Mineral oils: processes and products – Chemical conversion of hydrocarbons – Cracking
Patent
1996-07-10
1998-10-06
Griffin, Walter D.
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Cracking
208132, 208 78, 208 80, 208 72, 208 75, 585648, 585652, 422197, 422204, 196110, 196116, C10G 936, F28D 2100
Patent
active
058172262
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process for steam cracking of hydrocarbons in a cracking furnace with a convection zone and a radiation zone, in which the process comprises a first stage of precracking a feedstock of light hydrocarbons and a second stage of final co-cracking of the mixture of this precracked feedstock of light hydrocarbons and a feedstock of heavy hydrocarbons. The invention further relates to a device for steam cracking of hydrocarbons; said device comprises a cracking furnace with a convection zone and a radiation zone, at least one preheating tube for a feedstock of light hydrocarbons in the convection zone for preheating this feedstock, whereby this tube is connected downstream to at least one cracking tube for the feedstock of light hydrocarbons to precrack them in the radiation zone, and at least one preheating tube for a feedstock of heavy hydrocarbons in the convection zone for preheating this feedstock.
The process of steam cracking is well known and represents one of the most important processes in petrochemistry.
In this case, a feedstock that consists of hydrocarbons and steam is evaporated and preheated in the convection zone of a steam cracking furnace. In the radiation zone of the furnace, an enormous increase in the temperature of this feedstock beyond the initial cracking temperature is carried out, and it results in cracking at a high temperature before the cracked gases are cooled and the cracking products are fractionated.
Within the scope of this invention, "feedstock" is defined as a mixture of hydrocarbons and steam. This applies to both light and heavy feedstocks. The mixture, either before this mixture is cracked or else even while it is being cracked, is referred to as feedstock. The hydrocarbon-containing fraction of the feedstock (the fraction without steam), i.e., the hydrocarbons consisting of the feedstock or the mixture of hydrocarbons and steam before the feedstock is cracked, is to be distinguished from the feedstock.
The preheating temperatures are normally in the range between 450.degree. and 650.degree. C., and the cracking temperatures (discharge temperature of the furnace) are usually in the range between 780.degree. and 920.degree. C.
The high values in the temperature intervals relate in general to the lightest feedstocks, and the low values relate to the relatively heavy feedstocks. For the feedstocks, the initiation of cracking in the convection zone is avoided if possible.
In connection with the invention, "initial cracking temperature" is defined as the temperature above which cracking of the hydrocarbons sets in or occurs to a significant extent and above which cracking always occurs more and more quickly. The initial cracking temperatures basically depend on the composition of the feedstock. The values of the initial cracking temperature are known to one skilled in the art.
In connection with the invention, the following different values apply, for example, to the indicated compositions of the feedstock:
______________________________________ Composition of the
hydrocarbon-containing fraction
of the feedstock Initial cracking temperature
______________________________________
C.sub.2 --C.sub.3 --C.sub.4
720.degree. C.
Naphtha 710.degree. C.
Kerosine, atmospheric gas oil
690.degree. C.
Vacuum gas oil 680.degree. C.
______________________________________
These temperatures are conventional values. Since these temperatures generally do not represent any strict temperature values, temperatures that deviate by 10 to 20 K from the above-mentioned values could also be indicated. The above-indicated values correspond to very low cracking rates. In comparison with this, the temperatures normally are at least 100 K higher than the indicated temperature values at faster cracking rates. Such temperatures usually prevail at the outlet of the cracking furnace.
In a manner well known to one skilled in the art, an attempt is made to achieve a large rise in the temperature of the feedstock to the initial cracking
REFERENCES:
patent: 3579601 (1971-05-01), Kivlen
patent: 4268375 (1981-05-01), Johnson et al.
patent: 4492624 (1985-01-01), Johnson et al.
patent: 4552644 (1985-11-01), Johnson et al.
patent: 4615795 (1986-10-01), Woebcke et al.
patent: 4732740 (1988-03-01), Woebcke et al.
patent: 4906442 (1990-03-01), Johnson et al.
patent: 5190634 (1993-03-01), Fernandez-Baujin et al.
Griffin Walter D.
Linde Aktiengesellschaft
Procedes Petroliers Petrochimiques et SARL
LandOfFree
Process and device for steam-cracking a light and a heavy hydroc 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 and device for steam-cracking a light and a heavy hydroc, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and device for steam-cracking a light and a heavy hydroc will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-73961