Process and apparatus for separating C5 di-olefins from pyrolysis gasoline
Apparatuses, systems and methods for producing Pips stream for manufacturing catalytic C5 hydrocarbon resins containing all the key reactive monomers that are already present in the C5 fraction of the pyrolysis gasoline, which is otherwise lost with the crude isoprene stream, are disclosed herein. Embodiments of the invention are directed to producing a hydrocarbon resin grade DCPD stream consisting of dimers and codimers of isoprene which are of value in manufacturing thermal hydrocarbon resins, either polymer grade isoprene and gasoline quality raffinate (free or sulfur and acetylenes) or a relatively small crude isoprene stream with maximum utilization of isoprene by moving some of the isoprene to a DCPD stream used to manufacture thermal hydrocarbon resins.
1. A process for separating dicyclopentadiene (DCPD), piperylenes and isoprene from a C5 feed, the process comprising the steps of:
providing a C5 feed comprising isopentane, isoprene, cyclopentadiene, and piperylenes to a lights removal column;
separating isopentane from the C5 feed into a first lights fraction;
removing the remaining C5 feed into a first heavy bottoms fraction from the lights removal column;
feeding the first heavy bottoms fraction to a heat exchanger;
feeding the first heavy bottoms fraction from the heat exchanger to a first dimerization system to form a dimerized mixture comprising DCPD, isoprene, piperylenes, and unreacted cyclopentadiene;
passing the dimerized mixture through a C5 splitter column;
extracting isoprene from the C5 splitter column into a second lights fraction;
passing the second lights fraction through a two stage extractive distillation column/solvent recovery column system having an impurity removal system and a raw isoprene fractionation system disposed between a first and a second extractive distillation column/solvent recovery column system of the two stage extractive distillation column/solvent recovery column system;
recycling cyclopentadiene (CPD) from the raw isoprene fractionation system to the first dimer system;
collecting a second heavy bottoms fraction from the C5 splitter column containing DCPD and piperylenes;
passing the second heavy bottoms fraction from the C5 splitter column to a second dimerization system;
passing a fraction comprising DCPD and piperylenes from the second dimerization system to a piperylenes extraction column to extract piperylenes; and
passing a third heavy bottoms fraction comprising DCPD from the piperylenes extraction column to a DCPD extraction column to extract DCPD;
wherein the impurity removal system comprises a sulfur removal unit, an oxygenates removal unit, and an acetylene removal unit, each of which are disposed between the first extractive distillation column and the second extractive distillation column of the two stage extractive distillation column/solvent recovery column system.
2. The process of claim 1 , wherein the C5 splitter column comprises a minimum of 75 to 85 theoretical stages.
3. The process of claim 1 , wherein the process in the C5 splitter column is carried out at an overhead temperature range of 55° C. to 70° C.
4. The process of claim 1 , wherein the second dimerization system is operated at a temperature between 80° C. to 130° C.
5. The process of claim 1 , further comprising the step of passing the extracted isoprene through an isoprene extraction unit to produce polymer grade isoprene.
6. The process of claim 1 , further comprising removing bisulfides and oxygenates from the piperylenes from the piperylenes extraction column.
7. The process of claim 1 , wherein the first dimerization system comprises at least two dimer drums arranged in a parallel arrangement.
8. The process of claim 1 , wherein the second dimerization system comprises at least two dimer drums arranged in a parallel arrangement.
9. The process of claim 1 , wherein the first dimer system comprises a vessel with overhead vent control and an exchanger for temperature control.
10. The process of claim 1 , wherein the first dimer system comprises an isothermal heat exchanger with a vaporizing medium on a shell side of the of the isothermal heat exchanger.
11. The process of claim 1 , wherein the first dimer system comprises a tank with circulation pumps for temperature control and mixing.