CN117569898A - High-energy urea injection system with premixing function - Google Patents
High-energy urea injection system with premixing function Download PDFInfo
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- CN117569898A CN117569898A CN202311443903.2A CN202311443903A CN117569898A CN 117569898 A CN117569898 A CN 117569898A CN 202311443903 A CN202311443903 A CN 202311443903A CN 117569898 A CN117569898 A CN 117569898A
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- urea
- heat exchange
- aqueous solution
- tank
- cooling liquid
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- 239000004202 carbamide Substances 0.000 title claims abstract description 496
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 title claims abstract description 482
- 238000002347 injection Methods 0.000 title claims abstract description 78
- 239000007924 injection Substances 0.000 title claims abstract description 78
- 239000007864 aqueous solution Substances 0.000 claims abstract description 128
- 239000000110 cooling liquid Substances 0.000 claims abstract description 97
- 238000002156 mixing Methods 0.000 claims abstract description 32
- 239000003054 catalyst Substances 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 11
- 238000010438 heat treatment Methods 0.000 claims description 45
- 239000007788 liquid Substances 0.000 claims description 45
- 238000005485 electric heating Methods 0.000 claims description 33
- 239000000243 solution Substances 0.000 claims description 29
- 238000005086 pumping Methods 0.000 claims description 15
- 239000000498 cooling water Substances 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 13
- 239000007921 spray Substances 0.000 claims description 13
- 238000005507 spraying Methods 0.000 claims description 9
- 238000011144 upstream manufacturing Methods 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 8
- 239000003638 chemical reducing agent Substances 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 238000009835 boiling Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 5
- 230000000694 effects Effects 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 238000010257 thawing Methods 0.000 claims description 3
- WTHDKMILWLGDKL-UHFFFAOYSA-N urea;hydrate Chemical compound O.NC(N)=O WTHDKMILWLGDKL-UHFFFAOYSA-N 0.000 claims description 3
- 239000000284 extract Substances 0.000 claims description 2
- 239000000295 fuel oil Substances 0.000 claims description 2
- 238000002425 crystallisation Methods 0.000 abstract description 4
- 230000008025 crystallization Effects 0.000 abstract description 4
- 238000000354 decomposition reaction Methods 0.000 abstract description 2
- 238000002360 preparation method Methods 0.000 abstract 1
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 37
- 239000007789 gas Substances 0.000 description 28
- 239000002826 coolant Substances 0.000 description 23
- 238000002372 labelling Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000007062 hydrolysis Effects 0.000 description 4
- 238000006460 hydrolysis reaction Methods 0.000 description 4
- 238000010992 reflux Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 239000004215 Carbon black (E152) Substances 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000001960 triggered effect Effects 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- UHZZMRAGKVHANO-UHFFFAOYSA-M chlormequat chloride Chemical compound [Cl-].C[N+](C)(C)CCCl UHZZMRAGKVHANO-UHFFFAOYSA-M 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000009982 effect on human Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000012774 insulation material Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 238000005381 potential energy Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 150000003672 ureas Chemical class 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/18—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control
- F01N3/20—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by methods of operation; Control specially adapted for catalytic conversion ; Methods of operation or control of catalytic converters
- F01N3/2066—Selective catalytic reduction [SCR]
- F01N3/208—Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N2610/00—Adding substances to exhaust gases
- F01N2610/02—Adding substances to exhaust gases the substance being ammonia or urea
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Abstract
The invention relates to a high-energy urea injection system with a premixing function. The system comprises an engine, a heat exchange tank, a urea pump, a urea injection unit, an aftertreatment system and an SCR catalyst. The engine is connected with a heat exchange tank pipeline, and the heat exchange tank is used for exchanging heat of engine cooling liquid to urea aqueous solution, so that the urea aqueous solution in the storage tank is heated, and the rest urea aqueous solution is stored. The engine, the aftertreatment system and the SCR catalyst are connected in sequence, and the aftertreatment system comprises a DOC and a DPF system. Compared with the prior art, the invention can efficiently and rapidly convert urea aqueous solution into a high-temperature high-pressure state, effectively shorten the preparation time required by the SCR system to reach the working state, effectively promote the efficient decomposition and uniform mixing of urea sprayed into the system, reduce the requirement of the spraying-mixing system on the arrangement space, improve the SCR conversion efficiency and greatly reduce the risk of urea crystallization.
Description
Technical Field
The invention relates to the technical field of emission control of motor vehicles, in particular to a high-energy urea injection system with a premixing function.
Background
As one of the main sources of air pollution, NO emitted by diesel engines x (NO and NO) 2 ) Can cause environmental damage such as acid rain, photochemical smog, greenhouse effect, ozone layer cavity and the like, and has adverse effect on human health. The exhaust system of a diesel engine is in an oxygen-rich environment, and is currently used for NO under the lean combustion condition of the diesel engine x The purification technique is mainly selective catalyst reduction (Selective Catalytic Reduction, SCR), which can use HC, NH 3 And H 2 Etc. as reducing agents for NOx, the most common use of the Urea-SCR technology in road diesel engines has been the technology of injecting an aqueous Urea solution into exhaust gas having a certain temperature, and utilizing ammonia (NH) generated by hydrolysis and pyrolysis of Urea 3 ) Under the action of catalyst, nitrogen Oxides (NO) x ) Conversion to Nitrogen (N) 2 )。
The climate difference between the north and south of China is huge, the winter temperature in the northern area can reach below minus 35 ℃, the environment with such low temperature can not only lead to freezing of urea solution and failure of urea injection by SCR system, but also lead to low exhaust temperature of vehicles running under the environment, and the temperatures required by evaporation, pyrolysis and hydrolysis of urea aqueous solution are difficult to be reached. NO of diesel engine x The emission occupies NO of the automobile x Over 80% of total emissions, NO at the cold start stage due to the failure of the SCR system x The emissions account for more than 50% of the overall driving cycle, thus shortening the time for the system to reach SCR reaction conditions can effectively reduce cold start NOx emissions.
The water content in the urea solution accounts for 67.5%, and because of the large specific heat capacity of water, when the injected urea solution is mixed with exhaust gas, a large part of exhaust gas energy can be used for heating the water to the boiling point, and meanwhile, the water can absorb a large amount of heat when undergoing liquid-gas phase transition, so that the temperature of the injected SCR system is obviously reduced, the SCR catalytic system is not easy to quickly enter a high-efficiency conversion temperature window, and the risk of urea crystallization is greatly increased.
Aiming at the problems existing in the existing SCR system, a more optimal urea injection system design scheme is needed to be provided, and the design of a diesel vehicle urea system can be optimized.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a high-energy urea injection system with a premixing function, and the design of a small-size heat exchange tank, a liquid storage cavity and an electric heating urea pipe and the arrangement of a venturi pipe with a through hole at the tail end of a premixing urea nozzle enable the heating efficiency of urea aqueous solution to be higher, so that the whole SCR system can be in a working state quickly, the SCR conversion efficiency can be improved, and the risk of urea crystallization can be reduced.
The aim of the invention can be achieved by the following technical scheme:
the invention provides a high-energy urea injection system with a premixing function, which comprises an engine, a heat exchange tank, a urea pump, a urea injection unit, a post-treatment system and an SCR catalyst, wherein the heat exchange tank is arranged in the urea tank;
the engine is connected with the heat exchange tank pipeline and is used for converting chemical energy of fuel into mechanical energy so as to provide driving power for the vehicle and generate exhaust;
the heat exchange pool is used for exchanging heat of engine cooling liquid to urea aqueous solution, heating the urea aqueous solution in the storage pool and storing the rest urea aqueous solution;
the heat exchange tank is connected with the urea tank through a urea pipe, and the urea tank is used for storing urea aqueous solution required by the operation of the SCR system and thawing and heating the urea aqueous solution through a heating resistance wire in a low-temperature environment;
the urea pump is connected with the heat exchange tank through a urea pipe, and is used for pumping urea out of the urea tank and pressurizing the urea, then conveying the urea into the exhaust pipe through the urea injection unit to be mixed with exhaust gas for reaction, and simultaneously pumping the residual solution in the urea injection unit back to the heat exchange tank or the urea tank;
the engine, the aftertreatment system and the SCR catalyst are connected in sequence, and the aftertreatment system comprises a DOC and a DPF system;
the SCR catalyst is used for spraying reducing agent to make NO in exhaust gas under the action of catalyst x Reduction to N 2 And H 2 O。
Further, the device also comprises a cooling water pump, a cooling liquid electromagnetic valve, a back-pumping pump and a mixer;
the cooling water pump is arranged between the engine and the heat exchange tank and is used for providing flow energy for cooling liquid to enter and exit the heat exchange tank;
the cooling liquid electromagnetic valve is arranged between the engine and the heat exchange tank and is used for controlling engine cooling liquid to enter the heat exchange tank so as to enable the engine cooling liquid to exchange heat with urea solution;
the reverse pumping pump is arranged between the heat exchange tank and the urea tank, and is used for pumping the redundant urea aqueous solution in the heat exchange tank, all urea pipes and the residual urea aqueous solution in the urea injection unit back to the urea tank together with the urea pump after the engine stops working;
the mixer is arranged on one side of the SCR catalyst and is used for further uniformly mixing exhaust gas and urea aqueous solution spray.
Further, the urea injection unit comprises a urea pipe interface, a positioning fixing hole, an injection valve, an electrical interface and a pre-mixed urea nozzle, wherein the urea pipe interface is connected with a urea pipe and is used for introducing urea pressurized by a urea pump into the injection unit;
the positioning fixing hole is used for fixing the urea injection unit at a target position in the aftertreatment system;
the injection valve is arranged in the urea injection unit, is used for executing an injection command of a DCU (distributed control unit), and is opened and closed according to a certain duty ratio to control the injection rate;
the electrical interface is used for connecting the DCU to control the premixed urea nozzle;
the pre-mixing urea nozzle comprises a pre-mixing urea nozzle body, wherein the pre-mixing urea nozzle is of a venturi tube structure, and further comprises a urea spray inlet arranged at the upper end of the pre-mixing urea nozzle body, a pre-mixing outlet arranged at the lower end of the pre-mixing urea nozzle body and an exhaust inlet arranged at the middle side edge of the pre-mixing urea nozzle body, wherein the pre-mixing urea nozzle is used for spraying atomized urea solution, and the urea and air mixture pumped by urea pump smoothly flow into an exhaust pipe to uniformly atomize the sprayed urea.
Further, the urea injection unit further comprises a cooling liquid inlet pipe and a cooling liquid inlet pipe, wherein the cooling liquid inlet pipe and the cooling liquid inlet pipe are used for introducing circulated cooling liquid and cooling the premixed urea nozzle, so that the premixed urea nozzle is prevented from being overheated and failing under the high-temperature discharge condition.
Further, the heat exchange tank comprises a shell main body, wherein a urea aqueous solution heat exchange tube, a cooling liquid guide plate, an electric heating disc and a liquid storage cavity are sequentially arranged in the shell main body;
the cooling liquid guide plate is used for providing a guiding effect for the cooling liquid flowing into the heat exchange tank, so that the cooling liquid can obtain longer heat exchange time and higher heat exchange efficiency;
the urea aqueous solution heat exchange tube is used for physically isolating the urea aqueous solution and the cooling liquid, and the heat exchange process of the urea aqueous solution and the cooling liquid is realized through the heat conduction property of the material of the heat exchange tube;
the electric heating disc is arranged in the liquid storage cavity and is used for heating urea aqueous solution in the liquid storage cavity;
the liquid storage cavity is used for storing urea aqueous solution heated by cooling water, so that partial urea aqueous solution can be ensured to enter a working state quickly all the time in the heat exchange tank.
Further, the device also comprises a temperature sensor and NO x A sensor and a pressure sensor;
the temperature sensor is respectively arranged at the outlet of the cooling water pump, the outlet of the urea tank, the outlet of the heat exchange tank and the inlet of the pre-mixed urea nozzle and is used for detecting the temperature of the aqueous solution;
the temperature sensor is also arranged at an engine outlet, an SCR inlet and an SCR outlet and used for detecting the gas temperature;
the NO x The sensor is respectively arranged at the engine outlet and the SCR outlet and is used for detecting NO of outlet exhaust gas x Concentration;
the pressure sensor is respectively arranged at the outlet of the urea pump and the inlet of the SCR and is used for detecting the pressure of the urea aqueous solution at the outlet and the exhaust pressure;
the urea tank is also provided with a urea quality sensor and a urea liquid level sensor, and the urea quality sensor is used for detecting the concentration of urea aqueous solution in the urea tank; the urea liquid level sensor is used for detecting the liquid level of the urea aqueous solution in the urea tank.
Further, a urea aqueous solution inlet is formed in the top of the heat exchange tank shell main body, a cooling liquid outlet channel is formed in one side of the upper end of the shell main body, a cooling liquid inlet channel is formed in one side of the lower end of the shell main body, a urea tank reflux port is formed below the cooling liquid inlet channel, a urea aqueous solution outlet is formed in the bottom of the shell, and a temperature sensor is arranged on the cooling liquid inlet channel;
the cooling liquid inlet channel, the cooling liquid outlet channel, the urea aqueous solution inlet and the urea aqueous solution outlet are used for providing an aqueous solution circulation channel;
the urea tank backflow port is arranged at the upper part of the liquid storage cavity and is used for providing a channel for the urea aqueous solution in the heat exchange tube to flow back to the urea tank after the SCR stops working so as to avoid low-temperature icing blockage and damage to the heat exchange tube;
the temperature sensor is used for detecting the temperature of the cooling liquid and the urea.
Further, the urea pipe comprises an electric heating urea pipe and a common urea pipe, the electric heating urea pipe is arranged at the upstream of the urea pump and the downstream of the urea pump, and the electric heating urea pipe at the upstream of the urea pump is used for heating the urea aqueous solution in the pipe to a near boiling state;
the electric heating urea pipe at the downstream of the urea pump is used for heating the urea solution pressurized by the urea pump to a superheated state and conveying the heated and pressurized urea solution to the pre-mixing urea nozzle.
Further, after the engine is started, the high-energy urea injection system carries out heating judgment on the urea temperature in the urea tank, so that the repeated action of the heating system is prevented, and the method specifically comprises the following steps:
when the temperature of the urea tank is higher than the set temperature T1, opening an electromagnetic valve between the urea tank and the heat exchange tank to enable urea aqueous solution to flow into the heat exchange tank;
when the temperature of the cooling liquid at the inlet of the heat exchange tank is higher than the set temperature T2, a cooling liquid electromagnetic valve at the upstream of the heat exchange tank is opened, and the engine cooling liquid enters the heat exchange tank through a cooling liquid inlet channel of the heat exchange tank and exchanges heat with the low-temperature urea water solution in the heat exchange pipe.
Further, after the engine is started, the high-energy urea injection system further carries out heating judgment on the urea temperature in the liquid storage cavity, and specifically comprises the following steps:
when the temperature of urea in the liquid storage cavity is higher than the target temperature T3, the urea pump extracts urea from the heat exchange tank, pressurizes the urea and sends the urea to the electric heating urea pipe, the electric heating urea pipe controls heating power through a feedback value of a temperature sensor at an inlet of a pre-mixing urea nozzle, the pressurized urea is further heated to the target temperature T4 and then is sent to the urea injection unit, and the urea injection unit pre-mixes urea spray and exhaust gas at a throat pipe and then enters an exhaust system.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. according to the invention, through the design of the small-size heat exchange tank, the liquid storage cavity and the electric heating urea pipe, energy is efficiently used for heating urea aqueous solution needing to be sprayed into an exhaust system, so that the problem of low energy efficiency caused by a rough heating mode that the urea aqueous solution of the whole urea tank is heated by a traditional urea supply system is avoided; the urea water solution heating efficiency is higher, the time for the reducing agent supply system to reach the working state is shorter, and the whole SCR system can quickly enter the working state in the cold start stage.
2. According to the invention, efficient primary heating is realized through the electric heating disc in the liquid storage cavity of the heat exchange tank, then the urea aqueous solution after primary heating is pressurized through the urea pump to raise the boiling point of the urea aqueous solution, and further secondary heating of the urea aqueous solution is finished through the electric heating urea pipeline at the downstream of the urea pump, so that the urea solution enters a high-pressure overheat state before injection, and the urea aqueous solution has very high internal energy. This high energy state may create better phase and energy conditions for the premixing process, evaporation process, pyrolysis process, and hydrolysis process that follow.
3. According to the invention, the venturi tube with the through hole is arranged at the tail end of the pre-mixing urea nozzle, so that the rapid pre-mixing of urea aqueous solution spraying and exhaust is realized. The design can effectively promote efficient evaporation and decomposition of urea aqueous solution before being sprayed into the system, and compared with a traditional spraying mode, the spraying of the premixing nozzle has better mixing uniformity before entering the mixer, so that the requirement of the spraying-mixing system on arrangement space is reduced, the SCR conversion efficiency is improved, and the risk of urea crystallization is greatly reduced.
Drawings
FIG. 1 is an overall schematic diagram of a high-energy urea injection system with premixing function;
FIG. 2 is a schematic diagram of a control unit of the SCR system in embodiment 1;
FIG. 3 is an overall schematic diagram of the heat exchange cell of example 1;
FIG. 4 is a schematic diagram showing the structure of a urea injection unit in example 1;
FIG. 5 is an overall schematic of the premix urea nozzle of example 1;
fig. 6 shows a heating control method of the high-energy urea injection system having the premixing function in example 1.
Labeling in fig. 1:
1-engine, 2-heat exchange tank, 3-urea tank, 4-urea pump, 5-aftertreatment system, 6-SCR catalyst, 7-cooling water pump, 8-solenoid valve, 9-back pump, 10-premixed urea nozzle, 11-mixer, 12-engine outlet NOx sensor, 13-engine outlet temperature sensor, 14-heat exchange tank outlet temperature sensor, 15-electrically heated urea pipe, 16-urea pump outlet pressure sensor, 17-nozzle inlet temperature sensor, 18-urea tank temperature sensor, 19-urea quality sensor, 20-urea level sensor, 21-SCR inlet pressure sensor, 22-SCR inlet temperature sensor, 23-SCR outlet temperature sensor, 24-SCR outlet NOx sensor, 25-coolant temperature sensor;
labeling in fig. 2:
a 26-SCR control unit;
labeling in fig. 3:
201-urea aqueous solution inlet, 202-urea aqueous solution heat exchange tube, 203-coolant temperature sensor, 204-coolant inlet channel, 205-urea tank reflux port, 206-urea aqueous solution outlet, 207-urea temperature sensor, 208-liquid storage cavity, 209-electric heating disk, 210-coolant guide plate, 211-coolant outlet channel;
labeling in fig. 4 illustrates:
10-premixing urea nozzle, 27-cooling liquid outlet pipe, 28-cooling liquid inlet pipe, 29-urea pipe interface, 30-electrical interface, 31-positioning fixing hole and 32-injection valve;
labeling in fig. 5:
1001-urea spray inlet, 1002-exhaust inlet, 1003-premix outlet.
Detailed Description
The following describes in detail specific embodiments of the present invention by way of examples, which are given as detailed embodiments and specific operation procedures based on the embodiments of the present invention, but the scope of the present invention is not limited to the examples described below.
The invention will be further elucidated with reference to the drawings and the specific embodiments. Features such as component model, material name, connection structure and the like which are not explicitly described in the technical scheme are all regarded as common technical features disclosed in the prior art.
Example 1
The present embodiment provides a high-energy urea injection system with a premixing function, which is schematically shown in fig. 1, and includes an engine 1, a coolant inlet pipe, a coolant return pipe, a coolant pump 7, a coolant solenoid valve 8, a heat exchange tank 2, a coolant inlet temperature sensor 25, an electrically heated urea tank 3, a urea tank temperature sensor 18, a urea quality sensor 19, a urea liquid level sensor 20, a urea pipe 15, a reverse pump 9, a heat exchange tank outlet temperature sensor 14, a urea pump 4, a urea pump outlet pressure sensor 16, a premixing urea nozzle 10, a nozzle inlet temperature sensor 17, an engine exhaust pipe, an aftertreatment system 5, a mixer 11, an SCR, an engine outlet temperature sensor 13, an engine outlet NOx sensor 12, an SCR inlet temperature sensor 22, an SCR inlet pressure sensor 21, an SCR outlet temperature sensor 23, and an SCR outlet NOx sensor 24, and further includes an SCR control unit 26, as shown in fig. 2.
The engine 1 is connected with the heat exchange tank 2 through a pipeline, and the engine 1 is used for converting chemical energy of fuel oil into mechanical energy to provide driving power for a vehicle and generate exhaust; the outlet of the engine 1 is provided with a temperature sensor and a NOx sensor, and the engine outlet temperature sensor 13 is used for detecting the temperature of gas discharged by the engine outlet; the engine outlet NOx sensor 12 is for detecting the NOx concentration of the engine outlet exhaust gas; the heat exchange tank 2 is used for exchanging heat of the cooling liquid of the engine 1 to the urea aqueous solution, heating the urea aqueous solution in the storage tank is achieved, and the rest urea aqueous solution is stored.
The heat exchange tank 2 is connected with the urea tank 3 through a urea pipe, and the urea tank 3 is used for storing urea aqueous solution required by the operation of the SCR system, and thawing and heating the urea aqueous solution through a heating resistance wire in a low-temperature environment of-11 ℃ and below; the urea tank 3 is provided with a urea tank 3 temperature sensor for detecting the temperature of the urea aqueous solution in the urea tank 3; a urea quality sensor 19 for detecting the concentration of the urea aqueous solution in the urea tank 3; a urea level sensor 20 for detecting the urea aqueous solution level in the urea tank 3. The urea pump 4 is connected with the heat exchange tank 2 through a urea pipe, the urea pump 4 is used for pumping urea out of the urea tank 3 and pressurizing the urea, then the urea is conveyed into the exhaust pipe through the urea injection unit to be mixed with exhaust gas for reaction, and meanwhile, the residual solution in the urea injection unit is pumped back to the heat exchange tank 2 or the urea tank 3. The outlet of the urea pump 4 is provided with a pressure sensor for detecting the pressure of the urea aqueous solution at the outlet of the urea pump 4; the urea pipe is used for providing a flow channel for the urea aqueous solution to enter and exit the urea tank 3 and the heat exchange tank 2.
The engine 1, the aftertreatment system 5 and the SCR catalyst 6 are connected in sequence, and the aftertreatment system 5 comprises a DOC and a DPF device; the DOC device is used for oxidizing gases such as carbon monoxide (CO), hydrocarbon (HC) and the like in exhaust gas of the exhaust pipe and converting the gases into harmless CO 2 And H 2 O, and convert NO to NO 2 The method comprises the steps of carrying out a first treatment on the surface of the DPF devices are used to capture particulate emissions from the atmosphere before they enter the atmosphereWhile reducing exhaust emissions of particulate matter. When the device captures the particulate matters, the captured particulate matters are oxidized and digested, so that the DPF is regenerated.
The cooling liquid inlet pipe is used for providing a circulation channel for the cooling liquid of the engine 1 to enter the heat exchange tank 2; and the cooling liquid return pipe is used for providing a circulation channel of the cooling liquid in the heat exchange tank 2 for returning to the engine 1. The cooling water pump 7 is arranged between the engine 1 and the heat exchange tank 2, and the cooling water pump 7 is used for providing flow energy for cooling liquid to enter and exit the heat exchange tank 2; the cooling liquid electromagnetic valve 8 is arranged between the engine 1 and the heat exchange tank 2, and the cooling liquid electromagnetic valve 8 is used for controlling cooling liquid of the engine 1 to enter the heat exchange tank 2 so as to enable the cooling liquid of the engine 1 to exchange heat with urea solution; a coolant temperature sensor 203 is provided at the inlet of the heat exchange tank 2 for detecting the temperature of the coolant entering the heat exchange tank 2.
The reverse pumping pump 9 is arranged between the heat exchange tank 2 and the urea tank 3, and the reverse pumping pump 9 is used for pumping the redundant urea aqueous solution in the heat exchange tank 2, all urea pipes and the residual urea aqueous solution in the urea injection unit back to the urea tank 3 together with the urea pump 4 after the engine 1 stops working; the outlet of the heat exchange tank is provided with a urea temperature sensor 207 for detecting the temperature of the urea aqueous solution at the outlet of the heat exchange tank.
An electric heating urea pipe is arranged at the upstream and downstream of the urea pump respectively, wherein the electric heating urea pipe at the upstream of the urea pump is used for heating the urea aqueous solution in the urea pipe to a near boiling state; the urea pump downstream electrically heated urea pipe is used to heat the urea solution pressurized by the urea pump 4 to a superheated state and to deliver the heated pressurized urea solution to the pre-mixed urea nozzle 10 in the urea injection unit.
A mixer 11 is provided on one side of the SCR catalyst 6, said mixer 11 being used for further mixing the exhaust gas and the urea aqueous solution spray. The SCR catalyst 6 is used for reducing NOx in exhaust gas to N by the injected reducing agent under the action of the catalyst 2 And H 2 O. An SCR inlet temperature sensor 22 is provided at the inlet of the SCR catalyst 6 for detecting the exhaust gas temperature at the SCR inlet, which together with the SCR outlet temperature sensor measurement is used for calculating the catalyst carrier temperature; the inlet of the SCR catalyst 6 is also provided with an SCR inlet pressure sensor21 for detecting the exhaust pressure at the SCR inlet for evaluating the pressure drop magnitude of the system at this point; an SCR outlet temperature sensor 23 is arranged at the outlet of the SCR catalyst 6 for detecting the exhaust temperature at the SCR outlet, which is used together with the SCR inlet temperature sensor measurement for calculating the catalyst carrier temperature; the outlet of the SCR catalyst 6 is also provided with an SCR outlet NO x A sensor 24 for detecting NO in the SCR outlet exhaust x Concentration.
The structure of the heat exchange tank 2 is shown in fig. 3, the heat exchange tank 2 comprises a shell main body, and a urea aqueous solution heat exchange tube 202, a cooling liquid guide plate 210, an electric heating disc 209 and a liquid storage cavity 208 are sequentially arranged in the shell main body. The top of the heat exchange tank 2 shell main body is provided with a urea aqueous solution inlet 201, one side of the upper end of the shell main body is provided with a cooling liquid outlet channel 211, and one side of the lower end of the shell main body is provided with a cooling liquid inlet channel 204. A urea tank backflow port 205 is arranged below the cooling liquid inlet channel 204, a urea aqueous solution outlet 206 is arranged at the bottom of the shell, and a temperature sensor is arranged on the cooling liquid inlet channel 204.
The coolant inlet channel 204 is used for providing a circulation channel for the coolant into the heat exchange tank 2; the coolant deflector 210 is used to provide a guiding effect for the coolant flowing into the heat exchange tank 2 so that it can flow through the cooling tank in a longer path for a longer heat exchange time and a higher heat exchange efficiency; the coolant outlet channel 211 is used for providing a flow channel for the coolant to flow out of the heat exchange cell 2; the coolant temperature sensor 203 is configured to detect the temperature of the coolant entering the heat exchange tank 2, and close the electromagnetic valve 8 when the temperature of the coolant is low.
The urea aqueous solution inlet 201 is used for providing a flow channel for the urea aqueous solution to enter the heat exchange tank 2; the urea aqueous solution outlet 206 is used for providing a flow channel for the urea aqueous solution to flow out of the heat exchange tank 2; the urea solution heat exchange tube 202 is used for physically isolating the urea solution from the cooling liquid, and realizes the heat exchange process of the urea solution heat exchange tube and the cooling liquid through the heat conduction property of the material, and generally adopts a high heat conduction coefficient material with urea corrosion resistance; the urea temperature sensor 207 is used for detecting the urea temperature at the outlet of the urea aqueous solution and providing a control feedback signal of the heating power of the heating plate.
The liquid storage cavity 208 is used for storing the urea aqueous solution heated by the cooling water, so that partial urea aqueous solution can be ensured to enter a working state quickly all the time in the heat exchange tank 2; the electric heating plate 209 is used for heating the urea aqueous solution in the liquid storage cavity 208, and the heating target of the liquid in the cavity can be rapidly completed under the cold start condition because the total amount of the urea aqueous solution is less; the urea tank backflow port 205 is generally disposed at a higher position of the liquid storage cavity 208, and is used for providing a channel for the urea aqueous solution in the heat exchange tube to flow back to the urea tank 3 after the SCR stops working, so as to avoid low-temperature icing blockage and damage to the heat exchange tube.
The working principle of the heat exchange tank 2 is as follows: the high-temperature cooling liquid enters the heat exchange tank 2 through the cooling liquid inlet channel 204, flows to the upper cooling liquid outlet 211 through a longer flow path under the action of the cooling liquid guide plate 210, meanwhile, the low-temperature urea aqueous solution enters from the urea aqueous solution inlet 201 above the heat exchange tank 2 and flows to the liquid storage cavity 208 below along the densely distributed urea aqueous solution heat exchange pipes 202, and the low-temperature urea aqueous solution and the high-temperature cooling liquid exchange heat through the pipe walls of the heat exchange pipes in the flowing process, so that the temperature of the urea aqueous solution is increased. The heat exchange tank 2 is externally wrapped by heat insulation materials.
An electric heating plate 209 is arranged in the liquid storage cavity 208, when the urea temperature sensor 207 detects that the temperature of the urea aqueous solution in the liquid storage cavity 208 is insufficient, the electric heating plate 209 is triggered to heat, and after the urea aqueous solution is heated to the target temperature, the electromagnetic valve 8 below is opened, so that the passage of the urea aqueous solution into the urea pump 4 is opened.
The urea tank reflux port 205 is arranged at the higher position of the liquid storage cavity 208, the reverse pumping pump 9 does not work under the normal working state of SCR, the whole height of the heat exchange tank 2 is lower than the bottom of the urea tank 3, the liquid in the liquid storage cavity 208 cannot reflux to the urea tank 3, and the heated energy is ensured to be fully endowed with urea aqueous solution to be injected into an exhaust system.
The urea injection unit is shown in fig. 4 and comprises a coolant outlet pipe 27, a coolant inlet 28, a urea pipe interface 29, an electrical interface 30, a positioning and fixing hole 31, an internal injection valve 32 and a pre-mixed urea nozzle 10.
The urea pipe interface 29 is used for introducing urea pressurized by the urea pump 4 into the injection unit; the cooling liquid inlet pipe 28 and the cooling liquid outlet pipe 27 are used for introducing circulated cooling liquid to cool the premixed urea nozzle 10, so that the premixed urea nozzle 10 is prevented from being overheated and malfunctioning under the high-temperature exhaust condition; the electrical interface 30 is used to connect the DCU to control the premixed urea nozzle 10; the positioning fixing hole 31 is used for fixing the urea injection unit at a target position of the aftertreatment system 5; the internal injection valve 32 performs an injection command of the DCU to be opened and closed at a certain duty ratio to control an injection rate; the pre-mix urea nozzle 10 is used to achieve pre-mixing of urea solution with exhaust gas.
As shown in fig. 5, the structure of the premixing nozzle is schematically shown in fig. 5, the premixing urea nozzle 10 comprises a premixing urea nozzle body, the premixing urea nozzle is in a venturi tube structure, and further comprises a urea spray inlet 1001 arranged at the upper end of the premixing urea nozzle body, a premixing outlet 1003 arranged at the lower end of the premixing urea nozzle body, and an exhaust inlet 1002 arranged at the middle side of the premixing urea nozzle body, wherein the premixing urea nozzle 10 is used for spraying atomized urea solution, and smoothly spraying urea and air mixture sent by the urea pump 4 into the exhaust pipe, so that the sprayed urea is uniformly atomized. Since the pressure in the urea pipe 15 is high, the pressure potential energy of the urea aqueous solution is quickly converted into kinetic energy after the injection valve 32 is opened, the flow rate of the urea spray is quickly increased, the pressure is reduced to a level basically consistent with the pressure in the exhaust pipe, and then the urea spray enters the tapering part of the venturi pipe, at this time, the flow rate is further increased due to the reduction of the cross-sectional area, the greater the flow rate, the smaller the pressure, the maximum flow rate and the minimum pressure are provided in the throat pipe part, the pressure is lower relative to the gas pressure in the exhaust pipe, and the exhaust gas is sucked into the premixing nozzle through an opening at the throat pipe of the venturi pipe, and is primarily premixed with the urea spray.
As shown in fig. 6, the heating control method of the high-energy urea injection system with the mixing function can judge whether the system needs to be started for heating after each time the engine 1 is started, so that the repeated action of the heating system is prevented.
When the engine 1 is detected to be in a working state, the cooling liquid temperature sensor 203 detects the temperature of the cooling liquid of the engine 1 in real time, the temperature sensor of the urea tank 3 detects the temperature of the electrically heated urea tank 3, and the temperature sensor of the liquid storage cavity 208 detects the temperature of the urea aqueous solution in the liquid storage cavity 208; the ECU of the engine 1 judges whether the state of the engine 1, the electric heating urea tank 3 and the electric heating disk 209 of the liquid storage cavity 208 need to be heated according to the detection values of the cooling liquid temperature sensor 203 at the inlet of the heat exchange tank, the temperature sensor of the urea tank 3 and the temperature sensor of the liquid storage cavity 208.
When the temperature of the urea tank 3 is lower than T1, the electric heating function of the urea tank 3 is started to ensure that the urea aqueous solution in the urea tank 3 is in a liquid state with a good flowing state, once the temperature of the urea aqueous solution is detected to exceed T1, heating is stopped to save electric energy, and meanwhile, the electromagnetic valve 8 between the urea tank 3 and the heat exchange tank 2 is opened, so that the urea aqueous solution with the temperature higher than 7 ℃ can flow into the heat exchange tank 2; when the temperature of the cooling liquid is higher than a certain set threshold value T2, the cooling liquid electromagnetic valve 8 is opened, at the moment, the cooling liquid of the engine 1 enters the heat exchange tank 2 through the cooling liquid inlet channel 204 of the heat exchange tank 2 and exchanges heat with the low-temperature urea aqueous solution in the heat exchange pipe, and when the temperature of the cooling liquid is lower than the certain set threshold value T2, the cooling liquid can provide limited heat, and the rapid warming-up of the engine 1 body is not facilitated, at the moment, the cooling liquid electromagnetic valve 8 is closed, so that the cooling liquid electromagnetic valve fully absorbs the heat of the engine 1 in a small cycle.
If the detection value of the temperature sensor of the liquid storage cavity 208 is lower than a certain set threshold value T3, the electric heating disc 209 in the liquid storage cavity 208 continuously works to heat the urea aqueous solution in the liquid storage cavity 208, when the detection value of the temperature sensor of the liquid storage cavity 208 is higher than the certain set threshold value T3, the urea pump 4 starts to work, urea is extracted from the heat exchange tank 2 and pressurized and then is sent to the electric heating urea pipe, the electric heating urea pipe controls the heating power through the feedback value of the temperature sensor at the inlet of the urea nozzle 10, the pressurized urea is further heated to the target temperature T4 and then is sent to the urea injection unit, the urea injection unit pre-mixes the urea spray and the exhaust gas at the throat through a unique venturi structure, then enters the exhaust system, and NOx in the exhaust gas is reduced to N through the subsequent SCR catalyst 6 2 And H 2 O, and willThe purified exhaust gas is discharged into the air.
In this example, the reducing agent was an aqueous urea solution having a mass concentration of 32.5%.
When the ambient temperature is lower than the freezing point of the urea aqueous solution, the urea aqueous solution in the urea tank 3 is generally in a solid state during cold starting of the vehicle, and after the vehicle is electrified, the electric heating function of the urea tank 3 needs to be activated to help the urea aqueous solution to defrost; the thawed urea solution flows into the heat exchange tank 2 from the bottom of the urea tank 3, and the heat exchange tank 2 lifts the temperature of the urea aqueous solution entering the tank through two ways: firstly, heating urea aqueous solution by cooling liquid; secondly, the urea aqueous solution after heat exchange is heated in the heat exchange tank through the self-contained electric heating function of the heat exchange tank 2; after the urea aqueous solution in the heat exchange tank 2 is heated to the target temperature, a signal of the reducing agent supply state OK of the SCR system is sent to the DCU, once the signal value of an exhaust temperature sensor at the upstream of the SCR is larger than a reducing agent start-up and injection temperature set threshold value, an injection request of the urea aqueous solution is triggered, at the moment, the urea pipeline electromagnetic valve 8 is opened, the urea pump 4 begins to pay, and meanwhile, a urea pipe with a heating function adjusts heating power according to the urea aqueous solution temperature at the outlet of the heat exchange tank 2, so that the urea aqueous solution in the urea pipeline can be heated to an overheat state before reaching the outlet of a nozzle under the current injection rate request.
The temperature in the overheat state is higher than the boiling point under the current exhaust pressure and lower than the boiling point under the pressure in the rear pipe of the current urea pump 4, and the median value of the two is taken in the embodiment; wherein the exhaust gas pressure is measured by the SCR inlet pressure sensor 21; the pressure in the back pipe of the urea pump 4 is measured by a pressure sensor arranged between the urea pump 4 and the pre-mixed urea nozzle 10.
After the pressure in the pipe reaches the target injection pressure, the premixed urea nozzle 10 is opened and urea aqueous solution is injected into the exhaust pipe, and part of exhaust gas can be sucked into the venturi throat of the premixed urea nozzle 10 due to the special structural design of the nozzle, so that the premixing with the urea aqueous solution is realized; at the same time, the pressure drops rapidly after the nozzle is opened, the overheated urea aqueous solution evaporates rapidly to become a gaseous state, and the hydrolysis and the thermal interaction with the high-temperature exhaust gas are completedPyrolysis reaction to generate NH 3 After further mixing by the mixer 11, enters the SCR catalyst 6 and NO x Chemical reaction occurs to realize NO elimination x Is a target of (a).
The previous description of the embodiments is provided to facilitate a person of ordinary skill in the art in order to make and use the present invention. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. The high-energy urea injection system with the premixing function is characterized by comprising an engine (1), a heat exchange tank (2), a urea tank (3), a urea pump (4), a urea injection unit, an aftertreatment system (5) and an SCR catalyst (6);
the engine (1) is connected with the heat exchange tank (2) through a pipeline, and the engine (1) is used for converting chemical energy of fuel oil into mechanical energy so as to provide driving power for a vehicle and generate exhaust;
the heat exchange tank (2) is used for exchanging heat of engine cooling liquid to urea aqueous solution, heating the urea aqueous solution in the storage tank and storing the rest urea aqueous solution;
the heat exchange tank (2) is connected with the urea tank (3) through a urea pipe (15), and the urea tank (3) is used for storing urea aqueous solution required by the operation of the SCR system and thawing and heating the urea aqueous solution through a heating resistance wire in a low-temperature environment;
the urea pump (4) is connected with the heat exchange tank (2) through a urea pipe (15), the urea pump (4) is used for pumping urea out of the urea tank (3) and pressurizing the urea, then the urea is conveyed into the exhaust pipe through the urea injection unit to be mixed with exhaust gas for reaction, and meanwhile, the residual solution in the urea injection unit is pumped back to the heat exchange tank (2) or the urea tank (3);
the engine (1), the aftertreatment system (5) and the SCR catalyst (6) are sequentially connected, and the aftertreatment system (5) comprises a DOC and a DPF system;
the SCR catalyst (6) is used for spraying reducing agent to make NO in the exhaust gas under the action of the catalyst x Reduction to N 2 And H 2 O。
2. The high-energy urea injection system with the premixing function according to claim 1, which is characterized by further comprising a cooling water pump (7), a cooling liquid electromagnetic valve (8), a back-pumping pump (9) and a mixer (11);
the cooling water pump (7) is arranged between the engine (1) and the heat exchange tank (2), and the cooling water pump (7) is used for providing flow energy for cooling liquid to enter and exit the heat exchange tank (2);
the cooling liquid electromagnetic valve (8) is arranged between the engine (1) and the heat exchange tank (2), and the cooling liquid electromagnetic valve (8) is used for controlling engine cooling liquid to enter the heat exchange tank (2) so as to enable the engine cooling liquid to exchange heat with urea solution;
the reverse pumping pump (9) is arranged between the heat exchange tank (2) and the urea tank (3), and the reverse pumping pump (9) is used for pumping the redundant urea aqueous solution in the heat exchange tank (2), all urea pipes and the residual urea aqueous solution in the urea injection unit back to the urea tank (3) together with the urea pump (4) after the engine (1) stops working;
the mixer (11) is arranged on one side of the SCR catalyst (6), and the mixer (11) is used for further uniformly mixing exhaust gas and urea aqueous solution spray.
3. The high-energy urea injection system with premixing function according to claim 1, characterized in that the urea injection unit comprises a urea pipe interface (29), a positioning and fixing hole (31), an injection valve (32), an electrical interface (30) and a premixing urea nozzle (10), wherein the urea pipe interface (29) is connected with a urea pipe for introducing urea pressurized by a urea pump (4) into the injection unit;
the positioning and fixing hole (31) is used for fixing the urea injection unit at a target position in the aftertreatment system (5);
the injection valve (32) is arranged in the urea injection unit, is used for executing an injection command of the DCU, and is opened and closed according to a certain duty ratio to control the injection rate;
the electrical interface (30) is used for connecting the DCU to control the premixed urea nozzle (10);
the pre-mixing urea nozzle (10) comprises a pre-mixing urea nozzle main body, wherein the pre-mixing urea nozzle is of a venturi tube structure, and further comprises a urea spray inlet (1001) arranged at the upper end of the pre-mixing urea nozzle main body, a pre-mixing outlet (1003) arranged at the lower end of the pre-mixing urea nozzle main body and an exhaust inlet (1002) arranged at the middle side edge of the pre-mixing urea nozzle main body, wherein the pre-mixing urea nozzle (10) is used for spraying atomized urea solution, and the urea and air mixture sent by a urea pump (4) smoothly flow into an exhaust pipe, so that the sprayed urea is uniformly atomized.
4. A high energy urea injection system with premixing function according to claim 3, characterized in that the urea injection unit further comprises a cooling liquid inlet pipe (28) and a cooling liquid inlet pipe (28), the cooling liquid inlet pipe (28) and the cooling liquid inlet pipe (28) are used for introducing circulated cooling liquid and cooling down the premixed urea nozzle (10), and preventing the pre-mixed urea nozzle (10) from being overheated and malfunctioning under the condition of high exhaust temperature.
5. The high-energy urea injection system with the premixing function according to claim 1, wherein the heat exchange tank (2) comprises a shell main body, and a urea water solution heat exchange pipe (202), a cooling liquid guide plate (210), an electric heating disc (209) and a liquid storage cavity (208) are sequentially arranged in the shell main body;
the cooling liquid guide plate (210) is used for providing a guiding effect for the cooling liquid flowing into the heat exchange tank (2), so that the cooling liquid can obtain longer heat exchange time and higher heat exchange efficiency;
the urea aqueous solution heat exchange tube (202) is used for physically isolating the urea aqueous solution from the cooling liquid, and the heat exchange process of the urea aqueous solution and the cooling liquid is realized through the heat conduction property of the self material of the heat exchange tube;
the electric heating disc (209) is arranged in the liquid storage cavity (208), and the electric heating disc (209) is used for heating urea aqueous solution in the liquid storage cavity (208);
the liquid storage cavity (208) is used for storing urea aqueous solution heated by cooling water, so that partial urea aqueous solution can be ensured to enter a working state quickly all the time in the heat exchange tank (2).
6. The high-energy urea injection system with premixing function as claimed in claim 1, further comprising a temperature sensor, NO x A sensor and a pressure sensor;
the temperature sensors are respectively arranged at the outlet of the cooling water pump, the outlet of the urea tank (3), the outlet of the heat exchange tank and the inlet of the pre-mixed urea nozzle and are used for detecting the temperature of the aqueous solution;
the temperature sensor is also arranged at an engine outlet, an SCR inlet and an SCR outlet and used for detecting the gas temperature;
the NO x The sensor is respectively arranged at the engine outlet and the SCR outlet and is used for detecting NO of outlet exhaust gas x Concentration;
the pressure sensor is respectively arranged at the outlet of the urea pump and the inlet of the SCR and is used for detecting the pressure of the urea aqueous solution at the outlet and the exhaust pressure;
the urea tank (3) is also provided with a urea quality sensor and a urea liquid level sensor, and the urea quality sensor is used for detecting the concentration of urea aqueous solution in the urea tank (3); the urea liquid level sensor is used for detecting the liquid level of the urea aqueous solution in the urea tank (3).
7. The high-energy urea injection system with the premixing function according to claim 5, wherein the top of the shell main body of the heat exchange tank (2) is provided with a urea aqueous solution inlet (201), one side of the upper end of the shell main body is provided with a cooling liquid outlet channel (211), one side of the lower end of the shell main body is provided with a cooling liquid inlet channel (204), a urea tank backflow port (205) is arranged below the cooling liquid inlet channel (204), the bottom of the shell is provided with a urea aqueous solution outlet (206), and the cooling liquid inlet channel (204) is provided with a temperature sensor;
the cooling liquid inlet channel (204), the cooling liquid outlet channel (211), the urea aqueous solution inlet (201) and the urea aqueous solution outlet (206) are used for providing an aqueous solution circulation channel;
the urea tank backflow port (205) is arranged at the upper part of the liquid storage cavity (208) and is used for providing a channel for the urea aqueous solution in the heat exchange tube to flow back to the urea tank (3) after the SCR stops working so as to avoid low-temperature icing blockage and damage to the heat exchange tube;
the temperature sensor is used for detecting the temperature of the cooling liquid and the urea.
8. The high-energy urea injection system with premixing function according to claim 1, characterized in that the urea pipe (15) comprises an electrically heated urea pipe and a normal urea pipe, the electrically heated urea pipe is arranged upstream of the urea pump and downstream of the urea pump, and the electrically heated urea pipe upstream of the urea pump is used for heating the urea aqueous solution in the pipe to a near boiling state;
the electric heating urea pipe at the downstream of the urea pump (4) is used for heating the urea solution pressurized by the urea pump (4) to a superheated state and delivering the heated and pressurized urea solution to the pre-mixing urea nozzle (10).
9. The high-energy urea injection system with the premixing function according to claim 1, characterized in that after the engine (1) is started, the high-energy urea injection system carries out heating judgment on the urea temperature in the urea tank (3) to prevent the repeated action of the heating system, specifically:
when the temperature of the urea tank (3) is higher than the set temperature T1, an electromagnetic valve (8) between the urea tank (3) and the heat exchange tank (2) is opened, so that urea aqueous solution flows into the heat exchange tank (2);
when the temperature of the cooling liquid at the inlet of the heat exchange tank (2) is higher than the set temperature T2, a cooling liquid electromagnetic valve (8) at the upstream of the heat exchange tank (2) is opened, and the cooling liquid of the engine (1) enters the heat exchange tank (2) through a cooling liquid inlet channel (204) of the heat exchange tank (2) to exchange heat with the low-temperature urea aqueous solution in the heat exchange pipe.
10. The high-energy urea injection system with premixing function according to claim 9, characterized in that, after the engine (1) is started, the high-energy urea injection system further performs heating judgment on the urea temperature in the liquid storage cavity (208), specifically:
when the temperature of urea in the liquid storage cavity (208) is higher than the target temperature T3, the urea pump (4) extracts urea from the heat exchange tank (2) and pressurizes the urea and then sends the urea to the electric heating urea pipe, the electric heating urea pipe controls heating power through the feedback value of the temperature sensor at the inlet of the pre-mixing urea nozzle (10), the pressurized urea is further heated to the target temperature T4 and then is sent to the urea injection unit, and the urea injection unit pre-mixes urea spray and exhaust gas at the throat and then enters the exhaust system.
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| CN202311443903.2A CN117569898A (en) | 2023-11-01 | 2023-11-01 | High-energy urea injection system with premixing function |
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| CN202311443903.2A CN117569898A (en) | 2023-11-01 | 2023-11-01 | High-energy urea injection system with premixing function |
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