Study On Co-pyrolysis Of Shenfu Coal And Hydrolysed Sunflower Stalks

In this paper, the Shenfu 3^-1 coal and Shaanxi sunflower stalk were used to study the thermolyticreactivity in fixed bed reactor under N₂ atmosphere. Firstly, the conditions of dilute sulphuric acid and enzymatic hydrolysis of sunflower stalk were optimized. Then the synergistic effect in pyrolysis process of Shenfu coal and biomass was discussed using pyrolysis, co-pyrolysis, cascaded co-pyrolysis and selection coupling pyrolysis, and impact of sunflower stalk and its residue on Shenfu coal pyrolysis behavior was analysed.The results showed that the best sulphuric acid hydrolysis condition is that hydrolysis time was 60 minutes, solid to acid ratio was 1/30 and hydrolysis temperature was 120℃and sugar yields were 19.1%. The best enzymatic hydrolysis condition was that hydrolysis time was 12 hours, substrate concentration was 1/40, hydrolysis temperature was 55℃and enzymatic specificactivity was 700 U·g^-1 and hydrolysis rate was 53.39%.The thermolytic reactivities of sunflower stalk, sunflower stalk hydrolysis residue and Shenfu coal were compared using thermogravimetric analysis method. The results showed that Shenfu coal began pyrolysis at about 250℃and the maximum mass loss temperature was 440℃and the rate was from 30% to 45%. Sunflower stalk began pyrolysis at about 150℃and the maximum mass loss temperature was 330℃. Sunflower stalk residue began pyrolysis at about 200℃and the maximum heat loss temperature was 360℃. Mass loss rate of sunflower stalk after pyrolysis was above 90%. The initial temperature and maximum mass loss temperature of sunflower stalk residue were higher than those of sunflower stalk. The pyrolysis peak of hemicellulose was also observed at thermolysis curve of hydrolysis residue. Comparing Shenfu coal pyrolysis temperature, sunflower stalk and its residue pyrolysis temperature were lower.Pyrogenation tar harvest ratio of sunflower stalk and hydrolyzed residue showed increased trendency with pyrogenation final temperature, both of which reached max at 500℃. Compared pyrogenation production of sunflower stalk and hydrolyzed draff, tar harvest of maleic acid hydrolyzed draff was highest, and 5% more than sunflower stalk former sample. At 600℃the most production of maleic acid hydrolyzed draff and residue of enzymatic hydrolysis were H₂ and CH₄.During the process of Shenfu coal pyrogenation, tar harvest ratio enhanced apparently along with increased temperature, reached to max 13% at 650℃and half tar harvest 67%.The most quantity of CH₄ was 5.9 mL·mg^-1 at 500℃, the most quantity of H₂ was 2.9 mL·mg^-1 at 550℃.Shenfu coal and sunflower stalk hydrolyzed draff pyrogenation altogether could accelerate the production of moisture and coal gas during pyrogenation process, with little effect on pyrogenation tar harvest. When added sunflower stalk raw material, the increasedquantity of H₂ production was 2.9 mL·mg^-1 , CH₄ was 3.0 mL·mg^-1 .In the process of two-stage cascaded pyrolysis, the co-pyrolysis tar yield and high hydrocarbon component production which were got form co-pyrolysis of Shenfu coal and sulphuric acid hydrolysis were higher other hydrolysis residue. H₂ content from co-pyrolysis of Shenfu coal and maleic acid hydrolysis residue was highest. CH4 production from co-pyrolysis of Shenfu coal and maleic acid hydrolysis residue was maximum.During process of ruddle co-pyrogenation, sunflower stalk pyrogenation reached to most heat weightlessness temperature, while Shenfu coal had not yet begun pyrogenation at 350℃, when Shenfu coal accelerated production of sunflower stalk pyrogenation tar apparently, pyrogenation half tar of maleic acid hydrolyzed draff could accelerate Shenfu coal pyrogenation at 500℃. Addition of maleic acid hydrolyzed draff could improve co-pyrogenation tar ratio at 650℃.Cascaded co-pyrolysis is an effective method to achieve co-operative effects. The analysis of the mechanism shows that CO and CO₂ mainly come from the pyrolysis of lignin; and the key technology to increase co-operative effects is to improve efficient transfer of hydrogen radicals.