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
  • F01N3/18—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]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
  • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
  • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
  • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
  • B01D53/9495—Controlling the catalytic process
• • 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
  • F01N13/00—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00
  • F01N13/009—Exhaust or silencing apparatus characterised by constructional features ; Exhaust or silencing apparatus, or parts thereof, having pertinent characteristics not provided for in, or of interest apart from, groups F01N1/00 - F01N5/00, F01N9/00, F01N11/00 having two or more separate purifying devices arranged in series
• • 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
  • F01N3/105—General auxiliary catalysts, e.g. upstream or downstream of the main catalyst
  • F01N3/106—Auxiliary oxidation catalysts
• • 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
  • F01N3/2053—By-passing catalytic reactors, e.g. to prevent overheating
• • 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
  • F01N9/00—Electrical control of exhaust gas treating apparatus
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
  • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
  • F02D41/146—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration
  • F02D41/1461—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration of the exhaust gases emitted by the engine
  • F02D41/1462—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an NOx content or concentration of the exhaust gases emitted by the engine with determination means using an estimation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2251/00—Reactants
  • B01D2251/20—Reductants
  • B01D2251/206—Ammonium compounds
  • B01D2251/2067—Urea
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/10—Noble metals or compounds thereof
  • B01D2255/102—Platinum group metals
  • B01D2255/1021—Platinum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2255/00—Catalysts
  • B01D2255/20—Metals or compounds thereof
  • B01D2255/207—Transition metals
  • B01D2255/20723—Vanadium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/01—Engine exhaust gases
  • B01D2258/012—Diesel engines and lean burn gasoline engines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
  • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
  • B01D53/9404—Removing only nitrogen compounds
  • B01D53/9409—Nitrogen oxides
  • B01D53/9413—Processes characterised by a specific catalyst
  • B01D53/9418—Processes characterised by a specific catalyst for removing nitrogen oxides by selective catalytic reduction [SCR] using a reducing agent in a lean exhaust gas
• • 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
  • F01N2410/00—By-passing, at least partially, exhaust from inlet to outlet of apparatus, to atmosphere or to other 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
• • 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
  • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
  • F01N2900/04—Methods of control or diagnosing
  • F01N2900/0412—Methods of control or diagnosing using pre-calibrated maps, tables or charts
• • 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
  • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
  • F01N2900/06—Parameters used for exhaust control or diagnosing
  • F01N2900/08—Parameters used for exhaust control or diagnosing said parameters being related to the engine
• • 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
  • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
  • F01N2900/06—Parameters used for exhaust control or diagnosing
  • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
  • F01N2900/1402—Exhaust gas composition
• • 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
  • F01N9/00—Electrical control of exhaust gas treating apparatus
  • F01N9/005—Electrical control of exhaust gas treating apparatus using models instead of sensors to determine operating characteristics of exhaust systems, e.g. calculating catalyst temperature instead of measuring it directly
• • 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
  • F01N9/00—Electrical control of exhaust gas treating apparatus
  • F01N9/007—Storing data relevant to operation of exhaust systems for later retrieval and analysis, e.g. to research exhaust system malfunctions
• • 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
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/10—Capture or disposal of greenhouse gases of nitrous oxide (N2O)
• • 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
• • 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
  • Y02T10/40—Engine management systems

Definitions

• the present disclosure is directed to an exhaust treatment system and, more particularly, to an exhaust treatment system that implements selective Diesel Oxidation Catalyst (DOC) bypass.
• DOC Diesel Oxidation Catalyst
• SCR is a process where gaseous or liquid reductant (most commonly urea) is added to the exhaust gas stream of an engine and is absorbed onto a catalyst. The reductant reacts with NOx in the exhaust gas to form H 2 O and N 2 .
• gaseous or liquid reductant most commonly urea
• the reductant reacts with NOx in the exhaust gas to form H 2 O and N 2 .
• SCR can be effective, it is most effective when a concentration of NO to NO 2 supplied to the SCR is about 1:1.
• DOC Diesel Oxidation Catalyst
• NO 2 also facilitates the combustion of particulate matter.
• a particulate trap is commonly used to collect unburned particulates also known as soot. Over time, the particulate matter builds up in the trap and, if left unchecked, the particulate trap could negatively affect performance of the engine. As such, the particulate matter collected by the trap must be periodically removed through a process called regeneration.
• a liquid catalyst typically diesel fuel
• the fuel in the presence OfNO 2 , ignites and burns away the particulate matter.
• the ratio of NO to NO 2 may naturally be about 1 :1. In this situation, if all of the exhaust is passed through the DOC, the ratio of NO to NO 2 could actually exceed the desired 1:1 ratio and reduce the effectiveness of the SCR process. Thus, under some conditions, the exhaust flow can be directed to bypass the DOC. In another example, the DOC is only necessary during trap regeneration events. In this example, in order to conserve the DOC, the exhaust flow can again be directed to bypass the DOC during non-regeneration events.
• Patent Application JP 2005-2968 A (the '968 publication) by Mitsubishi Fuso, published January 6, 2005.
• the '968 publication discloses an exhaust gas purifying system having an oxidation catalyst, a temperature sensor, a bypass path, a bypass switching device, and an SCR device.
• the system is designed to create a 1 : 1 ratio of NO:NO 2 in an exhaust flow.
• the system estimates a ratio of NO:NO 2 based on a sensed exhaust gas temperature.
• the oxidation catalyst converts NO to NO 2
• the SCR device converts NO and NO 2 to N 2 in the presence of ammonia.
• the SCR device operates most efficiently when the ratio of NOrNO 2 is 1 : 1.
• the bypass switching device diverts exhaust flow so that the exhaust gas flows through the bypass path, and not through the oxidation catalyst. In this way, the system aims to prevent excessive NO 2 in the exhaust gas flow.
• the '968 publication also discloses the possibility of employing a NOx sensor to directly sense aNO:NO 2 ratio. [0007] ' Although the exhaust gas purifying apparatus of the '968 publication may disclose a method of operation that aims to achieve a 1:1 ratio of NO to NO 2 in an exhaust flow, it may be limited.
• NOx sensors that satisfy desired performance requirements to measure NOx effectively and quickly enough to provide real-time control over NO:NO 2 ratio in an exhaust flow.
• estimating an NO:NO 2 ratio based on a measurement of exhaust gas temperatures and other exhaust parameters may not accurately reflect the NO:NO 2 ratio, because, for example, changes in engine operating parameters may cause changes in an exhaust gas NOtNO 2 ratio, but not an exhaust gas temperature.
• changes in engine operating parameters may cause changes in exhaust gas temperature but not in an exhaust gas NO:N ⁇ 2 ratio.
• the exhaust treatment system may include an SCR device, and an oxidation device located upstream of the SCR device to convert NO to NO 2 .
• the exhaust treatment system may also include an exhaust passageway extending from an exhaust source to the oxidation device, and a bypass passageway extending from the exhaust passageway at a location upstream of the oxidation device to the exhaust passageway at a location downstream of the oxidation device.
• the exhaust treatment system may further include a valve element configured to selectively direct exhaust from the exhaust source through the oxidation device and through the bypass passageway, at least one sensor configured to sense operating parameters of the exhaust source, and a controller in communication with the valve element.
• the controller may be configured to move the valve element in response to an estimated ratio of NO to NO 2 based on sensed operating parameters of the exhaust source.
• Another aspect of the present disclosure is directed to a method of treating exhaust.
• the method may include generating a flow of exhaust, treating at least a portion of the flow of exhaust by a catalyst, and directing the flow of exhaust through an SCR device.
• the method may also include estimating a ratio of NO to NO 2 in the flow of exhaust based on sensed operating parameters of a power source that generates the flow of exhaust, and changing an amount of the at least a portion in response to the estimation.
• FIG. 1 is a schematic and diagrammatic illustration of an exemplary disclosed power system
• Fig. 2 is a flowchart depicting an exemplary disclosed operation of the power system of Fig. 1. Detailed Description
• Fig. 1 illustrates a power source 10 having an exemplary embodiment of an exhaust treatment system 12.
• Power source 10 may include an engine such as, for example, a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other engine apparent to one skilled in the art.
• Power source 10 may also include any non-engine source of power, such as a furnace.
• Power source 10 may combust a mixture of air and fuel to produce a power output and an exhaust gas flow.
• the exhaust gas flow from power source 10 may be diverted through exhaust treatment system 12.
• Exhaust treatment system 12 may include components that cooperate, by way of a main passageway 14, to treat the exhaust gas flow from power source 10.
• exhaust treatment system 12 may include a diesel oxidation catalyst (DOC) 26, an SCR device 32, and a urea injection unit 30.
• Exhaust treatment system 12 may also include a bypass circuit having a bypass valve 20 and bypass passageway 24.
• DOC 26 may be located within main passageway 14 and include a porous ceramic honeycomb-like or metal mesh substrate. The substrate may be coated with a material such as, for example, a precious metal, that catalyzes a chemical reaction to alter the chemical composition of exhaust gas.
• DOC 26 may include platinum or vanadium to facilitate the conversion of NO constituents into NO 2 , which may be more susceptible to catalytic treatment in SCR device 32.
• SCR device 32 may be disposed in main passageway 14 downstream of
• Urea injection unit 30 may be located adjacent to or upstream of SCR device
• SCR device 32 to inject urea directly into SCR device 32 and/or into main passageway 14.
• the injected urea may be broken down into ammonia, which may be retained within SCR device 32.
• the ammonia stored in SCR device 32 maybe used to reduce the amount of NO x in the exhaust gases passing through SCR device 32 by converting NO 2 to N 2 .
• other agents suitable for reducing NO x may be injected into main passageway 14 and/or SCR device 32.
• Bypass valve 20 may be fluidly connected to main passageway 14 and bypass passageway 24 at a point upstream of DOC 26.
• Bypass valve 20 may be any commonly known three-way valve capable of directing flow in variable proportion between two separate passageways (i.e. between main passageway 14 and bypass passageway 24).
• bypass valve 20 may be a two-way valve (not shown) located within bypass passageway 24.
• Bypass valve 20 may include a valve element 22 configured to control the amount of exhaust gas delivered to DOC 26.
• valve element 22 may be movable between a first, "open” position, at which substantially all of the exhaust gas flow from power source 10 is directed to flow through bypass passageway 24, toward a second, “closed” position, at which all of the exhaust gas flow from power source 10 is directed to flow through DOC 26.
• Valve element 22 may also be positioned at any intermediate position between the open and closed positions, to direct portions of the exhaust gas flow to both DOC 26 and bypass passageway 24.
• Valve element 22 may include a spool valve element, a ball valve element, a globe valve element, a butterfly valve element, or any other suitable type of valve element known in the art.
• Bypass valve 20 may include means for automatically moving valve element 22 in response to a control signal.
• control system 34 may regulate the operation of bypass valve 20 in response to one or more inputs.
• control system 34 may include a controller 36 that communicates with bypass valve 20 by way of a communication line 40, and with sensor 38 by way of a communication line 42.
• controller 36 may adjust a setting of valve element 22.
• Controller 36 is shown in Fig. 1 as a single controller, and it may include one or more microprocessors that include a means for controlling an operation of exhaust treatment system 12.
• controller 36 may be one or more controllers, each assigned to control a subsystem, and in communication with each other, for example a controller configured to control power source 10, and a separate controller configured to control exhaust treatment system 12.
• Numerous commercially available microprocessors may be configured to perform the functions of controller 36.
• controller 36 may alternatively embody a general engine control unit (ECU) capable of controlling numerous functions, including power source 10 and exhaust treatment system 12.
• ECU engine control unit
• Controller 36 may include all of the components required to run an application such as, for example, a memory, a secondary storage device, and a processor, such as a central processing unit or any other means known in the art for controlling bypass valve 20 and sensor 38.
• a processor such as a central processing unit or any other means known in the art for controlling bypass valve 20 and sensor 38.
• Various other known circuits may be associated with controller 36, including power supply circuitry, signal-conditioning circuitry, solenoid driver circuitry, communication circuitry, and other appropriate circuitry.
• Controller 36 may receive and store in memory communication from various sensors and components commonly known in the art, such as, for example, sensor 38, including measurements of, for example, exhaust gas NOx composition and concentrations, power source fuel/air settings, power source operating speed, power source load, power source fuel injection profile, other power source operating parameters, and/or DOC 26 operating temperature. Controller 36 may analyze and compare received and stored data, and, based on instructions and data stored in memory or input by a user, determine whether action is required. For example, controller 36 may compare received values with target values stored in memory, and, based on the results of the comparison, controller 36 may transmit signals to adjust bypass valve 20. [0022] Controller 36 may include memory means known in the art for storing data relating to engine operation.
• the data may be stored in the form of one or more maps that describe relationships between various power source 10 and/or DOC 26 operating parameters and resulting power source 10 exhaust gas compositions.
• Each of these maps may be in the form of tables, graphs, and/or equations, and include a compilation of data collected from lab and/or field operation of power source 10 and DOC 26.
• These maps may be generated by performing instrumented tests on the operation of power source 10 and DOC 26 under a variety of operating conditions, while varying parameters such as power source fuel/air settings, power source operating speed, power source load, power source fuel injection profile, other power source operating parameters, and while measuring DOC 26 operating temperature and exhaust gas NOiNO 2 ratio.
• Data from the tests may be logged, and may show correlation, for example, among one or more power source and/or DOC operating parameters and exhaust gas NOx composition, including a NO:NO 2 ratio.
• controller 36 may be capable of updating the maps based on measured operating conditions of power source 10 and DOC 26, which may allow controller 36 to adjust the maps to match the particular operating characteristics and modes of an individual power source 10 and DOC 26. Controller 36 may reference these maps and control the position of bypass valve 20 to bring the operation of exhaust treatment system 12 in line with desired values.
• Controller 36 may also contain one or more virtual models of exhaust treatment system 12.
• a virtual model may contain information such as tables, graphs, and/or equations, and include a compilation of data collected from lab and/or field operation of exhaust treatment system 12.
• the virtual model may contain data correlating exhaust gas NO:NO 2 ratio as reported by sensor 38, bypass valve 20 setting, operating parameters of power source 10 and/or DOC 26, and an expected exhaust gas NOrNO 2 ratio downstream of DOC 26.
• a virtual model may enable controller 36 to determine, based on sensed exhaust gas NO:NO 2 ratio, power source 10 operating parameters, and/or DOC 26 operating parameters, a setting of valve element 22 that will produce a desired exhaust gas NO:NO 2 ratio downstream of DOC 26.
• Controller 36 may use a virtual model in an open loop mode of operation of exhaust treatment system 12, as described below.
• Sensor 38 may be associated with main passageway 14. Sensor 38 is shown, for example, downstream of DOC 26. One skilled in the art will recognize, however, that sensor 38 may alternatively or additionally include sensing elements associated with, for example, power source 10, DOC 26, and SCR device 32. Sensor 38 may directly sense a concentration of NO and NO 2 in an exhaust gas flow, and generate a signal in response thereto. Alternatively, sensor 38 may sense a NO:NO 2 ratio of an exhaust gas flow and generate a ratio signal in response thereto. Sensor 38 may be any type of sensor commonly known in the art for sensing NO and NO 2 composition.
• sensor 38 may alternatively embody both physical sensors and a virtual sensor, included in controller 36, that generates a signal based on a map-driven estimate.
• a virtual sensor may include one or more physical sensing elements associated with, for example, power source 10 and/or DOC 26. Physical sensing elements may detect and communicate to controller 36 parameters including, for example power source fuel/air settings, power source operating speed, power source load, power source fuel injection profile, other power source operating parameters, and/or DOC 26 operating temperature.
• Virtual sensor 38 may evaluate the signals received from various physical sensors, and, using relationships contained within one or more maps stored in a memory of controller 36, estimate the expected exhaust gas NO:NO 2 ratio based on the sensed parameters.
• Controller 36 may monitor and regulate valve element 22 of bypass valve 20 to control the amount of exhaust gas delivered to DOC 26. Controller 36 may monitor an actual exhaust gas NOx composition via sensor 38 to determine a N0:NO 2 ratio, and then adjust valve element 22 to deliver an amount of exhaust gas to DOC 26 necessary to provide SCR device 32 with exhaust gas having a desired ratio of NO:NO 2 . In one embodiment, the desired ratio may be 1:1.
• controller 36 may monitor operating parameters of power source 10 and/or DOC 26, use the maps stored in memory to estimate an exhaust gas NOrNO 2 ratio based on the sensed operating parameters, and then adjust valve element 22 to deliver an amount of exhaust gas to DOC 26 necessary to provide SCR device 32 with exhaust gas having a desired NOiNO 2 ratio.
• the desired ratio may be 1 : 1.
• Controller 36 may control a NO:NO 2 ratio using either a closed or open loop scheme.
• controller 36 may measure a NO:NO 2 ratio using sensor 38, determine that the ratio is too low, adjust valve element 22 toward its open position to direct more exhaust gas flow to bypass passageway 24, and then measure a NO:NO 2 ratio again. If controller 36 determines the ratio is still too low, controller 36 may open bypass valve 20 further and then measure a NOrNO 2 ratio again, continuing until the desired NO:NO 2 ratio is obtained.
• controller 36 may measure a NOrNO 2 ratio using sensor 38, determine that the ratio is too high, adjust valve element 22 toward its closed position to direct more exhaust gas flow to DOC 26, and then measure a NOrNO 2 ratio again. If controller 36 determines the ratio is still too high, controller 36 may close bypass valve 20 further and then measure a NOrNO 2 ratio again, continuing until the desired NOrNO 2 ratio is obtained.
• controller 36 may measure a NOrNO 2 ratio using sensor 38, compare that ratio to a desired NOrNO 2 ratio, and then, based on a virtual model of exhaust treatment system 12 stored in memory of controller 36, adjust valve element 22 to a specific setting corresponding to the desired NOrNO 2 ratio. For example, when sensor 38 reports a NOrNO 2 ratio of 2:1, then controller 36 may use a virtual model of exhaust treatment system 12 to determine that valve element 22 should be moved to, for example, 25% bypass, so as to obtain a desired exhaust gas NOrNO 2 ratio for SCR device 32.
• Fig. 2 shows a flowchart illustrating an exemplary method of operating control system 34. Fig. 2 will be described in detail below.
• the exhaust treatment system of the present disclosure may be applicable to any power source, including, for example, an engine or a furnace that benefits from reduced NOx emissions.
• the disclosed system may improve reduction of NOx by providing an approximately 1:1 mix of NO and NO 2 to an associated SCR device.
• the operation of exhaust treatment system 12 will now be explained. [0031] Referring to Fig. 1, air and fuel may be drawn into power source 10 for subsequent combustion. Fuel maybe injected into power source 10, mixed with the air therein, and combusted by power source 10 to produce a mechanical work output and an exhaust gas flow.
• the exhaust gas flow may contain a complex mixture of air pollutants composed of gaseous material, which can include oxides of nitrogen (NOx).
• DOC 26 may modify a NOx composition of exhaust gas by converting NO to NO 2
• SCR device 32 may remove NO 2 from the exhaust gas flow by conversion to N 2 (Step 100).
• controller 36 may determine a ratio of
• controller 36 may determine an exhaust gas NOrNO 2 ratio by sensing operating parameters of power source 10 and/or DOC 26, and then compare the parameters with relationships stored in one or maps in controller 36 memory. For example, controller 36 may use a map as a lookup table to determine the ratio OfNOrNO 2 based on sensed power source fuel/air settings, power source operating speed, power source load, power source fuel injection profile, other power source operating parameters, and/or DOC 26 operating temperature.
• controller 36 may adjust valve element 22 toward its open position to decrease the amount of exhaust gas flowing through DOC 26. Controller 36 may increase the amount of exhaust gas flowing through bypass passageway 24 until the ratio of NOiNO 2 in the exhaust gas reaches about 1 :1 (Step 108).

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• 2007
  • 2007-05-02 EP EP07825368A patent/EP2142771A1/de not_active Withdrawn
  • 2007-05-02 WO PCT/IB2007/003065 patent/WO2008135805A1/en active Application Filing
  • 2007-05-02 US US12/598,417 patent/US20100199634A1/en not_active Abandoned

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