CN110067618B - DPF regeneration device with two-phase flow medium mixed and exhaust temperature rising strategy thereof - Google Patents

DPF regeneration device with two-phase flow medium mixed and exhaust temperature rising strategy thereof Download PDF

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CN110067618B
CN110067618B CN201910188893.XA CN201910188893A CN110067618B CN 110067618 B CN110067618 B CN 110067618B CN 201910188893 A CN201910188893 A CN 201910188893A CN 110067618 B CN110067618 B CN 110067618B
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dpf
temperature
phase flow
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exhaust
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CN110067618A (en
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刘军
卞加柱
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Jiangsu University
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    • 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
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • 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
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F01N11/002—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity the diagnostic devices measuring or estimating temperature or pressure in, or downstream of the exhaust apparatus
    • 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
    • F01N3/02—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust
    • F01N3/021—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters
    • F01N3/023—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles
    • F01N3/025—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust
    • F01N3/0253—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases
    • F01N3/0256—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for cooling, or for removing solid constituents of, exhaust by means of filters using means for regenerating the filters, e.g. by burning trapped particles using fuel burner or by adding fuel to exhaust adding fuel to exhaust gases the fuel being ignited by electrical means
    • 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
    • F01N9/00—Electrical control of exhaust gas treating apparatus
    • F01N9/002—Electrical control of exhaust gas treating apparatus of filter regeneration, e.g. detection of clogging
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1404—Exhaust gas temperature
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/14—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust gas
    • F01N2900/1406—Exhaust gas pressure
    • 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
    • F01N2900/00—Details of electrical control or of the monitoring of the exhaust gas treating apparatus
    • F01N2900/06—Parameters used for exhaust control or diagnosing
    • F01N2900/16—Parameters used for exhaust control or diagnosing said parameters being related to the exhaust apparatus, e.g. particulate filter or catalyst
    • F01N2900/1602—Temperature of exhaust gas apparatus
    • 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

Abstract

The invention provides a DPF regeneration device mixed by two-phase flow media and an exhaust temperature rising strategy thereof, wherein a nozzle is arranged at the inlet of an exhaust pipe, an oxidation catalyst DOC and a particulate filter DPF are arranged in the exhaust pipe, and the DPF regeneration device comprises a two-phase flow media mixing device and a control system; the two-phase flow medium mixing device is used for providing the two-phase flow medium mixed by the nozzle; the control system comprises a control unit, a DPF temperature sensor, a DOC front exhaust temperature sensor and a DPF differential pressure sensor, wherein the DPF temperature sensor is used for measuring the temperature of an inlet and an outlet of the DPF of the particulate filter; the DOC front exhaust temperature sensor is used for measuring the temperature of a DOC inlet of the oxidation catalyst; the pressure difference sensor of the DPF is used for measuring the pressure difference between the inlet and the outlet of the DPF of the particulate trap. The invention sprays two-phase flow medium into the exhaust pipe through the nozzle, ignites oil gas through the ignition plug, and the control system realizes the state monitoring and the state control of the whole regeneration process.

Description

DPF regeneration device with two-phase flow medium mixed and exhaust temperature rising strategy thereof
Technical Field
The invention relates to the technical field of DPF exhaust aftertreatment, in particular to a DPF regeneration device with a two-phase flow medium mixed and an exhaust temperature rising strategy thereof.
Background
The diesel engine has the advantages of good fuel economy, high reliability, high thermal efficiency, long service life and the like, and is widely applied to the fields of transportation, industrial and agricultural production and the like. The main pollutant emitted by diesel engine is nitrogen oxide NOXAnd Particulate Matter (PM), causing environmental pollution and serious harm to human health. In recent years, increasingly stringent emission regulations have placed higher technical demands on diesel PM emissions. The Diesel Particulate Filter (DPF) technology is considered to be the most effective aftertreatment means for reducing PM at present, the collection efficiency can reach more than 90%, the DPF filters the PM in the exhaust gas when the exhaust gas passes through the Filter, the key technology is the regeneration of the Filter material and the Filter, and the regeneration method and the control strategy for selectively removing the collected PM are the technical difficulties of the DPF application. However, as the driving range increases, more and more particles are deposited in the trap, which causes the exhaust back pressure to increase, the economy and the dynamic performance of the diesel engine deteriorate, and therefore, the trapped combustible particles must be oxidized and burned off in time to realize the regeneration of the particulate trap.
The traditional DPF regeneration system adopts a gear pump to pressurize diesel oil, the diesel oil is directly sprayed into an exhaust channel through a nozzle, an igniter is ignited to burn the diesel oil and oxygen in the exhaust gas so as to realize exhaust heating, the heated exhaust gas passes through the DPF to enable the temperature of a carrier to rise to be more than 600 ℃, and Particulate Matter (PM) captured on the carrier is combusted with the oxygen in the exhaust gas, so that DPF regeneration is realized.
Conventional DPF regeneration systems suffer from the following disadvantages:
1. during regeneration, both the fuel injected into the exhaust and the PM collected by the DPF require oxygen during combustion. The content of oxygen in the exhaust is influenced by the operation condition of the engine, when the engine works under a large load, the concentration of the oxygen in the exhaust is low, the combustion of injected fuel and the combustion of PM collected on the DPF filter body can be influenced, and the regeneration efficiency of the DPF is reduced;
2. the fuel is pressurized by the gear pump and then is directly sprayed into the exhaust through the nozzle, and the atomization performance of the fuel is poor. The oil injection pressure is only about 0.8MPa, and the porous small-aperture nozzle is adopted, so that the particle size of the fuel oil spray is still enlarged, generally more than 80 mu m, the ignition characteristic and the combustion speed of the fuel oil spray are influenced, and the regeneration of the DPF is further influenced;
3. the system reliability is not high. Because the oxygen concentration in the exhaust gas is low or the exhaust gas temperature is very low, the ignition difficulty often occurs, and the injected fuel can not be ignited easily. After the spray is stopped, fuel oil residue exists in the nozzle, and carbon deposition and even blockage of the nozzle are easily caused;
4. accurate metering of the injected fuel cannot be achieved. To ensure high pressures, brushless motor-driven gear pumps operate at very high speeds, typically with the amount of fuel injected being controlled by the operating time. However, the pressure drop due to the wear of the gear pump changes the fuel injection amount.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a DPF regeneration device with a two-phase flow medium mixed and an exhaust temperature rising strategy thereof, which mainly comprise an air-assisted fuel injection and accurate metering system, wherein the fuel is mixed with high-pressure air to form an oil-gas two-phase flow medium which is conveyed to a nozzle, the two-phase flow medium is injected into an exhaust pipe through the nozzle, the oil gas is ignited through an ignition plug, and a control system realizes the state monitoring and the state control of the whole regeneration process.
The present invention achieves the above-described object by the following technical means.
A DPF regeneration device with two-phase flow medium mixing is characterized in that a nozzle is arranged at the inlet of an exhaust pipe, an oxidation catalyst (DOC) and a particle trap (DPF) are arranged in the exhaust pipe, and the DPF regeneration device comprises a two-phase flow medium mixing device and a control system; the two-phase flow medium mixing device is used for providing the two-phase flow medium mixed by the nozzle;
the control system comprises a control unit, a DPF temperature sensor, a DOC front exhaust temperature sensor and a DPF differential pressure sensor, wherein the DPF temperature sensor is used for measuring the temperature of an inlet and an outlet of the DPF of the particulate filter; the DOC front exhaust temperature sensor is used for measuring the temperature of a DOC inlet of the oxidation catalyst; the DPF differential pressure sensor is used for measuring the differential pressure between the inlet and the outlet of the DPF of the particulate trap; the control unit collects and analyzes signals of the DPF temperature sensor, the DOC front exhaust temperature sensor and the DPF differential pressure sensor and controls the oil injection rate of the two-phase flow medium mixing device.
Further, the two-phase flow medium mixing device comprises a mixing cavity, a gas supply system and a liquid supply system; the gas supply system and the liquid supply system are respectively communicated with the mixing cavity and are used for mixing two-phase flow media; the mixing chamber is in communication with a nozzle.
Further, the air supply system comprises a compressed air source, an air path on-off electromagnetic valve, a pressure reducing and stabilizing device and an air path one-way valve, wherein the compressed air source is communicated with the mixing cavity sequentially through the air path on-off electromagnetic valve, the pressure reducing and stabilizing device and the air path one-way valve;
the liquid supply system comprises a fuel tank, a diaphragm pump and a liquid path one-way valve, and the fuel tank is communicated with the mixing cavity sequentially through the diaphragm pump and the liquid path one-way valve.
Further, still include bypass gas accuse liquid return valve, the bypass of bypass gas accuse liquid return valve with gas supply system intercommunication, bypass gas accuse liquid return valve import and hybrid chamber intercommunication, bypass gas accuse liquid return valve export and fuel tank intercommunication.
The device further comprises a pump pressure sensor and a DPF differential pressure sensor, wherein the pump pressure sensor is used for measuring the pressure of the outlet of the diaphragm pump; the DPF differential pressure sensor is used for measuring the differential pressure between the inlet and the outlet of the DPF of the particulate trap; the control unit collects signals of the analysis pump pressure sensor and the DPF differential pressure sensor.
Further, the control unit diagnoses the fault of the DPF system according to the collected signals, specifically:
judging whether the liquid supply system or the nozzle is blocked or not according to the pressure of the outlet of the diaphragm pump measured by the pump pressure sensor;
judging whether the DPF is blocked or not according to the pressure difference between the inlet and the outlet of the DPF measured by the DPF pressure difference sensor;
and judging whether the combustion temperature reaches the DPF regeneration condition or not according to the temperature of the DPF inlet and the temperature of the DPF outlet measured by the DPF temperature sensor and the temperature of the DOC inlet measured by the DOC front exhaust temperature sensor of the particulate filter.
An exhaust temperature ramping strategy for a two-phase flow media mixed DPF regeneration device, comprising the steps of:
measuring the temperature T of the DOC inlet of the oxidation catalyst by the DOC front exhaust temperature sensor1(ii) a Measuring temperature T of DPF inlet of particulate trap through DPF front exhaust temperature sensor2(ii) a Measuring temperature T of DPF outlet of particulate trap through DPF rear exhaust temperature sensor3；
When the temperature T is1When the temperature is lower than 350-; when the temperature T is1When the temperature is more than 350-400 ℃, the nozzle sprays fuel oil, and the fuel oil is combusted through the exhaust temperature of the exhaust pipe;
when the temperature T is2Less than the critical temperature TcrAccording to T, the control unit2Controlling the flow rate of the fuel injected by the nozzle; when the temperature T is2Greater than the critical temperature TcrClosing the nozzle;
when the temperature T is3Greater than DPF safety temperature-resistant threshold TsafeAnd when the control unit is in operation, the control unit sends out a fault signal.
Go toThe control unit determines the temperature T of the DPF inlet according to the following formula2The range of (A):
temperature T of inlet required for DPF regeneration of particulate trap2Conditions are as follows:
Figure GDA0002740672650000031
in the formula:
wb＝f-1(Δp)
wherein: ρ is the exhaust gas density (kg/m)3) (ii) a v is the exhaust flow rate (m/s); cPGThe specific heat capacity of exhaust gas is J/(kg. K); r is a gas constant; e is surface activation energy; d is the diameter (m) of the particulate trap DPF; rhokPore density (pores/m) for a particulate trap DPF; s is the particle layer deposition coefficient (m)-1) (ii) a p is the discharge pressure (kPa); y is the current exhaust oxygen molar concentration (mol/m)3)； wbIs the thickness (m) of the microparticle layer; a is the side length (m) of a DPF pore channel of the particulate filter; l is the length (m) of the DPF; alpha is the oxidation completeness of the carbon particles; Δ HCOIs the enthalpy of formation of CO (J/(kg. mol);. DELTA.HCO2Is CO2Delta P is the pressure difference (kPa) between the inlet and the outlet of the DPF of the particulate trap measured by a DPF pressure difference sensor;
from the above formula, T is derivedcr<T2<TsafeWherein T issafeThe safety temperature-resistant threshold value of the DPF is set.
Further, the control unit is based on T2Controlling the flow of the fuel injected by the nozzle, specifically:
Figure GDA0002740672650000041
in the formula: qburner(T) theoretical exhaust temperature Texh(T) increase to T2Energy released by combustion (kJ) of the injected fuel;
Qamb(t) is the burner heat loss rate (kJ/h);
CPthe specific heat capacity at constant pressure (kJ/kg. K);
qmthe exhaust flow rate (kg/h);
Tburner(t) is the theoretical heating temperature (K);
Tambambient temperature (K);
Texh(t) theoretical exhaust temperature (K);
Rtresistance to heat dissipation;
Hμthe fuel is diesel oil with low heat value;
b is the injection rate (kg/h) of the fuel injected from the nozzle (112).
The invention has the beneficial effects that:
1. the DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof have simple, compact and reasonable structure, small influence on a diesel engine in the regeneration process of a DPF system, no secondary pollution to the environment, and good reliability and durability.
2. The DPF regeneration device with two-phase flow medium mixing and the exhaust temperature rising strategy thereof have the advantages that fuel oil is accurately metered, fuel oil is metered in a fixed time and a fixed quantity manner, the temperature and pressure sensors are arranged, the injection quantity can be accurately corrected, and the metering injection precision is within 2%.
3. The DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof have good fuel atomization performance, the fuel atomization particle size of oil gas reaches 30-50 mu m, and the ignition and combustion performance are good.
4. According to the DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof, air is brought by conveying and injecting the gas-assisted fuel oil, so that the injected fuel oil is in an oxygen-rich environment with sufficient oxygen, and the ignition condition and the combustion condition of the fuel oil are improved. On the one hand, the ignition can be smoothly performed, on the other hand, the combustion efficiency can be improved, the temperature of the DPF filter body can be rapidly increased, and the condition that the PM collected in the DPF is oxidized and combusted at high temperature is improved. The regeneration efficiency of the DPF is greatly improved.
5. The DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof simplify an ignition device. The fuel oil is conveyed and sprayed in an auxiliary gas mode, so that the sprayed fuel oil is fully atomized, the particle size of fuel oil particles is distributed in the range of 30-50 microns, sufficient air is sprayed in the auxiliary gas mode, oil gas is fully mixed, and the ignition condition and the flame propagation condition of the fuel oil are greatly improved. The ignition device generally employs a resistance type ignition plug.
6. The DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof are stable in the later working period. The diaphragm pump realizes accurate fuel metering and has good stability in long-term operation. On one hand, the reciprocating motion of the rubber diaphragm is used for absorbing and pressurizing fuel oil, so that the metal moving part is prevented from contacting with the oil liquid when the gear pump operates, and the corrosion is prevented. On the other hand, the diaphragm pump has no mechanical abrasion during working and long service life. When the gear pump is adopted, gear wear can cause tooth clearance increase, so that the oil hydraulic pressure is reduced.
7. According to the DPF regeneration device with the two-phase flow medium mixed and the exhaust temperature rising strategy thereof, after oil injection is stopped, the stepping motor does not rotate to inject oil, the conveying pipeline and the nozzle can be effectively swept through air, the fuel oil residue is avoided, and carbon deposition and blockage of the nozzle are avoided.
Drawings
FIG. 1 is a schematic diagram of a DPF regeneration apparatus with a two-phase flow medium mixed according to the present invention.
Fig. 2 is a flow chart of the control unit for fault diagnosis of the DPF system according to the present invention.
FIG. 3 is a flow chart of an exhaust temperature ramp strategy according to the present invention.
In the figure:
101-a source of compressed air; 102-gas path on-off electromagnetic valve; 103-a pressure reducing and stabilizing device; 104-gas path check valve; 105-a fuel tank; 106-step motor; 107-diaphragm pump; 108-a liquid path check valve; 109-a mixing chamber; 110-a bypass air control liquid return valve; 111-mixed oil and gas conveying pipeline; 112-a nozzle; 113-an igniter; 114-oxidation catalyst DOC; 115-particulate trap DPF; 116-a control unit; 117-DPF differential pressure sensor; 118-DOC front exhaust gas temperature sensor; 119-DPF front exhaust temperature sensor; 120-DPF rear exhaust gas temperature sensor; 121-pump pressure sensor.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
As shown in FIG. 1, the DPF regeneration device with two-phase flow medium mixing of the invention is provided with a nozzle 112 at the inlet of an exhaust pipe, an oxidation catalyst DOC114 and a particulate filter DPF115 are arranged in the exhaust pipe, and comprises a two-phase flow medium mixing device and a control system; the two-phase flow medium mixing device is used for providing the two-phase flow medium mixed by the nozzle 112;
the two-phase flow medium mixing device comprises a mixing cavity 109, an air supply system and a liquid supply system; the gas supply system and the liquid supply system are respectively communicated with the mixing cavity 109 and are used for mixing two-phase flow media; the mixing cavity 109 is communicated with the nozzle 112 through a mixed oil and gas conveying pipeline 111; the air supply system comprises a compressed air source 101, an air path on-off electromagnetic valve 102, a pressure reducing and stabilizing device 103 and an air path one-way valve 104, wherein the compressed air source 101 is communicated with the mixing cavity 109 through the air path on-off electromagnetic valve 102, the pressure reducing and stabilizing device 103 and the air path one-way valve 104 in sequence; the compressed air source 101 (the pressure of the compressed air source is 0.5-0.9 MPa) obtains an air source with a basically constant pressure of 0.3MPa through the pressure reducing and stabilizing device 103, the air after pressure reducing and stabilizing is sprayed into the mixing cavity 109 through the air path one-way valve 104, and the opening pressure of the air path one-way valve 104 is about 0.1 MPa.
The liquid supply system comprises a fuel tank 105, a diaphragm pump 107 and a liquid path one-way valve 108, wherein the fuel tank 105 is communicated with a mixing cavity 109 through the diaphragm pump 107 and the liquid path one-way valve 108 in sequence. The suction and pressurization of the fuel from the fuel tank 105 is achieved by a diaphragm pump 107 driven by a stepper motor 106, typically to 0.5-0.8Mpa, and a fluid line check valve 108 for injecting high pressure fuel into a mixing chamber 109. The opening pressure of the liquid path check valve 108 is about 0.2 Mpa.
Still include bypass gas accuse return liquid valve 110, bypass gas accuse return liquid valve 110 the bypass with air supply system intercommunication, bypass gas accuse return liquid valve 110 import and mixing chamber 109 intercommunication, bypass gas accuse return liquid valve 110 export and fuel tank 105 intercommunication. When the air path on-off solenoid valve 102 is switched off, air inlet is cut off, the diaphragm of the bypass air control liquid return valve 110 is under the action of the return spring, so that the liquid return valve is opened, the liquid path is the same as the liquid return, and pressure relief of the liquid path is realized. In addition, in the process of pressure building of the liquid path, the liquid return valve is opened to drive the stepping motor 106, so that the diaphragm pump 107 works to discharge air in the liquid path cavity through liquid return, and the pressure building difficulty caused by the existence of air in the liquid path is prevented.
When the gas path on-off solenoid valve 102 is switched on, the pressure reducing and stabilizing valve starts to work to provide air with stable pressure, the liquid return valve is closed after the diaphragm of the bypass pneumatic control liquid return valve 110 overcomes the force of the return spring under the action of air pressure, the liquid path and the return liquid are cut off, and the stepping motor 106 drives the diaphragm pump 107 to realize smooth pressure building of the liquid path and injection of high-pressure fuel through the liquid path one-way valve.
The fuel oil and the air are mixed in the mixing cavity 109, the fuel oil is fully atomized, the obtained mixed oil-gas two-phase medium is conveyed to the single-hole nozzle 112 through the mixed oil-gas conveying pipeline 111, and a certain pressure is formed in the mixing cavity 109 due to the throttling effect of the nozzle 112 and is sprayed into the front end of the oxidation catalyst DOC114 through the nozzle 112. An electric resistance type igniter 113 is disposed near the outlet of the nozzle 112. Because of the good atomization condition, the resistance heating type igniter 113 is adopted to ignite the oil gas, so that the oil gas is smoothly ignited.
When the amount of fuel required for regeneration is injected from the injection nozzle 112, the stepper motor is deactivated and no more fuel is injected into the mixing chamber 109. At the moment, the gas path on-off solenoid valve 102 is still connected, high-pressure air is still sprayed into the mixing cavity through the gas path one-way valve 104 and is sprayed into the exhaust pipe through the conveying pipeline 111 and the nozzle 112, so that the conveying pipeline 111 and the nozzle 112 are effectively purged, fuel oil is prevented from remaining at the conveying pipeline 111 and the nozzle 112, and carbon deposition blockage of the nozzle 112 is avoided. A single-hole nozzle 112 is adopted, a hammer-shaped rotatable valve core is adopted in the nozzle, the valve core is provided with a tangential channel, and after ventilation, the valve core generates tangential force under the action of airflow to enable the valve core to rotate.
The control system comprises a control unit 116, a DPF temperature sensor, a DOC front exhaust temperature sensor 118 and a DPF differential pressure sensor 117, wherein the DPF temperature sensor is used for measuring the temperature of an inlet and an outlet of a particulate trap DPF 115; the DOC front exhaust temperature sensor 118 is used for measuring the temperature of the DOC114 inlet of the oxidation catalyst; the DPF pressure difference sensor 117 is used for measuring the pressure difference between the inlet and the outlet of the DPF115 of the particulate trap; the control unit 116 collects and analyzes signals of the DPF temperature sensor, the DOC front exhaust temperature sensor 118, and the DPF differential pressure sensor 117, and controls the injection rate of the two-phase flow medium mixing device.
The control unit 116 diagnoses the fault of the DPF system according to the collected signals, specifically:
judging whether the liquid supply system or the nozzle 112 is blocked or not according to the pressure at the outlet of the diaphragm pump 107 measured by the pump pressure sensor 121;
judging whether the particulate trap DPF115 is blocked or not according to the pressure difference between the inlet and the outlet of the particulate trap DPF115 measured by the DPF pressure difference sensor 117;
and judging whether the combustion temperature reaches the DPF regeneration condition or not according to the temperature of the inlet and the outlet of the DPF115 of the particulate filter measured by the DPF temperature sensor and the temperature of the inlet of the DOC114 of the oxidation catalyst measured by the DOC front exhaust temperature sensor 118.
The exhaust temperature rising strategy of the DPF regeneration device with the two-phase flow medium mixing comprises the following steps:
measuring the temperature T of the inlet of the oxidation catalyst DOC114 by means of the DOC front exhaust temperature sensor 1181(ii) a Measurement of temperature T at the inlet of the particulate trap DPF115 by a DPF front exhaust temperature sensor 1192(ii) a Measuring temperature T of particulate trap DPF115 outlet via DPF post-exhaust temperature sensor 1203；
When the temperature T is1When the temperature is lower than 350-; when the temperature T is1When the temperature is higher than 350-400 ℃, the nozzle 112 injects fuel oil, and the fuel oil is combusted through the exhaust temperature of the exhaust pipe;
when the temperature T is2Less than the critical temperature TcrAccording to T, the control unit 1162Controlling the flow rate of the fuel injected from the injection nozzle 112; when the temperature T is2Greater than the critical temperature TcrWhile, the nozzle 112 is closed;
when the temperature T is3Greater than DPF safety temperature-resistant threshold TsafeThe control unit 116 signals a fault.
The control unit 116 determines the temperature T at the inlet of the particulate trap DPF115 according to the following formula2The range of (A):
temperature T of inlet required for regeneration of the particulate trap DPF1152Conditions are as follows:
Figure GDA0002740672650000071
in the formula:
wb＝f-1(Δp)
wherein: ρ is the exhaust gas density (kg/m)3) (ii) a v is the exhaust flow rate (m/s); cpgThe specific heat capacity of exhaust gas is J/(kg. K); r is gas constant, R is 8.31m3kPa/(kg. mol. K); e is surface activation energy, E ═ 80-160 x 103J/mol; d is the diameter (m) of the particulate trap DPF; rhokPore density (pores/m) for a particulate trap DPF; s is the particle layer deposition coefficient (m)-1) (ii) a p is the discharge pressure (kPa); y is the current exhaust oxygen molar concentration (mol/m)3)；wbIs the thickness (m) of the microparticle layer; a is the side length (m) of a DPF pore channel of the particulate filter; l is the length (m) of the DPF; alpha is the oxidation completeness of carbon particles, and alpha is 0.5-1; Δ HCOIs the enthalpy of formation of CO (J/(kg. mol);. DELTA.HCO2Is CO2Δ P is the pressure difference (kPa) of the inlet and outlet of the particulate trap DPF115 as measured by a DPF pressure difference sensor 117;
from the above formula, T is derivedcr<T2<TsafeWherein T issafeThe safety temperature-resistant threshold value of the DPF is set.
In the examples, 600 ℃ was calculated<T2<750 ℃ C, i.e. TcrAt 600 ℃ and TsafeIt was 750 ℃.
After a certain amount of time that the particulate trap DPF115 is operational, the exhaust backpressure value (i.e., Δ P) reaches a regeneration exhaust backpressure threshold, and DPF regeneration begins. In the regeneration strategy, a gas supplementing module and an oil injection module are core parts of a control system of the regeneration strategy, the gas supplementing module controls the opening and closing of a gas supplementing valve through a load-oxygen concentration relation to ensure that the oxygen content of exhaust gas is in a surplus state, and the control algorithm is carried out according to the following processes:
the control unit (116) is based on T2Controlling the flow rate of the fuel injected by the nozzle (112), specifically:
Figure GDA0002740672650000081
in the formula: qburner(T) theoretical exhaust temperature Texh(T) increase to T2Energy released by combustion (kJ) of the injected fuel;
Qamb(t) is the burner heat loss rate (kJ/h);
Cpthe specific heat capacity at constant pressure (kJ/kg. K);
qmthe exhaust flow rate (kg/h);
Tburner(t) is the theoretical heating temperature (K);
Tambambient temperature (K);
Texh(t) theoretical exhaust temperature (K);
Rtgenerally, 0.35-0.4 Kh/kJ is taken for heat dissipation resistance;
Hμis low heating value of diesel oil, and is generally 4.25X 104kJ/kg；
b is the injection rate (kg/h) of the fuel injected from the nozzle (112).
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.

Claims (7)

1. A DPF regeneration device with two-phase flow medium mixing is characterized by comprising a two-phase flow medium mixing device and a control system, wherein a nozzle (112) is arranged at the inlet of an exhaust pipe, and an oxidation catalyst DOC (114) and a particulate filter DPF (115) are arranged in the exhaust pipe; the two-phase flow medium mixing device is used for providing the two-phase flow medium mixed by the nozzle (112);
the control system comprises a control unit (116), a DPF temperature sensor, a DOC front exhaust temperature sensor (118) and a DPF differential pressure sensor (117), wherein the DPF temperature sensor is used for measuring the temperature of an inlet and an outlet of a particulate trap DPF (115); the DOC front exhaust temperature sensor (118) is used for measuring the temperature of an inlet of the oxidation catalyst DOC (114); the DPF pressure difference sensor (117) is used for measuring the pressure difference between the inlet and the outlet of the DPF (115) of the particulate trap; the control unit (116) collects and analyzes signals of a DPF temperature sensor, a DOC front exhaust temperature sensor (118) and a DPF differential pressure sensor (117), and controls the oil injection rate of the two-phase flow medium mixing device;
the control unit (116) diagnoses the fault of the DPF system according to the acquired signals, specifically:
judging whether the particulate trap DPF (115) is blocked or not according to the pressure difference between the inlet and the outlet of the particulate trap DPF (115) measured by a DPF pressure difference sensor (117);
and judging whether the combustion temperature reaches the DPF regeneration condition or not according to the temperature of the inlet and the outlet of the DPF (115) of the particulate trap measured by the DPF temperature sensor and the temperature of the inlet of the DOC (114) of the oxidation catalyst measured by the DOC front exhaust temperature sensor (118).
2. The DPF regeneration device with two-phase flow media mixing according to claim 1, wherein the two-phase flow media mixing device comprises a mixing chamber (109), an air supply system and a liquid supply system; the gas supply system and the liquid supply system are respectively communicated with the mixing cavity (109) and are used for mixing two-phase flow media; the mixing chamber (109) communicates with a nozzle (112).
3. The DPF regeneration device with two-phase flow medium mixing function according to claim 2, wherein the air supply system comprises a compressed air source (101), an air passage on-off solenoid valve (102), a pressure reduction and stabilization device (103) and an air passage one-way valve (104), wherein the compressed air source (101) is communicated with the mixing cavity (109) sequentially through the air passage on-off solenoid valve (102), the pressure reduction and stabilization device (103) and the air passage one-way valve (104);
the liquid supply system comprises a fuel tank (105), a diaphragm pump (107) and a liquid path one-way valve (108), and the fuel tank (105) is communicated with the mixing cavity (109) sequentially through the diaphragm pump (107) and the liquid path one-way valve (108).
4. The DPF regeneration device with two-phase flow medium mixing function according to claim 3, further comprising a bypass air-controlled liquid return valve (110), wherein a bypass of the bypass air-controlled liquid return valve (110) is communicated with the air supply system, an inlet of the bypass air-controlled liquid return valve (110) is communicated with the mixing cavity (109), and an outlet of the bypass air-controlled liquid return valve (110) is communicated with the fuel tank (105).
5. The two-phase flow media mixed DPF regeneration device of claim 3, further comprising a pump pressure sensor (121), said pump pressure sensor (121) for measuring the pressure at the outlet of the diaphragm pump (107); the control unit (116) collects signals of the analysis pump pressure sensor (121).
6. The DPF regeneration device with two-phase flow medium mixing according to claim 5, characterized in that the control unit (116) diagnoses failure of DPF system according to the collected pump pressure sensor (121) signal, specifically:
and judging whether the liquid supply system or the nozzle (112) is blocked or not according to the pressure of the outlet of the diaphragm pump (107) measured by the pump pressure sensor (121).
7. An exhaust temperature ramping strategy for a two-phase flow media mixed DPF regeneration device according to claim 1, comprising the steps of:
measuring the temperature T of the oxidation catalyst DOC (114) inlet by means of the DOC front exhaust temperature sensor (118)1(ii) a Before passing through DPFAn exhaust temperature sensor (119) measures a temperature T at an inlet of a particulate trap DPF (115)2(ii) a Measuring temperature T of particulate trap DPF (115) outlet by DPF after-exhaust temperature sensor (120)3；
When the temperature T is1When the temperature is lower than 350-; when the temperature T is1When the temperature is more than 350-400 ℃, the nozzle (112) injects fuel oil, and the fuel oil is combusted through the exhaust temperature of the exhaust pipe;
when the temperature T is2Less than the critical temperature TcrAccording to T, the control unit (116)2Controlling the flow rate of fuel injected by the nozzle (112); when the temperature T is2Greater than the critical temperature TcrWhile closing the nozzle (112);
when the temperature T is3Greater than DPF safety temperature-resistant threshold Tsafe-the control unit (116) issues a fault signal;
the control unit (116) determines the temperature T of the inlet of the DPF (115) of the particulate trap according to the following formula2The range of (A):
temperature T of inlet required for regeneration of said particulate trap DPF (115)2Conditions are as follows:
Figure FDA0002740672640000021
in the formula:
wb＝f-1(Δp)
wherein: ρ is the exhaust gas density (kg/m)3) (ii) a ν is the exhaust flow rate (m/s); cpgThe specific heat capacity of exhaust gas is J/(kg. K); r is a gas constant; e is surface activation energy; d is the diameter (m) of the particulate trap DPF; rhokPore density (pores/m) for a particulate trap DPF; s is the particle layer deposition coefficient (m)-1) (ii) a p is the discharge pressure (kPa); y is the current exhaust oxygen molar concentration (mol/m)3)；wbIs the thickness (m) of the microparticle layer; a is the side length (m) of a DPF pore channel of the particulate filter; l is the length (m) of the DPF; alpha is the oxidation completeness of the carbon particles; Δ HCOIs the enthalpy of formation of CO (J/(kg. mol);
Figure FDA0002740672640000022
is CO2Delta P is the pressure difference (kPa) of the inlet and outlet of the particulate trap DPF (115) measured by a DPF pressure difference sensor (117);
from the above formula, T is derivedcr<T2<TsafeWherein T issafeA safe temperature-resistant threshold value of the DPF;
the control unit (116) is based on T2Controlling the flow rate of the fuel injected by the nozzle (112), specifically:
Figure FDA0002740672640000031
in the formula: qburner(T) theoretical exhaust temperature Texh(T) increase to T2Energy released by combustion (kJ) of the injected fuel;
Qamb(t) is the burner heat loss rate (kJ/h);
Cpthe specific heat capacity at constant pressure (kJ/kg. K);
qmthe exhaust flow rate (kg/h);
Tburner(t) is the theoretical heating temperature (K);
Tambambient temperature (K);
Texh(t) theoretical exhaust temperature (K);
Rtresistance to heat dissipation;
Hμthe fuel is diesel oil with low heat value;
b is the injection rate (kg/h) of the fuel injected from the nozzle (112).
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