Method and apparatus for cooling pyrolysis effluent

A process for creating a wetted wall in a cooling conduit for use in quenching gaseous effluent from a hydrocarbon pyrolysis furnace, the process comprising:

• (a) introducing said gaseous effluent into a cooling conduit, said cooling conduit comprising;
• (i) an inner wall for contacting said effluent, said inner wall defining a bore extending a length of said cooling conduit, said inner wall including a perimeter opening along said bore;
• (ii) an outer wall external to said inner wall and substantially coaxial to said inner wall;
• (iii) a substantially annular cavity external to said inner wall and including at least a portion of said outer wall, said annular cavity fluidly and remotely connected to said perimeter opening, said annular cavity externally surrounding a perimeter of said inner wall;
• and
• (iv) a peripheral channel extending around a perimeter of said inner wall, said peripheral channel fluidly connecting said annular cavity and said perimeter opening, along said perimeter of said inner wall;
• (b) introducing a liquid quench fluid through a liquid quench fluid introduction port tangentially into said annular cavity, substantially along a first portion of said outer wall, whereby said introduced liquid quench fluid fills said cavity;
• (c) passing said introduced liquid quench fluid from said annular cavity through said channel to said perimeter opening along a channel flow path;
• and
• (d) passing said liquid quench fluid from said perimeter opening onto said inner wall for distribution of said quench fluid along at least a portion of said length of said inner wall as a quench fluid film, while concurrently passing said gaseous effluent along said bore of said cooling conduit to produce a quenched gaseous effluent stream.