Recent stream of development and utilization of coal energy

[3601-06-04] Effect of Hydrothermal Treatment Coupled with Mechanical Expression on Equilibrium Water Content of Loy Yang Lignite

○Xiang Chun Liu¹, Tsuyoshi Hirajima¹, Moriyasu Nonaka ¹, Keiko Sasaki ¹ (1. Kyushu University)

Chairman: Yuichi Sugai(Kyusyu University)

Keywords:lignite, water re-adsorption, relative humidity

Measurements of equilibrium water contents (EWCs) in samples obtained from hydrothermal treatment (HT) and HT coupled with mechanical expression (HT-ME) were undertaken across a range of relative humidities (RHs) to investigate the performance of EWC. The results showed that EWCs decreased with progressively severe HT and HT-ME conditions and EWCs of HT-ME samples were lower than those of HT samples, indicating that HT and HT-ME can upgrade lignite by reducing water loading capacity and HT-ME was better than HT. At RHs lower than 10%, the factor that controls EWC is water molecules-active sites interactions and one to two water molecules are associated with each carboxyl group. Within RH range 10–42%, monolayer water is important and ca. two multilayer water molecules are bound to each monolayer water molecule, while at RHs (42 < RH ≤ 92%) the amount of monolayer water and mesopore volume gain in significance. At high RHs (RH > 92%), EWC is determined by comprehensive factors such as macropores and cracks.