Large two-stroke diesel engine with an exhaust gas purification system

Abstract

The invention relates to a crosshead type large-sized turbocharging two-stroke internal combustion engine, which comprises a plurality of cylinders. Each cylinder is connected to an exhaust gas receiver. A selective catalytic reduction reactor is arranged on the downstream of the exhaust gas receiver. The outlet of the selective catalytic reduction reactor is connected to a turbine of a turbocharger through an exhaust pipe. The turbine drives a compressor of the turbocharger. The compressor sends scavenging air through a scavenging air path to a scavenging air receiver which is connected to the plural cylinders. An auxiliary blower on the scavenging air path assists the compressor in a low-load condition. A controllable bypass pipeline extends from the scavenging air receiver to the exhaust pipe. In a low engine load condition, controlled scavenging air flow is guided from the scavenging air receiver to an exhaust pipe part located on the downstream of the selective catalytic reduction reactor and the upstream of the turbine of the turbocharger. The above-mentioned measure makes the temperature of the exhaust gas entering the selective catalytic reduction reactor increased.

Description

technical field [0001] The present invention relates to a large crosshead turbocharged two-stroke internal combustion piston engine, preferably a diesel engine with an exhaust gas purification system, especially a crosshead large two-stroke crosshead with a selective catalytic reduction reactor Diesel engines. Background technique [0002] Large two-stroke engines of the crosshead type are commonly used in the propulsion systems of large ships or as prime movers in power plants. Emissions requirements have been and will become more difficult to meet, especially with respect to mononitrogen oxides (NO x )s level. [0003] The use of selective catalytic reduction (SCR) reactors is known for assisting diesel engines in reducing NO x emissions measures. A minimum temperature of about 300 to 350°C for the exhaust gas entering the SCR converter is required for proper operation of the SCR reactor. [0004] However, due to the nature of two-stroke turbocharged engines, exhaust ...

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Problems solved by technology

[0004] However, due to the nature of two-stroke turbocharged engines, exhaust gas temperatures at low engine loads (e.g. below 40% of the maximum continuous power associated with the engine) are relatively low, i.e., too low for the exhaust gas to operate in the SCR converted in the reactor

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