JPS6091129A - melting equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 1-11 The present invention relates to a melting device for melting water treatment sludge or ash and dust discharged from an incinerator into slag, and more specifically relates to a melting device for melting water treatment sludge or ash and dust discharged from an incinerator, and more specifically, This invention relates to a melting device equipped with a structure for effectively collecting low-boiling point dust that tends to circulate in a passageway.

In the facility that incinerates municipal waste, a melting furnace is installed after the incinerator to solidify the incineration residue and recovered dust, and after the incineration residue and recovered dust are turned into molten slag. It is widely practiced to cool, solidify, and exhaust. In addition, water treatment sludge and the like are made into molten slag in a direct melting furnace, cooled and solidified, and then discharged.

FIG. 1 shows a flow diagram of a conventional melting apparatus for carrying out the melting process as described above. The waste 1 collected from the fabric is once stored in a storage bit and then incinerated in an incinerator. Incineration residue 2 such as ash or incombustible materials and exhaust gas 3 are discharged from the incinerator. Of these, the incineration residue 2 is introduced into a melting furnace heated to a predetermined temperature, turned into molten slag, and then cooled and solidified to form solid slag 7.
is discharged from the system as On the other hand, the exhaust gas 3 is cooled by passing through an exhaust gas cooling section A (for example, a sprinkler type cooling device), and after dust in the exhaust gas is removed in the dust collection section A, it is discharged to the outside of the system. Further, the dust 4 collected in the dust collecting section A is introduced into the melting furnace, and the incineration residue 2 is
It is also turned into molten slag. Furthermore, the exhaust gas 5 generated when the incineration residue 2 and the collected dust 4 are melted in the melting furnace is introduced into a heat exchanger and cooled, and then is combined with the incinerator exhaust gas 3 through a line 6 to be collected in the dust collection section A. The dust is collected again.

However, 2, K (4, N
It contains components such as aCQ and FeCfL2 that have a boiling point lower than the temperature inside the melting furnace.

These low boiling point dusts are vaporized in the melting furnace and discharged together with the exhaust gas, and cannot be solidified as slag. When such a gaseous low-boiling point component is cooled by a heat exchanger or the like, it solidifies again and becomes dust, which is collected in the dust collecting section A. Therefore, it is reinjected into the melting furnace again. However, since the internal temperature of the melting furnace is higher than the boiling point of such low boiling point components, the low boiling point components will be vaporized again and circulated within the system. In this way, the low-boiling components are kept circulating within the recovery system and are not discharged outside the system. Therefore, during long-term operation of this type of melting equipment, low boiling point dust accumulates in the recovery system.
A problem has arisen in that a considerable amount of the melting furnace exhaust gas 5 adheres to the flow pipes and heat exchangers, leading to blockages or failures.

Therefore, the inventor of the present application proposed a configuration for solving the above-mentioned problems in an earlier application, that is, Japanese Patent Application No. 57-100119, which has not yet been published. Here, a separate dust collection section is provided in the exhaust gas line 6 of the melting furnace, and the low boiling point dust collected in this dust collection section is introduced into a separately designed remelting furnace with a low furnace temperature. A structure is disclosed in which the molten slag is turned into molten slag and discharged outside the system.

However, even with this improved melting device, there were problems such as the relatively complicated structure and the high cost of operating the newly introduced remelting furnace.

Therefore, an object of the present invention is to provide a melting device that can efficiently discharge low-boiling point dust to the outside of the system, has a relatively simple structure, and has low operating costs. There is a particular thing.

In summary, the present invention provides an incinerator for incinerating waste, a melting furnace for melting incineration residue discharged from the incinerator into slag, and a slag discharged from the incinerator and recovered. A first dust supply line for supplying dust to a melting furnace, and an exhaust gas duct branched from a slag discharge port of the melting furnace, and a dust collection section is provided in the exhaust gas duct via an exhaust gas cooling section. In the melting apparatus, a low temperature melting section is provided in the exhaust gas duct upstream of the exhaust gas cooling section, a cooling means is disposed for cooling the slag discharged from the low temperature melting section, and the slag is further collected in the dust collecting section. A second dust supply line for returning the collected dust to the low temperature melting section and a third dust supply line branched from the first dust supply line and connected to the second dust supply line are provided. This is a melting device characterized by:

Other features of the invention will become apparent from the following description of the embodiments.

Figure 2 is a flow explanatory diagram of a melting apparatus according to an embodiment of the present invention. It consists of an incineration treatment portion surrounded by an X, and a melting treatment portion surrounded by a single point @ line Y. In the following description, the symbol A indicates a structure that is also provided in the conventional device shown in FIG. 1, and the symbol @B indicates a device that is provided for the first time in this embodiment.

The waste 11 to be incinerated is stored in the storage bit 12 and then thrown into the incineration F13. The waste 11 is incinerated in the incinerator 13, and the incineration residue 14 and exhaust gas 1 are
5 occurs. The incineration residue 14 is supplied to a melting processing section Y, which will be described later.

On the other hand, the exhaust gas 15 generated in the incinerator 13 is cooled by the exhaust gas cooling section Δ16 and then guided to the exhaust gas processing section 17. The exhaust gas processing section 17 includes an HCfL@collecting section 18 and a dust collecting section A19. , Incinerator 13 in HC Mimi Absorption 18
For example, HC particles generated by combustion of PVC products are absorbed or adsorbed and removed. In addition, H.C.
When absorbing Q, Ca COa , Ca (OH
) 2. Ca 2 O or Na OH etc. are used in a dry method or a wet method. As a result of the setup reaction, CaCA2 or NaC (hereinafter referred to as chloride), etc. are produced.

On the other hand, the dust in the exhaust gas is captured by the dust collection section 19.

The chlorides generated in the HC bulk absorption 18 and the dust captured in the dust collecting section Δ19 are collected and supplied to the melting furnace 22 through the first dust supply line 21. Note that from this first dust supply line 21, another third dust supply line 23 is branched off. Third
The dust supply line 23 is led to a low-temperature melting section 29 of the melting section Y, as will be described later.

The incineration residue 14 and the chlorides and dust in the exhaust gas are thrown into the melt 11F22, and after being turned into molten slag,
The slag is cooled and solidified in the slag cooling section 7 at 25, and is discharged from the system as solidified slag.

By the way, the melting furnace 22 is normally maintained at a relatively high temperature of 1300°C to 1500°C. Therefore, the exhaust gas generated in the melting furnace 22 contains a large amount of vaporized low-boiling component dust as described above.

This vaporized material is cooled and solidified in an exhaust gas cooling section B26 provided in the exhaust gas duct, and then captured in a dust collecting section B27. The low-boiling point dust captured by the dust collector 827 is transferred to the third dust supply line 23 via the second dust supply line 28.
It is thrown into the low-temperature melting section 29 together with the dust from. As is clear from FIG. 2, the low-temperature melting section 29 is located upstream of the exhaust gas cooling section 826. therefore,
i! discharged from the melting furnace 22 is fed to the low temperature melting section 29. F!
! A certain amount of exhaust gas is supplied, and the low boiling point dust is melted by the heat of this exhaust gas. As a result, the low boiling point component becomes molten slag 30 and is discharged from the slag cooling section B31 as solidified slag to the outside of the system.

In the apparatus shown in FIG. 2 described above, the incinerator 13 was placed upstream of the melting furnace 22. However, when the waste to be treated is water treatment sludge, as shown by the imaginary line in FIG.
1 can be processed by suddenly supplying it to the melting furnace 22. In this case, the dust supplied to the low-temperature melting section 29 is only that captured by the dust collecting section B27.

However, some of the slag is discharged from the slag cooling section A25 and is transferred to the slag supply line 49 (shown with imaginary lines).
, the low-temperature melting section 29 together with the dust from the dust collecting section B27
It may be supplied to

Next, the specific structure of the melting apparatus of this embodiment will be explained with reference to FIG. The most important feature of this device is that it has a low-temperature melting section that directly utilizes the sensible heat of the exhaust gas generated in the melting furnace, without constructing a low-humidity melting section that requires a separate heat source as in the previously unknown invention. The goal is to prepare for

Referring to FIG. 3, the melting apparatus of this embodiment has a melting wIA
'P22, low temperature melting section 29, melting furnace slag cooling water tank 25
, a low-temperature melting section slag cooling water 131 (corresponding to the slag cooling section 831 in the previous flow diagram), an exhaust gas cooling section 826, a dust collecting section 827, and the like. A hopper H is attached to the upper part of the melting furnace 22. In this hopper H, wastes such as crushed waste from the storage bit 12, incinerated ash from the incinerator 13, recovered chloride from the HC observation absorption 18, and collected dust from the dust collection section △19 are collected all at once. Injected. As mentioned above, when treating waste such as water treatment sludge, the water treatment sludge is transferred to this hopper H.
and is subjected to melting treatment as described below.

The waste to be treated inputted from the hopper H is melted by flame heat from burners 34, 34 provided approximately in the middle of the upper fireproof wall 33 of the flame chamber 32 of the melting furnace 22. Melting furnace 2
A re-combustion chamber 35 is formed at the bottom of 2. The re-combustion chamber 35 functions as a fall path for the molten slag, and has a plow for re-combusting the incompletely combusted exhaust gas generated in the melting furnace, including exhaust gas <Hz, CO, etc.

The molten slag 36 falls onto the sloped bottom 37 of the reburn chamber 35 . By the way, in this real 8IrA, the inclined bottom part 37
An inclined slag chute 38 is provided to cover the surface of the slag. The inclined slag chute 38 is made of, for example, a stainless steel plate with excellent corrosion resistance and heat resistance. Further, above the inclined slag chute 38, a cooling water supply port 39 is provided on the side wall of the reburning chamber 35.
Cooling water is supplied to the top. Therefore, the reburning chamber 3
The molten slag 36 that has fallen into the slag 5 does not come into direct contact with the slanted bottom 37, but instead falls onto the slag chute 38.

Therefore, damage to the inclined bottom portion 37 due to the heat of the molten slag 36 can be effectively prevented. Also,
Since the impact when the molten slag 36 falls is also alleviated by the inclined slag chute 38, damage to the inclined bottom portion 37 caused by the falling molten slag 36 can be avoided. The molten slag that has flowed down from the inclined slag shoes 1 and 38 together with the cooling water is solidified in the cooling water tank 25 and is discharged to the outside of the yarn by the conveyor 42.

Note that surplus cooling water circulation paths Δa and Ab are provided between the cooling water supply port 39 and the cooling water recovery path 43a,
This is from the cooling water supply port 39 to the inclined slug shoes 1 and 3.
This serves as a circulation path for the supplied cooling water. In this case, part of the cooling water stored in the cooling water tank 25 is used as the cooling water. That is, the water that is circulated as cooling water uses overflow water that has flowed into the surplus cooling water recovery path 43a attached to the upper part of the cooling water tank 25, and the surplus cooling water that has flowed into the recovery path 433 is used as a pump. 44 and sent to the heat exchanger 45 from the cooling water circulation path Aa. After being cooled by the heat exchanger 45, this water passes through the cooling water circulation path Ab to the cooling water supply port 3.
Guided by 9. The cooling water discharged from the cooling water supply port 39 passes through the inclined slag chute 38 to the cooling water tank 2.
5 and overflows into the surplus cooling water recovery path 438 again. In this way, the cooling water is circulated, cold water is always supplied onto the inclined slag chute 38, and the falling molten slag 36 is smoothly swept away toward the cooling water tank 25 and at the same time is cooled. Therefore, the problem of the inclined bottom portion 37 being heated as described above can be effectively solved.

Note that the molten slag 36 is cooled by cooling water on the inclined slag chute 38 to generate steam. However, since the cooling water is constantly flowing on the inclined slag chute 38, it will be understood that the position where steam is generated in the view is the lower portion of the communication passage 46. Further, the cooling water flowing down the inclined slag shoes 1 to 38 forms an inclined water film, that is, a water curtain in the communication passage 46 portion. Therefore, the water vapor generated in the cooling water tank 25 is prevented from rising by this water curtain.

Therefore, there is no fear that steam flowing into the re-combustion chamber 35 will flow, and the temperature within the re-combustion chamber 35 can be kept constant.

On the other hand, a cooling medium such as water continues to be supplied to the heat exchanger 45 from the pipes 3a, 31) in order to cool the cooling water sent from the pump 44. In other words, it is cooled by the pump 52 from the storage tank 51! The cooling medium is heat exchanger 4
5, and after being heat exchanged in the heat exchanger 45,
It is discharged from pipe Bb. The cooling medium, that is, the heated cooling medium, sent out from the pipe line Bb is appropriately supplied to end equipment for utilizing residual heat. This makes it possible to effectively utilize waste heat.

Next, the treatment of dust in the exhaust gas, which is a characteristic feature of this starter, will be explained. The incomplete combustion exhaust gas generated in the melting furnace 22 is transferred to the afterburner 5 provided in the afterburner chamber 35.
Complete combustion is achieved by 3.

Completely combusted exhaust gas is re-burned a! The exhaust gas is introduced into the exhaust gas cooling section B26 via the exhaust gas duct 54 branched from the chamber 35. In the exhaust gas cooling section B26, low boiling point dust vapors in the exhaust gas are solidified by cooling. Therefore, these solidified dusts are collected in the dust collecting section B27, and the purified exhaust gas is discharged to the outside of the system.

On the other hand, the low-temperature melting section 29 is inserted into the exhaust gas duct 54 upstream of the exhaust gas cooling section 826 .

The low-temperature melting section 291 has a silo-shaped insertion tube 55 whose outer surface is covered with a refractory material, and a W# structure in which a pot 56 is suspended below the silo-shaped insertion tube 55. Below the low temperature melting zone 29,
A water seal type low temperature melting section slag cooling water WI31 is provided. The dust collected in the east a section B27 as described above is fed into the low temperature melting section 29 via the second dust supply line 28. By the way, a mixer 58 is provided in the middle of this dust supply line 28. The mixer 58 includes
A third dust supply line 23 branched from the first dust supply line 21 heading from the HCA absorption section 18 and dust collection section A19 of the incineration processing section to the melting furnace 22 is also connected. Further, an introduction line 6o for adding Fe 804 is also connected to the mixer 58. Therefore, these dusts and Fe 804 enter the low temperature melting zone 29.
etc. are configured so that they are input all at once. The mixer 58 is equipped with a configuration that can set the blending ratio of the dust supplied from the dust supply line 28.23 to a predetermined value, thereby making it possible to set the dust blending ratio to a preferable value as described later. can.

Further, when supplying the dust i to the low-temperature melting section 29, it is desirable that each dust is uniformly mixed in the mixer 58. For this purpose, hot water supplied, for example, from the residual heat utilization water pipe Bb described above may be introduced into the mixer 58, and each dust and Fe 804 may be mixed with each other by an arbitrary stirring means. Furthermore, it goes without saying that water may be mixed instead of hot water. As the stirring means, a known mechanical stirring device or air bubbling may be used. Furthermore, if the gas discharged from the dust collector 827 is used to perform air bubbling, the apparatus can be simplified. The reason why the mixer 58 is provided in this way to mix the dust supplied from the third dust supply line 29 from the incineration processing section will be explained in detail later.

Since the dust introduced into the low-temperature melting section 29 is in the form of a paste, it flows down inside the silo-shaped insertion tube 55 . At this time, since the tip of the silo-shaped insertion tube 55 is inserted into the exhaust gas duct 54, it is heated by the high temperature exhaust gas flowing inside the exhaust gas duct 54, and the temperature is gradually increased. By the way, the temperature of the exhaust gas flowing in the exhaust gas duct 54 is lower than the temperature in the melting furnace 22 and the afterburning chamber 35, and does not have enough humidity to vaporize the ms point dust. Therefore, the low boiling point dust is reliably melted in the low temperature melting section 29, accumulates in the pot 56, overflows from the edge of the pot 56, and falls into the cooling water 1131. The molten slag is cooled and solidified in the cooling water tank 31 and discharged to the outside by the conveyor 61.

In the above-mentioned melting apparatus, the temperature inside the melting furnace 22 is raised to about 1350° C. in order to convert high-boiling point dust such as incineration ash into molten slag. However, the temperature of the exhaust gas that has reached the low-temperature melting section 29 from the melting furnace 22 through the re-combustion chamber 35 and the exhaust gas duct 54 is between 1000°C and 120°C.
The temperature is about 0°C.

Therefore, the temperature of the dust inside the insertion tube 55 heated by the exhaust gas is raised to only 900° C. to 950° C. at most, and the low boiling point dust inside the insertion tube 55 is only melted and not vaporized. Therefore, the boiling point dust turns into molten slag and falls into the cooling water tank 31.

The melting device of this embodiment selectively extracts low-boiling point dust and melts it into slag at a temperature above the melting point and below the boiling point, and is designed to use the heat retained in the exhaust gas as a heat source, and to use a third The feature is that the dust from the dust supply line is also introduced into the low temperature melting section. Therefore, it can be seen that low boiling point dust can be economically converted into slag.

Next, mixing of the dust supplied from the dust supply line 28 which is connected to the above-mentioned agitator 58 and the dust supplied from the dust supply line 23 will be explained. First, it should be pointed out that the mixer 58 is not an essential component of the present invention. That is, the structure may be such that the mixer 58 is removed. It will be understood that even in this case, the low boiling point dust is turned into molten slag due to the retained heat of the exhaust gas flowing in the exhaust gas duct 54, and therefore the low boiling point dust can be reliably discharged from the system. However, preferably, the mixer 58 is provided as described above, and the mist supply line 23 from the incineration processing section and the Fe SOz introduction line 60 are connected to the low temperature melting section 29 as mixed dust.
supplied to The reason for this will be explained in detail based on the following experimental examples.

FIG. 4 is a graph showing changes in the melting point of mixed dust when the mixing ratio of the dust supplied from the second dust supply line 28 and the dust supplied from the third dust supply line 23 is changed. It is.

As is clear from FIG. 4, the second dust supply line 2
Dust supply line 23 of dust countermeasure 3 supplied from 8
It will be understood that when the blending ratio of the dust supplied from the above exceeds 12, the melting point of the mixed dust exceeds 900°C. Therefore, if this mixing ratio is exceeded, low-boiling point dust such as chloride will be vaporized and it will no longer be possible to form molten slag. Therefore, the mixing ratio of the dust supplied from the second dust supply line 28 and the dust supplied from the third dust supply line 23 is 1:2.
The following is required. Preferably, this ratio is 1:0.9 or less. This is because the melting point of the mixed dust can be lowered to 800° C. or lower, and the vaporization of low-boiling point dust can be reliably prevented.

Incidentally, the fundamental reason for processing the mixed dust is to prevent heavy metals such as Cd and Pb from leaching out from the slag that has been cooled and solidified in the low-temperature melting section 29 and the slag cooling water tank 31. That is, only the low-boiling point dust collected in the dust collecting section B27 is transferred to the second dust supply line 2.
In the slag obtained by inputting it into the low temperature melting section 29 from 8,
It has been experimentally confirmed that heavy metals such as Cd and Pb can be eluted. In order to prevent this, the dust from the third dust supply line 23 is mixed in the mixer 58 as described above. When experiments were repeated under various conditions using the melting apparatus of this example, the following results were obtained. Table 1 shows the results regarding heavy metal elution from the obtained slag.

Table 1*: Mixing ratio means the ratio of dust from the second dust supply line to dust from the third dust supply line.

*: The unit of melting temperature is °C, and the unit of heavy metal elution amount is mQ/view.

As is clear from Table 1, the second dust supply line 2
The blending ratio of the molten dust supplied from 8 and the incinerated dust supplied from the third dust supply line 23 is 1.
It will be understood that the elution amount of pb and Cd can be kept low under the conditions of :0.7 to 1:0.9. However, if you just want to ignore CD and suppress the elution amount of PB to 3.0 PPM or less, this blending ratio should be 1:0.5~
It will be appreciated that the range may be 1:0.9.

Conversely, pb can be ignored and the elution amount of cd can be set to 0.
If it is only required to keep it below 3PPM,
This mixing ratio is 1:0. - It will be understood that 6 or more is sufficient. As is clear from the results in Table 1 above, by mixing the dust from the incineration section from the third dust supply line 23 in the mixer 58, the dust formed in the low temperature melting zone 29 and the slag cooling water tank 31 is Elution of heavy metals from slag can be effectively prevented.

Next, the advantage of connecting the Fe5Oq introduction line 60 to the mixer 58 will be explained. Table 2 shows the experimental results when FeSO4 was mixed.

Table 2*: Compounding ratio is the amount of dust from the second dust supply line and the amount of dust from the third dust supply line: The unit of Fe So 4 additive is weight %, and the unit of heavy metal elution port is mQ/ It is Q.

As is clear from Table 2, when 1% FeSO4 is added, cd and pb
It will be understood that the amount of elution can be more effectively reduced. Also, if Fe 804 is added, the stirrer 5
It has also been confirmed that the mixed dust kneaded in 8 can be made more uniform, so that the mixed dust with a stable composition can be obtained, and the amount of heavy metals eluted from the slag can be reliably kept below a certain value.

Effects of the Invention This invention provides a low-temperature melting section upstream of the exhaust gas cooling section of the exhaust gas duct, a cooling means for cooling the slag discharged from the low-temperature melting section, and furthermore, a dust collecting section that collects the slag. a second dust supply line for returning dust to the low-temperature melting section; and a third dust supply line branched from the first dust supply line for supplying dust from the incinerator to the melting furnace and connected to the second dust supply line. Because the structure has a dust supply line, it is possible to economically convert low-boiling point dust into slag, and since dust does not accumulate in the system, there is no possibility of blockages in ducts or dust collectors. This makes it possible to reliably prevent such accidents.

[Brief explanation of the drawing]

FIG. 1 is a flow diagram of a conventional waste melter system. FIG. 2 is a flow diagram of a system incorporating a melting device according to an embodiment of the present invention. FIG. 3 is a schematic sectional view showing the specific structure of the melting device shown in FIG. 2. FIG. Figure 4 shows the blending ratio of the dust supplied to the low temperature melting section from the second dust supply line and the dust supplied to the low temperature melting section from the third dust supply line, and the ratio of dust supplied to the low temperature melting section from the second dust supply line. It is a figure showing the relationship with the melting point of dust. 13... Incinerator, 21... First dust supply line, 22... Melting furnace, 23... Third dust supply line, 26... Exhaust guy cooling section, 27... Collection dust section, 28
... second dust supply line, 29 ... low temperature melting section, 31 ... cooling water tank as cooling means, 54 ... exhaust gas duct. (Ha power x 2 people)

Claims (1)

[Claims] An incinerator for incinerating waste; a melting furnace for melting incineration residue discharged from the incinerator into slag;
a first dust supply line for supplying dust discharged and recovered from the incinerator to the melting furnace;
A melting apparatus comprising an exhaust gas duct branched from a slag discharge port of the melting furnace, and a ts abdomen is provided in the exhaust gas duct via an exhaust gas cooling section, wherein the exhaust gas duct is provided with a low-temperature part upstream of the exhaust gas cooling section. a second melting section, a cooling means for cooling the slag discharged from the low-temperature melting section, and a second cooling means for returning the dust collected in the dust collecting section to the low-temperature melting section; A melting device comprising a dust supply line and a third dust supply line branched from the first dust supply line and connected to the second dust supply line.