JP2003285028A - Ash treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ash treatment method capable of removing fly ash having adhered to the inner surface of a retort without interrupting the operation of a rotary drum type heating device. <P>SOLUTION: Fly ash, which is collected by the dust collection facilities of an incinerator such as a stoker or the like or machinery such as a boiler, an air waste heater or the like, is subjected to dechlorination treatment in a heating dechlorination treatment apparatus. Fly ash (a) is subjected to dechlorination treatment in the heating dechlorination treatment apparatus B and, if the value of a meter showing an operation state during dechlorination treatment exceeds a set value, the incineration ash (e) discharged from the bottom of the incinerator is charged in the heating dechlorination treatment apparatus B to be cleaned. After cleaning, the fly ash (a) is re-charged in the heating dechlorination treatment apparatus B. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a thermal dechlorination treatment apparatus to remove fly ash collected by a dust collector of an incinerator such as a stoker type or a fluidized bed type, a boiler and an air preheater. The present invention relates to an ash treatment method for chlorination.

[0002]

2. Description of the Related Art When incinerating general waste such as municipal solid waste or industrial waste including combustibles such as waste plastic in a stoker type or fluidized bed type incinerator, incinerator ash is discharged from the bottom of the incinerator. On the other hand, fly ash is captured by equipment such as a dust collector of an incinerator, a boiler, and an air preheater.

Of these ashes, fly ash, in particular, contains a large amount of dioxins such as organic chlorine compounds harmful to the human body, for example, PCDD (polychlorinated dibenzodioxin) and PCDF (polychlorinated dibenzofuran). It is said that

By the way, conventionally, for example, a fly ash is dechlorinated by using the heating dechlorination apparatus A shown in FIG. The heating dechlorination apparatus A is a fixed quantity supply apparatus 2 including a fly ash storage tank 1, a hopper 3, and a constant quantity feeder 4, and one to several heating pipes (hereinafter referred to as a retort).
7 and a cylindrical heating unit 8, a rotary drum heating device 5, an air heater 6, an exhaust device 9 provided at the outlet of the rotary drum heating device 5, a rotary drum cooler 10, a blower blower 11, a dust collector. 12, an activated carbon adsorption tower 13 and an attracting blower 14.

The fly ash a in the fly ash storage tank 1 is supplied to the rotary drum type heating device 5 by the hopper 3 and the fixed amount feeder 4 of the constant amount supply device 2 and heated by the air heater 6. In the presence of b, while passing through the inside of one or several heating pipes (retort) 7 of the rotary drum heating device 5, it is heated to a predetermined temperature by a cylindrical heating unit 8 located outside thereof.

Dioxins are dechlorinated by thermal decomposition while evaporating the contained water. The dechlorinated ash a ′ is passed through the discharging device 9 and then the rotating drum type cooler 1
It is supplied to 0 and rapidly cooled to become ash a ″ at room temperature.

On the other hand, the exhaust gas d separated by the exhaust device 9
After being diluted with the air b taken in by the blower blower 11, it is supplied to the incinerator (not shown) via the dust collector 12, the activated carbon adsorption tower 13 and the attracting blower 14. Also, the ash a ″ captured by the dust collector 12 is
Returned to hopper 3.

[0008]

However, when the fly ash a is heated by the rotary drum type heating device 5, it adheres to the inner wall surface of the retort 7 and interferes with the dechlorination process. The particle size of fly ash is extremely small (100 μm or less)
It is presumed that the low melting point salts contained in fly ash are the factors.

In any case, if the fly ash a adheres to the inner surface of the retort 7, the heat transfer efficiency is reduced and it becomes difficult to heat the fly ash a to a predetermined temperature. Therefore, if the set temperature is raised in order to heat the fly ash a to a predetermined temperature, power consumption may increase and a situation may occur in which peripheral devices are adversely affected.

The fly ash a adhering to the inner surface of the retort 7 is peeled from the inner surface of the retort 7 when the retort 7 and the cylindrical heating portion 8 on the outer side thereof are hit with a hammer or the like, but the heating device 5 Although it is a low speed, it is rotating at a rotation speed of 3 to 15 rotations per minute, so it is dangerous to approach the heating device 5 during operation.

Therefore, in order to remove the fly ash a adhering to the inner wall surface of the retort 7, it is conceivable that the operation of the rotary drum type heating device 5 is temporarily interrupted, but the operation of the rotary drum type heating device 5 is temporarily stopped. If the operation is interrupted, the operation efficiency will decrease.

The present invention has been made to solve the above problems, and fly ash which can remove the fly ash adhering to the inner surface of the retort without interrupting the operation of the rotary drum type heating device. Its main purpose is to provide a processing method.

[0013]

In order to solve such problems, the present invention is constructed as follows.

(1) When fly ash collected by a dust collection facility of a stoker type or a fluidized bed type incinerator, equipment such as a boiler and an air preheater is dechlorinated by a heating dechlorination apparatus In addition, the fly ash is dechlorinated by the heating dechlorination treatment device, and if the meter value indicating the operating status during this dechlorination treatment exceeds a set value, the heating dechlorination treatment device is set in the incinerator furnace. The ash treatment method is characterized in that incineration ash discharged from the bottom is charged to clean the heating dechlorination treatment device, and after cleaning, fly ash is re-charged to the heating dechlorination treatment device.

(2) In the ash treatment method according to (1), the fly ash operation mode is switched to the cleaning operation mode when the heater current value of the heating dechlorination apparatus exceeds a set value.

(3) The ash treatment method according to (1), characterized in that the incinerated ash discharged from the bottom of the incinerator is crushed into particles having a predetermined particle size or less in advance.

(4) At least 400 to 55 fly ash.
The ash treatment method according to (1) is characterized in that heat treatment is performed at 0 ° C.

(5) In the ash treatment method described in (1), at least fly ash is rapidly cooled at a cooling rate of 40 ° C./min or more, preferably 150 ° C./min or more.

Here, fly ash is a general term for dust ash collected in a dust collection facility of a stoker type or fluidized bed type incinerator, and ash collected in facilities such as a boiler and an air preheater. is there.

On the other hand, the incineration ash means the incineration residue discharged from the bottom of the incinerator. The same effect can be obtained by using molten slag, diatomaceous earth, sand, etc. discharged from a melting furnace or the like instead of incineration ash (furnace bottom ash).

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a heating dechlorination treatment apparatus for carrying out the ash treatment method of the present invention. The heating dechlorination treatment apparatus B is the same as the conventional heating dechlorination treatment apparatus. A fixed amount supply device 2 including an ash storage tank 1, a hopper 3, and a constant amount feeder 4, a rotary drum heating device 5 including an heating heater 8 (retort) 7 and a tubular heating unit 5, an air heater 6, A discharge device 9 provided at the outlet of the rotary drum heating device 5, a rotary drum cooler 10, a blower blower 11, a dust collector 12, an activated carbon adsorption tower 13, and an attracting blower 14.
Is formed by.

However, this thermal dechlorination treatment apparatus B is
An incineration ash storage tank 20 is added above the hopper 3 to store incineration ash (incineration residue discharged from the bottom of the incinerator) e therein. In FIG. 1, 1a and 20a are
It is a feeder.

That is, above the incineration ash storage tank 20,
As shown in FIG. 2, the mesh size of the first 100 mm
Vibrating screen 21, crusher 22, mesh size of about 15 mm
Second vibrating screen 23 is installed, and the incineration ash E discharged from the incinerator (not shown) is separated by the first vibrating screen 21, crushed by the crusher 22, and further the second vibrating screen 23.
Incineration ash storage tank 2 for incineration ash e of 15 mm or less re-sorted by
It is designed to be stored at 0. The first vibrating screen 2
The rubble f remaining at 0 is removed to the outside of the system, and the residue remaining on the second vibrating screen 23 is returned to the crusher 22 and crushed again.

The rotary drum type heating device 5 will be described in detail. The rotary drum type heating device 5, as shown in FIG. 3, has a cylindrical heating portion having a heating means 16 such as a combustion burner or an electric heater. (Hereinafter referred to as heating furnace) 8
And one to several tubes (4 in the figure) provided in the heating furnace 8.
Book) heating tube (hereinafter referred to as a retort) 7, a drive device (not shown) for rotating the retort group, and the retort 7
And a discharge device 9 provided at the outlet of the.

A rotary drum type cooler 10 is provided below the heating furnace 8. The heating furnace 8, the retort 7, and the cooler 10 have a downward slope.

Next, the dechlorination treatment of the thermal dechlorination treatment apparatus B according to the present invention will be described.

The thermal dechlorination apparatus B is normally set in the "fly ash operation mode", and the fly ash a in the fly ash storage tank 1 is supplied by the feeder 1a of the fly ash storage tank 1 in a fixed amount supply device. It is supplied to the hopper 3 of No. 2 and is further supplied to the rotary drum type heating device 5 by the quantitative feeder 4 of the hopper 3.

The fly ash a passes through one or several retorts 7 of the rotary drum heating device 5 in the presence of the air b heated by the air heater 6 for about 3 to 10 minutes. And a predetermined temperature (eg 400 to 550 ° C., preferably 430 to 4
It is heated to 80 ° C. At that time, the water contained in the fly ash a is evaporated, and dioxins are thermally decomposed and dechlorinated. The dechlorinated ash a ′ is discharged to the discharge device 9, and the unburned components in the fly ash a are burned.

The ash a ′ discharged to the discharge device 9 is, for example, 40 ° C./min or more, preferably 150 ° C., in a rotary drum type cooling device 10 so that dioxins are not resynthesized.
The dechlorinated ash a ″ is rapidly cooled at a cooling rate of not less than 1 minute / minute, for example, at 80 ° C. or less, preferably at room temperature.

On the other hand, the exhaust gas d separated by the exhaust device 9
Is diluted by the air b taken in by the blower blower 11 and sent to the dust collector 12. Then, the dust collector 12, the activated carbon adsorption tower 13, and the attracting blower 1
It is supplied to an incinerator (not shown) via No. 4. Further, the ash a ′ captured by the dust collector 12 is fixed in the fixed amount supply device 2
It is returned to the hopper 3 of.

By the way, the rotary drum type heating device 5 is provided with a temperature sensor 17 at its outlet, and when the temperature inside the rotary drum type heating device 5 falls below a set temperature, the "fly ash operation mode" is changed to "cleaning". The operation mode is switched to, the supply of fly ash a is stopped, and the inner surface of the retort 7 of the rotary drum heating device 5 is cleaned with incineration ash e.

That is, after the supply of the fly ash a is stopped, the incinerated ash e in the incinerated ash storage tank 20 is fed to the hopper 3 of the constant quantity supply device 2 by the feeder 20a at the bottom of the incinerated ash storage tank 20.
Is further supplied to the rotary drum type heating device 5 by the constant amount feeder 4 provided at the lower end of the hopper 3.

Then, the incinerated ash e is heat-treated in the same manner as the fly ash a while passing through the retort 7 of the rotary drum type heating device 5, but at the same time, the fly ash attached to the inner surface of the retort 7 is also treated. a is removed. The fly ash removal is probably due to the polishing force of the incinerated ash e, which has a granular shape of about 15 mm or less.

After that, when the internal temperature of the rotary drum type heating device 5 returns to within the set temperature range, the incineration ash storage tank 20
The supply of the incineration ash e from the above is stopped, and the mode is switched to the "fly ash operation mode" again.

As described above, according to the present invention, the fly ash a adhering to the inner surface of the retort 7 of the rotary drum type heating device 5 can be removed without interrupting the operation of the heating dechlorination device B. Is possible.

[0037]

(Example) (Example 1) Thermal dechlorination apparatus B of FIG.
Was used to test the cleaning effect of incineration ash. First, the fly ash a is dechlorinated, and when the temperature inside the retort 7 of the rotary drum heating device 5 falls below the set temperature, the "fly ash operation mode" is changed to the "cleaning operation mode".
After switching to, the inside of the retort 7 returned to within the set temperature range. This confirmed the cleaning effect of incinerated ash.

The operating conditions of the heating dechlorination apparatus B are as follows.

Particle size of incinerated ash: 15 mm or less ・ Water content: 25% ・ Ash heating temperature: 450 ℃ ・ Oxygen concentration: 5% ・ Ash cooling rate: 40 ° C / min or more

[0040]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the fly ash collected by the dust collecting facility of the incinerator such as the stoker type or the fluidized bed type, the equipment such as the boiler and the air preheater is heated and dechlorinated. During the dechlorination treatment by the equipment, the fly ash is dechlorinated by the heating dechlorination treatment equipment, and if the value of the meter showing the operation status during this dechlorination treatment exceeds the set value, the heating dechlorination treatment is performed. The incineration ash discharged from the bottom of the incinerator is put into the chlorination treatment equipment to clean the heating dechlorination treatment equipment, and after the cleaning, the fly ash is put back into the heating dechlorination treatment equipment. It became possible to remove the fly ash adhering to the inner surface of the retort of the rotary drum type heating device without interrupting the operation of the chlorination device.

Since the heat treatment temperature is relatively low, the physical properties of the fly ash hardly change due to melting. Therefore, after the dechlorination treatment, it can be reused as a material such as aggregate or sand.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus for carrying out an ash treatment method according to the present invention.

FIG. 2 is a schematic diagram of a pretreatment means for incinerated ash.

FIG. 3 is a schematic view of a heating dechlorination treatment apparatus.

FIG. 4 is a schematic view of a conventional thermal dechlorination apparatus.

[Explanation of symbols]

a fly ash A, B heating dechlorination equipment e Incinerated ash

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Maaya Itaya             Mitsui Shipbuilding No. 1 Hachiman Kaigan Dori, Ichihara City, Chiba Prefecture             Chiba office (72) Inventor Keizo Hazama             5-6-4 Tsukiji, Chuo-ku, Tokyo Mitsui             Inside the ship company F-term (reference) 3K061 NA01 NA17 NA18                 4D004 AA37 AB07 AC05 CA22 CA32                       CB09 CB31 CB32 CB34 DA02                       DA03 DA06 DA12 DA20

Claims (5)

[Claims] 1. A method for dechlorinating fly ash collected by a dust collection facility of a stoker type or fluidized bed type incinerator, equipment such as a boiler and an air preheater by a heating dechlorination treatment device. , The fly ash is dechlorinated by the heating dechlorination apparatus, and if the value of the meter indicating the operation status during this dechlorination processing exceeds a set value, the heating dechlorination apparatus is in the furnace of the incinerator. An ash treatment method characterized in that the incinerated ash discharged from the bottom is charged to clean the heating dechlorination treatment device, and after the cleaning, the fly ash is re-charged to the heating dechlorination treatment device. 2. The ash processing method according to claim 1, wherein the fly ash operation mode is switched to the cleaning operation mode when the heater current value of the thermal dechlorination apparatus exceeds a set value. 3. The incineration ash discharged from the bottom of the incinerator,
The ash treatment method according to claim 1, wherein the ash treatment method is performed by crushing to a predetermined particle size or less in advance. 4. The ash treatment method according to claim 1, wherein at least fly ash is heat-treated at 400 to 550 ° C. 5. The ash treatment method according to claim 1, wherein at least fly ash is rapidly cooled at a cooling rate of 40 ° C./min or more, preferably 150 ° C./min or more.