KR101041651B1 - Complex denitrification system - Google Patents

Abstract

The present invention relates to an integrated complex denitrification system for removing nitrogen oxides remaining in the exhaust gas between the boiler and the chimney, the present invention is formed in the form of an empty box inside, the exhaust gas after combustion discharged from the boiler to one side inflow A filter dust collector in which an exhaust gas inlet is formed; Cotton cloth, wool, asbestos, silk natural fiber or glass fiber or synthetic fiber or artificial fiber provided in the filter bag; And a plate-shaped SCR catalyst layer provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas, wherein the shape of the filter cloth is formed in a bag shape, and the SCR catalyst layer is provided inside the filter cloth. Removes nitrogen oxide contained in, wherein, on one side of the exhaust gas inlet port of the filter precipitator, a control damper capable of adding or subtracting the flue gas inflow amount containing the nitrogen oxide to the filter bag is installed, the plate-shaped SCR catalyst layer, A support provided in the bag filter; And a disk-shaped SCR catalyst installed in the support and provided in multiple stages at regular intervals so as not to take a differential pressure. The cross-section of the SCR catalyst is formed in any one of a honeycomb type and a corrugated type.

 Catalyst, nitrogen oxide, bag filter

Description

Integrated Complex Denitrification System {COMPLEX DENITRIFICATION SYSTEM}

The present invention relates to an integrated complex denitrification system for removing nitrogen oxides remaining in exhaust gas between a boiler and a chimney.

In general, electricity generation uses nuclear, coal, LNG, oil and renewable raw materials. In Korea, coal accounts for about 33%, which is increasing every year. In addition, the government is also planning to maintain more than 40% of heavy oil and coal-fired power generation facilities in consideration of the global supply and demand of energy resources. However, as regulations on air pollutants are expected to be tightened in the future, it is necessary to develop related technologies for treating air pollutants emitted from boilers.

The conventional treatment of existing boiler exhaust gas is applied to the system of unique unit technology such as denitrification unit, electrostatic precipitator, deactivation unit, and other harmful substance treatment technology. Currently, the Selective Catalytic Reduction (SCR) method, which is a dry method in terms of technical reliability and economic efficiency, is adopted by various countries around the world, especially in Japan. I use it.

In particular, the treatment of nitrogen compounds in boilers is mainly the selective catalytic reduction method using ammonia as a reducing agent. Catalysts mainly used for the treatment of nitrogen oxides in boilers disperse oxides such as V, W and Mo and mixtures thereof in a finely dispersed form (TiO ₂ / V ₂ O ₂ ) in Ti-based oxides. Depending on the shape, it is used in the shape of honeycomb, plate, etc. However, in domestic boilers, the catalyst activity was reduced due to the thermal fatigue of the catalyst due to frequent operation changes such as the temperature of the flue gas increased instantaneously, and the catalyst life was lowered, thereby increasing the operating cost due to frequent catalyst exchange.

To solve this problem, a method of installing a denitrification facility at the rear end of the Flue-Gas Desulfurization (FGD) field has been developed. Brought about economic losses.

In order to satisfy the recently strengthened standards, even if low sulfur fuel is used, SO2 generation of about 100 to 200 ppm is inevitable, and 5 to 20% of water is contained in the exhaust gas, which is inevitable when ammonia is used as a reducing agent of the denitrification equipment. As a result, catalyst poisoning may occur due to the production of ammonium sulfate and the like. In addition, the outflow of ammonia contained in the flue-gas causes corrosion of the rear end equipment, and the regulation of ammonia itself is tightened.

Commercial ammonia catalysts are operated with a molar ratio of NH ₃ / NOx of 0.8 to 0.9 in order to avoid ammonia slip, but in this case the NOx removal rate can be obtained only up to 80 to 90%. There is a disadvantage in that the amount of the catalyst used is sharply increased.

And because the enumerated system takes up a lot of installation space, it is difficult to secure the site and the installation cost is increased when the existing facility is repaired. In addition, there is a problem that the performance fluctuation range of the electrostatic precipitator is large due to the change of coal type.

In order to solve the above problems, the present invention aims to integrate the SCR catalyst inside the bag filter in order to exhibit excellent denitrification efficiency even in a low temperature region.

In addition, an object of the present invention is to minimize the installation space and save installation cost through the above-mentioned integration.

In order to achieve the above object, the present invention,
An inner bag formed in an empty box shape and having a exhaust gas inlet through which exhaust gas after combustion discharged from a boiler is formed at one side; Cotton cloth, wool, asbestos, silk natural fiber or glass fiber or synthetic fiber or artificial fiber provided in the filter bag; And a plate-shaped SCR catalyst layer provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas.
The filter cloth is formed in the shape of a bag,
The SCR catalyst layer is provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas,
Here, on one side of the exhaust gas inlet of the bag filter,
A control damper is provided that is capable of adding or subtracting the amount of inlet gas containing nitrogen oxides to the bag filter,
The plate-shaped SCR catalyst layer,
A support provided in the bag filter; And
Is installed on the support, and made of a disk-shaped SCR catalyst provided in multiple stages at regular intervals so as not to take the differential pressure,
The cross section of the SCR catalyst is formed in one of honeycomb type and corrugated type.

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The effect which arises by implementation by said structure is as follows.

First, the operating temperature of the catalyst is lowered to increase the life of the catalyst and at the same time the operating cost has the advantage of lower than other denitrification system.

In addition, since the denitration catalyst and the bag filter are integrated, the pressure loss of the system is low, and the driving part is simplified, and the energy consumption rate is low.

In addition, since the SCR operation temperature is lowered, reheating of the exhaust gas is not required, thereby saving energy.

And since the existing space is used for improvement / repair of existing facilities, construction costs can be reduced by minimizing the scope of renovation.

Compared with the existing enumerated SCR system, the operation cost is low due to the reduction of unit process.

Hereinafter, the present invention will be described in detail with reference to preferred embodiments of the accompanying drawings.

1 is a view schematically showing an integrated complex denitrification system according to the present invention, and FIG. 2 is a view schematically showing the filter cloth of FIG. 1.

The present invention is an integrated composite denitrification system relates to a technique for removing nitrogen oxides by selective catalytic reduction, as shown in Figure 1, the inside is formed in the form of an empty box, exhaust gas after combustion discharged from the boiler 20 on one side A filter dust collector 100 in which the exhaust gas inlet 150 is formed; A filter cloth provided in the bag filter 200; And a plate-shaped SCR catalyst layer 300 provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas.

Filter dust collector (filtration dust collector, 100) serves to filter various harmful particles, such as dust contained in the exhaust gas discharged from the boiler (20). In this embodiment, the filter medium of glass fiber or cotton fiber attached to the filter material as shown in Figure 2 is formed by adopting an internal filtration method to collect the dust inside the filter cloth.

As described above, the filter cloth 200 is a function of filtering out dust from inside the bag filter 100 and may also be called a follicle or a filter cloth. That is, when the dust and the like contained in the exhaust gas flows into the inside of the bag filter 100, it serves to filter them. At this time, the material of the filter cloth 200 may be composed of natural fibers such as cotton wool, wool, asbestos, silk and hemp, or may be implemented by artificial fibers such as glass fiber, synthetic fiber and metal wool.

In the embodiment, the filter cloth 200 was formed in a bag shape. However, it should be noted that in the construction of the filter cloth 200, the gap between the tissues of the filter cloth 200 should be dense enough to filter out particulate matter of about 0.1 to 0.5. In addition, the allowable temperature of the filter cloth 200 is different in the temperature that can be treated according to the fiber, but except for asbestos, generally not suitable for high temperature high temperature gas, care must be taken in selecting the material of the filter cloth 200 according to the implementation conditions. do.

SCR catalyst layer 300 is provided in the above-described filter cloth 300 serves to remove the nitrogen oxide contained in the exhaust gas. In the present invention, unlike the existing technology, the SCR catalyst 320 is mounted inside the bag filter 100 to integrate the same, thereby minimizing the installation space of the system for removing nitrogen oxide and reducing the installation cost.

The SCR catalyst layer 300 may be configured in various configurations according to the implementation conditions. In the present embodiment, as shown in the configuration shown in Figure 2, after the SCR catalyst layer 300 is installed at regular intervals of the support 310 inside the filter dust collector 100, the SCR catalyst 320 to the interval of the support It was equipped in multiple stages so that a differential pressure might not be matched. At this time, the shape of the SCR catalyst 320 was configured to be mounted on the support by forming a disk shape.

In addition, when the SCR catalyst 320 is configured in a disk shape, the exhaust gas inlet 150 is provided at one lower portion of the filter dust collector 100 to remove the dust and the like of the exhaust gas passing through the filter cloth 200, and the exhaust gas has a temperature and density. Nitrogen oxides (NOx) are removed while passing through the SCR catalyst layer 300 as the temperature moves to the upper portion and rises due to the difference.

And the SCR catalyst 320 is formed in a disk shape, the cross-section of the SCR catalyst 320 can be configured in various shapes, as shown in Figures 3 to 4 attached, honeycomb honeycomb (Honeycomb Type) or core It is preferable to carry out by selecting to form in the shape of any one of the gate type (Corrugate Type).

And in the practice of the present invention, the control damper 155 for controlling the influx of the inflow amount of the exhaust gas containing nitrogen oxide to the filter dust collector 100 in the exhaust gas inlet 150 formed on one side lower portion of the filter dust collector 100 It can be carried out further including. That is, by controlling the inflow amount of the exhaust gas flowing into the bag filter 100, it is possible to determine the demassation of nitrogen oxides and the operation of the denitrification system. And when replacing the filter cloth 200 or SCR catalyst 300 has the advantage that can block the inflow of the exhaust gas through the control damper 155 and replace them. In addition, by integrating the bag filter 100 and the SCR catalyst layer 300, there is an advantage in that it is possible to save energy required for securing the space and operating the system.

Hereinafter will be described the operating principle of the present invention.

As shown in Figure 1, the exhaust gas discharged after the combustion of coal in the boiler 20 is discharged along the pipe. The discharged exhaust gas is mixed with ammonia, a reducing agent injected by an ammonia injector.

The discharged exhaust gas is regulated by the control damper 155 along the pipe and is introduced into the bag filter 100. Since the exhaust gas introduced into the filter dust collector 100 is relatively higher in temperature than the inside of the filter dust collector 100, the exhaust gas rises upward due to a density difference, and passes dust through the filter cloth 200 installed inside the filter dust collector 100. Etc. are removed.

The exhaust gas from which dust is removed passes through the multi-stage SCR catalyst layer 300 installed inside the filter cloth 200, and ammonia reacts with the SCR catalyst 320 to cause an oxidation reaction in which hydrogen is released. A reduction reaction occurs, i.e. 4NO + 4NH3 + O2 4N2 + 6H2, and consequently ammonia and flue gas are converted to nitrogen (N ₂ ) and water (H ₂ O) to remove nitrogen oxides (NOx).

The reaction temperature at this time is 200 ~ 350, the space velocity (Space Velocity, SV) is 7,000 ~ 10,000 h ^-1 . At this time, care should be taken to put a lot of catalyst without taking the differential pressure to the SCR catalyst layer 300 as much as possible.

After the exhaust gas exited through the exhaust gas outlet 160 of the bag filter is the temperature is reduced to a certain temperature while going through the reduction reaction, the temperature is reduced to 90 while passing through the heat exchanger (30) chimney 40 It is discharged to the outside via.

1 is a view schematically showing an integrated complex denitrification system according to the present invention;

2 is a view schematically showing the filter cloth of FIG.

3 is a honeycomb perspective view and a partially enlarged view of an SCR catalyst used in the present invention;

4 is a corrugated perspective view and a partially enlarged view of an SCR catalyst used in the present invention.

<Description of the symbols for the main parts of the drawings>

20; Boiler

30; heat transmitter

40; Chimney

100; Bag filter

150; Flue gas inlet

155; Adjustable damper

160; Flue gas outlet

200; Filter cloth

300; SCR Catalyst Layer

310; support fixture

320; SCR Catalyst

Claims (4)

An inner bag formed in an empty box shape and having a exhaust gas inlet through which exhaust gas after combustion discharged from a boiler is formed at one side; Cotton cloth, wool, asbestos, silk natural fiber or glass fiber or synthetic fiber or artificial fiber provided in the filter bag; And a plate-shaped SCR catalyst layer provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas. The filter cloth is formed in the shape of a bag, The SCR catalyst layer is provided inside the filter cloth to remove nitrogen oxides contained in the exhaust gas, Here, on one side of the exhaust gas inlet of the bag filter, A control damper is provided that is capable of adding or subtracting the amount of inlet gas containing nitrogen oxides to the bag filter, The plate-shaped SCR catalyst layer, A support provided in the bag filter; And Is installed on the support, and made of a disk-shaped SCR catalyst provided in multiple stages at regular intervals so as not to take the differential pressure, The cross-section of the SCR catalyst is an integral composite denitrification system, characterized in that formed in the shape of any one of honeycomb type and corrugated type. delete delete delete

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