Patent ID: 9644149
Date: 2017-05-09
CPC Classifications: B08B,C10B,C10G

Claim:
1. A method for removing coke deposits in radiant tubes of an olefin cracking furnace and removing accumulated spalled coke from one or more outlet elbows of the olefin cracking furnace without performing a cold shutdown of the furnace, the method comprising the steps of: (a) introducing decoking air and low pressure steam into a plurality of radiant tubes of the olefin cracking furnace, and maintaining flow through the plurality of radiant tubes for a first period of time; (b) identifying a first outlet elbow with restricted flow therethrough due to accumulated spalled coke resulting from step (a); and (c) lining-up a supply of medium pressure steam by opening a block valve then opening a control valve, and introducing the medium pressure steam through a first subset of the plurality of radiant tubes, the first subset of tubes comprising (i) a plurality of tubes upstream of one or more outlet elbows through which flow is not restricted and (ii) a second subset of tubes upstream of the first outlet elbow identified in step (b) through which flow is restricted, and maintaining flow therethrough for a second period of time, thereby removing accumulated spalled coke from the first outlet elbow.