JPH02211219A - Waste gas treatment apparatus - Google Patents

Abstract

PURPOSE:To enhance treatment efficiency by providing gas measuring devices to the inlet and outlet of a plasma reactor and mounting a processor which is inputted with the signals from the measuring devices to calculate an actual processing efficiency. CONSTITUTION:The first NOx/SOx measuring device 8a is provided to the inlet part of a plasma reactor 05 while the second NOx/SOx measuring device 8b is provided to the outlet part thereof. The outputs of the NOx/SOx measuring devices 8a, 8b are sent to an processor 9. A program generator 10 receives signals from the processor 9, a combustion apparatus 01 and a setting device 11 and the output thereof is sent to a variable frequency power supply 6. The output of the variable frequency power source 6 is sent to the plasma reactor 05. By this method, predetermined high treatment efficiency is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to boilers, diesel engines, and gas turbine control equipment.

[Conventional technology]

FIGS. 6 and 7 are configuration diagrams showing a conventionally used exhaust gas treatment apparatus for denitrification and desulfurization using glow discharge plasma. An example will be explained in which this device is used to treat NOx in exhaust gas from a combustion device.

In FIG. 6, the exhaust gas generated from the combustion device o1 is passed through the exhaust pipe 02 to the cyclone collector o3 to remove particulates, and then passed through the cyclone collector o3 and the exhaust pipe 04.
and into the plasma reactor o5.

As shown in detail in FIG. 7, the plasma reactor 05 has an electrode 21 provided inside the reaction vessel 09 in contact with the dielectric 2o. Further, an electrode 22 is provided between the dielectric body 2o, and power is supplied between the two electrodes 21 and 22 via a transformer 23 from a power source o6.

In the above configuration, by converting the exhaust gas into plasma, NOx in the exhaust gas is removed according to the following principle. That is, a high voltage of a constant frequency is applied between the electrode 21 and the electrode 22 using the power source 06 to generate glow discharge. The exhaust gas is turned into plasma by the atmospheric pressure glow discharge phenomenon.

For example, NOt causes the following chemical reaction (1), C2).

2NO□→2NO+O, (1) 2NO+Off→Nx+2oz (2) In plasma, high-energy electrons accelerated by an electric field collide with gas molecules, resulting in a mixture of excited molecules, atoms, free radicals, ions, and neutral particles. It is an ionized gas. the above(
In equations 1) and (2), it is thought that NOx, which has obtained an energy of several ev to several tens of ev, becomes a chemically active species and becomes N2 and 0□ as a result of a complex reaction.

Now, as mentioned above, when the exhaust gas of a combustion device is turned into plasma using the atmospheric pressure glow discharge phenomenon, (NO
In a range of approximately ffi/sin, a NOx removal rate of 30 to 40% can be achieved when the plasma generation power, that is, the power supplied from the power source 06 is in the range of several tens of W to several hundreds of W.

Therefore, it is being used as an exhaust gas treatment device for exhaust gas pollution control of various combustion devices such as boilers, gas turbines, and diesel engines.

[Problem to be solved by the invention]

The conventional device described above has the following problems.

(1) Frequency is constant (50Hz or 60Hz)
If so, the exhaust gas treatment efficiency (denitrification and desulfurization efficiency) is low.

(2) Furthermore, when the exhaust gas flow rate decreases, unnecessary glow is generated, which increases the electric power required for exhaust gas treatment.

(3) Due to the reasons (1) and (2) above, it cannot be used as a treatment device for combustion gas with large load fluctuations.

Measures to solve problem C】 The present invention takes the following measures to solve the above problems.

That is, in an apparatus including a plasma reactor that denitrates and desulfurizes exhaust gas generated from a combustion device to be treated by glow discharge as an exhaust gas treatment apparatus, a first NOx, SOx measuring device provided at the inlet of the plasma reactor;
A second NOx, S provided at the outlet of the plasma reactor
An arithmetic unit that inputs signals from the Ox measuring device and the first and second NOx and SOx measuring devices and calculates an effective efficiency signal;
Inputting a setting device for setting the target efficiency, signals from the arithmetic unit and setting device, and an actual load signal from the combustion device,
A program generator that calculates and outputs a control signal with a frequency that makes the actual efficiency equal to the set efficiency, and a variable generator that manually inputs the control signal of the program generator and supplies power to the plasma reactor with a frequency according to the control signal. A frequency power source is provided.

The above means was provided based on the fact that as the frequency of the power source increases, the processing efficiency of the plasma reactor increases to a certain extent.

[Effect]

By the above means, the NOx and SOx concentrations before and after exhaust gas treatment are sent from the first and second NOx and SOx measuring instruments to the computing unit. The arithmetic unit calculates the NOx+SOxOx upstream effective efficiency signal. The program generator receives the target efficiency signal from the setting device, the actual load signal from the combustion device, and the actual efficiency signal from the computing unit, and calculates and outputs a control signal with a frequency that makes the actual efficiency equal to the target efficiency. , input to variable frequency power supply. The variable frequency power source changes the frequency and supplies power to the plasma reactor according to the input control signal.

In this way, NOx is always maintained even if the actual load fluctuates.

The effective efficiency of SOx processing is maintained at the target efficiency.

〔Example〕

An embodiment of the present invention will be explained with reference to FIGS. 1 to 5. FIG. 1 is a block diagram of the configuration, FIG. 2 is a block diagram of the program generator section, and FIGS. 3 to 5 are diagrams for explaining the operation.

Note that the description of the parts explained in the conventional example will be omitted for the sake of redundancy, and the parts related to the present invention will be mainly explained.

In FIG. 1, a first NOx and SOx measuring device 8a is provided at the inlet of the plasma reactor o5. A second NOx and SOx measuring device 8b is also provided at the outlet. NO
X.

The outputs of the SOx measuring devices 8a and 8b are sent to a computing unit 9.

The program generator 10 receives signals from the computing unit 9, the combustion device Of, and the setting device 11, and outputs the output from the variable frequency power supply 6.
send to Further, the output of the variable frequency power supply 6 is sent to the plasma reactor 05.

In the above configuration, the operation will be explained below.

It has been found that the exhaust gas treatment efficiency of the plasma reactor 05 increases as the frequency increases up to a certain frequency, as shown in FIG. 3, depending on the flow rate of the exhaust gas and the frequency of the power source. It was also found that the power consumption is almost proportional to the frequency as shown in FIG. The present example is also notable for the above results.

The computing unit 9 includes first and second NOx and SOx measuring instruments 8
It receives a signal from a+8b and outputs an effective efficiency signal t by calculating the following equations (1) and (2).

(Inlet NOx - Outlet NOx) /Inlet NOx ---
(1) (Inlet 5Ox - Outlet 5OX) /Inlet SOx
---(2) The setting device 11 outputs a preset target efficiency signal r. As shown in FIG. 2, the program generator 10 also generates a target efficiency signal r, an actual efficiency signal, and a combustion device
1 receives the effective efficiency signal S, generates a frequency control signal so that the effective efficiency becomes the target efficiency, and controls the frequency and output of the variable frequency power supply 6. FIG. 5 shows the power consumption curve &'ila of this embodiment and the curve of the conventional example.

As described above, even if the load on the combustion device 01 fluctuates, NOx and SOx are automatically removed at a predetermined high set efficiency.

Note that even if an ammonia injection device for reaction is provided in front of the plasma reactor 05, the system can be operated efficiently as well.

〔Effect of the invention〕

As explained above, the present invention has the following effects.

(1) The conventional constant frequency power supply method had low exhaust gas processing efficiency, but the present invention can achieve extremely high processing efficiency.

(2) A predetermined high treatment efficiency can always be obtained even if the exhaust gas fluctuates.

(3) Power consumption is reduced compared to conventional devices.

(4) Since it works efficiently not only for exhaust gas treatment of general combustion furnaces but also as a large-capacity exhaust gas treatment device, it has high industrial utility value.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the configuration of an exhaust gas treatment device according to an embodiment of the present invention, Fig. 2 is a block diagram of a program generator section of the same embodiment, and Figs. 3, 4, and 5 are the same implementation. FIG. 6 is a block diagram of the configuration of the conventional example, and FIG. 7 is a configuration diagram of the plasma reactor section of the conventional example. Ol... Combustion device, 02--Exhaust pipe, 0
3...-cyclone collector, O4-exhaust pipe, 05...
- Plasma reactor, 06- Power source, 07...- Exhaust gas outlet pipe, 6-- Variable frequency power source, 3a, 8b-4
0x, SOx measuring instrument, 9--operating unit, lO- program generator. Figure 2 Figure 5 Load (%)

Claims (1)

[Claims] In an apparatus including a plasma reactor for denitrifying and desulfurizing exhaust gas generated from a combustion device to be treated by glow discharge, a first NOx provided at an inlet of the plasma reactor;
, an SOx measuring device, a second NOx, SOx measuring device provided at the outlet of the plasma reactor, and an arithmetic unit that inputs signals from the first and second NOx, SOx measuring devices and calculates an effective efficiency signal. and a setting device for setting the target efficiency, and a program generation that inputs the signals of the arithmetic unit and the setting device, and the actual load signal from the combustion device, and calculates and outputs a control signal with a frequency that makes the actual efficiency equal to the set efficiency. and a variable frequency power source that inputs a control signal of the program generator and supplies power at a frequency according to the control signal to the plasma reactor.