Relationship between textural properties, fly ash carbons, and Hg capture in fly ashes derived from the combustion of anthracitic pulverized feed blends

Journal Article · Wed Aug 15 04:00:00 EDT 2007 · Energy and Fuels

DOI:https://doi.org/10.1021/ef060656z· OSTI ID:20939413

Surez-Ruiz, Isabel; Parra, Jose B ^[1]

---

1. Instituto Nacional del Carbon (CSIC), Oviedo (Spain)

In this work, the textural properties of a series of whole anthracitic-derived fly ashes sampled in eight hoppers from the electrostatic precipitators and their sized fractions (from {gt}150 to {lt}25 {mu}m) are investigated. Data from N{sub 2} adsorption isotherms at 77 K, helium density, and mercury porosimetry have contributed to establish a relationship between the Brunauer-Emmett-Teller (BET) surface areas, VTOT, porosity, carbon content (the type of fly ash carbons), and Hg retention in these fly ashes. The unburned carbons in these ashes are macroporous materials, and they are different from the carbons in fly ashes from classes C and F (the latter derived from the combustion of bituminous coals) and show different textural properties. These ashes represent the end member of the fly ash classes C and F with respect to certain textural properties. Although the BET surface area and VTOT values for the studied samples are the lowest reported, they increase with the increase in carbon content, anisotropic carbon content, and particle size of the ashes. Thus, a positive relationship between all these parameters and Hg capture by the coarser ash fractions was found. The finest fraction of carbons ({lt}25 {mu}m) represented an exception. Although it makes a significant contribution to the total carbon of the whole fly ashes and shows relatively higher surface areas and VTOT values, its Hg concentration was found to be the lowest. This suggests that the type of unburned carbons in the finest fraction and/or other adsorption mechanisms may play a role in Hg concentration. Because the textural properties of anisotropic carbons depend on their subtype and on their origin, the need for its differentiation has been evidenced. 54 refs., 8 figs., 3 tabs.

• OSTI ID: 20939413
• Journal Information: Energy and Fuels, Journal Name: Energy and Fuels Journal Issue: 4 Vol. 21; ISSN ENFUEM; ISSN 0887-0624
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
ANTHRACITE
CAPTURE
CARBON
FLY ASH
MERCURY
PARAMETRIC ANALYSIS
PULVERIZED FUELS
SURFACE AREA
TEXTURE