CN214660452U

CN214660452U - Tail gas treatment system capable of effectively reducing energy consumption

Info

Publication number: CN214660452U
Application number: CN202120576306.7U
Authority: CN
Inventors: 邢科伟; 齐宝华; 李春强; 张庆昌; 杨超; 岳荣
Original assignee: Xian Cummins Engine Co Ltd
Current assignee: Xian Cummins Engine Co Ltd
Priority date: 2021-03-22
Filing date: 2021-03-22
Publication date: 2021-11-09
Anticipated expiration: 2031-03-22

Abstract

The utility model discloses a can effectively reduce tail gas processing system of energy consumption, including controller and intake pipe, leading catalyst unit, manifold, first break valve, second break valve, main rearmounted catalyst unit and vice rearmounted catalyst unit, leading catalyst unit includes first urea injection apparatus, leading DOC, second urea injection apparatus and leading SCR, and main rearmounted catalyst unit includes rearmounted DPFA, the first low flow combustor that links to each other with rearmounted DPFA through first three-way pipe, rearmounted SCRA and third urea injection apparatus, and vice rearmounted catalyst unit includes rearmounted DPFB, the second low flow combustor that links to each other with rearmounted DPFB through the second three-way pipe, rearmounted SCRB and fourth urea injection apparatus. The utility model discloses well main rearmounted catalyst unit and vice rearmounted catalyst unit parallel operation can effectively reduce system's backpressure, promote simultaneously and take off a sale efficiency.

Description

Tail gas treatment system capable of effectively reducing energy consumption

Technical Field

The utility model relates to a tail gas treatment system especially relates to a can effectively reduce tail gas treatment system of energy consumption.

Background

The current emission post-treatment technology mainly comprises: DOC (oxidation catalyst technology), DPF (particulate trap technology), SCR (selective catalytic reduction technology), and EGR (exhaust gas recirculation technology). In the existing emission post-treatment technology, the oxidation catalysis technology is mainly used for reducing the emission of HC and CO and increasing the low-temperature denitration efficiency of the selective catalytic reduction technology; particle trap technology is used to remove PM from exhaust gases; selective catalytic reduction techniques, which can remove NOx in exhaust gas by selectively promoting the reaction of a reducing agent with NOx, and exhaust gas recirculation techniques, which can both be used to reduce NOx in exhaust gas; and exhaust gas recirculation technology is the reduction of NOx emissions by lowering the peak combustion temperature in the engine.

In the technology of exhaust after-treatment of an engine, the DOC and the SCR have an operating temperature range. For DOC, HC and CO in tail gas can have considerable reaction to generate removal effect only when the temperature is higher than a certain ignition temperature, the working temperature of SCR is generally in the range of 190-450 ℃, and the working temperature ranges of different catalysts are slightly different.

In order to obtain high conversion efficiency, the temperature of the exhaust gas needs to be controlled in a high-efficiency temperature zone of the catalyst, and the existing exhaust gas treatment system arranges the DPF downstream of the DOC and the SCR downstream of the DPF; the layout is beneficial to the passive regeneration of the DPF, namely more NOx flows through the DPF to react with soot in the DPF, and meanwhile, the tail gas passing through the SCR is cleaner and is not easy to attach the soot on a catalyst; however, such an arrangement also has the disadvantage that the temperature of the exhaust gas reaching the SCR is reduced due to the heat absorption of the DPF, which is detrimental to the removal of NOx in low temperature exhaust gases, especially in the case of a relatively low DPF temperature, such as during cold start. In the prior art, in order to quickly raise the temperature of the SCR, the exhaust gas is often heated, which increases the energy consumption of the system. If the DPF is arranged at the downstream of the SCR, although the temperature rise process of the SCR can be accelerated, due to the denitration effect of the SCR, NOx is lacked, so that the passive regeneration effect is reduced, and the soot cleaning of the DPF cannot be completed by means of passive regeneration; while active regeneration generally heats the temperature of the exhaust passing through the DPF, the energy required for heating increases with the exhaust flow rate, and therefore the energy required for heating the exhaust increases significantly when the exhaust flow rate is large; meanwhile, the back pressure of the system is too high in the tail gas treatment process, so that the fuel combustion efficiency is further reduced, the economical efficiency is reduced, the dynamic performance is reduced, the emission is reduced, and the pollution is increased.

In the prior art, in the regeneration process, in order to reduce energy consumption, regeneration is only carried out when the tail gas flow is low; in mobile applications, when the exhaust gas treatment system is installed on a vehicle, low-flow regeneration can be achieved by regeneration only when the vehicle is stopped; in this case, the engine will be stopped or at idle and its exhaust gas flow is low; but limit certain applications of the exhaust gas treatment system, such as high exhaust gas flow regeneration applications.

Thus, there is a need to solve the above problems.

SUMMERY OF THE UTILITY MODEL

Utility model purpose: the utility model aims at providing a can effectively reduce the backpressure of system and promote the tail gas treatment system who takes off round pin efficiency effectively that can effectively reduce the energy consumption simultaneously.

The technical scheme is as follows: in order to achieve the above object, the utility model discloses a can effectively reduce tail gas processing system of energy consumption, including controller and along the intake pipe that the tail gas direction of giving vent to anger was arranged, leading catalyst unit, manifold, be located the first break-make valve of the first gas outlet department of manifold, be located the second break-make valve of the second gas outlet department of manifold, the main rearmounted catalyst unit that is linked together with the first gas outlet department of manifold and the vice rearmounted catalyst unit that is linked together with the second gas outlet department of manifold, leading catalyst unit includes the first urea injection apparatus who arranges along the tail gas direction of giving vent to anger, leading DOC, second urea injection apparatus and leading SCR, and main rearmounted catalyst unit includes rearmounted DPFA, the first low flow combustor that links to each other with rearmounted DPFA through first three-way pipe, rearmounted SCRA and the third urea injection apparatus that is located rearmounted SCRA upstream, vice rearmounted catalyst unit includes rearmounted DPFB, The second low-flow combustor, the rear SCRB and a fourth urea injection device are connected with the rear DPFB through a second three-way pipe; the controller is respectively electrically connected with the first urea injection device, the front DOC, the second urea injection device, the front SCR, the rear DPFA, the rear DPFB, the first low-flow combustor, the second low-flow combustor, the rear SCRA, the rear SCRB, the third urea injection device and the fourth urea injection device and controls the on and off of the first urea injection device, the front DOC, the second urea injection device, the front SCR, the rear DPFA, the rear DPFB, the first low-flow combustor, the second low-flow combustor, the rear SCRA, the rear SCRB, the third urea injection device and the fourth urea injection device.

The rear DPFA, the first air outlet of the manifold and the first low-flow combustor are communicated through a first three-way pipe, the rear DPFB is located at the upstream of the fourth urea injection device, and the rear DPFB, the first air outlet of the manifold and the second low-flow combustor are communicated through a second three-way pipe.

Preferably, the rear DPFA is positioned at the downstream of the rear SCRA, the rear DPFA, the rear SCRA and the first low-flow combustor are communicated through a first three-way pipe, and the third urea injection device is communicated with a first air outlet of the manifold; the rear DPFB is positioned at the downstream of the rear SCRB, the rear DPFB, the rear SCRB and the second low-flow combustor are communicated through a second three-way pipe, and the fourth urea injection device is communicated with a second air outlet of the manifold.

Furthermore, a third on-off valve is arranged at the outlet of the first low-flow combustor, and a fourth on-off valve is arranged at the outlet of the second low-flow combustor.

Preferably, the first urea injection device comprises a first decomposition pipe and a first mixer which are arranged between the air inlet pipe and the front DOC along the exhaust outlet direction, and a first urea nozzle is arranged on the first decomposition pipe.

Furthermore, the second urea injection device comprises a second decomposition pipe and a second mixer which are arranged between the front DOC and the front SCR along the exhaust gas outlet direction, and a second urea nozzle is arranged on the second decomposition pipe.

Further, the third urea injection device comprises a third decomposition pipe and a third mixer which are arranged at the upstream of the rear-mounted SCRA along the exhaust gas outlet direction, and a third urea nozzle is arranged on the third decomposition pipe; the fourth urea injection device comprises a fourth decomposition pipe and a fourth mixer which are arranged on the upstream of the rear SCRB along the exhaust gas outlet direction, and a fourth urea nozzle is arranged on the fourth decomposition pipe.

And the lower limit value of the working temperature of the front DOC is lower than the lower limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB, the upper limit value of the working temperature of the front DOC is higher than the lower limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB, and the upper limit value of the working temperature of the front DOC is lower than the upper limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB.

Has the advantages that: compared with the prior art, the utility model has the advantages of it is following:

(1) the utility model discloses when two sets of postposition catalysts work in parallel, denitration "relay" process makes from low temperature to high temperature all have at least two sets of catalysts to participate in the denitration, therefore can be under the lower application environment of tail gas temperature, can realize high-efficient catalytic action through heating tail gas not, thereby greatly reduced the energy consumption of system, parallelly connected catalyst works together simultaneously can effectively reduce the backpressure of system, promotes the efficiency of denitration simultaneously;

(2) when two sets of rear-mounted catalysts are used, the air flow of the DPF in the regeneration branch is controlled by the low-flow combustor, and the regenerated air flow is far lower than the tail gas flow, so that the regeneration energy consumption is reduced; meanwhile, the active regeneration branch is not carried out, so that the normal high-flow tail gas emission can be kept, the overall work of the system is not influenced, and the application of the whole machine is not influenced.

Drawings

Fig. 1 is a schematic structural diagram of embodiment 1 of the present invention;

fig. 2 is a schematic structural diagram of embodiment 2 of the present invention.

Detailed Description

The technical solution of the present invention will be further explained with reference to the accompanying drawings.

Example 1

As shown in fig. 1, in order to remove the emissions in the exhaust gas with high efficiency, this embodiment 1 is an exhaust gas treatment system capable of effectively reducing energy consumption, and includes a controller, an air inlet pipe 1, a pre-catalyst unit, a manifold 2, a first open-close valve 3, a second open-close valve 4, a main post-catalyst unit, and a sub-post-catalyst unit, where the air inlet pipe 1, the pre-catalyst unit, and the manifold 2 are sequentially arranged along the exhaust gas outlet direction, the first open-close valve 3 is located at a first air outlet of the manifold 2, the second open-close valve 4 is located at a second air outlet of the manifold 2, the main post-catalyst unit is communicated with the first air outlet of the manifold 2, and the sub-post-catalyst unit is communicated with the second air outlet of the manifold 2.

The preposed catalyst unit comprises a first urea injection device, a preposed DOC5, a second urea injection device and a preposed SCR6 which are sequentially arranged along the exhaust gas outlet direction, the first urea injection device comprises a first decomposition pipe 17 and a first mixer 18 which are arranged between the air inlet pipe 1 and the preposed DOC5 along the exhaust gas outlet direction, a first urea nozzle 19 is arranged on the first decomposition pipe 17, urea solution sprayed out of the first urea nozzle 19 is firstly sprayed into the first decomposition pipe and can be decomposed into ammonia gas, and the first mixer breaks up sprayed urea solution liquid drops and uniformly mixes the broken liquid drops with the exhaust gas; the first urea injection device injects urea, low-temperature high-efficiency NOx removal is realized by using the low-temperature catalytic characteristic of the metal platinum of the front DOC, the working temperature interval is determined according to the specific characteristic of the front DOC, and the working temperature interval of the front DOC can be 150-250 ℃; the second urea injection device comprises a second decomposition pipe 20 and a second mixer 21 which are arranged between the front DOC5 and the front SCR6 along the exhaust gas outlet direction, a second urea nozzle 22 is arranged on the second decomposition pipe 20, the urea solution sprayed out of the second urea nozzle 22 is firstly sprayed into the second decomposition pipe and can be decomposed into ammonia gas, and the second mixer breaks up the sprayed urea solution droplets and uniformly mixes the broken droplets with the exhaust gas; when the temperature of the front SCR rises to exceed the lower limit value of the working temperature of the front SCR, the lower limit value of the working temperature can be 190 ℃, and a second urea injection device arranged upstream of the front SCR starts to work to inject urea.

The main post-catalyst unit comprises a first three-way pipe 8, a first low-flow combustor 9, a post-DPFA 7, a third urea injection device and a post-SCRA, which are sequentially arranged along the exhaust gas outlet direction, the first low-flow combustor 9 is connected with one pipe orifice of the first three-way pipe 8, the post-DPFA 7 is connected with the other pipe orifice of the first three-way pipe 8, the rear DPFA7, a first air outlet of the manifold 2 and the first low-flow combustor 9 are communicated through a first three-way pipe 8, a third opening valve 15 is arranged at an outlet of the first low-flow combustor 9, the third urea injection device comprises a third decomposition pipe 23 and a third mixer 24 which are arranged at the upstream of the rear SCRA along the exhaust gas outlet direction, a third urea nozzle 25 is arranged on the third decomposition pipe 23, urea solution sprayed out of the third urea nozzle 25 is firstly sprayed into the third decomposition pipe and can be decomposed into ammonia gas, and the third mixer breaks up sprayed urea solution liquid drops and uniformly mixes the broken liquid drops with the exhaust gas; when the temperature of the rear SCRA rises to exceed the lower limit value of the working temperature of the rear SCRA, the lower limit value of the working temperature can be 190 ℃, and a third urea injection device on the upstream of the rear SCRA starts to work to inject urea.

The auxiliary post-catalyst unit comprises a second three-way pipe 12, a second low-flow combustor 13, a post-DPFB 11, a fourth urea injection device and a post-SCRB, wherein the second three-way pipe 12, the second low-flow combustor 13, the post-DPFB 11, the fourth urea injection device and the post-SCRB are sequentially arranged along the exhaust gas outlet direction, the rear DPFB11, a first air outlet of the manifold 2 and the second low-flow combustor 13 are communicated through a second three-way pipe 12, a fourth breaking valve 16 is arranged at an outlet of the second low-flow combustor 13, a fourth urea injection device comprises a fourth decomposition pipe 26 and a fourth mixer 27 which are arranged at the upstream of the rear SCRB along the exhaust gas outlet direction, a fourth urea nozzle 28 is arranged on the fourth decomposition pipe 26, urea solution sprayed out of the fourth urea nozzle 28 is firstly sprayed into the fourth decomposition pipe and can be decomposed into ammonia gas, and the fourth mixer breaks up sprayed urea solution droplets and uniformly mixes the broken droplets with the exhaust gas; when the temperature of the rear SCRB rises to exceed the lower limit value of the working temperature of the rear SCRB, the lower limit value of the working temperature can be 190 ℃, and the fourth urea injection device on the upstream of the rear SCRB starts to work to inject urea.

The utility model discloses the operating temperature lower limit value of well leading DOC is less than the operating temperature lower limit value of leading SCR, rearmounted SCRA and rearmounted SCRB, and the operating temperature upper limit value of leading DOC is higher than the operating temperature lower limit value of leading SCR, rearmounted SCRA and rearmounted SCRB, and the operating temperature upper limit value of leading DOC is less than the operating temperature upper limit value of leading SCR, rearmounted SCRA and rearmounted SCRB. When the temperature in the front DOC is higher than the lower limit value of the working temperature of the front DOC, starting the first urea injection device, and carrying out catalytic reaction on the front DOC; when the temperature of the front SCR rises to the lower limit value of the working temperature of the front SCR, starting a second urea injection device, and carrying out catalytic reaction on the front SCR; when the temperature of the rear SCRA rises to the lower limit value of the working temperature of the rear SCRA, a third urea injection device is started, and the rear SCRA performs catalytic reaction; when the temperature of the rear SCRB rises to the lower limit value of the working temperature of the rear SCRB, a fourth urea injection device is started, and the rear SCRB carries out catalytic reaction; and when the temperature in the DOC is higher than the upper limit value of the working temperature of the front DOC, the first urea injection device is closed, and the DOC does not generate catalytic reaction.

When main rearmounted catalyst unit and vice rearmounted catalyst unit adopt one to be equipped with a mode, the utility model discloses apart from the operating temperature lower limit value of leading DOC to this section interval of operating temperature lower limit value of leading SCR, only leading DOC carries out denitration, all the other all have two sets of catalysts to carry out denitration, leading DOC and leading SCR carry out denitration at least in one section, trailing section has leading SCR and rearmounted SCRA to carry out denitration or has leading SCR and rearmounted SCRB to carry out denitration at least in one section, so multiunit catalyst relay participates in the very big promotion of denitration reaction holistic efficiency of out-of-stock.

When main rearmounted catalyst unit and vice rearmounted catalyst unit adopt parallelly connected common work mode, the utility model discloses apart from the operating temperature lower limit value of leading DOC to this section interval of operating temperature lower limit value of leading SCR, only leading DOC carries out denitration, all the other all have at least two sets of catalysts to carry out denitration, leading DOC and leading SCR carry out denitration at least in one section, trailing one section has leading SCR at least, trailing SCRA and trailing SCRB carry out denitration, so multiunit catalyst relay participates in the very big promotion of denitration reaction holistic efficiency of taking off sale.

The controller is connected and control its and open and close with first urea injection apparatus, leading DOC5, second urea injection apparatus, leading SCR6, rearmounted DPFA7, rearmounted DPFB11, first low flow combustor 9, second low flow combustor 13, rearmounted SCRA10, rearmounted SCRB14, third urea injection apparatus and fourth urea injection apparatus looks electricity respectively, the utility model discloses well first urea injection apparatus, second urea injection apparatus, third urea injection apparatus and the three independent work of fourth urea injection apparatus group. When the engine starts to work, under the action of tail gas, the temperature of the front DOC starts to rise, when the temperature rises to be higher than the lower limit value (such as the ignition temperature of 150 ℃) of the working temperature of the front DOC, the controller controls the first urea injection device on the upstream of the front DOC to start to work, urea solution is injected to generate ammonia gas through cracking and pyrolysis, and then the ammonia gas and NOx in the tail gas react under the action of a platinum catalyst in the front DOC; the temperature of the front SCR begins to rise along with the rise of the temperature of the front DOC, and when the temperature of the front SCR exceeds the lower limit value (such as 190 ℃) of the working temperature of the front SCR, the controller controls a second urea injection device between the front DOC and the front SCR to start working, and the front SCR begins to generate a denitration effect; when the temperature of the tail gas further rises to exceed the upper limit value (such as 250 ℃) of the working temperature of the front DOC, the controller controls the first urea injection device upstream of the front DOC to be closed so as to avoid ammonia gas from being oxidized into NOx; meanwhile, when the temperature of the rear SCRA exceeds the lower limit value (for example 190 ℃) of the working temperature of the rear SCRA, the controller controls a third urea injection device at the upstream of the rear SCRA to start working, and the rear SCRA starts to perform denitration; when the temperature of the post-SCRB exceeds the lower limit value (for example 190 ℃) of the working temperature of the post-SCRB, the controller controls the fourth urea injection device at the upstream of the post-SCRB to start working, and the post-SCRB starts denitration.

In this embodiment, when the main post-catalyst unit and the sub-post-catalyst unit adopt a standby mode (i.e., the first and second on-off valves are opened and closed), the denitration has a "relay" process: the method comprises the steps that firstly, the front DOC starts to work in a low-temperature section (such as 150 ℃), then the front SCR starts to work, and finally the rear SCRA or the rear SCRB works, when the temperature is higher than a high-temperature limit (such as 250 ℃), the front DOC stops working, and the front SCR and the rear SCRA become main denitration catalysts or the front SCR and the rear SCRB become main denitration catalysts. The utility model discloses in, denitration "relay" process makes and all has two sets of catalysts to take off the round pin participating in from low temperature to high temperature, consequently can be under the lower application environment of tail gas temperature, and efficient catalytic action just can be realized to the non-heating tail gas to greatly reduced the energy consumption of system.

In this embodiment, when the main post-catalyst unit and the sub-post-catalyst unit adopt a parallel joint working mode (i.e. the first and second cut-off valves are both opened), the denitration has a "relay" process: the method comprises the steps that firstly, the front DOC starts to work in a low-temperature section (such as 150 ℃), then the front SCR starts to work, finally the rear SCRA and the rear SCRB work, when the temperature is higher than a high-temperature limit (such as 250 ℃), the front DOC stops working, and the front SCR, the rear SCRA and the rear SCRB become main denitration catalysts. The utility model discloses in, denitration "relay" process makes and all has two sets of catalysts to take off the round pin participating in from low temperature to high temperature at least, consequently can be under the lower application environment of tail gas temperature, and efficient catalytic action just can be realized to the non-heating tail gas to greatly reduced the energy consumption of system, simultaneously can also effectively reduce system's backpressure.

The volume of the preposed DOC5 of the preposed SCR6 participating in the catalytic reaction is V3, the volume of the preposed DOC5 of the preposed SCR6 not participating in the catalytic reaction under the same denitration efficiency is V4, and V3 is smaller than V4. Therefore, the front SCR can also be set to play a main role only in the temperature rise process, and in the tail gas temperature rise process, due to the help of the front DOC, the tail gas flow is lower, and the requirement on the efficiency of the front SCR can be properly reduced; therefore, under the same denitration efficiency, the volume of the front SCR can be reduced to reduce the back pressure; in such a system in which the volume of the pre-SCR is reduced, the post-SCRA and the post-SCRB are main catalysts after the temperature rises, and the pre-SCR assists.

When the rear DPFA is arranged at the upstream of the rear SCRA, the second urea injection device at the upstream of the front SCR can be closed after the temperature of the tail gas rises, so that the soot in the rear DPFA can be removed by utilizing passive regeneration, but the temperature rise of the rear SCRA is slow due to the heat capacity of the rear DPFA, and the volume of the front SCR needs to be increased in order to prevent the phenomenon of 'missing connection' possibly occurring in the denitration 'relay' process, namely the low valley of denitration efficiency occurs in the temperature rise process, namely the volume of the front SCR6 is V1; when the rear-mounted DPFB is arranged at the upstream of the rear-mounted SCR, the second urea injection device at the upstream of the front-mounted SCR can be closed after the temperature of the exhaust gas rises, so that the soot in the rear-mounted DPFB can be removed by fully utilizing the passive regeneration, but the temperature rise of the rear-mounted SCR is slow due to the heat capacity of the rear-mounted DPFB, and the volume of the front-mounted SCR needs to be increased in order to prevent the phenomenon of 'missing connection' which may occur in the denitration 'relay' process, namely the low valley of denitration efficiency occurs in the temperature rise process, namely the volume of the front-mounted SCR6 is V1.

The utility model discloses a reduce the energy of regeneration process consumption, parallelly connected set up main rearmounted catalyst unit and vice rearmounted catalyst unit, use first low flow combustor to take the initiative regeneration to rearmounted DPFA, use second low flow combustor to take the initiative regeneration to rearmounted DPFB, rearmounted DPFA and rearmounted DPFB can be regenerated in turn respectively. When the main post-catalyst unit needs to be regenerated, the first cut-off valve is powered on and cut off, the first low-flow combustor provides high-temperature airflow to regenerate the catalyst, the airflow of the first low-flow combustor is controllable, so that the catalyst can be regenerated by using low-flow airflow, and the airflow of DPF regeneration is controlled by the low-flow combustor to be far lower than the exhaust airflow, so that the energy consumption of regeneration is reduced; when regeneration at high tail gas flow is needed, the main post catalyst unit and the auxiliary post catalyst unit can work alternately in the regeneration process, for example, the first cut-off valve is closed, the third cut-off valve is opened, high-temperature gas flow provided by the first low-flow combustor is used for regenerating the post DPFA, the second cut-off valve is opened, the fourth cut-off valve is closed, and the post DPFB is not used for active regeneration, so that the tail gas flow is high, the air flow in the regenerated DPFA branch is still low, and the energy consumption is low, so that the whole operation of the system is not influenced.

Example 2

As shown in fig. 2, in order to remove the emissions in the exhaust gas efficiently, the exhaust gas treatment system of this embodiment 2 capable of reducing energy consumption effectively includes a controller, an air inlet pipe 1, a pre-catalyst unit, a manifold 2, a first open-close valve 3, a second open-close valve 4, a main post-catalyst unit, and a sub-post-catalyst unit, wherein the air inlet pipe 1, the pre-catalyst unit, and the manifold 2 are sequentially arranged along the exhaust gas outlet direction, the first open-close valve 3 is located at a first gas outlet of the manifold 2, the second open-close valve 4 is located at a second gas outlet of the manifold 2, the main post-catalyst unit is communicated with the first gas outlet of the manifold 2, and the sub-post-catalyst unit is communicated with the second gas outlet of the manifold 2.

The main post-catalyst unit comprises a third urea injection device, a post-SCRA, a first three-way pipe 8, a first low-flow combustor 9 connected with one pipe orifice of the first three-way pipe 8 and a post-DPFA 7 connected with the other pipe orifice of the first three-way pipe 8 which are sequentially arranged along the exhaust gas outlet direction, the rear SCRA, the first low-flow combustor 9 and the rear DPFA7 are communicated through a first three-way pipe 8, a third opening valve 15 is arranged at the outlet of the first low-flow combustor 9, the third urea injection device comprises a third decomposition pipe 23 and a third mixer 24 which are arranged at the upstream of the rear SCRA along the exhaust gas outlet direction, a third urea nozzle 25 is arranged on the third decomposition pipe 23, the urea solution sprayed out of the third urea nozzle 25 is firstly sprayed into the third decomposition pipe and can be decomposed into ammonia gas, and the third mixer breaks up the sprayed urea solution droplets and uniformly mixes the broken droplets with the exhaust gas; when the temperature of the rear SCRA rises to exceed the lower limit value of the working temperature of the rear SCRA, the lower limit value of the working temperature can be 190 ℃, and a third urea injection device on the upstream of the rear SCRA starts to work to inject urea.

The auxiliary post-catalyst unit comprises a fourth urea injection device, a post-SCRB, a second three-way pipe 12, a second low-flow combustor 13 connected with one pipe orifice of the second three-way pipe 12 and a post-DPFB 11 connected with the other pipe orifice of the second three-way pipe 12 which are sequentially arranged along the exhaust gas outlet direction, the rear SCRB, the second low-flow combustor 13 and the rear DPFB11 are communicated through a second three-way pipe 12, a fourth breaking valve 16 is arranged at the outlet of the second low-flow combustor 13, the fourth urea injection device comprises a fourth decomposition pipe 26 and a fourth mixer 27 which are arranged at the upstream of the rear SCRB along the exhaust gas outlet direction, a fourth urea nozzle 28 is arranged on the fourth decomposition pipe 26, the urea solution sprayed out of the fourth urea nozzle 28 is firstly sprayed into the fourth decomposition pipe and can be decomposed into ammonia gas, and the fourth mixer breaks up sprayed urea solution droplets and uniformly mixes the broken droplets with the exhaust gas; when the temperature of the rear SCRB rises to exceed the lower limit value of the working temperature of the rear SCRB, the lower limit value of the working temperature can be 190 ℃, and the fourth urea injection device on the upstream of the rear SCRB starts to work to inject urea.

The volume of the pre-SCR may be reduced when the post-DPFA is arranged downstream of the post-SCRA and the volume of the pre-SCR may be reduced when the post-DPFB is arranged downstream of the post-SCRB, i.e. when the volume of the pre-SCR 6 is V2, the volume of the pre-SCR 6 in example 1 is V1 is greater than the volume of the pre-SCR 6 in example 2, V2.

Claims

1. The utility model provides a can effectively reduce tail gas treatment system of energy consumption which characterized in that: the device comprises a controller, an air inlet pipe (1), a pre-catalyst unit, a manifold (2), a first cut-off valve (3) positioned at a first air outlet of the manifold, a second cut-off valve (4) positioned at a second air outlet of the manifold, a main post-catalyst unit communicated with the first air outlet of the manifold and an auxiliary post-catalyst unit communicated with the second air outlet of the manifold, wherein the air inlet pipe (1), the pre-catalyst unit, the manifold (2), the first cut-off valve and the second cut-off valve are arranged along the exhaust gas outlet direction; the front catalyst unit comprises a first urea injection device, a front DOC (5), a second urea injection device and a front SCR (6) which are arranged along the exhaust gas outlet direction, the main rear catalyst unit comprises a rear DPFA (7), a first low-flow combustor (9) connected with the rear DPFA through a first three-way pipe (8), a rear SCRA (10) and a third urea injection device positioned at the upstream of the rear SCRA, and the auxiliary rear catalyst unit comprises a rear DPFB (11), a second low-flow combustor (13) connected with the rear DPFB through a second three-way pipe (12), a rear SCRB (14) and a fourth urea injection device positioned at the upstream of the rear SCRB; the controller is respectively electrically connected with the first urea injection device, the front DOC (5), the second urea injection device, the front SCR (6), the rear DPFA (7), the rear DPFB (11), the first low-flow combustor (9), the second low-flow combustor (13), the rear SCRA (10), the rear SCRB (14), the third urea injection device and the fourth urea injection device and controls the on and off of the first urea injection device, the front DOC (5), the second urea injection device, the front SCR (6), the rear DPFA (7), the rear DPFB (11), the first low-flow combustor (9), the second low-flow combustor, the rear SCRA (10), the rear SCRB (14), the third urea injection device and the fourth urea injection device.

2. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the rear DPFA (7) is positioned at the upstream of the third urea injection device, the rear DPFA (7), a first air outlet of the manifold (2) and the first low-flow combustor (9) are communicated through a first three-way pipe (8), the rear DPFB (11) is positioned at the upstream of the fourth urea injection device, and the rear DPFB (11), the first air outlet of the manifold (2) and the second low-flow combustor (13) are communicated through a second three-way pipe (12).

3. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the rear DPFA (7) is positioned at the downstream of the rear SCRA (10), the rear DPFA (7), the rear SCRA (10) and the first low-flow combustor (9) are communicated through a first three-way pipe (8), and the third urea injection device is communicated with a first air outlet of the manifold (2); the rear DPFB (11) is located at the downstream of the rear SCRB (14), the rear DPFB (11), the rear SCRB (14) and the second low-flow combustor (13) are communicated through a second three-way pipe (12), and the fourth urea injection device is communicated with a second air outlet of the manifold (2).

4. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: and a third on-off valve (15) is arranged at the outlet of the first low-flow combustor (9), and a fourth on-off valve (16) is arranged at the outlet of the second low-flow combustor (13).

5. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the first urea injection device comprises a first decomposition pipe (17) and a first mixer (18), wherein the first decomposition pipe and the first mixer are arranged between the air inlet pipe and the front DOC along the exhaust outlet direction, and a first urea nozzle (19) is arranged on the first decomposition pipe; the second urea injection device comprises a second decomposition pipe (20) and a second mixer (21), wherein the second decomposition pipe and the second mixer are arranged between the front DOC and the front SCR along the exhaust gas outlet direction, and a second urea nozzle (22) is arranged on the second decomposition pipe.

6. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the third urea injection device comprises a third decomposition pipe (23) and a third mixer (24) which are arranged at the upstream of the rear SCRA along the exhaust gas outlet direction, and a third urea nozzle (25) is arranged on the third decomposition pipe.

7. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the fourth urea injection device comprises a fourth decomposition pipe (26) and a fourth mixer (27), wherein the fourth decomposition pipe and the fourth mixer are arranged at the upstream of the rear SCRB along the exhaust gas outlet direction, and a fourth urea nozzle (28) is arranged on the fourth decomposition pipe.

8. The tail gas treatment system capable of effectively reducing energy consumption according to claim 1, characterized in that: the lower limit value of the working temperature of the front DOC is lower than the lower limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB, the upper limit value of the working temperature of the front DOC is higher than the lower limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB, and the upper limit value of the working temperature of the front DOC is lower than the upper limit values of the working temperature of the front SCR, the rear SCRA and the rear SCRB.