Cleaning coke deposits from process equipment

A method for cleaning a coke deposit from an internal surface of a plurality of furnace tubes, the method comprising:

• aromatizing hydrocarbons in an aromatization reactor system to produce an aromatization product, wherein the aromatization reactor system comprises a furnace having a plurality of furnace tubes disposed therein, wherein the internal surface of each of the plurality of furnace tubes has a metal protective layer comprising stannide disposed thereon, and wherein coke deposits are formed on the metal protective layer of the internal surface of one or more of the plurality of furnace tubes;
• halting the aromatizing;
• propelling a flexible pig through at least one of the plurality of furnace tubes, wherein the flexible pig is propelled by a fluid comprising an aqueous solution;
• removing at least a portion of the coke deposits from the internal surface using the flexible pig, without damaging the metal protective layer of the internal surface;
• and
• resuming aromatization of hydrocarbons in the aromatization reactor system,
• wherein the flexible pig comprises:
• at least two foam spacers,
• at least two bristle sections, and
• a flexible cable extending along a longitudinal axis of the flexible pig through the at least two foam spacers and through the at least two bristle sections,
• wherein each of the at least two bristle sections comprises a plurality of bristles, and wherein the at least two bristle sections are separated by one of the at least two foam spacers.