JP2020183724A - Mixing device - Google Patents

Abstract

To provide a mixing device which can convert an additive injected and supplied to exhaust emission to a reductant by favorably atomizing and evaporating it, and can effectively and favorably mix the reductant with the exhaust emission while suppressing exhaust resistance.SOLUTION: In this mixing device (mixer 10) for mixing a liquid additive injected and supplied to exhaust emission which flows in an exhaust passage of a combustion device and exhaust emission, thin-thickness band-shaped plates 11 which are formed into zigzags are constituted so that a prescribed clearance 11C is formed between the adjacent band-shaped plates 11 in a width direction along a thickness direction, and the band-shaped plates 11 are arranged so that exhaust emission flows in from a direction in which the prescribed clearance 11C is formed, and the injected and supplied additive collides with surfaces (collision surfaces 11D) of the thin-thickness band-shaped plates 11 from a direction in which the additive intersects with the surfaces.SELECTED DRAWING: Figure 3

Description

The present invention relates to a mixing device (mixer) that mixes a liquid additive (for example, a reducing agent) used in an exhaust treatment device (for example, a NOx reducing catalyst) with the exhaust gas of a combustion engine.

Purifying the exhaust gas from a combustion device such as an internal combustion engine to suppress the spread of environmental pollution is an important issue. For example, in order to reduce NOx contained in the exhaust gas of an internal combustion engine such as a diesel engine, It has been proposed that the exhaust passage be provided with urea SCR (Selective Catalytic Reduction), which is effective in reducing NOx. Urea SCR is a selective reduction NOx catalyst having the property of being able to selectively react NOx with a reducing agent even in the presence of oxygen, and is ammonia by adding non-toxic urea water to the exhaust. It is thermally decomposed into carbon dioxide gas, and the generated ammonia is used as a reducing agent to reduce and purify NOx in the exhaust on a selective reduction NOx catalyst.
In addition, in this specification, an additive (for example, urea water) which is a source of producing a reducing agent (for example, ammonia) in a NOx reduction catalyst may be expressed as an additive added to exhaust gas.

More specifically, in the conventional exhaust treatment device, for example, a diesel particulate filter with an oxidation catalyst is interposed at a position where the exhaust temperature on the upstream side of the exhaust passage of the diesel engine is relatively high from the viewpoint of regeneration efficiency and the like. A urea water addition device, a mixer, and a urea SCR catalyst are interposed on the downstream side.

Further, for example, in an exhaust gas system as described in Patent Document 1, an oxidation catalyst is interposed at a position where the exhaust temperature on the upstream side of the exhaust passage of a diesel engine is relatively high, and a urea water addition device and a mixer are provided on the downstream side thereof. , Diesel particulate filter and urea SCR catalyst are interposed.
Special Table 2015-537145

However, in these conventional exhaust treatment devices, urea water is evaporated from the urea water addition device, which is a place where urea water is added to the exhaust gas, to be converted into ammonia in a relatively short distance, and this is uniformly mixed with the exhaust gas. Then, there is a fact that it is required to carry it to a urea SCR catalyst.
At the same time, from the viewpoint of maintaining fuel efficiency, the mixer is also required to keep the exhaust resistance low.

In addition, when the exhaust temperature is low (before warming up shortly after starting (when cooling down)), urea water is satisfactorily evaporated and converted to ammonia until the internal combustion engine and the exhaust treatment device are warmed up predeterminedly. It is difficult, and even if the urea SCR catalyst is activated at an early stage, there is a possibility that the reducing agent cannot be supplied well and NOx cannot be sufficiently reduced and purified.
Therefore, there is a fact that the mixer is required to efficiently and surely evaporate and atomize the urea water jetted and supplied from the urea water addition device to convert it into ammonia, and to mix this uniformly with the exhaust gas. is there.

In addition, ammonium carbamate is produced when urea water is dehydrated in the process of conversion to ammonia, which causes the mixer to be severely corroded and durable with conventional general stainless steel materials (for example, SUS436 material). It has been found that there is a problem with sexuality, and there is a fact that mixers are also required to withstand this corrosion and enable long-term use.

The present invention has been made in view of the various circumstances described above, and the additive (for example, urea water) injected and supplied to the exhaust gas from the additive addition device (urea water addition device) is satisfactorily atomized and evaporated to reduce it. It can be converted to an agent (for example, ammonia), and this reducing agent can be effectively mixed well with the exhaust while keeping the exhaust resistance low, so that a NOx reducing catalyst (for example, urea SCR) can be mixed from an early stage after starting. It is an object of the present invention to provide a mixer (mixing device) that can contribute to the reduction of NOx emissions by the catalyst).

Therefore, the present invention
A mixing device for mixing the exhaust with the liquid additive injected and supplied to the exhaust flowing through the exhaust passage of the combustion device.
A thin strip-shaped plate formed in a zigzag shape is configured so that a predetermined gap is formed along the thickness direction between the strip-shaped plates adjacent in the width direction thereof.
The strip-shaped plate is arranged so that the exhaust gas flows in from the direction in which the gap is formed, and the additive supplied by injection collides with the thin strip-shaped plate in the direction intersecting the width direction surface. It is characterized in that it is arranged.

The mixing device according to the present invention can be characterized in that it functions as a heating wire type heater by energizing the thin strip-shaped plate formed in a zigzag shape.

The mixing device according to the present invention is
At the time of cold start, it is energized until the exhaust temperature reaches the specified temperature.
It can be characterized in that the energization is controlled so that the energization is stopped when the exhaust temperature exceeds a predetermined temperature.

In the present invention, the material of the thin strip-shaped plate formed in a zigzag shape can be characterized by being a Ni—Cr based alloy.

According to the present invention, the additive (for example, urea water) injected and supplied to the exhaust gas from the additive addition device (urea water addition device) can be satisfactorily atomized and evaporated to be converted into a reducing agent (for example, ammonia). At the same time, this reducing agent can be effectively mixed with the exhaust gas while keeping the exhaust resistance low, which contributes to the reduction of NOx emissions by the NOx reducing catalyst (for example, urea SCR catalyst) from an early stage after starting. It is possible to provide a mixer (mixing device) that can be used.

It is a block diagram which shows one configuration example of the exhaust treatment system of the internal combustion engine which concerns on one Embodiment of this invention. It is a side view which shows the part of the mixer and the additive addition apparatus which concerns on the same embodiment by extracting. (A) is a perspective view of the same mixer viewed obliquely from the exhaust upstream side to the downstream side, and (B) is a perspective view of the same mixer viewed obliquely from the exhaust downstream side to the upstream side. (A) is a view (front view) of the same mixer as seen from the exhaust upstream side, and (B) is a view of the same mixer as seen from the exhaust downstream side (rear view). (A) is a view (plan view) of the mixer as seen from above orthogonal to the exhaust flow, (B) is a right side view of (A), and (C) is a left side view of (A). is there. (A) is a perspective view showing an example of a case where the mixer according to the same embodiment is configured to function as an electric heating type (heating wire type) heater, and (B) is a strip-shaped plate (belt-shaped) which is heated by energization. It is a perspective view which shows the state which a plate) generated heat, and (C) is a table which shows the calculated value and the actually measured value of the heating capacity of the same mixer. It is a figure which shows the behavior of a droplet in a model experiment which confirmed the state of atomization and atomization when urea water was sprayed toward a wall surface according to the temperature. (A) is a table showing the composition components of the Ni—Cr based alloy according to the present embodiment, and (B) is a table showing the electric resistance of the Ni—Cr based alloy. It is a graph which shows the experimental data about the corrosion resistance of the Ni—Cr based alloy which concerns on this embodiment.

Hereinafter, an embodiment according to the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

As shown in FIG. 1, the exhaust treatment device according to the embodiment of the present invention has a regeneration efficiency or the like at a position where the exhaust temperature on the most upstream side of the exhaust passage 2 of the internal combustion engine 1 such as a diesel combustion engine is relatively high. From the viewpoint, an oxidation catalyst 3 and a diesel particulate filter 4 are interposed, and a urea water addition device (additive addition device) 5 and a urea SCR catalyst (NOx reduction catalyst) 6 are interposed on the downstream side thereof. In addition, in FIG. 1, FIG. 2, FIG. 3, and FIG. 5, reference numeral E indicates an exhaust flow direction.

However, the oxidation catalyst 3 and the diesel particulate filter 4 may be omitted, or may be interposed on the exhaust downstream side of the urea water addition device 5 and the urea SCR catalyst 6.

The urea water addition device 5 is configured to include a solenoid valve type urea water injection nozzle 5A that injects and supplies urea water (an additive that is a source of a reducing agent) to exhaust gas at a predetermined timing. The urea water is sent from the urea water tank (not shown) to the urea water injection nozzle 5A via the urea water supply pump (not shown).

The urea water injected and supplied from the urea water injection nozzle 5A collides with the mixer (mixing device) 10 provided in the exhaust passage 2 and is atomized to promote evaporation.

As shown in FIGS. 3 (A) and 3 (B), the mixer 10 according to the present embodiment is a continuous single plate formed of a thin plate adjusted to a predetermined thickness and length by cold rolling. The strip-shaped plate (belt-shaped plate) 11 is folded back in a zigzag shape to form a straight portion 11A (for example, a width of about 2 mm and a thickness of about 0.5 mm) (however, a width of about 1.5 to 10 mm (preferably, about 1.5 to 10 mm). (It can be about 2 to 5 mm) and about 0.3 to 1.5 mm in thickness) and the folded-back portion 11B, and some folded-back portions 11B are supported by the bracket 12.

Specifically, for example, on a thin metal flat plate (for example, a thickness of 0.5 mm) (however, the thickness can be about 0.3 to 1.5 mm), FIG. 5 (A) A cut as shown in is made into a zigzag shape by laser processing or the like, and then stretched so that the distance between the straight portions 11A is separated in the thickness direction (height direction) as shown in FIGS. 3 and 4. Can be formed by However, by joining one end of the plurality of straight portions 11A in a staggered manner, it is possible to create a structure similar to that shown in FIGS. 3 to 5. In FIGS. 5B and 5C, reference numeral Z indicates the center of the injection direction of the additive (urea water).

The bracket 12 is fixed to the inside of the exhaust passage 2, but is fixed so as to have the arrangement shown in FIG. 4A when viewed from the upstream side to the downstream side of the exhaust flow.

Therefore, the exhaust gas discharged from the diesel combustion engine 1, passing through the oxidation catalyst 3 and the diesel particulate filter 4 and flowing from the upstream side passes through the gaps 11C formed between the straight line portions 11A. Will flow to the downstream side.
Therefore, the mixer 10 according to the present embodiment can suppress the ventilation resistance of the exhaust gas to a low level.

On the other hand, the urea water jetted and supplied from the urea water injection nozzle 5A is ejected from the upper side to the lower side of the mixer 10 as shown in FIG. In FIG. 2, reference numeral X indicates a urea water supply passage, and reference numeral Y indicates an example of spraying urea water injected and supplied from the urea water injection nozzle 5A.

At this time, when the mixer 10 is viewed from the urea water injection nozzle 5A side, as shown in FIG. 5A, the plurality of straight portions 11A are arranged so as to be arranged in parallel (horizontally) without a gap. Therefore, the urea water injected and supplied from the urea water injection nozzle 5A is surely collided with the upper surface (collision surface 11D) of the straight line portion 11A, and atomization / atomization can be promoted.

That is, according to the mixer 10 according to the present embodiment, urea water can be effectively collided with a wall surface having a large area while suppressing the ventilation resistance of the exhaust gas to be low, so that atomization / atomization can be promoted. It can contribute to the promotion of conversion of urea water to ammonia.

Further, according to the mixer 10 according to the present embodiment, the exhaust gas flowing from the upstream side passes through the plurality of gaps 11C formed between the plurality of straight line portions 11A, and at that time, each straight line is formed. Since it collides with the upper surface (collision surface 11D) of the portion 11A and flows to the downstream side while being mixed with the atomized / atomized urea water, the exhaust gas and the urea water can be uniformly mixed. You can also play.

In other words, when looking at the cross section (radial cross section) of the exhaust passage 2, as shown in FIGS. 3 and 4, the upper surface (collision surface 11D) of the straight portion 11A, which is the collision surface with urea water, is Since there are a plurality of them in the cross section and they are dispersed in the cross section, urea water can be spread evenly in the cross section of the exhaust passage to disperse ammonia, and urea SCR can be dispersed. It can contribute to the improvement of NOx reduction efficiency in the catalyst 6.

As described above, in the present embodiment, the thin strip-shaped plates 11 constituting the mixer 10 are formed in a zigzag shape, and the thickness direction (thickness direction of the thin strip-shaped plates 11) is formed between the adjacent strip-shaped plates 11. Is arranged so that a gap (gap 11C) is formed (stretched in the thickness direction), and exhaust gas flows in from the direction (thickness direction) in which the gap (gap 11C) is formed. In addition, the additive is sprayed from the direction intersecting the exhaust flow (the direction facing the upper surface of the thin strip-shaped plate 11).

That is, in the mixer 10 according to the present embodiment, a predetermined gap 11C is formed along the thickness direction between the thin strip-shaped plates 11 formed in a zigzag shape and adjacent to the strip-shaped plates 11 in the width direction. In addition to the above, the mixer 10 is arranged so that the exhaust gas flows in from the direction in which the gap 11C is formed (the thickness direction of the strip-shaped plate 11), and the additive supplied by injection is thin. The strip-shaped plate 11 is arranged so as to collide from the widthwise surface (collision surface 11D) and the direction (direction facing each other at a predetermined angle).
The predetermined angle can be a substantially right angle, but can be any other crossing angle (crossing angle larger than 0 degrees and smaller than 180 degrees).

As a result, the exhaust gas passes through the gap (gap 11C), so that the ventilation resistance can be kept small, while the additive is arranged in a form such that there is no gap when viewed from the injection direction. Since it collides with the upper surface of the NOx, it is possible to promote the atomization of the additive, thereby promoting the atomization, evaporation, and conversion of the additive to a reducing agent, which in turn can contribute to the improvement of the NOx reduction effect of the NOx reduction catalyst. Is.

In the present embodiment, as shown in FIGS. 3B and 5A, the folding portion 11B (top portion 11B1) is located on the exhaust downstream side of the folding portion 11B at the uppermost portion in the drawing. ), A plurality of straight portions 11A and folded portions 11B (parts on the downstream side of the exhaust) are provided, but this is also strip-shaped on the downstream side (rear side) of the exhaust from the folded portions 11B (top 11B1). By providing the plate (belt-shaped plate) 11 of the above, the chance of the exhaust coming into contact with the straight portion 11A is increased, thereby further promoting the mixing of the exhaust and the evaporated urea and thus the ammonia. It can be omitted if it is possible or if there are restrictions on the installation space.

However, by providing a strip-shaped plate (belt-shaped plate) 11 on the downstream side (rear side) of the exhaust from the folded-back portion 11B (uppermost portion 11B1), the mixing of the exhaust and the evaporated urea and thus the ammonia is further promoted. Therefore, it is possible to contribute to the improvement of the NOx reduction effect of the NOx reduction catalyst.

By the way, as described above, when the internal combustion engine 1 has a low exhaust temperature (before warming up shortly after starting (during cooling)), urea is used until the internal combustion engine 1 and the exhaust treatment device are warmed up to a predetermined value. It is difficult to satisfactorily evaporate water and convert it to ammonia, and even if the urea SCR catalyst 6 is activated at an early stage, the reducing agent is not supplied well and NOx cannot be sufficiently reduced and purified. There is a fear that.

Therefore, in the mixer 10 according to the present embodiment, as shown in FIG. 6A, the strip-shaped plate (belt-shaped plate) 11 is made of metal, and the portion (folded portion 11B) in contact with the bracket 12 is formed. By covering the periphery with an insulator 11E such as alumina, the strip-shaped plate (belt-shaped plate) 11 can be configured to be energized and heated.

That is, the mixer 10 according to the present embodiment can be configured to function as a heating type (heating wire type) heater. Then, as shown in FIGS. 6 (B) (the portion that looks white indicates the high temperature portion) and FIG. 6 (C), the mixer 10 according to the present embodiment has a sufficient heating capacity as a heater. (When a Ni—Cr alloy having a width of 2 mm and a thickness of about 0.5 mm is used for the straight portion 11A) has been confirmed.

In addition, the results of a model experiment in which the state of atomization and atomization when the urea water was sprayed toward the wall surface was confirmed according to the temperature are shown in FIG. 7 (for a period of 10 msec immediately after the injection at each temperature). A series of photographs taken). In the figure, it is shown that the stronger the degree of atomization / atomization, the stronger the degree of whiteness. In FIG. 7, the uppermost row shows an image immediately after the start of urea water injection, and then the image obtained by frame-advancing the captured moving image every several msec is shown in the lower row. From this figure, it can be seen that there is no atomization / atomization at 100 ° C. or lower, and that the higher the temperature, the shorter the atomization / atomization is completed.
<Injecting>
The second stage from the top of the frame-by-frame image in FIG. 7 corresponds to during injection, but the spray is atomized by collision and reflection of urea water having a boiling point of 87 ° C up to a mixer surface temperature of 100 ° C. It turns out that it is difficult to do. That is, it can be seen that the degree of whiteness is low.

On the other hand, when the surface temperature of the urea collision wall surface (corresponding to the upper surface of the straight portion 11A of the mixer 10 (corresponding to the collision surface 11D with urea water)) is set to a predetermined temperature (for example, 125 ° C) or higher. It was found that immediately after the urea water injected from the urea water injection nozzle collided with the wall surface, atomization due to evaporation proceeded.

<After injection>
The third and subsequent stages from the top of the frame-by-frame image in FIG. 7 correspond to after injection, but after injection (after the end of injection), if the surface temperature of the urea collision wall surface is lower than 100 ° C, evaporation does not occur. Observed as.
At 125 ° C or higher, the evaporation rate (degree of evaporation) differs depending on the surface temperature, and it is preferable to set it at 150 ° C or higher from the viewpoint of promoting atomization.

That is, when the internal combustion engine 1 has a low exhaust temperature (before warming up shortly after starting (when cooling down)) (so-called cold start), the exhaust temperature near the exhaust inlet of the mixer 10 becomes a predetermined temperature (injected urea). The mixer 10 is energized to operate the mixer 10 as an electric heater until the temperature reaches 150 ° C (preferably 180 ° C at which urea water evaporates), which promotes atomization and evaporation of water. By promoting atomization and atomization and promoting conversion to ammonia, it is possible to contribute to exerting the NOx reduction effect of the urea SCR catalyst 6 at an early stage after starting.

Further, after warming up the internal combustion engine 1 and the exhaust treatment system (the predetermined temperature (the exhaust temperature near the exhaust inlet of the mixer 10 is 150 ° C., which promotes atomization and evaporation of the injected urea water). Preferably, when the temperature becomes higher than 180 ° C)) where the urea water evaporates), the engine controller (ECU) 100 (ECU) 100 (ECU) so as to stop the energization of the mixer 10 and operate the mixer 10 as a normal mixing device. (See FIG. 1) is preferably controlled. In FIG. 1, reference numeral 101 indicates an additive injection supply control signal, and reference numeral 102 indicates an electric heater energization control signal.

As described above, in the mixer 10 according to the present embodiment, since the elongated thin strip-shaped plate (belt-shaped plate) 11 is formed in a zigzag shape, this can be directly used as a heating wire. Since it is not necessary to provide a type heater or the like, it is possible to contribute to the promotion of atomization and evaporation of urea water in the mixer 10 while simplifying the configuration, reducing the cost, and reducing the weight and size.

Further, as described above, ammonium carbamate is produced when the urea water is dehydrated, which causes the mixer to be severely corroded and durable in the conventional general stainless steel material (for example, SUS436 material). Problems can occur. Further, even if SUS447 material (30% Cr) having high corrosion resistance was used, corrosion could not be effectively suppressed yet.

Therefore, in the present embodiment, a highly corroded portion (a place where urea water collides and evaporates) such as a strip-shaped plate (belt-shaped plate) 11 and a bracket 12 of the mixer 10 is created with a Ni—Cr alloy. As a result, it was confirmed that the corrosion wear of the mixer 10 to which the urea water collides with the relatively high temperature can be effectively suppressed.
Although it is a substitute test using a test piece, FIG. 9 shows an example of experimental results in which the corrosion rate of a Ni—Cr alloy in boiling nitric acid is compared with that of other materials.

The "Ni—Cr alloy" refers to a Ni-based alloy containing 40 to 50% Cr in mass%. Of these, a high Cr-containing Ni-based heat-resistant corrosion-resistant alloy (representative component: Ni-45Cr-1Mo (mass%)), which exhibits excellent properties in terms of both corrosion resistance and heat resistance, is preferable (for the composition, "Ni" in FIG. 8 (A). -Cr alloys "). A particularly preferable component range is as follows.

By mass%, Cr: 40 to 50%, Mo: 0.1 to 2.0%, Fe: more than 0% and 3% or less, Mn: more than 0% and 0.5% or less, Si: 0% More than 0.1%, Al: more than 0% and less than 0.3%, Ti: more than 0% and less than 0.3%, Mg: 0.01% or less, N: 0.04% or less , B: 0.01% or less, and as selective elements, Co: 3% or less, V: 0.1% or less, Zr: 0.05% or less, Cu: 0.02% or less, W: An alloy having a composition in which the balance is composed of Ni and unavoidable impurities, which can further contain any one or more of 0.1% or less, Nb: 0.1% or less, and Ca: 0.002% or less. ..

Further, in the severely corroded part (the place where urea water collides and evaporates) such as the strip-shaped plate (belt-shaped plate) 11 and the bracket 12 of the mixer 10, the electric resistance is increased in order to exert the heating capacity as a heater. It is preferably in the range of 100 to 150 μΩ · m. The electrical resistance of a typical Ni—Cr alloy shown in FIG. 8 (A) is 110 μΩ · m as shown in FIG. 8 (B). On the other hand, stainless steel, which is a conventional material, has a small electric resistance, and cannot be heated at a practical size, and the cross-sectional area must be reduced, which is not preferable.

As described above, according to the present embodiment, the material of at least the strip-shaped plate (belt-shaped plate) 11 of the mixer 10 is a high Cr-containing Ni-based heat-resistant corrosion-resistant alloy (Ni-45Cr-1Mo (mass%)). Since corrosion can be effectively suppressed even for ammonium carbamate produced in the process of converting urea water to ammonia, it can withstand long-term use even if it is used as a mixer for urea SCR catalyst 6. It becomes possible.

As described above, according to the present embodiment, the additive (for example, urea water) injected and supplied from the additive addition device (urea water addition device) to the exhaust gas is satisfactorily atomized and evaporated to satisfactorily atomize and evaporate the reducing agent (for example). It can be converted to (ammonia), and this reducing agent can be effectively mixed well with the exhaust while keeping the exhaust resistance low, so that a NOx reducing catalyst (for example, urea SCR catalyst) can be used from an early stage after starting. It is possible to provide a mixer (mixing device) that can contribute to the reduction of NOx emissions.

By the way, in the present embodiment, the diesel combustion engine 1 has been described as an example, but the present invention is not limited to this, and if it is a combustion device including exhaust, a gasoline engine, a gas turbine, or another internal combustion engine. In addition, it can be an external combustion engine, and can be any mobile or stationary combustion device regardless of the combustion method.

Further, in the present embodiment, the urea SCR catalyst 6 is exemplified as the NOx reduction catalyst, and the additive that is the source of producing the reducing agent supplied to the NOx reduction catalyst is described as urea water, but the present invention is limited thereto. If it is a mixer (mixing device) that is required to add a liquid additive to the exhaust gas flowing through the exhaust passage and mix the additive and the exhaust gas, the present invention is used. Applicable.

For example, when an HC (hydrocarbon) selective reduction NOx catalyst {HC-SCR (HC-Selective Catalytic Reduction) type catalyst (HC-SCR catalyst) is interposed as a NOx reduction catalyst instead of the urea SCR catalyst, A liquid additive such as light oil or kerosene, which is a source of producing HC which is a reducing agent for the HC selective reduction NOx catalyst, corresponds to an example of the liquid additive according to the present invention.

The embodiments described above are merely examples for explaining the present invention, and various modifications can be made without departing from the gist of the present invention.

1 Internal combustion engine (diesel combustion engine, etc.)
2 Exhaust passage 3 Oxidation catalyst 4 Diesel particulate filter 5 Urea water addition device 5A Urea water injection nozzle 6 Urea SCR catalyst 10 Mixer (mixing device)
11 Strip-shaped plate (belt-shaped plate) (thin strip-shaped plate according to the present invention)
11A Straight line part 11A
11B Folded part 11C Gap 11D Collision surface (upper surface of straight part 11A)
11E Insulator 12 Bracket

Claims (4)

A mixing device for mixing the exhaust with the liquid additive injected and supplied to the exhaust flowing through the exhaust passage of the combustion device.
A thin strip-shaped plate formed in a zigzag shape is configured so that a predetermined gap is formed along the thickness direction between the strip-shaped plates adjacent in the width direction thereof.
The strip-shaped plate is arranged so that the exhaust gas flows in from the direction in which the gap is formed, and the additive supplied by injection collides with the thin strip-shaped plate in the direction intersecting the width direction surface. A mixing device, characterized in that it is disposed. The mixing device according to claim 1, wherein the thin strip-shaped plate formed in a zigzag shape is energized to function as a heating wire type heater. At the time of cold start, it is energized until the exhaust temperature reaches the specified temperature.
The mixing device according to claim 2, wherein the energization is controlled so that the energization is stopped when the exhaust temperature exceeds a predetermined temperature. The mixing apparatus according to any one of claims 1 to 3, wherein the material of the thin strip-shaped plate formed in a zigzag shape is a Ni—Cr alloy.