JP4731260B2 - Surface melting furnace - Google Patents

Description

  The present invention relates to a surface melting furnace capable of efficiently melting incineration ash discharged from a waste incinerator or the like in a stable state.

  Conventionally, incineration ash and fly ash discharged from incinerators such as municipal waste have been subjected to a melting and solidification process in order to reduce the volume and make them harmless upon disposal. In order to melt and solidify the incineration ash and fly ash, a surface melting furnace is generally used.

  In the surface melting furnace, usually in the case of a fixed surface melting furnace having a circular or octagonal furnace shape, two or more burners are installed on the ceiling of the melting furnace, and the material to be melted (incineration ash and fly ash) It is supplied from the supply tank into the furnace and is heated and melted using the combustion heat from the burner and the amount of combustible material in the material to be melted, and then melted from the slag port provided at the center of the bottom of the furnace body to the cooling water tank below. It is dropped and taken out as granulated slag. As such a surface melting furnace, for example, a circular fixed melting furnace as described in Patent Document 1 is known.

  In such a surface melting furnace, in order to improve the processing efficiency by homogenizing the temperature in the furnace and homogenizing the slag quality and preventing the generation of deposits near the slag port, An oxygen jet nozzle is attached to the burner flame, and oxygen is blown directly into the burner flame from the nozzle at a high speed to generate a swirling flow of combustion gas in the furnace. The temperature inside the furnace is made uniform and the temperature is increased to increase the processing efficiency. Further, a surface melting furnace provided with a nozzle for blowing oxygen toward the flame of the burner and the slag port to prevent the generation of deposits in the vicinity of the slag port with the high-temperature combustion gas is based on the prior application of the present applicant. It has been proposed (Patent Document 2).

  Also, in the surface melting furnace, as the melt is melted, when the melting point of the melt is high, or when the melt has a high viscosity and poor meltability (fluidity), Since the slag port is blocked by being cooled and solidified, a slag port heating burner for heating the melt around the slag port is provided in the furnace ceiling as a means for solving this, and the slag port is detected by the slag port blockage detecting means. An arrangement configured to actuate a port heating burner is known from US Pat.

Japanese Patent No. 3361198 JP 2000-346335 A JP 2000-292065 A

  However, in the prior art, when a burner is installed vertically on the ceiling of the furnace, the material to be melted immediately below the burner has the highest temperature, and the high melting point metal mixed in the material to be melted is melted. The refractory metal flows toward the slag port together with the slag, but the refractory is strongly cooled around the slag port, and the refractory metal does not flow down as it is, but solidifies into an icicle and closes the slag port. There is a problem that it ends up. In addition, in order to raise the low temperature range other than the vicinity heated by the flame radiation of the burner to the meltable temperature, it is necessary to further raise the temperature near the burner, which increases fuel consumption and impairs the durability of the furnace wall. become. Moreover, since the temperature in the vicinity of the burner becomes high, there arises a problem that the NOx value in the combustion exhaust gas becomes high.

  Further, as is known from Patent Document 2, the swirling flow of combustion gas into the furnace by blowing oxygen directly into the burner flame at high speed directly from the oxygen blowing nozzle toward the burner flame in the furnace of the surface melting furnace. In the method of generating oxygen, since oxygen is constantly injected, it is necessary to supply oxygen in addition to the fuel to be supplied to the burner, and there is a problem that the running cost is greatly increased.

  Further, when the slag port heating burner known from Patent Document 3 is provided, in order for the combustion flame to reach the slag port opening, it is necessary to configure the burner to protrude largely into the furnace. For this purpose, a telescopic structure is required that is retracted to a standby state when the burner is not used. However, in this slag port heating burner, when the vicinity of the slag port is heated, the slag port heating burner is used by protruding into the combustion chamber in a high temperature state.

  In order to solve the above-described problems, the present invention generates a swirling flow of combustion gas in the combustion chamber without using an auxiliary agent to achieve uniform and high temperature in the furnace, thereby improving the processing efficiency. The object of the present invention is to provide a surface melting furnace capable of increasing the slag and preventing the slag port from being blocked.

In order to achieve the above object, the surface melting furnace according to the present invention comprises:
In a fixed surface melting furnace, a burner that burns in the form of multiple wide-angle flames is placed on the furnace ceiling with the axis center tilted in a fixed direction toward the combustion chamber, and at the center of the furnace ceiling and the center of the furnace floor A narrow-angle flame burner that injects and burns toward the provided slag port is installed.

  In the above invention, the burner that burns in the wide-angle flame shape preferably has a combustion spread angle of 110 to 140 ° (second invention). Further, the burner that burns in the shape of the wide-angle flame is preferably installed at an inclination angle of 70 to 80 degrees with respect to the ceiling surface of the mounting axis (third invention).

  In the invention, the narrow-angle flame burner has a two-fluid mixed portion of fuel oil and compressed air in the shape of a Laval nozzle, and has a plurality of air suction holes along the axis at the position in front of the diffuser outlet of the Laval nozzle. It is preferable that a flame with high linearity can be obtained by the air-fuel mixture injected by sucking air from the air suction hole around the air-fuel mixture (fourth invention).

  According to the present invention, by installing a plurality of burners that burn in a wide-angle flame shape, a swirl flow is generated in the combustion gas in the furnace without injecting the auxiliary agent (oxygen), and the atmosphere temperature in the furnace is uniform. And melting of metals due to local high temperature can be suppressed. Further, even if the metal is melted and solidified near the slag port, the metal solidified by the narrow-angle flame burner can be dissolved and removed to prevent the slag port from being blocked. Further, it is not necessary to always secure the melting temperature as a countermeasure against the blockage of the slag port, the melting temperature can be minimized, and the fuel consumption can be reduced. Moreover, since the furnace atmosphere can be made uniform at a lower temperature than conventional, the generation of thermal NOx can be suppressed. Furthermore, since the heat load on the material to be melted in the furnace can be made uniform, a stable molten surface can be formed, and the slag quality can be improved.

  Further, according to the second and third inventions, by using a burner that burns in a wide-angle flame shape for heating the melt, the share of the burner can be expanded, and the combustion gas has a slight inclination. It is possible to give direction to the flow of the gas, and there is an advantage that the temperature inside the furnace is easily made uniform.

  Further, according to the fourth aspect of the present invention, the mixing portion of the two fluids is shaped into a Laval nozzle and a burner that burns by injecting the mixture at high speed is used. Thus, since a flame that burns at a narrow angle is obtained, local heating can be performed, and the effect of being able to effectively treat the dissolution and removal of the molten and solidified material that remains after a short period of use can be obtained.

  Next, specific embodiments of the surface melting furnace according to the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view schematically showing the main part of the surface melting furnace according to the present embodiment, FIG. 2 is a schematic plan view schematically showing the arrangement relationship of burners in the furnace, and FIG. FIG. 4 shows a partial cross-sectional overall view (a) and an enlarged vertical cross-sectional view (b) of a main part of a narrow-angle flame burner. ing.

  In the surface melting furnace 1 of the present embodiment, the cross-sectional shape of the furnace body 2 is octagonal, the slag port 4 is provided at the center position of the furnace body floor 3, and is disposed below the furnace body 2. Slag is dripped in the cooling water tank which is not done. A melt storage chamber 5 is provided on the entire periphery of the furnace body 2, and a melt supply device 7 is disposed on each surface of the furnace wall at the bottom of the melt storage chamber 5. On the furnace ceiling wall 6, four burners 10 are disposed toward the combustion chamber 9, and a narrow-angle flame burner 20 is disposed substantially downward at the center.

  The melted material storage chamber 5 provided around the furnace body 2 has a known structure, and the melted material supply device 7 having a known structure is used for the melted material F such as incinerated ash and fly ash. The supply pusher 8 is pushed into the center side of the combustion chamber 9, and the surface portion of the melt F is heated and melted by the burner 10 in the combustion chamber 9.

  The burner 10 disposed on the ceiling wall 6 is a burner of a type that burns in a wide-angle flame shape (hereinafter referred to as “wide-angle flame burner 10” or simply “burner 10”), and the furnace body is divided into four equal parts. It attaches so that the surface part of the to-be-melted material extruded to the floor | bed 3 may be heated. The wide-angle flame burner 10 has a constant axial center line within a range of about 70 to 80 ° with respect to the wall surface of the ceiling wall 6 (preferably on a circle drawn with a required radius from the center of the ceiling wall 6). (Tilt direction) and attached. As the wide-angle flame burner 10, for example, as shown in FIG. 3, the compressed air supplied by the outer tube 11 and the fuel oil supplied from the inner tube 12 are atomized through the annular slit 14, and the cap 15 A wide-angle conical shape is formed through an annular slit 19 formed by a conical target 18 which is mixed in the inner mixing chamber 16 and is attached to the front portion of a spout 17 where the air-fuel mixture is ejected from the mixing chamber 16. A burner (see Utility Model Registration No. 2559333) is used which is jetted into the nozzle and burned at a wide angle as it is. In addition, it is preferable that the combustion spread angle | corner (theta) by the ejection of the said air-fuel | gaseous mixture is the range of 110-140 degrees. In the figure, reference numeral 35 denotes a mounting seat for the burner.

  The narrow-angle flame burner 20 has a double-pipe structure composed of a fuel supply pipe 21 (inner pipe) and a compressed air supply pipe 22 (outer pipe), for example, as shown in FIGS. Then, a needle valve 23 for adjusting the flow rate is provided at the distal end of the inner tube 21, and the valve stem 24 inserted from the rear end of the inner tube 11 is rotated at the rear end 24a to rotate the valve at the distal end. 24 'is advanced and retracted to adjust the amount of fuel oil supplied from the outlet 23' provided at the tip 21a of the inner pipe 21. A nozzle head 25 is attached to the tip of the double pipe thus configured, and a mixing portion of fuel oil and compressed air is formed at the base of the nozzle head 25.

  The nozzle head 25 has a rear half portion attached to the tip of the outer tube 22 with a coaxial core, and receives a portion in which the inner tube 21 protrudes longer than the end of the outer tube 22. An annular compressed air flow space forming portion 27 is formed between the outer periphery of the tube 21. An intermediate portion of the nozzle head 25 forms a Laval nozzle that leads from a trumpet-shaped suction portion 28a that constricts toward the axial center from the flow space forming portion 27 to a diffuser 28c through a constricted portion 28b (throat portion 28b) on the central axis. A portion 28 is provided. Further, an air suction portion 29 having an enlarged opening diameter is formed from the intermediate portion to the front portion so as to be connected to the diffuser 28c. The air suction portion 29 is formed in a cylindrical shape having a required length with a diameter larger than the tip diameter of the diffuser 28c of the Laval nozzle forming portion 28, and the cylindrical portion is divided into a peripheral surface and is a long hole along the axis. A plurality of air suction holes 30 are provided.

  The surface melting furnace 1 of the present embodiment configured as described above stores the melted material F provided around the furnace body 2 with the melted material F such as incineration ash and fly ash discharged from a waste incinerator or the like. It is received in the chamber 5, and is sequentially pushed toward the center of the combustion chamber 9 by the supply pusher 8 of the melt supply device 7 disposed at the lower part of the storage chamber 5, and the surface portion of the melt F in the combustion chamber 9. Is heated and melted by the burner 10.

  In the combustion chamber 9 in the furnace, four wide-angle flame burners 10 are arranged on the ceiling wall 6 downward and inclined with their mounting axes inclined in a fixed direction. By doing in this way, the combustion flame of the burner 10 diffuses in a wide range and radiates the combustion gas in the tilt direction. In this state, a plurality of (four) burners 10 burn simultaneously, so that in the combustion chamber 9 surrounded by the furnace wall, the combustion gas flows preferentially in the direction of inclination of the axis of the burner 10. As a result, the combustion gas flows as a swirl flow in the combustion chamber 9 and is extruded into the combustion chamber 9 to melt the surface layer portion of the melt F that forms an inclined surface.

  Therefore, the combustion chamber 9 can make the furnace atmosphere temperature uniform by flowing the combustion gas generated by the combustion of the burner 10 as a swirling flow and radiating the flame to a wide angle range. In other words, it is possible to eliminate an unbalance in the furnace temperature such that the temperature immediately below the burner becomes higher than that of the other parts as in the prior art. In addition, it is possible to avoid obstacles associated with melting of a metal having a high melting point without increasing the temperature in order to eliminate the imbalance in the atmospheric temperature in the combustion chamber 9. In addition, since the furnace temperature atmosphere can be made uniform at a lower temperature than conventional, there is an advantage that generation of thermal NOx can be suppressed. Furthermore, since the heat load on the material to be melted in the furnace can be made uniform, a stable melt surface can be formed, and the occurrence of unmelted material in the melt can be eliminated, and the slag quality can be improved. In addition, the fuel consumption can be saved and the operation cost can be reduced.

  Note that when the wide-angle flame burner 10 is used, the combustion spread angle θ is set to 110 to 140 °. This is because when the combustion spread angle θ is 110 ° or less, the expansion range of the combustion flame is reduced and the heating effect is increased accordingly. Decreases. In addition, it is difficult for the burner to have a combustion spread angle θ of 140 ° or more, and the diffusion of the flame becomes insufficient due to the expansion of the combustion spread angle θ, thereby reducing the heating effect. Therefore, it is preferable to select the combustion spread angle θ in the range of 110 to 140 °. Also, the reason why the mounting axis of the wide-angle flame burner 10 is set to 70 ° to 80 ° with respect to the mounting ceiling wall surface is to use a burner having a wide combustion spread angle when the mounting axis is tilted to 70 ° or less. In addition, the combustion flame may come into contact with the surface of the ceiling wall 6, which is not preferable. Further, if the mounting axis is set to 80 ° or more, the effect of tilting the burner and mounting is reduced. Therefore, the tilt angle of the mounting shaft center line is preferably selected within the range of 70 ° to 80 °.

  On the other hand, as the operation progresses, the melt F extruded into the combustion chamber 9 melts on the upper surface of the furnace floor 3 from the extrusion side toward the slag port 4 by the extrusion by the supply pusher 8. Then, it flows down and drops from the slag port 4 to the cooling water tank. However, around the slag port 4, the cooling is strengthened in order to maintain the durability, so that the melt is easily adhered and solidified. Therefore, as a result of regular or situation monitoring, if the amount of adhesion increases, it is necessary to remove the adhered and solidified slag in order to prevent the slag port 4 from being blocked.

  In order to prevent the slug port 4 from being blocked, a narrow-angle flame burner 20 is used. The narrow-angle flame burner 20 is attached to the center portion of the ceiling wall 6 so as to be directly below the combustion chamber 9 (slag port 4). The narrow-angle flame burner 20 is operated according to the closed state of the slag port 4 to dissolve and remove the molten fixed matter adhering to the vicinity of the slag port 4.

  As described above, the narrow-angle flame burner 20 is provided with the nozzle head 25 having a function of attracting air to the periphery thereof by injecting the Laval nozzle-shaped portion 28 and the air-fuel mixture ejected to possess the straightness. Structure. Accordingly, the fuel oil fed from the fuel oil supply port is ejected through the inner pipe 21 from the jet outlet 23 ′ at the tip thereof to the suction portion 28 a having a Laval nozzle shape. On the other hand, the compressed air (or steam) is fed from the supply port into the flow space forming portion 27 from the inside of the outer tube 22, and a set gap in the nozzle head 25 (gap between the trumpet-shaped reduced wall surface and the inner tube tip portion 21a). And is ejected to the suction portion 28a.

  The fuel oil and compressed air (or steam) ejected to the suction part 28a in the nozzle head 25 are vigorously mixed and atomized at the inlet of the Laval nozzle (suction part), and are compressed by the throat part 28b which forms the narrowest flow path. Then, it is accelerated to a speed equal to or higher than the speed of sound, passes through the diffuser 28c, and is injected at an extremely high speed at the outlet 28d. Due to the discharge force (injection force) of the air-fuel mixture passing through the outlet portion 28d, the surrounding air is sucked and ejected from a plurality of air suction holes 30 formed in a vertically long shape by the air suction portion 29 provided at the nozzle tip portion. The air flow sucked around the air-fuel mixture is injected in the surrounding state. As a result, the air-fuel mixture injected from the nozzle tip is prevented from diffusing at the nozzle tip outlet 31 and is injected with high straightness. If the mixture is ignited by a separate ignition means for the injection part of the mixture, the combustion is carried out at a high speed at a high speed. The flame reaches the vicinity of the slag port 4 to dissolve the adhering solidified matter. And can be removed by dripping. The flame of the narrow-angle flame burner 20 that burns at a narrow angle in this way becomes a blue fire due to high-speed combustion up to about half of the total flame length, and the other half becomes a red fire with strong radiant heat. Therefore, since the solidified substance around the slag port 4 can be melted and removed locally and concentrated, it can be processed in a very short time, and the atmosphere temperature in the combustion chamber 9 can be excessively increased. Absent.

Thus, the slag port 4 can be prevented from being blocked due to the melting of the material F to be melted in the melting furnace, so that the operation does not reach the stop state and the stable operation can be continued. Therefore, the work efficiency can be improved.

The longitudinal cross-sectional view which represents typically the principal part of the surface melting furnace which concerns on this embodiment Flat cross-sectional schematic diagram showing the arrangement of burners in the furnace Main part sectional drawing of one Embodiment of the burner which burns with a wide angle flame shape Partial cross-sectional overall outline view (a) and main part enlarged vertical cross-sectional view (b) of an embodiment of a narrow-angle flame burner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface melting furnace 2 Furnace body 4 Slag port 5 Molten material storage chamber 6 Furnace ceiling wall 7 Molten material supply apparatus 9 Combustion chamber 10 Wide-angle flame burner (burner)
20 Narrow-angle flame burner 25 Nozzle head 28 Laval nozzle forming part 29 Air suction part F Melted material

Claims (4)

  In a fixed surface melting furnace, burners that burn in the form of multiple wide-angle flames are installed on the furnace ceiling, and the axial center line is inclined in a fixed direction toward the combustion chamber. A surface melting furnace characterized in that a narrow-angle flame burner that injects and burns toward a slag port provided on the surface is installed.   The surface melting furnace according to claim 1, wherein the burner that burns in the wide-angle flame shape has a combustion spread angle of 110 to 140 °.   3. The surface melting furnace according to claim 1, wherein the burner that burns in the wide-angle flame shape is installed at an inclination angle of 70 to 80 ° with respect to the ceiling surface of the mounting axis.   The narrow-angle flame burner has a two-fluid mixing portion of fuel oil and compressed air in the shape of a Laval nozzle, and has a plurality of air suction holes along an axis at a position in front of the diffuser outlet of the Laval nozzle. The surface melting furnace according to claim 1, wherein a flame having high straightness can be obtained by a mixture to be injected by sucking air from the air suction hole around the surface.

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