KCP&L LaCygne Unit 1 - CFD Modeling for SCR Optimization

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1 February 5, 2014 KCP&L LaCygne Unit 1 - CFD Mdeling fr SCR Optimizatin EUEC Cnference 2014 Reid Thmas

2 AGENDA KCPL Prblem Statement Flue gas flw maldistributin and excessive flyash pluggage in LaCygne 1 SCR Cmputatinal fluid dynamics (CFD) & Physical Flw Mdeling GSG Graduated Straightening Grid Technlgy Unifrm-Vertical-Nn Recirculating Flw Implementatin and Installatin Summary f Operatinal & Maintenance Results SCR and Mdeling Lessns Learned 2

3 LA CYGNE UNIT 1 KCPL LaCygne Unit 1 Unit 1 is a 815 MWg cyclne fired biler PRB Blend Cal 2 SCR reactrs added t unit in 2007 Cntinuus ash build up in the reactr due t pr flw Finacial impacts f ash build up: Replacement f 8 catalyst layers in 5 years Frced utages fr ash remval Derate due t catalyst dp 3

4 PROBLEM STATEMENT & BASELINE FLOW MODEL GEOMETRY Straightening Grid and Perf Plate Catalyst Trusses Catalyst Supprts Mixer LPA Screen AIG Dampers Symmetry Plane 4

5 EXCESS FLYASH PLUGGAGE LAYER 1 ASH DEPOSIT MAP After 1 year peratin First layer 45% plugged Ash rws nted belw structural supprts 5

6 EXCESSIVE FLYASH PLUGGAGE TURNING VANES 6

7 EXCESSIVE ASH PLUGGAGE TURNING VANES Ash slughs r falls frm turning vanes after startup ΔP escalates fllwing each startup Trend cntinuus frm 2007 t late

8 EXCESS FLYASH PLUGGAGE A-SCR LAYER 2ND SEAL STRIP 8

9 FLYASH ACCUMULATION Excessive ash remval csts Catalyst cleaning was critical path during utages Catalyst replacement csts High catalyst pressure drp, fan pwer, and peratinal derates High NH 3 slip and increased reagent cnsumptin 9

10 COMPUTATIONAL FLUID DYNAMICS (CFD) MODELING

11 CFD MODELING APPROACH & GOALS Fuel Tech prvided CFD mdeling and design services fr KCP&L LaCygne Unit Initial Study t determine rt cause and easy fix 2012 Full Study fr GSG retrfit Design flue gas flw distributin devices capable f imprving the velcity int the catalyst reactr by 40% frm the baseline LaCygne Unit 1 SCR system is symmetric abut the biler centerline, nly ne reactr (the B-side reactr) and ne half f the ecnmizer utlet duct wrk was mdeled 11

12 CFD BASELINE VELOCITY RESULTS STRUCTURE: Truss & Gussets restrict flw t back Egg Crate STRUCTURE disturbs flw t catalyst High and lw spts frm the turning vanes are helped by the straightening grid and perfrated plate but still yield a pr distributin int the 1 st catalyst layer. 12

13 BASELINE RESULTS VELOCITY VECTORS TURNING VANES & RECIRC: Turning Vanes and Perfrated Plate create lw flw and flw recirculatin Vectrs near vanes shw recirculatin areas where ptential ash fallut can ccur. 13

14 ASH BUILDUP AND FLOW RECIRCULATION 14

15 CFD AND EXPERIMENTAL MODELING Multiple CFD runs t reach ptimized slutin 1:12 th Scale Experimental mdel tests f ptimized slutin: Velcity prfiles at catalyst Pressure drp Ash fallut GSG ptimizatin Cnverged results f CFD and experimental mdel 15

16 GSG GRADUATED STRAIGHTENING GRID FLUID DYNAMICS - PATENTED Dramatically Imprves Flue Gas Velcity Distributin withut Increasing Cst, Cmplexity r Cmprmise n Perfrmance Minimizes Angle at which Ash Particles Enter Catalyst, Near Perfectly Vertical Flw int Catalyst Innvative Design Allws fr Higher Flue Gas Velcity, Imprved Operating and Financial Perfrmance via Lnger Catalyst Life and Reduce Dwntime Reductin in Time Required t Tune Ammnia Injectin Grid Higher Flue Gas Velcity Translates int Smaller Crss-sectin and, Lwer Capital Typical Arrangement GSG Arrangement 16

17 CFD FLOW MODELING AND GSG BENEFITS GSG with variable perfrated plate eliminates turning vane and recirculatin zne Structural egg crate members remved GSG 17

18 CFD OPTIMIZED RESULTS (GSG) - VELOCITY 4 Sectins f Perfrated Plate 18

19 OPTIMIZED RUN RESULTS (REACTOR) - VELOCITY Smaller shadws belw beams Catalyst Inlet Velcity 9.5% RMS 19

20 CFD FLOW MODELING BENEFITS & RESULTS Baseline GSG Desired Flw +/- 15% 58% 91% 100% Flw +/- 30% 94% 99% Nt Used RMS 17.5% 9.5% Nt Used 20

21 CONSTRUCTION & IMPLEMENTATION

22 DEMOLITION OF EGG CRATE STRAIGHTENER AND SUPPORTS 22

23 GSG PANEL INSTALLATION 23

24 GSG PANEL INSTALLATION 24

25 OPERATING RESULTS

26 SIGNIFICANT REDUCTION OF ASH BUILDUP AFTER 4 MONTHS Befre Structure slughs and recirculatin causing excessive buildup After Mdified beam internal structures and tent shaped catalyst seals 26

27 RESULTS AT 4 MONTHS LAYER 2 2 ND SEAL STRIP LAYER 2 DIVISION WALL 27

28 2013 FALL OUTAGE Recent fall utage shwed ash build up alng the shared wall: During vacuuming a hard crusted layer f ash was fund attached t the catalyst During the previus utage in January the SCR dampers failed t clse allwing cld mist ambient air t reach the catalyst The flyash absrbed the misture and slidified n the hneycmb layers Once the unit restarted, ash built up n the crusted slid layer causing the cmplete blckage near the shared wall Patented cleaning methd using dry ice was used t remve the hard ash layer. 28

29 GSG BENEFITS FOR LACYGNE UNIT 1 OPERATION Imprved flue gas flw distributin and reduced fly ash accumulatin resulting in: Reduced catalyst replacement csts. The next catalyst layer replacement budgeted after 2019, resulting in ne layer being replaced after 7 years f peratin Reduced fly ash vacuum remval csts/reduced cmplexity f utages Reduced catalyst pressure drp and fan pwer csts eliminating de-rate f Unit Reduced ammnia slip and ammnia reagent csts. The lwer ammnia slip als reduces FGD faming that can damage ID Fan $5MM in realized perating & maintenance cst savings 29

30 KEY SCR DESIGN REQUIREMENTS AND LESSONS LEARNED Unifrm, vertical, nn-recirculating flw int catalyst Flue Gas flw design criteria 15% frm Mean vs. RMS r Cv CFD and Physical Mdeling Cmplimentary design activities. Matching results validate each mdel. Flw Mdeler needs t have SCR experience & PRB cal experience Flw mdel reslutin 5MM t 10MM cells SCR Hd t Layer 1 Equipment mdeled 6 in physical / all flw disturbances in CFD 30

31 LESSONS LEARNED - CONTINUED Minimal structure inside SCR reactr and flue gas ductwrk flw disturbances Minimize hrizntal surfaces PRB ash accumulates n any surface Catalyst pitch minimum 8.2 mm Hneycmb r 5.7 mm plate Outage layup keep SCR ht r use heaters t prevent cndensatin Snic hrn failures Misture and PM LPA screen failures Ersin r layut Outage ash cleaning methd vacuum t catalyst face Inspectins and Mnitring catalyst management prgram 31

32 CONTACTS AND QUESTIONS Sctt Hiedeman KCP&L LaCygne Prject Manager Reid Thmas Fuel Tech Sr. Prcess Engineer P: (913) Dale Pfaff Fuel Tech Reginal Manager P: (847) P: (630) Additinal Infrmatin at FTEK Bth N