Design Basis

Design Basis Considerations

The development of a Design Basis Memorandum (DBM)should be done for every project undertaken

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• Theand

The

DBM documents the project requirements, expectationsphilosophies

DBM benefits and protects the project sponsors and•

project designers by establishing communication

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The Importance of Design Basis

• The design basis has tremendous impactproject-

on all aspectsof a

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Investment

Safety

Operability

and Operating CostBasic

DesignEngineeringConstruction

Operation

MaintenanceRevamp/HAZOP

FeasibilityStudy

Concept

ConceptConstructability

Maintainability

Profitability

• The conceptual and feasibility stage help to set up thedesign basis.

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The Impact of Initial Phase ofDesign Activities

The development of design basis is often overlooked by the owner as well as the engineering consultant.

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• The conceptual and feasibility stage help to set up the design basis.

• Every single line in a design basis should have thought and analysis behind it. Athorough study of key issues is needed to establish a proper design basis.

• The graph in the next slide shows the impact of actions taken in early stages of project.

• The best cost reduction exercise can be done at the design basis stage itself.

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The Impact of Initial Phase ofDesign Activities

Concept, Design Basisand Basic Design

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Key Issues forDesign

the ProcessBasis

1. Project Description 4.•

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Raw Material Source and CompositionRaw Material SourceTransportation ModeRaw Material Composition

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Project NameOwnershipBrief Description

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ProductsProduct SlateProduct SpecificationProduct DestinationDispatch Mode

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Plant Capacity RelatedCapacityStream FactorTurndown RatioOperating PhilosophySafety Management Philosophy 6.

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Battery Limit RelatedB/L DefinitionB/L Temp. and Pr.Raw Material & ProductsUtilities & Storage

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Location and Site DataLocation MapSite MapSite DataSurrounding DetailsAccess

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HSEEnvironmental Permit / Regulatory RequirementsHSE (or other) project commitments (EIA, QRA, other?) 6

Capacity Related Parameters

Capacity is decided based on market survey and projection, which is part of feasibility study.•

• Capacity is defined in a number of ways depending on the type of project.

• Oilfield-– In oilfield it is described by oil production in BPD or MMTPA, Gas Oil Ratio (e.g. SM3 gas per M3 oil) and

water percent.Production profile over field life also is important capacity parameter.–

• Refinery-––

Crude Processing capacity in BPSDProduct Slate

• Petrochemical Plants-– Often defined by product capacity

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On-Stream Factor (Plant

On-Stream factor depends on-

Availability)

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Planned maintenance shutdown requirements.Unplanned shutdowns.

• Normally in a complex process plant, 330 days a year is considered a good basis.

• Some may require operation for a few months or even a few weeks a year.

• But certain critical projects may call for 365 days a year. It is quite common in oil/gas productionfacilities.

• On-Stream factor has a huge influence on the process concept and costs of the project.––

Sparing PhilosophyLayers of Protection & Safety Shutdown systems

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On-Stream

A basic scheme for oil and

Factor - Exercise

•gas production is given below. The owner wants to be able to deliver gas tothe gas pipeline 98% of the time. What are things to consider given:

Pipeline

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Separator vessels have a 99% Availability.

Dehydrators require 8 hour regeneration

time every 2 days.

Historical data shows rotating equipment is

available 90% of the time

Control valve loops can fail multiple times

per year and take a few hours

to repair each time

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Treatment–

Or re-injection–

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M

Gas M Cooling

Dehydrator Gas to

HP Compressor

Separator

LP

Water Oil (Liquid) Separator

Water Atm.

Water Storage Oil Oil /Liquid

Dehydration Pipeline

Water discharge Pump

Impact of Site Data on ProcessDesign and Costs

Critical site data for process design are-•

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Contour diagram

Elevation

Maximum Design Ambient Temperature

Minimum Design Ambient

Ambient Pressure

Humidity

Wind Direction

Rainfall data

Temperature

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Case StudyHow Site Affects Design & Cost

• The scheme below had to be implemented….

Dehydrator Pipeline

Separator

Water Oil (Liquid)(3 bar)

Storage

OilPipeline

Water discharge

• In a hilly terrain like this…. Any advantage of the terrain?

20 M

• Cooling considerations11

M

Natural gas Gas M Cooling Gas to

Well Fluid HP Compressor

(15 bar)

LP

Separator

Water Atm.

Treatment Water 10 MMTPA 600,000 M3 Oil /Liquid

Dehydration

Or re-injection Pump

Case StudyMaximum Design Ambient Temp

Metrological department gives temperature profile around the year for several years.

Designer should recommend maximum and minimum design ambient

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•temperatures and maximum solar radiation temperature.

• Propane Refrigerant Make-up Plant

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Desert Location

Maximum Design Ambient Temp.oCtaken as 55

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oCRequired propane temperature < 50

Turnkey skid mounted supply.

Solar radiation requires protectionagainst thermal expansion

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Air

Cooler

PACKING

LPG Feed Propane

TRAYS

Butane

Wind Direction

Gas Processing Plant producing LPGout of natural gas

Wind direction reported 75% timesSouth East to North West

Large Flare to be located 90 M away.

Where shall you locate the flare

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•stack? Control Room?Administration Building?

Muster Points•

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Prevailing

Wind Direction

Wind Direction

Bhopal MIC leak was a major disaster.•

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PrevailingWind Direction

Thousand died or were affected.

Lesson Learned: Location of a plant dealing with hazardous materials must:

Leaked MIC

– Have Emergency Management Plans that• Identify mitigative measures to manage

risks– Buffer zones around the plant - downwind

Emergency Response Plan that includes

– Train operators so that they can save themselves. – understand evacuation plan and importance of wind direction.

– Community Involvement – ACC Right toKnow

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Operators Escape

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Raw Material and ProductSpecification

Processing scheme and operating conditions are dictated by product specification.The plant needs to be designed with some flexibility on raw material and product specifications.The flexibility need to be spelt out in the design basis. Example-– Range of natural gas composition for a gas processing plant.

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– Gasoline production facility in a refinery to produce to as international spec.

Resultant product quality considerations include:

Indian spec as well

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The need for online analyzersSampling pointsPossibly even the need for check tanks

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Utilities and Storage

Storage and HandlingUtility Related Issues••

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Fuel / Power / SteamInstrument and Plant

Raw Material Storage CriteriaRaw Material ReceiptProduct Storage criteriaProduct DispatchIntermediate Product StorageCriteriaChemical Storage CriteriaYard PipingEmission Limitations– Tank Design– Vapor Recovery

AirRaw Water SpecificationCooling WaterSea WaterProcess water

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Effluent DischargeFlaring Philosophy

Specifications

Major Effluents SummaryEffluent Treatment Requirements

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Other

Operation and Maintenance

Issues

• • Buildings and Misc. Offsites

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Equipment Sparing Philosophy

Instrumentation and ControlPhilosophy

Safety Shutdown Systems

Operating Philosophy

Office

Maintenance Facilities

Fire Fighting Facilities

Entry Gate

Control Room

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Utilities DesignKey Issue

Optimization between Fuel, Power andimportance at today’s energy cost.

Basis

• Steam is of great

• Combined cycle power generation and waste heat utilization key issues.

are

• Cooling Water vs. Air Cooler is also a key issue.

• Keeping the utility parameters floating at design basis stagesin evolving cost saving concepts.

helps

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Storage Design BasisKey Issues

• Storage has a cost both in terms of investment and inventory cost.

• Storage design basis is dictated by-

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Internal operational requirementsDownstream operators limitationsEngineering limitations- what size of tanks?Tanker logistics – requiring operations research studies.

• Storage could also be dictated by strategic reasons.

• Keeping the utility parameters floating at design basis stages concepts.

helps in evolving cost saving

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January 17, 2013

Operating PhilosophyDesign Basis Key Issues

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Highly automated or not?Unmanned remote operation totally changes instrumentationconcept.Unmanned concept is common in oil and gas production, pipelines,small plants in remote areas.SCADA with telemetry tele-control concept is utilized in such cases.Rotating machinery is avoided as far as possible.For example, remote operated well platforms have solar powerinstead of generator for instrument power.

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Summary and Conclusion

The Design Basis Communicates Expectations, Requirements and Preferences

Decisions made in the development of the design basis affects the concept and cost of the process plant.

Critical Economic Analyses are needed to develop the designbasis

Time spent upfront to develop comprehensive Design Basis willprevent significant costs in rework later in the project.

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