CN100402806C - A wall-flow diesel vehicle exhaust particulate filter-regeneration device - Google Patents

Abstract

The invention relates to a diesel vehicle exhaust soot filter system, in particular to a wall-flow type diesel vehicle exhaust particulate filter-regeneration device, including a power supply, a controllable fuel injection device, a fuel dispersion unit, an electric heating element, and a flame dispersion unit , wall-flow ceramic foam particulate filter; the electric heating element and the fuel dispersing unit before and after the electric heating heating element, the flame dispersing unit and the wall-flow ceramic foam particulate filter are installed in the purification system connected to the exhaust pipe of the diesel engine. The wall-flow ceramic foam particle filter is composed of multiple silicon carbide foam ceramic plates in parallel, and the silicon carbide foam ceramic plates have a single foam pore size or variable pore size. The device of the present invention has high purification efficiency and good in-situ regeneration ability. After effectively filtering the diesel vehicle particles, it can realize intelligent regeneration of the vehicle state under the normal power supply of the vehicle power supply and the normal operation of the vehicle, thus having great advantages. Good durability.

Description

A wall-flow diesel vehicle exhaust particulate filter-regeneration device

technical field

The invention relates to a diesel vehicle exhaust soot filter system, specifically a wall-flow diesel vehicle exhaust particulate filter-regeneration device with silicon carbide foam ceramics as the carrier of the filter device, which can effectively reduce the soot emission of diesel vehicles Diesel vehicles realize regeneration under normal power supply and normal driving conditions.

Background technique

Due to the difference in mixing and combustion methods, the CO and HC in the exhaust components of diesel engines are much less than those of gasoline engines, while the soot is dozens of times or even more than that of gasoline engines, and the soot emissions are easier for people to visually perceive, so diesel engines The purification of vehicle exhaust has always been the focus and difficulty of diesel vehicle pollution control.

Theoretically speaking, the existing soot filter technology for diesel vehicles is mainly divided into surface filter and body filter. Surface filtration is also called filter cake filtration. Filtration occurs on the surface of the filter. The principle is to make the exhaust gas containing soot particles flow through a ceramic wall with many small holes and high density. Diesel soot particles cannot pass through the small holes in the wall and settle on the surface of the filter. This filtering method is very effective, but it has a large resistance and high exhaust back pressure. The representative technology of surface filtration theory is wall-flow honeycomb ceramics; in-body filtration is also called deep filter bed filtration. Filtration occurs inside the filter. When the exhaust gas flows through the filter, the soot particles in it collide with the ribs inside the filter for many times. , precipitate in the pores of the filter by means of diffusion and interception. This structure has low exhaust resistance, and the soot particles deposited in the filter are evenly distributed. Representative technologies for in vivo filtration are ceramic foam filters and fiber filters.

After the soot particulate filter works for a period of time, as the number of filtered particles increases, the phenomenon of filter hole clogging will gradually occur. If the clogging accumulates to a certain extent, the flow of exhaust gas will be blocked, resulting in engine exhaust back pressure. The sharp increase will affect the working efficiency of the engine. At this time, the filter needs to be regenerated. The regeneration methods of the particulate filter mainly include the following types. The first one uses catalyst regeneration, that is, adding a catalyst on the surface of the particulate filter, and using the catalytic effect of the catalyst to reduce the ignition temperature of the particulates, so that the captured particulates are released at a lower temperature. It reacts with oxygen or nitrogen oxides in the exhaust gas to form carbon dioxide to remove particulates. However, this regeneration method requires that the temperature of the exhaust gas must meet a certain requirement. When the car is running at low speed or under light load conditions, the temperature of the exhaust gas often cannot meet this requirement; the second regeneration method is to use a heater or combustion to increase the temperature of the exhaust gas. Temperature, so that the particles are burned and removed under high temperature conditions. The first two methods are in-situ regeneration methods, that is, the catalyst is still in the original installation position during regeneration. Another is the non-situ regeneration method, that is, when the particulate filter captures a certain amount of particulates, the particulate filter is removed from the car and placed in an air furnace and other equipment for heating, so that the particulates can be removed by combustion. Or blow the dismantled particulate filter from the opposite direction with atmospheric airflow to blow out the soot particles and collect them for removal.

No matter what kind of regeneration method is used, there are two problems: one is the problem of regeneration efficiency, and the other is that the currently used particulate filter material is easy to burst due to the extreme temperature unevenness caused by the rapid heat release of particulate combustion. These two problems are the main problems of the current soot filtration-regeneration technology. The present invention adopts the wall-flow soot particulate filter made of silicon carbide foam ceramics with high thermal conductivity, low expansion coefficient and high melting point, which has the advantages of surface filtration and body filtration, high filtration efficiency, good thermal shock resistance, and Effectively avoid filter bursting during regeneration and ensure the reliability of the filter; regeneration uses exhaust gas fuel injection combined with electric heating to achieve low-cost regeneration of the filter and prolong the service life of the filter.

Contents of the invention

The purpose of the present invention is to provide a wall-flow type diesel vehicle exhaust particle filter-regeneration device, which can effectively filter the soot emitted by the engine, and can filter the particles by burning fuel oil combined with electric heating after the filter reaches a certain level The engine can be regenerated in situ, and the installation of the device will not cause a significant loss of engine power.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A wall-flow type diesel vehicle exhaust particle filter-regeneration device includes a power supply, a controllable fuel injection device, a fuel dispersion unit, an electric heating element, a flame dispersion unit, a wall-flow type foam ceramic particle filter and an electric control part. The electric heating element is composed of a foam ceramic electric heating unit, and the foam ceramic electric heating unit is composed of conductive silicon carbide foam ceramics and two metal electrodes welded on the silicon carbide ceramic electrode bases at both ends of the conductive silicon carbide foam ceramics. The metal electrode and the conductive silicon carbide foam ceramic form a circuit to supply power to the conductive silicon carbide foam ceramic. The controllable fuel injection device consists of an electric pump, a solenoid valve, and a fuel nozzle. The device takes fuel from the fuel tank of the vehicle through the fuel pipeline. The fuel dispersing unit, electric heating heating element, flame dispersing unit and wall-flow ceramic foam particle filter are installed together in the purifier package shell connected to the exhaust pipe of the diesel engine, and the fuel nozzle of the controllable fuel injection device is located in the electric heating heating upstream of the body. The electric control part is connected with the electrodes of the foam ceramic electric heating heating element.

The wall-flow ceramic foam particle filter is composed of multiple silicon carbide foam ceramic plates in parallel, and the distance between every two composite silicon carbide foam ceramic plates is 1.5-3 mm. Inside the filter, there are many short channels that are not directly connected to each other. The gas can only pass through the silicon carbide foam ceramic plate to enter the other channel from one channel, and the soot particles are filtered during the passage.

The silicon carbide foam ceramic plate constituting the wall-flow ceramic foam particulate filter may have a single foam pore size or a variable pore size. The silicon carbide foam ceramic plate with variable pore size is prepared in one of the following three ways: a. It is composed of two or more silicon carbide foam ceramic plates with different pore sizes; b. On a silicon carbide foam ceramic plate with a single pore size Prepare the microporous coating; c, the combination of the first two methods, that is, prepare the microporous coating on the composite silicon carbide foam ceramic plate mentioned in a. When using variable-pore-diameter foam ceramics, the surface of the large-pore foam ceramics is the exhaust gas entry surface, and the small-pore or micropore surface is the exhaust gas exit surface.

The foam ceramic electric heating heating element is composed of at least one foam ceramic electric heating unit. When the filter is composed of two or more units, the units are connected in parallel, and are connected into one by welding between electrodes. Overall, the volume of the electric heating exhaust gas purifier is controlled between 50-400ml, and the thickness is controlled within the range of 10-50mm.

Both the fuel dispersing unit and the flame dispersing unit are made of silicon carbide foam ceramics, which promote the lateral diffusion of fuel and flame by utilizing the unique three-dimensional interconnected structure of foam ceramics.

The silicon carbide foamed ceramics is composed of 90% to 98% of silicon carbide and 10% to 2% of silicon in terms of weight fraction.

The silicon carbide foam ceramics uses a polygonal closed ring as a basic unit, and each basic unit is connected with each other to form a three-dimensional connected network; the relative density of the ceramic ribs constituting the polygonal closed ring unit is ≥ 99%, and the average grain size is 50nm-10μm.

The fuel dispersing unit, the electric heating element, and the flame dispersing unit can be prepared with an active alumina coating, and the catalyst is loaded, and the silicon carbide foam ceramic is used as the carrier, and the coating content per liter of the carrier is 80-130g. The weight ratio of each substance is: Al ₂ O ₃ : CeO ₂ : La ₂ O ₃ : BaO=50～55:30～40:2～8:1～10; the active material used in the catalyst can be Pt or Pd, each The total content of Pt or Pd in the carrier is 1-5g.

The present invention mainly includes three parts: a. install a controllable fuel injection device, when the filter needs to be regenerated, the device sprays fuel into the front of the electric heating heating element; b. use conductive silicon carbide foam ceramics as the heating element, and use the vehicle The battery is used as the power supply, and the heating element is energized under the set conditions to ignite the fuel fed by the controllable fuel injection device, and heat the exhaust gas to burn the particles in the wall-flow particulate filter; c. Silicon foam ceramics are combined with wall-flow particulate filters, and the obtained filters have the advantages of both surface filtration and volume filtration. By adjusting the average pore size of the foamed ceramics, the volume fraction of the ceramics, the thickness of the ceramic plate and other parameters, a high filtration efficiency can be obtained under reasonable back pressure conditions. Moreover, due to the characteristics of low expansion coefficient, high thermal conductivity and high melting point of silicon carbide foam ceramics, it has strong thermal shock resistance and will not burst during regeneration.

Compared with the prior art, the present invention has the following beneficial effects:

①The soot filter body is made of silicon carbide foam ceramics. The filter body has the following characteristics: a. Good thermal conductivity, ensuring uniform temperature distribution of the filter body, avoiding excessive thermal stress and reducing the existence of regeneration dead angle; b. Heat resistance It has good impact resistance and can withstand the drastic temperature change caused by the oxidation and combustion of particles during regeneration; c. The melting point is high, above 2000°C, ensuring a long service life at high temperatures.

②The electric heating element adopts silicon carbide foam ceramics, which realizes the integration of heating and filtering functions, has a simple structure, and the resistivity can be adjusted in a wide range according to actual needs. In addition, silicon carbide ceramics have good oxidation resistance, high temperature resistance, and acid and alkali resistance. Compared with metal resistance wire heating elements, they are more suitable for use in automobile exhaust environments.

③The regeneration method combining fuel injection and electric heating is adopted to improve the regeneration efficiency.

④The foam ceramic wall-flow structure adopted by the filter body has a large filtration area, which not only increases the collision probability of the particulate matter and the filter body, improves the filtration efficiency, promotes the uniform dispersion of the particulate matter in the filter body, but also helps reduce the Back pressure, reducing engine power loss.

⑤ The device adopts the vehicle-mounted storage battery as the electric heating power source, and does not need an external power source. The scope of vehicle modification is small and the cost is low.

⑥The control system is intelligent, and the regeneration state can be controlled according to conditions such as water temperature, engine speed and back pressure.

⑦ Brazing is used to prepare metal electrodes to minimize contact resistance and improve energy utilization efficiency.

⑧The device of the present invention has good and controllable filtration-regeneration performance, and can realize effective filtration of diesel vehicle particles and intelligent in-situ regeneration when the vehicle power supply is normally powered and the vehicle is running normally and the vehicle is running normally. Diesel vehicle emissions can meet strict purification standards for a long period of time, and have the characteristics of good effect, in-situ regeneration, and long life.

Description of drawings

Figure 1 is a working schematic diagram of a wall-flow diesel vehicle exhaust particulate filter-regeneration device.

Fig. 2 is a schematic diagram of a ceramic foam electric heating regenerative heating element unit (electric heating unit).

Fig. 3 is a schematic diagram of the structure of a wall-flow ceramic foam particulate filter.

Fig. 4 is a schematic structural view of a composite silicon carbide foam ceramic plate.

In the figure, 1 diesel engine; 2 water temperature sensor; 3 speed sensor; 4 control unit; 5 power assembly; 6 vehicle battery; 7 cable; ; 10 metal electrode; 11 metal electrode; 12 electric heating heating element; 13 exhaust pipe; 14 pressure sensor; 15 flame dispersion unit; 16 fuel dispersion unit; 17 fuel nozzle; 18 solenoid valve; 19 electric pump; 20 oil pipeline; 21 automobile fuel tank; 22 silicon carbide ceramic electrode base; 23 silicon carbide ceramic electrode base; 24 conductive silicon carbide foam ceramic heating element; 25 (composite silicon carbide foam ceramic plate) large-pore silicon carbide foam ceramic plate; 26 ( Composite silicon carbide foam ceramic plates) small-pore silicon carbide foam ceramic plates or coatings with micropores.

Detailed ways

The preparation process of the wall-flow diesel vehicle exhaust particulate filter-regeneration device of the present invention is as follows:

①Adopt conductive silicon carbide foam ceramics according to "A High-Strength and Dense Foamed Silicon Carbide Ceramic Material and Its Preparation Method" (applied by the Institute of Metal Research, Chinese Academy of Sciences, application number 03134039.3, application date: September 22, 2003) , as the source of all silicon carbide foam ceramics used in the present invention.

② The silicon carbide foam ceramic material is combined into a wall-flow ceramic foam particle filter as shown in Figure 3, which is used as the main filter of the wall-flow diesel vehicle exhaust particle filter-regeneration device. The air flow enters the main filter through the open channel, passes through the silicon carbide foam ceramic wall, and enters the adjacent channel, as shown by the arrow in Figure 3, during which the soot particles are filtered and purified. When composite foam ceramics with transitional apertures are used, the large-aperture ceramic surface is the exhaust gas inflow surface, and the small-aperture ceramic surface is the exhaust gas outflow surface. Parameters such as the volume of the main filter and the number of channels, and the average pore size of silicon carbide foam ceramics can be adjusted according to the requirements of exhaust gas flow and back pressure.

③According to the conditions of different vehicles, parameters such as fuel injection frequency and fuel injection volume of the controllable fuel injection device can be adjusted.

④ Select one or more suitable silicon carbide foam ceramic electric heating units according to the resistance requirements. If multiple units are used, the units are connected in parallel and connected into one by welding metal plates on the metal electrodes. overall.

⑤ Activated alumina coatings can be prepared on the ceramic foam fuel dispersing unit, electric heating element and flame dispersing unit, and the catalyst can be loaded to promote the accelerated combustion of soot particles and reduce the emission of gaseous pollutants during the cold start stage.

The concrete process of catalyst preparation is as follows:

a. Soak silicon carbide foam ceramics in a NaOH or KOH solution with a concentration of 2-5M for 5-10 minutes to remove impurities such as oil stains on the surface, then wash with water, and then place it in an air atmosphere at 100-150°C for 1-4 hours drying;

b. Take 110-160 parts of γ-Al ₂ O ₃ , 50-70 parts of CeO _{2 ,} 2-10 parts of La ₂ O ₃ , 4-20 parts of BaO, mix them, add 500 parts of water, and ball mill for 2-4 hours to obtain a coating slurry;

c. Immerse the foamed ceramics in the slurry for 2-5 minutes, blow off the excess slurry with compressed air, then dry it in an air atmosphere at 100-150°C for 20-30 minutes, and then dip into the slurry again after cooling. Repeat this many times until the coating content reaches 80-130g/(L carrier), and finally bake at 450-500°C for 4-5 hours, and the coating is prepared;

d. If Pt is used as the catalytic active component, take 10-15 parts of H ₂ PtCl ₆ and add 500 parts of water to prepare a mixed solution, and then vacuum-immerse the foamed ceramics with active coating in the solution for 10-15 minutes. Afterwards, the impregnated ceramics are dried in an oven at a temperature of 100-150°C for 20-30 minutes; the dried samples are reduced in a hydrogen atmosphere at 450-500°C for 2-4 hours to obtain silicon carbide foam A silicon carbide foam ceramic electric heating heating element with catalytic function and a wall-flow foam ceramic particle filter with ceramics as the carrier and Pt as the catalytic active component.

e. If Pd is used as the catalytic active component, take 5-20 parts of PdCl ₂ and add 500 parts of water to prepare a mixed solution, then vacuum-immerse the foamed ceramics with active coating in the solution for 10-15 minutes, and then put The impregnated ceramics are dried in an oven at a temperature of 100-150°C for 20-30 minutes; the dried samples are reduced in a hydrogen atmosphere at 450-500°C for 2-4 hours, and silicon carbide foam ceramics can be obtained. The carrier, the silicon carbide foam ceramic electric heating heating element with catalytic function and Pd as the catalytic active component, and the wall flow type foam ceramic particle filter.

⑥ Encapsulate the fuel dispersing unit 16, the electric heating element 12, the flame dispersing unit 15 and the wall-flow ceramic foam particle filter 9 together in the filter housing 8, the filter housing is welded by 2 mm thick stainless steel plate, There is a shockproof interlayer between the filter housing 8 and the ceramic foam electric heating element 12 and the wall-flow ceramic foam particle filter 9 . The packaged filter is connected to the exhaust pipe 13 of the diesel engine at the intake end. The fuel inlet end of the controllable fuel injection device is connected with the fuel tank 21 of the vehicle through the fuel pipeline 20 , and the fuel nozzle 17 is located upstream of the electric heating heating element 12 .

As shown in Figures 1 and 2, the wall-flow diesel vehicle exhaust particulate filter-regeneration device includes a wall-flow foam ceramic particulate filter 9, a flame dispersing unit 15, an electric heating element 12, a fuel dispersing unit 16, a controllable fuel injection The device and the electric control part, wherein the electric heating heating element 12, the flame dispersing unit 15, the fuel dispersing unit 16 and the wall-flow ceramic foam particle filter 9 are installed in the purifier packaging shell 8 connected with the exhaust pipe 13 of the diesel engine The electric heating element 12 is composed of a foam ceramic electric heating unit, the foam ceramic electric heating unit is a conductive silicon carbide foam ceramic 24 as the main body, and two metal electrodes are welded on the silicon carbide ceramic electrode base located at the two ends of the conductive silicon carbide foam ceramic 24 On the seats 22, 23, the power supply 6 constitutes a loop with the conductive silicon carbide foam ceramics 24 through the metal electrodes 10, 11 to supply power for the conductive silicon carbide foam ceramics 24; The controllable fuel injection device is composed of a fuel delivery pipeline 20, an electric pump 19, a one-way solenoid valve 18 and a fuel nozzle 17. The fuel delivery pipeline 20 is connected with the fuel tank 21 of the vehicle, and the fuel nozzle 17 is located at the upstream of the electric heating heating element 12. The fuel nozzle 17 and the An electric pump 19 and a solenoid valve 18 are arranged on the fuel pipeline between the automobile fuel tanks 21 . The electronic control part is composed of a control unit 4 and a power component 5 . The electronic control part of the present invention adopts the Chinese invention patent application, application number: 200510046472.1, application date: May 20, 2005, see Figure 5 and related text descriptions therein for details. The only difference is: the output end of the power component is connected in parallel with the electric heating heating element, the solenoid valve and the electric pump of the controllable fuel injection device, and the controllable fuel injection device can perform controllable continuous or pulsed fuel injection, and the pulse frequency and injection The time can be controlled by the control unit 4 in a conventional manner. The control unit 4 can receive corresponding signals from the pressure sensor 14, the water temperature sensor 2, and the rotational speed sensor 3, and control the start or stop of the controllable fuel injection device and the electric heating heating element according to the signals.

After the diesel vehicle is started, the automobile exhaust containing soot particles is discharged from the diesel engine 1, and reaches the fuel dispersion unit 16, the electric heating heating element 12, the flame dispersion unit 15 and the wall-flow foam ceramic particle filter 9 through the exhaust pipe 13, During this process, the soot particles are filtered and intercepted by the foam ceramics. The cooling water temperature, rotational speed and back pressure signals monitored by the diesel engine cooling water temperature sensor 2 , rotational speed sensor 3 and pressure sensor 14 are received by the control unit 4 and then transmitted to the power assembly 5 . When the back pressure is higher than the set value, when the cooling water temperature and engine speed reach the specified value, the power component 5 is connected to the circuit, and the on-board battery 6 starts to supply power to the electric heating element 12 through the cable 7. The power-on time It can be set by the control unit; after power on for a period of time, the control unit 4 turns on the electric pump 19 and the one-way solenoid valve 18, draws fuel from the fuel tank 21 of the vehicle through the oil pipeline 20, and delivers it to the fuel nozzle 17, where the fuel is sprayed out. The fuel first reaches the fuel dispersing unit 16 , is uniformly dispersed, and then reaches the electric heating element 12 . The electric heating heating element 12 in the energized heating state ignites the fuel, and the heat released by the fuel combustion is carried by the exhaust gas to the downstream flame dispersing unit 15. The foam ceramic flame dispersing unit 15 can evenly disperse the flame and then spread it to the wall-flow foam ceramic particles The filter 9 makes the soot filtered in the filter evenly burn everywhere, so as to avoid the phenomenon of temperature inhomogeneity when the filter is regenerated. After these processes, the entire filter system achieves the purpose of regeneration.

As shown in Figure 2, the foam ceramic electric heating unit is made of conductive silicon carbide foam ceramics 24, two metal electrodes 10, 11 welded on the silicon carbide ceramic electrode bases 22, 23 at the two ends of the conductive silicon carbide foam ceramics 24, One end of the two metal electrodes 10, 11 is connected to the silicon carbide ceramic electrode base by brazing, and the other end is connected to the cable. A complete electric heating heating body can be composed of one or more foam ceramic electric heating units. In the case of combination, the units are connected in parallel, and are connected as a whole by welding between electrodes. The volume of the electric heating element is controlled between 100-400ml, and the thickness is controlled within the range of 10-50mm.

Fig. 3 shows the structural representation of the wall-flow type ceramic foam particle filter, the wall-flow type ceramic foam particle filter 9 is formed by parallel combination of multiple silicon carbide foam ceramic plates, and the gap between every two composite silicon carbide foam ceramic plates The distance is 1.5-3mm. Inside the filter, there are many short passages that are not directly connected to each other. The airflow enters from the opening of the air inlet, passes through the foam ceramic wall and enters the adjacent passage. During this process, the soot particles are filtered by the silicon carbide foam ceramic plate.

The silicon carbide foam ceramic plate constituting the wall-flow type ceramic foam particle filter of the present invention can have a single foam pore size or a variable pore size, and the foam ceramic plate with a variable pore size is one of the following three preparation methods: a, consisting of two or more than two Composite foam ceramic plates with different pore diameters; b. Microporous coatings are prepared on silicon carbide foam ceramic plates with a single pore size; c. The combination of the first two methods, that is, the composite ceramic plates mentioned in a A microporous coating is then prepared. The original preparation slurry of silicon carbide foam ceramics is synthesized on the silicon carbide foam ceramics into a coating with a thickness of no more than 0.5mm, and the microporous coating can be obtained after sintering. By adopting the above method, a wide range of pore diameter transition from 1 mm to 0.01 mm in the pore diameter of the composite silicon carbide foam ceramic can be realized. When using variable-pore-diameter foam ceramics, the surface of the large-pore foam ceramics is the exhaust gas entry surface, and the small-pore or micropore surface is the exhaust gas exit surface. As shown in Figure 4, the composite silicon carbide foam ceramic plate with variable pore diameter, the small-pore silicon carbide foam ceramic plate or the coating 26 with micropores has a pore diameter of 0.01 mm to 0.5 mm; the large-pore silicon carbide foam ceramic plate 25 has a pore diameter of 0.1 mm ~ 1mm.

The exhaust gas purification device of the present invention is mainly composed of the above-mentioned foam ceramic soot filter-electric heating regenerative purifier (including fuel oil dispersing unit 16, electric heating heating element 12, flame dispersing unit 15 and wall flow type foam ceramic particle filter 9) and intelligent control Unit 4, composed of a controllable fuel injection device. The electric heating element in the purifier is mainly made of conductive silicon carbide foam ceramics, which has good and controllable electrical conductivity; the wall flow type foam ceramic particle filter is composed of foam ceramics. The material has the characteristics of porous, variable pore size, rough surface, high temperature resistance and thermal shock, which can effectively filter the exhaust particles of diesel vehicles; it can be loaded on the fuel dispersing unit 16, the electric heating heating element 12 and the flame dispersing unit 15 Catalyst: The intelligent control unit can receive the cooling water temperature, back pressure and engine speed signals from the control unit platform, and automatically control the regeneration state of the wall-flow diesel vehicle exhaust particulate filter-regeneration device according to the signals. The in-situ regeneration of the foam ceramic soot wall-flow type diesel vehicle exhaust particulate filter-regeneration device can be realized under the condition that the vehicle power supply is powered and the normal running of the vehicle is not affected.

Examples and related comparative examples

The engine model used in the tests of each embodiment and related comparative examples is SOFIM8140.43, and the test method adopts the diesel engine 13 working condition.

Example 1

① Take conductive silicon carbide foam ceramics 130×40×20mm, soak them in NaOH solution with a concentration of 3M for 8 minutes, remove oil stains and other impurities on the surface, then wash them with water, and then dry them in an air atmosphere at 120°C for 2 hours;

② Brazing two stainless steel columns with a diameter of 6 mm on the silicon carbide ceramic electrode bases located at both ends of the conductive silicon carbide foam ceramics described in ① as electrodes connected to wires. An electric heating unit is prepared;

③According to the above steps ①～②, make two electric heating heating element units, and then weld the two electric heating heating element units in parallel by welding metal plates on the metal electrodes to obtain a complete electric heating heating element body; the resistance of the electric heating element is 50mΩ.

④ As shown in Figure 3, the silicon carbide foam ceramic plates with a volume fraction of 30% and an average pore diameter of 0.5 mm are combined to form a wall-flow type ceramic foam particle filter. The thickness of each silicon carbide foam ceramic plate is 5 mm, and the distance between every two ceramic plates is 2mm, and the final filter shape is 220×130×150mm ³ ;

⑤ Using silicon carbide foam ceramics with an average pore diameter of 1.5mm and a volume fraction of 30% as raw materials, prepare the fuel dispersion unit 16 and the flame dispersion unit 15 by mechanical processing, wherein the fuel dispersion unit 16 has a center thickness of 30mm, an edge thickness of 5mm, and a length and the width are 220mm and 130mm respectively; the profile of the flame dispersing unit 15 is 220×130×20mm ³ ;

6. Encapsulate the fuel dispersion unit 16, the electric heating heating element 12, the flame dispersion unit 15 and the wall-flow type ceramic foam particle filter 9 in a housing, and the vacant space of the layer where the electric heating heating element 12 is located is formed by combining with the electric heating heating element 12 Filled with silicon carbide foam ceramics of the same thickness;

⑦ Connect the wall-flow diesel vehicle exhaust particulate filter-regeneration device with the engine. The engine model used in the test is SOFIM8140.43, and the test method adopts the diesel engine 13 working condition; no power is applied during the test.

Example 2

The difference from Example 1 is:

Before the test, the wall-flow diesel vehicle exhaust particulate filter-regeneration device was installed in the designated position of the diesel engine exhaust passage, and the engine was kept running at a high-concentration soot emission state with a speed of 2160rpm, a torque of 188Nm, and a power of 42.5kW. The control unit monitors the signal of the back pressure sensor, and when the back pressure signal is greater than 20kPa, it is considered that the filter needs to be regenerated. At this time, the control unit is connected to the electric heating circuit, which is powered by the 12V vehicle-mounted DC battery. After 5 seconds, the controllable fuel injection device is turned on, and the fuel is injected at a flow rate of 200ml/min at a frequency of 12 times/min upstream of the electric heating heating element. times, 5ml each time, then cut off the power, stop the oil, and shut down the engine.

Restart the engine after the engine cools down, and carry out the 13 working conditions test under the same conditions as in Example 1 to check the effect of regeneration.

Example 3

The difference from Example 2 is:

Inject fuel oil 5 times at a flow rate of 200ml/min upstream of the electric heating element at a frequency of 12 times/min, 10ml each time.

Example 4

The difference from Example 2 is:

Inject fuel oil 5 times at a flow rate of 200ml/min upstream of the electric heating element at a frequency of 12 times/min, 20ml each time.

Example 5

The difference from Example 2 is:

Inject fuel oil 5 times at a flow rate of 200ml/min upstream of the electric heating element at a frequency of 12 times/min, 30ml each time.

Example 6

The difference from Example 2 is:

Continuously inject 200ml of fuel oil upstream of the electric heating element at a flow rate of 200ml/min.

Example 7

The difference with embodiment 2 is:

The resistance of the electric heating element is 70mΩ; fuel is injected 5 times at a flow rate of 200ml/min at a frequency of 12 times/min, 30ml each time, upstream of the electric heating element.

Example 8

The difference with embodiment 2 is:

The resistance of the electric heating element is 90mΩ; fuel is injected 5 times at a flow rate of 200ml/min at a frequency of 12 times/min, 30ml each time, upstream of the electric heating element.

Example 9

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow ceramic foam particulate filter is 40%, and the average pore diameter is 0.5 mm.

Example 10

Different from embodiment 5 in that:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow ceramic foam particulate filter is 40%, and the average pore diameter is 0.5mm.

Example 11

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow type foam ceramic particulate filter is 50%, and the average pore diameter is 0.5mm.

Example 12

Different from embodiment 5 in that:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow type foam ceramic particulate filter is 50%, and the average pore diameter is 0.5mm.

Example 13

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow ceramic foam particulate filter is 40%, and the average pore diameter is 0.2mm.

Example 14

The difference with embodiment 5 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow ceramic foam particulate filter is 40%, and the average pore diameter is 0.2 mm.

Example 15

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics forming the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically, a silicon carbide foam ceramic plate with a thickness of 3mm and an average pore diameter of 0.2mm and a thickness of 2mm, Silicon carbide foam ceramic plates with an average pore diameter of 0.05 mm are assembled together.

Example 16

The difference with embodiment 5 is:

The volume fraction of silicon carbide foam ceramics forming the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically, a silicon carbide foam ceramic plate with a thickness of 3mm and an average pore diameter of 0.2mm and a thickness of 2mm, Silicon carbide foam ceramic plates with an average pore diameter of 0.05 mm are assembled together.

Example 17

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically a composite microporous coating on a silicon carbide foam ceramic plate with a thickness of 5 mm and an average pore diameter of 0.2 mm. layer, the average pore diameter of the microporous coating is about 0.01mm.

Example 18

The difference with embodiment 5 is:

The volume fraction of silicon carbide foam ceramics constituting the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically a composite microporous coating on a silicon carbide foam ceramic plate with a thickness of 5 mm and an average pore diameter of 0.2 mm. layer, the average pore diameter of the microporous coating is about 0.01mm.

Example 19

The difference from Example 1 is:

The volume fraction of silicon carbide foam ceramics forming the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically, a silicon carbide foam ceramic plate with a thickness of 3mm and an average pore diameter of 0.2mm and a thickness of 2mm, Silicon carbide foam ceramic plates with an average pore diameter of 0.05mm are combined together, and then a microporous coating is compounded on the silicon carbide foam ceramic plate with a pore diameter of 0.05mm. The average pore diameter of the microporous coating is about 0.01mm.

Example 20

The difference with embodiment 5 is:

The volume fraction of silicon carbide foam ceramics forming the wall-flow type ceramic foam particle filter is 40%, and the silicon carbide foam ceramic plate is a composite structure, specifically, a silicon carbide foam ceramic plate with a thickness of 3mm and an average pore diameter of 0.2mm and a thickness of 2mm, Silicon carbide foam ceramic plates with an average pore diameter of 0.05mm are combined together, and then a microporous coating is compounded on the silicon carbide foam ceramic plate with a pore diameter of 0.05mm. The average pore diameter of the microporous coating is about 0.01mm.

Example 21

The difference from Example 19 is:

There are catalytic coatings on the surface of the fuel dispersion unit, electric heating element and flame dispersion unit, the coating content is 80-130g/(L carrier), and the weight ratio of each substance in the coating is: Al ₂ O ₃ : CeO ₂ : La ₂ O ₃ :BaO=55:35:3:7. The Pt content was 1.5 g/(L carrier).

Example 22

The difference from Example 20 is:

There are catalytic coatings on the surface of the fuel dispersion unit, electric heating element and flame dispersion unit, the coating content is 80-130g/(L carrier), and the weight ratio of each substance in the coating is: Al ₂ O ₃ : CeO ₂ : La ₂ O ₃ :BaO=55:35:3:7. The Pt content was 1.5 g/(L carrier).

Related comparative examples

The diesel engine 13 operating condition test under the condition of not installing a filter was carried out on the same engine as in the embodiment.

The results of the examples and related comparative examples are shown in Table 1. Experiments 1 to 22 in Table 1 are examples, and Experiment 23 is a related comparative example. Comparing the results of each embodiment with the comparative example, it can be found that in the case of using wall-flow silicon carbide foam ceramics, the filtration efficiency can reach more than 90%, and the filtration efficiency increases with the increase of the volume fraction and the decrease of the average pore size. However, an increase in the volume fraction and a decrease in the average pore size will also cause an increase in the back pressure. The addition of noble metal catalysts can significantly reduce CO and THC emissions, but the reduction effect on particulate emissions is not very significant; the amount of fuel injected during regeneration should not be less than 150ml, otherwise the regeneration will not be complete;

In addition, the resistance of the electric heating element should not be too large. A large resistance will lead to a reduction in power, failure to ignite the injected fuel, and incomplete regeneration. Under the conditions of this patent, the resistance of the electric heating element should preferably be controlled at 50 The regenerated filter can still maintain good filtration efficiency under suitable conditions, indicating that the wall-flow diesel vehicle exhaust particulate filter-regeneration device not only has good purification and filtration performance, but also can be effectively regenerated and has a long service life. life.

Table 1

Claims (5)

1. a wall-flow type filtering-regeneration device for particulates in exhaust gas from diesel vehicle comprises power supply (6), controlled fueling injection equipment, fuel oil dispersal unit (16), electric heating heater (12), flame dispersal unit (15), wall-flow type foamed ceramics particulate filter (9); Wherein the fuel oil dispersal unit (16) before and after electric heating heater (12) and the electric heating heater (12), flame dispersal unit (15) are in wall-flow type foamed ceramics particulate filter (9) is installed on the purifier package casing (8) that links to each other with diesel engine exhaust; Electric heating heater (12) is made up of the foamed ceramics electric heating unit, the foamed ceramics electric heating unit by conductive silicon carbide foam ceramic (24), two metal films (10,11) of being welded on the silicon carbide ceramics electrode base (22,23) that is positioned at conductive silicon carbide foam ceramic (24) two ends constitute, power supply constitutes the loop by metal film (10,11) and conductive silicon carbide foam ceramic (24), is conductive silicon carbide foam ceramic (24) power supply; Controlled fueling injection equipment is made up of electric pump (19), solenoid valve (18), fuel nozzle (17), fuel nozzle (17) is positioned at the upstream of heating heater (12), and the petroleum pipeline between fuel nozzle (17) and the automotive oil tank (21) is provided with electric pump (19), solenoid valve (18); Described wall-flow type foamed ceramics particulate filter (9) is by parallel the combining of multi-disc foam silicon carbide ceramics plate, distance between per two foam silicon carbide ceramics plates is 1.5～3mm, filter interior interlaces and arranges numerous jitties that directly do not communicate mutually, gas passes foamed ceramic panel and enters other passage by a passage, and soot particle is filtered in crossing process; It is characterized in that: the foam silicon carbide ceramics plate that constitutes wall-flow type foamed ceramics particulate filter has single foam aperture or changes the aperture, and the foam silicon carbide ceramics plate that changes the aperture is one of following three kinds of structures: a, is composited by the foam silicon carbide ceramics plate in two or more different apertures; B, on the foam silicon carbide ceramics plate in single aperture, prepare micro porous coating; The combination of c, preceding two kinds of methods, promptly in a, mention compound after the foam silicon carbide ceramics plate on prepare micro porous coating again.

2. according to the described wall-flow type filtering-regeneration device for particulates in exhaust gas from diesel vehicle of claim 1, it is characterized in that: described electric heating heater (12) is formed at least one foamed ceramics electric heating unit, when heater is made of two or two above unit, be relation in parallel between each unit, be linked to be an integral body by the mode of welding between the electrode.

3. according to the described wall-flow type filtering-regeneration device for particulates in exhaust gas from diesel vehicle of claim 1, it is characterized in that: fuel oil dispersal unit (16) is a thick middle, thin foam silicon carbide ceramics all around; Flame dispersal unit (15) is a foam silicon carbide ceramics.

4. according to the described wall-flow type filtering-regeneration device for particulates in exhaust gas from diesel vehicle of claim 1, it is characterized in that: go up preparation active oxidation aluminium paint in fuel oil dispersal unit (16), electric heating heater (12), flame dispersal unit (15), and supported catalyst, the coating levels of every liter of carrier is at 80～130g, and the weight ratio of each material is in the coating: Al ₂O ₃: CeO ₂: La ₂O ₃: BaO=50～55: 30～40: 2～8: 1～10; The used active substance of catalyzer is Pt or Pd, and Pt or Pd total content are 1～5g in every liter of carrier.

5. according to the described wall-flow type filtering-regeneration device for particulates in exhaust gas from diesel vehicle of claim 1, it is characterized in that: described foam silicon carbide ceramics is an elementary cell with polygonal closed loop, and each elementary cell is interconnected to form three-dimensional networks; Constitute relative density 〉=99% of the ceramic muscle of polygonal closed loop unit, average grain size is at 50nm～10 μ m; Described foam silicon carbide ceramics is the mark meter by weight, and its composition is made up of 90%～98% silicon carbide and 10%～2% silicon.

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