Determination of Sulfur in Petroleum Products by Fast-neutron Activation and the Interfering Elements

Abstract

In a previous paper, a rapid nondestructive method to determine sulfur in petroleum products with 14 MeV neutrons was reported. The correction for oxygen, the predominant interfering element, was made, but the results showed a little positive bias.
In the present paper, further experiments with the error are described, together with a counting technique and the precisions.
It is shown through a calculation that, in the case of middle east crude oils, nitrogen has a great contribution to the bias; this is experimentally confirmed by the decay curves for three crude oils (each-Saran, Kuwait, and Khafji) and three commercial products (gas oil, and light and medium fuel oils) and by their spectra. Accordingly, a counting technique which chiefly reduces the effect of nitrogen is adopted. The biases observed in this way are +0.06 S% for the gas oil, +0.09 S% for the light fuel oil, and +0.11 S% for the medium fuel oil. The relative standard deviations are 2.4% for the medium fuel oil containing 2.40 %S and 7.4% for the gas oil containing 0.54%S.