KR100697840B1 - SOx, VOx and NOx reduction system at furnace - Google Patents

Abstract

A system for reducing SOx, VOx and NOx in a furnace is provided to reduce SOx, VOx and NOx by selective catalytic reduction or selective non-catalytic reduction by using simplified triple complex equipments without generation air pollution. A system for reducing SOx, VOx and NOx in a furnace includes a first De-NOx equipment(10) based on selective catalytic reduction, a second De-NOx equipment(20) based on selective non-catalytic reduction, and a De-SOx/De-VOx equipment(30). The first De-NOx equipment has a first storage bath(11), a first improved supply module(12), and a catalyst reaction tower(13), and is disposed at a lower part of a furnace(100), wherein a reducing agent kept in the first storage bath is supplied to the catalyst reaction tower along the flow path of exhaust gas out of the furnace. The second De-NOx equipment has a second storage bath(21) and a second improved supply module(22) based on the selective non-catalytic reduction, wherein a reducing agent kept in the second storage bath is sprayed to the inside of the furnace through one or more sprays(110). The De-SOx/De-VOx equipment includes a third storage bath(31) and a third improved supply module(32), wherein an additive kept in the third storage bath is sprayed into the furnace by the spray(110). A first De-NOx action and the De-SOx/De-VOx action are carried out simultaneously by spraying the reducing agent for De-NOx and the additive for the De-SOx/De-VOx simultaneously based on the selective catalytic reduction and a second De-NOx action is further carried out based on the selective non-catalytic reduction for additional reduction of NOx remaining in exhaust air moving along exhaust path.

Description

Reduction system of sulfur oxide, vanadium oxide and nitrogen oxide in combustion apparatus {SOx, VOx and NOx reduction system at furnace}

1 is a schematic process diagram of an abatement system according to the present invention.

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

1 ----- abatement system, 10 ----- first denitrification equipment,

20 ----- denitrification plant, 30 ----- desulfurization and devanadium plant,

The present invention can reduce sulfur oxides and vanadium oxides together with a denitrification system that reduces nitrogen oxides by using Selective Catalytic Reduction (SCR) or Selective Non-Catalytic Reduction (SNCR). It is an abatement system equipped with a complex facility.

As described, by-products such as nitrogen oxides (NOx), sulfur oxides (SOx), and vanadium oxides (VOx), which are harmful emissions from the combustion of fossil fuels in factories or combustion engines, have various methods and methods. Therefore, the reality is that the need to keep the atmosphere clean by reducing it to the maximum.

These nitrogen oxides are released into the troposphere to generate photochemical smog while generating various oxidizing agents such as ozone (O ₃ ), HCHO, PAN, etc., due to external influences of self- or visible light. In particular, ozone and nitrogen dioxide (NO ₂ ) react with hydrocarbons in the air to produce oxidants, which results in photochemical smog.

In addition, in sulfur oxides, sulfur is commonly found in "fossil fuels" such as coal and petroleum. Therefore, as urbanization progresses, the consumption of fossil fuels is inevitably increased, resulting in acid rain.

The process is as follows.

Sulfur dioxide in the fossil fuel is burned to produce sulfur dioxide (SO ₂ ). Sulfur dioxide reacts with oxygen (O ₂ ) in the atmosphere and is converted to sulfur trioxide (SO ₃ ), which is then dissolved in moisture in the atmosphere to become sulfuric acid (H ₂ SO ₄ ), dissolved in rain water and mixed down.

In addition, although not indicated in the formula, vanadium (V) in the fuel is converted to V ₂ O ₅ .

In order to reduce the oxides of sulfur and vanadium generated during combustion of the fuel, the sulfur oxides should be provided separately from the nitrogen oxide reduction system. In particular, the sulfur oxide reduction in parallel with the selective non-catalytic reduction method for reducing the nitrogen oxides in the furnace is required. The installation of additional equipment exposes problems to the durability of the furnace.

More specifically, sulfur dioxide is contained in flue gas of combustion apparatuses such as thermal power plants and factories, such as large boilers, as sulfur, vanadium or fuels and materials containing these compounds are burned. Since this flue gas is a source of pollution, it does not mean sulfur oxides, sodium (Na), potassium (K), vanadium (V) and chlorine (Cl) generated in the furnace not only in the combustion device but also in components such as ammonia injection facilities. The secondary reactions not only cause fatal hazards to the catalyst for denitrification, but also cause excessive slag formation in the combustion apparatus and strong acidification of fly ash, resulting in corrosion of many post equipment. In particular, a reducing agent such as urea or ammonia used to remove nitrogen oxides and sulfur oxides and vanadium oxides generated in the combustion apparatus react with each other, thereby degrading the performance of the catalyst and even making it unusable.

As described above, the abatement system according to the present invention having a nitrogen oxide abatement facility and a sulfur oxide abatement facility using a selective non-catalytic reduction method using urea or ammonia and a selective catalytic reduction method is used in the combustion apparatus through a selective non-catalytic reduction method. 2, to perform the first denitrification, desulfurization and devanadium action by simultaneously spraying the denitrification reducing agent and the additive for desulfurization and devanadium and further reducing residual nitrogen oxides remaining in the exhaust gas moving along the discharge path. It is characterized in that the denitrification is carried out by selective catalytic reduction.

As is well known to those skilled in the art, the process of denitrifying nitrogen oxide using urea (NH ₂ CONH ₂ ) or ammonia (NH ₃ ) as a reducing agent in a selective catalytic reduction method or a selective non-catalytic reduction method is as follows.

The chemical reaction of ammonia and nitrogen oxides is

As above.

In other words, ammonia (NH ₃ ) is hydrolyzed to react with nitrogen oxides to produce nitrogen (N ₂ ) and water (H ₂ O), which is converted to nitrogen oxides to minimize its emissions.

In place of ammonia, urea (NH ₂ CONH ₂ ) to be used as a reducing agent is converted to the following formula (3).

Ammonia and cyanuric acid (HNCO) decomposed from urea are reacted with nitrogen oxides in a denitrification system such as a catalytic reaction tower, and the reaction of ammonia and nitrogen oxides is described by Chemical Formula 2. Through the reaction of another product, cyanuric acid and nitrogen oxides,

As a chemical reaction, harmful nitrogen oxides are converted into nitrogen (N ₂ ) and carbon dioxide (CO ₂ ).

Secondary reactions such as SOx and sodium (Na), potassium (K), vanadium (V) and chlorine (Cl) generated in combustion apparatuses, such as furnaces, act as a critical hazard to denitrification catalysts and Since excessive slag is generated and strong acidification of fly ash causes problems such as corrosion of the post equipment, it is necessary to remove sulfur oxides reliably.

Formula 5 transports the off-gas after sufficiently desulfurized to the rear end equipment to react with sulfur oxides are magnesium oxide (MgO) additives to be used as a reducing agent for the desulfurization by neutralization with magnesium sulfate (MgSO _4), and, MgO · V ₂ O ₅ . The additive for desulfurization and vanavanadium may be selected from the group of magnesium (Mg), magnesium oxide (MgO) or magnesium hydroxide (Mg (OH ₂ )).

It is an object of the present invention to provide a desulfurization and denitrification system.

Another object of the present invention is to reduce the life extension and maintenance costs of the plant through desulfurization and denitrification.

Still another object of the present invention is to significantly reduce nitrogen oxides, sulfur oxides, and vanadium oxides to prevent air pollution.

The invention will now be described in detail with reference to the accompanying drawings.

1 is a schematic process diagram of a reduction system according to the present invention, in particular the present invention is to selectively reduce sulfur oxides in addition to nitrogen oxides (Selective Catalytic Reduction (SCR) or selective non-catalytic reduction method (Selective Non- A denitrification facility (10, 20) based on Catalytic Reduction (SNCR) and desulfurization and devanadium facility (30) are combined.

As shown briefly only the equipment, the present invention provides a first denitrification system 10 based on the selective catalytic reduction method, a second denitrification system 20 based on the selective non-catalytic reduction method and a desulfurization / devanadium facility. It consists of 30.

The first denitrification system 10 of the selective catalytic reduction method provided to remove nitrogen oxide which is a part of harmful exhaust gas discharged from a plant or a combustion engine, etc. is based on the content of nitrogen oxide contained in the exhaust gas discharged from the combustion device 100. According to the stoichiometric ratio, if ammonia or urea is decomposed in a short response time under high temperature and converted to ammonia (see Formula 3), the decomposed ammonia is chemically decomposed with nitrogen oxides in the first denitrification system (10). It causes the reaction, through the reduction chemical reaction nitrogen oxides are converted to harmless nitrogen, thereby significantly reducing the emissions of harmful nitrogen oxides (see Formula 2 and Formula 4).

The storage tank 11 in the first denitrification system 10 stores a reducing agent such as ammonia or urea, and the improved supply module 12 stores the storage tank 11 based on the amount of nitrogen oxides to be generated in the combustion device 100. ), A predetermined amount of reducing agent is provided to the next step. That is, the improved supply module 12 determines the flow rate required by the catalytic reaction tower 13, which is the amount of nitrogen oxide contained in the exhaust gas generated from the combustion device 100 and the ammonia or element required therefor. The amount of reducing agent formed is calculated according to the stoichiometric equivalence ratio and is supplied to the improved supply module 12. As is already well known to those skilled in the art, it is possible to substitute urea for use in storage tank 11 due to the handling risks of ammonia, which are not specifically described here but through various chemical reactions to allow urea to be converted to ammonia. Ammonia as a reducing agent is preferably mixed with air to form a very thin ammonia vapor phase. The lean ammonia vapor is then injected into an ammonia injection grid (not shown). The ammonia injection facility smoothly maximizes the degree of mixing nitrogen oxide and lean ammonia vapor discharged from the combustion device 100. As described, the mixed gas of the lean ammonia vapor and the nitrogen oxide is moved to the catalytic reaction column 13, whereby the nitrogen oxide causes a more effective reduction reaction through the ammonia. In general, the reaction temperature of the catalytic reaction tower 13 is at a high temperature of 300 ° C. or higher, and must be mixed with sufficient excess air before entering the catalytic reaction tower 13 to limit the explosiveness of ammonia. The multi-stage catalytic reaction tower 13 ensures a sufficient residence time for chemical reaction of nitrogen oxide and ammonia to occur inside, and is reformed into nitrogen and hydrogen. This nitrogen and oxygen is released to the atmosphere through the chimney (9). The harmful nitrogen oxides through the first denitrification system 10 according to the schematic selective catalytic reduction method are converted into nitrogen gas.

The second denitrification of the selective non-catalytic reduction method for reducing the emission of nitrogen oxides (NO _X ) in the combustion device 100, which is a component facility using recycled fuel using fuel and waste in a large chemical plant according to the other reduction method. The plant 20 is adapted to treat gaseous substances, in particular the production of nitrogen oxides at high temperatures during the heating and combustion of the combustion apparatus 100 to an internal temperature, for example 1,500 ° C. or higher, mainly due to the formation of free radicals of oxygen and nitrogen. It is further increased due to chemical bonding between and nitrogen oxides. In addition, the fuel itself contains nitrogen oxides, and is converted to nitrogen oxides during the combustion process to reduce the nitrogen oxides by injecting chemicals to be used as a reducing agent such as ammonia or urea.

This, in the second denitrification facility 20 to spray the reducing agent at the point of the upper side wall of the combustion device 100 so that the reduction reaction for denitrification can occur between 850 to 1,100 ℃. In addition, a plurality of atomizers 110 disposed on the upper side wall of the combustion apparatus 100 are configured to spray the reducing agent at a speed of 15 to 30 m / s or more in order to reliably spray the reducing agent into the large combustion apparatus.

The second denitrification apparatus 20 for directly reacting with nitrogen oxides generated in the combustion apparatus 100 operating under a high temperature to have a denitrification effect primarily includes a reducing agent used in the first denitrification apparatus 10 described above. Similarly, ammonia or urea is used as the reducing agent. The reservoir 21 safely stores the reducing agent as described above. The reducing agent to be supplied to the combustion device 100 is discharged to the top of the combustion device 100 by controlling the amount of reducing agent and the spraying speed of the reducing agent by means of the improved supply module 22.

As described above, the reducing agent to be stored in the denitrification plant is characterized in that it is in the form of ammonia, preferably urea or ureaprile. In addition, the denitrification reducing agent may use ammonium carbonate (NH ₄ CO ₃ ).

The desulfurization and devanadium facility 30 is for reducing a large amount of sulfur oxide and vanadium oxide generated in the combustion device 100 which is burned at a high temperature, and is arranged similarly to the second denitrification facility 20.

As shown, the desulfurization and devanadium facility 30 is composed of a reservoir 31, an improved supply module 32, a pump and a sprayer 110. In particular, all components move through a flow path such as a pipe. The storage tank 31 of the desulfurization and devanadium installation 30 contains an additive, for example magnesium oxide, which can react with sulfur oxides and desulfurize. While detecting the emissions of sulfur oxides generated when the fuel is combusted in the combustion device 100, the combustion apparatus 100 moves to the injector 110 under the control of the improved supply module 32 (see Formula 5).

In order to improve structural stability and simplification, the denitrification reducing agent to be controlled and transferred to the improved supply module 22 of the second denitrification plant and the desulfurization reducing agent to be controlled and transferred to the improved supply module 32 of the desulfurization and devanadium facility 30. The additive to be used may be sprayed into the combustion device 100 through the same sprayer 110 through each flow path through the pump. In other words, the reducing agent and the additive stored in the second denitrification facility 20 and the desulfurization and devanadium facility 30 are injected into the combustion device 100 through the same atomizer 110, but may be provided in the combustion device. The number of atomizers can be significantly reduced to ensure the durability of the combustion device, as well as to reduce the considerable labor in installing the atomizer.

In particular, the additive may be selected from the group consisting of magnesium, magnesium oxide, magnesium hydroxide or combinations thereof.

In addition, the reduction system 1 according to the present invention is driven. Therefore, sulfur oxides and nitrogen oxides are generated in the combustion apparatus 100, and the appropriate reducing agent and additive are added in the second denitrification facility 20 and the desulfurization and devanadium facility 30 through the improved supply module by sensing their emissions. It is injected into the combustion device 100 through the sprayer 110. Then, the nitrogen oxide having a lower concentration provides an additional denitrification effect by means of the first denitrification system 10 having a catalytic reaction tower installed outside the combustion device 100. The purified exhaust gas is discharged into the atmosphere through the chimney 9 of FIG.

The invention is not limited to this specification with reference to the accompanying drawings, but it is to be understood that modifications and variations are possible within the scope of the following claims.

As described above, according to the present invention, not only can nitrogen oxides be reduced through the selective catalytic reduction method using urea or ammonia as a reducing agent, the selective non-catalytic reduction method and a combination thereof, but also sulfur oxides generated by using sulfur-containing fuel. In addition to the high efficiency of denitrification, the protection of the catalyst by preventing slag adhesion in the furnace, the removal of sulfur oxides and vanadium oxides in the furnace, and the neutralization of fly ash are provided to achieve the protection of the post equipment after the combustion device. In addition, it is possible to simply apply the triple complex equipment economically to prevent air pollution in advance, and also to create an economic benefit effect to reduce the life of the equipment and cost of maintenance.

Claims (4)

In the reduction system for reforming the pollutant generated by the operation of the combustion device 100, On the basis of the selective non-catalytic reduction method, a reservoir 21 and an improved supply module 22 are provided, and the reducing agent stored in the reservoir 21 is one or more atomizers 110 inside the combustion device 100 along a flow path. A second denitrification facility 20 sprayed through; Desulfurization and devanadium having a reservoir 31 and the improved supply module 32, the additive stored in the reservoir 31 is sprayed through one or more atomizers 110 inside the combustion device 100 along the flow path Facility 30; Based on the selective catalytic reduction method, a storage tank 11, an improved feed module 12, and a catalytic reaction tower 13 are arranged on the downstream side of the combustion device 100, and the reducing agent stored in the storage tank 11 is provided. And a first denitrification system (10) for providing the exhaust gas to be discharged from the combustion device (100) to the catalytic reaction tower (13) along the flow path. 2. The abatement system of claim 1, wherein said reducing agent consists of urea or ammonia. The method of claim 1 or 2, wherein the additive is selected from the group consisting of magnesium (Mg), magnesium oxide (MgO), magnesium hydroxide (Mg (OH ₂ )) and is used as a reducing agent for desulfurization and talvanadium. Abatement system. According to claim 1, wherein the atomizer 110 is located at the top of the combustion device 100, more specifically the internal temperature of the combustion device within the range of 850 to 1,100 ℃, the reducing agent and additives 15 to 30m / s or more Reduction system, characterized in that sprayed by.

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