JP2006308120A - Catalyst combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst combustion device capable of burning catalyst by sufficiently uniformly mixing gas and air. <P>SOLUTION: A swirl vane 22 is spirally mounted in a gas mixing heating portion 13, and a heating chamber 23 is formed inside of the swirl vane 22. The gas supplied to a gas burner 12 is partially burnt at a combustion opening 16 to heat a mixture gas in the heating chamber 23. On the other hand, the gas supplied to the gas burner 12 is partially discharged into the heating chamber 23 from a gas discharge opening 17. The air supplied from an air supply opening 21 of the gas mixing heating portion 13 is supplied into the heating chamber 23 through the swirl vane 22. The air passing through the swirl vane 22 is spirally swirled by the swirl vane 22, and the gas in the heating chamber 23 and the air are stirred and uniformly mixed by being swirled, to completely burn the mixture gas in a catalyst layer 14. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalytic combustion apparatus in which gas is completely burned using a catalyst.

  When the gas burns incompletely, nitrogen oxides (NOx) are generated. Since nitrogen oxide pollutes the environment, a catalytic combustion apparatus is used to reduce nitrogen oxide generated when gas is burned.

  An example of a conventional catalytic combustion apparatus is disclosed in Japanese Utility Model Laid-Open No. 61-4110 (Patent Document 1). In this catalytic combustion apparatus, a gas of 400 to 500 ° C. preheated by a pilot burner is supplied into the combustion apparatus main body from one end. On the other hand, a plurality of fuel nozzles are connected to the outer peripheral body surface of the combustion apparatus main body, and each fuel nozzle is inclined in a direction toward the center of the combustion apparatus main body and is arranged in a spiral shape. Moreover, the catalyst layer is provided in the other end part of the combustion apparatus main body.

  Thus, gas is supplied from one end of the combustion apparatus body into the combustion apparatus body, and secondary fuel is supplied from the fuel nozzle into the combustion apparatus body, and the gas and the secondary fuel are mixed in the combustion apparatus body. ing. Since the fuel nozzle is arranged in a spiral shape, the flow of the secondary fuel discharged from the fuel nozzle at this time becomes a spiral in the combustion apparatus body, and the gas and the secondary fuel are uniformly stirred. The uniformly stirred gas and secondary fuel are completely burned in the catalyst layer.

  However, in the catalytic combustion apparatus having such a structure, the spiral flow generated by the secondary fuel supplied from the combustion nozzle is only around the inside of the combustion apparatus body (near the inner wall surface), and the central part of the combustion apparatus body In this case, the gas and the secondary fuel could not be sufficiently stirred, and the gas concentration of the mixed gas of the gas and the secondary fuel was uneven.

  If the gas and the secondary fuel are not uniformly mixed and the gas concentration is uneven, the catalyst layer cannot react at a high gas concentration, and the gas may not be burned completely.

  Furthermore, a temperature distribution due to reaction heat with the catalyst layer is generated in the catalyst layer in proportion to the gas concentration of the mixed gas. When the catalyst layer reaches a certain temperature or higher, sintering (sintering) occurs, and the ability as a catalyst is reduced, and the ability as a catalyst is lost. Therefore, when the temperature unevenness occurs in the catalyst due to such temperature distribution, the ability of the catalyst is partially impaired. Therefore, it is necessary to use the catalyst layer while maintaining it so that it is always kept below a certain temperature. However, if temperature distribution occurs, such temperature management becomes difficult.

Japanese Utility Model Publication No. 61-4110

  The present invention has been made in view of the above technical problems, and an object of the present invention is to provide a catalytic combustion apparatus capable of performing catalytic combustion by sufficiently uniformly mixing gas and air. There is.

  According to a first aspect of the present invention, there is provided a catalytic combustion apparatus comprising: a gas mixing part for mixing gas and air; a gas outlet for supplying gas to the gas mixing part; and supplying air to the gas mixing part. An air supply port, a combustion part for heating the gas mixed with the gas supplied to the gas mixing part, and a catalyst layer for burning the mixed gas mixed and heated in the gas mixing part In the catalytic combustion apparatus, a swirl vane for swirling the air supplied to the gas mixing unit to mix the air and gas in the mixing unit is provided in the gas mixing unit. The gas supplied from the gas discharge port may contain air.

  According to the catalytic combustion apparatus of the first aspect of the present invention, since the swirl vane is provided in the gas mixing unit, the air supplied to the gas mixing unit and passing through the swirl vane is swirled by the swirl vane to generate a vortex flow. The gas and air in the gas mixing chamber can be forcibly stirred by this vortex. Moreover, since this vortex is generated by the swirl vanes provided inside the gas mixing chamber, a vortex can be generated also at the center of the gas mixing chamber, and the gas and air can be efficiently stirred.

  Therefore, according to the catalytic combustion apparatus of claim 1, the gas and air can be uniformly mixed and the mixed gas can be heated uniformly, and the temperature and gas concentration of the mixed gas in the catalyst layer are uniformly distributed. The gas can be completely burned by the catalyst layer. Moreover, it can avoid that a catalyst layer partially becomes high temperature and deteriorates, and can extend the lifetime of a catalyst layer.

  Further, since the swirl vanes are stationary, no power is required to rotate the swirl vanes, and the structure of the catalytic combustion apparatus is not complicated. Further, since air and gas are separately supplied to the mixed gas heating chamber, the gas does not burn unexpectedly except in the mixed gas heating chamber, and the safety of the catalytic combustion apparatus is high.

  According to a second aspect of the present invention, in the catalytic combustion apparatus of the first aspect, the gas discharge port is provided on the bottom surface of the gas mixing unit separately from the combustion unit. According to this embodiment, the gas supplied from the gas discharge port can be supplied to the gas mixing unit while preheating by the combustion unit, and the gas and air can be mixed so as to have a more uniform temperature distribution. it can. Further, since the combustion part and the gas discharge port can be integrated on the bottom surface of the gas mixing part, the catalytic combustion apparatus can be made compact.

  The embodiment described in claim 3 is the catalytic combustion apparatus according to claim 1 or 2, wherein the combustion section burns a part of the gas supplied to the gas mixing section. . According to such an embodiment, a part of the gas to be burned in the catalyst layer can be led to the combustion part and burned in the combustion part, so there is no need for a means for separately supplying gas to the combustion part, and the catalytic combustion apparatus The structure can be simplified.

  According to an embodiment of the present invention, in the catalytic combustion apparatus according to claim 1, 2, or 3, the swirl vane is arranged in a cylindrical shape, the air is provided at the center of the swirl vane. Arranged to flow from the direction perpendicular to the axis into the space surrounded by the swirl vanes, and the gas outlet is arranged so that the gas flows from the direction parallel to the central axis of the swirl vanes into the space surrounded by the swirl vanes It is characterized by that. According to such an embodiment, gas can be supplied from a direction perpendicular to the swirling direction of the mixed gas swirled by swirl blades in the gas mixing unit (or a direction parallel to the central axis of the swirl blades), Gas and air can be mixed more uniformly.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, it is needless to say that the present invention is not limited to the embodiments described below, and the design can be changed as appropriate.

  FIG. 1 is a schematic sectional view showing a catalytic combustion apparatus 11 according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line XX of FIG. The catalytic combustion apparatus 11 includes a gas burner 12, a gas mixing and heating unit 13 (gas mixing unit), and a catalyst layer 14 in order from the bottom.

  The gas burner 12 includes an annular gas chamber 15, and a combustion port 16 is formed in an annular shape in the upper surface plate 19 of the gas burner 12 in the inner periphery of the gas chamber 15, and further, an upper surface plate 19 is formed outside the combustion port 16. A plurality of gas discharge ports 17 are opened. The gas burner 12 is connected to a gas supply pipe 18 for supplying gas into the gas chamber 15. In addition, in the example of illustration, although the gas mixing heating part 13 and the gas burner 12 are integrally formed, these may be comprised separately.

  The gas mixing and heating unit 13 is formed in a substantially cylindrical shape, the lower surface center portion thereof is blocked by a bottom plate (the upper surface plate 19 of the gas burner 12), and the mixed gas outlet 20 is opened at the upper surface center portion. In addition, a plurality of pipe-like air supply ports 21 are provided on the circumferential body surface (outer circumferential surface) of the gas mixing and heating unit 13.

  A swirl vane 22 is provided in the gas mixing and heating unit 13 in a cylindrical shape so as to surround a space between the bottom plate and the mixed gas outlet 20. The inside of the gas mixing and heating unit 13 is partitioned by a cylindrical region in which the swirl vanes 22 are arranged, the air supply port 21 is positioned outside the swirl vanes 22, and the catalyst layer 14 is a mixed gas outlet. 20 faces a space inside the swirl vane 22 in the gas mixing and heating unit 13 (hereinafter referred to as a heating chamber 23), and the gas discharge port 17 is connected to the heating chamber 23 in the gas mixing and heating unit 13. Facing. The combustion port 16 of the gas burner 12 is disposed so as to protrude into the heating chamber 23 from below.

  As shown in FIG. 2, the swirl vane 22 is composed of a plurality of vanes 26 standing up and down, and each vane plate 26 is inclined in a spiral shape so that the gap between the vanes 26 extends from the outside to the inside. And the air can pass through. The air supply port 21 is arranged so that the length direction thereof faces a circular tangential direction that forms the outer peripheral surface of the gas mixing and heating unit 13, and is supplied when air is supplied from the air supply port 21. The generated air flows in a spiral shape in the gas mixing and heating unit 13 along the circumferential direction.

  As the catalyst layer 14, for example, a platinum catalyst can be used, but other catalysts may be used. For example, the catalyst is not limited to a metal catalyst, and may be a ceramic catalyst.

  Next, the operation until the gas is completely burned by the catalyst in the catalytic combustion apparatus 11 will be described. A gas or a low mixed gas is fed into the gas chamber 15 of the gas burner 12. The low mixed gas here is a mixed gas of gas and air, but is a mixed gas having an air amount of less than or equal to the theoretical air amount m = 1. That is, the mixing ratio of air is smaller than the mixing ratio of air at the optimum combustion ratio of gas and air. Part of the gas or low-mixed gas fed into the gas chamber 15 is discharged from the combustion port 16 into the heating chamber 23, and part of the gas is discharged from the gas discharge port 17 to the vicinity of the swirl vane 22 in the heating chamber 23. Is done.

  On the other hand, when air is blown into the gas mixing and heating unit 13 from the air supply port 21, it is blown into the gas mixing and heating unit 13 in a spiral shape along the circumferential direction as shown in FIG. Therefore, since the air blown into the gas mixing and heating unit 13 flows along the inner surface of the peripheral drum portion of the gas mixing and heating unit 13, the temperature rise of the peripheral drum surface of the gas mixing and heating unit 13 is suppressed. Then, the air supplied to the gas mixing and heating unit 13 is supplied into the heating chamber 23 while being swirled in a spiral shape by passing between the blade plates 26 of the swirling blades 22.

  Accordingly, the gas or the low mixed gas is supplied from the gas discharge port 17 into the heating chamber 23 and the air is supplied from the air supply port 21, and the gas or the low mixed gas and the air are mixed in the heating chamber 23. The Here, the amount of air supplied to the gas mixing and heating unit 13 is such that the amount of mixed gas in the heating chamber 23 is about three times the theoretical amount of air. This is because catalytic combustion requires about three times the theoretical air volume. Therefore, the mixed gas in the heating chamber 23 is a lean mixture, and the mixed gas does not burn even if heated in the heating chamber 23 before the catalyst layer 14.

  The gas or low mixed gas and air sent into the heating chamber 23 are forcibly swirled by the flow of air sent into the heating chamber 23 by the swirl vanes 22 and swirled in a spiral shape. And evenly stirred. Therefore, according to this catalytic combustion device 11, the gas in the heating chamber 23 or the low mixed gas and the air can be sufficiently stirred. Further, in the first embodiment, the gas or the low mixed gas is supplied from the gas discharge port 17 perpendicularly to the swirling direction of the mixed gas swirling in the heating chamber 23 (that is, in parallel with the central axis of the swirling blade 22). Since the gas is discharged, the gas or the low mixed gas and the air can be mixed very efficiently.

  Further, when the low mixed gas is discharged from the gas discharge port 17, the mixed gas (m = 1 or less) has already been obtained. Therefore, when the gas not mixed with air is discharged from the gas discharge port 17. In comparison, the low gas mixture is in a state where it is very easy to mix with air.

  The gas or low mixed gas discharged from the combustion port 16 into the heating chamber 23 is ignited and burned at the combustion port 16. Therefore, the mixed gas in the heating chamber 23 is heated by the combustion heat of the gas combusted at the combustion port 16. The reason why the gas or the low mixed gas is burned at the combustion port 16 is that the mixed gas needs to be heated to a certain temperature or higher in order to cause the catalytic reaction to completely burn the gas. However, as described above, the gas in the heating chamber 23 is not burned by heating.

  Since the mixed gas in the heating chamber 23 swirls in the heating chamber 23 as described above, the mixed gas in the heating chamber 23 is uniformly heated.

  In this way, the mixed gas that has been sufficiently uniformly mixed and heated is sent to the catalyst layer 14 and is catalytically burned in the catalyst layer 14. Therefore, the gas is completely burned in the catalyst layer 14 and the generation of nitrogen oxides and the like is suppressed.

  Further, according to the catalytic combustion device 11, a part of the supplied gas is combusted, the mixed gas is heated by using the heat, and the mixed gas is swirled by the swirl vanes 22, thereby mixing the mixed gas. Can be uniformly mixed and heated uniformly. As a result, in the catalyst layer 14, a mixed gas having a uniform concentration and a uniform temperature can be burned, and each region of the catalyst layer 14 is maintained at a substantially constant temperature. Therefore, there is little possibility that the catalyst layer 14 is deteriorated by sintering or the like, and the life of the catalyst layer 14 is also extended.

  In addition, in such a catalytic combustion device 11, the same effect can be obtained even if a mixture of gas and air is jetted from the air supply port 21 to the heating chamber 23 in advance. May spread to the air supply port 21 side due to flashback. On the other hand, if the gas is supplied from the gas outlet 17 separately from the air as in the first embodiment, only a flame is formed at the gas outlet 17 even in the worst case. Since the above flashback does not occur, it can be used safely.

FIG. 1 is a schematic sectional view showing the structure of a catalytic combustion apparatus according to Embodiment 1 of the present invention. 2 is a cross-sectional view taken along line XX of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Catalytic combustion apparatus 12 Gas burner 13 Gas mixing heating part 14 Catalyst layer 15 Gas chamber 16 Combustion port 17 Gas discharge port 18 Gas supply pipe 19 Upper surface plate 20 Mixed gas blower outlet 21 Air supply port 22 Swirling blade 23 Heating chamber 26 Blade plate

Claims (4)

A gas mixing unit for mixing gas and air, a gas discharge port for supplying gas to the gas mixing unit, an air supply port for supplying air to the gas mixing unit, and a gas supplied to the gas mixing unit In a catalytic combustion apparatus comprising a combustion section for heating a mixed gas of air and air, and a catalyst layer for burning the mixed gas mixed and heated in the gas mixing section,
A catalytic combustion apparatus characterized in that a swirl vane for swirling air supplied to the gas mixing section to mix air and gas in the mixing section is provided in the gas mixing section.   2. The catalytic combustion apparatus according to claim 1, wherein the gas discharge port is provided on a bottom surface of the gas mixing unit separately from the combustion unit.   The catalytic combustion apparatus according to claim 1 or 2, wherein the combustion section burns a part of the gas supplied to the gas mixing section.   The swirl vane is disposed in a cylindrical shape, and the air supply port is disposed such that air flows into a space surrounded by the swirl vane from a direction perpendicular to the central axis of the swirl vane, and the gas discharge port is 4. The catalytic combustion apparatus according to claim 1, wherein the gas is arranged so as to flow into a space surrounded by the swirl vanes from a direction parallel to the central axis of the swirl vanes.

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