Large-sized two-stroke diesel engine having exhaust gas purifying system

Abstract

The invention relates to a large turbocharged two-stroke internal combustion engine of the crosshead type, comprising a plurality of cylinders, each connected to an exhaust receiver. A selective catalytic reduction reactor is arranged downstream of the exhaust gas receiver. An exhaust pipe connects the outlet of the selective catalytic reduction reactor to the turbine of the turbocharger. The turbine drives the compressor of the turbocharger, which delivers the scavenging air to the scavenging air receiver via the scavenging air path. The scavenging receiver is connected to a plurality of cylinders. An auxiliary blower in the scavenging path assists the compressor during low load conditions. A controllable bypass line extends from the scavenging receiver to the exhaust. At low engine loads, a controlled scavenging flow is directed from the scavenging receiver to the exhaust pipe at a location downstream of the selective catalytic reduction reactor and upstream of the turbine of the turbocharger. This measure increases the temperature of the exhaust gas entering the selective catalytic reduction reactor.

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 demands 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, the exhaust...

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Problems solved by technology

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

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