Chemical Equilibrium Analysis Of Hydrogen Production From Biomass And Coal Gasification In Supercritical Water

Hydrogen is a clean energy with no pollutant and high energy value. Specially, When hydrogen is used in a fuel cell, it has the advantage of high efficiency and environment friendly. Biomass is the fourth of consumed energy in China. Biomass is a renewable resource, applying biomass as energy can lead to a zero CO₂ emission in a very short life cycle period since carbon in the form of CO₂ and energy are fixed by photosynthesis during biomass growth. Coal plays a big role in Chinese energy. But it brings serious environment pollute and environment damage. Thus converting coal and biomass into hydrogen increases the energy efficiency decrease the air pollutant and has dual function on energy and environment protection.Methanol, cellulose, straw and coal/CMC have been researched in this paper, and a method that is combined with theory and experiment validated is used based on minimum free energy. The influence of temperature, pressure and feedstock concentration upon gasification efficiency, cold gasification efficiency and higher heating value has been systematically studied. It is showed that: (1) The hydrogen yield are strongly affected by temperature, and different material has different temperature scope that favors hydrogen production. (2) In supercritical temperature scope as we concerned, the pressure has no great effect on the product gas composition. (3) The mole fraction of hydrogen drops and carbon dioxide increase with increasing feedstock concentration, methanol mole fraction drops slightly. The mole fraction of carbon monoxide and other hydrocarbon (the number of carbon atom>2) is almost constant. (4) The higher heating value decreases as the temperature increases and increases as the concentration increases. The cold efficiency and gasification efficiency are opposed to the former.The key factors that affected the whole gasification process have been obtained in this paper. The basic thermodynamic rule of converting biomass and coal into hydrogen-rich gas is revealed. This paper can be used to the design, optimize, and improve of hydrogen production from biomass and coal gasification in supercritical water.