Patent GB-978256-A (GB)
Title: Process for the continuous cracking of gasoline hydrocarbons
IPC: C10G47/00
Filed: 1963-06-20
Abstract: A process for the continuous cracking of aliphatic hydrocarbons or mixtures thereof having a boiling range of from 30 DEG  to 250 DEG C. to produce a combustible gas, comprises subjecting gasolene vapours which have been preheated to up to 300 DEG C. to a hydrogenating cracking in the presence of a gas containing at least 60 per vol. cent hydrogen and heated to 750 DEG  to 850 DEG  C. to produce a fuel gas, and then cracking some at least of the fuel gas with water vapour in externally heated nickel-catalyst-containing tubes, converting some at least of the CO in the water gas so produced to CO2 and H2, and returning some or all of the converted water gas to the hydrogenating cracking zone, any surplus fuel gas and converted water gas not so recycled constituting, alone or in admixture, the product of the process.  Two main embodiments are described in detail.  In the first, a light gasoline having a final boiling point of 80 DEG C. and having a CH ratio of 5.29 is gasified to produce a gas interchangeable with town gas and having a calorific value of 4300 Kcal./Nm.3 and a density of 0.5.  The first cracking step produces a fuel gas containing 64.3 vol. % CH4, part of this gas being catalytically gasified with water vapour heated to at least 300 DEG  C. in the proportion 1 volume of fuel gas to 1 to 3 volumes water vapour.  Air may be added in the proportion 7 volumes water vapour to 1 volume air.  The cracking temperature is 780 DEG  to 820 DEG  C. CO conversion is carried out catalytically after cooling, and CO2 is washed out. The process is adapted to all feeds boiling below 250 DEG  C. and consisting mainly of paraffinic hydrocarbons, the quantities of recycle gas and water vapour, and the extent of CO conversion and CO2 washing being varied to suit the feed. If the feed contains sulphur, a desulphurizer must be employed between the cracking stages, e.g. using ZnS at 250 DEG  C.  In the second embodiment, a substitute for natural gas is made using a feed having a final boiling point of 185 DEG C. and having a CH ratio of 5.99, cracking taking place at up to 25 atmospheres, and all the converted water gas is recycled, the surplus fuel gas from the first cracking stage, which is methane-rich (46 to 50 vol. per cent) being CO-converted and washed, if desired after traversing a cold desulphurizer.ALSO:A process for the continuous cracking of aliphatic hydrocarbons or mixtures thereof having a boiling range of from 30 DEG  to 250 DEG  C. to produce a combustible gas, comprises subjecting gasolene vapours which have been preheated to up to 300 DEG  C. to a hydrogenating cracking in the presence of a gas containing at least 60 volume per cent hydrogen and heated to 750 DEG to 850 DEG  C. to produce a fuel gas, and then cracking some at least of the fuel gas with water vapour in externally heated nickel-catalyst-containing tubes, converting some at least of the CO in the water gas so produced to CO2 and H2, and returning some or all of the converted water gas to the hydrogenating cracking zone, and surplus fuel gas and converted water gas not so recycled constituting, alone or in admixture, the product of the process. Two main embodiments are described in detail.  In the first, a light gasoline having a final boiling point of 80 DEG  C. and having a CH ratio of 5.29 is gasified to produce a gas interchangeable with town gas and having a calorific value of 4300 KCal/Nm3 and a density of 0.5.  The first cracking step produces a fuel gas containing 64.3 volume per cent CH4, part of this gas being catalytically gasified with water vapour heated to at least 300 DEG  C. in the proportion 1 volume of fuel gas to 1 to 3 volumes water vapour.  Air may be added in the proportion 7 volumes water vapour to 1 volume air. The cracking temperature is 780 DEG  to 820 DEG  C. CO conversion is carried out catalytically after cooling, and CO2 is washed out.  The process is adapted to all feeds boiling below 250 DEG  C. and consisting mainly of paraffinic hydrocarbons, the quantities of recycle gas and water vapour, and the extent of CO conversion and CO2 washing being varied to suit the feed.  If the feed contains sulphur, a desulphurizer must be employed between the cracking stages, e.g. using ZnS at 250 DEG  C. In the second embodiment, a substitute for natural gas is made using a feed having a final boiling point of 185 DEG  C. and having a CH ratio of 5.99, cracking taking place at up to 25 atmospheres, and all the converted water gas is recycled, the surplus fuel gas from the first cracking stage, which is methane-rich (46 to 50 volume per cent) being CO-connected and washed, if desired after traversing a cold desulphurizer.