JP2007051846A - Gasification melting system and operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively suppress the accumulation of ash in gas in a duct in a gasification melting system while adapting the structure of connecting the duct to a gas discharge part of a high-temperature combustion device including a melting furnace. <P>SOLUTION: A gas discharge port 40 of the high-temperature combustion device 14 including the melting furnace 30 is connected to a gas inlet 42 of a temperature reducing tower 42 by the duct 60. The duct 60 is cooled by cooling water or the like, whereby the inner surface temperature of the duct 60 is reduced to prevent the ash in the gas contacting with the duct inner surface to the inner surface from being softened, adhered and accumulated to the inner surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gasification and melting system for treating waste such as municipal waste and industrial waste.

Conventionally, as a means for processing waste, a gasification melting system as described in Patent Document 1, for example, is known. This system includes a fluidized bed type gasification furnace in which a fluidized bed is formed by a fluidized gas, and a subsequent melting furnace, and the fluidized bed type gasification furnace is configured to remove the waste introduced into the fluidized bed. Combusting to produce pyrolysis gas, the melting furnace further burns the pyrolysis gas generated by the fluidized bed gasification furnace to melt the ash in the gas, thereby generating molten slag, Discharge. The high-temperature combustion gas generated in the melting furnace is sequentially sent to a subsequent boiler, a gas cooling chamber, and a bag filter, and is discharged out of the system after the processing.
JP 2004-37049 A

  Among the waste treatment facilities to which the system is introduced, for example, in a small-scale waste treatment facility such as provided in a local city with a small population, the boiler is omitted, and a high temperature including the melting furnace instead is provided. A system may be employed in which a gas discharge part of a combustion apparatus and a subsequent temperature reduction tower are connected via a duct.

  However, in such a system in which the duct is directly connected to the gas discharge part of the high-temperature combustion apparatus, the temperature of the gas flowing in the duct, that is, the high-temperature combustion gas is very high, and the temperature of the inner surface of the duct that contacts the gas is There is a possibility of exceeding the softening point (about 800 ° C. to 1000 ° C.). In this case, when the ash contained in the high-temperature combustion gas contacts the inner surface of the duct, the ash may soften on the inner surface of the duct and adhere to the inner surface of the duct. If such ash content is left unattended, the ash content accumulates in the duct and closes the duct. Therefore, it is necessary to periodically maintain the duct, resulting in an increased work load. In some cases, it may interfere with long-term continuous operation.

  In view of such circumstances, the present invention is effective in depositing ash in a duct in a gasification and melting system while connecting the duct to a gas discharge part of a high-temperature combustion apparatus including the melting furnace. The purpose is to deter.

  As means for solving the problems, the present invention combusts a gasification furnace that pyrolyzes an object to be processed to generate a pyrolysis gas, and a combustible component in the pyrolysis gas generated in the gasification furnace. A high temperature combustion apparatus including a melting furnace for melting ash in the gas and discharging the molten slag, and a duct connected to a gas discharge portion of the high temperature combustion apparatus And the exhaust gas of the high-temperature combustion apparatus flows through the inside of the duct, and at least a part of the portion where the temperature of the gas flowing inside the duct is 400 ° C. or higher is cooled to reduce the inner surface temperature of the ash content. It is lower than the softening point.

  The present invention also includes a gasification furnace that pyrolyzes an object to be processed to generate a pyrolysis gas, and combustible components in the pyrolysis gas generated in the gasification furnace to melt ash in the gas. A gasification and melting system including a high-temperature combustion apparatus that discharges the molten slag, and a duct is connected to a gas discharge portion of the high-temperature combustion apparatus, and a gas flowing inside the duct is connected to the gas discharge section of the high-temperature combustion apparatus. The duct is provided with cooling means for lowering the inner surface temperature of at least a part of the portion having a temperature of 400 ° C. or higher.

  The present invention also includes a gasification furnace that pyrolyzes an object to be processed to generate a pyrolysis gas, and combustible components in the pyrolysis gas generated in the gasification furnace to melt ash in the gas. A high-temperature combustion apparatus including a melting furnace for discharging the molten slag, a temperature reducing tower for cooling the gas discharged from the high-temperature combustion apparatus, a gas discharge unit of the high-temperature combustion apparatus, and a gas inlet of the temperature reduction tower And a cooling means for lowering the inner surface temperature of the duct.

  According to the above configuration, the ash in the gas contacting the inner surface of the duct is softened on the inner surface by cooling the duct connected to the gas discharge part of the high-temperature combustion apparatus and lowering the inner surface temperature thereof. Thus, it is possible to effectively suppress adhesion to the inner surface. In particular, by cooling at least a portion of the duct where the temperature of the gas flowing inside thereof is 800 ° C. or higher, the effect of suppressing the adhesion and accumulation of ash becomes remarkable.

  The high-temperature combustion apparatus may be constituted only by the melting furnace, or may have a secondary combustion chamber in the subsequent stage in addition to the melting furnace. In the latter case, it may be downstream of the secondary combustion chamber (directly downstream of the secondary combustion chamber, or further downstream of an air preheater provided downstream of the secondary combustion chamber. ) In which the gas discharge part is provided.

  The cooling means preferably includes a passage forming member that forms a cooling fluid passage having a shape surrounding the inner wall of the duct. According to this configuration, the cooling fluid can be allowed to flow immediately outside the inner wall, and thereby the inner surface temperature of the inner wall can be efficiently reduced with a simple configuration.

  In particular, the passage forming member has a substantially cylindrical shape surrounding the inner wall with a gap radially outward from the inner wall of the duct, and a cooling fluid passage that is continuous over the entire circumference between the inner wall of the duct. If it forms, the said inner wall can be efficiently cooled over the substantially whole region.

  The duct may be integrated over its entire length, but if it is constructed by connecting a plurality of duct constituent pipes divided in the gas flow direction, its transport work and installation work on site will be more effective. It becomes easy. In this case, each of the passage forming members forms an independent cooling fluid passage for each of the duct constituent pipes, and includes connection pipes that connect the cooling fluid passages of the adjacent duct constituent pipes. The cooling fluid passages can be reliably sealed with the duct constituent pipes, and the cooling fluid passages extending over the plurality of duct constituent pipes can be formed by connecting the cooling fluid passages with the connecting pipes. In addition, the cooling efficiency can be improved by increasing the heat radiation area by the connection pipe.

  As described above, according to the present invention, the duct connected to the gas discharge portion of the high-temperature combustion apparatus is cooled to lower the inner surface temperature thereof, so that the ash content in the high-temperature combustion gas adheres to the inner surface of the duct. There is an effect that can be effectively suppressed and smooth operation can be realized.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  The gasification and melting system shown in FIG. 1 includes a dust feeder 10, a fluidized bed gasification furnace 12, a high-temperature combustion device 14, a first temperature-decreasing tower 16, an air preheating device 18 in order from the front side. The second temperature reducing tower 20, the bag filter 22, the induction fan 24, and the chimney 26 are provided.

  The dust feeder 10 has a waste hopper 11 and quantitatively supplies the waste introduced into the waste hopper 11 to the fluidized bed gasifier 12 by a screw conveyor.

  A fluidized bed 28 made of fluidized particles such as sand is formed on the hearth of the fluidized bed gasification furnace 12, and the fluidized bed 28 is charged into the fluidized bed 28 while maintaining the temperature of the fluidized bed 28 at, for example, 450 to 650 ° C. An operation is performed in which the generated waste is subjected to low-temperature pyrolysis, that is, primary combustion. Incombustible substances contained in the garbage are extracted from the bottom of the furnace together with the fluidized particles, and separated from the fluidized particles in the subsequent stage. The separated fluidized particles are returned to the fluidized bed 28 and reused.

  The high-temperature combustion apparatus 14 has a configuration in which a melting furnace 30 extending in the vertical direction, a secondary combustion chamber 32 and a secondary air preheater 34 in the subsequent stage are arranged in parallel.

  In the melting furnace 30, the pyrolysis gas sent from the fluidized bed gasification furnace 12 is further burned under the condition of a total air ratio of 1.3, for example. Specifically, a swirl flow is formed in the melting furnace 30 by combustion air, and high-temperature combustion at about 1300 ° C. is performed, and the ash in the pyrolysis gas is melted on the furnace wall by the heat and slag is formed. And is discharged from the outlet 36 at the bottom of the high-temperature combustion device 14 through the furnace wall. The molten slag is recovered to a specific location after being subjected to a cooling process by the slag water cooling device 38 or the like.

  The secondary combustion chamber 32 is provided on the opposite side of the melting furnace 30 with the tap hole 36 interposed therebetween, and plays a role of further secondary combustion of the gas introduced from the melting furnace 30. The secondary air preheater 34 is arranged on the downstream side of the secondary combustion chamber 32 and above the secondary combustion chamber 32, and the air rising from the secondary combustion chamber 32 is sent from the air preheating device 18 described later. By exchanging heat, the temperature of the gas is reduced and the air is heated to serve as secondary air. The secondary air whose temperature has been raised here is supplied to appropriate locations of the fluidized bed gasification furnace 12 and the melting furnace 30. In the secondary combustion chamber 32 and the secondary air preheater 34 also, the ash in contact with the inner wall surface may melt and become slag, but the slag also travels along the inner wall surface to the outlet. 36 is discharged.

  In the present invention, the secondary air preheater 34 may be omitted as appropriate.

  In the illustrated high-temperature combustion apparatus 14, a gas discharge port 40 is provided on the downstream side, that is, the upper side of the secondary air preheater 34, and the gas at the top of the gas discharge port 40 and the first temperature-decreasing tower 16 is provided. An inlet 42 is connected via a duct 60. The structure of the duct 60 will be described in detail later.

  The first temperature-decreasing tower 16 causes the high-temperature combustion gas introduced from the gas inlet 42 to flow down while being in contact with cooling water, and reduces the temperature of the gas to, for example, about 300 ° C. to 400 ° C. To discharge.

  The air preheater 18 includes a secondary air preheater 44, a forced air preheater 46, and a white smoke prevention air heater 48 in this order from the upstream side (lower side in the figure), and the first temperature reducing tower. The temperature of the gas is lowered and the supply air is preheated by heat exchange between the gas discharged from 16 and the supplied air.

  Air sent from the secondary blower 50 is introduced into the secondary air preheater 44, and this air is preheated by the secondary air preheater 44 and then the secondary air preheater 34 of the high-temperature combustion apparatus 14. Is sent to. Similarly, the air sent from the pushing air blower 52 is introduced into the pushing air preheater 46, and this air is preheated by the pushing air preheater 46 and then pushed into the furnace bottom of the fluidized bed gasifier 12. It is sent as (fluidizing gas). In addition, air sent from the white smoke prevention blower 54 is introduced into the white smoke prevention air heater 48, and this air is reheated by the air reheater 56 and then introduced into the lower part of the chimney 26. The

  The gas that has passed through the air preheating device 18 is further cooled to about 150 ° C. to 200 ° C. in the second temperature reducing tower 22, and then sent to the bag filter 22, and is sent out of the system from the induction blower 24 through the chimney 26. Discharged.

  In the present invention, the air preheating device 18 and the second temperature reduction tower 22 are not necessarily required. For example, if the gas temperature can be sufficiently lowered in the first temperature reduction tower 20, the first temperature reduction tower will be described. The bug filter 22 may be directly connected to the 20. When the air preheating device 18 is provided, the heat exchanger may be a radiant type or a plate type having a plate inserted therein.

  Next, the structure of the duct 60 connecting the gas outlet 40 of the high-temperature combustion apparatus 14 and the gas inlet 42 of the first temperature reducing tower 16 will be described with reference to FIGS. .

  The duct 60 is configured by connecting a plurality of (four in the illustrated example) duct constituent pipes 60A, 60B, 60C, 60D in that order. Each of the duct constituent pipes 60A to 60D has flanges 61 and 62 at the upstream end and the downstream end in the gas flow direction, respectively, and the downstream flange 62 of each duct constituent pipe 60A, 60B, and 60C and the downstream side thereof. Are connected to the upstream flange 61 of the duct constituent pipes 60B, 60C, 60D adjacent to each other, and the upstream flange 61 of the uppermost duct constituent pipe 60A is joined to the gas discharge port of the high-temperature combustion apparatus 14. The downstream flange 62 of the most downstream duct component pipe 60D is joined to the gas inlet 42 of the first temperature reducing tower 16.

  A main body portion of each of the duct constituent tubes 60A to 60D includes an inner wall 64 and a passage forming tube 66 that surrounds the inner wall 64 from the outside.

  The inner wall 64 is formed in a cylindrical shape with a refractory material (for example, a silicon carbide (SiC) -type castable material), and is configured such that exhaust gas of the high-temperature combustion device 14 flows through the inside thereof. The passage forming pipe 66 has a substantially cylindrical shape covering the inner wall 64 from the outside in the radial direction over the entire circumference, and forms a cylindrical cooling water passage 65 continuous with the inner wall 64 over the entire circumference. The cooling water passage 65 has both axial ends sealed by flange portions 61 and 62 of the duct constituent pipes 60A to 60D, and the cooling water passage 65 is independent for each of the duct constituent pipes 60A to 60B. It has become.

  Furthermore, in each of the duct constituent pipes 60A to 60D, pipe connection flanges 68 and 67 connected to the cooling water passage 65 are formed at positions near the upstream flange portion 61 and the downstream flange portion 62, respectively. . And the pipe connection flange 67 on the downstream side in the gas flow direction of the duct constituent pipes 60A, 60B, 60C, and the pipe connection flange 68 on the upstream side in the gas flow direction of the duct constituent pipes 60B, 60C, 60D adjacent to the downstream side. By connecting both ends of the connection pipe 70 to each other, the cooling water passages 65 of the duct constituent pipes adjacent to each other are communicated with each other via the connection pipe 70, and a continuous cooling water passage is formed over the entire length of the duct 60. ing.

  Here, the shape of the connection pipe 70 can be set as appropriate. However, each connection pipe 70 according to this embodiment has a shape straddling the flange portions 62 and 61 of the duct constituent pipes adjacent to each other (U-shaped in the illustrated example). Shape), and bulges from the duct body to the outside in the radial direction so that a heat radiation area can be obtained.

  Furthermore, a cooling water supply pipe (not shown) is connected to the pipe connecting flange 67 (downstream in the gas flow direction) of the duct constituting pipe 60D, and the most upstream duct constituting pipe 60A (downstream in the gas flow direction). ) A cooling water discharge pipe (not shown) is connected to the pipe connection flange 68. Then, the cooling water introduced from the cooling water supply pipe into the cooling water passage 65 of the duct constituent pipe 60D is connected to the connecting pipe 70 between the duct constituent pipes 60D and 60C → the cooling water passage 65 of the duct constituent pipe 60C → the duct configuration. The connection pipe 70 between the pipes 60C and 60B → the cooling water passage 65 of the duct constituent pipe 60B → the connection pipe 70 between the duct constituent pipes 60B and 60A → the cooling water passage 65 of the duct constituent pipe 60A (in other words, inside the duct). Contrary to the gas flow), the gas is discharged to the cooling water discharge pipe connected to the pipe connection flange 68 of the duct constituting pipe 60A.

  In FIGS. 2A and 2B, reference numeral 72 denotes a bracket for fixing the duct 60 to an appropriate place in the facility.

  In the duct 60 described above, the inner surface temperature of the inner wall 64 can be lowered by flowing cooling water through the cooling water passage outside the inner wall 64, and the inner surface temperature is adjusted by the supply flow rate of the cooling water. Can do. Therefore, by suppressing the surface temperature of the inner wall 64 to a temperature (for example, 400 ° C.) lower than the softening point of ash (about 800 ° C. to 1000 ° C.), the ash in contact with the inner surface of the inner wall 64 is softened. As a result, it is possible to prevent the ash from accumulating in the duct 60 and block the duct 60, thereby extending the continuous operation possible period.

  The cooling fluid for cooling the duct 60 is not limited to water, and various fluids can be used as appropriate. Further, the cooling can be performed by applying a cooling fluid to the outside of the duct 60. However, if the cooling water passage 65 is formed outside the duct inner wall 64 as shown in the drawing, there is an advantage that the inner surface temperature of the inner wall 64 can be more efficiently lowered. It is also effective to wind the cooling water pipe on the outer surface of the inner wall 64.

  Further, in the present invention, it is not always necessary to cool the duct 60 over the entire area, and at least a part thereof (for example, a part that is particularly easily clogged due to the shape of the duct, etc.) in the region where the gas temperature is 400 ° C. or higher is set as the cooling target. By doing so, it is possible to effectively suppress the accumulation of molten ash content inside the duct. However, it is more preferable that the object to be cooled includes at least a region where the gas temperature is 800 ° C. or higher.

1 is an overall configuration diagram of a gasification melting system according to an embodiment of the present invention. (A) is a top view of the duct provided in the said gasification melting system, (b) is the cross-sectional front view. It is the sectional view on the AA line of FIG.2 (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 12 Fluidized bed type gasifier 14 High temperature combustion apparatus 16 1st temperature-reduction tower 30 Melting furnace 32 Secondary combustion chamber 36 Outlet 40 Gas discharge port of a high temperature combustion apparatus 42 Gas inlet of 1st temperature reduction tower 60 Duct 60A, 60B, 60C, 60D Duct constituting pipe 64 Inner wall 65 Cooling water passage (cooling fluid passage)
66 Passage forming pipe (passage forming member)
70 Connection piping

Claims (10)

  A gasification furnace that pyrolyzes an object to be processed and generates pyrolysis gas; and a melting furnace that burns combustible components in the pyrolysis gas generated in the gasification furnace and melts ash in the gas A gasification and melting system including a high-temperature combustion apparatus for discharging the molten slag, wherein a duct is connected to a gas discharge portion of the high-temperature combustion apparatus, and an exhaust gas of the high-temperature combustion apparatus is disposed inside the duct. And at least part of the portion of the duct where the temperature of the gas flowing inside thereof is 400 ° C. or higher is cooled to lower the inner surface temperature below the ash softening point. How to operate the system.   2. The operation method of a gasification and melting system according to claim 1, wherein at least a portion of the duct where the temperature of the gas flowing inside thereof is 800 [deg.] C. or more is cooled to lower the inner surface temperature below the softening point of the ash. A method for operating a gasification and melting system characterized by the above.   A gasification furnace that pyrolyzes an object to be processed and generates pyrolysis gas; and a melting furnace that burns combustible components in the pyrolysis gas generated in the gasification furnace and melts ash in the gas In the gasification and melting system including the high-temperature combustion apparatus that discharges the molten slag, a duct is connected to the gas discharge portion of the high-temperature combustion apparatus, and the temperature of the gas flowing inside the duct is 400 ° C. or higher. A gasification and melting system, wherein the duct is provided with cooling means for lowering the inner surface temperature of at least a part of the part.   4. The gasification melting system according to claim 3, wherein the cooling means lowers the inner surface temperature of a portion of the duct where the temperature of the gas flowing at least inside thereof is 800 ° C. or more. system.   A gasification furnace that pyrolyzes an object to be processed and generates pyrolysis gas; and a melting furnace that burns combustible components in the pyrolysis gas generated in the gasification furnace and melts ash in the gas A high-temperature combustion apparatus for discharging the molten slag, a temperature reducing tower for cooling the gas discharged from the high-temperature combustion apparatus, and a gas discharge section of the high-temperature combustion apparatus and a gas inlet section of the temperature reduction tower are connected to each other. A gasification and melting system comprising a duct and provided with cooling means for lowering the inner surface temperature of the duct.   6. The gasification and melting system according to claim 5, wherein the cooling means is provided in at least a part of a portion of the duct where the temperature of the gas flowing inside thereof is 400 ° C. or higher. .   The gasification and melting system according to any one of claims 3 to 6, wherein the high-temperature combustion apparatus has a secondary combustion chamber at the rear stage of the melting furnace, and the gas is disposed downstream of the secondary combustion chamber. A gasification and melting system characterized in that a discharge part is provided.   The gasification melting system according to any one of claims 3 to 7, wherein the cooling means includes a passage forming member that forms a cooling fluid passage having a shape surrounding an inner wall of the duct. .   9. The gasification and melting system according to claim 8, wherein the passage forming member has a substantially cylindrical shape surrounding the inner wall with a gap from the inner wall of the duct to the outside in the radial direction, and between the inner wall of the duct. A gasification and melting system characterized by forming a cooling fluid passage continuous over the entire circumference.   10. The gasification and melting system according to claim 8, wherein the duct is configured by connecting a plurality of duct constituent pipes divided in the gas flow direction, and the passage forming member includes the duct constituents. A gasification and melting system comprising a connecting pipe that forms an independent cooling fluid passage for each pipe and connects the cooling fluid passages of the adjacent duct constituent pipes.

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