JP5855785B1 - Operation method of waste gasification melting furnace - Google Patents

Abstract

An object of the present invention is to provide a coke bed with a sufficiently uniform coke bed at the bottom of the furnace that can sufficiently suppress an increase in coke to be introduced into the furnace when the operation is performed with the through hole for discharging the melt steadily opened. Provided is a method for operating a waste gasification melting furnace that can maintain the formed state and that can sufficiently prevent the through-holes from being blocked due to a temperature drop of the melt in and around the through-holes. The present invention relates to a melting furnace portion located on the furnace bottom side, a plurality of tuyere for supplying oxygen into the melting furnace portion, a through hole formed in the melting furnace portion, and an interior communicating with the through hole. The present invention relates to a method for operating a waste gasification melting furnace including a pressure holding chamber having a space. In this operation method, the amount of oxygen SN supplied per unit time from the tuyere closest to the through hole into the melting furnace unit is united from the tuyere far away from the through hole to the melting furnace unit. It is characterized by being less than the amount of oxygen SF supplied per hour. [Selection] Figure 2

Description

  The present invention relates to a method for operating a waste gasification melting furnace.

  As a method for treating general waste, industrial waste, etc., a method is known in which carbon-based solid fuel (for example, coke) is used as a heat source and the waste is melted in an industrial furnace. The melting treatment of waste has an advantage that not only the volume of waste can be reduced, but also incinerated ash and incombustible waste that have been finally disposed of by landfill can be recovered as resources such as slag and metal.

  Patent Document 1 discloses a method of treating in-furnace gas flowing out together with a melt from a melt outlet of a melting furnace in a waste melting furnace for melting waste. Referring to FIG. 1 of Patent Document 1 and the scope of claims, the in-furnace gas flowing out from the melt discharge port 2 is accommodated in the enclosure hood 3 and then led to the gas combustion furnace 6 through the duct 5.

JP 2004-12077 A

  By the way, as an operation form of the waste gasification melting furnace, a form in which the melt is intermittently discharged from the bottom of the melting furnace (referred to as “intermittent hot water”) and a form in which the melt is continuously discharged (“continuous hot water”). ") Is known. In the case of intermittent hot water, the through hole for discharging the melt is closed with a heat-resistant material, the melt is discharged by opening the through-hole every predetermined time, and then the through-hole is closed again with the heat-resistant material. . Since this work has to be relied upon manually, the present inventors have repeatedly studied to realize a stable operation by continuous hot water. As a result, it was found that stable operation by continuous hot water has the following problems.

  First, as in the invention described in Patent Document 1, not only the melt but also high-temperature furnace gas is discharged out of the furnace from the open through-hole. For this reason, in order to maintain the furnace temperature at a predetermined temperature, it is necessary to increase the amount of fuel introduced into the furnace.

  Secondly, the coke bed formed at the bottom of the furnace is easily consumed unevenly under the influence of the gas passing through the through hole. That is, it is desirable to maintain a state in which a coke bed having a sufficiently uniform thickness is formed on the furnace bottom for stable operation of the waste gasification melting furnace. However, since the through holes are regularly opened, the thickness of the coke bed tends to be uneven.

  Thirdly, unless the temperature drop of the melt in the through hole and its periphery is sufficiently suppressed, the through hole is blocked by the solidified product of the melt in a relatively short time. In the case of intermittent hot water, a relatively large amount of melt accumulated in the bottom of the furnace is discharged within a short period of time, so the problem associated with a decrease in the temperature of the melt has not become apparent. On the other hand, in the case of continuous hot water, a small amount of the melt is discharged continuously (intermittently in some cases) from the through hole, so that the temperature of the melt is likely to decrease in the through hole and its surroundings. When the melt is made highly viscous or solidified due to the temperature decrease, it is gradually closed from the lower part of the through hole, and if this state continues, the entire through hole may eventually be closed.

  The present invention provides a coke bed with a sufficiently uniform coke bed that can sufficiently suppress an increase in coke to be introduced into the furnace when the melt discharge through-holes are constantly opened and operated. And a waste gasification melting furnace operating method that can sufficiently prevent the through hole from being blocked due to a temperature drop of the melt in and around the through hole. For the purpose.

The present invention relates to a method for operating a waste gasification melting furnace having the following configuration. That is, the waste gasification melting furnace is formed from the melting furnace section located on the furnace bottom side, a plurality of tuyere that respectively supply oxygen from different positions into the melting furnace section, and from the inner surface to the outer surface of the melting furnace section. The through hole and the pressure holding chamber having an internal space communicating with the through hole are disposed outside the melting furnace section, and are disposed in the pressure holding chamber, and heat is supplied to the melt discharged from the through hole. With a burner to add. The operation method includes forming a coke bed in the melting furnace section, supplying oxygen into the melting furnace section from a plurality of tuyere, discharging the melt from the through hole to the pressure holding chamber side, fuel, oxygen Is supplied to the burner, fuel is burned in the burner in the presence of oxygen, and the pressure in the holding pressure chamber is maintained higher than the pressure in the melting furnace section, so that the combustion gas of the burner is melted through the through hole. The amount of oxygen S _N supplied per unit time from the tuyere closest to the through hole into the melting furnace is melted from the tuyere far from the through hole than the tuyere. characterized by less than the oxygen amount S _F supplied per unit time in the furnace section.

  According to the above operation method, the melt is discharged from the through hole to the pressure holding chamber side, while the gas in the pressure holding chamber can be caused to flow into the furnace from the through hole so as to face the melt flow. . That is, the melt and the gas are counterflowed in the through hole. Thereby, the stable operation by continuous hot water supply is fully realizable. The reason is as follows. First, the melt discharged from the through hole can be heated with a flame of a burner. Thereby, the viscosity rise of a melt can be suppressed and obstruction | occlusion of a through-hole can be suppressed. Furthermore, the combustion gas generated from the burner can make the pressure in the pressure holding chamber higher than the pressure in the melting furnace. Thereby, combustion gas flows into a melting furnace part through a through-hole. That is, by making the pressure in the pressure holding chamber higher than the pressure in the melting furnace section, it is possible to prevent high temperature furnace gas from being discharged outside the furnace through the through-hole, and to maintain a sufficiently high temperature combustion gas. It can be made to flow through the through hole from the pressure chamber to the melting furnace. As a result, a decrease in the temperature in the melting furnace (furnace temperature) can be suppressed, and an increase in fuel to be introduced into the furnace can be sufficiently suppressed.

  Coke is used as fuel to be charged into the waste gasification melting furnace. In this case, a coke bed is formed in the melting furnace. By forming the coke bed in the melting furnace, the inside of the melting furnace can be stably maintained at a high temperature (for example, higher than 1700 ° C.). The size of the through hole is preferably set to a size that does not allow unburned coke (before charging into the furnace) to pass through. By adopting such a configuration, it is possible to suppress the coke charged in the furnace from being discharged from the through hole (see FIG. 2). Moreover, the inner surface side opening area of the through hole may be set larger than the outer surface side opening area. Increasing the inner opening area of the through-hole makes it easier to place coke halfway through the through-hole (see FIG. 4), thereby further reliably suppressing the temperature of the melt flowing through the through-hole from decreasing. it can. In addition, as long as a coke bed can be formed in a melting furnace part, you may use the thing derived from biomass as coke.

Furthermore, according to the above operation method, coke near the through hole is excessively consumed by relatively reducing the amount of oxygen _SN supplied from the tuyere near the through hole into the melting furnace section. Can be suppressed. This is useful to keep the coke bed thickness sufficiently uniform. That is, the coke near the through hole is consumed by the combustion gas of the burner flowing from the through hole, and is therefore more easily consumed than the coke in other regions. The reaction formula between the gas species that can be contained in the burner combustion gas and the carbon that constitutes the coke is as follows.
C + O ₂ → CO ₂ (1)
2C + O ₂ → 2CO (2)
C + CO ₂ → 2CO (3)
C + H ₂ O → H ₂ + CO (4)

  In this operation method, fuel and oxygen larger than the theoretical oxygen amount may be supplied to the burner. In this case, oxygen remains in the burner combustion gas. For this reason, the combustion gas (oxygen-containing gas) flowing into the melting furnace through the through-hole contributes to the combustion of coke located near the through-hole (the above reaction formulas (1) and (2)). In particular, by bringing the high-temperature coke and the melt into solid-liquid contact in the vicinity of the through hole, the melt can be discharged from the through hole while being maintained at a high temperature. In this case, coke near the through-hole is also consumed by the reactions of the above reaction formulas (3) and (4).

  The pressure in the pressure holding chamber may be maintained by water sealing. That is, the waste gasification and melting furnace is further provided with a water tank that is disposed below the through hole and that contains water for sealing the lower part of the pressure holding chamber and cooling the melt discharged from the through hole. May be.

  The waste gasification melting furnace may further include a valve for controlling the pressure in the holding pressure chamber. By operating this valve as needed, more stable operation can be realized. For example, when the pressure in the pressure holding chamber is maintained by water sealing as described above, the water sealing state is sufficiently maintained by preventing the pressure in the pressure holding chamber from rising excessively by operating the valve. it can. In normal times, as described above, the melt and gas flow in the through hole so as to face each other, whereas both the melt and the gas in the furnace pass from the through hole to the pressure holding chamber side as necessary. It may be allowed to be discharged. For example, when the viscosity of the melt tends to increase due to the composition or temperature of the melt, the pressure in the holding pressure chamber is temporarily lower than the pressure in the furnace, and the pressure difference is used to The molten material may be forcibly discharged to the pressure holding chamber side. In addition, by controlling the gas flow so that the high-temperature furnace gas passes through the through-hole for a predetermined time, the high-temperature furnace gas can reduce the viscosity of the melt around the through-hole. The blockage of the hole can be further reliably suppressed.

  The type of the waste gasification melting furnace is not particularly limited as long as it has a melting furnace section on the furnace bottom side. The waste gasification and melting furnace may further include, for example, a shaft portion that is located above the melting furnace portion and that dries and thermally decomposes the waste material filled therein. The shaft portion only needs to have a waste inlet and a furnace gas outlet on the upper side. The shaft portion may not be provided directly above the melting furnace portion. For example, the shaft portion and the melting furnace portion may be arranged with their cores shifted in the lateral direction. In this case, the waste gasification melting furnace may further include a communication part that connects the bottom side of the shaft part and the upper side of the melting furnace part. For example, the communicating portion may have a movable carbonization grate that transfers waste from the shaft portion toward the melting furnace portion and carbonizes the waste.

  According to the present invention, when the melt discharge through-hole is constantly opened for operation, an increase in coke to be introduced into the furnace can be sufficiently suppressed and a coke bed having a sufficiently uniform thickness can be obtained. The state formed in the furnace bottom can be maintained, and the through hole can be sufficiently prevented from being blocked due to the temperature drop of the melt in the through hole and its surroundings.

FIG. 1 is a longitudinal sectional view schematically showing one embodiment of a waste gasification melting furnace according to the present invention. FIG. 2 is a cross-sectional view schematically showing the positional relationship between the four tuyere in the melting furnace section and the through holes for discharging the melt. FIG. 3A is a cross-sectional view illustrating an example of the shape of the through hole, and FIG. 3B is a cross-sectional view illustrating a state in which solid matter is deposited below the through hole. FIG. 4 is an enlarged longitudinal sectional view showing a portion including the through hole of the melting furnace section. FIG. 5 is a cross-sectional view schematically showing the positional relationship between the six tuyere and the through holes in the melting furnace section. FIGS. 6A to 6C are images showing a state in which the fluidity of the melt is improved from the state where the discharge of the melt from the through hole is stopped to the situation where the melt flows out stably.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and a duplicate description is omitted.

<Waste gasification melting furnace>
A waste gasification melting furnace 10 shown in FIG. 1 includes a shaft portion 1, a communication portion 2, a carbonization grate portion 3, a melting furnace portion 4, a pressure holding chamber 6, and a burner 7 as main components. And a water tank 8. The shaft portion 1 dries waste in a reducing atmosphere and thermally decomposes it. The communication part 2 connects the shaft part 1 and the melting furnace part 4. The carbonization grate part 3 further thermally decomposes the waste from the shaft part 1 to carbonize the waste. The melting furnace section 4 burns and melts the carbonized waste. The melt M generated in the melting furnace section 4 is discharged to the pressure holding chamber 6 side through the through hole 4a. The pressure holding chamber 6 is for maintaining the pressure in the space outside the through hole 4a. The burner 7 is disposed in the pressure holding chamber 6 and is directed in the direction of the through hole 4a. The water tank 8 seals the lower part of the pressure holding chamber 6 and contains water for cooling the melt M discharged from the through hole 4a. Each configuration will be described below.

  The shaft portion 1 is for drying and thermally decomposing waste in a reducing atmosphere. The cross-sectional shape of the shaft portion 1 is, for example, a cylindrical shape. A waste charging inlet 11 for charging waste into the furnace is formed at the upper portion of the shaft portion 1. On the upper side of the shaft portion 1, an in-furnace gas discharge port 12 that discharges gas generated when the waste is dried, burned, and thermally decomposed is formed. An opening 13 is formed at the lower end of the shaft portion 1, and the waste that descends in the shaft portion 1 by its own weight is discharged from the opening 13 to the communication portion 2. The inner diameter and height of the shaft portion 1 can be appropriately determined according to the processing capacity of the furnace. For example, it is preferable that the height of the shaft portion 1 is a height at which the waste filling height in the shaft portion 1 can be managed at least 1 m from the lower end surface. By securing the filling height to 1 m or more, the blow-in phenomenon of the gas in the furnace can be suppressed in the shaft portion 1.

  The communication part 2 connects the bottom side opening 13 of the shaft part 1 and the upper side opening 46 of the melting furnace part 4. The vertical cross-sectional shape of the communication portion 2 is, for example, a rectangle, and the carbonized fire lattice portion 3 is disposed along the bottom surface. The carbonized grate part 3 further thermally decomposes the waste dried and thermally decomposed by the shaft part 1.

  The bottom surface of the communication part 2 is constituted by a carbonized grate part 3. As described above, the carbonized grate part 3 has not only a function for thermally decomposing waste (dry distillation), but also a function as a supply device for supplying the carbonized waste to the melting furnace part 4. The carbonization grate part 3 is formed by combining a movable carbonization grate and a fixed carbonization grate alternately in a staircase shape or an inclined shape. Each movable carbonization grate is configured to reciprocate at a constant pitch in the lateral direction by drive devices 31a and 31b such as fluid pressure cylinders (see double arrows in FIG. 1). By combining the movable carbonization grate and the fixed carbonization grate, the waste on the carbonization grate unit 3 can be pushed out from the upstream side to the downstream side while stirring. In addition, the carbonization grate part 3 may be composed of only a fixed carbonization grate, and a supply device may be provided separately. An example of the supply device is a pusher.

  The bottom surface of the communication part 2 is composed of a plurality of carbonized grate, and the whole is not a flat surface, but as a whole, it is inclined so as to become lower from the shaft part 1 side toward the melting furnace part 4 side. doing.

  The carbonization grate portion 3 has a two-stage structure including a supply carbonization grate 3A on the upper stage side and a dry distillation carbonization grate 3B on the lower stage side. The supply carbonization grate 3 </ b> A is located directly below the shaft portion 1 and directly receives a load of waste filled in the shaft portion 1. The supply carbonization grate 3A further thermally decomposes the waste so that carbonization of the dry and pyrolyzed waste at the shaft portion 1 proceeds and supplies the waste by pushing it to the dry distillation carbonization grate 3B. It is preferable that the width of the carbonization grate part 3, particularly the width of the supply carbonization grate 3 </ b> A, is approximately equal to the inner diameter of the shaft part 1. By making the width of the carbonization grate part 3 and the inner diameter of the shaft part 1 approximately the same at the place where the shaft part 1 is switched to the carbonization grate part 3, the unloading of the waste can be stabilized.

  The dry distillation carbonization grate 3B is provided adjacent to the supply carbonization grate 3A. The dry distillation carbonization grate 3B further decomposes the waste from the supply carbonization grate 3A to generate carbide, and pushes the carbonized waste to the melting furnace unit 4 to supply it. The dry distillation carbonization grate 3B has the same configuration as the supply carbonization grate 3A. The dry distillation carbonization grate 3B may have the same width as the supply carbonization grate 3A or a different width. Since the volume of waste is reduced with the progress of drying and thermal decomposition, the furnace bottom inner diameter of the melting furnace part 4 may be smaller than the inner diameter of the shaft part 1 and the width of the communication part 2. The width of the dry distillation carbonization grate 3B may be set so as to gradually decrease from the upstream side toward the downstream side.

  The movable carbonization grate of the supply carbonization grate 3A is driven by the first drive unit 31a, and the movable carbonization grate of the dry distillation carbonization grate 3B is driven by the second drive unit 31b. If the first and second driving devices 31a and 31b are provided independently of each other in this way, the driving, stopping and driving speed of the carbonization grate 3A, 3B can be controlled independently. As a result, the carbonization grate 3A, The waste supply rate by 3B can also be controlled independently.

  The carbonization grate portion 3 is configured such that air can be blown into the furnace from the entire surface through gaps between the carbonization grate and / or blow holes (not shown) formed in the carbonization grate. That is, the carbonization grate part 3 also has a function of blowing waste drying and pyrolysis air into the furnace.

  On the back side of the supply carbonization grate 3A and the carbonization carbonization grate 3B, there is a recovery chamber 32 for recovering when fine ones of carbonized waste fall from the gaps between the carbonization grates. Has been placed. Each recovery chamber 32 is configured so that a predetermined amount of air can be supplied from the blower 33 through the air supply pipe L1. It is preferable that the clearance gap between carbonization grate and / or the ventilation hole formed in the carbonization grate is 400 mm pitch or less, for example. The air supplied from the supply carbonization grate 3A and the dry distillation carbonization grate 3B may be at normal temperature, and may be preheated to about 200 ° C., for example. The preheating of air can be performed, for example, by heat exchange with the high temperature gas discharged from the furnace gas discharge port 12.

  The melting furnace section 4 is for burning and melting carbonized waste. The melting furnace part 4 is arranged so as to shift the furnace core laterally with respect to the shaft part 1 described above. The shaft portion 1 and the melting furnace portion 4 each extend in the vertical direction. By adopting such a configuration, coke (carbon-based solid fuel) can be directly introduced into the melting furnace section 4. The cross-sectional shape of the melting furnace part 4 is, for example, a cylindrical shape. An auxiliary material charging port 41 for charging coke or the like into the melting furnace unit 4 is provided above the melting furnace unit 4. In the present embodiment, the auxiliary material inlet 41 is formed on the upper surface of the communication portion 2 (see FIG. 1). A carbon-based combustible material other than coke may be charged from the auxiliary material inlet 41 together with coke, or limestone or slag as a basicity adjusting agent may be charged. The coke may be charged from the waste charging port 11 together with the waste.

  As shown in FIG. 2, four tuyere 42 a, 42 b, 42 c, 42 d are arranged in the circumferential direction on the furnace bottom side of the melting furnace section 4. Combustion oxygen is supplied into the melting furnace section 4 from the tuyere 42a, 42b, 42c, 42d. Note that oxygen may be supplied together with nitrogen or the like in the state of air or oxygen-enriched air, or high-purity oxygen may be supplied. Oxygen-enriched air means air having an oxygen concentration higher than that of normal air. By supplying oxygen into the melting furnace section 4, waste pyrolysis residue and coke C are combusted. The melting furnace section 4 may further include a plurality of tuyere (not shown) above the tuyere 42a, 42b, 42c, 42d.

  A through-hole 4 a for discharging the melt M (mixture containing molten slag and molten metal) is formed at the furnace bottom of the melting furnace section 4. The through-hole 4a is formed from the inner surface to the outer surface of the melting furnace part 4, and is constantly opened. Thereby, the molten material M can be continuously discharged from the through-hole 4a. The melt M discharged from the through hole 4a falls into the water stored in the water tank 8.

The size of the through hole 4a is preferably set to a size that does not allow the unburned coke C (before charging into the furnace) to pass through. By adopting such a configuration, it is possible to suppress the coke C charged in the furnace from being discharged from the through hole 4a (see FIG. 2). What is necessary is just to set the opening area of the through-hole 4a according to the size of the coke C to be used, the scale of the waste gasification melting furnace 10, etc., for example, about 50-500 cm < ² >. The shape of the through-hole 4a is not particularly limited and may be a circle, an ellipse, a rectangle, or the like. However, as shown in FIG. Thereby, as shown in FIG.3 (b), even if the solid S of the melt M gradually adheres from the lower side of the through hole 4a, the time until the through hole 4a is blocked can be made sufficiently long. it can. When the flow path cross section of the through-hole 4a is vertically long, the lateral width may be a width that does not allow unburned coke C to pass. For example, a V-shaped groove 4b may be provided below the through-hole 4a so that the melt M flows through the groove 4b (see FIG. 3A).

  FIG. 4 is an enlarged longitudinal sectional view showing a portion including the through hole 4 a of the melting furnace section 4. As shown in this figure, it is preferable that the lower side surface 4c through which the melt M flows in the through hole 4a is inclined so as to become lower from the inner surface of the melting furnace section 4 toward the outer surface. Thereby, it can suppress that the melt M stays in the through-hole 4a. Moreover, it is preferable that the inner surface side opening area of the through-hole 4a is larger than the outer surface side opening area. For example, the upper side of the through hole 4 a may have an expanded portion 4 d with a flow path cross section on the inner surface side of the melting furnace portion 4. In this case, as shown in FIG. 4, the coke C is likely to be disposed partway through the through hole 4a. By bringing the high-temperature coke C and the melt M into solid-liquid contact as close as possible to the through-hole 4a, the melt M that is maintained at a high temperature and has a sufficiently low viscosity can be discharged from the through-hole 4a.

  The pressure holding chamber 6 is for maintaining the pressure in the space outside the through hole 4a. As shown in FIG. 1, the pressure holding chamber 6 is disposed outside the melting furnace section 4, and has an internal space 6S communicating with the through hole 4a. The internal space 6S is formed by a cylindrical member 6a extending in the vertical direction, an upper plate 6b that closes the upper opening of the cylindrical member 6a, and a water surface W that seals the lower opening of the cylindrical member 6a. The cylindrical member 6a and the upper plate 6b are made of, for example, a steel plate material. The longitudinal cross-sectional shape of the cylindrical member 6a is a shape defined by, for example, two semicircles that are spaced apart from each other and two straight lines that connect the ends of these semicircles. In the present embodiment, the case where the pressure in the pressure holding chamber 6 is maintained by water sealing is exemplified, but pressure holding means other than water sealing may be employed. Further, an opening (not shown) for supplying an oxygen-containing gas (for example, air) may be provided in the pressure holding chamber 6. By supplying an oxygen-containing gas into the pressure holding chamber 6 through this opening, the oxygen concentration of the gas flowing from the pressure holding chamber 6 into the melting furnace section 4 may be adjusted.

  A burner 7 is disposed in the internal space 6S. Specifically, the burner 7 is disposed toward the through hole 4 a, and the through hole 4 a and its surroundings are heated by the flame of the burner 7. The type of the burner 7 is not particularly limited, and a burner that uses propane, kerosene, or the like as a fuel may be used. A heat insulating material 6c for keeping the internal space 6S warm is disposed in the pressure holding chamber 6 (except for the lower part immersed in water). It can suppress that the temperature of the combustion gas from the burner 7 falls by covering the inner surface of the steel plate (iron skin) which comprises the pressure-holding chamber 6 with the heat insulating material 6c. Thereby, when the pressure in the holding pressure chamber 6 is higher than the pressure in the melting furnace section 4, high-temperature combustion gas can be flowed into the melting furnace section 4 through the through holes 4 a. In addition, the exit periphery of the through-hole 4a is exposed to the flame of the burner 7 as mentioned above. For this reason, even if it comprises the part exposed to a flame with the outstanding heat resistant material, there exists a possibility of deteriorating within a comparatively short period. For this reason, the said part may be comprised with the member 4e which can be attached or detached, and you may enable it to replace | exchange regularly (refer FIG. 4). Further, from the viewpoint of preventing the melt M from adhering to the heat insulating material 6c, the steel plate 6e is disposed so as to cover a part or all of the heat insulating material 6c, and thereby a part or all of the inner wall of the pressure holding chamber 6 is covered. (See FIG. 1).

  The pressure holding chamber 6 has an opening 6d for discharging the gas in the internal space 6S. A gas transfer pipe L2 is connected to the opening 6d. The gas discharged from the opening 6d is introduced into the gas combustion furnace 9 through the gas transfer pipe L2. A valve V is provided in the middle of the gas transfer pipe L2. By adjusting the opening degree of the valve V, the pressure in the pressure holding chamber 6 can be adjusted. For example, the gas in the pressure holding chamber 6 is caused to flow into the melting furnace portion 4 through the through hole 4a by maintaining the pressure in the pressure holding chamber 6 higher than the pressure in the melting furnace portion 4 at normal times. Can do. On the other hand, the valve V may be operated so that the pressure in the pressure holding chamber 6 becomes lower than the pressure in the melting furnace section 4 at the time of abnormality. As a specific example at the time of abnormality here, when the pressure in the pressure holding chamber 6 becomes excessively high for some reason and the water seal state of the pressure holding chamber 6 cannot be maintained, or such a situation is likely to occur. The viscosity of the melt M tends to increase due to the composition or temperature of the melt M, and the melt M is forced to be discharged together with the outflow of gas from the melting furnace section 4.

  The increase in the viscosity of the melt M can be grasped by, for example, an image of a camera (not shown) disposed in the pressure holding chamber 6. The pressure in the pressure holding chamber 6 may be monitored by a pressure gauge (not shown). You may enable it to grasp | ascertain the obstruction | occlusion degree of the through-hole 4a by monitoring the differential pressure | voltage of the melting furnace part 4 and the holding pressure chamber 6. FIG. The operation of the waste gasification and melting furnace 10 is urgently stopped based on the pressure (differential pressure) and temperature data at a plurality of locations in the waste gasification and melting furnace 10 and the temperature and viscosity data of the melt M. You may be able to do it.

  The valve V may be configured to automatically open when the pressure in the pressure holding chamber 6 becomes equal to or higher than a threshold value. Alternatively, the opening degree of the valve V may be PID controlled so that the differential pressure between the pressure holding chamber 6 and the melting furnace unit 4 is kept constant.

  The water tank 8 seals the lower part of the pressure holding chamber 6 and contains water for cooling the melt M discharged from the through hole 4a. As shown in FIG. 1, the lower opening of the cylindrical member 6 a extends below the water surface. The melt M dropped from the through hole 4a is rapidly cooled with water in the water tank 8. As a result, slag (also referred to as “granulated slag”) and metal are obtained. A conveyor 8 a that conveys slag and metal out of the water tank 8 is installed at the bottom of the water tank 8. Slag (granulated slag) is a nonmagnetic component obtained by magnetic separation of a mixture obtained by cooling the melt.

<Waste treatment method>
Next, a waste processing method using the waste gasification melting furnace 10 will be described. Waste to be treated is charged into the shaft portion 1 from the waste inlet 11. The kind of waste is not particularly limited, and may be any of general waste and industrial waste. Shredding dust (ASR), excavated waste, incinerated ash, or the like, or a mixture of these and combustible waste can be treated. A waste filling layer 100 is formed in the shaft portion 1 by the waste. Waste or char dry-distilled from the waste inlet 11 may be input together with the waste.

  In the shaft portion 1, the drying of the waste and the heat are performed by heat exchange when the air blown from the carbonization grate portion 3 and the melting furnace portion 4 and the gas generated in the furnace pass through the waste filling layer 100. Decomposition proceeds. The heat generated by the waste itself is also used for drying and pyrolysis of the waste. The waste gradually descends in the shaft portion 1, reaches the supply carbonization grate 3A, is further thermally decomposed by the supply carbonization grate 3A, and then is sent to the dry distillation carbonization grate 3B. The waste is further thermally decomposed by the carbonized carbonization grate 3B and carbonization proceeds. The waste falls from the upper side opening 46 and is supplied to the melting furnace section 4.

  Waste carbonized from the communication part 2 is supplied to the melting furnace part 4. A packed bed 101 is formed in the melting furnace section 4 by the carbonized waste. Coke C and a basicity adjusting agent (for example, limestone) are charged into the melting furnace section 4 from the auxiliary material charging port 41 as necessary. Also, coke C and waste fixed carbon are combusted by blowing oxygen-enriched air from the tuyere 42a, 42b, 42c, 42d. As a result, a high-temperature coke bed Bc is formed at the bottom of the furnace, and the ash and incombustible components contained in the waste are melted by the heat. On the other hand, the high-temperature gas discharged from the in-furnace gas discharge port 12 recovers waste heat with an apparatus such as a boiler, and then discharges it after detoxifying. In addition, by forming the coke bed Bc in the melting furnace part 4, the inside of the melting furnace part 4 can be stably maintained at a high temperature state (for example, higher than 1700 ° C.).

  The filling height of the waste in the melting furnace section 4 during operation should be maintained within a range from +0.5 m above the tuyere 42 a, 42 b, 42 c, 42 d to the lowest end of the carbonized fire grate section 3. Is preferred. By maintaining within this range, oxygen leakage from the furnace bottom due to the thin layer thickness of the packed bed 101 can be suppressed. Furthermore, it is possible to suppress the degradation of the thermal decomposition efficiency of the carbonized grate portion 3 and the stagnation of the distribution in the melting furnace portion 4 due to overfilling.

  The filling height of the waste in the melting furnace part 4 can be controlled by adjusting the speed at which the carbonization grate part 3 supplies the waste to the melting furnace part 4. For example, a sensor (not shown) for detecting the height of the packed bed 101 is disposed in the melting furnace section 4 and the supply rate of the carbonization grate section 3 is controlled based on the height of the packed bed 101 detected by the sensor. May be. Alternatively, for example, the operator may monitor the filling height and control the supply speed based on the monitoring result.

  The supply rate (V1) of the supply carbonization grate 3A and the supply rate (V2) of the dry distillation carbonization grate 3B may be set to be relatively different or may be set to be the same. When the supply rate is set to be relatively different, it is preferable to set the supply rate (V2) of the dry distillation carbonization grate 3B to be higher than the supply rate (V1) of the supply carbonization grate 3A. Furthermore, it is more preferable to variably control the supply rate (V1) of the feed carbonization grate 3A while keeping the supply rate (V2) of the carbonization grate 3B constant. By making the supply rate V2 higher than the supply rate V1, the waste sent from the supply carbonization grate 3A can be expanded so as to form a relatively thin layer on the dry distillation carbonization grate 3B. Thereby, the heat from the dry distillation carbonization grate 3B can be applied to the entire waste layer, and the carbonization state of the entire waste can be sufficiently improved.

  For example, the waste material may be charged not only from the waste material inlet 11 but also from the auxiliary material material inlet 41. For example, it is preferable that waste with a large amount of water is supplied from the waste inlet 11 and supplied to the melting furnace section 4 after being processed in the shaft section 1 and the carbonized fire grate section 3. On the other hand, waste with a large amount of ash and low moisture can be loaded from the auxiliary material inlet 41 to reduce drying and pyrolysis loads in the shaft portion 1 and the carbonized grate portion 3. An example of waste with a large amount of water is sludge, and an example of waste with a large amount of ash is incinerated ash. The waste loading port may be provided at a place other than the waste loading port 11 and the auxiliary material loading port 41. By appropriately changing the position where the waste is charged into the furnace based on the properties of the waste, the load on the entire furnace can be reduced as a result.

Next, regarding the case where the waste gasification melting furnace 10 is operated in a state where the through-holes 4a are constantly opened, the following four types of operation methods will be specifically described. According to these operation methods, stable operation by continuous hot water can be sufficiently realized. You may combine suitably each process and conditions of these operation methods as needed.
1. 1. Gas flow control in the through hole 4a 2. Adjust the amount of oxygen supplied to the burner 7. 3. Adjustment of oxygen amount supplied from tuyere 42a, 42b, 42c, 42d Insert slag as needed from the auxiliary material inlet 41

1. Gas flow control in the through-hole 4a This operating method includes the following steps.
The melt M is discharged from the through hole 4a to the pressure holding chamber 6 side.
Supply fuel and oxygen to the burner 7.
Burning fuel in the burner 7 in the presence of oxygen.
By maintaining the pressure in the pressure holding chamber 6 higher than the pressure in the melting furnace section 4, the gas in the pressure holding chamber 6 is caused to flow into the melting furnace section 4 through the through holes 4 a.

  According to this operation method, the melt M discharged from the through hole 4 a can be heated by the flame of the burner 7. Thereby, the viscosity rise of the melt M can be suppressed and obstruction | occlusion of the through-hole 4a can be suppressed. Further, the pressure in the holding chamber 6 (for example, 1.5 to 2.5 kPa (gauge pressure)) is changed to the pressure in the melting furnace section 4 (for example, 1.0 to 2.0 kPa (gauge) by the combustion gas generated from the burner 7. Pressure)). Thereby, combustion gas flows into the melting furnace part 4 through the through-hole 4a. That is, by making the pressure in the pressure holding chamber 6 higher than the pressure in the melting furnace section 4, it is possible to prevent high-temperature furnace gas from being discharged outside the furnace through the through-hole 4 a, and a sufficiently high temperature. The combustion gas can be flowed from the holding pressure chamber 6 to the melting furnace section 4 through the through hole 4a. As a result, a decrease in the temperature (in-furnace temperature) in the melting furnace section 4 can be suppressed, and an increase in fuel to be introduced into the furnace can be sufficiently suppressed. In addition, if the temperature of the combustion gas which passes through the through-hole 4a is 1200 degreeC or more (more preferably about 1300 degreeC), it can fully suppress that the melt M solidifies around the through-hole 4a. The melting point of the slag contained in the melt M is about 1175 ° C. although it depends on its composition.

  When attention is paid to the flow of the melt M and the combustion gas in the through hole 4a, the melt M and the gas are counterflowing in the through hole 4a. In order to stably discharge the melt M from the through hole 4a, it is preferable that the flow of the melt M is sufficiently separated from the flow of the combustion gas in the through hole 4a. That is, when the fluid flow in the through hole 4a is regarded as an opposed gas-liquid two-phase flow, it is preferable that the melt M forms a separated flow (a laminar flow or a wave flow). From this point of view, the opening area of the through hole 4a, the size of the coke C, the flow rate of the gas flowing into the melting furnace section 4 from the pressure holding chamber 6 and the like may be set. For example, the flow rate of the combustion gas passing through the through hole 4a is preferably 0 to 20 Bm / s, more preferably 3 to 10 Bm / s. The unit of flow velocity “Bm / s” means the flow velocity under the in-situ temperature and pressure conditions.

  In addition, although the case where the coke bed Bc was formed in the melting furnace part 4 was illustrated in this embodiment, you may implement this operating method on the conditions in which the coke bed Bc is not formed in the melting furnace part 4.

2. Adjustment of oxygen amount supplied to burner This operating method includes the following steps.
Forming a coke bed Bc in the melting furnace section 4;
The melt M is discharged from the through hole 4a to the pressure holding chamber 6 side.
Supply fuel and oxygen in excess of the theoretical oxygen amount to the burner 7.
Combusting the fuel in the burner 7 under a condition where oxygen is higher than the theoretical oxygen amount.
By maintaining the pressure in the holding pressure chamber 6 higher than the pressure in the melting furnace section 4, the oxygen-containing gas in the holding pressure chamber 6 flows into the melting furnace section 4 through the through holes 4 a.

  According to this operation method, the melt M discharged from the through hole 4 a can be heated by the flame of the burner 7. Thereby, the viscosity rise of the melt M can be suppressed and obstruction | occlusion of the through-hole 4a can be suppressed. Furthermore, the pressure in the holding pressure chamber 6 can be made higher than the pressure in the melting furnace section 4 by the combustion gas generated from the burner 7. Thereby, combustion gas flows into the melting furnace part 4 through the through-hole 4a. That is, by making the pressure in the pressure holding chamber 6 higher than the pressure in the melting furnace section 4, it is possible to prevent high-temperature furnace gas from being discharged outside the furnace through the through-hole 4 a, and a sufficiently high temperature. The combustion gas can be flowed from the holding pressure chamber 6 to the melting furnace section 4 through the through hole 4a. As a result, a decrease in the temperature (in-furnace temperature) in the melting furnace section 4 can be suppressed, and an increase in fuel to be introduced into the furnace can be sufficiently suppressed.

  Further, in this operation method, fuel and oxygen larger than the theoretical oxygen amount are supplied to the burner 7. For this reason, oxygen remains in the combustion gas of the burner 7. The combustion gas (oxygen-containing gas) flowing into the melting furnace part 4 through the through hole 4a contributes to the combustion of the coke C located near the through hole 4a. In particular, by bringing the high-temperature coke C and the melt M into solid-liquid contact in the vicinity of the through hole 4a, the melt M that is maintained at a high temperature can be discharged from the through hole 4a.

  The method of operation may further include temporarily increasing the amount of oxygen relative to the fuel. Thereby, the amount of oxygen remaining in the combustion gas can be temporarily increased. By performing such an operation, the oxygen concentration of the gas flowing into the melting furnace section 4 through the through hole 4a is increased. Thereby, combustion of the coke C near the through hole 4a in the melting furnace part 4 is promoted, and as a result, the temperature of the region can be temporarily increased. This tends to increase the viscosity of the melt due to a decrease in the composition of the melt M or the temperature, and is effective as an improvement measure in the case where solid content is observed around the through-holes.

  The present inventors performed the following evaluation tests in a waste gasification melting furnace having the same configuration as the waste gasification melting furnace 10 shown in FIG. That is, the burner was operated by further increasing the amount of oxygen supplied to the burner from the state where the burner was operated with oxygen larger than the theoretical oxygen amount (burner oxygen ratio exceeding 1). As a result, when the burner oxygen ratio was increased, it was confirmed that the coke seen from the through hole was red hot. Accompanying this, it was confirmed that the viscosity of the melt was lowered, in other words, an effect of improving fluidity was obtained. The burner oxygen ratio here means the ratio (Os / Ot) of the amount of oxygen (theoretical oxygen amount) Ot required for complete combustion of the fuel supplied to the burner and the amount of oxygen Os supplied to the burner. To do.

3. Adjustment of oxygen amount supplied from tuyere 42a, 42b, 42c, 42d This operation method includes the following steps.
Forming a coke bed Bc in the melting furnace section 4;
Supply oxygen from the tuyere 42a, 42b, 42c, 42d into the melting furnace 4 respectively.
The melt M is discharged from the through hole 4a to the pressure holding chamber 6 side.
Supply fuel and oxygen to the burner 7.
Burning fuel in the burner 7 in the presence of oxygen.
By maintaining the pressure in the holding pressure chamber 6 higher than the pressure in the melting furnace section 4, the combustion gas of the burner 7 is caused to flow into the melting furnace section 4 through the through holes 4 a.
In this operation method, the amount of oxygen S _N supplied per unit time from the tuyere 42a, 42d closest to the through hole 4a into the melting furnace section 4 is more from the through hole 4a than the tuyere 42a, 42d. distance is less than the amount of oxygen S _F supplied far tuyere 42b, per unit time in the melting furnace section 4 from 42c.

  According to this operation method, the melt M discharged from the through hole 4 a can be heated by the flame of the burner 7. Thereby, the viscosity rise of the melt M can be suppressed and obstruction | occlusion of the through-hole 4a can be suppressed. Furthermore, the pressure in the holding pressure chamber 6 can be made higher than the pressure in the melting furnace section 4 by the combustion gas generated from the burner 7. Thereby, combustion gas flows into the melting furnace part 4 through the through-hole 4a. That is, by making the pressure in the pressure holding chamber 6 higher than the pressure in the melting furnace section 4, it is possible to prevent high-temperature furnace gas from being discharged outside the furnace through the through-hole 4 a, and a sufficiently high temperature. The combustion gas can be flowed from the holding pressure chamber 6 to the melting furnace section 4 through the through hole 4a. As a result, a decrease in the temperature (in-furnace temperature) in the melting furnace section 4 can be suppressed, and an increase in fuel to be introduced into the furnace can be sufficiently suppressed.

Furthermore, coke C near the through-hole 4a is excessively consumed by relatively reducing the amount of oxygen _SN supplied into the melting furnace section 4 from the tuyere 42a and 42d near the through-hole 4a. This is useful for maintaining a sufficiently uniform thickness of the coke bed Bc. That is, the coke C near the through-hole 4a is consumed by the combustion gas of the burner 7 flowing from the through-hole 4a, so that it is more easily consumed than the coke C in other areas. The reaction formula of the gas species that can be included in the combustion gas of the burner 7 and the carbon constituting the coke C is as follows.
C + O ₂ → CO ₂ (1)
2C + O ₂ → 2CO (2)
C + CO ₂ → 2CO (3)
C + H ₂ O → H ₂ + CO (4)

  The amount of oxygen supplied per unit time from the tuyere 42a, 42b, 42c, 42d is consumed as uniformly as possible in the coke C constituting the coke bed Bc (so that the thickness of the coke bed Bc does not become non-uniform). ), You can set each. If it demonstrates referring FIG. 2, in the cross section of the melting furnace part 4, it will be divided into two area | regions of the side (right side of FIG. 2) containing the through-hole 4a, and the side (left side of FIG. 2) which does not contain the through-hole 4a. What is necessary is just to divide the melting furnace part 4 and balance the coke consumption per unit time in these two area | regions. First, the consumption per unit time of the whole coke is set based on the temperature required at the furnace bottom of the melting furnace section 4. The amount of coke consumed per unit time of the entire coke bed Bc is balanced with the amount of coke charged into the melting furnace section 4. Assuming that the coke consumption per unit time of the entire coke bed Bc is 100, 25 cokes may be consumed per unit time by oxygen supplied from the tuyere 42b and 42c, respectively. Next, the amount of combustion gas flowing from the through hole 4a and the composition thereof are set based on the amount of heat necessary for heating around the through hole 4a. If the amount of combustion gas and its composition are determined, the amount of coke consumed per unit time by the combustion gas can be determined based on the reaction formulas (1) to (4). If the coke consumption is 20, the amount of coke to be consumed per unit time by oxygen from the remaining two tuyere 42a and 42d is 30. Then, in this case, the amount of coke to be consumed per unit time by oxygen from the tuyere 42a and 42d is 15 respectively.

  The present inventors are provided with two tuyere (a tuyere close to the through-hole and a tuyere far from the through-hole) near the bottom of the melting furnace section, and the waste gasification and melting shown in FIG. The following evaluation test was performed in a waste gasification melting furnace having the same configuration as that of the furnace 10. In other words, considering the consumption of coke by the combustion gas flowing in from the through hole, the oxygen supply from the tuyere close to the through hole is less than the oxygen supply from the tuyere far from the through hole, and waste gasification and melting The furnace was operated for 500 hours. As a result, the melt can be discharged stably and continuously from the through-hole 4a, and the thickness of the coke bed can be maintained sufficiently uniform (the thickness of the coke bed becomes non-uniform). There was no indication that this was happening.) Propane gas was used as the burner fuel, and the burner was operated with more oxygen than the theoretical oxygen amount (over 1 burner oxygen ratio). Considering the amount of coke consumed by the reactions of the above reaction formulas (1) to (4), the oxygen supply amount from the tuyere close to the through hole was reduced from the oxygen supply amount from the tuyere far from the through hole.

  The number of tuyere is not limited to four, but may be two or more. FIG. 5 is a cross-sectional view schematically showing the melting furnace section 4 provided with six tuyere 42a to 42f. The horizontal cross-sectional shape of the melting furnace part 4 shown in FIG. 5 is an ellipse. By making the shape of the melting furnace part 4 into an elliptical shape, there is an advantage that heat generated by oxygen supplied from the tuyere 42a to 42f can easily reach the center of the melting furnace part 4 as compared with a circular shape. .

  In this operation method, when fuel and oxygen larger than the theoretical oxygen amount are supplied to the burner 7, oxygen remains in the combustion gas of the burner 7. The combustion gas (oxygen-containing gas) flowing into the melting furnace section 4 through the through hole 4a contributes to the combustion of the coke C located near the through hole 4a (the above reaction formulas (1) and (2)). In particular, by bringing the high-temperature coke C and the melt M into solid-liquid contact in the vicinity of the through-hole 4a, the melt M can be discharged from the through-hole 4a while being maintained at a high temperature. In this case, the coke C near the through hole 4a is also consumed by the reactions of the reaction formulas (3) and (4).

  In this operation method, when fuel and oxygen smaller than the theoretical oxygen amount are supplied to the burner 7, almost no oxygen remains in the combustion gas of the burner 7. In this case, coke C near the through hole 4a is consumed mainly by the reactions of the above reaction formulas (3) and (4). Although the combustion gas (combustion gas containing almost no oxygen) flowing into the melting furnace section 4 through the through-hole 4a does not contribute to the combustion of the coke C, the combustion gas is sufficiently high in temperature, so the inside of the melting furnace section 4 This contributes to the maintenance of the temperature (furnace temperature).

4). If necessary, slag is charged from the auxiliary material inlet 41. This operation method includes the following steps.
Discharging the melt M out of the furnace from the through hole 4a.
Monitor the flow of the melt M discharged from the through hole 4a.
The slag obtained by the gasification melting treatment of the waste is charged into the melting furnace unit 4 from the auxiliary material inlet 41 in accordance with the decrease in the fluidity of the melt M.

  According to this operation method, the flowability of the melt M discharged from the through-hole 4a is obtained by charging the slag obtained by the gasification and melting treatment of the waste into the melting furnace section 4 from the auxiliary material inlet 41. Can be improved quickly enough. The reason is as follows. First, it is not necessary to sample the slag obtained from the melt M and actually measure its basicity. Secondly, according to the waste gasification melting furnace 10, the slag can be directly supplied from the auxiliary material inlet 41 to the melting furnace section 4. By improving the deterioration of the fluidity of the melt M sufficiently quickly, the state in which the melt M is stably discharged from the through holes 4a can be sufficiently maintained.

  The flow of the melt M is monitored, for example, by installing a video camera (not shown) outside the through-hole 4a (on the pressure holding chamber 6 side), and the flow of the melt M around the through-hole 4a and its periphery is determined by the image. It can be implemented by observing the operator. More specifically, the state of the melt M flowing through the through-hole 4a (see FIG. 6) or the state of flowing down on the surface of the member 4e from the outlet of the through-hole 4a may be set as the observation target.

When it is determined by monitoring the flow of the melt M that the fluidity of the melt M has decreased compared to the normal time, slag is charged from the auxiliary material inlet 41 into the melting furnace section 4. Here, “normal time” means a state in which the melt M is stably discharged from the through hole 4a. On the other hand, specific examples of the situation to be judged as “the fluidity of the melt M has decreased” include the following.
-When the melt M is not discharged | emitted from the through-hole 4a over a fixed time or more (for example, 300 second or more).
-Although the melt M is discharged | emitted from the through-hole 4a, when the speed of the melt M which flows down on the wall surface near the through-hole 4a is slow compared with the normal time.
-When the pressure difference between the pressure in the melting furnace section 4 and the pressure in the holding pressure chamber 6 tends to increase (when the through hole 4a tends to be closed).
Whether or not the slag is actually loaded may be determined by an operator observing the image, or automatically determined based on image processing data or operation data (for example, differential pressure data). May be.

The slag charged from the auxiliary material charging port 41 may be any slag obtained by the gasification and melting treatment of waste, and may be a granulated slag recovered from the water tank 8 of the waste gasification and melting furnace 10. It may be slag obtained in another waste gasification melting furnace. From the viewpoint of exhibiting the effect of improving the fluidity of the melt M sufficiently quickly in the melting furnace section 4, the slag is preferably powdery or granular. In the melting furnace section 4, from the viewpoint of sufficiently diluting the cause of the fluidity deterioration of the melt M, the basicity of the slag charged from the auxiliary material charging port 41 is preferably 0.8 to 1.0. . The “basicity” here is a mass ratio (CaO / SiO ₂ ) between CaO and SiO ₂ contained in the slag, and can be determined by elemental analysis using a fluorescent X-ray analyzer.

  In this operation method, when the deterioration of the fluidity of the melt M is recognized, the slag may be immediately charged from the auxiliary material inlet 41 into the melting furnace section 4. The basicity of the molten slag in the melting furnace section 4 can be returned to a range suitable for flow by charging the slag to be a molten slag having fluidity suitable for the temperature in the melting furnace section 4. That is, if the basicity of the molten slag in the melting furnace section 4 is lower than the lower limit value (for example, 0.8) of the setting range, this can be increased, while the basicity of the molten slag in the melting furnace section is set within the setting range. If it is higher than the upper limit value (for example, 1.0), it can be lowered. In this operating method, the basicity of the molten slag in the melting furnace section 4 is not intended to be within a predetermined range, and when the fluidity of the molten slag in the melting furnace section 4 deteriorates, It is to improve quickly. In contrast, seasonal fluctuations in the basicity of molten slag are dealt with by regularly measuring the basicity of the slag and adjusting the amount of basicity adjusting agent (for example, limestone) based on the measurement results. do it.

  There is no restriction | limiting in particular in the quantity of the said slag charged into the melting furnace part 4 from the submaterial charging port 41. FIG. Monitoring of the state where the melt M discharged from the through hole 4a flows is continued, and if the effect of improving the fluidity is insufficient, the slag may be charged again. As described above, the slag can be directly supplied from the auxiliary material inlet 41 to the melting furnace section 4, and thereby the fluidity improvement effect can be achieved in a short time (for example, about 3 minutes). Therefore, after supplying the slag, it can be determined in a sufficiently short time whether the effect of improving the fluidity is sufficient, and it can be determined whether the slag should be supplied again. In addition, since the slag supplied to the melting furnace unit 4 has an appropriate basicity, even if it is excessively supplied to the melting furnace unit 4, it does not affect the stable operation of the waste gasification melting furnace 10. Specifically, it can be limited to the extent that the consumption of coke C in the melting furnace section 4 temporarily increases as slag having a low temperature is excessively supplied. Therefore, even if the fluidity of the melt M is not actually lowered, the slag may be supplied from the auxiliary material charging port 41 to the melting furnace section 4 when such signs are observed.

  In the waste gasification melting furnace similar to the waste gasification melting furnace 10 shown in FIG. 1, the present inventors performed an evaluation test for improving melt fluidity by slag. According to this evaluation test, when 10 kg of slag (basicity 0.8 to 1.0) is charged 1 to 3 times from the auxiliary material inlet into the melting furnace part, the effect of improving the fluidity of the melt was gotten. From the auxiliary material inlet of the waste gasification and melting furnace, operation was performed while charging about 10 kg of coke every 15 minutes and 10 kg of limestone (basicity adjusting agent) every 15 minutes. .

  FIG. 6 is an image obtained by photographing the through hole from the pressure holding chamber side. FIG. 6A shows a state where the discharge of the melt from the through hole is stopped. When this image was taken, the supply of slag from the auxiliary material inlet to the melting furnace was started. FIG. 6B shows an image about 1 minute after the start of slag supply, and FIG. 6C shows an image about 3 minutes after the start of slag supply. As can be seen from these images, an effect of improving the fluidity of the melt was obtained about 3 minutes after the start of slag supply.

  In this embodiment, although the case where the said slag was supplied to the melting furnace part 4 in the operation form of continuous hot water was illustrated, when it was recognized that the fluidity | liquidity of a melt was inadequate in the operation form of intermittent hot water. The slag may be supplied to the melting furnace section 4.

  As mentioned above, although embodiment of this invention was described in detail, various substitution, a deformation | transformation, a change, etc. about a form and detail deviate from the mind and range of this invention as prescribed | regulated by description of a claim. It is clear to those having ordinary knowledge in the art that it can be done without any problems. Therefore, the scope of the present invention should not be limited to the above-described embodiment and the accompanying drawings, but should be determined based on the description of the claims and equivalents thereof.

  For example, in the above-described embodiment, the waste gasification melting furnace 10 (also referred to as “low carbon type shaft furnace”) including the shaft portion 1, the melting furnace portion 4, and the communication portion 2 that connects them. However, the present invention does not include the communication part 2 and is a waste gasification melting furnace (“shaft furnace type gasification melting furnace”) in which the shaft part 1 is disposed directly above the melting furnace part 4. (However, “4. Inserting slag as needed from the auxiliary material inlet 41” is excluded). In addition, the low carbon type shaft furnace has an advantage that the amount of coke to be used can be reduced and the pressure fluctuation of the melting furnace section 4 is small as compared with the shaft furnace type gasification melting furnace.

DESCRIPTION OF SYMBOLS 1 ... Shaft part, 2 ... Communication part, 3 ... Carbonization grate part, 4 ... Melting furnace part, 4a ... Through-hole, 6 ... Holding pressure chamber, 7 ... Burner, 10 ... Waste gasification melting furnace, 11 ... Disposal Material inlet, 12 ... Furnace gas outlet, 42a-42f ... tuyere, Bc ... coke bed, C ... coke, V ... valve.

Claims (8)

An operation method of a waste gasification melting furnace,
The waste gasification melting furnace is
A melting furnace located on the furnace bottom side;
A plurality of tuyere supplying oxygen from different positions into the melting furnace part,
A through hole formed from the inner surface to the outer surface of the melting furnace part;
A pressure holding chamber disposed outside the melting furnace portion and having an internal space communicating with the through hole;
A burner that is disposed in the pressure-holding chamber and that heats the melt discharged from the through hole;
With
Forming a coke bed in the melting furnace section,
Supplying oxygen into the melting furnace from the plurality of tuyere,
Discharging the melt from the through hole to the pressure holding chamber side;
Supplying fuel and oxygen to the burner;
Burning the fuel in the burner in the presence of oxygen;
Maintaining the pressure in the pressure-holding chamber higher than the pressure in the melting furnace part, allowing the combustion gas of the burner to flow into the melting furnace part through the through-hole,
Including
The amount of oxygen S _N supplied per unit time from the tuyere closest to the through hole into the melting furnace section is transferred from the tuyere far from the through hole to the inside of the melting furnace section. It is less than the amount of oxygen S _F supplied per unit time, the method of operating waste gasification melting furnace.   The operation method according to claim 1, wherein fuel and oxygen larger than a theoretical oxygen amount are supplied to the burner.   The waste gasification melting furnace is disposed below the through hole, and has a water tank for sealing the lower part of the pressure holding chamber and containing water for cooling the melt discharged from the through hole. The operation method according to claim 1, further comprising: The waste gasification and melting furnace further includes a valve for controlling the pressure in the holding chamber,
In normal time, by maintaining the pressure in the pressure holding chamber higher than the pressure in the melting furnace portion, the gas in the pressure holding chamber flows into the melting furnace portion through the through hole,
Operating the valve so that the pressure in the pressure-holding chamber is lower than the pressure in the melting furnace during an abnormality,
The driving | running method as described in any one of Claims 1-3 containing these.   The size of the said through-hole is a driving | operation method as described in any one of Claims 1-4 set to the size which an unburned coke does not pass.   The operation method according to any one of claims 1 to 5, wherein an inner surface side opening area of the through hole is larger than an outer surface side opening area. The waste gasification melting furnace is further provided with a shaft part that is located above the melting furnace part and that dries and thermally decomposes the waste material filled therein,
The said shaft part is a driving | running method as described in any one of Claims 1-6 which has a waste loading inlet and the gas discharge port in a furnace in the upper part side. In the waste gasification melting furnace, the shaft part and the melting furnace part are arranged with their respective cores shifted laterally, and connect the bottom side of the shaft part and the upper side of the melting furnace part. A communication part,
The communication part has a movable carbonization grate that transfers waste from the shaft part toward the melting furnace part and carbonizes the waste,
The operating method according to claim 7, comprising directly introducing coke into the melting furnace section.