The present study mainly focus on two parts: one was the optimization of FactSage calculation, compared with HT-XRD measurements on mineral matter behaviors during the heating of coal and blend ashes from 500 °C to 1000 °C in reducing atmosphere. The aim was to obtain the optimized input parameters and options for FactSage calculation, and the outputs should be as close as possible to HT-XRD results. The other was the application of FactSage on ash melting behaviors. Since the maximum temperature of HT-XRD measurement in laboratory was 1000 °C in reducing atmosphere, the optimized FactSage was applied to investigate the ash melting behaviors in temperature range between 600 °C and 1600 °C for coal, biomass and their blends.
The FactSage calculation was optimized by investigations of several input parameters and options including the mass ratio of reactant gas amount to ash sample, solution species and compound solid species. The results obtained from the optimized calculation were much better to fit the mineral transformations measured by HT-XRD. However, there were still some differences between the results from optimized FactSage calculations and HT-XRD measurements. This is mainly due to the amorphous substances which occurred as solid phases and liquid slag in FactSage outputs but cannot be detected by HT-XRD. Besides, several factors, such as the diffusion, particle size distribution and so on, affect the actual measurements greatly but been neglected in thermodynamic calculations, which enhance the distinctions. In addition, the effects of atmosphere were investigated and the differences of mineral matter behaviors were mainly embodied in sulphur-rich minerals, iron-rich minerals and amorphous substance.
For application of FactSage on ash melting behaviors, AFTs tests for coal, biomass and their blends were adopted, and the results were well investigated by ash chemical components analyzed by XRF and also equilibrium phases calculated by FactSage. Hemispheric temperature and flowing temperature were mainly dependent on the high melting point substances at high temperature, such as free CaO in HKN and SWC, SiO2 in WS and KOL. The sintering temperature was largely affected by alkali oxides, which could combine with other oxides to form low melting point substances. For blended ashes, AFTs of the blended ash of HKN and WS shown a V shape with WS addition mass ratio rising, and the minimum values of AFTs appeared at 50 wt.% WS addition. AFTs of KOL changed in a small scale when mixed with WS, due to their similar ash composition (high in SiO2). As the SWC ash contents is much less than HKN and KOL, it did not affect the AFTs much when blended with coals. Moreover, the biomass addition affection on the blended ashes AFTs were also well illustrated by the liquid phases mass fraction and also the mineral matter transformations calculated by FactSage.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:22943 |
| Date | 16 December 2014 |
| Creators | Zhang, Guanjun |
| Contributors | Meyer, Bernd, Hessenkemper, Heiko, TU Bergakademie Freiberg |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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