KR101383310B1 - Apparatus for removing nitrogen oxides with multy layer cone type mesh filter and soot removing device - Google Patents

Abstract

According to the present invention, in the selective catalytic reduction method of nitrogen oxide removal, a multi-layered solid stainless steel filter is installed upstream of the reactor, and a large amount of exhaust gas is filtered and retained in the eye to maintain catalyst activity for a long time. In addition, the filtered soot of the solid filter may be backwashed by a pulsed air jet and the soot may be sucked away by a blower to the cyclone separator to remove soot, and the partial and gradual blocking effect of several gas flows in the solid filter may be removed. By spreading the gas streamline to the outside, a slight pressure difference is generated due to the flow resistance of the filter to increase the uniformity of the flow velocity distribution on the transverse cross-section so that the load on the catalyst layer is uniform to improve the nitrogen oxide removal efficiency. Equipped with multi-layer solid mesh filter and soot remover It relates to an exhaust gas treatment device of a diesel engine.

Description

TECHNICAL FIELD The exhaust gas treatment unit for diesel engines equipped with a multi-layer solid-state filter and the soot eliminator is made.

The present invention relates to a technique for removing soot in exhaust gas flowing into a reduction reactor of a selective catalytic reduction apparatus which is effectively applied as an exhaust pollutant purifier from a combustion apparatus, and at the same time improving the flow velocity uniformity at the catalyst inlet.

Diesel engines emit a lot of nitrogen oxides (hereinafter referred to as 'NOx') mainly composed of NO and NO2 due to the characteristics of combustion in the cylinder.

Selective Catalytic Reduction (SCR) (hereinafter referred to as SCR) is widely used as the most effective denitrification method to remove NOx.

In order to improve the NOx removal efficiency of the SCR, the use of a catalyst having high activity becomes a primary influence factor.

However, it is secondary but equally important to increase the homogeneity of the reducing agent at the catalyst inlet and to improve the uniformity of the flow rate is an important influence factor.

In order to increase the activity of the catalytic reduction group, the chemical composition of the catalyst material is primary, and secondly, it is necessary to prevent physicochemical poisoning of the catalyst.

Physical poisoning involves the filling of catalyst pores or even plugging of catalyst beds by soot consisting of ash and non-combustion generated from combustion of diesel engines.

In order to increase the homogeneity of the reducing agent at the inlet of the catalyst and to improve the uniformity of the flow velocity, a static mixer is installed in the front of the SCR reactor so that a vortex or a tumbling ) Or by mixing them at the same time and using a very long straight tube.

The exhaust of the diesel engine contains a relatively high level of particulate matter (PM), and this exhaust gas forms a relatively large soot by flocculation and coalescence while it flows through the exhaust pipe. In the city, many of them attach to and deposit on the wall of the pipe. Soot adhered and deposited under conditions such as sudden changes in the load of the engine are released and discharged into the stack along with the gas.If the SCR reactor is installed on the way to the stack, the SCR catalyst consists of a honeycomb channel of size 3-5mm. As a result, the catalyst may be blocked at the inlet of the catalyst or adhered to the middle of the passage, thereby significantly reducing the catalytic activity.

Addition of transverse vortex or longitudinal vortex to the flow, or simultaneous addition, improves to a satisfactory level in the homogeneity of the reducing agent. However, in terms of the uniformity of flow, the cross section of the inlet tube of the reactor is significantly smaller than the cross section of the reactor body and is located in the center of the cross section of the reactor, so that the streamline does not rapidly spread outward due to the flow inertia in the reactor inlet tube. Therefore, there is a problem that the streamline of the flow is concentrated at the center of the catalyst inlet end. To solve this problem, there is a method of causing the flow to spread by centrifugal force, but this also concentrates the position of the peak of the velocity distribution It was not only to move from the outer to the annular position on the outside, but also to improve the uniformity of the flow rate, but it was limited.

Domestic Patent Publication No. 10-2012-0057583 (published date: June 05, 2012)

A multi-layered stainless steel metal mesh is installed in front of the SCR catalyst bed, and the filtered amount is filtered by sequential filtering through the dense metal mesh from the coarse metal mesh while the exhaust gas flows from the upstream side to the downstream side. You can keep the soot in your eyes.

According to the present invention, the filtered soot can be aspirated and discharged using a period during which the SCR is not operated, and then removed using a cyclone separator, thereby repeatedly recovering the original device without opening the device and smoothly operating the SCR. It is to achieve the partial elimination effect of soot to a certain level.

In addition, the present invention is to install the solid stainless steel metal mesh of different angles so as to face the upstream direction of the flow of gas and step by step from the small angle of the solid while the exhaust gas flows from the upstream side to the downstream side. The gas streams are partially blocked by the filter net, and the gas streams are partially blocked by the filter net, and gradually diffused to the outside of the reactor, while a slight pressure difference before and after the filter caused by the flow resistance of the filter net is applied to the whole filter net. There is a tendency to be relatively uniform over, and the speed of the flow through the filter net is proportional to the square root of the pressure difference, and as a result, the effect of making the flow rate uniform in the cross section in the reactor is to be made available.

As a means for achieving the problem to be solved by the present invention, the exhaust gas treatment apparatus of a diesel engine for removing PM (particulate matter) contained in the exhaust gas of the diesel engine and reducing the nitrogen oxide with nitrogen,

A nitrogen oxide treatment unit for reducing and treating nitrogen oxide contained in exhaust gas generated from the diesel engine with nitrogen;

And a PM filter unit for collecting PM contained in exhaust gas discharged from the diesel engine between the nitrogen oxide processing unit and the diesel engine, and uniformly supplying the exhaust gas to the inlet side of the nitrogen oxide processing unit. do.

And the exhaust gas treatment apparatus of such a diesel engine,

A washing unit which sprays a cleaning gas to an outlet side of the nitrogen oxide processing unit and washes PM attached to the nitrogen oxide processing unit and the PM filter unit;

A PM collecting unit which sucks the washing gas discharged to the inlet side of the PM filter unit by the washing unit, removes the PM included in the washing gas, and discharges the washing gas from which the PM is removed to the inlet side of the PM filter unit; Characterized in that made.

SCR catalyst is blocked for a relatively long time by installing a large number of stages of stainless steel metal mesh at different stages of the SCR and allowing the exhaust gas to pass through the exhaust gas so that the size of soot particles is largely filtered and retained on the eyes. The phenomenon can be prevented and the original condition can be recovered by discharging using a soot separation device such as a pulsed air jet and a cyclone separator using the period during which the operation of the SCR is stopped, and the activity of the SCR catalyst can be maintained high.

In addition, due to the partial blocking effect on the flow of the multi-layered stainless steel filter net, the streamline is diffused outward and the flow rate is made more uniform due to a slight pressure difference due to the flow resistance of the filter net. By uniformizing the catalytic reaction load, the nitrogen oxide removal efficiency of the entire SCR can be improved.

1 is a schematic longitudinal sectional view of an apparatus for treating exhaust gas of a diesel engine according to an embodiment of the present invention;
2 is an exhaust gas flow chart in the configuration of FIG. 1;
3 is an enlarged view of a portion A of FIG. 1;
4 is a conceptual diagram of an exhaust gas treating apparatus of a diesel engine according to another embodiment of the present invention;
5 is a schematic longitudinal sectional view of a main part of the configuration of FIG. 4;
FIG. 6 is a flow chart of a cleaning gas in the configuration of FIG. 5. FIG.

The present invention is directed to the exhaust gas treatment apparatus (100) of a diesel engine for removing PM (particulate matter) contained in exhaust gas of a diesel engine and reducing nitrogen oxides with nitrogen. As a technique to improve the uniformity,

A nitrogen oxide processing unit 20 for reducing and treating nitrogen oxide contained in exhaust gas generated from the diesel engine with nitrogen;

PM filter unit 30 which collects PM contained in the exhaust gas discharged from the diesel engine between the nitrogen oxide processing unit 20 and the diesel engine and uniformly supplies the exhaust gas to the inlet side of the nitrogen oxide processing unit 20. );

The present invention relates to an exhaust gas treatment apparatus for a diesel engine equipped with a multi-layer solid-state mesh filter and a soot removal device.

The exhaust gas treatment apparatus 100 of the diesel engine injects a cleaning gas to the outlet side of the nitrogen oxide treatment unit 20 to wash the PM attached to the nitrogen oxide treatment unit 20 and the PM filter unit 30. Section 50;

The cleaning gas discharged to the inlet side of the PM filter unit 30 by the washing unit 50 is sucked, the PM included in the cleaning gas is removed, and the cleaning gas from which the PM is removed is removed from the PM filter unit 30. Characterized in that it further comprises; PM collection unit 60 for discharging to the inlet side.

In addition, the PM filter unit 30 is formed of a plurality of first filter holes 31a through which the exhaust gas passes, and a cross section having a cross section at a predetermined angle with respect to the center of the exhaust gas flow path flowing from the diesel engine. 1 filter 31; A plurality of second filter holes 32a through which the exhaust gas via the first filter 31 passes is formed, and a cross section is formed at an angle greater than that of the first filter 31 based on the center of the exhaust gas flow path. It is characterized in that it comprises a second filter 32, which is flared.

In addition, the washing unit 50, the jet nozzle 53 which is disposed in the outlet side direction of the nitrogen oxide processing unit 20; It characterized in that it comprises a; solenoid valve 51 for adjusting the injection amount of the cleaning gas injected into the jet nozzle (53).

In addition, the PM collecting unit 60, the suction unit 67 for sucking the cleaning gas discharged to the inlet side of the PM filter unit 30; A cyclone separator (61) for separating the PM contained in the cleaning gas sucked by the suction unit (67); A PM collection box 63 for collecting PM separated from the cyclone separator 61; And a return unit 68 for discharging the cleaning gas from which the PM is separated from the cyclone separator 61 to the initial cleaning gas suction point side of the suction unit 67.

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

≪ Example 1 >

1 is a schematic longitudinal cross-sectional view of an exhaust gas treating apparatus of a diesel engine according to an embodiment of the present invention, FIG. 2 is an exhaust gas flow chart in the configuration of FIG. 1, and FIG. 3 is an enlarged view of portion A of FIG. 1. .

1 to 3, the exhaust gas treatment apparatus 100 of a diesel engine includes an SCR reactor 13 and a static mixer 12. Reference numeral 11 denotes an exhaust gas inlet tube, and exhaust gas generated from a diesel engine is introduced, and reference numeral 14 denotes an exhaust gas outlet tube to discharge harmless exhaust gas into the atmosphere. On the other hand, the exhaust gas inlet pipe 11 side is called upstream of the exhaust gas, and the exhaust gas outlet pipe 14 side is called downstream of the exhaust gas.

The SCR reactor 13 includes a nitrogen oxide treatment unit 20 and a PM filter unit 30 to remove PM (particulate matter) contained in exhaust gas of a diesel engine and reduce nitrogen oxide to nitrogen. The static mixer 12 transversely vortexes the exhaust gas introduced from the exhaust gas inlet tube 11 so as to homogeneously mix the reducing agent supplied upstream to make the tube axis direction vector of the flow velocity in the pipe cross section uniform. Vortex the species and mix.

The nitrogen oxide processing unit 20 is configured to reduce nitrogen oxide contained in exhaust gas generated from a diesel engine to nitrogen, and includes a first catalyst layer 21 and a second catalyst layer 22, and uses a conventional configuration. do.

The PM filter unit 30 collects PM contained in the exhaust gas discharged from the diesel engine between the nitrogen oxide processing unit 20 and the static mixer 12, and discharges the exhaust gas to the inlet side of the nitrogen oxide processing unit 20. Supply uniformly. In detail, the PM filter unit 30 includes a plurality of first filter holes 31a through which the exhaust gas passes, and has a first cross section at a predetermined angle with respect to the center of the exhaust gas flow path flowing from the diesel engine. A filter 31 and a plurality of second filter holes 32a through which exhaust gas passes through the first filter 31 are formed, and the first filter 31 has a cross section based on the center of the exhaust gas flow path. The second filter 32 is formed at an angle larger than that, and the dust mixed in the exhaust gas is attached to the inner wall of the pipe throughout the exhaust gas pipe to aggregate and coalesce to form a relatively large PM. When the sudden change of the operating conditions of these can be separated by the gas flow to reach the inlet of the first and second catalyst layers (21, 22) is provided for the purpose of removing such PM.

The PM filter unit 30 is a multi-layered first and second filters 31 and 32, and the first filter hole 31a having a larger diameter in stages while the exhaust gas flows from the upstream side to the downstream side. The amount of PM to be collected by allowing the particles to flow from the first filter 31 having a diameter to the second filter 32 having a small diameter of the second filter hole 32a in a stepwise manner from the larger particles to the smaller PMs. Can be maximized.

In addition, as shown in FIGS. 2 and 3, the first and second filters 31 and 32 of the PM filter unit 30 have a cross section at a set angle θ1 and θ2 based on the center of the exhaust gas flow path. The second filter 32 is flared at a larger angle than the first filter 31. This is because the angle is gradually increased while going from upstream to downstream of the exhaust gas, so that the exhaust gas is concentrated in the central portion of the first and second catalyst layers 21 and 22 through a plurality of steps. Prevent it. That is, a slight pressure difference generated by the flow resistance of the multi-layered solid first and second filters 31 and 32 tends to be uniform over the entire cross section of the first and second filter 31 and 32, The first and second filters 31 and 32 according to the principle that the flow rate across the first and second filters 31 and 32 is proportional to the square root of the pressure difference between the first and second filters 31 and 32. The uniformity of the flow velocity of the downstream exhaust gas M3 via the first and second filters 31 and 32 is improved rather than the flow rate distribution of the exhaust gas M2 in the upstream.

≪ Example 2 >

4 is a conceptual diagram of an exhaust gas treating apparatus of a diesel engine according to another embodiment of the present invention, FIG. 5 is a schematic longitudinal cross-sectional view of an essential part of the configuration of FIG. 4, and FIG. 6 is a flow chart of a cleaning gas in the configuration of FIG. 5. to be.

Example 2 includes all of the configurations of Example 1, and further includes a washing unit 50 and a PM collecting unit 60.

The cleaning unit 50 is configured to wash the PM attached to the nitrogen oxide processing unit 20 and the PM filter unit 30 by spraying a cleaning gas to the outlet side of the nitrogen oxide processing unit 20, and the PM collection unit 60. ) Sucks the cleaning gas discharged to the inlet side of the PM filter unit 30 by the cleaning unit 50, removes the PM contained in the cleaning gas, and removes the PM gas from the PM filter unit 30. Is discharged to the inlet side.

Specifically, the washing unit 50 passes through the SCR reactor 13 and the nozzle line 52 installed inside the SCR reactor 13 and the nozzle line 52 toward the outlet side of the nitrogen oxide treatment unit 20. It consists of a jet nozzle 53 which is arranged in plural number and a solenoid valve 51 for adjusting the injection amount of the cleaning gas injected into the jet nozzle 53. The washing unit 50 is to restore the net function (exhaust gas flow rate uniformity and PM collection) of the PM filter unit 20 by washing the PM filled in the PM filter unit 20 with time, and in addition, the first , 2 washes the PM stuck to the catalyst layers (21, 22). Acceleration of air when ejecting through the jet nozzle 53 by opening the cleaning gas (eg, compressed air) at a pressure higher than the critical pressure ratio of the jet nozzle 53 by means of the solenoid valve 51 during the pulse period. The shock wave generated by this is applied to the first and second catalyst layers 21 and 22. The PM stuck to the first and second catalyst layers 21 and 22 is separated by the shock wave, and flows together with the exhaust gas in flow and is discharged to the exhaust gas outlet pipe 14. Since the marine SCR device does not need to operate the SCR device during berthing or sea navigation, the exhaust gas is discharged directly to the year by bypassing the SCR reactor 13 through a bypass valve not shown in the figure. PM, which is washed by using the liquid, and flows upstream, is sucked through the suction part 67 formed on the pipe wall circumference of the SCR reactor 13 to separate and remove the PM by centrifugal force in the cyclone separator 61. Opening the 62 and collecting it to the PM collection box 53, the clean cleaning gas is made by the return unit 68 discharged through the blower 64 to the initial cleaning gas suction point side of the suction unit 67.

By applying energy by the blower 54 and discharging the clean gas to the return unit 68, an upward air flow is formed upstream of the static mixer 12, so that the PM removed during the cleaning process is sucked before moving to the static mixer 12. It can lead to the part 67 side.

The controller 54 controls the solenoid valve 51 and the blower 64.

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 readily occur to those skilled in the art without departing from the spirit and scope of the invention. Therefore, it should be understood that the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense, and that the true scope of the invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof, .

100: exhaust gas treatment device 20: nitrogen oxide treatment unit
30: PM filter unit 50: washing unit
60: PM collecting part 31a: first filter hole
31: first filter 32: second filter
32a: second filter hole 51: solenoid valve
53: jet nozzle 61: cyclone separator
63: PM collection box 67: suction
68: return

Claims (5)

In the exhaust gas processing apparatus 100 of a diesel engine which removes PM (particulate matter) contained in exhaust gas of a diesel engine, and reduces and processes nitrogen oxide with nitrogen,
A nitrogen oxide processing unit 20 for reducing and treating nitrogen oxide contained in exhaust gas generated from the diesel engine with nitrogen;
PM filter unit 30 which collects PM contained in the exhaust gas discharged from the diesel engine between the nitrogen oxide processing unit 20 and the diesel engine and uniformly supplies the exhaust gas to the inlet side of the nitrogen oxide processing unit 20. Including;
The PM filter unit 30,
A first filter 31 formed with a plurality of first filter holes 31a through which the exhaust gas passes, and having a cross section opened at a predetermined angle with respect to the center of the exhaust gas flow path flowing from the diesel engine;
A plurality of second filter holes 32a through which the exhaust gas via the first filter 31 passes is formed, and a cross section is formed at an angle greater than that of the first filter 31 based on the center of the exhaust gas flow path. An open second filter 32;
Exhaust gas treatment apparatus for a diesel engine equipped with a multi-layer solid-state mesh filter and soot removal device, characterized in that comprises a. The method according to claim 1,
A washing unit (50) for washing the PM attached to the nitrogen oxide processing unit (20) and the PM filter unit (30) by injecting a cleaning gas to the outlet side of the nitrogen oxide processing unit (20);
The cleaning gas discharged to the inlet side of the PM filter unit 30 by the washing unit 50 is sucked, the PM included in the cleaning gas is removed, and the cleaning gas from which the PM is removed is removed from the PM filter unit 30. PM collecting unit 60 discharged to the inlet side;
The exhaust gas treatment apparatus of a diesel engine equipped with a multi-layer solid-state mesh filter and a soot removal device, characterized in that further comprises. 3. The method of claim 2,
The PM collecting unit 60,
A suction part 67 for sucking the cleaning gas discharged to the inlet side of the PM filter part 30;
A cyclone separator (61) for separating the PM contained in the cleaning gas sucked by the suction unit (67);
A PM collection box 63 for collecting PM separated from the cyclone separator 61;
A return unit 68 for discharging the cleaning gas from which the PM is separated from the cyclone separator 61 to the initial cleaning gas suction point side of the suction unit 67;
Exhaust gas treatment apparatus for a diesel engine equipped with a multi-layer solid-state mesh filter and soot removal device, characterized in that comprises a. 3. The method of claim 2,
The washing unit 50,
A jet nozzle 53 disposed in an outlet side direction of the nitrogen oxide treatment unit 20;
A solenoid valve 51 for adjusting the injection amount of the cleaning gas injected into the jet nozzle 53;
Exhaust gas treatment apparatus for a diesel engine equipped with a multi-layer solid-state mesh filter and soot removal device, characterized in that comprises a. delete

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