CN209855885U - Control device for removing urea crystals by SCR system - Google Patents
Control device for removing urea crystals by SCR system Download PDFInfo
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- CN209855885U CN209855885U CN201920491769.6U CN201920491769U CN209855885U CN 209855885 U CN209855885 U CN 209855885U CN 201920491769 U CN201920491769 U CN 201920491769U CN 209855885 U CN209855885 U CN 209855885U
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- dissolving
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- dissolving liquid
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- 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
- Y02T10/40—Engine management systems
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- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
Abstract
The utility model provides a controlling means of urea crystallization is clear away to SCR system, include: a dissolving liquid heating device and a first temperature sensor are arranged on the dissolving liquid container; the dissolving solution heating device is used for heating the dissolving solution in the dissolving solution container, and the first temperature sensor is used for detecting the temperature of the liquid in the dissolving solution container; the mixer is arranged at the front end of the SCR, and a pressure sensor is arranged at the front end of the mixer; the outlet of the fan is connected with an air flow meter through a one-way valve, and the outlet of the air flow meter is arranged on the mixer; the mixer is provided with a solution nozzle; the dissolving liquid nozzle is connected with the spraying device; the spraying device is connected with the dissolving liquid container; a mixer heating device is arranged on the mixer; the second temperature sensor is arranged at the rear end outlet of the SCR. The utility model is used for clear away the urea crystallization of SCR to effectual improvement SCR's conversion efficiency.
Description
Technical Field
The utility model belongs to the technical field of the diesel engine tail gas treatment technique and specifically relates to a controlling means that urea crystallization was clear away to SCR system.
Background
The main technical route of tail gas aftertreatment of the national six diesel engine is DOC + DPF + SCR, wherein the SCR is mainly used for reducing NOX in engine tail gas, the working principle of the SCR is that a certain amount of urea is injected into an SCR carrier at a certain exhaust temperature, and NH3 in the urea reduces the NOX into harmless N2 and H2O under the action of the SCR. However, urea is easily crystallized when injected into the SCR carrier at a low temperature or at a low exhaust gas flow rate, and the urea is adhered to the surface of the SCR carrier after crystallization, thereby reducing the NOX conversion efficiency of the SCR carrier and increasing the exhaust gas pressure of the engine body, thereby deteriorating the power and fuel consumption of the engine.
At present, in order to prevent urea crystallization, a mixer is additionally arranged between a urea nozzle and an SCR carrier, so that urea aqueous solution is well atomized when flowing through the mixer, and the risk of urea crystallization is reduced.
Disclosure of Invention
An object of the utility model is to overcome the not enough of existence among the prior art, provide a controlling means that urea crystallization was clear away to the SCR system, effectual improvement SCR's conversion efficiency. The utility model adopts the technical proposal that:
a control device for an SCR system to purge urea crystals, comprising: the device comprises a dissolving liquid container, a dissolving liquid heating device, an air flow meter, a one-way valve, a fan, a dissolving liquid nozzle, a mixer heating device, a pressure sensor, a first temperature sensor and a second temperature sensor;
the dissolving liquid container is used for storing dissolving liquid for dissolving urea crystals;
a dissolving liquid heating device and a first temperature sensor are arranged on the dissolving liquid container; the dissolving solution heating device is used for heating the dissolving solution in the dissolving solution container, and the first temperature sensor is used for detecting the temperature of the liquid in the dissolving solution container;
the mixer is arranged between the DPF and the SCR and positioned at the front end of the SCR, and a pressure sensor is arranged at the front end of the mixer;
the outlet of the fan is connected with an air flow meter through a one-way valve, and the outlet of the air flow meter is arranged on the mixer; the mixer is provided with a solution nozzle; the dissolving liquid nozzle is connected with the spraying device; the spraying device is connected with the dissolving liquid container;
a mixer heating device is arranged on the mixer;
the second temperature sensor is arranged at the rear end outlet of the SCR.
Further, the dissolving liquid heating device comprises a first heating wire.
Furthermore, the dissolving liquid heating device also comprises a heat exchange interlayer in the dissolving liquid container; the heat exchange interlayer in the dissolving liquid container is connected with the engine cooling water tank through a back-and-forth pipeline; a first control valve and a second control valve are respectively arranged on a reciprocating pipeline of the heat exchange interlayer of the solution container and the engine cooling water tank.
Further, the mixer heating device employs a second heating wire.
A control method for cleaning urea crystals by an SCR system comprises the following steps:
when the rotating speed of the engine is zero and the ignition switch is in a closed state, three conditions of ambient temperature, the running kilometers of the whole vehicle and the accumulated value of accumulated urea injection are detected; when the environmental temperature is less than or equal to a first preset threshold value, the logic judgment is true, the time counter starts to accumulate time at the moment, and when the time accumulation value is greater than or equal to a second preset threshold value, the output is true; otherwise, it is false; when the number of kilometers of the whole vehicle is greater than or equal to a third preset threshold value, the output is true; when the accumulated value of the accumulated urea injection quantity is greater than or equal to a fourth preset threshold value, the output is true; when the three conditions meet any one condition, namely the output is true, the rotating speed of the engine is zero, and the ignition switch is turned off, the first signal processing module triggers and feeds a trigger signal back to the control module to start the SCR urea crystallization detection;
firstly, the control module sends information to the fan, the fan is controlled to start to operate at a constant wind speed, and the air flow meter detects air inflow and feeds the air inflow back to the control module in real time; after the fan starts to operate, the second temperature sensor starts to detect the gas temperature at the SCR outlet, and when the gas temperature at the SCR outlet is detected to be lower than a fifth preset threshold value, the judgment is false, and at the moment, the mixer heating device starts to heat; when the temperature of the gas at the outlet of the SCR is detected to be more than or equal to a fifth preset threshold value, the judgment is true, the pressure sensor detects the pressure in front of the SCR, and when the pressure is detected to be less than an eighth preset threshold value, urea crystallization is considered to be absent, and the injection of a dissolving solution is stopped; when the pressure value is detected to be larger than or equal to the eighth preset threshold value, the SCR generates urea crystals, and at the moment, if the temperature of the first temperature sensor is smaller than or equal to the seventh preset threshold value, the urea crystal dissolving solution is not sprayed; if the temperature of the first temperature sensor is detected to be higher than a seventh preset threshold value, the dissolved urea crystal dissolving liquid starts to be sprayed through the dissolving liquid nozzle;
the temperature of the first temperature sensor is less than or equal to a ninth preset threshold value, the engine is in a running state, the control module sends a signal to the fourth signal processing module, and the dissolving liquid heating device is controlled to run to heat the dissolving liquid for dissolving urea crystals; when the temperature of the first temperature sensor is detected to be higher than a seventh preset threshold value, the temperature is processed through a fifth signal processing module, and when the temperature of the first temperature sensor is increased to exceed a tenth preset threshold value, the solution heating device is closed;
when the engine is in a driving stage, the ignition switch is in an on state, the pressure sensor detects the pressure before the SCR, and when the pressure value is larger than or equal to a sixth preset threshold value, the third signal processing module sends a signal to the first signal processing module, and after the first signal processing module receives the signal, the subsequent SCR urea crystallization condition detection is carried out after the engine is stopped, and the dissolved urea crystallization dissolving liquid injection or non-injection is carried out according to the detection result.
Further, the tenth preset threshold is higher than the seventh preset threshold, and the seventh preset threshold is higher than the ninth preset threshold.
Further, the ninth preset threshold is between 0 ℃ and 5 ℃.
Further, the sixth preset threshold is a map value, the abscissa of the map value is the mass flow passing through the SCR carrier, and the ordinate is the temperature at the outlet of the SCR.
The utility model has the advantages that:
1) the utility model discloses through sending into invariable mass flow's air in to the SCR carrier under the engine off state, then according to the urea crystallization condition on the SCR carrier of the big or small judgement SCR carrier front pressure, do not receive engine operating mode change influence during the test, the test result is more accurate credible.
2) The urea crystals on the SCR carrier can be quickly dissolved by spraying the dissolved urea crystal dissolving solution with higher temperature onto the SCR carrier.
3) When the SCR urea crystal is cleared, the aftertreatment carrier does not need to be disassembled.
Drawings
Fig. 1 is a schematic view of the structure of the present invention.
Fig. 2 is a flowchart of the control method of the present invention.
Detailed Description
The invention is further described with reference to the following specific drawings and examples.
As shown in fig. 1, an exhaust gas aftertreatment system of a diesel engine (the engine for short) includes a DOC (oxidation catalyst), a DPF (particulate filter), and an SCR (selective catalytic reduction) connected in sequence;
the utility model provides a controlling means that SCR system clears away urea crystallization, including dissolving liquid container 1, dissolving liquid heating device, air flowmeter 4, check valve 5, fan 6, dissolving liquid nozzle 8, blender 13, blender heating device, pressure sensor 12, first temperature sensor 10, second temperature sensor 14;
the dissolving liquid container 1 is used for storing dissolving liquid for dissolving urea crystals, such as water or specially-made liquid for dissolving urea crystals;
a dissolving solution heating device and a first temperature sensor 10 are arranged on the dissolving solution container 1; the dissolving solution heating device is used for heating the dissolving solution in the dissolving solution container 1, and the first temperature sensor 10 can detect the temperature of the solution in the dissolving solution container 1 in real time;
the dissolving solution heating device comprises a first heating wire 9 and a heat exchange interlayer in the dissolving solution container 1; the heat exchange interlayer in the dissolving liquid container 1 is connected with the engine cooling water tank 3 through a back-and-forth pipeline, so that convection circulation can be formed; a first control valve 2 and a second control valve 11 are respectively arranged on a reciprocating pipeline of a heat exchange interlayer of the dissolving liquid container 1 and the engine cooling water tank 3; the dissolving liquid container 1 can be heated by the liquid in the engine cooling water tank 3 by opening the first control valve 2 and the second control valve 11;
the mixer 13 is arranged between the DPF and the SCR and positioned at the front end of the SCR, and the front end of the mixer 13 is provided with a pressure sensor 12;
the outlet of the fan 6 is connected with an air flow meter 4 through a one-way valve 5, and the outlet of the air flow meter 4 is arranged on a mixer 13; the mixer 13 is provided with a solution nozzle 8; the dissolving solution nozzle 8 is connected with a spraying device; the spraying device is connected with a dissolving liquid container 1;
the mixer 13 is provided with a mixer heating means, such as the second heating wire 7;
the second temperature sensor 14 is arranged at the outlet of the rear end of the SCR;
the pressure sensor 12 is used for detecting the pressure of the front end of the SCR; the mixer 13 is used for atomizing the liquid flowing through the SCR; a second temperature sensor 14 for detecting the temperature of the gases passing through the SCR outlet; the fan 6 can provide air with a certain mass flow rate to flow through the SCR, and the fan 6 adopts a direct current fan; the one-way valve 5 is used for ensuring that air can only flow from one side of the fan 6 to one side of the SCR carrier and cannot flow from one side of the SCR carrier to one side of the fan; the air flow meter 4 can detect the mass flow of the air flowing to the SCR carrier by the fan 6; the second heating wire 7 can heat the gas flowing through the SCR carrier; the dissolving liquid nozzle 8 is used for spraying dissolving liquid for dissolving urea crystals;
a control method for cleaning urea crystals by an SCR system is shown in FIG. 2, wherein in FIG. 2, each signal processing module 1-5 is a logic function module in a control program, and the control module can be an ECU on a vehicle;
when the rotating speed of the engine is zero and the ignition switch is in a closed state, three conditions of ambient temperature, the running kilometers of the whole vehicle and the accumulated value of accumulated urea injection are detected; when the environmental temperature is less than or equal to a first preset threshold (which is a calibration value and can be calibrated according to different types, such as 20-25 ℃), the logic judgment is true, the time counter starts to accumulate time at the moment, and when the time accumulation value is greater than or equal to a second preset threshold (which is a calibration value and can be calibrated according to different types), the output is true; otherwise, it is false; when the number of kilometers of the whole vehicle is greater than or equal to a third preset threshold (which is a calibration value and can be calibrated according to different types), the output is true; when the accumulated value of the accumulated urea injection quantity is larger than or equal to a fourth preset threshold (is a calibration value and can be calibrated according to different models), the output is true; when the three conditions meet any one condition, namely the output is true, the rotating speed of the engine is zero, and the ignition switch is turned off, the first signal processing module 1 triggers and feeds a trigger signal back to the control module to start the detection of whether SCR urea is crystallized or not;
firstly, the control module sends information to the fan 6, the fan 6 is controlled to start to operate at a constant wind speed, and the air flow meter 4 detects the air inflow and feeds the air inflow back to the control module in real time; after the fan 6 starts to operate, the second temperature sensor 14 starts to detect the gas temperature at the outlet of the SCR, when the detected gas temperature at the outlet of the SCR is smaller than a fifth preset threshold value (which is a calibration value and can be calibrated according to different models), the detection result is false, and at this time, the mixer heating device (the second heating wire 7) starts to heat; when the temperature of the gas at the outlet of the SCR is detected to be greater than or equal to a fifth preset threshold value, the judgment is true, the pressure sensor 12 detects the pressure in front of the SCR, and when the pressure is detected to be less than an eighth preset threshold value (which is a calibration value and can be calibrated according to different models), the urea is considered to be not crystallized, and the injection of the dissolving liquid is stopped; when the pressure value is detected to be larger than or equal to the eighth preset threshold value, the SCR is considered to generate urea crystals at the moment, and at the moment, if the temperature of the first temperature sensor 10 is smaller than or equal to the seventh preset threshold value (which is a calibration value and can be calibrated according to different models, for example, 50 ℃), the urea crystal dissolving solution is not sprayed; if the temperature of the first temperature sensor 10 is detected to be higher than a seventh preset threshold value, the dissolved urea crystal dissolving solution starts to be sprayed through the dissolving solution nozzle 8;
when the temperature of the first temperature sensor 10 is less than or equal to a ninth preset threshold (for example, 0-5 ℃) and the engine is in a running state, the control module sends a signal to the fourth signal processing module 4 to control the dissolved solution heating device to run (for example, the first control valve 2 and the second control valve 11 are controlled to be opened, and the first heating wire 9 starts to work), so that the dissolved urea crystal dissolved solution is heated; when the temperature of the first temperature sensor 10 is detected to be higher than a seventh preset threshold (for example, 50 ℃), the processing is performed by the fifth signal processing module 5, and when the temperature of the first temperature sensor 10 rises to exceed a tenth preset threshold (for example, 60 ℃), the solution heating device is turned off (for example, the first control valve 2 and the second control valve 11 are controlled to be turned off, and the first heating wire 9 stops working);
when the engine is in a driving stage, the ignition switch is in an on state, the pressure sensor 12 detects the pressure before the SCR, the pressure value is larger than or equal to a sixth preset threshold value (the pressure value is a map value, the abscissa is the mass flow passing through the SCR carrier, the ordinate is the temperature of an SCR outlet, and the map value can be calibrated according to different engine models), the third signal processing module 3 sends a signal to the first signal processing module 1, and after the first signal processing module 1 receives the signal, the subsequent SCR urea crystallization condition detection is carried out after the engine is stopped, and the dissolved urea crystallization dissolving liquid injection or non-injection is carried out according to the detection result.
The utility model discloses an engine shuts down and sends into the air of constant velocity of flow in the back to the SCR carrier to detect SCR front end pressure through pressure sensor, regard as the urea crystallization of spraying on the SCR when detecting pressure overhigh, and begin to spray through the solution nozzle and dissolve liquid, thereby the effectual urea crystallization of cleaing away.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the scope of the claims of the present invention.
Claims (4)
1. A control device for an SCR system to remove urea crystals is characterized by comprising a dissolving liquid container (1), a dissolving liquid heating device, an air flow meter (4), a one-way valve (5), a fan (6), a dissolving liquid nozzle (8), a mixer (13), a mixer heating device, a pressure sensor (12), a first temperature sensor (10) and a second temperature sensor (14);
the dissolving liquid container (1) is used for storing dissolving liquid for dissolving urea crystals;
a dissolving liquid heating device and a first temperature sensor (10) are arranged on the dissolving liquid container (1); the dissolving solution heating device is used for heating the dissolving solution in the dissolving solution container (1), and the first temperature sensor (10) is used for detecting the temperature of the liquid in the dissolving solution container (1);
the mixer (13) is arranged between the DPF and the SCR and positioned at the front end of the SCR, and a pressure sensor (12) is arranged at the front end of the mixer (13);
an outlet of the fan (6) is connected with an air flow meter (4) through a one-way valve (5), and an outlet of the air flow meter (4) is arranged on the mixer (13); a dissolving liquid nozzle (8) is arranged on the mixer (13); the dissolving solution nozzle (8) is connected with a spraying device; the spraying device is connected with a dissolving liquid container (1);
a mixer heating device is arranged on the mixer (13);
a second temperature sensor (14) is disposed at the SCR rear end outlet.
2. The control device for cleaning urea crystal of SCR system according to claim 1,
the solution heating device comprises a first electric heating wire (9).
3. The control device for cleaning urea crystal of SCR system according to claim 2,
the dissolving solution heating device also comprises a heat exchange interlayer in the dissolving solution container (1); a heat exchange interlayer in the dissolving liquid container (1) is connected with an engine cooling water tank (3) through a back-and-forth pipeline; a first control valve (2) and a second control valve (11) are respectively arranged on a reciprocating pipeline of a heat exchange interlayer of the dissolving liquid container (1) and the engine cooling water tank (3).
4. The control device for cleaning urea crystal of SCR system according to claim 1,
the mixer heating means uses a second heating wire (7).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920491769.6U CN209855885U (en) | 2019-04-12 | 2019-04-12 | Control device for removing urea crystals by SCR system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920491769.6U CN209855885U (en) | 2019-04-12 | 2019-04-12 | Control device for removing urea crystals by SCR system |
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| CN209855885U true CN209855885U (en) | 2019-12-27 |
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| CN201920491769.6U Active CN209855885U (en) | 2019-04-12 | 2019-04-12 | Control device for removing urea crystals by SCR system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109899137A (en) * | 2019-04-12 | 2019-06-18 | 无锡威孚力达催化净化器有限责任公司 | A kind of SCR system removes the control method and device of urea crystals |
| CN114233445A (en) * | 2021-12-13 | 2022-03-25 | 潍柴动力股份有限公司 | Method and device for detecting urea crystals of SCR system |
-
2019
- 2019-04-12 CN CN201920491769.6U patent/CN209855885U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109899137A (en) * | 2019-04-12 | 2019-06-18 | 无锡威孚力达催化净化器有限责任公司 | A kind of SCR system removes the control method and device of urea crystals |
| CN109899137B (en) * | 2019-04-12 | 2023-12-01 | 无锡威孚力达催化净化器有限责任公司 | Control method and device for removing urea crystals by SCR system |
| CN114233445A (en) * | 2021-12-13 | 2022-03-25 | 潍柴动力股份有限公司 | Method and device for detecting urea crystals of SCR system |
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