1 selecting an ers design basis sache workshop gary van sciver september 20, 2005

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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

1

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