Process Economics Program Report 248A
Advances in Naphtha Steam Cracking
Published: December 2005
This PEP report is designed to help clients better understand the technology changes that are being incorporated in modern, state of the art naphtha steam crackers, and also assist operators of existing steam crackers in providing incremental upgrades to improve performance and profitability.
For grass roots naphtha steam crackers, we provide an engineering process design and corresponding production economics for a 1.2 MM tpy naphtha steam cracking unit that incorporates state of the art technology. These new developments include: mercury and arsenic pre-treatment of feedstock, DMSO addition to naphtha very low in sulfur content, furnace operation for both maximum ethylene and maximum propylene business objectives, front end de-propanizer fractionation trains, dual depropanizer tower optimization, front end hydrogenation of di-olefins with dilute hydrogen, mixed refrigerant cryogenics, and low pressure (20 bar) process compression.
We consider 4 material balances cases:
- Steam cracking light naphtha for max ethylene yield
- Steam cracking light naphtha for max propylene yield
- Steam cracking full range naphtha for max ethylene yield
- Steam cracking full range naphtha for max propylene yield
We compare the licensed process offerings currently made by KBR, Lummus, S&W, Technip and Linde.
We also explore typical debottlenecking strategies to incrementally increase production capacity. These include cracked gas and refrigeration compressor upgrades, major driver modifications, quench oil and water wash tower modifications, and fractionation train tray and packing modifications.
To extend major turnaround frequency to 5 year intervals, we identify the major equipment that needs to be upgraded and/or made redundant. These include heavy service reboilers, compressor inter-stage coolers, TLE operation, upgraded furnace tube metallurgy, and quench cooler upgrades.
Given the emphasis currently applied to on-line, real time economic optimizers, we review the vendor offerings, and describe the sources of economic credits that justify this type of SCADA investment.