Thermodynamic analysis of synergistic coal gasification using blast furnace slag as heat carrier

Abstract

In this paper, a thermodynamic analysis of the synergistic coal/CO2/H2O gasification process with BFS (blast furnace slag) as heat carrier was performed using the Gibbs free energy minimization approach through Lagrange multiplier method. The effect of temperature, pressure and C/CO2/H2O were investigated. Carbon, CO2 and H2O conversion, H2 and CO yield, and H2/CO ratio were used to characterize the synergistic gasification performance. The results showed that the atmospheric pressure was preferable for coal gasification and the increasing of temperature caused the increase in carbon conversion and syngas production. The optimal temperature of the synergistic gasification was 800-900 ºC. Not only did it ensure the coal gasification reaction completely, but also it recovered the BFS waste heat effectively. The results clearly showed that the addition of H2O and CO2 could lead to the reduction of the carbon residue and increase of the production of H2 and CO, respectively. Meanwhile, it was beneficial to reduce the waste heat using to heating extra steam and enhance the coal/CO2 gasification reaction rate by controlling the addition of CO2 and H2O reasonably. Moreover, the production syngas application was also investigated by changing the relative CO2/C ratio and H2O/C ratio in the feed to modify the H2/CO ratio.

Potential use of liquid metal oxides for chemical looping gasification: A thermodynamic assessment

“…To the best of our knowledge, neither theoretical nor experimental investigations of gasification using molten metal have been reported previously. Figure 3 presents the syngas quality (H2/CO) estimated with the HSC model in comparison with Yu et al [61] for two different steam to fuel ratios at 1200°C. As can be seen, the results calculated for syngas quality agree with those of calculated by Yu et al [61] to within an absolute average deviation of ±16%.…”

“…Figure 3 presents the syngas quality (H2/CO) estimated with the HSC model in comparison with Yu et al [61] for two different steam to fuel ratios at 1200°C. As can be seen, the results calculated for syngas quality agree with those of calculated by Yu et al [61] to within an absolute average deviation of ±16%. This is deemed to be sufficiently reliable for the present assessment of thermodynamic feasibility of the system.…”

“…To partially validate the model, the results obtained for the gas production and syngas quality were compared with previous studies on gasification with molten slag reported by Yu et al [61]. To the best of our knowledge, neither theoretical nor experimental investigations of gasification using molten metal have been reported previously.…”

“…In particular, it offers high rates of heat and mass transfer, which results in good controllability in operation and syngas quality. Hence, the ratio of the H2/CO can be readily adjusted through the ratio of CO2/feedstock or H2O/feedstock, which leads to the high carbon conversion rates and high quality of the syngas product [29][30][31][32][33][34][35].…”

Integration of biomass/steam gasification with heat recovery from hot slags: Thermodynamic characteristics

“…Li et al experimentally investigated the kinetics of coal gasification reaction using the waste heat from BFS under CO 2 agent and found that the BFS acted as a good catalyst on coal gasification [15,16] and recently Duan et al [17,18] calculated the thermodynamics of coal/ steam gasification in the presence of BFS. Compared to primary coal, biomass was a natural carbon-neutral, the gasification of which is generally an important approach of syngas production for the chemical engineering industry [19,20].…”