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CHEMCAD Process Safety Emergency Relief John Edwards, P&I Design Ltd
January 2015 1
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PROCESS SAFETY - EMERGENCY RELIEF
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF 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
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PROCESS SAFETY - EMERGENCY RELIEF RELIEF DEVICES – VALVE TYPES
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF RELIEF DEVICES – VALVE TYPES
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PROCESS SAFETY - EMERGENCY RELIEF RELIEF DEVICES RUPTURE DISCS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF RELIEF DEVICES RUPTURE DISCS
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PROCESS SAFETY - EMERGENCY RELIEF TYPICAL BLOWDOWN MANIFOLD
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF TYPICAL BLOWDOWN MANIFOLD REACTOR 1 BLOWDOWN TANK REACTOR 2 REACTOR 3 PUMP SCRUBBING COLUMN VENT RELIEF HEADERS DISPERSION
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PROCESS SAFETY - EMERGENCY RELIEF CHEMCAD SIZING TOOL FEATURES
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF CHEMCAD SIZING TOOL FEATURES DESIGN/RATING ATMOSPHERIC STORAGE TANKS PRESSURE VESSELS VESSEL MODEL BUBBLY CHURN-TURBULENT HOMOGENEOUS VESSEL NON-FLASHING LIQUID VENT MODEL HEAT MODEL VENT FLOW TEMPERED RUNAWAY REACTION NFPA 30 OSHA HEM ERM HFZ SINGLE PH VAPOR STEAM HNE API 520/521 API 2000 HEAT RATE NON TEMPERED RUNAWAY REACTION
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PROCESS SAFETY - EMERGENCY RELIEF PRESSURE SPECIFICATIONS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF PRESSURE SPECIFICATIONS SET PRESSURE SET PRESSURE +10% DESIGN PRESSURE DESIGN PRESSURE +10% Pressure rise due to reaction Safety valve starts to open Maximum accumulated pressure Safety valve full open PRESSURE TIME
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EMERGENCY RELIEF SIMULATION REACTION TYPES
SIMULATION SUITE CHEMCAD SOFTWARE EMERGENCY RELIEF SIMULATION REACTION TYPES REACTION SYSTEM VAPOUR PRESSURE HYBRID GASSY TEMPERED UNTEMPERED
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PROCESS SAFETY - EMERGENCY RELIEF VESSEL BEHAVIOUR MODELS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF VESSEL BEHAVIOUR MODELS HOMOGENEOUS BUBBLY CHURN-TURBULENT Relief Area ↑
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PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW REGIMES
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW REGIMES VENT FLOW HIGH VISCOSITY LOW VISCOSITY FOAMY NON FOAMY HOMOGENEOUS BUBBLY TWO PHASE RELIEF SINGLE PHASE CHURN-TURBULENT
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PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW MODELS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW MODELS HEM ERM HENRY-FAUSKE HNE NON-FLASHING LIQUID SINGLE PHASE VAPOUR STEAM RELIEF HFZ (HOMOGENEOUS FROZEN)
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PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW MODELS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF VENT FLOW MODELS
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PROCESS SAFETY - EMERGENCY RELIEF HEAT MODELS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF HEAT MODELS API 520/521 API 2000 NFPA 30 OSHA SPECIFY VENT FLOW SPECIFY HEAT RATE TEMPERED RUNAWAY REACTION NON TEMPERED RUNAWAY REACTION
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PROCESS SAFETY - EMERGENCY RELIEF CODE SETS EXPOSED AREA
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF CODE SETS EXPOSED AREA NFPA-30 & OSHA 55% total exposed area 75% total exposed area, if<200 ft2 use 100% 100% total exposed for first 30 ft exclude bottom area if flat and supported on ground SPHERE HORIZONTAL TANK VERTICAL TANK
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SIMULATION SUITE CHEMCAD SOFTWARE
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF API 520 / 521 > 15 psig SETS EXPOSED AREA SPHERE HORIZONTAL TANK VERTICAL TANK PROCESS VESSEL FRACTIONATING COLUMN Area up to maximum horizontal diameter or up to 25ft height whichever is greater Area equivalent to the average inventory level up to 25ft height Area equivalent to level in bottom & reboiler plus tray hold up to a height of 25ft
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PROCESS SAFETY - EMERGENCY RELIEF API 2000 ≤ 15 psig
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF API 2000 ≤ 15 psig SPHERE As in API 520/API521 HORIZONTAL TANK 75% total exposed area VERTICAL TANK As in OSHA
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PROCESS SAFETY EMERGENCY RELIEF EXTERNAL FIRE API 520 STANDARDS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF EXTERNAL FIRE API 520 STANDARDS
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PROCESS SAFETY - EMERGENCY RELIEF SIMULATION SET UP PROCEDURE
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY - EMERGENCY RELIEF SIMULATION SET UP PROCEDURE Inlet Stagnation Conditions Sizing Blowdown Piping Design Piping use Beggs and Brill and Calculation Mode 5 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 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
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING Section 6 Case 6.06 page 205 Fluid Propane Set pressure Pa No external heat, rating determines nozzle capacity
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING Section 6 Case 6.06 page 205
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.06 RELIEF DEVICE RATING Section 6 Case 6.06 page 205 Vent Flux = 3.55E05/(3600* ) = 5580 kg/s-m2
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.13 REACTOR MANIFOLD
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.13 REACTOR MANIFOLD Section 6 Case 6.13 page 213 Section 6 Case 6.06 page 205
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.13 RELIEF MANIFOLD GUI
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.13 RELIEF MANIFOLD GUI Section 6 Case 6.06 page 205
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PROCESS SAFETY EMERGENCY RELIEF CRITICAL FLOW CONSIDERATIONS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CRITICAL FLOW CONSIDERATIONS API 520 Part 1, 7th Edition January 2000, Section 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
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PROCESS SAFETY EMERGENCY RELIEF DYNAMIC VESSEL MODEL
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF DYNAMIC VESSEL MODEL DIERS Technology used to model vessel bed expansion API 520 heat input model used to simulate fire 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
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 COINCIDENT DYNAMIC RELIEF
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 COINCIDENT DYNAMIC RELIEF Section 6 Case 6.15 page 220 30ft 4in x 40 120ft 6in x 40 40ft 6in x 40
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SIMULATION SUITE CHEMCAD SOFTWARE
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 COINCIDENT DYNAMIC DVSL SPECS Section 6 Case 6.06 page 205 DVSL psia
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PROCESS SAFETY EMERGENCY RELIEF PIPE NETWORK PROPERTIES
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF PIPE NETWORK PROPERTIES 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
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PROCESS SAFETY EMERGENCY RELIEF PIPE NETWORK NODE UNITOP
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF PIPE NETWORK NODE UNITOP 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
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 PRESSURE NODE SPECIFICATIONS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 PRESSURE NODE SPECIFICATIONS Section 6 Case 6.06 page 205
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 DYNAMIC SIMULATION SET UP
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 DYNAMIC SIMULATION SET UP 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
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PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 DYNAMIC SIMULATION RESULTS
SIMULATION SUITE CHEMCAD SOFTWARE PROCESS SAFETY EMERGENCY RELIEF CASE 6.15 DYNAMIC SIMULATION RESULTS Section 6 Case 6.06 page 205
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