Zhu Dewen, Chen Yongsheng, Zhong Chengyi
Abstract: In view of the limitations of the original biomass pelletizer and the problems in the process of forming, a hollow to roll bio pellet forming machine was developed and designed. The structure and working principle of the pelletizer were explained. Roller biological particle molding machine core structural parameters.Experiments show that the aircraft structure and parameters of the design is reasonable to meet the special requirements of bio-particle molding.The development of this machine greatly enhance the quality of bio-particle mechanization molding and forming rate is The ideal biological particle molding machine.
0 Preface
Biomass is very rich in our country, mainly including agricultural and forestry waste, animal waste and organic waste, etc. Biomass can be processed into feed, fertilizer and fuel, and biomass energy is the fourth largest energy source next to coal, oil and natural gas , Accounting for 14% of the world's total energy consumption Biomass-forming particles have the advantages of easy storage, transportation, easy to use, hygienic, fuel efficient combustion, clean energy, environmentally friendly [1, 2]Existing biomass particle molding equipment, there are some shortcomings, granulation, the material is easy to produce high temperature, high pressure active ingredients change, low power efficiency, the need for cooling system after granulation; the same time, this granulator Complex structure, more wearing parts, maintenance difficulties, unstable working performance and short continuous working time.In order to overcome the shortcomings of the above granulator, the new type of hollow roller pair developed successfully by Nanjing Agricultural Mechanization Research Institute of the Ministry of Agriculture Biological particle molding machine, is also the first case in our country, to fill the gaps in the country.
Experiments show that the structure and parameters of the aircraft are designed reasonably and can meet the special requirements of bio-pellet molding machine. The technology and equipment research and development have promoted the development of bio-pellet molding industry in our country[3].
1 structure, working principle and main technical parameters
1.1 Structure and working principle
New hollow-roll bio-particle molding machine structure diagram, shown in Figure 1.
The molding machine is composed of a main motor, a power transmission device, a hollow roller pair, a feeding hopper, a stirring device, a discharging hopper, a vibrating screen, a vibration motor, a scraper and a rack, etc. The power transmission device mainly comprises a main motor, a belt, , Decelerator, coupling, overload protection device, gear box and main and passive transmission shaft, overload protection device is installed between the coupling and the gear box.When there are larger and harder foreign objects falling into two hollow counter-roller Between the wheels, through the role of overload protection device to interrupt the power transmission, to avoid damage to components, play a protective effect on the entire equipment. Gear box is equipped with a pair of size power transmission gear, through the transmission of large and small gear can be achieved two hollow The differential rotation of the roller to do the work.Because the two hollow on the differential rotation of the roller so that the material into the two hollow roller on the forming hole by the shear force and the friction between the two pairs of rollers and the material Joint action, so that materials are easy to overlap, enveloping and molding into the hole, which can improve the material forming rate and molding density in the two hollow on the roller system were made of multiple rows spaced from each other were Pair of through holes forming the opening shape as shown in FIG.
In the forming through-hole feed end of the smaller bell mouth, the larger bell mouth, the middle of the cylindrical shaped through-hole, made of small trumpet-shaped entrance In order to make the material easier to enter the molding through-hole molding, to prevent the material Under the action of pressure to move up to affect the material forming effect; discharge port made into a large trumpet shaped particles in order to make it easy to release material out of the middle of the diameter of the through-hole length should be based on the molding material and the size of the particle size Of the hopper in the feed inlet is equipped with a material mixing device, which on the one hand play the time and quantitative material sent to between the two pairs of hollow roller, on the other hand have to push down the material Role to reduce the material due to the role of the pressure and move up, forcing the material into the forming hole molding in the shape of the particle outlet with a shaker, vibrating screen in the vibrating motor driven by the constant vibration, forming the demolished particles fall into In the vibrating screen, the shaped particles in the upper part of the vibrating screen finally fall into the material conveying mechanism, the broken material in the lower part of the vibrating screen is collected and then reformed into the feeding hopper, and the scraper is fixed on the machine Shelf, put two hollow roller particles forming the exit, the material can be cut off after molding.
Work, the motor power through the final drive power transmission device to the two hollow on the roller, so that differential operation, at the same time crushed material into the feed hopper through the feed mixing device, an endless stream of materials to the two Hollow to the roller, and the formation of a certain downward propulsion, the material into the two pairs of hollow roller on the roller by the material and the friction between the two pairs of hollow roller to do differential operation When the shear force generated by the feed mixing device generated by the downward thrust and the two hollow on the operation of the roller during the mutual squeezing force generated by the combined action so that a steady stream of materials into the forming hole molding, Blade scraping fall into the shaker, and eventually fall into the transport mechanism to take the whole process to complete the material granulation.
1.2 The main technical parameters
Molding machine dimensions / mm: 500 × 2000 × 1760
Machine quality / kg: 2000 ~ 3000
Supporting the total power / kW: 35
Hollow to roller diameter / mm: 450
Particle size / mm: φ4 ~ φ12
Production capacity / t · h-1: 1~ 4
Particle formation rate /%:> 85
Two hollow on the roller speed / rad · min-1: 80~ 200
Forming granule average compressive strength / N: 10 ~ 50
2 structural features
2.1 A multi-purpose machine (versatility)
The machine can change the two hollow pairs of rollers, according to production requirements, the biomass can be processed into different sizes of feed, fertilizer or fuel to achieve a multi-function machine.The machine uses the principle of two pairs of rollers opposite rolling forming, work During the process, less wear and tear of work parts, stable and reliable performance, can work at room temperature in the system of pelleted feed or fertilizer, so that the original composition of the material can be maintained, and can work continuously for a long time.
2.2 transmission system structure
Transmission system is a belt drive and gear transmission joint transmission operation, the reducer, gear box and the gearbox and the input shaft between the installation of an overload protection coupling composition .General gear box gear is composed of a pair of large and small gears , Can achieve two hollow roller differential motion.When overload occurs due to various reasons, the overload protection coupling will produce fracture or separation, cut off the power transmission, to achieve the protection of the machine[4].
2.3 two hollow on the roller and its forming through-hole
Taking into account the machine dimensions, quality, productivity and material pressure angle between the two rollers and other factors, to determine the diameter of the two pairs of rollers 450mm, a width of 40 ~ 70mm. In the roller made of multiple rows Shaped through-hole, the molding through-hole is divided into 3 sections as shown in Figure 2. The feed end is small bell-shaped, the discharge end was a large bell-shaped mouth, the purpose is to facilitate the material into the forming hole forming and forming Particle release; the middle of the cylindrical shaped through-hole, forming the diameter of the through-hole and its length should be based on the size of the material forming particles.
3 test analysis
Biomass compression molding is affected by many factors, some of which are related to the biochemical characteristics of the biomass itself, and some are closely related to external compression conditions, mold types, compression methods, molding processes and the like, all of which fundamentally affect or Which restricts the bonding mode and cohesive force inside the molding, which directly causes the difference of the physical quality of the molding.For a designed particle molding machine, the kind of the raw material, the moisture content, the particle size, the temperature and the working pressure are the factors influencing the particle The main factor of forming[5, 6].
3.1 different raw material pellet forming the result analysis
The biomass raw materials for the experiment are ground corn stalks and sawdust. After drying, the moisture content is 20% -30%, the particle size of the raw materials is 2~10 mm, and the molding temperature is 140~60 ° C. The test results are shown in Table 1 Show.
Table 1 shows the test data, due to the different types of raw materials used in molding, making the molding machine production, power consumption per unit product, molding density and molding rate are different from Table 1 saw the use of sawn timber productivity , Forming density and forming rate are larger than the crop straw material, and unit energy consumption is smaller, indicating that the sawn wood material is easier to shape than the straw[7, 8].
3.2 The moisture content of raw materials and particle size of the impact of particle molding corn stalk as raw materials for testing, measured the molding machine performance indicators and the basic characteristics of the formed particles, the measured data shown in Table 2.
As can be seen from Table 2, the impact of the particle size of the raw material on the performance index of the molding machine, with the increase of the particle size of the material, the output of the molding is reduced and the power consumption is increased, which has little effect on the molding rate and the molding density of the molding particles. Output and power consumption, as well as the forming rate and forming density of the formed particles are within a certain range of moisture content of the raw material, and increase with the increase of the moisture content of the raw material. When the moisture content exceeds 30%, as the moisture content of the raw material increases, The amount is still increased, the remaining indicators are reduced.Thus, raw material forming suitable moisture content of 25% to 28%, the particle size should be between 1 ~ 6mm[9~ 11].
3.3 molding pressure and temperature on the impact of particle molding
According to the relevant experimental data, due to the different content of lignin, hemicellulose and cellulose in the molding material, the pressure and temperature required for the molding are also different.The pressure is too low and the material can not be compacted and compacted, resulting in the decrease of the molding rate of the material particles. In the production of pellet fuel, the temperature is too low, not enough to make lignin plastics, even if there is sufficient pressure can not make the material forming biomass can be decomposed and transformed into liquid, solid and partially gaseous products when heated, biomass heat Solution technology combined with compression molding process, the use of pyrolysis reaction of liquid pyrolysis oil or tar as a compression molding binder, is conducive to the material compression molding and can improve the quality and calorific value of the molding fuel, but the molding temperature is too high It will also cause serious thermal decomposition of the surface of the molding fuel, cracks, reduce the intensity, or even can not be molded, so select the appropriate pressure and temperature during molding is necessary[12].
4 Conclusion
Through the analysis of the forming machine performance index and the basic characteristics of the molded granules, the results show that the performance of the hollow roller type bio-pellet forming machine meets the requirements of the biomass pellet forming.At the same time, , Using different granulation process and parameters to meet the production requirements of the production of bio-organic fertilizer, pellet feed and pellet fuel to achieve the function of a multi-purpose machine.Experiments show that the machine has high production efficiency, stable performance and reasonable design , Novel structure, less wearing parts, and long-time continuous operation.The research and development of this machine can provide effective granulation way for biomass including straw and sawnwood and promote the effective utilization of biomass resources. Continuous development.
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