Experimental Inverstigation On Sawdust Pyolysis With In Molten Alkali

The exploitation and utilization of biomass energy can effectively relieve the energy crisis and decrease the the environmental pollution.Biomass thermal chemical conversion technique is one of the hottest topics about the utilization of biomass energy,among of these techniques,pyrolysis has been paid great attentions because it can convert low-quality biomass to high-quality liquid fuel or high value-added chemical products.In biomass pyrolysis process,heat carrier selection is one of the important research topics.This article relies on the National Natural Science Foundation of China,sawdust is selected as raw material,and sodium hydroxide as heat carrier,experimental investigation on the pyrolysis of biomass have been carried out in a self-designed reactor.In this paper,different components of biomass were determined,and the macro structure characteristics of wood and straw were got by proximate and elementary analysis.During the reseach,sodium hydroxide was selected as heat carrier,a series of experimental studies on sawdust pyrolysis had been carried out in a self-designed reactor.The effects of pyrolysis temperature,feeding rate,the flow rate of carrier gas,biomass raw material and different types of inorganic salts on the pyrolysis process were investigated.The experiment results indicated that with the increased temperature,the char yield was increased,and the gas yield was decreased,the liquid yield was kept between 13%and 15%.The hydrogen content was 90.1%in the pyrolysis gas at 450℃,and the tar yield was 29.8%at 500℃.With the feeding rate increased,the hydrogen content gas was increased firstly and then was decreased,when the feeding rate was 1.03g/min,the hydrogen content was 89.7%,and the one of methane was 10.3%in pyrolysis gas.With increased flow rate of carrier gas,the bio-gas yield was increased firstly and then kept constantly.When the flow rate of carrier gas was 100L/h,the yield of hydrogen and methne were 0.52L/g and 0.06L/g respectively.The effect of biomass raw material on the composition of bio-gas was not intensive,but the effect on pyrolysis products yields was significant,the maximum pyrolysis production was different for biomass types,and they are tar,bio-gas and bio-oil for sawdust,birch and fir respectively.The addition inorganic salts into molten NaOH have a significant effect on pyrolysis production yield,the composition distributions of products,FeCl3 and CoCl2 could promote the production of bio-gas and bio-oil,and ZnCl2 could promote the formation of bio-gas;inorganic salts promoted the production of water in pyrolysis reactions,so the moisture content in bio-oil was increased under the role of inorganic salts,and the organic compounds of bio-oil components was decreased.During the pyrolysis,COx can be absored by molten alkali to produce carbonate,such as Na2CO3,in order to recycle the molten alkali and get high-value productions,the molten crystallization was adopted to separate sodium hydroxide and sodium carbonate according to their different solid flying points.The influences of stable time,depart temperature,teperature controlling way,molar content and the total quality on the separation results were studyed.The results showed that the suitable stable time was 30 minutes,and the way of dropping temperature to desirable separation temperature was in favor of improving the percentage of NaOH.The suitable separation temperature was impacted by the content of Na2C03.The quality was kept constantly when the molar content of Na2C03 was 0.25,and the appropriate separation temperature was 390℃,there was 100℃ higher than that of the molar content of Na2C03 was 0.1.The dissertation provided the reference for sawdust pyolysis with in molten alkali,and investigation on recover the molten salt,the research provided the reference for pyrolysis and separation of the pyrolysis solid products.