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Title: Estimation and modeling of coal pore accessibility using small angle neutron scattering

Gas diffusion in coal is controlled by nano-structure of the pores. The interconnectivity of pores not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify pore accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical pore accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas pressure using deuterated methane (CD4) at low Q values for both coals. Pores smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the pore radius is larger than 40 nm, the pore accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of pores are accessible to CD4 for anthracite and 37% for sub-bituminous coal, where the pore radius is 16 nm. For these two coals, pore accessibility and pore radius follows a power-law relationship.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ;  [2] ;  [2] ;  [1]
  1. Pennsylvania State Univ., University Park, PA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
OSTI Identifier:
1265817
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Fuel
Additional Journal Information:
Journal Volume: 161; Journal Issue: C; Journal ID: ISSN 0016-2361
Publisher:
Elsevier
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). High Flux Isotope Reactor (HFIR)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 01 COAL, LIGNITE, AND PEAT pore accessibility; SANS; coal pore characterization; accessibility modeling