Zhang Yuda
Abstract: This paper mainly introduces the development status of biomass pellet fuel manufacturing technology at home and abroad and the development trend of biomass pellet manufacturing technology. It focuses on the process flow and production characteristics of raw material pellet fuel produced by ring mode compression technology, and develops Prospects for the technical prospects of biomass pellet fuel manufacturing are expected to provide a reference for the development of particulate fuels.
Biomass pellet fuel is a kind of fuel product which is physically extruded by using agricultural and forestry processing residues as raw materials. It is a good substitute for fossil energy such as coal. The raw materials have wide source and low combustion pollution. The production of biomass energy particles, its production equipment is relatively simple, high production efficiency, good product quality; less investment, quick results, is the current development trend of particle manufacturing technology.
1 Development status of domestic and international biomass pellet fuel manufacturing technology
Biomass energy is an important renewable energy source. In the current world energy consumption, bioenergy accounts for 14% of the world's total energy consumption, ranking second only to oil, natural gas and coal. Many countries have developed corresponding Development research programs, such as Japan's Sunshine Program, India's Green Energy Project, and US Energy Farm, all reflect the importance of bioenergy development and utilization. Bioenergy development is mainly focused on biomass energy pellet manufacturing, which is more than other organisms. Energy is easier to achieve mass production and use [1-3]Therefore, it has received extensive attention. The development of foreign wood compression molding pellets began in the 1940s. In 1948, Japan declared the first patent for the production of rod-shaped molding fuels from wood chips. In the early 1950s, it produced goods. Single-head, multi-head screw extrusion molding machine, the Wood Forming Fuel Industry Association was established in the 1960s. In the United States, the development of biomass fuel originated from the energy shortage period in the 1970s, and the development of internal pressure drum type pellet molding Machine, and mass production in the country. Switzerland, Sweden, Western Europe and other developed countries have also developed compression molding fuel [4]And put into scale production.
The research and development of domestic biomass energy fuel started late, and the state and local governments gave important support to the development of the industry. In 1990, through the implementation of the national 'seventh five-year project's wooden rod (spiral extrusion) molding machine Development and research work, the first rod-shaped particle spiral extrusion molding production line was established in China. [5]In 1998, the Nanjing Forestry Institute of the Chinese Academy of Forestry, through the implementation of the 'Research on the production of particulate-formed fuel technology for forestry residues' project, developed a ring-formed roll-forming equipment with wood chips and shavings as the main raw materials; The unit has increased its research efforts and achieved gratifying results. Tsinghua University Clean Energy Research and Education Center develops cold-forming technology and equipment for raw material pellet fuel; National Key Laboratory of Energy Clean Utilization of Institute of Biomechanical Engineering, Zhejiang University in Biomass Forming The theory, molding fuel combustion technology and other aspects have been studied. At present, China has introduced or independently developed biomass energy production projects started construction. The Chinese government also attaches great importance to the development and utilization of bioenergy, issued in January 2006 The Renewable Energy Law clarifies the status of bioenergy in the energy structure and lays a policy foundation for the promotion and application of biomass energy pellet technology. With the introduction of relevant national support policies, it will usher in the development of biomass energy industry. .
2 Development trend of biomass pellet fuel manufacturing technology
There are various methods for manufacturing biomass pellets. According to the difference in process characteristics, it can be divided into normal temperature pressure compact molding, hot compact compact molding and carbonized dense molding. At present, the production equipment used in the field of biomass pellet fuel manufacturing mainly exists at home and abroad. Screw extrusion equipment, piston stamping equipment, roll mold rolling equipment. Roll mold compression molding equipment includes ring compression molding equipment and flat mold compression molding equipment.
The research and development of biomass and biomass residues in agriculture and forestry are the results of research and development in recent years. [6]The compression molding of ring mold in normal temperature forming has become the mainstream of the production of material particles in the world. Compared with other molding methods, it has the following advantages: 1 high production efficiency, low energy consumption, large and medium-sized ring die compression equipment per hour. The production of finished pellets is more than 2t, the energy consumption is 56%~33% of the heat-densifying molding energy consumption; 2The raw material pretreatment requirements are low, the water content is 10%~18%, and it can be molded; 3The molding die wears little, because it is normal temperature forming, The strength and wear resistance of the molding die will not decrease, and the service life of the molding die will be longer; 4 The calorific value of the molding fuel will not change substantially, and the biomass material can be molded at room temperature without destroying the molecular structure of the raw material, without chemical reaction and any heat cracking. The role of differentiation, so the molding fuel has almost no heat loss, can maintain the stable heating value of the original material. It can be seen that biomass pellet fuel manufacturing technology is developing in the direction of efficient, energy-saving and low-cost ring compression molding.
Technical characteristics of 3 ring mode compression to produce material pellet fuel
3.1 Production process
The production process of ring-shaped compressed raw material particles consists of mixing, drying, separation, quenching and tempering, granulation system, etc. [7]Raw materials (rice husk or sawdust, etc.) are led to the material storage bin to be dried by the induced draft fan. After being stirred by the auger, the mixture is sent to the tumble dryer, and the material is baked under the action of the hot air drying furnace. Dry, the dried material is sent to the cyclone separator by the fan, and the powder is separated from the mixed gas by the separator. The separated material is lifted by the hoist to the material storage bin to be processed, and the material is tested here. Moisture content and temperature (such as material index and processing requirements are very large, by adjusting the previous process parameters to meet the requirements), and through the stirrer internal mixing rod to mix and temper with the material, the quenched and tempered material after feeding The auger enters the granulator for pressing. The pressed pellets are lifted to the cooling chamber via a hoist for cooling, and after the particles are cooled, they are screened and separated in the vibrating screen (Fig. 1).
3.2 Characteristics of production equipment
Ring die compression molding equipment: Its die is annular, and the pressure roller and the die are embedded. [8-12]After the raw material enters the ring mold, it is extruded between the pressure roller and the ring die, and is extruded from the hole diameter on the ring die. The technical features are as follows: 1 The method of compact molding at room temperature, relying on material extrusion molding The friction heat generated can soften and bond the material; 2 the moisture content of the raw material is required to be wide; 3 the production efficiency is high, the output is greatly improved, the product quality is better, the product granularity is uniform, and the density is high; Low cost; 5 small size, simple and practical design; 6 no added binder, effectively reduce production costs, products are more natural and environmentally friendly.
4 Development prospects of biomass pellet fuel manufacturing technology
Biomass energy particles are available in a wide range of raw materials. The national forestry industry produces more than 40 million mories of recyclables per year. 3Crop straw, rice husk, peanut shell, hazelnut shell, etc. up to 600 million tons per year. Provides rich and cheap raw materials for the development of biomass energy particles. [13-14]Biomass pellet fuel meets the circular economy concept of energy saving and environmental protection. Compared with traditional energy sources such as coal, biomass pellet fuel has zero carbon dioxide emissions, hydrocarbons (HC) and nitrogen oxides (NO). x), sulfur dioxide (SO 2) Low emissions, less environmental pollution, renewable and so on.
Biomass pellet products have broad market prospects and can be widely used in industrial production and residential life. The government's policy of subsidizing the use of biomass energy by power companies, the use of biomass pellet fuel by power companies is becoming a reality. Recently, the State Forestry Administration held The Biomass Energy Conference requires all localities to formulate biomass energy development plans and develop leading enterprises. Biomass particle development is bound to become a trend. In short, the development of biomass fuel pellet manufacturing technology is in line with China's industrial policy and China's national conditions, with good development. prospect.
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