Gasification is a flexible technology which is applied in industry for electricity generation, hydrogen production, steam raising and liquid fuels production. Furthermore, it can utilize one or more feedstocks such as coal, biomass, municipal waste and petroleum coke. This versatility, in addition to being adaptable to various emissions control technologies (including carbon capture) renders it an attractive option for years to come. One of the most common gasifier types is the entrained-flow slagging gasifier. The behaviour of inorganic fuel components in these gasifiers is still ill-understood even though it can be the determining factor in their design and operation. A literature review of inorganic matter transformation sub-models for entrained-flow slagging gasifiers is provided. Slag viscosity was identified as a critical property in the sub-models. Slag viscosity models are only applicable to a limited range of slag compositions and conditions, and their performance is not easily assessed. An artificial neural network model was developed to predict slag viscosity over a broad range of temperatures and slag compositions. Furthermore, a toolbox was developed to assist slag viscosity model users in the selection of the best model for given slag compositions and conditions, and to help users determine how well the best model will perform. The slag viscosities of coal, petroleum coke and coal/petroleum coke blends were measured in the temperature range of 1175-1650ºC. Interaction of vanadium-rich slags with various materials was investigated. The results from the first two parts of a three-part research program which involves fuel characterization, testing in a 1 MWth gasifier, and computational fluid dynamics (CFD) modeling for entrained-flow slagging gasification are presented. The end goal is to develop a CFD model which includes inorganic matter transformations. Fuel properties were determined with prioritization based on their application; screening of potential fuels, ensuring proper gasifier operation, gasifier design and/or CFD modeling. Using CanmetENERGY’s 1 MWth gasifier, five gasification tests were completed with the characterized coals. Solid samples from the refractory liners, in-situ gas sampling probe sheaths and impingers, the slag tap, the slag pot, quench discharge water and scrubber water were collected and characterized.

Thesis (Ph. D.)--Lehigh University, 2003. / In two parts. Includes vita. Includes bibliographical references (leaves 307-330).

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Extensive literature reviews are presented in this thesis with respect to the hydration of slag, especially on the mechanism of hydration. The range of work in the thesis includes: 1) compressive strength testing on slag cement pastes and slag pastes with other alkaline activators; the effect of curing temperatures and slag compositions were specially discussed. 2) Analysis of pore fluid from slag/NaOH pastes. 3) Porosity and pore structure analysis of slag cement pastes as a function of age. 4) Phase development in hydrating slag or slag cement pastes. 5) Microstructural and microchemical development of slag hydration products. Electron microscopy has shown that several chemically and microstructurally distinct zones quickly develop in a hydrating slag cement paste. Initially, a dense layer of gel-like hydration product forms around slag grains. The microstructure and chemistry of the gel are not constant, but evolve with time. Microstructural evolution is manifested by the crystallization of the previously formed gel hydrate, with the formation of a hydrotalcite-like phase. This crystallization is accompanied by distinctive chemical evolution, in which Ca, Si and some A1 migrate into the outer matrix; however, Mg appears to be virtually immobile. The evolution results in the creation of pores in the in-situ slag hydration zones, and at the same time, the marked densification of the outer matrix. Mass balance calculations are used to support the microstructural observations and to generalize on them, so the extent of the densification potential can be assessed. The ability to calculate the potential for densification, at least in principle, is regarded as an important step forward in the design for durability. A theory, based on the microstructural observations, is proposed to account for the differences between the calculated and observed porosities.

Thesis (Ph.D.)--University of Western Australia, 2007.