Drum dimensions, nozzle sizes and if required, internals are shown on the process vessel sketch furnished by process engineering and included in the process release package.
Following diagram shows a typical process vessel sketch for a horizontal drum. The following information is required in order to position drum nozzles:
- Process vessel sketch.
- Instrument vessel sketch.
- Plant layout specification.
- Nozzle summary.
- Insulation Requirements.
- Plot Plan.
Following diagram shows the preferred nozzle locations for horizontal drums. The preferred locations for level instruments is away from the turbulence at the liquid outlet nozzle.
Although the vessel is provided with vortex breaker, instruments should be set in the quiet zone of the vessel – for example, on the opposite side of the weir or baffle or near the vapor outlet end.
- Process nozzles should be located a minimum from the tangent line.
- Steam-out connections should be located at the end opposite the maintenance access and vent in the bottom section of the drum.
- Pressure instruments should be located anywhere in the vapor space, preferably at the top section of the drum.
- Temperature instruments should be located anywhere in the liquid space, preferably at the bottom section of the drum.
- The vent connection should be located in the top section of the drum at the end opposite the steam out connection.
- Drain should be located in the bottom section of the drum.
- To facilitate specific elevation requirements for level instruments or positioning a maintenance access, nozzles may be located off the main axis.
- These nozzles are generally referred to as hillside nozzles.
- Tall vertical drum nozzles should be elevated and orientated using the tower subject as a guide.
- It should be noted however that nozzle locations are not restricted by internal components, as in the case of distillation tower.
- The nozzles shown below were positioned using the guidelines discussed here as well as other information contained in this handbook.
Process vessel sketch.
Instrument vessel sketch.
Plant layout specification.
Insualtion – No requirement.