Decoking apparatus

An apparatus for decoking a reaction vessel adapted for the thermal cracking of heavy petroleum oil comprising:

• cylinder assembly means adapted for mounting in a top opening of a reaction vessel, said cylinder assembly means including cylinder means and piston means mounted in said cylinder means for reciprocating movement, said cylinder means and piston means defining a fluid chamber divided into multiple subchambers including a main scrubbing liquid subchamber and sealing fluid subchambers;
• a main injection pipe in communication with said main scrubbing liquid subchamber and being connected to said piston means for reciprocating motion therewith;
• said main injection pipe having a plurality of perforations along the lower length of said main injection pipe for injecting scrubbing liquid from said main scrubbing liquid subchamber against inner wall surfaces of a reaction vessel;
• means for injecting a fluid into said sealing subchambers of said multiple subchambers to drive said piston means with reciprocating motion;
• and
• means for rotating said main injection pipe.