Material balances of major and trace elements in hydrogen production process from coal with CO2 recovery

A new hydrogen production process “HyPr-RING” (hydrogen production by reaction integrated novel gasification), in which high-pressure steam (HPS) gasifies organic materials with a CO2 sorbent (CaO) has been developed. In this study, the material balances of major elements such as sodium and magnesium, and trace elements such as arsenic, mercury and lead in coal in the HyPr-RING process at thermodynamic equilibrium were investigated using commercial simulation software package, and compared with those experimentally determined on the HPS gasification of coal with CaO at a temperature of 650 °C and calcination of the solid residue collected after gasification at 900 °C. The behaviors of sodium, magnesium and lead in the experiments were similar to those at equilibrium, whereas those of arsenic and mercury were different. Sodium and lead existed as solid-phase species after gasification, whereas they existed partly as gas-phase species after calcination. Magnesium existed as solid-phase species after gasification and calcination. After gasification, arsenic existed as gas-phase species at equilibrium, whereas solid-phase species were present in the experiments. After calcination, arsenic existed as solid-phase species at equilibrium and in the experiments. After gasification and calcination, mercury existed as gas-phase species at equilibrium, but part of the mercury remained in the solid residue collected in the experiments.