Combustion Kinetic Characteristics Of Pressed Pellets Of Biomass Straw Blended With Oil Sludge

In order to realize the low energy consumption pressing of cotton and corn stalk powder and the energy utilization of oil sludge,the oil sludge is evenly mixed in the cotton and corn stalk powder in different proportions,and the pressed pellets are prepared at 50℃,10MPa.In order to compare the pressing characteristics,the pure cotton and corn powder are prepared at 50℃,80℃,100℃ and 120℃.The results showed that with the increase of temperature,the pressed pellets density was increased,and the density of cotton straw increased from 0.454 g/cm~3 to 0.582 g/cm~3,while that of corn straw increased from 0.504 g/cm~3 to 0.770 g/cm~3;this is because some cellulose,hemicellulose,lignin and other components in biomass melt,gelatinize and closely combine at a higher temperature,so that the density of pressed pellets increases.Therefore,the temperature plays a role in increasing the density of cotton straw pressed particles.However,the shape of pressed pellets can`t be maintained at low temperature.After adding oil sludge,cotton and corn stalk powder can be shaped at 50℃.Although the density is slightly smaller than that at high temperature,it can maintain the shape for a long time.When 5%oil sludge was added to cotton straw powder,the density of pressed pellets increased to 0.519 g/cm~3.When the proportion of oil sludge was increased to 20%,the density of pressed pellets decreased slightly to 0.508 g/cm~3.When5%oil sludge was added to corn straw powder,the density of pressed pellets decreased to 0.479 g/cm~3,when the adding proportion of oil sludge increased to 20%,the value of density of the pressed pellets increased to 0.639 g/cm~3.This shows that the density characteristics of sludge are different when it is added to different biomass powders.The thermo balance analysis and the weight loss experiment of large particles combustion were carried out for the pressed pellets,and the double logarithm method of isothermal thermal analysis was used for dynamic analysis.The results show that under low temperature,adding oil sludge can reduce the pressed pellets evaporation and combustion speed,vice versa.The activation energy of combustion reaction of cotton and corn stalk powder at 120℃ was 75.12 k J/mol and 53.72 k J/mol,respectively.The activation energy of combustion reaction of cotton and corn stalk powder decreased to 34.46 k J/mol and 37.58 k J/mol when the proportion of oil sludge was 20%.In order to obtain the effect of temperature on the pyrolysis characteristics of corn stalk pressed pellets,the pyrolysis experiments were carried out at 700℃,800℃,900℃ and 1000℃.The experimental results show that when the corn stalk powder pellets are pyrolyzed at 700℃,there is an obvious inflection point in the weight loss curve of the pressed pellets at about 150 s,the weight loss at the inflection point is about70%,and the part after 150s is mainly coke combustion.When the temperature increases to 800℃,900℃ and 1000℃,the time corresponding to the inflexion point of combustion loss decreases to about 60 s.Therefore,with the increase of temperature,the pyrolysis speed of pressed pellets is advanced,and the time required is reduced.