JP2007085567A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a combustion device capable of reducing a quantity of NOx in a combustion exhaust gas with a simple constitution, and providing stable combustion. <P>SOLUTION: This combustion device is provided with a combustion air supply passage 14 at an outer periphery of a fuel gas supply pipe 13 for supplying a fuel gas, a flame stabilizing baffle plate 15 mounted at a tip portion of the fuel gas supply pipe in the combustion air supply passage, a heat chamber 10 provided with an ignition means 16 near fuel gas ports 13a, 13b at a tip of the fuel gas supply pipe, and an outer pipe 20 projecting forward in the jetting direction with respect to the heat chamber at an outer peripheral side of the heat chamber, and provided with an exhaust gas introduction port 21 for guiding the combustion exhaust gas near the gas ports of the tip of the heat chamber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion apparatus, and is particularly characterized in that the amount of NOx in combustion exhaust gas can be reduced with a simple configuration and stable combustion can be performed.

  Conventionally, in order to protect the environment, a method of reducing the amount of NOx present in the combustion exhaust gas after the fuel gas is burned by the combustion device has been studied.

  Here, it is known that the amount of NOx in the combustion exhaust gas increases as air is sufficiently supplied during combustion and the flame temperature increases.

  Then, as one of the methods for reducing the amount of NOx in the combustion exhaust gas, the combustion exhaust gas is circulated, and this combustion exhaust gas is mixed into the combustion air. Thus, the combustion air and fuel in which the combustion exhaust gas is mixed are used. What mixed gas and made it burn is known (for example, refer patent documents 1-3).

However, when the combustion exhaust gas is circulated and mixed with the combustion air, it is necessary to secure a flow path for circulating the combustion exhaust gas and leading it to the combustion air. In addition, there is a problem that the equipment cost is high, and there is also a problem that when combustion air mixed with combustion exhaust gas and fuel gas are mixed and burned, stable combustion cannot be performed.
Japanese Utility Model Publication No. 57-36883 Japanese Patent Laid-Open No. 61-240008 JP 2000-283423 A

  An object of the present invention is to solve the above-described problems in the conventional combustion apparatus, and to reduce the amount of NOx in the combustion exhaust gas with a simple configuration and to perform stable combustion. Is an issue.

  In the combustion apparatus according to the present invention, in order to solve the above-described problems, a combustion air supply path is provided on the outer periphery of the fuel gas supply pipe for supplying fuel gas, and the fuel gas supply pipe in the combustion air supply path A combustion cylinder in which a flame-holding plate is provided at the tip of the fuel gas, and an ignition means is provided in the vicinity of the fuel gas outlet at the tip of the fuel gas supply pipe. And an outer pipe provided with an exhaust gas inlet for guiding the exhaust gas in the vicinity of the jet outlet at the tip of the combustion cylinder.

  Here, in the combustion apparatus according to the present invention, the tip of the combustion cylinder is formed in a contracted shape toward the ejection port, and the outer tube is formed in a venturi shape, and the diameter of the outer tube is small. It is preferable that the throat portion thus formed is located in front of the above-described exhaust gas inlet and the outlet of the combustion cylinder in the ejection direction.

  In the combustion apparatus according to the present invention, when the inner diameter of the combustion cylinder is D and the distance from the tip of the fuel gas supply pipe to the jet outlet of the combustion cylinder is L, the value of L / D is It is preferable to be in the range of 0.5 to 2.7.

  In the combustion apparatus according to the present invention, the combustion air guided through the combustion air supply passage provided on the outer periphery of the fuel gas supply pipe is dispersed by the flame holding plate and guided to the tip of the fuel gas supply pipe. The combustion air and the fuel gas ejected from the fuel gas outlet at the tip of the fuel gas supply pipe are mixed and ignited by the ignition means, and the combustion air and the fuel gas are mixed with the combustion cylinder. The combustion exhaust gas guided to the vicinity of the nozzle at the front end of the combustion cylinder through the exhaust gas inlet provided in the outer pipe, and the combustion flame is ejected from the nozzle at the front end of the combustion cylinder. This is mixed with the combustion flame ejected from the ejection port of the combustion cylinder, and the fuel gas is further combusted in the outer tube.

  Here, after the combustion air and the fuel gas are combusted to some extent in the combustion cylinder as described above, the combustion exhaust gas is mixed with the combustion flame ejected from the jet outlet at the tip of the combustion cylinder in the outer tube. Further, when the fuel gas is burned, the flame temperature is prevented from greatly increasing, and the amount of NOx in the combustion exhaust gas is reduced. Further, unlike the conventional combustion device that circulates the combustion exhaust gas and mixes the combustion exhaust gas into the combustion air, it is not necessary to secure a flow path that circulates the combustion exhaust gas and leads it to the combustion air. Cost is not increased, and stable combustion can be achieved without causing unstable combustion as in the case where combustion air mixed with combustion exhaust gas is mixed with fuel gas for combustion. It becomes like this.

  Further, in the combustion apparatus according to the present invention, the tip of the combustion cylinder is formed in a contracted shape toward the ejection port, and the outer tube is formed in a venturi shape, and the diameter of the outer tube is reduced. When the throat portion is positioned in front of the exhaust gas inlet and the nozzle at the tip of the combustion cylinder in the ejection direction, the speed of the combustion flame ejected from the nozzle of the combustion cylinder is increased, and the venturi in the outer pipe is increased. Due to the effect, the combustion exhaust gas in the heating furnace is efficiently guided to the vicinity of the jet outlet at the tip of the combustion cylinder through the exhaust gas inlet provided in the outer tube, and a sufficient amount of the combustion exhaust gas is supplied to the combustion flame. It becomes like this.

  Further, in the combustion apparatus according to the present invention, when the inner diameter of the combustion cylinder is D and the distance from the tip of the fuel gas supply pipe to the nozzle at the tip of the combustion cylinder is L, the value of L / D is small. If it is too high, the combustion air and fuel gas will not be properly burned in the combustion cylinder and lift combustion will occur and the combustion will become unstable. On the other hand, if the L / D value becomes too large, The combustion air and the fuel gas are sufficiently combusted in this, and NOx is already generated in the combustion cylinder. After that, even if the combustion exhaust gas is mixed as described above, the amount of NOx generated is sufficiently reduced. Can not be made. On the other hand, when the L / D value is in the range of 0.5 to 2.7 as described above, the generation amount of NOx can be sufficiently reduced without causing unstable combustion. Become.

  Hereinafter, a combustion apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the combustion apparatus according to the present invention is not limited to the one shown in the following embodiment, and can be implemented with appropriate modifications within a range not changing the gist of the invention.

  In the combustion apparatus in this embodiment, as shown in FIG. 1, a combustion air supply port 11 for supplying combustion air into the combustion cylinder 10 is provided on the rear side of the combustion cylinder 10. The tip portion is contracted in a tapered shape, and a jet port 12 is provided at the tip of the combustion cylinder 10 thus contracted.

  A fuel gas supply pipe 13 for introducing fuel gas into the combustion cylinder 10 is provided, and the combustion air supply port 11 is provided between the outer periphery of the fuel gas supply pipe 13 and the inner periphery of the combustion cylinder 10. A combustion air supply passage 14 is formed to guide the combustion air supplied from the inside to the combustion cylinder 10. Here, as shown in FIGS. 1 and 2, the fuel gas supply pipe 13 is provided with fuel gas ejection ports 13 a and 13 b that eject fuel gas at the tip and the outer periphery of the tip.

  Further, a flame holding plate 15 having a plurality of air passage openings 15a is provided at a portion of the combustion air supply passage 14 on the tip side of the fuel gas supply pipe 13, and in front of the flame holding plate 15, An ignition means 16 such as a spark plug or a pilot burner is provided in the vicinity of the fuel gas outlet 13 b provided on the outer periphery of the tip of the fuel gas supply pipe 13.

  An outer tube 20 having a venturi shape is provided on the outer peripheral side of the combustion cylinder 10 so as to protrude forward from the ejection port 12 at the tip of the combustion cylinder 10 in the ejection direction, and the tip of the combustion cylinder 10 is provided. In the vicinity of the nozzle 12, a plurality of exhaust gas inlets 21 are provided in the outer tube 20 along the circumferential direction.

  Further, in the outer tube 20 having a venturi shape as described above, the throat portion 22 having a reduced diameter is positioned forward of the exhaust gas introduction port 21 and the jet port 12 at the tip of the combustion cylinder 10 in the ejection direction. The tip part in the ejection direction from the throat part 22 is shaped like a taper.

  And in this embodiment, as shown in said FIG. 1, while attaching said combustion apparatus to the attaching part 31 provided in the burner tile 30, attachment of the said burner tile 30 is carried out to the front end side of this combustion apparatus. In this state, the burner tile 30 to which the combustion apparatus is attached is attached to a predetermined position of the heating furnace 40 so as to protrude from the portion 31 into the mouth portion 32 of the burner tile 30 that is tapered toward the front. I have to.

  Here, when the fuel gas is burned by the combustion apparatus in this embodiment, the fuel gas is guided to the fuel gas outlets 13a and 13b provided at the front end and the outer periphery of the front end through the fuel gas supply pipe 13, and The fuel gas is ejected from the fuel gas ejection ports 13 a and 13 b into the combustion cylinder 10, and the combustion air supplied from the combustion air supply port 11 into the combustion cylinder 10 is passed through the combustion air supply path 14. It is guided to the flame holding plate 15 and guided to the tip of the fuel gas supply pipe 13 while dispersing the combustion air through the air passage port 15a provided in the flame holding plate 15 so as to be mixed with the fuel gas. To do.

  The fuel gas thus mixed with the combustion air is ignited by the ignition means 16, the fuel gas mixed with the combustion air is combusted to some extent in the combustion cylinder 10, and the combustion flame is The exhaust pipe 12 at the tip of the combustion cylinder 10 contracted as described above is ejected into the outer pipe 20 and the combustion exhaust gas in the heating furnace 40 is provided to the outer pipe 20 from the mouth 32 of the burner tile 30. The exhaust gas is introduced into the outer pipe 20 through the exhaust gas inlet 21, and the fuel gas is burned in the outer pipe 20 while supplying the combustion exhaust gas thus led to the combustion flame. To erupt.

  Here, when the fuel gas mixed with the combustion air as described above is burned to some extent in the combustion cylinder 10 and this combustion flame is ejected into the outer tube 20, the diameter of the outer tube 20 is reduced. The speed of the combustion flame is increased at the throat portion 22, and due to this venturi effect, the combustion exhaust gas in the heating furnace 40 is sufficiently guided from the mouth portion 32 of the burner tile 30 into the outer pipe 20 through the exhaust gas inlet 21. As a result, a sufficient amount of combustion exhaust gas is supplied to the combustion flame. As a result, a significant increase in the temperature of the combustion flame is suppressed, and the amount of NOx in the combustion exhaust gas is reduced.

  Here, in the above combustion apparatus, the inner diameter D of the combustion cylinder 10 and the distance L from the tip of the fuel gas supply pipe 13 to the jet port 12 at the tip of the combustion cylinder 10 are changed, so that L / D When the value is changed, the combustion exhaust gas introduction rate introduced into the outer pipe 20 through the exhaust gas inlet 21 and how the NOx generation rate in the combustion exhaust gas changes are examined. FIG. 3 shows the changing state, and FIG. 4 shows the state where the NOx production rate in the combustion exhaust gas changes.

  As a result, as shown in FIG. 3, as the L / D value increases, the combustion exhaust gas introduction rate increases, and the amount of combustion exhaust gas guided into the outer pipe 20 through the exhaust gas inlet 21 increases. did.

  On the other hand, as shown in FIG. 4, the NOx production rate in the combustion exhaust gas is minimum when the L / D value is around 1.5, and the L / D value is 0.5 to 2.7. In this range, the increase in the NOx generation rate was low.

It is a schematic sectional explanatory view showing the state where the combustion device concerning one embodiment of this invention was attached to the heating furnace via the burner tile. In the combustion apparatus which concerns on the same embodiment, it is a cross-sectional explanatory view showing the state of the tip of the fuel gas supply pipe. In the combustion apparatus according to the embodiment, when the L / D value is changed by changing the inner diameter D of the combustion cylinder and the distance L from the tip of the fuel gas supply pipe to the jet outlet of the tip of the combustion cylinder. It is the schematic diagram which showed the state from which the introduction rate of the combustion exhaust gas guide | induced into an outer pipe | tube through an exhaust gas inlet changes. In the combustion apparatus according to the embodiment, when the L / D value is changed by changing the inner diameter D of the combustion cylinder and the distance L from the tip of the fuel gas supply pipe to the jet outlet of the tip of the combustion cylinder. It is the schematic diagram which showed the state from which the NOx production rate in combustion exhaust gas changes.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Combustion cylinder 11 Combustion air supply port 12 Jet port 13 Fuel gas supply pipe 13a, 13b Fuel gas jet port 14 Combustion air supply path 15 Flame holding plate 15a Air passage port 16 Ignition means 20 Outer tube 21 Exhaust gas inlet port 22 Throat Part 30 Burner tile 31 Mounting part 32 Port 40 Heating furnace D Inner diameter of combustion cylinder L Distance from the tip of the fuel gas supply pipe to the jet outlet at the tip of the combustion cylinder

Claims (3)

  A combustion air supply path is provided on the outer periphery of the fuel gas supply pipe for supplying the fuel gas, and a flame holding plate is provided at the tip of the fuel gas supply pipe in the combustion air supply path. A combustion cylinder in which ignition means is provided in the vicinity of the fuel gas outlet at the tip, and an exhaust gas that protrudes forward in the ejection direction from the combustion cylinder on the outer peripheral side of the combustion cylinder and near the outlet at the tip of the combustion cylinder And an outer pipe provided with an exhaust gas inlet for guiding the combustion.   The combustion apparatus according to claim 1, wherein the tip of the combustion cylinder is formed in a contracted shape toward the ejection port, and the outer tube is a venturi tube, and the diameter of the outer tube is A combustion apparatus characterized in that the reduced throat portion is located in front of the exhaust gas introduction port and the ejection port at the tip of the combustion cylinder in the ejection direction.   In the combustion apparatus according to claim 1 or 2, when the inner diameter of the combustion cylinder is D and the distance from the tip of the fuel gas supply pipe to the jet outlet of the combustion cylinder tip is L, L / D Is a range from 0.5 to 2.7.

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