WO2023138506A1 - 选择性氧化还原scr系统和发动机 - Google Patents

选择性氧化还原scr系统和发动机 Download PDF

Info

Publication number
WO2023138506A1
WO2023138506A1 PCT/CN2023/072094 CN2023072094W WO2023138506A1 WO 2023138506 A1 WO2023138506 A1 WO 2023138506A1 CN 2023072094 W CN2023072094 W CN 2023072094W WO 2023138506 A1 WO2023138506 A1 WO 2023138506A1
Authority
WO
WIPO (PCT)
Prior art keywords
holes
baffle
scr system
air
air holes
Prior art date
Application number
PCT/CN2023/072094
Other languages
English (en)
French (fr)
Inventor
薛裕丹
李健巍
石代龙
鞠敏
刘强
Original Assignee
潍柴动力股份有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 潍柴动力股份有限公司 filed Critical 潍柴动力股份有限公司
Publication of WO2023138506A1 publication Critical patent/WO2023138506A1/zh

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
    • F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
    • F01N3/2066—Selective catalytic reduction [SCR]
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
    • F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
    • F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
    • F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
    • F01N3/28—Construction of catalytic reactors
    • F01N3/2892—Exhaust flow directors or the like, e.g. upstream of catalytic device
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2610/00—Adding substances to exhaust gases
    • F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present application belongs to the technical field of engines, for example, it relates to a selective redox SCR system.
  • the present application also relates to an engine.
  • SCR Selective catalytic reduction
  • the present application proposes a selective redox SCR system and an engine capable of dealing with the situation in the related art that the SCR conversion efficiency is reduced due to uneven distribution of NH 3 entering the carrier in the SCR system.
  • the first aspect of the present application proposes a selective redox SCR system, including a box, a mixer, a baffle and a carrier.
  • the mixer, the baffle and the carrier are sequentially arranged inside the box along the air flow direction inside the box, and the baffle is provided with a plurality of through holes. At least one parameter among the distribution density of the through holes and the hole area of the through holes is negatively correlated with the uniform distribution index of NH at the baffle .
  • a baffle is set between the mixer and the carrier, and at least one parameter among the density of the through holes on the baffle and the hole area of the through holes is adjusted according to the uniformity of NH3 in front of the carrier, so that NH3 and exhaust gas are mixed twice, thereby improving the uniformity of NH3 distribution and the uniformity of gas velocity, thereby improving the SCR conversion efficiency.
  • This application can be applied to the aftertreatment of all structures, and the opening density of the baffle is adjusted according to the uniformity of NH3 distribution in front of the carrier, so as to achieve a perfect match with aftertreatment of different structures and engines of different displacements, and the SCR system has no complicated connection and installation structure, and has high reliability.
  • the distribution uniformity index is according to the formula Obtain, wherein, m "ii is the NH on each unit grid on the selected plane The mass fraction value, m " mean is the NH on the selected plane The average value of the mass fraction, Ai is the area of each unit grid on the selected plane , and A is the area of the selected plane.
  • the through hole is not provided at a position of the baffle where the distribution uniformity index is greater than a preset threshold.
  • the distribution density of the through holes is also negatively correlated with the gas flow velocity at the baffle.
  • the plurality of through holes include a plurality of first air holes and a plurality of second air holes, the first air holes are arranged along the circumferential periphery of the area where the plurality of second air holes are located, and the hole area of the first air holes is smaller than the hole area of the second air holes.
  • the second air hole is fan-shaped, and the plurality of through holes further include a third air hole, the third air hole is disposed at the center of the baffle plate, and a plurality of the second air holes are arranged along the circumferential direction of the third air hole.
  • the first air hole is circular.
  • the third air hole is circular.
  • the baffle is arranged perpendicular to the axial direction of the box.
  • the second aspect of the present application provides an engine, including the selective redox SCR system provided in the first aspect of the present application.
  • Fig. 1 schematically shows a schematic structural diagram of an SCR system according to an embodiment of the present application
  • Fig. 2 schematically shows a schematic structural diagram of a baffle according to an embodiment of the present application
  • Fig. 3 schematically shows a simulation diagram of a baffle in CFD software according to an embodiment of the present application.
  • first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, an element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
  • spatial relative terms may be used herein to describe the relationship of one element or feature as shown in the figures relative to another element or feature, such as “inside”, “outside”, “inside”, “side”, “below”, “below”, “above”, “above” and the like.
  • Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” or “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below.
  • the device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
  • the first aspect of the present application proposes an SCR system, which includes a box 10, a mixer 11, a baffle 12 and a carrier 13.
  • the mixer 11, the baffle 12 and the carrier 13 are sequentially arranged inside the box 10 along the flow direction of the air flow inside the box 10.
  • a plurality of through holes are provided on the baffle 12. The distribution density of the through holes and/or the hole area of the through holes are negatively correlated with the uniform distribution index of NH at the baffle 12 .
  • the basic principle of SCR technology is to inject fuel or add other reducing agents to the exhaust, select a suitable catalyst, promote the reaction between the reducing agent and NOx , and at the same time inhibit the oxidation of the reducing agent by the oxygen in the exhaust.
  • the existing SCR technology can be divided into urea
  • urea SCR technology There are two types of urea SCR technology in which NH 3 produced by decomposing is used as reducing agent and hydrocarbon SCR technology using hydrocarbon as reducing agent.
  • the hydrocarbon SCR technology is still under further research, and there are not many practical applications; while the urea SCR technology is relatively mature, and there are many practical applications.
  • the urea generates ammonia before the actual SCR reaction starts.
  • urea aqueous solution is sprayed into the exhaust pipe through the nozzle in the form of tiny droplets, and the water evaporates in the high-temperature exhaust gas to produce granular urea CO(NH 2 ) 2 .
  • the temperature is as high as 180°C
  • the pyrolysis reaction of urea produces isocyanic acid (HNCO) and a part of NH 3 .
  • isocyanic acid HNCO
  • Subsequent hydrolysis of isocyanic acid produced by pyrolysis produces part of NH 3 and CO 2 .
  • NH 3 -SCR utilizes NH 3 produced by the decomposition of urea in exhaust gas to selectively catalyze NO x .
  • the box body 10 can be in the shape of a cylinder or a square barrel. One end of the box body 10 is opened to introduce engine exhaust gas.
  • the mixer 11 is provided with a urea nozzle and an airflow guide structure. 3
  • the density of through holes is low or even no holes are opened at the position with high uniformity.
  • NH 3 The position with low uniformity has a higher through-hole density or a larger hole area. Setting more or larger through-holes can increase the flow rate of the mixed gas at this location, thereby strengthening the mixing of NH3 and exhaust gas, and increasing the NH 3
  • the uniformity of mixing so that the NH of the mixed gas entering the carrier 13 3 The distribution is uniform, thereby improving the reaction effect between the catalyst in the carrier 13 and the mixed gas, thereby improving the conversion efficiency.
  • the distribution uniformity index of NH3 can be simulated by Computational Fluid Dynamics (CFD) software to the SCR system.
  • CFD Computational Fluid Dynamics
  • modeling is carried out according to the structure of the actual SCR system, and the boundary conditions and fluid information are input into the CFD software. The higher the mole fraction of , the darker the color, and then the uniform distribution index of NH 3 is obtained.
  • the SCR system proposed in this application sets a baffle 12 between the mixer 11 and the carrier 13, and adjusts the density of through holes on the baffle 12 according to the uniformity of NH3 in front of the carrier 13, so that the NH3 and the exhaust gas are mixed twice, thereby improving the uniformity of NH3 distribution and the uniformity of gas velocity, thereby improving the SCR conversion efficiency.
  • This application can be applied to the aftertreatment of all structures, and the opening density of the baffle 12 is adjusted according to the uniformity of NH3 distribution in front of the carrier 13, so as to achieve a perfect match with different structures of aftertreatment and different displacement engines, and the SCR system has no complicated connection and installation structure, and has high reliability.
  • the distribution uniformity index is according to the formula Obtain, wherein, m " i is the NH on each unit grid on the selected plane
  • the mass fraction value, m " mean is the NH on the selected plane
  • the average value of the mass fraction, Ai is the area of each unit grid on the selected plane
  • A is the area of the selected plane.
  • the above plane may be taken as a certain radial section of the box body 10 located between the mixer 11 and the carrier 13, and the radial section is input into the CFD software, and the CFD software calculates and analyzes the SCR system model to obtain the value of U vapor .
  • the calculation method of the above-mentioned uniform distribution index is obtained by computer software, which has high calculation accuracy and fast speed, and can avoid calculation errors.
  • the gas velocity distribution uniformity at the baffle 12 is according to the formula get, among them.
  • ⁇ i is the gas velocity value on each unit grid on the plane taken
  • ⁇ mean is the average value of gas velocity on the plane taken.
  • CFD software is also calculated.
  • the distribution density of the through holes is also negatively correlated with the gas flow velocity at the baffle 12 .
  • passing through the baffle plate 12 can weaken the flow velocity of the mixed gas, so that the uniformity of the flow velocity of the mixed gas on the entire plane is better, so that the airflow in some places is fast and the airflow in some places is very slow.
  • the above setting also makes the distribution uniformity of NH 3 better, thereby improving the conversion efficiency of the SCR system.
  • the plurality of through holes includes a plurality of first air holes 121 and a plurality of second air holes 122, the first air holes 121 are arranged along the circumferential periphery of the area where the plurality of second air holes 122 are located, and the hole area of the first air holes 121 is smaller than the hole area of the second air holes 122.
  • the first air holes 121 may be circular, polygonal, etc.
  • the second air holes 122 may be arc-shaped, fan-shaped, etc., which are not limited herein.
  • the distribution uniformity of NH 3 at the position near the center of the baffle 12 is worse than that at the edge of the baffle 12, so it is necessary to set a denser or larger NH near the center of the baffle 12.
  • the cross-sectional area of the through hole, that is, the second air hole 122, is used to increase the gas flow velocity there, strengthen the mixing of NH 3 and exhaust gas, and improve the uniformity of NH 3 distribution.
  • the second air holes 122 are fan-shaped, and the plurality of through holes further include a third air hole 123 , the third air hole 123 is arranged at the center of the baffle 12 , and a plurality of second air holes 122 are arranged along the circumference of the third air hole 123 .
  • Four fan-shaped second air holes 122 can be arranged along the outer circumference of the third air hole 123 to form a circle. According to the CFD software simulation, the distribution uniformity of NH3 at the center of the baffle plate 12 is higher than the uniformity of NH3 distribution at a position slightly outside the center of the baffle plate 12.
  • the third air hole 123 can be set in a form with a smaller hole area than the second air hole 122, so that the gas flow rate at the position where the NH3 distribution uniformity is poor on the baffle plate 12 is increased, thereby improving the distribution uniformity of NH3 and the conversion efficiency of the SCR.
  • no through holes are provided at positions where the distribution uniformity index of the baffle plate 12 is greater than a preset threshold.
  • a preset threshold can be set according to the actual situation and the calculation results of the CFD software, and no holes are opened at the position where the distribution uniformity index of the baffle plate 12 is higher, so as not to further weaken the NH 3 distribution uniformity of the baffle plate 12 .
  • the first air hole 121 is circular, and the third air hole 123 is circular.
  • the circular air hole is convenient for processing and has a good gas circulation effect.
  • the baffle plate 12 is arranged vertically to the axial direction of the box body 10, so that the baffle plate 12 is convenient to install and the flow direction of the front airflow of the baffle plate 12 is conducive to adjusting the airflow.
  • the outer edge of the baffle plate 12 can be fixed on the inner side wall of the box body 10 by welding or bolting.
  • the second aspect of the present application provides an engine, including the SCR system provided in the first aspect of the present application.
  • the engine proposed in the second aspect of the present application has the same beneficial effects as the SCR system proposed in the first aspect of the present application, and will not be repeated here.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Exhaust Gas After Treatment (AREA)

Abstract

一种选择性氧化还原SCR系统，包括箱体（10）、混合器（11）、挡板（12）和载体（13），混合器（11）、挡板（12）和载体（13）沿箱体内部的气流流动方向依次设置在箱体（10）的内部，挡板（12）上设有多个通孔，通孔的分布密度和通孔的孔面积中的至少一种参数与挡板处的NH 3的分布均匀指数呈负相关。还涉及一种发动机，发动机包括SCR系统。在实际应用中，通孔的分布密度和孔面积的设置能够提高氨气的混合均匀性，进而提高载体内催化剂与混合气的反应效果。

Description

选择性氧化还原SCR系统和发动机
本申请要求2022年01月18日提交中国专利局、申请号为202210055994.1、发明名称为“SCR系统和发动机”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请属于发动机技术领域，例如涉及一种选择性氧化还原SCR系统。本申请还涉及一种发动机。
背景技术
现有的选择性氧化还原(Selective catalytic reduction，SCR)系统一般都配置有混合器，混合器将尿素与废气混合，混合后的混合气中的NH3分布通常是不均匀的，混合气进入载体后会与载体内的催化剂进行反应生成清洁物质，NH3分布不均会影响其与催化剂的反应效果，进而导致SCR转化效率降低。
发明内容
本申请提出一种选择性氧化还原SCR系统和发动机，能够处理相关技术中SCR系统的进入载体的NH3分布不均导致SCR转化效率降低的情况。
本申请的第一方面提出了一种选择性氧化还原SCR系统，包括箱体、混合器、挡板和载体，所述混合器、所述挡板和所述载体沿所述箱体内部的气流流动方向依次设置在所述箱体的内部，所述挡板上设有多个通孔，所述通孔的分布密度和所述通孔的孔面积中的至少一种参数与所述挡板处的NH3的分布均匀指数呈负相关。
本申请提出的选择性氧化还原SCR系统在混合器与载体之间设置挡板，根据载体前的NH3均匀性调整挡板上通孔的密度和所述通孔的孔面积中的至少一种参数，使NH3与废气二次混合，从而提升NH3分布的均匀性和气体速度均匀性，进而提升SCR转化效率。本申请可应用于所有结构的后处理，根据载体前NH3分布均匀性调整挡板的开孔密度，实现与不同结构后处理、不同排量发动机的完美匹配，并且该SCR系统无复杂连接安装结构，可靠性高。
在本申请的一些实施例中，所述分布均匀指数根据公式 获得，其中，m″ii为所取平面上各单元网格上的NH3质量分数值，m″mean为所取平面上NH3质量分数平均值，Ai为所取平面上各单元网格的面积，A为所取平面的面积。
在本申请的一些实施例中，所述挡板的所述分布均匀指数大于预设阈值的位置不设置所述通孔。
在本申请的一些实施例中，所述通孔的分布密度还与所述挡板处的气体流动速度呈负相关。
在本申请的一些实施例中，所述多个通孔包括多个第一气孔和多个第二气孔，所述第一气孔沿所述多个第二气孔所在区域的周向外围布置，所述第一气孔的孔面积小于所述第二气孔的孔面积。
在本申请的一些实施例中，所述第二气孔呈扇形，所述多个通孔还包括第三气孔，所述第三气孔设置在所述挡板的中心处，沿所述第三气孔的周向设置有多个所述第二气孔。
在本申请的一些实施例中，所述第一气孔呈圆形。
在本申请的一些实施例中，所述第三气孔呈圆形。
在本申请的一些实施例中，所述挡板与所述箱体的轴向方向垂直设置。
本申请的第二方面提出了一种发动机，包括本申请第一方面提出的选择性氧化还原SCR系统。
附图说明
图1示意性地示出了根据本申请实施方式的SCR系统的结构示意图；
图2示意性地示出了根据本申请实施方式的挡板的结构示意图；
图3示意性地示出了根据本申请实施方式的挡板在CFD软件中的模拟示意图。
具体实施方式
应理解的是，文中使用的术语仅出于描述特定示例实施方式的目的，而无意于进行限制。除非上下文另外明确地指出，否则如文中使用的单数形式“一”、“一个”以及“所述”也可以表示包括复数形式。术语“包括”、“包 含”、“含有”以及“具有”是包含性的，并且因此指明所陈述的特征、步骤、操作、元件和/或部件的存在，但并不排除存在或者添加一个或多个其它特征、步骤、操作、元件、部件、和/或它们的组合。文中描述的方法步骤、过程、以及操作不解释为必须要求它们以所描述或说明的特定顺序执行，除非明确指出执行顺序。还应当理解，可以使用另外或者替代的步骤。
尽管可以在文中使用术语第一、第二、第三等来描述多个元件、部件、区域、层和/或部段，但是，这些元件、部件、区域、层和/或部段不应被这些术语所限制。这些术语可以仅用来将一个元件、部件、区域、层或部段与另一区域、层或部段区分开。除非上下文明确地指出，否则诸如“第一”、“第二”之类的术语以及其它数字术语在文中使用时并不暗示顺序或者次序。因此，以下讨论的元件、部件、区域、层或部段在不脱离示例实施方式的教导的情况下可以被称作第二元件、部件、区域、层或部段。
为了便于描述，可以在文中使用空间相对关系术语来描述如图中示出的一个元件或者特征相对于另一元件或者特征的关系，这些相对关系术语例如为“内部”、“外部”、“内侧”、“侧”、“下面”、“下方”、“上面”、“上方”等。这种空间相对关系术语意于包括除图中描绘的方位之外的在使用或者操作中装置的不同方位。例如，如果在图中的装置翻转，那么描述为“在其它元件或者特征下面”或者“在其它元件或者特征下方”的元件将随后定向为“在其它元件或者特征上面”或者“在其它元件或者特征上方”。因此，示例术语“在……下方”可以包括在上和在下的方位。装置可以另外定向(旋转90度或者在其它方向)并且文中使用的空间相对关系描述符相应地进行解释。
如图1和图2所示，本申请的第一方面提出了一种SCR系统，包括箱体10、混合器11、挡板12和载体13，混合器11、挡板12和载体13沿箱体10内部的气流流动方向依次设置在箱体10的内部，挡板12上设有多个通孔，通孔的分布密度和/或通孔的孔面积与挡板12处的NH3的分布均匀指数呈负相关。
需要说明的是，SCR技术的基本原理是向排气中喷射燃油或者添加其他还原剂，选择合适的催化剂，促进还原剂与NOx反应，同时抑制还原剂被排气中的氧气氧化。现有SCR技术按照还原剂的种类可以分为以尿素分 解产生的NH3作为还原剂的尿素SCR技术和以碳氢作为还原剂的碳氢SCR技术两类。目前碳氢SCR技术仍在进一步的研究当中，实际应用不多；而尿素SCR技术较为成熟，实际应用较多。在实际的SCR反应开始前尿素先生成氨。尿素水溶液以微小液滴形式经喷嘴喷入排气管内，在温度较高的排气中水分蒸发，产生颗粒状的尿素CO(NH2)2。当温度高与180℃时，尿素发生热解反应产生异氰酸(HNCO)和一部分NH3。随后热解产生的异氰酸发生水解反应产生一部分NH3和CO2。NH3-SCR利用尿素在尾气中分解生成的NH3来选择催化NOx。
箱体10可呈圆筒形或方桶型，箱体10的一端开口引入发动机废气，混合器11上设置尿素喷嘴和气流引导结构，尿素喷嘴喷入尿素与废气混合，废气及尿素喷雾经气流引导结构加强混合，提高混合的均匀性，经混合器11混合均匀后的混合气流经挡板12上的通孔，挡板12在NH3均匀性高的位置上通孔密度较低甚至不开孔，在NH3均匀性低的位置通孔密度较高或者通孔的孔面积更大，设置更多或更大的通孔能够使得该处混合气的流速提高，进而加强NH3与废气混合，提高NH3的混合均匀性，使得进入载体13内的混合气的NH3分布均匀，进而提高载体13内的催化剂与混合气的反应效果，从而提高转化效率。
如图3所示，NH3的分布均匀指数可通过计算流体动力学(Computational Fluid Dynamics，CFD)软件对SCR系统进行模拟，在CFD软件中根据实际SCR系统的结构进行建模，将边界条件及流体信息等输入至CFD软件中，CFD软件对SCR系统进行网格划分，然后对气体反应及流动进行模拟，并基于上述网格进行计算，从而得出NH3分布的数据和图(即图3)，图3中区域的NH3的摩尔分数越高颜色越深，进而得出NH3的分布均匀指数。
本申请提出的SCR系统在混合器11与载体13之间设置挡板12，根据载体13前的NH3均匀性调整挡板12上通孔的密度，使NH3与废气二次混合，从而提升NH3分布的均匀性和气体速度均匀性，进而提升SCR转化效率。本申请可应用于所有结构的后处理，根据载体13前NH3分布均匀性调整挡板12的开孔密度，实现与不同结构后处理、不同排量发动机的完美匹配，并且该SCR系统无复杂连接安装结构，可靠性高。
在本申请的一些实施例中，分布均匀指数根据公式获得，其中，m″i为所取平面上各单元网格上的NH3质量分数值，m″mean为所取平面上NH3质量分数平均值，Ai为所取平面上各单元网格的面积，A为所取平面的面积。上述所取平面可取箱体10位于混合器11和载体13之间的部分的某一径向截面，将该径向截面输入至CFD软件中，CFD软件对SCR系统模型进行计算分析，从而得到Uvapor的数值，上述分布均匀指数的计算方法通过计算机软件获得，计算精度高，速度快，能够避免计算带来的误差。
另外，挡板12处的气体速度分布均匀性根据公式获得，其中。ωi为所取平面上各单元网格上的气体速度值，ωmean为所取平面上气体速度的平均值。上述各值也通过CFD软件进行计算获得，挡板12上的通孔根据与NH3分布均匀性成反比的规律布置后，挡板12处的气体速度分布均匀性也得到相应的提高。
在本申请的一些实施例中，通孔的分布密度还与挡板12处的气体流动速度呈负相关。在气体流动速度快的地方，经过挡板12可以减弱混合气的流动速度，使得整个平面上混合气的流动速度的均匀性更好，而不至于有的地方气流很快，有的地方气流很慢。上述设置同样使得NH3的分布均匀性更好，进而提高了SCR系统的转化效率。
在本申请的一些实施例中，多个通孔包括多个第一气孔121和多个第二气孔122，第一气孔121沿多个第二气孔122所在区域的周向外围布置，第一气孔121的孔面积小于第二气孔122的孔面积。第一气孔121可呈圆形、多边形等，第二气孔122可设置为弧形、扇形等，在此不做限定。根据CFD软件计算结果显示，挡板12靠近中心处的位置NH3分布均匀性比挡板12的边缘处更差，因此需要在挡板12靠近中心处设置更密或者更大 截面积的通孔，即第二气孔122，以提高该处的气流速度，加强NH3与废气混合，提高NH3的分布均匀性。
在本申请的一些实施例中，第二气孔122呈扇形，多个通孔还包括第三气孔123，第三气孔123设置在挡板12的中心处，沿第三气孔123的周向设置有多个第二气孔122。扇形的第二气孔122可沿第三气孔123的外周向设置四个，形成圆形。根据CFD软件模拟显示，挡板12中心处的NH3分布均匀性比挡板12中心处稍外位置的NH3分布均匀性更高，因此可将第三气孔123设置成孔面积比第二气孔122更小的形式，使得挡板12上NH3分布均匀性较差的位置的气体流速得到提高，进而提高NH3的分布均匀性和SCR的转化效率。
在本申请的一些实施例中，挡板12的分布均匀指数大于预设阈值的位置不设置通孔。可根据实际情况和CFD软件的计算结果设置一个预设阈值，在挡板12的分布均匀指数较高的位置不开孔，以免进一步削弱挡板12的NH3分布均匀性。
在本申请的一些实施例中，第一气孔121呈圆形，第三气孔123呈圆形，圆形的气孔一是方便加工，二是气体流通效果好。
在本申请的一些实施例中，挡板12与箱体10的轴向方向垂直设置，使得挡板12方便安装并且挡板12正面气流的流向，有利于调整气流，另外，挡板12的外缘可通过焊接或者螺栓连接的形式固定在箱体10的内侧壁上。
本申请的第二方面提出了一种发动机，包括本申请第一方面提出的SCR系统。
本申请第二方面提出的发动机具有和本申请第一方面提出的SCR系统相同的有益效果，在此不再赘述。

Claims (10)

  1. 一种选择性氧化还原SCR系统，包括箱体、混合器、挡板和载体，所述混合器、所述挡板和所述载体沿所述箱体内部的气流流动方向依次设置在所述箱体的内部，所述挡板上设有多个通孔，所述通孔的分布密度和所述通孔的孔面积中的至少一种参数与所述挡板处的NH3的分布均匀指数呈负相关。
  2. 根据权利要求1所述的选择性氧化还原SCR系统，其特征在于，所述分布均匀指数根据公式获得，其中，m″ii为所取平面上各单元网格上的NH3质量分数值，m″mean为所取平面上NH3质量分数平均值，Ai为所取平面上各单元网格的面积，A为所取平面的面积。
  3. 根据权利要求2所述的选择性氧化还原SCR系统，其中，所述挡板的所述分布均匀指数大于预设阈值的位置不设置所述通孔。
  4. 根据权利要求1所述的选择性氧化还原SCR系统，其中，所述通孔的分布密度还与所述挡板处的气体流动速度呈负相关。
  5. 根据权利要求1所述的选择性氧化还原SCR系统，其中，所述多个通孔包括多个第一气孔和多个第二气孔，所述第一气孔沿所述多个第二气孔所在区域的周向外围布置，所述第一气孔的孔面积小于所述第二气孔的孔面积。
  6. 根据权利要求5所述的选择性氧化还原SCR系统，其中，所述第二气孔呈扇形，所述多个通孔还包括第三气孔，所述第三气孔设置在所述挡板的中心处，沿所述第三气孔的周向设置有多个所述第二气孔。
  7. 根据权利要求5所述的选择性氧化还原SCR系统，其中，所述第一气孔呈圆形。
  8. 根据权利要求6所述的选择性氧化还原SCR系统，其中，所述第三气孔呈圆形。
  9. 根据权利要求1至8任一项所述的选择性氧化还原SCR系统，其中，所述挡板与所述箱体的轴向方向垂直设置。
  10. 一种发动机，包括权利要求1至9任一项所述的选择性氧化还原 SCR系统。
PCT/CN2023/072094 2022-01-18 2023-01-13 选择性氧化还原scr系统和发动机 WO2023138506A1 (zh)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202210055994.1A CN114542247B (zh) 2022-01-18 2022-01-18 Scr系统和发动机
CN202210055994.1 2022-01-18

Publications (1)

Publication Number Publication Date
WO2023138506A1 true WO2023138506A1 (zh) 2023-07-27

Family

ID=81672277

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2023/072094 WO2023138506A1 (zh) 2022-01-18 2023-01-13 选择性氧化还原scr系统和发动机

Country Status (2)

Country Link
CN (1) CN114542247B (zh)
WO (1) WO2023138506A1 (zh)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114542247B (zh) * 2022-01-18 2023-04-18 潍柴动力股份有限公司 Scr系统和发动机

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007021422A (ja) * 2005-07-20 2007-02-01 Hino Motors Ltd 選択還元型触媒及びそれを用いたエンジンの排ガス浄化装置
CN106285863A (zh) * 2016-10-18 2017-01-04 南京依柯卡特排放技术股份有限公司 一种柴油车尿素双螺旋双涡旋scr混合器
CN107257709A (zh) * 2015-02-24 2017-10-17 天纳克汽车经营有限公司 双螺旋推运器混合系统
CN109356693A (zh) * 2018-11-13 2019-02-19 浙江银轮机械股份有限公司 一种紧凑式混合器组件
CN109826697A (zh) * 2019-03-26 2019-05-31 平原滤清器有限公司 柴油机排放后处理用旋流装置
CN109915241A (zh) * 2017-12-13 2019-06-21 北汽福田汽车股份有限公司 导流挡板、氧化催化器和车辆
CN114542247A (zh) * 2022-01-18 2022-05-27 潍柴动力股份有限公司 Scr系统和发动机

Family Cites Families (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3651021B2 (ja) * 1994-06-17 2005-05-25 株式会社デンソー 自己発熱型触媒コンバータ
US20040057888A1 (en) * 2002-09-25 2004-03-25 Mitsubishi Power Systmes, Inc. Ammonia distribution grid for selective catalytic reduction (SCR) system
DE102009056183A1 (de) * 2009-11-27 2011-06-01 Emitec Gesellschaft Für Emissionstechnologie Mbh Abgasreinigungskomponente mit Umlenkfläche und Verfahren zu deren Herstellung
CN102094699A (zh) * 2010-12-15 2011-06-15 杭州银轮科技有限公司 一种用于柴油机尿素选择性催化还原装置的静态混合器
CN103867273A (zh) * 2014-04-04 2014-06-18 北京科领动力科技有限公司 一种柴油机scr系统还原剂分布均匀性测量装置及方法
WO2016039720A1 (en) * 2014-09-08 2016-03-17 Cummins, Inc. Exhaust gas mixer device
GB2533331A (en) * 2014-12-16 2016-06-22 Daimler Ag Mixing device for an exhaust gas system
CN205779152U (zh) * 2016-07-04 2016-12-07 天纳克（苏州）排放系统有限公司 尾气后处理装置
CN206144632U (zh) * 2016-09-21 2017-05-03 佛吉亚排气控制技术开发(上海）有限公司 端盖以及包括该端盖的混合器、排气后处理装置和车辆
CN107267169B (zh) * 2017-07-21 2022-08-19 中冶焦耐(大连)工程技术有限公司 一种捣固焦炉机侧装煤烟尘定向控制系统及方法
CN107701270B (zh) * 2017-08-09 2019-10-22 北汽福田汽车股份有限公司 用于车辆的混合器、排气系统和混合器的确定方法
WO2019089041A1 (en) * 2017-11-03 2019-05-09 Faurecia Emissions Control Technologies, Usa, Llc Flow reversing mixer assembly
CN209458001U (zh) * 2018-12-12 2019-10-01 河北亿利橡塑集团有限公司 一种用于发动机尾气后处理系统的混合装置
CN210799103U (zh) * 2019-09-12 2020-06-19 无锡威孚力达催化净化器有限责任公司 喷嘴集成式scr后处理尿素混合装置
CN211819593U (zh) * 2019-11-14 2020-10-30 无锡恒和环保科技有限公司 一种scr排气混合装置
DE102020101226A1 (de) * 2020-01-20 2021-07-22 Friedrich Boysen GmbH & Co KG. Vorrichtung zum Einbringen und Verteilen einer Flüssigkeit in einen Gasstrom
CN213178329U (zh) * 2020-09-11 2021-05-11 洛阳新普石化设备开发有限公司 固废焚烧沼气燃烧器
CN112973400B (zh) * 2021-02-25 2022-06-21 东南大学 一种基于流速与NOx浓度监测的SCR系统喷氨支管控制方法

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007021422A (ja) * 2005-07-20 2007-02-01 Hino Motors Ltd 選択還元型触媒及びそれを用いたエンジンの排ガス浄化装置
CN107257709A (zh) * 2015-02-24 2017-10-17 天纳克汽车经营有限公司 双螺旋推运器混合系统
CN106285863A (zh) * 2016-10-18 2017-01-04 南京依柯卡特排放技术股份有限公司 一种柴油车尿素双螺旋双涡旋scr混合器
CN109915241A (zh) * 2017-12-13 2019-06-21 北汽福田汽车股份有限公司 导流挡板、氧化催化器和车辆
CN109356693A (zh) * 2018-11-13 2019-02-19 浙江银轮机械股份有限公司 一种紧凑式混合器组件
CN109826697A (zh) * 2019-03-26 2019-05-31 平原滤清器有限公司 柴油机排放后处理用旋流装置
CN114542247A (zh) * 2022-01-18 2022-05-27 潍柴动力股份有限公司 Scr系统和发动机

Also Published As

Publication number Publication date
CN114542247B (zh) 2023-04-18
CN114542247A (zh) 2022-05-27

Similar Documents

Publication Publication Date Title
CN106837480B (zh) 一种基于模型的尿素喷射量控制方法及后处理控制系统
CN206016920U (zh) 用于柴油机尾气后处理的尿素喷射混合单元
WO2023138506A1 (zh) 选择性氧化还原scr系统和发动机
CN204877615U (zh) 排气处理装置
CN113586212A (zh) 一种多旋流结构的混合装置
CN205190012U (zh) 筒式scr后处理混合腔
CN104963750A (zh) 一种用于大功率柴油机scr系统的静态混合装置
CN105464764B (zh) 用于排气设施的混合器及scr系统
CN204003038U (zh) 一种scr尾气处理系统的进气管、scr尾气处理系统
CN106311068B (zh) 动态式叶片混合器
CN202012386U (zh) 一种用于柴油机尿素scr系统的混合装置
CN103742238A (zh) 一种尿素scr系统低温加热混合装置
CN103470353B (zh) 一种基于尿素分解效率的柴油机scr系统控制方法
CN204357536U (zh) 一种废气处理系统
CN211819593U (zh) 一种scr排气混合装置
CN104653353A (zh) 一种减少egr冷却器积碳的装置
CN109854345B (zh) 一种scr后处理尿素混合装置
WO2023138342A1 (zh) Scr系统和发动机
CN110953045A (zh) 用于船机排气后处理系统的混合器组件
CN113107650A (zh) 一种用于柴油机urea-SCR系统的动态混合器
Jain et al. A study on the factors affecting the formation of urea crystals and its mitigation for SCR after-treatment systems
CN111764989B (zh) 一种高效后处理封装scr混合器系统及其处理方法
CN105114160B (zh) 催化转化装置及其废气空气混合器
CN204532599U (zh) 一种减少egr冷却器积碳的装置
CN204152606U (zh) 一种三元催化器

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23742821

Country of ref document: EP

Kind code of ref document: A1