KR20200033161A - NOx and SOx removal device and removal process in wet scrubber using pyrolysis of hydrogen peroxide - Google Patents

Abstract

The present invention relates to an apparatus and a method for removing NOx and SOx in a wet scrubber using pyrolysis of hydrogen peroxide, which is capable of efficiently removing NOx. The apparatus of the present invention comprises: a wet scrubber unit (2); a water treatment system treating discharged contaminated water; a recovery line returning the contaminated water to the wet scrubber unit (2); a hydrogen peroxide storage unit connected to the recovery line; a sodium hydroxide storage unit connected to the recovery line; and an inlet line.

Description

The NOx and SOx removal device and removal process in wet scrubber using pyrolysis of hydrogen peroxide}

The present invention relates to an SOx removal apparatus using a wet scrubber using thermal decomposition of hydrogen peroxide and a removal method using the same.

Nitrogen oxides are produced in high temperature combustion and discharged into the atmosphere, most of which are condensed in nitrogen in the air, but some are caused by oxidation of nitrogen contained in the fuel. When nitrogen is oxidized, various nitrogen oxides, namely nitrogen monoxide (NO), nitrogen trioxide (N ₂ O ₃ ), and nitrogen dioxide (NO ₂ ), and the like are collectively referred to as NOx. Nitrogen oxides are easily oxidized in the air and converted to nitrogen dioxide (NO ₂ ). When dissolved in water, nitric acid (HNO ₃ ) becomes a source of acid rain.

In addition, nitrogen oxides are harmful and directly irritate the human respiratory system, causing inflammation and damaging plants, and indirectly play a key role in photochemical smog reactions.

Most of the sulfur oxides are produced by combining sulfur in the fuel with oxygen in the air during combustion and discharged into the atmosphere. When sulfur content is oxidized, it first becomes a port (= sulfur dioxide: SO ₂ ), and when it is further oxidized, it becomes sulfur trioxide (= sulfuric acid gas: SO ₃ ), which is collectively referred to as SOx (SO ₂ and SO ₃ ). SO ₂ easily oxidizes to SO ₃ in air, which reacts with moisture in the air to form fine sulfuric acid (H ₂ SO ₄ ) droplets.

Sulfur oxide gas is a colorless, strong, irritating gas that, when above a certain concentration, is poisonous to the respiratory system and harms plants that have low resistance even at low concentrations. In addition, sulfur oxides, along with nitrogen oxides, cause acid rain to erode, eroding buildings and metal structures, and harming plants and animals.

As a conventional chemical treatment method for treating nitrogen oxides, a method of injecting ammonia, urea or cyan (CN) solution to exhaust gas has been mainly used in burners and industrial furnaces, and in the case of diesel engines, reducing nitrogen oxides The method of spraying urea containing urea components has been used most recently. In the conventional method of reducing nitrogen oxides using ammonia and urea, the concentration of nitrogen oxides is minimized near 1400K (1127 ℃), so that almost all nitrogen oxides are decomposed, but the exhaust gas temperature should be as high as 1127 ℃, so a factory using a burner is used. There are problems such as reheating of exhaust gas, which results in enormous energy loss, which is unreasonable in reality.

 A system in which ammonia and urea are installed together with a catalyst is also applied in recent years, but there is a problem in that installation and operation costs are high. In addition, ammonia itself is a toxic substance and has the disadvantage of being highly corrosive and difficult to store. Since cyanide itself has strong toxicity, the risk of personal injury in case of leakage is very large and requires great care during storage.

Moreover, after use, cyanide sublimates and becomes isocyanoic acid, condensed in the low temperature part of the nitrogen oxide reduction device and remains as a poison, so it is very dangerous when used. The method for reducing nitrogen oxides using platinum catalysts can decompose nitrogen oxides at relatively low temperatures (about 800 ° C), but the configuration of the device is very complex, the installation cost and the cost of the catalyst are very high, and the exhaust gas has a large capacity or high concentration. Nitrogen oxides cannot be used. On the other hand, in the case of nitrogen oxides emitted from diesel engines, there has not been an example in which the reduction device has been applied in Korea. In foreign countries, there is a method of simultaneously reducing nitrogen oxides and so-called particulate matter using a catalyst of Toyota Motor. There are disadvantages of high cost and short life.

There are two types of methods for reducing air pollution by sulfur oxides, proactive and ex post. For the prior method, it is most preferable to use a low-sulfur fuel (low-sulfur crude oil or coal) or a clean fuel (natural gas, LPG) or a desulfurization of the petroleum products in advance. As an ex post method, it is a so-called flue gas desulfurization method that desulfurizes sulfur dioxide in flue gas generated by combustion of heavy oil or coal and discharges it into a chimney.

Accordingly, there is a need for a stable and economical method for efficiently reducing nitrogen oxides and sulfur oxides simultaneously.

With increasing interest in the environment around the world, emission control of harmful substances is strengthening. Since 2016, the International Maritime Organization (IMO) has been implementing regulations to reduce the amount of NOx emissions from ships to 20% in the ECAs. Currently, typical NOx removal technologies include SCR, EGR, fuel replacement, and removal using oxidizing agents.

NO, which accounts for about 90% of the NOx emitted to the atmosphere, is very low in water so that it can be removed in a wet scrubber by oxidizing it with other highly soluble nitrogen oxides (NO ₂ , HNO ₃ , HNO ₂ ). Republic of Korea Patent Registration '10 -1696979 'proposes a ship emission treatment system and a treatment method using the same, uses ozone in the treatment of ship emissions, and uses an oxidizing agent. The NO oxidation rate of H ₂ O ₂ is about 30%, which is not high, but when using UV or an oxidizing agent, the NO oxidation rate becomes 100% when sufficient H ₂ O ₂ is used, but the method using UV or an oxidizing agent requires additional equipment. There is a problem that there are many restrictions to apply to ships with limited space and weight.

KR 10-1696979

 Oxidation and Removal of Emission from Ship Using Hydrogen Peroxide Photolysis, Clean Technol, Vol.23, No.3, 2017.11, pp.294-301

In order to solve the above problems, an object of the present invention is to provide a NOx and SOx removal device in a wet scrubber in which thermal decomposition of hydrogen peroxide (H ₂ O ₂ ) is induced inside an exhaust gas outlet.

In addition, an object of the present invention is to provide a specialized structure for efficient treatment efficiency.

The NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide according to an embodiment of the present invention includes an inlet port for transferring exhaust gas generated from an exhaust gas source upward through an exhaust gas transfer line, and upwards from the inlet port Distributing the exhaust gas input to the inlet 1 / N is provided with a branch that is radially branched, the end of each branch is provided with a separate scrubber in communication, the scrubber is provided with the same cross-sectional area, each of the scrubbers A wet scrubber unit having a system for individually removing nitrogen oxides and sulfur oxides; A water treatment system provided in communication with one side of the scrubber part, equipped with a ph regulator, and treating contaminated water discharged through a discharge line after a reaction process in the scrubber; A recovery line for returning contaminated water including residual nitrogen oxides (NOx) and sulfur oxides (SOx), which were not oxidized even in the water treatment system, to the wet scrubber part; A hydrogen peroxide storage unit communicating with the recovery line and supplying hydrogen peroxide (H ₂ O ₂ ); A sodium hydroxide storage unit communicating with the recovery line and supplying sodium hydroxide (NaOH); The hydrogen peroxide storage unit and the sodium hydroxide storage unit and an inflow line communicating with the exhaust gas transfer line are provided, and the exhaust gas inputted to the inlet is uniformly distributed to each scrubber through the branching section, thereby providing nitrogen oxide and sulfuric acid. Provided is a structure of a NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide, characterized by comprising a wet scrubber portion for removing cargo.

At this time, it is characterized in that a predetermined ratio of NO contained in the exhaust gas is oxidized through thermal decomposition using hydrogen peroxide introduced into the exhaust gas transfer line through the inflow line and an exhaust heat source of 300 to 400 ° C included in the exhaust gas. do.

On the other hand, the exhaust gas is sulfur oxide (SOx) and nitrogen oxides include (NOx), and is that the hydrogen peroxide (H ₂ O ₂₎ aqueous solution injected in the liquid scrubber unit, the hydrogen peroxide inside the exhaust gas outlet (H ₂ It characterized in that the thermal decomposition of O ₂ ) is induced.

Then, the remaining amount of nitrogen oxide (NOx) that is not oxidized among the treated water discharged from the water treatment system is mixed with hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in a predetermined ratio through the recovery line 10. , It is characterized in that the configuration is introduced back to the wet scrubber.

On the other hand, the sodium hydroxide (NaOH) is characterized in that it is mixed with 0 to 0.03mol / L.

And, the pH controller (4) is characterized in that to adjust the pH of the aqueous solution to 7 to 9.

In addition, a sulfur oxide (SOx) and nitrogen oxide (NOx) dust collecting tank 7 is additionally installed at the outlet of the water treatment system 3.

At this time, the wet scrubber portion is in communication with the exhaust gas transfer line, the inlet for conveying the exhaust gas upwards, and branched by a number of 1 / N from the inlet, and at a predetermined angle in the upward direction around the inlet With respect to the divergent portion which diverges radially, each scrubber is provided in communication at each end of the branch portion, the scrubber is provided with the same cross-sectional area, and each of the scrubbers is provided as an independent treatment system, centering on the central axis of the inlet. It is characterized in that the combined cross-sectional shape of each of the rubbers is provided in a circular, elliptical or polygonal shape.

Each of the scrubbers is characterized by having a wet strover portion having a cross-sectional area of a predetermined angle with respect to the central axis of the inlet, and having the circular cross-sectional area by combining the strevers.

In addition, each of the scrubbers is composed of an individual scrubber having a trapezoidal cross-sectional area that is radially widened by a predetermined angle with respect to the central axis of the inlet, and the scrubbers are combined to have a wet cross-section having a predetermined polygonal shape. It is characterized in that it comprises a strut portion.

In addition, the exhaust gas introduced into the inlet is characterized by uniformly distributing the exhaust gas from each branch to the separate system after being uniformly distributed from the branch to each strever.

In the removal method using a NOx and SOx removal device in a wet scrubber using the thermal decomposition of the hydrogen peroxide, the thermal decomposition using the exhaust gas through the exhaust gas transfer line (H ₂ O ₂ ) and exhaust heat through the inlet line To do; Uniformly branching the exhaust gas flowing through the inlet from the branching section to each of the strevers; Oxidizing sulfur oxides (SOx) and nitrogen oxides (NOx) by the hydrogen peroxide (H ₂ O ₂ ) thermally decomposed in the scrubbers; Neutralizing H + generated in the oxidation step using sodium hydroxide (NaOH); A water treatment step of purifying the treated water coming through the neutralization reaction; And mixing the hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in water coming through the water treatment process and recovering it again with a wet scrubber.

At this time, it is characterized in that the pH in the water treatment system is adjusted within a range of 7 to 9 using a pH controller in the water treatment step.

And, it characterized in that it further comprises the step of collecting sulfur oxides (SOx) and nitrogen oxides (NOx) after the water treatment step.

Since it does not require any other equipment except the hydrogen peroxide (H ₂ O ₂ ) storage tank and spray nozzle, this technology is expected to be effectively applied to existing ships because the additional equipment cost is not large.

In addition, there is no side effect such as a simple reaction and no secondary pollutants, and 100% of NOx can be removed depending on the amount of hydrogen peroxide (H ₂ O ₂ ). As the amount of NOx to be removed increases, the more hydrogen peroxide (H ₂ O ₂ ) is consumed, the larger the amount of NOx emissions is, but a large container ship or ECAs that has a low proportion of emission limit zones (ECAs) in operation. It operates only inside, but it can be effectively applied to small ships with low NOx emissions.

On the other hand, the wet scrubber system composed of a plurality of independently operating scrubbers, and the effect of being able to maximize the processing efficiency of the scrubber can be expected due to the structural characteristics of the branch portion communicating with each individual scrubber in the exhaust line.

1 is a schematic diagram of a wet scrubber using hydrogen peroxide (H ₂ O ₂ ) pyrolysis according to an embodiment of the present invention.
2 is a process schematic diagram according to an embodiment of the present invention.
3 is a graph of NOx emission and SO ₂ removal according to the L / G ratio according to an embodiment of the present invention.
4 is a molar ratio of H ₂ O ₂ consumption and H ₂ O ₂ consumption: NO removal to satisfy NOx emission regulation according to an embodiment of the present invention.
5 to 7 is a view showing a coupling relationship connected to each scrubber from the inlet and the branch according to an embodiment of the present invention.
8 to 9 show the distribution of the exhaust gas inside the scrubber in the configuration of the existing wet scrubber.
10 to 11 shows the exhaust gas distribution state inside the scrubber in the configuration of the wet scrubber according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. However, the spirit of the present invention is not limited to the presented embodiments, and those skilled in the art to understand the spirit of the present invention may easily propose other embodiments within the scope of the same spirit.

1 is a schematic diagram of a wet scrubber using hydrogen peroxide (H ₂ O ₂ ) pyrolysis according to an embodiment of the present invention. 2 is a process schematic diagram according to an embodiment of the present invention. 3 is a graph of NOx emission and SO ₂ removal according to the L / G ratio according to an embodiment of the present invention. 4 is a molar ratio of H ₂ O ₂ consumption and H ₂ O ₂ consumption: NO removal to satisfy NOx emission regulation according to an embodiment of the present invention.

5 to 7 are views showing a coupling relationship connected to each scrubber from the inlet 8 and the branch 11 according to an embodiment of the present invention. 8 to 9 show the distribution of the exhaust gas inside the scrubber in the configuration of the existing wet scrubber. 10 to 11 shows the exhaust gas distribution state inside the scrubber in the configuration of the wet scrubber according to an embodiment of the present invention.

Looking at, the NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide according to an embodiment of the present invention includes an inlet 8 for transferring exhaust gas generated from an exhaust gas source upward through an exhaust gas transfer line, and Dispensing the exhaust gas inputted to the inlet (8) in the upward direction from the inlet (8) 1 / N is provided with a branch portion (11) that is branched radially, the end of each branch portion (11) a separate scrubber Is provided in communication, the scrubber is provided with the same cross-section, each scrubber is a wet scrubber portion (2) having a system for removing nitrogen oxides and sulfur oxides individually; A water treatment system provided in communication with one side of the scrubber part, equipped with a ph regulator, and treating contaminated water discharged through a discharge line after a reaction process in the scrubber; A recovery line for returning contaminated water including residual nitrogen oxides (NOx) and sulfur oxides (SOx), which were not oxidized even in the water treatment system, to the wet scrubber part 2 again; A hydrogen peroxide storage unit communicating with the recovery line and supplying hydrogen peroxide (H ₂ O ₂ ); A sodium hydroxide storage unit communicating with the recovery line and supplying sodium hydroxide (NaOH); The hydrogen peroxide storage unit and the sodium hydroxide storage unit and an inflow line communicating with the exhaust gas transfer line are provided, and the exhaust gas introduced into the inlet 8 is uniform to each scrubber through the branch 11. It provides a configuration of a NOx and SOx removal device in a wet scrubber using the thermal decomposition of hydrogen peroxide, characterized in that it has a wet scrubber portion (2) to remove nitrogen oxides and sulfur oxides.

At this time, it is characterized in that a predetermined ratio of NO contained in the exhaust gas is oxidized through thermal decomposition using hydrogen peroxide introduced into the exhaust gas transfer line through the inflow line and an exhaust heat source of 300 to 400 ° C included in the exhaust gas. do.

On the other hand, the exhaust gas includes sulfur oxides (SOx) and nitrogen oxides (NOx), the aqueous hydrogen peroxide (H ₂ O ₂ ) aqueous solution is injected in the wet scrubber part 2, and hydrogen peroxide inside the exhaust gas outlet It characterized in that the thermal decomposition of (H ₂ O ₂ ) is induced.

Then, the remaining amount of nitrogen oxide (NOx) that is not oxidized among the treated water discharged from the water treatment system is mixed with hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in a predetermined ratio through the recovery line 10. , It is characterized by a configuration that is introduced back to the wet scrubber (2).

On the other hand, the sodium hydroxide (NaOH) is characterized in that it is mixed with 0 to 0.03mol / L.

And, the pH controller (4) is characterized in that to adjust the pH of the aqueous solution to 7 to 9.

In addition, a sulfur oxide (SOx) and nitrogen oxide (NOx) dust collecting tank 7 is additionally installed at the outlet of the water treatment system 3.

At this time, the wet scrubber part 2 is in communication with the exhaust gas transfer line, the inlet port 8 for transferring the exhaust gas upward, and the inlet port 8 is branched to the number of 1 / N, the inlet port (8) The diverging portion 11 which branches radially with respect to a predetermined angle in the upward direction with respect to the center, and each scrubber is provided in communication with each end of the branching portion 11, and the scrubber has the same cross-sectional area It is characterized in that each of the rubbers is provided as an independent treatment system, and the combined cross-sectional shape of each of the rubbers is provided in a circular, elliptical or polygonal shape around the central axis of the inlet 8.

Each of the strrubbers is composed of an individual thruster having a cross-sectional area of a predetermined angle with respect to the central axis of the inlet 8, and the strevers are combined to provide a wet strover portion having a circular cross-sectional area. do.

In addition, each of the strevers is composed of individual struts having a trapezoidal cross-sectional area that is radially widened by a predetermined angle around the central axis of the inlet port 8, and the cross-section of a predetermined polygonal shape by combining the strevers It characterized in that it is provided with a wet strover portion having.

Then, the exhaust gas inputted to the inlet 8 is uniformly distributed to each of the strevers in the branch 11, and then uniformly treats the exhaust gas flowing into each separate system from the respective strevers. It is characterized by.

A wet scrubber 2 having an exhaust gas passage connected to an inlet and an exhaust line 9 connected to an outlet; A hydrogen peroxide (H ₂ O ₂ ) injection nozzle connected to the exhaust gas passage and an inlet line 8 at the end of the connection part, and a hydrogen peroxide (H ₂ O ₂ ) storage 5 connected to the recovery line 10; And a sodium hydroxide (NaOH) storage unit 6 connected to the recovery line 10, the aqueous solution of hydrogen peroxide (H ₂ O ₂ ) is sprayed in the wet scrubber, and hydrogen peroxide ( It provides a NOx and SOx removal device in a wet scrubber where pyrolysis of H ₂ O ₂ ) is induced.

The exhaust gas contains sulfur oxides (SOx) and nitrogen oxides (NOx), and is removed by thermal decomposition with the aqueous hydrogen peroxide (H ₂ O ₂ ) solution. In addition, the ratio of the aqueous solution (L / G, unit L / m ³ ) to the gas injected into the wet scrubber (2) is greater than or equal to 0.4, and hydrogen peroxide (H ₂ O ₂ ) has a nitrogen oxide (NOx) and molar ratio of 0.3 to 1.4. Can be used in proportions. Hydrogen peroxide (H ₂ O ₂ ) is thermally decomposed at 300 ~ 400 ℃ to oxidize a part of nitrogen oxide, and the remaining amount of unoxidized nitrogen oxide is oxidized by aqueous hydrogen peroxide (H ₂ O ₂ ) solution in a wet scrubber and dissolved in water. Can be removed. These characteristics or processes are explained in more detail by the following description and examples.

1 is a schematic diagram of a wet scrubber using hydrogen peroxide (H ₂ O ₂ ) pyrolysis according to an embodiment of the present invention.

An exhaust gas generated from diesel engines (1) is the exhaust gas of hydrogen peroxide (H ₂ O ₂₎ a storage tank (5) The hydrogen peroxide (H ₂ O ₂₎ supplied from the connected along the inlet line 8 via an injection nozzle Spray. The sprayed hydrogen peroxide (H ₂ O ₂ ) is thermally decomposed and reacts in a wet scrubber 2 to remove nitrogen oxides (NOx). The residual nitrogen oxide (NOx) that is not oxidized is sent back to the wet scrubber 2 through the recovery line 10.

_{2NO + 3H 2 O 2 ↔ 2H} + + 2NO 3 - + 2H 2 O

As shown in the above reaction formula, when nitrogen monoxide (NO) reacts with hydrogen peroxide (H ₂ O ₂ ), H + is produced, and when it increases, the rate of the reverse reaction of the reaction increases, and when it is removed, it is positively reacted by Le Chatelier's principle. NaOH is used for this because of the increased speed. An aqueous NaOH storage tank 6 is added to the recovery line 10 to add hydrogen peroxide (H ₂ O ₂ ) aqueous solution and NaOH.

According to another aspect of the invention,

A wet scrubber 2 having an exhaust gas outlet connected to an inlet and an exhaust line 9 connected to an outlet; A hydrogen peroxide (H ₂ O ₂ ) injection nozzle is installed at the end connected to the exhaust gas outlet and the inlet line 8, and a hydrogen peroxide (H ₂ O ₂ ) storage unit 5 connected to the recovery line 10; A sodium hydroxide (NaOH) storage 6 connected to the recovery line 10; And a water treatment system 3 connected to the discharge line 9 of the wet scrubber 2 and equipped with a pH controller 4, wherein the aqueous hydrogen peroxide (H ₂ O ₂ ) aqueous solution is in the wet scrubber. It is injected, and provides a NOx and SOx removal device in a wet scrubber in which thermal decomposition of hydrogen peroxide (H ₂ O ₂ ) is induced inside the exhaust gas outlet.

The purified water flowing through the water treatment system 3 may be mixed with hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) through the recovery line 10 and circulated back to the wet scrubber 2. In addition, sodium hydroxide (NaOH) is mixed at 0 to 0.03 mol / L, the pH controller 4 can adjust the pH of the aqueous solution to 7 to 9, sulfur oxide (SOx) and the outlet of the water treatment system 3 A nitrogen oxide (NOx) dust collection tank 7 may be additionally installed.

The contaminated water coming out of the reaction in the wet scrubber 2 can be sent to a water treatment system 3 for wastewater treatment through the discharge line 9. In addition, a pH controller 4 is applied to the water treatment system 3 to adjust the proper concentration of NaOH.

In addition, a process of adding NaOH to hydrogen peroxide (H ₂ O ₂ ) to increase the oxidation rate of nitrogen oxides by placing the NaOH storage tank 6 may be applied, and resupply to the wet scrubber 2 through the recovery line 10 Can be. In addition, the fine dust (PM), sulfur oxide, nitrogen oxide dust collection tank 7 is placed to store fine dust (PM), nitrogen oxides, sulfur oxides, etc., which are generated by water treatment.

The wet scrubber for ships 2 is a wet scrubber for ships for removing dust from exhaust gas generated in a heat engine, the housing having a chamber through which a cleaning liquid for cleaning the exhaust gas is injected, and the chamber with an exhaust gas inflow path It includes a thermoelectric module partition for dividing into the cleaning liquid storage unit, the thermoelectric module partition may be disposed in the chamber to have a high temperature portion in contact with the exhaust gas inlet side exhaust gas and a low temperature portion in contact with the cleaning liquid storage side side cleaning liquid. .

The principle of the wet scrubber is a device that separates particles from the flow of gas directly by washing the impregnated gas with droplets, liquid films, bubbles, etc., and adhering to the particles, promoting aggregation between particles. The general collecting principle of wet scrubbers is that particles collide with droplets, adhere to particles, intergranular aggregation by diffusion of particulates, intergranular aggregation by steam evaporation, promote vapor condensation and cohesiveness of particles into the nucleus, or particles contact with air bubbles It can be attached. The liquid used is mainly water, but in some cases, a surface active agent is used, and it is desirable to install a demister to prevent mist from being finally scattered to nearby areas.

In the present invention, hydrogen peroxide (H ₂ O ₂ ) is injected into the exhaust gas outlet through an injection nozzle. A plurality of spray nozzles can be installed depending on the processing capacity, and when multiple droplet spray nozzles are installed, the droplet spray angle is adjusted to prevent interference between droplets sprayed from different droplet spray nozzles, and the droplets are placed on the tank wall. Minimizing contact with can increase the efficiency of the reaction. The particle diameter of the droplet can be changed to 80 to 200 μm by adjusting the nozzle diameter of the droplet injection nozzle. The thermal decomposition reaction can be controlled by changing the particle size.

Pyrolysis of hydrogen peroxide (H ₂ O ₂ ) can effectively oxidize nitrogen oxides. Hydrogen peroxide (H ₂ O ₂ ) is thermally decomposed at about 300 ° C., preferably thermally decomposed uniformly with OH · at 450 to 550 ° C.

In the removal method using a NOx and SOx removal device in a wet scrubber using the thermal decomposition of the hydrogen peroxide, the thermal decomposition using the exhaust gas through the exhaust gas transfer line (H ₂ O ₂ ) and exhaust heat through the inlet line To do; Uniformly branching the exhaust gas flowing through the inlet (8) from the branching section (11) to each of the respective thrubbers; Oxidizing sulfur oxides (SOx) and nitrogen oxides (NOx) by the hydrogen peroxide (H ₂ O ₂ ) thermally decomposed in the scrubbers; Neutralizing H + generated in the oxidation step using sodium hydroxide (NaOH); A water treatment step of purifying the treated water coming through the neutralization reaction; And mixing the hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in water coming through the water treatment process and recovering it again with a wet scrubber.

At this time, it is characterized in that the pH in the water treatment system is adjusted within a range of 7 to 9 using a pH controller in the water treatment step.

And, it characterized in that it further comprises the step of collecting sulfur oxides (SOx) and nitrogen oxides (NOx) after the water treatment step.

According to another aspect of the invention,

Thermally decomposing hydrogen peroxide (H ₂ O ₂ ) using exhaust gas; The thermally decomposed hydrogen peroxide (H ₂ O ₂ ) oxidizing sulfur oxides (SOx) and nitrogen oxides (NOx) in a wet scrubber; Neutralizing H + generated in the oxidation step using sodium hydroxide (NaOH); A water treatment step of purifying water coming through the reaction; And mixing the hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) with water coming out through the water treatment process to recover it again with a wet scrubber. It provides a NOx and SOx removal process in the wet scrubber.

The pH controller 4 adjusts the pH inside the water treatment system 3 to 7 to 9, and further comprises a process of collecting sulfur oxides (SOx) and nitrogen oxides (NOx) after the water treatment process. Provides NOx and SOx removal process in the scrubber.

2 is a process simulation diagram according to an embodiment of the present invention.

In order to see the removal efficiency of SOx and NOx in the scrubber using H ₂ O ₂ aqueous solution, simulation was conducted through process simulation based on the target engine and general exhaust gas component data.

Since the temperature of the exhaust gas of the ship is high at about 350 ° C, NO can be oxidized by thermal decomposition of hydrogen peroxide (H ₂ O ₂₎ . Since the intermediate reaction between hydrogen peroxide (H ₂ O ₂₎ and NO proceeds very quickly, all reaction formulas cannot be used for process simulation. Therefore, process simulation can be performed using the reaction rate of the integrated reaction formula except for the following intermediate products. have.

Therefore, the present invention can calculate the required H ₂ O ₂ according to the removal of NOx at a given operating condition using the following integrated reaction formula of H ₂ O ₂ and NO.

3HNO ₂ ↔ HNO ₃ + 2NO + H ₂ O

HNO ₂ + H ₂ O ₂ → HNO ₃ + H ₂ O

∴ 2NO + 3H ₂ O ₂ → 2HNO ₃ + 2H ₂ O

Item Unit One 2 3 4 5 6 H2O2 consumption kmol / h 22.36 16.46 12.60 7.75 2.91 0.17 De-NO rate kmol / h 16.49 12.29 9.49 5.98 2.48 0.50 H2O2: NO ratio mol 1.36 1.34 1.33 1.29 1.17 0.34

Table 1 shows the amount of hydrogen peroxide (H ₂ O ₂ ) consumption that satisfies the NOx emission regulation. Since the molar ratio of H ₂ O ₂ : NO used in the present invention is 0.3 to 1.4, NOx emission regulation can be satisfied. Most preferred.

In the present invention, the mechanism of action for reducing nitrogen oxides and its reaction formula are as follows.

H ₂ O ₂ → 2OH (by Thermal-decomposition)

H ₂ O ₂ + · OH → HO ₂ · + H ₂ O

OH + OH → H ₂ O ₂

HO ₂ · + HO ₂ · → H ₂ O ₂ + O ₂

HO ₂ · + OH → H ₂ O + O ₂

NO + OH → HNO ₂

NO + OH → NO ₂ + H

NO ₂ + OH → HNO ₃

HNO ₂ + HOH → HNO ₃ + H

Hydrogen peroxide (H ₂ O ₂ ) decomposes to generate OH radicals. However, hydrogen peroxide (H ₂ O ₂ ) is not completely converted to OH radicals, and hydrogen peroxide (H ₂ O ₂ ) has the highest conversion rate to OH radicals at 430 ° C. under atmospheric pressure exhaust gas conditions. Thereafter, hydrogen peroxide (H ₂ O ₂ ) reacts with OH radicals to exist as water (H ₂ O) and HO ₂ . On the other hand, in general, 90 to 95% of nitrogen oxides generated in the combustion process are NO, and the rest are NO ₂ or N ₂ O.

Since the temperature of the exhaust gas of the engine is about 300 to 400 ° C, NO can be oxidized by thermal decomposition of hydrogen peroxide (H ₂ O ₂ ). When hydrogen peroxide (H ₂ O ₂ ) is injected into the exhaust gas from the engine, a part of hydrogen peroxide (H ₂ O ₂ ) is thermally decomposed to oxidize NO. NO which is not oxidized enters the wet scrubber and is oxidized to other nitrogen oxides by H ₂ O ₂ aqueous solution, dissolved in water and removed.

When the exhaust gas containing nitrogen oxide is brought into contact with hydrogen peroxide, HO ₂ and NO react and NO is converted into NO ₂ .

When water is injected into the reactant converted to NO ₂ , nitrogen oxides become an NO ₂ containing aqueous solution. Since NO ₂ is soluble in water, an aqueous solution containing NO _{2 is} easily obtained by spraying water.

In addition, NaOH is used to increase the oxidation rate of NO using a hydrogen peroxide (H ₂ O ₂ ) aqueous solution in a scrubber. The reasons for using NaOH are as follows.

When NO is oxidized, a large amount of H + is generated, and the higher the concentration of H + in the aqueous solution, the more favorable the reverse reaction is, so neutralize with OH- of NaOH to induce a positive reaction.

The following reaction scheme is a reaction scheme for neutralizing H + using NaOH.

NO + OH ↔ H + + NO _2-

2NO + 3H ₂ O ₂ ↔ 2H + + 2NO _3- + 2HO

When OH ^- ions generated by ionization of NaOH meet H ⁺ and cause oxidation / reduction reactions, H ⁺ is effectively removed, so NaOH can increase the oxidation rate of NO. As the amount of NaOH increases, the pH of the aqueous solution increases, and when it decreases, it decreases proportionally. The amount of NaOH is 0 to 0.03 mol / L, and it is preferable to adjust the pH according to the concentration, so that the aqueous solution maintains a weak alkali of pH 7 to 9.

In order to achieve the above object, a pH adjuster 4 may be applied inside the process.

The purpose of the pH regulator is to maintain a constant pH of the aqueous hydrogen peroxide (H ₂ O ₂ ) solution because the oxidation rate of NO changes depending on the concentration of NaOH. In addition, a water treatment system 3 may be used to purify an aqueous solution in which nitrogen oxides (NOx) and sulfur oxides (SOx) are dissolved.

The water passing through the water treatment system 3 is mixed with hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) through the recovery line 10 and then enters the scrubber again, and residual nitrogen oxides (NOx) and sulfur oxides that are not oxidized (SOx) can be removed once more to improve the removal efficiency.

The captured nitrogen oxide (NOx) -containing aqueous solution can be decomposed by wastewater treatment using microorganisms. Wastewater treatment using microorganisms is a long period of time leaving the NO ₂ NO ₂ ^- and this material is decomposed is used to feed the microorganisms.

In addition, the NO ₂ and sulfur oxides obtained above can be moved to a dust collection tank and stored. The aqueous solution containing NO ₂ is generally collected and stored in a pit, and it is preferable that the aqueous solution moving in the horizontal direction is bent so that the aqueous solution moving in the horizontal direction descends under load so that the aqueous solution containing NO ₂ is easily separated from other exhaust gas components.

Hereinafter, examples of the present invention will be described in more detail, but the present invention is not limited to these examples.

<Example 1> Exhaust gas analysis

Hydrogen peroxide (H ₂ O ₂ ) In order to see the removal efficiency of SOx and NOx in the scrubber using an aqueous solution, a simulation was conducted based on the engine exhaust gas component data Table 2 and Table 3.

Component Typical normalized N ₂ 75.80% 76.135% O ₂ 13.00% 13.057% H ₂ O 5.35% 5.374% CO ₂ 5.20% 5.223% SOx 600ppm 602.265ppm NOx 1500ppm 1506.663ppm etc. - Total. 99.56% 100%

Table 2 shows the exhaust gas components and process simulation data of a typical low-speed two-stroke engine. The above data shows that SOx and NOx are included in the exhaust gas components.

Power and rpm 39,938 kW x 73.6 rpm Exhaust gas temperature 365 ℃ Before turbine temperature 342 ℃ After turbine temperature 193 ℃ NOx 15.79 g / kWh

Table 3 shows the measured values of the target engine MAN 11S90ME-C9.2 (75% load). The exhaust gas temperature of the target engine 365 ° C. satisfies the decomposition conditions of hydrogen peroxide (H ₂ O ₂ ) that is thermally decomposed at about 300 ° C. can do.

<Example 2> SOx removal rate test

3 is a graph of NOx emission and SO ₂ removal according to the L / G ratio according to an embodiment of the present invention.

The L / G ratio represents the amount of water relative to the gas entering the scrubber.

Since SOx has a property of being soluble in water, the removal rate of SOx varies depending on the amount of water.

Therefore, looking through the results of FIG. 3, in order for the removal rate of SOx to be 99% ^{, the} ratio of L / G (unit = L / m ³⁾ is preferably 0.4.

<Example 3> Hydrogen peroxide to satisfy emission regulations (H ₂ O ₂ ) Consumption test

4 is a molar ratio of H ₂ O ₂ consumption and H ₂ O ₂ consumption: NO removal to satisfy NOx emission regulation according to an embodiment of the present invention.

The test was conducted using a process simulation. In the process simulation, HNO ₂ , an intermediate product of the reaction between hydrogen peroxide (H ₂ O ₂ ) and NO, was very unstable, so an integrated reaction scheme was used, and a general SOx reaction scheme was also used.

3HNO ₂ ↔ HNO ₃ + 2NO + H ₂ O

HNO ₂ + H ₂ O ₂ → HNO ₃ + H ₂ O

∴ 2NO + 3H ₂ O ₂ → 2HNO ₃ + 2H ₂ O

Item Unit One 2 3 4 5 6 H2O2 consumption kmol / h 22.36 16.46 12.60 7.75 2.91 0.17 De-NO rate kmol / h 16.49 12.29 9.49 5.98 2.48 0.50 H2O2: NO ratio mol 1.36 1.34 1.33 1.29 1.17 0.34

Table 4 shows the amount of hydrogen peroxide (H ₂ O ₂ ) consumption within the range that satisfies the NOx emission regulation through process simulation. Referring to FIG. 4 and Table 4, it can be seen that, as a result of the process simulation, the emission control of NOx can be satisfied when the molar ratio of H ₂ O ₂ : NO is about 0.3 to 1.4.

On the other hand, looking at Figures 8 to 11, Figures 8 to 9 shows the distribution of the exhaust gas inside the scrubber in the configuration of the existing wet scrubber, and FIGS. 10 to 11 are wet scrubbers according to an embodiment of the present invention. The configuration shows the distribution of exhaust gas inside the scrubber.

8 to 9, it can be seen that when the exhaust gas is introduced through the inflow formed at one place on one side of the existing wet scrubber, the exhaust gas tends to be concentrated on the opposite side of the inlet 8 in the wet scrubber. have.

Through this, it can be confirmed that the treatment is not uniformly performed inside the wet scrubber due to a phenomenon in which exhaust gas is biased to one side.

On the other hand, referring to Figures 10 to 11, when applying the configuration of the wet scrubber according to an embodiment of the present invention, unlike in FIGS. 8 to 9, it can be seen that the exhaust gas is relatively uniformly dispersed and distributed inside the wet scrubber. have.

1: engine 2: wet scrubber part
3: Water treatment system 4: pH adjuster
5: H ₂ O ₂ storage unit 6: NaOH storage unit
7: PM, sulfur oxide, nitrogen oxide dust collection tank 8: Inlet line
9: discharge line 10: recovery line
11. Branch 20: Scrubber

Claims (14)

In the NOx and SOx removal apparatus contained in the exhaust gas using a wet scrubber using the thermal decomposition of hydrogen peroxide,
1 / N distribution of exhaust gas introduced from the inlet port 8 through the exhaust gas transfer line and the exhaust gas introduced upwardly from the inlet port 8 upwardly. The radially branched portion 11 is provided,
A separate scrubber is provided at the end of each branch 11 in communication, the scrubber is provided with the same cross-section, and each scrubber is a wet scrubber part having a system for individually removing nitrogen oxides and sulfur oxides ( 2) and;
A water treatment system provided in communication with one side of the scrubber part, equipped with a ph regulator, and treating contaminated water discharged through a discharge line after a reaction process in the scrubber;
A recovery line for returning contaminated water including residual nitrogen oxides (NOx) and sulfur oxides (SOx), which were not oxidized even in the water treatment system, to the wet scrubber part 2 again;
A hydrogen peroxide storage unit communicating with the recovery line and supplying hydrogen peroxide (H ₂ O ₂ );
A sodium hydroxide storage unit communicating with the recovery line and supplying sodium hydroxide (NaOH);
The hydrogen peroxide storage unit and the sodium hydroxide storage unit is provided with an inlet line in communication with the exhaust gas transfer line,
Pyrolysis of hydrogen peroxide, characterized in that the exhaust gas introduced into the inlet (8) has a wet scrubber part (2) that is uniformly distributed to each scrubber through the branch part (11) to remove nitrogen oxides and sulfur oxides. NOx and SOx removal device in wet scrubber using
According to claim 1,
Hydrogen peroxide characterized by oxidizing a predetermined ratio of NO contained in the exhaust gas through thermal decomposition using a 300-400 ° C. exhaust heat source contained in the exhaust gas and hydrogen peroxide introduced into the exhaust gas transfer line through the inflow line. NOx and SOx removal device in wet scrubber using thermal decomposition.
According to claim 1,
The exhaust gas includes sulfur oxides (SOx) and nitrogen oxides (NOx), and the aqueous hydrogen peroxide (H ₂ O ₂ ) aqueous solution is sprayed in the wet scrubber part 2, and hydrogen peroxide (H) is inside the exhaust gas outlet. ₂ O ₂ ) NOx and SOx removal device in a wet scrubber using pyrolysis of hydrogen peroxide, characterized in that the thermal decomposition is induced.
According to claim 1,
The remaining amount of nitrogen oxide (NOx) in the treated water discharged from the water treatment system is mixed with hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in a predetermined ratio through the recovery line 10, and then again NOx and SOx removal device in the wet scrubber using the thermal decomposition of hydrogen peroxide, characterized in that the configuration is introduced into the wet scrubber part (2).
The method of claim 4,
The sodium hydroxide (NaOH) is 0 to 0.03mol / L NOx and SOx removal device in a wet scrubber using the thermal decomposition of hydrogen peroxide, characterized in that mixed.
The method of claim 4,
The pH controller (4) is NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide, characterized in that to adjust the pH of the aqueous solution to 7 to 9.
The method of claim 4,
A device for removing NOx and SOx in a wet scrubber using thermal decomposition of hydrogen peroxide, characterized in that a sulfur oxide (SOx) and nitrogen oxide (NOx) dust collection tank 7 is additionally installed at the outlet of the water treatment system 3.
According to claim 1,
The wet scrubber part 2,
An inlet (8) communicating with the exhaust gas transfer line and transferring the exhaust gas upward;
A branch 11 branched from the inlet 8 to a number of 1 / N, and branched radially with respect to a predetermined angle upward in the center of the inlet 8;
Each scrubber is provided in communication at each end of the branch 11, the scrubber is provided with the same cross-section, and each scrubber is provided as an independent treatment system,
NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide, characterized in that the combined cross-sectional shape of each of the scrubbers is provided in a circular, elliptical or polygonal shape around the central axis of the inlet (8).
The method of claim 8,
Each of the above-mentioned rubber is
Consists of a separate scrubber having a cross-sectional area of a predetermined angle around the central axis of the inlet (8), and by using the thermal decomposition of hydrogen peroxide, characterized in that provided with a wet scrubber portion having a circular cross-sectional area by combining the strever NOx and SOx removal device in wet scrubber.
The method of claim 8,
Each of the above-mentioned rubber is
Consists of an individual strut having a trapezoidal cross-sectional area that is radially widened by a predetermined angle around the central axis of the inlet 8, and the wetted thrubber part having a predetermined polygonal cross-sectional area by combining the strevers is provided. NOx and SOx removal device in a wet scrubber using the thermal decomposition of hydrogen peroxide, characterized in that.
According to claim 1,
The exhaust gas introduced into the inlet (8),
NOx in the wet scrubber using thermal decomposition of hydrogen peroxide, characterized in that the branch 11 is uniformly distributed to each of the scrubbers, and then uniformly treats exhaust gas flowing from each of the scrubbers into a separate system. And SOx removal device.
In the removal method using a NOx and SOx removal device in a wet scrubber using the thermal decomposition of hydrogen peroxide according to claim 1,
Thermally decomposing the exhaust gas through the exhaust gas transfer line using hydrogen peroxide (H ₂ O ₂ ) and exhaust heat introduced through the inlet line;
Uniformly branching the exhaust gas flowing through the inlet (8) from the branching section (11) to each of the respective thrubbers;
Oxidizing sulfur oxides (SOx) and nitrogen oxides (NOx) by the hydrogen peroxide (H ₂ O ₂ ) thermally decomposed in the scrubbers;
Neutralizing H + generated in the oxidation step using sodium hydroxide (NaOH);
A water treatment step of purifying the treated water coming through the neutralization reaction; And
Containing; including a step of mixing the hydrogen peroxide (H ₂ O ₂ ) and sodium hydroxide (NaOH) in the water coming out through the water treatment process again with a wet scrubber
Removal method using NOx and SOx removal device in wet scrubber using thermal decomposition of hydrogen peroxide.
The method of claim 12,
Removal method using a NOx and SOx removal device in a wet scrubber using thermal decomposition of hydrogen peroxide, characterized in that the pH inside the water treatment system is adjusted within a range of 7 to 9 using a pH controller in the water treatment step.
The method of claim 12,
A method for removing NOx and SOx in a wet scrubber using thermal decomposition of hydrogen peroxide, further comprising collecting sulfur oxides (SOx) and nitrogen oxides (NOx) after the water treatment step.

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