KR20220005663A - Apparatus for reducing air pollutant - Google Patents

Abstract

An apparatus for reducing exhaust pollutants is provided according to an embodiment of the present invention. The apparatus for reducing exhaust pollutants according to an embodiment of the present invention comprises: an exhaust pipe for discharging exhaust gas generated from a combustion engine that generates power by burning liquefied natural gas; a methane oxidation catalytic reactor that is installed in the exhaust pipe and oxidizes unburned methane contained in exhaust gas to carbon dioxide by including a methane oxidation catalyst; a selective catalytic reduction reactor installed in the exhaust pipe of the rear end of the methane oxidation catalytic reactor to reduce nitrogen oxides contained in exhaust gas; and a carbon dioxide collecting apparatus installed in a branch pipe branched from the exhaust pipe at the rear end of the selective catalytic reduction reactor to remove carbon dioxide contained in the exhaust gas, thereby capable of reducing unburned methane, nitrogen oxides, and carbon dioxide contained in exhaust gas.

Description

Apparatus for reducing air pollutant

The present invention relates to an exhaust pollutant reduction device, and more particularly, to an exhaust pollutant reducing device capable of reducing unburned methane, nitrogen oxides, and carbon dioxide contained in exhaust gas.

In general, various engines installed in ships generate power by burning fuel, and exhaust gas generated in the process of combustion of fuel includes nitrogen oxides, sulfur oxides, carbon dioxide, unburned methane, and the like. As air pollution increases, regulations on various harmful substances included in exhaust gas are becoming stricter, and not only nitrogen oxides and sulfur oxides, but also carbon dioxide are subject to emission regulations from the International Maritime Organization (IMO), the United Nations oxidation agency. are receiving In fact, from 2020, the International Maritime Organization limits the sulfur content of fuel to 0.5% in the global area as well as in the Emission Control Area (ECA). It is in the process of reducing it by 40% and reducing it by 70% by 2050.

On the other hand, in the case of nitrogen oxides, they are removed using a selective catalytic reduction reactor (SCR), and in the case of sulfur oxides, it is common to remove them using a wet scrubber. Since the wet scrubber has improved performance and price compared to the initial stage, there is no great difficulty in satisfying the regulations related to the sulfur content of fuel. However, it is difficult to satisfy the regulations related to the emission of carbon dioxide using the existing fuel efficiency reduction technology unless a low-carbon or de-carbonized fuel is used. In addition, unburned methane due to incomplete combustion of fuel is released into the atmosphere through a funnel, and discharging methane with a high Global Warming Potential (GWP) into the atmosphere without separate treatment is responsible for global warming. There is an aggravating problem.

Accordingly, there is a need for an exhaust pollutant reduction device capable of reducing unburned methane and carbon dioxide contained in exhaust gas.

Republic of Korea Patent Registration No. 10-1834488 (2018. 02. 26.)

An object of the present invention is to provide an exhaust pollutant reduction device capable of reducing unburned methane, nitrogen oxides, and carbon dioxide contained in exhaust gas.

The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Exhaust pollutant reduction apparatus according to an embodiment of the present invention for achieving the above technical problem is an exhaust pipe for discharging exhaust gas generated from a combustion engine generating power by burning liquefied natural gas, and is installed in the exhaust pipe, and methane A methane oxidation catalyst reactor for oxidizing unburned methane contained in the exhaust gas to carbon dioxide, including an oxidation catalyst, and a selective catalyst installed in the exhaust pipe at the rear end of the methane oxidation catalyst reactor to reduce nitrogen oxides contained in the exhaust gas It includes a reduction reactor, and a carbon dioxide collecting device installed in a branch pipe branched from the exhaust pipe at the rear end of the selective catalytic reduction reactor to remove carbon dioxide contained in the exhaust gas.

The methane oxidation catalyst reactor is a ceramic structure in which a methane oxidation catalyst made of one or more metals selected from platinum, palladium, rhodium, ruthenium, and cobalt is supported on a carrier made of one or more oxides selected from magnesium, aluminum, silica, and zirconia. It may include a porous support.

The methane oxidation catalytic reactor may be installed inside the selective catalytic reduction reactor.

The exhaust pollutant reduction device may further include a burner unit that receives the exhaust gas from the exhaust pipe at the rear end of the selective catalytic reduction reactor, heats it, and supplies it to the exhaust pipe at the front end of the methane oxidation catalyst reactor.

The exhaust pollutant reduction device may further include an air injection unit for desorbing impurities by injecting compressed air into the methane oxidation catalytic reactor and the selective catalytic reduction reactor, respectively.

The carbon dioxide collection device may include an absorption tower that injects an absorbent that absorbs carbon dioxide into the exhaust gas, and a regeneration tower that receives the absorbent in which carbon dioxide has been absorbed from the absorption tower and separates carbon dioxide from the absorbent.

The exhaust pollutant reduction device includes an economizer installed in the exhaust pipe to generate steam by exchanging heat with the exhaust gas, and a reboiler for heating the absorbent supplied to the regeneration tower using the steam generated by the economizer. may include more.

According to the present invention, by installing a methane oxidation catalyst reactor in the exhaust pipe, it is possible to oxidize unburned methane contained in the exhaust gas to carbon dioxide. As unburned methane is oxidized to carbon dioxide, it is possible to minimize the emission of methane, a greenhouse gas, into the atmosphere, thereby reducing the aggravation of global warming. In particular, as the methane oxidation catalytic reactor is installed inside the selective catalytic reduction reactor, the space inside the ship can be used more efficiently, and the ancillary equipment such as a burner unit and an air injection unit can be shared, thereby reducing costs. In addition, as the methane oxidation catalytic reactor is disposed close to the combustion engine, some of the waste heat generated from the combustion engine can be utilized for the catalytic reaction, thereby reducing costs.

In addition, by installing a carbon dioxide collecting device in a branch pipe branched from the exhaust pipe, it is possible to reduce carbon dioxide contained in the exhaust gas. In particular, since the reboiler heats the absorbent using the steam generated by the economizer, there is no need to operate a separate boiler for steam generation, thereby reducing energy consumption and preventing the generation of another carbon dioxide due to boiler operation. have.

1 is a diagram schematically showing the configuration of an exhaust pollutant reduction device according to an embodiment of the present invention.
FIG. 2 is a partially enlarged view of the exhaust pollutant reduction device of FIG. 1 .
3 is a diagram showing the configuration of a carbon dioxide trapping device.
4 and 5 are operational diagrams for explaining the operation of the exhaust pollutant reducing device.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, an apparatus for reducing exhaust pollutants according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5 .

Exhaust pollutant reduction device according to an embodiment of the present invention is a device for reducing the concentrations of unburned methane, nitrogen oxide, and carbon dioxide contained in exhaust gas, for example, is installed in a ship, the exhaust generated in the shipbuilding and marine fields It can be used to treat gases.

The exhaust pollutant reduction device may oxidize unburned methane contained in the exhaust gas to carbon dioxide by installing a methane oxidation catalyst reactor in the exhaust pipe. As unburned methane is oxidized to carbon dioxide, it is possible to minimize the emission of methane, a greenhouse gas, into the atmosphere, thereby reducing the aggravation of global warming. In particular, as the methane oxidation catalytic reactor is installed inside the selective catalytic reduction reactor, the space inside the ship can be used more efficiently, and the ancillary equipment such as a burner unit and an air injection unit can be shared, thereby reducing costs. In addition, as the methane oxidation catalytic reactor is disposed close to the combustion engine, some of the waste heat generated from the combustion engine can be utilized for the catalytic reaction, thereby reducing costs. In addition, by installing a carbon dioxide collecting device in a branch pipe branched from the exhaust pipe, it is possible to reduce carbon dioxide contained in the exhaust gas. In particular, since the reboiler heats the absorbent using the steam generated by the economizer, there is no need to operate a separate boiler for steam generation, thereby reducing energy consumption and preventing the generation of another carbon dioxide due to boiler operation. there is a characteristic

Hereinafter, the exhaust pollutant reducing device 1 will be described in detail with reference to FIGS. 1 to 3 .

1 is a diagram schematically showing the configuration of an exhaust pollutant reducing device according to an embodiment of the present invention, FIG. 2 is a partially enlarged view of the exhaust polluting pollutant reducing device of FIG. 1, and FIG. 3 is carbon dioxide capture It is a diagram showing the configuration of the device.

The exhaust pollutant reducing device 1 according to the present invention includes an exhaust pipe 10 , a methane oxidation catalytic reactor 20 , a selective catalytic reduction reactor 30 , and a carbon dioxide trapping device 40 .

The exhaust pipe 10 is a pipe for discharging exhaust gas generated from the combustion engine 100 , and one end is connected to the combustion engine 100 and the other end is connected to the communication (F). Since the combustion engine 100 generates power by burning fuel, exhaust gas according to the combustion of the fuel is generated, and the generated exhaust gas is discharged through the exhaust pipe 10 . At this time, since the exhaust gas contains a large amount of unburned methane, nitrogen oxides, and carbon dioxide, it must be removed and then discharged to the atmosphere.

A branch pipe (10a) is branched to the exhaust pipe (10), and the exhaust pipe (10) at the front end of the branch pipe (10a) has

A methane oxidation catalytic reactor 20 and a selective catalytic reduction reactor 30 are installed in series, and a carbon dioxide capture device 40 is provided in a branch pipe 10a branched from the exhaust pipe 10 at the rear end of the selective catalytic reduction reactor 30. is installed The methane oxidation catalytic reactor 20 has a reaction temperature of about 300 ° C to 600 ° C, and the selective catalytic reduction reactor 30 has a reaction temperature of about 200 ° C to 400 ° C, so the methane oxidation catalytic reactor 20 having a high reaction temperature is It may be installed in front of the selective catalytic reduction reactor 30 and disposed close to the combustion engine 100 . When the methane oxidation catalytic reactor 20 is disposed close to the combustion engine 100, some of the waste heat generated in the combustion engine 100 can be utilized for the catalytic reaction, thereby reducing costs.

The methane oxidation catalyst reactor 20 oxidizes unburned methane contained in exhaust gas to carbon dioxide, and may include a methane oxidation catalyst. More specifically, the methane oxidation catalyst reactor 20 is a methane oxidation catalyst consisting of one or more metals selected from platinum, palladium, rhodium, ruthenium, and cobalt on a carrier made of one or more oxides selected from magnesium, aluminum, silica, and zirconia. may include a porous support 21 that is a ceramic structure on which is supported. The methane oxidation catalyst may be supported on a support, prepared in a solution form by a binder, and then coated on the porous support 21, which is a ceramic structure. The porous support 21 may be formed in a honeycomb structure or a plate structure, as shown in FIG. 2 . Since the porous support 21 is formed in a honeycomb structure, the contact area with the exhaust gas may be increased to increase the oxidizing effect of unburned methane. The methane oxidation catalytic reactor 20 may be installed inside the selective catalytic reduction reactor 30 . As the methane oxidation catalytic reactor 20 is installed inside the selective catalytic reduction reactor 30, the space inside the ship can be used more efficiently, and ancillary equipment such as a burner unit 50 and an air injection unit 60 to be described later are shared. This can also reduce costs. Unburned methane contained in the exhaust gas may be oxidized by reacting according to the following reaction equation.

<reaction formula>

CH ₄ + 2O ₂ → CO ₂ + 2H ₂ O

_{(Here, O 2} used in the oxidation reaction of unburned methane may be oxygen contained in exhaust gas.)

In the exhaust gas in which unburned methane is oxidized in the methane oxidation catalytic reactor 20 , nitrogen oxides may be reduced in the selective catalytic reduction reactor 30 . The selective catalytic reduction reactor 30 may reduce nitrogen oxides contained in the exhaust gas to nitrogen and water by passing exhaust gas and ammonia through the catalyst layer 31 installed therein. The catalyst layer 31 may be formed in a honeycomb structure or a plate structure, like the porous support 21 . Since the selective catalytic reduction reactor 30 and the catalyst layer 31 are known techniques, detailed descriptions related to their structures will be omitted. The nitrogen oxides contained in the exhaust gas may be reduced by reacting according to the following reaction formula.

<reaction formula>

NO + NO ₂ + 2NH ₃ → 2N ₂ + 3H ₂ O

4NO + 4NH ₃ + O ₂ → 4N ₂ + 6H ₂ O

2NO ₂ + 4NH ₃ + O ₂ → 3N ₂ + 6H ₂ O

_{(Here, O 2} used in the reduction reaction of nitrogen oxides may be oxygen contained in the exhaust gas.)

Exhaust gas with reduced concentrations of unburned methane and nitrogen oxides moves along the exhaust pipe 10 and passes through the economizer 12, a part is released into the atmosphere through the flue F, and the remaining part is the branch pipe 10a ) may be introduced into the carbon dioxide collecting device 40 through the. The economizer 12 generates steam by heat-exchanging with the exhaust gas, and may supply the generated steam to a reboiler 43 to be described later.

A recovery pipe 11 may be branched from the exhaust pipe 10 at the rear end of the selective catalytic reduction reactor 30 . The recovery pipe 11 has an inlet end connected to the exhaust pipe 10 at the rear end of the selective catalytic reduction reactor 30 and an outlet end connected to the exhaust pipe 10 at the front end of the methane oxidation catalytic reactor 20, so that unburned methane and nitrogen Part of the exhaust gas with the reduced oxide concentration can be recovered. A burner unit 50 is installed in the recovery pipe 11 .

The burner unit 50 may receive the exhaust gas that has passed through the selective catalytic reduction reactor 30 and heat it together with fuel such as gas and oil, and supply it to the exhaust pipe 10 of the front end of the methane oxidation catalytic reactor 20 . The heat generated in the burner unit 50 is used to regenerate the porous support 21 of the methane oxidation catalytic reactor 20 or the catalyst layer 31 of the selective catalytic reduction reactor 30, or the methane oxidation catalytic reactor 20 or It can be used to react in the selective catalytic reduction reactor 30 or used to generate ammonia used in the selective catalytic reduction reactor 30 . More specifically, a blower 51 is installed on the recovery pipe 11 at the front end of the burner unit 50, and the blower 51 sucks some of the exhaust gas discharged from the selective catalytic reduction reactor 30, and the burner unit ( 50) can be supplied. If necessary, a flow meter (not shown) and a flow control valve (not shown) are installed in the recovery pipe 11 at the front end of the blower 51 to adjust the amount of exhaust gas supplied to the burner unit 50 . . A urea water decomposition unit 70 is installed in the recovery pipe 11 at the rear end of the burner unit 50 .

The urea water decomposition unit 70 may generate ammonia by heating the urea water with the heat of the exhaust gas supplied from the burner unit 50 . The urea water is stored in the urea water storage tank 72 , and may be injected into the urea water decomposition unit 70 by the urea water injection unit 71 . Ammonia generated by thermal decomposition of urea water is supplied to the front end of the methane oxidation catalyst reactor 20 through the recovery pipe 11, and a mixer 80 is installed at the connection point between the outlet end of the recovery pipe 11 and the exhaust pipe 10. Exhaust gas and ammonia can be easily mixed. For example, the mixer 80 may be formed of a plate having a curved surface or a plate twisted at an angle to induce mixing and rotational flow of exhaust gas and ammonia.

During the regeneration process of the porous support 21 or the catalyst layer 31, the urea water injection unit 71 stops the injection of urea water into the urea water decomposition unit 70, and accordingly, the urea water injection unit 71 is supplied from the burner unit 50. The heat of the exhaust gas may sequentially pass through the urea water decomposition unit 70 , the recovery pipe 11 , and the mixer 80 , and may be supplied into the selective catalytic reduction reactor 30 through the exhaust pipe 10 . When the heat of the burner unit 50 is supplied into the selective catalytic reduction reactor 30, foreign substances such as soot adsorbed on the surface of the porous support 21 or the catalyst layer 31 are burned to increase the catalytic reaction effect. can be When the porous support 21 or the catalyst layer 31 is used for a long time, various residues such as soot, fine dust (PM), by-products, oil oil, organic/inorganic compounds, and solid substances are adsorbed on the catalyst surface to reduce the reaction area. decreased, and thus, the catalytic reaction of unburned methane and nitrogen oxides is inevitably reduced. Accordingly, foreign substances are removed by periodically applying heat to the porous support 21 and the catalyst layer 31 . However, the porous support 21 and the catalyst layer 31 are not limited to being regenerated by the heat supplied from the burner unit 50, and the porous support 21 and the catalyst layer 31 are formed by the air injection unit 60. may be played.

The air injection unit 60 sprays compressed air into the methane oxidation catalytic reactor 20 and the selective catalytic reduction reactor 30, respectively, to desorb impurities attached to the catalyst surface. Separately from the regeneration process by the burner unit 50 It can be operated periodically to remove particulate or organic/inorganic impurities deposited on the catalyst. The air injection unit 60 includes a storage tank 61 , a plurality of nozzle pipes 62 , and a blower 63 . The storage tank 61 stores compressed air therein, and is installed outside the selective catalytic reduction reactor 30 . At this time, the storage tank 61 may receive compressed air from the outside and store it, or may generate and store compressed air by itself. The compressed air stored in the storage tank 61 is injected into the methane oxidation catalytic reactor 20 and the selective catalytic reduction reactor 30 through a plurality of nozzle pipes 62 , respectively. A blower 63 is installed on the nozzle tube 62 so that compressed air can flow smoothly. In the drawing, two nozzle pipes 62 are connected to the storage tank 61, and each nozzle pipe 62 passes through the selective catalytic reduction reactor 30 and is compressed under the porous support 21 and the catalyst layer 31. Although illustrated as a structure for spraying air, the present invention is not limited thereto, and the number and arrangement of the nozzle tubes 62 may be variously modified.

Meanwhile, the exhaust gas introduced into the carbon dioxide collecting device 40 through a blower (not shown) installed in the branch pipe 10a is subjected to a carbon dioxide removal process. As the exhaust gas with reduced concentrations of unburned methane and nitrogen oxides flows into the carbon dioxide capture device 40, the capacity of the carbon dioxide capture device 40 can be reduced, thereby reducing CAPEX (Capital Expenditures) and volume, Accordingly, there is an advantage of easy arrangement in the ship.

The carbon dioxide collecting device 40 removes carbon dioxide contained in exhaust gas, and includes an absorption tower 41 , a regeneration tower 42 , and a reboiler 43 .

The absorption tower 41 atomizes or atomizes an absorbent that absorbs carbon dioxide into the exhaust gas supplied through the branch pipe 10a and atomizes it and sprays it, where the absorbent refers to carbon dioxide It may be a solution having absorption properties, for example, an aqueous solution of an amine compound or ammonia. The absorption tower 41 may be formed as a gas contact type absorption tower to easily cope with the fluctuations of the ship. The exhaust gas is supplied to the lower portion of the absorption tower 41 and comes into contact with the absorbent sprayed from the upper portion of the absorption tower 41, whereby carbon dioxide contained in the exhaust gas may be absorbed by the absorbent and removed from the exhaust gas. The exhaust gas from which unburned methane, nitrogen oxides, and carbon dioxide are all removed is discharged to the outside through the upper part of the absorption tower 41. At this time, it may be joined to the exhaust gas discharged through the flue (F) and discharged to the outside, It can also be released independently. Since an exothermic reaction occurs when carbon dioxide is absorbed into the absorbent in the absorption tower 41, the exhaust gas discharged to the upper portion of the absorption tower 41 may be discharged to the outside after undergoing a separate cooling process. For example, the exhaust gas may be discharged after being cooled in contact with a cooling medium such as fresh water sprayed from the upper portion of the absorption tower 41 , and the cooling medium in contact with the exhaust gas is collected and discharged to the outside of the absorption tower 41 . After being discharged, it may be circulated back to the absorption tower 41 through a pressurization and cooling process. The absorbent that has absorbed carbon dioxide in the absorption tower 41 is supplied to the regeneration tower 42 through the supply line 41a.

The supply line 41a has one end connected to the lower portion of the absorption tower 41 and the other end connected to the upper portion of the regeneration tower 42, so that the absorbent absorbing carbon dioxide discharged from the absorption tower 41 is transferred to the upper portion of the regeneration tower 42. can supply A pump 41b for pressurizing the absorbent for absorbing carbon dioxide and a heat exchanger 41c for exchanging heat between the supply line 41a and a second circulation line 42b to be described later may be installed on the supply line 41a. The heat exchanger 41c heats the absorbent that has absorbed carbon dioxide at about 40 to 50° C. discharged from the absorption tower 41 with the absorbent from which carbon dioxide of about 80 to 150° C. discharged from the regeneration tower 42 is separated. do. That is, the heat exchanger 41c includes the absorbent supplied from the absorption tower 41 to the regeneration tower 42 through the supply line 41a, and the absorption tower from the regeneration tower 42 through the second circulation line 42b ( By exchanging the absorbent circulated to 41), the temperature of the absorbent supplied to the regeneration tower 42 is increased and the temperature of the absorbent circulated to the absorption tower 41 is lowered. Accordingly, carbon dioxide can be easily absorbed by the absorbent in the absorption tower 41 , and carbon dioxide can be easily separated from the absorbent in the regeneration tower 42 . The absorbent that has absorbed the carbon dioxide heated in the heat exchanger 41c may be introduced into the upper portion of the regeneration tower 42 .

The regeneration tower 42 receives an absorbent that has absorbed carbon dioxide from the absorption tower 41 and separates carbon dioxide from the absorbent. More specifically, the absorbent absorbing carbon dioxide supplied to the upper portion of the regeneration tower 42 after being heated in the heat exchanger 41c flows from the upper portion of the regeneration tower 42 to the lower portion, and carbon dioxide is separated by thermal energy. At this time, some of the absorbent in the regeneration tower 42 is introduced into the reboiler 43 through the first circulation line 42a and is heated, and carbon dioxide and vapor generated from the absorbent by the heating of the reboiler 43 are It is supplied to the regeneration tower 42 through the first circulation line 42a to provide additional thermal energy and increase the separation efficiency of carbon dioxide. As described above, the absorbent supplied to the regeneration tower 42 is heated in the heat exchanger 41c, and carbon dioxide and steam generated from the absorbent heated in the reboiler 43 additionally provide thermal energy, so carbon dioxide can be easily separated from the absorbent. The high-concentration carbon dioxide separated from the absorbent is discharged to the upper portion of the regeneration tower 42, passes through the condenser 42c and the reflux drum 42d in sequence, moisture is removed, and may be supplied as needed through a separate compression process. The water separated from the carbon dioxide is pressurized and circulated back to the regeneration tower 42 .

The reboiler 43 heats the absorbent supplied to the regeneration tower 42 using the steam generated by the economizer 12 described above, and circulates the absorbent discharged from the regeneration tower 42 back to the regeneration tower 42 . It may be installed on the first circulation line (42a). In other words, the reboiler 43 is installed on the first circulation line 42a and heats the absorbent flowing through the first circulation line 42a with steam supplied from the economizer 12 to generate carbon dioxide and steam, and It is supplied to the regeneration tower 42 . At this time, the steam may be supplied through the steam supply pipe (12a). By supplying steam generated from waste heat of exhaust gas to the reboiler 43 and using it as a heat source, not only the overall system efficiency is improved, but also energy consumption can be reduced because there is no need to operate a separate boiler for steam generation, Another generation of carbon dioxide due to the operation of the boiler can be prevented.

Meanwhile, the second circulation line 42b may also be connected to the regeneration tower 42 . The second circulation line 42b circulates the absorbent discharged from the regeneration tower 42 to the absorption tower 41, and the above-described heat exchanger 41c, the pump 421, and the cooler 422 are installed. can The absorbent from which carbon dioxide at about 80 to 150° C. discharged from the regeneration tower 42 through the second circulation line 42b is separated is primarily cooled by exchanging heat with the absorbent flowing through the supply line 41a in the heat exchanger 41c. And, after being pressurized by the pump 421, the second cooling in the cooler 422 may be supplied to the absorption tower 41 at about 30 ~ 50 ℃.

Hereinafter, the operation of the exhaust pollutant reducing device 1 will be described in more detail with reference to FIGS. 4 and 5 .

4 and 5 are operational diagrams for explaining the operation of the exhaust pollutant reducing device.

The exhaust pollutant reduction device 1 according to the present invention may oxidize unburned methane contained in the exhaust gas to carbon dioxide by installing the methane oxidation catalytic reactor 20 in the exhaust pipe 10 . As unburned methane is oxidized to carbon dioxide, it is possible to minimize the emission of methane, a greenhouse gas, into the atmosphere, thereby reducing the aggravation of global warming. In particular, as the methane oxidation catalytic reactor 20 is installed inside the selective catalytic reduction reactor 30, the space inside the ship can be used more efficiently, and the ancillary equipment such as the burner unit 50 and the air injection unit 60 is shared. You can do this to reduce costs. In addition, as the methane oxidation catalytic reactor 20 is disposed close to the combustion engine 100, some of the waste heat generated in the combustion engine 100 can be utilized for the catalytic reaction, thereby reducing costs. In addition, by installing the carbon dioxide collecting device 40 in the branch pipe 10a branched from the exhaust pipe 10, it is possible to reduce the carbon dioxide contained in the exhaust gas. In particular, since the reboiler 43 heats the absorbent using the steam generated by the economizer 12, there is no need to operate a separate boiler for steam generation, thereby reducing energy consumption and another carbon dioxide can also be prevented.

4 is an operational diagram illustrating a purification process of exhaust gas, and FIG. 5 is an operational diagram illustrating a regeneration process of a methane oxidation catalytic reactor and a selective catalytic reduction reactor.

First, referring to FIG. 4 , the exhaust gas generated from the combustion engine 100 is

The methane oxidation catalytic reactor 20 and the selective catalytic reduction reactor 30 are discharged to the exhaust pipe 10 installed in series and mixed with ammonia in the mixer 80 . Ammonia is supplied from the urea water decomposition unit 70 through the recovery pipe 11, and the urea water decomposition unit 70 receives the urea water injected from the urea water injection unit 71 with heat supplied from the burner unit 50. It can be heated to produce ammonia. In an initial state in which there is no exhaust gas supplied to the burner unit 50 through the recovery pipe 11 , outside air is separately introduced into the burner unit 50 to be heated together with fuel and generate heat.

The exhaust gas and ammonia mixed in the mixer 80 pass through the porous support 21 of the methane oxidation catalytic reactor 20 . The porous support 21 is a ceramic structure in which a methane oxidation catalyst made of one or more metals selected from platinum, palladium, rhodium, ruthenium, and cobalt is supported on a support made of one or more oxides selected from magnesium, aluminum, silica, and zirconia. Unburned methane contained in the exhaust gas may react with oxygen in the methane oxidation catalyst to be oxidized to carbon dioxide. The exhaust gas in which unburned methane is oxidized to carbon dioxide passes through the catalyst layer 31 of the selective catalytic reduction reactor 30 disposed at the rear end of the porous support 21 together with ammonia, and at this time, nitrogen oxides contained in the exhaust gas It can be reduced to nitrogen and water by reacting with ammonia and oxygen contained in the exhaust gas. A part of the exhaust gas containing carbon dioxide, nitrogen, and water may move to the exhaust pipe 10 , and the remaining part may be introduced into the recovery pipe 11 by the blower 51 . The exhaust gas introduced into the recovery pipe 11 is supplied to the burner unit 50 and heated together with fuel to generate heat, and the heat generated in the burner unit 50 is transferred to the urea water decomposition unit through the recovery pipe 11 . (70) can be supplied. When exhaust gas is supplied to the burner unit 50 , the inflow of outside air may be stopped.

On the other hand, the exhaust gas moving to the exhaust pipe 10 passes through the economizer 12, a part is branched into the branch pipe 10a, and the remaining part is discharged to the atmosphere through the communication pipe (F). The steam generated by the economizer 12 is supplied to the reboiler 43 through the steam supply pipe 12a to be used for heating the absorbent.

The exhaust gas branched into the branch pipe 10a passes through the absorption tower 41 and the regeneration tower 42 sequentially to remove carbon dioxide, and the exhaust gas from which all unburned methane, nitrogen oxides, and carbon dioxide are removed is the absorption tower 41 ) is discharged to the outside through the upper part. At this time, the exhaust gas discharged through the upper absorption tower 41 may be discharged to the outside by joining the exhaust gas discharged through the flue F, or may be discharged independently.

When the porous support 21 and the catalyst layer 31 are used for a long time through this series of processes, various residues such as soot, fine dust (PM), by-products, oil oil, organic/inorganic compounds, and solid substances become catalysts. It is adsorbed on the surface and the reaction area is reduced. If the reaction area of the catalyst is reduced, the catalyst reaction is lowered and the effect of reducing pollutants is reduced, so the catalyst must be regenerated. Therefore, as shown in (a) of Figure 5, the heat generated in the burner unit 50 is supplied to the inside of the selective catalytic reduction reactor 30 and adsorbed on the surface of the porous support 21 and the catalyst layer 31 Foreign substances such as soot can be burned. During the catalyst regeneration process, the inflow of exhaust gas to the exhaust pipe 10 in which the selective catalytic reduction reactor 30 is installed is stopped, and the exhaust gas flows to a bypass pipe (not shown) that bypasses the selective catalytic reduction reactor 30. can In addition, the urea water injection unit 71 may also stop the injection of the urea water into the urea water decomposition unit 70 .

The air injection unit 60 operates periodically separately from the catalyst regeneration process by the burner unit 50 to supply compressed air to the porous support 21 and the catalyst layer 31 as shown in FIG. can be sprayed As the compressed air is sprayed, the deposited particulate or organic/inorganic impurities attached to the surface of the catalyst are detached, and the catalyst can be regenerated.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains can realize that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

1: Exhaust pollutant reduction device
10: exhaust pipe 10a: branch pipe
11: Recovery Building 12: Economizer
12a: steam supply pipe 20: methane oxidation catalyst reactor
21: porous support 30: selective catalytic reduction reactor
31: catalyst layer 40: carbon dioxide trapping device
41: absorption tower 42: regeneration tower
43: reboiler 50: burner unit
51: blower 60: air injection unit
61: storage tank 62: nozzle pipe
63: blower 70: urea water decomposition unit
71: urea water injection unit 72: urea water storage tank
80: mixer
100: combustion engine
F: flue

Claims (7)

an exhaust pipe for discharging exhaust gas generated from a combustion engine that generates power by burning liquefied natural gas;
a methane oxidation catalyst reactor installed in the exhaust pipe and oxidizing unburned methane contained in the exhaust gas to carbon dioxide, including a methane oxidation catalyst;
A selective catalytic reduction reactor installed in the exhaust pipe at the rear end of the methane oxidation catalytic reactor to reduce nitrogen oxides contained in the exhaust gas, and
and a carbon dioxide collecting device installed in a branch pipe branched from the exhaust pipe at the rear end of the selective catalytic reduction reactor to remove carbon dioxide contained in the exhaust gas. According to claim 1, wherein the methane oxidation catalytic reactor,
Exhaust pollution comprising a porous support as a ceramic structure in which a methane oxidation catalyst made of one or more metals selected from platinum, palladium, rhodium, ruthenium, and cobalt is supported on a carrier made of one or more oxides selected from magnesium, aluminum, silica, and zirconia. Substance abatement device. 3. The method of claim 2,
The methane oxidation catalytic reactor is an exhaust pollutant reduction device installed inside the selective catalytic reduction reactor. 3. The method of claim 2,
The exhaust pollutant reduction apparatus further comprising a burner unit receiving the exhaust gas from the exhaust pipe at the rear end of the selective catalytic reduction reactor, heating it, and supplying it to the exhaust pipe at the front end of the methane oxidation catalyst reactor. 3. The method of claim 2,
Exhaust pollutant reduction device further comprising an air injection unit for desorbing impurities by injecting compressed air into the methane oxidation catalytic reactor and the selective catalytic reduction reactor, respectively. According to claim 1, wherein the carbon dioxide collecting device,
an absorption tower for spraying an absorbent for absorbing carbon dioxide into the exhaust gas;
and a regeneration tower configured to receive the absorbent in which carbon dioxide has been absorbed from the absorption tower and separate carbon dioxide from the absorbent. 7. The method of claim 6,
an economizer installed in the exhaust pipe and heat-exchanged with the exhaust gas to generate steam;
The exhaust pollutant reduction apparatus further comprising a reboiler for heating the absorbent supplied to the regeneration tower by using the steam generated by the economizer.

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