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CN-122014436-A - Carbon smoke and pollutant emission control system of low-speed two-stroke dual-fuel engine with 460mm cylinder diameter and control method thereof

CN122014436ACN 122014436 ACN122014436 ACN 122014436ACN-122014436-A

Abstract

The invention discloses a control system and a control method for discharging carbon smoke and pollutants of a low-speed two-stroke dual-fuel engine with a cylinder diameter of 460mm, wherein a cylinder head of the engine is provided with a methanol fuel injector and a diesel injector, an included angle between the axis of the nozzle of the diesel injector and the axis of the nozzle of the methanol fuel injector is 30 degrees, diesel oil bundles sprayed by the diesel injector and methanol oil bundles sprayed by the methanol fuel injector are mutually and alternately mixed in a combustion chamber, and the fuel injection proportion is controlled according to the fuel energy, wherein the injection amount of methanol accounts for 95% of the total fuel energy, and the injection amount of diesel oil accounts for 5% of the total fuel energy. The invention realizes reliable ignition, stable combustion and collaborative emission reduction under the substitution of high-proportion methanol through innovative injection system arrangement, accurate fuel control strategy and operation parameter range optimized by system experiments, and is an existing marine powertrain.

Inventors

  • LI QINGBO
  • JIANG HAN
  • LIU YANXIN

Assignees

  • 大连海事大学

Dates

Publication Date
20260512
Application Date
20260312

Claims (9)

  1. 1. The soot and pollutant emission control system of the low-speed two-stroke dual-fuel engine with the 460mm cylinder diameter is characterized in that the engine is a 6-cylinder engine, the cylinder diameter is 460mm, the stroke is 1932mm, the rated rotation speed is 108rpm, and the rated power is 6450kW; a cylinder head of the engine is provided with a fuel injector, wherein the fuel injector is configured to inject fuel into a combustion chamber of the engine; The fuel injector is a methanol fuel injector and a diesel injector; The nozzle axis of the diesel injector and the nozzle axis of the methanol fuel injector are in the same plane, an included angle between the nozzle axis of the diesel injector and the nozzle axis of the methanol fuel injector is 30 degrees, and diesel oil bundles sprayed by the diesel injector and methanol oil bundles sprayed by the methanol fuel injector are mutually and alternately mixed in a combustion chamber to realize mixed injection of double fuel of methanol and diesel.
  2. 2. The system of claim 1, wherein the system is configured to control fuel injection ratio with fuel energy, wherein the injection amount of methanol is 95% of total fuel energy, and the injection amount of diesel is 5% of total fuel energy; the injection pressure of the methanol fuel injector is 800-1000 bar, and the injection pressure of the diesel injector is 500-600 bar; the initial air inlet temperature of the engine is 365K-405K, and the initial air inlet pressure is 0.403 MPa-0.447 MPa.
  3. 3. The system for controlling the emission of soot and pollutants of a low-speed two-stroke dual-fuel engine with a cylinder diameter of 460mm according to claim 1, wherein the diesel injector is connected with a diesel supply unit, and the diesel output end of the diesel supply unit is connected with the diesel injector input end for providing diesel; the methanol fuel injector is connected with a methanol supply unit, and the methanol output end of the methanol supply unit is connected with the input end of the methanol fuel injector and is used for providing methanol.
  4. 4. The system for controlling the emission of soot and pollutants of the low-speed two-stroke dual-fuel engine with the cylinder diameter of 460mm according to claim 1, wherein the methanol supply module comprises a methanol tank and an alcohol supply pipeline, wherein the input end of the alcohol supply pipeline is connected with the methanol tank, and the output end of the alcohol supply pipeline is connected with the methanol fuel injector; the diesel oil supply module comprises a diesel oil tank and an oil supply pipeline, wherein the input end of the oil supply pipeline is connected with the diesel oil tank, and the output end of the oil supply pipeline is connected with the diesel oil injector.
  5. 5. The system for controlling the emission of soot and pollutants of a low-speed two-stroke dual-fuel engine with a cylinder diameter of 460mm according to claim 4, wherein the alcohol supply pipeline is made of methanol corrosion resistant material; The methanol fuel injector adopts a four-hole oil nozzle structure.
  6. 6. A control method for discharging carbon smoke and pollutant of a 460mm cylinder diameter low-speed two-stroke dual-fuel engine, which is characterized in that a control system according to any one of claims 1-5 is used, the method comprises the steps of utilizing a methanol fuel injector to inject methanol into a combustion chamber of the engine at a set injection pressure, wherein the injection amount of the methanol is 95% of the total fuel energy, utilizing a diesel injector to inject diesel into the combustion chamber of the engine at the set injection pressure, the injection amount of the diesel is 5% of the total fuel energy, and the diesel oil bundles injected by the diesel injector and the methanol oil bundles injected by the methanol fuel injector are mutually mixed in the combustion chamber to form mixed fuel, and utilizing diesel to ignite the methanol to realize full combustion.
  7. 7. The method for controlling emission of soot and pollutants of the low-speed two-stroke dual-fuel engine with the cylinder diameter of 460mm according to claim 6, wherein the injection pressure of the methanol fuel injector is 800-1000 bar, and the injection pressure of the diesel injector is 500-600 bar; the initial air inlet temperature of the engine is 365K-405K, and the initial air inlet pressure is 0.403 MPa-0.447 MPa.
  8. 8. A low speed two-stroke dual fuel engine of 460mm bore comprising the engine of claim 1 5 According to any one of the preceding claims the control system.
  9. 9. The 460mm bore low speed two stroke dual fuel engine of claim 8, wherein the engine has a NOx emission of 8g/KWh to 20g/KWh and a soot peak emission factor of 0.5g/KWh to 5g/KWh.

Description

Carbon smoke and pollutant emission control system of low-speed two-stroke dual-fuel engine with 460mm cylinder diameter and control method thereof Technical Field The invention relates to the technical field of engines, in particular to a control system and a control method for carbon smoke and pollutant emission of a low-speed two-stroke dual-fuel engine with a cylinder diameter of 460 mm. Background With the continuous increase of the low-carbon emission reduction requirements of the global shipping industry, the traditional low-speed two-stroke diesel engine faces huge environmental protection pressure. Methanol, which is a clean and renewable marine alternative fuel, has the advantages of convenient storage and transportation, high oxygen content, extremely low sulfur content and the like, and is considered as one of important paths for realizing shipping decarburization. The prior diesel engine is transformed into a methanol dual-fuel engine, and is a realistic technical choice for considering both economy and emission reduction targets. However, the stable and efficient combustion of high-proportion methanol fuel on a low-speed two-stroke engine faces a plurality of technical challenges, namely, firstly, the vaporization latent heat of methanol is extremely high (about 1100 kJ/kg) which is more than 4 times that of diesel, compression ignition is difficult due to low cetane number (about 3-5), the combustion instability, fire and even deflagration phenomenon are easily caused by excessively strong evaporation heat absorption and excessively low local temperature in a cylinder, secondly, the physical and chemical properties of the methanol and the diesel are obviously different, the original engine fuel supply system needs to be subjected to corrosion resistance, leakage prevention and other adaptive transformation, and furthermore, the organization of the methanol combustion process is extremely sensitive to the formation, ignition and combustion phase of mixed gas in the cylinder, and the small change of the initial condition (temperature and pressure) of intake air possibly causes the remarkable fluctuation of combustion efficiency and emission performance. Existing dual fuel retrofit solutions have focused on hardware adaptation of the fuel supply system, or simply fuel substitution, lacking deep coupling optimization for methanol fuel characteristics and low speed two-stroke engine operation. In particular, in the aspects of the arrangement of an injection system, the fuel energy proportioning and the cooperative regulation and control of the initial condition of air intake, a systematic solution is not formed, so that the problems of reduced combustion efficiency, unbalanced emission control, insufficient stability of high-load working conditions and the like are caused in actual operation. Therefore, there is a need to propose a methanol dual fuel retrofit method for a low speed two-stroke diesel engine. Disclosure of Invention The invention aims to overcome the defects in the prior art, and provides a carbon smoke and pollutant emission control system and a control method thereof for a low-speed two-stroke dual-fuel engine with a 460mm cylinder diameter, and reliable ignition, stable combustion and collaborative emission reduction under high-proportion methanol substitution are realized through innovative injection system arrangement, an accurate fuel control strategy and an operation parameter range optimized through system experiments, so that a feasible technical scheme is provided for green upgrading of the existing marine power system. In order to achieve the above purpose, the technical scheme of the invention is as follows: A soot and pollutant emission control system of a 460mm cylinder diameter low-speed two-stroke dual-fuel engine is a 6-cylinder engine, the cylinder diameter is 460mm, the stroke is 1932mm, the rated rotation speed is 108rpm, the rated power is 6450kW, a cylinder head of the engine is provided with a fuel injector, the fuel injector is configured to inject fuel into a combustion chamber of the engine, the fuel injector is a methanol fuel injector and a diesel injector, the nozzle axis of the diesel injector and the nozzle axis of the methanol fuel injector are in the same plane, an included angle between the nozzle axis of the diesel injector and the nozzle axis of the methanol fuel injector is 30 degrees, and diesel oil bundles sprayed by the diesel injector and methanol oil bundles sprayed by the methanol fuel injector are mutually mixed in the combustion chamber, so that mixed injection of methanol and diesel fuel is realized. The invention also discloses a control method for discharging the soot and the pollutants of the low-speed two-stroke dual-fuel engine with the cylinder diameter of 460mm, which uses the control system, and comprises the steps of utilizing a methanol fuel injector to inject methanol into a combustion chamber of the engine at a set injection