KR101601478B1 - Reducing agent mixing duct assembly - Google Patents

Abstract

The present invention relates to a reducing agent mixing duct assembly for mixing a reducing agent used in a selective catalytic reduction to an exhaust gas containing a nitrogen oxide (NOx). The reducing agent mixing duct assembly according to an embodiment of the present invention includes: a mixing duct which has an inlet in which an exhaust gas flows at one side, and has an outlet for discharging the exhaust gas at another side; a reducing agent spraying part for spraying a reducing agent by being inserted into the mixing duct; a hydrocarbon collection part which collects hydrocarbon by being arranged between the reducing agent spraying part and the inlet of the mixing duct; and a mixer which is arranged between the reducing agent spraying part and the outlet of the mixing duct, and mixes the reducing agent sprayed by the reducing agent spraying part and the exhaust gas.

Description

[0001] REDUCING AGENT MIXING DUCT ASSEMBLY [0002]

The present invention relates to a reducing agent mixing duct assembly, and more particularly, to a reducing agent mixing duct assembly for mixing a reducing agent used in a selective catalytic reduction reaction into an exhaust gas containing nitrogen oxides (NOx).

Generally, a power unit used for a ship or the like includes a low speed diesel engine and a turbocharger. A selective catalytic reduction (SCR) system is a system for reducing nitrogen oxides by purifying exhaust gases generated from a diesel engine.

The selective catalytic reduction system reacts the nitrogen oxides contained in the exhaust gas with the reducing agent while passing the exhaust gas and the reducing agent together in the reactor equipped with the catalyst, thereby reducing the nitrogen and the water vapor.

The reducing agent is injected from the reducing agent injection nozzle, moves inside the exhaust gas duct, and mixes and reacts with the exhaust gas.

The moving distance of the exhaust gas and the nitrogen oxide reducing agent (such as NH3 or Urea) is an important factor in the reduction of nitrogen oxides. It is necessary to secure a distance at which the nitrogen oxide reducing agent and the exhaust gas are sufficiently mixed and reacted until the nitrogen oxide reducing agent (such as NH3 or Urea) is injected into the exhaust gas duct and reaches the inlet of the reactor.

However, the length of the exhaust gas duct is also limited because the space in the engine room in the ship is narrow. Therefore, it is difficult to secure a mixing distance required for sufficiently mixing and reacting the exhaust gas with the nitrogen oxide reducing agent.

The exhaust gas generated while burning the fuel supplied to the marine engine contains not only nitrogen oxides but also contaminants such as carbon monoxide (CO) and hydrocarbons (HC) generated from incomplete combustion of fuels as well as soot particles . Therefore, reduction of pollution gases other than nitrogen oxides is also required.

In addition, the hydrocarbon contained in the exhaust gas causes carbon deposition on the catalyst for selective catalytic reduction reaction.

If the catalyst is immersed in the catalyst, the activity of the catalyst is lowered and the efficiency of the catalyst is lowered.

Embodiments of the present invention provide a reducing agent mixing duct assembly that not only efficiently mixes exhaust gas and reducing agent, but also reduces hydrocarbon.

According to an embodiment of the present invention, a reducing agent mixing duct assembly for mixing a reducing agent used in a selective catalytic reduction reaction with an exhaust gas containing nitrogen oxides (NOx) includes an inlet port through which exhaust gas is introduced into one side, A reducing agent spraying part inserted into the mixing duct and spraying a reducing agent, and a reducing agent spraying part disposed between the reducing agent spraying part and the inlet of the mixing duct to form hydrocarbons, And a mixer disposed between the reducing agent spraying unit and the outlet of the mixing duct to mix the reducing agent sprayed with the reducing agent spraying unit with the exhaust gas.

The hydrocarbon collecting part may include a wire mesh.

An auxiliary mixer may be installed in the hydrocarbon trapping part.

The reducing agent mixing duct assembly may further include a steam injecting unit disposed between the hydrocarbon collecting unit and the inlet of the mixing duct.

The reducing agent mixing duct assembly described above may further include a heating member for burning the captured hydrocarbons.

The reductant mixing duct assembly may include a first pressure sensor disposed in front of the mixing duct, a second pressure sensor disposed behind the mixing duct, and a second pressure sensor disposed downstream of the mixing duct in accordance with the differential pressure information provided by the first pressure sensor and the second pressure sensor. And a control unit for controlling the operation of the heating member.

According to an embodiment of the present invention, the reducing agent mixing duct assembly can effectively reduce the hydrocarbon as well as effectively mix the exhaust gas and the reducing agent.

1 is a configuration diagram of a reducing agent mixing duct assembly according to an embodiment of the present invention.
FIG. 2 is an enlarged front view of a portion of the hydrocarbon trapping unit used in the reducing agent mixing duct assembly of FIG. 1; FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

The drawings are schematic and illustrate that they are not drawn to scale. The relative dimensions and ratios of the parts in the figures are exaggerated or reduced in size for clarity and convenience in the figures, and any dimensions are merely illustrative and not restrictive. And to the same structure, element or component appearing in more than one drawing, the same reference numerals are used to denote similar features.

The embodiments of the present invention specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustration are expected. Thus, the embodiment is not limited to any particular form of the depicted area, but includes modifications of the form, for example, by manufacture.

Hereinafter, a reducing agent mixing duct assembly 101 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

1, the reducing agent mixing duct assembly 101 according to an embodiment of the present invention includes a mixing duct 200, a reducing agent spraying unit 400, a hydrocarbon trapping unit 300, and a mixer 800).

The reducing agent mixing duct assembly 101 according to an embodiment of the present invention includes a steam injecting unit 600, a steam supplying unit 650, a first pressure sensor 710, a second pressure sensor 720, a controller 700 ), And a reducing agent supply unit 450.

The mixing duct 200 provides a space for mixing the reducing agent used in the selective catalytic reduction reaction into the exhaust gas containing nitrogen oxides (NOx).

The mixing duct (200) has an inlet (201) through which exhaust gas flows into one side and an outlet (209) through which exhaust gas is discharged from the other side. The mixing duct 200 is formed to be larger than the exhaust passage through which the exhaust gas is expanded to suppress an increase in differential pressure. In particular, the mixing duct 200 can be enlarged to suppress the increase of the differential pressure by the hydrocarbon trapping unit 300 to be described later.

The reducing agent spraying unit 400 is inserted into the mixing duct 200 to spray a reducing agent into the mixing duct 200.

Specifically, the reducing agent spraying unit 400 may include a structure such as a nozzle or an injection grid. The reducing agent spraying unit 400 can spray a reducing agent such as urea, CO (NH ₂ ) ₂ ) aqueous solution, ammonia aqueous solution, and anhydrous ammonia.

The reducing agent injected from the reducing agent injecting section 400 is converted into gaseous ammonia and sufficiently mixed with the exhaust gas.

The reducing agent supply unit 450 is provided outside the mixing duct 200 to store and supply the reducing agent to be sprayed by the reducing agent spraying unit 400.

The mixer 800 is disposed between the reducing agent spraying unit 400 and the discharge port 209 of the mixing duct 200 to effectively mix the reducing agent sprayed by the reducing agent spraying unit 400 with the exhaust gas.

Specifically, the mixer 800 is decomposed and efficiently converted into gaseous ammonia, and is evenly mixed with the exhaust gas so that gaseous ammonia can be evenly distributed in the catalyst in the reactor for the selective catalytic reduction reaction.

The mixer 800 may be formed in various forms known to those skilled in the art.

The hydrocarbon trapping unit 300 is disposed between the reducing agent spraying unit 400 and the inlet of the mixing duct 200 to collect hydrocarbons.

In one embodiment of the present invention, the hydrocarbon trapping section 300 may include a wire mesh (310) as shown in FIG.

However, in one embodiment of the present invention, the shape of the wire mesh 310 that may be used is not limited to that shown in Fig. 2, but may have various shapes known to those skilled in the art.

In FIG. 2, the wire meshes 310 are overlapped with each other. However, the present invention is not limited thereto and may be overlapped with three or more wires.

In addition, the hydrocarbon trapping part 300 may further include a heating member 370 for burning the captured hydrocarbon. Specifically, the heating member 370 can heat the wire mesh 310 that captured the hydrocarbon using electric energy.

Although the wire mesh 310 and the heating member 370 are shown separately in FIG. 1, the wire mesh 310 may also serve as a heating member 370 by receiving electrical energy. That is, the wire mesh 310 and the heating member 370 can be integrally formed.

In addition, when the heating member 370 burns the captured hydrocarbon, the temperature of the exhaust gas passing through the mixing duct 200 can be raised by the heat energy generated by combustion of the hydrocarbon.

As described above, when the temperature of the exhaust gas rises, the reducing agent injected from the reducing agent injecting section 400 can be more easily converted into gaseous ammonia.

Further, since the temperature of the exhaust gas to be introduced into the reactor for the selective catalytic reduction reaction is raised, it is possible to secure a necessary temperature for the catalyst to be efficiently activated.

The catalyst used in the selective catalytic reduction reaction may be made of various materials known to those skilled in the art, such as zeolite (Zeolite), vanadium, and platinum. In one example, the catalyst may have an active temperature in the range of 250 degrees Celsius to 350 degrees Celsius. Here, the activation temperature refers to a temperature at which the catalyst can be stably reduced without being poisoned. When the catalyst reacts outside the active temperature range, the efficiency decreases as it is poisoned.

In particular, when exhaust gas flows having a relatively low temperature of less than 250 ° C, the catalyst poisoning material is generated by the ammonia of sulfur oxides in the exhaust gas (SOx) and a reducing agent (NH ₄₎ response. Catalyst poisoning material may comprise one or more of ammonium sulfate _{(Ammonium sulfate, (NH4) 2} SO 4) and ammonium bisulfite _{(Ammonium bisulfate, NH 4 HSO 4} ).

The catalyst poisoning material is adsorbed on the catalyst to lower the activity of the catalyst. That is, when the nitrogen oxide reduction efficiency is lowered, it can be judged that the catalyst is poisoned. Such catalyst poisonous materials can be decomposed or removed by an external heat source.

In addition, the heating member 370 of the hydrocarbon trapping unit 300 may continuously operate in addition to burning the captured hydrocarbon so that the heating member 370 directly raises the temperature of the exhaust gas.

In addition, the hydrocarbon trapping unit 300 may further include an auxiliary mixer 380 installed therein.

1, the auxiliary mixer 380 is disposed between the wire mesh 310 and the heating member 370. However, the auxiliary mixer 380 may be disposed between the wire mesh 310 and the heating member 370, As shown in FIG.

Further, when the wire mesh 310 and the heating member 370 are integrally formed, the auxiliary mixer 380 may be embedded in the wire mesh.

The auxiliary mixer 380 induces the formation of a vortex or vortex flow so that the reducing agent injected from the reducing agent injecting section 400 is effectively mixed with the exhaust gas.

The steam jetting unit 600 is disposed between the hydrocarbon trapping unit 300 and the inlet 201 of the mixing duct 200.

The steam injector 600 can inject a small amount of high-temperature steam into the exhaust gas directed to the hydrocarbon trapping unit 300 to wet the soot, thereby improving the collection efficiency of the hydrocarbon trapping unit 300.

The steam supply unit 650 supplies steam to the steam injection unit 600. The steam supply unit 650 may be provided separately, but it may utilize high temperature steam applied to the boiler from the ship or part of the cooling water used in the ship.

The first pressure sensor 710 is installed in front of the mixing duct 200 and the second pressure sensor 720 is installed in the rear of the mixing duct 200. The control unit 700 controls the operation of the heating member 370 according to the differential pressure information provided by the first pressure sensor 710 and the second pressure sensor 720.

Specifically, when the differential pressure information provided by the first pressure sensor 710 and the second pressure sensor 720 exceeds the reference value set in the normal range, the control unit 700 determines that the hydrocarbon trapped in the hydrocarbon trapping unit 300 is saturated It is determined that the differential pressure is increased by interrupting the flow of the exhaust gas, and the heating member 370 is operated to burn the hydrocarbon trapped in the hydrocarbon trapping section 300.

With such a construction, the reducing agent mixing duct assembly 101 according to an embodiment of the present invention can effectively reduce the hydrocarbon as well as effectively mix the exhaust gas and the reducing agent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be.

It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

101: Reductant Mixing Duct Assembly
200: mixing duct 201: inlet
209: Exhaust port 300: Hydrocarbon collecting section
310: wire mesh 370: heating member
380: auxiliary mixer 400: reducing agent jetting part
450: Reducing agent supply part 600: Steam injection part
650: steam supply unit 700: control unit
710: first pressure sensor 720: second pressure sensor

Claims (6)

A reducing agent mixing duct assembly for mixing a reducing agent used in a selective catalytic reduction reaction into an exhaust gas containing nitrogen oxides (NOx)
A mixing duct in which an inlet port through which exhaust gas is introduced into one side and an outlet through which exhaust gas is discharged is formed on the other side;
A reducing agent spraying part inserted into the mixing duct to spray a reducing agent;
A hydrocarbon trapping portion disposed between the reducing agent spraying portion and the inlet of the mixing duct to collect hydrocarbons; And
A mixer disposed between the reducing agent spraying unit and the outlet of the mixing duct for mixing the reducing agent sprayed by the reducing agent spraying unit with the exhaust gas;
/ RTI >
And an auxiliary mixer is installed in the hydrocarbon trapping part. The method of claim 1,
Wherein the hydrocarbon trapping portion comprises a wire mesh. delete The method of claim 1,
Further comprising a steam injector disposed between the hydrocarbon trap and the inlet of the mixing duct. The method according to any one of claims 1, 2, and 4,
Wherein the hydrocarbon trapping portion further comprises a heating member for burning the captured hydrocarbon. The method of claim 5,
A first pressure sensor disposed in front of the mixing duct;
A second pressure sensor disposed behind the mixing duct; And
A controller for controlling the operation of the heating member in accordance with the differential pressure information provided by the first pressure sensor and the second pressure sensor,
Further comprising a reducing agent mixing duct assembly.

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