JP2004243301A - Exhaust gas cleaning device using graphite silica as contact material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system for decomposing and removing dioxins contained in an exhaust gas from a waste incinerator. <P>SOLUTION: Graphite silica 2, which is an ore containing reduced iron, is installed as a contact material in a packed tower 1 and the tower is preheated by the exhaust gas. Water is sprayed in the tower so as to generate high-temperature water vapor. It is confirmed that, in the tower, hydrolysis reaction by the high-temperature water vapor, a far infrared ray effect from the ore, and dechlorination reaction by the iron catalyst are carried out simultaneously and the dioxins contained in the exhaust gas are reduced to about 1/100. Furthermore, although the discharged water from the system contains the dioxins, the amount of the dioxins is very small and can be cleaned with a simple treatment including settling and filtration or the like, so that the water can be recycled. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００８】
【表２】

【０００９】
黒鉛珪石は常温で強力に遠赤外線を放射する物質で、図２の赤外線放射エネルギー測定結果（北海道立工業試験場）に示すように、４．０〜１４．０μｍになだらかなピークを持つ黒体放射ライン（理論上の理想曲線のこと）に近い理想的な遠赤外線放射特性を示し、安定した高い放射率を示す。高温域においてはそれが著しい。
【００１０】
本発明の実施の形態を説明する。一般的に遠赤外線とは０．８〜１０００μｍの波長帯をさすが、黒鉛珪石から放射される波長は図２に示すように２．５〜１４．０μｍに特有な放射帯を持っている。有機物はその構造により固有の吸収スペクトルを持っており、ダイオキシン類もまたその例外ではない。ベンゼン環をつなぐ酸素結合は３μｍの波長に吸収を持ち伸縮振動（ゴム紐のように伸縮すること）を激しくする。一方ベンゼン環に結合している塩素原子は１３〜１７μｍに吸収を持ち変角振動（振り子の様に動くこと）を起こす（化１）。このようにエネルギーを吸収したダイオキシン分子は励起状態に有り反応性が高くなっている。
【００１１】
【化１】

【００１２】
焼却炉から排出される煙は数百度から千度近い温度があり、その熱により黒鉛珪石は高温状態となる。そこに適量の水を散布することにより高温水蒸気を発生させ、ダイオキシン類の加水分解反応を起こし分解する（化２）。
【００１３】
【化２】

【００１４】
黒鉛珪石は鉄を数％含有しており、その鉄は黒鉛の結晶中に取り込まれているため還元状態（第一鉄）になっている。第一鉄は反応性に富み、その触媒効果により脱塩素化反応を起こすことが知られている。ダイオキシンから塩素原子を脱離させることにより、無毒化することができる（化３）。
【００１５】
【化３】

【００１６】
焼却炉からの排煙を充填塔（１）の中に導き、黒鉛珪石（２）の層を通過させる。ノズル（３）は黒鉛珪石（２）充填層の上にあり表面温度を２００〜４００℃程度に保ちつつ黒鉛珪石に付着したダイオキシンを含む煤を洗い流す。そのため黒鉛鉱石の表面は常に清浄に保たれ分解反応は滞る事無く進行する。
【００１７】
煙を水で洗浄することにより排煙中の煤、塩化水素、窒素酸化物、硫黄酸化物も除去できる。
【００１８】
発生する汚水は排水処理施設で処理し循環再利用する。
【００１９】
【実施例】
実際に小型焼却炉の排煙中ダイオキシン類分解実験を行った結果、図３、図４に示すように、充填塔入り口のダイオキシン濃度は３００ｎｇ−ＴＥＱ／ｍ^３Ｎだったが出口では３．９ｎｇ−ＴＥＱ／ｍ^３Ｎに減少していた。さらに汚水に含まれるダイオキシン濃度も２０００ｐｇ−ＴＥＱ／Ｌと激減しており、このことは充填塔内部でのダイオキシン類の分解反応によるものと考えられる。
【００２０】
さらに図５、図６のように異性体分布をみても処理前と処理後では大きくパターンが変わっておりこのことは分解反応を裏づける大きな要因である。
【００２１】
【発明の効果】
以上の様に本発明では従来ダイオキシンを発生しやすいと言われてきた条件を敢えて作り出し（２００〜４００℃の温度を数秒間保持する）、黒鉛珪石の遠赤外線効果、高温水蒸気、触媒作用によりダイオキシン類を分解するという点に大きな特徴を持っている。従来のバグフィルターを用いた処理法に比べ非常に簡易な設備、安価なコストでの提供が可能となる。
【図面の簡単な説明】
【図１】本発明の概略説明図
【図２】赤外線放射エネルギー測定結果
【図３】排煙中ダイオキシン類測定結果
【図４】排水中ダイオキシン類測定結果
【図５】ダイオキシン類異性体分布グラフ（充填塔入口）
【図６】ダイオキシン類異性体分布グラフ（充填塔出口）
【符号の説明】
１ 充填塔
２ 黒鉛珪石
３ ノズル[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention decomposes and removes dioxins in flue gas generated by incineration of combustible waste by simple equipment and method.
[0002]
[Prior art]
The conventional method of treating dioxins in flue gas uses a bag filter by blowing activated carbon, slaked lime, etc. into the flue gas. This involves simply adsorbing and trapping dioxins, without any change in toxicity and requiring new processing equipment and enormous costs for safe processing.
[0003]
[Problems to be solved by the invention]
Accordingly, the present invention is to treat dioxins by causing a decomposition reaction inside a packed tower for purifying flue gas.
[0004]
[Means for Solving the Problems]
The present invention relates to dioxin by high-temperature steam generated by filling graphite silica in a packed tower and heating and spraying the graphite silica with the heat of flue gas, far-infrared rays radiated from graphite silica, and iron catalysis of graphite silica. They are trying to break down classes.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Graphite silica, which is an essential component of the present invention, is a black ore containing carbon mainly composed of silicon oxide, which is produced at the fault crushed part in Pre-Tertiary black hard mudstone, and is a powdery substance with an extremely greasy feeling. It is produced in the form of flakes and breccia.
[0006]
Table 1 shows the composition of the graphite silica ore lumps by the glass bead method (quantitative determination) and the carbon content analysis (Power Reactor Nuclear Fuel Development Corporation), and Table 2 shows the composition of the powder.
[0007]
[Table 1]

[0008]
[Table 2]

[0009]
Graphite silica is a substance that emits far-infrared rays at room temperature, and as shown in the infrared radiation energy measurement result (Hokkaido Prefectural Industrial Testing Laboratory) in FIG. 2, black body radiation having a gentle peak at 4.0 to 14.0 μm. It shows ideal far-infrared radiation characteristics close to the line (theoretical ideal curve) and shows a stable high emissivity. This is remarkable in the high temperature range.
[0010]
An embodiment of the present invention will be described. Generally, far-infrared rays refer to a wavelength band of 0.8 to 1000 μm, but the wavelength radiated from graphite silica has a specific radiation band of 2.5 to 14.0 μm as shown in FIG. Organic substances have unique absorption spectra due to their structures, and dioxins are no exception. The oxygen bond connecting the benzene rings has an absorption at a wavelength of 3 μm and intensifies stretching vibration (stretching like a rubber string). On the other hand, the chlorine atom bonded to the benzene ring has an absorption at 13 to 17 μm and causes bending vibration (moving like a pendulum) (Formula 1). The dioxin molecules that have absorbed energy in this way are in an excited state and have high reactivity.
[0011]
Embedded image

[0012]
The smoke discharged from the incinerator has a temperature of several hundred degrees to nearly 1,000 degrees, and the heat causes the graphite silica to reach a high temperature state. By spraying an appropriate amount of water there, high-temperature steam is generated, causing a hydrolysis reaction of dioxins and decomposing (chemical formula 2).
[0013]
Embedded image

[0014]
Graphite silica contains several percent of iron, and the iron is in a reduced state (ferrous iron) because it is incorporated into graphite crystals. Ferrous iron is known to be highly reactive and to cause a dechlorination reaction by its catalytic effect. Detoxification can be achieved by removing chlorine atoms from dioxin (Chem. 3).
[0015]
Embedded image

[0016]
The flue gas from the incinerator is directed into the packed tower (1) and passes through a layer of graphite silica (2). The nozzle (3) is on the graphite silica (2) packed layer, and rinses soot containing dioxin attached to the graphite silica while maintaining the surface temperature at about 200 to 400 ° C. Therefore, the surface of the graphite ore is always kept clean and the decomposition reaction proceeds without delay.
[0017]
By cleaning the smoke with water, soot, hydrogen chloride, nitrogen oxides and sulfur oxides in the flue gas can also be removed.
[0018]
The generated sewage is treated at a wastewater treatment facility and recycled.
[0019]
【Example】
As a result of actually conducting an experiment for decomposing dioxins in flue gas from a small incinerator, as shown in FIGS. 3 and 4, the dioxin concentration at the entrance of the packed tower was 300 ng-TEQ / m ³ N, but 3.9 ng at the exit. −TEQ / m ³ N. Furthermore, the concentration of dioxin contained in the sewage is also drastically reduced to 2000 pg-TEQ / L, which is considered to be due to the decomposition reaction of dioxins inside the packed tower.
[0020]
Further, as shown in FIG. 5 and FIG. 6, the pattern is greatly changed before and after the isomer distribution in the isomer distribution, which is a major factor supporting the decomposition reaction.
[0021]
【The invention's effect】
As described above, in the present invention, conditions that are conventionally considered to easily generate dioxin are intentionally created (a temperature of 200 to 400 ° C. is maintained for several seconds), and dioxin is produced by the far-infrared effect, high-temperature steam, and catalytic action of graphite silica. It has a great feature in decomposing kinds. Very simple equipment can be provided at a low cost as compared with a processing method using a conventional bag filter.
[Brief description of the drawings]
1 is a schematic explanatory view of the present invention. FIG. 2 is a measurement result of infrared radiation energy. FIG. 3 is a measurement result of dioxins in flue gas. FIG. 4 is a measurement result of dioxins in waste water. (Packing tower entrance)
FIG. 6: Distribution graph of dioxin isomers (outlet of packed tower)
[Explanation of symbols]
1 packed tower 2 graphite silica 3 nozzle

Claims (3)

A method of radiating far-infrared rays from graphite silica to dioxins in flue gas to cause stretching vibration and bending vibration between molecules to accelerate the decomposition reaction. A method in which dioxins are hydrolyzed and decomposed by high-temperature steam generated by sprinkling water on graphite silica heated by flue gas. A method in which chlorine atoms bonded to dioxins are dechlorinated by the dechlorination reaction using iron contained in graphite silica as a catalyst.

Images