JPH10300031A - Method of reducing chlorine organic compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of reducing chlorine organic compounds such as dioxins or the like economically. SOLUTION: In a garbage incineration process using a garbage incineration device which includes an incinerator 16 for incinerating garbage 12, a hopper 15 to supplying combustibles to the combustion furnace 16, a bag filter 21 to remove solid matters in an exhaust gas generated in the combustion furnace 16, an aqueous solution of polyoxyethylene alkylether calcium carbonate is sprayed to the garbage 12, and an aqueous solution containing atoms bonded to chlorine atoms such as calcium in the form of an organic salt is highly dispersed to be introduced into the combustion furnace 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing chlorine-based organic compounds such as dioxins in a refuse incinerator used for incineration of municipal waste and industrial waste.

[0002]

2. Description of the Related Art In recent years, extremely toxic dioxins and other chlorine-based organic compounds have been detected in exhaust gas from incinerators for combustible materials such as municipal waste and industrial waste.
It is a serious problem. Various researches and developments have been conducted on the formation mechanism and suppression technology of these compounds, and some results are being obtained.

[0003] One of them is a technique disclosed in Japanese Patent Application Laid-Open No. 6-66417 (hereinafter referred to as Prior Document 1). That is, when incinerating municipal solid waste or industrial waste, calcium compounds are burned in a combustor (combustion furnace).
It is characterized in that

[0004]

In the prior art disclosed in the above-mentioned prior art document 1, the calcium compound is charged into the combustor in the form of solid particles, so that only the calcium on the surface layer of the solid particles is used for the immobilization reaction. Since it does not contribute, there is a problem that a remarkable effect cannot be obtained unless the input amount is increased.
In other words, according to this conventional technique, in addition to the calcium content contained in the garbage and the like, the molar ratio is equivalent to at least 2.5 times the sum of 1/2 of chlorine and the sulfur contained in the garbage and the like. The effect can be obtained only when a calcium compound is added to the combustor. As described above, the conventional technology requires stoichiometrically excessive calcium to be input to refuse and the like, and is often not very economical in view of the treatment.

The present invention has been made in view of the above points, and provides a method for reducing chlorine-based organic compounds that can economically reduce chlorine-based organic compounds such as dioxins.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a combustion furnace for incinerating combustibles, a combustible material supply means for supplying combustibles to the combustion furnace, and a method for removing solid matter in exhaust gas generated in the combustion furnace. In the incineration process of combustibles using a combustibles incinerator equipped with a dust removing means, an aqueous solution containing an atom capable of binding to a chlorine atom in the form of an organic salt is introduced into the combustion furnace in a highly dispersed state. A method for reducing a chlorine-based organic compound is provided.

In the method for reducing a chlorine-based organic compound according to the present invention, a method of making an aqueous solution containing an atom capable of binding to a chlorine atom in the form of an organic salt highly dispersed includes, for example, spraying the aqueous solution on a combustible material. Alternatively, the aqueous solution can be introduced by accompanying the aqueous solution with water injected into the combustion furnace.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The method for reducing chlorine-based organic compounds according to the present invention is characterized in that atoms capable of binding to chlorine atoms are introduced into a combustion furnace in a highly dispersed state in the form of organic salts. Here, an atom that can be bonded to a chlorine atom means that it is contained in a combustible material such as garbage as a chlorine compound such as chlorine (Cl ₂ ) or hydrogen chloride, or chemically bonded to a chlorine atom generated in a combustion process. (X) that can form a chlorine compound
And specifically, calcium, magnesium, manganese, nickel, silver or the like.

These atoms (X) are dissolved in water in the form of an organic acid salt such as, for example, an organic carboxylate or an organic phosphate. That is, this organic salt is a salt comprising the cation ( ^{Xn +} ) of the atom (X) and the organic anion ( ^Rn- ). As the organic anion, for example,
A carboxylic acid group such as polyoxyethylene alkyl ether carboxylic acid and a phosphate group such as alkyl ether phosphate used for an anionic surfactant can be used. Naturally, the organic anion (R ⁿ⁻ ) preferably does not contain a chlorine atom.

The introduction of an aqueous solution containing an atom (X) capable of binding to a chlorine atom in the form of an organic salt (hereinafter referred to as an organic salt aqueous solution) into a combustion furnace includes, for example, (1) an organic salt aqueous solution Is sprayed on a combustible material before being charged into a combustion furnace, and (2) an organic salt aqueous solution is accompanied by water sprayed for temperature control in the combustion furnace.

In the first method, the above-mentioned organic salt aqueous solution is sprayed on combustibles before being put into a combustion furnace, for example, on dust in a waste pit. Thereby, the atoms (X) capable of binding chlorine are adsorbed dilutely on the surface of the refuse, so that the refuse is put into the combustion furnace after the dispersion state is improved. At this time, after the organic salt aqueous solution is sprayed in the garbage pit, the garbage is thoroughly mixed with the garbage, whereby the effect of reducing the chlorine-based organic compound can be further improved.

[0012] In the second method, an organic chlorine solution is accompanied, that is, dissolved and introduced into the combustion furnace by spraying water supplied into the combustion furnace by a water spray means for controlling the furnace temperature. The method for reducing a chlorine-based organic compound according to the present invention described above is, for example, a combustible incinerator such as a normal refuse incinerator, at least as a combustion furnace, a combustible material supply unit, an air supply unit and a dust removal unit. Applicable to those equipped with a dust collector. As described above, this dust collector is formed by chloride (XCl) generated by the reaction of the above atom (X) with chlorine or hydrogen chloride.
It is necessary to separate and collect incineration ash containing _n ) from exhaust gas. In addition, the combustible incinerator may be provided with a combustible supply unit and a combustion air supply unit, as is generally used.If necessary, a water spray unit for controlling the furnace temperature, a gas cooling unit, and And a boiler for heat recovery. Further, the furnace type of the combustion furnace is not particularly limited, such as a stalker system or a fluidized bed system. Therefore,
The method for reducing chlorine-based organic compounds of the present invention can be easily applied to existing combustible incinerators.

As described above, according to the method for reducing chlorinated organic compounds of the present invention, the chlorinated organic compounds such as dioxins are introduced by introducing the aqueous organic salt solution into the combustion furnace in a highly dispersed state. Significantly reduced. This is supposed to be due to the following mechanism. That is, an atom (X) that can be bonded to a chlorine atom even in a small amount is dissolved in water in the form of an organic salt, and this aqueous solution is highly dispersed in combustibles in a dilute state. The reaction efficiency with chlorine or hydrogen chloride existing in the combustion furnace in a high state is increased, and even a small amount of introduced atoms (X) can efficiently capture chlorine or hydrogen chloride. Chloride, which is a compound formed by the reaction of atom (X) with chlorine or hydrogen chloride, does not decompose even at high temperatures in a combustion furnace, and is almost harmless incinerated ash together with ash generated from combustibles. become. Further, a part of the incinerated ash that has been turned into dust can be removed by a dust collector. On the other hand, the organic anion (R ⁿ⁻ ) which has been combined with the cation (X ^{n +} ) to form a salt is decomposed at a high temperature in the combustion furnace.

It is conceivable that the atom (X) capable of binding to a chlorine atom is converted into an aqueous solution in the form of an inorganic salt. However, considering that the atom (X) is calcium, calcium carbonate (C
aCO ₃ ), calcium hydroxide (Ca (OH) ₂ ), C
aSO _{4 and the} like are not preferable because they are hardly soluble in water. Calcium chloride (CaCl ₂ ) is readily soluble in water, but naturally supplies chlorine to combustibles, which is unsuitable.

[0015]

EXAMPLES Examples of the method for reducing chlorine-based organic compounds according to the present invention will be described below. FIG. 1 is a schematic view showing a fluidized bed type waste incinerator in which an embodiment of the present invention is performed. The waste incinerator 10 shown in FIG. 1 includes a waste pit 13 for temporarily storing waste 12 transported by truck. A crane 14 that transports the refuse 12 is provided in the refuse pit 13.

A waste hopper 15 is attached to the waste pit 13 as waste supply means. Garbage hopper 15
A combustion furnace 16 is provided on the waste discharge side. An exhaust gas transmission pipe 17 for leading out exhaust gas generated in the combustion furnace 16 is connected to an upper portion of the combustion furnace 16. A gas cooling chamber 18 is provided at the downstream end of the exhaust gas transmission pipe 17. A heat exchanger 19 for exhaust heat recovery and a temperature reducer 20 for the purpose of adjusting the temperature of exhaust gas for subsequent equipment (dust collection) are provided downstream of the gas cooling chamber 18. A bag filter 21 that collects and removes incineration ash in the exhaust gas is provided downstream of the cooler 20. An induction blower 23 is connected to the exhaust side of the bag filter 21 via a gas exhaust pipe 22.

On the other hand, combustion air is supplied to the combustion furnace 16 from a plurality of locations on the side and bottom surfaces of the combustion furnace 16 from a forced air blower 24 via an air transmission pipe 25.
Further, a plurality of, for example, two water spray ports 26 are provided at an upper portion of the combustion furnace 16, and water for furnace temperature adjustment is supplied from a gas cooling water tank 28 via a water supply pipe 27, and the water spray ports 26 are provided. Water is sprayed into the combustion furnace 16.

The following Examples 1 and 2 were carried out using the refuse incinerator 10 described above. Example 1 4.8 t of a 5% by weight aqueous solution of calcium polyoxyethylene alkyl ether carboxylate (molecular weight 766) was sprayed in the pit 13 to about 80 t of the incinerated garbage in one day. Burned well mixed day. 80 tons / day of waste incineration, combustion furnace temperature (furnace temperature) about 9
00 ° C, 180-200 ° C inlet temperature of bag filter 21
Driven by Further, in order to control the combustion temperature (furnace temperature), water is sprayed through a water spray port 26 provided at the upper part of the furnace of the combustion furnace 16 for 200 hours.
Sprayed at liter / hr. Under these operating conditions, the exhaust gas was sampled for 2 hours from the sampling hole on the outlet side of the bag filter 21 by a method based on the US EPA method. The collected sample is analyzed by a usual dioxin analysis method (based on concentration / cleanup by manual analysis and quantification by a high-performance gas chromatograph-mass spectrometer) to determine the amount of dioxins (2, 3). Ng-TEQ / Nm ³ ) was calculated in terms of the toxicity value of 7,8-tetrachlorodibenzodioxin. Table 1 shows the results. In addition, before the bag filter 21,
HCl, 50k slaked lime for the purpose of removal, such as SO ₂
g / hr, and the amount of exhaust gas that has passed through the bag filter 21 (dry exhaust gas flow rate) is about 12,000 Nm ³ / h
r.

Example 2 The operation was performed at a waste incineration amount of 80 t / day, a combustion furnace temperature of about 900 ° C., and an inlet temperature of the bag filter 21 of 180 to 200 ° C.
At this time, the water spray port 26 provided in the upper part of the combustion furnace 16
A 5% by weight aqueous solution of calcium polyoxyethylene alkyl ether carboxylate (molecular weight: 766) was sprayed at 200 L / hr together with water sprayed into the combustion furnace 16 for controlling the combustion temperature. Under these operating conditions, exhaust gas was sampled from the sampling hole on the outlet side of the bag filter 21 for 2 hours by a method based on the US EPA method. The collected sample is analyzed by a conventional dioxin analysis method (based on concentration / cleanup by manual analysis and quantification by a high performance gas chromatograph-mass spectrometer), and the amount of dioxins (2, 3) is analyzed. 7,8 in tetrachloro die benzo dioxin toxicity equivalent value, ng-TEQ / Nm ³⁾
I asked. Table 1 shows the results. Before the bag filter 21, slaked lime was added at 50 kg / hr for the purpose of removing HCl, SO _{2 and the} like.
The amount of exhaust gas that has passed through (dry exhaust gas flow rate) is about 12,000.
It was 0 Nm ³ / hr.

Comparative Example 1.3 kg / hr of lime particles and 200 l / water
A test was conducted with the same refuse incinerator 10 as in Examples 1 and 2 under the same operating conditions as in Example 1, except that the sample was introduced into the combustion furnace 16 in h. Example 1 for sampling and analysis
Table 1 shows the analytical values of dioxins obtained by performing
Shown in

[0021]

[Table 1]

As is apparent from Table 1, in the case of Example 1 in which the aqueous solution of calcium polyoxyethylene alkyl ether carboxylate was sprayed on the refuse 12 in the refuse pit 13 and the refuse 12 was charged into the combustion furnace 16, and In the case of Example 2 in which an aqueous solution of calcium polyoxyethylene alkyl ether carboxylate was sprayed into the combustion furnace 16 with water from the water spray port 26, calcium was introduced into the combustion furnace 16 in a highly dispersed state. Therefore, the dioxin concentration can be reduced as compared with the case of the comparative example in which lime particles are introduced into the combustion furnace 16.

[0023]

As described above, according to the method for reducing chlorine-based organic compounds of the present invention, an aqueous solution containing an atom capable of binding to a chlorine atom in the form of an organic salt is placed in a combustion furnace in a highly dispersed state. By introducing, chlorine or hydrogen chloride in combustibles can be fixed as inactive chlorides, and chlorine addition to organic compounds in combustibles can be prevented, so incineration of chlorine-based organic compounds such as dioxins etc. There is an effect that the discharge from the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a fluidized bed type waste incinerator according to an embodiment of the present invention.

[Explanation of symbols]

10: refuse incinerator, 12: refuse, 13: refuse pit,
14 crane, 15 refuse hopper, 16 combustion furnace, 1
7 ... exhaust gas transmission pipe, 18 ... gas cooling chamber, 19 ... heat exchanger, 20 ... temperature reducer, 21 ... bag filter, 22 ... gas exhaust pipe, 23 ... induction blower, 24 ... push-in blower, 25 ... Air transmission pipe, 26: water spray port, 27: water supply pipe, 28: gas cooling water tank.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Yokoyama 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd.

Claims (5)

[Claims] 1. A combustible furnace comprising: a combustion furnace for incinerating combustibles; a combustible supply means for supplying the combustibles to the combustion furnace; and a dust removing means for removing solids in exhaust gas generated in the combustion furnace. In the incineration process of combustibles using a waste incinerator, a chlorine-based organic compound characterized in that an aqueous solution containing atoms capable of bonding with chlorine atoms in the form of organic salts is introduced into the combustion furnace in a highly dispersed state. Method for reducing compounds. 2. The chlorinated organic compound according to claim 1, wherein the aqueous solution is made to be in a highly dispersed state by spraying an aqueous solution onto a combustible material in the form of an organic salt, which is capable of bonding with a chlorine atom. Reduction method. 3. An aqueous solution containing an atom capable of binding to a chlorine atom in the form of an organic salt is introduced into the combustion furnace together with water to be injected, whereby the aqueous solution is in a highly dispersed state. The method for reducing a chlorine-based organic compound according to claim 1. 4. The method for reducing a chlorine-based organic compound according to claim 1, wherein the atom capable of binding to a chlorine atom is at least one selected from the group consisting of calcium, magnesium, manganese, nickel and silver. 5. The method for reducing a chlorine-based organic compound according to claim 1, wherein the organic salt is at least one selected from the group consisting of an organic carboxylate and an organic phosphate.