EGR (Exhaust Gas Recirculation) system used for marine medium-speed diesel engine

Abstract

The invention discloses an EGR (Exhaust Gas Recirculation) system used for a marine medium-speed diesel engine. The EGR system comprises an exhaust pipeline, an EGR pipeline, an EGR by-pass pipeline, an EGR mixer and an exhaust gas by-pass pipeline, wherein an EGR valve, an EGR one-way valve and an EGR cooler are mounted on the EGR pipeline; the EGR valve is used for opening and closing the EGR pipeline; the EGR one-way valve is used for stopping air from flowing into the EGR pipeline; the EGR cooler is used for reducing the temperature of gas mixed with exhaust gas and air; an EGR by-pass valve is mounted on the EGR by-pass pipeline and is used for controlling the flow of exhaust gas which flows to the EGR by-pass pipeline and the EGR pipeline; an exhaust gas by-pass valve is mounted on the exhaust gas by-pass pipeline and is used for controlling the flow of exhaust gas which passes through a turbocharger. Through adjusting the opening and closing of the EGR by-pass valve, exhausted gas enters a cylinder again, larger intake and discharge reverse pressure difference of the marine medium-speed diesel engine is overcome, and the NOx discharge is reduced.

Description

technical field [0001] The invention relates to an exhaust gas recirculation system, in particular to an EGR system for a marine medium-speed diesel engine. Background technique [0002] Exhaust gas recirculation EGR (Exhaust Gas Recirculation) technology is to reintroduce a certain amount of combustion exhaust gas into the engine cylinder in a certain way to increase the proportion of inert gas (water vapor, nitrogen and carbon dioxide, etc.) in the intake air in the cylinder , because the inert gas has a higher specific heat capacity, the specific heat capacity of the intake air containing a higher proportion of inert gas increases, thereby reducing the maximum combustion temperature in the combustion process and suppressing NO x generation. [0003] At present, high-pressure EGR systems are widely used on small diesel engines, but high-pressure EGR systems are not suitable for marine medium-speed diesel engines. For example, patent CN102797595A proposes to introduce the...

AI Technical Summary

Problems solved by technology

For example, U.S. Patent No. 5,564,275 discloses a high-pressure EGR system suitable for high-pressure diesel engines. The system is equipped with an additional EGR supercharger, and the exhaust gas is expanded in the turbine to drive the compressor to supercharge the EGR. To overcome the pressure deficit of intake and exhaust, but the pipeline design and control system of this system are relatively complicated. In addition, the working medium of the EGR turbocharger compressor is the exhaust gas of a high-temperature and high-pressure diesel engine. At present, there is no mature and reliable product in the market. This product appears on the Internet, and its cost will be very high due to its special use environment

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