JP4851895B2 - Shredder dust melting method - Google Patents

Description

  The present invention relates to a shredder dust melting method that can stably operate while suppressing the retention of tar when melting shredder dust in a shaft furnace type gasification melting furnace.

  Shredder dust finely cut by a shredder machine or the like is generated at the time of dismantling of discarded automobiles, home appliances, and the like. As a method for treating shredder dust, there is known a method in which shredder dust is melted and recycled in a shaft furnace type gasification melting furnace. In this melting process, shredder dust and other waste materials as well as coke and limestone are added to the shaft furnace type gasification melting furnace, and air and oxygen are blown from the lower tuyere at the bottom of the furnace. In this drying zone, the waste is dried, the combustible substance is pyrolyzed from the lower part of the shaft part in the pyrolysis zone of the morning glory part, and the pyrolysis residue is burned and melted in the combustion melting zone below the pyrolysis zone.

  Shredder dust contains many plastic materials such as urethane. Therefore, when the shredder dust is put into the shaft furnace type gasification melting furnace, the temperature above the drying zone is 500 ° C. or less, so that the tar generation rate increases. The generated tar content is solidified into liquid and stays above the drying zone, and adheres to the waste and the furnace wall that has been added to form a ventilation resistance layer, resulting in unstable operation. In addition, there arises a problem that a tar component adheres to the gas pipe exhausting the exhaust gas to block the gas pipe.

  Therefore, the present applicant has proposed a technique for preventing the generated tar content from staying above the dry zone in the shredder dust melting method (see Patent Document 1).

  4A and 4B are diagrams illustrating a shredder dust melting method of Patent Document 1 in which (a) shows the position of the tuyere and (b) shows changes in the furnace atmosphere temperature.

In FIG. 4 (a), the shaft furnace type gasification melting furnace 1 is configured such that a waste material is introduced into a furnace from a charging device 8 provided with seal valves on the upper and lower sides, and air + oxygen is supplied from a lower tuyere 2 to the furnace. Is blown and melted. The temperature in the furnace is measured by a thermometer 5, a furnace top thermometer 6, and the temperature in the refractory is measured by a refractory thermometer 7. Furnace so that the atmosphere temperature in the furnace near the stock line is 550 ° C. to 650 ° C. from the tuyere 4 arranged close to the stock line of the shaft furnace type gasification melting furnace 1 and not exceeding the stock line. Air or oxygen is blown into the object to be processed packed bed.
Japanese Patent Laid-Open No. 2003-247708

  However, when operated according to Patent Document 1, as shown in FIG. 4B, the combustion melting zone of the hearth is about 1800 ° C. and the solution loss reaction zone is about 1000 ° C., but the shaft above the morning glory is high. In the pyrolysis zone / dry zone, even if the upper end portion of the dust filling was 600 ° C. or higher, there was a portion where the temperature once decreased to less than 550 ° C. due to the endothermic heat of the solution loss reaction. As a result, even though the vicinity of the stock line can prevent the stay of tar at 550 to 650 ° C by blowing from the tuyere, the tar stays in the lower part of the vicinity of the stock line, and the residue adheres in the furnace. As a result, the unloading becomes poor and the processing amount may be reduced. In addition, when shelves are resolved, char is scattered, the temperature of the combustion chamber in the rear stream rises rapidly, and clinker is generated in the combustion chamber. Therefore, it was necessary to stop the furnace and remove it periodically. .

  Therefore, the present invention prevents a stagnation of the tar content and prevents a decrease in the furnace atmosphere temperature when the shredder dust is melted in the shaft furnace type gasification melting furnace so that stable operation can be performed reliably. The purpose is to do.

  In the method for melting shredder dust by the shaft furnace type gasification melting furnace of the present invention, air or oxygen is supplied from the region where the atmospheric temperature in the furnace is lowered or lower than that in the shaft portion or morning glory portion due to the endotherm of the solution loss reaction. It blows in and makes the atmosphere in a furnace 500 degreeC or more over the whole region, and prevents the partial fall (less than 500 degreeC) of temperature.

  In the method for melting shredder dust of Patent Document 1, the cause of the phenomenon of unstable operation was investigated. (1) It was impossible to completely dry distillation above the tuyere near the stock line. It was found that when the temperature of the shredder dust dropped in the furnace, the temperature of the solid did not increase with the gas whose temperature decreased due to the endotherm of the solution loss reaction, and the low temperature region was formed in the shaft or morning glory. In this low temperature region, the tar component that cannot be volatilized stays and turns into a ventilation resistance layer around the furnace char (dry distillation residue). (2) Volume shrinkage occurs due to a decrease in the thermal decomposition rate in the low temperature region. It was suppressed, and it was found that the unloading was poor.

  Therefore, in order to prevent the formation of a partial low-temperature region due to the endothermic heat of the solution loss reaction, tuyere is installed in the region where the ambient temperature is lowered or below it, and air or oxygen is blown into the furnace. By burning the combustible matter in the tar, gas, and carbonization residue, preventing the formation of a ventilation resistance layer due to retention of the tar, which cannot be volatilized by securing the atmospheric temperature in the melting furnace to 500 ° C. or higher, Decreasing the thermal decomposition rate suppresses volume shrinkage and prevents unloading.

  Therefore, according to the present invention, the position of the upper tuyere that blows air or oxygen into the workpiece packed bed in the furnace is a position below the stock line and the distance from the stock line to the stock line and the lower tuyere is 40. One or more stages are installed at a position of less than%, and similarly one or more stages are installed at a position of 40% to 60%, and the furnace atmosphere of the morning glory and the shaft part is maintained at 500 ° C. or more over the entire area. The stock line is the surface level of the workpiece packed bed formed by the workpiece to be put into the furnace during steady operation, and the lower tuyere is a feather that blows air + oxygen provided in the hearth The mouth.

  As shown in the graph of FIG. 3, in the shaft furnace type gasification melting furnace, it was found that the temperature in the furnace rises when the amount of oxygen blown from the upper tuyere is increased. Therefore, the amount of oxygen blown from the upper tuyere is set to 50% by volume or more of the amount of oxygen blown to the whole, and the treatment ratio of shredder dust is set to 80% by weight or less of the amount to be treated, and the temperature is partially decreased (less than 500 ° C.). Can be prevented.

  The present invention provides a melting furnace furnace atmosphere by blowing oxygen or air from a tuyere located in a temperature lowering region due to heat absorption of a solution loss reaction when a shredder dust is melted in a shaft furnace type gasification melting furnace. Can be set to 500 ° C. or higher, the formation of the ventilation resistance layer due to the retention of the tar content can be prevented, and the pressure difference in the furnace is reduced. In addition, since a decrease in the thermal decomposition rate can be prevented, stable operation is possible. Furthermore, clogging and unloading were stabilized, the amount of processing increased, combustion chamber temperature fluctuations were reduced, clinker generation in the combustion chamber was greatly suppressed, and the clinker removal work load was also reduced.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a shredder dust melting method according to the present invention, wherein (a) shows the position of the tuyere, (b) shows the state of the furnace atmosphere temperature, and FIG. 2 shows the upper tuyere position in the present invention. It is a figure which shows the tuyere structure of a horizontal cross-section part, and attaches | subjects the same code | symbol to the same structure as above-mentioned FIG.

The upper tuyere 3a is installed at least one stage at a distance (L ₁ ) from 0% to 40% of the entire packed bed height (distance from the lower tuyere to the stock line) L _{0 in} the downward direction from the stock line. , upper tuyere 3b is similarly placed at least one or more stages from a distance of over 40% _{(L 1} than) 60% of the distance _(L 2 + L _1). The upper tuyere portion oxygen amount converted from the air and oxygen blown from the upper tuyere 3a and 3b is 50% by volume or more of the total oxygen amount.

  As shown in FIG. 1 (a), when the shredder dust is melted in the shaft furnace type gasification melting furnace 1 from the lower tuyere 2 into which oxygen-enriched air is blown, a solution is provided to prevent the formation of a low temperature region. Air or oxygen is blown from the tuyere 3a, 3b arranged in the vicinity of the region where the furnace atmosphere temperature is lowered by the endothermic reaction of the loss reaction.

  As shown in FIG. 1 (b), the furnace ambient temperature is about 1800 ° C. in the combustion melting zone of the hearth, about 1000 ° C. in the solution loss reaction zone, and the shaft portion 1b above the morning glory 1a is in the pyrolysis zone.・ It becomes a dry zone and the temperature decreases due to the solution loss reaction, but by blowing air or oxygen-enriched air from the tuyere 3a, 3b, the temperature in the furnace of the shaft portion 1b rises and the pyrolysis zone The drying zone can be maintained in the range of 500 ° C. or higher. In addition, this time, the thermometer 5 was inserted from the middle part of the shaft and the upper part of the morning glory, and the temperature was measured at a plurality of points and averaged. In addition, the correlation between the actual temperature measurement result and the measured value of the representative point, for example, the refractory thermometer 7 for measuring the temperature inside the refractory and the thermometer 6 at the top of the furnace, is grasped in advance, and the refractory temperature and the top of the furnace are indirectly monitored. You may manage and control by gas temperature.

  Table 1 shows the properties of the shredder dust of company A melt-treated in this example.

Table 2 shows the properties of general waste in B city.

Table 3 shows melting treatment conditions and treatment results when the general waste shown in Table 2 is mixed with the shredder dust shown in Table 1.

  In this example, the temperature of the shaft portion and the morning glory portion was maintained at 550 ° C. to 650 ° C., retention of the tar content was prevented, and stable operation could be performed without causing shelves.

(A) shows the position of the tuyere in this invention, (b) is a figure which shows the state of furnace atmospheric temperature. It is a figure which shows the tuyere structure of the horizontal cross-section part in an upper tuyere position in this invention. It is a graph which shows the relationship between the oxygen ratio which blows in from an upper tuyere, and average melting furnace temperature. In the conventional shredder dust melting method, (a) shows the position of the tuyere and (b) shows the change in the furnace atmosphere temperature.

Explanation of symbols

1: shaft furnace type gasification melting furnace 1a: morning glory part 1b: shaft part 2: lower tuyere 3a, 3b: upper tuyere 4: upper tuyere 5: thermometer 6: furnace top thermometer 7: refractory temperature 8 : Loading device

Claims (1)

In the melting treatment method of shredder dust by the shaft furnace type gasification melting furnace having the hearth part, morning glory and shaft part provided with the lower tuyere,
The position of the upper tuyere that blows air or oxygen into the workpiece packed bed in the furnace is a position below the stock line and less than 40% of the distance from the stock line to the stock line and the lower tuyere. Install one or more stages, and similarly install one or more stages at 40% to 60%, maintain the morning glory and the atmosphere in the furnace of the shaft section at 500 ° C or higher, and the amount of oxygen blown from the upper tuyere The amount of oxygen blown into the whole is 50 vol% or more, the shredder dust treatment ratio is 80 mass% or less of the amount to be treated, and the retention of tar content is prevented .

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