Post on 19-Feb-2017
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
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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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