Large-scale engine SCR denitration method and system

Abstract

The invention provides a large-scale engine SCR denitration method and system. According to the invention, an SCR bale is positioned between a turbocharger and the engine to solve the problems that the SCR bale is positioned behind the turbocharger, so that the back pressure of the engine is too high, and the engine efficiency is affected in the prior art, as well as the temperature of flue gas flowing into the SCR is too low; the large-scale engine, especially a peculiar scavenging box of a marine two-stroke engine is adopted, parts of air in the scavenging box is directly bypassed to the upstream of the turbocharger, so that intake air-fuel ratio in a cylinder of the engine is lowered, the cylinder pressure is reduced, and the combustion of fuel is relatively insufficient, which increase the discharge temperature and greatly improve the efficiency of denitration.

Description

technical field [0001] The invention relates to an engine exhaust system, in particular to an exhaust emission control system of a large engine. Background technique [0002] For some large engines, especially marine engines, the exhaust temperature is often lower than the temperature range of 280°C to 400°C where the SCR catalyst is more active, which makes the NOx in the exhaust gas not fully converted. At the same time, because the fuel of large engines is mostly HFO, with high sulfur content, there are many particulate matter in the exhaust gas generated by combustion, which will easily block the SCR catalyst and increase the back pressure accordingly. At present, there are many methods for increasing the exhaust gas temperature, all of which are to use additional heating devices or heat preservation devices to heat or insulate the exhaust gas. For example, in the Chinese patent with the publication number CN101514651, one or more The above heat insulation coating can r...

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is to provide a large-scale engine SCR denitrification method and its system, which can use the engine itself to more effectively adjust and increase the exhaust temperature of large-scale engines, and effectively solve the problem of SCR catalyst clogging and traditional SCR denitrification. The problem of increased engine back pressure caused by placement after the turbocharger

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