Multistage parallel SCR system

Abstract

The invention discloses a multistage parallel SCR system. The multistage parallel SCR system comprises a gas inlet unit, a reaction unit and a gas outlet unit which are sequentially connected in series, wherein a plurality of reaction channels are arranged in the reaction unit; a plurality of distribution branch tubes, which correspond to the reaction channels, are arranged on the gas inlet unit;the distribution branch tubes communicate to the same gas inlet of the gas inlet unit; a plurality of confluence branch tubes, which correspond to the reaction channels, are arranged on the gas outletunit; and the confluence branch tubes communicate to the same gas outlet of the gas outlet unit. Large-flow tail gas flow is distributed into the reaction channels through the distribution branch tubes of the gas inlet unit, so that tail gas flow in single reaction channel is correspondingly reduced, and therefore, the barrel body cross section dimension of single reaction channel can be correspondingly reduced, speed uniformity of tail gas flow is controlled easier, other-flow-speed distribution uniformity is high, urea crystallization risk is reduced, performance of a post-treatment systemis ensured, and conversion efficiency of nitric oxides is improved.

Description

technical field [0001] The invention relates to the technical field of marine engine exhaust post-treatment, in particular to a marine multi-stage parallel SCR system. Background technique [0002] The prosperity and development of the shipping industry is a powerful driving force to promote my country's economic development, but at the same time, the pressure and challenges brought by the air pollution emissions from ships to air quality should not be underestimated. Ship engines are mainly diesel engines. With the continuous development of the shipping industry, the exhaust gas from marine diesel engines is increasingly polluting the atmospheric environment. The nitrogen oxides (NO X ) is one of the main sources of air pollution. In order to reduce the pollution of diesel engine emissions to the atmosphere, it is necessary to treat the exhaust emissions of marine diesel engines. Marine diesel engines usually use Selective Catalytic Reduction (SCR) to post-treat exhaust em...

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Problems solved by technology

[0004] In view of the disadvantages of the above-mentioned existing marine single-channel and single-nozzle SCR systems, such as poor gas flow velocity distribution, easy formation of urea crystals, poor mixing uniformity of airflow, and low conversion efficiency of nitrogen oxides, the applicant provides a SCR system with a reasonable structure. The marine multi-stage parallel SCR system has good gas flow rate distribution uniformity, low risk of urea crystallization, good gas flow mixing uniformity, and high conversion efficiency of nitrogen oxides

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