Process for cracking and transhydrogenation of hydrocarbon feeds

Details Process for cracking and transhydrogenation of hydrocarbon feeds Process for cracking and transhydrogenation of hydrocarbon feeds

1995-06-23

1998-11-17

Myers, Helane

Mineral oils: processes and products

Chemical conversion of hydrocarbons

Plural serial stages of chemical conversion

585257, 585616, 585627, 585661, 585660, C10G 6902

Patent

active

058371273

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to hydrocarbons and in particular to the production of olefins, or derivatives thereof, from a hydrocarbon feedstock stream.
It is well known that a hydrocarbon feedstock stream, such as naphtha, LPG, or gas-oil, may be cracked in a furnace to give a mixture of hydrocarbons of varying molecular weight. Often the aim of such a cracking operation is to produce olefins containing up to about 5 carbon atoms, although inevitably non-olefinic compounds and also some higher molecular weight products will usually be formed. The cracking process gives a mixture of hydrogen and saturated, unsaturated, and aromatic hydrocarbons. The precise composition of the cracker product will of course depend on the nature of the feedstock and the cracking furnace operating conditions; a typical percentage composition (by weight) of the product of cracking naphtha is as follows:


______________________________________ hydrogen 1 benzene 6 methane 16 toluene 3 ethene 32 C.sub.8 aromatics 2 propene 16 fuel oil 4 C.sub.4 hydrocarbons 8 others 12 ______________________________________
The cracker product is usually separated, e.g., by distillation, into a number of streams, such as hydrogen, methane, C.sub.2, C.sub.3, C.sub.4, and higher hydrocarbon streams. Usually it is desired to produce olefin streams and to this end the C.sub.2, C.sub.3 and/or the C.sub.4 streams are separated into the appropriate olefinic and paraffinic streams. Often the paraffinic streams are recycled to the cracking furnace. The cracking operation is normally effected at temperatures in the range 750.degree.-900.degree. C., particularly 800.degree.-850.degree. C., using steam as a diluent, usually in proportions of 0.25-0.75, particularly 0.4-0.6, tonnes of steam per tonne of hydrocarbon feedstock. The cracking is usually non-catalytic and is effected at relatively low pressure, generally below about 10 bar abs. and often below about 2 bar abs. The cracker product, possibly after an initial separation of at least some of the hydrocarbons containing 5, 6, or more carbon atoms, is then compressed, typically to above about 20 bar abs., before effecting the separation into the desired product streams by means of a suitable cold train and separation columns.
The olefin components are generally the highest value products and so it is often desirable to increase the yield of such components. Also among the cracker products are components, such as propadiene, propyne, and butadiene, that are more highly unsaturated than mono-olefins. In PCT application GB92/00699 (now published as WO 92/19575)--the disclosure of which is incorporated herein by reference--a process termed transhydrogenation is described wherein such more highly unsaturated hydrocarbons are catalytically reacted with paraffins, effecting dehydrogenation of the paraffins and hydrogenation of the more highly unsaturated components. The paraffins thus act as hydrogen-donors while the more highly unsaturated hydrocarbons act as hydrogen-acceptors.
Such a transhydrogenation process, which like cracking is desirably operated at a relatively low pressure for operating reasons, enables the yield of olefins to be increased. The transhydrogenation is desirably effected in the presence of added hydrogen. In addition to the desired olefins, the transhydrogenation product will contain other components, eg hydrogen, unreacted paraffins, unreacted hydrogen-acceptor compounds, together with products resulting from cracking and/or hydrogenation reactions taking place as well as transhydrogenation. Consequently recovery of the desired olefin components from the transhydrogenation product is also necessary. In the present invention this is effected by means of the product separation facilities employed for the separation of the cracker product into component streams.


SUMMARY OF THE INVENTION

Accordingly the present invention provides a process wherein a hydrocarbon feedstock is subjected to cracking at a first pressure to produce a cracker product,

REFERENCES:
patent: 2322025 (1943-06-01), Ipalieff et al.
patent: 3211635 (1965-10-01), Phillips Petroleum
patent: 3267170 (1966-08-01), Aldridge et al.
patent: 3267171 (1966-08-01), Esso
patent: 3321545 (1967-05-01), Rigney et al.
patent: 3855327 (1974-12-01), Billings
patent: 3950447 (1976-04-01), Gryaznov
patent: 4062803 (1977-12-01), Bianchi et al.
patent: 4546204 (1985-10-01), Parris
patent: 4684755 (1987-08-01), Parris et al.
patent: 4975097 (1990-12-01), Harandi et al.
patent: 5047070 (1991-09-01), Harandi et al.
patent: 5160424 (1992-11-01), Le et al.
patent: 5585530 (1996-12-01), Gough
patent: 5639926 (1997-06-01), Turner et al.

Affiliated with

Also associated with

Rating

Process for cracking and transhydrogenation of hydrocarbon feeds does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for cracking and transhydrogenation of hydrocarbon feeds, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for cracking and transhydrogenation of hydrocarbon feeds will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-880749