JP2006084064A - Ash melting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent attachment of slag from a slag tap to a slag drop cylinder, and coagulative fixing of chloride in an combustion gas for heating slag, to piping. <P>SOLUTION: In this ash melting device comprising the slag tap 38 for dropping the slag from an ash melting furnace, the slag drop cylinder 39 connected with the slag tap, and a water tank mounted at a lower part of the slag drop cylinder, a combustion gas extracting part 60 is formed in a state of surrounding a lower outer periphery of the slag drop cylinder, a lower end of the combustion gas extracting part is mounted at a lower part with respect to a water level of the water tank, a clearance 65 is formed between a lower end of the slag drop cylinder and the water level of the water tank, and the combustion gas of the ash melting furnace is successively passed through the slag tap 38, the slag drop cylinder 39, the clearance 65 and the combustion gas extracting part 60. Further a nozzle 64 is mounted for jetting the water to the inclined piping 61, and the jetted water from the nozzle flows toward the combustion gas extracting part 60. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refuse gasification melting system, and more particularly, to an ash melting apparatus suitable for improving reliability and reducing maintenance costs when discharging slag in a melting furnace.

  In recent years, gasification and melting furnace systems that melt and detoxify ash using the combustion heat of garbage itself are being put into practical use. FIG. 3 is a block diagram showing the entire system of a waste gasification and melting system related to the prior art. For the names of the components in the overall configuration shown in FIG.

  In FIG. 3, the waste is supplied from the feed hopper 1 to the gasification furnace 6 through the fixed amount feeder 2 and the supply chute 5. The air blown into the fluidized bed 8 through the pipe 21 reacts with dust to generate pyrolysis gas. The temperature of the fluidized bed 8 is maintained at about 600 ° C. by this thermal decomposition reaction heat (partial combustion heat). The fluidized bed type gasification furnace 6 is operated at an air ratio of 1 or less and an air ratio of 0.3 to 0.6 for ordinary waste.

  The air ratio is controlled so that the temperature of the gasification furnace 6 including the fluidized bed is about 900 ° C. or less in order to avoid the ash melting and sticking trouble in the gasification furnace 6. That is, if the fluidized bed and the furnace temperature are too high, the air ratio of the gasification furnace 6 is lowered. If the temperature is too low, the furnace temperature is controlled by increasing the air ratio. is doing. In many cases, the fluidized bed 8 usually uses sand having a particle diameter of about 1 mm as an in-layer medium. That is, the fluidized bed is filled with fine sand.

  On the other hand, coarse incombustible foreign matter is usually mixed in the waste, and these incombustible foreign matter is deposited at the bottom of the fluidized bed 8. Since fluidization is hindered when a large amount of incombustible foreign matter is deposited in the fluidized bed, the incombustible foreign matter is extracted regularly or continuously using the discharge device 22. At that time, the fine in-layer medium is also mixed with incombustible foreign matter and discharged.

  The mixture of the coarse incombustible foreign matter and the fine in-layer medium discharged by using the discharge device 22 separates the fine in-layer medium by the fluid 43 and returns to the fluidized bed 8 through the pipe 30 to be reused as the in-layer medium. . On the other hand, coarse incombustible foreign matter that hinders fluidization is discharged through a pipe 44, and valuables such as iron and aluminum in the non-combustible foreign matter are separated using a metal separator 45 or the like and collected through a pipe 47. On the other hand, the remaining coarse incombustible foreign matter mainly composed of rubble is discharged from the pipe 46 and disposed of in landfill.

  The pyrolysis gas and char generated from the garbage in the gasification furnace 6 enter the melting furnace 9 through the flue 12 and react with the air blown into the melting furnace 9 through the pipe 20 to be completely burned. Most of the ash contained in the char is melted by the high heat of the melting furnace 9 and becomes slag and is discharged out of the system via the slag tap 38, the slag dropping cylinder 39, and the slag discharge device 11.

  Since the melting furnace 9 is a high-temperature combustion furnace at 1,300 ° C. or higher, a large amount of thermal NOx is generated when excess air combustion is performed. On the other hand, if the air ratio is lowered too much, a large amount of unburned CO is generated. If it is a certain amount of CO, it can be burned completely with the air blown in the secondary combustion furnace 24 in the subsequent stage, but if it is too much CO, it cannot be burned completely in the secondary combustion furnace 24, and the boiler 3, the gas quenching tower 13, It will be discharged into the atmosphere from the chimney 17 via the dust collector 15.

Considering the balance of NOx and CO, the melting furnace 9 is controlled so that the air ratio is in the vicinity of 0.9 to 1.05. The exhaust gas from the melting furnace 9 containing some CO and NOx enters the secondary combustion furnace 24 and completely burns CO with the air blown from the air nozzle 42. The air ratio in the secondary combustion furnace 24 is normally controlled to be about 1.2 to 1.3 in order to cause complete combustion. If the air ratio is too high, the amount of exhaust gas will increase unnecessarily, resulting in a large sensible heat loss of the exhaust gas and a decrease in boiler efficiency, and a decrease in the furnace temperature due to the tempering effect caused by excess air not involved in combustion. CO combustion is hindered. Therefore, control of the air ratio of the secondary combustion furnace 24 is also important. A CO meter 58 at the outlet of the dust collector 15 is installed to monitor the CO that has not been burned out in the secondary combustion furnace 24.
The completely burned exhaust gas is purified through the boiler 3, the air heater 14, the gas quenching tower 13, and the dust collector 15, and discharged from the chimney to the atmosphere. The collected ash in the dust collector 15 is generated by the reaction between the fine ash that has passed through the melting furnace 9 and the low-boiling substances that have become fumes condensed in the flue leading to the dust collector 15, as well as acid gas and slaked lime. It consists of a Ca compound. The dust ash is sent to an ash stabilization facility through a pipe 48 and stabilized by chemicals, and then disposed of in landfill.

  Since the amount of heat generated from garbage is low, the temperature of the melting furnace 9 can only be maintained at a temperature slightly higher than the flow temperature of ash. The molten slag drops from the slag tap 38 from the melting furnace, drops in the slag dropping cylinder 39, is cooled by the water stored in the slag discharge device 11, and becomes granulated slag.

  In the gasification melting system, the melting furnace 9 is the hottest part. That is, the slag after being discharged from the melting furnace 9 is being cooled. For this reason, in the case of slag that is difficult to melt, there is often a problem that the slag is in a molten and flowing state in the melting furnace 9 but solidified and clogged in the vicinity of the slag tap 38 exiting the melting furnace 9. In order to prevent this, a method has been proposed in which a portion of the high-temperature combustion gas from the melting furnace 9 is extracted through the slag tap 38 to heat the vicinity of the slag tap 38 to prevent slag solidification trouble.

  That is, using the ejector 41 that uses high-pressure air from the pipe 40 shown in FIG. 3 as the working fluid, the gas is sucked from the slag dropping cylinder 39 via the pipe 51, and the high-temperature combustion from the melting furnace 9 into the slag tap 38 part. This is a method of passing gas. A mixture of the gas sucked through the pipe 51 and the high-pressure air from the pipe 40 is blown into the secondary combustion furnace 24 through the pipe 52. FIG. 4 shows a schematic structure and function in a slag dropping cylinder portion of a melting furnace related to the prior art.

In addition, as a conventional technique for preventing clogging trouble due to condensation of low boiling point compounds such as chlorine, sodium or potassium on the flue portion constituting the melting furnace, for example, a technique as shown in Patent Document 1 is proposed and disclosed. Has been. According to this, the gas volatilized from the surface of the ash layer stays in the circulation area, and by extracting it from the extraction pipe, the exhaust gas discharged through the flue contains only a very small amount of volatilized gas. Blockage is prevented.
Japanese Patent Laid-Open No. 11-99818

However, the conventional technique shown in FIG. 4 has the following problem to be solved. That is, (1) the gas flow sucked through the pipe 51 may cause the slag droplets to shake and collide with the inner wall of the slag dropping cylinder, solidify, or the slag droplets may be sucked into the pipe 51 along the gas flow. . (2) The portion of the slag tap near the suction port of the pipe 51 is heated because the high-temperature combustion gas drifts, but the portion of the slag tap far from the suction port is hardly heated. (3) As the suctioned combustion gas is cooled in the pipe 51, low boiling point substances such as NaCl, CaCl ₂ , chloride, lead, tin, etc. vaporized in the melting furnace condense and solidify, and enter the pipe 51 inlet. There is a risk that it will adhere and grow and block the piping.

In order to solve the above problems, the present invention mainly adopts the following configuration.
A slag tap provided at a lower part of a flue connecting the ash melting furnace and the secondary combustion chamber to flow down the slag from the ash melting furnace, a slag dropping cylinder connected to the slag tap, and below the slag dropping cylinder In an ash melting apparatus equipped with a water tank installed in
Providing a combustion gas extraction part surrounding a lower outer periphery of the slag dropping cylinder, and arranging a lower end of the combustion gas extraction part below the water surface of the water tank;
Forming a gap between the lower end of the slag dropping cylinder and the water surface of the tank,
The combustion gas of the ash melting furnace passes through the slag tack, the slag dropping cylinder, the gap, and the combustion gas extraction unit in this order.

A slag tap provided at a lower part of a flue connecting the ash melting furnace and the secondary combustion chamber to allow the slag from the ash melting furnace to flow down; a slag dropping cylinder connected to the slag tap; and the slag dropping cylinder In an ash melting device provided with a water tank installed below,
Providing a combustion gas extraction part surrounding a lower outer periphery of the slag dropping cylinder, and arranging a lower end of the combustion gas extraction part below the water surface of the water tank;
The lower end of the slag dropping cylinder is disposed below the water surface of the water tank,
A plurality of combustion gas vent holes are provided in the vicinity of the water surface of the slag dropping cylinder,
The combustion gas of the ash melting furnace passes through the slag tack, the slag dropping cylinder, the combustion gas vent hole, and the combustion gas extraction portion in this order.

  According to the present invention, by uniformly sucking the combustion gas from the circumferential portion at the position farthest from the slag tap, there is no bias in the amount of extraction of the combustion gas at the peripheral portion in the slag tap opening, and further from the slag tap. The horizontal shake of the slag droplets can be reduced.

  Further, low boiling point substances such as chlorides can be removed by flowing water down the wall portion of the combustion gas passage.

  Moreover, the removal of chloride and the like improves the reliability of the entire gasification and melting system, leading to a reduction in plant operating costs.

  An ash melting apparatus according to an embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing a configuration example of slag discharge in an ash melting apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing another configuration example of slag discharge in the ash melting apparatus according to the present embodiment. In addition, in embodiment of this invention, the system configuration example shown in FIG. 3 is used for the whole structure of a gasification melting apparatus.

  1 and 2, 11 is a slag discharge device, 31 is a slag, 38 is a slag tap (opening for flowing down the slag from the ash melting furnace 9), 39 is a slag dropping cylinder, and 60 is an even extraction section Part (combustion gas extraction part surrounding the lower outer periphery of the slag dropping cylinder), 61 piping, 62 water injection header, 63 water injection hole, 64 water injection nozzle, 65 gap, 66 gas exhaust hole, 67 water Each represents piping.

  The configuration shown in FIG. 1 is an example in which gas is sucked evenly in the circumferential direction from the vicinity of the water surface of the slag discharge device 11. A uniform extraction section 60 (a member for extracting gas uniformly on the circumference) is provided on the outer periphery of the lower portion of the slag dropping cylinder 39, and a pipe 61 is connected to the uniform extraction section 60. Here, a gap 65 is provided between the lowermost end of the slag dropping cylinder 38 and the water surface of the aquarium, and an equal extraction section 60 is provided on the outer periphery of the lower portion of the slag dropping cylinder, and the lower end of the equal extraction section 60 is provided. A water seal structure is formed under the water surface. Further, a water injection header 62 is provided on the upper part of the uniform extraction section 60, and water can be injected from the water injection header 62 to the inner wall and outer wall of the slag dropping cylinder 39 and the inner wall of the uniform extraction section 60 through a large number of water injection holes 63. ing. The water in the water pipe 67 to the water injection header 62 may be supplied from outside the system, or the water in the water tank may be circulated.

  Further, the pipe 61 in which the water injection nozzle 64 is arranged is connected to be inclined toward the uniform extraction section 60, so that the injection water flows into the water tank of the slag discharge device 11.

  The operation of the configuration example shown in FIG. 1 will be described. When gas is sucked through a pipe 61 using an ejector not shown in FIG. 1 (see the ejector 41 in FIG. 3) or the like, the lowermost circle of the slag dropping cylinder 39 is drawn. From the gap 65 provided in the peripheral portion, the gas is evenly sucked in the circumferential direction, and the gas existing in the slag tap 38 flows downward substantially vertically. As a result, it is possible to eliminate the velocity component that causes the slag droplet to shake in the horizontal direction of the slag dropping cylinder 39 (in contrast to the flow of the slag droplet shown in FIG. 4), and a uniform flow even at the opening of the slag tap 38. Therefore, uniform heating of the slag tap 38 can be realized.

The high-temperature combustion gas sucked from the slag tap 38 is cooled by the lower inner wall of the slag dropping cylinder 39 and the portion of the uniform extraction section 60, and is vaporized in the melting furnace 9 and included in the combustion gas as steam. Chloride, low boiling point metal, etc. condense and grow on the wall. If this wall adhesion is left as it is, the gas passage is blocked, so that water is poured from the water injection header 62 to the lower inner wall and outer wall of the slag dropping cylinder 39 and the inner wall of the uniform extraction section 60 to be removed. Almost all of chlorides, low boiling point metals, etc. contained in the combustion gas as steam are easily soluble in water such as NaCl, KCl, CaCl ₂ and can be easily removed by water injection.

  Some of chlorides, low boiling point metals, etc. in the combustion gas pass through the uniform extraction section 60 and condense and adhere to the inlet portion of the pipe 61, but this is dissolved and removed by water from the water jet nozzle 64. be able to.

  The gas extracted through the pipe 61 is sent to the secondary combustion furnace 24 using the ejector 41 and the like as in the prior art shown in FIG. A blower or the like can be used instead of the ejector 41.

  Next, in another configuration example of the present embodiment shown in FIG. 2, an example in which gas extraction from the lower portion of the slag dropping cylinder 39 is performed through a number of gas vent holes 66 provided in a lower portion of the slag dropping cylinder 39. Show. Here, in the configuration example of FIG. 2, the lowermost end of the slag dropping cylinder 39 is submerged in the water surface, unlike FIG. 1. Also in this configuration example, the extracted gas may be processed in the same manner as in the prior art shown in FIG. The configuration example shown in FIG. 2 differs in the shape of the gas extraction part from the lower part of the slag dropping cylinder 39, but the function is the same as that of the configuration example shown in FIG.

  As described above, in general, fluidized bed waste gasification and melting systems have low heat generation of waste, so there is little room in the temperature of the ash melting furnace, and slag solidification problems with slag taps are likely to occur. In the conventional technology, high temperature combustion gas is sucked from the slag tap and the temperature of the slag tap and slag is maintained. However, in the prior art, the drift of the sucked combustion gas, slag droplet fluctuation due to the gas flow, and chlorination in the extraction pipe Since there was a problem to be improved in terms of reliability, such as adhesion and blockage of objects, in order to solve this problem, the features of the ash melting apparatus according to the embodiment of the present invention are as follows: , Function or action.

  That is, a gap is provided in the lowermost circumferential portion of the slag dropping cylinder, or a number of gas vent holes are provided in the lower portion of the slag dropping cylinder, and gas is sucked from the portion farthest from the slag tap. Further, a gap is provided in the lowermost circumferential portion of the slag dropping cylinder or a large number of gas vent holes are provided in the lower portion of the slag dropping cylinder so that the gas is evenly sucked from the circumferential portion at the portion farthest from the slag tap. Furthermore, a facility for flowing or jetting water is provided on the inner wall and the outer wall of the slag dropping cylinder.

  With such a configuration of the present embodiment, as the gas extraction hole provided in the lower portion of the slag dropping cylinder is further away from the slag tap, the gas velocity component in the vertical direction of the gas flow increases geometrically as the distance increases. Since the gas velocity component in the direction becomes small, the horizontal shake of the slag droplet is reduced. Further, since the gas is extracted from a position equidistant from the peripheral edge of the slag tap, the deviation of the gas extraction amount in the circumferential direction of the slag tap 38 is reduced. Furthermore, since most of the deposits adhering to the wall of the slag dropping cylinder are chlorides that are easily dissolved in water, they can be easily removed with water.

It is a figure which shows the structural example of the slag discharge | emission in the ash melting apparatus which concerns on embodiment of this invention. It is a figure which shows the other structural example of the slag discharge | emission in the ash melting apparatus which concerns on this embodiment. It is a block diagram which shows the whole system | strain of the refuse gasification melting system regarding a prior art. It is a figure which shows the general | schematic structure and function in the slag dropping cylinder part of the melting furnace regarding a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Dust supply hopper 2 ... Fixed quantity feeder 3 ... Boiler 5 ... Supply chute 6 ... Gasification furnace 7 ... Oil injection nozzle 8 ... Fluidized bed 9 ... Melting furnace 10 ... Start-up burner 11 ... Slag discharge device 13 ... Gas quench tower 14 ... Air heater 15 ... Dust collector 16 ... Attracting fan 17 ... Chimney 18 ... Damper 19 ... Blower 4,20,21,23,25,30,32,37,40,44,46,47, 48,51,52 ... Piping 22 ... Exhaust device 24 ... Secondary combustion furnace 26-29 ... Control valve 31 ... Slag 12, 33, 35 ... Flue 34, 36, 49, 50 ... Flow meter 38 ... Slag tap 39 ... Slag dropping cylinder 41 ... Ejector 42 ... Air nozzle 43 ... Fluy 45 ... Metal separator 57 ... O ₂ meter 58 ... CO meter

Claims (6)

A slag tap provided at a lower part of a flue connecting the ash melting furnace and the secondary combustion chamber to flow down the slag from the ash melting furnace, a slag dropping cylinder connected to the slag tap, and below the slag dropping cylinder In an ash melting apparatus equipped with a water tank installed in
Providing a combustion gas extraction part surrounding a lower outer periphery of the slag dropping cylinder, and arranging a lower end of the combustion gas extraction part below the water surface of the water tank;
Forming a gap between the lower end of the slag dropping cylinder and the water surface of the tank,
The combustion gas of the ash melting furnace passes through the slag tack, the slag dropping cylinder, the gap, and the combustion gas extraction unit in this order. In the ash melting apparatus according to claim 1,
A pipe that discharges the combustion gas to the outside is connected to the combustion gas extraction portion at an angle, and a nozzle that ejects water to the inclined pipe is provided.
The ash melting apparatus, wherein the water ejected from the nozzle is caused to flow toward the combustion gas extraction unit. In the ash melting apparatus according to claim 1 or 2,
An ash melting device is provided, wherein a water injection header for allowing water to flow down is provided on the inner wall of the combustion gas extraction portion, the lower inner wall and outer wall of the slag dropping cylinder. A slag tap provided at a lower part of a flue connecting the ash melting furnace and the secondary combustion chamber to flow down the slag from the ash melting furnace, a slag dropping cylinder connected to the slag tap, and below the slag dropping cylinder In an ash melting apparatus equipped with a water tank installed in
Providing a combustion gas extraction part surrounding a lower outer periphery of the slag dropping cylinder, and arranging a lower end of the combustion gas extraction part below the water surface of the water tank;
The lower end of the slag dropping cylinder is disposed below the water surface of the water tank,
A plurality of combustion gas vent holes are provided in the vicinity of the water surface of the slag dropping cylinder,
The combustion gas of the ash melting furnace passes through the slag tack, the slag dropping cylinder, the combustion gas vent hole, and the combustion gas extraction portion in this order. In the ash melting apparatus according to claim 4,
A pipe that discharges the combustion gas to the outside is connected to the combustion gas extraction portion at an angle, and a nozzle that ejects water to the inclined pipe is provided.
The ash melting apparatus, wherein the water ejected from the nozzle is caused to flow toward the combustion gas extraction unit. In the ash melting apparatus according to claim 4 or 5,
An ash melting device is provided, wherein a water injection header for allowing water to flow down is provided on the inner wall of the combustion gas extraction portion, the lower inner wall and the outer wall of the slag dropping cylinder.

Images