| 摘要 |
Process for the manufacture of olefins and diolefins by cracking of gaseous hydrocarbons with steam, consisting in passing through radiation region of a furnace a mixture of gaseous hydrocarbons and steam moving in a cracking tube placed inside this region, in a mean residence time of between 300 and 1800 milliseconds, under a furnace outlet pressure of between 120 and 240 kPa, which process is characterised in that: a. The cracking temperature of the mixture of gaseous hydrocarbons and steam increases from the inlet temperature of the radiation region of between 500 and 700 DEG C to the outlet temperature of this region of between 800 and 880 DEG C, and b. The reaction volume of the second half of the length of the cracking tube, situated towards the outlet of the radiation region, is from 1.3 to 4 times greater than that of the first half of the length of the tube, situated towards the inlet of this region. <IMAGE>
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