- Thesis topic: Investigating Trade-Off Between Carbon and Flue Gas Emission Abatements in Steel and Cement Industries

- Doi: 

- Abstract: 

        This study analyzes the emissions of carbon dioxide, particulate matter (PM), sulfur oxides (SOₓ), and nitrogen oxides (NOₓ) from the cement and steel industries. It explores differences in production processes, fuel usage, and the current status and potential of energy-saving and emission-reduction strategies. The goal is to provide scientific data that supports the pursuit of both economic development and environmental sustainability.
For the cement industry, this study compiles air pollutant and carbon emission data from 2018 to 2022 and calculates the emission factors for each plant. The five-year average carbon emission factors for CM01, CM02, CM03, and CM04 were 777, 1068, 965, and 1002 kg/ton of cement, respectively; PM emission factors were 160, 27, 368, and 256 g/ton; SOₓ emission factors were 13, 22, 156, and 48 g/ton; and NOₓ emission factors were 1106, 1444, 1474, and 1214 g/ton of cement, respectively. The carbon and nitrogen oxide emission factors of Taiwan's cement industry are relatively higher compared to those of some other countries. Therefore, it is recommended that Taiwan’s cement industry reduce its clinker-to-cement ratio, switch from coal to fuel oil or natural gas, and expedite the installation of NOₓ control equipment. Furthermore, prior to using alternative fuels, it is essential to assess the fuel composition, in-plant processes, and existing control technologies to fully realize the co-benefits of alternative fuels. In the steel industry, the five-year average carbon emission factors for ST01 and ST02 were 2305 and 1681 kg/ton of crude steel, respectively; PM emissions were 252 and 116 g/ton; SOₓ emissions were 595 and 373 g/ton; and NOₓ emissions were 686 and 434 g/ton of crude steel.
In response to the anticipated tightening of air pollution regulations for the steel sector by local authorities, this study collected Continuous Emission Monitoring System (CEMS) data from the coke oven and sintering plants of an integrated steel mill. It compiled the emission concentration trends for each flue gas from 2018 to 2022 and applied a 720-hour moving average to observe emission variations. In addition, the 2022 emission concentrations were compared against the proposed stricter emission standards to evaluate exceedance rates. These data were then cross-referenced with process and equipment information disclosed in permit documents for comprehensive assessment. Results show that for the ST01 plant, 75% and 99% of SOₓ and NOₓ concentrations in the PC23 coke oven flue, and 98% and 99% in the PC83 flue, complied with the stricter standards. For the four main sintering flues, 97–99% of SOₓ and NOₓ concentrations were within the regulatory limits, although occasional exceedances were still observed. The adoption of Coke Dry Quenching (CDQ) technology in the coking process could help further reduce such exceedances. Moreover, data from permission indicate that the ST01 sintering furnaces currently focus on sinter production and rely primarily on coke oven gas, coke breeze, and anthracite as fuel. Transitioning to pellet production and introducing biomass fuels could achieve co-benefit reductions in both air pollutants and carbon emissions.

Keywords: Iron and steel making Industry, Cement Industry, Carbon emission factor, Air pollutant emission factor, Alternative fuel, Co-benefit reduction.