SPECTROGRAPHIC DETERMINATION OF NITROGEN-CONTENT IN PETROLEUM COKE

A procedure is described for the determination of nitrogen in raw and calcined petroleum coke according to the band of cyanogen that is formed by reaction of carbon with nitrogen in the zone of an ac arc. The spectra were recorded on an ISP-51 spectrograph with a three-lens system of slit illumination. Experiments showed that with an argon flow rate of 5 liters/min, the difference in densities of the cyanogen band and the background is minimal, and remains unchanged when the purge rate is further increased. The residual content of nitrogen in the chamber is monitored by means of a blank experiment. The results obtained by the proposed method on raw cokes are compared with results obtained by the Kjeldahl method; for the calcined coke, they are compared with results obtained by the method of additions. The content of nitrogen in needle cokes is at the 0. 2% level. The lower level for determination of nitrogen content in coke is 0. 05%, and the relative standard deviation is 0. 1.