JP3742947B2 - Waste incineration method and incinerator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for incinerating industrial waste, general waste, and the like and a furnace for incineration.
[0002]
[Prior art]
Conventionally, a rotary kiln type incinerator has been used as an apparatus for incinerating industrial waste, general waste, and the like (hereinafter simply referred to as waste).
FIG. 7 shows an example of a conventional rotary kiln-type incinerator, in which an opening b on the upper side of the inclination of a cylindrical rotary kiln a having a predetermined inclination angle and rotatable in the circumferential direction is a wind While being closely enclosed by the box c, as shown in FIGS. 8 and 9, a refractory material d is provided in the wind box c.
[0003]
The refractory material d having an outer diameter smaller than the inner diameter of the rotary kiln a protects the wind box c from high-temperature combustion heat in the rotary kiln a, and the waste refractory material d is disposed through the refractory material d. An inlet e and a burner f for injecting fuel such as kerosene, heavy oil, propane gas, and pyrolysis gas are provided in the rotary kiln a.
[0004]
When the combustion air is supplied into the wind box c from the air fan g while rotating the rotary kiln a in the circumferential direction, the combustion air is provided between the wind box c and the refractory material d as shown in FIG. The air volume circulates in the direction indicated by the arrow A by the partition wall h in the direction indicated by the arrow A, and the amount of air that is approximately 1/3 of the air fed into the wind box d is equal to the inner peripheral surface of the rotary kiln a and the outer peripheral surface of the refractory material d The air is blown into the rotary kiln a through the annular clearance i formed between the two and the air amount of about 2/3 of the remaining amount is blown into the rotary kiln a through the notch j formed in the refractory material d.
[0005]
In this way, while supplying combustion air into the rotary kiln a, fuel is sent from the burner f and ignited, and the thrown-in waste is dried and burned. When the waste having a high calorific value is sufficiently combusted, the temperature in the rotary kiln a rises, so that the fuel supply is stopped, and then the self-combustion is performed by supplying combustion air. The incinerated ash obtained by drying → combustion is discharged from the discharge port k on the lower side of the rotary kiln a and solidified as it is or using cement or the like, and then disposed of in landfill.
[0006]
[Problems to be solved by the invention]
In the case of the rotary kiln a, since waste and combustion air can be supplied only from the opening b, the temperature atmosphere in the vicinity of the opening b tends to decrease. Solid or liquid wastes burn and burn with a phenomenon in which they become combustible gases by evaporation or thermal decomposition, then mix with air and oxidize. To maintain combustion, the combustion of combustible gases The concentration needs to be kept within a certain range.
[0007]
If air is blown onto waste that is not sufficiently burned, the concentration of combustible gas cannot be maintained, and the flame cannot be maintained. For this reason, ignition was delayed and efficient combustion was not possible. Therefore, maintaining the combustion at the opening b is very important in the case of the rotary kiln a. However, in the conventional rotary kiln type incinerator, the contact between the waste and the combustion air in the vicinity of the opening b. When the excess air ratio is increased, the vicinity of the opening b of the rotary kiln a becomes difficult to burn, and the fuel loss is increased.
[0008]
Further, an upward air flow is generated in the rotary kiln a due to the combustion temperature at which the waste is incinerated. Then, a part of the air blown through the wind box c passes through the space above the rotary kiln a on the ascending current, and is directly flowed in the direction of the outlet k without being used for combustion, and is discharged to the outside. (The flow shown in the direction of arrow B in FIG. 7).
[0009]
Since the rotary kiln a is inclined in a downward state, when air is released on the ascending current, the oxygen concentration necessary for combustion gradually decreases in the intermediate part of the rotary kiln a, and mixing with the combustion gas occurs. Since it becomes weak, the combustion temperature in the rotary kiln a is lowered and the contact with the waste (incinerated material) is reduced, and there is a problem that the unburned portion tends to remain in the rotary kiln a.
[0010]
In view of the problems of the conventional waste incineration method and the incinerator described above, the present invention is configured to send the combustion air to the position near the opening of the rotary kiln and the intermediate portion while generating a swirling flow to generate waste. It aims at providing the incineration method of the waste which improves the combustion efficiency of this.
Another object of the present invention is to provide a waste incinerator capable of improving the mixing efficiency with air and improving the combustion efficiency by reversing and stirring the waste in the rotary kiln. is there.
[0011]
[Means for Solving the Problems]
In order to achieve the above-described object, the incineration method of the present invention introduces waste into a rotary kiln that is rotatable in the circumferential direction in an inclined state, supplies combustion air, and ignites the fuel supplied from the burner. In the method of incinerating waste, the combustion air is blown out toward the waste from the blowout port formed in the refractory material 4 provided in the wind box 3 surrounding the opening 2 on the inclined upper side of the rotary kiln 1 and the rotary kiln 1 Sealing air is fed from the clearance 7 with the refractory material 4.
[0012]
The incinerator of the present invention is a furnace for injecting waste into a rotary kiln that can rotate in a circumferential direction in an inclined state, supplying combustion air, igniting the fuel supplied from the burner, and incinerating the waste The rotary kiln 1 is provided with a stirrer 12 on the inner circumferential surface of the rotary kiln 1 for raising and reversing the waste along the rotational direction of the rotary kiln 1.
[0013]
Furthermore, the incinerator of the present invention is a furnace for injecting waste into a rotary kiln that can rotate in the circumferential direction in an inclined state, supplying combustion air, igniting the fuel supplied from the burner, and incinerating the waste In the refractory material 4 provided in the wind box 3 surrounding the opening 2 on the inclined upper side of the rotary kiln 1, a blowout port through which combustion air can be blown out toward the waste is formed and the rotary kiln 1 and the refractory material 4 are formed. From the clearance 7, sealing air is sent, and on the inner circumferential surface of the rotary kiln 1, waste is lifted and reversed along the rotational direction of the rotary kiln 1, and a stirrer 12 that can be stirred is provided.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 and 2, the opening 2 on the upper side of the cylindrical rotary kiln 1 having a predetermined inclination angle and rotatable in the circumferential direction is tightly surrounded by the air box 3 and within the air box 3. Is provided with a refractory material 4, and a burner 6 for injecting fuel such as kerosene, heavy oil, propane gas, and pyrolysis gas through the refractory material 4 toward the rotary kiln 1. The combustion air sent from an air fan (not shown) is blown into the rotary kiln 1 while fuel is sent from the burner 6 to ignite, the input waste is dried and burned, and the incinerated ash is disposed of as waste. Same as before.
[0015]
In the present invention, in addition to injecting combustion air from an annular clearance 7 formed between the rotary kiln 1 and the refractory material 4, combustion air outlets 8 and 9 are formed in the refractory material 4, and the rotary kiln 1 and the refractory material are fired. A feature is that a small amount of combustion air is blown from the clearance 7 formed with the material 4 and the remaining amount of combustion air is blown into the rotary kiln 1 from the respective outlets 8 and 9 so as to increase the combustion efficiency. Have.
[0016]
That is, the amount of air blown from the clearance 7 is set to be approximately 1/3 of the total amount of blown air to the rotary kiln 1, and the remaining air amount 2/3 is sent into the rotary kiln 1 from the respective outlets 8 and 9. It has been adjusted. However, this numerical value is not limited, and can be appropriately adjusted according to the size of the rotary kiln 1 and the content of waste.
[0017]
The air sent from the clearance 7 serves to seal the clearance 7 in addition to the combustion. That is, the internal pressure of the rotary kiln 1 is adjusted to a -5 to -10 mm water column, and since there is a pressure fluctuation, the waste in the rotary kiln 1 must be sent to the wind box 3 without being kept at a positive pressure. Since combustion waste gas or the like may flow backward, the backflow is prevented by sealing air. Further, the refractory material 4 is heated by the combustion heat in the rotary kiln 1, and the air box 3 is cooled by supplying air into the wind box 3.
[0018]
Thus, by reducing the supply air from the clearance 7, the concentration and temperature of the combustible gas in the vicinity of the opening 2 are maintained, the ignition is accelerated and the thermal decomposition is promoted to increase the initial combustion efficiency. Waste is efficiently burned by a large amount of combustion air fed into the rotary kiln 1 from the ports 8 and 9.
[0019]
For this purpose, the outlets 8 and 9 are provided at two locations on one side along the circumferential direction of the refractory material 4, for example, at 45 ° and 135 ° points clockwise from the center of the refractory material 4 in FIG. As shown in FIGS. 3 and 4, the blowout ports 8 and 9 face the axial direction of the rotary kiln 1 and the tilt direction with respect to the rotational direction of the rotary kiln 1.
[0020]
Normally, the rotary kiln 1 rotates in either the left or right direction, but in the present invention, it is rotated in the right direction as shown in FIG.
The waste 10 is not located at the bottom of the rotary kiln 1, but contact friction works between the rotary kiln 1 and the waste 10 so that the waste 10 tends to be pushed up along the rotation direction. Since the waste 10 has a function of lowering due to its own weight, the waste 10 is located in the rotary kiln 1 in a slanting left direction along the rotational direction as shown in FIG. It is what. Therefore, it is desirable that the combustion air blown out from the blowout ports 8 and 9 strikes the waste 10.
[0021]
Further, the reach distance of the combustion air to the waste 10 in the rotary kiln 1 from the outlets 8 and 9 is different.
Depending on the scale of the rotary kiln 1, the reach distance from the outlets 8 and 9 is 1/5 × L to 1/3 × L from the opening 2 from the lower outlet 9, and the opening from the upper outlet 8 What is necessary is just to reach | attain in the range of 1/3 * L-1 / 2 * L from the part 2. FIG.
[0022]
For example, in the case of the rotary kiln 1 having an inner diameter D = 4 m and a length L = 14 m, the lower blowout port 9 reaches the waste 10 at a position 3 to 4 m from the opening 2, and the upper blowout port 8. , It reached the waste 11 at a location 5 to 7 m from the opening 2 and sent fresh air to the waste 10. As a result, the optimum combustion effect was obtained.
Combustion air branched from a combustion air supply path 11 sent from an air fan (not shown) into the rotary kiln 1 from the air outlets 8 and 9 or from an independent air fan is sent into the rotary kiln 1. The working air is blown out.
[0023]
In the above configuration, if the combustion air is fed into the rotary kiln 1 from the outlets 8 and 9 while sending the sealing air from the clearance 7, the air is directly supplied to the waste from each of the outlets 8 and 9. Since the waste is sprayed and the waste is stirred, the waste can be incinerated efficiently.
[0024]
In particular, since the flame generated when the waste is burned rises, if the combustion air is blown out from the air outlets 8 and 9, the air comes into contact with the bottom of the waste and burns. Fresh air easily enters the part.
[0025]
In the above description, the outlets 8 and 9 are provided in two places in the refractory material 4, but are not limited thereto. There may be one outlet, or two or more outlets. Regardless of the number of outlets, the combustion air is blown out toward the waste, and it is necessary to efficiently burn the waste while stirring the waste.
[0026]
5 and 6 show another embodiment of the present invention, and the same reference numerals are used for the same parts as those in the previous embodiment.
In this embodiment, a lifter 12 is provided on the circumferential inner surface of the rotary kiln 1 to invert and agitate the waste. The lifter 12 made of the same material as the refractory material 4 is elongated along the length direction of the rotary kiln 1 and has a triangular cross section. A plurality of lifters 12 are provided along the circumferential direction of the rotary kiln 1. Are arranged at regular intervals, and are distributed and arranged within a certain distance range from the opening 2 of the rotary kiln 1.
[0027]
This distance range may be a range of 2/5 × L to 3/5 × L depending on the scale of the rotary kiln 1, and is desirably installed at a position close to the opening 2. For example, in the case of the rotary kiln 1 with a length L = 14 m, the waste is well dispersed in the arrangement in which it is distributed within the range from the opening 2 to 6 m and dispersed at the maximum within the range from the opening 2 to 8 m. And good combustion results were obtained.
[0028]
By setting the inside of the rotary kiln 1 as described above, the thrown-in waste is transferred upward by the lifter 12 along the rotation direction of the rotary kiln 1, and is inverted and dropped. By repeating this, the waste is Since the agitation is performed, the whole waste is incinerated on average, and an efficient incineration effect is obtained.
[0029]
As shown in FIGS. 5 and 6, the lifters 12 are provided at four positions along the circumferential direction of the rotary kiln 1 at equal intervals, and the odd and even rows are provided with a phase shifted by 45 °. Alternatively, the arrangement state of the lifters 12 can be arbitrarily selected.
[0030]
Furthermore, the combustion efficiency of the waste to be reversed and agitated can be increased by sharing the blowout of combustion air from the blowout ports 8 and 9 provided in the refractory material 4 described in the above embodiment and the lifter 12. .
[0031]
In the above description, the waste is incinerated and disposed of. However, in recent years, it has become difficult to secure a landfill site for incineration ash, and landfill itself has become difficult due to pollution problems such as dioxins. Then, incineration ash is melted by raising the incineration temperature with a rotary kiln that can withstand high temperatures. For example, as shown in FIG. 7, slag incinerated and melted in the rotary kiln a is discharged from the outlet k, and granulated slag is generated in a cooling water tank n provided at the lower part of the duct m, and this granulated slag is discarded. It is supposed to be disposed of.
The present invention can also be applied to waste incineration and melting techniques using the rotary kiln 1.
[0032]
【The invention's effect】
As described above, according to the present invention described above, in the incineration using the cocurrent type rotary kiln that supplies the combustion air from the same direction as the input of the waste, the outlet 8 is provided in the refractory material 4 provided in the wind box 3. 9 is formed, and the combustion air is blown toward the waste from the blowout ports 8 and 9, so that the waste is agitated by the blown air and the combustion efficiency can be increased.
[0033]
In particular, since a small amount of sealing air is blown from the clearance 7 formed between the rotary kiln 1 and the refractory material 4, waste, combustion waste gas, or the like flows backward due to the pressure in the rotary kiln 1. In addition, the combustible gas concentration and temperature are maintained in the vicinity of the opening 2 to accelerate ignition and promote thermal decomposition to increase combustion efficiency.
[0034]
In addition, by providing a plurality of lifters 12 for raising, reversing and dropping the waste on the inner circumferential surface of the rotary kiln 1, the waste can be reversed and stirred to increase combustion efficiency. The combustion efficiency of waste can be further increased by sharing the combustion air blown from the blowout ports 8 and 9 formed in the refractory material 4 and the lifter 12.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a rotary kiln type incinerator used in the present invention.
FIG. 2 is a cross-sectional view of a rotary kiln type incinerator used in the present invention as viewed from the opening side.
FIG. 3 is a cross-sectional view of a rotary kiln showing a blowing direction of air blown from a blowing port formed in a refractory material.
FIG. 4 is a transverse cross-sectional view of a rotary kiln showing a blowing direction of air blown from a blowing port formed in a refractory material.
FIG. 5 is a longitudinal sectional view showing another embodiment of the rotary kiln type incinerator used in the present invention.
6 is a cross-sectional view taken along line XX in FIG.
FIG. 7 is a front view schematically showing a conventional rotary kiln type incinerator.
FIG. 8 is a cross-sectional view of a main part of a conventional rotary kiln type incinerator.
FIG. 9 is a cross-sectional view of a conventional rotary kiln type incinerator viewed from the opening side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rotary kiln 2 Opening part 3 Wind box 4 Refractory material 5 Waste inlet 6 Combustion burner 7 Clearance 8 Combustion air outlet 9 Combustion air outlet 10 Waste 11 Combustion air supply path 12 Lifter

Claims (2)

In a method of injecting waste into a rotary kiln that can rotate in the circumferential direction in an inclined state, supplying combustion air, igniting the fuel supplied from the burner, and incinerating the waste, the upper side of the rotary kiln 1 is inclined Combustion air is blown out toward the waste from an outlet formed in the refractory material 4 provided in the wind box 3 surrounding the opening 2 of the air and sealing air is sent from the clearance 7 between the rotary kiln 1 and the refractory material 4. A waste incineration method characterized by the above. In a furnace that injects waste into a rotary kiln that can rotate in the circumferential direction in an inclined state, supplies combustion air, ignites the fuel supplied from the burner, and incinerates the waste, and the upper side of the rotary kiln 1 inclines The refractory material 4 provided in the wind box 3 surrounding the opening 2 is formed with a blowout port through which combustion air can be blown toward the waste and from the clearance 7 between the rotary kiln 1 and the refractory material 4 for sealing. A waste incinerator characterized in that air is blown, and waste is lifted and reversed along the rotational direction of the rotary kiln 1 on the inner circumferential surface of the rotary kiln 1 and a stirrer 12 is provided.

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