A large turbocharged two-stroke diesel engine with exhaust gas purification

Abstract

A large turbocharged two-stroke diesel engine with crossheads, said engine having a plurality of cylinders (1) in line, a turbocharger (5) and an SCR reactor (19) upstream of the turbocharger and downstream of an exhaust gas receiver (3) . The exhaust gas receiver (3) is connected to the individual cylinders (1) via respective exhaust ducts (35) that introduce the exhaust gas tangentially and cause a swirl in the exhaust gas inside the exhaust gas receiver (3) . The exhaust gas receiver (3) is provided with an outlet (33) . A unit (42) with plurality of vanes (43) around a central axial duct (47) divides the exhausts gas receiver (3) in a mixing section (48) downstream of the unit and an outlet section (49) upstream of the unit (42) The swirling exhaust gas passes along the vanes (43) on its way from the inixing section (48) to the outlet section (49) and the vanes (43) cause the exhaust gas to lose its swirl and gain pressure. The pressure gain causes a portion of the exhaust gas in the outlet section (49) to flow back to the mixing section (48) via said central duct (47) . The reductant is introduced in the flow in said central duct 47) . A large turbocharged two-stroke diesel engine with an exhaust gas receiver (3) with tangential inlets (35) and a tangential outlet (39) is also disclosed It is suggested that Fig. 4 is published with the abstract.

Description

technical field [0001] The present invention relates to a crosshead large turbocharged two-stroke internal combustion piston engine, preferably a diesel engine with an exhaust gas purification system, in particular, the present invention relates to a diesel engine with a system for purifying NO in the exhaust gas x (nitrogen oxides) SCR (Selective Catalytic Reduction, Selective Catalytic Reduction) reactor crosshead large two-stroke diesel engine. Background technique [0002] Large crosshead two-stroke engines are commonly used in the propulsion systems of large ships or as prime movers in power stations. In particular, for nitrogen oxides (NO x ) levels, the emission requirements have been or will become increasingly difficult to meet. [0003] General awareness of environmental issues is growing rapidly. Emission limits in the form of air pollution at sea are now being discussed within the IMO (International Maritime Organisation). Authorities in various parts of the ...

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Problems solved by technology

[0010] Against this background, it has been proposed to provide SCR systems with complex and thus expensive injection systems for homogeneous distribution of ammonia or urea in the exhaust gas flow and in order to ensure sufficient mixing downstream using special so-called hybrid units, which are usually quite large and bulky

Also, the mixing unit contributes to the overall head loss (pressure loss) of the exhaust system and it equates to a reduction in turbocharger efficiency

In particular, the loss of efficiency in turbochargers is unsatisfactory from the point of view of fuel efficiency

Furthermore, this pressure loss limits the applicability of power turbines driven by wastegate flow (Waste heat recovery - WHR)

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