JP3869695B2 - Waste melting furnace operation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a waste melting method for melting different types of waste with high ash content such as municipal waste and digging waste other than municipal waste in a vertical shaft furnace.
[0002]
[Prior art]
Wastes include municipal waste, mainly industrial waste, various industrial wastes, or incineration ash, fly ash, crushed impurities and intermediate treatment products obtained by incineration, There are landfill waste, sludge, etc. that contain earth and sand that have been dug up again. In this waste melting treatment, waste is charged from the upper part of the melting furnace, and a certain amount of coke is charged as a secondary raw material with a basicity adjusting agent such as limestone or silica as the auxiliary material. In addition, oxygen-containing gas or oxygen-enriched gas is blown from the tuyeres at the bottom of the furnace, or air is blown from the tuyere above, and the waste is dried, preheated, pyrolyzed, burned, melted, and taken out as slag or metal. is there. For the effective use of slag, the physical properties of the slag are important. The slag fluidity is an important factor in discharging from the bottom of the furnace and greatly affects the physical properties and quality of the slag.
[0003]
For example, in Japanese Patent Publication No. 55-21923, in a method for melting waste in a melting furnace, lime is supplied to the waste so that the component of slag is 1> CaO / SiO ₂ > 0.5. It is stated that it will operate. This operation is mainly for municipal waste with relatively stable properties, and only the basicity of the final slag is set as the input target for secondary materials.
[0004]
In recent years, slag conversion by melting treatment has been promoted due to the shortage of final disposal sites. Heterogeneous waste is incinerated ash discharged from other factories (stoker furnaces / fluidized beds), incinerated fly ash, and high ash content from landfill waste from the final disposal site. In particular, the excavated waste is covered with soil covering from the viewpoint of scattering and odor, but since it is contaminated with heavy metals and other harmful substances, melting and detoxification are required in a lump.
[0005]
[Problems to be solved by the invention]
Currently, in vertical shaft furnaces, different types of waste are introduced in layers from the top of the furnace to control the mixing rate, and the basicity modifier (limes) is adjusted so that the basicity of the slag is 0.5 to 1.1. is doing.
[0006]
However, when miscellaneous waste is treated, for example, in the case of digging waste, plastics, incineration ash, covering soil, construction waste, etc. that are not suitable for incineration are mixed, and ash content is 15 to 30% compared to 5 to 10% of municipal waste. Even if a certain amount of basicity adjusting agent is added, the basicity deviation is partially large. In particular, in the treatment of excavated waste, the simple basicity varies greatly from 0.02 to 0.3 due to the amount of covering soil, and the basicity is partially high and low. Furthermore, since the incombustible layer such as ash and digging waste and the lime layer are thick and the mixing property is poor, the melting point of the slag tends to increase. As a result, the slag viscosity increases in front of the tuyere, and the flammability of the coke is hindered due to adhesion of slag to the tuyere and coke. In the worst case, it becomes impossible to pour hot water. For this purpose, an increase in the load of the slag heating work due to the lance occurs, and it is necessary to raise the CR as a countermeasure.
[0007]
Therefore, the present invention provides good slag fluidity in a waste melting furnace operating method in which municipal waste and high-ash waste such as incineration ash and excavated waste other than municipal waste are melted in the waste melting furnace. Therefore, the present invention provides a method for operating a waste melting furnace capable of stable operation.
[0008]
[Means for Solving the Problems]
The present invention relates to a waste melting furnace operating method in which municipal waste and high-ash waste such as incineration ash and excavated waste other than municipal waste are melted in a waste melting furnace. Calculate the amount of limestone mixed with the different types of waste from the relationship between the soil contamination rate and basicity for each ash content of the different types of waste, and mix this amount of limestone with the different types of waste in advance. The dissimilar waste and the municipal waste are mixed and charged by a crane in a pit. Furthermore, you may charge alternately with the limestone required for the municipal waste in this mixture.
[0009]
The present invention also relates to a waste melting furnace operating method in which municipal waste and different types of high-ash waste such as incineration ash and excavated waste other than municipal waste are melted in a waste melting furnace. The basicity required when mixing the wastewater, the amount of limestone determined based on the basicity is mixed with the foreign waste in advance, and the foreign waste and the municipal waste are put into the crane in the pit. It is characterized by mixing and charging.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing the distribution (charged state) of dust and lime in the melting furnace, (a) and (b) are the present invention, and (c) and (d) are comparative examples.
[0011]
FIG. 1 (d) shows a case in which only municipal waste is treated, and the municipal waste 1 and the amount of lime 2 required for the municipal waste are alternately put in layers from the furnace top and melted. Is.
[0012]
Since municipal waste is generally composed of miscellaneous items, in this case, from the average waste quality, the average basic waste is The amount of limestone required for the operation is determined, and the input amount is determined and charged according to the input amount of garbage (kg / ch). Municipal waste has a low ash content, so the ash layer at the bottom of the furnace is thin and easy to mix with limestone, and the melting point of the melt is lowered, enabling stable operation.
[0013]
Fig. 1 (c) shows that municipal waste 1 and dissimilar waste 3 are treated at the same time, and the basicity required per ton is calculated from the average waste quality of municipal waste and dissimilar waste. Furthermore, the mixing ratio of both is accurately grasped, and the amount of limestones to be charged is determined in accordance with the amount of both charged garbage.
[0014]
The charging method was as follows.
[0015]
(C-1) does not mix the municipal waste 1 and the different kind of waste 3, but alternately charges it in layers from the top of the furnace, and in the meantime, the amount of limestones 2 and different kinds of waste required for the municipal waste 1 The amount of limestone 4 required for the garbage 3 was charged in layers.
[0016]
(C-2) mixes municipal waste 1 and foreign waste 3 in advance and charges the mixture in layers from the top of the furnace. In total, each was charged in layers.
[0017]
In (c-1), the basicity is adjusted at the boundary between each of the trash 1 and 3 and the limestone 2 and 4, but the basicity adjustment is insufficient at the central part of the layered dissimilar trash and the melting point is lowered. The fluidity of the slag declined, and the combustion before the tuyere worsened further due to the slag adhering to the tuyere, and stable operation was not possible.
[0018]
In (c-2), since the municipal waste 1 and the different kind of waste 3 are mixed, the layer of the garbage naturally becomes thicker, and accordingly, uniform basicity adjustment is difficult. ), The melting point other than the interface did not decrease, and the slag fluidity decreased and stable operation was not possible. In particular, when different types of waste are dug up, the basicity of the layer that is not mixed with limestone is extremely lowered, resulting in problems such as inability to pour out.
[0019]
In addition, since municipal waste and different types of waste are usually mixed with a waste pit and a waste crane, in the case of (c-2), it is difficult to accurately grasp each weight ratio in 1ch mixed waste. There was a large variation in the basicity of 1ch.
[0020]
FIG. 1 (a) shows a method for calculating the basicity required for different kinds of waste in advance by the method of the present invention, determining the amount of limestone to be charged based on the basicity, and determining the determined amount of limestone. Before charging 4 into the furnace, it is mixed with the foreign waste 3 in advance. Next, this mixture 3 and 4 is further mixed with municipal waste 1.
[0021]
The mixture of the three parties 1, 3, and 4 is alternately layered with the amount of limestone 2 required for municipal waste 1.
[0022]
The inventor has found through experiments that the desired fluidity of the slag can be obtained if the basicity of the different types of waste is in the range of 0.5 to 1.2.
[0023]
Furthermore, in order to maintain the basicity in the range of 0.5 to 1.2, it is only necessary to charge 56 to 224 kg (100 to 400 kg in terms of limestone) of CaO of limestone with respect to 1 t of different types of waste. I found it.
[0024]
In this way, if different kinds of waste 3 and limestones 4 are mixed in advance and charged in advance, the basicity of the different kinds of garbage is always adjusted and the melting point is lowered, so that it is easy to dissolve, and the lime is entirely formed. The dispersion of the basicity in the furnace is smoothed by being dispersed. Furthermore, since the mixing work of different types of waste mixed with limestone in advance and general waste is performed using a crane in the pit, it is difficult to accurately grasp the weight ratio of each, but it is somewhat difficult to find different types of waste, especially digging up. In the case of garbage, even if the mixing rate varies, the basicity of different kinds of garbage itself is adjusted in advance, so that stable operation with little variation in basicity of 1ch can be obtained.
[0025]
FIG. 1 (b) shows another embodiment of the present invention. First, the basicity required when the municipal waste 1 and the foreign waste 3 are mixed is calculated, and based on the basicity, the limestone Before the charged amount of limestone 2 and 4 is charged into the furnace, it is first mixed with the foreign waste 3 and then mixed with the municipal waste 1 and charged into the furnace. ing.
[0026]
Even in this method, since the basicity of the different types of waste was adjusted, the melting point of the melted material was lowered, and stable operation was obtained as a whole furnace.
[0027]
In the experiments of the present inventors, it was found that the basic melt of the mixture of municipal waste and general waste can obtain proper melting if limestones are charged so as to maintain the range of 0.8-1. .
[0028]
FIG. 2 is a diagram showing an example of the relationship between the soil mixing rate in different types of waste, the amount of limestone mixed in advance (kg / type of different types of waste t), and the basicity of different types of trash after mixing with lime. FIG. 2 shows a case where the ash content of different kinds of waste (before soil mixing) is 30%, in order to make the basicity of the different kinds of garbage after soil mixing 0.5 to 1.2 according to the soil mixing ratio. The pre-mixed limestone ratio (kg) to be mixed in advance per different kind of waste lt can be obtained.
[0029]
For example, when the premixed limestone ratio is less than 30% and the premixed limestone ratio is 100 to 200 and 30 to 70%, the premixed limestone ratio may be 200 to 400.
[0030]
Thus, if the relationship between soil mixing rate and basicity is calculated | required for every ash content of different kinds of garbage, the amount of limestone mixed according to the kind of different kinds of garbage can be calculated | required easily.
[0031]
When melting waste of 231 kg of municipal waste (kg kg) and ash content of 30% (of which 69 kg of covered soil) is melted, the basic waste is mixed with 69 kg of limestone from the graph in FIG. 50 kg of limestone is added so that the basicity of the mixture becomes 0.88. Lime refers to limestone and all materials containing CaO. For example, waste melting furnace dust containing slaked lime can also be used. Further, not only CaO but also a substance containing MgO can obtain the same effect.
[0032]
【The invention's effect】
According to the present invention, when municipal waste and different types of waste are melted, it can be maintained well without deteriorating the fluidity of slag, and as a result, work load and CR can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the distribution of trash and lime in a melting furnace, (a) and (b) are the present invention, and (c) to (d) are comparative examples.
FIG. 2 is a diagram showing the relationship between soil mixing ratio and basicity of different types of waste.
[Explanation of symbols]
1: Municipal waste 2: Lime 3: Heterogeneous waste 4: Lime

Claims (4)

In the operation method of waste melting furnace that melts municipal waste and different kinds of high-ash waste such as incineration ash and digging waste other than municipal waste in the waste melting furnace,
The basicity required for different types of waste is calculated, the amount of limestone mixed in the different types of waste is calculated from the relationship between the soil contamination rate and the basicity of each type of ash in the different types of waste, and this amount of limestone is determined in advance. A method for operating a waste melting furnace, comprising mixing with different kinds of garbage, mixing the different kinds of garbage and the municipal waste with a crane in a pit, and charging them. In the operation method of the waste melting furnace that melts municipal waste and different types of waste with high ash content such as incineration ash and digging waste other than municipal waste in the waste melting furnace,
The basicity required for different types of waste is calculated, the amount of limestone mixed in the different types of waste is calculated from the relationship between the soil contamination rate and basicity of each type of ash in the different types of waste, and this amount of limestone is Mixing with different types of waste in advance, further mixing the different types of waste and the municipal waste with a crane in a pit, and alternately charging with limestones required for the municipal waste in the mixture To operate waste melting furnace. In the operation method of the waste melting furnace that melts municipal waste and different types of waste with high ash content such as incineration ash and digging waste other than municipal waste in the waste melting furnace,
The basicity required when mixing municipal waste and different types of waste is calculated, the amount of limestone determined based on the basicity is mixed with the different types of waste in advance, and further A method for operating a waste melting furnace, characterized in that municipal waste is mixed and charged in a pit with a crane . Operation method of waste melting furnace according to claim 3, characterized in that the set mixing basicity of municipal solid waste and different garbage (CaO / SiO ₂₎ to 0.8.

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