JP2009108726A - Exhaust emission control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device capable of uniformly diffusing urea water of a reducing agent into exhaust emission, and efficiently reducing nitrogen oxides included in the exhaust emission for cleaning the exhaust emission. <P>SOLUTION: This device includes a urea injection nozzle 13 which adds urea water 12 to an exhaust emission duct 11, an SCR catalyst 14 placed downstream of the position where the urea water is added by the urea injection nozzle, in the exhaust emission flow direction, in the duct 11 and reduces the nitrogen oxides in the exhaust emission to nitrogen with the urea water, and a stirring member 15 placed between the nozzle 13 and catalyst 14 and gives swirl to the exhaust emission. The stirring member has swirling blades with inclination of 30-60° in relation to a flow direction to swirl the exhaust emission along the flow direction. Distance L1 between the stirring member and the nozzle 13 is set to a ratio of 1.8-6.3 to a diameter D1 of the duct 11. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an exhaust gas purification device that purifies the exhaust gas by adding a reducing agent to the exhaust gas and reducing nitrogen oxides in the exhaust gas, and in particular, exhaust gas discharged from an internal combustion engine such as a diesel engine or a gas engine, or waste It is effective when applied to purify exhaust gas by reducing nitrogen oxides in the exhaust gas discharged from a furnace that incinerates or melts.

  Exhaust gas discharged from internal combustion engines such as engines and furnaces that incinerate waste contains nitrogen oxides. By reducing the nitrogen oxides with an exhaust gas purification device, the exhaust gas is purified to the atmosphere. It is trying to discharge. This exhaust gas purifying apparatus purifies exhaust gas by using ammonia as a reducing agent, bringing the ammonia and nitrogen oxides in the exhaust gas into contact with each other by a denitration catalyst and reducing them to nitrogen. In such an exhaust gas purifying apparatus, it has been studied to improve the reduction and removal of nitrogen oxides by a catalyst by using urea as a raw material of ammonia and uniformly diffusing the urea into the exhaust gas.

  For example, Patent Document 1 below discloses an exhaust gas treatment apparatus in which a carburetor with a heater is provided in the vicinity of a urea water injection valve and a swirl vane is provided. In this exhaust gas treatment device, urea water injected from a urea water injection device is vaporized by a vaporizer provided with a heater to form urea vapor, and urea vapor is diffused into the exhaust gas by swirl vanes.

  In addition, a cylindrical swirl chamber with one end face of the exhaust gas duct closed is provided, a urea water spray nozzle is provided on the closed end face of the swirl chamber, and an exhaust gas inlet duct is further provided to introduce exhaust gas into the swirl chamber from a tangential direction. Urea water vaporizers are known. In this urea water vaporizer, an uneven ammonia concentration distribution is prevented on the inlet side of the denitration catalyst disposed downstream of the swirl chamber in the exhaust gas flow direction.

  Further, there is an exhaust gas purification apparatus in which a porous plate, a mixing plate, a shielding plate, etc. are installed between a urea water spray nozzle that sprays urea water in an exhaust gas passage through which exhaust gas flows and a denitration catalyst disposed in the exhaust gas passage. Are known. In such an exhaust gas purification apparatus, the flow of the exhaust gas is disturbed by the installation of the member, and the urea water is uniformly diffused in the exhaust gas in the radial cross section of the exhaust gas passage.

JP-A-2005-344597 (see, for example, paragraphs [0016]-[0041], [FIG. 1] to [FIG. 6], etc.)

  The exhaust gas treatment device described in Patent Document 1 described above is a device that includes a vaporizer with a heater in addition to the urea water injection device, and the device itself becomes complicated due to the installation of the vaporizer. This leads to an increase in size and an increase in equipment cost.

  Further, in the urea water vaporizer described above, since the exhaust gas flow is swirled immediately after the urea water spray from the urea water spray nozzle, the urea water droplets sprayed from the nozzle due to the increased exhaust gas flow rate are caused by the swirl chamber. If the swirl becomes too large, it will be affected by this and will collide with the wall surface of the exhaust gas duct, etc. and will not be able to supply the reducing agent uniformly to the denitration catalyst. Conversely, if the exhaust gas flow rate is reduced and the swirling of the exhaust gas in the swirl chamber becomes too small, the reducing agent cannot be uniformly diffused into the exhaust gas and the reducing agent cannot be uniformly supplied to the denitration catalyst. As a result, the predetermined denitration performance of the denitration catalyst may not be obtained. In addition, when the exhaust gas temperature is lowered, solid substances may be deposited, causing corrosion and clogging of the exhaust gas duct.

  Furthermore, when a perforated plate, a mixing plate, a shielding plate, or the like is installed, the exhaust gas flow path must be lengthened to increase the degree of mixing of the reducing agent with the exhaust gas, which may result in a large size. . Conversely, if the exhaust gas flow path is shortened, the concentration distribution of the reducing agent is biased in the radial cross section, and the reducing agent does not contact the NOx removal catalyst uniformly, thereby obtaining the predetermined NOx removal performance of the NOx removal catalyst. There was a risk of not being able to. In addition, if the flow rate of the exhaust gas changes, the reducing agent may not be uniformly dispersed in the exhaust gas.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and with a simple structure, the reducing agent can be uniformly diffused in the exhaust gas to efficiently reduce the nitrogen oxides in the exhaust gas, thereby purifying the exhaust gas. An object is to provide an exhaust gas purification device.

  An exhaust gas purifying apparatus according to a first invention for solving the above-mentioned problem is an exhaust gas purifying apparatus that reduces and purifies nitrogen oxides in exhaust gas flowing through an exhaust gas duct, and adds a reducing agent to the exhaust gas duct. A reducing agent adding means that is disposed in the exhaust gas duct so as to be located downstream of the reducing agent addition position by the reducing agent adding means in the flow direction of the exhaust gas, and the nitrogen oxide in the exhaust gas is A reduction catalyst that reduces the nitrogen to a reducing agent; and a stirring member that is disposed between the reducing agent addition means and the reduction catalyst and that imparts a swirling flow to the exhaust gas. A swirl vane having an inclination of 30 ° or more and 60 ° or less with respect to the flow direction so as to swirl along the flow direction, and a distance L1 between the stirring member and the reduction catalyst is the exhaust gas The ratio is 1.8 to 6.3 in terms of the ratio of the cut to the diameter D1.

  An exhaust gas purifying apparatus according to a second invention that solves the above-described problem is the exhaust gas purifying apparatus according to the first invention, wherein the stirring member is an evaporation member that promotes evaporation of the reducing agent. And

  An exhaust gas purifying apparatus according to a third invention for solving the above-described problem is the exhaust gas purifying apparatus according to the first or second invention, wherein the swirl blade has a plurality of holes or protrusions. It is characterized by that.

  An exhaust gas purifying apparatus according to a fourth invention for solving the above-mentioned problem is an exhaust gas purifying apparatus according to any one of the first to third inventions, wherein a distance between the reducing agent adding means and the stirring member. L2 is 7 or less in a ratio to the diameter D1 of the exhaust gas duct.

  An exhaust gas purifying apparatus according to a fifth invention for solving the above-described problem is the exhaust gas purifying apparatus according to any one of the first to fourth inventions, wherein the stirring member is disposed between the exhaust duct and the exhaust gas purifying apparatus. The exhaust gas duct is supported via a support member so as to have a gap.

  An exhaust gas purification apparatus according to a sixth invention for solving the above-described problem is an exhaust gas purification apparatus according to any one of the first to fifth inventions, wherein heat insulation is provided between the stirring member and the exhaust gas duct. The material is arranged.

  An exhaust gas purifying apparatus according to a seventh invention for solving the above-mentioned problem is an exhaust gas purifying apparatus according to any one of the first to sixth inventions, wherein the stirring member is coated with a hydrolysis catalyst. It is characterized by being.

  An exhaust gas purifying apparatus according to an eighth invention for solving the above-described problem is an exhaust gas purifying apparatus according to any one of the first to seventh inventions, wherein a plurality of the agitating members are arranged in the exhaust gas circulation direction. It is characterized by.

  An exhaust gas purification apparatus according to a ninth invention for solving the above-described problem is the exhaust gas purification apparatus according to any one of the first to eighth inventions, wherein the stirring member rotates with respect to the exhaust gas duct. It has the rotation support means which supports so that it is possible.

  An exhaust gas purifying apparatus according to a tenth invention for solving the above-described problem is an exhaust gas purifying apparatus according to any one of the first to ninth inventions, wherein the reducing agent adding means supplies the reducing agent to the reducing agent. The stirrer is added to the vicinity of the wall surface of the exhaust gas duct, and the stirring member has a hole at a position located in a central portion of the exhaust gas duct in the exhaust gas circulation direction.

  According to the exhaust gas purifying apparatus according to the first aspect of the present invention, there is provided an exhaust gas purifying apparatus for reducing and purifying nitrogen oxides in the exhaust gas flowing in the exhaust gas duct, wherein the reducing agent is added to the exhaust gas duct. And in the exhaust gas duct so as to be located on the downstream side in the flow direction of the exhaust gas from the addition position of the reducing agent by the reducing agent addition means, and nitrogen oxides in the exhaust gas are converted into nitrogen by the reducing agent. A reducing catalyst for reducing the exhaust gas, and a stirring member that is disposed between the reducing agent adding means and the reducing catalyst and imparts a swirling flow to the exhaust gas, and the stirring member passes the exhaust gas along a flow direction. Swirling blades having an inclination of 30 ° or more and 60 ° or less with respect to the flow direction so that the distance L1 between the stirring member and the reduction catalyst is equal to the diameter D1 of the exhaust gas duct. When the ratio is 1.8 or more and 6.3 or less, the reducing agent added from the reducing agent adding means is completely evaporated, and the reducing agent is uniformly diffused into the exhaust gas by the stirring member. And a reducing agent contacts uniformly in the cross section with respect to the exhaust gas distribution direction in a reduction catalyst, and it can reduce and remove the nitrogen oxide in exhaust gas effectively using a reducing agent with a reduction catalyst. Thus, the denitration performance can be improved with a simple configuration of adjusting the distance L1 between the stirring member and the reduction catalyst with respect to the angle of the swirl vane and the diameter D1 of the exhaust gas duct. Moreover, since the exhaust gas duct length can be optimized, the exhaust gas purification unit itself can be made compact.

  According to the exhaust gas purification apparatus according to the second aspect of the invention, the stirring member is an evaporation member that promotes evaporation of the reducing agent, so that the same effects as the exhaust gas purification apparatus according to the first aspect of the invention can be achieved. Since the reducing agent droplets evaporate and gasify on the evaporation member, the exhaust gas duct length (distance between the reducing agent addition means and the evaporation member) required for droplet evaporation can be shortened, further reducing the size of the apparatus. Can be planned.

  According to the exhaust gas purification apparatus according to the third aspect of the invention, the swirl vanes are formed with a plurality of holes or protrusions, so that the same effect as the exhaust gas purification apparatus according to the first and second aspects of the invention is achieved. In addition, the contact area with the exhaust gas is widened, and the heat of the exhaust gas can be more efficiently transferred to the reducing agent droplets to promote evaporation. Therefore, the length of the exhaust gas duct required for droplet evaporation can be shortened, and the apparatus can be further downsized.

  According to the exhaust gas purification apparatus of the fourth invention, the distance L2 between the reducing agent addition means and the stirring member is 7 or less in terms of the ratio to the diameter D1 of the exhaust gas duct. As in the exhaust gas purifying apparatus according to the above, the exhaust gas duct length required for droplet evaporation can be shortened, and the apparatus can be further downsized.

  According to the exhaust gas purification apparatus of the fifth aspect of the invention, the stirring member is supported by the exhaust gas duct via the support member so as to have a gap with the exhaust gas duct. In addition to the same operational effects as the exhaust gas purifying apparatus according to the invention of 4, the contact area between the agitating member and the exhaust gas duct can be reduced, and the temperature of the agitating member is not lowered due to heat radiation to the exhaust gas duct, and the reduction to the agitating member is achieved. The sticking of the agent can be prevented.

  According to the exhaust gas purification apparatus according to the sixth aspect of the present invention, the same action as that of the exhaust gas purification apparatus according to the first to fifth aspects of the present invention is provided by disposing a heat insulating material between the stirring member and the exhaust gas duct. In addition to having an effect, the heat insulating material suppresses the temperature drop of the stirring member due to heat radiation to the exhaust gas duct, and can more reliably prevent sticking of a reducing agent or the like to the stirring member and precipitation of by-products.

  According to the exhaust gas purification apparatus of the seventh invention, the stirring member is coated with a hydrolysis catalyst, so that the same operational effects as the exhaust gas purification apparatus of the first to sixth inventions are achieved. In addition, when the reducing agent is urea water, the generation reaction for generating ammonia from the urea water is promoted, and the ammonia can be stably supplied to the reduction catalyst, and the denitration reaction at the reduction catalyst can be promoted.

  According to the exhaust gas purifying apparatus according to the eighth aspect of the present invention, the plurality of stirring members are arranged in the exhaust gas circulation direction, thereby providing the same effects as the exhaust gas purifying apparatus according to the first to seventh aspects of the invention. The exhaust gas can be swirled reliably, and the pressure loss due to swirling can be reduced. Furthermore, since a larger turning force can be applied in the exhaust gas circulation direction without pressure loss than the turning of the exhaust gas by one stirring member, the exhaust gas duct length can be further shortened.

  According to the exhaust gas purification apparatus according to the ninth aspect of the invention, the stirring member has a rotation support means that rotatably supports the exhaust gas duct, so that the exhaust gas purification apparatus according to the first to eighth aspects of the invention can be achieved. In addition to having the same effect, the swirling blades of the stirring member rotate by the inflow of exhaust gas, and the stirring member itself imparts a turning force to the exhaust gas, and the swirling of the exhaust gas can be further increased by rotating the stirring member. . Therefore, in addition to promoting evaporation of the reducing agent added to the exhaust gas, the reducing agent can be uniformly diffused in the exhaust gas, and the denitration performance by the reduction catalyst can be improved.

  According to the exhaust gas purification apparatus of the tenth aspect of the invention, the reducing agent addition means adds the reducing agent to the vicinity of the wall surface of the exhaust gas duct, and the stirring member is the exhaust gas flow direction of the exhaust gas duct. In addition to having the same effect as the exhaust gas purifying apparatus according to the first to ninth inventions, the reducing agent added to the exhaust gas can be used with respect to the exhaust gas flow direction. It can be diffused uniformly in the cross section, and denitration with a reduction catalyst can be performed efficiently. That is, even if the engine load fluctuates or the flow rate of the exhaust gas fluctuates, the reducing agent added from the reducing agent addition means is used as it is by using the flow of the exhaust gas flowing along the peripheral wall of the exhaust gas duct. It can be guided and passed through the stirring member, and the reducing agent can be reliably mixed in the exhaust gas and diffused uniformly. Furthermore, since the central portion of the stirring member is open, pressure loss can be reduced, and the fuel efficiency of the engine can be improved and the fan power in the waste incinerator or waste melting furnace can be reduced.

  An embodiment of an exhaust gas purifying apparatus according to the present invention will be specifically described with reference to the drawings.

[First embodiment]
A first embodiment of an exhaust gas purification apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a schematic configuration diagram of an exhaust gas purification apparatus. FIG. 2 is a schematic view of a swirl vane of the exhaust gas purification apparatus of FIG. FIG. 3 is a view showing the concentration distribution of ammonia on the inlet side of the selective reduction catalyst. FIG. 3 (a) shows a case where no stirring member is installed in the exhaust gas duct, and FIG. 3 (b) shows the inside of the exhaust gas duct. The case where the distance between the installed stirring member and the reduction catalyst is 500 mm is shown, and FIG. 3C shows the case where the distance between the stirring member installed in the exhaust gas duct and the reduction catalyst is 2000 mm. FIG. 4 is a graph showing the standard deviation of the reducing agent mass flow rate according to the arrangement of the stirring members. FIG. 5 is a graph showing the relationship between the exhaust gas flow rate and the standard deviation of the reducing agent mass flow rate. In FIG. 3, the density of the dots indicates the standard deviation of the reducing agent mass flow rate (kg / s).

  The exhaust gas purifying apparatus according to the present embodiment is exhausted from exhaust gas containing nitrogen oxides, exhausted by combustion of fuel in an internal combustion engine such as a diesel engine, gasoline engine, or gas engine, a waste incinerator, a waste melting furnace, or the like. It is used for purification treatment of exhaust gas containing nitrogen oxide.

  As shown in FIG. 1, the exhaust gas purifying apparatus 10 described above includes an exhaust gas duct 11 through which the exhaust gas 1 circulates, and a urea spray nozzle (reducing agent adding means) 13 that sprays urea water 12 as a reducing agent into the exhaust gas duct 11. And a selective reduction catalyst that purifies the exhaust gas by reducing nitrogen oxides in the exhaust gas 1 to nitrogen with ammonia formed by the urea water 12 reacting with the water in the exhaust gas 1 and disposed in the exhaust gas duct 11 (hereinafter, (Referred to as SCR catalyst) 14. The exhaust gas duct 11 has cylindrical small-diameter portions 11a and 11b on the introduction side of the exhaust gas 1 and the exhaust side of the exhaust gas 2, and the exhaust gas duct has a larger diameter than the small-diameter portions 11a and 11b between the small-diameter portions 11a and 11b. A rectangular large-diameter portion 11c is formed in a cross section with respect to the flow direction, and the small-diameter portions 11a and 11b and the large-diameter portion 11c are connected by connection portions 11d and 11e. In the exhaust gas duct 11, a urea spray nozzle 13 is disposed in the small diameter portion 11a on the introduction side of the exhaust gas 1, and a plurality of SCR catalysts 14 are disposed in the large diameter portion 11c (two stages and two rows (four) in FIG. 1). Has been. As the SCR catalyst 14, a honeycomb-shaped catalyst can be used.

  In the exhaust gas duct 11 described above, a stirring member 15 is disposed between the urea spray nozzle 13 and the SCR catalyst 14. Therefore, in the exhaust gas duct 11 described above, the urea spray nozzle 13, the stirring member 15, and the SCR catalyst 14 are arranged in this order from the upstream side in the exhaust gas circulation direction. For example, as shown in FIG. 2, the swivel member 15 may be one in which a plurality of swirl blades 17 are attached to the peripheral surface 16 a of the shaft body 16. However, the swirl vanes 17 are arranged so as to be inclined at a predetermined angle θ with respect to the exhaust gas circulation direction. A swirl flow is imparted to the exhaust gas 1 by the stirring member 15.

  In the exhaust gas purification apparatus 10 described above, the urea water 12 sprayed from the urea spray nozzle 13 is vaporized and reacts with the water in the exhaust gas 1 to become ammonia, and the ammonia is stirred by the stirring member 15 and the exhaust gas flow direction of the SCR catalyst 14. At the upstream end surface 14a, the angle θ of the swirl blade 17, the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11, the stirring member 15 so that the rotational rotation is one rotation in a cross section perpendicular to the exhaust gas flow direction. A distance L1 between the SCR catalyst 14 and the SCR catalyst 14 is set. That is, the swirl vane 17 is adjusted to an angle in the range of 30 ° to 60 ° with respect to the exhaust gas flow direction. When the angle θ of the swirl vane 17 is larger than 60 °, the pressure loss increases. Conversely, when the angle θ is smaller than 30 °, the urea water 12 added to the exhaust gas 1 does not evaporate sufficiently, and the exhaust water 12 enters the exhaust gas. It does not diffuse uniformly and the exhaust duct length must be increased. The distance L1 between the stirring member 15 and the SCR catalyst 14 is adjusted to a range of 1.8 or more and 6.3 or less as a ratio (L1 / D) to the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11. If this ratio L1 / D1 is larger than 6.3, the urea water 12 added to the exhaust gas 1 is sufficiently evaporated and uniformly diffused in the exhaust gas, but the exhaust gas duct 11 becomes too long. On the other hand, if the ratio L1 / D1 is less than 1.8, the urea water 12 added to the exhaust gas 1 does not sufficiently evaporate and does not diffuse uniformly into the exhaust gas. Specifically, when the angle of the swirl vane 17 is 30 °, the distance L1 between the stirring member 15 and the SCR catalyst 14 is 6 as a ratio (L1 / D1) to the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11. .3. When the angle of the swirl vane 17 is 60 °, the distance L1 between the stirring member 15 and the SCR catalyst 14 is set to 1.8 as a ratio (L1 / D1) to the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11. The

  Here, the results of evaluating the diffusion of ammonia formed by the urea water 12 added to the exhaust gas when the distance L1 between the stirring member 15 and the SCR catalyst 14 is adjusted and reacting with the water in the exhaust gas are evaluated. 3 shows. However, the case where the urea water 12 is added to the exhaust gas 1 when the diameter D1 of the small diameter part 11a of the exhaust gas duct 11 is 450 mm is shown. In addition, the diameter D2 of the large diameter part 11c is 1200 mm, and the connection part 11d on the introduction side of the exhaust gas 1 extends and extends at 35 ° from the extending direction of the small diameter part 11a.

  As shown in FIG. 3A, in the exhaust gas duct 11, when the stirring member 15 is not disposed between the urea spray nozzle 13 and the SCR catalyst 14, the end surface 14 a on the upstream side in the exhaust gas circulation direction of the SCR catalyst 14. It can be seen that the concentration distribution of ammonia is shifted to a part of the upper right in the figure. As shown in FIG. 3 (b), in the exhaust gas duct 11, when the distance L1 between the stirring member 15 and the SCR catalyst 14 is 500 mm, ammonia is present at the end surface 14a upstream of the SCR catalyst 14 in the exhaust gas flow direction. In the figure, it can be seen that the density distribution has a circular arc from the center to the lower left side and is offset by a quarter rotation. As shown in FIG. 3 (c), in the exhaust gas duct 11, when the distance L1 between the stirring member 15 and the SCR catalyst 14 is 2000 mm, ammonia is present at the end surface 14a upstream of the SCR catalyst 14 in the exhaust gas flow direction. It can be seen that the density distribution is almost uniform after one rotation at the center in the figure. Therefore, when the distance L1 between the stirring member 15 and the SCR catalyst 14 is 4.4 as a ratio (L1 / D) with respect to the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11, the ammonia swirls one or more turns by the stirring member 15. It was found that the SCR catalyst 14 was in contact with the SCR catalyst.

  Here, the result of evaluating the relationship between the arrangement of the stirring member 15 in the exhaust gas duct 11 and the diffusion of ammonia formed by the evaporation reaction of the urea water 12 added to the exhaust gas is shown in FIG. However, the case where the urea water 12 is added to the exhaust gas 1 when the diameter D1 of the small diameter part 11a of the exhaust gas duct 11 is 450 mm is shown. In addition, the diameter D2 of the large diameter part 11c is 1200 mm, and the connection part 11d on the introduction side of the exhaust gas 1 extends and extends at 35 ° from the extending direction of the small diameter part 11a.

  As shown in FIG. 4, when the distance L1 between the stirring member 15 and the SCR catalyst 14 is 0.5 m and the distance L2 between the stirring member 15 and the urea spray nozzle 13 is 3.0 m, The standard deviation of the reducing agent mass flow rate is about 2.3E-06 at the upstream end surface 14a in the exhaust gas flow direction, the distance L1 between the stirring member 15 and the SCR catalyst 14 is 2.0 m, and the stirring member 15 and the urea spray nozzle When the distance L2 with respect to 13 is 1.5 m, it has been found that the standard deviation of the reducing agent mass flow rate is 1.0E-06 at the end face 14a upstream of the SCR catalyst 14 in the exhaust gas flow direction. That is, even if the distance (L1 + L2) between the urea spray nozzle 13 and the SCR catalyst 14 is the same, the urea spray nozzle in the exhaust gas duct 11 in the region where the urea water 12 sprayed from the urea spray nozzle 13 has evaporated. It was found that the reducing member (ammonia) can diffuse more uniformly in the exhaust gas when the stirring member 15 is disposed in the vicinity of 13.

  Here, the relationship between the exhaust gas flow rate and the standard deviation of the reducing agent mass flow rate will be described with reference to FIG. The conditions shown in Table 1 below were set as mode 1, mode 2, mode 3, and mode 4 in FIG.

As shown in FIG. 5 and Table 1, even if the exhaust gas flow rate changes in the range of about 6600 Nm ³ / h to about 1900 Nm ³ / h, the reducing agent mass flow rate at the end face 14 a upstream of the SCR catalyst 14 in the exhaust gas flow direction. The standard deviation is about 3.0E-04 or less, and it was found that the reducing agent can be uniformly diffused into the exhaust gas without depending on the exhaust gas flow rate.

  Therefore, in the exhaust gas purification device 10, the urea water 12 sprayed on the exhaust gas 1 evaporates due to the heat of the exhaust gas 1 and reacts with the water in the exhaust gas 1 to become ammonia, and the ammonia is discharged into the exhaust gas duct 11 by the stirring member 15. It turns in the radial direction and diffuses almost uniformly in the radial cross section of the exhaust gas duct. Then, the exhaust gas containing uniformly diffused ammonia comes into contact with the SCR catalyst 14 to reduce and purify the nitrogen oxides in the exhaust gas, and the exhaust gas 2 from which the nitrogen oxides have been removed is discharged from the small diameter portion 11 b of the exhaust gas duct 11. Discharged.

  Therefore, according to the exhaust gas purification apparatus 10 according to the present embodiment, the agitating member 15 has a swirl blade having an inclination of 30 ° or more and 60 ° or less with respect to the flow direction so that the exhaust gas 1 is swung along the flow direction. 17 and the distance L1 between the stirring member 15 and the SCR catalyst 14 is 1.8 or more and 6.3 or less in a ratio (L1 / D1) to the diameter D1 of the small diameter portion 11a of the exhaust gas duct 11, so that the urea spray nozzle The urea water 12 sprayed from 13 completely evaporates, reacts with the water in the exhaust gas to become ammonia, and the ammonia is uniformly diffused into the exhaust gas by the stirring member 15. And ammonia will contact uniformly in the cross section 14a with respect to the exhaust gas distribution direction of the SCR catalyst 14, and the SCR catalyst 14 can effectively utilize ammonia to reduce and remove nitrogen oxides in the exhaust gas. Thus, the denitration performance can be improved with a simple configuration of adjusting the distance L1 between the stirring member 15 and the SCR catalyst 14 with respect to the angle of the swirl vane 17 and the diameter D1 of the small diameter portion of the exhaust gas duct 11. Further, since the exhaust gas duct length can be optimized, the exhaust gas purification unit 10 itself can be made compact.

  Further, as described above, the urea water 12 completely evaporates in front of the SCR catalyst 14 to become a gas, and is sufficiently mixed and uniformly diffused in the cross section of the exhaust gas duct 11. Leak ammonia due to passing through the catalyst 14 can be suppressed. Even if there is a distribution of droplets of urea water 12 after spraying without adjusting the spraying pressure or the like of the urea spray nozzle 13 (even when the engine has a load fluctuation such as unsteady operation), the exhaust gas Mixing and diffusing sufficiently in the cross section of the flow path of the duct 11 can suppress leakage ammonia due to excessive supply of urea water 12 and passing through the SCR catalyst 14. The mixing member 15 can sufficiently mix and diffuse with low pressure loss, and the fuel efficiency of the engine is improved.

[Second Embodiment]
A second embodiment of the exhaust gas purifying apparatus according to the present invention will be described with reference to FIG.
FIG. 6 is a schematic diagram of the stirring member of the exhaust gas purifying apparatus.

  The exhaust gas purifying apparatus according to the present embodiment is obtained by applying an evaporation member that promotes evaporation of droplets of urea water 12 in place of the stirring member 15 in the exhaust gas purifying apparatus 10 according to the first embodiment described above. Other than that, it has the same equipment.

  The exhaust gas purifying apparatus according to the present embodiment includes an evaporation member (agitating member) that promotes evaporation of urea water droplets injected from the urea spray nozzle, and non-evaporated urea droplets collide with the evaporation member. Are arranged as follows. For example, as shown in FIG. 6, the evaporation member 25 has a plurality of swirling blades 27 attached to the peripheral surface 16 a of the shaft body 16, and each swirling blade 27 has a plurality of holes 27 a. . By providing the plurality of holes 27a in the swirl vanes 27 of the evaporation member 25 in this way, the contact area with the exhaust gas is widened, and the heat of the exhaust gas is more efficiently transmitted to the droplets of urea water to promote evaporation. Can do. Therefore, the length of the exhaust gas duct required for droplet evaporation can be shortened, and the apparatus can be further downsized. Specifically, the evaporation member 25 can be arranged such that the distance L2 between the urea spray nozzle and the evaporation member 25 is less than 7 in a ratio (L1 / D1) to the diameter D1 of the exhaust gas duct 11.

  Therefore, according to the exhaust gas purifying apparatus according to the present embodiment, the same effects as in the first embodiment described above can be obtained, and the urea droplets are evaporated and gasified on the evaporation member 25. The required exhaust gas duct length (distance L2 between the urea spray nozzle and the evaporation member 25) can be shortened, and the apparatus can be further downsized.

  In addition, although this embodiment demonstrated using the evaporation member 25 which comprises the turning blade 27 in which the hole 27a was formed in multiple numbers, it replaced with such an evaporation member 25, for example, and several protrusion part was provided. It is also possible to apply an evaporation member having swirl vanes. Even such an evaporating member has the same effect as the evaporating member 25 described above.

[Third embodiment]
A third embodiment of the exhaust gas purifying apparatus according to the present invention will be described with reference to FIG.
FIG. 7 is a schematic configuration diagram of the exhaust gas purification device, in which (a) is a side view thereof, and (b) is a cross-sectional view taken along the line VII-VII in (a).

The exhaust gas purifying apparatus according to the present embodiment is obtained by changing the support structure of the stirring member of the exhaust gas purifying apparatus according to the first embodiment described above, and has the same configuration except that.
In the exhaust gas purification apparatus according to the present embodiment, the same components as those in the exhaust gas purification apparatus according to the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, in the exhaust gas purifying apparatus 30 according to the present embodiment, the stirring member 35 is attached to the inside of the small diameter portion 11 a of the exhaust gas duct 11 by the first and second support members 31 and 32. That is, the agitating member 35 has a shaft body 36 and a plurality of swirl blades 37 whose proximal ends are attached to the peripheral surface of the shaft body 36. A cylindrical first support member 31 is attached to the tip end side of the swirl vane 37. The first support member 31 is attached to the small diameter portion 11 a of the exhaust gas duct 11 by the second support member 32. Therefore, the gap S is interposed between the small diameter portion 11 a of the exhaust gas duct 11 and the stirring member 35.

  Therefore, according to the exhaust gas purifying apparatus 30 according to the present embodiment, the same effect as in the first and second embodiments described above can be obtained, and the stirring member 35 is disposed between the small diameter portion 11 a of the exhaust gas duct 11. Since the exhaust gas duct 11 is supported by the exhaust gas duct 11 via the first and second support members 31 and 32 so as to have the gap S, the contact area between the stirring member 35 and the exhaust gas duct 11 can be reduced. The temperature drop of the agitating member 35 due to heat radiation is eliminated, and it is possible to prevent adhesion of precipitates such as urea and cyanuric acid which is a side-reactive product to the agitating member 35.

  In the present embodiment, the exhaust gas purification device 30 in which the stirring member 35 is attached to the exhaust gas duct 11 by the first and second support members 31 and 32 has been described. For example, as shown in FIG. Between the member 35 and the small-diameter portion 11a of the exhaust gas duct 11, a heat insulating material (for example, a tile such as ceramic or glass, wool, or the like) 41 that is a material having low heat conduction can be disposed. Even in the exhaust gas purifying apparatus having such a configuration, a temperature decrease of the stirring member due to heat radiation to the exhaust gas duct is suppressed by the heat insulating material, and sticking of a reducing agent or the like to the stirring member can be prevented.

[Fourth embodiment]
A fourth embodiment of the exhaust gas purifying apparatus according to the present invention will be specifically described.
The exhaust gas purifying apparatus according to the present embodiment is the same as the exhaust gas purifying apparatus according to the first embodiment described above, except that the stirring member is coated with a hydrolysis catalyst, and the other devices are the same.

  The exhaust gas purifying apparatus according to this embodiment is an apparatus including a stirring member coated with a hydrolysis catalyst. Examples of the catalyst include metal oxides such as alumina, titania, silica, zeolite, ceria, magnesia, and calcia, or a mixture thereof. Furthermore, using the metal oxide as a carrier, nickel (Ni), tungsten (W), vanadium (V), iron (Fe), molybdenum (Mo), cobalt (Co), manganese (Mn), copper (Cu), etc. Transition metals, platinum (Pt), palladium (Pd), rhodium (Rh) and other precious metals may be mixed or supported.

  Therefore, according to the exhaust gas purification apparatus according to the present embodiment, in addition to the same effects as the first to third embodiments described above, by applying the catalyst described above to the stirring member, ammonia can be obtained from the urea water. The production reaction to be generated is promoted, and the gasified reducing agent (ammonia) can be stably supplied to the SCR catalyst 14, and the denitration reaction at the SCR catalyst 14 can be promoted.

[Fifth embodiment]
With reference to FIG. 9, it demonstrates concretely about 5th embodiment of the exhaust gas purification apparatus which concerns on this invention.
FIG. 9 is a schematic configuration diagram of the exhaust gas purification apparatus.

The exhaust gas purifying apparatus according to the present embodiment has a configuration in which a plurality of agitation members are arranged in parallel in the exhaust gas flow direction in the first embodiment described above, and the other components are the same.
In the exhaust gas purification apparatus according to the present embodiment, the same components as those in the exhaust gas purification apparatus according to the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the exhaust gas purifying apparatus 50 according to the present embodiment, as shown in FIG. 9, stirring members 55A, 55B, and 55C are arranged in parallel on the small diameter portion 11a of the exhaust gas duct 11. However, the turning angles (inclination angles with respect to the exhaust gas circulation direction) θ1, θ2, and θ3 of the stirring members 55A, 55B, and 55C increase in order from the upstream side in the exhaust gas circulation direction. That is, the turning angle θ1 <the turning angle θ2 <the turning angle θ3. Thereby, turning will be given to exhaust gas gradually and pressure loss can be reduced.

  Therefore, according to the exhaust gas purifying apparatus 50 according to the present embodiment, by arranging the plurality of stirring members 55A, 55B, and 55C, the exhaust gas can be reliably swirled and pressure loss due to swirling can be reduced. Furthermore, since a larger turning force can be applied in the exhaust gas circulation direction without pressure loss than the turning of the exhaust gas by one stirring member, the exhaust gas duct length can be further shortened.

  In the present embodiment, the description has been given using the exhaust gas purifying apparatus 50 in which three stages of stirring members are installed and the turning angle of each stirring member is sequentially increased from the upstream side in the exhaust gas circulation direction. It is also possible to provide an exhaust gas purifying device that is arranged at 4 or more stages. Even such an exhaust gas purifying device has the same effects as the exhaust gas purifying device 50 described above.

  In the present embodiment, the exhaust gas purification device 50 having a plurality of stirring members that swirl the exhaust gas in the same direction has been described. For example, one of the plurality of stirring members is arranged to swirl the exhaust gas to one side. However, other than that, it is also possible to provide an exhaust gas purifying device arranged so as to turn the exhaust gas to the other side. Even such an exhaust gas purifying device has the same effects as the exhaust gas purifying device 50 described above.

[Sixth embodiment]
A sixth embodiment of the exhaust gas purifying apparatus according to the present invention will be specifically described with reference to FIG.
FIG. 10 is a schematic diagram of a stirring member of the exhaust gas purifying apparatus.

The exhaust gas purifying apparatus according to the present embodiment has a configuration in which, in the first embodiment of the exhaust gas purifying apparatus described above, the stirring member is rotatably disposed in the exhaust gas duct, and the other components are the same.
In the exhaust gas purification apparatus according to the present embodiment, the same components as those in the exhaust gas purification apparatus according to the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the exhaust gas purifying apparatus according to the present embodiment, as shown in FIG. 10, the stirring member 65 is rotatably supported by the small diameter portion 11 a of the exhaust gas duct 11. In other words, the stirring member 65 has a shaft body 66 and a plurality of swirl vanes 67 attached to the shaft body 66. The shaft body 66 is rotatably supported by a bearing 68, and the bearing 68 is attached to the small diameter portion 11 a of the exhaust gas duct 11 by a support member 69. Therefore, when the exhaust gas flows into the small diameter portion 11a of the exhaust gas duct 11, the swirl vane 67 rotates, and the exhaust gas is uniformly mixed and diffused in the flow passage cross section of the exhaust gas duct.

  Therefore, according to the exhaust gas purification apparatus according to the present embodiment, in addition to the same effects as the first to fifth embodiments described above, the swirl vanes 67 of the stirring member 65 are rotated by the inflow of exhaust gas, In addition to applying a turning force to the exhaust gas by the swirl vane 67 itself, the swirl vane 67 rotates to further increase the swirl of the exhaust gas. Therefore, in addition to promoting the evaporation of the urea water sprayed on the exhaust gas, ammonia formed by the reaction of the urea water with the water in the exhaust gas can be uniformly diffused in the exhaust gas, and the denitration performance by the SCR catalyst is improved. be able to.

[Seventh embodiment]
A seventh embodiment of the exhaust gas purifying apparatus according to the present invention will be described with reference to FIG.
FIG. 11 is a schematic configuration diagram of the exhaust gas purification apparatus, in which (a) is a side view and (b) is a cross-sectional view taken along line XI-XI in (a).

The exhaust gas purifying apparatus 70 according to the present embodiment is the same as the exhaust gas purifying apparatus according to the first embodiment described above, except that the position of the urea spray nozzle is defined and the shape of the stirring member is changed. It has a configuration.
In the exhaust gas purifying apparatus according to this embodiment, the same components as those in the above-described exhaust gas purifying apparatus according to the first embodiment of the present invention are denoted by the same reference numerals, and description thereof is omitted.

  In the exhaust gas purification apparatus 70 according to the present embodiment, as shown in FIG. 11, a urea spray nozzle 73 is disposed so as to spray the urea water 12 in the vicinity of the wall surface of the small diameter portion 11 a of the exhaust gas duct 11. A stirring member 75 is disposed between the urea spray nozzle 73 and the SCR catalyst 14. However, the stirring member 75 has a cylindrical member 76 and a plurality of swirl vanes 77 each having a proximal end attached to the peripheral surface thereof. The tip end side of the swirl vane 77 is in contact with the wall surface of the small diameter portion 11 a of the exhaust gas duct 11. That is, the stirring member 75 has a hole at a position located in the central portion of the exhaust gas duct 11 in the exhaust gas circulation direction. Therefore, the urea water 12 sprayed from the urea spray nozzle 73 evaporates while flowing from the left side to the right side in the figure in the vicinity of the peripheral surface of the exhaust gas duct 11, and further reacts with the water in the exhaust gas to become ammonia. As a result of passing through the stirring member 75, the exhaust gas duct 11 is uniformly diffused in the radial cross section. As a result, the ammonia-containing exhaust gas comes into uniform contact with the cross section of the SCR catalyst 14 with respect to the exhaust gas flow direction, so that denitration is efficiently performed.

  Therefore, according to the exhaust gas purifying apparatus 70 according to the present embodiment, in addition to the same operational effects as the first to sixth embodiments described above, the urea spray nozzle 73 causes the urea water 12 to be in the vicinity of the wall surface of the exhaust gas duct 11. The stirring member 75 has a hole at a position located in the central portion of the exhaust gas duct 11 in the exhaust gas flow direction, so that the urea water 12 sprayed on the exhaust gas 1 is efficiently evaporated. At the same time, the generated ammonia can be uniformly diffused in a cross section with respect to the exhaust gas flow direction, and denitration with the SCR catalyst 14 can be performed efficiently. Even if the load of the engine fluctuates or the flow rate of the exhaust gas fluctuates, the urea water 12 sprayed from the urea spray nozzle 13 is used as it is by using the flow of the exhaust gas flowing along the peripheral wall of the exhaust gas duct 11. Ammonia that evaporates and reacts with water in the exhaust gas can be guided and passed to the swirl vanes 76 of the stirring member 75, and the ammonia can be reliably mixed and diffused uniformly in the exhaust gas. Further, since the central portion of the stirring member 75 is open, pressure loss can be reduced, and the fuel efficiency of the engine can be improved and the fan power in the waste incinerator or waste melting furnace can be reduced.

It is a schematic block diagram of 1st embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a schematic diagram of the stirring member of 1st embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a figure which shows the density | concentration distribution of ammonia in the inlet_port | entrance side of a selective reduction catalyst. It is a graph which shows the standard deviation of the reducing agent mass flow rate by arrangement | positioning of a stirring member. It is a graph which shows the relationship between the exhaust gas flow rate and the standard deviation of a reducing agent mass flow rate. It is a schematic diagram of the stirring member of 2nd embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a schematic block diagram of 3rd embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a schematic diagram of the stirring member of other examples of 3rd embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a schematic block diagram of 5th embodiment of the exhaust gas purification apparatus which concerns on this invention. It is a schematic diagram of 6th embodiment stirring member of the exhaust gas purification apparatus which concerns on this invention. It is a schematic block diagram of 7th embodiment of the exhaust gas purification apparatus which concerns on this invention.

Explanation of symbols

1, 2, Exhaust gas 10, 30, 50, 70 Exhaust gas purification device 11 Exhaust gas duct 12 Urea water 13, 73 Urea spray nozzle 14 Selective reduction catalyst (SCR catalyst)
15, 35, 55, 65, 75 Stirring member 17, 27, 37, 67, 77 Swivel blade 25 Evaporating member 68 Bearing

Claims (10)

An exhaust gas purification device that reduces and purifies nitrogen oxides in exhaust gas flowing through an exhaust gas duct,
Reducing agent addition means for adding a reducing agent to the exhaust gas duct;
It is arranged in the exhaust gas duct so as to be located downstream of the reducing agent addition position by the reducing agent addition means in the exhaust gas flow direction, and nitrogen oxides in the exhaust gas are reduced to nitrogen by the reducing agent. A reduction catalyst,
A stirring member that is disposed between the reducing agent addition means and the reduction catalyst and imparts a swirling flow to the exhaust gas;
The stirring member includes a swirl blade having an inclination of 30 ° or more and 60 ° or less with respect to the flow direction so as to swirl the exhaust gas along the flow direction;
An exhaust gas purification apparatus, wherein a distance L1 between the stirring member and the reduction catalyst is 1.8 to 6.3 in a ratio to a diameter D1 of the exhaust gas duct. An exhaust gas purification device according to claim 1,
The exhaust gas purification apparatus, wherein the stirring member is an evaporation member that promotes evaporation of the reducing agent. An exhaust gas purification device according to claim 1 or claim 2, wherein
2. The exhaust gas purifying apparatus according to claim 1, wherein the swirl blade has a plurality of holes or protrusions. An exhaust gas purification device according to any one of claims 1 to 3,
The exhaust gas purifying apparatus, wherein a distance L2 between the reducing agent adding means and the stirring member is 7 or less in proportion to the diameter D1 of the exhaust gas duct. An exhaust gas purification apparatus according to any one of claims 1 to 4,
The exhaust gas purifying apparatus, wherein the stirring member is supported by the exhaust gas duct via a support member so as to have a gap between the stirring member and the exhaust gas duct. An exhaust gas purification apparatus according to any one of claims 1 to 5,
An exhaust gas purification apparatus, wherein a heat insulating material is disposed between the stirring member and the exhaust gas duct. It is an exhaust gas purification apparatus as described in any one of Claim 1 thru | or 6, Comprising:
The exhaust gas purifying apparatus according to claim 1, wherein the stirring member is coated with a hydrolysis catalyst. An exhaust gas purifying device according to any one of claims 1 to 7,
An exhaust gas purification apparatus, wherein a plurality of the agitating members are arranged in the exhaust gas circulation direction. An exhaust gas purifying device according to any one of claims 1 to 8,
The exhaust gas purifying apparatus according to claim 1, wherein the agitating member includes a rotation support unit that rotatably supports the exhaust gas duct. An exhaust gas purification apparatus according to any one of claims 1 to 9,
The reducing agent adding means is for adding the reducing agent to the vicinity of the wall surface of the exhaust gas duct,
The exhaust gas purifying apparatus according to claim 1, wherein the stirring member has a hole at a position located in a central portion of the exhaust gas duct in the exhaust gas circulation direction.

Images