CN115539228A - Air inlet control system and method of premixed high-power gas engine - Google Patents

Air inlet control system and method of premixed high-power gas engine Download PDF

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CN115539228A
CN115539228A CN202211264717.8A CN202211264717A CN115539228A CN 115539228 A CN115539228 A CN 115539228A CN 202211264717 A CN202211264717 A CN 202211264717A CN 115539228 A CN115539228 A CN 115539228A
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gas
gas engine
air
air inlet
rotating speed
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焦联国
李焕英
胡明生
陈平
李锦华
蒋爱香
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Shannxi Diesel Engine Heavy Industry Co Ltd
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Shannxi Diesel Engine Heavy Industry Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
    • F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/0002—Controlling intake air
    • F02D41/0007—Controlling intake air for control of turbo-charged or super-charged engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1445—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being related to the exhaust flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1454—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an oxygen content or concentration or the air-fuel ratio
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1473—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the regulation method
    • F02D41/1475—Regulating the air fuel ratio at a value other than stoichiometry
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D9/00—Controlling engines by throttling air or fuel-and-air induction conduits or exhaust conduits
    • F02D9/08—Throttle valves specially adapted therefor; Arrangements of such valves in conduits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
    • F02M21/023—Valves; Pressure or flow regulators in the fuel supply or return system
    • F02M21/0239—Pressure or flow regulators therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
    • F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
    • F02M21/04—Gas-air mixing apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/10—Air intakes; Induction systems
    • F02M35/10006—Air intakes; Induction systems characterised by the position of elements of the air intake system in direction of the air intake flow, i.e. between ambient air inlet and supply to the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/10—Air intakes; Induction systems
    • F02M35/1015—Air intakes; Induction systems characterised by the engine type
    • F02M35/10157—Supercharged engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
    • F02M35/00—Combustion-air cleaners, air intakes, intake silencers, or induction systems specially adapted for, or arranged on, internal-combustion engines
    • F02M35/10—Air intakes; Induction systems
    • F02M35/10242—Devices or means connected to or integrated into air intakes; Air intakes combined with other engine or vehicle parts
    • F02M35/10255—Arrangements of valves; Multi-way valves
    • 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
    • Y02T10/30—Use of alternative fuels, e.g. biofuels

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

Abstract

The air inlet control system and the method thereof of the premixing type high-power gas engine are provided, two air inlet ends of a mixer are respectively connected with an air inlet pipe connected with an air filter and a gas inlet pipe provided with a gas flow valve, the gas flow valve and a rotating speed sensor arranged at the rotating speed detection position of an exhaust gas turbocharger are both connected with a control unit, the control unit takes the rotating speed of the exhaust gas turbocharger detected by the rotating speed sensor as an input variable, and the opening degree of the gas flow valve is controlled to realize the control of the air-fuel ratio of mixed gas entering the gas engine; an electric throttle valve connected with the control unit is installed on the intercooler exhaust pipe, and a bypass unit communicated with the intercooler exhaust pipe and the exhaust gas turbocharger air inlet pipe is connected with the control unit through a control line. The invention improves the accuracy of air-fuel ratio control of the pre-mixing type gas engine under the transition working condition, improves the economical efficiency and the emission of the operation of the gas engine, and meets the automatic regulation of the flow rate of the mixed gas under different operation working conditions of the gas engine.

Description

Air inlet control system and method of premixed high-power gas engine
Technical Field
The invention belongs to the technical field of engines, and particularly relates to an air inlet control system and an air inlet control method of a premixing type high-power gas engine.
Background
At present, the air intake mode of a gas engine can be divided into a premixing mode, a single-point injection mode, a multipoint injection mode and an in-cylinder direct injection mode, wherein the premixing mode mixes gas and air according to a preset air-fuel ratio through a mixer before entering a supercharger, then the gas and the air are supercharged through an exhaust gas turbocharger, and the gas and the air enter a cylinder for ignition and combustion after being cooled by an intercooler; for an exhaust gas turbocharging gas engine, under the transient working condition of the engine, the open-loop control of the air-fuel ratio is basically adopted, but the dynamic response of the gas engine is poor, and the duration of the overload working condition such as loading, unloading and the like is long, so that the air-fuel ratio cannot be accurately controlled in the process, the economical efficiency and the emission performance of the gas engine are directly influenced, and particularly, the increasingly strict environmental regulations have higher requirements on the emission of the engine; moreover, due to the inertia effect of the exhaust gas turbine, the phenomenon of turbine lag exists, namely when the load working condition of the engine changes, the air inflow cannot be changed in time, and the problem that the air-fuel ratio cannot be accurately controlled to a certain extent exists by adopting a speed-density method or a gas mass flow control algorithm; for a premixed gas engine, gas and air are mixed in a mixer before entering an exhaust gas turbocharger through a gas flow valve, a throttle valve and an intake bypass valve are mainly used for adjusting the pressure of an intake manifold, namely controlling the flow of the mixture entering a cylinder to realize the control of the rotation speed and the load of the engine, namely the control of the air-fuel ratio and the control of the rotation speed and the load are relatively independent, the measured pressure and the temperature of the intake manifold are the pressure and the temperature of the mixture, and the gas flow calculated by a speed-density method is also the flow of the mixture, so that the air-fuel ratio cannot be accurately reflected; the fuel gas mass flow method is to correct the fuel gas flow by the actually measured engine power to achieve the purpose of controlling the air-fuel ratio, but for the premixed gas engine, the opening degrees of a throttle valve and an air intake bypass valve are main factors influencing the engine power, and the air-fuel ratio cannot be accurately controlled, while the main factor influencing the air-fuel ratio is the air flow entering a supercharger, the difficulty and the cost of measuring the air intake flow of the supercharger are very high for the high-power gas engine, and the difficulty of controlling the air-fuel ratio of the premixed gas engine is large, so that improvement needs to be provided for the problems.
Disclosure of Invention
The technical problems solved by the invention are as follows: the air inlet control system and the method thereof for the premixed high-power gas engine are provided, the rotating speed of an exhaust gas turbocharger detected by a rotating speed sensor is taken as an input variable, the control of the air-fuel ratio of mixed gas entering the gas engine is realized by controlling the opening of a gas flow valve, so that the direct control of the air-fuel ratio of the premixed gas engine is realized, the control is simple, the calculation process is simplified, an air flow meter is omitted, the cost is saved, the accuracy of the air-fuel ratio control of the premixed gas engine in the transition working condition is improved, and the running economy and the emission performance of the gas engine are improved; the bypass unit is arranged, so that the real-time regulation and control of the using amount of the mixed gas can be completed according to the operation working conditions of the gas engine on the premise of adjusting the air-fuel ratio in real time, and the automatic regulation of the flow of the mixed gas under different operation working conditions of the gas engine can be met.
The technical scheme adopted by the invention is as follows: the air inlet control system of the premixing type high-power gas engine comprises an exhaust gas turbocharger and an intercooler, wherein an air inlet end of the intercooler is connected with an exhaust pipe of the exhaust gas turbocharger, an air inlet pipe of the exhaust gas turbocharger is connected with an exhaust end of a mixer, two air inlet ends of the mixer are respectively connected with an air inlet pipe connected with an air filter and a gas inlet pipe provided with a gas flow valve, an exhaust pipe of the intercooler is connected with an air inlet main pipe of the gas engine, an exhaust main pipe of the gas engine is connected with an air inlet pipe of the exhaust gas turbocharger, the gas flow valve and a rotating speed sensor arranged at a rotating speed detection position of the exhaust gas turbocharger are connected with a control unit, the control unit takes the rotating speed of the exhaust gas turbocharger detected by the rotating speed sensor as an input variable, and the air-fuel ratio of mixed gas entering the gas engine is controlled by controlling the opening degree of the gas flow valve; the electric throttle valve connected with the control unit is installed on the intercooler exhaust pipe, the bypass unit communicated with the intercooler exhaust pipe and the exhaust gas turbocharger air inlet pipe is connected with the control unit through a control line, and the control unit regulates the electric throttle valve and the bypass unit according to the operation condition of the gas engine to realize regulation of the flow of mixed gas entering the gas engine.
The bypass unit comprises a bypass pipe and an air inlet bypass valve, one end of the bypass pipe is communicated with an exhaust pipe of an intercooler, the other end of the bypass pipe is communicated with an air inlet pipe of an exhaust gas turbocharger, the air inlet bypass valve is installed on the bypass pipe, the input end of the air inlet bypass valve is connected with the output end of the control unit through a control line, and the control unit coordinates the opening degrees of the air inlet bypass valve and the electric throttle valve according to the operation condition of the gas engine.
Further, the output end of the rotating speed sensor is connected with the first input end of the control unit; an oxygen sensor for measuring the oxygen content in the exhaust gas of the gas engine is arranged on an air inlet pipe of the exhaust gas turbocharger, and the output end of the oxygen sensor is connected with the second input end of the control unit; and a pressure temperature sensor for measuring the pressure and the temperature of the mixed gas in the air inlet manifold is arranged on the air inlet manifold of the gas engine, and the output end of the pressure temperature sensor is connected with the third input end of the control unit.
The air intake control method of the premixing type high-power gas engine comprises the following steps:
1) Detecting the rotating speed n of the gas engine and the load P of the gas engine, and when the rotating speed n of the gas engine is not less than the rated rotating speed ne of the gas engine and the load P of the gas engine is not less than the grid-connected basic load P0 of the gas engine, determining that the gas engine is in grid-connected operation, and entering an air-fuel ratio control mode;
2) Detecting the rotating speed nT of the exhaust gas turbocharger through a rotating speed sensor, and obtaining the mass flow rate Qc of the mixed gas according to a rotating speed-flow MAP graph of the exhaust gas turbocharger;
3) Obtaining a theoretical excess air coefficient lambda 0 according to the detected load P of the gas engine and a load-excess air coefficient MAP graph of the gas engine, determining an actual excess air coefficient lambda 1 according to the oxygen content in the exhaust gas of the gas engine detected by an oxygen sensor, and calculating a target excess air coefficient lambda according to the theoretical excess air coefficient lambda 0 and the actual excess air coefficient lambda 1, wherein the target excess air coefficient lambda is calculated by the following formula:
λ＝|λ0-λ1|；
4) Calculating a target gas mass flow Qg0 according to the mixed gas mass flow Qc and the target excess air coefficient lambda obtained in the step 2), sending a control instruction to a gas flow valve by a control unit, controlling the gas flow valve to a flow opening corresponding to the target gas mass flow Qg0, and feeding back an actual gas mass flow Qg to the control unit by the gas flow valve to realize closed-loop control, wherein the calculation step of the target gas mass flow Qg0 is as follows:
according to the natural gas combustion chemical reaction equation in the gas engine (12): CH4+2o2= co2+2h2o, the stoichiometric ratio of complete combustion of natural gas in air = QaL/Qg0=2 × 29 ÷ 21%/16=17.2, the relationship between the mixture mass flow rate Qc and the actual air mass flow rate Qa and the target gas mass flow rate Qg0 is Qa = Qc-Qg0, and the target excess air coefficient λ = Qa/QaL, as can be seen from the above:
Qa＝QaL×λ
i.e., qaL x λ = Qc-Qg0
And QaL/Qg0=17.2
QaL＝17.2×Qg0
Then Qc-Qg0=17.2 × λ × Qg0
Figure BDA0003892570690000051
From λ = | λ 0- λ 1 |:
Figure BDA0003892570690000052
wherein: qg 0-target gas mass flow;
qc-mass flow of the mixed gas;
qa — actual air mass flow;
QaL-theoretical air mass flow;
λ 0 — theoretical excess air coefficient;
λ 1 — actual excess air coefficient;
λ — target excess air coefficient;
5) The control unit controls the electric throttle valve and the air inlet bypass valve according to the running working condition of the gas engine to realize the control of the rotating speed/load of the gas engine; when the gas engine is in a low-load working condition when the load P is less than or equal to 25 percent of the rated load, the air inlet bypass valve is closed, and the rotating speed/load of the gas engine is independently controlled by the electric throttle valve; when the gas engine is in the working condition of medium and high load when the load P is more than 25% of rated load, the control unit controls the electric throttle valve to be fully opened, and the rotating speed/load of the gas engine is controlled by the air inlet bypass valve alone.
Compared with the prior art, the invention has the advantages that:
1. the technical scheme takes the rotating speed of the exhaust gas turbocharger detected by the rotating speed sensor as an input variable, realizes the control of the air-fuel ratio of the mixed gas entering the gas engine by controlling the opening of the gas flow valve, realizes the direct control of the air-fuel ratio of the premixed gas engine, has simple control, simplifies the calculation process, saves an air flow meter and saves the cost;
2. according to the technical scheme, the bypass unit is arranged, on the premise of adjusting the air-fuel ratio in real time, the amount of the mixed gas is adjusted and controlled in real time according to the operation working conditions of the gas engine, and the automatic adjustment of the flow of the mixed gas under different operation working conditions of the gas engine is met;
3. the technical scheme has the advantages of simple structure and novel design, the rotating speed of the exhaust gas turbocharger can quickly reflect the change of the air flow, the dynamic response is quick, the accuracy of the air-fuel ratio control of the transition working condition of the premixed gas engine is improved, and the economical efficiency and the emission performance of the operation of the gas engine are improved.
Drawings
FIG. 1 is a block diagram of the present invention;
FIG. 2 is a control logic diagram of the system of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1-2 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation. The use of the phrase "comprising one of the elements" does not exclude the presence of other like elements in the process, method, article, or apparatus that comprises the element.
The air inlet control system of the premixing type high-power gas engine comprises an exhaust gas turbocharger 4 and an intercooler 8, wherein the air inlet end of the intercooler is connected with an exhaust pipe of the exhaust gas turbocharger 4, the air inlet pipe of the exhaust gas turbocharger 4 is connected with the exhaust end of a mixer 2, two air inlet ends of the mixer 2 are respectively connected with an air inlet pipe connected with an air filter 1 and a gas inlet pipe provided with a gas flow valve 3, the exhaust pipe of the intercooler 8 is connected with an air inlet main pipe of a gas engine 12, an exhaust main pipe of the gas engine 12 is connected with the air inlet pipe of the exhaust gas turbocharger 4, the gas flow valve 3 and a rotating speed sensor 5 arranged at the rotating speed detection position of the exhaust gas turbocharger 4 are both connected with a control unit 10, the control unit 10 takes the rotating speed of the exhaust gas turbocharger 4 detected by the rotating speed sensor 5 as an input variable, and realizes the control of the air-fuel ratio of mixed gas entering the gas engine 12 by controlling the opening degree of the gas flow valve 3; an electric throttle valve 7 connected with a control unit 10 is installed on an exhaust pipe of the intercooler 8, a bypass unit communicated with the exhaust pipe of the intercooler 8 and an air inlet pipe of the exhaust turbocharger 4 is connected with the control unit 10 through a control line, and the control unit 10 regulates and controls the electric throttle valve 7 and the bypass unit according to the operation condition of the gas engine 12 to realize the regulation of the flow of mixed gas entering the gas engine 12; in the structure, the rotating speed of the exhaust gas turbocharger 4 detected by the rotating speed sensor 5 is used as an input variable, the control of the air-fuel ratio of the mixed gas entering the gas engine 12 is realized by controlling the opening degree of the gas flow valve 3, so that the direct control of the air-fuel ratio of the premixed gas engine 12 is realized, the control is simple, the calculation process is simplified, the air flow meter is omitted, and the cost is saved; the bypass unit is arranged, so that the real-time regulation and control of the consumption of the mixed gas are completed according to the operation working conditions of the gas engine 12 on the premise of real-time adjustment of the air-fuel ratio, and the automatic adjustment of the flow of the mixed gas under different operation working conditions of the gas engine 12 is met;
the bypass unit is specifically as follows: the bypass unit comprises a bypass pipe 13 and an air inlet bypass valve 6, one end of the bypass pipe 13 is communicated with an exhaust pipe of the intercooler 8, the other end of the bypass pipe 13 is communicated with an air inlet pipe of the exhaust turbocharger 4, the air inlet bypass valve 6 is installed on the bypass pipe 13, an input end of the air inlet bypass valve 6 is connected with an output end of the control unit 10 through a control line, and the control unit 10 coordinates the opening degrees of the air inlet bypass valve 6 and the electric throttle valve 7 according to the operation condition of the gas engine 12.
Wherein, the output end of the rotating speed sensor 5 is connected with the first input end of the control unit 10; an oxygen sensor 9 for measuring the oxygen content in the exhaust gas of the gas engine 12 is arranged on an air inlet pipe of the exhaust gas turbocharger 4, and the output end of the oxygen sensor 9 is connected with a second input end of the control unit 10; and a pressure and temperature sensor 11 for measuring the pressure and the temperature of the mixed gas in the intake manifold is mounted on the intake manifold of the gas engine 12, and the output end of the pressure and temperature sensor 11 is connected with the third input end of the control unit 10.
The air intake control method of the premixing type high-power gas engine comprises the following steps:
1) Detecting the rotating speed n of the gas engine 12 and the load P of the gas engine 12, and when the rotating speed n of the gas engine (12) is more than or equal to the rated rotating speed ne of the gas engine 12 and the load P of the gas engine 12 is more than or equal to the grid-connected basic load P0 of the gas engine 12, determining that the gas engine 12 is in grid-connected operation, and entering an air-fuel ratio control mode;
2) Detecting the rotating speed nT of the exhaust gas turbocharger 4 through the rotating speed sensor 5, and obtaining the mass flow rate Qc of the mixed gas according to a rotating speed-flow MAP graph of the exhaust gas turbocharger 4; the mass flow rate Qc of the mixed gas is determined according to a flow value corresponding to the rotating speed of the exhaust gas turbocharger 4 in a rotating speed-flow MAP provided by the manufacturer of the exhaust gas turbocharger 4;
3) A theoretical excess air factor λ 0 is obtained from the detected load P of the gas engine 12 and a load-excess air factor MAP (provided by a gas engine manufacturer) of the gas engine 12, an actual excess air factor λ 1 is determined from the oxygen content in the exhaust gas of the gas engine 12 measured by the oxygen sensor 9, and a target excess air factor λ is calculated from the theoretical excess air factor λ 0 and the actual excess air factor λ 1, the target excess air factor λ being calculated as follows:
λ＝|λ0-λ1|；
4) Calculating a target gas mass flow Qg0 according to the mixed gas mass flow Qc and the target excess air coefficient lambda obtained in the step 2), sending a control instruction to the gas flow valve 3 by the control unit 10, controlling the gas flow valve 3 to a flow opening corresponding to the target gas mass flow Qg0, and feeding back an actual gas mass flow Qg to the control unit 10 by the gas flow valve 3 to realize closed-loop control, wherein the calculation step of the target gas mass flow Qg0 is as follows:
according to the natural gas combustion chemical reaction equation in the gas engine 12: CH4+2o2= co2+2h2o, the stoichiometric ratio of complete combustion of natural gas in air = QaL/Qg0=2 × 29 ÷ 21%/16=17.2, the relationship between the mixture mass flow rate Qc and the actual air mass flow rate Qa and the target gas mass flow rate Qg0 is Qa = Qc-Qg0, and the target excess air coefficient λ = Qa/QaL, as can be seen from the above:
Qa＝QaL×λ
i.e., qaL × λ = Qc-Qg0
And QaL/Qg0=17.2
QaL＝17.2×Qg0
Then Qc-Qg0=17.2 × λ × Qg0
Figure BDA0003892570690000091
From λ = | λ 0- λ 1 |:
Figure BDA0003892570690000092
wherein: qg 0-target gas mass flow;
qc-mass flow of the mixed gas;
qa — actual air mass flow;
QaL-theoretical air mass flow;
λ 0 — theoretical excess air coefficient;
λ 1 — actual excess air coefficient;
λ — target excess air coefficient;
5) The control unit 10 controls the electric throttle valve 7 and the intake bypass valve 6 according to the operation condition of the gas engine 12 to realize the control of the rotating speed/load of the gas engine 12; when the gas engine 12 is in a low-load working condition when the load P is less than or equal to 25 percent of the rated load, the air inlet bypass valve 6 is closed, and the rotating speed/load of the gas engine 12 is independently controlled by the electric throttle valve 7; when the gas engine 12 is in the middle and high load working condition when the load P is more than 25% of the rated load, the control unit 10 controls the electric throttle valve 7 to be fully opened, and the rotating speed/load of the gas engine 12 is controlled by the intake bypass valve 6 alone.
The working principle is as follows: the gas is mixed with the air passing through the air filter 1 in the mixer 2 through the gas flow valve 3 to form mixed gas, then enters the exhaust gas turbocharger 4 for pressurization, is cooled by the intercooler 8, enters the air inlet main pipe of the gas engine 12 after being controlled by the electric throttle valve 7, and then enters the cylinder for ignition, combustion and work doing.
The rotation speed sensor 5 is used for measuring the rotation speed of the exhaust gas turbocharger 4, the oxygen sensor 9 is used for measuring the oxygen content (namely the actual excess air coefficient lambda) in the exhaust gas discharged by the gas engine 12, the pressure and temperature sensor 11 is used for measuring the pressure and temperature of the mixed gas in the air inlet main pipe of the gas engine 12, the signals are all connected into the control unit 10 (namely a gas engine control unit ECU), the control unit 10 sends out instructions to control the gas flow valve 3 to control the air-fuel ratio, and the electric throttle valve 7 and the air inlet bypass valve 6 are coordinately controlled to realize the rotation speed/load control of the gas engine; under the working conditions of starting and low load, the rotating speed/load of the gas engine is controlled by the electric throttle valve 7 alone, and under the working conditions of medium and high load, the electric throttle valve 7 is fully opened, and the rotating speed/load is controlled by the air inlet bypass valve 6; since the intake pressure and temperature can reflect the amount of mixture entering the cylinder, directly affecting the gas engine speed/load control, it can be used as a feedback signal for closed-loop speed/load control.
The rotating speed of the exhaust gas turbocharger 4 is measured by the rotating speed increasing sensor 5, the air quantity entering the mixer 2 can be directly obtained according to the rotating speed-flow characteristic curve of the exhaust gas turbocharger, the control unit 10 controls the gas flow valve 3 to adjust the gas flow entering the mixer 2, and therefore the air-fuel ratio is controlled, and the air-fuel ratio closed-loop control is achieved by combining signals of the oxygen sensor 9; during transient engine operation conditions, the speed of the exhaust gas turbocharger 4 will respond quickly to engine speed/load changes and can directly affect the amount of air entering the mixer 2, and thus the air-fuel ratio of the gas engine; the control software related in the technical scheme can be realized by a program with the soft flow number of 2022R11L1703312 named as a premixing type high-power gas engine air-fuel ratio control system, and the automatic and accurate control of the air-fuel ratio is realized.
The technical scheme has the advantages of simple structure and novel design, the rotating speed of the exhaust gas turbocharger can quickly reflect the change of the air flow, the dynamic response is quick, the accuracy of the air-fuel ratio control of the transition working condition of the premixed gas engine is improved, and the economical efficiency and the emission performance of the operation of the gas engine are improved.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it is to be understood that all embodiments may be combined as appropriate by one of ordinary skill in the art to form other embodiments as will be apparent to those of skill in the art from the description herein.

Claims (4)

1. An air inlet control system of a premixing type high-power gas engine is characterized in that: the device comprises an exhaust gas turbocharger (4) and an intercooler (8) with an air inlet end connected with an exhaust pipe of the exhaust gas turbocharger (4), wherein an air inlet pipe of the exhaust gas turbocharger (4) is connected with an exhaust end of a mixer (2), two air inlet ends of the mixer (2) are respectively connected with an air inlet pipe connected with an air filter (1) and a gas inlet pipe provided with a gas flow valve (3), an exhaust pipe of the intercooler (8) is connected with an air inlet main pipe of a gas engine (12), an exhaust main pipe of the gas engine (12) is connected with an air inlet pipe of the exhaust gas turbocharger (4), the gas flow valve (3) and a rotating speed sensor (5) arranged at a rotating speed detection position of the exhaust gas turbocharger (4) are both connected with a control unit (10), the control unit (10) takes the rotating speed of the exhaust gas turbocharger (4) detected by the rotating speed sensor (5) as an input variable, and controls the air-fuel ratio of mixed gas entering the gas engine (12) by controlling the opening degree of the gas flow valve (3); the device is characterized in that an electric throttle valve (7) connected with a control unit (10) is installed on an exhaust pipe of the intercooler (8), a bypass unit communicated with the exhaust pipe of the intercooler (8) and an air inlet pipe of the exhaust gas turbocharger (4) is connected with the control unit (10) through a control line, and the control unit (10) regulates and controls the electric throttle valve (7) and the bypass unit according to the operation condition of the gas engine (12) to realize the regulation of the flow of mixed gas entering the gas engine (12).
2. The intake control system of the premixed high power gas engine as claimed in claim 1, wherein: the bypass unit comprises a bypass pipe (13) and an air inlet bypass valve (6), one end of the bypass pipe (13) is communicated with an exhaust pipe of the intercooler (8), the other end of the bypass pipe (13) is communicated with an air inlet pipe of the exhaust gas turbocharger (4), the air inlet bypass valve (6) is installed on the bypass pipe (13), an input end of the air inlet bypass valve (6) is connected with an output end of the control unit (10) through a control line, and the control unit (10) coordinates the opening degrees of the air inlet bypass valve (6) and the electric throttle valve (7) according to the operation condition of the gas engine (12).
3. The intake control system of the premixed high power gas engine as claimed in claim 2, wherein: the output end of the rotating speed sensor (5) is connected with the first input end of the control unit (10); an oxygen sensor (9) for measuring the oxygen content in the exhaust gas of the gas engine (12) is mounted on an air inlet pipe of the exhaust gas turbocharger (4), and the output end of the oxygen sensor (9) is connected with the second input end of the control unit (10); and a pressure temperature sensor (11) for measuring the pressure and the temperature of the mixed gas in the air inlet main pipe is arranged on the air inlet main pipe of the gas engine (12), and the output end of the pressure temperature sensor (11) is connected with the third input end of the control unit (10).
4. The air intake control method of the premixing type high-power gas engine is characterized by comprising the following steps:
1) Detecting the rotating speed n of the gas engine (12) and the load P of the gas engine (12), and when the rotating speed n of the gas engine (12) is not less than the rated rotating speed ne of the gas engine (12) and the load P of the gas engine (12) is not less than the grid-connected basic load P0 of the gas engine (12), determining that the gas engine (12) is in grid-connected operation, and entering an air-fuel ratio control mode;
2) Detecting the rotating speed nT of the exhaust gas turbocharger (4) through a rotating speed sensor (5), and obtaining a mixed gas mass flow rate Qc according to a rotating speed-flow rate MAP graph of the exhaust gas turbocharger (4);
3) A theoretical excess air ratio lambda 0 is obtained from the detected load P of the gas engine (12) and a load-excess air ratio MAP of the gas engine (12), an actual excess air ratio lambda 1 is determined from the oxygen content in the exhaust gas of the gas engine (12) detected by the oxygen sensor (9), and a target excess air ratio lambda is calculated from the theoretical excess air ratio lambda 0 and the actual excess air ratio lambda 1, the target excess air ratio lambda being calculated as follows:
λ＝|λ0-λ1|；
4) Calculating a target gas mass flow Qg0 according to the mixed gas mass flow Qc and the target excess air coefficient lambda obtained in the step 2), sending a control instruction to the gas flow valve (3) by the control unit (10), controlling the gas flow valve (3) to a flow opening corresponding to the target gas mass flow Qg0, and feeding back an actual gas mass flow Qg to the control unit (10) by the gas flow valve (3) to realize closed-loop control, wherein the calculation step of the target gas mass flow Qg0 is as follows:
according to the natural gas combustion chemical reaction equation in the gas engine (12): CH4+2o2= co2+2h2o, the stoichiometric ratio of complete combustion of natural gas in air = QaL/Qg0=2 × 29 ÷ 21%/16=17.2, the relationship between the mixture mass flow rate Qc and the actual air mass flow rate Qa and the target gas mass flow rate Qg0 is Qa = Qc-Qg0, and the target excess air coefficient λ = Qa/QaL, as can be seen from the above:
Qa＝QaL×λ
i.e., qaL × λ = Qc-Qg0
And QaL/Qg0=17.2
QaL＝17.2×Qg0
Then Qc-Qg0=17.2 × λ × Qg0
Figure FDA0003892570680000031
From λ = | λ 0- λ 1 |:
Figure FDA0003892570680000032
wherein: qg 0-target gas mass flow;
qc-mass flow of the mixed gas;
qa — actual air mass flow;
QaL-theoretical air mass flow;
λ 0 — theoretical excess air coefficient;
λ 1 — actual excess air coefficient;
λ — target excess air coefficient;
5) The control unit (10) controls the electric throttle valve (7) and the intake bypass valve (6) according to the operation condition of the gas engine (12) to realize the control of the rotating speed/load of the gas engine (12); when the gas engine (12) is in a low-load working condition when the load P is less than or equal to 25 percent of rated load, the air inlet bypass valve (6) is closed, and the rotating speed/load of the gas engine (12) is independently controlled by the electric throttle valve (7); when the gas engine (12) is in a medium-high load working condition when the load P is larger than 25% of the rated load, the control unit (10) controls the electric throttle valve (7) to be fully opened, and the rotating speed/load of the gas engine (12) is independently controlled by the intake bypass valve (6).
CN202211264717.8A 2022-10-17 2022-10-17 Air inlet control system and method of premixed high-power gas engine Pending CN115539228A (en)

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Citations (8)

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JPH0539728A (en) * 1991-08-06 1993-02-19 Tokyo Gas Co Ltd Air-fuel ratio control method for gas engine
CN102493884A (en) * 2011-12-23 2012-06-13 重庆潍柴发动机厂 Gas inlet control method for large-power gas engine
JP2013087716A (en) * 2011-10-20 2013-05-13 Kansai Electric Power Co Inc:The Control device of premixed type gas engine, control method of premixed type gas engine, and premixed type gas engine system
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JP2019094908A (en) * 2019-03-28 2019-06-20 国立研究開発法人 海上・港湾・航空技術研究所 Air-fuel ratio control device of gas engine, and ship equipped with gas engine with air-fuel ratio control device
CN112664356A (en) * 2020-12-03 2021-04-16 西安科美动力科技有限公司 Gas engine branch air inlet control device and control method thereof
CN114635785A (en) * 2022-03-04 2022-06-17 潍柴动力股份有限公司 Gas machine, control method and device and gas machine system
CN218439547U (en) * 2022-10-17 2023-02-03 陕西柴油机重工有限公司 Air inlet control system of premixed high-power gas engine

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0539728A (en) * 1991-08-06 1993-02-19 Tokyo Gas Co Ltd Air-fuel ratio control method for gas engine
JP2013087716A (en) * 2011-10-20 2013-05-13 Kansai Electric Power Co Inc:The Control device of premixed type gas engine, control method of premixed type gas engine, and premixed type gas engine system
CN102493884A (en) * 2011-12-23 2012-06-13 重庆潍柴发动机厂 Gas inlet control method for large-power gas engine
JP2017110566A (en) * 2015-12-16 2017-06-22 Ｊｆｅエンジニアリング株式会社 Control method and device of gas engine, and gas engine
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CN112664356A (en) * 2020-12-03 2021-04-16 西安科美动力科技有限公司 Gas engine branch air inlet control device and control method thereof
CN114635785A (en) * 2022-03-04 2022-06-17 潍柴动力股份有限公司 Gas machine, control method and device and gas machine system
CN218439547U (en) * 2022-10-17 2023-02-03 陕西柴油机重工有限公司 Air inlet control system of premixed high-power gas engine

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