Ship selective catalytic reduction emission-reducing system

Abstract

The invention discloses a ship selective catalytic reduction emission-reducing system which comprises a mixer, wherein the mixer is used for mixing a reducing agent with engine smoke and is connected with a reactor smoke inlet; a reactor comprises a shell, a smoke inlet and a purified gas outlet are arranged on the shell, and a catalyst module is arranged in the shell; and the reducing agent is an urea aqueous solution. The invention has reasonable structure and high working performance; and when the even mixed gas of the reducing agent and the smoke passes through catalyst in the reactor, NOx in the smoke is selectively reduced into harmless nitrogen (N2) and water (H2O), thereby realizing the standard emission of the NOx.

Description

Technical field: [0001] The invention relates to a marine selective catalytic reduction emission reduction system. Background technique: [0002] The air pollution caused by ships has reached a level that cannot be ignored, and has brought increasingly serious impacts on the internal and external environments of ships, especially in ports, straits and some sea areas with dense routes and high ship traffic. major source of pollution in the area. [0003] The International Maritime Organization (IMO) has proposed three-stage requirements to all flag states for the reduction of NOx emissions from ships. From 2011, the Tier II limit value of NOx emission will be implemented, and the Tier III limit value of NOx emission will be implemented in 2016. Because the NOx limit value stipulated by Tier III cannot be achieved by the technical improvement of the engine itself, and all For NOx emission reduction measures, only the engine exhaust after-treatment device SCR can achieve the ...

AI Technical Summary

Problems solved by technology

[0023] 2. The sulfur content of marine fuel oil is high. At present, the sulfur content of a large number of shipping fuel oil in the world is 4.5%, which can be reduced to 3.5% in 2012. The fuel oil higher than 1.5% makes the SCR catalyst temperature reaction window narrow and easy to poison. It cannot meet the needs of marine SCR for efficient NOx reduction;

[0024] 3. The operating conditions of marine engines change frequently. Under low-load conditions, the exhaust temperature of a considerable part of diesel engines is too low, exceeding the minimum reaction temperature allowed by general vanadium-based catalysts, reducing NOx emission reduction efficiency and increasing ammonia slip;

[0025] 4. Domestically produced catalysts used in SCR devices are mostly products for denitrification in power plants, which cannot fully adapt to the characteristics of marine applications;

[0026] 5. Due to the safety requirements of ship navigation, the reductant of SCR system cannot use ammonia reductant commonly used in power plants. Urea solution reductant is the first choice for ship application of SCR. 32.5% urea solution for vehicles cannot be used, so 40% urea solution must be used as the SCR reducing agent for ships;

[0027] 6. International and domestic testing and certification methods for marine SCR system devices have not yet been promulgated, which can only be resolved through the application and testing practice of the first marine SCR

[0028] 7. The performance of domestic independent marine diesel engine products is backward, and the emission reduction performance and reliability of matching SCR system devices are limited

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