JP2005270901A - Method and equipment for treating molten fly ash - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and equipment for treating molten fly ash capable of highly maintaining the removal efficiency of dioxins and enhancing the operation efficiency with respect to the treatment of dioxins. <P>SOLUTION: The equipment for treating molten fly ash is provided with a heater 2 for heating molten fly ash, a crusher 3 for crushing molten fly ash heated by the heater after cooling and a discrimination mechanism 4 for discriminating the molten property of the molten fly ash from the crushing state of the molten fly ash by means of the crusher 3. In addition, a sorter 5 for sorting into easily fusible molten fly ash and hardly fusible molten fly ash based on the discrimination result of the discrimination mechanism 4 is disposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a molten fly ash treatment method and apparatus for performing a decomposition step of treating molten fly ash and decomposing and removing dioxins contained in the molten fly ash.

Conventionally, incinerated fly ash and molten fly ash are known to contain several ppb of dioxins. Such dioxins are highly toxic and are removed from molten fly ash as harmful to the environment. It is hoped that.
However, it is known that dioxins are not easily decomposed, and various treatment methods are being studied.

  As such a treatment method, a heat treatment that decomposes dioxins by heating to high temperature, and a chemical treatment that removes dioxins by adding a decomposition agent that decomposes dioxins (see Patent Document 1) are known. A technique for treating incineration fly ash or molten fly ash by any method has been put into practical use.

JP 2002-45820 A

  In the case where fly ash is heat-treated, dioxins can be decomposed and removed by 99.5% or more because they are treated at a high temperature of 400 ° C. to 500 ° C., but the energy cost for heating increases. Further, depending on the properties of the fly ash, the fly ash itself may be melted, and the fly ash may be cooled and adhered and solidified in the transport path, thereby blocking the transport path. For this reason, there is a problem in operation efficiency such that maintenance and inspection must be performed more than necessary, and treatment at a low temperature at which fly ash does not melt is desired.

  Therefore, the chemical treatment is applied, but the chemical treatment has an advantage that dioxins can be removed even at a low temperature of 100 ° C. to 150 ° C., but the removal rate of the dioxins is the treatment of incineration fly ash. It is known that it is only about 85% even when performing the above.

  For this reason, it has been difficult to achieve both improvement in the removal efficiency of dioxins and improvement in operation efficiency for the treatment of dioxins.

  Accordingly, an object of the present invention is to maintain high removal efficiency of dioxins and to improve the operation efficiency related to the treatment of dioxins.

  For the above purpose, the characteristic means of the molten fly ash treatment method of the present invention is a molten fly ash treatment method in which a molten fly ash is treated and a decomposition step of decomposing and removing dioxins contained in the molten fly ash is performed. In addition, prior to the decomposition step, a meltability confirmation step for determining the meltability of the molten fly ash is performed, and a separation step for separating the melted fly ash that is easy to melt and the melted fly ash that is difficult to melt is performed. .

  That is, the melting temperature of the molten fly ash can be known by performing the meltability confirmation step. Although it is not necessary to know the melting temperature strictly, it is possible to know whether it is easy to melt or difficult to melt by knowing at least a rough melting temperature. Thereby, when the decomposition process which decomposes | disassembles and removes dioxins is performed by heat-processing the said molten fly ash, it can be estimated whether the decomposition process is performed favorably. If a separation process is performed based on this prediction, a decomposition process suitable for each separated molten fly ash can be performed.

  Moreover, the second characteristic means of the molten fly ash treatment method of the present invention is a decomposition in which the molten fly ash determined to be easily melted is subjected to chemical treatment for removing dioxins by adding a decomposition agent for decomposing dioxins. The molten fly ash, which has been subjected to a process and determined to be difficult to melt, is subjected to a decomposition process in which dioxins are decomposed and removed by heat treatment.

  Therefore, chemical treatment and heat treatment can be properly used as the decomposition treatment process according to the meltability of the molten fly ash, so that the high decomposition and removal efficiency of dioxins by heat treatment is achieved as much as possible. When a decrease in operation efficiency due to maintenance inspection or the like is predicted, the operation efficiency can be increased by chemical treatment.

  The characteristic configuration of the molten fly ash treatment apparatus of the present invention includes a heating device that heats the molten fly ash, a crushing device that crushes the molten fly ash heated by the heating device, and then crushes the molten fly ash by the crushing device. A discriminating mechanism for discriminating the meltability of the molten fly ash from the crushing situation, and a separation device for separating the melted fly ash that is easily meltable and the melted fly ash that is difficult to melt based on the discrimination result of the discriminating mechanism It is in.

  That is, when the molten fly ash is heated by the heating device, the molten fly ash becomes a heating state according to the heating condition of the heating device. At this time, for example, when the molten fly ash is heated to a temperature close to the heat treatment temperature of dioxins, when the molten fly ash is easily melted at the heat treatment temperature, melting of the molten fly ash is observed. However, when it is difficult to melt, the particle shape of the molten fly ash by heating does not change.

When the melted fly ash is melted by the heating device, the melted fly ash is provided to the crushing device because the molten fly ash has a large particle size when cooled and solidified and integrated before crushing by the crushing device. The load of the molten fly ash crushing process in the crushing device increases.
On the other hand, when the molten fly ash is not melted and the particle shape is not changed, the particle size of the molten fly ash is not increased even when crushing by the crushing device. When ash is provided, the load of the molten fly ash crushing process in the crushing device remains small. Moreover, not only the crushing load but also the crushing conditions such as the properties of the molten fly ash to be crushed vary greatly depending on the meltability of the molten fly ash.

  Therefore, the meltability of the molten fly ash can be determined by the discriminating mechanism from the crushing situation such as the molten fly ash crushing load by the crushing device, and the sorting device sorts the molten fly ash according to the meltability. . By subjecting the separated molten fly ash to a decomposition process according to its meltability, it is possible to achieve as high a decomposition and removal efficiency of dioxins as possible by heat treatment. Even when a decrease in the operation efficiency due to is predicted, the operation efficiency can be increased by chemical treatment.

  A characteristic configuration as a different form of the molten fly ash treatment apparatus of the present invention includes a heating apparatus that heats the molten fly ash, an image processing apparatus that observes a melting state of the molten fly ash heated by the heating apparatus, and the image A discriminating mechanism that discriminates the meltability of the molten fly ash from the melting status of the molten fly ash by the processing device is provided, and based on the discrimination result of the discriminating mechanism, the molten fly ash that is easy to melt and the molten fly ash that is difficult to melt are separated And a separation device for performing the above.

  According to the previous molten fly ash treatment device, the meltability of the molten fly ash was determined by the crushing device, but the melting state of the molten fly ash was image-processed, and the fluidity etc. The meltability can be determined. When the molten fly ash is separated according to the meltability by the sorting device, it is easy to achieve both high decomposition efficiency of dioxins and high operating efficiency, as before.

  In addition, the characteristic configuration of the molten fly ash treatment apparatus of the present invention is that it is provided with a chemical treatment apparatus that removes dioxins from easily melted molten fly ash by adding a decomposition agent that decomposes dioxins, and is difficult to melt. You may provide the thermal decomposition apparatus which heats molten fly ash and decomposes | disassembles dioxins.

  In other words, each of the separated molten fly ash can be subjected to a decomposition process according to its meltability to achieve as high a decomposition and removal efficiency of dioxins as possible by heat treatment. Even when a decrease in operation efficiency due to inspection or the like is predicted, the operation efficiency can be increased by chemical treatment.

  Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the molten fly ash treatment apparatus of the present invention uses molten fly ash generated in a fly ash melting furnace provided in an incineration facility or the like as a processing object, As a basic configuration, a storage tank 1 for storing molten fly ash as an object to be processed is provided, and the heating apparatus 2 that heats the molten fly ash from the storage tank 1 and the heating apparatus A crushing device 3 that crushes the heated molten fly ash after cooling, and a discriminating mechanism 4 that discriminates the meltability of the molten fly ash from the crushing state of the molten fly ash by the crushing device are provided. Based on this, there is provided a separation device 5 for separating molten fly ash that is easy to melt and molten fly ash that is difficult to melt. In addition, it is equipped with a chemical treatment device 6 that adds a decomposing agent that decomposes dioxins and removes dioxins from easily melted molten fly ash, and heat decomposes by heating molten fly ash that is difficult to melt to decompose dioxins. A device 7 is provided.

  The storage tank 1 extracts a quantity of molten fly ash and transfers it to the heating device 2. In the heating device 2, the molten fly ash is heated to 400 ° C. and conveyed to the crushing device 3. The molten fly ash transported to the crushing device 3 is cooled in the transport process and is in a lump shape. In the crushing device 3, the massive molten fly ash is crushed into granules.

  Here, the melted fly ash cooled in the transporting process is once melted and becomes a large lump and requires a large load to be crushed, and if not, a small load is sufficient for crushing. Become. Therefore, the crushing device 3 is provided with a measuring device 31 for measuring the magnitude of the load required for crushing, such as a motor load current and a device for measuring torque, and the discriminating mechanism has a measuring load by the measuring device 31. Based on the above, the meltability of the molten fly ash is judged (meltability confirmation step).

  The sorting device 5 includes a charging unit 51 that receives molten fly ash that has passed through the crushing device 3, and also includes a low melting point molten fly ash discharge unit 52 and a high melting point molten fly ash discharge unit 53, A switching unit 54 for switching between the low melting point molten fly ash discharge unit 52 and the high melting point molten fly ash discharge unit 53 is provided, and the switching unit 54 is controlled to be switched by the determination mechanism 4. .

  The high-melting point molten fly ash discharge unit 53 is connected to a thermal decomposition apparatus 7, and the induced molten fly ash is introduced into the thermal decomposition apparatus 7. In addition, a chemical treatment device 6 is connected to the low melting point molten fly ash discharge unit 52 to introduce the induced molten fly ash (sorting step).

<Thermal decomposition equipment>
The thermal decomposition apparatus 7 includes a heating kiln 71 and a cooling kiln 72 in this order, and after temporarily storing the molten fly ash discharged from the cooling kiln 72, removes heavy metals and the like with a processing agent such as a chelating agent and discharges them. A kneader 74 is provided.

  In the heating kiln 71, the supplied molten fly ash is heated to 400 ° C. to 500 ° C., and dioxins contained in the molten fly ash are decomposed and removed by high heat (decomposition step by heat treatment). The molten fly ash that has passed through the heating kiln 71 is immediately put into the cooling kiln 72 and rapidly cooled to 100 ° C. to 120 ° C., so that resynthesis of dioxins is suppressed. The cooled molten fly ash is temporarily stored in the storage unit 73. The molten fly ash in the storage unit 73 is conveyed to the kneading machine 74 for each predetermined amount, and the processing material supplied from the processing material storage tank 75 is kneaded with the molten fly ash and is contained in the discharged molten fly ash. This is a configuration capable of reducing heavy metals.

<Chemical treatment equipment>
The chemical treatment apparatus 6 includes a decomposition agent storage tank 61 for storing a decomposition agent to be kneaded with molten fly ash, an accelerator storage tank 62 for storing an accelerator used together with the decomposition agent, and the like. A kneading unit 63 for kneading is provided.

  The decomposition agent storage tank 61 is configured to store a decomposition agent added to decompose dioxins contained in fly ash and to be sequentially transported to the kneading unit 63. Next, the accelerator storage tank 62 stores an accelerator added to increase the reactivity of the decomposer added to decompose the dioxins contained in the fly ash, and can be sequentially conveyed to the kneading unit 63. It is configured. Thereby, dioxins contained in the molten fly ash are decomposed (decomposition process by chemical treatment).

  Examples of the decomposing agent and the accelerator include a decomposing agent in which fine particles mainly composed of metal oxide are oil-coated, an aqueous solution of an alkali metal compound, hydrogen peroxide solution, detergent water, monovalent or polyhydric alcohol. And an accelerator composed mainly of an aqueous solution of the above or an aqueous solution of an organic chelating agent is preferably used.

  The kneading unit 63 is configured to knead the molten fly ash, the decomposer, and the accelerator that have been transferred. The kneading part 63 is composed of a rotary kiln for kneading fly ash, a decomposing agent, and an accelerator. A kneading step is performed, and a kneading step is provided with a heating part 64 for heating the inside of the kneading part 63. The heating process is subsequently performed. A burner is effectively used as the heating unit 64.

  The burner is configured to be heated by a flame from the outer peripheral surface side of the rotary kiln at the outlet end side of the rotary kiln, and the rotary kiln is rapidly heated when the kneaded material is kneaded in the rotary kiln. Heating in a wide range from slightly downstream to the exit end of the rotary kiln from the position where the molten fly ash and the decomposition agent join.

  The rotary kiln is provided with an ITV 65 for observing the internal kneaded material, and provided with a combustion control mechanism 66 for determining the temperature of the kneaded material from the image of the ITV 65 and burning the burner based on the temperature determination result. Configured. The combustion is controlled by the combustion control mechanism 66 so that the temperature of the kneaded product is maintained at 120 to 150 ° C.

  Further, a water addition unit 67 for supplying water for adjusting the amount of water in the molten fly ash and maintaining the reactivity of the decomposition agent to the mixing unit may be further provided.

  As shown in FIG. 2, the molten fly ash treatment apparatus of the present invention uses molten fly ash generated in a fly ash melting furnace provided in an incineration facility or the like as a processing object, As a basic configuration, a storage tank 1 for storing molten fly ash as an object to be processed is provided. Moreover, the heating apparatus 2 which heats the molten fly ash from the said storage tank 1 is heated by the crushing apparatus 3 which crushes the molten fly ash heated with the said heating apparatus after cooling, and the said heating apparatus. An image processing apparatus 8 for observing the melting state of the molten fly ash and a discrimination mechanism 4 for determining the meltability of the molten fly ash from the melting state of the molten fly ash by the image processing apparatus 8 are provided. Further, based on the discrimination result of the discriminating mechanism 4, there is provided a sorting device 5 for sorting the melted fly ash that is easy to melt and the melted fly ash that is difficult to melt. In addition, it is equipped with a chemical treatment device 6 that adds a decomposing agent that decomposes dioxins and removes dioxins from easily melted molten fly ash, and heat decomposes by heating molten fly ash that is difficult to melt to decompose dioxins. A device 7 is provided.

  The storage tank 1 discharges a fixed amount of molten fly ash and transfers it to the heating device 2. In the heating device 2, the molten fly ash is heated to 400 ° C. The image processing device 8 captures the molten fly ash heated by the heating device 2 with an ITV 81 or the like, and the imaging device 8 considers the molten fly ash temperature information from a radiation thermometer or the like, its fluidity, etc. To analyze. Based on the analysis result, the determination mechanism 4 determines the meltability of the molten fly ash. The crushing device 3 crushes the molten fly ash that has been agglomerated when heated by the heating device 2 into particles, so that subsequent dioxins can be easily decomposed and removed.

  Since the configuration after the subsequent sorting device 5 is the same as that of the first embodiment, the description thereof is omitted.

  The amount of dioxins discharged together with the molten fly ash can be reduced by efficiently treating the molten fly ash generated from an incinerator, a melting furnace or the like.

Schematic of the molten fly ash treatment apparatus of the present invention Schematic diagram of chemical treatment equipment Schematic diagram of thermal decomposition equipment Schematic of different molten fly ash treatment equipment of the present invention

Explanation of symbols

2 Heating device 3 Crushing device 4 Discriminating mechanism 5 Sorting device

Claims (6)

A molten fly ash treatment method for treating a molten fly ash and performing a decomposition step of decomposing and removing dioxins contained in the molten fly ash,
Before the decomposition step, perform a meltability confirmation step to determine the meltability of the molten fly ash,
A molten fly ash treatment method for performing a separation step of separating molten fly ash that is easy to melt and molten fly ash that is difficult to melt. The molten fly ash determined to be easily melted is subjected to a decomposition process for performing chemical treatment to remove dioxins by adding a decomposition agent that decomposes dioxins,
The molten fly ash treatment method according to claim 1, wherein the molten fly ash determined to be difficult to melt is subjected to a decomposition step in which dioxins are decomposed and removed by heat treatment. A heating device for heating the molten fly ash;
A crushing device for crushing the molten fly ash heated by the heating device after cooling;
A discriminating mechanism for discriminating the meltability of the molten fly ash from the crushing status of the molten fly ash by the crushing device;
A molten fly ash treatment apparatus provided with a separation device for separating molten fly ash that is easily meltable and molten fly ash that is difficult to melt based on the determination result of the determination mechanism. A heating device for heating the molten fly ash;
An image processing device for observing the melting state of the molten fly ash heated by the heating device;
A discriminating mechanism for discriminating the meltability of the molten fly ash from the melting state of the molten fly ash by the image processing device,
A molten fly ash treatment apparatus provided with a separation device for separating molten fly ash that is easy to melt and molten fly ash that is difficult to melt based on the determination result of the determination mechanism.   The molten fly ash treatment apparatus according to claim 3 or 4, further comprising a chemical treatment apparatus that adds a decomposing agent that decomposes dioxins and removes dioxins from easily melted molten fly ash.   The molten fly ash treatment apparatus according to claim 3, further comprising a thermal decomposition apparatus that decomposes dioxins by heating molten fly ash that is difficult to melt.

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