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

Helin Pan,Hao Ling,Cong Wu,Feng Ju,Hui Luan,Guangli Xiu

doi:10.1007/s11356-021-16767-1

Helin Pan, Hao Ling + Show 4 more

Open Access

https://doi.org/10.1007/s11356-021-16767-1

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Abstract

Fluid catalytic cracking (FCC) unit is one of the means to lighten heavy oil in refineries, and its regenerated flue gas is also the main source of air pollutants from refinery. However, it is not clear about the type and amount of pollutants discharged from FCC units in China. The emissions of regenerated pollutants in the stack flue 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 (SO2) and nitrogen oxides (NOx), and the results showed that Fourier transform infrared spectroscopy (FTIR) monitoring results of SO2 and NOx are approximately 10 times and 5 times larger than those of the continuous emission monitoring system (CEMS) data, respectively. Also, the contents of characteristic pollutants such as NH3, C6H6, HCN, C8H8, C2H4, CH4, 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 NH3, HCN, and C6H6 of 116.99, 71.94, and 56.41 mg/Nm3 in flue gas, respectively. The emission of regenerated pollutants in U2 and U3 are significantly different from U1. Regeneration processes (including coke properties, operating modes, and presence or absence of CO boilers) affected pollutants' emission factors in varying degrees. At last, reasonable emission factors based on the different FCC regeneration processes contribute to the prediction, assessment, and control for the pollutant emission.

Highlights

The Fluid Catalytic cracking (FCC) is the core process technology for lightening heavy oil in petroleum refining enterprises, and it is one of the key monitoring sources for the petroleum refining industry
Different monitoring methods were used to analyze the concentration of sulfur dioxide (SO2) and nitrogen oxides (NOx), and the results showed that Fourier Transform Infrared Spectroscopy (FTIR) monitoring results of SO2 and NOx are approximately 10 times and 5 times larger than that of the Continuous Emission Monitoring System (CEMS) data, respectively
In order to find out the emissions of FCC regenerated pollutants, such as whether the pollutant concentration exceeds the limitation, whether the online monitoring data is accurate and whether there are unknown pollutants, the on-site monitoring of typical FCC unit regenerated flue gas was carried out by using the FTIR method

Summary

Introduction

The FCC is the core process technology for lightening heavy oil in petroleum refining enterprises, and it is one of the key monitoring sources for the petroleum refining industry. The FCC catalyst regenerator vent might be the biggest single source of air pollution in an oil refinery. The FCC catalyst regenerator vent releases a wide variety of pollutants, including particulate matters (PM), SO2, NOx, CO, VOCs, metal hazard air pollutants (HAPs), organic HAPs, and ammonia (US EPA, 2015). These pollutants could have an impact on population health. Despite this critical scenario, few studies have been developed with the objective of fully evaluating pollutant emissions of the FCC catalyst regenerator vent, especially regarding the quantification of pollutant emission sources

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