FRONT END CD HYDRO- RAW GAS HYDROGENATION ACHIEVED

摘要

Front End CDHydro applies catalytic distillation hydrogenation to the ethylene flowsheet to successfully accomplish raw, cracked gas hydrogenation. The Front End CDHydrosystem features a depentanizer tower with a hydrogenation catalyst zone in the rectifying zone of the tower to convert the C_2 to C_5 acetylenes and dienes to olefins.By combining the numerous fixed bed reactors into a single integrated step, investment costs are lower and plant reliability is improved. In addition, 30% to 35% of the pyrolysis hydrogen is removed by chemical reaction rather than by cryogenic separation. This reduces compressor power requirements by 10%. Furthermore, by using the butenes produced by the Front End CDHydro system as feed to a metathesis unit, the process chemistry downstream of the cracking heaters is further changed by producing up to one third of the propylene by energy-neutral metathesis rather than by energy-intensive thermal cracking.