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Direct observation of swelling coal particles. Using high-temperature confocal scanning laser microscopy to examine some intrinsic and extrinsic influences on the unconstrained thermal swelling of discrete coal particles
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Moore, Ian A. (2019) Direct observation of swelling coal particles. Using high-temperature confocal scanning laser microscopy to examine some intrinsic and extrinsic influences on the unconstrained thermal swelling of discrete coal particles. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b3453539~S15
Abstract
Steel is the most important engineering and construction material in the world, with global production predicted to continue rising to meet the needs of a growing population. The steel industry is therefore economically important, but also energy intensive and thus a significant source of carbon emissions.
The blast furnace–basic oxygen furnace (BF-BOF) integrated route to steelmaking will retain a strong contribution to steel production throughout the current century, as such its continued improvement is desirable. Pulverised coal injection (PCI) is a key part of modern blast furnace ironmaking as it reduces the dependence upon coke, which is costly and environmentally unfriendly to produce. PCI involves injecting fine coal particles into the raceway of a blast furnace via the tuyeres.
Different coal types vary in their suitability for blast furnace injection, therefore a thorough understanding of all aspects of coal behaviour during blast furnace injection is necessary for optimised PCI operation. A relevant feature of coal behaviour is the thermoplastic swelling of coal particles; however, little is known about the effects of coal thermoplasticity on blast furnace performance. The high temperature confocal scanning laser microscope (HT-CSLM) offers a potential novel technique to evaluate the thermoplastic swelling properties of coal particles.
This thesis investigates the applicability of the HT-CSLM technique to the study of the thermal swelling of discrete coal particles. Four types of coal are included. The effect of heating rate on swelling behaviour is investigated, as is the effect of particle density. A study of the influence of particle size on swelling behaviour was conducted using size and density separated samples in an attempt to mitigate against the segregation of components during comminution. A drop tube furnace (DTF) was used to ‘scale-up’ the experiments by providing a heating environment closer to that of the blast furnace raceway.
Results show that the HT-CSLM is a suitable technique for this type of study, although with a limitation regarding highly fluid coals. The maximum swelling ratio of coal particles is shown to increase with increasing heating rate. Lighter particles are found to be generally more highly swelling, which can be related to composition. The effect of particle size differed between coal types and suggested the possibility of a coal type-dependent optimum particle size in relation to maximum swelling ratio. The HT-CSLM and DTF swelling results were in agreement provided certain assumptions were made. Char reactivity results indicated that a greater degree of swelling led to more reactive char particles, however no evidence was found that swelling increased the rate of coal conversion at short residence times.
| Item Type: | Thesis (PhD) | ||||
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| Subjects: | T Technology > TD Environmental technology. Sanitary engineering T Technology > TN Mining engineering. Metallurgy T Technology > TP Chemical technology |
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| Library of Congress Subject Headings (LCSH): | Coal -- Combustion, Coal -- Thermal properties, Coal, Pulverized, Particles -- Measurement, Steel industry and trade, Manufacturing industries | ||||
| Official Date: | August 2019 | ||||
| Dates: |
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| Institution: | University of Warwick | ||||
| Theses Department: | Warwick Manufacturing Group | ||||
| Thesis Type: | PhD | ||||
| Publication Status: | Unpublished | ||||
| Supervisor(s)/Advisor: | Seetharaman, Sridhar ; Li, Zushu ; Atkinson, Colin | ||||
| Sponsors: | Tata Iron and Steel Company ; Engineering and Physical Sciences Research Council ; Materials Processing Institute | ||||
| Format of File: | |||||
| Extent: | xxi, 260 leaves : illustrations, charts | ||||
| Language: | eng |
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