JP2000291922A - Waste treatment method and apparatus - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a waste treatment technique for co-firing sludge and waste in an incinerator, the sulfur content that is insufficient to effectively reduce the concentration of dioxins is stabilized. An index for efficiently supplying and controlling the supply amount of the sulfur component-containing powder is provided. SOLUTION: A waste treatment method for co-firing sludge and waste in an incinerator, characterized by supplying a sulfur component-containing powder to a supply line to the incinerator for sludge or waste. Method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for treating waste mixed with municipal solid waste and sludge in an incinerator, and more particularly to a method and apparatus for efficiently reducing dioxins. Regarding the device.

[0002]

2. Description of the Related Art A fluidized bed incinerator is widely used as an incinerator for co-firing sludge with general waste such as municipal solid waste (hereinafter simply referred to as "waste"). FIG. 3 shows a schematic diagram of a representative example. In the fluidized bed incinerator, waste and sludge dewatered cake are put into the furnace 34 from the respective feeders 31 and 32, and dried and ignited by the sand layer flowing by the air sent from below the dispersion plate 38. . The ignited waste is burned in the furnace 34, and after the combustion is completed, the exhaust gas is discharged from the furnace outlet 39 through the exhaust gas treatment device 42 to the chimney 44.
Is released to the outside.

[0003]

As described above, when co-firing waste and sludge, especially organic sludge generated in a sewage treatment process, dioxins are compared with the case where only waste is incinerated according to recent research. It is becoming apparent that the concentration is lower. This is for the following reason.

[0004] Sulfur contained in sludge is present in the furnace as H ₂ S, CS ₂ , COS, SO ₂ , and SO ₃ during the combustion process. These substances have a poisoning effect on copper and similar substances that catalyze the production of dioxins such as dioxin and furan, and can effectively suppress dioxins in the exhaust gas line after the furnace exit from the high-temperature combustion field in the furnace. it can. In addition, the nitrogen contained in the sludge generates ammonia in the combustion process, particularly in a reducing atmosphere in the primary combustion zone, and this reacts with a chlorine compound,
It suppresses the dioxin formation reaction of Cl in the process of dioxin formation. Furthermore, the generation of soot can be reduced by controlling the moisture concentration in the sludge to suppress the combustion reaction rate of combustibles. If the amount of soot generation can be suppressed, the concentration of aromatic organic compounds resulting therefrom will decrease, and as a result, the concentration of dioxin-like substances, which are incomplete combustion products, will also decrease.

[0005] However, when the sludge and the waste are co-fired to suppress the generation of dioxins, it is important to balance the sulfur content, the nitrogen content, the moisture and the like in the sludge. That is, when general waste and sludge discharged in a certain area, for example, in a local government, are mixed, the amount of general waste and sludge discharged in the area becomes a problem.

That is, the ratio of waste and sludge (dewatered cake) generally discharged by humans is about 10: 1 by weight. Among them, general sludge contains a sufficient nitrogen content of about 2 to 10% by dry weight, and the water content can be adjusted in the process of turning sludge into a dewatered cake.
However, the sulfur content is 0.1% by dry weight in general sludge.
Since it is as small as about 2%, there is a problem that the sulfur content is insufficient in order to effectively suppress the generation of dioxins by co-firing sludge and waste. Here, it is very difficult to supply sulfur powder alone into the furnace in order to compensate for the insufficient sulfur content in consideration of uniformity and stable combustion in the furnace. There is also a problem that direct supply of powder into the furnace involves the risk of dust explosion.

[0007] The present invention has been made to solve such problems, and in the treatment of waste mixed with sludge and waste in an incinerator, the combustion state in the furnace is kept constant. Accordingly, it is an object of the present invention to provide a waste disposal method and an apparatus for efficiently reducing dioxins.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on the efficient suppression of dioxins in the treatment of waste in an incinerator, and have obtained the following findings.

In other words, in a waste treatment technology for co-firing sludge and waste in an incinerator, a dioxin concentration is reduced by supplying a sulfur-containing powder to a supply line for sludge or waste to an incinerator. Can be efficiently supplied in a stable state.

Furthermore, stable in order to control the charging amount of the sulfur component-containing powder to realize combustion conditions inside the furnace as an indicator for determining the combustion conditions in the furnace, the furnace outlet or the predetermined range SO _X concentration in the chimney By maintaining the content within the range, the effect of suppressing dioxins is further improved.

The present invention has been made based on such knowledge, and is characterized by having the following configuration.

That is, the present invention provides a method for treating waste in which incineration sludge and waste are co-fired, wherein a powder containing a sulfur component is supplied to a supply line of sludge or waste to the incinerator. To provide waste disposal methods.

[0013] In the processing method of the waste described in (1), a furnace, the SO _X concentration is measured in the furnace outlet or chimney, controlling the supply amount of the sulfur-containing powder on the basis of the measured value And a method for treating waste.

In the method for treating waste described in (2), the concentration of SO _X in the chimney is 50 to 400 ppm.
It is preferable to control the supply amount of the sulfur component-containing powder so that

In the method for treating waste according to any one of (1) to (3), the incinerator is preferably a fluidized bed furnace.

Further, the present invention provides a waste treatment apparatus for co-firing sludge and waste in an incinerator, comprising a supply device for supplying a sulfur component-containing powder to a supply line to the incinerator for sludge or waste. The present invention provides a waste treatment apparatus characterized in that:

The waste treatment apparatus described in (5)
And SO in furnace, furnace outlet or chimney _XS to measure concentration
O_XConcentration meter, containing the sulfur component based on the measured value
And a control device for controlling a supply amount of the powder.
To provide a waste treatment apparatus.

[0018] In the processing apparatus of the waste described in (6), said SO _X concentration in the chimney 50~400ppm
It is preferable to control the sulfur component-containing powder so that

Further, in the waste treatment apparatus described in any one of (5) to (7), it is preferable that the incinerator is a fluidized bed furnace.

Here, the "supply device for supplying the sulfur component-containing powder" described in (5) is connected to the sulfur powder storage tank and the sludge supply line or the sulfur powder storage tank and the waste supply line. Refers to a sulfur powder supply line.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the waste treatment technology according to the present invention, dioxin concentration can be effectively reduced by supplying a sulfur component-containing powder to a supply line to a sludge or waste incinerator. It is possible to efficiently supply the insufficient sulfur content in a stable state.

A sulfur component supply line for supplying the sulfur component-containing powder is connected to a sludge supply line or a waste supply line to the incinerator, and the sulfur component-containing powder is mixed with the sludge or waste and supplied into the furnace. By doing so, a mixture comprising sulfur powder and sludge or waste can be supplied into the furnace with uniform properties. In addition, it is possible to avoid the inhomogeneity in the furnace and the danger of dust explosion, which are caused by directly supplying only the sulfur component-containing powder into the furnace. During the operation, the supply operation of the sulfur content can be started and ended simultaneously with the start and end of the supply of the sludge or the waste, so that the simplicity and safety of the operation are established. Further, since the sulfur content, the nitrogen content, and the water content are sufficiently supplied into the furnace, dioxins are efficiently reduced for the above-described reason.

At this time, the concentration of SO _X in the exhaust gas at the furnace, at the furnace outlet or in the stack is determined by the combustion conditions such as the furnace temperature, the amount of the sulfur component-containing powder supplied to the sludge supply line or the waste supply line, and the like. Therefore, it can be used as a standard for dioxin production. In other words, the furnace to monitor the SO _X concentration value, by performing the combustion by adjusting the SO _X concentration in the reactor outlet or chimney in a predetermined range, determining the sulfur component-containing powder content to realize stable combustion conditions Harmful gases such as dioxins can be efficiently suppressed.

[0024] In order to achieve this, the furnace, the furnace outlet or chimney need only install the SO _X concentration meter, a special modification or the like unnecessary, it is possible to inexpensively realize.

Hereinafter, a more detailed description will be given with reference to the drawings. However, the present invention is not limited to these.

FIG. 1 shows an example of a waste disposal apparatus according to the present invention. This treatment apparatus includes a waste storage tank 1, a sludge storage tank 2, a sulfur powder storage tank 3, and an incinerator 4, and further includes a waste storage tank 1 between the waste storage tank 1 and the incinerator 4. Tank 1
A waste supply line 5 for supplying the waste in the incinerator 4 is connected to the incinerator 4, and between the sludge storage tank 2 and the incinerator 4, the sludge in the sludge storage tank 2 is supplied to the incinerator 4. Of the sulfur powder storage tank 3 and the sludge supply line 6, the sulfur powder in the sulfur powder storage tank 3 is incinerated with the incinerator 4.
And a sulfur powder supply line 7 for supplying the sulfur powder.

In this example, the sludge in the sludge storage tank 2 is pumped from the sludge storage tank 2 to the incinerator 4 through the sludge supply line 6 by a pump (not shown). At this time, the sulfur powder fed from the sulfur powder storage tank 3 is supplied to the sludge supply line 6.
The sludge is mixed with the sulfur powder while being conveyed downstream, and is supplied to the incinerator 4 with uniform properties.

With such an arrangement, non-uniformity in the furnace and danger such as dust explosion, which are generated by directly supplying only sulfur powder into the furnace, can be avoided. Dioxins can be efficiently reduced while maintaining the balance of nitrogen, nitrogen and moisture. Also, during the operation, the supply operation of sulfur can be started and ended together with the start and end of the supply of sludge, and the simplicity and safety of the operation are established.

However, in the present invention, the sulfur content supplied to the sludge supply line is not limited to a powdery one.
If it is a sulfur component-containing material, for example, a slurry-like material can be suitably used.

Further, in this figure, an example is shown in which the sulfur powder supply line is connected to the sludge supply line, but it is also possible to connect the sulfur powder supply line to the waste supply line.
In this case as well, the waste and the sulfur powder are mixed and supplied to the incinerator with uniform properties, and the same effect as in the above case is produced. Further, as a simpler method than the method shown in this example, the same effect can be exerted by supplying sulfur powder to a water supply line for furnace temperature control, a waste sewage supply line, or the like.

FIG. 2 shows another example of the waste disposal apparatus according to the present invention. This treatment apparatus includes a waste storage tank 11, a sludge storage tank 12, a sulfur powder storage tank 13, and a fluidized bed incinerator 14, and an exhaust gas treatment apparatus 22 is connected to the incinerator 14, A chimney 24 is connected to the device 22. Further, a waste supply line 15 for supplying the waste in the waste storage tank 11 to the incinerator 14 is communicated between the waste storage tank 11 and the incinerator 14, and the sludge storage tank 1
2 and an incinerator 14, a sludge supply line 16 for supplying sludge in the sludge storage tank 12 to the incinerator 14 is communicated, and a sulfur powder storage tank 13 and a sludge supply line 16 A sulfur powder supply line 17 for supplying the sulfur powder in the powder storage tank 13 to the incinerator 14 is connected.
An SO _X concentration meter 20 is attached to the chimney 24, and a concentration detection signal from the SO _X concentration meter 20 is input to a control device or an instrument 21.

In this example, as described above, the sulfur component-containing powder supplied to the sludge supply line 16 is sufficiently mixed with the sludge in the sludge supply line 16 to be supplied to the incinerator 14 with uniform properties. . The sludge and the waste supplied from the waste storage tank 11 through the waste supply line 15 are dried and raised by the sand layer flowing by the air sent from the wind box 25 below the dispersion plate 18. It is heated and ignites. The ignited waste burns in the freeboard section,
The combustion is completely completed. The exhaust gas is discharged from the chimney 24 to the outside via the exhaust gas treatment device 22. Based on the concentration detection signal from the SO _X concentration meter 20 installed in the chimney 24, the supply amount of the sulfur component-containing powder is determined by the control device or the instrument 21 so that the SO _X concentration in the chimney falls within a predetermined range. You. Specifically, if the SO _X concentration is too low, the supply amount of the sulfur-containing powder is increased,
If such O _X concentration is too high reduces the supply amount of the sulfur component-containing powder.

In the present invention, the preferred SO _X concentration of the chimney is 50 to 400 ppm. If the SO _X concentration in the chimney is less than 50 ppm, the effect of controlling dioxins is not sufficient, and if it exceeds 400 ppm, the SO _X concentration cannot reach the regulated value.

[0034] By such white smoke preventing air from the chimney upstream is joined to the exhaust gas line as shown in FIG. 2, if that impact SO _X concentration in the chimney, for example, oxygen 12% conversion, etc. And the concentration may be considered. Also, if you are automatic control, it may be added to the value of the SO _X concentration in the operating parameters.

In this example, the SO _X concentration meter is installed in the chimney. However, the SO _X concentration meter is installed in the furnace 14 or the furnace outlet 19 so that the SO _X concentration in the furnace or at the furnace outlet is within a predetermined range. Preferably, in any case, the supply amount of the sulfur component-containing powder can be controlled so as to be 60 to 600 ppm. In this figure, an example in which a fluidized bed incinerator is used as an incinerator is shown. However, the present invention is not limited to this, and the invention can be applied to a grate incinerator and the like.

[0036]

As described above, according to the present invention, in the treatment of waste in which waste and sludge are co-fired in an incinerator, sulfur powder for supplementing the sulfur concentration that is effective in reducing dioxins is provided. It can be supplied stably and efficiently.

In the furnace, at the furnace outlet or in the chimney,
_Since the combustion state in the furnace can be determined based on the _X concentration, it is possible to determine the supply amount of the sulfur component-containing powder that realizes stable combustion conditions for more efficiently reducing dioxins.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a waste treatment apparatus according to the present invention.

FIG. 2 is a schematic view showing another example of the waste disposal apparatus of the present invention.

FIG. 3 is a schematic diagram showing a typical example of a conventional fluidized bed furnace.

[Explanation of symbols]

1,11 ... waste storage tank, 2,12 ... sludge storage tank, 3,
13: sulfur powder storage tank, 4, 34: fluidized bed incinerator,
5, 15 ... waste supply line, 6, 16 ... sludge supply line, 7, 17 ... sulfur powder supply line, 14, 34 ... fluidized bed incinerator, 18, 38 ... dispersion plate, 19, 39 ... furnace outlet, 20: SO _X concentration meter, 21: control device or instrument, 2
2, 42: exhaust gas treatment device, 23, 43: white smoke prevention blower, 24, 44: chimney, 25: wind box

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F23G 5/50 ZAB F23G 7/00 ZAB 7/00 ZAB 102B 102 B09B 3/00 303J (72) Inventor Akiyama Hajime Hajime 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. F-term (reference) 3K062 AA11 AB01 AC01 AC02 BA02 BB01 BB04 CA05 CB08 DA26 DA40 DB30 3K065 AA11 AB01 AC01 AC02 BA05 BA07 BA10 CA04 4D004 AA02 AA46 AB07 CA28 CA42 CB01 CB42 CC02 CC20 DA01 DA02 DA03 DA10 DA12 4D059 AA03 BB01 BB13 BB18 CA14 CB01 DA70 EA09 EB09 EB11

Claims (8)

[Claims] Claims: 1. A method for treating waste, in which sludge and waste are co-fired in an incinerator, comprising supplying a sulfur component-containing powder to a supply line to the incinerator for sludge or waste. Processing method. 2. The method for treating waste according to claim 1, wherein the SO _X concentration in the furnace, at the furnace outlet or in the chimney is measured, and the supply amount of the sulfur-containing powder is controlled based on the measured value. A method for treating waste. 3. The method for treating waste according to claim 2, wherein the concentration of SO _X in the chimney is 50 to 400.
A method for treating waste, comprising controlling a supply amount of the sulfur component-containing powder so as to become ppm. 4. The method for treating waste according to claim 1, wherein said incinerator is a fluidized bed furnace. 5. A waste treatment apparatus for co-firing sludge and waste in an incinerator, comprising a supply device for supplying a sulfur component-containing powder to a supply line to the incinerator for sludge or waste. Waste treatment equipment. In the processing apparatus 6. A waste according to claim 5, the furnace, the SO _X concentration meter for measuring the SO _X concentration in the reactor outlet or chimney, the sulfur component-containing powder on the basis of the measured value And a control device for controlling a supply amount of the waste. In the processing apparatus according to claim 7 wastes according to claim 6, wherein said SO _X concentration in the chimney 50 to 400
A waste treatment apparatus characterized in that the supply amount of the sulfur component-containing powder is controlled so as to be ppm. 8. An apparatus for treating waste according to claim 5, wherein said incinerator is a fluidized bed furnace.