JPH03275119A - Apparatus for treating exhaust gas with plasma - Google Patents

Abstract

PURPOSE:To easily decompose and remove harmful substances in exhaust gas at a low temp. by placing a dielectric having catalytic function between a discharge electrode and an earthing electrode and generating plasma on the surface of the dielectric. CONSTITUTION:A dielectric 3 having catalytic function is placed between a discharge electrode 1 and an earthing electrode 2 and a high voltage power source 4 is connected to the electrodes 1, 2. Exhaust gas to be treated is passed through the space between the electrodes 1, 2. Harmful substances in the exhaust gas can easily be decomposed and removed at a low temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for treating combustion exhaust gas and other industrial and automobile exhaust gases.

[Conventional technology]

Conventionally, as a treatment method for harmful gases such as NOx and CO contained in exhaust gas, chemical reactions have been caused to cause decomposition using heat or the power of heat and a catalyst, such as in-furnace DeNox or catalytic DeNox.

[Problem to be solved by the invention]

However, the conventional techniques require very high thermal energy and a reaction accelerator such as N1 (3) as shown in the example shown below, and are also quite expensive.

(1) In the case of DeNOx in the furnace, the temperature is 800 to 900°C + NH3 (2) In the case of catalyst DeNOx, the temperature is 400'' Take the following measures.

That is, as a plasma exhaust gas treatment device, a discharge electrode,
A ground electrode facing the discharge electrode, a dielectric having a catalytic function provided between the discharge electrode and the earth electrode, and a high voltage source connected to the discharge electrode and the earth electrode. was made to pass through the space between the discharge electrode and the ground electrode.

[Effect]

When a direct current, alternating current, or pulsed high voltage is applied between the discharge electrode and the earth electrode from a high urine temperature using the above means,
There is a 1-reamer and glow-like corona in the space, and between dielectric materials with catalytic functions such as ceramics and metal oxides,
Each microscopic discharge occurs, and the vicinity of the electrode and the surface of the dielectric material that has a catalytic function become in a plasma state.

Here, when the exhaust gas containing harmful substances is passed through, the high-density plasma near the surface of the dielectric material with a catalytic function decomposes and removes the harmful substances even at low temperatures, and the catalytic function also causes a decomposition reaction. further promoted.

In this way, harmful substances can be easily decomposed at low temperatures.

[Example] A first example of the present invention will be described with reference to FIGS. 1 and 2. A square duct-shaped ground electrode 2 is provided coaxially within the square duct 7 and is grounded.

Further, the inner surface of the earth electrode 2 is covered with a layer of a dielectric material 3 having a catalytic function. The layer of dielectric material 3 having a catalytic function is porous, or formed in the shape of a solid plate or tube using granular or granular sintered plates. Further, on the same axis as the earth electrode 2, spheres with barbs a facing perpendicular to the surface of the earth electrode 2 are arranged at approximately equal intervals, and a wire is connected between them.
will be provided. The discharge electrode 1 is connected to a high voltage power source 4.

8 in the figure indicates a shield.

In the above configuration, when the exhaust gas to be treated flows through the earth electrode 2 and a DC, AC, or pulsed high voltage is applied between the discharge electrode 1 and the earth electrode 2 from the high voltage power supply 4, for example, (1) AC Alternatively, when an alternating pulsed high voltage is applied, a glow-like discharge is generated from the discharge electrode 1 and progresses to the dielectric material 3 having a catalytic function, so that the entire gas passage becomes in a plasma state.

Further, microscopic discharge occurs within the layer of the dielectric material 3 having a catalytic function.

(2) When a negative electrode DC high voltage is applied, reverse ionization of the positive electrode occurs within the three porous dielectric layers having a catalytic function, and a glow-like corona discharge spreads throughout the gas passage. When exhaust gas flows through such a 6U discharge area, harmful substances in the exhaust gas, such as NOx and CO, are removed by high-density electrical energy.
, causing a reaction or decomposition as shown in equation (2),
removed.

2NO->N2+ 02...(1)C
O+-0□→CO2...(2) A second embodiment in which the earth electrode 2a has a cylindrical shape is shown in FIG. The operation is the same as above, so the explanation will be omitted.

A third embodiment is shown in FIG. A rectangular ground electrode 2b which is divided into upper and lower halves is provided coaxially within the duct 7.

Furthermore, rod-shaped discharge electrodes 1a are arranged at approximately equal intervals along the axis of the duct 7, perpendicularly and horizontally to the axis of the duct 7, between the horizontal surfaces of the ground electrodes 2b.

Further, a dielectric plate 3b having a porous catalytic function whose upstream ends are attached to the upper and lower surfaces of the discharge electrode 1a across the discharge electrode 1a, and the interval is gradually decreased toward the downstream side, and the downstream ends are brought into contact and closed.
It has been established. The operation is almost the same as described above, so the explanation will be omitted.

A fourth embodiment is shown in FIG. The interior of the duct 7 is divided into upper and lower layers by three layers of porous dielectric material 3c having a catalytic function, and the wake ends of the upper and lower layers are connected with the same layer of dielectric material having a catalytic function to close the duct. The front end of the middle layer is closed by connecting it with a dielectric material in the same layer that has a catalytic function. Further, a ground electrode 2c having a flat, porous, or fibrous shape is sandwiched or embedded in the dielectric material 3c having a catalytic function. Further, between the ground electrodes 2c, rod-shaped discharge electrodes 1b are provided at approximately equal intervals along the axis of the duct 7, perpendicularly and horizontally to the axis of the duct 7. The operation is almost the same as described above, so the explanation will be omitted.

A fifth embodiment is shown in FIG. A perforated plate or mesh-like ground electrode 2d on a surface perpendicular to the axis of the duct 7, and a perforated plate or mesh-like discharge electrode 1 facing the ground electrode 2d.
c is provided. Further, a granular dielectric material 3d having a catalytic function is provided between the discharge electrode 1c and the earth electrode 2d.

In this case, when a voltage is applied between the discharge electrode 1c and the earth electrode 2d, a small discharge is observed on the surface of the granular dielectric material 3d having a catalytic function, and when the voltage is further increased, a discharge is observed on the entire granular surface. Inside this is...high voltage power supply...shielding material.

...By passing the exhaust gas containing harmful substances through the duct, the exhaust gas can be decomposed.

Claims (1)

[Claims] A discharge electrode, a ground electrode facing the discharge electrode, a dielectric having a catalytic function provided between the discharge electrode and the ground electrode, and a high voltage source connected to the discharge electrode and the ground electrode, A plasma exhaust gas treatment device characterized in that exhaust gas to be treated passes through a space between the discharge electrode and the earth electrode.