mixture of air and auxiliary fuel (which will be described later in detail) flowing in the connecting pipe 3 does not separate from the inner wall surface 3a (for example 5 to 10 degrees). Such a specific value of the angle θ ₁ can be appropriately set theoretically or experimentally.

  Note that the connection between the first combustion chamber 1 and the second combustion chamber 2 is not necessarily limited to the case where the first combustion chamber 1 and the second combustion chamber 2 are connected via the tapered connection pipe 3, and the first combustion chamber 1 and the second combustion chamber 2 are not limited to the first combustion chamber 1 and second combustion chamber 2. The 1st combustion chamber 1 and the 2nd combustion chamber 2 may be directly connected, and an internal diameter may change in steps at both connection parts.

  Two nozzles 6 are provided on the side surface (circumferential surface) of the first combustion chamber 1. These nozzles 6 are for injecting into the first combustion chamber 1 a premixed mixture of auxiliary fuel and air sent from an auxiliary fuel supply device (not shown). As the auxiliary fuel, gas fuel such as city gas or LPG having good ignitability is used. A long slit-shaped hole 1a is formed in the circumferential surface (side surface) of the first combustion chamber 1 along the tube axis direction, and the tip end portion 6a of the nozzle 6 is connected to the peripheral portion of the hole 1a. . Further, the two nozzles 6 and the hole 1a are provided at the same position in the tube axis direction on the peripheral surface of the first combustion chamber 1, and are in a line-symmetrical positional relationship with respect to the tube axis. In addition, although it is desirable to provide two nozzles 6 in the first combustion chamber 2 as in the illustrated example, the present invention is not necessarily limited thereto, and one or three or more nozzles 6 may be provided in the first combustion chamber 2.

In addition, the angle θ _{2 of} the nozzle 6 with respect to the radial direction of the first combustion chamber 1 is 90 degrees. That is, the nozzle 6 is provided in the first combustion chamber 1 in a state of being directed in the tangential direction of the inner wall surface 1 b of the first combustion chamber 1. Note that the tip ends of the two nozzles 6 are both directed in the same circumferential direction (counterclockwise direction in the illustrated example).

  Accordingly, when an air-fuel mixture of auxiliary combustion fuel and air is blown into the first combustion chamber 1 from these nozzles 6 as indicated by arrows in FIG. 1 (d), the inner combustion chamber 1 is moved along the inner wall surface 1 b. A swirling flow of the air-fuel mixture is formed. The nozzle 6 has a tip 6a that is long and flat along the tube axis direction of the first combustion chamber 1 and has a reduced opening area. Can be blown at high speed. An ignition plug 8 is provided on the side surface of the first combustion chamber 1 in the vicinity of the nozzle 6, and the air-fuel mixture blown into the first combustion chamber 1 is ignited by the ignition plug 8. ing.

  On the other hand, two nozzles 7 are provided on the side surface (circumferential surface) of the second combustion chamber 2. These nozzles 7 are for blowing a premixed mixture of pulverized fuel and air sent from a pulverized fuel supply device (not shown) into the second combustion chamber 2. As the pulverized fuel, various pulverized fuels can be used in addition to the finely pulverized biomass fuel.

  Two slit-like holes 2a are formed in the circumferential surface (side surface) of the second combustion chamber 2 along the tube axis direction, and the tip 7a of the nozzle 7 is connected to the peripheral edge of these holes 2a. Has been. Further, the two nozzles 7 and the hole 2a are provided at the same position in the tube axis direction on the peripheral surface of the second combustion chamber 2, and are in a line symmetric positional relationship with respect to the tube axis. In addition, although it is desirable to provide two nozzles 7 in the second combustion chamber 2 as in the illustrated example, the present invention is not necessarily limited to this, and one or three or more nozzles 7 may be provided in the second combustion chamber 2.

The angle θ ₃ of the nozzle 7 with respect to the radial direction of the second combustion chamber 2 is 90 degrees. That is, the nozzle 7 is provided in the second combustion chamber 2 in a state in which it is directed in the tangential direction of the inner wall surface 2 b of the second combustion chamber 2. The two nozzles 7 are both directed at the tip side in the same circumferential direction (counterclockwise direction in the illustrated example). Therefore, when pulverized fuel and air are blown into the second combustion chamber 2 from these nozzles 7 as indicated by arrows in FIG. 1B, the second combustion chamber 2 is moved along the inner wall surface 2b. A swirling flow of air and the pulverized fuel is formed. The nozzle 7 has a flat shape in which the tip 7a is long along the tube axis direction of the second combustion chamber 2 and its opening area is reduced, so that the air and the pulverized fuel can be reliably supplied. It is possible to blow in the tangential direction at high speed.

The attachment of the nozzle 7 is not necessarily limited to the case in which the nozzle 7 is directed in the tangential direction. The nozzle 7 is attached to the tangential direction in order to ensure that the powdery fuel enters the swirling flame 11 (tubular flame zone). You may make it attach toward the direction which inclines. That is, in order to form a swirl flow of air, it is desirable to attach the nozzle 7 toward the tangential direction, but in order to ensure that the pulverized fuel enters the swirl flame 11, the nozzle 7 is inclined with respect to the tangential direction. It may be better to attach the nozzle 7 in the direction. In this case, the attachment angle (blowing angle) of the nozzle 7 is 45 degrees (θ ₄ ) with respect to the radial direction of the second combustion chamber 2 as shown by a one-dot chain line in FIG. It is appropriate to set the angle within a range up to an angle of 90 degrees (θ ₃ ) (range of 45 to 90 degrees). Note that the specific angle to be set is determined in consideration of the passage time of the swirl flame 11 of the pulverized fuel according to the particle size of the pulverized fuel, for example, when the particle size is relatively small Is an angle close to 90 degrees, and an angle close to 45 degrees when the particle size is relatively large.

  From the above, the following effects can be obtained in the pulverized fuel burner of the first embodiment.

  That is, according to the first embodiment, in the first combustion chamber 1, the first combustion is performed from the nozzle 6 provided in the first combustion chamber 1 toward the tangential direction of the inner wall surface 1 b of the first combustion chamber 1. When a mixture of air and auxiliary fuel is blown into the chamber 1, the mixture turns in the first combustion chamber 1. For this reason, when the air-fuel mixture is ignited by the spark plug 8, the flame formed by the combustion of the auxiliary combustion fuel of the air-fuel mixture is subjected to a strong swirl. A swirl flame 11 swirling along 1b is formed. The swirling flame 11 rises (moves) while swirling, and reaches the second combustion chamber 2 through the connection pipe 3.

  At this time, since the first combustion chamber 1 and the second combustion chamber 2 are connected so that their tube axes are on the same axis, the swirl flame 11 is compared with the case where the tube axes are shifted. The first combustion chamber 1 can be guided to the second combustion chamber 2 more reliably. Further, the connecting pipe 3 has an inner wall surface 3 a having an inner diameter as it goes from one end having the same inner diameter as the first combustion chamber 1 to the other end having the same inner diameter as the second combustion chamber 2. Is a tapered surface that gradually increases, so that the swirl flame 11 can be more reliably compared to the case where the inner diameter changes stepwise at the connection between the first combustion chamber 1 and the second combustion chamber 2. The first combustion chamber 1 can lead to the second combustion chamber 2.

  On the other hand, in the second combustion chamber, from the nozzle 7 provided in the second combustion chamber 2 toward the tangential direction of the inner wall surface 2b of the second combustion chamber 2 or toward the direction inclined with respect to the tangential direction, When air and pulverized fuel are blown into the two combustion chambers 2, the air and the pulverized fuel rotate in the second combustion chamber 2. The pulverized fuel is supplied to the swirl flame 11 that has moved (increased) from the first combustion chamber 1 to the second combustion chamber 2 and combusted.

  More specifically, in the second combustion chamber 2, the pulverized fuel is given a strong swirl together with air and is injected into the second combustion chamber 2 (supplied to the swirling flame 11). Ascending (moving toward the open end surface 5) while turning along the wall surface 2b. For this reason, the powdery fuel passes through the inside of the swirling flame 11 (tubular flame zone) by centrifugal force, and then rises while swirling in a state accompanied by the high-temperature reaction zone of the auxiliary fuel. As a result, in the second combustion chamber 2, heat exchange between the powdery fuel and the high-temperature reaction zone of the auxiliary fuel is performed very efficiently, so that the oxidation reaction (combustion) of the powdered fuel proceeds rapidly. Therefore, in the present pulverized fuel burner, even if a low-grade pulverized fuel such as a biomass fuel having a low calorie and a high water content is used as the pulverized fuel, reliable ignition and stable combustion are possible, and a relatively wide air Flame holding in the range of the ratio is also possible.

  In this case, in particular, the mounting angle of the nozzle 7 provided in the second combustion chamber 2 is set (fixed) by adjusting to an angle within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber 2. Thus, the pulverized fuel can be surely entered by the swirling flame 11 (tubular flame zone) and ignited more reliably.

  In the pulverized fuel burner according to the first embodiment, the inner diameter of the second combustion chamber 2 is made larger than the inner diameter of the first combustion chamber 1 so that the amount of air blown into the second combustion chamber 2 is the first. Since the amount of air blown into the combustion chamber 1 is increased, a large amount of pulverized fuel can be burned by the swirling flame 11 of a relatively small amount of auxiliary combustion fuel, thereby realizing high load combustion.

  In addition, since the pulverized fuel burner of the first embodiment is installed so that the tube axis directions of the first combustion chamber 1 and the second combustion chamber are vertical, the unburned pulverized fuel falls due to gravity. Even if it is blown up again by the swirling flame 11 or air rising from below, a circulating flow of unburned powdery fuel is formed in the vertical direction. For this reason, the residence time of the pulverized fuel in the second combustion chamber 2 is extended, and stable combustion is possible even with a relatively coarse pulverized fuel. As described above, the present pulverized fuel burner can be used even if it is installed so that the tube axis directions of the first combustion chamber 1 and the second combustion chamber 2 are in the horizontal direction. It is desirable to use a pulverized fuel having a small particle size.

<Embodiment 2>
FIG. 2 is a cross-sectional view of a main part of a powder fuel burner according to Embodiment 2 of the present invention, and is a cross-sectional view corresponding to FIG. In the powder fuel burner of the second embodiment, only the configuration of the nozzle provided in the second combustion chamber is different from the first embodiment (see FIG. 1), and the other configurations are the first embodiment. Therefore, detailed description and illustration are omitted here.

  As shown in FIG. 2, in the pulverized fuel burner according to the second embodiment, four nozzles 7 </ b> A and 7 </ b> B are provided on the side surface (circumferential surface) of the second combustion chamber 2. Two of these nozzles 7A are for blowing only air (oxygen-containing gas) sent from an air (oxygen-containing gas) supply device (not shown) into the second combustion chamber 2, and the other two nozzles 7B is for injecting into the 2nd combustion chamber 2 the pulverized fuel sent with air (oxygen-containing gas) from the pulverized fuel supply apparatus which is not illustrated.

  Four long slit-like holes 2a are formed in the circumferential surface (side surface) of the second combustion chamber 2 along the tube axis direction, and the tip portions 7a of the nozzles 7A and 7B are formed at the peripheral edge portions of these holes 2a. Each is connected. Further, the four nozzles 7A and 7B and the hole 2a are provided at the same position in the tube axis direction on the peripheral surface of the second combustion chamber 2, and the two nozzles 7A and the hole 2a are positions symmetrical with respect to the tube axis. The other two nozzles 7B and the hole 2a are also symmetrical with respect to the tube axis. The nozzles 7A and 7B are both directed at the tip side in the same circumferential direction (counterclockwise direction in the illustrated example). Further, since the nozzle 7 has a flat shape in which the tip 7a is long along the tube axis direction of the second combustion chamber 2, and the opening area thereof is reduced, air and powdered fuel are introduced in the tangential direction. Can be blown at high speed. In addition, although it is desirable to provide two nozzles 7A in the second combustion chamber 2 as in the illustrated example, the number is not necessarily limited to this, and one or three or more nozzles 7A may be provided in the second combustion chamber 2. Although it is desirable to provide two nozzles 7B in the second combustion chamber 2 as in the illustrated example, the number is not necessarily limited to this, and one or three or more nozzles 7B may be provided in the second combustion chamber 2.

  The nozzle 7 </ b> A is provided in the second combustion chamber 2 in a state of being directed in the tangential direction of the inner wall surface 2 b of the second combustion chamber 2. Accordingly, when air is blown into the second combustion chamber 2 from the nozzle 7A as indicated by an arrow in FIG. 2, a swirling flow of the air is formed in the second combustion chamber 2 along the inner wall surface 2b. . In this case as well, the attachment angle of the nozzle 7A is not necessarily limited to the case where the nozzle 7A is directed in the tangential direction. If a swirl flow of air can be formed in the second combustion chamber 2, the attachment angle with respect to the tangential direction May be directed in an inclined direction (for example, the angle may be set within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber 2).

  The nozzle 7B is also provided in the second combustion chamber 2 in a state in which it is directed in the tangential direction of the inner wall surface 2b of the second combustion chamber 2 in the illustrated example. However, since the nozzle 7A for blowing only air is provided separately from the nozzle 7B for blowing powdered fuel, the mounting angle of the nozzle 7B is not limited to the angle directed in the tangential direction, but the powdered fuel is swirl flame 11 (tubular flame). The angle is set not only to an angle within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber 2, but also to an angle smaller than 45 degrees. be able to.

  Even in the pulverized fuel burner of the second embodiment, the number of nozzles provided in the second combustion chamber 2 is larger than that in the pulverized fuel burner of the first embodiment, but the second embodiment is similar to the second embodiment. The same effect as the powder fuel burner can be obtained. Moreover, in the second embodiment, from the nozzle 7A provided in the second combustion chamber 2 toward the tangential direction of the inner wall surface 2b of the second combustion chamber 2 or toward the direction inclined with respect to the tangential direction, By blowing only air into the second combustion chamber 2, the air is swirled in the second combustion chamber 2, and powder is injected into the second combustion chamber 2 from another nozzle 7 </ b> B provided in the second combustion chamber 2. The powdered fuel is blown together with the air so that the powdered fuel is supplied to the swirling flame 11 that has moved from the first combustion chamber 1 to the second combustion chamber 2 and burned. Since the nozzle 7A for blowing only air is provided separately from the nozzle 7B for blowing air, the mounting angle of the nozzle 7B can be arbitrarily set separately from the nozzle 7A. Supply powdered fuel to Rukoto can.

<Embodiment 3>
3A is a side view of a pulverized fuel burner according to Embodiment 3 of the present invention, FIG. 3B is a cross-sectional view taken along line D-D in FIG. 3A, and FIG. FIG. 3A is a cross-sectional view taken along line EE in FIG. 3A, and FIG. 3D is a cross-sectional view taken along line FF in FIG.

  As shown in FIGS. 3 (a) to 3 (b), in the powdery fuel burner of the third embodiment, a tubular nozzle 21 is provided on the end surface 4 of the first combustion chamber 1. The nozzle 21 is provided such that its tube axis is coaxial with the tube axis of the first combustion chamber 1. And by blowing powdery fuel such as biomass fuel together with air (oxygen-containing gas) from the nozzle 21 into the first combustion chamber 1 in the direction of the pipe axis as indicated by an arrow in FIG. The pulverized fuel is supplied to the swirl flame 11 formed by the auxiliary fuel and burned.

  Since the other configuration of the third embodiment is the same as that of the first or second embodiment (see FIGS. 1 and 2), detailed description thereof is omitted here. In this case, the powdered fuel is not supplied from the nozzles 7, 7 </ b> A, 7 </ b> B into the second combustion chamber 2, but only the powdered fuel is supplied from the nozzle 21 into the first combustion chamber 1. It may be. In this case, only the first combustion chamber 1 may be provided without providing the second combustion chamber 2 as the combustion chamber.

  According to the pulverized fuel burner of the third embodiment, the swirl flame 11 made of auxiliary combustion fuel is stably formed around the pulverized fuel supplied into the first combustion chamber 1, and the nozzle 21 Immediately thereafter, the pulverized fuel blown into one combustion chamber 1 is rapidly heated by heat transfer from the swirling flame 11, leading to thermal decomposition, volatilization, and ignition. That is, the powdery fuel is supplied to the base of the swirling flame 11 formed by the auxiliary fuel, and the heat of the swirling flame 11 is surely supplied to the powdered fuel. Therefore, the biomass with low calorie and high water content is used as the powdered fuel. Even if a low-grade powdery fuel such as fuel is used, reliable ignition and stable flame holding are possible.

<Embodiment 4>
FIG. 4 is a side view showing a part of the main part of the powder fuel burner according to the fourth embodiment of the present invention. As shown in FIG. 4, in the pulverized fuel burner of the fourth embodiment, the inner wall surface 21 a of the nozzle 21 provided on the end surface 4 of the first combustion chamber 1 approaches the end surface 4 of the first combustion chamber 1. It has a tapered surface with an gradually increasing inner diameter. The angle θ ₅ of the inner wall surface 21a with respect to the tube axis direction (vertical direction) of the first combustion chamber 2 is an angle at which air mixed with the pulverized fuel flowing through the nozzle 21 does not separate from the inner wall surface 21a (for example, 5 to 5). 10 degrees). Such a specific value of the angle θ ₅ can be appropriately set theoretically or experimentally.

  Since the other configuration of the fourth embodiment is the same as that of the first to third embodiments (see FIGS. 1 to 3), detailed description and illustration are omitted here.

  According to the pulverized fuel burner of the fourth embodiment, the same effects as those of the third embodiment can be obtained. Moreover, in the pulverized fuel burner according to the fourth embodiment, the inner wall surface 21a of the nozzle 21 is a tapered surface whose inner diameter gradually increases as it approaches the end surface 4 of the first combustion chamber 1, and therefore from the nozzle 21. Since the pulverized fuel blown into the first combustion chamber 1 together with air spreads sufficiently in the first combustion chamber 1 as compared with the simple tubular nozzle 21 as in the third embodiment, the auxiliary combustion is more reliably performed. Since the fuel is supplied to the swirling flame 11 (tubular flame zone) formed by the fuel, more reliable ignition and stable flame holding of the powdered fuel are possible.

  The present invention relates to a pulverized fuel burner, and is particularly useful when applied to a low-grade pulverized fuel such as a biomass fuel having a low calorie and a high water content as fuel for the burner.

(A) is a side view of the pulverized fuel burner according to Embodiment 1 of the present invention, (b) is a cross-sectional view taken along line AA of (a), and (c) is BB of (a). A sectional view taken along line arrow, (d) is a sectional view taken along line CC of (a). It is principal part sectional drawing of the powdery fuel burner which concerns on Example 2 of Embodiment of this invention. (A) is a side view of a pulverized fuel burner according to Embodiment 3 of the present invention, (b) is a cross-sectional view taken along line DD of (a), and (c) is an EE of (a). A sectional view taken along line arrow, (d) is a sectional view taken along line FF of (a). It is a side view which partially fractures | ruptures and shows the principal part of the powdery fuel burner which concerns on Example 4 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st combustion chamber 1a Hole 1b Inner wall surface 2 2nd combustion chamber 2a Hole 2b Inner wall surface 3 Connection pipe 3a Inner wall surface 4,5 End surface 6 Nozzle 6a Tip part 7 Nozzle 7a Tip part 7A, 7B Nozzle 8 Spark plug 11 Swing flame 11 21 Nozzle 21a Inner wall surface

Claims (11)

The tubular first combustion chamber and the tubular second combustion chamber are connected in series, and the end surface on the first combustion chamber side is closed, while the end surface on the second combustion chamber side is opened,
In the first combustion chamber, oxygen-containing gas and auxiliary fuel are introduced into the first combustion chamber from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. And the mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber, and the mixture is ignited by an ignition plug provided in the first combustion chamber. To form a swirl flame,
In the second combustion chamber, from one or a plurality of nozzles provided in the second combustion chamber toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas and the pulverized fuel are swirled in the second combustion chamber by blowing the oxygen-containing gas and the pulverized fuel into the second combustion chamber, and the pulverized fuel is turned into the first combustion chamber. A powdery fuel burner configured to supply and burn the swirl flame that has moved from the chamber to the second combustion chamber. The pulverized fuel burner according to claim 1,
The nozzle provided in the second combustion chamber is set at an angle within a range of 45 to 90 degrees with respect to the radial direction of the second combustion chamber. The tubular first combustion chamber and the tubular second combustion chamber are connected in series, and the end on the first combustion chamber side is closed, while the end on the second combustion chamber side is opened,
In the first combustion chamber, oxygen-containing gas and auxiliary fuel are introduced into the first combustion chamber from one or a plurality of nozzles provided in the first combustion chamber toward the tangential direction of the inner wall surface of the first combustion chamber. And the mixture of the oxygen-containing gas and the auxiliary fuel is swirled in the first combustion chamber, and the mixture is ignited by an ignition plug provided in the first combustion chamber. To form a swirl flame,
In the second combustion chamber, from one or a plurality of nozzles provided in the second combustion chamber toward the tangential direction of the inner wall surface of the second combustion chamber or toward the direction inclined with respect to the tangential direction. The oxygen-containing gas is swirled in the second combustion chamber by blowing only the oxygen-containing gas into the second combustion chamber, and from one or more other nozzles provided in the second combustion chamber, The pulverized fuel is blown into the second combustion chamber together with the oxygen-containing gas so that the pulverized fuel is supplied to the swirling flame that has moved from the first combustion chamber to the second combustion chamber and burned. A powdery fuel burner characterized by that. In the pulverized fuel burner according to any one of claims 1 to 3,
The powdery fuel burner, wherein the first combustion chamber and the second combustion chamber are connected such that their tube axes are on the same axis. In the pulverized fuel burner according to any one of claims 1 to 4,
An inner diameter of the second combustion chamber is larger than an inner diameter of the first combustion chamber;
A powdery fuel burner characterized in that the amount of the oxygen-containing gas blown into the second combustion chamber is larger than the amount of the oxygen-containing gas blown into the first combustion chamber. The pulverized fuel burner according to claim 5,
The first combustion chamber and the second combustion chamber are connected in series via a connection pipe having one end connected to the first combustion chamber and the other end connected to the second combustion chamber.
A taper in which the inner wall surface of the connecting pipe gradually increases from the one end having the same inner diameter as the first combustion chamber toward the other end having the same inner diameter as the second combustion chamber. A pulverized fuel burner characterized in that it is shaped like a surface. In the pulverized fuel burner according to any one of claims 1 to 6,
The powdery fuel is blown into the first combustion chamber together with the oxygen-containing gas from the nozzle provided on the end face of the first combustion chamber, so that the powdery fuel is supplied to the swirling flame and burned. A pulverized fuel burner. Having a tubular combustion chamber with one end face closed and the other end face open;
In the combustion chamber, oxygen-containing gas and auxiliary fuel are blown into the combustion chamber from one or more nozzles provided in the combustion chamber toward the tangential direction of the inner wall surface of the combustion chamber. A mixture of gas and the auxiliary fuel is swirled in the combustion chamber, and the mixture is ignited by a spark plug provided in the combustion chamber to form a swirling flame in the combustion chamber, and one of the combustion chambers A pulverized fuel, wherein the pulverized fuel is blown into the combustion chamber together with an oxygen-containing gas from a nozzle provided on the end face of the slag so that the pulverized fuel is supplied to the swirling flame and burned. Burner. The pulverized fuel burner according to claim 7 or 8,
The inner wall surface of the nozzle provided on the end surface on the first combustion chamber side is a tapered surface whose inner diameter gradually increases so as to approach the end surface of the first combustion chamber, or one end surface of the combustion chamber A powdery fuel burner characterized in that the inner wall surface of the nozzle provided on the nozzle is a tapered surface whose inner diameter gradually increases so as to approach one end surface of the combustion chamber. In the pulverized fuel burner according to any one of claims 1 to 9,
A pulverized fuel burner, wherein the first combustion chamber and the second combustion chamber are installed so that the tube axis directions are vertical. In the pulverized fuel burner according to any one of claims 1 to 10,
The pulverized fuel burner, wherein the pulverized fuel is a pulverized biomass fuel.

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