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Heat Capacity and Oxidation Kinetic Studies of Fe-Ti Composite Metal Oxide (ITCMO) using Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis

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2017, Master of Science, Ohio State University, Chemical Engineering.
The present work aims to understand the oxidation kinetics of Iron-Titanium composite (ITCMO) metal oxides used in Coal Direct Chemical Looping (CDCL), an advanced combustion process with near zero carbon dioxide emissions. Chemical Looping is an emerging third-generation advanced carbon capture technology with the most cost reduction benefits among all existing CO2 capture technologies. The Ohio State University has pioneered the development of Coal Direct Chemical Looping (CDCL) technology for efficient and cost-effective carbon capture from power plants.The CDCL process uses a proprietary Fe-Ti composite metal oxide developed by the OSU Clean Energy Laboratory that transfers oxygen from the air to fully oxidize coal through a redox reaction mechanism. Pulverized coal is injected into the moving bed reducer where the oxygen carrier is reduced while maximizing the oxidation of coal. The reduced oxygen carrier is combusted in an air combustor in a highly exothermic reaction. The design of the reducer has been studied in greater detail to develop this technology to establish the gas-solid multi phase flow contact pattern and kinetics. A pre-FEED study is in progress to demonstrate this technology on a 10MWe scale. For a successful demonstration of this technology and further scale up on to a 550MWe unit; the oxidation kinetics need to be thoroughly established. The kinetics of the Combustor is necessary for the development of a heat exchanger network and a CFD model. The HEN network is required to remove the exothermic heat using in bed heat exchangers in the fluidized bed combustor. System parameters for dynamic simulation models of the process also need to be established. This study focused on the estimation of the heat capacity of Fe-Ti composite metal oxide particles (ITCMO) used in the CDCL technology. Calculation of activation energy, rate constant and heat of reaction of the ITCMO particles reduced using H2 and CO is also carried out. A preliminary kinetic model is created for the development of an ASPEN Plus simulation model. A simultaneous Differential Scanning Calorimetry and Thermogravimetric Analyzer was used to measure the heat and weight changes in the ITCMO samples. The heat capacity experiments were performed at temperatures from 200C -1200C under inert N2 atmosphere. The heat of reaction studies was carried out at temperatures ranging from 750C - 1100C which are representative of the temperatures used in the combustor. The model prepared from the isothermal studies show that the reaction rate is governed by a complex diffusion controlled mechanism. The initial reaction is governed by a logarithmic rate law indicating that the for the first 90 seconds, the reaction proceeds by a followed by a slow diffusion process. At higher temperature, ionic diffusion affects the reaction rate. The reaction happens on the grain boundaries. At temperatures above 800C, the formation of pseudobrookite is favored. Based on the observations from the isothermal studies, temperature programmed oxidation and corresponding heat of reaction, a reaction pathway is proposed for the oxidation reactions.
Liang-Shih Fan (Advisor)
Andre Palmer (Committee Chair)
83 p.

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Citations

  • Kumar, P. (2017). Heat Capacity and Oxidation Kinetic Studies of Fe-Ti Composite Metal Oxide (ITCMO) using Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502723527531035

    APA Style (7th edition)

  • Kumar, Prateek. Heat Capacity and Oxidation Kinetic Studies of Fe-Ti Composite Metal Oxide (ITCMO) using Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis. 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1502723527531035.

    MLA Style (8th edition)

  • Kumar, Prateek. "Heat Capacity and Oxidation Kinetic Studies of Fe-Ti Composite Metal Oxide (ITCMO) using Simultaneous Differential Scanning Calorimetry and Thermogravimetric Analysis." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1502723527531035

    Chicago Manual of Style (17th edition)