초록 ▼

A flexible steam cracking process for hydrocarbon feeds comprises injection of particles with an average size of between 0.02 mm and 4 mm, at a circulation rate in indirect transfer line exchangers (4) of 20 to 180 m/s, and in a sufficient quantity to limit the increase in temperature at the outlet

A flexible steam cracking process for hydrocarbon feeds comprises injection of particles with an average size of between 0.02 mm and 4 mm, at a circulation rate in indirect transfer line exchangers (4) of 20 to 180 m/s, and in a sufficient quantity to limit the increase in temperature at the outlet to the exchangers (4) to a value of less than 100.degree. C. per month, into at least one point upstream of an indirect transfer line exchanger (4), cracking zone (2) remaining in communication with downstream means (6) for the treatment of cooled effluents. At least 70% by weight of the quantity of injected particles is introduced between the outlet to the cracking zone (2) and the tubes of the indirect transfer line exchanger (4). Chemical decoking is carried out in the tubes of the cracking zone at time intervals of less than 4 months by establishing accelerated coke gasification conditions, for example by injecting compounds which catalyse gasification by steam, or by decoking in air and/or steam.

대표청구항 ▼

[ We claim:] [1.] A process for steam cracking hydrocarbon feeds in a steam cracking facility comprising at least one steam cracking furnace which comprises at least one cracking zone (2) containing pyrolysis tubes, connected via a transfer zone (3) to indirect cooling means (4) for the effluents fr

[ We claim:] [1.] A process for steam cracking hydrocarbon feeds in a steam cracking facility comprising at least one steam cracking furnace which comprises at least one cracking zone (2) containing pyrolysis tubes, connected via a transfer zone (3) to indirect cooling means (4) for the effluents from that cracking zone (2), and downstream means (6) for the treatment of the cooled effluents, the process comprising injection of solid erosive particles upstream of the indirect cooling means (4) to eliminate at least a portion of the carbon-containing deposits located on the internal walls of the facility, the cracking zone remaining in communication with the downstream means (6) during the particle injection phases, the process being characterized in that:a) during a steam cracking cycle, solid erosive particles are injected with a diameter in the range 0.02 mm to 4 mm, at at least one point in the transfer zone (3), the particles then circulating in the indirect cooling means, transported by a carrier gas with an average velocity in the range 20 to 180 m/s,the average amount, Q, of particles injected into said transfer zone during a steam cracking cycle being at least 0.7 times the overall average amount, [Q+q], with respect to the cracked gases, of particles injected upstream of the indirect cooling means (4) during the same steam cracking cycle, q being the average amount of particles introduced into and/or upstream of said cracking zone;the overall average amount, [Q+q] of injected particles being set so as to limit the increase in the temperature at the outlet from the indirect cooling means (4) to a value of less than 100.degree. C. per month,b) in the cracking zone (2), either continuously or discontinuously at intervals not exceeding 4 months, establishing accelerated coke gasification conditions to maintain the operation of the cracking zone. [25.] A steam cracking facility comprising at least one steam cracking furnace (20) comprising at least one cracking zone (2) containing pyrolysis tubes connected downstream via a transfer line (3) to at least one indirect transfer line exchanger (4), and downstream means for treatment of the effluent connected to said exchanger, characterized in that it comprises:means (7) for dosing and injecting solid erosive particles, these means (7) being connected to the transfer line (3) to introduce at least 70% by weight of solid particles injected upstream of the transfer line exchanger and connected either directly to the cracking zone or upstream of said zone;means for measuring the temperature of the effluent at the outlet to the transfer line exchanger (4) to control its fouling;and means (15, 17, 18) for chemical decoking connected upstream of the pyrolysis tubes in the cracking zone (2), to establish accelerated gasification conditions for the coke in this zone (2).