JP2771114B2 - Waste incineration method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waste incineration method for incinerating waste such as sewage sludge, municipal waste and industrial waste using a fluidized bed incinerator.

[0002]

2. Description of the Related Art In a conventional waste incineration method using a fluidized bed incinerator, a fluidized bed is formed using silica sand having a particle size of about 0.3 to 0.9 mm as a fluidized medium, and the fluidized medium is heated to 700 to 900 ° C.
In this state, the waste is put into the storage medium and the heat capacity and the stirring action of the fluidized medium can burn even the flame-retardant waste.

However, incineration ash discharged from such a fluidized bed incinerator is a fine particle having a particle size of 100 μm or less, and is liable to generate dust, and has a very low bulk density of 0.5 to 0.8 t / m ^3. It has the drawback that the processing volume is large and it is difficult to handle. This incineration ash is also used for cyclones, electric dust collectors,
Since it is collected by a dust collecting device such as a bag filter and finally disposed of in a landfill, there is a disadvantage that a large amount of cost is required for treating this incinerated ash.

Further, in the conventional waste incineration method using a fluidized bed incinerator, the flow rate in the furnace is limited to about 0.5 to 1.2 m / s due to the fluidized state of the fluidized bed and the height of the fluidized medium. The throughput per unit area of the furnace is determined and it is impossible to increase this throughput.

Further, the fluid medium is vigorously stirred at a high temperature, so that the fluid medium becomes fine due to wear and crushing and is discharged together with the exhaust gas to the outside of the furnace. Therefore, the fluid medium must be periodically replenished from the outside. is there.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, does not generate dust, can effectively use incinerated ash as aggregate, and treats the incinerator in a unit area per unit area. The purpose of the present invention is to provide a waste incineration method which can increase the amount of waste and does not need to periodically replenish the fluid medium from the outside.

[0007]

Means for Solving the Problems To solve the above problems, a waste incineration method according to the present invention is directed to a granulating machine for incinerated ash recovered from exhaust gas of a circulating fluidized bed incinerator for incinerating waste. the granulated to a particle size of 1 to 8 mm, furnace granulated ash
The granulated sintered ash thus obtained is put into a circulating fluidized bed incinerator with an internal flow rate of 4 to 8 m / s and sintered, and the granulated sintered ash obtained in this manner is transferred to a particle-rich portion at the lower part of the circulating fluidized bed incinerator . Circulate
Oh characterized in that used as the fluidized medium Te
You.

[0008]

According to the present invention, useful incinerated ash can be produced by granulating incinerated ash to a particle size of 1 to 8 mm and sintering in a circulating fluidized bed incinerator to obtain granulated sintered ash. At the same time, the granulated sintered ash is circulated to the particle-rich part at the bottom of the circulating fluidized bed incinerator.
And used as a fluid medium. For this reason, dust is not generated unlike the conventional case, and since the granulated sintered ash having a fluidization start speed and a terminal speed higher than that of the conventional silica sand is used as the fluidizing medium, the flow velocity in the furnace is reduced. Conventional 0.5
It can be greatly increased from ~ 1.2 m / s to 4-8 m / s. Therefore, the incineration capacity per unit area can be increased to about five times the conventional value. Further, there is no need to periodically replenish the fluid medium from the outside as in the prior art. Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a circulation provided with a cyclone 14.
It is an annular fluidized bed incinerator, and waste such as sewage sludge is introduced into the furnace through an incineration material inlet 2 and incinerated at 900 to 1100 ° C. by contact with a fluidized medium 3 in the furnace. Exhaust gas is withdrawn from the furnace top, fine ash and coarse sintered by cyclone 14
Separate from the ashes. The exhaust gas containing the fine incineration ash exchanges heat with the air supplied from the blowers 6 and 7 while passing through the first heat exchanger 4 and the second heat exchanger 5, and furthermore, a dust collector. It is led to 8.

The fine incineration ash contained in the exhaust gas is collected and collected by the dust collecting device 8. The collected incinerated ash is granulated by a granulator 9 to form granulated ash having a particle size of 1 to 8 mm, further dried by a drier 10 and put into a furnace through a granulated ash inlet 11. You. The granulated ash charged into the furnace in this manner is sintered at a high temperature of 900 to 1100 ° C. in the furnace to form granulated ash having a uniaxial crush strength of 3 kgf / particle or more.
On the other hand, the large incinerated ash is circulated to the particle dense part at the bottom of the furnace.
In this way, the incinerated ash collected by the dust collecting device 8 is not burned.
Can be 1% or less. Also the particle size distribution
Since it is very narrow, granulation by the granulator 9 can be performed stably.
There are advantages. Granulation and sintering by the action of hot ash particles
Particle concentration at the bottom of the furnace formed by ash and unsintered granulated ash
The agitating action of the part is promoted and the temperature distribution in the furnace is evened.
Stable products with stable properties can be obtained
Becomes This produces granulated sintered ash as raw material
Stabilizes the strength and shrinkage of secondary processed products such as water-permeable blocks
Therefore, an excellent product can be obtained.

In the present invention, this granulated sintered ash is used as the fluid medium 3 as it is. Therefore, there is no need to regularly replenish the fluid medium from the outside as in the conventional case. Further, since the granulated sintered ash having a particle size of 1 to 8 mm was used as the fluidized medium 3, the flow start speed was 1.5 to 3 m / s, and the flow rate in the furnace was stabilized to 4 to 8 m / s, which is 2 to 3 times the flow rate. A fluidized bed can be formed. Therefore, the throughput per unit area of the incinerator can be increased to about five times the conventional value.

At the lower end of the furnace, there is provided a discharge port 13 provided with a discharge amount control valve 12, so that the height of the fluidized bed made of the granulated sinter ash is kept constant. Extract the ash. The granulated sintered Yuihai increases as compared with the conventional and bulk density of 0.8 ~1.2t / m ^3, it is easy to dispose of without generation of dust. In addition, the crushing strength is 3 kgf / particle or more, and the elution stability of heavy metals etc. is high, so it can be used as it is as aggregate for concrete and aggregate for rainwater runoff, etc. Can be used as

The results of incineration of sewage sludge according to the present invention are shown below. For sewage sludge, polymer chemical sludge is dehydrated by a dehydrator.
Dehydrated to 80% was used. The characteristic values are as shown in Table 1.

[0014]

[Table 1] │ │ Moisture │ 80.1% │ │ Flammables in solids │ 79.8% │ │ Ash in solids │ 20.2% │ │ Higher solids Calorific value │4680kcal / kg │ ├────────┼──────┤ │ Ash composition SiO ₂ │42.5% │ │ CaO │ 9.0% │ │ Al ₂ O ₃ │18.4% │ │ P ₂ O ₅ │ 9.7% │ │ Fe ₂ O ₃ │ 9.5% │ │ Others │ 10.9% │ └────────┴──────┘

In this embodiment, a stirring type granulator 9 is used.
3.0% firing aid to increase particle strength during sintering
Add and granulate, then granulated ash 0.5 to 10 mm in particle size
The particles were classified into the respective particle size ranges shown in the table . The granulated ash outside the classification range was pulverized by a pulverizer and returned to the granulator 9 again. Granulated ash contains about 30% moisture in the state after granulation, and if it is put into a furnace as it is, particles are destroyed due to rapid evaporation of moisture, and the recovery rate is reduced. Therefore, in this embodiment, the second heat exchanger 5
Using hot air heated to 200 ° C., drying was performed by a drier 10 until the water content became 3% or less, and then the product was put into a furnace.

The fluidized bed incinerator 1 used was a small furnace having an inner diameter of 0.3 m and a height of 6.5 m, and the incineration amount was 120 to 180 kg / h.
The air ratio was about 1.3 . In addition , LNG (13A) was used as an auxiliary fuel to maintain the temperature of the fluidized bed at a predetermined furnace temperature.

Tables 4 to 6 show the uniaxial crushing strength and the residual particle ratio of the obtained granulated sintered ash. Table 4 and Table 5 shows the case of changing the particle size and furnace velocity sintering temperature (furnace temperature) as 950 ° C., Table 6 by changing the sintering temperature particle size and furnace flow rate as a constant Here is the case. Here, the uniaxial crushing strength indicates an average value of 20 pieces of granulated sintered ash extracted from the furnace bottom. The particle residual ratio is simply calculated by the following equation. Particle residual rate [%] = amount of sintered material [kg / h] / (amount of granulated material-moisture in granulated material-combustible content in granulated material) [kg / h] x 100 Is the discharge per hour when particles are extracted from the furnace bottom so as to keep the height of the fluidized bed constant. In this case, it is supplemented by cyclone 14.
The amount of particles collected is controlled by the circulation amount control valve so that the amount of particles
It was controlled to be 25 kg / s per sectional area. To cyclone 14
Therefore, the fine incineration ash that is not collected is collected in the dust collector 8 (bath) at the subsequent stage.
Dust), but the collected ash is reduced by ignition
The amount was 1% or less. The dust is collected by the dust collector 8 and the furnace
Remove the particles from the downcomer 15 so that the internal circulation amount is constant.
The mixture was granulated by mixing. This mixing ratio is determined in Examples.
Is the downcomer 14 for the ash collected by the dust collector 8?
The extracted particles account for about 5 to 15%. Ignition after mixing
The weight loss is between 1.0 and 1.5% by weight.

[0018]

[Table 2]

[0019]

[Table 3]

The evaluation criteria in the tables in this specification are as follows. Regarding the flow state, ◎ indicates that the whole is flowing uniformly, Δ indicates that a part that does not flow temporarily occurs, and X indicates that the flow state is poor. Regarding the blow-off of the particles, を indicates that the blow-off amount was 5% or less of the amount of the granulated material, Δ indicates 5 to 20%, and x indicates 20% or more. The unconfined crushing strength was evaluated as ◎ when 5 kgf / particle or more, 〇 when 3 to 5 kgf / particle, and × when 3 kgf / particle or less. Regarding the particle residual ratio, ◎ indicates 80% or more, Δ indicates 70 to 80%, and X indicates 70% or less. The comprehensive evaluation was evaluated as ◎ when all of 〜 were, 〇 when there was no X and no 〇 in 〇, and × when there was even one X in 〜.

[0021]

[0022]

[0023]

[0024]

[0025]

[Table 4] ┌─┬─────┬────┬──┬───┬─────┬────┬──┐ │ number │ particle size │ flow rate in furnace │ flow │Particle blowing│Uniaxial crushing │Particle surviving│Overall││No.│ │ │State│Skip│Strength │Ratio │Evaluation│ │ │ mm │ m / s │ │ │kgf / Particle │% │ │ ├─┼── ├─┼── │ │18│0.5 ~ 1.0 │ 4 │ ◎ │ × │ × 1.4 │ × 21 │ × │ │19│1.0 to 2.0 │ 4 │ ◎ │ ◎ │〇 3.6 │〇 76 │〇 │ │20│2.0 to 4.0 │ 4 │ ◎ │ ◎ │ ◎ 7.6 │ ◎ 85 │ ◎ │ │21│4.0 to 6.0 │ │ 4 │ ◎ │ ◎ │ ◎ 14.6 │ ◎ 91 │ ◎ │ │22│6.0 to 8.0 │ 4 │〇 │ ◎ │ ◎ 23.4 │ ◎ 92 │〇 │ │23│8.0 〜10 │4 │ × │ − │ ── │ ── │ × │ │24│10 〜 12 │ 4 │ × │ − │ ── │ ── │ × │ ├─┼─────┼────┼──┼── │ │25│0.5 to 1.0 │ 8 │ ◎ │ × │ × 1.9 │ × 12 │ × │ │26│1.0 to 2.0 │ 8 │ ◎ │ 〇 │〇 3.8 │〇 73 │〇 │ │27│2.0 to 4.0 │ 8 │ ◎ │ ◎ │ ◎ 8.3 │ ◎ 81 │ ◎ │ │28│4.0 to 6.0 │ 8 │ ◎ │ ◎ │ ◎ 15.2 │ ◎ 86 │ ◎ │ │ │ │ 29│6.0 〜 8.0 │8 │ ◎ │ ◎ │ ◎ 25.1 │ ◎ 89 │ ◎ │ │30│8.0 〜10 │8 │ ○ │ ◎ │ ◎ 36.2 │ ◎ 91 │ ○ │ │31│10 〜12 │ 8 │ × │ − │ ── │ ── │ × │ └─┴─────┴────┴──┴───┴─────┴────┴──┘

[0027]

[Table 5] ┌─┬─────┬────┬──┬───┬─────┬────┬──┐ │ number │ particle size │ flow rate in furnace │ flow │Particle blowing│Uniaxial crushing │Particle surviving│Overall││No.│ │ │State│Skip│Strength │Ratio │Evaluation│ │ │ mm │ m / s │ │ │kgf / Particle │% │ │ ├─┼── ├─┼── │ │32│ 2.0〜4.0 │2 │ × │ − │ ── │ ── │ × │ │33│ 2.0-4.0 │ 4 │ ◎ │ ◎ │ ◎ 7.6 │ ◎ 85 │ ◎ │ │34│ 2.0-4.0 │ 6 │ ◎ │ ◎ │ ◎ 7.8 │ ◎ 82 │ ◎ │ │35│ 2.0-4.0 │ 8 │ ◎ │ ◎ │ ◎ 8.3 │ ◎ 81 │ ◎ │ │36│ 2.0 ~ 4.0 │10 │ ◎ │ × │ ◎ 8.9 │ × 31 │ × │ ├─┼─────┼────┼─ ─┼───┼─────┼────┼──┤ │37│ 6.0〜8.0 │2 │ × │ − │ ── │ ── │ × │ │38│ 6.0-8.0 │ 4 │ ○ │ ◎ │ ◎ 23.4 │ ◎ 92 │ ○ │ │39│ 6.0-8.0 │ 6 │ ◎ │ ◎ │ ◎ 24.1 │ ◎ 90 │ ◎ │ │40│ 6.0-8.0 │ 8 │ ◎ │ ◎ │ ◎ 25.1 │ ◎ 89 │ ◎ │ │41│ 6.0-8.0 │10 │ ◎ │ ○ │ ◎ 27.3 │〇 77 │ ○ │ │42│ 6.0-8.0 │12 │ ◎ │ × │ ◎ 28.2 │ × 28 │ × │ └─┴─────┴────┴──┴───┴─────┴────┴──┘

[0028]

[Table 6] ┌─┬─────┬────┬────┬─────┬────┬──┐ │ number │ particle size │ flow rate in furnace │ sintering temperature │Uniaxial crush │Particle remaining│Overall│ │No.│ │ │ │Strength │Ratio │Evaluation│ │ │ mm │ m / s │ ℃ │kgf / particle │% │ │ ├─┼─────┼─── ─┼────┼─────┼────┼──┤ │43│2.0 〜4.0 │5 │ 700 │ × 0.9 │ × 32 │ × │ │44│2.0 〜4.0 │5 │ 800 │ × 1.5 │ × 43 │ × │ │45│2.0 to 4.0 │ 5 │ 900 │ ○ 3.1 │ ○ 73 │ ○ │ │46│2.0 to 4.0 │ 5 │ 950 │ ◎ 7.7 │ ◎ 85 │ ◎ │ │47│ 2.0 〜 4.0 │ 5 │ 1000 │ ◎ 18.8 │ ◎ 86 │ ◎ │ │ 48 │ 2.0 〜 4.0 │ 5 │ 1050 │ ◎ 22.8 │ ◎ 81 │ ◎ │ │ 49 │ 2.0 〜 4.0 │ 5 │ 1100 │ ◎ 15.6 │ ○ 77 │ ○ │ │50│2.0 〜 4.0 │ 5 │ 1150 │ ── │Clinker│ × │ └─┴─────┴────┴────┴─── ──┴────┴──┘

As is apparent from the above Tables 4 6, overall evaluation 〇 next when the 1~8mm for the particle size of the granulated <br/> Tsubuhai, particularly comprehensive when the 2~6mm The evaluation is ◎. When the flow velocity in the furnace was 4 to 8 m / s, the overall evaluation was 〇, and when the flow velocity in the furnace was about 6 to 8 m / s, the overall evaluation was ◎. The sintering temperature is 900 ~
When the temperature is 1100 ° C, the overall evaluation is 〇, especially 950 to 10
When the temperature is 50 ° C., the overall evaluation is ◎.

[0030]

As described above, according to the present invention, no dust is generated unlike the prior art, and since granulated sintered ash is used as a fluidizing medium, incineration per unit area is possible. The capacity can be increased up to about five times the conventional capacity. Further, there is no need to periodically replenish the fluid medium from the outside as in the prior art. Further, according to the present invention , in addition to the above-mentioned effects, the strength of the granulated sintered ash can be further increased.
There is also . Therefore, the present invention is of great value as a waste incineration method that solves the conventional problems.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention .

[Explanation of symbols]

1 fluidized bed incinerator, 2 incineration material inlet, 3 fluidized media,
4 First heat exchanger, 5 Second heat exchanger, 6 Blower, 7 Blower, 8 Dust collector, 9 Granulator, 10 Dryer, 11 Granulated ash inlet, 12 Extraction amount control valve, 13 Outlet 14 cyclone, 15 downcomer

Continuation of front page (56) References JP-A-60-194220 (JP, A) JP-A-64-75809 (JP, A) JP-A-55-102812 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) F23G 5/30 F23J 1/00

Claims (2)

(57) [Claims] An incinerated ash collected from exhaust gas of a circulating fluidized bed incinerator for incineration of waste is granulated by a granulator into 1 to 8 mm particles.
And granulated to a diameter of 4 to 8 m / s.
Was charged into a circulating fluidized bed incinerator with is sintered, furnace granulated sintered Yuihai a circulating fluidized bed incinerator thus obtained
A waste incineration method characterized by being circulated to a lower particle concentration portion and used as a fluid medium. 2. The method according to claim 1, wherein the sintering temperature is 900 to 1100 ° C.
The waste incineration method described.