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Selectingan ERS
Design Basis
SACHE WorkshopGary Van Sciver
September 20, 2005
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EmergencyReliefSystem
RuptureDisk
Reactor
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Vessel Overpressure
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1999 Allentown, PA 5 fatalities high concentration and temperature of hydroxylamine
Concept Sciences
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Hazardous Release
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Phillips
Pasedena, Texas 1989 23 fatalities
Vapor cloud explosion of ethylene and other gases
Explosion occurred ~ 2 minutes after release started
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Bhopal
Union Carbide 1984 2,500 fatalities
large ERS release of methyl isocyanate
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Venting Policy:
ERS must protecton-site people AND
off-site people
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Balance:
Economics
Off-siteRisk
On-siteRisk
$
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What is aDesign Basis?
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Design Basis:
Simple way to express system capacity
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FailureScenario
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Fire Scenario
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Runaway Scenario
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Failure Scenario: Series of events leading to high
vessel pressure.
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How high?
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Codes require that the maximum pressure not
exceed the vessel design pressure
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Design Basis:
Most severe failure scenario which
complies with the Codes.
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How do we do it?
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Procedure:
1. Identification
2. Selection
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1. Identification
(of all important failure scenarios)
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ideas
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Non-reactiveSystems
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Product Tank Example
RD
Heating/Cooling
From Reactor
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Non-Reactive Checklist
1. Heat addition a. Normal breathingb. Firec. Excessive heating
2. Pressurized liquid addition 3. Pressurized gas addition
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1a. Normal breathing(atmospheric temperature and pressure changes)
RD
Heating/Cooling
From Reactor
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1b. Fire Exposure
RD
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1c. Excessive heating(steam valve failures, coil leaks)
RD
Steam wide open
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2. Pressurized liquid addition(usually accompanied by some flashing, especially if hot)
RD
Liquid
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3. Pressurized gas addition(line blowing, pressure transfers, pads or purges)
RD
Air, Nitrogen or Steam
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ReactiveSystems
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Is there an exothermic or gas-generating
reaction?
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Generic Emulsion Compatibility Matrix
activator
bactericide
catalyst
chain transfer agent
miscellaneous additive
monomer
neutralizer
preform
promoter
soap
water
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Reactive Chemistry Worksheet
developed by EPA and NOAA (National Oceanic and Atmospheric Administration)
http://response.restoration.noaa.gov/chemaids/react.html
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OSHA Chemical Reactivity Website
http://www.osha.gov/dep/reactivechemicals/
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Bretherick’s
Handbook of Reactive Chemical
Hazards
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LabExperiments
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Emulsion Reactor Example
Reactant
Catalyst/Activator
Miscellaneous
CoolingWater
TIC
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NormalReaction Checklist
1. Inadequate cooling 2. Inadequate heat sink 3. Excessive reactant 4. Poor reactivity
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Coolingwaterfails
1. Inadequate cooling
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Water NOTcharged
2. Inadequate heat sink
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Reactant
Bypass open
3. Excessive reactant (continuous)
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3. Excessive Reactant (batch)
Reactant
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Agitator offReactant
4. Poor reactivity
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Abnormal Reaction Checklist
1. Too hot
2. Wrong composition
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1. Too hot
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2. Wrong composition
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System ________________
1. Non-Reactive Scenarios
1a. Normal Breathing
1b. Excessive Heating
1c. Fire Exposure
1d. Liquid Addition
1e. Gas Addition
2. Normal Reaction Scenarios
2a. Inadequate Cooling
2b. Inadequate Heat Sink
2c. Excessive Reactants Fed
2d. Excessive Reactant Buildup
3. Abnormal Reaction Scenarios
3a. Too Hot
3b. Wrong Composition
Apply?
XXX
Description & Size
XXXXXXXXXXX
XXX XXXXXXXXXXX
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2. Selection
(of a design basis from the important failure scenarios)
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Selection Approaches:
A. Codes/StandardsB. Tradition/AnalogyC. Risk
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List scenarios by ERS size
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Example Scenario List:
1. Liquid filling2. Fire case3. Half charge runaway4. Full charge runaway5. Full charge runaway
without water heel
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A. Codes/ Standards
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NFPA 30 requiresERS protection against
fire exposure
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B. Tradition/ Analogy
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Traditional Designs
Non-reactive: Fire Case Reactive: Full-charge
Runaway
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Traditional DesignExample of Traditional Design
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10
100
1000
100 1,000 10,000 100,000
Monomer Volume
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ERS Database
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C. Risk
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Probability
of
consequences
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Consequences
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Probability(of high vessel pressure)
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Fenceline
Process
Offices
Neighbors
Hospital
Plot Plan
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Fenceline
Process
Offices
Neighbors
Hospital
Risk Contours
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On-site Risk - once per 40,000 years
Off-site Risk - once per 100,000 years
Rohm and Haas Risk Criteria