Toxic Release of Chlorine

8/3/2019 Toxic Release of Chlorine

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Safety Risk Assessment OfToxic Release Of Chlorine

Gas

Praveen Garg KirninderjeetKaur

08112055 08110009

CHE, final year CHE, final year

Project Supervisor: Mr. S. Bajpai


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Introduction

includes:

Incident identification andConsequence analysis.

1) Incident identification describes

How an accident occurs.Includes analysis of the probabilities ofoccurrence.

2) Consequence analysis describesExpected potential damage.Includes loss of life, damage to the environmentor

capital equipment.


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Chlorine is a toxic gas that irritates pulmonarysystem, with intermediate water solubility.Chlorine gas, also known as bertholite, wasfirst used as a weapon in World War I.Heavier than air, and hence tends to

accumulate at the bottom of poorly ventilatedspaces.Strong oxidizer, which may react withflammable materials.

Release of chlorine gas causes deaths andinjuries to workers and the public, resulting inthe evacuation of communities and adverselyaffecting the environment as a whole.


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In this project, we will:

Review probability mathematics, includingthe mathematics of equipment failure,Show how the failure probabilities ofindividual hardware components contribute to

the failure of a process using Fault Trees.Calculate concentration of chlorine releasedin different locations using Air DispersionModeling,

Compare the results (as obtained by airdispersion modeling) as per DOW CEI.


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Literature ReviewS.No. Author Field Software

UsedMethodology

1. Hyo Kim, Jae-SunKoh, Youngsoo Kimand Theofanius G.Theofanous et al. 2004

Risk Assessment ofMembrane TypeLNG Storage Tanks

Fault TreeAnalysis

2. Mark Brandyberry andGeorge Apostolakis etal. 1989

Fire Risk Analysis COMPBRN ResponseSurfaceMethodology

3. Raymond H. MyersAndre I. Khuri

Walter H. Carter, Jr. etal.

Overview ofResponse Surface

Methodology

ResponseSurface

Methodology

4. Saari Mustapha ,TanChye Hee, MohanadEl-Harbawi, AbdulRashid Shariff,Thomas S.Y. Choong,

Chlorine incidentand its toxichazardouschemical releaseimpact in the

GIS software(GeoMediaProfessional5.1)

Air DispersionModeling


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PROPOSED METHODOLOGIES

Conventional Approaches

Modern Approaches


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FAULT TREESFault trees are a deductive method for

identifying ways in which hazards can leadto accidents.

The approach starts with a well-defined

accident, or top event, and works backwardtoward the various scenarios that can cause theaccident.The contributing causes are either basic or

intermediate events. The basic events areevents that cannot be defined further, andintermediate events are events that can.

These events are connected to the top eventb AND or OR lo ic function.


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EVENT TREESEvent trees begin with an initiating event and worktoward a final result.

The method provides information on how a failurecan occur and the probability of occurrence.

Steps in an event tree analysis :

identify an initiating event of interest, identify the safety functions designed to deal withthe initiating event, construct the event tree, anddescribe the resulting accident event sequences.

The event tree can be used quantitatively if data areavailable on the failure rates of the safety functionsand the occurrence rate of the initiation event.


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FACTORIAL DESIGN AND RESPONSESURFACE METHODOLOGY

A structured method for combining the ranges of theindependent variables into a set of experiments whichsample the range of each independent variable.Each independent variable is assigned two values or

levels(high and low).Each pair of levels are combined with all other pairs toyield 2k experiments.This type of design can be used to reduce the numberof necessary experiments.

is useful forthe modeling and analysis of programs in which aresponse of interest is influenced by several variables

and the objective is to optimize this response.


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Expected Results/Case StudyChlorine is usually stored in a 1 ton cylinder capacity

with 0.75 inch vapor connection stored at ambient

temperature (250C)B.P.= -340C and stored in liquefied state at roomtemperature with pressures above 8 atmospheres at -100C.

Four top events leading greatly to the large release ofchlorine gas are defined and solved using differentmethodologies.

Chlorine Gas Release

Rupture ofstorage tank

Failure ofloading/unloadi

ng lines

Leakage invalves and

joints

Intentionalfailures/damag

e


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The evaporation rate of chlorine depends on two cases:Case 1: Due to rupture of the storage tank

Qm=MKAPsat

/RgTL

Q, is the evaporation rate (mass/time),M is the molecular weight of the volatile substance,K is a mass transfer coefficient (length/time) for an area

A,R, is the ideal gas constant, andT is the absolute temperature of the liquid.

K=K0(M

o/M)1/3

Water is most frequently used as a referencesubstance; it has a mass transfer coefficient of 0.83cm/s.


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Case 2: Leakage in tank/pipelines(assuming thatleakage occurs through a hole of circular shape)

Qm=AC0(2gcpPg)1/2

Pg is the gauge pressure(pr inside the storage tank)(force/area),p is the fluid density (mass/volume),

gc is the gravitational constant (length mass/force time2),A is leak area,C0 is the discharge coefficient 0.61 for sharp edge orifice

1 for well rounded nozzle 0.81 for a short section of pipe attached to a vessel.


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From the evaporation rate of chlorine release we canfind out the ground level concentrations of chlorine atdifferent locations of an effected area by use of Air

Dispersion Modeling so that onsite and offsitepreventive measures can be installed accordingly.

Equation for plume with continuous steady-state sourceat height H above ground level and wind moving in xdirection at constant velocity uis given by:


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Conclusions/Future Work:

Fault Tree Analysis helps in identifying the ways in

which an accident can occur and also the probability ofoccurrence.By the use of Air Dispersion Modeling, we can find outthe concentration of chlorine at different locations andutilizing this data we can evaluate up to which area theconcentration of chlorine is acceptable as per Dows

ERPG values.

This analysis using RSM(if possible) is our future work.

The different ways of occurrence of a hazard will act asdifferent factors for analysis in Response SurfaceMethodology.The significant factors of use will retain and an

optimized result is taken out in the form of mostrevailin conditions which can cause maximum


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Toxic Release of Chlorine