| Bio-briquette was made from materials of meager-lean coal,willow sawdust and additive alkaline-earth metallic compounds.Then bio-briquette was carried on the thermogravimetric analysis,the pyrolysis and infrared experimental research to research influences and mechanisms of bio-briquette’s pyrolysis from alkaline-earth metals.First,bio-briquette was made from sawdust and coal removing minerals res pectively by pickling and flotation technology and alkaline-earth metallic compo unds adding by impregnation method.Then pyrolysis characteristics and dynamic behaviors of bio-briquette were studied.The results showed that bio-briquette r eflected in stages pyrolytic characters of single sawdust and coal in the process of pyrolysis,and alkaline-earth metallic compounds disappeared shoulder peak of hemicellulose formed from pyrolysis.CaH(bio-briquette with Ca(OH)2),C aC(bio-briquette with CaCO3),MgO(bio-briquette with MgO)and MgC(bi o-briquette with MgCO3)compared with NON(bio-briquette without alkalineearth metallic compounds)made respectively preliminary precipitation temperat ure of volatiles advance 31.5 ℃,27.0 ℃,20.6 ℃,11.0 ℃ and peak of maximu m weight loss rate advance 16.0 ℃、5.00 ℃、4.01 ℃,3.98 ℃.Also,it’s found t hat CaH,CaC,MgO and MgC compared with NON made respectively pyrolytic activation energy reduce 24.92 kJ/mol、14.82 kJ/mol、12.96 kJ/mol 和 17.36 kJ/mol in main reaction range between 260 ℃ and 400 ℃.Secondly,alkaline-earth metallic compounds influenced on pyrolytic product of bio-briquette.It turned out that alkaline-earth metallic compounds promoted the pyrolytic carbocoal and gas generation and reduce the liquid production rate,and facilitated formation of H2,CO,CO2,CH4 and so on from pyrolsis of bio-briquette,but magnesium-based compounds affected generation of CH4 inferiorly.Carbonate was inferior to other alkaline-earth metallic compounds in promoting pyrolytic reaction of bio-briquette,but carbonate decomposition resulted in the larger generation of CO2.Calcium-based compounds were superior to magnesium-based compounds in influencing on pyrolytic products and gas of bio-briquette.Finally,pyrolytic functional groups’ changes and mechanisms of bio-briquette were researched.The results indicated that alkaline-earth metallic compounds affected mainly oxygen containing functional groups,hydroxyl and alkaline-earth metallic junctions through carboxyl in bio-briquette.It also found that magnesium-based compounds were more stable and less prone to form metallic ions effects with polar atom in bio-briquette than calcium-based compounds,so calcium-based compounds has a more positive role in pyrolysis of bio-briquette. |
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