Zhang Yuda
Abstract: In this paper, rice husk and sawdust were used as test materials to produce material pellet fuel by particle forming equipment. The effects of raw material particle size, water content and ring compression ratio on the production efficiency and quality of pellet products were determined. The optimal production process parameters of biomass pellets provide practical experience for large-scale production.
Biomass pellet fuel is made from sawdust, crop straw, rice husk, peanut shell and other agricultural and forestry residues. It is physically compressed into a rod-like, granular and solid molded product to replace fossil energy such as coal. Renewable energy products. It not only has the advantages of good combustion performance, high thermal efficiency, no pollution, but also convenient storage and transportation. In the face of crisis of fossil energy, renewable biomass energy has received extensive attention from all countries. Currently, biomass The pellet fuel market has broad prospects, and the demand for fuels in countries such as South Korea and Japan is rising. [1]In China, the amount of raw materials that can be used for biomass energy production is high and the price is low, which provides raw material guarantee for large-scale production, and is also an effective way for farmers to increase their income.[2-3].
This study focuses on the main factors affecting the production of particulate fuel from rice husks and sawdust as raw materials and the main process parameters.
1 test materials and equipment
1.1 Materials
Sawdust selects sawdust from coniferous wood in Donggang City, Liaoning Province; rice hulls are selected from Donggang City, Liaoning Province, with a diameter of ≤7mm, un-crushed rice hulls after threshing. From the source of raw materials in this region and the economic aspects of cost Consider the mixture of rice shell and sawdust 7..3 as the experimental material.
1.2 equipment and working principle
The biomass pellet production test uses the SZLH420 granulator. This equipment uses a ring mold to rotate, and the basic structure of the pressure roller and the ring mold are embedded. [4-5]After the raw material enters the ring mold, the particles are formed by the mutual extrusion between the pressure roller and the ring die. The production process includes pulverization, screening, mixing, drying, granulation, cooling, etc.
2 test methods
2.1 Scheme and raw material selection
According to the preliminary preliminary experimental analysis, raw material moisture content, ring mode compression ratio, raw material particle size may be the main conditions affecting the formation rate and density of biomass pellet products. The pellet formation rate is the main factor determining the production efficiency, and the particle density is the influence of particle quality. The main factor is '6-8'. Therefore, in this experiment, the raw material moisture content, the ring compression ratio, and the raw material particle size were used as experimental factors to analyze the influence of each level of each variation factor on the production efficiency and quality of the particles.
Select rice hulls and sawdust with suitable moisture content and low impurity content. After drying, mix with 7..3 and carry out granule compression molding experiment.
2.2 Method
According to the experience of previous experiments, the moisture content is 18%, the ring mode compression ratio is 1..5.5, the material size is ≤7mm as the basic condition of the experiment, and the water content and the ring mode compression ratio are respectively selected 5 levels, and the raw material particle size is selected as 3 levels. Carry out the experiment. Set each level to 3 repetitions and take the average. The specific experimental design is shown in Table 1.
3 results and analysis
3.1 Effect of water content of mixed raw materials on particle density and molding rate
The compression ratio of the ring mold is 1:5.5, and the influence of the change of water content on the particle density and the molding rate when the raw material particle size is less than 7 mm (Fig. 1). It can be seen from Fig. 1 that the water content of the mixed raw material is the density and molding rate of the granular product. The influence is large, and a certain law is presented: When the water content of the raw material is 14%, the forming ratio of the raw material is low and the particle density is also the smallest; when the moisture content of the raw material reaches 18%, the peak occurs, and then the moisture content of the raw material increases. , the density and molding rate become smaller; when the moisture content of the raw material reaches 22%, the molding rate is less than 50%, and the density is also small.
3.2 Influence of ring mode compression ratio on particle product density and forming rate
The mixture with a water content of 18% and a particle size of less than 7 mm was tested to adjust the effect of the ring mode compression ratio on the particle density and molding rate (Fig. 2).
The ring mode compression ratio has a significant effect on the density and molding rate of the pellet product: when the compression ratio is 1..4.5, the molding rate and the particle density are the smallest; when the compression ratio reaches 1..5.5, the molding rate peaks and the particle density is close to the highest level; Then, as the compression ratio of the ring mold increases, the product forming rate decreases gradually, and the particle density does not change significantly.
3.3 Influence of raw material particle size on particle product density and molding rate
When the water content is 18% and the ring mode compression ratio is 1..5.5, the influence of the particle size change of the test material on the particle density and the molding rate is shown (Table 2).
It can be seen that the influence of raw material particle size on the density and molding rate of the pellet product is not obvious, and there is no obvious regularity and peak value.
4 Conclusions and discussion
Based on the above analysis, the water content and the compression ratio of the ring film have an obvious effect on the particle density and the molding rate. When the compression ratio of the ring mode is from 1..5 to 1..6.5, the moisture content of the raw material is 16% to 20%, the particle quality is better. The molding rate is also relatively high. When the ring mold compression ratio is 1..5.5, when the moisture content of the raw material reaches 18%, the pellet product has the highest molding rate and the best particle density. The rice shell and sawdust are mixed according to 7..3. The optimum experimental conditions for the production of pellets by raw material compression are: the moisture content of the raw material is 18%; the compression ratio of the ring mold is 1..5.5; considering the factors such as energy consumption, production efficiency, product cost and product quality, it is determined that rice is used in Donggang area. The shell and sawdust are mixed according to 7..3. The optimum process parameters for producing biomass pellets are: The moisture content of the raw material is controlled at 16% ~ 20%, and the compression ratio of the ring mold is determined to be 1..5.5.
references:
'1' Chang Yuhong. Sawdust, straw powder production mechanism and equipment for compressing charcoal 'J'. Forestry Industry, 1996, (2): 38-39.
'2' Chen Yongsheng, Mu Forest, Zhu Dewen, et al. Development of biomass molding fuel industry in China 'J'. Solar Energy, 2006 (4): 16-18.
'3' Jiang Jianchun, Xu Jianhua. Research on the Technology of Manufacture of Particle Forming Fuel from Forestry Residues[J'. Forest Products Chemistry and Industry, 1999, 19 (3) : 25-30.
'4' Guo Jun, Zhang Xiaojian, Guo Junbao.Study on the extrusion of biomass pellet fuel using corn stalk as raw material 'J'. Energy Engineering, 2007, (6) : 34-36.
'5' Lei Qun. Discussion on the technical problems of biomass fuel forming machine 'J'. Woodworking Machinery, 1997, (1): 35-36.
'6' Zhong Qixin, Qi Guanghai. Granulation mechanism and its influencing factors 'J'. China Feed, 1999, (14) : 11-13.
'7' Shen Shuyun, Dong Yuping. Ring Modeling Study of Biomass Particle Forming Machine 'J'. Journal of Solar Energy, 2010, 31 (1): 132-136.
'8' Meng Lingqi, Zhang Luoming, Chen Jingyun. Design of pressure roller ring die system for granulator 'J'. Development and Innovation of Mechanical and Electrical Products, 2004, (5) : 1-5.
