JP2005034797A - Exhaust gas cleaning filter and production method of filter element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas clarifying filter which can be manufactured at a low cost and can efficiently catch particulate materials in the exhaust gas. <P>SOLUTION: In the exhaust gas cleaning filter for filtering the particulate materials contained in the exhaust gas, either one of a filter element which is made by charging particles obtained by calcining sewage sludge incineration ash or the filter element of a porous body obtained by molding pelletized sewage sludge incineration ash to a prescribed shape and then calcining, or their combination is used as the filter element of the filter. Thereby the particulate materials in the exhaust gas can be efficiently caught and the filter can be manufactured at a low cost. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a filter for purifying exhaust gas discharged from a diesel vehicle, and more particularly to an exhaust gas purification filter made of sewage sludge incineration ash and a method for manufacturing the filter element.

  Particulate matter contained in diesel engine exhaust gas and the like is mostly particulate matter of 1 micron or less, and if these are released into the atmosphere, there is a risk of affecting the human body. Therefore, in the exhaust gas generation source, it is necessary to sufficiently remove the particulate matter in the exhaust gas and discharge the cleaned exhaust gas.

  Generally, as a method for removing these particulate substances, a method is known in which exhaust gas is passed through a heat-resistant ceramic filter, and the particulate substances trapped on the filter are heated and removed by combustion. For example, in a porous honeycomb structure using silicon carbide particles as a constituent material, a filter corresponding to the filtration rate of automobile exhaust gas has been proposed by keeping the porosity within a predetermined range (see, for example, Patent Document 1). .)

JP 2001-199777 A

  However, the more complex the shape structure of the filter made of porous ceramics is, the more expensive raw materials with a stable composition are required, and strict firing control is required. There's a problem.

  An object of the present invention is to provide an exhaust gas purifying filter that is manufactured at low cost and can efficiently collect particulate matter in exhaust gas.

  In general, sewage sludge generated in large quantities in sewage treatment in cities and the like is heated to a high temperature in an incinerator or the like and reduced to a state of sewage sludge incineration ash, and then landfilled as waste. However, since it is difficult to secure a new landfill, a method for reusing these sewage sludge incineration ash as resources is desired. Therefore, the present inventor devised a method of using this sewage sludge incineration ash (hereinafter simply referred to as incineration ash) as a filter for purifying diesel engine exhaust gas, and as a result of earnest examination, granulated incineration ash, It has been found that the particulate matter in the exhaust gas is efficiently filtered by filling the exhaust gas passage with a particulate fired body obtained by firing the obtained granulated body and passing the exhaust gas through the exhaust gas passage. It was.

  That is, when the particulate fired body is filled, the fired body has a complicated structure, and the area where the particulate matter in the exhaust gas comes into contact with the fired body increases. Therefore, the particulate matter can be efficiently collected on the surface of the fired body. Furthermore, since the fired body has a combustion catalytic action in addition to the heat storage characteristics due to the composition of the incinerated ash, the particulate matter collected on the surface of the fired body can be efficiently decomposed by combustion. In addition, since the fired body of the present invention heats the incineration ash at a high temperature (for example, 1050 ° C.), the fired body has heat resistance sufficient to withstand the use environment, and because of its small mutual binding force, There is no need to consider deformation due to expansion or the like.

  Further, instead of a fired body obtained by firing a granulated body obtained by granulating the incinerated ash, a porous body obtained by molding the granulated body into a predetermined shape and firing the formed body may be used. . According to this, the particulate matter in the exhaust gas is filtered by passing through the porous body and efficiently burned and decomposed.

  According to the present invention, by using sewage sludge incineration ash, an exhaust gas purifying filter that efficiently collects particulate matter in exhaust gas can be manufactured at low cost.

  Hereinafter, an embodiment to which the present invention is applied will be described. FIG. 1 is a partial cross-sectional view illustrating the configuration of a diesel engine exhaust gas purification filter to which the present invention is applied. As shown in the figure, an exhaust gas purifying filter (hereinafter simply referred to as a filter) 1 includes a vertical container 2, partition plates 3 and 4, and a particulate fired body 5. The container 2 includes a barrel portion formed in a cylindrical shape having a circular cross section, and a top portion and a bottom portion constricted in a tapered shape, and an exhaust gas introduction port 6 and a purified gas discharge port are respectively provided in the center of the top portion and the bottom portion. 7 is formed. An elbow joint 8 is connected to the purified gas discharge port 7. The partition plate 3 is formed, for example, at a height approximately at the center of the body portion, with the inner wall of the body portion being circumferentially passed, while the partition plate 4 is circumferentially passed with the inner wall of the bottom portion in front of the purified gas discharge port 7. Is formed. A space formed between the partition plates 3 and 4 in the container 2 is filled with a particulate fired body 5. Here, it is preferable that the fired body 5 is uniformly filled so as not to flow in the space when the exhaust gas is introduced. As the partition plates 3 and 4, a net-like member or a porous body having a plurality of holes having such a small resistance as to pass through the exhaust gas that the fired body 5 cannot pass through can be used.

  The fired body 5 in the present embodiment is generally manufactured using powdered incineration ash discharged from an incinerator when incinerating sewage sludge discharged from a city or the like in an incinerator or the like. . That is, by adding a binder such as a known binder or surfactant and water to the incinerated ash, kneading and granulating the granulated product, by firing it at a known firing method, for example, at a high temperature of 1050 ° C. Can be manufactured. The obtained fired body 7 becomes small spherical particles having a diameter of 0.6 to 3.4 mm, for example.

  Moreover, you may make it use the porous body formed by shape | molding said granulated body in a predetermined shape and baking the obtained molded object as a partition plate of this embodiment. In this case, the porosity of the porous body must be determined by a method described later in consideration of the exhaust gas treatment speed, that is, the space velocity.

  Next, the operation | movement is demonstrated about the exhaust gas purification apparatus 1 comprised as mentioned above. Exhaust gas discharged from a diesel engine or the like is introduced into the container 2 of the exhaust gas purification device 1 connected to the exhaust gas flow path, passes through a hole in the partition plate 3, and is filled with the fired body 5 (hereinafter referred to as filling). Is called a layer). The packed bed of the present embodiment has a large opening area in the exhaust gas flow direction compared to the opening area of the conventional porous ceramics, but the flow path has a complicated structure. The contact area increases. Therefore, when the exhaust gas passes through the packed bed, for example, graphite particulate matter in the exhaust gas adheres to the surface of the fired body 5 and is collected.

  In this way, the particulate matter is gradually removed, and the purified exhaust gas passes through the holes of the partition plate 4 and is discharged from the purified gas discharge port 7. On the other hand, since the fired body 5 has heat storage characteristics and combustion catalytic action due to the composition of the incinerated ash, the particulate matter collected on the surface of the fired body 5 is efficiently decomposed by combustion. Note that a specific catalyst (for example, a three-way catalyst) or a reaction promoting substance considering the wettability of the collected substance may be attached to the surface of the fired body 5 in advance.

  The fired body 5 of the present embodiment is separated into coarse particles and fine particles (for example, 0.6 to 1.7 mm as fine particles and 1.8 to 3.4 mm as coarse particles), for example, with a sieve or the like. It is preferable to mix by the compounding ratio. According to this, since the packed state of the fired body 5 in the packed bed becomes dense, the exhaust gas flow path is further complicated, and the collection efficiency of the particulate matter is improved. Further, the particle size of the fired body 5 may be changed with respect to the traveling direction of the exhaust gas, and the particulate matter may be collected step by step for each size.

  Next, the filter element used for the exhaust gas purification filter of the present embodiment will be described with reference to the drawings. FIG. 2 is a schematic view of a filter element 11 filled with a particulate fired body 5. As shown in the figure, the filter element 11 filled in a cylindrical space, for example, collects particulate matter in the exhaust gas introduced from the side surface of the black arrow and from the side surface facing the cleaned exhaust gas. Discharge. Since the filter element 11 has a structure in which the particulate fired bodies 5 made of incinerated ash are filled in a predetermined space and accumulated as described above, the raw material is inexpensive and can be easily manufactured. Further, since the fired body 5 is obtained by firing the granulated incinerated ash at a high temperature, the fired body 5 has heat resistance and does not cause thermal expansion, alteration, or erosion due to high temperature. Moreover, although incineration ash may contain a heavy metal etc., since this embodiment is based on gas contact, these do not elute.

  FIG. 3 is a schematic view of a filter element 13 in which a porous body 12 made of incinerated ash is provided as a partition plate on one side surface of the filter element 11 of FIG. This porous body can be manufactured by molding a granulated body obtained by granulating incinerated ash into, for example, a shape similar to that of a partition plate, and firing. Here, the porosity of a porous body changes with the magnitude | size of the pressure applied to a granulated body at the time of shaping | molding of a granulated body. That is, if the molding pressure is large, the gap between the granulated bodies is reduced and the porosity is reduced. On the other hand, if the molding pressure is reduced or no pressure is applied, the gap is increased and the porosity is increased. The porosity of the porous body is appropriately determined depending on the filtration rate (space velocity) of the exhaust gas.

  In addition, the filter element of this embodiment is not restricted to the above-mentioned embodiment, For example, the porous body 12 may be formed in the both sides | surfaces part of the filter element 11, and the porous body 12 is used independently. May be.

  As described above, according to the present embodiment, a granular fired body, a porous body, or a combination thereof obtained by reusing sewage sludge incineration ash that is produced in large quantities at low cost is used as a filter element of an exhaust gas purification filter. By using it, particulate matter in exhaust gas, particularly diesel engine exhaust gas, can be efficiently collected. Moreover, the exhaust gas purification filter can be easily and inexpensively manufactured by configuring the filter element as described above.

  Hereinafter, the effect of the present invention will be specifically described by way of examples. FIG. 4 shows a configuration diagram of an exhaust gas purifying filter testing machine in the present embodiment. As shown in the figure, this testing machine is provided with two partition plates 20 through which exhaust gas flows in a cylindrical container 22, and the sludge incineration ash is fired in a space sandwiched between the partition plates 20. The filter element 23 is formed by filling a commercially available lightweight fine-grain material (trade name: sludgelite). The filter element 23 is a space having a cross section of φ200 and a thickness of 20 mm. One end of the container 22 is connected to the exhaust system of the diesel engine 21.

The specifications of the diesel engine 21 used in this embodiment are as follows, and kerosene is supplied as fuel.
1) Engine model: 6D16-T
Rated output: 166PS1800RPM
Total displacement: 7545cc
2) Generator type: Denyo power SP, DCA-125 SPMT
In the exhaust gas purification filter testing machine configured as described above, exhaust gas is introduced into the container 22 when the diesel engine 21 is operated, and the soot concentration in the exhaust gas before and after the filter element 23 (IN, OUT) is measured. The soot collection rate collected by the filter element 23 was determined. In this case, the load (engine output) of the diesel engine 21 was increased in the order of 0, 1, 2, 3, and the exhaust gas flow rate and the temperature around the filter element 23 in each load state were measured. The exhaust gas temperature was measured at three locations on the IN side and one location on the OUT side. As sludgelite to be used, two types of coarse particles (particle size: 0.6 to 1.7 mm) and fine particles (particle size: 1.8 to 3.4 mm) were used.

  The concentration of soot (hereinafter referred to as “Soot” as appropriate) in the exhaust gas was measured by attaching smoke meters (SMOKE METER, manufactured by AVL) in the containers 22 around the filter element 23. The measurement principle of the smoke meter is that after passing the exhaust gas through the filter paper, the black portion on the filter paper is irradiated with light to measure FSN (Filtered Smoke Number), and based on the measured value, the FSN-Soot conversion graph is used. The amount of soot is calculated.

  Tables 1 and 2 show the results of measuring the collection rate of the exhaust gas purification filter by the above measurement method. In addition, as a sludgelite which comprises the filter element 23, the case where a coarse grain is used is shown in Table 1, and the case where a fine grain is used is shown in Table 2.

表１の結果によれば、エンジン負荷の上昇とともに、排ガス流量が増加し、これにより捕集率が低下する傾向が見られたが、最大で２５％以上の高い捕集率が実現できた。これに対し、表２によれば、フィルタエレメント２１の粒子を細かくすることにより、負荷変化による捕集率の振れが小さくなり、安定的に高い捕集率が得られることが判った。これは、スラジライトの細粒化にともない、排ガス流路がより複雑化したためと推測される。

According to the results in Table 1, although the exhaust gas flow rate increased with the increase in engine load, and the collection rate tended to decrease, a high collection rate of 25% or more could be realized at the maximum. On the other hand, according to Table 2, it was found that by making the particles of the filter element 21 finer, the fluctuation of the collection rate due to the load change is reduced, and a high collection rate can be stably obtained. This is presumably because the exhaust gas flow path has become more complicated with the finer sludgelite.

It is a block diagram of the filter for exhaust gas purification to which this invention is applied. It is a schematic diagram of a filter element to which the present invention is applied. It is a schematic diagram of another filter element to which the present invention is applied. It is a block diagram of the filter testing machine for exhaust gas purification which concerns on one Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification filter 2,22 Container 3,4,20 Partition plate 5 Sintered body 11,13,23 Filter element 21 Diesel engine

Claims (5)

A filter for purifying particulate matter contained in exhaust gas, wherein the filter is filled with particles obtained by firing sewage sludge incineration ash. A filter for filtering particulate matter contained in exhaust gas, wherein the filter is a porous body formed by granulating sewage sludge incineration ash into a predetermined shape and firing it. Filter for purification. A filter for filtering particulate matter contained in exhaust gas, comprising: two partition plates through which the exhaust gas passes; and particles formed by burning sewage sludge incineration ash filled between the partition plates, The plate is a porous body formed by molding and firing the sewage sludge incineration ash into a predetermined shape. A method for producing an exhaust gas purifying filter element, comprising granulating sewage sludge incinerated ash and filling a predetermined space with particles obtained by firing the obtained granulated body. A method for producing an exhaust gas purifying filter element, characterized by molding granulated sewage sludge incineration ash into a predetermined shape and firing the resulting molded body.

Images