| Biomass pyrolysis technology is one of the effective utilization methods for biomassenergy, through which can obtaine solid char, liquid bio-oil and combustible pyrolysis gas.However there are many factors that can affect thermal cracking, not only the operatingconditions but also the biomass characteristics itself, what is more high value using ofproduct is difficult. This article embarks from the resource feasibility, select agriculturalwaste cotton stalk and four forestry waste as the research object to pyrolysis them underdifferent conditions, and also analysis the characteristics of the pyrolytic products.Analyzed the physical and chemical properties of cotton stalk by ultimate analysis,proximate analysis and thermogravimetric analysis method, the thermogravimetric processconsisted of preheating, carbonization and calcine three stages, by this way the operatingconditions range was determined for pyrolysis experiment.For four typical kinds of wooden biomass Cotinus coggygria (branches, tree trunks,leaves and bark), Mulberry, Wide jujube and Rhus typhina which obtained from YanshanMountains, first of all, conducted the thermal cracking experiment of Cotinus coggygriabranches under different pyrolysis conditions (pyrolysis temperature, heating rate, carriergas flow rate and particle size). The results showed that the pyrolysis temperature was themost significant factor for the product yields, the yield of biochar declined with the risingof the pyrolysis temperature, gas product was always rising up, the liquid product reachedto the maximum of52.04%at500℃, then the optimal operating conditions combinationwas gained; Then carried out the pyrolysis experiments of the four biomass under theoptimal operating conditions, which showed that the Cotinus coggygria branches, leavesand the Rhus typhina had the maximum yield of gas product, and the Cotinus coggygriabark, the Mulberry, Wide jujube producted the maximum char and bio-oil yields.Carried out the characteristics nanlysis of the products for the Cotinus coggygriapyrolyzed under different temperatures and the four biomass pyrolyzed under the optimalconditions. Showed that gas calorific value increased with the rise of temperature, when thetemperature was above500℃, the calorific value was up to15MJ Nm-3, which to meet therequirements of the civil gas; From the respects of yields and the characteristics of theproducts, Cotinus coggygria branches and Rhus typhina were the most suitable biomass forthe production of pyrolytic gas, and the Cotinus coggygria bark and Wide jujube were forthe production of biochar and the bio-oil.The distillation range characteristic experiment was carried out with the bio-oilprovided by Hebei Xuran Straw Energy Limited Company in Hengshui city. For the theupper light component oil and lower heavy component oil and also the mixture oil with a volume ratio1:2between heavy oil components and light oil components and theirdistillation fractions were compared with their physical and chemical properties. Resultsshowed that the bio-oil and distillation fractions contained the much higher oxygen contentbut lower carbon content than fuel such as diesel, but only parts of them contained a smallamount of nitrogen and sulfur elements, almost no pollution to the environment. GC-MSanalysis of bio-oil and distillation fractions indicated that they were kinds of complex acidmixture, contained a variety of oxygen containing compounds, such as acid, alcohol,aldehyde, ester, ketone, and phenol and their derivative etc., with the carbon atom numberbetween2-19. In addition to some combustible fractions could be refined as a fuel,extracted some chemical raw materials to use in chemical production from other fractionswas also feasible. |
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