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A transport bed flash calcination (TBFC) process applied to magnesite is systematically investigated through process simulation to optimize the energy-saving strategy. The high-temperature calciner flue gas is used to preheat the fed magnesite, while the sensible heat with the caustic calcined magnesia (CCM) product is cooled by air sent to the calciner. Pre-decomposition of magnesite during preheating is considered on basis of the kinetics measured using a micro fluidized bed reaction analyzer that allows the minimized effect of external diffusion on reaction. With staged fuel gas supply the TBFC process allows the equivalence ratios around 1.2 for combustion. The preferred arrangement of stages for magnesite preheating and CCM cooling are respectively 4 and 2, leading to the energy consumption of 4100 kJ/kg-CCM and the energy efficiency of 66.8%, which is almost doubly higher than the 33.9% of the conventional reverberatory furnaces (RF). The pre-decomposition occurs mainly in the 1st-stage preheater, and the maximal conversion is about 13%. Varying the stages of preheating appears more influential on the energy saving than varying the cooling stages, while residence time above 1 s in the preheaters has limited effect.

There are few studies about pyrolysis with the a massive sample at high heating rates to obtain liquid and gas products. This study adopted a newly designed small fixed bed reactor mounted with infrared heating to minimize secondary reactions to volatiles and further to investigate the pyrolysis of Xinjiang Naomaohu coal in terms of pyrolysis products characterization at different temperatures and heating rates. Infrared heating has good penetrability to heat the inner layer of the sample at a quick rate of up to 1723 °C/min in the particle bed. For the tested reactor at 700 °C, raising the heating rate decreased the yields of gas and char and increased the yield of tar. The realized tar yield was higher than that in Gray-King (G-K) assay at heating rates above 18 °C/min. For the heating rate of 667 °C/min at the pyrolysis temperature of 700 °C, the obtained maximum yield of tar was 134% of the G-K assay oil yield. Overall, increasing the heating rate decreased char yield and increased the production of total volatiles. At higher heating rates, the tar became heavier, while at higher pyrolysis temperatures, it produced more light tar. The extraction rate of hydrogen from coal was found to be subject to a linear relationship with pyrolysis gas yield.

This study investigated the characteristics of pyrolysis for waste tire particles in the newly developed fixed-bed reactor with internals that are a central gas collection channel mounted inside reactor. And a few metallic plates vertically welded on the internal wall of the reactors and extending to the region closing their central gas collection pipe walls. Experiments were conducted in two laboratory fixed bed reactors with or without the internals. The results shown that employing internals produced more light oil at externally heating temperatures above 700 °C due to the inhibited secondary reactions in the reactor. The oil from the reactor with internals contained more aliphatic hydrocarbons and fewer aromatic hydrocarbons, leading to its higher H/C atomic ratios as for crude petroleum oil. The char yield was relatively stable for two beds and showed the higher heating values (HHVs) of about 23 MJ/kg. The gaseous product of pyrolysis mainly consisted of H2 and CH4, but the use of internals led to less pyrolysis gas through its promotion of oil production. Keywords: Pyrolysis, Waste tire, Fixed bed, Internals, Secondary reactions

Thermochemical conversion of fuels via pyrolysis/carbonization, cracking, gasification and combustion has to involve a number of individual reactions called attribution reactions to form an intercorrelated reaction network for any conversion process. By separating one or some attribution reactions from the others to decouple their interactions existing in the reaction network, the so-called reaction decoupling enables a better understanding of the complex thermal conversion process and further the optimization of the conditions for attribution reactions as well as the entire conversion process to realize advanced performances. The dual bed conversion and two-stage conversion are the two representative types of fuel conversion technologies developed in recent years based on reaction decoupling. Many technical advantages have been proven for such decoupling fuel conversion technologies, such as poly-generation of products, low-cost production of high-grade products, elimination of undesirable products or pollutants, easy operation and control, and so on. The treated fuels with decoupling conversion technologies mainly include solid biomass and coal, as well as liquid petroleum oil. This paper is devoted to reiteration of the reaction decoupling concept and further to reviewing the research, developments and successful applications of several decoupling fuel conversion technologies of two such types by using fluidized bed as their major reactors. Keywords: Reaction decoupling, Fuel conversion, Reaction network, Fluidized bed, Dual bed, Two-stage

This work investigates the evolution of micro/meso pores during a mild thermal treatment of subbituminous coal based on the observation of coal structure changes with the gradual detachment of organic matter from the coal. Pores in coal can be described as super-micropores (d < 1 nm), micropores (1 nm < d < 2 nm) and mesopores (2 nm < d < 50 nm). The decomposition of the carboxyl group at 200 °C decreases the super-micropore volume. A mild and sustained reaction takes place at 300 °C to gradually change the aromaticity and CH2/CH3 ratio of the treated coal. The amount of micropore structure sharply decreases in the early stages of heating, while the amount of mesopore structure continuously decreases during the whole process. A dramatic reaction takes place at 400 °C to sharply change the aromaticity and CH2/CH3 ratio of the treated coal, while the detachment of volatile compounds from the coal matrix caused an evident variation in the mesopore structure of the coal. The aromaticity and CH2/CH3 ratio of coal organics are found to correlate with the volumes of super-micropores and mesopores, respectively. The super-micropores are identified as comprising the inter-layer distance between stacks of aromatic rings, and mesopores are the spaces between macromolecular aromatic rings which are inter-connected via aliphatic chains.