JP2007120842A - Method and its device for treating ash melting furnace granulation water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for treating granulation water without enlarging waste water treatment equipment since waste water treatment equipment is not used, without raising salt concentration of recycled water since the granulation water is not recycled, and without lowering combustion energy. <P>SOLUTION: The granulation water being slag cooling water is treated by carrying out particle size separation via a sedimentation tank, and spraying it on a temperature reducing tower or a melting temperature reducing tower of an incinerator to evaporate it. By carrying out particle size separation and removal of particles with a particle diameter of 0.01mm or more in the sedimentation tank, blocking of a nozzle carrying out spraying to the temperature reducing tower is prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for treating granulated water for cooling slag after ash produced when incineration of trash and the like is performed in an ash melting facility.

2. Description of the Related Art Ash melting equipment that melts incineration ash generated when incineration of trash and the like into slag has been widely used for the purpose of reducing incineration ash volume and resources. In the ash melting facility, the incinerated ash is melted at a high temperature of 1200 ° C. or higher and then rapidly cooled with water to obtain a vitreous solidified product mainly composed of SiO ₂ , CaO and Al ₂ O ₃ called granulated slag. It is done. In addition, dioxins contained in the ash are pyrolyzed during melting at the ash melting facility, and most of the heavy metals in the incinerated ash are volatilized and removed by high temperatures, but the remaining traces of heavy metals are contained in the glassy slag. Granulated slag is a safe substance and can be recycled as roadbed materials, concrete aggregates, asphalt mixing aggregates, and the like.

  In order to obtain the granulated slag, a process of quenching the slag in which the incinerated ash is melted with water is necessary, and the water for quenching is called granulated water. Since the granulated water contains molten fly ash and salts from the molten exhaust gas, the salt concentration of the granulated water is high and the metal piping is easily corroded, so that it is difficult to use as recycled water. For this reason, granulated water was treated by drainage and discharged.

  However, in recent years, there has been a demand for non-discharge of wastewater for environmental protection around the waste incineration facility, and it has been forced to use it in the field as reused water after being treated in the incineration facility. For this reason, the salt concentration of reused water has increased, and there has been a problem that equipment costs increase due to the use of high-grade materials in order to prevent equipment corrosion and equipment corrosion. Moreover, since it is necessary to perform a waste water treatment with a waste water treatment apparatus, there also existed a problem that a waste water treatment apparatus enlarged.

Therefore, the method of spraying and evaporating crushed water to an incinerator has been conventionally performed. Further, Patent Document 1 discloses a method in which pulverized water is sprayed to a secondary combustion chamber that completely burns molten exhaust gas from an ash melting furnace.
JP 2005-95749 A

  However, the method of spraying and evaporating the granulated water to the incinerator has a problem that the combustion energy of the incinerator is lowered by blowing the granulated water into the combustion furnace. The method disclosed in Patent Document 1 also has a problem in that the combustion energy in the secondary combustion chamber is lowered.

  Accordingly, in view of the problems of the prior art, the present invention does not require the use of a waste water treatment device, so that it is not necessary to increase the size of the waste water treatment device, and the salt concentration of reused water is increased in order not to reuse the granulated water. It is another object of the present invention to provide a method for treating granulated water without reducing combustion energy.

In order to solve the above problems, the present invention is directed to the granulated water after cooling the slag discharged from the ash melting furnace to the slag settling tank to separate the slag particles having a predetermined particle size or more, and the particle size separation is performed. It is characterized by spraying the later granulated water to a temperature reducing tower provided in the exhaust gas path of the incinerator or melting furnace and evaporating it.
The slag particle size separation in the slag sedimentation tank may be performed using a hydrocyclone or filtration, but preferably a sedimentation process is performed, and particles having a particle diameter of 0.01 mm or more are separated by particle size separation and removed by the sedimentation process. Is good.
And the apparatus suitably used in the present invention includes a precipitation tank for precipitating slag in the granulated water after cooling the slag discharged from the ash melting furnace, a temperature reducing tower provided in the exhaust gas path of the incinerator or melting furnace, The slag particles having a predetermined particle size or more are separated in the sedimentation tank by a particle size separation, and the granulated water introduced after the particle size separation is led to the temperature-decreasing tower, and the temperature reduction is performed via the line. It is characterized by comprising means for spraying on the tower.
Also in this apparatus, the slag settling tank is a settling tank that performs slag particle size separation by settling treatment, and the granulated water guided from the settling tank to the granulated water introduction line has a particle diameter of substantially 0.01 mm or more. It is preferable that the crushed water contains only slag particles, and the amount of the crushed water injected into the slag sedimentation tank is A (t / h), and the tank intersects the flow of the granulated water in the precipitation tank. When the width is X (m), it is preferable to use a sedimentation tank whose tank length in the flow direction of the granulated water is Y (m) or more.

According to the present invention, since the crushed water is sprayed and processed on the temperature reducing tower, the waste water treatment device is not used, it is not necessary to increase the size, and the salt concentration of the waste water does not increase. Further, since the water is sprayed onto the temperature reducing tower, which is a process for lowering the temperature by spraying water on the exhaust gas after the boiler exit from which the waste heat has been recovered, it is efficient without reducing the amount of power generation.
Therefore, according to the present invention, since the waste water treatment device is not used, it is not necessary to increase the size of the waste water treatment device, the reused water is not reused, the salt concentration of reused water does not increase, and the combustion energy is reduced. A method for treating crushed water can be provided without reducing the recovery rate.
Further, when the present invention is put into practical use, it is necessary to use a spray nozzle with a fine nozzle diameter when spraying, because it is sprayed to a temperature-decreasing tower having a temperature lower than that of a combustion furnace to treat the crushed water. As a result, there is a problem that particles of slag fragments (hereinafter referred to as “SS of slag”) contained in the granulated water clog the spray nozzle. Therefore, particles having a particle diameter of 0.01 mm or more are separated and removed. By doing so, it is possible to treat the granulated water without blocking the nozzle. For particle size separation, it is possible to operate the particle size separation device stably without being affected by fluctuations in the amount of granulated water treatment. Is the best.
And by using the settling tank which calculated | required the optimal tank length of the flow direction of granulated water from the injection amount of the granulated water to the settling tank, and the tank width of the direction crossing the flow of the granulated water of the settling tank The particles having a particle diameter of 0.01 mm or more can be separated and removed most efficiently.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

FIG. 1 is a flow diagram using the treatment method of the present invention in which crushed water is sprayed onto a temperature reducing tower. Garbage and the like are incinerated in the incinerator 1, main ash generated during incineration is sent to the ash melting furnace 5, and exhaust gas is sent to the boiler 2. The exhaust gas sent to the boiler 2 is cooled by the boiler 2, further cooled by spraying water in the temperature reducing tower 3, and sent to the bag filter 4. The bag filter 4 is sent to the ash melting furnace 5 as fly ash from which HCl, SO _{x and the} like are adsorbed and removed by the dust contained in the exhaust gas and the reactive chemicals blown in. The main ash and fly ash sent to the ash melting furnace 5 are melted in the ash melting furnace 5 at a slag temperature of about 1400 to 1700 ° C. (preferably 1550 to 1650 ° C.). The molten slag obtained by melting leaves the ash melting furnace 5 and falls into the granulation tank 7. For example, in order to prevent a steam explosion associated with contact with the granulated water in the granulating tank 7, the molten slag is rapidly cooled by spraying the granulated water while dropping into the granulated water tank 7, It is collected in the granulation tank 7 as slag. The granulated water sprayed to the molten slag falls into the granulated tank 7 together with the molten slag.

  The crushed water flowing out from the crushed water tank 7 is received in the crushed water hot water tank 8 and temporarily stored, then sent from the crushed water pump 9, cooled through the crushed water heat exchanger 17, and then rapidly cooled again. It is circulated and used as crushed water. When the granulated water is circulated, molten fly ash and salt from the molten exhaust gas are mixed, so the salt concentration of the granulated water is concentrated to a high level. Is extracted to the slag settling tank 11 by the granulated water drainage pump 10. The extracted crushed water is subjected to particle size separation in the slag settling tank 11, particles having a particle diameter of 0.01 mm or more are transferred to the slag pit 12, and the granulated water from which particles having a particle diameter of 0.01 mm or more are removed is the weir 18. Further, the water is sprayed to the temperature reducing tower 3 through the crushed water dewarmed water tank 13, the crushed water dewarmed water pump 14, the dewarmed water tank 15, and the dewarmed water pump 16, and is evaporated.

Since the present invention treats the crushed water by spraying to a temperature-decreasing tower having a temperature lower than that of the combustion furnace, it is necessary to use a spray nozzle having a fine nozzle diameter when spraying. A nozzle with an aperture of 0.4 mm was used. However, when a fine spray nozzle is used, there is a problem that the SS of the slag contained in the granulated water clogs the spray nozzle. Therefore, large particles were removed in the slag settling tank 11.
FIG. 4 is a graph of the particle size distribution of the sludge in the slag settling tank 11. The vertical axis represents the relative particle amount (%), and the horizontal axis represents the particle diameter (μm). From the graph, it can be seen that 10 μm (= 0.01 mm) particles are about 90%. FIG. 5 is an electron micrograph of sludge in the slag settling tank 11. The arrow in the figure represents 10 μm (= 0.01 mm). From FIG. 4 and FIG. 5, the particles to be removed were particles having a particle diameter of 0.01 mm or more.

The size of the sedimentation tank necessary for removing particles of 0.01 mm or more was set based on the following grounds.
FIG. 6 is a graph showing the relationship between the sedimentation rate and particle size of particles having a specific gravity of 2.8. The vertical axis represents the sedimentation rate (mm / min), and the horizontal axis represents the particle size (mm). From the graph, it can be seen that the sedimentation rate of particles having a particle size of 0.01 mm is 3.3 mm / min (= 0.0034 m / min).
Therefore, when the amount of granulated water injected into the slag sedimentation tank 11 is A (t / h) and the tank width in the direction intersecting the flow of the granulated water in the sedimentation tank is X (m), A sedimentation tank having a tank length in the flow direction of Y (m) or more is required. Here, considering the relationship between A, X, and Y, the water head flowing out from the settling tank is about 0.05 m.
Y = (A / 60) × (1 / 0.05X) × (0.05 / 0.0033)
It is.

  FIG. 2 is a flow diagram using the treatment method of the present invention in which crushed water is sprayed onto a melting and decooling tower. The flow and configuration were the same as in Example 1 except that the portion to be evaporated by spraying water with crushed water was used as a melting and cooling tower.

  The exhaust gas generated when ash is melted in the ash melting furnace 5 is sent to the secondary combustion chamber 6 and completely burned. The exhaust gas generated in the secondary combustion chamber 6 is cooled by being sent to the melting temperature reducing tower 21 and sprayed with water, and is processed through the melting bag filter 22. Further, the granulated water to be disposed sent to the slag settling tank 11 is subjected to particle size separation in the slag settling tank 11. Particles having a particle diameter of 0.01 mm or more are supplied to the slag pit 12, and granulated water from which particles having a particle diameter of 0.01 mm or more have been removed is the granulated water dewarmed water tank 13, granulated water dewarmed water The water is sprayed to the melting and temperature reducing tower 21 through the pump 14, the temperature-reducing water tank 15, and the temperature-reducing water pump 16, and is evaporated.

  In addition, since the temperature of the melting and cooling tower is lower than that of the incinerator as in the first embodiment, it is necessary to use a spray nozzle having a fine nozzle diameter in order to spray the melting and cooling tower. Therefore, since there is a problem of blockage of the spray nozzle as in Example 1, the particle diameter (0.01 mm or more) removed by the spray nozzle, the slag precipitation tank 11 and the slag precipitation tank 11 is the same as in Example 1.

(Comparative Example 1)
The crushed water was treated by a conventional method in which the crushed water was treated with a wastewater treatment device and used as reused water.

(Comparative Example 2)
FIG. 3 is a flow diagram using a conventional processing method in which crushed water is sprayed onto an incinerator. The flow was the same as in Examples 1 and 2 except that the portion to be subjected to the evaporation treatment by spraying the crushed water was an incinerator and the temperature-reducing water tank 15 and the temperature-reducing water pump 16 were not provided.

  Further, the crushed water to be disposed sent to the slag settling tank 11 is sprayed from the weir 18 to the incinerator 1 through the crushed water dewarmed water tank 13 and the crushed water dewarmed water pump 14 and evaporated. The particle size to be removed in the slag settling tank 11 was not particularly determined. The slag settling tank 11 may have any size as long as it can process the crushed water charged into the slag settling tank 11.

[Wastewater treatment equipment]
In Example 1, Example 2, and Comparative Example 2, the waste water treatment apparatus was unnecessary, but in Comparative Example 1, the waste water treatment apparatus was necessary, and the waste water treatment apparatus was required to be enlarged.
FIG. 7 shows the water balance when Example 1, Example 2 and Comparative Example 2, that is, a waste water treatment device is not required, and FIG. 8 shows the water balance when Comparative Example 1, ie, the waste water treatment device is required. is there. As can be seen from FIGS. 7 and 8, in Example 1, Example 2 and Comparative Example 2, the wastewater treatment amount was 80 t / day, but in Comparative Example 1, it was 130 t / day, and the wastewater treatment apparatus was enlarged. Was necessary.

[Reuse water salt concentration]
In Comparative Example 1, since the crushed water having a high salt concentration is recycled as reused water, the salt concentration of the crushed water and the reused water is high. In Examples 1, 2 and 2, the salt concentration is high. Since high crushed water is not reused, the salt concentration of crushed water and reused water is lower than that of Comparative Example 1, so the possibility of equipment corrosion is low, and high-grade materials are used to prevent equipment corrosion. There is no need to use.
FIG. 9 shows measured values obtained by measuring the salt concentration of the crushed water and reused water during the execution of Comparative Example 1 over about 7 months. The vertical axis represents the chlorine (Cl) concentration (mg / l), and the horizontal axis represents the measurement date. From FIG. 9, it can be seen that the chlorine (Cl) concentration of the granulated water is 5000 to 7000 mg / l, and the reused water is 3000 to 4200 mg / l. The chlorine concentration of the crushed water and reused water in Example 1, Example 2 and Comparative Example 2 is 5,000 to 5000 mg / l of crushed water chlorine concentration and 1000 to 2200 mg / l of reused water chlorine concentration. Declined.

[Combustion energy]
In Comparative Example 2, the problem of a reduction in combustion energy of the combustion furnace occurred because of the spraying of granulated water to the combustion furnace and evaporation. However, in Example 1 and Example 2, since it processed by spraying to the temperature-reduction tower which is the process of reducing temperature, the problem of the reduction of combustion energy did not generate | occur | produce. Moreover, since the comparative example 1 does not perform an evaporation process, the problem of a combustion energy fall did not generate | occur | produce.

  Table 1 summarizes the results for each task of Example 1, Example 2, Comparative Example 1 and Comparative Example 2. Both Example 1 and Example 2 have solved all the problems in Comparative Example 1 and Comparative Example 2.

  According to the present invention, since the waste water treatment device is not used, it is not necessary to increase the size of the waste water treatment device, and the salt concentration of the reused water does not increase because the ground water is not reused. It is possible to provide a method for treating granulated water without lowering.

It is a flowchart using the processing method of this invention which sprayed the granulated water to the temperature-reduction tower. It is a flow figure using the processing method of the present invention which sprayed granulated water on the melting temperature-decreasing tower. It is a flowchart using the conventional processing method which sprayed the granulated water to the incinerator. It is a graph of the particle size distribution of the sludge of the slag sedimentation tank. 3 is an electron micrograph of sludge in a slag settling tank 11. It is a graph of the relationship between the sedimentation rate and particle size of particles having a specific gravity of 2.8. It is a water balance when a waste water treatment apparatus is unnecessary. This is the water balance when a wastewater treatment device is required. Measures the salt concentration of crushed water and reused water over about 7 months when the crushed water is treated with wastewater treatment equipment and used as reused water. Measured value.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Incinerator 2 Boiler 3 Temperature reduction tower 4 Bag filter 5 Ash melting furnace 6 Secondary combustion chamber 7 Granulated water tank 8 Granulated water hot water tank 9 Granulated water pump 10 Granulated water drainage pump 11 Slag sedimentation tank 12 Slag pit 13 Water Crushed water dewarmed water tank 14 Crushed water dewarmed water pump 15 Dewarmed water tank 16 Dewarmed water pump

Claims (6)

  The crushed water after cooling the slag discharged from the ash melting furnace is guided to a slag settling tank to separate slag particles of a predetermined particle size or more, and the crushed water after the particle size separation is separated into an incinerator or A method for treating granulated water, characterized by spraying and evaporating a temperature reducing tower provided in an exhaust gas path of a melting furnace.   The method for treating granulated water according to claim 1, wherein the slag particle size separation in the slag sedimentation tank is a sedimentation treatment, and particles having a particle diameter of 0.01 mm or more are separated by particle size separation and removed by the sedimentation treatment. . The flow rate of the granulated water when the amount of the granulated water injected into the slag sedimentation tank is A (t / h) and the tank width in the direction intersecting the flow of the granulated water in the sedimentation tank is X (m) The processing method of the granulated water of Claim 1 or 2 using the sedimentation tank whose tank length is more than Y (m).
Y: Value calculated by the following equation Y = (A / 60) × (1 / 0.05X) × (0.05 / 0.0033)   A settling tank for precipitating slag in the granulated water after cooling the slag discharged from the ash melting furnace, a temperature reducing tower provided in the exhaust gas path of the incinerator or melting furnace, and a set particle size or more in the settling tank The slag particles are separated by particle size, and the granulated water after the particle size separation is composed of a granulated water introduction line that leads to the temperature-decreasing tower, and means for spraying the temperature-decreasing tower via the line. An apparatus for treating granulated water.   The slag settling tank is a settling tank that performs slag particle size separation by settling treatment, and the granulated water guided from the settling tank to the granulated water introduction line contains only slag particles having a particle diameter of substantially 0.01 mm or more. The apparatus for treating granulated water according to claim 4, wherein the apparatus comprises granulated water. When the slag settling tank has an injection amount of granulated water into the settling tank of A (t / h) and the tank width in the direction crossing the flow of the granulated water of the settling tank is X (m), 6. The apparatus for treating granulated water according to claim 5, wherein the tank length in the water flow direction is a precipitation tank having a length of Y (m) or more.
Y: Value calculated by the following equation Y = (A / 60) × (1 / 0.05X) × (0.05 / 0.0033)

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