FEEDING PYOIL AND STEAM AT CRACKER FURNACE CROSSOVER
Olefins are made by passing a cracker stream through a convection section of a cracker furnace; introducing steam and a stream comprising a recycle content pyrolysis oil into the cracker stream to form a combined stream, and the steam, r-pyoil stream, or both are introduced downstream of the inlet to the convection section, such as between the inlet to the coils and the radiant zone, or at the cross-over. Additionally, dilution steam can be added to a stream of r-pyrolysis to form a steam-diluted r-pyoil stream which is then introduced into a cracker furnace at any location, such as downstream of the inlets to the convection box or at a cross-over.
1 . A method for making olefins, said method comprising:
(a) passing a cracker stream through a convection section of a cracker furnace;
(b) introducing steam and a stream comprising a recycle content pyrolysis oil composition (r-pyoil) into said cracker stream to form a combined stream, wherein at least one of said steam and the r-pyoil stream are introduced downstream of the inlet to said convection section; and
(c) cracking said combined stream in said cracker furnace to form an olefin-containing effluent stream.
2 . The method of claim 1 , wherein r-pyoil is co-fed with steam at the location where steam is introduced into the convection zone.
3 . The method of claim 1 , wherein said r-pyoil is present in said combined stream in an amount of at least 5 weight percent, based on the total weight of the combined stream.
4 . The method of claim 1 , wherein said combined stream has a steam-to-hydrocarbon ratio of at least 0.2:1.
5 . The method of claim 1 , wherein the residence time of the cracker feed in the radiant section is not more than 2 seconds.
6 . The method of claim 1 , wherein said r-pyoil stream is introduced downstream of the inlet to said convection section.
7 . The method of claim 1 , wherein said r-pyoil stream is introduced at a cross-over zone between said convection section and said radiant section.
8 . The method of claim 1 , wherein said steam is introduced downstream of the inlet to said convection section.
9 . The method of claim 1 , wherein said steam is introduced at a cross-over zone between said convection section and said radiant section.
10 . The method of claim 1 , wherein said r-pyoil stream and said steam are combined and the combined stream is introduced at a cross-over zone between said convection section and a radiant section of said furnace.
11 . The method of claim 1 , wherein said cracker stream comprises predominantly propane or predominantly ethane.
12 . The method of claim 1 , wherein said cracker stream comprises at least 55 weight percent of non-recycled C 2 to C 4 components, based on the total weight of said cracker stream.
13 . A method for making olefins, said method comprising:
(a) adding dilution steam to a stream comprising a recycle content pyrolysis oil composition (r-pyoil) to form a steam-diluted r-pyoil stream;
(b) introducing said steam-diluted r-pyoil stream into a cracker stream in a cracker furnace; and
(c) cracking the combined stream in a radiant section of said furnace to form an olefin-containing effluent stream,
wherein said pyrolysis oil and dilution steam are introduced into said cracker stream upstream of the entrance to said radiant section.
14 . The method of claim 13 , wherein said adding of step (a) occurs upstream of an inlet to a convection section of said furnace.
15 . The method of claim 13 , wherein said adding of step (a) occurs in the cross-over zone of said furnace.
16 . The method of claim 13 , wherein said steam-diluted r-pyoil stream is atomized prior to said introducing.
17 . The method of claim 13 , wherein said introducing of step (b) occurs upstream of the inlet to a convection section of said furnace.
18 . A method for making olefins, said method comprising:
(a) passing a cracker stream through convection tubes in a cracker furnace;
(b) combining a stream comprising a recycle content pyrolysis oil composition (r-pyoil) with steam to form a steam-diluted r-pyoil stream;
(c) combining said steam-diluted r-pyoil stream with said cracker stream in a cross-over zone of said cracker furnace to provide a combined cracker stream; and
(d) cracking said combined cracker stream in a radiant section of said cracker furnace to form an olefin-containing effluent stream.
19 . The method of claim 18 , further comprising, prior to said combining of step (b), heating a feed stream comprising r-pyoil to form a heated r-pyoil stream and wherein step (b) comprises combining said heated r-pyoil stream with said steam to form said steam-diluted r-pyoil stream.
20 . The method of claim 19 , wherein said steam-diluted r-pyoil stream has a vapor fraction of at least 0.75.
21 . The method of claim 20 , wherein said r-pyoil is present in said combined cracker stream in an amount of at least 5 weight percent, based on the total weight of the combined stream.
22 . The method of claim 21 , wherein the residence time of the combined cracker stream in the radiant section is not more than 1.1 seconds.