08_Relief System Adequacy – a Step Towards SAFER Operations_Deepak_Ingenero

8/19/2019 08_Relief System Adequacy – a Step Towards SAFER Operations_Deepak_Ingenero

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Confidential & Proprietary1

Relief System Adequacy – a step towards SAFER

operations

by

Deepak Padwal, Ingenero, Mumbai, India

Prepared for presentation at the

AspenTech

Engineering Solution Seminar, Mumbai

February 23, 2016


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Presentation Outline

• Brief Introduction to Ingenero

• Introduction: Pressure Relief System

• Adequacy of Pressure Relief System

• Equipment based PRA

• Role of simulation

• Safety Analysis Environment in Aspen Hysys

• Case Example – Ethylene Plant


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Ingenero – Overview

A High End Engineering Services CompanySupporting Operating Companies and ServiceProviders


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Global Business Profile

Houston(Headquarters)

Chicago

Ingenero Tech (I) Pvt Ltd,Mumbai(Technical Ops & Delivery Center)

Doha,Qatar

Johore,Malaysia

Tokyo,Japan

BeneluxGermany

South Africa

Offices

Client Sites

Target clusters

We serve customers in multiple continents withkey offices in USA, India, KSA and Qatar

Nigeria KSA


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Ingenero Key Service Areas

Ingenero combines extensive knowledge withprocess expertise and operations experience todeliver highly specialized 3600 engineering solutions

Focus area for this

presentation


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• Equipment or Relief Device based revalidation for the existingfacilities as well as new designs

• Process design basis development

• Flare header, Radiation & Dispersion analyses

• Network equipment rating

• Dynamic simulation & QRA

• Risk categorization and cost effective mitigations for theidentified deficiencies

Pressure Relief Analysis Capability

We have been involved with several PressureRelief Systems projects for refiners in the USA,Europe, Southeast Asia and the Middle Eastcovering the following activities:


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• More than 30,000 PSVs analyzed/designed

• Broad spectrum of industries analyzed– Refineries and Oil & Gas – ~50

– Petrochemicals – ~16

– Specialty Chemicals - ~12

• Over 80 process engineers with PRA experience

• Engineers are familiar with and apply all relevantinternational codes and standards

• Leverage on operation and engineering expertise• Rigorous evaluations to uncover design deficiencies

• Focus on cost-effective solutions

• Work-Processes and Quality Management Systems

Broad Experience Of Our PRA Team

Ingenero’s extensive experience with pressurerelief systems and engineering allows for superiordelivery


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Introduction : Pressure Relief System

• Overpressure is result of an imbalance or disruption of the

normal flows of material and energy that causes the

material or energy, or both, to build up in the system

• Overpressure is prevented by relieving fluid from an over-

pressurized equipment or equipment system

• The pressure relief system comprises of physical relief

device & the associated downstream disposal system (KO

drum, Flare) to safely handle the material relieved

Pressure relief is a dedicated system to protect lifeand property from the dangers of overpressure


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When is Pressure Relief Required?

• Blocked outlet

• Control valve failure

• Exposure to fire

• Utility failure

• Exchanger Tube rupture

• Thermal expansion

• Operational errors, etc…

In processing plants, overpressure can happen dueto various individual or combined triggers

The overpressure can lead to a major incident ifthe pressure relief system is not in place/notfunctional/not adequate


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Layers of Protection

Relief system is the last line of preventive defenseagainst catastrophic failure of equipment

The physical relief devices should be capable ofoperating at all times


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Adequacy of Pressure Relief System

• In general, for design capacity & composition, pressure

relief systems of processing plants are adequately

designed to handle overpressure contingencies

• However, process plants go through continuous

modifications to enhance efficiency or capacity, often

without due attention being given to existing safety system – This increases the risks of major accidents.

• Unforeseen incidents in the process industry in the recent

past have prompted many facilities to undergo adequacy

checks of their relief devices

– To reduce the likelihood of damage to their assets and

surrounding environment

Relief system needs on-going revalidation toensure overpressure protection


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Industry Incident – Example 1

Unforeseen incidents have caused damage toassets and surrounding environment

Refinery in Texas (USA)March 23, 2005

Vessel overfilling, vapor

cloudthrough atmospheric

blowdown system

Fifteen fatalities, 170 injured

Key findings: Various pressure relief system related

citations (inadequate relief system, Inadequate headerdesign info, equipment not protected..)


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Industry Incident – Example 2

Unforeseen incidents have caused damage toassets and surrounding environment

Key findings: Third stage separator was not equipped with

any pressure relief device as mandated by API specification

Processing Plant , Louisiana(USA)

March 4, 1998

CatastrophicVessel over-pressurization

Four fatalities


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Revalidation of Relief System

Changes in process plants warrant immediaterevalidation of existing Pressure Relief system

Rate change

Composition change

Change in Unit or Equipment operation mode

Rotating or fixed equipment change

Piping change

Change in vessel or flange ratings

Utility conditions change Electrical Redistribution (New

Transformer/MCC/Substation)

Change in relief device set pressure/size/type/discharge

location

Vessel or relief device relocation or new service

Changes in flare header size/Knock Out Drum/Flare Tip

Outcome of studies such as PHA , HAZOP or Incident

investigation


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Equipment based Pressure Relief Analysis

Pressure Relief Analysis (PRA): Key Steps1) Identify applicable Codes, Laws, Standards & Practices

→ ASME BPVC / NBIC / API standards & RP/ ANSI Standards / NFPAStandards / Best Design Practices / Local regulatory laws &

guidelines.2) Data collection & validation

→ P&IDs, PFDs, Isometrics / Process basis (H&MB) / Equipment data (drawings,U-1 forms)

→ Rotating & control equipment data (performance curves, Control valve

datasheets, orifice sizes etc.) /→ Details of latest changes & modifications / Operating & Emergency

procedures

3) Supporting tools & programs

→ PPM,PSPPM (Siemens)/ Salus (Smith & Burgess) /PSVplus(AspenTech)/ iPRSM(Farris) / SuperChems (iOMosaic)→ Aspen/ Hysys/ PROII/ FlareNET(for flare hydraulic study)/ DNV–

Phast (for Dispersion analysis / Internal programs & spreadsheets…


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Equipment based Pressure Relief Analysis

Pressure Relief Analysis (PRA): Key Steps

4) Detailed Pressure Relief Analysis

→ Overpressure scenario identification.→ Required relief rate calculations.→ PRV sizing, adequacy & reliability checks,

PRA

PRA

→ Risk ranking/categorization

→ Advise on mitigation of identified concerns→ Finalization of strategy & actions in consultation

with Client

→ Final documentation.


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Role of simulation

• Simplified calculations can often result in overdesign

• Global scenarios include utility failures• Total & Partial Power Failure

• Steam failure

• Cooling Water failure

• Instrument air failure etc

• Global scenarios often dictate the flare header sizing,

network equipment sizing and individual relief system

sizing

• Determine global scenario load from various systems

using a simulator

Relief load determination requires rigoroussimulation for global scenarios


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Steady state simulations

• Faster compared to dynamic simulations

• Critical step for most of the systems is the reduced duty

calculations at elevated pressure

Snapshot from HYSYS:

Steady state simulation is used for conservativeestimation of relief loads


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Relief simulation : Column system

Steady State set up for a typical column system

Snapshot from HYSYS for a typical column system:


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Relief simulation : Column system

Multiple flash drum set up for a high level partialpower failure scenario

Snapshot from HYSYS for a typical column system:


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Dynamic simulation

• Time dependent analysis

• Time intensive

• Pressure relief is unsteady event with continuous

changes in various process parameters

• Accounts for liquid hold-up

• Better estimate of relief rates – Estimates time for the system to reach relief pressure

• HYSYS Dynamic simulations results used effectively to:

Address flare adequacy issues due to expansion

Address flare flexibility during TAR

Avoid installation of additional relief capacity in HF Alky

unit for an isostripper based on steady state estimations

Dynamic simulation is selectively performed forcritical systems, for better estimate of relief loads


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Case Example – Ethylene Plant

• A detailed pressure relief analysis for Ethylene plant was

performed in safety analysis environment, integrated

within latest versions of Aspen Hysys software

• API overpressure scenarios were documented within Hysys

& sized with rigorous sizing methods in the software

• The safety analysis environment enabled efficient analysis

and eliminates the manual data transfer & the errors

associated with it

• The relief sizing results were effectively utilized for

mitigation and flare analysis

Revalidation of pressure relief system needed forEthylene plant due to changes in feed and capacity


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Equipment based PRA performed for Ethyleneplant involving variety of equipment

Total equipment systems ~ 200 ; Total equipment ~ 300

123

496

912

34

14960

12

0 25 50 75 100 125 150

FilterSphere

TankPiping

TurbinePump

CompressorFired Heater

ReactorHeat

VesselColumn

Equipment count


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Applicable Standards andCodesEquipment Design Relief analysis

PressureVessels ASME sec VIII

ASME sec VIII, API STD 520,API STD 521

Piping System ASME B31.3 API STD 520, API STD 521

Low PressureStorage Tanks

API STD 620, API STD650, API 12 API 2000, NFPA

Power Boilers ASME sec I ASME sec I

FiredHeaters

API STD 530, API STD560 API STD 520, API STD 521

ExchangerTubular

API STD 660, API STD661, TEMA API STD 520, API STD 521

PRA performed based on respective applicablestandards and codes


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Relief Temp Concerns3%

In appropriate Set

Pressure1%

Installation concerns

7%

Inlet Piping Pressure

Loss

38%

Miscellaneous

4%Outlet Piping

Pressure Loss

18%

Undersized

29%

PRA study reported relief device inadequacyconcerns for 78% of total equipment systems

Total equipment systems ~ 200 ; Total concerns ~ 250


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Safety Analysis Environment in Hysys

PRA performed using Safety Analysis Environmentwithin Aspen Hysys

Snapshot from Hysys : Deethanizer Column System


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PRA Result for Deethanizer column

Existing PSV (4L6 & Conventional type) onDeethanizer found to be inadequate – Capacity &Outlet Pressure Drop concerns

Snapshot from Hysys : Rating of existing PSV


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Mitigation for PSV Inadequacy

It was recommended to replace existing PSV withnew PSV (4N6 size & Balanced Bellow Type)

Snapshot from Hysys : New PSV Data


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New PSV provides adequate capacity

Snapshot from Hysys : Rating of New PSV


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No inlet and outlet piping pressure drop issuesreported for New PSV recommended

Snapshot from Hysys : Line sizing for New PSV


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Documentation Builder (1)

Microsoft access based ‘Documentation Builder’ isavailable in Hysys for relief sizing documentation

Snapshot from Hysys : Documentation Builder

ld ( )


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‘Documentation Builder’ generates calculationsummary for each of the PSVs analyzed

Snapshot from Hysys : Calculation Summary

D t ti B ild (3)


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‘Documentation Builder’ also generates summaryof relief loads for each of the PSVs analyzed

Snapshot from Hysys : Relief Device Summary

D t ti B ild (4)


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Process Datasheet of New PSV generated bydocumentation builder

Snapshot from Hysys : Process Datasheet of New PSV

D t ti B ild (5)


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Mechanical Datasheet (ISA form) of New PSVgenerated by documentation builder

Snapshot from Hysys : Mechanical Datasheet of New PSV

Integ tion ith Fl e n l i


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Integration with Flare analysis

Relief loads of PSVs can be easily imported forFlare analysis in Aspen Flare System Analyzer

Snapshot from Hysys:Importing relief loads for flare analysis

Conclusion


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Conclusion

• Ensure all equipment within the facility are protected for

various overpressure scenarios per standards and codes

• Commercially various tools are available to document

overpressure scenarios, estimate relief rates, relief

device sizing and flare header sizing

• Effectively utilize tools in the design of relief systems to

ensure safer plant operation and economical design at

the same time reducing the capital expenditure

• Robust Management of Change (MOC) process must be

in place to keep relief systems documentation updated

Process safety (relief system) information is keyelement of Process Safety Management

References


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References

1. ‘Sizing, Selection and Installation of Pressure-relieving Devices,’ API

Standard 520, Part I 9th edition.

2. ‘Pressure-relieving and Depressuring Systems’, API Standard 521, 6th

edition.

3. Jung S K, Heather J D, Dr. N.R.Singh “Proper relief-valve sizing

requires equation mastery” Hydrocarbon Processing, Dec 2011.


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Thank You

Author


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Author

Deepak Padwal is a Assistant General Manager – ProcessEngineering at INGENERO . He is currently managing multiple teamsfor process development, simulation & optimization and processsafety related work.

He received his Bachelor in Chemical Engineering degree fromInstitute of Chemical Technology (ICT), Mumbai, India, and ExecutiveMBA from S.P. Jain Institute of Management and Research, Mumbai,

India.

Before joining Ingenero, he worked for Reliance Industries Ltd, Indiaand Tata Enterprise, India.

08_Relief System Adequacy – a Step Towards SAFER Operations_Deepak_Ingenero

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