NUMERICAL SIMULATION RESEARCH ON 600MW BOILER WITH DIFFERENT SINGLE BURNER HEAT POWER

Transcription

1 NUMERICAL SIMULATION RESEARCH ON 600MW BOILER WITH DIFFERENT SINGLE BURNER HEAT POWER Qulan Zhou Department of Thermal Engineering Xi an Jiaotong University

2 Contents 1 2 Introduction Modeling and methods 3 4 Simulation Results Summary and conclusion

3 Introduction world Boiler has larger capacity and higher condition China To avoid complex air and coal powder pipe system Research gap Boiler volume and single burner heat power Operation badly and scorification seriously Boiler capacity,(600mw,1000mw) single burner heat power Coal property, different from coal abroad Babcock, adopts smaller burner (16.28~19.77MW), Good working condition FW, adopts larger burner(48.8~58.8mw) for 510/550MW, 58.15~81.4MW) for 620/700MW.

4 Modeling and method Geometrical model Refer to 600MW boiler from Shanghai boiler company Size defination Size code Size value units How to select it remark Furnace structure size Furnace width a mm Covering flame angle OFA Some 600MW power plant of Huaneng corp. information form internet γ ~55 Furnace depth b mm Furnace height h mm combustion chamber hopper dip angle Chamber hopper Throat width E mm 0.8~ Covering flame angle length D mm About 1/3 of furnace depth Covering flame angle Inclined angle β 25 Covering flame angle on α 45 Horizontal flue depth mm Burner arrangement <coal burner design and operation>:15~30 <principle of boiler and calculate>: 20~30 <coal burner design and operation>:30~50 <principle of boiler and calculate>: 20~45 Refer to 600MW boiler of Huaneng <coal burner design and operation>: Larger value should be adopted by more ash fuel Burner primary air spout interlamellar spacing H mm Combustion zone Spout level distance between the same layer burner Distance from the top spout to platen superheater bottom H mm H mm Distance from the bottom spout to chamber hopper inflexion point H mm Some 600MW power plant of Huaneng corp. information form internet 2.4~3.6m,larger value for slagging coal The distance between outboard burner and flank d mm 3H 2d a 2 Boiler chamber hopper Distance between the center OFA and top burner Distance between the outboard OFA and top burner H mm H mm

5 Modeling and method physical model---mathematical model Gas phase ( Ui ) ( ) S (continues) model x x x Pulverized coal phase (discrete particle) model Combustion model i i i du pi gi ( p ) FD ( Ui U Pi ) Fi dt P 18 CDRe FD 2 d 24 P d p U Pi Ui Re a2 a3 CD a Re Re P 1 2 Reaction of Volatile matter two mutually competing single step reactions are used Reaction of char particles The heterogeneous char oxidation rate is calculated by a kinetics/diffusion model developed by Field et al dv dt ( 1k1 2k2) mp En kn k0nexp( ), n 1,2 RTP dmp 2 kk c d dppox dt k k k d kc [( Tp Tg) / 2] C1 d C e 2 ( E/ RT p ) p c d 0.75

6 Modeling and method NOx formation model accurate velocity, temperature, mixture species profiles Char-N post processing program Coal-N O 2 Char Volatile-N HCN/NH 3 NO N 2 3(char-N):7(volatile-N) De Soete s model 9(HCN from Volatile-N):1(NH3 from volatile-n) Thermal NOx Fuel NOx solving the corresponding transport equations with HCN and NH 3

7 Simulation Results 1.Flow and temperature field characteristic 2.Inflammation performance 3.The burn-out characteristic 4.NO x Emission 5. Boiler Absorbted heat 6.The velocity and temperature distribution of furnace outlet 7.Hot corrosion of water wall tendency analyzing

8 Simulation Results 1.Flow and temperature field characteristic 24burners v1 v2 v3 v4 Four vertical sections velocity vector of furnace

9 Simulation Results 1.Flow and temperature field characteristic outlet zone furnace height/m burnout zone OFA layer central combustion zone Partial enlarged details of velocity vector in main combustion zone 10 furnace hopper zone furnace temperature/k

10 temperature/k temperature/k temperature/k temperature/k temperature/k temperature/k Simulation Results 2.Inflammation performance burners furnace third layer second layer first layer boiler depth/m burners furnace third layer second layer firtst layer boiler depth/m burners furnace third layer second layer first layer boiler depth/m burners furnace third layer second layer first layer boiler depth/m burners furnace fourth layer third layer second layer first layer boiler depth/m burners furnace fourth layer third layer second layer first layer boiler depth/m Temperature distribution at burner axis of different burner single power conditions

11 fraction conversion% Simulation Results 3.The burn-out characteristic burner number volatile fixed carbon

12 Simulation Results 4. NO x Emission NO/mg/m burner number

13 Heat absorption capacity of furnace/10 8 W furnace volumn heat release rate q v,kw/m 3 Simulation Results 5. Boiler Absorbed heat burners 24burners 30burners 36burners 40burners 48burners 50 18burners 24burners 30burners 36burners 40burners 48burners burner numbers burner numbers

14 Simulation Results 6.The velocity and temperature distribution of furnace outlet 18burners 24burners 30burners 36burners 40burners Furnace outlet velocity distribution 48burners

15 Simulation Results 6.The velocity and temperature distribution of furnace outlet 18burners 24burners 30burners 36burners 40burners 48burners Furnace outlet temperature distribution

16 Simulation Results 7.Hot corrosion of water wall tendency analyzing Variable distribution in Furnace with 24burners Variable distribution in Furnace with 18burners

17 Simulation Results 7.Hot corrosion of water wall tendency analyzing Variable distribution in Furnace with 36burners Variable distribution in Furnace with 30burners

18 Simulation Results 7.Hot corrosion of water wall tendency analyzing Variable distribution in Furnace with 48burners Variable distribution in Furnace with 40burners

19 Summary and Conclusion Single heat power (MW) Burner numbers 600MW-boiler combustion simulation results Ignition distance Burn-out characteristic NOxemission Heat absorption capacity of furnace*10 8 W Most heat deviation of water wall Longer Better Lower Larger Furnace outlet velocity and temperature distribution Hot corrosion of water wall tendency Easy Shorter common Higher Larger Not easy A little Too long better Larger Hard high Little proper better lower Lower effect, Not easy within shorter worse Highest Lower 1m/s,10 Not easy shorter best Lower Lower Not easy Optimum number /36/48 No effect 36 30

20 Thank You!