Steam-cracking of hydrocarbons

Abstract

Abstract IN ORDER TO ELIMINATE THE DEPOSIT OF HARD MATERIALS, SUCH AS COKE, DURING THE FRACTIONATION OF PRODUCTS DERIVED FROM THE STEAM-CRACKING OF HYDROCARBONSTO PRODUCE OLEFINS, THERE IS PROVIDED A PROCESS WHEREIN A MIXTURE OF STEAM WITH A HYDROCARBON FEEDSTOCK OF THE NAPHTHA TO GAS OIL RANGE INCLUSIVE IS HEATED UP TO ABOUT 500-1200* C., THE RESULTING GASEOUS CRACKED PRODUCT IS ADMIXED SUCCESSIVELY WITH A FIRST RELATIVELY COOL STREAM OF RECYCLED IQUID HYDROCARBONS AND A SECOND RELATIVELY COOL STREAM OF RECYCLED HYDROCARBONS SO AS TO SUBJECT THE CRACKED PRODUCT TO A FIRST DECREASE OF TEMPERATURE DOWN TO ABOUT 195-230*C. AND CONDENSE A PART THEREOF, THE RESULTING LIQUID FRACTION IS SEPARATED FROM THE GASEOUS, UNCONDENSED FRACTION IN A FIRST FRACTIONATION ZONE, A PORTION OF THE SAID LIQUID FRACTION, AFTER PASSAGE THROUGH A FIRST INDIRECT HEAT EXCHANGE ZONE TO LOWER ITS TEMPERATURE, IS USED AS FIRST RECYCLED LIQUID HYDROCARBON STREAM, THE GASEOUS FRACTION WITHDRAWN FROM THE FIRST FRACTIONATION ZONE IS ADMIXED WITH A THIRD, RELATIVELY COOL STREAM OF RECYLED LIQUID HYDROCARBON, IN ORDER TO FURTHER LOWER THE TEMPERATURE OF THIS GASEOUS FRACTION DOWN TO ABOUT 140-190* C. AND CONDENSE ANOTHER PORTION THEREOF, THE RESULTING GASEOUS FRACTION IS SEPARATED FROM THE RESULTING LIQUID FRACTION IN A SECOND FRACTIONATION ZONE, A PORTION OF THE LATTER LIQUID FRACTION AFTER PASSAGE THROUGH A SECOND INDIRECT HEAT EXCHANGE ZONE TO LOWER ITS TEMPERATURE, IS USED AS THE SECOND AND THIRD RECYCLED HYDROCARBON STREAMS, AND THE GASEOUS FRACTION OF THE SECOND FRACTIONATION ZONE IS WITHDRAWN, SAID FRACTION CONTAINING THE DESIRED OLEFINS.

Inventors

• 👤 Francois Bigache
• 👤 Michel Lemee

Bibliographic Details