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The technique is accomplished by positioning a small radioactive source and a sensitive detector along the outside of the column.  If the spacing is held constant, the radiation field at the detector is a function of the average density between the two.  Or more simply, a dense material (liquid) blocks more radiation from reaching the detector than does a light material (vapor).

In distillation columns, the source and detector are lowered down opposite sides of the vessel (constant spacing).  Plotting the detector response versus elevation generates a unique and accurate density profile of the material inside the vessel.  (Liquid responds to the left, vapor to the right).  Performance is then readily evaluated by analyzing the liquid holdup and liquid/vapor disengagement at each tray level.

By analyzing this density profile, our engineers can readily determine:

• Damaged or missing trays.
• Aerated liquid loadings on trays
• Location and extent of flooding
• Location and severity of entrainment
• Location and density characteristics of foaming
• Downcomer liquid levels, base liquid levels
• Integrity of demister pads and distributors
• Integrity of packed beds and catalyst beds
• Draw pan integrity and liquid holdup
• Scale, coke, or ice buildup in pipes

Besides locating and identifying problem areas, nuclear scans enable your process and technical people to more fully understand their processes and the nature of instability or poor performance.

Gamma scanning can also eliminate a potential shutdown by showing that tower inefficiencies are not due to internal problems and that process personnel should concentrate their efforts to external causes.