Techno-economic assessment of Blast furnace gas pre-combustion decarbonisation integrated with the power generation

Aiming at the iron and steel industry decarbonisation with blast furnace gas (BFG) utilisation, techno-economic feasibility of the pre-combustion carbon capture with methyl diethanolamine (MDEA) is evaluated herein. The effectiveness of water gas shift (WGS) implementation on the capture performance is also investigated. The integration of a power plant with decarbonised fuel from the capture unit is taken into account from both technical and economic perspectives. Aspen Plus® is used to develop the process. The results obtained from the techno-economic analysis showed that the WGS implementation increases the capture efficiency from 46.5% to 83.8%, with increased CO2 capture cost from €39.8/𝑡𝐶𝑂2 to €44.3/𝑡𝐶𝑂2. The sensitivity analysis on the effect of 1) different BFG composition and 2) different carbon capture rate (CCR) on the capture unit integrated with WGS performance is performed. The obtained results revealed that BFG with a lower calorific value is less practical from a techno-economic point of view as it increases the specific primary energy consumption for CO2 capture avoidance (𝑆𝑃𝐸𝐶𝐶𝐴) from 3.3 𝑀𝐽𝐿𝐻𝑉/𝑘𝑔𝐶𝑂2 to 3.8 𝑀𝐽𝐿𝐻𝑉/𝑘𝑔𝐶𝑂2. Moreover, the lower CCR increases the thermal energy of the H2-rich gas from the capture unit from 266.8 MW to 269.6 MW. The techno-economic advantages of the based case do not results beneficial for na environment point of view since at lower CCR the specific CO2 emissions increase from 51 𝑘𝑔𝐶𝑂2/𝐺𝐽𝐿𝐻𝑉 to 70 𝑘𝑔𝐶𝑂2/𝐺𝐽𝐿𝐻𝑉. The fully integrated power plant to the capture unit reveals that the 37.52% (without WGS) and 24.27% (with WGS) efficiencies are achievable through the combined cycle integration. For the combined cycle, the integration of WGS reactor will reduce the CO2 specific emission to 675.1 𝑘𝑔𝐶𝑂2𝑀𝑊ℎ⁄ in comparison to 1391.5 𝑘𝑔𝐶𝑂2𝑀𝑊ℎ⁄ for the case with no WGS.