(31f) CO2 Reduction for Steam Cracking Furnaces By Full Hydrogen Firing

When firing fuel gas as generated within the cracker, the steam cracking furnaces emit about 90 to 95 percent of the plant’s total CO₂ emissions. One option to reduce CO₂ emissions from the cracking furnaces is to increase the hydrogen content in the fuel gas. By switching to firing 98 vol.% hydrogen fuel gas, CO₂ emissions from the furnace stack can be reduced by about 95 percent for liquid crackers (typically 10 vol.% H₂ in fuel gas) to 85 percent for ethane crackers (typically 85 vol.% H₂ in fuel gas).

Due to the difference in fuel gas characteristics when moving to firing high hydrogen content fuel gas the flue gas mass flowrate decreases, the firebox efficiency increases, the heat load into the furnace convection section decreases and the adiabatic flame temperature increases. When revamping existing furnaces, next to the adequacy of the firing system, there will be consequences on the furnace run length and superheated high pressure steam production and the revamp strategy needs to be adopted accordingly.

This paper discusses the design considerations when firing high hydrogen content fuel gas. The effect on the cracking furnace performance such as run length and SHP steam production, will be further explored and the adequacy and considerations on the convection section will be discussed. In addition, the impact on the burner design will be touched upon. Technip Energies is developing and testing burners suitable for hydrogen firing. The results from both the large capacity LSV^® bottom burner and side wall TSWB^® burner firing full hydrogen are presented.