CN201588675U

CN201588675U - Diesel particulate filter and selective catalytic reduction compound system for tail gas clean-up of diesel engine

Info

Publication number: CN201588675U
Application number: CN200920286164XU
Authority: CN
Inventors: 谭丕强; 胡志远; 楼狄明
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2009-12-24
Filing date: 2009-12-24
Publication date: 2010-09-22
Anticipated expiration: 2019-12-24

Abstract

The utility model belongs to the field of diesel engine exhaust gas after-treatment technique, and particularly relates to a diesel particulate filter and selective catalytic reduction compound system for tail gas clean-up of a diesel engine. The system comprises a diesel particulate filter (DPF), a selective catalytic reduction (SCR) device, a tail gas valve, an airflow control valve, an exhaust pipe, a middle pipe and the like, wherein the airflow control valve is respectively connected with the diesel engine exhaust pipe, a DPF front end pipe and an SCR front end pipe, the DPF front end pipe is connected with the diesel particulate filter (DPF) which is connected with a DPF rear end pipe internally provided with a DPF tail gas valve; the SCR front end pipe is connected with the selective catalytic reduction (SCR) device connected with an SCR rear end pipe internally provided with an SCR trail gas valve, and the middle pipe is connected with the diesel particulate filter (DPF) and the selective catalytic reduction (SCR) device. According to the change in load of the diesel engine, the system can flexibly adjust the sequence that waste gas flow passes through a DPF device and an SCR device, give full play to the advantages of respective arrangement schemes, and improve the purification effect of particles and emitted nitric oxide in the waste gas of the diesel engine greatly.

Description

Particle trapper and selective catalytic reduction combined hybrid system that diesel engine vent gas purifies

Technical field

The utility model belongs to diesel engine vent gas post-processing technology field, is specifically related to particle trapper and selective catalytic reduction (DPF+SCR) combined hybrid system that a kind of diesel engine vent gas purifies.

Background technique

Diesel engine is widely used in fields such as communications and transportation, farm machinery and engineering machinery with its good and economic and power character.But particulate of diesel engine (PM) and nitrogen oxide (NOx) discharging are higher, environment and human body all there is very big harm, except that continuing to take the interior measure of machine to improve the burning, must take the outer reprocessing control techniques of machine to particulate in the diesel exhaust and nitrogen oxide, could effectively reduce the noxious emission amount of the two.In many technological schemes, micro particle filtering catcher DPF is one of main post-processing technology measure that reduces particle emission, and selective catalytic reduction SCR is one of main post-processing technology measure that reduces discharged nitrous oxides.

Along with the increasingly stringent of automobile emission regulation, must on diesel engine exhaust system, install DPF and SCR simultaneously additional, could satisfy following more strict Abgasgesetz, such as the U.S.'s No. 6 Abgasgesetzs of automobile emission regulation or Europe afterwards in 2010.

When vent systems is used DPF and SCR simultaneously, there is the priority Layout Problem of the two particular location.In general two kinds of schemes are arranged:

(1) SCR behind the first DPF, promptly waste gas passes through SCR again by DPF earlier.For this scheme, waste gas by DPF, can carry out trap filter with the particulate in the waste gas earlier, and the waste gas behind the purification particulate enters SCR again, can reduce the depositions in SCR such as soot particle, favourable to response area and the service behaviour thereof that guarantees NOx in the SCR catalyst converter.Shortcoming is when to be waste gas through DPF enter SCR again, and the waste gas self-temperature descends to some extent, and this just can have the SCR system of good NOx conversion efficiency unfavorable to needing uniform temperature.

(2) DPF behind the first SCR, promptly waste gas passes through DPF again by SCR earlier.For this scheme, then just opposite with aforementioned schemes.When waste gas during earlier by SCR when reducing the NOx discharging, the exhaust gas temperature that enters SCR this moment is higher, this is to guaranteeing that wherein the catalytic conversion efficient of NOx is very favourable.Have the inwall that part is deposited on the SCR catalyst converter but shortcoming is the particulate in the waste gas, its service behaviour is influenced to some extent.Waste gas enters DPF more then, and its particulate is captured purification, and this moment, exhaust gas temperature decreased.If it is what its regeneration techniques used is active regeneration techniques such as technology such as electric heating or oil spout, little to its regeneration effect influence; If but what adopt is passive regeneration technology such as catalytic regeneration or additive regeneration, because regeneration needs certain delivery temperature, so regeneration effect will be affected.

As seen, adopt the DPF+SCR technology can reduce diesel particulation and discharged nitrous oxides simultaneously, but, influenced the two reprocessing purifying effect diesel engine vent gas owing to there is present system layout problem.

Summary of the invention

The purpose of this utility model is that the diesel engine vent gas that provides a kind of while effectively to reduce particulate and discharged nitrous oxides purifies particle trapper and selective catalytic reduction (DPF+SCR) combined hybrid system.

Particle trapper and selective catalytic reduction combined hybrid system that the diesel engine vent gas that the utility model proposes purifies, by DPF particle trapper 1, SCR selective catalytic reduction device 2, DPF tail gas valve 3, SCR tail gas valve 4, control damper 5, outlet pipe 7, DPF front tube 8, SCR front tube 9, DPF rear end pipe 10, SCR rear end pipe 11 and intervalve 12 are formed, wherein, the left side of control damper 5 connects Diesel Engine Exhaust Pipe 7 one ends, Diesel Engine Exhaust Pipe 7 the other ends connect diesel engine 6, control damper 5 upsides connect DPF front tube 8 one ends, downside connects SCR front tube 9 one ends, DPF front tube 8 the other ends connect the front end of DPF particle trapper 1, the rear end of DPF particle trapper 1 connects DPF rear end pipe 10, be provided with rotatable DPF tail gas valve 3 in the DPF rear end pipe 10, the rear end of this DPF rear end pipe 10 communicates with atmosphere; SCR front tube 9 the other ends connect the front end of SCR selective catalytic reduction device 2, the rear end of SCR selective catalytic reduction device 2 connects SCR rear end pipe 11, be provided with rotatable SCR tail gas valve 4 in the SCR rear end pipe 11, the rear end of this SCR rear end pipe 11 communicates with atmosphere; Intervalve 12 connects DPF particle trapper 1 and SCR selective catalytic reduction device 2.

In the utility model, the waste gas that diesel engine is discharged is through outlet pipe 7, and when arriving control damper 5 places, control damper 5 has two positions, enters DPF front tube 8 or SCR front tube 9 with the decision air-flow.

Working procedure of the present utility model is:

(1) when diesel engine is in large load operation, the diesel particulate emission amount is higher, and delivery temperature is also higher.Control damper 5 is switched to lower position (as shown in Figure 1), close DPF tail gas valve 3 simultaneously and open SCR tail gas valve 4.Waste gas is introduced into DPF particle trapper 1 with the filtration, purification particulate.Then, the waste gas after the filter particulates enters SCR selective catalytic reduction device 2 via intervalve 12, and the exhaust initial temperature is higher during owing to big load, when entering SCR again via DPF, still has uniform temperature in the SCR to help the catalytic reduction process of NOx.

(2) when diesel engine is in little load operation, the diesel particulate emission amount is lower.Control damper 5 is switched to top position (as shown in Figure 2), close SCR tail gas valve 4 simultaneously and open DPF tail gas valve 3.Waste gas is introduced into SCR selective catalytic reduction device 2 to reduce the NOx discharging.Because this moment, particulate emission was low,, influence less to its service behaviour so it is less to be deposited on the particulate loading of SCR catalyst converter inwall.Waste gas enters DPF via intervalve 12 then, its particulate is carried out trap filter purify.

The utility model is according to the variation of diesel load, the flexible sequencing of adjusting off-gas flows by DPF and SCR device, at utmost bring into play the advantage of arrangement separately and avoid the shortcoming of arrangement separately, the purifying effect of particulate and discharged nitrous oxides improves greatly in the diesel exhaust thereby make.

Description of drawings

Fig. 1 is the structural diagrams when control damper 5 is in lower position among the utility model embodiment 1.

Fig. 2 among the utility model embodiment 1 above control damper 5 is in the structural diagrams the during position.

Number in the figure: 1 is the DPF particle trapper, and 2 is the SCR selective catalytic reduction device, and 3 is DPF tail gas valve, and 4 is SCR tail gas valve, 5 is control damper, and 6 is diesel engine, and 7 is outlet pipe, and 8 is the DPF front tube, 9 is the SCR front tube, and 10 is the DPF rear end pipe, and 11 is the SCR rear end pipe, and 12 is intervalve.

Embodiment

Further specify the utility model below by embodiment.

Embodiment 1: the waste gas that diesel engine is discharged at first flows into outlet pipe 7, and the left side of control damper 5 connects Diesel Engine Exhaust Pipe 7, and its upside is a DPF front tube 8, and downside is a SCR front tube 9.The front end of DPF connects front tube 8, and the rear end connects DPF rear end pipe 10, and a rotatable DPF tail gas valve 3 is arranged in the DPF rear end pipe 10, and the rear end of this rear end pipe 10 communicates with atmosphere.The front end of SCR connects front tube 9, and the rear end connects SCR rear end pipe 11, and a rotatable SCR tail gas valve 4 is arranged in the SCR rear end pipe 11, and the rear end of this rear end pipe 11 communicates with atmosphere.Intervalve 12 connects DPF particle trapper 1 and SCR selective catalytic reduction device 2.

As shown in Figure 1, when control damper 5 was in lower position, air-flow entered DPF front tube 8, sealed SCR front tube 9 simultaneously.Meanwhile, DPF tail gas valve 3 cuts out, and SCR tail gas valve 4 is opened, and off-gas flows flows into SCR selective catalytic reduction device 2 via DPF particle trapper 1 via intervalve 12, and the SCR rear end pipe 11 of flowing through again finally enters atmosphere.

As shown in Figure 2, during the position, air-flow enters SCR front tube 9, seals DPF front tube 8 simultaneously above control damper 5 is in.Meanwhile, SCR tail gas valve 4 cuts out, and DPF tail gas valve 3 is opened, and off-gas flows flows into DPF particle trapper 1 via SCR selective catalytic reduction device 2 via intervalve 12, and the DPF rear end pipe 10 of flowing through again finally enters atmosphere.

Claims

1. the particle trapper and the selective catalytic reduction combined hybrid system that purify of a diesel engine vent gas, by DPF particle trapper (1), SCR selective catalytic reduction device (2), DPF tail gas valve (3), SCR tail gas valve (4), control damper (5), outlet pipe (7), DPF front tube (8), SCR front tube (9), DPF rear end pipe (10), SCR rear end pipe (11) and intervalve (12) are formed, the left side that it is characterized in that control damper (5) connects Diesel Engine Exhaust Pipe (7) one ends, Diesel Engine Exhaust Pipe (7) the other end connects diesel engine (6), control damper (5) upside connects DPF front tube (8) one ends, downside connects SCR front tube (9) one ends, DPF front tube (8) the other end connects the front end of DPF particle trapper (1), the rear end of DPF particle trapper (1) connects DPF rear end pipe (10), be provided with rotatable DPF tail gas valve (3) in the DPF rear end pipe (10), the rear end of this DPF rear end pipe (10) communicates with atmosphere; SCR front tube (9) the other end connects the front end of SCR selective catalytic reduction device (2), the rear end of SCR selective catalytic reduction device (2) connects SCR rear end pipe (11), be provided with rotatable SCR tail gas valve (4) in the SCR rear end pipe (11), the rear end of this SCR rear end pipe (11) communicates with atmosphere; Intervalve (12) connects DPF particle trapper (1) and SCR selective catalytic reduction device (2).