Qi Jing, Yu Hongliang, Lin Hai, Wang Yang, Li Yongfu
Abstract: The microscopic observation of biomass particles in rice husk by electron microscope (SEM) was used to analyze the forming mechanism of biomass particles in rice husk, including chemical and physical aspects. The research work was focused on the development of husk biomass particle fuel technology and its industrialization Application laid the foundation.
The utilization of biomass dense molding equipment and full use of agricultural and forestry wastes such as rice hulls, sawdust, straw and other production of particulate fuel, has good economic and social benefits in the biomass particle products, rice hulls particles is a new product. Compared with other kinds of biomass particle products, the raw materials of rice husk particles are more widely sourced, the price is lower, the forming effect is better, the production process is simpler, and has good economic, ecological and social benefits.
This paper reports the microscopic observation of rice husk biomass particles by scanning electron microscopy, analyzes its forming mechanism, and provides a theoretical basis for improving the production technology and product quality.
1 test materials and methods
1.1 test materials and equipment
Test material: rice husk biomass particles, cylindrical, size: length 80mm, diameter 8mm.
Instrument: Quanta200 scanning electron microscope (the United States FEI company).
1.2 test method
Specimen production: Using rice husk as a raw material component, a shaped product of rice husk biomass particles is manufactured, and the good quality of molding is selected for the electron microscope observation test.
Electron microscopy: First, the length of a cylindrical specimen with a diameter of 8 mm was cut to 8 mm, and the surface was cleaned with sandpaper. The specimens with flat surface, good molding effect and no serious defects were numbered and used as test materials. The cross section is placed upright on a stage for microscopic observation; after the fixation, the surface of the specimen is sprayed with gold; finally, the stage is placed in an electron scanning microscope for microscopic observation, and after observation, Selected electron micrographs are stored for research and analysis.
2 test results and analysis
2.1 Husk particle chemical binding analysis
From the chemical bonding point of view, Figure 1, we found that the rice husk biomass particles as raw material, the bonding between the raw materials as wood particles as tight, can clearly observe the existence of single-chip rice husk, rice husk The gap between the shells is also relatively large, and no significant buckling and deformation of the sheet-like rice hulls occurs because, on the one hand, the outer surface of the rice hull is covered with a layer of inorganic compounds of silicon and silicon (sheet-like '癞 leather 'type hemispherical protrusions), showing a mesh arrangement due to the chemical properties of silicon and its inorganic compounds is very stable, under normal conditions is difficult to react with other substances, but it also has a high hardness. Therefore In the process of compression molding of rice hull raw materials, the outer surface of the raw material is in contact with the outer surface, the outer surface and the inner surface, and the combination of cellulose and hemicellulose containing polar groups can not form chemical bonds such as hydrogen bond On the other hand, since rice is herbaceous, its content of cellulose, hemicellulose and lignin is lower than that of wood, especially lignin content is less than 50% of that of wood, whereas lignin is a natural Binder, when the temperature is 70 ~ 110 ℃, lignin can begin to soften, with a certain viscosity at 200 ~ 300 ℃ was molten, high viscosity.
2.2 Husk particle physical binding analysis
From the physical aspects of the analysis.Microscopic, because the outer surface of the raw rice husk covered with a layer of silicon, this layer of silicon with high hardness, special arrangement and three-dimensional spatial structure.
So that in the process of compression molding, when two rice husks are in contact with each other, it is difficult to form a close interaction between the molecules, and since silicon and its inorganic compounds are non-polar stabilizing substances, rice husks Therefore, the degree of binding between the rice hulls is not as close as the sawdust macroscopically, since the rice hulls used in this study have not been crushed after the threshing, they still maintain the original shape of the rice hulls, which Of the larger diameter, usually between 4 ~ 7mm, and was flaky; it is difficult to form such tight packing between the woody material as can be seen from Figure 2, the rice husk biomass particles in rice shell material Between the film and film patchwork stacked together.
The obvious delamination between raw materials of rice husk can be observed from Fig. 3. This shows that during the process of compression molding of rice husk raw materials, the main raw materials are 'bridging' and 'bridging' The way it is formed is that bulky or a certain length of raw material items come together on top of each other and are stacked one on top of the other.
The rice husk material used in this study is flaky, so we call this combination "slack" or "lamination." Due to the presence of a harder siliceous layer, the rice husk has poor plasticity, In the compression process is difficult to deformation to achieve close contact between the raw materials, there is a large gap between the raw materials, so the combination of 'patch' (see Figure 4), the friction between raw materials is limited; mechanical In terms of resistance, only the shear resistance perpendicular to the direction of the rice husks is better, and the mechanical resistance parallel to the rice husks is relatively poor. Compared with the woody biomass particles, the rice husk particles are prone to the fault phenomenon. The granular products Easy to break in. In addition, rice husk belongs to the hard short fiber biomass material, compared with the wood fiber length is shorter; in the compression molding process, does not appear that the woody raw material that the wound-like combination.
3 Conclusion
In this study, the biomass of rice husk was observed and compared by electron microscopy, and its forming mechanism and differences with wood particles were analyzed.In general, the forming mechanism of rice husk particle products includes chemical binding and physical binding Part.Firstly, due to the presence of siliceous layer, the chemical binding ability of raw material of rice husk is lower than that of wood raw material. Secondly, the physical combination between raw materials of rice husk is mainly in the form of ' In general, the use of rice husk as a raw material for the production of biomass particles is feasible, the product molding effect is better, has a broad market prospects, with good economic, ecological and social benefits.
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