水稻秸秆与木屑混合原料热压成型试验

    Hot pressing forming experiment of the rice straw and sawdust mixed material

    • 摘要: 为提高水稻秸秆原料成型燃料的质量,提出通过添加木质素含量较高的木屑原料即形成混合原料并通过试验的方法进行研究。首先进行对比试验,以成型燃料的物理性能为指标,在相同实验条件下对木屑、水稻秸秆和水稻秸秆与木屑1∶1混合的原料进行热压成型试验。对比试验的结果表明小压力下1∶1混合原料成型燃料的综合物理性能优于水稻秸秆成型燃料,证明混合原料可提高单一水稻秸秆原理成型燃料的质量。但由于木屑原料本身的结构特性使得1∶1混合原料成型燃料的抗渗水性较弱。因此为进一步提高混合原料成型燃料质量,我们利用正交试验方法研究对于混合原料成型燃料各物性指标而言最显著影响因素及最佳参数组合并通过试验加以论证。试验结果表明:针对不同性能指标,各工艺参数的影响力不一致,对于松弛密度、抗碎强度及抗压强度而言,压力对其影响较大;而对于抗渗水性而言,原料混合比影响较大。对于松弛密度,最佳成型参数(混合比、温度、压力)组合为0.5∶1,70℃、31.11 MPa,抗碎强度的成型参数最优组合为2∶1,110 ℃、31.11 MPa,抗渗水性和抗压强度的最佳成型参数组合为1.5∶1,90 ℃、31.11 MPa。

       

      Abstract: Abstract: The former result of cold pressing forming experiments for rice straw showed that the rice straw cold pellets had poor quality. We found that wood chips had a high content of lignin which can take the function of the binder in high temperature condition. To improve the quality of rice straw pellets, it was proposed to take some wood chips added to the rice straw materials which could form the mixed raw material with the research carried out through the test method. We chose raw straw material which was produced in the south area of Anhui, 2012 and wood processing plant residues - pine sawdust. The equipment of closed compressing molding experiment were design by ourselves. Firstly, pellets' physical properties (loose density, shatter resistance, compressive forces and water resistance) were chosen as judgment criteria, and contrast hot pressing forming experiments was carried out to investigate the effect of different materials(rice straw, wood chips and 1:1 blends of rice straw and wood chips) on pellets. Two hours later after experiment, physical properties were tested, and the date were analyzed by DESIGN EXPERT8.0 with the orthogonal design method of multi-index analysis-comprehensive balance. By analyzing the results of contrast tests, we find that under lower compressive forces, the comprehensive physical (loose density, shatter resistance and compressive forces properties) of 1:1 blend material pellets were better than rice straw pellets and wood chips material pellets, and the results also indicated that added wood chips in the rice straw material can indeed improve the quality of single rice straw material pellets. However, because of the structural feature of wood chips material, the 1:1 blends of rice straw and wood chips material pellets were more weaker than rice straw and wood chips materials pellets in the respects of water resistance physical property. In the actual production, one or more physical properties should be requested high based on the specified use of pellets. Therefore, to further research the effect of blends on the quality of pellets, secondly, we take mixing materials of rice straw and wood chips as research object, a set of orthogonal hot pressing forming experiment with three factors and four levels were used to investigate the effect of compressive forces, mixing ratio and temperature on mixing materials pellets. It aimed to respectively get the most significant effect factors and the reasonable combination of three parameters (compressive forces, mixing ratio and temperature) for each pellets' physical property and the result will testify by test. The orthogonal experiment results indicated that each process parameter had different impact extent to various physical properties. Indexes of loose density, shatter resistance and compressive strength were strongly correlated with compressive force, and the mixing ratio has massive effect on the index of water resistance. The reasonable parameter combination for water resistance and compressive strength: the mixing ratio was 1.5:1 and the temperature was 90℃ and compressive strength was 31.11 MPa. The reasonable parameter combination (mixing ratio,temperature and compressive forces) for loose density was 0.5:1×70℃×31.11 MPa, and for shatter resistance was 2:1×110℃×31.11 MPa. Third, in order to testified the orthogonal experiment results, each reasonable parameter combination of physical property were text contrast with the reference group. The contrast group for physical properties (loose density, shatter resistance, compressive forces and water resistance) were respectively group two, group sixteen, group eleven, group seven. Other parameters of experiment were same as much as possible. Two hours later after experiment, physical properties (loose density, shatter resistance, compressive forces and water resistance) were tested and the date were analyzed. The result showed that each estimated value of treatment group are higher than reference group value, so the orthogonal experiment results were testified. The conclusion can provide technical support for industrialized production of rice straw molding fuel.

       

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