JP2018159281A - Exhaust emission control device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a constitution compact in size as a whole while installing a sensor in a casing via a sensor boss between catalysts.SOLUTION: In an exhaust emission control device in which a temperature sensor 4 is arranged in a casing 1 via a sensor boss 8, accommodated in the casing 1 in a state that external peripheries of a selective reduction type catalyst 2 and an ammonia reduction catalyst 3 are gripped by catalyst holding materials 5, 6 between the selective reduction type catalyst 2 and the ammonia reduction catalyst 3. The selective reduction type catalyst 2 and the ammonia reduction catalyst 3 are approximately arranged so that opposing end faces of the catalyst holding members 5, 6 retreat to a direction in which they separate from each other while avoiding a weld point W of the sensor boss 8, and opposing end faces of the selective reduction type catalyst 2 and the ammonia reduction catalyst 3 advance up to a position in which they partially overlap on the weld point W of the sensor boss 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exhaust emission control device and a manufacturing method thereof.

  Conventionally, a diesel engine is equipped with a selective catalytic reduction catalyst having a property of selectively reacting NOx (nitrogen oxide) with a reducing agent even in the presence of oxygen in the middle of an exhaust pipe through which exhaust gas flows. A required amount of reducing agent was added upstream of the selective catalytic reduction catalyst, and the reducing agent was allowed to undergo a reduction reaction with NOx in the exhaust gas on the selective catalytic reduction catalyst, thereby reducing the NOx emission concentration. There is something.

On the other hand, in the field of industrial flue gas denitration treatment in plants and the like, the effectiveness of a method for reducing and purifying NOx using ammonia (NH ₃ ) as a reducing agent is already widely known. In recent years, it has been proposed to use urea water as a reducing agent because it is difficult to ensure safety when traveling with ammonia itself.

  That is, when a selective catalytic reduction catalyst is interposed in the middle of the exhaust pipe (generally near the end) and urea water is added to the exhaust gas flow by an injector provided upstream thereof, the urea water is converted into ammonia and carbonic acid. It is decomposed into gas, and NOx in the exhaust gas is satisfactorily reduced and purified by ammonia on the selective catalytic reduction catalyst.

  In such an exhaust purification device using a selective reduction catalyst, it is important to grasp the bed temperature of the selective reduction catalyst with the highest possible accuracy in order to predict NOx purification performance. The exhaust temperature is measured by placing a temperature sensor on the inlet side of the catalyst, and the bed temperature of the selective catalytic reduction catalyst that changes slightly behind the exhaust temperature is thermodynamically estimated from the exhaust temperature and the exhaust flow rate. I am doing so.

  However, since the bed temperature of the selective catalytic reduction catalyst changes slowly depending on its own heat capacity with respect to the exhaust temperature on the inlet side of the selective catalytic reduction catalyst that changes in response to various transient operation conditions, If the exhaust temperature of the selective catalytic reduction catalyst is to be estimated with higher accuracy, the exhaust gas temperature on the outlet side of the selective catalytic reduction catalyst may also be combined. Need to be measured.

  The prior art document information related to the exhaust gas purification apparatus that estimates the bed temperature based on the exhaust gas temperature on the inlet side of the selective catalytic reduction catalyst includes the following patent document 1 and the like.

JP 2009-13930 A

  However, when an ammonia reduction catalyst that oxidizes surplus ammonia is provided at the subsequent stage of this type of selective reduction catalyst, the temperature sensor that measures the exhaust temperature on the outlet side of the selective reduction catalyst is a selective reduction type catalyst. In the past, the distance between the selective reduction catalyst and the ammonia reduction catalyst is considered in consideration of the thermal effect of welding the sensor boss for attaching the temperature sensor. Therefore, there is a problem that the overall configuration becomes large and the mounting property to a vehicle or the like is deteriorated.

  That is, as shown in FIG. 2, when the temperature sensor 4 is installed between the selective reduction catalyst 2 and the ammonia reduction catalyst 3 accommodated in the casing 1, the selective reduction catalyst 2 and the ammonia reduction catalyst 3 are respectively connected. The catalyst holding materials 5 and 6 are wound around the outer periphery and are pressed into the casing 1. After that, a hole 7 is formed between the selective catalytic reduction catalyst 2 and the ammonia reducing catalyst 3 in the casing 1. In addition, the sensor boss 8 is welded all around the hole 7, and the temperature sensor 4 is fitted and installed in the sensor boss 8, so that the selective reduction catalyst 2 and the welded portion W of the sensor boss 8 can be avoided. If the distance S from the ammonia reducing catalyst 3 is not sufficiently long, the catalyst holding members 5 and 6 may be thermally affected when the sensor boss 8 is welded, which may cause burning.

  On the other hand, it is conceivable that the selective reduction catalyst 2 and the ammonia reducing catalyst 3 are press-fitted into the casing 1 after the sensor boss 8 is first welded. There is a possibility that the catalyst holding members 5 and 6 may be damaged, and it is necessary to ensure a long interval S between the selective reduction catalyst 2 and the ammonia reduction catalyst 3 in order to avoid the weld back bead of the sensor boss 8.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to realize a compact overall configuration while a sensor is installed in a casing through a sensor boss between catalysts.

  According to the present invention, a plurality of catalysts are accommodated in a casing in a state where the outer periphery is held by a catalyst holding material, and a sensor is installed in the casing via a sensor boss between at least a pair of successive catalysts among the respective catalysts. In this exhaust purification apparatus, the opposed end surfaces of the catalyst holding members holding the pair of catalysts are retracted in a direction away from each other while avoiding the welded portion of the sensor boss, and the opposed end surfaces of the pair of catalysts Is characterized in that the pair of catalysts are arranged close to each other so as to advance to a position partially overlapping with the welded portion of the sensor boss.

  Thus, in this way, the opposing end surfaces of the catalyst holding members that hold the pair of catalysts have been retracted in advance in a direction away from each other so as to avoid the welded portion of the sensor boss. The catalyst support material is not affected by heat, causing burnout, and the sensor bead's welded back bead does not damage the catalyst support material, and the pair of catalysts themselves have their opposite end faces welded to the sensor boss. Therefore, the distance between the catalysts can be shortened compared to the prior art, and the overall configuration can be made compact.

  Further, when manufacturing the exhaust purification device as described above, a sensor boss is first welded to the casing, and each of the pair of catalysts is pressed together with the catalyst holding material from both directions across the welded portion of the sensor boss. By doing so, the sensor boss is welded to the casing first, so that it is possible to surely avoid the possibility that the heat effect during the welding of the sensor boss will reach the catalyst holding material, and from both directions across the welded portion of the sensor boss. By press-fitting each of the pair of catalysts together with the catalyst holding material, the catalyst holding material does not touch the welded back bead of the sensor boss, and the possibility of damage to the catalyst holding material is reliably avoided.

  According to the exhaust purification apparatus and the manufacturing method thereof of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the overall configuration can be made compact while the sensor is installed in the casing through the sensor boss between the catalysts, and can be mounted on a vehicle or the like. The performance can be greatly improved as compared with the prior art.

  (II) According to the invention described in claim 2 of the present invention, it is possible to more reliably prevent the catalyst holding material from being burned out due to the thermal influence during the welding of the sensor boss and the catalyst holding material from being damaged due to contact with the weld back bead of the sensor boss. It can be avoided.

It is the schematic which shows an example of the form which implements this invention. It is the schematic which shows a prior art example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of an embodiment for carrying out the present invention. In this embodiment, the selective reduction catalyst 2 and the ammonia reduction catalyst 3 are retained as in the case of the conventional example shown in FIG. The outer periphery is held in the casing 1 by the materials 5 and 6, and the temperature sensor 4 is installed in the casing 1 via the sensor boss 8 between the selective reduction catalyst 2 and the ammonia reduction catalyst 3. Although the exhaust purification apparatus is configured, the opposed end surfaces of the catalyst holding members 5 and 6 holding the selective catalytic reduction catalyst 2 and the ammonia reducing catalyst 3 are mutually avoided by avoiding the welding portion W of the sensor boss 8. The selective catalytic reduction catalyst 2 and the ammonia reducing catalyst 3 are moved backward in a direction away from each other, and the opposed end surfaces of the selective catalytic reduction catalyst 2 and the ammonia reducing catalyst 3 are advanced to a position partially overlapping with the welded portion W of the sensor boss 8. Ann Near the reduction catalyst 3 are arranged close.

  Here, in this embodiment, when the opposing end surfaces of the catalyst holding members 5 and 6 are moved away from each other in a direction away from the welding location W of the sensor boss 8, the welding of the catalyst holding members 5 and 6 is performed. Although the case where a portion overlapping with the portion W is partially cut away is illustrated, the entire catalyst holding members 5 and 6 may be shifted in a direction away from each other.

  Thus, in this way, the opposed end faces of the respective catalyst holding members 5 and 6 holding the selective reduction catalyst 2 and the ammonia reducing catalyst 3 are separated from each other by avoiding the welded portion W of the sensor boss 8 in advance. Since the catalyst boss 8 is welded to the sensor boss 8, the catalyst holding material 5, 6 is thermally affected and burns out, or the sensor boss 8 weld back bead damages the catalyst holding material 5, 6. In addition, the selective catalytic reduction catalyst 2 and the ammonia reduction catalyst 3 themselves are arranged close to each other so that their opposing end faces advance to a position partially overlapping with the welding location W of the sensor boss 8. In addition, the distance S between the selective catalytic reduction catalyst 2 and the ammonia reduction catalyst 3 can be shortened, and the overall configuration can be made compact.

  In manufacturing the exhaust gas purification apparatus as described above, the sensor boss 8 is first welded to the casing 1, and the selective reduction catalyst 2 and the ammonia reduction catalyst 3 are formed from both directions sandwiching the welded portion W of the sensor boss 8. It is preferable to press-fit each of the catalyst holding members 5 and 6 together. By doing so, the sensor boss 8 is first welded to the casing 1, so that the heat effect during welding of the sensor boss 8 is applied to the catalyst holding members 5 and 6. And the selective catalytic reduction catalyst 2 and the ammonia reduction catalyst 3 are press-fitted together with the catalyst holding materials 5 and 6 from both directions across the welded portion W of the sensor boss 8. 5 and 6 do not touch the welded back bead of the sensor boss 8, and the possibility of damaging the catalyst holding members 5 and 6 is surely avoided.

  Therefore, according to the above-described embodiment, the catalyst holding members 5 and 6 are burned out due to the thermal influence during the welding of the sensor boss 8 and the catalyst holding members 5 and 6 are more reliably damaged by the contact of the sensor boss 8 with the weld back bead. Since the temperature sensor 4 can be installed in the casing 1 via the sensor boss 8 between the selective reduction catalyst 2 and the ammonia reduction catalyst 3, the overall configuration can be made compact, so that the vehicle or the like can be realized. It is possible to greatly improve the mountability to the conventional one.

  Note that the exhaust purification apparatus and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, and the pair of catalysts may be other than a combination of a selective reduction catalyst and an ammonia reduction catalyst. , A combination of various different catalysts, a combination of the same catalyst may be divided, the sensor is not necessarily limited to a temperature sensor, and various changes may be made without departing from the scope of the present invention. Of course, it can be added.

1 Casing 2 Selective reduction catalyst (catalyst)
3 Ammonia reduction catalyst (catalyst)
4 Temperature sensor (sensor)
5 Catalyst holding material 6 Catalyst holding material 7 Hole 8 Sensor boss S Interval W Welding location

Claims (2)

  Exhaust gas purification in which a plurality of catalysts are accommodated in a casing in a state where the outer periphery is held by a catalyst holding material, and a sensor is installed in the casing via a sensor boss between at least a continuous pair of the catalysts. The opposed end surfaces of the catalyst holding members holding the pair of catalysts are retracted in a direction away from each other so as to avoid the welded portions of the sensor bosses, and the opposed end surfaces of the pair of catalysts are The exhaust purification apparatus, wherein the pair of catalysts are arranged close to each other so as to advance to a position partially overlapping with a welding location.   A method for manufacturing an exhaust emission control device according to claim 1, wherein a sensor boss is first welded to the casing, and each of the pair of catalysts is press-fitted together with the catalyst holding material from both directions sandwiching the welded portion of the sensor boss. A method of manufacturing an exhaust purification device characterized by the above.

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