Process for decreasing the coking of heat exchange surfaces

摘要

The invention relates to a process for decreasing the coking of heat exchange surfaces in a shell and tube heat exchanger made of boiler steel which, in particular within a plant for thermocracking hydrocarbons to form alkenes, downstream of the cracking furnace with production of steam, performs rapid cooling of the cracked products. According to the invention it is proposed that the sides of the heat exchange surfaces coming into contact with the cracked products, after cleaning has been carried out, before re-use of the shell and tube heat exchanger, are treated under reducing conditions until reduction of Fe2O3 at the surface to Fe3O4 has occurred as far as possible without submicron Fe powder being formed in the course of this.