CN114439577A

CN114439577A - Tail gas post-treatment device for non-road diesel engine

Info

Publication number: CN114439577A
Application number: CN202011212044.2A
Authority: CN
Inventors: 姜瑞霞; 常跃进; 刘洋; 张翔; 纪民; 许庆; 魏赛赛
Original assignee: Shanghai Gotek Catalyst Co ltd; Zhejiang Bondlye Environmental Technology Co ltd
Current assignee: Shanghai Gotek Catalyst Co ltd; Zhejiang Bondlye Environmental Technology Co ltd
Priority date: 2020-11-03
Filing date: 2020-11-03
Publication date: 2022-05-06

Abstract

An exhaust aftertreatment device for an off-road diesel engine comprising: a housing having an air inlet and an air outlet, an oxidation catalyst, and a particulate trap, wherein: the oxidation catalyst and the particle catcher are arranged inside the shell in sequence. The invention has the characteristics of three-dimensional net-shaped and porous structure, high porosity, large surface area, uniform pore size distribution and the like, has small back pressure and high filtering efficiency, enhances the retention time and contact area of the particles, and enables the particles to be captured in a large range when passing through; the invention adopts the technical scheme of carrying out surface aluminizing treatment on the metal carrier of the oxidation catalyst and the metal carrier of the particle catcher to improve the aluminum content of the surface layer of the carrier, improves the coating amount and the coating fastness of the catalyst coating, can effectively decompose the accumulated soot in time, greatly improves the purification performance of tail gas, and still obtains better purification effect after hydrothermal aging because the catalyst layer is firm, the catalyst has better durability and stronger stability.

Description

Tail gas post-treatment device for non-road diesel engine

Technical Field

The invention relates to a technology in the field of automobile exhaust emission, in particular to an exhaust aftertreatment device for a non-road diesel engine.

Background

The existing Diesel Particulate Filter (DPF) is mainly made of ceramic materials such as silicon carbide, cordierite and aluminum titanate, and the back pressure of an exhaust aftertreatment system is too high due to the thick wall thickness; the thin-wall ceramic carrier is fragile, so that higher requirements are put forward on the packaging technology and auxiliary materials; and is easily cracked by thermal shock due to poor heat-conducting property. The metal DPF developed at present mainly adopts a semi-permeable metal fiber felt and an inner core structure of a metal honeycomb, and the permeable open pore structure is difficult to control the concentrated emission of particulate matters. Due to increased emission requirements, it is desirable to coat more oxidation or selective reduction catalyst coatings and active components on metallic DPF carriers, as well as efficiently decompose accumulated soot, hydrocarbons, CO, or nitrogen oxides. However, the coating amount of the coating on the metal DPF is low, the coating fastness is insufficient, and the activity and the stability of the catalyst cannot meet the requirements.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the tail gas post-treatment device for the non-road diesel engine, which has the characteristics of three-dimensional net-shaped and porous structure, high porosity, large surface area, uniform pore size distribution and the like, has small back pressure and high filtration efficiency, enhances the retention time and contact area of particulate matters, and enables the particulate matters to be captured in a large range when passing through; the invention adopts the technical scheme of carrying out surface aluminizing treatment on the metal carrier of the oxidation catalyst and the metal carrier of the particle catcher to improve the aluminum content of the surface layer of the carrier, thereby improving the coating amount and the coating fastness of the catalyst coating, effectively decomposing the accumulated carbon smoke in time, greatly improving the purification performance of tail gas, and still obtaining better purification effect after hydrothermal aging because the catalyst layer is firm and has better durability and stronger stability.

The invention is realized by the following technical scheme:

the invention comprises the following steps: a housing having an air inlet and an air outlet, an oxidation catalyst, and a particulate trap, wherein: the oxidation catalyst and the particle catcher are arranged inside the shell in sequence.

The particle catcher comprises: a metal tube shell and a tube type filter or a fin type filter arranged in the metal tube shell.

The shell and tube filter comprises: a plurality of filter tubes, an inlet tube sheet, and an outlet tube sheet, wherein: the inlet tube plate and the outlet tube plate are respectively arranged at two ends of the filter tube so as to fix the position of the filter tube in the metal tube shell.

The finned filter is a plate-fin filter or a tube-fin filter. The plate-fin filter comprises: the plate-fin filter layers and the partition plates are arranged in a staggered mode; the tube and fin filter comprises: the tubular filter layer and the fin filter layer are vertical at equal intervals.

One end of the filter pipe is of a closed structure.

The inlet tube plate is of a closed structure, and the corresponding outlet tube plate is of a porous structure so that purified gas can be discharged.

The fin filter layer adopts an octagonal, hexagonal or quadrangular structure.

The oxidation catalyst includes: the catalyst layer comprises a carrier layer, an aluminized layer, a catalyst layer and an active component layer which are sequentially stacked.

The oxidation catalyst support layer comprises: a ceramic support or a metal support, wherein the metal support is based on a group VIII metal alloy, preferably an iron-chromium-aluminum alloy or a nickel-chromium-aluminum alloy.

The filtering layers of the tubular filter and the finned filter of the particle catcher are respectively composed of a metal particle catching carrier, an aluminizing layer, a catalyst layer and an active component layer which are sequentially stacked.

The filter metal particle trapping carrier of the particle trap is a sintered felt made of a plurality of layers of VIII group metal alloy wire nets, and iron-chromium-aluminum alloy or nickel-chromium-aluminum alloy is preferred.

The oxidation catalyst metal carrier and the particle catcher filter layer are subjected to surface aluminizing treatment to improve the surface aluminum content.

The oxidation catalyst metal carrier and the particle catcher filter layer are subjected to surface aluminizing treatment to improve the surface aluminum content. The aluminized layer is obtained by powder aluminizing, hot-dipping aluminizing or hot-spraying aluminizing.

The oxidation catalyst metal carrier and the aluminizing layer on the surface of the particle catcher filter layer are obtained by a powder aluminizing method.

The catalyst layer of the particle catcher filter comprises an oxidation catalyst and a selective reduction catalyst.

The oxidation catalyst and the oxidation type particle trap catalyst layer include: an alumina layer and a molecular sieve layer.

The molecular sieve in the catalyst layer of the oxidation catalyst and the oxidation type particle trap is preferably beta molecular sieve.

The active component layers of the oxidation catalyst and the oxidation type particle catcher are platinum catalyst layers, palladium catalyst layers or a combination thereof.

The selective reduction type particle trap catalyst active component is preferably a metal modified molecular sieve, and the selective reduction type particle trap catalyst active component metal is preferably metal Cu, metal Fe and a combination of metal Cu and Fe.

The molecular sieves include, but are not limited to, AEI, AFT, AFX, BEA, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MFI, MOR, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, WEN type molecular sieves, or combinations thereof.

The selective reduction type particle trap catalyst active component molecular sieve includes but is not limited to AEI, BEA, CHA type molecular sieves or combinations thereof.

The invention further relates to a preparation method of the tail gas post-treatment device, which comprises the following steps:

step 1: the sintered felt is made of fine VIII group metal fibers (the diameter is accurate to micrometer) with different wire diameters through non-woven paving, overlapping and high-temperature sintering, and is preferably iron-chromium-aluminum alloy or nickel-chromium-aluminum alloy.

Step 2: carrying out surface aluminizing treatment on the metal DOC carrier to obtain a metal DOC carrier with a high-aluminum-content surface; and (3) carrying out surface aluminizing treatment on the metal alloy sintered felt, and then cleaning to obtain the filter layer with the high-aluminum-content surface.

And step 3: and (3) manufacturing a filtering tube pass with a closed tail end by adopting the filtering layer obtained in the step (2), wherein the tail end is closed, tail gas enters the tube pass with the closed tail end and is manufactured by the filtering layer from the air inlet of the particle trap, and gas filtered and purified by the filtering layer is discharged from the outlet of the particle trap through the shell pass. The filtering tube side is of a tube array type or a fin type, and the fin type filtering layer is of a plate fin type or a fin tube type.

And 4, step 4: for an oxidation catalyst and an oxidation type particle trap, quantitative alumina, a molecular sieve and distilled water are mixed, corresponding auxiliaries are added to prepare slurry, quantitative platinum nitrate and palladium nitrate are added to adjust the pH, and uniform slurry is obtained after the slurry is subjected to a ball mill or a grinding mill. For the selective reduction type particle trap, a certain amount of metal modified molecular sieve and distilled water are mixed, corresponding auxiliary agents are added, slurry is prepared, the pH value is adjusted, and uniform slurry is obtained after the slurry is processed by a ball mill or a grinder.

And 5: and (3) coating the ceramic DOC carrier, the DOC metal carrier obtained in the step (2) and the filter layer of the particle trap obtained in the step (3) with the slurry obtained in the step (4).

Step 6: the oxidation catalyst and the particle trap are packaged as shown in FIG. 1, with particular attention to the flow direction of the DPF.

Technical effects

The particle catcher filter has the characteristics of three-dimensional net shape, porous structure, high porosity, large surface area, uniform pore size distribution and the like, and has high filtering efficiency and small back pressure. Through the improvement of the DOC carrier of the particle oxidation catalyst and the DPF of the particle trap, the coating amount, the coating strength and the durability and the stability of the DOC and the DPF are improved, and the DOC carrier has higher low-temperature activity and conversion efficiency on HC and CO; the Diesel Particulate Filter (DPF) has the advantages that the processing capacity of the DPF on pollutants in the tail gas of a diesel engine is improved, the function of collecting the polluted particles with great capacity is realized, large-range capture of the particles is realized when the particles pass through the DPF, the residence time and the contact area of the particles are enhanced, the working efficiency is improved, and the quality and the quantity of the particles are well reduced.

The catalyst has high coating amount and coating fastness, high activity and stability, and can effectively decompose accumulated carbon smoke in time and greatly improve the purification performance of tail gas. Through the improvement to particle trap, realized great ability and collected the function of polluting the particulate matter, realized catching on a large scale when making the particulate matter pass through to strengthened the dwell time and the area of contact of particulate matter, made the particulate matter decompose through the catalytic oxidation of the active component of catalyst on the firm catalyst layer, solved because the poor trap that causes of particulate matter entrapment effect blocks up the problem and the follow-up degree of difficulty that administers increases the problem, improved work efficiency. And because the catalyst layer is firm, the catalyst has better durability and stronger stability, and still obtains better purification effect after hydrothermal aging.

Drawings

FIG. 1 is a schematic structural diagram of a diesel exhaust aftertreatment device of the present invention;

FIG. 2 is a schematic cross-sectional view of the shell and tube particulate trap of the present invention;

FIG. 3 is a schematic cross-sectional structure diagram of the tubular particle trap of the present invention, wherein A is the inlet end and B is the outlet end, wherein the number of the tubular particles is determined according to the actual space and the requirement;

FIG. 4 is a schematic structural diagram of a plate-fin trap according to the present invention, wherein the number of the plate-fin filter layers is determined according to the actual space and the requirement;

FIG. 5 is a schematic structural view of a tube-fin trap according to the present invention, wherein the number of the tube-fin filter layers can be one or more according to the actual space and requirement;

FIG. 6 is a schematic structural view of a plate-fin filter;

FIG. 7(a) is a schematic structural view of a tube and fin filter; FIG. 7(b) is a cross-sectional view A-A of a tube and fin filter;

FIG. 8 is a schematic view of the surface structures of the oxidation catalyst layer of the metal carrier and the catalyst layer of the filter layer of the particle trap.

Detailed Description

As shown in fig. 1, the present embodiment relates to a diesel engine exhaust gas aftertreatment device, which includes: a housing 11 having an inlet 12 and an outlet 13, an oxidation catalyst 14 and a particle trap 15, wherein: an oxidation catalyst 14 and a particle trap 15 are arranged in this order inside the housing 11.

The carrier of the oxidation catalyst 14 includes: a ceramic support or a metal support.

The particle catcher 15 can be a shell and tube particle catcher or a fin particle catcher, wherein the fin particle catcher can be a plate fin particle catcher or a tube fin particle catcher.

As shown in fig. 2, the shell and tube type particle catcher comprises: a metal envelope 21 and a filter device 20 arranged inside it.

As shown in fig. 2, the filter device 20 includes: a plurality of filter tubes 23, an inlet tube sheet 22, and an outlet tube sheet 24, wherein: an inlet tube sheet 22 and an outlet tube sheet 24 are respectively provided at both ends of the filter tube 23 to fix the position of the filter tube 23 in the metal shell tube 21.

One end of the filter pipe 23 is of a closed structure.

The inlet tube sheet 22 is of a closed structure.

The outlet tube sheet 24 is of a porous structure to facilitate the discharge of the purified gas.

FIG. 3 is a schematic view of a tubular filter apparatus, wherein A is the inlet end and B is the outlet end.

As shown in fig. 4, the plate-fin particulate trap includes: a housing 41 with an air inlet and an air outlet and a plate-fin filter 42 disposed inside.

As shown in fig. 4 and 6, the plate-fin filter includes: the side strips 61, a plurality of plate-fin filter layers 62 and partition plates 63 are arranged in a staggered mode.

As shown in fig. 5 and 7, the tube-fin filter 52 includes: a tubular filter layer 71 and an equally spaced vertical fin filter layer 72.

The fin filter layer 72 is in an octagonal, hexagonal or tetragonal structure.

The metal carrier oxidation catalyst and the metal carrier particle catcher in the diesel engine tail gas aftertreatment device are shown in fig. 8, and comprise a metal carrier 81, an aluminized layer 82 on the surface of the metal carrier, a catalyst layer 83 coated on the aluminized layer 82, and a catalyst active component 84 loaded on the catalyst layer.

The metal carrier 81 is a sintered felt made of a group VIII metal alloy, but is not limited thereto.

The metal alloy is iron-chromium-aluminum alloy or nickel-chromium-aluminum alloy.

The oxidation type particle trap catalyst layer 83 includes: an alumina layer and a molecular sieve layer.

The molecular sieve layer in the oxidation type particle trap adopts but is not limited to beta molecular sieve.

The active component layer 84 in the oxidation type particle trap is a platinum catalyst layer, a palladium catalyst layer or a combination thereof.

The selective reduction type particle trap catalyst active component layer 84 is preferably a metal modified molecular sieve.

The selective reduction type particle catcher catalyst active component metal is preferably metal Cu, metal Fe and the combination of metal Cu and Fe.

The selective reduction type particle trap catalyst active component molecular sieve comprises but is not limited to AEI, AFT, AFX, BEA, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MFI, MOR, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, WEN type molecular sieve or combination thereof.

The selective reduction type particle trap catalyst active component molecular sieve comprises but is not limited to AEI, BEA, CHA type molecular sieve or the combination thereof.

The above device works by: the tail gas enters from the air inlet of the shell 11, enters the oxidation catalytic converter 14, decomposes the accumulated soot in time, enters the filtering device through the inlet of the particle catcher 15, enters the filtering device through the filtering pipe 23 of the tubular particle catcher, or the plate-fin filtering layer 62, or the metal particle catching carrier of the tubular filtering layer 71 and the fin filtering layer 72 for filtering, and carries out oxidation or selective reduction reaction on the catalytic layer on the carrier, the purified and filtered gas is discharged through the metal particle catching carrier 15, passes through the three-dimensional net structure to complete filtering, the purified gas is discharged through the outlet of the tubular shell of the metal particle catcher, and finally is released to the environment through the air outlet 13 of the shell 11.

And (3) detecting the performance of the catalyst:

an 3.298L off-road engine was used, which is originally listed in Table 1. Different oxidation catalysts and particle traps are installed, pollutants and PM are detected, and the purification performance is shown in table 2.

TABLE 13.298L original row of non-road engine

Contaminants	Original row, (g/kwh)
		CO	0.461
THC	0.229
		NOx	2.447
PM	0.094

Size of the post-treatment carrier: oxidation catalyst

400/6；DPF：

300/12。

TABLE 2 purification Performance of the exhaust gas aftertreatment device

The foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. An exhaust gas aftertreatment device for a non-road diesel engine, comprising: a housing having an air inlet and an air outlet, an oxidation catalyst, and a particulate trap, wherein: the oxidation catalyst and the particle catcher are arranged in the shell in sequence; the particle catcher comprises: the metal tube shell and a tube type filter or a fin type filter arranged in the metal tube shell;

the shell and tube filter comprises: a plurality of filter tubes, an inlet tube sheet, and an outlet tube sheet, wherein: the inlet tube plate and the outlet tube plate are respectively arranged at two ends of the filter tube so as to fix the position of the filter tube in the metal tube shell;

the finned filter is a plate-fin filter or a tube-fin filter;

the plate-fin filter comprises: the plate-fin filter layers and the partition plates are arranged in a staggered mode;

the tube and fin filter comprises: tubular filter layer and equidistant perpendicular fin filter layer.

2. The exhaust gas after-treatment device of the non-road diesel engine as claimed in claim 1, wherein one end of the filter pipe is a closed structure;

the inlet tube plate is of a closed structure, and the corresponding outlet tube plate is of a porous structure so that purified gas can be discharged conveniently;

the fin filter layer adopts an octagonal, hexagonal or quadrangular structure.

3. The exhaust after-treatment device of a non-road diesel engine as claimed in claim 1, wherein said oxidation catalyst comprises: carrier layer, aluminizing layer, catalyst layer and the active ingredient layer that stacks gradually, wherein the carrier layer includes: a ceramic support or a metal support, wherein the metal support is based on a group VIII metal alloy.

4. The exhaust gas after-treatment device of the off-road diesel engine according to claim 1, wherein the filter layers of the tubular filter and the fin filter of the particulate filter are composed of a metal particulate trapping carrier, an aluminized layer, a catalyst layer and an active component layer which are sequentially laminated.

5. The exhaust gas after-treatment device of the off-road diesel engine as claimed in claim 1, wherein the filter metal particle trapping carrier of the particulate trap is a sintered felt made of a plurality of layers of group VIII metal alloy wire mesh.

6. The exhaust gas after-treatment device of the off-road diesel engine according to claim 1, wherein the oxidation catalyst metal carrier and the particle trap filter layer are subjected to surface aluminizing treatment to increase the surface aluminum content, and the aluminized layer is obtained by powder aluminizing, hot dipping or hot spraying;

7. The exhaust after-treatment device of an off-road diesel engine as claimed in claim 1, wherein said particulate trap filter catalyst layer comprises an oxidation catalyst and a selective reduction catalyst;

8. The exhaust gas after-treatment device of the off-road diesel engine as claimed in claim 7, wherein the molecular sieve in the catalyst layer of the oxidation catalyst and the oxidation type particulate filter is a beta molecular sieve;

9. The exhaust after-treatment device of the off-road diesel engine of claim 7, wherein the catalyst active component is a metal modified molecular sieve; wherein the metal is Cu, Fe, or a combination of Cu and Fe; the molecular sieve is AEI, AFT, AFX, BEA, CHA, EAB, EMT, ERI, FAU, GME, JSR, KFI, LEV, LTL, LTN, MFI, MOR, MOZ, MSO, MWW, OFF, SAS, SAT, SAV, SBS, SBT, SFW, SSF, SZR, TSC, WEN type molecular sieve or a combination thereof.

10. The exhaust gas after-treatment device of the off-road diesel engine of claim 7, wherein the selective reduction type particulate trap catalyst active component molecular sieve is AEI, BEA, CHA type molecular sieve or a combination thereof.