Verfahren zur Spaltung von Kohlenwasserstoff-Einsätzen und unhydrierten C¶4¶-Fraktionen

摘要

The invention concerns a process for the joint cracking of hydrocarbon charges (1), especially naphtha, and non hydrogenated C4 fractions (4b) in pyrolysis furnaces to produce olefines, in which the whole of the charge to be cracked is preheated in the convection region of the pyrolysis furnace by the flue gases from the radiant region with the addition of process steam (4a) and then subjected to thermal cracking in the radiant region. According to the invention, the C4 fraction (4b) is not fed into the convection region together with the hydrocarbon charges, as is usual, but is heated in mixture with process steam (4a) in the convection region (9) and then mixed with the hydrocarbon charge (2, 5) and reheated together before being fed into the radiant region (10). The heated mixture of process steam and C4 fraction can be mixed with the hydrocarbon charge at several points. Advantageously, in the process of the invention, superheated process steam is introduced or the process steam in the mixture of it and C4-hydrocarbons is superheated before being mixed with the hydrocarbon charge. Particular advantages are obtained if the C4 fraction amounts to up to 25% wt. and preferably up to 10% wt. of the hydrocarbon charge. The C4 fraction may consist of up to 100% wt., and preferably 30 to 60% wt., of butadiene.