Remaining Life Assessments of Refinery Cokr Furnace Tubes Using Omega Simulations

Remaining Life Assessments of Refinery Coker Furnace Tubes Using Omega Simulations

Gerald W. Wilks, Lemont Refinery, CITGO Petroleum Inc.

Abstract

Process simulations are used frequently in refineries to determine the optimum operating parameters for a wide range of processes. The development of Omega technology by the oil industry in the 1990's led a new type of simulation that made it possible to assess both the effects of corrosion and past high temperature service on the life of refinery equipment.  This technology also made it possible to predict future equipment performance based on proposed process changes.  Furnace tubes are a type of high temperature equipment that is well suited to Omega simulation analyses.  However, in Coker furnaces the accumulation of coke in the tubes leads to gradual changes in temperature and pressure that make accurate simulations of the furnace difficult.  Furnace tubes typically fail due to the combination of corrosion and creep processes, and with changes occurring in temperature and pressure, the rate of degradation from corrosion and creep are also continuously changing.  This paper describes how corrosion data and process data can be used in Omega simulations to obtain accurate assessments of furnace tube remaining life.  Included in this paper is an explanation of how anticipated changes in process conditions can be evaluated with Omega simulations to determine the impact of those process changes on the remaining life of coker furnace tubes.