On-site solvent generation and makeup for tar solvation in an olefin plant
A system and process for generating, on-site, a sustained C 6 +C 7 aromatic rich solvent stream for tar solvation within the olefin plant employing a two-fuel oil tower system receiving a hydrocarbon feed from a quench water separator drum, where the two-fuel oil tower system is configured to make a sufficient solvent stream containing C 6 +C 7 aromatic rich hydrocarbons that is recycled and mixed with quench water going to the quench water separator drum to assist in removing tar molecules out of the quench water.
1. A system for generating on-site a C 6 +C 7 aromatic rich solvent stream, the system comprising:
a quench water separator drum having sequential compartments including a last compartment;
a primary fuel oil separation tower;
a secondary fuel oil separation tower;
a first line connecting the quench water separator drum to the primary fuel oil separation tower and configured to direct a hydrocarbon stream from the last compartment of the quench water separator drum to the primary fuel oil separation tower;
a makeup stream comprising a portion of a C 6 +C 7 aromatic hydrocarbons rich bottoms stream essentially free of C 5 hydrocarbon of a debutanizer receiving a hydrocarbon feed located downstream of an olefin plant, wherein the debutanizer is connected to the first line, and wherein the debutanizer comprises a C 5 hydrocarbon rich side draw stream;
a recycle line connecting an overhead stream of the primary fuel oil separation tower to a feed stream of the quench water separator drum; and
a second line connecting a bottoms stream of the primary fuel oil separation tower to the secondary fuel oil separation tower.
2. The system of claim 1 , further comprising a quench tower comprising a quench tower overhead stream and a quench tower bottoms stream, wherein the quench tower bottoms stream is fed to the quench water separator drum.
3. The system of claim 1 , wherein the quench water separator drum comprises a two-phase separator having tar in a top light hydrocarbon phase.
4. The system of claim 1 , wherein tar present in the feed stream to the quench water separator drum is dissolved in a hydrocarbon phase in the quench water separator drum.
5. An ethylene plant comprising:
a system for generating on-site a C 6 +C 7 aromatic rich solvent stream, the system comprising:
a quench water separator drum having sequential compartments including a last compartment;
a primary fuel oil separation tower; and
a secondary fuel oil separation tower;
a first line connecting the quench water separator drum to the primary fuel oil separation tower and configured to direct a hydrocarbon stream from the last compartment of the quench water separator drum to the primary fuel oil separation tower;
a makeup stream comprising a portion of a C 6 +C 7 aromatic hydrocarbons rich bottoms stream essentially free of C 5 hydrocarbon of a debutanizer receiving a hydrocarbon feed located downstream of an olefin plant, wherein the debutanizer is connected to the first line, and wherein the debutanizer comprises a C 5 hydrocarbon rich side draw stream;
a recycle line connecting an overhead stream of the primary fuel oil separation tower to a feed stream of the quench water separator drum; and
a second line connecting a bottoms stream of the primary fuel oil separation tower to the secondary fuel oil separation tower.
6. The ethylene plant of claim 5 , further comprising a quench tower comprising a quench tower overhead stream and a quench tower bottoms stream, wherein the quench tower bottoms stream is fed to the quench water separator drum.
7. The ethylene plant of claim 5 , wherein the quench water separator drum is a two-phase separator having tar in a top light hydrocarbon phase.
8. The ethylene plant of claim 5 , wherein tar present in the feed stream of the quench water separator drum is dissolved in a hydrocarbon phase in the quench water separator drum.