In some examples, a flow of hydrocarbon feed can be introduced into a pyrolysis furnace that includes a first radiant coil and a second radiant coil. At least a portion of the hydrocarbon feed can be pyrolysed in the first radiant coil and the second radiant coil to produce a pyrolysis effluent and to deposit coke on an inner surface of each of the first radiant coil and the second radiant coil. The flow of the hydrocarbon feed can be decreased into the first radiant coil and the flow of the hydrocarbon feed into the second radiant coil can be maintained, wherein the flow of the hydrocarbon feed into the pyrolysis furnace can be decreased by about 10 vol. % to about 90 vol. %. A decoking feed including steam at a pressure of ≥690 kPag can be introduced into the first radiant coil of the pyrolysis furnace to remove at least a portion of the coke deposited on the inner surface of the first radiant coil.

Methods that reduce fouling of equipment in a quench water recycling loop of a steam cracker quench system by separating tar from water in the quench water recycling loop. The methods may include settling a bottom stream comprising pyrolysis gasoline, from a quench tower, in at least two quench water settlers in parallel, each of the quench water settlers producing a settler hydrocarbon stream and a settler bottom quench water stream. The methods may also include mixing a bottom stream comprising pyrolysis gasoline, from a quench tower, with quench tower effluent water to form a combined stream. The method may further include settling the combined stream in at least two quench water settlers in parallel to produce settler hydrocarbon streams, settler bottom quench water streams, and settler process water streams.

Methods that reduce fouling of equipment in a quench water recycling loop of a steam cracker quench system by separating tar from water in the quench water recycling loop. The methods may include settling a bottom stream comprising pyrolysis gasoline, from a quench tower, in at least two quench water settlers in parallel, each of the quench water settlers producing a settler hydrocarbon stream and a settler bottom quench water stream. The methods may also include mixing a bottom stream comprising pyrolysis gasoline, from a quench tower, with quench tower effluent water to form a combined stream. The method may further include settling the combined stream in at least two quench water settlers in parallel to produce settler hydrocarbon streams, settler bottom quench water streams, and settler process water streams.

Disclosed is a valve mechanical linkage system. A valve comprises a main valve and a secondary valve; the system comprises a first transmission mechanism and a second transmission mechanism; the first transmission mechanism is connected with the main valve and used for converting the up-and-down reciprocating motion of the main valve into a rotational reciprocating motion; the first transmission mechanism and the second transmission mechanism are connected by means of a coupling (4), and the rotational force of the rotational reciprocating motion is transferred to the second transmission mechanism by means of the coupling (4); the second transmission mechanism is connected with the secondary valve, and achieves on-off control on the secondary valve by converting the rotational reciprocating motion into the up-and-down reciprocating motion.

An anti-coking nanomaterial based on a stainless steel surface. In percentage by weight, the nanomaterial comprises: 0 to 3% of carbon, 23% to 38% of oxygen, 38% to 53% of chromium, 10% to 35% of ferrum, 0 to 2% of molybdenum, 0 to 4% of nickel, 3.5 to 5% of silicon, 0 to 1% of calcium, and the balance of impurity elements. Also disclosed are a preparation method for the anti-coking nanomaterial, the anti-coking nanomaterial that is based on a stainless steel surface and that is prepared by using the preparation method, and a stainless steel substrate comprising the anti-coking nanocrystalline material.

Disclosed are compositions and methods for preventing or reducing polymer formation and polymer deposition in equipment used in petrochemical processes. An antifoulant composition includes a combination of one or more antioxidants; one or more antipolymerants; one or more dispersants; and one or more solvents. A method of preventing or reducing fouling of process equipment used in an industrial process is also described. The method includes introducing into the process equipment an antifoulant composition, the antifoulant composition comprising a combination of one or more antioxidants; one or more antipolymerants; one or more dispersants; and one or more solvents.

Disclosed are compositions and methods for preventing or reducing polymer formation and polymer deposition in equipment used in petrochemical processes. An antifoulant composition includes a combination of one or more antioxidants; one or more antipolymerants; one or more dispersants; and one or more solvents. A method of preventing or reducing fouling of process equipment used in an industrial process is also described. The method includes introducing into the process equipment an antifoulant composition, the antifoulant composition comprising a combination of one or more antioxidants; one or more antipolymerants; one or more dispersants; and one or more solvents.

Disclosed herein are methods for reducing fouling caused by process water present within a water recycling loop of a pyrolysis plant. Fouling is caused by phase separation and accumulation of materials from the process water on equipment surfaces. The method includes applying a total of about 5 ppm to 500 ppm total of a first polymerization inhibitor and second polymerization inhibitor to the process water to form a treated process water, wherein the first polymerization inhibitor has a pygas-water partition coefficient of about 0.0001 to 9 and the second polymerization inhibitor has a pygas-water partition coefficient of about 1000 to 50,000.

Disclosed herein are methods for reducing fouling caused by process water present within a water recycling loop of a pyrolysis plant. Fouling is caused by phase separation and accumulation of materials from the process water on equipment surfaces. The method includes applying a total of about 5 ppm to 500 ppm total of a first polymerization inhibitor and second polymerization inhibitor to the process water to form a treated process water, wherein the first polymerization inhibitor has a pygas-water partition coefficient of about 0.0001 to 9 and the second polymerization inhibitor has a pygas-water partition coefficient of about 1000 to 50,000.

The invention relates to a pipe for thermal cracking of hydrocarbons in the presence of steam, in which the feed mixture is guided through externally heated pipes, wherein the pipe extends along a longitudinal axis and has a number N.sub.T of grooves that have been introduced into the inner surface of the pipe and extend in a helix around the longitudinal axis along the inner surface, the inner surface into which the grooves have been introduced, in a cross section at right angles to the longitudinal axis, has a diameter Di and a radius r.sub.1=Di/2, the grooves in the cross section at right angles to the longitudinal axis, in their groove base, each have the form of a circular arc and the circular arc has a radius r.sub.2, and
the grooves each have a groove depth TT which, in the cross section at right angles to the longitudinal axis, corresponds in each case to the smallest distance between the circle having the diameter Di on which the inner surface lies and the center of which lies on the longitudinal axis, and the furthest removed point of the groove base of the grooves from the longitudinal axis.