Objective 03: Design and Construction Flashcards
What are some of the items assessed in a Feasibility Study, in detail?
- Size of the Plant and its main process flows
- Demand for product, e.e. electrical power, oil and gas, or chemicals
- Influence of government regulations, e.g. environmental impacts
- Economic alternatives, e.g. different process designs or plant sizes
- Choices of plant processes, fuels, auxiliary equipment, degree of instrumentation and automatic control
- Mode of operation, i.e. whether plant is run in steady state mode, is base loaded, or used for peak loads
- Choice of cycle, e.g. is it simple or cogeneration
- Choice of fuel - cost and availability, handling costs, and fixed charges
- Amount of instrumentation and automatic control
What are some of the items included in the Detailed Design, in detail?
- Detailed drawing, e.g. P&IDs
- Detailed specifications for all engineering disciplines including material specifications
- Construction drawings, including isometric piping drawings
- Process flow diagrams with mass balances
What form may Drawings take?
- Paper-based
- Computer based on CAD programs
- Combination
- Scale model of the plant equipment
- 3D computer images of the equipment
What are the 2 basic steps in Plant Design?
- Feasibility Study
- Detailed Design
What are the 3 basic steps in Plant Construction?
- Construction Company or Primary or General Contractor selected through bidding process
- They oversee construction of the plant
- Once plant is constructed, equipment is started up (commissioned)
What are the steps of the Bidding/Negotiation Phase?
- Companies with expertise to construct plant are located.
- Short list of 1-6 of the most suitable companies is compiled
- A copy of the plant design is given to each of them
- Each company supplies bid based on plant design, that details the timeline, forms of payment, and other required details
- After bids are received, bid review process analyses the competing bids
- From analysis, the winning bid is selected (usually the lowest)
What is the role of the engineering staff during the construction phase?
- Contract administration, including resolving any design changes
- Quality assurance
What are some causes of design changes?
- Omissions from the original design
- Factors that don’t comply with the original design
- Request by the Plant Owner
What is the consequence of making design changes during construction?
- More significant changes add to the cost of the project as the changes must be re-engineered and changes made to the drawings and specifications
- Smaller field changes require little or no engineering changes
What is the basic order of the construction work?
- Site grading and roads
- Excavating for underground piping and foundations
- Laying underground piping and pouring cement foundations
- Work on the main electrical supply, including installation of the main substation and motor control centres
- Placing of major pieces of equipment on their foundations
- Installing steelwork for buildings and structures
- Erection of larger buildings and furnaces
- Placing of large pressure vessels and rotating machines on their foundations
- Installation of large diameter piping
- Installation of small diameter piping, including instrumentation and electrical wiring
- Installation of small pumps, motors, and turbines
- Insulation of piping and tanks
When does pre-commissioning begin?
Once piping is complete
What is Pre-Commissioning?
Activities that must be completed before commissioning or startup of the plant can begin.
What activities are included in pre-commissioning?
- Air or steam blowing and purging of piping to remove debris, scale, and liquids; often preceded by a chemical clean
- Checking the operation of control loops from the control room to field devices such as valves and dampers
- Hydrostatic testing and leak testing of flanges and piping
- Test running pumps and motors
What is Commissioning?
Process startup of a new plant
What is the general outline of commissioning?
It is done in systems, starting with the plant offsites and utilities and working through the process until the final product.
What is important to observe for commissioing?
- Go slowly
- Follow manufacturer’s recommendations
- Adhere closely to limits on temperatures and pressures
What is an example of a Commissioning?
- Instrument and plant air systems
- Water and nitrogen purge systems
- Cooling tower and cooling water circulation
- Water pre-treatment and demineralization or softening operations
- Testing effluent and flare systems
- Steam blowing lines and commissioning the LP steam systems
- Commissioning the MP steam systems
- Bringing in fuel gas including leak checking
- Firing auxiliary or main boilers
- Starting main process in steps
- Sending product to storage
- Slowly raising plant rates
- Starting the performance test
