A method for producing an olefin and a monocyclic aromatic hydrocarbon of the present invention includes a dicyclopentadiene removal treatment step of removing dicyclopentadienes having a dicyclopentadiene skeleton from a feedstock oil which is a thermally-cracked heavy oil obtained from an apparatus for producing ethylene and which has a 90 volume % distillate temperature, as a distillation characteristic, of 390° C. or lower; and a cracking and reforming reaction step of obtaining a product containing an olefin and a monocyclic aromatic hydrocarbon by bringing the feedstock oil having a content of dicyclopentadienes adjusted to 10% by weight or less by treating a part or all of the feedstock oil through the dicyclopentadiene removal step into contact with a catalyst and reacting the feedstock oil.

A process is provided for utilizing polypropylene-containing waste plastic. The process provides pyrolyzing a plastic feed in a pyrolysis reactor to obtain a pyrolysis effluent stream. The process further provides passing the pyrolysis effluent stream to a distillation column to obtain a C.sub.9 hydrocarbons rich stream which is also dimethylheptenes rich and then passing the C.sub.9 hydrocarbons rich stream to a reforming unit to provide a reformate stream. The process further provides passing the reformate stream to a transalkylation unit to provide a mixed-xylenes stream.

A feed stream of cyclic paraffins may be separated to obtain an overhead of methylcyclopentane or cyclohexane and a bottoms stream cyclohexane or methylcyclohexane. The overhead stream may be subjected to separation of normal paraffins from non-normal paraffins with the former being isomerized or the entire overhead stream may be isomerized. In a further embodiment, the bottoms stream may be subjected to steam cracking. In an additional embodiment, the feed stream of cyclic paraffins may be formerly subjected to aromatic saturation.

A feed stream of cyclic paraffins may be separated to obtain an overhead of methylcyclopentane or cyclohexane and a bottoms stream cyclohexane or methylcyclohexane. The overhead stream may be subjected to separation of normal paraffins from non-normal paraffins with the former being isomerized or the entire overhead stream may be isomerized. In a further embodiment, the bottoms stream may be subjected to steam cracking. In an additional embodiment, the feed stream of cyclic paraffins may be formerly subjected to aromatic saturation.

Hydrocarbon-containing fluids are provided for use during solvent-assisted hydroprocessing of pyrolysis tar, such as steam cracker tar. The hydrocarbon-containing fluids can be used at any convenient time, such as during start-up of a pyrolysis process when recycled liquid pyrolysis product is not available; when the amount of liquid pyrolysis product available for recycle is not sufficient to maintain desired hydroprocessing conditions; and/or when the changes to the quality of the liquid pyrolysis product reduce the suitability of the recycle stream for use as a utility fluid.

Hydrocarbon-containing fluids are provided for use during solvent-assisted hydroprocessing of pyrolysis tar, such as steam cracker tar. The hydrocarbon-containing fluids can be used at any convenient time, such as during start-up of a pyrolysis process when recycled liquid pyrolysis product is not available; when the amount of liquid pyrolysis product available for recycle is not sufficient to maintain desired hydroprocessing conditions; and/or when the changes to the quality of the liquid pyrolysis product reduce the suitability of the recycle stream for use as a utility fluid.

A method and apparatus for processing a hydrocarbon stream are described. The method includes heating a feed stream in a convective bank. The heated feed stream is reacted in a first reaction zone to form a first effluent, which is heated in a first radiant cell. The first radiant cell combusts fuel to heat the first effluent and forms a first exhaust gas. The first exhaust gas is contacted with the convective bank to heat the feed stream. The outlet temperature the heated feed stream from the convective bank is controlled by introducing an additional gas stream into the convective bank. There can be additional reaction zones and radiant heaters.

A method and apparatus for processing a hydrocarbon stream are described. The method includes heating a feed stream in a convective bank. The heated feed stream is reacted in a first reaction zone to form a first effluent, which is heated in a first radiant cell. The first radiant cell combusts fuel to heat the first effluent and forms a first exhaust gas. The first exhaust gas is contacted with the convective bank to heat the feed stream. The outlet temperature the heated feed stream from the convective bank is controlled by introducing an additional gas stream into the convective bank. There can be additional reaction zones and radiant heaters.

The present invention concerns a process for the production of light olefins and BTX using a catalytic cracking unit, NCC, processing a naphtha type feed, and an aromatics complex. It can be used to exploit the synergies between these two units. The thermal balance of the NCC, which is intrinsically deficient in coke, is resolved by the optimal use of heat from the reforming furnaces in order to preheat the feed for the NCC, and by introducing at least a portion of the raffinate obtained from the aromatics complex as a mixture with the naphtha.

The present invention concerns a process for the production of light olefins and BTX using a catalytic cracking unit, NCC, processing a naphtha type feed, and an aromatics complex. It can be used to exploit the synergies between these two units. The thermal balance of the NCC, which is intrinsically deficient in coke, is resolved by the optimal use of heat from the reforming furnaces in order to preheat the feed for the NCC, and by introducing at least a portion of the raffinate obtained from the aromatics complex as a mixture with the naphtha.