A method for preparing ethylene including: feeding a thermally cracked compressed stream to a first distillation apparatus selectively operating as a first deethanizer or a depropanizer; and feeding an overhead discharge stream of the first distillation apparatus to a second distillation apparatus. When the first distillation apparatus is operated as the first deethanizer, a bottom discharge stream of the second distillation apparatus is fed to a C2 separator. When the first distillation apparatus is operated as the depropanizer, the bottom discharge stream of the second distillation apparatus is passed through a third distillation apparatus and fed to the C2 separator.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

Antifoulant compositions and methods are used for inhibiting fouling on structural parts of a system exposed to a fluid hydrocarbon or petrochemical stream. Polyamine antifoulants are added to such systems. The polyamine antifoulants may be conjointly used with dispersants and/or fatty acids. The fatty acids have been found to reduce thermal degradation of the polyamine antifoulants.

In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitriding there is a reduced tendency to carburization of the metal substrate improving the reactor life.

In chemical processes for cracking hydrocarbons, reactors are subject to coking. This results in carburization of the metal substrate for the reactor leading to a reduced reactor life. If the reactor is subject to a decoke process, followed by a steam scour and nitriding there is a reduced tendency to carburization of the metal substrate improving the reactor life.

A method for preparing ethylene including: feeding a thermally cracked compressed stream to a first distillation apparatus selectively operating as a first deethanizer or a depropanizer; and feeding an overhead discharge stream of the first distillation apparatus to a second distillation apparatus. When the first distillation apparatus is operated as the first deethanizer, a bottom discharge stream of the second distillation apparatus is fed to a C2 separator. When the first distillation apparatus is operated as the depropanizer, the bottom discharge stream of the second distillation apparatus is passed through a third distillation apparatus and fed to the C2 separator.

A method for cleaning a metal surface of a metal component of an industrial plant is disclosed comprising measuring the electrical resistance R.sub.A1 of a metal component over a cleaned area of the metal surface with a resistance meter, comparing the electrical resistance R.sub.A1 measured with a pre-determined electrical resistance value R.sub.DET, assessing whether R.sub.A1 is greater, smaller or equal to R.sub.DET, and repeating cleaning if the electrical resistance R.sub.A1 measured is greater than R.sub.DET, or terminating cleaning of the surface area of the metal component if R.sub.A1 is smaller than or identical to R.sub.DET.

The present invention concerns a method of weakening and removal of coke or carbonaceous material which deposits as a result of thermal cracking of hydrocarbons on the inner walls of coils, piping, tubing, and in general, hydrocarbon processing equipment.