Fundamental and Technical Challenges for a Compatible Design Scheme of Oxyfuel Combustion Technology

Oxyfuel combustion with carbon capture and sequestration （CCS） is a carbon-reduction technology for use in large-scale coal-fired power plants. Significant progress has been achieved in the research and development of this technology during its scaling up from 0.4 MWth to 3 MWth and 35 aWth by the combined efforts of universities and industries in China. A prefeasibility study on a 200 MWe large-scale demonstration has progressed well, and is ready for implementation. The overall research development and demonstration （RD＆D） roadmap for oxyfuel combustion in China has become a critical component of the global RD＆D roadmap for oxyfuel combustion. An air combustion/oxyfuel combustion compatible design philosophy was developed during the RD＆D process. In this paper, we briefly address fundamental research and technology innovation efforts regarding several technical challenges, including combustion stability, heat transfer, system operation, mineral impurities, and corrosion. To further reduce the cost of carbon capture, in addition to the large-scale deployment of oxyfuel technology, increasing interest is anticipated in the novel and next- generation oxyfuel combustion technologies that are briefly introduced here, including a new oxygen-production concept and flameless oxyfuel combustion.

Effect of Oxygen-Rich Combustion on Flame Propagation of Syngas in a Half-Open Pipe at Elevated Temperatures

The investigation of syngas flame propagation has great benefits for the effective use of gas turbines.This essay sets out to study the flame propagation of premixed oxygen-rich combustion(oxygen enrichment coefficient in volumeΩ:0.21,0.27,0.32,0.37)of syngas(H_(2):CO=2:8)in half-closed rectangular ducts at elevated temperatures(T:300 K,400 K,500 K)and evaluate the effects of initial temperature and oxygen enrichment coefficient on the LBV from sensitivity analysis and kinetic analysis.This paper presents the effect of the expansion effect on laminar burning velocity for the first time,and separates the effect of the expansion effect on laminar burning velocity by a new method.Research shows that as the initial temperature goes up,the faster the exponential growth phase of the flame front velocity,the slower the slow growth phase.The smaller and earlier the maximum flame front velocity arrives,the slower the average flame speed is.As the oxygen enrichment coefficient goes up,the peak value of the flame front velocity gradually decreases.Oxygen-rich combustion and increasing initial temperature inhibit flame propagation in a half-open tube,but promote laminar burning velocity,which increases the key chemical bond and adiabatic flame temperature.The net reaction rate shows that oxygen-rich combustion mainly promotes the combustion reaction of H_(2)(R2).However,increasing the initial temperature mainly promoted the oxidation of CO(R29).Analysis of the reaction path showed that oxygen-rich combustion and increased initial temperature promoted the reaction of H_(2)and CO with key chemical bonds,increased OH concentration,and inhibited OH cracking reaction.

Forms of potassium and chlorine from oxy-fuel co-combustion of lignite coal and corn stover

In this work,the forms of potassium and chlorine from oxy-fuel co-combustion of lignite coal and corn stover under atmospheric pressure were investigated.In order to check transitional stage,the feedstocks were combusted stepwise,first by pyrolysis to form coke under N2 environment and later by coke combustion into the ash at 850℃ in O_(2)/CO_(2) atmosphere.The results show that an increase in blend ratio from 15%to 40%results in an increase in water-soluble potassium in the feedstock and the ashes from 0.15%to 0.4%and 0.015%to 0.038%in weight respectively.The water-soluble potassium is present mainly as KCl and K2SO4.For ammonium acetate soluble potassium,a similar trend to water-soluble potassium is presented but with a much lower content of potassium.The bound potassium in the fuel matrix exists,likely in the form of AlKSi_(2)O_(6).Chlorides are present mainly in the form of KCl which is the dominant water-soluble compound.