JPS5881421A - Ceramic honeycomb filter - Google Patents

Abstract

PURPOSE:To enable the collection of fine particles in a high filtering ratio as well as to easily regenerated and restore a filter, by a method wherein a metal resistance film is coated to a honeycomb structure comprising porous ceramic and the coated honeycomb structure is simultaneously heated by passing current through said resistance film. CONSTITUTION:A honeycomb structure H comprising porous ceramic is molded by baking an extrusion molded honeycomb like ceramic pattern at a temp. slightly lower than a sintering temp. or baking a stock material having an org. substance mixed therein and, to inner walls and side surfaces of each piercing holes J of this structure H, a metal resistance film R comprising Ni, Cr or Ni-Cr is coated by electroless plating or vapor deposition. Because this film R is coated to the surfaces of grid parts of the porous ceramic, fine pores of partition walls F are not clogged. In addition, to the end surface of the structure H, metal closure plate P having plural pores K formed by punching is contacted under pressure so as to close the openings of piercing holes J every other one and a lead wire L is connected thereto to carry out heating during regeneration of a filter by passing current through the metal resistance film R.

Description

Detailed Description of the Invention The present invention is a ceramic lid that collects and burns carbon particles, unburned mist, dust, etc. contained in exhaust gas from automobile engines, exhaust gas from factories, etc. This relates to honeycomb filters.

In the past, attempts have been made to use porous lamic molded into a predetermined shape as a filter for the purpose of collecting carbon particles, dust, etc. in the gas, but the part that acts as a filtration Due to many disadvantages, such as small size, high pressure loss, low mechanical strength, and inability to reopen the pores to restore the filtration effect if they become clogged, It has not yet been widely used as a filter to collect carbon particles, unburned dust, etc. in exhaust gas from gases and factories. If the pores of the engine become clogged, the pressure loss will be large, leading to a significant drop in output and deterioration of fuel efficiency in engines.

Therefore, in order to eliminate these clogging, carbon particles,
It is possible to reburn unburned mist, etc. Possible ways to do this include deploying oxidizing probes and installing burners. However, when reburning using a catalyst, nalphate phosphate, etc. are produced, and unlike in the case of a gas reaction, carbon particles are faceted, so the combustion start temperature is high, making it difficult to burn, and the burner In the case of the type in which the filter is heated from the outside, there is a high risk of the filter becoming broken due to heat shock due to the thermal gradient or carbon combustion heat bath melting. You also need equipment to
Moreover, there are many drawbacks such as the complicated mechanism and the difficulty in controlling the heated bolt.

In view of the above-mentioned situation C, the present invention utilizes the excellent filtration properties of porous ceramics and uses heat generated from the metal resistance film formed on the surface of the porous ceramic to burn and remove carbon particles collected. This is to eliminate clogging and restore filter characteristics again.

The ceramic filter according to the invention consists of a honeycomb structure made of porous ceramic. Materials for this porous ceramic include alumina (Al2O3), cordierite (2Mg0-2AI203・!1si02)A
5 () (3A1203.2810!) is k
'dX (81c) -Silicon nitride (8i3N4)
However, the manufacturing method is to knead each raw material powder with a small amount of other elemental powder, an aiming agent, and a binder, and then extrude it into a honeycomb shape using a specified mold. The honeycomb structure constituting the present invention is sintered in an oxidizing atmosphere or in a non-oxidizing atmosphere such as an argon atmosphere or a vacuum atmosphere at a temperature suitable for the ceramic. Because of the need for a ceramic body, a honeycomb structure made of porous ceramic is manufactured by firing at a slightly lower U degree than that of the sintered structure. Another method is to mix an appropriate amount of organic powder into the raw materials in advance and take advantage of the fact that the organic powder is burned away during firing to form a honeycomb structure made of porous ceramic blocks. May be manufactured.

For example, the honeycomb structure obtained in this way is
A honeycomb structure H made of porous ceramic (hereinafter simply referred to as -I-nicum) used as a filter constituting the exhaust gas purification device C in the middle of the exhaust pipe from the engine E shown in the figure is shown in FIG. As shown in FIG. 2, one end face is a closing plate P with a plurality of punched holes K so as to close every other through hole J/)M of the honeycomb H, as shown in FIG. -) A closing plate p+ in which a large number of punched holes K are lined up and opened and closed in each row is soldered to both ends sc of the honeycomb H, as shown in figure s3, or by a mechanism (not shown). It is held by pressure contact.

In this case, a blockage &P with a punched hole K at a predetermined position is used.
(The PI is installed in such a way that the through hole J is open at one end face of the honeycomb H, and the through hole J of I!Ij- is closed at the other end face.

These closing plates P, P・ are made of nickel (Ni ), a metal plate such as nichrome (Ni-Cr) is used, and a punched hole K is bored in the metal plate.The shape of the punched hole is a large moon shape that matches the shape of the hole formed in the honeycomb 1llc. , square, tricircular, etc. punched holes K may be punched.

Further, R is a metal resistance film which is hardened on the surface of the porous ceramic body forming the honeycomb AH, and C is provided so as to generate heat when energized. This 5-metal resistor 1iKR is nickel (Ni), chromium (Or)
, Nichrome A (Ni-Cr), etc. are suitable.Methods for adhering to the porous ceramic surface of such electrical insulators include sputtering, vapor deposition, and electroless plating. In order to uniformly form the metal resistor #IR on the surface of the gap IIF of the deep narrow through hole J, it is best to use an electroless plating method. For example, according to this nickel electroless plating method, a honeycomb H consisting of a porous ivy body is coated with stannic chloride (8nCl*), Ja chloride, etc. *(After activation treatment with PdC1 or S solution, if it is immersed in a plating solution based on hot or phosphoric acid, a nickel film with metal resistance @n is generated based on the following chemical reaction in the plating solution. be coated.

(H*POz)−+ 120 →H(HPOa)−+
zHNi2" + 2H-+Ni + tH" Deposited metal resistance@Bf') The film thickness depends on the specific resistance of metals such as nickel and chromium, the length between the electrodes, the applied voltage, the required temperature rise when generating heat, etc. Since it is different, a
It is necessary to appropriately set the resistance value, that is, the film thickness. Also, depending on the case, there are times when it is necessary to control the temperature. The metal resistive film 8 is deposited on the surface of the porous ceramic lattice forming the honeycomb H, and although the average pore diameter of the micropores is slightly reduced, it does not clog the micropores.

As mentioned above, the many through holes J that the honeycomb H has are those that are open at the r end. Therefore, the adjacent through holes Jc are configured so that the ends are alternately opened and closed, so that the gas flow is indicated by the arrows in the figure. (The gas that entered the punched hole at one end passes through the fine holes in the partition wall F forming each through hole J from the adjacent through hole, and flows into the through hole Jc whose other end is open. The gas flows out through the punched hole K. In this way, through the through hole J with one side open, the 4C #L, , car 11', i++ Dan particles, and non-carrying particles contained in the gas pass through the fine holes in the partition wall F. Combustion busts and the like have been captured and are now in circulation.

Filter and purify the body.

If such a filtration action is continued, carposi particles and unburned electrolyte particles will gradually accumulate on the partition wall Fc, which will impede the filtration action and increase the pressure loss.

In such a case, the conductors LX are connected to blocking plates p and p'c, which are made of a conductor and also serve as electrode plates.

L2 is connected to 111 via switch 8 as shown in section 1g.
When the switch 83 is closed, the metal resistive film Rc attached to the surface of the gap IIF constituting the through hole J of the fly cam E is energized.

The partition wall F is heated to a high temperature by the heat generated by the gold 1I4Ik anti-W4 blade. Therefore, the partition wall F results, and the partition wall FC
The accumulated carbon particles, unburned mist, etc. are moved and discharged by the high Iic, and the filtration ability of the honeycomb (2) is restored again. Even if the filtration capacity decreases due to the accumulation of filtered Carmage particles, etc., the eye>p made of the honeycomb H made of porous ceramic can easily restore the filtration capacity by closing the switch 8. I'll come. Yes, the switch is set to 80% pressure, which automatically closes the circuit when the pressure loss exceeds a certain level.
- The function may be restored.

Next, we investigated the relationship between the porosity of the porous ceramic used as a filter, the average pore diameter of the pores coated with the honeycomb, the filtration rate for collecting carbon particles, and the pressure loss. Table 1 shows the fixed results when applied to the exhaust gas purification of a diesel engine.The rotation speed of the diesel engine is 2 ooo rp town 7 load,
The outer diameter of the honeycomb structure used as a filter is 144 m, the length is 1505 m, and the effective direction of filtration is approximately 2. ．． 2tllv was used.

-〇- -As is clear from this measurement result, the porosity of the porous ivy that makes up the honeycomb that constitutes the filter must be within the range of at least 10 to 10%. When the porosity is less than 10%, the force loss, that is, the flow resistance, becomes extremely large, and the practicality of the filter decreases.On the other hand, when the porosity is more than io1, the pressure loss is reduced by the average pore diameter of the micropores. As a result, the filtration rate for collecting moldy carbon particles, unburned mist, etc. contained in the exhaust gas of diesel engines is less than half, despite the good performance. Since the pressure loss is extremely large, it cannot be used for practical purposes.

Next, with the number E listed in No. 111aC, the porosity is 47, the average pore value is xsP, the pressure loss is ? -1 of mHH is nickel 1 with a thickness of 0.4μ on both sides of the porous ceramic electric lid.
0- Metal resistive film is attached and the specifications of the two cams are outer diameter 144
■、Length 1sO■The resistance value between conductor L1%L3 is all
, Q is used to purify the exhaust gas of a diesel engine, and when the initial pressure loss of 61-0 rises to about 70- due to the collection of carbon particles, etc., the above-mentioned conductors t, t
, t, and z, a current of approximately 12 V and SOm was applied, and the temperature inside the two-cam structure reached SaO°C.

This state is maintained for 6 seconds to burn off the carbon particles and unburned particles deposited on the partition walls of the honeycomb holes that perform the filtering action. As a result, the clogging of the micropores as a filter is almost eliminated and the pressure drop is close to the original pressure loss.
I was able to recover it.

Although the recovery operation of accumulating carbon particles and mist and completely dissipating them was repeated several times, it was possible to restore the pressure to about 66 or 63 cod Hg.

By the way, the shape of the holes in the honeycomb structure and the cough passage: 1・i
1. The thickness of the partition wall made of porous ceramic that forms the pores and performs the filtration action has a large influence on the filtration rate and pressure loss, but the shape of the through hole in the one used in the above experiment was t4am x 1 ．．
It has a rectangular shape of -, and the thickness of the partition wall is Ol-.

In this case, as the thickness of the partition wall is large, the mechanical strength and filtration rate of I. Nikam Yanagi's corpse will be large (1), but the pressure loss will be especially large ('), so the necessary filtration rate, strength, etc. At a certain thickness, it has filter characteristics.
In addition, it is necessary to appropriately set the size of the through holes, that is, the number of through holes per inch, etc., and in order to apply electricity to the metal resistive film of the honeycomb structure and generate heat to the required temperature, it is necessary to coat it. It is necessary to set in advance suitable ranges such as the resistance value of the metal resistive film, the applied power supply voltage, and the heating time.

1. As an embodiment of the present invention, FIG. 3C shows a case in which a closed gp snow with a punched hole K is used as an electrode for energizing. CI'
= Each through hole is alternately opened at both ends of the cam H.
Sealed with y Yuuga Rei / ni Kame end thiC metal rapid fire, -
The electrodes W may be formed by means such as bonding or metallization, and conductive wires Lt and Ll for conducting electricity may be attached.

As mentioned above, this @7 Iruta has a metal resistive film coated on a honeycomb structure made of porous ceramic, and can be captured with a high filtration rate. Even if the properties of the honeycomb structure deteriorate, the metal resistance of the honeycomb structure can be heated by energizing the particles.

By burning out the electrolytic strike, it can be repeatedly regenerated and used as a ceramic filter with excellent filter characteristics. Moreover, high II
Since it is constructed of C-resistant seven vessels, it is possible to efficiently and permanently purify high-temperature exhaust gas from engines, combustion equipment, etc.

Incidentally, in C above, only the case where gas is filtered is described, but it goes without saying that the method can also be applied to the filtering of liquid.

[Brief explanation of the drawing]

FIG. 1 schematically shows an example in which the filter of the present invention is applied to an engine exhaust gas purification system. 1s-0) (b) is a diagram showing one end surface of the filter O of the embodiment of the present invention, and FIGS. 3 and 4 are respectively diagrams showing FIG.
It is a figure showing a partial sectional view at K-. E8 engine B! Power supply Ll, L2 s conductor H! No. 1 Nikam Structure F; Partition Wall 18 Through Holes R1 Metal Resistance Exhibition Applicant: Kyoto Cera Electric Co., Ltd. Representative: Kazuo Inamori 14-

Claims (1)

[Claims] A honeycomb structure is formed from porous ceramic. The inner wall surface and side surface of each through hole of the honeycomb structure [C
A metal resistor was applied, and each through hole was alternately opened at one end and closed at the other end, and an electrical conductor was provided at each end, and the metal resistor was energized and heated. Seven u-i Tsuku honeycomb filter that uses IF # mold.