A Process Consulting Services feasibility study develops process flow schemes, product yields and quality, sized equipment lists, utilities requirements, and cost estimates based on crude blend. Because more engineering is completed during a feasibility study than during a scoping study, the cost estimate will be of a higher quality. Sufficient work will be done to provide accurate information to the cost estimators, but final equipment design is not required at this stage. In our experience, poor cost estimates result from incorrect process flow schemes and are rarely affected by minor changes in equipment sizing.
Consider an example where a refiner wishes to revamp a unit to process high percentage blends of Eagle Ford crudes. It may be determined that an existing desalter is large enough because the crudes are light and low viscosity. However, we know that these crudes tend to form stabilized emulsions due to high solids contents which leads to problems in small desalters. The solids are not effectively removed and periodic rag formation results in high salt carryover from the desalters. This salt carryover results in severe corrosion in the crude overhead system and short heater run length due to solids laydown in the heater tubes. Under these conditions, crude unit run length can be as short as 3-6 months. A feasibility study will either identify changes in the process flow scheme and equipment design necessary to prevent these problems or will predict frequent shutdowns so that they can be factored into the project economics. Sufficient engineering work is performed to identify all process and equipment changes or to determine the likelihood of unscheduled outages.