CN112031895A

CN112031895A - Spliced non-uniform thermal expansion particle catcher

Info

Publication number: CN112031895A
Application number: CN202010972732.2A
Authority: CN
Inventors: 缪卫国
Original assignee: Changzhou Haowei Environmental Protection Technology Co ltd
Current assignee: Changzhou Haowei Environmental Protection Technology Co ltd
Priority date: 2020-09-16
Filing date: 2020-09-16
Publication date: 2020-12-04

Abstract

The invention relates to a spliced non-uniform thermal expansion particle catcher which is formed by sticking a plurality of blocks through a concrete layer, wherein a plurality of honeycomb-shaped holes are uniformly distributed on each block, the central position of the particle catcher is a central area, the rest areas are peripheral areas, the blocks in the central area are made of silicon carbide, the blocks in the peripheral areas are made of silicon carbide added with materials with high melting point and high expansion coefficient, and the mass ratio of the silicon carbide to the materials with high melting point and high expansion coefficient is 1-10: 1. according to the invention, the material with high melting point and high thermal expansion coefficient is added into the silicon carbide material in the edge region, so that the thermal expansion coefficient of the edge region is increased, the difference of the thermal expansion amount of the center and the edge region is reduced in the regeneration process, the thermal stress is reduced, and the cracking in the regeneration process is avoided.

Description

Spliced non-uniform thermal expansion particle catcher

Technical Field

The invention relates to a tail gas treatment device, in particular to a spliced non-uniform thermal expansion particle catcher.

Background

Honeycomb ceramic particle trap technology has been widely used in the treatment of automobile and truck exhaust. In general, the honeycomb ceramic particle catcher adopts a wall-flow type filtration mode to remove particles in tail gas. The principle is that every other hole is blocked at the inlet, and the other hole is kept smooth; while at the outlet the corresponding hole remains blocked or unblocked conversely. Therefore, the honeycomb ceramic is in a chessboard type of the chess, and ensures that tail gas must pass through the wall, thereby achieving the purpose of retaining particles in the tail gas on the wall.

In application, particles (such as carbon black) in the tail gas are gathered in a channel which is not blocked at the inlet, and after a certain amount of particles is obtained, a computer system starts a regeneration process to burn off the collected carbon black, so that the back pressure of the system is reduced.

Since most of such carbon blacks are small particles of micron or nanometer size, their burning speed is extremely fast, releasing a large amount of heat in a very short time (within ten or more minutes), causing a sharp rise in the internal temperature of the particle trap. If the control is not good, the particle catcher can be burnt. By computer control of the regeneration step, the risk of melting can be reduced. However, thermal stress resulting from too high and too fast a temperature rise is always present and is a major cause of particle trap cracking.

In the temperature rising process of regeneration, the honeycomb ceramic is a large heat accumulator, so that the central temperature of the object is sharply increased, and the temperature of the edge zone is relatively low, so that a temperature gradient is formed, and thermal stress is generated. In the central zone, the body is expanded due to the relatively high temperature, while the low-temperature zones of the edges are contracted with respect to the center, resulting in the thermal stress experienced in the center being compressive stress, while the edge zones are tensile stress. In the case of ceramic bodies, the cracking is generally under tensile stress, so that the cracking caused by recycling is generally in the edge zones.

In addition, in the case of an engine, lubricating oil generates ash, which is accumulated in the inlet passage as much as carbon black, and since the ash is an inorganic oxide, even if carbon black is burned off at the time of regeneration, the ash is retained in the inlet passage. As mileage increases, ash accumulates more, resulting in increased backpressure and, therefore, fuel consumption. For light and medium diesel engines, in order to reduce the impact of ash on back pressure, an asymmetric structure is generally adopted to increase the storage capacity of ash due to the small size of the particle catcher. In this configuration, the inlet channels are large holes and the outlet channels are small holes, thereby providing more ash storage capacity and reducing the effect of ash on back pressure. However, since the distance between the large holes is small, the strength is reduced, and thus cracking is likely to occur, particularly in the region where stress and thermal stress are concentrated.

For most particle traps used in light and medium diesel engines, the carbon loading requirement is high due to volume limitations, and in order to avoid melting of the material during regeneration, silicon carbide materials are generally used. Because the silicon carbide has high thermal expansion coefficient and large thermal stress, the particle catcher is generally made in a splicing mode, and the square blocks of the silicon carbide are stuck together by a concrete layer to form the spliced particle catcher.

The radial heat transfer is difficult due to the presence of the concrete layer, resulting in large temperature differences between the blocks. In this case, the temperature difference between the center and the edge area causes a tensile stress to be concentrated in the edge area, resulting in cracking.

Disclosure of Invention

The invention aims to provide a spliced non-uniform thermal expansion particle catcher which is formed by adding a high-melting-point high-thermal expansion coefficient material into a silicon carbide material in an edge area, so that the thermal expansion coefficient of the edge area is increased, the difference of the thermal expansion amount of a center and the thermal expansion amount of the edge area is reduced in the regeneration process, the thermal stress is reduced, and cracking in the regeneration process is avoided.

In order to achieve the purpose, the technical scheme of the invention is as follows: the utility model provides a concatenation formula non-uniform thermal expansion particle trapper, constitutes after pasting through concrete layer by a plurality of squares, all the equipartition has the honeycomb hole of a plurality of on every square, the central point of particle trapper is central zone, and other regions are peripheral zone, and central zone's square is made for carborundum, and peripheral zone's square is added high melting point high expansion coefficient material in the carborundum and is made, and the quality ratio of carborundum and high melting point high expansion coefficient material is 1-10: 1.

preferably, the high-melting-point high-expansion-coefficient material is one of alumina, magnesia, zirconia and spinel.

Preferably, the particle trap is less than six inches in diameter, with the central region being the centermost square.

Preferably, the particle trap has a diameter greater than six inches and the central area is the centermost nine squares.

Preferably, the mass ratio of the silicon carbide to the high-melting-point and high-expansion-coefficient material is 5: 1.

after the method is adopted, the high-melting-point high-thermal expansion coefficient material is added into the silicon carbide material in the edge area, so that the thermal expansion coefficient of the edge area is increased, the difference of the thermal expansion amounts of the center and the edge area is reduced in the regeneration process, the thermal stress is reduced, and cracking in the regeneration process is avoided.

Drawings

FIG. 1 is a schematic view of a particle trap of the present invention.

Detailed Description

The examples given below illustrate the invention in further detail.

Referring to fig. 1, a spliced non-uniform thermal expansion particle trap is formed by sticking a plurality of blocks 1 through a concrete layer 2, wherein each block 1 is uniformly provided with a plurality of honeycomb-shaped holes 3, the central position of the particle trap is a central area 4, the rest areas are peripheral areas 5, the blocks 1 of the central area 4 are made of silicon carbide, the blocks 1 of the peripheral areas 5 are made of silicon carbide added with a material with a high melting point and a high expansion coefficient, the adding time is that the materials are added during material preparation, and the mass ratio of the silicon carbide to the material with the high melting point and the high expansion coefficient is 1-10: 1. in this embodiment, preferably, the mass ratio of the silicon carbide to the high-melting-point high-expansion-coefficient material is 5: 1.

referring to fig. 1, the high-melting-point and high-expansion-coefficient material of this embodiment is alumina, and may be replaced by magnesia, zirconia, spinel, or other materials, which also has the same effect. As the coefficient of thermal expansion of the material is far larger than that of silicon carbide (25-1000 ℃,4.7x 10)^-6/° c), the peripheral region 5 has a higher coefficient of thermal expansion of the silicon carbide material than the central region after doping.

The particle trap in this embodiment is less than six inches in diameter, with the central region 4 being the centermost one of the squares 1. If the particle trap is larger than six inches in diameter, the central area 4 is the centermost nine squares 1.

Adding high-melting-point high-thermal expansion coefficient material into the silicon carbide material of the peripheral area 5, thereby increasing the thermal expansion coefficient of the peripheral area 5, further reducing the difference between the central thermal expansion amount and the peripheral thermal expansion amount in the regeneration process, reducing the thermal stress, and avoiding cracking in the regeneration process

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the inventive concept of the present invention, and these changes and modifications are all within the scope of the present invention.

Claims

1. A spliced non-uniform thermal expansion particle trap, comprising: constitute after pasting through concrete layer (2) by a plurality of squares (1), all the equipartition has a plurality of honeycomb hole (3) on every square (1), the central point of particle trapper is central zone (4), and other areas are peripheral zone (5), and square (1) of central zone (4) are made for carborundum, and square (1) of peripheral zone (5) is added high melting point high expansion coefficient material for carborundum and is made, and the quality ratio of carborundum and high melting point high expansion coefficient material is 1-10: 1.

2. the tiled, non-uniform thermal expansion particle trap of claim 1, wherein: the high-melting-point and high-expansion-coefficient material is one of aluminum oxide, magnesium oxide, zirconium oxide and spinel.

3. The tiled, non-uniform thermal expansion particle trap of claim 1, wherein: the particle trap has a diameter of less than six inches and the central region (4) is the centermost block (1).

4. The tiled, non-uniform thermal expansion particle trap of claim 1, wherein: the particle trap is larger than six inches in diameter, and the central area (4) is the most central nine squares (1).

5. The tiled, non-uniform thermal expansion particle trap of claim 3, wherein: the mass ratio of the silicon carbide to the high-melting-point and high-expansion-coefficient material is 5: 1.