CN111677581A - Airflow guiding device for SCR - Google Patents

Airflow guiding device for SCR Download PDF

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Publication number
CN111677581A
CN111677581A CN202010582298.7A CN202010582298A CN111677581A CN 111677581 A CN111677581 A CN 111677581A CN 202010582298 A CN202010582298 A CN 202010582298A CN 111677581 A CN111677581 A CN 111677581A
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CN
China
Prior art keywords
section
flow
scr
gas
mixer
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Pending
Application number
CN202010582298.7A
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Chinese (zh)
Inventor
许越
倪培永
王向丽
喜冠南
王玉
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Nantong University
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Nantong University
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Priority to CN202010582298.7A priority Critical patent/CN111677581A/en
Publication of CN111677581A publication Critical patent/CN111677581A/en
Pending legal-status Critical Current

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    • 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
    • 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]
    • F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
    • 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

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  • 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

The invention discloses an airflow guiding device for SCR, which is characterized in that three airflow guiding devices are respectively designed on a bent pipe section, a straight pipe section and an expansion section: a bending section guide device, a blade type cyclone mixer and an expansion section guide device. The invention can select one or more combined airflow guide devices according to the specific exhaust emission concentration and exhaust back pressure of the diesel engine, and simultaneously improves the purification performance of the SCR system. The bending section guide device can effectively improve the speed uniformity, and has a simple structure and is convenient to manufacture; the vane type cyclone type mixer can reduce the pressure drop caused by arranging a flow guide device at other supplement positions of the SCR system while improving the gas-liquid mixing degree. The expansion section guiding device is used for reducing disturbance of exhaust gas flow and solving the problem that NH near the pipeline wall is caused by the concentration of the gas flow at the middle position of the expansion section3Low concentration and small flow rate, thereby improving the uniformity of gas flow rate and NH in the SCR reactor3Uniformity of concentration.

Description

Airflow guiding device for SCR
Technical Field
The invention belongs to the technical field of flue gas denitration, and particularly relates to an airflow guiding device for SCR.
Background
In recent years, people are gradually turning to environmental pollution control. And NO emitted from marine diesel engine exhaust among air pollution componentsXA certain share is occupied. Thus, it is necessary to control the marine diesel exhaust emission. In order to make NO in the tail gas of marine diesel engineXMeets the strict ship tail gas emission standard at home and abroad, and needs to treat the tail gas generated by ships. Selective Catalytic Reduction (SCR) technology, one of the most promising exhaust gas aftertreatment technologies, has a high NO contentXConversion efficiency, little change to the original machine and the like. Therefore, the method has great significance for the optimization research of the SCR system of the marine diesel engine. Among the factors influencing SCR performance, the degree of mixing of ammonia and tail gas to NO of SCRXConversion and NH3The escape rate is greatly affected. Therefore, it is necessary to design a suitable SCR system airflow directing device.
Disclosure of Invention
The purpose of the invention is as follows: to address the deficiencies of the prior art, the present invention provides an airflow directing device for an SCR.
The technical scheme is as follows: an airflow guiding device for SCR is characterized in that three airflow guiding devices are respectively installed on a bent pipe section, a straight pipe section and an expansion section in an SCR system: the device comprises a bending section flow guide device, a blade type cyclone mixer and an expansion section guide device;
the bent section flow guiding device consists of a plurality of layers of flow guide rings at equal intervals, and can shunt gas to enter the bent section, reduce gas impacting the pipe wall and improve the uniformity of the flow velocity of the gas in the pipeline;
the blade type rotational flow type mixer is placed below the spray of the straight pipe section of the air inlet pipe of the SCR system, the mixer comprises six blades, the blades have certain radian, and the number and the radian of the blades can be adjusted according to the pipe diameter of the straight pipe section and the exhaust flow; a bearing is arranged in a thin shell in the middle of the mixer, and a connecting device is arranged in the bearing and connected with an air inlet pipe. When the airflow passes through the mixer, the airflow drives the blades to rotate, so that the airflow disturbance is effectively carried out, the mixing degree of urea and tail gas is improved, and the purification performance of the SCR system is improved;
the flow guide device of the expansion section adopts a trapezoidal layered design structure and consists of three layers of flow guide rings, the angle of each layer of flow guide ring can be adjusted according to the angle of the expansion angle of the SCR reactor, so that gas flow can be effectively divided, the disturbance of waste gas flow is reduced, the radial nonuniformity of the gas flow is improved, and the problem that the gas flow is concentrated in the middle of the expansion section to cause the NH near the pipeline wall3Low concentration and small flow rate, thereby improving the uniformity of gas flow rate and NH in the SCR reactor3Uniformity of concentration.
As an optimization: in the blade type rotational flow type mixer, the rotation of the blades can effectively reduce the pressure drop caused by the arrangement of the flow guide devices on the bent pipe section and the expansion section, thereby ensuring the economy of the diesel engine.
Has the advantages that: the specific advantages of the invention are as follows:
1. the invention arranges a layered structure on the bend section, which can effectively improve the speed uniformity and has simple structure and convenient manufacture.
2. The invention designs a novel blade type rotational flow type mixer, which has stronger mixing capability compared with the static linear mixer widely used at present.
3. The spiral-flow type mixer provided by the invention can reduce the pressure drop caused by arranging the flow guide device at other compensation positions of the SCR system while improving the gas-liquid mixing degree, and ensures the economy of a diesel engine.
4. The flow guide device of the expansion section can reduce the disturbance of the waste gas flow and solve the problem that the flow is concentrated in the middle of the expansion section to cause NH near the pipeline wall3Low concentration and small flow rate, thereby improving the uniformity of gas flow rate and NH in the SCR reactor3Uniformity of concentration.
5. According to the invention, three airflow guide devices are respectively designed on the bent pipe section, the straight pipe section and the expansion section, one or more combined airflow guide devices can be selected according to the specific tail gas emission condition and the exhaust back pressure of the diesel engine, and the purification performance of the SCR system is improved while the economy of the diesel engine is ensured.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic view of a model of the elbow flow guide apparatus of the present invention;
FIG. 3 is a schematic view of the diverging section flow directing arrangement of the present invention;
FIG. 4 is a schematic view of a swirl-type mixer according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below so that those skilled in the art can better understand the advantages and features of the present invention, and thus the scope of the present invention will be more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention.
Examples
In the actual application of the SCR system, various pipeline forms such as pipeline bending, pipeline expansion and the like are often constructed to adapt to the installation space of the SCR system. Therefore, at these particular pipe locations, fluctuations in the flow of gas can occur.
The gas easily impacts the pipe wall in the bending section, so that the flow velocity distribution of the gas is not uniform. The bent section flow guiding device is composed of a plurality of layers of flow guide rings at equal intervals, and can shunt gas which is about to enter a bent section, reduce gas impacting a pipe wall and improve the uniformity of the flow velocity of the gas in a pipeline.
As shown in figures 1-4, the novel blade-type swirl mixer is placed below the spray of the straight pipe section of the air inlet pipe of an SCR system. The mixer comprises six fan blades, the fan blades have certain radian, and the number and the radian of the fan blades can be adjusted according to the pipe diameter of the straight pipe section and the exhaust flow. A bearing is arranged in a thin shell in the middle of the mixer, and a connecting device is arranged in the bearing and connected with an air inlet pipe. When the air current passes through the mixer, the air current drives the blade rotation, and the effectual air current disturbance that carries on improves the mixing degree of urea and tail gas to improve SCR system's purification performance. The mixer has a higher mixing capacity than the static linear mixer which is widely used at present. Meanwhile, the rotation of the blades also has the effect of an exhaust fan, and the pressure drop caused by the arrangement of the flow guide devices on the bent pipe section and the expansion section can be effectively reduced, so that the economical efficiency of the diesel engine is ensured.
The flow guiding device of the expansion section of the SCR reactor adopts a trapezoidal layered design structure and consists of three layers of flow guiding rings, the angle of each layer of flow guiding ring can be adjusted according to the angle of the expansion angle of the SCR reactor, so that gas flow can be effectively divided, the disturbance of waste gas flow is reduced, the radial nonuniformity of the gas flow is improved, the gas flow is changed to be concentrated in the middle position of the expansion section, and NH near the pipeline wall is enabled to be concentrated3Low concentration and small flow rate, thereby improving the uniformity of gas flow rate and NH in the SCR reactor3Uniformity of concentration.
The invention can select one or more combined airflow guide devices according to the specific exhaust emission concentration and exhaust back pressure of the diesel engine, thereby improving the purification performance of the SCR system while ensuring the economy of the diesel engine. The bending section flow guide device can effectively improve the speed uniformity, and has simple structure and convenient manufacture; the vane type cyclone type mixer can reduce the pressure drop caused by arranging a flow guide device at other supplement positions of the SCR system while improving the gas-liquid mixing degree, thereby ensuring the economy of the diesel engine. The blade type cyclone mixer is used for promoting the urea aqueous solution to be fully atomized and hydrolyzed and fully mixed with the diesel engine waste gas; the guide device of the expansion section can reduce the disturbance of the waste gas flow and solve the problem that the flow is concentrated in the middle of the expansion section to cause NH near the pipeline wall3Low concentration and small flow rate, thereby improving the uniformity of gas flow rate and NH in the SCR reactor3Uniformity of concentration.

Claims (2)

1. An airflow directing device for an SCR, comprising: three airflow guiding devices are respectively arranged on a bent pipe section, a straight pipe section and an expansion section in the SCR system: the device comprises a bending section flow guide device, a blade type cyclone mixer and an expansion section guide device;
the bent section flow guiding device consists of a plurality of layers of flow guide rings at equal intervals, and can shunt gas to enter the bent section, reduce gas impacting the pipe wall and improve the uniformity of the flow velocity of the gas in the pipeline;
the blade type rotational flow type mixer is placed below the spray of the straight pipe section of the air inlet pipe of the SCR system, the mixer comprises six blades, the blades have certain radian, and the number and the radian of the blades can be adjusted according to the pipe diameter of the straight pipe section and the exhaust flow; a bearing is arranged in a thin shell in the middle of the mixer, and a connecting device is arranged in the bearing and connected with an air inlet pipe. When the airflow passes through the mixer, the airflow drives the blades to rotate, so that the airflow disturbance is effectively carried out, the mixing degree of urea and tail gas is improved, and the purification performance of the SCR system is improved;
the guiding device of the expansion section adopts a trapezoidal layered design structure and consists of three layers of guide rings, the angle of each layer of guide ring can be adjusted according to the angle of the expansion angle of the SCR reactor, so that gas flow can be effectively divided, the disturbance of waste gas flow is reduced, the radial nonuniformity of the gas flow is improved, the gas flow is changed to be concentrated in the middle of the expansion section, the concentration of NH3 near the pipeline wall is low, and the flow rate is low, so that the uniformity of the gas flow rate and the uniformity of the NH3 concentration in the SCR reactor are improved.
2. The airflow directing device for an SCR of claim 1, wherein: in the blade type rotational flow type mixer, the rotation of the blades can effectively reduce the pressure drop caused by the guide devices arranged on the bent pipe section and the expansion section, thereby ensuring the economy of the diesel engine.
CN202010582298.7A 2020-06-23 2020-06-23 Airflow guiding device for SCR Pending CN111677581A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112523843A (en) * 2020-11-17 2021-03-19 江苏大学 Control device and method for actively regulating and controlling working environment of diesel engine SDPF system

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947253A (en) * 1973-04-28 1976-03-30 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Catalytic exhaust gas purification device
CN103089383A (en) * 2013-02-04 2013-05-08 江苏大学 Guiding device and guiding method for diesel engine selective catalytic reduction (SCR) system for automobile
CN106311068A (en) * 2016-08-24 2017-01-11 上海理工大学 Dynamic blade mixer
CN207546230U (en) * 2017-11-13 2018-06-29 同兴环保科技股份有限公司 A kind of self-operated type ammonia mixing arrangement
CN108757125A (en) * 2018-06-19 2018-11-06 中国船舶重工集团柴油机有限公司 A kind of improved selective catalytic reduction device suitable for boat diesel engine
CN110295981A (en) * 2019-08-13 2019-10-01 中国船舶重工集团柴油机有限公司 A kind of high pressure SCR system of efficient emission-reducing peculiar to vessel

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3947253A (en) * 1973-04-28 1976-03-30 Dr. Ing. H.C.F. Porsche Aktiengesellschaft Catalytic exhaust gas purification device
CN103089383A (en) * 2013-02-04 2013-05-08 江苏大学 Guiding device and guiding method for diesel engine selective catalytic reduction (SCR) system for automobile
CN106311068A (en) * 2016-08-24 2017-01-11 上海理工大学 Dynamic blade mixer
CN207546230U (en) * 2017-11-13 2018-06-29 同兴环保科技股份有限公司 A kind of self-operated type ammonia mixing arrangement
CN108757125A (en) * 2018-06-19 2018-11-06 中国船舶重工集团柴油机有限公司 A kind of improved selective catalytic reduction device suitable for boat diesel engine
CN110295981A (en) * 2019-08-13 2019-10-01 中国船舶重工集团柴油机有限公司 A kind of high pressure SCR system of efficient emission-reducing peculiar to vessel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112523843A (en) * 2020-11-17 2021-03-19 江苏大学 Control device and method for actively regulating and controlling working environment of diesel engine SDPF system

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Application publication date: 20200918

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