Effect of reaction pressure on thermal conversion characteristics of alkali metal in corn stalk ash
Corn straw was used as raw material to explore the effect of reaction pressure on the thermal conversion characteristics of alkali metals in biomass ash.Corn stalk ash was prepared at 500 ℃,and then the ash samples were placed in a pressurized tube furnace with different reaction pressures and reaction temperatures,and the prepared ash samples were analyzed by XRF and XRD.The results show that the release of inorganic minerals from ash is inhibited by reaction pressure.At 900 ℃ the ash loss rate decreases from 6.75％at 0.1 MPa to 5.93％at 1.0 MPa,which is about 12％.At 1 000℃ severe melting occurs between the ash particles,and the voids of volatile substances released into the gas phase are blocked.The mass fraction of K2O in ash at 0.1 MPa and 2.0 MPa is 13.2％and 13.6％,while the mass fraction of Cl increases from 0.61％at 0.1 MPa to 1.0％at 2.0 MPa.The results show that increasing the reaction pressure can effectively reduce the melting and agglomeration of ash at high temperature,and inhibit the decomposition or gasification of low-melting point substances in ash,and retain more K and Cl elements in ash.Combined with XRD analysis,the content of inorganic minerals such as KCl and SiO2 in the ash increases with the increase of pressure,which proves that the increase of pressure can effectively inhibit the release of KCl and convert it into silicate and retain it in the ash.
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