Reduction of energy cost and CO2 emission for the furnace using energy recovered from waste tail-gas

In this research, the waste tail gas emitted from petrochemical processes, e.g. catalytic reforming unit, catalytic cracking unit and residue desulfurization unit, was recovered and reused as a replacement of natural gas (NG). On-site experimental results show that both the flame length and orange-yellowish brightness decrease with more proportion of waste gas fuel added to the natural gas, and that the adiabatic temperature of the mixed fuel is greater than 1800 °C. A complete replacement of natural gas by the recovered waste gas fuel will save 5.8 × 10⁶ m³ of natural gas consumption, and 3.5 × 10⁴ tons of CO₂ emission annually. In addition, the reduction of residual O₂ concentration in flue gases from 4% to 3% will save 1.1 × 10⁶ m³ of natural gas consumption, reduce 43.0% of NO_x emission, and 1.3 × 10³ tons of CO₂ emission annually. Thus, from the viewpoint of the overall economics and sustainable energy policy, recovering the waste tail gas energy as an independent fuel source to replace natural gas is of great importance for saving energy, reducing CO₂ emission reduction, and lowering environmental impact.