Inhibition of Sodium Release from Zhundong Coal via the Addition of Mineral Additives: Online Combustion Measurement with Laser-Induced Breakdown Spectroscopy (LIBS)

Abstract

Zhundong coal represents a large portion of China’s future energy supply, because of the large reserve capacity. Although Zhungdong coal has low ash and good ignition characteristics, it also contains large amounts of sodium, which can foul and corrode heat-transfer surfaces. For economically viable use of Zhundong coal or other high-alkali coals, the alkali release must be mitigated prior to or within the burner. This can be done either by washing the coal, using sorbents to trap the sodium, or a combination of these methods. Additive influence on the release of sodium over the entire coal combustion process was measured using a calibrated laser-induced breakdown spectroscopy (LIBS) technique. The additives used were alumina, silica, and five mineral sorbents comprising blends of silica, alumina, and various other inorganic compounds; different coal/sorbent ratios were assessed (1%, 3%, and 5% additive, by weight). During the three stages of sample coal combustion, it was found that the first stage, devo...