Apparatus for the catalytic cracking of hydrocarbons

A process for the fluidized catalytic cracking of hydrocarbon feedstocks in multiple reactors which comprises:

• (a) passing a fluidized mixture of catalyst particles and a first hydrocarbon feedstock upwardly through a first elongated transfer line reactor under effective cracking conditions, whereby catalytic cracking of said first hydrocarbon feedstock is effected;
• (b) passing a fluidized mixture comprising catalyst particles and hydrocarbon vapors, including cracked hydrocarbon products, from said first transfer line reactor to a reactor vessel communicating with and enclosing the upper end of said first transfer line reactor;
• (c) passing hydrocarbon vapors and entrained catalyst particles from said vessel to a first cyclone separation system located within said vessel and adapted to separate catalyst particles from vapors, which comprises at least one cyclone gas-solids separation means having a dip-leg depending therefrom whereby entrained catalyst particles are separated from the vapors and returned to said vessel;
• (d) passing said vapors from said first cyclone separation system to a product recovery zone;
• (e) passing a fluidized mixture of catalyst particles and a second hydrocarbon feedstock upwardly through a second elongated transfer line reactor under effective cracking conditions, whereby catalytic cracking of the second hydrocarbon feedstock is effected, and wherein said first and second hydrocarbon feedstocks are the same or different;
• (f) passing a fluidized mixture comprising catalyst particles and hydrocarbon vapors, including cracked hydrocarbon products, from an upper portion of said second transfer line reactor to a second cyclone separation system located within said vessel, directly connected by an inlet means to the upper end of said second transfer line reactor, and adapted to separate the mixture of catalyst particles and vapors which is discharged from said second transfer line reactor, wherein said second cyclone separation system comprises at least one cyclone gas-solids separation means having a dip-leg depending therefrom, and whereby the vapors from said second transfer line reactor are substantially separated and prevented from entering said vessel and catalyst from the second transfer line reactor is separated and passed into said vessel;
• and
• (g) passing said vapors from said second cyclone separation system to said product recovery zone and recovering therein cracked hydrocarbon products from said vessel and said second transfer line reactor.

A process for the fluidized catalytic cracking of hydrocarbon feedstocks in multiple reactors which comprises:

• (a) passing a fluidized mixture of catalyst particles and heavy hydrocarbon feedstock upwardly through a first elongated transfer line reactor under effective cracking conditions, whereby catalytic cracking of the heavy hydrocarbon feedstock is effected;
• (b) passing a fluidized mixture comprising catalyst particles and hydrocarbon vapors, including cracked hydrocarbon products, from said first transfer line reactor to a reactor vessel communicating with and enclosing the upper end of said first transfer line reactor;
• (c) passing hydrocarbon vapors and entrained catalyst particles from said vessel to a first cyclone separation system located within said vessel and adapted to separate catalyst particles from vapors, which comprises at least one cyclone gas-solids separation means having a dip-leg depending therefrom whereby entrained catalyst particles are separated from the vapors and returned to said vessel;
• (d) passing said vapors from said first cyclone separation system to a first product recovery zone and recovering a hydrocarbon fraction comprising at least 25 weight percent mono-aromatic hydrocarbons and boiling in the range from about 110.degree. to about 260.degree. C.;
• (e) passing a fluidized mixture of catalyst particles and a naphtha feedstock upwardly through a second elongated transfer line reactor under effective cracking conditions, whereby catalytic cracking of the naphtha feedstock is effected, and wherein said naphtha feedstock comprises at least a portion of the hydrocarbon fraction from step (d) in combination with from 0 to 20 volume percent of another vaporizable hydrocarbon fraction;
• (f) passing a fluidized mixture comprising catalyst particles and hydrocarbon vapors, including cracked hydrocarbon products, from an upper portion of said second transfer line reactor to a second cyclone separation system located within said vessel, directly connected by an inlet means to the upper end of said second transfer line reactor, and adapted to separate the mixture of catalyst particles and vapors which is discharged from said second transfer line reactor, wherein said second cyclone separation system comprises at least one cyclone gas-solids separation means having a dip-leg depending therefrom, and whereby the vapors from said second transfer line reactor are substantially separated and prevented from entering said vessel and catalyst from the second transfer line reactor is separated and passed into said vessel;
• and
• (g) passing said vapors from said second cyclone separation system to a second product recovery zone and recovering therein cracked hydrocarbon products from said second transfer line reactor.