JP2018204837A - Combustor - Google Patents

Abstract

To provide a combustor capable of stably combusting low grade fuel.SOLUTION: The combustor comprises: a cylindrical gas feed pipe with a first opening formed on a side wall thereof; a first feed part connected to the first opening to feed first gas to the gas feed pipe and causes the first gas to swirl along an inner wall of the gas feed pipe; a combustion pipe connected to the gas feed pipe to combust the first gas in the pipe; and a gas recycle pipe disposed to cover the gas feed pipe and the combustion pipe to recycle exhaust gas resulting from the combustion in the combustion pipe to the gas feed pipe side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a combustor.

  For example, there is a need for a technique for inexpensively treating or using heat, such as biomass-derived off-gas or by-product gas, which has a low calorific value or combustion rate, and which has a low combustibility (hereinafter referred to as “low-grade fuel”). Yes. In order to burn these low-grade fuels, there is a method in which a combustion catalyst or a high-quality fuel is added and burned, but an increase in initial cost or running cost is unavoidable.

  Therefore, it is conceivable to use a swirling flow in order to burn the low-grade fuel as described above. As a method of swirling fuel to burn, a method of swirling fuel in a mixing tube by swirl blades is disclosed (for example, see Patent Document 1).

JP 2005-133957 A

  However, in the method disclosed in Patent Document 1, there is a limit to the strength (swirl number) of the swirl flow that can be realized. That is, there is a possibility that the low-grade fuel cannot be burned stably.

  This invention is made | formed in view of the above, Comprising: It aims at providing the combustor which can burn a low quality fuel stably.

  According to the combustor in one aspect of the present invention, a cylindrical gas supply pipe having a first opening formed on the side wall, a first gas connected to the first opening and supplied to the gas supply pipe, A first supply unit that swirls the gas along the inner wall of the gas supply pipe, a combustion pipe that is connected to the gas supply pipe and burns the first gas in the pipe, and is provided to cover the gas supply pipe and the combustion pipe. A gas recirculation pipe for recirculating exhaust gas generated by combustion in the pipe to the gas supply pipe side.

  According to the embodiment of the present invention, a combustor capable of stably burning low-grade fuel is provided.

It is a figure which illustrates the combustor in 1st Embodiment. It is a figure which illustrates the gas supply pipe, the 1st supply part, and the 2nd supply part in a 1st embodiment. It is a figure which illustrates the gas supply pipe in a 1st embodiment, the 1st supply part, the 2nd supply part, and a gas reflux pipe. It is a figure which illustrates the combustion pipe in 1st Embodiment. It is a figure for demonstrating the flow of the mixed gas in a combustion pipe. It is a figure for demonstrating the flow of the exhaust gas in a combustor. It is a figure which shows the measurement result of the methane density | concentration in fuel gas when CO density | concentration in the waste gas in Examples 1-3 becomes 10, 100, 1000 ppm. It is a figure which shows the measurement result of the methane density | concentration in fuel gas when the CO density | concentration in the waste gas in Examples 4-6 will be 10, 100, 1000 ppm. It is a figure which illustrates the combustor in 2nd Embodiment.

  Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

[First Embodiment]
FIG. 1 is a diagram illustrating a combustor 100 according to the first embodiment.

  As shown in FIG. 1, the combustor 100 includes a gas supply pipe 10, a first supply part 20, a second supply part 30, a combustion pipe 40, a spark plug 50, and a gas recirculation pipe 60.

  The gas supply pipe 10 is formed in a cylindrical shape, and supplies the fuel gas supplied from the first supply unit 20 and the second supply unit 30 to the combustion pipe 40. The first supply unit 20 is connected to the gas supply pipe 10 and supplies, for example, a mixed gas in which fuel gas and air are mixed in advance to the gas supply pipe 10 from the opening 20A. The second supply unit 30 is connected to the gas supply pipe 10 at a position different from that of the first supply unit 20, and supplies, for example, a mixed gas in which fuel gas and air are mixed in advance to the gas supply pipe 10 from the opening 30A. .

  The gas supply pipe 10, the first supply unit 20, and the second supply unit 30 may be joined after being formed as separate bodies, or any two or more may be integrally formed. The gas supply pipe 10, the first supply unit 20, and the second supply unit 30 are formed of, for example, a resin having high heat resistance, a metal material, or the like.

  Further, the fuel gas is supplied from the first supply unit 20 to the gas supply pipe 10, the air is supplied from the second supply unit 30 to the gas supply pipe 10, and the fuel gas and air mixed in the gas supply pipe 10 are mixed. A mixed gas may be supplied to the combustion tube 40.

  The combustion tube 40 is formed in a cylindrical shape by glass, for example. The combustion tube 40 is supplied with a mixed gas from the gas supply tube 10, and the mixed gas is ignited by a spark plug 50, which is an ignition device, and a flame F is formed in the tube. The combustion tube 40 may be formed of, for example, a metal material.

  The spark plug 50 is attached to a mounting hole (not shown) provided in the bottom wall of the gas supply pipe 10, and the ignition portion faces the inside of the gas supply pipe 10. The spark plug 50 generates a spark discharge by a high voltage applied from the outside, and ignites the mixed gas in the combustion tube 40. The ignition device is not limited to the spark plug 50 as long as it can ignite the mixed gas in the combustion tube 40.

  The gas recirculation pipe 60 is formed in a cylindrical shape and is attached so as to cover the gas supply pipe 10 and the combustion pipe 40. In addition, a notch 61 is formed in the gas circulation pipe 60 at a location where the first and second supply parts 20 and 30 interfere with the attachment of the gas circulation pipe 60. The gas reflux tube 60 is formed of a metal material having a low thermal conductivity, such as stainless steel.

  The gas recirculation pipe 60 causes the exhaust gas generated by the combustion of the mixed gas in the combustion pipe 40 to be folded at the closed upper end 62, and is circulated to the gas supply pipe 10 side through the outside of the combustion pipe 40. Further, a cylindrical exhaust pipe 63 is attached in the vicinity of the lower end of the gas circulation pipe 60, and exhaust gas exhausted from the opening 63 </ b> A of the exhaust pipe 63 is exhausted.

  Next, each part of the combustor 100 will be described in detail with reference to FIGS. 2 and 3.

  FIG. 2 is a side view illustrating the gas supply pipe 10, the first supply unit 20, and the second supply unit 30 in the first embodiment. FIG. 3 is a diagram illustrating the gas supply pipe 10, the first supply unit 20, the second supply unit 30, and the gas recirculation pipe 60 in the first embodiment. It is the figure which described the gas reflux tube 60 collectively.

  As shown in FIGS. 2 and 3, the gas supply pipe 10 is formed in a cylindrical shape whose lower end side is closed by a bottom wall except for a mounting hole for a spark plug (not shown). A gas chamber 11 into which fuel gas is supplied from the first supply unit 20 and the second supply unit 30 is formed inside the gas supply pipe 10.

  As shown in FIG. 2, a combustion tube receiving portion 15 having a diameter larger than that of the gas chamber 11 and into which the combustion tube 40 is inserted is formed above the gas chamber 11 of the gas supply tube 10. A seal ring 16 formed in an annular shape with a material having high heat resistance and hermeticity, for example, is attached to the inner peripheral surface of the combustion tube receiving portion 15. A seal ring 16 attached to the combustion tube receiver 15 seals between the combustion tube receiver 15 and the combustion tube 40.

  A first opening 12 and a second opening 13 are formed in the side wall of the gas supply pipe 10. As shown in FIG. 2, the first opening 12 and the second opening 13 are each formed in a rectangular shape extending in the axial direction of the gas supply pipe 10. In the present embodiment, the first opening 12 and the second opening 13 are formed at positions different by 180 ° in the circumferential direction of the gas supply pipe 10, but the present invention is not limited to this.

  2 and 3, the first supply unit 20 is formed in a flat plate shape, and is connected to the gas supply pipe 10 so as to extend in the tangential direction of the side wall of the gas supply pipe 10. The first supply unit 20 has a first gas channel 21 formed therein, and is connected to the gas supply pipe 10 so that the first gas channel 21 communicates with the first opening 12.

  The second supply unit 30 is formed in a flat plate shape like the first supply unit 20, and is connected to the gas supply pipe 10 so as to extend in the tangential direction of the side wall of the gas supply pipe 10. The second supply section 30 has a second gas flow path 31 formed therein, and is connected to the gas supply pipe 10 so that the second gas flow path 31 communicates with the second opening 13.

  The first gas passage 21 is connected to the first opening 12 so as to extend in the tangential direction of the inner wall surface of the gas chamber 11 of the gas supply pipe 10. The second gas flow path 31 is connected to the second opening 13 so as to extend in the tangential direction of the inner wall surface of the gas chamber 11 of the gas supply pipe 10. For this reason, the mixed gas supplied to the gas supply pipe 10 from the first gas flow path 21 and the second gas flow path 31 is along the inner peripheral surface of the side wall of the gas supply pipe 10 as shown in FIG. It flows and swirls inside the gas chamber 11. Further, the mixed gas supplied to the gas supply pipe 10 rises while swirling inside the gas chamber 11, and is supplied to the combustion pipe 40 and combusted as shown in FIG.

  Further, when fuel gas is supplied from the first supply unit 20 and air is supplied from the second supply unit 30, the fuel gas and air are mixed while swirling inside the gas chamber 11, and the fuel gas and A mixed gas with air is supplied to the combustion tube 40.

  As shown in FIG. 3, the gas recirculation pipe 60 is provided with an exhaust pipe 63 for exhausting the recirculated exhaust gas. The exhaust gas generated by the combustion of the mixed gas in the combustion pipe 40 is folded at the upper end 62 of the gas circulation pipe 60, circulated to the gas supply pipe 10 side while turning, and exhausted from the exhaust pipe 63.

  Further, the exhaust pipe 63 is attached so as to be deviated from the central axis of the gas circulation pipe 60 so that the swirling exhaust gas is easily exhausted. In the present embodiment, the exhaust pipes 63 are attached at two locations, but the present invention is not limited to this.

  FIG. 4 is a diagram illustrating the combustion tube 40 in the first embodiment.

  As shown in FIG. 4, the combustion tube 40 has a small diameter portion 41, a tapered portion 42, and a large diameter portion 43.

  The small diameter portion 41 is formed in a cylindrical shape whose inner diameter is equal to the inner diameter of the gas chamber 11 of the gas supply pipe 10 and whose outer diameter is equal to the inner diameter of the combustion pipe receiving portion 15 of the gas supply pipe 10. The combustion pipe 40 is connected to the gas supply pipe 10 by inserting the small diameter part 41 into the combustion pipe receiving part 15. The taper portion 42 is connected to the small diameter portion 41 and is formed in a truncated cone shape whose inner diameter increases as the distance from the small diameter portion 41 increases. The large diameter portion 43 is formed in a cylindrical shape whose inner diameter is larger than the inner diameter of the small diameter portion 41 and is connected to the tapered portion 42.

  FIG. 5 is a view for explaining the flow of the mixed gas in the combustion tube 40.

  The combustion tube 40 is supplied with a mixed gas that rises while swirling along the inner peripheral surface of the gas chamber 11 of the gas supply tube 10. The mixed gas supplied to the combustion pipe 40 rises while swirling along the inner peripheral surface of each part so as to reach the large diameter part 43 through the small diameter part 41 and the tapered part 42.

  Here, inside the combustion tube 40, the mixed gas swirls to attract the internal gas toward the outer peripheral side, so that the pressure near the inner peripheral surface increases and the pressure difference increases so that the pressure at the central portion decreases. Arise. Further, the swirling flow of the mixed gas is weakened as the inner diameter gradually increases in the tapered portion 42 and the large diameter portion 43. For this reason, the mixed gas supplied to the combustion tube 40 rises while swirling and reaches the large diameter portion 43, and then the pressure decreases at the taper portion 42 and the small diameter portion 41 as shown in FIG. It flows so as to descend toward the central part of the swirling flow.

  When the mixed gas flows inside the combustion pipe 40 as described above, the flame F formed by the combustion of the mixed gas is positioned in the vicinity of the tapered portion 42 as shown in FIG. Thus, according to the combustion tube 40 in the first embodiment, the position of the flame F is stabilized in the vicinity of the tapered portion 42, and the mixed gas can be combusted stably.

  FIG. 6 is a view for explaining the flow of exhaust gas in the combustor 100.

  The exhaust gas generated by the combustion of the mixed gas in the combustion pipe 40 is folded at the upper end 62 of the gas circulation pipe 60. The folded exhaust gas is recirculated to the gas supply pipe 10 side through the outside of the combustion pipe 40 while turning, and is exhausted from the exhaust pipe 63.

  At this time, since the combustion tube 40 is covered with the high-temperature exhaust gas, the loss due to the radiant heat from the flame formed in the tube of the combustion tube 40 is reduced, and the combustibility can be improved. Further, by covering the gas supply pipe 10 with high-temperature exhaust gas, the mixed gas supplied from the gas supply pipe 10 to the combustion pipe 40 is preheated, and the combustibility can be improved.

  In addition, the dimension of each part of the gas supply pipe 10, the 1st supply part 20, the 2nd supply part 30, the combustion pipe 40, and the gas recirculation pipe | tube 60 in the combustor 100 is not limited to an above-described example, It may be changed. The shapes of the gas supply pipe 10, the combustion pipe 40, and the gas recirculation pipe 60 are not limited to a cylindrical shape as long as the gas can be swirled. Further, the combustion tube 40 does not necessarily have the tapered portion 42.

  Moreover, although the 1st supply part 20 and the 2nd supply part 30 are provided so that it may extend in the tangential direction of the side wall of the gas supply pipe | tube 10 in this embodiment, the gas supplied inside the gas supply pipe | tube 10 is swirled. If it can be made, it will not be restricted to the structure illustrated in this embodiment.

  Further, only one of the first supply unit 20 and the second supply unit 30 may be provided. In addition to the first supply unit 20 and the second supply unit 30, the gas supply pipe 10 has the same configuration. One or more supply parts for supplying fuel gas or the like may be further provided. Further, the shape of the supply unit and the gas flow path provided in the combustor 100 is limited to the shape illustrated in the first embodiment as long as a swirl flow can be formed inside the gas chamber 11 of the gas supply pipe 10. It is not a thing.

<Example>
Next, in the combustor 100 according to the first embodiment, the height H1 of the first opening 12 and the second opening 13 of the gas supply pipe 10 shown in FIG. 2, the first of the first supply unit 20 shown in FIG. The width W1 of the first gas passage 21, the width W2 of the second gas passage 31 of the second supply unit 30, the angle θ of the tapered portion 42 of the combustion tube 40 shown in FIG. The angle formed by the inner wall surface of the portion 41 and the inner wall surface of the large-diameter portion 43) and the dimensions of the combustion tube 40 are set as follows, and a mixed gas of methane and carbon dioxide is used as the fuel gas. An embodiment in which the methane concentration in the fuel gas is measured for a low-grade fuel having a low concentration will be described.

  Specifically, the height H1 of the first opening 12 and the second opening 13 of the gas supply pipe 10 was set to 10 mm. Further, the width W1 of the first gas channel 21 of the first supply unit 20 and the width W2 of the second gas channel 31 of the second supply unit 30 were set to 1 mm.

  Further, the inner diameter D1 of the small diameter portion 41 of the combustion pipe 40 is 17 mm (the inner diameter D1 of the gas chamber 11 of the gas supply pipe 10 is also 17 mm), the angle θ of the tapered portion 42 is 10 °, and the inner diameter D2 of the large diameter portion 43 is It was 30 mm. Further, the length L1 of the small diameter portion 41 of the combustion tube 40 was 30 mm, and the length L2 of the large diameter portion 43 was 200 mm.

  In each example of the first embodiment, a mixed gas obtained by mixing a fuel gas obtained by diluting methane with carbon dioxide and air in advance is supplied from the first gas channel 21 and the second gas channel 31. The methane concentration in the fuel gas was measured.

Example 1
In Example 1, in the combustor 100 having the above-described configuration, the flow rate [L / min] of the supplied mixed gas is fixed to 1.0 L / min, and the ratio of the combustible component in the fuel to the oxygen in the air is set. The methane concentration in the fuel gas was measured while changing the equivalent ratio divided by the theoretical fuel-air ratio. In Example 1, the measurement was performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 was 10 ppm.

(Example 2)
In the second embodiment, the conditions are the same as those in the first embodiment, except that the measurement was performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 was 100 ppm.

Example 3
In Example 3, the conditions were the same as in Example 1 except that the measurement was performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 was 1000 ppm.

  The measurement results of the methane concentration in the fuel gas in Examples 1 to 3 are shown in FIG. In the graph shown in FIG. 7, the horizontal axis represents the equivalence ratio, and the vertical axis represents the methane concentration [%] in the fuel gas.

  From FIG. 7, in Example 1, the methane concentration in the fuel gas was 12.0%, which is the lowest, at an equivalence ratio of 0.87. In Example 2, the methane concentration in the fuel gas was the lowest 11.7% at an equivalence ratio of 0.87. In Example 3, the methane concentration in the fuel gas was 11.3%, which is the lowest, at an equivalent ratio of 0.79 to 0.87.

  From the measurement results of Examples 1 to 3, it can be seen that in the combustor 100 having the above-described configuration, the methane concentration in the fuel gas becomes the lowest in the vicinity of the equivalence ratio of 0.87. Therefore, the methane concentration in the fuel gas was measured while changing the flow rate [L / min] of the mixed gas supplied to the combustor 100 with the equivalence ratio fixed at 0.87.

(Example 4)
In Example 4, in the combustor 100 having the above-described configuration, the equivalence ratio was fixed to 0.87, and the methane concentration in the fuel gas was measured while changing the flow rate [L / min] of the supplied mixed gas. In Example 1, the measurement was performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 was 10 ppm.

(Example 5)
In the fifth embodiment, the conditions are the same as those in the fourth embodiment except that the measurement is performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 is 100 ppm.

(Example 6)
In Example 6, the conditions were the same as in Example 4 except that the measurement was performed when the CO (carbon monoxide) concentration of the exhaust gas exhausted from the exhaust pipe 63 was 1000 ppm.

  The measurement result of the methane density | concentration in the fuel gas in Examples 4-6 is shown in FIG. In the graph shown in FIG. 8, the horizontal axis represents the flow rate [L / min] of the mixed gas supplied to the combustor 100, and the vertical axis represents the methane concentration [%] in the fuel gas.

  From FIG. 8, in Example 4, the methane concentration in the fuel gas was the lowest 11.4% at a flow rate of 24 L / min. In Example 5, the methane concentration in the fuel gas was the lowest at 11.2% at a flow rate of 24.2 L / min. In Example 6, the methane concentration in the fuel gas was the lowest 10.8% at a flow rate of 24.7 L / min.

  These values are derived from methane as carbon dioxide in previous studies (HF Coward, GW Jones, Limits of Flammability of Gases and Vapors, U.S. Bur. Mines Bull. No. 503 (1952)). Compared to the methane concentration (22.8%) in combustible fuel gas when diluted and not preheated, this is a significant improvement.

  Thus, it can be seen that the methane concentration in the fuel gas in each example is lower than the methane concentration in the fuel gas in the previous research, and even the mixed gas having a low methane concentration can be combusted in the combustor 100.

  As described above, according to the combustor 100 in the first embodiment, the gas circulation pipe 60 causes the exhaust gas generated by the combustion in the combustion pipe 40 to be circulated to the gas supply pipe 10 side, so that the methane concentration Even if it is a low-grade fuel with low, it becomes possible to burn stably.

[Second Embodiment]
Next, a second embodiment will be described based on the drawings. Note that a description of the same components as those of the above-described embodiment will be omitted.

  FIG. 9 is a diagram illustrating a combustor 200 according to the second embodiment.

  As shown in FIG. 9, the combustor 200 according to the second embodiment has an annular slit 18 formed along the periphery of the bottom wall of the gas supply pipe 10. A third supply unit 70 having a gas flow path connected to the slit 18 is connected to the gas supply pipe 10. The slit 18 may have a shape different from that of the present embodiment.

  In the combustor 200, for example, air is supplied from the first supply unit 20 and the second supply unit 30 to the gas supply pipe 10, and fuel gas is supplied from the third supply unit 70 through the slit 18. The combustor 200 may be provided with only one of the first supply unit 20 and the second supply unit 30, and a supply unit that supplies fuel gas or the like to the gas supply pipe 10 with the same configuration is further provided. One or more may be provided.

  By supplying the fuel gas and air to the gas supply pipe 10 in this way, the fuel gas and air are mixed while swirling inside the gas chamber 11. The mixed gas of fuel gas and air mixed in the gas supply pipe 10 rises while swirling, is supplied to the combustion pipe 40, is ignited by the spark plug 50, and burns.

  At this time, the mixed gas flows in the combustion tube 40 as described above, so that the flame F formed by the combustion of the mixed gas is positioned in the vicinity of the tapered portion 42 as shown in FIG. Thus, according to the combustion tube 40 in the second embodiment, the position of the flame F is stabilized in the vicinity of the tapered portion 42, and the mixed gas can be combusted stably.

  Further, the exhaust gas generated by the combustion of the mixed gas in the combustion pipe 40 is folded at the upper end 62 of the gas circulation pipe 60, circulated to the gas supply pipe 10 side while turning, and exhausted from the exhaust pipe 63.

  In the combustor 200 according to the second embodiment, as described above, the air supplied from the first supply unit 20 and the second supply unit 30 and the fuel gas supplied from the third supply unit 70 are gas supply pipes. 10 is mixed and supplied to the combustion tube 40 while swirling as a mixed gas. According to the combustor 200 in the second embodiment, low-grade fuel can be stably combusted in the same manner as the combustor 200 in the first embodiment.

  Although the combustor according to the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements can be made within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Gas supply pipe 18 Slit 20 1st supply part 21 1st gas flow path 30 2nd supply part 31 2nd gas flow path 40 Combustion pipe 41 Small diameter part 42 Taper part 43 Large diameter part 50 Spark plug 60 Gas recirculation pipe 70 1st 3 Supply unit 100, 200 Combustor

Claims (6)

A cylindrical gas supply pipe having a first opening formed on the side wall;
A first supply unit connected to the first opening to supply a first gas to the gas supply pipe, and to turn the first gas along an inner wall of the gas supply pipe;
A combustion pipe connected to the gas supply pipe to burn the first gas in the pipe;
A gas combustor provided to cover the gas supply pipe and the combustion pipe, and configured to circulate exhaust gas generated by combustion in the combustion pipe toward the gas supply pipe. The combustor according to claim 1, further comprising an ignition device attached to a bottom wall of the gas supply pipe so that an ignition unit faces the inside of the gas supply pipe. The combustor according to claim 1 or 2, wherein the gas reflux tube is made of stainless steel. The combustion pipe includes a cylindrical small-diameter portion connected to the gas supply pipe, a tapered portion connected to the small-diameter portion and formed so that an inner diameter increases as the distance from the small-diameter portion increases, and the tapered portion A combustor according to any one of claims 1 to 3, further comprising a cylindrical large-diameter portion connected to the cylinder. The gas supply pipe has a second opening formed in the side wall,
A second supply part connected to the second opening for supplying a second gas to the gas supply pipe and mixing the second gas with the first gas while swirling along the inner wall of the gas supply pipe; The combustor according to any one of claims 1 to 4. The gas supply pipe has a slit formed at the periphery of the bottom wall,
The combustor according to any one of claims 1 to 5, further comprising a third supply unit that is connected to the slit and supplies a third gas to the gas supply pipe.