Study on emission factors of FCC flue gas pollutants in petroleum refineries

Abstract

Fluid Catalytic cracking (FCC) unit is one of the means to lighten heavy oil in re neries, and its regenerated ue gas is also the main source of air pollutants from re nery. However, it is not clear about the type and amount of pollutants discharged from FCC units. The emissions of regenerated pollutants in the stack ue gases of three typical FCC units in China were investigated in this study, including a partial regeneration unit without a CO boiler (U1), a partial regeneration unit with a CO boiler (U2) and a full regeneration unit (U3). Different monitoring methods were used to analyze the concentration of sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ), and the results showed that Fourier Transform Infrared Spectroscopy (FTIR) monitoring results of SO 2 and NO x are approximately 10 times and 5 times larger than that of the Continuous Emission Monitoring System (CEMS) data, respectively. Also, the contents of characteristic pollutants such as NH 3 , C 6 H 6 , HCN, C 8 H 8 , C 2 H 4 , CH 4 and CO were also monitored by FTIR, and the emission factors based on coke burn-off rate and throughput were investigated. The pollutants in U1 exhibited relatively higher contents with the NH 3 , HCN and C 6 H 6 of 116.99, 71.94 and 56.41 mg/Nm 3 in ue gas, respectively. The emission of regenerated pollutants in U2 and U3 are signi cantly different from U1. Regeneration processes (including coke properties, operating modes and presence or absence of CO boilers) affected pollutants emission factors in varying degree. At last, reasonable emission factors based on the different FCC regeneration processes contributes to the prediction, assessment and control for the pollutants emission.

Investigation on NO reduction behavior within complex atmosphere during pilot ignition of low calorific gas

“…6 In comparison, it is a more promising approach to ignite and improve the flame stability of LCG by using a pilot flame. 7–9…”

“…6 In comparison, it is a more promising approach to ignite and improve the flame stability of LCG by using a pilot flame. [7][8][9] In addition, the LCG generation processes generally bring NO or other N-contained species (NH 3 , or HCN) involved, causing a tendency of high NO x emission during combustion. To utilize the heating resource of LCG conveniently, a modified pilot ignition approach had been proposed 10 to improve its ignition stability, and the air stage approach was together adopted to reduce NO emission via enhancing the re-burning (by CH 4 ) effect.…”