JP2006266548A - Ash melting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ash melting method capable of effectively melting the melting object ash by a surface melting system. <P>SOLUTION: Carbide is mixed in the melting object ash to be charged into an ash melting furnace 6 of the surface melting system in advance. The carbide is a powder body or a granulated material of which particle diameter is 10 mm or less, the mixing ratio is preferably 30% or less, and the carbide is preferably derived from the waste. In the ash melting furnace 6, the melting object ash is heated or melted from both of the inner and outer surfaces by heating from a surface of a melting object ash layer by a burner 9 and combustion heat of the carbide mixed into the inside of the melting object ash layer, and thereby melting excellent in heat efficiency is possible. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is an efficient method for incineration ash discharged from incinerators such as sludge, municipal waste and industrial waste, and waste-derived ash such as molten fly ash from the melting furnace in an ash melting furnace of the surface melting type. The present invention relates to an ash melting method for melting well.

  Conventionally, incineration ash such as sludge and municipal waste has been exclusively disposed of in landfills, but it is difficult to secure a suitable site for landfilling, and problems such as the migration of heavy metals eluted from the incineration ash to groundwater are pointed out Therefore, recently, a method of melting incineration ash at a high temperature of 1200 to 1400 ° C. to form slag and enclosing heavy metals in a stable glassy material has become widespread.

  For this purpose, for example, an ash melting furnace is used as described in Patent Document 1. Although the ash melting furnace of this Patent Document 1 has a structure combining swirl melting and surface melting, most of the fuel type ash melting furnaces heat the surface of the molten ash layer charged into the furnace with a burner, This is a method of melting the surface. This surface melting method is widely used because there is an advantage that the molten slag can flow down naturally if the bottom of the furnace is gently inclined.

However, since this method is a method in which heating is performed only from the surface of the ash layer to be melted as schematically shown in FIG. 3, heat is not easily transmitted to the inside of the ash layer to be melted with low thermal conductivity. Since it takes time, there is a problem that a considerably large melting area is required to increase the processing capacity.
Japanese Patent No. 3071171

  An object of the present invention is to solve the above-mentioned conventional problems and to provide an ash melting method capable of melting molten ash by a surface melting method in a shorter time than in the prior art.

  In the ash melting method of the present invention made to solve the above-mentioned problems, carbides are mixed in advance into the molten ash charged into the ash melting furnace of the surface melting type, and the molten ash layer by the burner is mixed. The molten ash is heated and melted from both inside and outside by heating from the surface and combustion heat of carbide mixed in the molten ash layer.

  In addition, although the mixing rate of the carbide | carbonized_material with respect to a molten ash changes with carbide | carbonized_material properties, it is preferable to set it as 30% or less, and it is preferable that the particle size of a carbide | carbonized_material is 10 mm or less powder and granulated goods. Further, it is preferable from the viewpoint of waste treatment that the carbide is derived from waste.

  According to the ash melting method of the present invention, the molten ash layer can be heated and melted from both the inside and outside by heating from the surface with a burner and the combustion heat of the carbide mixed in the molten ash layer. In particular, the carbide is mixed in the molten ash layer and generates heat at a position adjacent to the object to be melted, so that it can be melted very efficiently. In particular, if the pyrolysis residue of the waste or the waste carbonized in the carbonization furnace is used as the carbide, the burner fuel can be reduced and the waste can be treated, and the heavy oil that is the burner fuel can be reduced. it can.

Preferred embodiments of the present invention are shown below.
In FIG. 1, reference numeral 1 denotes a molten ash storage tank, in which incineration ash discharged from an incinerator such as sludge, municipal waste, industrial waste, and molten fly ash discharged from the melting furnace is disposed. Ashes derived from things are stored. In addition, it is preferable to keep the massive ash like the ash of the stalker furnace crushed by a crusher.

  The ash in the storage tank 1 is cut out by a fixed amount on the conveyor 3 by a cutting device 2 such as a screw feeder provided in the lower part thereof. In this embodiment, as the conveyor 3, a flight conveyor is used in which a large number of feed plates are attached to an endless chain and the molten ash is transferred while being pushed by these feed plates. However, the structure of the conveyor 3 is not particularly limited, and for example, a screw conveyor may be used.

  4 is a carbide storage tank, and a carbide is cut out on the conveyor 3 by a predetermined amount by a cutting device 5 provided in the lower part thereof. Although a commercially available carbide can be used as the carbide, it is preferable to use a carbide derived from waste. For example, a carbide produced by pyrolyzing wood, sludge, garbage, or the like can be used. The particle size of the carbide is preferably 10 mm or less. This is because if the particle size is larger than this, uniform mixing is difficult.

  The mixing ratio of the carbide to the ash to be melted varies depending on the properties of the carbide, but is preferably 30% or less by weight. If the amount is larger than this, the amount of molten slag increases, which is against the original purpose of volume reduction of waste by slag formation.

  The carbides cut out by a certain amount on the conveyor 3 are mixed with the ash to be melted supplied from the preceding storage tank 1 and put into the ash melting furnace 6. If the above-described flight conveyor, screw conveyor or the like is used, the carbide and the molten ash are mixed almost uniformly without using any special mixing means. This is because the apparent specific gravity is almost equal.

  The shape of the ash melting furnace 6 is not particularly limited as long as it is a surface melting type ash melting furnace. In this embodiment, an ash melting furnace 6 having an inlet 7 at the top of the inclined furnace body and a molten slag outlet 8 at the bottom is used. The mixture of the introduced carbide and molten ash is heated to 1200 to 1400 ° C. by the burner 9 while flowing down in a layered manner inside the furnace body, and the surface is melted.

  At this time, as shown in FIG. 2, the molten ash is not only heated from the surface of the molten ash layer by the burner 9, but also by the combustion heat of the carbide mixed inside the molten ash layer. It is melted by heating. Since the carbide burns at a position in contact with the molten ash, the heat of combustion efficiently contributes to the melting of the molten ash and melts the molten ash quickly. It is also conceivable to burn the carbide in a burner frame like a pulverized coal burner. In that case, the heat of combustion contributes to the melting of the molten ash, and in addition, heat dissipation from the furnace wall and heating of the exhaust gas. Therefore, the thermal efficiency is deteriorated as compared with the method of mixing carbide in the molten ash as in the present invention.

  In this way, the molten ash is melted efficiently and becomes molten slag, and flows down from the molten slag discharge port 8 at the lower part of the furnace body. This molten slag is effectively used for various applications including roadbed materials.

  Carbides were mixed in the ash melting furnace at a weight ratio of 0%, 10%, 20%, and 30%. Table 1 shows the properties of the molten ash and the carbide. In the case where no carbide is added, 202 L of kerosene per 1 ton of molten ash is required as burner fuel in order to completely slag the molten ash, but when 10% of carbide is added, the amount of kerosene used is reduced. The amount of kerosene used can be reduced by 34.8% when carbonized is added to 20%, and the amount of kerosene used is reduced by 53. 2% could be reduced.

It is explanatory drawing which shows the 1st Embodiment of this invention. It is principal part explanatory drawing in this invention. It is principal part explanatory drawing in the conventional method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Storage tank of molten ash 2 Cutting device 3 Conveyor 4 Carbide storage tank 5 Cutting device 6 Ash melting furnace 7 Input port 8 Molten slag discharge port 9 Burner

Claims (4)

  Carbide is mixed in advance into the molten ash to be charged into the ash melting furnace of the surface melting method, heating from the surface of the molten ash layer by a burner, and the carbide mixed inside the molten ash layer An ash melting method characterized in that molten ash is heated and melted from both inside and outside by combustion heat.   2. The ash melting method according to claim 1, wherein a mixing ratio of the carbide to the molten ash is set to 30% or less.   The ash melting method according to claim 1, wherein the particle size of the carbide is 10 mm or less.   The ash melting method according to claim 1, wherein the carbide is derived from waste.

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