CN105547707A - Method for verifying urea crystallization of SCR post-treatment system by use of engine pedestal - Google Patents
Method for verifying urea crystallization of SCR post-treatment system by use of engine pedestal Download PDFInfo
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- CN105547707A CN105547707A CN201610016810.5A CN201610016810A CN105547707A CN 105547707 A CN105547707 A CN 105547707A CN 201610016810 A CN201610016810 A CN 201610016810A CN 105547707 A CN105547707 A CN 105547707A
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- G—PHYSICS
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M15/00—Testing of engines
- G01M15/04—Testing internal-combustion engines
Abstract
The invention relates to a method for verifying urea crystallization of a SCR post-treatment system by use of an engine pedestal. The method is characterized by comprising following steps: S1: emission performance calibration of a diesel engine and the SCR post-treatment system is finished; S2: a test engine is selected; S3: the stable condition of the test engine is confirmed; S4: the method for verifying urea crystallization of a SCR post-treatment system of transport vehicles by use of a pedestal comprises following steps: it takes 60 hours for verification, wherein the 60 hours are divided in to a 30-hour WHTC suburban and high speed work condition cycle and a 30-hour ETC cycle; a SCR catalytic muffler urea mixing chamber is checked every 10 hours; S 5: the method for verifying urea crystallization of a SCR post-treatment system of urban road vehicles by use of a pedestal comprises following steps: it takes 60 hours for verification, wherein the 60 hours are divided in to a 30-hour WHTC urban work condition cycle and a 30-hour ETC cycle; a SCR catalytic muffler urea mixing chamber is checked every 10 hours; S6: whether the engine passes the verification or not is determined. By use of the method, whether the risk of urea crystallization exists in a post-treatment structure at the early stage of a SCR post-treatment development or not is detected so that timely optimization in the product development process is carried out.
Description
Technical field
The present invention relates to a kind of SCR aftertreatment system urea crystals engine pedestal verification method, especially utilize threst stand quick test SCR aftertreatment system with or without the method that may produce urea crystals, belong to engine SCR exhaust gas aftertreatment system technical field.
Background technology
SCR(SelectiveCatalyticReduction) exhaust treatment system is one of main aftertreatment technologies eliminating oxides of nitrogen in diesel engine vent gas.
The basic functional principle of SCR exhaust treatment system is: tail gas enters the draft tube of SCR exhaust treatment system after booster turbine flows out, simultaneously spray in draft tube by quantitative aqueous solution of urea with vaporific form by the urea-spray unit be arranged in draft tube, aqueous solution of urea comprises spraying into the Main physical chemical change occurred after in exhaust: the atomization of aqueous solution of urea and evaporation of water, urea decomposition generate ammonia and isocyanic acid (HNCO) and isocyanic acid and be hydrolyzed at catalyst surface and generate ammonia etc.But when delivery temperature is lower, have subsidiary reaction in urea decomposition process adjoint, easily generate the polymkeric substance such as cyanuric acid, melamine, thus sediment was formed before exhaust wall and catalyst support, blocking gas outlet or catalyzer duct, cause exhaust back pressure to increase, NO
xtransformation efficiency declines, the dynamic property of engine declines and oil consumption is risen.Time serious, gas exhaust piping or SCR case can be caused all to be blocked, engine can not normally be run.
Along with the integral implementation of diesel vehicle state four regulation, medium and heavy diesel vehicle is all adopt SCR aftertreatment system substantially.Commercially also there is the phenomenon of a large amount of urea crystals in these medium and heavy diesel vehicles of state four at present, all causes certain loss to user and enterprise.Also do not verify in the risk of development to urea crystals in current domestic diesel engine producer, or checking means are single, real road situation can not be reacted, therefore SCR aftertreatment system just cannot be effectively prevented to occur the risk of crystallization on stream, once find large quantities of urea crystals phenomenons to market, bring very large loss will to enterprise and user.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of SCR aftertreatment system urea crystals engine pedestal verification method is provided, can find whether aftertreatment structure exists the risk of urea crystals early stage in SCR aftertreatment research and development, to optimize product structure in time in R & D of complex, product is avoided to introduce the rear loss that urea crystals is brought that occurs to the market.
According to technical scheme provided by the invention, described SCR aftertreatment system urea crystals engine pedestal verification method, is characterized in that, specifically comprise the following steps:
Step S1: make diesel engine and SCR aftertreatment system complete emission behavior before test and demarcate;
Step S2: Selection experiment engine;
Step S3: validation test engine condition is stablized;
Step S4: haulage vehicle SCR aftertreatment system urea crystals stand verification method, specific as follows: to be 60 hours with the SCR aftertreatment system stand proving time, be divided into the WHTC suburb of 30 hours and high-speed working condition to circulate and the ETC of 30 hours circulates, carry out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours;
Step S5: urban road automobile-used SCR aftertreatment system urea crystals stand verification method, specific as follows: to be 60 hours with the SCR aftertreatment system stand proving time, be divided into the WHTC urban conditions circulation of 30 hours and the ETC circulation of 30 hours, carry out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours;
Step S6: judge whether engine is tested by SCR urea crystals according to urea crystals situation.
Further, described step S2: the system of selection of development engine: for the different model diesel engine using the configuration of identical SCR system, when SCR system rise spray temperature consistent, the maximum diesel engine of selective freezing factor of influence τ carries out the checking of SCR system crystallization risk; When SCR rise spray temperature inconsistent, selects lower spray temperature diesel engine test; Described crystallization factor of influence
, wherein, τ is crystallization factor of influence, and Ne is emission testing circulation urea consumption rate, and Pe is engine transient circulation merit.
Further, described step S3: carry out the test of diesel engine external characteristics before test, whether consistent with normal external characteristic curve by external characteristic curve, evaluate diesel engine state and whether stablize.
Further, in described step S4, WHTC suburb and high-speed working condition circulation preparation method are: choose the WHTC 1196s to 1795s that circulates and work out WHTC suburb and high-speed working condition circulates, single cycle time 600s; Rerun 180 times, accumulated running time 30h.
Further, in described step S4, ETC round-robin method is: single cycle time 1800s, reruns 60 times, accumulated running time 30h.
Further, in described step S5, WHTC urban conditions circulation preparation method is: choose the WHTC 311s to 710s that circulates and work out WHTC urban conditions test cycle, single cycle time 400s; Rerun 270 times, accumulated running time 30h.
Further, in described step S6, when meeting following result, then for be tested by SCR urea crystals, then for not pass through when not meeting:
(1) crystalline solid in SCR catalytic muffler urea hybrid chamber region is less than 1cm
3; Or meet,
(2) urea crystals body weight≤5g in SCR catalytic muffler.
Further, when engine is not by the test of SCR urea crystals, then stand demonstration test is re-started after optimizing SCR aftertreatment system.
The present invention has the following advantages:
(1) the present invention utilize engine pedestal fast and effeciently to verify diesel engine post-processing system is with or without urea crystals risk;
(2) stand verification method of the present invention adopts different checking circulations to verify according to the different use of after-treatment system, can verify pointedly, more realistic vehicle service condition;
(3) the present invention utilizes engine pedestal checking SCR urea crystals reproducible, facilitates technician to carry out the improvement of aftertreatment structure and optimization.
Accompanying drawing explanation
Fig. 1 is the process flow diagram of verification method of the present invention.
Embodiment
Below in conjunction with concrete accompanying drawing, the invention will be further described.
As shown in Figure 1, SCR aftertreatment system urea crystals engine pedestal verification method of the present invention, specifically comprises the following steps:
Step S1: the technical conditions of demand fulfillment during on-test, actual conditions is as follows:
(1) before test, diesel engine and SCR aftertreatment system must complete emission behavior demarcation, and data are no longer changed;
(2) SCR spraying system performance meets the demands, and function is normal;
(3) SCR box structure meets drawing requirement, guarantees that design and fabrication exemplar is consistent;
(4) test urea liquid meets the regulation of urea for vehicle solution technique condition;
(5) connection of test-bed upper pipeline need ensure to install consistent with actual vehicle.
Step S2: the system of selection of development engine: for the different model diesel engine using the configuration of identical SCR system, when SCR system rise spray temperature consistent, the maximum diesel engine of selective freezing factor of influence τ carries out the checking of SCR system crystallization risk; If SCR plays spray, temperature is inconsistent, and the diesel engine of lower of prioritizing selection spray temperature is tested; Described crystallization factor of influence
, wherein, τ is crystallization factor of influence, belongs to engine calibration attribute; Ne is emission testing circulation urea consumption rate, and truck, coach calculate according to ETC test cycle, and the city cars such as public transport calculate according to WHTC test cycle; Pe is engine transient circulation merit.
Step S3: the state confirmation of development engine:
The test of diesel engine external characteristics is carried out before test, whether consistent with normal external characteristic curve by external characteristic curve, evaluate diesel engine state and whether stablize.
Step S4: the long-distance transport SCR aftertreatment system urea crystals stand verification methods such as medium and heavy truck, coach, specific as follows:
This type of automobile-used SCR aftertreatment system stand proving time is 60 hours, is divided into the WHTC suburb of 30 hours and high-speed working condition to circulate and the ETC of 30 hours circulates, and carries out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours.
WHTC suburb and high-speed working condition circulation preparation method as follows: choose the WHTC 1196s to 1795s that circulates and work out WHTC suburb and high-speed working condition circulates, single cycle time 600s; Require that this test cycle reruns 180 times, accumulated running time 30h.
ETC round-robin method is as follows: single cycle time 1800s, requires that carrying out this test cycle reruns 60 times, accumulated running time 30h.
Step S5: the urban road automobile-used SCR aftertreatment system urea crystals stand verification methods such as bus, sanitation cart, light truck, specific as follows:
This type of automobile-used SCR aftertreatment system stand proving time is 60 hours, is divided into the WHTC urban conditions circulation of 30 hours and the ETC circulation of 30 hours, carries out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours.
WHTC urban conditions circulation preparation method is as follows: choose the WHTC 311s to 710s that circulates and work out WHTC urban conditions test cycle, single cycle time 400s.Require that this test cycle reruns 270 times, accumulated running time 30h.
Step S6:SCR urea crystals rig test result judges, concrete judgement is as follows:
If meet following result to think that the test of SCR urea crystals is passed through:
(1) SCR catalytic muffler urea hybrid chamber region is without obviously (cumulative volume is less than 1cm
3) crystalline solid;
(2) urea crystals body weight≤5g in SCR catalytic muffler;
(3) there is slight crystallization in SCR catalytic muffler urea hybrid chamber region (cumulative volume is less than 1cm
3) phenomenon, must not judge have rising tendency according to repeatedly opening and inspecting result.
If not enough the above results, then re-start stand demonstration test after needing to optimize SCR system.
The use that the present invention is different according to after-treatment system, is divided into the urban road automobile-used SCR aftertreatment system urea crystals stand verification methods such as long-distance transport SCR aftertreatment system urea crystals stand verification method and bus, sanitation cart, light truck such as medium and heavy truck, coach.The present invention can find whether aftertreatment structure exists urea crystals risk, to optimize product structure in time in R & D of complex, avoids product to introduce the rear loss that urea crystals is brought that occurs to the market in SCR aftertreatment research and development early stage.
Claims (8)
1. a SCR aftertreatment system urea crystals engine pedestal verification method, is characterized in that, specifically comprise the following steps:
Step S1: make diesel engine and SCR aftertreatment system complete emission behavior before test and demarcate;
Step S2: Selection experiment engine;
Step S3: validation test engine condition is stablized;
Step S4: haulage vehicle SCR aftertreatment system urea crystals stand verification method, specific as follows: to be 60 hours with the SCR aftertreatment system stand proving time, be divided into the WHTC suburb of 30 hours and high-speed working condition to circulate and the ETC of 30 hours circulates, carry out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours;
Step S5: urban road automobile-used SCR aftertreatment system urea crystals stand verification method, specific as follows: to be 60 hours with the SCR aftertreatment system stand proving time, be divided into the WHTC urban conditions circulation of 30 hours and the ETC circulation of 30 hours, carry out the inspection of SCR catalytic muffler urea hybrid chamber every 10 hours;
Step S6: judge whether engine is tested by SCR urea crystals according to urea crystals situation.
2. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, it is characterized in that: described step S2: the system of selection of development engine: for the different model diesel engine using the configuration of identical SCR system, when SCR system rise spray temperature consistent, the maximum diesel engine of selective freezing factor of influence τ carries out the checking of SCR system crystallization risk; When SCR rise spray temperature inconsistent, selects lower spray temperature diesel engine test; Described crystallization factor of influence
, wherein, τ is crystallization factor of influence, and Ne is emission testing circulation urea consumption rate, and Pe is engine transient circulation merit.
3. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, it is characterized in that: described step S3: before test, carry out the test of diesel engine external characteristics, whether consistent with normal external characteristic curve by external characteristic curve, evaluate diesel engine state and whether stablize.
4. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, it is characterized in that: in described step S4, WHTC suburb and high-speed working condition circulation preparation method are: choose the WHTC 1196s to 1795s that circulates and work out WHTC suburb and high-speed working condition circulates, single cycle time 600s; Rerun 180 times, accumulated running time 30h.
5. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, it is characterized in that: in described step S4, ETC round-robin method is: single cycle time 1800s, reruns 60 times, accumulated running time 30h.
6. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, it is characterized in that: in described step S5, WHTC urban conditions circulation preparation method is: choose the WHTC 311s to 710s that circulates and work out WHTC urban conditions test cycle, single cycle time 400s; Rerun 270 times, accumulated running time 30h.
7. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 1, be is characterized in that: in described step S6, when meeting following result, then for be tested by SCR urea crystals, then for not pass through when not meeting:
(1) crystalline solid in SCR catalytic muffler urea hybrid chamber region is less than 1cm
3; Or meet,
(2) urea crystals body weight≤5g in SCR catalytic muffler.
8. SCR aftertreatment system urea crystals engine pedestal verification method as claimed in claim 7, is characterized in that: when engine is not by the test of SCR urea crystals, then re-start stand demonstration test after optimizing SCR aftertreatment system.
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Cited By (3)
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| CN106226085A (en) * | 2016-07-22 | 2016-12-14 | 杭州银轮科技有限公司 | Diesel SCR after-treatment system exhaustor urea crystals test method |
| CN112985820A (en) * | 2021-02-08 | 2021-06-18 | 凯龙高科技股份有限公司 | Urea crystallization test method for SCR (Selective catalytic reduction) post-treatment system |
| CN114383849A (en) * | 2021-12-09 | 2022-04-22 | 江铃汽车股份有限公司 | Mixer crystallization experiment method, mixer crystallization experiment device, storage medium and equipment |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110749452B (en) * | 2019-09-29 | 2021-05-07 | 江铃汽车股份有限公司 | Crystallization bench test method for automobile urea mixer |
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