JP6430339B2 - Flameless combustion equipment - Google Patents

Description

  The present invention relates to a flameless combustion apparatus for generating flameless oxidation inside a furnace.

  Flameless combustion means that when an oxidant gas having a volume concentration of oxygen as an oxidizer of 13 [%] or less is mixed with fuel gas at a high temperature of 1200 [K] or more with two significant figures, A phenomenon in which all combustible gas components are oxidized without forming a visible fire (visible flame). In this flameless combustion, the heat of oxidation of the combustible part of the fuel gas can be recovered with higher thermal efficiency than in normal combustion, and the amount of nitrogen oxides generated is very high (for example, it cannot be detected by a detection device). There is a merit that it is less.

  Here, high temperature combustion is known as a phenomenon having advantages similar to flameless combustion. This high-temperature combustion is a combustion phenomenon when fuel is burned in a state in which normal air having an oxygen concentration or air having a reduced oxygen concentration is heated to a high temperature of about 1200 [K], for example. This high temperature combustion has the merit that the combustion heat of the fuel can be recovered with higher thermal efficiency than the normal combustion. In addition, there is a part of literature in which the generation amount of nitrogen oxides is suppressed in high-temperature combustion compared to normal combustion (see, for example, Patent Document 2 below. Is a phenomenon of the same kind as “hot combustion” in this specification. However, the amount of nitrogen oxide generated in high-temperature combustion is larger than the amount of nitrogen oxide generated in flameless combustion.

  For a flameless combustion apparatus that generates flameless combustion, for example, a technique described in Patent Document 1 below is known. In this technique, gaseous fuel and oxygen-containing gas are supplied to a closed radiant tube and ignited to heat the inside of the radiant tube, and a part of the generated combustion gas is discharged to the outside. At this time, the oxygen-containing gas is heated by heat exchange between the exhausted combustion gas and the oxygen-containing gas supplied into the radiant tube, and the oxygen-containing gas is mixed with the combustion gas in the radiant tube to raise the temperature while increasing the temperature. Reduce the concentration. Thereby, flameless combustion in which the gaseous fuel is oxidized by the oxygen-containing gas is realized in the radiation tube.

JP 2006-500743 A Japanese Patent No. 5216369

  In the technique described in Patent Document 1, flameless combustion can be performed on the oxygen-containing gas by mixing the combustion gas and the oxygen-containing gas in the radiation tube when flameless combustion is caused in the radiation tube. The temperature and oxygen concentration of oxidant gas are used. Here, when the technique of Patent Document 1 is applied to a furnace to cause flameless combustion inside the furnace, the oxygen-containing gas is mixed by mixing the combustion gas and the oxygen-containing gas in the furnace. Is converted to an oxidant gas having a temperature and oxygen concentration capable of flameless combustion. For this reason, when the technique of the above-mentioned patent document 1 is applied to a furnace in which the internal temperature fluctuates, when the temperature in the furnace fluctuates, the temperature of the combustion gas in the furnace fluctuates, and this combustion The oxidant gas mixed with the gas may reach a temperature at which flameless combustion cannot be realized. That is, when the technique described in Patent Document 1 is applied to a furnace whose internal temperature varies, flameless combustion cannot be stably generated inside the furnace.

  The present invention makes it possible to stably generate flameless combustion in a furnace regardless of fluctuations in temperature in the furnace by supplying a combustion gas necessary for flameless combustion from a flameless combustion apparatus. Is.

  In order to solve the above problems, the flameless combustion apparatus of the present invention takes the following means.

  A first invention is a flameless combustion apparatus that is provided in a furnace and causes flameless combustion inside the furnace. This flameless combustion apparatus includes a fuel gas flow path for supplying fuel gas to be oxidized by flameless combustion to the inside of the furnace through a nozzle. Further, the flameless combustion apparatus includes an oxidant gas flow path that supplies an oxidant gas that oxidizes fuel gas in the flameless combustion to the inside of the furnace through a nozzle. Here, the nozzle of the oxidant gas passage is provided at a position away from the nozzle of the fuel gas passage by a distance longer than the distance at which the oxidant gas and the fuel gas are diffused and mixed with each other and burned. ing. In addition, the flameless combustion apparatus includes an exhaust passage for exhausting generated gas generated after the fuel gas is oxidized in flameless combustion to the outside of the furnace. The flameless combustion apparatus also includes a heat exchange device that heats the oxidant gas in the oxidant gas flow path with the thermal energy of the generated gas in the exhaust flow path. Further, the flameless combustion apparatus is supplied with air and fuel, and the lean concentration in which the fuel is completely burned at an air-fuel ratio larger than the stoichiometric air-fuel ratio, the volume concentration of oxygen gas is less than 13 [%], and And a combustion gas generating device for generating combustion gas having a temperature higher than 1200 [K] by two significant digits. In addition, the flameless combustion device releases the combustion gas generated by the combustion gas generator into the furnace and realizes mixing of the combustion gas and the oxidant gas from the oxidant gas flow path inside the furnace. It has a road.

According to the flameless combustion apparatus of the first aspect of the present invention, the combustion gas is discharged from the combustion gas generator into the furnace and mixed with the oxidant gas, whereby the mixed gas containing the oxidant gas is flamelessly burned. Possible temperatures and oxygen concentrations can be achieved. Accordingly, it is possible to provide a flameless combustion apparatus capable of stably generating flameless combustion in the furnace regardless of temperature fluctuations in the furnace. According to the first aspect of the invention, in the combustion gas generator, the combustion gas is generated by lean combustion in which the fuel is completely burned at an air fuel ratio larger than the stoichiometric air fuel ratio. This lowers the combustion temperature of the fuel to reduce the amount of thermal NO _x (nitrogen oxide generated by the oxidation of nitrogen gas in the air when things burn at high temperatures) and It is possible to eliminate generation of nitrogen oxides due to combustion of combustible fuel by oxidant gas. According to the first aspect of the invention, diffusion combustion in which the oxidant gas and the fuel gas are diffused and mixed with each other and burned by separating the nozzle of the oxidant gas channel from the nozzle of the fuel gas channel. It is difficult to generate (diffusion combustion), and generation of nitrogen oxides by this diffusion combustion can be suppressed.

  Next, according to a second aspect of the present invention, in the first aspect described above, the combustion gas generator includes a combustion chamber, a pilot burner, a fuel discharge nozzle, and an air injection nozzle, which will be described later. . Here, the combustion chamber is formed in a cylindrical shape that is coaxial with the discharge path. The pilot burner also generates a spark for igniting the fuel at the center of the combustion chamber. The fuel discharge nozzle discharges the fuel so as to swirl around the igniter from a position around the igniter and away from the inner wall surface of the combustion chamber. The air ejection nozzle ejects room temperature air so as to swirl along the inner wall surface of the combustion chamber in the same direction as the swirling of the fuel.

  According to the second aspect of the present invention, the air jetted from the air jet nozzle is swirled around the spark in the combustion chamber of the combustion gas generator. A swirling flame is formed that burns fuel from the discharge nozzle. As a result, it is possible to suppress the disappearance of the spark and the swirling flame ignited by the spark in the combustion chamber, and to realize stable discharge of the combustion gas. Further, according to the configuration in which the combustion chamber is formed in a cylindrical shape coaxial with the combustion gas discharge path, the air swirling along the inner wall surface of the combustion chamber and the combustion gas discharged into the furnace by the swirling flame are swirled. Thus, mixing of the combustion gas and the oxidant gas from the oxidant gas flow path can be promoted. In addition, according to the configuration in which the air jetted along the inner wall surface of the combustion chamber is at room temperature, combustion at the normal temperature air is interposed between the swirling flame and the inner wall surface of the combustion chamber, and combustion by the heat of the swirling flame is performed. Damage to the room can be suppressed without using a temperature control device.

  Further, according to a third aspect of the present invention, in the first or second aspect, the nozzle of the fuel gas flow path is located from a position along the discharge area where the combustion gas is discharged from the discharge path inside the furnace from the discharge path. The fuel gas is supplied in a flow along the flow of the combustion gas discharged to the discharge area. In the third aspect of the invention, the nozzle of the oxidant gas flow path supplies the oxidant gas in a flow that collides with the flow of the combustion gas discharged from the discharge path to the discharge area.

  According to the third aspect of the invention, the oxidant gas from the oxidant gas passage is mixed with the combustion gas after the flow collides with the flow of the combustion gas from the discharge passage, and then from the fuel gas passage. Contact with fuel gas to cause flameless combustion. Thereby, it can be avoided that the oxidant gas before being mixed with the combustion gas comes into contact with the fuel gas and the fuel gas is burned, and nitrogen oxides are generated by this combustion.

It is principal part sectional drawing showing the crucible furnace 90 provided with the flameless combustion apparatus 10 concerning one Embodiment of this invention. It is the II-II sectional view taken on the line of FIG. FIG. 3 is a view taken along line III in FIG. 1. It is the IV-IV line end surface arrow directional view of FIG. FIG. 3 is a cross-sectional view similar to FIG. 2, showing a driving state of the frameless combustion apparatus 10. FIG. 3 is a view taken along line VI in FIG. 2. It is the graph showing reaction of the propane gas mixed with the mixed gas containing oxygen gas. It is the elements on larger scale of FIG. It is the IX-IX line end surface arrow directional view of FIG.

  A configuration of a flameless combustion apparatus 10 according to an embodiment of the present invention will be described with reference to FIGS. 1 to 9. In the following, detailed description of the incidental components such as bolts and insertion holes for attaching the frameless combustion apparatus 10 to the furnace body 90B (see FIG. 1) of the crucible furnace 90 will be omitted.

  As shown in FIG. 1, the flameless combustion apparatus 10 is a flameless combustion apparatus provided in a furnace body 90 </ b> B of a crucible furnace 90 corresponding to a “furnace” in the present invention. Here, in the crucible furnace 90, a crucible 90A in which an aluminum ingot 92 is placed is set in a crucible furnace 90 covered with a furnace body 90B and a furnace lid 90C, and the ingot 92 in the crucible 90A is set. It is a crucible furnace that is melted to make a molten metal 92A.

  The flameless combustion apparatus 10 generates flameless combustion inside the crucible furnace 90 to supply heat energy for melting the metal base 92. The flameless combustion that occurs in the crucible furnace 90 uniformly increases the temperature in the crucible furnace 90 and does not emit a visible fire (visible flame). It is not possible to identify and illustrate whether this occurs.

  As shown in FIGS. 1 to 3, the flameless combustion apparatus 10 is formed in a generally cylindrical shape as a whole, and has a configuration in which a disk-shaped flange 10 </ b> A is projected on the outer peripheral side of the cylinder. And the flameless combustion apparatus 10 is penetrated by the wall of the furnace body 90B, and the part which becomes an outer side (lower side as viewed in FIG. 2) and the flange 10A are brought into contact with each other and bolted. Thus, it can be attached to the furnace body 90B.

  Further, in the flameless combustion apparatus 10, a portion protruding outside the crucible furnace 90 (lower side as viewed in FIG. 2) was installed adjacent to the crucible furnace 90 as shown in FIGS. 1 and 2. Embedded in the supply device 91. The supply device 91 can separately supply petroleum gas mainly composed of propane gas and air at normal temperature from a plurality of locations.

  As shown in FIG. 5, the flameless combustion apparatus 10 supplies air 93 </ b> B and fuel gas 93 </ b> A to the inside of the crucible furnace 90 when the flameless combustion is generated inside the crucible furnace 90. The fuel gas 93A is oxidized using the air 93B as an oxidant gas. Here, the air 93 </ b> B is air supplied from the supply device 91, and is sent to the oxidant gas flow path 12 provided in the frameless combustion apparatus 10, and the nozzle provided in the oxidant gas flow path 12. It is supplied to the inside of the crucible furnace 90 through 12A. The fuel gas 93 </ b> A is a petroleum gas supplied from the supply device 91, and is sent to the fuel gas passage 11 provided in the frameless combustion device 10, and the nozzle 11 </ b> A provided in the fuel gas passage 11. Is supplied to the inside of the crucible furnace 90.

  It should be noted that the nozzle 12A of the oxidant gas flow channel 12 and the nozzle 11A of the fuel gas flow channel 11 are from the distance at which diffusion combustion occurs where air 93B and fuel gas 93A diffuse and mix with each other. Preferably, they are separated from each other by a long distance. By doing in this way, it is hard to generate | occur | produce the diffusion combustion of the fuel gas 93A by the air 93B, and it can suppress that nitrogen oxide is generated by this diffusion combustion.

  Further, a high temperature (eg, about 1300 [K]) generated gas 93D generated after the fuel gas 93A is oxidized in the flameless combustion is a cylindrical (see FIG. 3) exhaust flow provided in the flameless combustion apparatus 10. The gas is exhausted to the outside of the crucible furnace 90 through the path 13A. Here, as shown in FIGS. 1 and 2, a chimney 10B extending upward (upward as viewed in FIG. 1) is connected to the exhaust flow path 13A, so that exhaust through the chimney 10B can be performed. ing.

  Incidentally, the air supplied from the supply device 91 is air having a volume concentration of oxygen gas of about 20 [%] and a temperature of about 300 [K], and the fuel gas 93A (see FIG. 8), which is petroleum gas, is used as a flame. In order to make the combustion less, it is necessary to reduce the oxygen concentration and raise the temperature. For this reason, as shown in FIG. 5, the flameless combustion apparatus 10 includes a heat exchange device 13 that heats the air 93B flowing through the oxidant gas flow channel 12 using the generated gas 93D in the exhaust flow channel 13A. . Further, the flameless combustion apparatus 10 generates combustion gas 93C having a higher oxygen concentration at a higher temperature than the air 93B heated by the heat exchange device 13 by burning the fuel 95B with the air 95C from the supply device 91. A combustion gas generator 14 is provided. Here, the combustion gas 93 </ b> C is mixed with the air 93 </ b> B heated by the heat exchange device 13, thereby further raising the temperature of the air 93 </ b> B and reducing the oxygen concentration thereof.

  The heat exchanging device 13 is a thin tube in which the exhaust passage 13A is divided into a large number (for example, 180) of cylinders between a cylindrical inner tube 13B and a cylindrical outer tube 13C surrounding the inner tube 13B from the outside. 13D and a plurality of (for example, four) baffles 13E are arranged. Then, the heat exchange device 13 causes the air 93B from the supply device 91 to flow between the inner tube 13B and the outer tube 13C, and the heat energy of the generated gas 93D flowing through the narrow tube 13D of the exhaust passage 13A is converted into the air 93B. The air 93B is heated by moving it. At this time, each baffle 13E causes the air 93B flowing between the inner pipe 13B and the outer pipe 13C to meander to promote the movement of thermal energy from the generated gas 93D to the air 93B. In the present embodiment, the heat exchange device 13 reduces the temperature of the generated gas 93D from, for example, about 1300 [K] to about 700 [K], and the temperature of the air 93B, for example, from about 300 [K] to 1100 [K]. ] To a degree.

  As shown in FIG. 2, the combustion gas generator 14 is formed in a cylindrical shape and is coaxial with the combustion chamber 14B fitted into the inner tube 13B of the heat exchange device 13 and the central axis 14A of the cylinder of the combustion chamber 14B. And a discharge passage 15 formed in a cylindrical shape. In the present embodiment, the discharge passage 15 is formed as a thick-walled cylinder whose thickness decreases toward one side (upper side in FIG. 2), and the nozzle 12 </ b> A of the oxidant gas passage 12 and the fuel gas passage 11. It is integrated with the nozzle 11A.

  The combustion chamber 14B and the central axis 14A of the discharge passage 15 are set so as to extend between the crucible furnace 90 and the supply device 91. As a result, the combustion gas generator 14 and the heat exchange device 13 are disposed so as to extend from the supply device 91 toward the crucible furnace 90. Further, the discharge path 15 is disposed in a state in which the thickening side faces the combustion chamber 14B of the combustion gas generator 14, and the end of the combustion chamber 14B on the crucible furnace 90 side (upper side in FIG. 2). It is bolted via a counterbore 15A and a washer 15B.

  Further, at the end of the combustion chamber 14B of the combustion gas generator 14 opposite to the discharge path 15 (lower side in FIG. 2), a pilot burner 14D formed coaxially with the combustion chamber 14B, a fuel discharge nozzle 14E, And the air ejection nozzle 14I is inserted. Here, the air ejection nozzle 14I is inserted into the combustion chamber 14B and fitted to be coaxial with the combustion chamber 14B, and further, is an end opposite to the combustion gas generator 14 (lower side in FIG. 2). Is assembled to the base 10C. In addition, the pilot burner 14D and the fuel discharge nozzle 14E are assembled to the base 10C together with the air injection nozzle 14I at the ends opposite to the combustion gas generator 14, so that the air injection nozzle 14I and the combustion chamber 14B are assembled. And be coaxial.

  As shown in FIG. 2, the pilot burner 14D includes a spark rod 14J disposed so as to extend in a rod shape along the central axis 14A, a cylindrical inner tube 14C surrounding the spark rod 14J from the outside, And a cylindrical outer tube 14G surrounding the tube from the outside. Here, as shown in FIG. 6, the inner tube 14C, the outer tube 14G, and the spark rod 14J are coaxially connected to each other by connecting the end portions on the side inserted into the combustion chamber 14B via a spacer 14H. Has been. In this embodiment, the spacer 14H covers the end of the inner tube 14C on the combustion chamber 14B side, and is provided in a state where four spokes are extended toward the spark rod 14J and three spokes are extended toward the outer tube 14G. Yes.

  Further, in the pilot burner 14D, as shown in FIGS. 4 and 8, the inner pipe 14C is supplied with the oil gas 94A from the supply device 91, and releases the oil gas 94A into the combustion chamber 14B (see FIG. 4). It is supposed to be. Further, the outer pipe 14G is configured such that air 95A is sent from the supply device 91A and the air 95A is discharged around the petroleum gas 94A released from the inner pipe 14C. Then, as shown in FIG. 4, the spark rod 14J ignites the petroleum gas 94A (see FIG. 8) discharged from the inner tube 14C by spark discharge, so that the crucible furnace 90 side along the central axis 14A ( In FIG. 4, an igniter 94 that spouts upward is generated at the center of the combustion chamber 14B.

  Further, as shown in FIGS. 3 and 6, the fuel discharge nozzle 14E is formed in a cylindrical shape surrounding the pilot burner 14D from the outside. Then, as shown in FIG. 5, the fuel discharge nozzle 14 </ b> E uses the petroleum gas sent from the supply device 91 as the fuel 95 </ b> B, and this fuel 95 </ b> B is coaxial with the starter 94 around the starter 94 in the combustion chamber 14 </ b> B. It is designed to be ejected.

  Further, as shown in FIG. 4, the air ejection nozzle 14I is provided so as to surround the fuel discharge nozzle 14E from the outside and to separate the fuel discharge nozzle 14E from the inner wall surface of the combustion chamber 14B of the combustion gas generator 14. Yes. The air ejection nozzle 14I ejects normal temperature air 95C sent from the supply device 91, thereby realizing the combustion of the fuel 95B using the igniter 94 as an ignition source. As a result, the combustion gas generator 14 discharges the combustion gas 93C generated by the combustion of the fuel 95B to the discharge area 93 set inside the crucible furnace 90 via the discharge path 15, and the inside of the crucible furnace 90 Mixing of air 93B and combustion gas 93C is realized.

  Incidentally, the amount of the air 95C supplied from the supply device 91 is set so as to realize lean combustion in which the fuel 95B supplied from the supply device 91 is completely burned at an air / fuel ratio larger than the stoichiometric air / fuel ratio. More specifically, the amount of the air 95C is such that the combustion gas 93C generated when the fuel 95B is lean-burned has a volume concentration of oxygen gas of 3 [%] to less than 13 [%], and the temperature is an effective number 2 The gas mixture is set to be higher than 1200 [K] in terms of digits.

  Here, the meaning of each of the above conditions will be described with reference to FIG. In a mixed gas containing oxygen gas, the temperature is relatively low (for example, less than 1200 [K] with two significant figures), and the volume concentration of the oxygen gas is relatively high (see “normal combustion” in FIG. 7). When applicable, the propane gas mixed in the gas mixture is burned by normal combustion or high temperature combustion when an ignition source is applied. In this mixed gas, when the volume concentration of the oxygen gas decreases, the propane gas mixed in the mixed gas has its combustible component in the mixed gas depending on whether incomplete combustion occurs or combustion is stopped. (Refer to the area of “combustible matter remains” in FIG. 7).

  Further, when the temperature of the mixed gas is relatively high and the volume concentration of the oxygen gas is relatively high (corresponding to “high temperature combustion” in FIG. 7), the propane gas mixed in the mixed gas does not depend on the ignition source. It is spontaneously ignited and burned by high temperature combustion. In this mixed gas, when the volume concentration of the oxygen gas decreases, the propane gas mixed in the mixed gas is oxidized by flameless combustion using the mixed gas as an oxidant gas (see “Frame” in FIG. 7). Refer to the “Less combustion” area). However, when the volume concentration of oxygen gas in the mixed gas becomes very low (for example, less than 3%), the flammable component of the propane gas mixed in the mixed gas remains in the mixed gas (see “Combustible component in FIG. 7”). See “Remaining”).

  That is, the above-mentioned conditions “the volume concentration of oxygen gas is less than 13 [%]” and “the temperature is higher than 1200 [K] by two significant digits” are the mixed gas of the combustion gas 93C and the air 93B. The fuel gas 93A containing propane gas as a main component is set to enable flameless combustion. In addition, the above-mentioned condition that “the volume concentration of oxygen gas is 3 [%] or more” is that propane gas is a main component in the combustion gas 93C that is a mixed gas having a temperature of 1200 [K] or more in two significant figures. Is set so that no combustible component of the fuel 95B remains.

  According to each configuration described above, the combustion gas 93C is discharged from the combustion gas generator 14 to the discharge area 93 set inside the crucible furnace 90 and mixed with the air 93B heated by the heat exchange device 13, The mixed gas containing the air 93B can be set to a temperature at which flameless combustion is possible (at least two significant digits, 1200 [K] or more) and an oxygen concentration (volume concentration of oxygen gas is 13 [%] or less). Thus, it is possible to provide a flameless combustion apparatus 10 capable of stably generating flameless combustion inside the crucible furnace 90 regardless of temperature fluctuations inside the crucible furnace 90 (see FIG. 1). Can do. Further, by making the combustion of the fuel 95B lean, the combustible part of the fuel 95B is completely combusted so that it does not remain in the combustion gas 93C, and the combustible part of the fuel 95B remaining in the combustion gas 93C becomes the air 93B. It is possible to eliminate generation of nitrogen oxides by combustion.

Here, air is a mixed gas containing oxygen gas having a volume concentration of about 20 [%] and an inert gas having a volume concentration of about 80 [%]. Part of the heat is spent on increasing the internal energy of the inert gas. For this reason, when the combustion of the fuel 95B for generating the combustion gas 93C is lean combustion, the combustion heat that the inert gas in the air 95C spends on increasing its internal energy is increased, and the combustion temperature of the fuel 95B is lowered. Become. As a result, it is possible to reduce the generation amount of thermal NO _x which is a nitrogen oxide generated by oxidizing the nitrogen gas in the air 93B when the object burns at a high temperature. In addition, when the combustion of fuel (e.g., gasoline) that is vaporized during combustion is lean combustion, the combustion temperature of the fuel may increase due to reduction of the influence of the heat of vaporization absorbed by the fuel. Since the fuel 95B combusted in the apparatus 14 is petroleum gas supplied from the supply apparatus 91, it is not necessary to consider the influence of the heat of vaporization.

  By the way, as shown in FIG. 4, the fuel discharge nozzle 14 </ b> E discharges the fuel 95 </ b> B through a swirler 14 </ b> F having a plurality of holes (for example, 10 holes, see FIGS. 3 and 9). Yes. Here, as shown in FIGS. 3 and 6, the openings of the swirler 14F are provided at equal intervals along the inner wall surface of the combustion chamber 14B, and each of the openings is on one side in the circumferential direction of the cylinder of the fuel discharge nozzle 14E. It is inclined toward (see FIG. 6). Thereby, as shown in FIGS. 4 and 6, the fuel discharge nozzle 14 </ b> E ejects and discharges the fuel 95 </ b> B so as to turn around the spark 94 (see FIG. 4).

  Further, as shown in FIG. 5, the air 95C ejected from the air ejection nozzle 14I is fed into the inner tube 13B of the heat exchange device 13 from the supply device 91 and is provided integrally with the peripheral wall of the combustion chamber 14B. The air jet nozzle 14I is supplied through the flow path 14K. Here, as shown in FIG. 9, a plurality of (for example, four) air flow paths 14 </ b> K are arranged at equal intervals along the inner side surface of the air ejection nozzle 14 </ b> I, and one of the directions along the inner side surface is arranged. Air 95C is ejected to the side (clockwise in FIG. 9). Thereby, as shown in FIGS. 5 and 6, the air ejection nozzle 14 </ b> I ejects air 95 </ b> C so as to swirl along the inner wall surface of the combustion chamber 14 </ b> B. In addition, as shown in FIG. 6, the turning direction of the air 95C ejected from the air ejection nozzle 14I is set to be the same direction as the turning direction of the fuel 95B discharged from the fuel discharge nozzle 14E. .

  According to each configuration described above, as shown in FIG. 4 and FIG. 5, the combustion gas generating device 14 is sprayed around the spark 94 so as to be swung from the air ejection nozzle 14 </ b> I using the spark 94 as an ignition source. The swirling flame 95 is formed in which the air 95C that is swirled burns the fuel 95B from the fuel discharge nozzle 14E that is also swirled. Thereby, it is possible to suppress the disappearance of the flame 94 and the swirling flame 95 in the combustion chamber 14B, and to realize stable discharge of the combustion gas 93C. Further, according to the configuration in which the combustion chamber 14B of the combustion gas generator 14 is formed in a cylindrical shape that is coaxial with the discharge path 15 of the combustion gas 93C, the air 95C and the swirling flame 95 swirl along the inner wall surface of the combustion chamber 14B. The vortex can be generated in the combustion gas 93 </ b> C released into the crucible furnace 90. Then, mixing of the combustion gas 93C and the air 93B from the oxidant gas flow path 12 can be promoted. Further, air 95C ejected along the inner wall surface of the combustion chamber 14B is used as room temperature air from the supply device 91, so that room temperature air 95C is interposed between the swirling flame 95 and the inner wall surface of the combustion chamber 14B. Thus, damage to the combustion chamber 14B due to the heat of the swirling flame 95 can be suppressed without using a temperature control device.

  In the flameless combustion apparatus 10, the fuel gas flow path 11 is formed from a plurality of locations (for example, four locations) of an annular tube from the crucible furnace 90 side (upper side as viewed in FIG. 2) as shown in FIGS. 2 and 3. ) Is provided with a branch channel 11B formed to extend the branch. As shown in FIG. 2, a nozzle 11A is connected to each branch of the branch channel 11B via a connecting hole 15C opened in a washer 15B. As shown in FIGS. 3 and 5, each nozzle 11A is disposed so as to extend in parallel with the central axis 14A of the discharge path 15, and inside the crucible furnace 90, the combustion gas 93C (FIG. 5) is discharged from the discharge path 15. Is opened at a position along the discharge area 93 from which the reference is discharged. As shown in FIG. 5, each nozzle 11 </ b> A supplies the fuel gas 93 </ b> A through the opening along the flow of the combustion gas 93 </ b> C discharged from the discharge path 15 to the discharge area 93. Yes.

  Further, in the flameless combustion apparatus 10, the oxidant gas flow path 12 has a ring-shaped ring portion as an outlet of the air 93B (see FIG. 4) from the heat exchange device 13, as shown in FIGS. It is formed as a circulation path 12B. As shown in FIG. 4, a plurality of (for example, four) nozzles 12A are connected to the ring ring passage 12B through connecting holes 15D opened at a plurality of positions (for example, four) of a washer 15B. Yes. Each nozzle 12A is disposed in an inclined state so as to extend toward the central axis 14A of the discharge path 15, and is opened at a position along the discharge area 93 described above. And each nozzle 12A supplies air 93B by the flow which collides with the flow of the combustion gas 93C discharge | released from the discharge path 15 to the discharge area 93 from the opening.

  According to each configuration described above, as shown in FIG. 5, the air 93B from the oxidant gas flow path 12 collides with the flow of the combustion gas 93C from the discharge path 15 and is mixed with the combustion gas 93C. After that, contact with the fuel gas 93A from the fuel gas flow path 11 causes flameless combustion (not shown). As a result, it is possible to avoid that the air 93B before being mixed with the combustion gas 93C comes into contact with the fuel gas 93A to burn the fuel gas 93A and generate nitrogen oxides by this combustion.

  Further, in the frameless combustion apparatus 10, as shown in FIGS. 2 and 3, a pyrometer 91A and a flame detection apparatus 91B each formed in a rod shape are respectively provided in the base 10C through a cylinder of the fuel discharge nozzle 14E. It is inserted so that it may be exposed on the inner side (upper side in FIG. 2). Here, the pyrometer 91A measures the temperature in the crucible furnace 90 by sensing heat radiation from the inside of the crucible furnace 90, and outputs the measurement result to the outside. Further, the flame detection device 91B detects each combustion state of the spark 94 and the swirling flame 95 by sensing the brightness of the spark 94 and the swirling flame 95 (see FIG. 5) in the combustion chamber 14B and fluctuations in this brightness. The detection result is output to the outside.

  Next, an operation procedure for generating flameless combustion in the crucible furnace 90 using the above-described flameless combustion apparatus 10 will be described. Note that in the following, detailed description of ancillary operations such as a return operation for the extinction of the spark 94 (see FIG. 4) will be omitted.

  In generating flameless combustion inside the crucible furnace 90, an operator (not shown) of the flameless combustion apparatus 10 first supplies oil gas 94A and air 95A from the supply apparatus 91 to the pilot burner 14D (FIG. 8). Start). Further, the operator drives the spark rod 14J of the flameless combustion apparatus 10 to cause spark discharge. Thereby, the flameless combustion apparatus 10 generates the spark 94 at the center of the combustion chamber 14B (see FIG. 4).

  Next, the operator confirms the occurrence of the spark 94 by the output from the flame detection device 91B, and stops the driving of the spark rod 14J. Further, the operator starts the supply of the fuel 95B from the supply device 91 to the fuel discharge nozzle 14E and the supply of the air 95C from the supply device 91 to the air ejection nozzle 14I (see FIG. 5). As a result, a swirling flame 95 is generated inside the combustion chamber 14B in the flameless combustion apparatus 10.

  Subsequently, the operator starts the supply of the fuel gas 93 </ b> A from the supply device 91 to the fuel gas channel 11 and the supply of the air 93 </ b> B from the supply device 91 to the oxidant gas channel 12. At this time, since the generated gas 93D having a high temperature (for example, about 1300 [K]) has not yet been generated inside the crucible furnace 90, the air 93B is not heated by the heat exchanging device 13 and is not heated. Supplied in. Therefore, the fuel gas 93A supplied from the fuel gas passage 11 into the crucible furnace 90 is the air remaining in the crucible furnace 90 and the crucible using the ignition 94 or the swirling flame 95 in the combustion chamber 14B as an ignition source. It is burned by air 93B supplied into the furnace 90. This combustion is performed while a flame is emitted in the discharge area 93 in the crucible furnace 90, and the temperature in the crucible furnace 90 is increased, for example, to 1300 [K] or more in two significant figures.

  Here, the air that burns the fuel gas 93 </ b> A is mixed with the combustion gas 93 </ b> C from the combustion gas generator 14 to reduce the oxygen concentration. Therefore, in the crucible furnace 90, the fuel gas 93A generates soot by incomplete combustion of the fuel gas 93A, and the soot is heated by the combustion heat of the fuel gas 93A to make it shine. Is burned by. This luminous flame has the merit that the amount of heat radiation energy is larger than the flame generated when the fuel gas 93A is completely burned, and the temperature in the crucible furnace 90 can be increased more quickly.

  When the fuel gas 93A is combusted in the crucible furnace 90, the volume concentration of the oxygen gas in the crucible furnace 90 is reduced, and the generated high-temperature combustion gas (not shown) is discharged into the exhaust passage 13A and It is exhausted to the outside through the chimney 10B (see FIG. 1). At this time, the air 93 </ b> B supplied from the supply device 91 into the crucible furnace 90 is heated by the combustion gas passing through the narrow tube 13 </ b> D (see FIG. 5) of the exhaust passage 13 </ b> A, and further remains in the crucible furnace 90. And mixed with the combustion gas 93 </ b> C from the combustion gas generator 14. Thereby, the air 93 </ b> B supplied from the supply device 91 causes the fuel gas 93 </ b> A supplied into the crucible furnace 90 to flamelessly burn.

  The present invention is not limited to the appearance and configuration described in the above-described embodiment, and various modifications, additions, and deletions can be made without changing the gist of the present invention. For example, the following various forms can be implemented.

(1) The flameless combustion apparatus of the present invention is not limited to the one that uses petroleum as the oxidant gas and flamelessly burns petroleum gas. That is, the flameless combustion apparatus of the present invention can realize flameless combustion using any fuel gas such as city gas or natural gas instead of petroleum gas. The oxidant gas used for flameless combustion can be pure oxygen gas or any mixed gas in which the volume concentration of oxygen gas is 3% or more.

(2) The flameless combustion apparatus of the present invention is not limited to the one provided in a crucible furnace that melts an aluminum base metal to form a molten metal, and can achieve a target heating temperature by flameless combustion. It may be provided in any furnace. That is, the flameless combustion apparatus of the present invention can be provided in an annealing furnace used in, for example, plastic or glass annealing or metal annealing. Moreover, the flameless combustion apparatus of the present invention can be provided in a firing furnace used in, for example, pre-baking or overcoating of ceramics, or calcination of limestone when producing quicklime.

DESCRIPTION OF SYMBOLS 10 Frameless combustion apparatus 10A Flange 10B Chimney 10C Base 11 Fuel gas flow path 11A Nozzle 11B Branch flow path 12 Oxidant gas flow path 12A Nozzle 12B Annulus 13 Heat exchange apparatus 13A Exhaust flow path 13B Inner pipe 13C Outer pipe 13D Narrow pipe 13E Baffle 14 Combustion gas generator 14A Central shaft 14B Combustion chamber 14C Inner pipe 14D Pilot burner 14E Fuel discharge nozzle 14F Outlet 14G Outer pipe 14H Spacer 14I Air injection nozzle 14J Spark rod 14K Air flow path 15 Discharge path 15A Counterbore 15B Washer 15C connecting hole 15D connecting hole 90 crucible furnace (furnace)
90A Crucible 90B Furnace 90C Furnace lid 91 Supply device 91A Pyrometer 91B Flame detection device 92 Metal 92A Molten metal 93 Release area 93A Fuel gas 93B Air (oxidant gas)
93C Combustion gas 93D Generated gas 94 Open flame 94A Petroleum gas 95 Swirling flame 95A Air 95B Fuel 95C Air

Claims (3)

A flameless combustion apparatus provided in a furnace for generating flameless combustion inside the furnace,
A fuel gas flow path for supplying fuel gas to be oxidized by the flameless combustion to the inside of the furnace through a nozzle;
The nozzle of the fuel gas flow path is longer than the distance by which the oxidant gas and the fuel gas are diffused and mixed with each other and burned in the flameless combustion. An oxidant gas flow path for supplying the inside of the furnace through a nozzle provided at a position away from the furnace,
An exhaust passage for exhausting generated gas generated after the fuel gas is oxidized in the flameless combustion to the outside of the furnace;
A heat exchange device that heats the oxidant gas in the oxidant gas flow path by thermal energy of the generated gas in the exhaust flow path;
By lean combustion in which air and fuel are supplied and the fuel is completely burned at an air-fuel ratio larger than the stoichiometric air-fuel ratio, the volume concentration of oxygen gas is less than 13% and the temperature is two significant figures. A combustion gas generator for generating combustion gas higher than 1200 [K];
A discharge path for releasing the combustion gas generated by the combustion gas generator into the furnace and realizing mixing of the combustion gas and the oxidant gas from the oxidant gas flow path inside the furnace. When,
With
Flameless combustion device. A flameless combustion apparatus according to claim 1,
The combustion gas generator is
A combustion chamber formed in a cylindrical shape coaxial with the discharge path;
A pilot burner for generating a spark for igniting the fuel at the center of the combustion chamber;
A fuel discharge nozzle that discharges the fuel so as to swirl around the spark from a position around the spark and away from the inner wall surface of the combustion chamber;
An air ejection nozzle that ejects normal temperature air so as to swirl along the inner wall surface of the combustion chamber in the same direction as swirling of the fuel;
With
Flameless combustion device. A flameless combustion apparatus according to claim 1 or 2, wherein
The nozzle of the fuel gas flow path is located along a flow of the combustion gas discharged from the discharge path to the discharge area from a position along the discharge area where the combustion gas is discharged from the discharge path in the furnace. Supplying the fuel gas in a continuous flow,
The nozzle of the oxidant gas flow path supplies the oxidant gas in a flow that collides with the flow of the combustion gas discharged from the discharge path to the discharge area.
Flameless combustion device.

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