Design basis - PROCESS DESIGN FUNDAMENTALS
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The document discusses the importance of establishing a thorough design basis for engineering projects. It states that the design basis sets key parameters that impact all aspects of a project, including costs, safety, and operability. It emphasizes that developing the design basis is crucial as decisions made early in conceptual design have significant effects on the overall project. The design basis should document requirements, expectations, site conditions, raw materials and products, utilities, storage, operating philosophy and other factors to properly guide the engineering design.
Design basis - PROCESS DESIGN FUNDAMENTALS
- 1. Design Basis
- 2. Design Basis Considerations The development of a Design Basis Memorandum (DBM) should be done for every project undertaken • • The and The DBM documents the project requirements, expectations philosophies DBM benefits and protects the project sponsors and• project designers by establishing communication 2
- 3. The Importance of Design Basis • The design basis has tremendous impact project- on all aspects of a • • • • • • Investment Safety Operability and Operating Cost Basic Design Engineering Construction Operation Maintenance Revamp/ HAZOP Feasibility Study Concept Concept Constructability Maintainability Profitability • The conceptual and feasibility stage help to set up the design basis. 3
- 4. The Impact of Initial Phase of Design Activities The development of design basis is often overlooked by the owner as well as the engineering consultant. • • 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. A thorough 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. 4
- 5. The Impact of Initial Phase of Design Activities Concept, Design Basis and Basic Design 5
- 6. Key Issues for Design the Process Basis 1. Project Description 4. • • • Raw Material Source and Composition Raw Material Source Transportation Mode Raw Material Composition • • • Project Name Ownership Brief Description 5. • • • • Products Product Slate Product Specification Product Destination Dispatch Mode 2. • • • • • Plant Capacity Related Capacity Stream Factor Turndown Ratio Operating Philosophy Safety Management Philosophy 6. • • • • Battery Limit Related B/L Definition B/L Temp. and Pr. Raw Material & Products Utilities & Storage 3. • • • • • Location and Site Data Location Map Site Map Site Data Surrounding Details Access 7. • • HSE Environmental Permit / Regulatory Requirements HSE (or other) project commitments (EIA, QRA, other?) 6
- 7. 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 BPSD Product Slate • Petrochemical Plants- – Often defined by product capacity 7
- 8. On-Stream Factor (Plant On-Stream factor depends on- Availability) • – – 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 production facilities. • On-Stream factor has a huge influence on the process concept and costs of the project. – – Sparing Philosophy Layers of Protection & Safety Shutdown systems 8
- 9. On-Stream A basic scheme for oil and Factor - Exercise • gas production is given below. The owner wants to be able to deliver gas to the gas pipeline 98% of the time. What are things to consider given: Pipeline – 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 – Treatment – Or re-injection– 9 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
- 10. Impact of Site Data on Process Design and Costs Critical site data for process design are-• – – – – – – – – Contour diagram Elevation Maximum Design Ambient Temperature Minimum Design Ambient Ambient Pressure Humidity Wind Direction Rainfall data Temperature 10
- 11. Case Study How Site Affects Design & Cost • The scheme below had to be implemented…. Dehydrator Pipeline Separator Water Oil (Liquid) (3 bar) Storage Oil Pipeline Water discharge • In a hilly terrain like this…. Any advantage of the terrain? 20 M • Cooling considerations 11 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
- 12. Case Study Maximum Design Ambient Temp Metrological department gives temperature profile around the year for several years. Designer should recommend maximum and minimum design ambient • • temperatures and maximum solar radiation temperature. • Propane Refrigerant Make-up Plant • • Desert Location Maximum Design Ambient Temp. oCtaken as 55 • • • oCRequired propane temperature < 50 Turnkey skid mounted supply. Solar radiation requires protection against thermal expansion 12 Air Cooler PACKING LPG Feed Propane TRAYS Butane
- 13. Wind Direction Gas Processing Plant producing LPG out of natural gas Wind direction reported 75% times South East to North West Large Flare to be located 90 M away. Where shall you locate the flare • • • • stack? Control Room? Administration Building? Muster Points• 13 Prevailing Wind Direction
- 14. Wind Direction Bhopal MIC leak was a major disaster.• • • Prevailing Wind 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 to Know • Operators Escape 14
- 15. Raw Material and Product Specification 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. • • • – Gasoline production facility in a refinery to produce to as international spec. Resultant product quality considerations include: Indian spec as well • – – – The need for online analyzers Sampling points Possibly even the need for check tanks 16
- 16. Utilities and Storage Storage and HandlingUtility Related Issues • • • • • • • • • • • • • • • Fuel / Power / Steam Instrument and Plant Raw Material Storage Criteria Raw Material Receipt Product Storage criteria Product Dispatch Intermediate Product Storage Criteria Chemical Storage Criteria Yard Piping Emission Limitations – Tank Design – Vapor Recovery Air Raw Water Specification Cooling Water Sea Water Process water • • • Effluent Discharge Flaring Philosophy Specifications Major Effluents Summary Effluent Treatment Requirements 17
- 17. Other Operation and Maintenance Issues • • Buildings and Misc. Offsites – – – – – – – Equipment Sparing Philosophy Instrumentation and Control Philosophy Safety Shutdown Systems Operating Philosophy Office Maintenance Facilities Fire Fighting Facilities Entry Gate Control Room – – 18
- 18. Utilities Design Key Issue Optimization between Fuel, Power and importance 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 stages in evolving cost saving concepts. helps 19
- 19. Storage Design Basis Key Issues • Storage has a cost both in terms of investment and inventory cost. • Storage design basis is dictated by- • • • • Internal operational requirements Downstream operators limitations Engineering 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 20 January 17, 2013
- 20. Operating Philosophy Design Basis Key Issues • • Highly automated or not? Unmanned remote operation totally changes instrumentation concept. 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 power instead of generator for instrument power. • • • • 21
- 21. 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 design basis Time spent upfront to develop comprehensive Design Basis will prevent significant costs in rework later in the project. • • • • 22