Plenary Speakers

Abstract: Traditional coal combustion has a series of drawbacks such as high pollution, high emission and low efficiency, and traditional coal gasification also faces problems of heavy pollution, complicated system and high temperature requirement. Owing to the unique properties such as high solubility, diffusivity and reactivity of supercritical water (SCW), supercritical water gasification (SCWG) technology provides a clean, low-carbon and high-efficiency way for coal conversion for hydrogen production and has a promising market future. For the technology application, mild gasification temperature can effectively decrease investment and energy consumption but also means low reaction driving force, therefore, the current bottleneck is to reduce the overall reaction resistance. For this purpose, the resistance analogy analyze is applied in this work to match heat transfer, mass transfer and chemical reaction properly. Through lump parameter and time scale analyze, the ring-opening reaction of PAH is found to be the rate-determining step (RDS) in the gasification process, and the further molecular simulation shows that proper regulation of the free radical in SCW clusters can lower the energy barrier of ring-opening reaction by 70%. Based on this, a mass flow match method is proposed to provide free radical to the RDS area in the reactor, and carbon conversion is obviously promoted under mild temperature. To solve the problem that side reaction is apt to occur in nozzle and bottom areas with high coal particle concentration, numerical study is conducted to obtain accurate equations for drag force, heat transfer and diffusion prediction firstly as the fundamental study. In nozzle area, low temperature is maintained by proper heat boundary, and the side reaction volume is decreased by adjusting the injection angle. At reactor bottom, a swirling distributor is invented for more vigorous back-mixing and disturbing for a better particle distribution, thus effectively inhibits the side reaction. Finally, the main reactions need to be coordinated for high hydrogen production. An accurate kinetic model taking the porous structure characteristics into account is proposed firstly which decreases the model error of the existing model from 20% to 4%. Then, heat match is conducted for the reactor to not only avoid overheating, but also reduce the heat transfer resistance. On the basis of the optimization methods above, the complete gasification temperature can be below 670℃, and a demonstration plant was constructed and has continuously and stably operated for more than 10000 hours with good coal adaptability. In future work, the reaction field will be divided according to the heat/mass transfer and chemical reaction rule, and the resistance analogy will be conducted separately in these areas, to realize better match of mass and energy flow in reactor amplification and dynamic control process.

Abstract: The LPG industry, with current global consumption of some 300 million tonnes per year, is faced with decarbonising its product, as is the rest of the fossil fuel sector. Research has identified eight potential pathways to renewable LPG (RLPG): so far only one of them is commercial. This lecture presents an analysis and ranking of the eight pathways. The most-promising are: HVO, which is already commercial; gasification of biomass; and oligomerisation of olefins (alcohol-to-jet).