CN101375029A

CN101375029A - Controlled regeneration system

Info

Publication number: CN101375029A
Application number: CNA2006800529432A
Authority: CN
Inventors: S·N·科拉维努; S·M·萨赫德
Original assignee: Honeywell International Inc
Current assignee: Honeywell International Inc
Priority date: 2005-12-28
Filing date: 2006-12-19
Publication date: 2009-02-25
Also published as: WO2007078932A2; EP1969209A2; US20070144149A1; JP2009522489A; WO2007078932A3

Abstract

A system (80) for controlled regeneration of a lean NOx trap for an internal combustion engine. The system may include regenerating one trap (82, 83) or a portion of a lean NOx trap while using another trap or portion of the lean NOx trap for an exhaust, and then interchanging operations. The portions may be individual structures or of one structure. The trap may be a rotating element that is regenerated in part at a time. There may be valves (91, 93, 94) that direct the exhaust gas through one trap and regeneration gas through another trap and vice versa. Also, an exhaust system with regeneration may include temperature, pressure, NOx and differential pressure sensors. A processor may be connected to the sensors. There may be emission sampling lines connected to different parts of the system and to a collector to take, store, detect and analyze samples. A processor may be connected to the collector.

Description

Controlled regeneration system

Background technique

[0001] the present invention relates to engine exhaust system, and relate to the pollutant of control especially from releasing system.More specifically, the present invention relates to the renewal of the pollutant minimizing system of releasing system.

Summary of the invention

[0002] the invention provides the controlled updating that the poor nitrogen oxide (NOx) that is used for engine exhaust system receives portion.

Description of drawings

[0003] Fig. 1 a and 1b have shown the dual trap catalysis system;

[0004] Fig. 2 is the schematic representation with poor nitrogen oxide update system of instrument;

[0005] Fig. 3 is the figure line of injection speed control;

[0006] Fig. 4 is the figure line that shows the exhaust temperature management;

[0007] Fig. 5 is the figure line that shows the example of catalyst degradation speed;

[0008] Fig. 6 a is the schematic representation that is used to receive the chemical process of portion;

[0009] Fig. 6 b is to use the schematic representation of rich, high temperature fuel mixture;

[0010] Fig. 7 a has shown the device that can be placed in system's discharge stream;

[0011] Fig. 7 b has shown the updated stored device that is movable to the effluent with low flow velocity, high temperature and hypoxemia; With

[0012] Fig. 8,9 and 10 has showed various poor nox trap assemblies with continuous rotation of absorber element.

Embodiment

[0013] in automobile, to compare with traditional petrol engine, diesel engine and poor combustion petrol engine can provide the fuel economy benefit of 30-50% and 10-15% respectively.But, may need poor nox trap (LNT) system to loose to reduce nitrogen oxide row.Represent the poor nox trap of the traditional current global mechanism system of prior art situation can reduce nitrogen oxide, but have multiple shortcoming, comprising: because the high fuel cost due to the temperature of discharge stream needs regularly to raise entirely; The catalyzer that is related to the nitrogen oxides storage capacity loads; The high desulfurization temperature of LNT may be to the influence of durability of catalyst generation; With because less and to the influence of efficient generation from the nitrogen oxide of downstream material and the chance of meeting of catalyzer.The poor nox trap of a kind of controlled updating system can overcome these problems.

[0014] native system can address these problems by utilizing multiple principle.These principles are, catalysis is separated with the nitrogen oxides storage function, and use the controlled stream of gases of separating to carry out the storage medium renewal.Can there be many physical embodiments in these principles.Under " normally " operational condition, effulent can flow through NO is oxidized to NO ₂Oxidation catalyst and after through comprising such as Ca or BaCO ₃And so on the absorption system of absorbent material.When absorption system " saturated " and absorption efficiency decline, flowing to turn to much smaller tourie.The NOx sensor signal can be used for triggering above-mentioned turning to the computing device that is fit to.Though main engine exhaust flows is by than mini system, main system can use have controlled temperature, the mobile stream of oxygen and CO/HC concentration and upgrading.When main system was updated to default level, flowing to return to normal state, and renewable than mini system.The ratio of storage and update time can be determined the dimensional ratios of two systems.Alternately, can use the rotation absorber element.Absorption and update functions can and be carried out continuously along with the element rotation, and can keep absorption efficiency.The NO of desorb ₂Can in the three-way catalyst in downstream, be reduced to N ₂

[0015] Fig. 1 a has shown the catalysis system 80 with dual trap 30.Dual trap 30 can comprise: main poor nox trap (P-LNT) 82 and secondary poor nox trap (S-LNT) 83.Discharge pipe 78 can be with catalytic converter 81 (O _xC) be connected to the discharge manifold (Fig. 2) of engine 11.Effulent 79 can enter has oxidation catalyst so that NO is converted into NO ₂Catalytic converter 81 (O _xC) in.Catalyst material can be precious metal such as Pt or the material suitable with it.Effulent 79 can walk to main poor nox trap (P-LNT) 82 from converter 81, and P-LNT 82 can be suitable for the storage capacity of nitrogen oxide dimensionally.Receive the basic material of portion 82 can comprise or can be metal such as barium or calcium.Alternately, effulent 79 can walk to secondary poor nox trap (S-LNT) 83 from converter 81, and S-LNT 83 can be suitable for being used by the short time when the master receives portion 82 to upgrade dimensionally.Two-way valve 91 can that is to say be directed to lead to receive portion 82 or be directed to pair and receive portion 83, this depends on whether main poor nox trap 82 is being updated with exhausting air 79 along the guiding of one of both direction.Burner (B) 84 can be used for producing the low flow rate of gas 95 of high temperature and zero oxygen, is used for the renewal of poor nox trap 82 or 83.Burner 84 can add hot exhaust gases or provide another heated air to be used for renewal.When one was received portion to be used as to receive portion, another received portion to upgrade.Receive sustainable three tunnel catalysis (TWC) device 85 that passes through of output of

portion

82 or 83, wherein install 85 noble metal catalysts that have such as Pt.

[0016] two-way valve 92 can be directed to the low flow rate of gas 95 that is used to upgrade and receive portion 82 or receive portion 83.Two-way valve 93 can be worked as when receiving portion 82 to be output as exhausting air 79 it is directed to discharge pipe 96, maybe when receiving portion 82 to be output as to upgrade gas 95 it is directed to TWC device 85.Two-way valve 94 can be worked as when receiving portion 83 to be output as exhausting air 79 it is directed to discharge pipe 96, maybe when receiving portion 83 to be output as to upgrade gas 95 it is directed to TWC device 85.Valve 91-94 can be among two position A and the B, or is in more than one in two positions (that is, having the variable valve of open and close).If valve 91-94 moves towards the A position, then P-LNT 82 can be used as exhaust trap and S-LNT 83 can be used for upgrading.If valve 91-94 moves towards the B position, then P-LNT 82 can be used for upgrading and S-LNT 83 can be used as exhaust trap.Valve 91-94 can have the actuator that is connected to processor 90 shown in Fig. 1 b (and/or ECU (engine control unit)), and processor 90 determines when valve 91-94 should be in position A or B or be between A, the B and when definite burner 84 should work.Such actuating can also may be determined according to other factors according to the renewal needs of

device

82 and 83.

[0017] the dual trap system 80 among Fig. 1 a and the 1b can have the device at system's different parts, as shown in Fig. 1 b.Input and output place at converter 81 can have

temperature transducer

131 and 132 respectively.Input and output place at converter 81 can have pressure transducer 141 and 142 respectively.Input and output place at converter 81 can have

sampling circuit

161 and 162 respectively.Outlet at converter 81 can have NOx sensor 152.Can have temperature transducer 133, pressure transducer 143, NOx sensor 153 and sampling circuit 163 in the outlet of P-LNT 82.Can have temperature transducer 134, pressure transducer 144, NOx sensor 154 and sampling circuit 164 in the outlet of S-LNT 83.Input at P-LNT and S-LNT can directly be positioned with similar sensor; But, the sensor 132,142,152 and 162 in the outlet of converter 81 can be enough to substitute the LNT input pickup.

[0018] can have temperature transducer 135, pressure transducer 145 and sampling circuit 165 in the outlet of TWC 85 or filter 85.If filter 85 is located and regular effulent 79 is passed through wherein, then

valve

93 and 94 can suitably switch and realize that gas 79 flows through filter.Filter 85 is renewable, for example by enough gas (95 or 79) renewals of heat.Filter 85 can for example be a particulate material filter.

[0019] input and output place at TWC or filter 85 can have paired

differential pressure pickup

146 and 147 respectively.Outlet at burner 84 also can have temperature transducer 138 and pressure transducer 148.Described sensor can be connected to processor 90.Sensor and sampling circuit can be in the upstream or the downstream of corresponding proximate valves.Sampling circuit can be connected to collection and the detecting devices that can be used as processor 90 parts.Being connected among Fig. 1 b of sensor and sampling circuit and processor 90 is not shown.In system 80, can there be other sensor and sampling circuit.The sensor of other types can be arranged in system 80.

[0020] Fig. 2 has shown the example of the exhaust catalyst system 10 of instrumentation.For for the many engines the diesel engine, should can be particulate matter (PM), nitrogen oxide (NO by controlled most important pollutant _x) and sulfur oxide (SO _x).Engine 11 can output to pre-catalyst device 13 via manifold 97 and discharge pipe 14 with effulent 12.Pre-catalyst device 13 can mainly comprise oxidation catalyst.Pre-catalyst 13 can be used for crossing when the engine emissions temperature temperature of rising effulent 12 when low, improves the validity of downstream catalytic system with rapid heating.Effulent 12 can continue to walk to nox adsorber catalyst (NAC) device 15 of bottom via discharge pipe 16.

[0021] NAC can be mainly used in absorb or storage with the nitrogen oxide of nitrate form.For example, diesel emissions can tend to have excess of oxygen.Therefore, nitrogen oxide may not directly be reduced to N ₂Nitrogen oxide can be stored a bit of time (about 60 seconds capacity).That can carry out the utmost point short time (that is, approximately 2-5 second) is rich in the fuel-air married operation, makes the oxygen concentration of discharge stream reduce to and approaches zero.Temperature also can rise to desirable scope.Under these conditions, nitrogen oxide can react to produce N with CO and the HC in the effulent ₂, CO ₂And H ₂O.Can use the catalyzer of base metal and precious metal.

[0022] effulent 12 can walk to catalyzed diesel particulate filter 17 via discharge pipe 18 from NAC 15.This filter can be effulent 12 provides physical filtering with trap particulates.Wherein can comprise precious metal.After this, when temperature range was fit to, oxidation can take place in the particulate matter that is received.Effulent 12 can be via discharge pipe 19 discharge systems 10.

[0023] except poor/rich change of 60/2-5 second of nox adsorption/desorb reduction, also may there be other " passive " processes.These processes comprise desulfurization and PM after-flame (burn-off).The nox adsorption position can be by SO _xSaturated.Therefore, should regularly drive away SO _x, this may need than the required much higher temperature of nox desorption.For the PM after-flame,, then may exist and be forced to after-flame if drive condition (for example low speed of long duration or city operations) causes excessive PM accumulation.According to the duty factor of operation, the accumulation period can be a few hours.Cleaning can be several minutes (about 10 minutes).May need higher temperature and rational oxygen level.

[0024] as seen, catalysis system 10 can relate to complicated chemical reaction process.This process can be by being connected to sensor monitoring flow velocity, temperature, pressure and the pollutant of processor or computer 20.Described sensor can be arranged in the different parts of catalytic exhaust system 10, and can be used for surveying the recovery of needs, cleaning end and the normal running of capacity saturation point, rising exhaust temperature.

[0025] temperature transducer 21 and pressure transducer 22 can be arranged in discharge pipe 14 and be connected to computer or processor 20.The temperature transducer 23 and the pressure transducer 24 that are connected to processor 20 can be set in the discharge pipe 16.Temperature transducer 25 and pressure transducer 26 can be set in the discharge pipe 18.Temperature transducer 27 and pressure transducer 28 can be set in the discharge pipe 19.Differential pressure pickup 29 can be connected to discharge pipe 18 and discharge pipe 19 to survey the pressure difference between the discharge pipe 18 and 19.This pressure difference determined value can be sent to processor 20.NOx sensor 31 can be arranged in discharge pipe 16 and be connected to processor 20.NOx sensor 32 can be in the discharge pipe 18 and can be connected to processor 20.Processor 20 can be connected to the engine control unit (ECU) 65 at engine 11 places.

[0026] a plurality of discharging

sampling circuits

41,42,43 and 44 also can be set, it from

discharge pipe

14,16,18 and 19 traps 45 to sampling, is used for detecting and assessment respectively.Trap 45 can be connected to processor 20.In discharge pipe or

circuit

14,16,18 and 19, can there be

other sensor

46,47,48 and 49 respectively, be used for detecting different parameters according to the demand and the needs of releasing system 10.Trap 45 can be connected to processor 20.

[0027] fuel injection system can be designed to provide injection process, for example preceding process 51, bootup process 52, main procedure 53, from process 54 and back process 55, these processes as shown in the control of the injection speed among Fig. 3 figure line, have wherein shown the situation of injected fuel with respect to crank position with this time order.Do not influence the power that provides by engine from injection process 54 and back injection process 55, and can be advantageously used in and add heat discharge simply and use up excess of oxygen.Pre-catalyst can be pretreated pith, and this is because all burnings do not occur in the cylinder.The figure line 65 of Fig. 4 has shown the management of exhaust temperature.Line 56 is total torque percentage figure lines with respect to engine speed percentage.Upper right time line show approach the main injection process 57 of upper dead center (TDC) and be in TDC and lower dead centre (BDC) between the back injection process 58 in somewhere.This time line adds the back injection areas of 56 tops of reaching the standard grade corresponding to normal combustion in the figure line 65.The time line of bottom right shows the main injection process 57 that approaches TDC respectively and just at the first right-hand back injection process 59 of main procedure 57, and the second back injection process 58.This time line adds the back injection areas of line 56 belows of twice corresponding to normal combustion in the figure line 65.

[0028] in some cases, when temperature in process of expansion is very low (for example under the underload condition), back injected fuel can be used as crude fuel and flows out, and becomes and be difficult to use pre-catalyst 13 management.Under these circumstances, can use after two

kinds

59 and 58, one early stage elevated temperatures that are used in expansion stroke of injection, and second be used for the catalyzer process that further elevated temperature is used for the downstream.May there be influence to the engine fuel Economy.

[0029] native system aspect can be based on the information from process controller 20.Usually in catalytic flow system, the validity of catalyzer can reduce along catalyst length streamwise index, as shown in Figure 5.The figure line 66 of Fig. 5 shows the example of catalyst degradation speed.This figure line has shown the situation of absorption site percentage with respect to catalyst-assembly total length percentage of using up.

Curve

61,62,63 and 64 be along with in the figure line by the increase of time shown in the line 70 for the used positions of different periods curve with respect to catalyst length.

[0030] catalysis can be different with storage operation.Downstream desorption can demonstrate less catalyzer and thereby have low conversion of nitrogen oxides efficient.If poor nox trap (LNT) is separated in traditional current global mechanism system with catalyzer, then may need catalyzer to be used for upstream oxidation and downstream reduction.Catalyzer (Pt) and storage medium (Ba ₂CO ₃) can in traditional current global mechanism LNT system, mix.Have problem,, storage capacity and expensive Pt interrelated and cause the high desulfurization temperature of catalyst degradation comprising the temperature of the full releasing system that raises about " mixing " current global mechanism system.

[0031] Fig. 6 a is the schematic representation that is used to receive the chemical process of (lean fuel mixture).Can be with NO and O ₂The NO that adds Pt catalyzer 67 ₂In, can form like this and walk to the NO that receives portion 68 ₃Fig. 6 b is to use the schematic representation of the renewal of rich, high temperature fuel mixture.Fuel can be joined and receive the NO that collects in the portion 69 ₃In.Fuel from rich effulent can join NO ₃Thereby, form from receiving portion 69 and towards the combination of Pt catalyzer 71.Under the situation of back one action, from the described NO that receives the heat that portion removes ₃Can walk to catalyzer 71.At this, NO ₃Can in catalyzer, distribute N ₂And utilize CO to form NO.

[0032] catalysis can separate with material with storing process.Can adopt multiple physical arrangement.Fig. 7 a has shown the device 72 that can be placed in system's discharge stream.The device 72 can be used as in the normal poor operation receive portion and corresponding to the process among Fig. 6 a.Pt in the catalyst member 73 can be suitable for the NO-NO under full discharge speed dimensionally ₂Transformation efficiency.Material in the parts 73 can be some other suitable material.In receiving parts 74, receive material B a ₂CO ₃The optimization that can be suitable for storage capacity/efficiency/space dimensionally is compromise.Fig. 7 b has shown the updated stored device that is movable to the effluent with low flow velocity, high temperature and hypoxemia.Parts 76 can comprise and receive material B a ₂NO ₃Come self refresh to receive the NO of parts 76 ₃Can walk to catalyst member 77 and be used to be converted into NO.Pt amount required in the parts 77 can be less owing to hang down flow velocity.Catalyst material can be the material suitable with it that substitutes Pt.

[0033] Fig. 8 is illustrated in the poor nox trap (LNT) of the continuous rotation of the assembly 40 that has absorbing NOx element 109 in the parts 101.Parts 102 can have oxidation catalyst (O _xC) 104 and burner (B) 105.Burner 105 can provide the controlled flow of the controlled CO/HC concentration gases (that is, upgrading gas) of the zero oxygen of heat.Look closely Figure 106 and showed O _xThe subregion of C 104 and B 105.Parts 103 have the subregion of three-way catalyst (TWC) 108, TWC 108 use from burner 105, by receiving portion's element the part that is used to upgrade, to the stream of TWC 108, as look closely shown in Figure 107.Receive portion 109 rotatable, thereby but make its all part final updated.

[0034] Fig. 9 is presented at poor nox trap (LNT) assembly 50 of the continuous rotation that has absorber element 114 in the parts 111.Parts 112 can have burner (B) 115 and oxidation catalyst (O _xC) 116 subregion, as look closely shown in Figure 117.Parts 113 can have the subregion of three-way catalyst (TWC) 119 and the subregion of absorber element 114, as look closely shown in Figure 118.Burner 115 can provide the controlled flow of controlled CO/HC concentration gases of the zero oxygen of heat.Balance between renewal and rotation can keep the required absorption efficiency of main poor nox trap 50.

[0035] Figure 10 has shown the poor nox trap (LNT) 127 of the continuous rotation of the assembly 60 with each parts 121,122 and 123.The Figure 124 that looks closely of parts 122 has shown the subregion of burner (B) 126 and has received all the other subregions 127 of portion.The Figure 125 that looks closely of parts 123 has shown the subregion of three-way catalyst (TWC) 128 and has received all the other subregions 127 of portion.

[0036] ask in basis in the file, some contents are expressed with other forms or mode although be for character hypothesis or that estimate.

[0037] though the present invention be described by at least one illustrated examples, but to those skilled in the art, by reading over present specification, multiple variation and revise and will become apparent.Therefore, claims are intended to limit with respect to prior art as far as possible widely, and comprise variation and the modification that all are such.

Claims

1. the property upgraded system comprises:

Catalytic converter with input and output;

First valve, it is connected to the output of described catalytic converter;

First receives portion, and its input that has is connected to first output of described first valve;

Second receives portion, and its input that has is connected to second output of described first valve;

Second valve, its input that has are connected to described first output of receiving portion; With

The 3rd valve, its input that has are connected to described second output of receiving portion.

2. system as claimed in claim 1 further comprises: multichannel catalytic converter, the output that its first input that has is connected to the output of described second valve and is connected to described the 3rd valve.

3. system as claimed in claim 1, wherein, described first receives portion and second to receive portion to be respectively first nox trap and second nox trap.

4. system as claimed in claim 3 further comprises:

Burner with output;

The 4th valve, its input that has is connected to the output of described burner, and its first output that has is connected to the input of described first nox trap, and its second output that has is connected to the input of described second nox trap.

5. system as claimed in claim 4, wherein, each in described first valve, second valve, the 3rd valve and the 4th valve has actuator.

6. system as claimed in claim 5 further comprises: processor, it is connected to the actuator of described first valve, second valve, the 3rd valve and the 4th valve.

7. system as claimed in claim 6, wherein,

In described first valve, second valve, the 3rd valve and the 4th valve each has the primary importance and the second place at least;

Described primary importance makes exhausting air flow to described first nox trap from described catalytic converter, and makes that upgrading gas flow arrives described second nox trap; With

The described second place makes exhausting air flow to described second nox trap from described catalytic converter, and makes that upgrading gas flow arrives described first nox trap.

8. system as claimed in claim 7, wherein, described first nox trap and second nox trap are poor nox trap.

9. the releasing system of an instrumentation comprises:

Pre-catalyst device with output;

Dual trap with input and output, this input is connected to the output of described pre-catalyst device; With

Filter, its input that has is connected to the output of described dual trap.

10. system as claimed in claim 9, wherein,

Described pre-catalyst device is the oxidation catalyst device;

Described dual trap comprises the nox adsorption catalyst-assembly; With

Described filter is a catalytic particulate filter.

11. system as claimed in claim 9, wherein,

Described pre-catalyst is used to change the temperature of exhausting air;

Described dual trap is used for absorbing NOx; With

Described filter is used to receive the particulate from exhausting air.

12. as the system of claim 11, wherein, when receiving portion to receive nitrogen oxide for one in the described dual trap, another in the described dual trap receives portion to upgrade.

13. the system as claim 12 further comprises:

Be positioned at first temperature transducer of the input of described pre-catalyst; With

Be positioned at second temperature transducer of the outlet of described pre-catalyst.

14. the system as claim 13 further comprises: the processor that is connected to described first and second temperature transducers.

15. the system as claim 14 further comprises: third and fourth temperature transducer between the input of the output of described dual trap and described filter.

16. the system as claim 15 further comprises: the 5th temperature transducer that is positioned at the outlet of described filter.

17. the system as claim 12 further comprises:

First pressure transducer in the input of described pre-catalyst device; With

Second pressure transducer between the input of the output of described pre-catalyst device and described dual trap.

18. the system as claim 17 further comprises:

Third and fourth pressure transducer between the input of the output of described dual trap and described filter; With

The 5th pressure transducer in the outlet of described filter.

19. the system as claim 17 further comprises: the differential pressure pickup that is positioned at the input and the outlet of described filter.

20. the system as claim 17 further comprises:

Be positioned at first NOx sensor of the outlet of described pre-catalyst device; With

Lay respectively at the second and the 3rd NOx sensor of the outlet of described dual trap.

21. system as claimed in claim 9 further comprises:

Trap;

First sample line, its be connected to described trap and be in the output of described pre-catalyst device and the input of described dual trap between; With

Second sample line, the input that it is connected to described trap and is connected to described filter.

22. the system as claim 21 further comprises: the 3rd sample line, the output that it is connected to described trap and is connected to described filter.

23. the system as claim 22 further comprises: the 4th sample line, the input that it is connected to described trap and is connected to described pre-catalyst device.

24. a row looses and receives parts, comprising:

Rotatable row with first end and second end looses and receives portion;

Be attached to diffusing first parts that receive first end of portion of described rotatable row; With

Be attached to diffusing second parts that receive second end of portion of described rotatable row.

25. as the assembly of claim 24, wherein,

The first portion of described first parts is catalyst-assemblies;

The second portion of described first parts is burners;

The first portion of described second parts is the diffusing portions that receive of row;

The second portion of described second parts is multichannel catalyzer.

26. as the assembly of claim 25, wherein,

Exhausting air can flow through the first portion of described first parts, described rotatable row looses and receives at least a portion of portion and the first portion of described second parts;

Upgrade gas and can flow through described rotatable row loose at least a portion of receiving portion, and the second portion by described second parts from the second portion of described first parts.