JPH04122417A - Exhaust gas treating device - Google Patents

Abstract

PURPOSE:To enhance the treatment efficiency of exhaust gas and also to reduce power consumption by regulating the charge wave-form for plasma generation which is impressed between the electrodes of a plasma reactor to either a pulse charge wave-form or a triangular charge wave-form of high voltage instead of the conventional charge wave-form of a sine wave. CONSTITUTION:Exhaust gas is introduced into a plasma reactor 5 via an exhaust pipe 4 from a cyclone collector 3. A variable power source 16 impresses optimum current, voltage, a charge interval, rising time and a triangular charge wave-form of maximum voltage between the electrodes of the plasma reactor 5 in accordance with a signal equivalent to the optimum degree of removal for the respective components (NOx, N2O, SOx) given from a program generator 10. In other words, this variable power source 16 controls the charge interval (t) of the triangular charge wave-form, the rising time tau and the maximum voltage Vp and sets the optimum value in the relation of power consumption and the degree of removal for NOx, N2O, SOx. The variable power source 16 impressed this optimum value between the electrodes of the plasma reactor 5.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a denitrification and desulfurization method suitable for use in equipment that requires measures against exhaust gas pollution and cleaning, such as boilers, diesel engines, gas turbines, and various combustion equipment. The present invention relates to an exhaust gas treatment device for use in a vehicle.

[Prior Art] This type of exhaust gas treatment apparatus generally employs a method of denitrification and desulfurization using glow discharge plasma. FIG. 5 shows the overall configuration of such a conventional glow discharge plasma type exhaust gas treatment apparatus.

Further, FIG. 6 shows the internal structure of a plasma reactor that forms the center of the exhaust gas treatment apparatus shown in FIG. 5. Here, the operation of the conventional exhaust gas treatment device will be described with reference to FIGS. 5 and 6, taking as an example the case of treating NO8 in the exhaust gas of a combustion device.

Exhaust gas generated from the combustion device shown in FIG. 5 is passed through an exhaust pipe 2 to a cyclone collector 3 to remove particulates. Next, the exhaust gas from which fine particles have been removed in the cyclone collector 3 is introduced into the plasma reactor 5 from the cyclone collector 3 via the exhaust pipe 4. Inside the plasma reactor 5, a first electrode 2] is provided in contact with a dielectric 20. Further, a second electrode 22 is provided between the dielectrics 20 facing each other. Power is supplied between the picture electrodes 21 and 22 from the power source 6 via the transformer 23.

In the above configuration, NO8 in the exhaust gas is removed by turning the exhaust gas into plasma in the plasma reactor 5 according to the following principle. That is, the electrode 2 of the plasma reactor 5]
A high voltage alternating current of a sine wave with a constant frequency is applied between the plasma reactor 5 and the electrode 22 using the power source 6 to generate a glow discharge in the plasma reactor 5. This atmospheric pressure glow discharge phenomenon turns the exhaust gas into plasma, and for example, NO2 causes a chemical reaction expressed by the following equations (1) and (2).

2NO2→2NO+02 ('J, )
N20"N2+I/202 2NO→-〇2→N2+202 (2) In plasma, high-energy electrons accelerated by an electric field collide with gas molecules, resulting in excited molecules, atoms, free radicals, ions, and neutral particles. It is a mixture of ionized gases.''1
In equation (2), several eV to several 10 e
It is thought that N2 and 02 are produced as a result of NO8 having obtained the energy of V becoming a chemically active species and causing a complex reaction.

Now, when the exhaust gas of the combustion device 1 is turned into plasma in the plasma reactor 5 using the atmospheric pressure glow discharge phenomenon as described above, (NO + NO2) in the υ1 gas is 50-200
When the flow rate is approximately ppm and the flow rate is in the range of 300 to 60 C1/min, the plasma generation power, that is, the power supplied from the power source 6 to (the electrodes 21 and 22 of) the plasma reactor 5 is several tens of
In the range of W to several hundred W, a removal rate of 30 to 40% can be achieved. For this reason, the apparatus shown in FIG. 5 is being utilized as a one-of-a-kind gas treatment apparatus for the prevention of exhaust gas pollution in apparatuses involving various combustion devices such as boilers, diesel engines, and gas turbines.

[Problem to be solved by the invention] The conventional 01 gas treatment device described above mainly has the following two problems.
There were two problems.

■ When a normal sine wave AC voltage is applied, especially 50
If the frequency is around the commercial frequency (low frequency) of Hz or 60 Hz, the exhaust gas treatment efficiency (denitration and desulfurization efficiency) is low.

■ Also, even when using high frequency (high frequency charging method),
Since unnecessary glow discharge is generated, the power required for exhaust gas treatment increases.

The present invention has been made in view of the above circumstances, and its purpose is to:
The problem to be solved is to provide an exhaust gas treatment device that can improve exhaust gas treatment efficiency and reduce power consumption.

[Means for Solving the Problems] In order to solve the problems described in item 1, the present invention provides a plasma reactor for denitrifying and desulfurizing exhaust gas by electric discharge (in an exhaust gas treatment apparatus with 6ifs installed, between the electrodes of the plasma reactor It is characterized in that the applied plasma generation charging waveform is a high voltage pulse charging waveform or a triangular charging waveform instead of the conventional sinusoidal charging waveform.

[In the conventional exhaust gas treatment equipment that applies the action sine wave charging method,
As shown in FIG. 2(b), the configuration of the present invention described in 1. According to N08N20., because the pulse charging method or triangular charging method is applied. It becomes possible to apply an instantaneous high voltage to the gas that contributes to the decomposition of SO, and the same de-NO
It becomes possible to reduce the electric power required to achieve x and the removal S08 rate (denitrification and desulfurization efficiency) to 1/3 to 115 of that of the conventional method. Furthermore, in the conventional υI gas processing apparatus, it is now possible to decompose N20 to about 40%, which has been difficult to improve even with high-frequency charging.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an exhaust gas treatment device. Note that the same parts as in FIG. 5 are given the same initial number, the explanation of the parts explained in the [Prior Art] section is omitted to avoid redundancy, and the parts directly related to the present invention are omitted. Explain to the subject.

As shown in FIG. 1, at the entrance of the plasma reactor 5,
NO, N20, . S
o, a first measuring device (No, N, O, SO, IT measuring device) that measures the concentration of (each component to be processed) and outputs a concentration signal (inlet concentration signal) indicating the concentration of each component. vessel)
or may be provided. Further, at the outlet of the plasma reactor 5, No., N20. A concentration signal (outlet concentration signal) that measures the concentration of So and indicates the concentration of each component.
The second 31 instruments (NO8, N, !O, S○8
51 instrument) 8b is provided.

A computing unit 9 is connected to the outputs of the old measuring instruments 8a and 8b. The calculator 9 receives concentration signals output from the total 411 units 8a and 8b, that is, an inlet concentration signal indicating the concentration of each component (No, N20So, By manually inputting the outlet concentration signal, each component (No., N
20. Calculate the removal rate of So,). The output signal of this calculator 9 (ie, NOo in the plasma reactor 5).

A signal indicating the removal rate of N20 So, r is No, .
N20. The program generator 10 outputs the optimum removal rate of each component of So as an output signal. This program generator]0 contains a signal q outputted from the combustion device 1 and indicating the combustion conditions of the combustion device, that is, a signal q indicating air flow rate, fuel flow rate, etc., and a signal q indicating the setting j of the setting device 11, specifically. is also supplied with a signal p indicating the desired removal rate for each component (No, , N20, 5oy).

Thus, the program generator 10 receives a signal p indicating the required removal rate for each component from the setting device 11, a signal q indicating the combustion condition from the combustion device 1, and an actual removal rate for each component from the calculator 9. It receives a signal r indicating the rate and outputs a signal indicating the optimum removal rate for each component, which is preset according to the combination of the signals p, q, and r. The output of this program generator 10 includes a plasma reactor 5
As shown in FIG. 2(a), a variable power source 16 is connected between the electrodes (between electrode 2, not shown in FIG. 6) and electrode 22, which supplies power using a triangular charging method. This variable power supply 16 is
Each component (No, . . .
The optimum current, voltage, charge interval, rise time,
A square charge 1-I waveform of maximum voltage is applied between the electrodes of the plasma reactor 5. In other words, the variable power supply] 6 controls the charging interval t, the standing time τ, and the maximum voltage Vp of the R-angle charging waveform, as shown in the charging waveform explanatory diagram of FIG.
,,N20. An optimal value is set in relation to the So and rate, and applied between the electrodes of the plasma reactor 5.

The results of the above charge control (triangular charge control) are shown in FIG. In this Figure 4, Vl) = 15KV constant, t-50μ
This shows the relationship between the N20 removal rate and the power consumption when 5ec is constant and τ is used as a parameter.For comparison, the relationship between the N20 removal rate and the power consumption when the conventional high-frequency charging method is applied is also shown. be. As is clear from the figure, the exhaust gas treatment equipment that uses the conventional high-frequency charging method cannot achieve a sufficient N20 removal rate even with high power consumption, whereas the exhaust gas treatment equipment that uses the triangular charging control method in Figure 1 cannot achieve a sufficient deN20 rate. Exhaust gas treatment equipment provides sufficient nitrogen removal even with low power consumption.
It can be seen that a rate of 20 is obtained.

Note that the characteristics shown in FIG. 3 are based on the population N of the plasma reactor 5.
20 concentration or 200 ppm.

Although the above description has been made on the assumption that a triangular charging waveform is applied between the electrodes of the plasma reactor 5, similar effects can be obtained by applying a rectangular charging waveform, that is, a pulse charging waveform.

Further, in the above embodiment, a case was explained in which the exhaust gas treatment device of the present invention is applied to the treatment of exhaust gas generated from the combustion device 1, but the exhaust gas treatment device of the present invention is not capable of treating the exhaust gas of a general combustion furnace, and is suitable for large-capacity exhaust gas treatment. It can also be applied as a device for
In this case, it works efficiently as a large-capacity 01 gas processing device, so it has high industrial utility value.

Effects of the Invention] As described in detail below, according to the present invention, the atmospheric pressure glow discharge phenomenon generates V [with a high voltage pulse waveform or triangular waveform between the electrodes of a plasma reactor for converting gas into plasma]. By adopting a configuration in which power is supplied, each component (N
o,,N20. It is possible to apply an instantaneous high voltage that contributes to the decomposition of So, ), and it is possible to significantly improve the processing efficiency of exhaust gas compared to the conventional power supply method using a high frequency sine wave (high frequency charging method). It is possible to reduce power consumption.

]0

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an exhaust gas treatment device according to an embodiment of the present invention, FIG. 2 is a diagram showing a plasma generated charge waveform in the same embodiment compared with a conventional charge waveform, and FIG. 3 is the same. FIG. 4 is a diagram for explaining the plasma generated charge waveform (triangular charge waveform) in the example, FIG. The figure is a block diagram showing the configuration of a conventional υ1 gas processing apparatus, and FIG. 6 is a diagram showing the internal structure of the plasma reactor shown in FIG. 5. 1. Combustion device, 2.4. Exhaust pipe, 3. Cyclone collector, 5. Plasma reactor, 7. Exhaust gas outlet pipe, 8a
, 8b-Measuring instrument (NO,, N20; SOo ma1 measuring instrument),
9... Arithmetic unit, ] 0... Program generator, ] 1... Setting device, 16... Variable power supply, 2] 22... Electrode. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] An exhaust gas treatment device equipped with a plasma reactor for denitrifying and desulfurizing exhaust gas by electric discharge, characterized in that the plasma generation charge waveform applied between the electrodes of the plasma reactor is a high voltage pulse charge waveform or a triangular charge waveform. Exhaust gas treatment equipment.