METHOD FOR DETERMINING LIQUID-VAPOR INTERFACE VIA GAMMA RADIATION

摘要

A method for determining the position of a liquid interface between a lower tray and an upper tray in a process apparatus such as a distillation column, using gamma scanning and comparing the maximum count rate of gamma photons measured between two trays with the count rate attributed to scanning through the apparatus filled with vapour. The method enables the operating parameters of the apparatus to be optimized and provides a manner of calculating the % flood of an individual tray.

主权项

1. A method for determining the position of a liquid interface between a lower tray and an upper tray in a process apparatus comprising the steps of:
a) arranging a source of gamma radiation and a detector for said gamma radiation at opposed ends of a horizontal path P through said process apparatus, said path P being located at a vertical location between the height of said lower and upper trays and at height H above said lower tray; b) counting the amount of radiation emitted by the source which is detected by the detector; c) carrying out steps a) and b) N times to acquire N data points Dn, each consisting of the count rate Cn counted by the detector measuring radiation transmitted along path Pn at height Hn above said lower tray, each path Pn being of the same length and H1 being at or immediately above the height of the lower tray; d) defining the count rate CV to be the count rate when the path through the process apparatus passes through a vapour phase; e) identifying CMAX where CMAX=the maximum of measured count rates Cn between said lower tray and said upper tray; and f) estimating the height HL of the liquid interface by:
i. if CMAX≦CV and CMAX≧CV−x % of CV then HL=Hn at CMAX; orii. if CMAXCV−x % of CV then extrapolate data points, including Dn at CMAX and at least Dn−1 and Dn−2, to find HL where extrapolated line meets CV.