(123d) The Impact of Moving to Gas Feeds on the Maintenance & Reliability of the Ethylene Plant

The shale gas revolution in the United States has caused ethylene producers to push plants originally designed for heavier liquid feedstocks to crack increasingly lighter feedstocks to capitalize on the competitive advantage that they offer. The economic drivers and process modifications required to adapt to the changing market conditions are well documented, but the forecasted impacts to maintenance and reliability were educated assumptions. A few years into this shale gas revolution, those impacts are now being realized. What might operators and maintenance personnel expect to see as a result of the shift to lighter feeds? Certainly there is the potential for some process areas and pieces of equipment to see increased maintenance and reduced reliability because of the change in operating conditions or feedstock characteristics. Being alert to and prepared for these possibilities can minimize their negative impact. This paper will highlight areas of the ethylene plant affected by the shift from heavier liquid feeds to gas feeds and offer ideas of “things to watch for” based on the experience of several plant operators. Examples of monitoring points and case studies are provided to illustrate how changing feedstocks may affect a process and its equipment so that maintenance and reliability professionals may be better informed when facing the challenges imposed upon their plants by the shale gas revolution.