Mineral oils: processes and products – Chemical conversion of hydrocarbons – Plural serial stages of chemical conversion
Reexamination Certificate
2002-02-27
2004-09-14
Griffin, Walter D. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Plural serial stages of chemical conversion
C208S211000, C585S318000, C585S319000, C585S329000, C585S362000
Reexamination Certificate
active
06790342
ABSTRACT:
FIELD OF THE INVENTION
This invention is related to the field of processes wherein a cracked gas stream is separated to produce dilute olefin streams to be used as feedstocks to produce olefin-based derivatives. Specifically, this invention is related to the field of processes wherein a cracked gas stream is separated to produce a dilute ethylene stream and a dilute propylene stream to be used as feedstocks for producing olefin-based derivatives. More specifically, the dilute ethylene stream is used as a feedstock to produce ethylbenzene, and the dilute propylene stream is used as a feedstock to produce cumene, acrylic acid, propylene oxide or other propylene based derivatives.
BACKGROUND OF THE INVENTION
Feedstock costs in the chemical industry comprise a significant portion of the manufacturing costs. Continuous research is being conducted to lower these costs by utilizing lower cost feed sources. The alkylation of benzene and other aromatics is one area where dilute olefin streams are employed to reduce feed related manufacturing costs. For example, in the production of ethylbenzene, a raw material for the production of styrene, the off-gas from a fluidized catalytic cracking unit (FCC) can be successfully employed as a cost advantaged ethylene source. The FCC off-gas is a dilute stream containing typically less than 30 mole percent ethylene. Due to the large quantities of diluents in the FCC off-gas, such as, for example, hydrogen and methane, the alkylation section of the ethylbenzene unit requires that some of the equipment be oversized. Additionally, the hydrogen sulfide content of the FCC off-gas necessitates its removal in a gas pre-treatment section and subsequent compression before it can be routed to the alkylation reactor. The requirements of having oversized equipment and gas pretreatment followed by compression greatly increase the capital costs associated with an ethylbenzene unit utilizing FCC off-gas as its feedstock compared to a conventional ethylbenzene unit that utilizes high purity, polymer grade ethylene.
There is a need in the chemical industry to reduce feedstock costs by utilizing dilute olefin streams at olefins-based derivative units rather than polymer grade olefin feedstocks. To fulfill this need, the inventors provide this inventive process. This process reduces the amount of equipment traditionally required for the production of ethylene. An example of some of the equipment that has been eliminated is the ethylene refrigeration compressor, demethanizer, cold box system, and C
2
and C
3
splitters. Additionally, some equipment is smaller than with conventional crackers of comparable scale. The propylene refrigeration system is reduced in size over that of a conventional cracker. This invention also benefits the olefin-based derivative units that produce, for example, ethylbenzene, cumene, acrylic acid, and propylene oxide. One of the benefits is the pretreatment normally required for the olefins-based derivative units is not necessary in this inventive process because treatment has already been accomplished in the process to produce the dilute olefins stream. In others words, this inventive process to produce dilute olefin streams and route these stream to olefins-based derivative units has a reduced capital cost over a traditional FCC off-gas process since all pretreatment and compression is handled by the dilute olefins process.
SUMMARY OF THE INVENTION
An object of this invention is to provide a process to produce a dilute ethylene stream and a dilute propylene stream from a cracked gas stream.
Another object of this invention is to provide a process to produce the dilute ethylene stream and the dilute propylene stream from a cracked gas stream generated by the steam cracking of C
2
and higher hydrocarbons.
Another object of this invention is to provide a process to produce the dilute ethylene stream and dilute propylene stream wherein these streams are utilized to produce olefin-based derivatives.
Another object of this invention is to provide a process to produce a dilute ethylene stream wherein the dilute ethylene stream is used as a feedstock to produce ethylbenzene.
Another object of this invention is to provide a process to produce a dilute ethylene stream wherein the ethylbenzene unit utilizing the dilute ethylene stream does not contain pretreatment and compression zones.
Another object of this invention is to provide a process to produce a dilute propylene stream wherein the dilute propylene stream is used as a feedstock to produce cumene, acrylic acid, propylene oxide and other propylene derivatives.
Yet another object of this invention is to produce cumene, acrylic acid, and propylene oxide and other propylene derivatives without a pretreatment unit.
In accordance with one embodiment of this invention, a process for producing a dilute ethylene stream and a dilute propylene stream from a cracked gas stream is provided, the process comprising (or optionally, “consisting essentially of”) or “consisting of”) the following steps in the order named:
(1) separating the cracked gas stream in a deethanizer zone to produce a C
2
− stream and a C
3
+ stream;
(2) hydrogenating the C
2
− stream in a hydrogenation zone to remove a portion of the acetylene to produce the dilute ethylene stream;
(3) separating the C
3
+ stream in a depropanizer zone to produce a C
3
stream and a C
4
+ stream; and
(4) reacting the C
3
stream in a methylacetylene-propadiene hydrogenation (MAPD) reactor zone to convert a portion of methylacetylene and propadiene to propylene and propane to produce the dilute propylene stream.
In accordance with another embodiment of this invention, a process for producing the cracked gas stream is provided, the process comprising (or optionally, “consisting essentially of” or “consisting of”):
(1) heating a hydrocarbon feed in a cracking zone to form a raw cracked gas stream; wherein the raw cracked gas stream comprises hydrogen, methane, C
2
hydrocarbons, C
3
hydrocarbons and heavier constituents;
(2) quenching the raw cracked gas stream in a quenching zone to produce a quenched, cracked gas stream;
(3) compressing the quenched, cracked gas stream in a first compression zone to form a pressurized, cracked gas stream;
(4) deacidifying the pressurized, cracked gas stream in a deacidifying zone to remove a portion of the hydrogen sulfide to form a wet cracked gas stream; and
(5) drying the wet cracked gas stream in a drying zone to form a cracked gas stream.
In accordance with another embodiment of this invention, a process for producing a dilute ethylene stream and a dilute propylene stream is provided, the process comprising (or optionally, “consisting essentially of” or “consisting of”) the following steps in the order named:
(1) separating the cracked gas stream in a deethanizer zone to produce a C
2
− stream and a C
3
+ stream;
(2) compressing the C
2
− stream in a compression zone to form a pressurized C
2
− stream;
(3) hydrogenating the pressurized C
2
− stream in a hydrogenation zone to remove a portion of the acetylene to produce the dilute ethylene stream;
(4) separating the C
3
+ stream in a depropanizer zone to produce a C
3
stream and a C
4
+ stream; and
(5) reacting the C
3
stream in a MAPD reactor zone to convert a portion of methylacetylene and propadiene to propylene and propane to produce the dilute propylene stream.
In accordance with another embodiment of this invention, a process for producing a dilute ethylene stream and a dilute propylene stream is provided, the process comprising (or optionally, “consisting essentially of” or “consisting of”) the following steps in the order named:
(1) hydrogenating a portion of the acetylene in the cracked gas stream in a hydrogenation zone to produce a reduced acetylene cracked gas stream;
(2) separating the reduced acetylene cracked gas stream in a deethanizer zone to produce the dilute ethylene stream and a C
3
+ stream;
(3) separating the C
3
+ stream in the depropanizer zone to produce a C
Balinsky Anne M.
Porter Rodney L.
Weber Eric P.
Arnold Jr. James
Carroll Rodney B.
Chevron Phillips Chemical Company LP
Conley & Rose, P.C.
Griffin Walter D.
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