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Transportforum 2012, January 11-12th
Linköping
NOx Abatement Technique for Marine
Applications
Improved SCR Systems
Mathias Magnusson
PhD Student Department of Shipping and Marine Technology
Sustainable Ship Propulsion
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Outline
• Background
• Paper I:The influence of sulfur dioxide and water on the performance of
a marine SCR catalyst - Method
- Results and Concluding Remarks
• Paper II: A system perspective on practical experiences of marine SCR
installations - Method
- Results and Concluding Remarks
• Final concluding remarks and Outlook
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Background
• Environmental implications of NOx? - Eutrophication
- Acidification
- Contribution to ground level ozone
- Contribution to secondary particulate matter (PM)
• NOx emissions from shipping? - Global level: suggested that approx. 15% of all global anthropogenic NOx emissions
originates from vessels, with approx. 70% occurring within 400 km of land.
- European level: NOx emission from international shipping (EU) is projected to increase by
67% between 2000 and 2020 exceeding the total of all land-based sources in EU-25 in
2020.
- Regional level: NOx emission from vessels in the Baltic Sea during 2007 ~ 122 ktones of
nitrogen Sweden ~ 50 ktones of nitrogen.
- Swedish level: In addition, EMEP 2011 suggests 20% by shipping
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Background
• Incentives and regulations for reduced NOx emission from shipping?
- The Norwegian NOx fund and the Swedish environmentally differentiated fairway dues
- IMO’s Revised MARPOL Annex VI – Reg. 13
Demand for NOx abatement technology!
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Background
• NOx abatement technologies - Primary (combustion); IEM, EGR, Water techniques, LNG…
- Secondary (after-treatment); SCR
• Selective Catalytic Reduction (SCR)
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Method Paper I
• The aim: investigate how sulfur, water and low temperatures affect an SCR
- experimental flow reactor studies
- commercial vanadia-based washcoated urea-SCR catalyst for marine applications
𝑆𝑉 =𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑦 𝑜𝑓 𝑔𝑎𝑠 𝑓𝑙𝑜𝑤
𝑣𝑜𝑙𝑢𝑚𝑒 𝑜𝑓 𝑡𝑒 𝑐𝑎𝑡𝑎𝑙𝑦𝑠𝑡
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Flow reactor studies on SCR-activity as a function of
SO2-concentration
Feed gas composition:
500 ppm NO, 500 ppm
NH3, 8% O2 and 100-
1100 ppm SO2 (350oC
and 12200 h-1)
200 ppm SO2 ≈ 1 wt.% S
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Flow reactor studies on SCR-activity as a function of
temperature (SO2 + H
2O)
Feed gas composition:
500 ppm NO, 500 ppm
NH3, 8 % O2, 500 ppm
SO2 and 4 % H2O (SV
6100 h-1 or 300oC)
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Concluding Remarks Paper I
• In general, the addition of SO2, in the absence of water, promotes NOx
reduction and NH3 conversion along with increased formation of N2O
Formation of new acid sites that improve NH3 adsorption?
• In general, the addition of water, in the absence of SO2, decrease NOx
reduction and NH3 conversion along with reduced formation of N2O
Competitive adsorption on vanadia sites and reduced NH3 oxidation?
• In general, in the presence of both SO2 and water, the activity for NOx
reduction decreases at high concentrations of SO2 (>500 ppm) low
temperatures (< 300oC) and high space velocities (> 12200 h-1)
Complementary studies suggest formation of ammonium sulfates?
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Method Paper II
• The aim: identify important technical, human and organizational conditions
necessary for safe, efficient and sustainable operations of SCR
- Combination of focus group interviews (n=6+2) and individual interviews (n=5)
- Theme:
1) Installation; newbuilding and retrofit, decision making, stakeholder communication
2) Operation, service and maintenance; usability, accessibility, manuals, support, outage
3) Knowledge and training; before and after installation, knowledge transfer
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Practical experiences of marine SCR
installation
• Installation - Corporate environmental image and commercial benefits
- Price is the prime consideration, and flexibility and adaptability second
• Operation, service and maintenance - Urea quality and logistics
- Technical design issues: operating temperature, the space requirements & dimensions, urea
injection, high gas velocities and insufficient mixing of urea and exhaust gases
- Risks to the crew and/or service personnel
- No claims regarding SCR – the owners carry the cost
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Practical experiences of marine SCR
installation
• Knowledge and training - SCR is complex, chemical reactions not well understood
- SCR did not require any special training or knowledge, but some had arranged extra training
for their crew. (Note: hundreds of systems and the SCR is not a safety-critical system!)
- SCR suppliers are interested in improved training
- Cargo owners supposed sufficient training – safe and efficient operation
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Concluding Remarks Paper II
• Clear and concise incentives are needed
Regulations, customer demands or other commercial benefits?
• Design and operational challenges
Supply and quality of urea, urea-injection, exhaust gas
composition due to various marine fuel and lubrication oils?
• Lack of structure for training, development and transfer of knowledge of
SCR (chemical and practical)
Increased risk for occupational accidents and unnecessary
harmful emissions to the environment? (Cost x 3)
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Final Concluding Remarks and Outlook
• SCR is a highly efficient NOx abatement technology, but…
- …certain risks of deactivation, but may be avoided…(exhaust gas temperature, space
velocity and sulfur concentrations)
- …high overall efficiency requires appropriate and sufficient knowledge of how the system
works and what the prerequisites are to achieve successful SCR operation
• Outlook
- Flow reactor experiments using different types of urea?
- Flow reactor experiments with varying diesel exhaust gas compositions?
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Thank you for the attention!
Mathias Magnusson PhD Student
Shipping and Marine Technology
Sustainable Ship Propulsion
Chalmers University of Technology
Phone: +46(0)31-772 36 15
Mobile: +46(0)72-194 87 88
E-mail: [email protected]
Web: www.chalmers.se/smt
