Kinetics Of Powdered Coal Gasification In A Tubular Type Gasifier

Author : Ying Wang
Publisher :
ISBN 13 : 9781369094107
Total Pages : 143 pages
Book Rating : 4.0/5 (941 download)

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Download or read book CO2 and Steam Gasification Kinetics of Powder River Basin Coal Using a Modified Droptube Reactor written by Ying Wang and published by . This book was released on 2016 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gasification is the conversion of the organic fraction of a solid or liquid feedstock into product gases through partial combustion. Carbon reacts with CO2 and/or H2O to produce Syngas, which is primarily CO and H2. Carbon dioxide and steam gasification reaction rates were measured in a modified drop tube fixed bed reactor, accompanied with a customized rapid response, real-time gas analysis system with a quadrupole mass spectrometer. Rapid heating and fast pyrolysis of the coal sample are intended to approximate the injection of ambient temperature coal into a fluidized bed gasifier. Experiments were done within the Regime I temperature range (no mass transfer restrictions) and also in the Regime II temperature range, in which both surface reaction rates and mass transfer restrictions affect the observed reaction rates. The effects of temperature and pressure on reaction rates were analyzed using three different particle size ranges. Temperature varied from 833°C to 975°C and pressure was from 1 atm to 12 atm. The random pore model closely fit the experimental results and the fitting parameters are listed. Mass transfer resistances were analyzed by comparing experimental and theoretically predicted effectiveness factors using the Thiele modulus. Char characterizations are presented, including surface area measurements and scanning electron microscope images. Langmuir–Hinshelwood models are used for a CO2 and Steam competition study and inhibition of steam gasification by H2. This dissertation found a rarely observed competition mechanism, named steam-dominating competition. When H2O and CO2 are both present, H2O molecules primarily occupy active sites. The L-H type equation of this mechanism was proposed and it matches experimental results. H2 showed significant inhibition effect on steam gasification, as increasing the ratio of H2/H2O continuously decreases the steam gasification reactivity. The inhibition effect becomes less when reaction pressure increases, as the adsorption of H2O on active sites becomes more competitive than H2 adsorption. The values of the L-H parameters were calculated.