Performance Optimization of High-pressure SCR System in a Marine Diesel. Part II: Catalytic Reduction and Process

Zhu, Yuanqing; Zhang, Rongpei; Zhou, Song; Huang, Chunan; Feng, Yongming; Shreka, Majed; Zhang, Chaolei

doi:10.1007/s11244-018-1088-x

Cited by 13 publications

(5 citation statements)

References 18 publications

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“…Depending on their location upstream or downstream of the turbocharger in marine diesel engines, SCR systems are divided into high-pressure and low-pressure units. Operating at about 4 bar, the former is usually installed in the engine room of the ship, just after the exhaust manifold. − In the second case, the system is placed on the low-pressure line to the stack where the exhaust gas pressure drops to about 0.6 bar in the case of high-speed marine engines. , Ammonia sulfate formation is a challenging aspect of the use of SCR systems when ships burn high sulfur fuels. For a fuel with a given sulfur content, a preferred practical solution is to keep the exhaust gas temperature high enough to prevent the formation of ammonia sulfate (see Figure ).…”

Section: Exhaust Gas Cleaning Systems (Egcs)mentioning

confidence: 99%

Mitigation of Ship Emissions: Overview of Recent Trends

Sarbanha

Larachi

Taghavi

et al. 2023

Ind. Eng. Chem. Res.

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The urgency of reducing flue gas pollution in maritime transport makes it necessary to take a holistic view of its sustainability and environmental impacts. Among the approaches to reducing ship exhaust emissions, marinized gas scrubbers, given their ability to be retrofitted to existing ships, are a central element in the tradeoff against the use of expensive low-sulfur fuels. However, compounding this issue, the priority of reducing greenhouse gas (GHG) emissions in the coming decades poses new challenges to emissions compliance. The use of exhaust gas cleaning systems to remove SO X , NO X , and particulate matter (PM) emissions will be enhanced in the short to medium term by GHG reductions. In this study, the different types of scrubbers for seaborne operation and the potential risks associated with their secondary emissions will be critically reviewed. In addition, NO X reduction systems and recent efforts to reduce CO 2 through onboard carbon capture systems or alternative fuel combustion will also be covered.

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Section: Exhaust Gas Cleaning Systems (Egcs)mentioning

confidence: 99%

Mitigation of Ship Emissions: Overview of Recent Trends

Sarbanha

Larachi

Taghavi

et al. 2023

Ind. Eng. Chem. Res.

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“…A SCR reaction is a kind of gas-solid multiphase reaction, which occurs on the surface of the catalyst and mainly includes the standard SCR reaction, the fast SCR reaction, the slow SCR reaction, and the side reaction, respectively [6,7]. Due to the oxygen-enriched combustion of the diesel engines, the exhaust gas contains a large amount of NO.…”

Section: Of 22mentioning

confidence: 99%

“…Mathias Magnusson [8] believes that the formation of ammonium sulfate in the marine vanadium oxide catalysts can be relieved or avoided when the temperature is high enough (over 300 • C) and also while the space velocity (below 12,200 h −1 ) and the SOx concentration are low enough. Currently, there are few studies on the catalysts under the conditions of marine diesel engine exhaust gas [6,7,[9][10][11]. Nevertheless, studies on the sulfur poisoning of the catalyst samples have been carried out under laboratory conditions [12][13][14][15][16][17][18].…”

Section: Of 22mentioning

confidence: 99%

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Ammonium-Salt Formation and Catalyst Deactivation in the SCR System for a Marine Diesel Engine

et al. 2018

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Due to the low temperature and complex composition of the exhaust gas of the marine diesel engine, the working requirements of the selective catalytic reduction (SCR) catalyst cannot be met directly. Moreover, ammonium sulfate, ammonium nitrate, and other ammonium deposits are formed at low temperatures, which block the surface or the pore channels of the SCR catalyst, thereby resulting in its reduction or even its loss of activity. Considering the difficulty of the marine diesel engine bench test and the limitation of the catalyst sample test, a one-dimensional simulation model of the SCR system was built in this paper. In addition, the deactivation reaction process of the ammonium salt in the SCR system and its influencing factors were studied. Based on the gas phase and the surface reaction kinetics, the models of the urea decomposition, the surface denitrification, the nitrate deactivation, and the sulfate deactivation were both constructed and verified in terms of accuracy. Moreover, the formation/decomposition reaction pathway and the catalytic deactivation of ammonium nitrate and ammonium bisulfate, as well as the composition concentration and the exhaust gas temperature range were correspondingly clarified. The results showed that within a certain range, the increase of the NO2/NOx ratio was conducive to the fast SCR reaction and the NH4NO3 formation’s reaction. Increasing the exhaust gas temperature also raised the NO2/NOx ratio, which was beneficial to both the fast SCR reaction and the NH4NO3 decomposition reaction, respectively. Furthermore, the influence of the SO2 concentration on the denitrification efficiency decreased with the increase of the exhaust gas temperature because of increasing SCR reaction rate and reversibility of ammonia sulfate formation, and when the temperature of the exhaust gas was higher than 350 °C, the activity of the catalyst was almost unaffected by ammonia sulfate.

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“…Zhu et al. 15–19 has been working on SCR for years and have obtained some satisfactory results. However, detailed change processes, especially in the exhaust flow of marine diesel, cannot be described only using overall reaction pathways, so elementary gas–solid reaction pathways should be coupled to analyze the reaction kinetics of the catalytic process.…”

Section: Introductionmentioning

confidence: 99%

Reaction mechanism and chemical kinetics of NH₃-NO/NO₂-SCR system with vanadium-based catalyst under marine diesel exhaust conditions

Wang

Zhu

Zhou

2019

Proceedings of the Institution of Mechanical Engineers, Part A:

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As one of the most effective NOx emission removing technologies to meet the Tier III limitation by International Maritime Organization, urea-selective catalytic reduction (SCR) technology is starting to be used in two-stroke marine diesel engines. Based on the two-cycle catalytic mechanism proposed by Topsoe, in combination with the exhaust characteristics of the marine diesel, expansion studies on detailed SCR reaction model were carried out in this paper. According to the temperature dependence of reaction pathway, SCR reaction model was divided into three parts: low temperature reaction pathway, standard SCR reaction pathway, and high temperature oxidation pathways, and an expanded NH3-NO/NO2-SCR reaction model for V2O5 catalyst was proposed in the paper. In order to verify the accuracy of the expanded SCR reaction model, simulating and testing studies of SCR reaction under marine diesel conditions were carried out with a commercial extruded V2O5/TiO2 catalyst. The simulation values are agreed well with experimental values at 150–500 ℃, and kinetics characteristics of SCR reaction process under V2O5/TiO2 catalyst can be predicted accurately with the expanded NH3-NO/NO2-SCR reaction model.

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Performance Optimization of High-pressure SCR System in a Marine Diesel. Part II: Catalytic Reduction and Process

Cited by 13 publications

References 18 publications

Mitigation of Ship Emissions: Overview of Recent Trends

Mitigation of Ship Emissions: Overview of Recent Trends

Ammonium-Salt Formation and Catalyst Deactivation in the SCR System for a Marine Diesel Engine

Reaction mechanism and chemical kinetics of NH₃-NO/NO₂-SCR system with vanadium-based catalyst under marine diesel exhaust conditions

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Performance Optimization of High-pressure SCR System in a Marine Diesel. Part II: Catalytic Reduction and Process

Cited by 13 publications

References 18 publications

Mitigation of Ship Emissions: Overview of Recent Trends

Mitigation of Ship Emissions: Overview of Recent Trends

Ammonium-Salt Formation and Catalyst Deactivation in the SCR System for a Marine Diesel Engine

Reaction mechanism and chemical kinetics of NH3-NO/NO2-SCR system with vanadium-based catalyst under marine diesel exhaust conditions

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Reaction mechanism and chemical kinetics of NH₃-NO/NO₂-SCR system with vanadium-based catalyst under marine diesel exhaust conditions