Modeling Used to Advance the Recovery Process

Transcription

1 Modeling Used to Advance the Recovery Process Martha Salcudean and Jerry Yuan Process Simulations Ltd. #24, 2386 East mall Vancouver, BC, Canada V6T 13 CFD Application to Recovery Boilers Model development and validation at UBC since early 199s Over 5 recovery boilers being modeled at PSL Wide cooperation with pulp and paper mills, research institutes, boiler and air system manufactures Expertise in CFD, boiler, combustion, visualization PSL being an independent consultant

2 Modeling Application - Air System (1) Modeling Application - Air System (2) Boiler 1 Boiler AL m BL m m AL m AL BL m AL m 74.5 BL m 38.5 AL m AN 1 AN 2 SECONDARY (air)=132 = m (burner)=126 =3.24 m Air ports: Width: =.1683 m Height: =.4792 m Burner ports: Width: =.1683 m Height: 2 =.58 m FRONT AS 1 CAS 2 AS AR m BR m AR m BR m AR m AR m BR m AR m m m m m m 389 BL m m AL BL m AL m 2.5 BL m AL m 98.5 BL m 47.5 AL m SECONDARY T= 424.6K (air)=132 = m (burner)=126 =3.24 m Air ports: Width: =.1683 m Height: =.426 m Burner ports: Width: =.1683 m Height: 2 =.58 m FRONT AR m BR m 32.5 AR m BR m 2.5 AR m 29.5 BR m 98.5 AR m 6 BR m

3 Modeling Application - Carryover Reduction Y Y X X Case 1 Case drying ---- pyrolysis ---- char ---- smelt LB Carryover Mass flux (g/m 2 /s) Carryover Mass flux (g/m 2 /s) 2 18 H L Modeling Application - Load Increase Existing operation and air system Liquor fired: 1.65 MlbDS/day Future operation and new air system Liquor fired: 2.4 MlbDS/day

4 Modeling Application - NCG Burning Modeling Application - Wall Corrosion (1) Kinetic data of the two reactions of pyrolysis a 1 =.22 A 1 = [1/s] Ea 1 = [J/mole] a 2 =.54 A 2 = 15 [1/s] Ea 2 = [J/mole] H 2 S recapture reaction H 2 S + Na 2 CO 3 = Na 2 S + H 2 O + CO 2 Reaction rate k = A[H 2 S]exp(-Ea/RT) A = [1/s] Ea = 1 5 [J/mole] H 2 S oxidation reaction H 2 S + 1.5O 2 = H 2 O + SO 2 Reaction rate k = A[O 2 ] a [H 2 S] b exp(-ea/rt) A = [1/s] Ea = [J/mole] a = 1. [O 2 ] < 4% a = 1.3 [O 2 ] 4% b = Sulfur in Char, % of Sulfur in BLS t673k t773k t873k t973k t173k t1173k Sulfur in Volatile, % of S in BLS C 5C 6C 7C 8C 9C H 2 S(ppm) O2(%) O2(1%) O2(5%) O2(8%) Residence Time, s Temperature ( o C) Sulfur Evolution and Oxidation Model

5 Modeling Application - Wall Corrosion (2) Left Front Right Case 7RD Rear Front Rear Left Right Rear Front Left Right Btu/Hr/Ft 2 Case 7RD Right Wall Front Wall Left Wall H2S [vol, ppm] Rear Wall Modeling Application - BL Gasification (1)

6 Modeling Application - BL Gasification (2) Base case Black liquor gasification Fine droplet Log-normal droplet size distribution steam 1% more for 1 hole 1% less for 1 hole average for others Case 1 Case 2 Case 3 Case 4 Case5 Case 6 Case 7 Typical Mass fraction, dry, % CH CO CO H Volume fraction, dry, % CH CO CO H Heat value, dry kj/mole kj/m Medium droplet Coarse droplet 8% steam High droplet velocity Modeling Application - Airport Crack Study (1) Boiler 1 Global Boiler Modeling Single Airport Modeling Global Boiler + Single Airport Modeling

7 W[m/s] W[m/s] Modeling Application - Airport Crack Study (2) Deposition Rate (kg/m 2.s) Left Wall Front Wall Rear Wall Case 15 Right Wall Front Wall X 1 Y Front Wall X Y.77 m.75 m Simplified Airport Model of Design 1 Simplified Airport Model of Design 2 Recirculation extends to the bottom of the port. Recirculation locates far from the port. Visualization - ProcessCam Technology

8 Visualization - Simulator Technology Operator experience Process knowledge Measurements Physical Model Simulator Core Process Model φ j ui j j = S j x ρ φ Γ i x i Operational Simulators Training Simulators Virtual Cameras Conclusions An effective way to optimize design and operation. Helpful to understanding mechanisms and problem root-causes. Saving costs and reducing risks. Useful as a training tool for operators and process engineers. Further improvements on sub-models.

9 Other Equipment PSL Models Bark Boiler Utility Boiler Burner Ports Distributor Ports Under Dist. Ports Y Overfire Air Cyclone Undergrate Air X Headbox Kiln Electrostatic Precipitator Publications Tse D., Salcudean M. and Gartshore I.S., Multiple Jet Interaction with Relevance to Recovery Boilers Flow Fields, Pulp and Paper Canada, Vol. 95, No. 2, pp. T79-T82, M.E. Salcudean, I. Gartshore,. Abdullah and.p. Nowak, Modelling of Black Liquor Recovery Boilers, From Steam to Space: Contributions of Mechanical Engineering to Canadian Development, Commemorative Volume, 25 th Anniversary of CSME, Ottawa, Canada, pp , Final Report - Department of Energy (U)/IPST, Modelling of Black Liquor Recovery Boilers (Summary Report), by M. Salcudean, I. Gartshore,. Abdullah, P. Nowak, P. Sabhapathy, D. Tse, P Matys, M. Savage,.. Xiao and K. hang, 5 pages, April 1997 M. Salcudean,. Abdullah, and P. Nowak, "Cold Flow Computational Model of a Recovery Boiler", Journal of Pulp and Paper Sciences. Vol. 19, No. 5, pp , September 1993