TECHNICAL FIELD

Embodiments of the present disclosure generally relate to chemical processing and, more specifically, to process and systems utilizing fluid catalytic cracking to form olefins.

BACKGROUND

Ethylene, propene, butene, butadiene, and aromatics compounds such as benzene, toluene and xylenes are basic intermediates for a large proportion of the petrochemical industry. They are usually obtained through the thermal cracking (or steam pyrolysis) of petroleum gases and distillates such as naphtha, kerosene or even gas oil. These compounds are also produced through refinery fluidized catalytic cracking (FCC) process where classical heavy feedstocks such as gas oils or residues are converted. Typical FCC feedstocks range from hydrocracked bottoms to heavy feed fractions such as vacuum gas oil and atmospheric residue; however, these feedstocks are limited. The second most important source for propene production is currently refinery propene from FCC units. With the ever growing demand, FCC unit owners look increasingly to the petrochemicals market to boost their revenues by taking advantage of economic opportunities that arise in the propene market.

The worldwide increasing demand for light olefins remains a major challenge for many integrated refineries. In particular, the production of some valuable light olefins such as ethylene, propene, and butene has attracted increased attention as pure olefin streams are considered the building blocks for polymer synthesis. The production of light olefins depends on several process variables like the feed type, operating conditions, and the type of catalyst.

SUMMARY

Despite the options available for producing a greater yield of propene and other light olefins, intense research activity in this field is still being conducted. These options include the use of high severity fluid catalytic cracking (“HSFCC”) systems, developing more selective catalysts for the process, and enhancing the configuration of the process in favor of more advantageous reaction conditions and yields. The HSFCC process, in some embodiments, may be capable of producing yields of propene up to four times greater than the traditional fluid catalytic cracking unit and greater conversion levels for a range of petroleum steams. Embodiments of the present disclosure are directed to improved HSFCC systems and processes for producing one or more petrochemical products from a hydrocarbon material, such as a crude oil.

In one or more embodiments presently described, two FCC reactors, which may be downers, may be utilized for cracking of a hydrocarbon stream such as crude oil. According to embodiments presently disclosed, it has been recognized that separating the feed stream into at least three fractions may enhance product yields. In one or more embodiments, a lesser and medium boiling point fraction of the feed stream may be introduced into a first reactor, and a heavy boiling point fraction may be introduced into a second reactor. The lesser boiling point fraction may enter the reactor upstream of the medium boiling point fraction. In some embodiments, this arrangement may result in the lesser boiling point fraction being exposed to greater temperatures, greater catalyst to oil ratios, and/or greater residence time than the medium boiling point fraction. The varying reaction conditions of the lesser boiling point fraction and medium boiling point fraction may improve light olefin yields. Light olefin yields may be increased as compared to embodiments where only two fractions of feed oil are processed.

According to one or more embodiments, petrochemical products may be produced from a hydrocarbon material by a process that may comprise separating the hydrocarbon material into at least a lesser boiling point fraction, a medium boiling point fraction, and a greater boiling point fraction. The process may further comprise cracking at least a portion of the greater boiling point fraction in the presence of a first catalyst in a first reactor unit at a reaction temperature of from 500° C. to 700° C. to produce a first cracking reaction product. The process may further comprise cracking at least a portion of the lesser boiling point fraction and the medium boiling point fraction in a second reactor unit in the presence of a second catalyst at a reaction temperature of from 500° C. to 700° C. to produce a second cracking reaction product, wherein the lesser boiling point fraction enters the second reactor unit upstream of wherein the medium boiling point fraction enters the second reactor. The process may further comprise separating the petrochemical products from one or both of the first cracking reaction product or the second cracking reaction product.

According to one or more additional embodiments, a petrochemical product stream may be produced from a hydrocarbon feed stream by a process that may comprise introducing the hydrocarbon feed stream to a feed separator, and separating the hydrocarbon feed stream into at least a lesser boiling point fraction stream, a medium boiling point fraction stream, and a greater boiling point fraction stream in the feed separator. The process may further comprise passing the greater boiling point fraction stream to a first fluidized catalytic cracking unit, and passing the lesser boiling point fraction stream and the medium boiling point fraction stream to a second fluidized catalytic cracking unit, wherein the lesser boiling point fraction stream is passed into the second fluidized catalytic cracking unit upstream of the medium boiling point fraction stream. The process may further comprise cracking at least a portion of the greater boiling point fraction stream in the first fluidized catalytic cracking unit in the presence of a first catalyst at a reaction temperature of from 500° C. to 700° C. to produce a first cracking reaction product stream. The process may further comprise cracking at least a portion of the lesser boiling point fraction stream and the medium boiling point fraction stream in the second fluidized catalytic cracking unit in the presence of a second catalyst and at a reaction temperature of from 500° C. to 700° C. to produce a second cracking reaction product stream. The process may further comprise separating the petrochemical product stream from one or both of the first cracking reaction product stream or the second cracking reaction product stream.

Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description which follows, the claims, as well as the appended drawings.

