CN204572125U - A kind of diesel engine vent gas cleaning system - Google Patents

Abstract

The utility model relates to a diesel engine post-treatment system, in particular to a diesel engine tail gas purification system, comprising an oxidation catalyst, a diesel particle filter and a selective catalytic reduction device, the oxidation catalyst and the diesel particle filter are connected in series and packaged in an integrated In the casing and the oxidation catalyst is located upstream of the diesel particulate filter, the air inlet of the integrated casing is connected to the exhaust pipe I, and the gas outlet of the integrated casing is connected to the inlet of the selective catalytic reduction device through the exhaust pipe II. The gas outlet of the selective catalytic reduction device is connected with the outside through the exhaust pipe III; the exhaust pipe I is provided with a fuel injection nozzle; the exhaust pipe II is provided with a urea nozzle, and the exhaust pipe II is provided with a urea nozzle. The urea nozzle is connected with the urea tank. The utility model can effectively reduce various pollutants in the exhaust gas of the diesel engine, and can also timely process the carbon particles in the diesel particle filter, prevent the exhaust back pressure from being too high, and improve the power and economy of the diesel engine.

Description

A diesel engine exhaust purification system

technical field

The utility model relates to a diesel engine post-processing system, in particular to a diesel engine tail gas purification system.

Background technique

The main pollutants in diesel engine exhaust are nitrogen oxides, carbon particles, hydrocarbons and carbon monoxide. Among them, nitrogen oxides are mainly treated with urea solution through selective catalytic reduction (SCR) technology; carbon particles are mainly treated by diesel particles The filter (DPF) filters out hydrocarbons and carbon monoxide through an oxidation catalyst for oxidation. However, the filtering capacity of the diesel particulate filter is limited. With the increase of carbon particles in the diesel particulate filter, the exhaust back pressure will increase, which will affect the power and economy of the diesel engine.

Utility model content

The purpose of this utility model is to solve the above-mentioned deficiencies in the prior art, and provide a technical scheme of a diesel engine exhaust purification system, which can effectively reduce various pollutants in the diesel engine exhaust, and can also timely treat the carbon dioxide in the diesel particulate filter. Particles prevent excessive exhaust back pressure and improve the power and economy of the diesel engine.

The technical problem to be solved by the utility model is realized by the following technical solutions: a diesel engine exhaust purification system, including an oxidation catalyst, a diesel particle filter and a selective catalytic reduction device, the oxidation catalyst and the diesel particle filter are connected in series It is packaged in an integrated housing and the oxidation catalyst is located upstream of the diesel particulate filter. The air inlet of the integrated housing is connected to the exhaust port of the diesel engine through the exhaust pipe I, and the air outlet of the integrated housing is connected through the exhaust Pipe II is connected to the air inlet of the selective catalytic reduction device, and the gas outlet of the selective catalytic reduction device communicates with the outside world through the exhaust pipe III; The nozzle is connected to the oil circuit behind the diesel engine filter through the low-pressure oil pipe; the exhaust pipe II is provided with a urea nozzle, and the urea nozzle is connected to the urea tank.

The working principle of the utility model: the tail gas discharged by the diesel engine enters the integrated casing through the exhaust pipe I, the hydrocarbons, carbon monoxide and nitrogen monoxide in the tail gas are oxidized in the oxidation catalyst, and the nitrogen monoxide is oxidized into nitrogen dioxide , The heat release of the oxidation reaction can ensure the temperature in the integrated shell, so that the nitrogen dioxide can react with the carbon particles in the exhaust gas to form nitrogen and carbon dioxide, and reduce the carbon particles. At the same time, the fuel injector injects the carbon particles filtered by the diesel combustion diesel particulate filter to prevent excessive back pressure. Then the exhaust gas enters the selective catalytic reduction device, and the urea in the urea tank is sprayed into the exhaust pipe II through the urea nozzle to mix with the exhaust gas. The nitrogen oxides in the exhaust gas form nitrogen and water through reduction reaction.

The technical scheme of the utility model also has: the selective catalytic reduction device is provided with a ceramic carrier, and the ceramic carrier is a cylinder with a diameter of 380mm-500mm and a length of 254mm. The cross-section of the through hole is a square with a side length of 1.05 mm to 1.15 mm, and the center distance between adjacent through holes is 1.22 mm to 1.32 mm. By adopting the technical scheme, the exhaust back pressure can be effectively reduced while ensuring the catalytic reduction of the nitrogen oxides in the tail gas, thereby reducing the power loss of the diesel engine and reducing the fuel consumption.

The technical scheme of the utility model also includes: the ceramic carrier is fixed to the inner wall of the selective catalytic reduction device through a high-temperature-resistant liner. The liner plays the role of heat insulation to prevent heat loss in the ceramic carrier and ensure the temperature of the reduction reaction.

The technical solution of the utility model also includes: the ceramic carrier includes ceramic carrier I and ceramic carrier II axially connected in series. If the ceramic carrier is made in one piece, the process is difficult, so the ceramic carrier I and the ceramic carrier II are made separately and connected in series to form a ceramic carrier.

The technical solution of the present utility model also includes: the exhaust pipe II is provided with a temperature sensor for monitoring the temperature in the exhaust pipe II, which is fed back to the on-board diagnostic system (OBD). The temperature required for the catalytic reduction reaction.

The technical scheme of the utility model also includes: the exhaust pipe III is provided with a nitrogen and oxygen sensor, which is used to detect the content of nitrogen oxides in the exhaust pipe III, and feeds back to the on-board diagnostic system. The on-board diagnostic system sprays the urea nozzle The amount is regulated to ensure the progress of the selective catalytic reduction reaction.

Compared with the prior art, the beneficial effects of the diesel engine exhaust purification system of the utility model are: it can effectively reduce various pollutants in the diesel engine exhaust, and the nitrogen oxide conversion efficiency is as high as more than 90% in the steady state, and can reach 70% in the transient state. 75%, the diesel particulate filter can capture more than 90% of the particulate matter, and it can also deal with the carbon particles in the diesel particulate filter in time, prevent the exhaust back pressure from being too high, and improve the power and economy of the diesel engine.

Description of drawings

Fig. 1 is the front view of the utility model diesel engine exhaust purification system.

Fig. 2 is a sectional view of A-A in Fig. 1 .

FIG. 3 is a partially enlarged view of part B of FIG. 2 .

In the figure: 1. Oxidation catalyst, 2. Diesel particulate filter, 3. Selective catalytic reduction device, 4. Integrated housing, 5. Exhaust pipe I, 6. Exhaust pipe II, 7. Exhaust pipe III , 8, fuel injector, 9, urea nozzle, 10, urea tank, 11, through hole, 12, liner, 13, ceramic carrier Ⅰ, 14, ceramic carrier Ⅱ, 15, temperature sensor, 16, nitrogen and oxygen sensor, 17. Diesel engine. the

Detailed ways

In order to clearly illustrate the technical features of this solution, the specific implementation of the utility model will be further described below according to the accompanying drawings.

As shown in Figures 1-3, a diesel engine exhaust purification system includes an oxidation catalyst 1, a diesel particulate filter 2 and a selective catalytic reduction device 3, and the oxidation catalyst 1 and the diesel particulate filter 2 are connected in series and Packaged in the integrated housing 4 and the oxidation catalyst 1 is located upstream of the diesel particulate filter 2, the air inlet of the integrated housing 4 is connected to the exhaust port of the diesel engine 17 through the exhaust pipe I5, and the integrated housing 4 The gas outlet is connected to the air inlet of the selective catalytic reduction device 3 through the exhaust pipe II6, and the gas outlet of the selective catalytic reduction device 3 communicates with the outside world through the exhaust pipe III7; the selective catalytic reduction device 3 is provided with a shaft ceramic carrier I13 and ceramic carrier II14 connected in series, the ceramic carrier I13 and ceramic carrier II14 are cylindrical with a diameter of 380mm-500mm and a length of 254mm, and the ceramic carrier I13 and ceramic carrier II14 are provided with cloth A through hole 11 with a full cross section, the cross section of the through hole 11 is a square with a side length of 1.05mm-1.15mm, the center distance between adjacent through holes 11 is 1.22mm-1.32mm, ceramic carrier I13 and The ceramic carrier II14 is fixed to the inner wall of the selective catalytic reduction device 3 through a high-temperature-resistant gasket 12, and the catalyst is coated on the ceramic carrier I13 and ceramic carrier II14 by selecting an appropriate weight according to different product requirements, and the loading capacity is guaranteed after coating. It also ensures that the holes will not be blocked, and requires the coating to have a certain adhesion, so as to ensure that the catalyst will not be easily blown off during actual use; the exhaust pipe I5 is provided with an oil nozzle 8, and the nozzle The oil nozzle 8 is connected with the oil circuit after the filter of the diesel engine 17 through the low-pressure oil pipe; the exhaust pipe II6 is provided with a urea nozzle 9 and a temperature sensor 15, and the urea nozzle 9 is connected with the urea tank 10; A nitrogen and oxygen sensor 16 is provided on the pipe III7; a temperature sensor 15 and a nitrogen and oxygen sensor 16 are respectively connected to the on-board diagnostic system.

The working principle of the utility model: the tail gas discharged by the diesel engine 17 enters the integrated casing 4 through the exhaust pipe I5, the hydrocarbons, carbon monoxide and nitrogen monoxide in the tail gas are oxidized, and the nitrogen monoxide is oxidized to nitrogen dioxide, and the oxidation reaction The heat release can ensure the temperature inside the integrated housing so that the nitrogen dioxide reacts with the carbon particles in the exhaust gas to form nitrogen and carbon dioxide, reducing the carbon particles. At the same time, the fuel injector injects diesel fuel to burn the carbon particles filtered by the diesel particulate filter 2 to prevent excessive back pressure. Then the exhaust gas enters the selective catalytic reduction device 3, and the urea in the urea tank 10 is sprayed into the exhaust pipe II6 through the urea nozzle 9 to mix with the exhaust gas. The nitrogen oxides in the exhaust gas form nitrogen and water through reduction reaction.

The embodiments of the present utility model have been described in detail above in conjunction with the accompanying drawings, but the present utility model is not limited to the above-mentioned embodiments. Make various changes below.

Claims (6)

1. A diesel exhaust purification system, comprising an oxidation catalyst (1), a diesel particulate filter (2) and a selective catalytic reduction device (3), characterized in that: the oxidation catalyst (1) and diesel particulate filter The filter (2) is connected in series and packaged in the integrated housing (4) and the oxidation catalyst (1) is located upstream of the diesel particulate filter (2), the intake port and exhaust pipe of the integrated housing (4) Ⅰ (5), the gas outlet of the integrated housing (4) is connected to the inlet of the selective catalytic reduction device (3) through the exhaust pipe II (6), and the outlet of the selective catalytic reduction device (3) The air port communicates with the outside world through the exhaust pipe III (7); the exhaust pipe I (5) is provided with a fuel injection nozzle (8); the exhaust pipe II (6) is provided with a urea nozzle (9), The urea nozzle (9) is connected with the urea tank (10). 2. The diesel engine exhaust purification system according to claim 1, characterized in that: the selective catalytic reduction device (3) is provided with a ceramic carrier, and the ceramic carrier has a diameter of 380mm-500mm and a length of 254mm mm cylindrical, the ceramic carrier is provided with through holes (11) covering its cross section. ) between centers is 1.22mm-1.32mm. 3. The diesel engine exhaust purification system according to claim 2, characterized in that: the ceramic carrier is fixed to the inner wall of the selective catalytic reduction device (3) through a high temperature resistant gasket (12). 4. The diesel engine exhaust purification system according to claim 2, characterized in that: said ceramic carrier comprises ceramic carrier I (13) and ceramic carrier II (14) connected in axial series. 5. The diesel engine exhaust purification system according to any one of claims 1-4, characterized in that: the exhaust pipe II (6) is provided with a temperature sensor (15). 6. The diesel engine exhaust purification system according to any one of claims 1-4, characterized in that: the exhaust pipe III (7) is provided with a nitrogen and oxygen sensor (16).