(85e) Application of Dynamic Simulation in Improving Plant Efficiency

By

Tim Song, Maryn Pols, Prakash Ramdoss

CB&I
2 Riverway, Suite 1300
Houston, TX 77056
Tel: +1 713 375 8711

Prakash.ramdoss@cbi.com

In ethylene plants, considerate amount of CO2 and NOx emissions come from gas turbine exhaust gas and furnace flue gas. The hot gas turbine exhaust gas may be reused as oxygen source in the thermal cracking furnaces in place of cold ambient air, thus increasing the overall thermal efficiency, potentially reducing CO2 and NOx emissions from gas turbine combustion chamber and furnace combustion chamber combined. However the integration between gas turbine operation and the furnace operations raises operating flexibility and plant safety concerns, as the combined process needs to be able to operate in both ambient air mode and turbine exhaust gas mode and be able to transit from one mode to another in a safe and robust manner.

This work is part of a revamping project at an ethylene plant, where a new gas turbine is to be installed and integrated with the existing furnaces to improve plant efficiency. The hot gas turbine exhaust gas is routed to the furnaces, instead of the cold ambient air there by reducing fuel need for the furnaces. The work demonstrates that the dynamic process simulation models can be utilized to study the transition between modes of operation, revealing critical process insights. The transient analysis can also be used to determine key operating parameters such as damper opening and closing time parameters to ensure safe and smooth transitions and operations. Consequently, the analysis assures the plant operators with high confidence the robustness of integration between the gas turbine and furnace processes which increases the plant fuel efficiency thereby reducing emissions.