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CHEMCAD Process Safety Emergency Relief John Edwards, P&I Design Ltd January 2015

CHEMCAD Process Safety Emergency Relief John Edwards, P&I Design Ltd January 2015. www.chemstations.com. PROCESS SAFETY - EMERGENCY RELIEF. SIMULATION SUITE. CHEMCAD SOFTWARE. www.chemstations.com. www.chemcad.co.uk. EMERGENCY RELIEF SYSTEM DESIGN

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CHEMCAD Process Safety Emergency Relief John Edwards, P&I Design Ltd January 2015

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  1. CHEMCAD Process Safety Emergency Relief John Edwards, P&I Design Ltd January 2015 www.chemstations.com

  2. PROCESS SAFETY - EMERGENCY RELIEF SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk • EMERGENCY RELIEF SYSTEM DESIGN • Understand temperature and phase changes across relief device • Understand relief device parameters • Be able to specify a relief device • Understand vessel model and vent model characteristics • Understand heat model selection criteria • Be able to use CHEMCAD relief sizing tool • Set up multiple relief scenarios with blowdown systems • Study dynamic multiple relief scenarios

  3. PROCESS SAFETY - EMERGENCY RELIEFRELIEF DEVICES – VALVE TYPES SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk

  4. PROCESS SAFETY - EMERGENCY RELIEFRELIEF DEVICES RUPTURE DISCS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk

  5. PROCESS SAFETY - EMERGENCY RELIEFTYPICAL BLOWDOWN MANIFOLD DISPERSION VENT SCRUBBING COLUMN RELIEF HEADERS SIMULATION SUITE CHEMCAD SOFTWARE TANK BLOWDOWN TANK REACTOR 3 REACTOR 1 REACTOR 2 PUMP www.chemstations.com www.chemcad.co.uk

  6. PROCESS SAFETY - EMERGENCY RELIEFCHEMCAD SIZING TOOL FEATURES DESIGN/RATING ATMOSPHERIC STORAGE TANKS PRESSURE VESSELS VESSEL MODEL BUBBLY CHURN-TURBULENT HOMOGENEOUS VESSEL VENT MODEL HEM ERM HFZ SINGLE PH VAPOR NON-FLASHING LIQUID SIMULATION SUITE CHEMCAD SOFTWARE HEAT MODEL NFPA 30 OSHA 1910-106 VENT FLOW TEMPERED RUNAWAY REACTION www.chemstations.com www.chemcad.co.uk STEAM HNE API 520/521 API 2000 HEAT RATE NON TEMPERED RUNAWAY REACTION

  7. PROCESS SAFETY - EMERGENCY RELIEFPRESSURE SPECIFICATIONS Maximum accumulated pressure DESIGN PRESSURE +10% DESIGN PRESSURE Safety valve full open SET PRESSURE +10% PRESSURE SET PRESSURE Safety valve starts to open SIMULATION SUITE CHEMCAD SOFTWARE Pressure rise due to reaction TIME www.chemstations.com www.chemcad.co.uk

  8. EMERGENCY RELIEF SIMULATIONREACTION TYPES REACTIONSYSTEM GASSY HYBRID VAPOURPRESSURE SIMULATION SUITE CHEMCAD SOFTWARE TEMPERED UNTEMPERED www.chemstations.com www.chemcad.co.uk

  9. PROCESS SAFETY - EMERGENCY RELIEFVESSEL BEHAVIOUR MODELS SIMULATION SUITE CHEMCAD SOFTWARE HOMOGENEOUS Relief Area ↑ BUBBLY CHURN-TURBULENT www.chemstations.com www.chemcad.co.uk

  10. PROCESS SAFETY - EMERGENCY RELIEFVENT FLOW REGIMES VENT FLOW LOW VISCOSITY HIGH VISCOSITY NON FOAMY FOAMY SIMULATION SUITE CHEMCAD SOFTWARE CHURN-TURBULENT BUBBLY HOMOGENEOUS SINGLE PHASE RELIEF TWO PHASE RELIEF www.chemstations.com www.chemcad.co.uk

  11. PROCESS SAFETY - EMERGENCY RELIEFVENT FLOW MODELS HEM ERM STEAM RELIEF HENRY-FAUSKE HNE SIMULATION SUITE CHEMCAD SOFTWARE NON-FLASHING LIQUID SINGLE PHASE VAPOUR HFZ (HOMOGENEOUS FROZEN) www.chemstations.com www.chemcad.co.uk

  12. PROCESS SAFETY - EMERGENCY RELIEFVENT FLOW MODELS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk

  13. PROCESS SAFETY - EMERGENCY RELIEFHEAT MODELS API 520/521 API 2000 NFPA 30 OSHA 1910-106 SPECIFY HEAT RATE SIMULATION SUITE CHEMCAD SOFTWARE SPECIFY VENT FLOW TEMPERED RUNAWAY REACTION NON TEMPERED RUNAWAY REACTION www.chemstations.com www.chemcad.co.uk

  14. PROCESS SAFETY - EMERGENCY RELIEFCODE SETS EXPOSED AREA NFPA-30 & OSHA 1919-06 SPHERE 55% total exposed area HORIZONTAL TANK 75% total exposed area, if<200 ft2 use 100% SIMULATION SUITE CHEMCAD SOFTWARE VERTICAL TANK 100% total exposed for first 30 ft exclude bottom area if flat and supported on ground www.chemstations.com www.chemcad.co.uk

  15. PROCESS SAFETY - EMERGENCY RELIEFAPI 520 / 521 > 15 psig SETS EXPOSED AREA SPHERE Area up to maximum horizontal diameter or up to 25ft height whichever is greater HORIZONTAL TANK Area equivalent to the average inventory level up to 25ft height VERTICAL TANK Area equivalent to the average inventory level up to 25ft height SIMULATION SUITE CHEMCAD SOFTWARE PROCESS VESSEL Area equivalent to the average inventory level up to 25ft height FRACTIONATING COLUMN Area equivalent to level in bottom & reboiler plus tray hold up to a height of 25ft www.chemstations.com www.chemcad.co.uk

  16. PROCESS SAFETY - EMERGENCY RELIEFAPI 2000 ≤ 15 psig SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk SPHERE As in API 520/API521 HORIZONTAL TANK 75% total exposed area VERTICAL TANK As in OSHA

  17. PROCESS SAFETY EMERGENCY RELIEFEXTERNAL FIRE API 520 STANDARDS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk

  18. PROCESS SAFETY - EMERGENCY RELIEFSIMULATION SET UP PROCEDURE Inlet Stagnation Conditions Set up Inlet Stream at Set Pressure and Flow 1 kg/h Single Component Flash at vf 0 or 1 Multi –component Set weight fractions and Flash at vf 0 Sizing If vent flow specified use nominal size pseudo vessel Set vessel at maximum operating level Conservative use HEM vessel and vent flow models Non-tempered runaway must use HFZ vent model If single phase vapour specified check for two phase SIMULATION SUITE CHEMCAD SOFTWARE Blowdown Piping Design Piping use Beggs and Brill and Calculation Mode 5 www.chemstations.com www.chemcad.co.uk

  19. PROCESS SAFETY EMERGENCY RELIEFCASE 6.06 RELIEF DEVICE RATING SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205 Fluid Propane Set pressure 993000Pa No external heat, rating determines nozzle capacity

  20. PROCESS SAFETY EMERGENCY RELIEFCASE 6.06 RELIEF DEVICE RATING SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205

  21. PROCESS SAFETY EMERGENCY RELIEFCASE 6.06 RELIEF DEVICE RATING SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205 Vent Flux = 3.55E05/(3600*0.01767) = 5580 kg/s-m2

  22. PROCESS SAFETY EMERGENCY RELIEFCASE 6.13 REACTOR MANIFOLD SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.13 page 213 Section 6 Case 6.06 page 205

  23. PROCESS SAFETY EMERGENCY RELIEFCASE 6.13 RELIEF MANIFOLD GUI SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205

  24. PROCESS SAFETY EMERGENCY RELIEFCRITICAL FLOW CONSIDERATIONS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk API 520 Part 1,  7th Edition January 2000, Section 3.6.1.3 Under critical flow conditions, the actual pressure at nozzle exit of the pressure relief device cannot fall below the critical flow pressure even if a much lower pressure exists downstream. At critical flow, the expansion from nozzle pressure to downstream pressure takes place irreversibly with energy dissipated in turbulence into the surrounding fluid

  25. PROCESS SAFETY EMERGENCY RELIEFDYNAMIC VESSEL MODEL DIERS two phase flow methods used to calculate flow through valve Node represents back pressure on safety relief valve Two phase flow through piping system modeled dynamically DIERS Technology used to model vessel bed expansion SIMULATION SUITE CHEMCAD SOFTWARE API 520 heat input model used to simulate fire www.chemstations.com www.chemcad.co.uk

  26. PROCESS SAFETY EMERGENCY RELIEFCASE 6.15 COINCIDENT DYNAMIC RELIEF SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.15 page 220 30ft 4in x 40 120ft 6in x 40 40ft 6in x 40

  27. PROCESS SAFETY EMERGENCY RELIEFCASE 6.15 COINCIDENT DYNAMIC DVSL SPECS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205 DVSL2 - 180psia

  28. PROCESS SAFETY EMERGENCY RELIEFPIPE NETWORK PROPERTIES SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk • All Flows and Pressures dependent on each other • Flowrate can be calculated as a function of • Inlet Pressure (Pin) • Outlet Pressure (Pout) • Flow Scaling Unit Ops solve for flowrate as a function of Pin and Pout • Node Unit Op links all Flow Scaling UnitOps shown in Table below • Pipe (PIPE) • Valve (VALV) • Control Valve (CVAL) • Pumps (PUMP) • Compressors (COMP) • Expanders (EXPN) • Pin, Pout, and Flowrate for all scaling Unit Ops

  29. PROCESS SAFETY EMERGENCY RELIEFPIPE NETWORK NODE UNITOP SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk • Nodes link two or more Flow Scaler Unit Ops • Allows the simultaneous solving of unknown variables in a network • Has P and Fin and Fout • Can specify either • P and Fin, calculate Fout • P and Fout, calculate Fin • Fout and Fin, calculate P

  30. PROCESS SAFETY EMERGENCY RELIEFCASE 6.15 PRESSURE NODE SPECIFICATIONS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205

  31. PROCESS SAFETY EMERGENCY RELIEFCASE 6.15 DYNAMIC SIMULATION SET UP SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205 • Switch to dynamic mode under convergence • Set Run Time to 5 minutes with 0.1 minute step size • Record desired streams 4 and 9 • Record desired UnitOps 1, 2, 5 and 6 • Select Run Time plot options • Run from Initial State • Plot results

  32. PROCESS SAFETY EMERGENCY RELIEFCASE 6.15 DYNAMIC SIMULATION RESULTS SIMULATION SUITE CHEMCAD SOFTWARE www.chemstations.com www.chemcad.co.uk Section 6 Case 6.06 page 205

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