Thesis Presentation Beta2

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Thesis Presentation Beta2

  1. 1. KINETIC AND 2-D REACTOR MODELING OF CATALYTIC REDUCTION OF NOx IN A MONOLITH HONEYCOMB REACTOR S.R.Dhanushkodi Graduate Student Process Systems Engineering University of Regina SCR Simulation General information
  2. 2. Need for a System What is SCR ? Need of SCR in saskpower Importance of this study NO x effects Types of NO x  Thermal / fuel / prompt Regulations 2 85-95 LNB with OFA and SCR 50-80 LNB with SCR 75-85 SCR 30-60 SNCR 50-60 Reburn 40-60 LNB + OFA 35-55 Low Nox Burners (LNB) 20-30 Overfire air (OFA) NO Reduction Potential (%) Control Technique
  3. 3. Objectives <ul><li>To kinetically model the reduction reaction </li></ul><ul><li>To carry out comprehensive reactor modeling to simulate the reactor </li></ul><ul><li>To estimate the NOx reduction and the selectivity for the best performing V 2 O 5 /TiO 2 catalysts </li></ul><ul><li>To identify NOx reduction and NH 3 oxidation concentration profile </li></ul>3
  4. 4. Methodology - Phase 1 <ul><ul><li>Mechanism Development </li></ul></ul><ul><li>Development of the power law model </li></ul><ul><li>Proposition of Eley-Rideal and LHHW mechanism </li></ul><ul><li>Estimation of the Kinetic parameters using optimization method </li></ul><ul><li>Development of Matlab code for estimating the kinetic parameters </li></ul>4
  5. 5. <ul><ul><li>Reactor Modeling </li></ul></ul><ul><li>Development of the 2-D model geometry of Honeycomb monolith with wash coat </li></ul><ul><li>Momentum and mass balance for the model </li></ul><ul><li>Discretization of model </li></ul><ul><li>Product distribution </li></ul><ul><li>Estimating the selectivity and Mass transfer limitations </li></ul><ul><li>Comparison of the model results with experimental values. </li></ul>Methodology - Phase 2 5
  6. 6. Approach to the Kinetic study Experimental data taken from Gupta 6 3.T and P for the reactions 250 0 C- 400 o C and 1 atm 1. Stoichiometry 7. Mass transfer limitations 4. Phases of the reactions Gas phase / catalytic 6. Product distribution conversion Reaction information 2. Catalyst V 2 O 5 /TiO 2 monolith 5. Mechanism development and Estimation of Kinetic parameters
  7. 7. Kinetics variation according to Arrangement of SCR (a) Tail end arrangement (b) High dust SCR (c) Low dust SCR 7
  8. 8. Research Scheme N-S Equation Brinkman Diffusion convection 8
  9. 9. Mechanistic model development <ul><li>Power law model </li></ul><ul><li>ER - Gas Phase Reaction </li></ul><ul><li>ER – Adsorbed phase reaction (One active Site Mechanism) </li></ul><ul><li>LHHW- Two active site mechanism </li></ul>9
  10. 10. Power Law Model <ul><li>a, b, and c values </li></ul><ul><ul><li>affected by various process </li></ul></ul><ul><ul><li>qualitative results </li></ul></ul>10
  11. 11. <ul><ul><li>Ammonium ion with Gaseous NO </li></ul></ul><ul><ul><li>Intermediate structure and interaction has been neglected </li></ul></ul>ER - Gas Phase Reaction <ul><ul><li>Step 1 </li></ul></ul><ul><ul><li>Step 2 </li></ul></ul><ul><ul><li>Step 3 </li></ul></ul><ul><ul><li>Step 4 </li></ul></ul>11
  12. 12. <ul><ul><li>Step 1 </li></ul></ul><ul><ul><li>Step 2 </li></ul></ul><ul><ul><li>Step 3 </li></ul></ul><ul><ul><li>Step 4 </li></ul></ul><ul><ul><li>Step 5 </li></ul></ul>ER – Adsorbed phase reaction (One active Site Mechanism) V(+0)  catalyst relative oxidation states 12
  13. 13. <ul><ul><li>Step 1 </li></ul></ul><ul><ul><li>Step 2 </li></ul></ul><ul><ul><li>Step 3 </li></ul></ul><ul><ul><li>Step 4 </li></ul></ul><ul><ul><li>Step 5 </li></ul></ul><ul><ul><li>Step 6 </li></ul></ul>LHHW- Two active site mechanism (Model #8) 13
  14. 14. Models developed 14
  15. 15. Models developed 15
  16. 16. <ul><li>Models 1, 2, 4, 5, 6 have produced not only large AAD% but also failed the t-test. </li></ul><ul><li>Model 3 has 15 % AAD </li></ul><ul><li>Models 7, 8, 10, 12 and 13 have AAD% below 15 </li></ul>Models developed - Results 16
  17. 17. <ul><li>ANOVA test - Excel for 2 factor </li></ul><ul><li>Scheffe Test (1% level)– 4 Models with experimental rate </li></ul><ul><li>Model 8 has no significant difference with Exp.rate </li></ul>ANOVA and Scheffe Test 17 3.366 314.0048995 Experimental –M7 3.366 1.096732095 Experimental –M8 3.366 5.589576712 Experimental -M12 3.366 5.650498844 Experimental -M13 F(1%) Fobs
  18. 18. T-Test <ul><li>T test - Excel </li></ul><ul><li>Mean and SD estimated for </li></ul><ul><li>Model 8 with Exp.rate </li></ul>18 48% > 5% 0.483308 t-test results 310.2738 356.4549 Standard Deviation 2389.93 2418.655 Mean
  19. 19. Parity plot 19
  20. 20. Estimated parameters 20
  21. 21. Model 8 - Behaviour at all temperature 250 o C 350 o C 400 o C 300 o C Stringent Convergence criterion higher ammonia concentration 21
  22. 22. SCR and SCO rate as a function of T SCR rate SCO rate 22
  23. 23. Reactor modeling - FEM model Assumption <ul><li>Steady-state and isothermal conditions </li></ul><ul><li>Laminar flow inside the channel </li></ul><ul><li>Axial diffusion in the fluid phase is neglected </li></ul><ul><li>Negligible pressure drop along the monolith channel </li></ul><ul><li>Mass accumulation in the washcoat is ignored . </li></ul>23 Cylindrical coordinates
  24. 24. [NO] variation along the reactor <ul><li>Catalyst loading </li></ul><ul><li>NH 3 adsorption </li></ul><ul><li>Boundary integral </li></ul><ul><ul><li>60% efficiency </li></ul></ul><ul><li>S varies between </li></ul><ul><li>3.6 and 2.7 along the </li></ul><ul><li>reactor length </li></ul>24
  25. 25. Molar ratio <ul><li>NH 3 slip </li></ul><ul><li>Actual Stoichimetry ratio </li></ul><ul><li>Shut down </li></ul>25
  26. 26. Flow behavior of Species ( a) Bulk flow through pores; (b) diffusion through pores; (c) restricted diffusion 26
  27. 27. Pressure Drop estimation inside monolith <ul><li>Size of monolith Vs flow rate of ammonia and NO </li></ul><ul><li>Mole fraction gradients Vs Washcoat thickness </li></ul>27
  28. 28. Pressure Drop estimation inside monolith <ul><li>Assumptions: </li></ul><ul><li>Rigid Capillary forces </li></ul><ul><li>Plug flow assumed </li></ul><ul><li>Gas plug ∆P ignored </li></ul>28
  29. 29. Mass transfer Limitations <ul><li>Bulk flow to the outer surface of catalyst </li></ul><ul><li>Distribution of active components </li></ul><ul><li>Diffusion of reactants through the catalyst structure to reach inner active sites </li></ul><ul><li>Transfer of oxygen between the reducing and oxidizing sites </li></ul>29
  30. 30. Mass transfer Limitations 30 0.76 1.59 Mass Transfer Limit, Lm, 2.56E-02 3.9E-02 K g m/s 4.2 7.1 Sherwood Number Equation 2 Equation 1
  31. 31. Mass transfer Limitations The diffusion length is  characteristic length scale  increases with the square root of the time  Diffusion length Vs system length 31
  32. 32. Conclusions <ul><ul><li>LHHW-type rate model based on the assumption of dissociative adsorption of NO on active sites as the rate-determining step </li></ul></ul><ul><ul><li>Model # 8 and Model # 9 can be used for designing the pilot plant </li></ul></ul><ul><ul><li>Mechanistic approach helps in finding the residence time for the reactor development </li></ul></ul><ul><ul><li>Pe confirms the diffusion dominant in Y direction flow </li></ul></ul><ul><ul><li>Sh number helps in determining MT film coefficient </li></ul></ul><ul><ul><li>Re number confirms the Laminar flow </li></ul></ul>32
  33. 33. Conclusions <ul><ul><li>Study helps to design monolith catalyst geometrical design </li></ul></ul><ul><ul><li>NO conversion of 60% is possible on time scales of gas flow through the monolith for temperatures around 623 K </li></ul></ul><ul><ul><li>The selectivity parameter vary between 3.3 and 2.4 along the reactor length </li></ul></ul><ul><ul><li>This results helps sizing the SCR plant for saskpower </li></ul></ul>33
  34. 34. Future work <ul><ul><li>A 3-D model could help predicting </li></ul></ul><ul><ul><ul><li>hydrodynamic entrance length, </li></ul></ul></ul><ul><ul><ul><li>the influence of the oxygen concentration, </li></ul></ul></ul><ul><ul><li>Experimental research is required on catalyst design in order to accomplish high conversion. </li></ul></ul><ul><ul><li>A detailed modeling study is required on oxidation of SO 2 to understand the catalyst mechanical specifications. </li></ul></ul>34
  35. 35. Acknowledgement Back to presentation This study was funded by the Natural Science and Engineering Research Council of Canada through a research grant to Dr. Mahinpey
  36. 36. General information KINETIC AND 2-D REACTOR MODELING OF CATALYTIC REDUCTION OF NOx IN A MONOLITH HONEYCOMB REACTOR Title: Pollution control Equipment –Process system engineering Topic discipline: NOx, E-R mechanism, Brinkman equation, Naviers stokes equation,Selective catalytic reaction, V 2 O 5 /TiO 2 Keywords: Shankar raman Dhanushkodi Presenter Selective catalytic reduction (SCR) is one of the best NOx reduction technologies. The present study discusses the development of a mechanistic kinetic model for SCR of NOx to describe the kinetics of V2O5/TiO2 catalysis at atmospheric pressure and a temperature of 623K in a monolith honeycomb reactor. This work describes the details of a predictive model specifically designed for SCR used in the experimental study. Abstract: The author has copyright to the module Copyright information: 25 minutes Estimated time to complete: - Software requirements:
  37. 37. Gratitude
  38. 38. Publications <ul><li>S.R.Dhanushkodi., N.Mahinpey and M. Wilson, 2008. Kinetic and 2D reactor modeling for simulation of the catalytic reduction of NOx in the monolith honeycomb reactor. Process Safety and Environmental Protection, 86(4), pp. 303-309. </li></ul><ul><li>S.R.Dhanushkodi., N.Mahinpey., A.Srinivasan and M.Wilson., 2008. Life Cycle Analysis of Fuel Cell Technology. Journal of Environmental Informatics, 11(1), pp. 36-44. </li></ul><ul><li>S.R.Dhanushkodi, N.Mahinpey, and M.Wilson., 2008. Optimization of Kinetic parameters and 2-D Reactor Modeling for Simulation of the catalytic Reduction of NOx in the Monolith Honeycomb Reactor. Green Science and Technology Conference 2008. ttp://www.uregina.ca/greenconference2008/pdf/Abstracts.pdf accessed on 6 th September 2008 </li></ul><ul><li>S.R.Dhanushkodi., N.Mahinpey., and M.Wilson., 2008. SCR of NOx, University of Regina graduate and undergraduate conference, Regina. http://www.uregina.ca/gradconference/index.php?id=46 accessed on 6 th September 2008 </li></ul><ul><li>A.Srinivasan and S.R.Dhanushkodi .,2008 Concepts in Industrial Ecology, University of Regina graduate and undergraduate conference, Regina. http://www.uregina.ca/gradconference/index.php?id=46 accessed on 6 th September 2008 </li></ul><ul><li>M.Pulikesi., T.Mani., S.R.Dhanushkodi., N. Mahinpey, S.Sivanesan 2008 Special Trend of surface ozone observed at industrial site, in Chennai, University of Regina graduate and undergraduate conference, Regina. http://www.uregina.ca/gradconference/index.php?id=46 accessed on 6 th September 2008 </li></ul><ul><li>S.R.Dhanushkodi ., N.Mahinpey., P.Murugan and M.Wilson, 2007 Kinetic and 2-D reactor modeling for simulation of the catalytic reduction of NOx over V 2 O 5 /TiO 2 by the honey comb reactor. 57th Canadian Society of Chemical Engineering and Oil ands Conference in Edmonton, Alberta. http://abstracts.csche2007.ca/00000055.htm accessed on 6 th September 2008 </li></ul><ul><li>S.R.Dhanushkodi., N.Mahinpey., and M.Wilson,2007, Life Cycle Assessment of stack production and fueling fuel cell. 57th Canadian Society of Chemical Engineering and Oil ands Conference in Edmonton, Alberta. http://abstracts.csche2007.ca/00000057.htm accessed on 6 th September 2008 </li></ul><ul><li>M.Pulikesi. , S.R.Dhanushkodi. , N.Mahinpey and S.Sivanesan 2007 S.Annual Varibility of Surface Ozone at an Urban Coastal Site. 57th Canadian Society of Chemical Engineering and Oil ands Conference in Edmonton, Alberta. http://abstracts.csche2007.ca/00000056.htm accessed on 6 th September 2008 </li></ul><ul><li>N.Mahinpey, M.Wilson , S.R.Dhanushkodi. , 2007 Sustainability and Green engineering: Concepts in Biomass Gasification 57th Canadian Society of Chemical Engineering and Oil ands Conference in Edmonton, Alberta. http://abstracts.csche2007.ca/00000109.htm accessed on 6 th September 2008 </li></ul><ul><li>S.R.Dhanushkodi., N.Mahinpey., A.Srinivasan and M.Wilson., 2007.Environmental impact of fuel cell technology, University of Regina graduate and undergraduate conference, Regina. (Poster Presentation) </li></ul>

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