Equipment Sizing Reference
Reference information for sizing common process equipment based on process requirements and best practices.
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Vertical Vessel Sizing Guidelines
Reference information for vertical vessel design
Sizing Methodology
Vertical vessels are typically sized based on the required residence time and the process flow rate. The basic equation for determining vessel volume is:
Volume = Flow Rate × Residence Time
Once the volume is determined, the vessel dimensions (diameter and length) are calculated using an appropriate length-to-diameter (L/D) ratio.
Typical L/D Ratios
- Knock-out drums: 2.5 to 4
- Flash drums: 2 to 3
- Reflux drums: 2 to 3
- Storage vessels: 3 to 5
- Vertical separators: 3 to 4
Typical Residence Times
- Knock-out drums: 5 to 10 minutes
- Flash drums: 5 to 10 minutes
- Reflux drums: 5 minutes
- Surge vessels: 10 to 30 minutes
- Liquid-liquid separators: 30 to 60 minutes
Design Considerations
- Minimum liquid level for pump suction
- Vapor disengagement space (typically 15-30% of vessel height)
- Nozzle placement and orientation
- Internal components (demister pads, vortex breakers)
- Mechanical design (ASME code requirements)