JP2839028B2 - Desulfurization and denitrification method and desulfurization and denitrification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention is thermal power plants BACKGROUND OF THE INVENTION, steelworks, relates rid general sulfur dioxide SO ₂ contained in the exhaust gas discharged from the plant and nitrogen compounds NO _X at the same time low-temperature plasma method, more Speaking of which, installing a condenser in a low temperature plasma reactor improves desulfurization and denitrification efficiency, prevents low temperature corrosion, expands the operating temperature range, saves operating costs, reduces the amount of secondary wastewater, and makes the reactor smaller. TECHNICAL FIELD The present invention relates to a desulfurization and denitrification method for the purpose of effecting gasification.

[0002]

2. Description of the Related Art FIG. 1 is used for convenience in describing a low-temperature plasma method used in a conventional desulfurization and denitrification method. The conventional method shown in FIG. 1 uses a low-temperature plasma reactor to remove sulfur dioxide and nitrogen compounds in exhaust gas through the following steps.

1) The exhaust gas discharged from an industrial boiler is supplied to a reactor 2 after the temperature of the exhaust gas is reduced to 110 ° C. or less by a heat exchanger 1 provided before entering the plasma reactor. 2) Further, the temperature of the exhaust gas in the reactor 2 is reduced to 80 ° C. or less by spraying water through the spray nozzle 4. 3) A high-voltage pulse power is supplied by a pulse power generator 5 to both poles of a plasma electrode rod having a structure similar to an industrial dust collector composed of a plasma electrode rod and a dust collecting plate. At this time, a streamer corona is generated at both poles, and at the same time, the space inside the reactor is filled with a collection of strong electrons. 4) The electron group in the reactor 2 collides with oxygen, water vapor, nitrogen, etc., which are the main constituent molecules of the exhaust gas, to form radicals having strong oxidizing power. The various constituent molecules serve to convert sulfurous acid gas and nitrogen compounds into aerosol-like acidic salts. 5) The aerosol of the acidic salt reacts with the ammonia injected into the reactor during the grain growth to become a particulate neutral salt having a diameter of 1 μm and is collected by the electrostatic precipitator 6.

An important factor that determines the operating power of desulfurization and denitrification by the conventional low-temperature plasma method is the production process of acidic salts and neutral salts, and is supplied to a reactor in order to increase the efficiency of the production process. The temperature of the exhaust gas was controlled by a heat exchanger provided on the inlet side of the reactor and water spray in the reactor.
Either cool below 0 ° C or allow the sprayed water to absorb the salt.

[0005]

However, when the operating temperature of the exhaust gas is reduced to 80 ° C. or less and supplied to the reactor by the above-mentioned conventional method, 1) the sulfurous acid gas changes to sulfuric acid, which promotes low-temperature corrosion of the reactor. . 2) There is a problem in that the energy cost for lowering the temperature of a large amount of exhaust gas through a heat exchanger disposed in front of the reactor is large.

In the case of promoting the formation of salt in a reactor that sprays water through a spray nozzle, 1) the distribution of the sprayed water becomes uneven, and the distribution of the generated salt is ubiquitous in space; ) Water supply stop due to corrosion of spray nozzle, 3) Corrosion of reactor caused by scattered droplets,
4) Secondary spray water is generated by spraying water, and 5) If spray is used, the volume of the reactor must be increased.

Accordingly, an object of the present invention is to eliminate low temperature corrosion, reduce the required power for operation, and eliminate the generation of secondary wastewater.
An object of the present invention is to provide a desulfurization and denitrification method which is excellent in desulfurization and denitrification efficiency and has a low running cost.

[0008]

In order to solve the above-mentioned problems of the conventional method, the temperature of the exhaust gas is lowered through a heat exchanger, and instead of spraying water into the reactor, as shown in FIG. In order to perform desulfurization and denitrification using a low temperature plasma reactor having a condenser inside the reactor.

By using the desulfurization and denitrification method and apparatus according to the present invention, the exhaust gas discharged from an industrial boiler or the like can be
If supplied directly to the low-temperature plasma reactor 2, the moisture in the exhaust gas supplied to the reactor 2 is condensed on the surface of the condenser 9 provided in the reactor, and this condensed droplet or liquid film causes Salt generation and exhaust gas neutralization occur. On this occasion,
As the condenser, a circulating cooler to which the cooling water is continuously supplied from the cooling water supplier 10 is used.

The conditions required for the condenser used in the low-temperature plasma reactor used in the present invention are as follows.

[0011] 1) The cooling pipe of the condenser should have a large contact area with the exhaust gas passing through the reactor, and be sized according to the cross section of the reactor so that the water can be sufficiently condensed. 2) A condenser is provided downstream of the exhaust gas flow of each plasma electrode rod of the reactor. One set of the plasma electrode rod and the condenser is referred to as one unit. 3) Depending on the size of the reactor, a plurality of units can be provided in the reactor in multiple stages.

When the reactor size is large, the desulfurization and denitrification performance improves as the number of condensers increases. Therefore, the size and the number of units of the condenser must be appropriately arranged according to the target processing capacity.

It should be noted that the arrangement is such that the total temperature of the exhaust gas supplied into the reactor is lowered by several tens of degrees or more, for example, the size of the condenser is too large, the number of units is too large, or the amount of cooling water is too large. If the amount is too large, improvement in low-temperature plasma desulfurization and denitrification performance cannot be expected. Further, depending on the arrangement of the cooling pipes of the condenser, the pressure loss of the passing exhaust gas increases and the economic efficiency decreases.

In order to avoid such a disadvantage, the internal temperature of the reactor is prevented from lowering to 110 ° C. or less, and the pressure loss is prevented from exceeding 100 mmA so that the water in the exhaust gas can be condensed. Container size, number of units,
It is desirable to appropriately adjust the amount of cooling water and the like.

Unlike the conventional low-temperature plasma reactor (FIG. 1) in which the cooling spray is provided in front of the plasma electrode rod, in the present invention, the condenser is provided behind the plasma electrode rod. This is because electrons generated from the plasma electrode rod change sulfurous acid gas and nitrogen oxide into acidic salts, and then contact these acidic salts with a condenser to change them into neutral salts. That is, if the condenser is provided in front of the plasma electrode rod, the condenser does not come into contact with the acid salt, and the meaning of the condenser for converting the acid salt to the neutral salt is lost. The advantages of the desulfurization and denitrification method according to the present invention as described above are as follows.

1) Conventionally, a heat exchanger at the front end of the reactor and a spray system have been used to promote the formation of salt. However, in the method according to the present invention, this function is performed only by the condenser inside the reactor. And the process can be simplified. 2) In the present invention, the role of the condenser is not to reduce the temperature of the exhaust gas, but to condense the moisture in the exhaust gas on the cooling pipe. Therefore, the operating temperature of the reactor can be reduced from the conventional 80 ° C. or lower to 110 ° C. or higher, and low-temperature corrosion of the reactor constituent material can be effectively prevented. 3) Since the salt absorption reaction occurs in droplets or liquid films uniformly distributed on the surface of the condenser, the removal efficiency is improved. 4) In the method and apparatus according to the present invention, no water is supplied to the reactor, so that no secondary wastewater is generated. 5) In the apparatus according to the present invention, it is easy to reduce the volume of the reactor. 6) The rate of desulfurization and denitrification is remarkably improved as compared with the conventional method.

The desulfurization and denitrification apparatus used in the above-mentioned desulfurization and denitrification method can be used in a device having a structure in which exhaust gas is passed from the low-temperature plasma reactor to an electric dust collector to perform desulfurization and denitrification. The low-temperature plasma reactor includes a low-temperature plasma reaction vessel, a plasma electrode housed therein, and a condenser for cooling and coagulating water contained in exhaust gas.

At this time, the plasma electrode rod and the condenser as a cooler are arranged in series in the low-temperature plasma reactor along the flow of the exhaust gas. It is particularly preferred to form a stream in which the exhaust gas is first brought into contact with the plasma electrode rods and then into contact with a condenser which is a cooler. When the exhaust gas is alternately and repeatedly contacted with the plasma electrode rod and the condenser as the cooler, higher desulfurization and denitrification efficiency can be enhanced.

Furthermore, it is possible to adjust and use the arrangement and number of the plasma electrode rods and condensers as appropriate in consideration of the characteristics of the treated exhaust gas, the amount of treatment, and the like. As the electric precipitator used here, those generally used for industrial purposes can be used.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method according to the present invention will be described below in more detail with reference to embodiments that are considered to be optimal.

[0021] First Embodiment: This embodiment, NO by condensation phenomenon of the plasma reactor employing the method according to the present invention prior to fabrication of the plasma desulfurization denitrification pilot plant _X
A small reactor was prepared and an experiment was conducted with the focus on the removal performance. FIG. 3 is a cross-sectional view of the reactor 2 viewed from above so that the arrangement of the cooling pipe 9 that contacts the exhaust gas can be seen.

[0022] comparing the NO _X removal rate of the case where the plasma reactor is not equipped with a condenser and a case having the above-mentioned condenser. Comparison condition, the exhaust gas flow rate is carried out at an initial NO _X concentration 200 ppm, pulse repetition rate 60 Hz, under the conditions of pulse width 1000nsec small plasma reactor 20 Nm ³ / h. The results are as shown in FIG.

As shown in FIG. 4, when the condenser is provided in the plasma reactor, the NO.
_X removal rate is much higher, if no condenser also Maximizes 50kV an added voltage to the reactor has resulted in NO _X removal rate is only on the level of 15%. That is, it can be seen that can result from the case NO _X removal rate improved considerably to provide a condenser plasma reactor.

Second Embodiment Here, the desulfurization and denitrification effects of a case where a reactor having a condenser according to the present invention is used and a case where a plasma reactor without a condenser according to the present invention is used are compared. .

The results of a comparison between a plasma desulfurization and denitrification pilot plant with a condenser (invention) and a conventional pilot plant without a condenser (data from the Italian National Electric Power Company) are shown in Table 1. Was as shown in FIG.

[0026]

[Table 1]

As can be seen from Table 1, the efficiency of desulfurization and denitrification in the plant according to the present invention provided with the condenser when the same voltage is supplied is higher than that in the conventional plant without the condenser. , The power required for operation was low, and the operating temperature was high, so that low-temperature corrosion of the reactor could be prevented.

[0028]

By using the low-temperature plasma reaction method and the reactor according to the present invention, it is possible to prevent low-temperature corrosion occurring in the conventional apparatus, extend the life cycle of the apparatus, and reduce unnecessary energy costs. Running costs can be reduced. In addition, the reactor according to the present invention does not use exhaust gas cooling water, so that secondary wastewater does not occur and is excellent in terms of environmental protection.

[Brief description of the drawings]

FIG. 1 is a drawing showing a conventional low-temperature plasma reactor.

FIG. 2 is a view showing a low-temperature plasma reactor according to the present invention.

FIG. 3 is a cross-sectional view of a low-temperature plasma reactor according to the present invention.

FIG. 4 is a graph showing experimental results according to the present invention.

[Explanation of symbols]

 1: Heat exchanger 2: Low-temperature plasma reactor 3, 3 ': Plasma electrode rod 4: Spray nozzle 5: Pulse power generator 6: Electric dust collector 7: Exhaust gas inhaler 8: DC power generator 9: Condenser (Cooling pipe) 10: Cooling water feeder

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shen-Han, Korea 103 No. 202, 103, 5 Ue-sung Apartment, Sejong-gu, Cheongju-si, Chungcheongbuk-do, South Korea No. 202 Wing No. 401 (72) Inventor Zhang Jihong 158-2 Masade Apartment 2158, Yongde 2-dong, Aiwon-gu, Masan-si, Gyeongsangnam-do, Republic of Korea No. 1213 No. 58 (58) Field surveyed (Int.Cl. ⁶ , DB name) B01D 53/60 B01D 53/74 B01D 53/34

Claims (5)

(57) [Claims] 1. A method for oxidizing sulfurous acid gas and nitrogen oxides using a low-temperature plasma reactor and finally producing and removing neutral salts with ammonia. A desulfurization and denitrification method using a low-temperature plasma reactor, wherein water contained in exhaust gas is condensed on the surface of the condenser in a condenser provided inside the reactor to promote salt formation and neutralization. 2. A desulfurization and denitrification apparatus used in the desulfurization and denitrification method according to claim 1, wherein the exhaust gas flows from a low-temperature plasma reactor to an electric dust collector to perform desulfurization and denitrification. The reactor is composed of a low-temperature plasma reactor, a plasma electrode contained in the reactor, and a condenser that cools and solidifies the water contained in the exhaust gas. A low-temperature plasma desulfurization and denitrification device, which is arranged in series along the flow of exhaust gas. 3. The low-temperature plasma desulfurization and denitrification apparatus according to claim 2, wherein a plurality of plasma electrode rods and / or condensers provided inside the low-temperature plasma reactor are arranged. 4. The low-temperature plasma desulfurization and denitrification apparatus according to claim 2, wherein the condenser is disposed downstream of the exhaust gas flow of the plasma electrode rod inside the low-temperature plasma reactor. 5. The operating temperature of the low-temperature plasma reactor is 110
The method for low-temperature plasma desulfurization and denitrification according to claim 1, wherein the low-temperature plasma desulfurization and denitrification are prevented by raising the temperature to at least ℃.