CN214787621U

CN214787621U - High-efficient natural gas engine aftertreatment system

Info

Publication number: CN214787621U
Application number: CN202121211905.5U
Authority: CN
Inventors: 官维; 林铁坚; 盛利; 宁德忠; 刘志治
Original assignee: Guangxi Yuchai Machinery Co Ltd
Current assignee: Guangxi Yuchai Machinery Co Ltd
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2021-11-19
Anticipated expiration: 2031-06-01

Abstract

The utility model discloses a high-efficient natural gas engine aftertreatment system relates to engine aftertreatment technical field, solve the technical problem that current aftertreatment mode is difficult to realize ultralow emission, the system includes the engine, the blast pipe of engine has connected gradually binary TWC catalyst converter, the air draws the mechanism, the GOC catalyst converter, the SCR catalyst converter, the ASC catalyst converter, the input of binary TWC catalyst converter is equipped with first oxygen sensor, the output of binary TWC catalyst converter is equipped with the second oxygen sensor, the input of SCR catalyst converter is equipped with the third oxygen sensor, the output of SCR catalyst converter is equipped with the NOx sensor, the ECU of engine is electric connection air respectively and draws the mechanism, first oxygen sensor, the second oxygen sensor, the third oxygen sensor, the NOx sensor. The primary conversion is carried out through a binary TWC catalyst, the emission of NOx, HC and CO is controlled to a lower level, the oxygen concentration of tail gas is increased, and then the tail gas is further processed through a GOC catalyst and an SCR catalyst, so that the ultralow emission can be realized.

Description

High-efficient natural gas engine aftertreatment system

Technical Field

The utility model relates to an engine aftertreatment technical field, more specifically say, it relates to a high-efficient natural gas engine aftertreatment system.

Background

In order to meet the requirements of national six-emission regulations (GB17691-2018) of heavy-duty commercial vehicles and engines (emission limits require that NOx is controlled to be less than or equal to 0.46g/kWh, CH4 is less than or equal to 0.5g/kWh, NMHC is less than or equal to 0.16g/kWh and NH3 is less than or equal to 10ppm), the existing natural gas engine generally adopts a combustion technical route of equivalent weight + EGR + TWC + ASC. The engine firstly controls the primary NOx, NMHC, CH4 and CO to a certain level through the internal control technology such as engine body design, combustion optimization and external cooling EGR strategy, and then controls the total emission of the engine within the emission regulation limit of the state 6 by combining the external purification mode (TWC + ASC).

The current technical solution Three Way Catalyst (TWC) has high requirements for air-fuel ratio control accuracy (as shown in fig. 1): the maximum effective conversion windows of NOx, CO and CH4 are different to a certain extent, the conversion efficiency of NOx, CO and CH4 cannot be simultaneously maximized due to the fact that the concentration of exhaust gas is lean or rich, the existing scheme is limited by an air-fuel ratio window, ultra-low emission control is difficult to achieve, the overall emission of an engine is not large relative to the national six-emission limit value, the emission regulation at the next stage is met, the technical challenge exists, and particularly the durability of a catalyst is difficult to guarantee. Meanwhile, the ternary-TWC adopts three precious metal elements, wherein the control of NOx emission depends on expensive precious metal Rh to realize high-efficiency conversion, and the cost of the catalyst is high.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is not enough to the above-mentioned of prior art, the utility model aims at providing a can reduce high-efficient natural gas engine aftertreatment system of catalyst converter cost.

The technical scheme of the utility model is that: the utility model provides a high-efficient natural gas engine aftertreatment system, includes the engine, the blast pipe of engine has connected gradually binary TWC catalyst converter, air and has penetrated mechanism, GOC catalyst converter, SCR catalyst converter, ASC catalyst converter, binary TWC catalyst converter's input is equipped with first oxygen sensor, binary TWC catalyst converter's output is equipped with the second oxygen sensor, the input of SCR catalyst converter is equipped with the third oxygen sensor, the output of SCR catalyst converter is equipped with the NOx sensor, the ECU of engine electric connection respectively the air penetrates mechanism, first oxygen sensor, second oxygen sensor, third oxygen sensor, NOx sensor.

As a further improvement, the two-element TWC catalyst only adopts two noble metals of Pt and Pd.

Further, the air draws and penetrates the mechanism and includes venturi, venturi's outlet side is equipped with the air supplement pipe.

Furthermore, the air supply pipe is provided with an adjusting valve which is electrically connected with the ECU.

Furthermore, a one-way valve is arranged on the air supplementing pipe.

Further, an air filter is arranged at the input port of the air supply pipe.

Further, a DPF catalyst is arranged on an exhaust pipe between the GOC catalyst and the SCR catalyst.

Advantageous effects

Compared with the prior art, the utility model, the advantage that has does:

1. the utility model discloses earlier carry out preliminary conversion to NOx, HC and CO through binary TWC catalyst converter, with NOx, HC and CO emission control to lower level, increase tail gas oxygen concentration again, further high-efficient conversion HC and CO through the GOC catalyst converter, further handle NOx through the SCR catalyst converter, can realize ultralow emission.

2. The utility model discloses a binary TWC catalyst converter has only adopted two kinds of noble metals of Pt and Pd, has eliminated the reliance to noble metal Rh in the binary catalyst converter to make aftertreatment device have very big this space of falling on realizing ultralow emission.

Drawings

FIG. 1 is a schematic diagram of a TWC post-treatment reaction;

FIG. 2 is a schematic structural view of the present invention;

fig. 3 is a schematic structural view of the air injection mechanism of the present invention.

Wherein: the system comprises an engine 1, an exhaust pipe 2, a TWC catalyst 3-binary, an air injection mechanism 4, a GOC catalyst 5, an SCR catalyst 6, an ASC catalyst 7, a first oxygen sensor 8, a second oxygen sensor 9, a third oxygen sensor 10, an NOx sensor 11, a Venturi tube 12, a gas supplementing tube 13, a regulating valve 14, a check valve 15, an air filter 16 and a DPF catalyst 17.

Detailed Description

The invention will be further described with reference to specific embodiments shown in the drawings.

Referring to fig. 2 and 3, a high-efficient natural gas engine aftertreatment system, including engine 1, exhaust pipe 2 of engine 1 connects gradually binary TWC catalyst 3, air draws and penetrates mechanism 4, GOC catalyst 5, SCR catalyst 6, ASC catalyst 7, binary TWC catalyst 3's input is equipped with first oxygen sensor 8, binary TWC catalyst 3's output is equipped with second oxygen sensor 9, SCR catalyst 6's input is equipped with third oxygen sensor 10, SCR catalyst 6's output is equipped with NOx sensor 11, engine 1's ECU draws mechanism 4, first oxygen sensor 8, second oxygen sensor 9, third oxygen sensor 10, NOx sensor 11 of electric connection respectively.

After the tail gas is subjected to efficient oxidation reduction treatment by a binary TWC catalyst 3, the emission of NOx, CO and HC is controlled to a lower level, and the emission of CO and HC is controlled to an ultralow level by GOC combined with a Venturi air injection technology; the residual pollutant component in the tail gas from GOC is mainly NOx, the tail gas then enters SCR to react, NH3 in the SCR system is generated by decomposition of NH2CONH2 and H2O in urea solution at high temperature, and the reaction equation is as follows:

NH2CONH2+H2O->2NH3+CO2；

the reducing agent NH3 and NOx are subjected to high-efficiency reaction to reduce the NOx into N2 and H2O, wherein NO2 generated in GOC is beneficial to improving the conversion efficiency of SCR, and the reaction equation in the SCR is as follows:

NO+NO2+2NH3->2N2+3H2O；

4NO+O2+4NH3->4N2+6H2O；

2NO2+O2+4NH3->3N2+6H2O；

the tail gas continues to pass through the ASC, and unreacted NH3 in the SCR reacts with O2 to purify NH3 emissions to a lower level.

In this embodiment, the two-way TWC catalyst 3 uses only two precious metals, Pt and Pd, and eliminates the dependence on the precious metal Rh in the two-way catalyst, so that the aftertreatment device has a large cost reduction space in achieving ultra-low emissions.

Air draws and penetrates mechanism 4 and includes venturi 12, and the outlet side of venturi 12 is equipped with air supplement pipe 13, is equipped with electric connection ECU's governing valve 14 on the air supplement pipe 13, and the opening of control governing valve 14 can accurate control air supplement volume. The air supply pipe 13 is provided with a one-way valve 15 to prevent tail gas leakage. An air filter 16 is arranged at the input port of the air supply pipe 13, so that the cleanliness of air can be ensured.

Exhaust pipe 2 between GOC catalyst 5, the SCR catalyst 6 is equipped with DPF catalyst 17, can further reduce exhaust particulate matter and discharge, realizes the ultralow emission of tail gas.

The utility model discloses earlier carry out preliminary conversion to NOx, HC and CO through binary TWC catalyst converter, with NOx, HC and CO emission control to lower level, increase tail gas oxygen concentration again, further high-efficient conversion HC and CO through the GOC catalyst converter, further handle NOx through the SCR catalyst converter, can realize ultralow emission.

The above is only a preferred embodiment of the present invention, and it should be noted that for those skilled in the art, without departing from the structure of the present invention, several modifications and improvements can be made, which will not affect the utility of the invention and the utility of the patent.

Claims

1. The utility model provides a high-efficient natural gas engine aftertreatment system, includes engine (1), its characterized in that, blast pipe (2) of engine (1) have connected gradually binary TWC catalyst converter (3), air and have penetrated mechanism (4), GOC catalyst converter (5), SCR catalyst converter (6), ASC catalyst converter (7), the input of binary TWC catalyst converter (3) is equipped with first oxygen sensor (8), the output of binary TWC catalyst converter (3) is equipped with second oxygen sensor (9), the input of SCR catalyst converter (6) is equipped with third oxygen sensor (10), the output of SCR catalyst converter (6) is equipped with NOx sensor (11), the ECU of engine (1) electric connection respectively air penetrates mechanism (4), first oxygen sensor (8), second oxygen sensor (9), third oxygen sensor (10), An NOx sensor (11).

2. A high efficiency natural gas engine after treatment system according to claim 1, wherein the binary TWC catalyst (3) uses only two precious metals Pt and Pd.

3. The aftertreatment system of a high-efficiency natural gas engine according to claim 1, wherein the air injection mechanism (4) comprises a venturi tube (12), and an air supplement pipe (13) is arranged on the outlet side of the venturi tube (12).

4. A high efficiency natural gas engine after-treatment system as claimed in claim 3, wherein said air supply pipe (13) is provided with a regulating valve (14) electrically connected with said ECU.

5. A high efficiency natural gas engine after treatment system as claimed in claim 3, wherein said air supply pipe (13) is provided with a one-way valve (15).

6. A high efficiency natural gas engine after treatment system as claimed in claim 3, wherein the inlet of the air supply pipe (13) is provided with an air filter (16).

7. A high efficiency natural gas engine after treatment system according to claim 1, characterized in that the exhaust pipe (2) between the GOC catalyst (5), the SCR catalyst (6) is provided with a DPF catalyst (17).