skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Determination of Sticking Probability Based on the Critical Velocity Derived from a Visco-Elastoplastic Model to Characterize Ash Deposition in an Entrained Flow Gasifier

Authors:
; ;
Publication Date:
Research Org.:
National Energy Technology Lab. (NETL), Pittsburgh, PA, and Morgantown, WV (United States). In-house Research
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1165549
Report Number(s):
NETL-PUB-1003
Journal ID: ISSN 0887-0624
Resource Type:
Journal Article
Resource Relation:
Journal Name: Energy and Fuels; Journal Volume: 28; Journal Issue: 8
Country of Publication:
United States
Language:
English

Citation Formats

Gibson, LaTosha M, Shadle, Lawrence J, and Pisupati, Sarma V. Determination of Sticking Probability Based on the Critical Velocity Derived from a Visco-Elastoplastic Model to Characterize Ash Deposition in an Entrained Flow Gasifier. United States: N. p., 2014. Web. doi:10.1021/ef5008616.
Gibson, LaTosha M, Shadle, Lawrence J, & Pisupati, Sarma V. Determination of Sticking Probability Based on the Critical Velocity Derived from a Visco-Elastoplastic Model to Characterize Ash Deposition in an Entrained Flow Gasifier. United States. doi:10.1021/ef5008616.
Gibson, LaTosha M, Shadle, Lawrence J, and Pisupati, Sarma V. Thu . "Determination of Sticking Probability Based on the Critical Velocity Derived from a Visco-Elastoplastic Model to Characterize Ash Deposition in an Entrained Flow Gasifier". United States. doi:10.1021/ef5008616.
@article{osti_1165549,
title = {Determination of Sticking Probability Based on the Critical Velocity Derived from a Visco-Elastoplastic Model to Characterize Ash Deposition in an Entrained Flow Gasifier},
author = {Gibson, LaTosha M and Shadle, Lawrence J and Pisupati, Sarma V},
abstractNote = {},
doi = {10.1021/ef5008616},
journal = {Energy and Fuels},
number = 8,
volume = 28,
place = {United States},
year = {Thu Aug 21 00:00:00 EDT 2014},
month = {Thu Aug 21 00:00:00 EDT 2014}
}
  • By comparing the spatial distribution of Ti atom density in front of a planar substrate with a diffusion model proposed by Chantry [P. J. Chantry, J. Appl. Phys. 62, 1141 (1987)], the authors evaluated the sticking probability of Ti atoms in magnetron sputtering deposition. The spatial distribution of Ti atom density was measured precisely by laser-induced fluorescence imaging spectroscopy. They found that the sticking probability of Ti atoms during the growth of Ti film was 0.9{+-}0.2. This result suggests the possibility that the sticking probability is less than unity, which is widely assumed in many simulation studies. The sticking probabilitymore » was almost unchanged when the discharge pressure and power were varied. In addition, heating the substrate at 250 deg. C and biasing it at a self-bias voltage of -200 V by a rf power had no significant influence on the sticking probability.« less
  • Coal gasification is a versatile process to convert a solid fuel in syngas, which can be further converted and separated in hydrogen, which is a valuable and environmentally acceptable energy carrier. Different technologies (fixed beds, fluidized beds, entrained flow reactors) are used, operating under different conditions of temperature, pressure, and residence time. Process studies should be performed for defining the best plant configurations and operating conditions. Although 'gasification models' can be found in the literature simulating equilibrium reactors, a more detailed approach is required for process analysis and optimization procedures. In this work, a gasifier model is developed by usingmore » AspenPlus as a tool to be implemented in a comprehensive process model for the production of hydrogen via coal gasification. It is developed as a multizonal model by interconnecting each step of gasification (preheating, devolatilization, combustion, gasification, quench) according to the reactor configuration, that is in entrained flow reactor. The model removes the hypothesis of equilibrium by introducing the kinetics of all steps and solves the heat balance by relating the gasification temperature to the operating conditions. The model allows to predict the syngas composition as well as quantity the heat recovery (for calculating the plant efficiency), 'byproducts', and residual char. Finally, in view of future works, the development of a 'gasifier model' instead of a 'gasification model' will allow different reactor configurations to be compared.« less
  • In the study, two fly ash samples from Texaco gasifiers were compared to coal char and the physical and chemical properties and reactivity of samples were investigated by scanning electron microscopy (SEM), SEM-energy-dispersive spectrometry (EDS), X-ray diffraction (XRD), N{sub 2} and CO{sub 2} adsorption method, and isothermal thermogravimetric analysis. The main results were obtained. The carbon content of gasified fly ashes exhibited 31-37%, which was less than the carbon content of 58-59% in the feed coal. The fly ashes exhibited higher Brunauer-Emmett-Teller (BET) surface area, richer meso- and micropores, more disordered carbon crystalline structure, and better CO{sub 2} gasification reactivitymore » than coal char. Ashes in fly ashes occurred to agglomerate into larger spherical grains, while those in coal char do not agglomerate. The minerals in fly ashes, especial alkali and alkaline-earth metals, had a catalytic effect on gasification reactivity of fly ash carbon. In the low-temperature range, the gasification process of fly ashes is mainly in chemical control, while in the high-temperature range, it is mainly in gas diffusion control, which was similar to coal char. In addition, the carbon in fly ashes was partially gasified and activated by water vapor and exhibited higher BET surface area and better gasification activity. Consequently, the fact that these carbons in fly ashes from entrained flow gasifiers are reclaimed and reused will be considered to be feasible. 15 refs., 7 figs., 5 tabs.« less
  • To obtain qualitative information regarding the operating characteristics of the two-stage entrained-flow coal gasifier, a series of cold flow tests was conducted in a scale model of the proposed prototype gasifier. Common, unreacting substances were used to simulate the flow of anticipated components in the prototype, with air representing product gas, granulated cork (between 40- and 50-mesh USS) representing both coal and char feeds, and glycerine simulating the flow of slag in the lower stage (Stage I) of the gasifier. The flow rates for these substances were determined by matching, as closely as was possible, numerical values of various dimensionlessmore » groups in the model to those expected in the prototype. Since the primary objective of the cold model was to obtain some insight into the operation of the prototype, several aspects of the flow patterns in both stages were examined, including possible problem areas concerned primarily with refractory erosion, slag drainage, and particulate agglomeration. The results of these tests, the majority of which were recorded photographically, indicated that the gas solids mixing in both stages was generally quite intense. Based upon the results, as well as the results of the previous tests, FWEC concluded that, after incorporating recommended geometry changes into the gasifier design, further tests should be conducted in a small reacting pilot plant so that more detailed information could be obtained, especially with regard to the effects of the reactions on the behavior of the flows within both the upper and lower stages.« less