Yu Juan 1Yu Hongliang 2Qi Jing 2Li Qing2
(1.Liaoning Provincial Forestry Seedling Management Station, Shenyang 110036, China; 2. Liaoning Forest Management Research Institute, Dandong, Liaoning 118002, China)
Abstract: The paper uses high-frequency mechanical vibrating screen and cone calorimeter to test the performance of rice husk biomass pellets. The results show that the transportability and storage of rice husk biomass pellets are in line with biomass pellet fuel standards. The performance is close to that of raw coal, and the environmental performance is better than that of raw coal. It can fully meet the requirements as an alternative energy source, and has great potential for utilization as biomass energy.
Biomass energy is an important source of renewable energy. Biomass energy can largely supplement the shortage of conventional energy. Compared with other biomass energy technologies, biomass pellet fuel technology is easier to achieve mass production and use. The convenience of using biomass particles is comparable to that of gas, fuel, etc. The use of agricultural and forestry waste such as rice husks, wood chips, straw, etc. to produce pellet fuel is one of the economic and social benefits of biomass energy. Among the biomass pellet products, rice husk granules are an emerging product. Compared with other types of biomass granule products, rice husk granules have a wider range of raw materials, lower prices, better forming effects, and simpler production processes. Very good economic, ecological and social benefits.
At present, the research on the performance of rice husk granule products is still in the exploration stage, and it has been continuously developed with the emergence of new technologies and new instruments. As an alternative energy source, the use of biomass energy particles has become widely applicable. The important premise. In this paper, high-frequency mechanical vibrating screen and cone calorimeter are used to test the performance of rice husk biomass pellets, in order to provide basis for the development and industrial application of rice husk biomass pellet fuel technology.
1 testing materials and methods
1.1 Testing materials and instruments
Test material: rice husk biomass pellet, cylindrical, specifications: length 80mm, diameter 8mm.
Instruments: High-frequency mechanical vibrating screen (Dandong Longchang Machinery Manufacturing Co., Ltd.), cone calorimeter (UK FTT company).
1.2 Detection method
Sample preparation: Using rice husk as a raw material component, a molded product of rice husk biomass pellets was produced, and the molding quality was selected for performance test.
Use performance testing:
1 Transportation performance test: The high-frequency mechanical vibrating screen is used as a testing device for measuring the mechanical scrap rate of the granular product. The diameter of the sieve of the vibrating screen is 5 mm. 5 kg of the rice husk biomass pellet product is placed in the vibrating screen for high frequency. Vibration treatment, vibration treatment time is 2h. After the vibration treatment is finished, the quality of the remaining granular product in the vibrating screen is measured, and the mechanical scrap rate of the granular product is calculated. The specific calculation formula is as follows:
2 Storage, thermal efficiency and environmental performance testing: According to ISO5660-1. First, the rice husk biomass pellets are evenly arranged, placed in the burning test box, and the box is covered. The specifications of the specimen box are 100mm×100mm. Then, place the burning test box on the combustion table of the cone calorimeter, ignite and burn. When the combustion process is over, stop the measurement and record the test data.
2 test results and analysis
2.1 Transportation performance
As a commodity, rice husk biomass energy granules are inevitably transported. In the process of transportation, rice husk biomass granule products are subject to varying degrees of bumps and vibrations, and some particles with low bonding strength will be broken into powder. Therefore, the performance of biomass pellet products is seriously affected. The mechanical scrap fraction of pellet products is mainly determined by the bonding strength of the raw materials, so it can be used as an index to characterize the transport performance of rice husk biomass pellets. It can be known from the test data (Table 1). The mechanical scrap rate of rice husk biomass pellets is 2.5%, which fully meets the transportation performance requirements of granular products.
2.2 Storage performance
The particle storage performance of this study mainly refers to whether the rice husk biomass particles are easy to cause fire during storage and threaten the safe production. The specific performance indicators include ignition time and heat release rate.
The ignition time, also known as the ignition induction time, is the time required to detect the product from the start of ignition to the ignition. This indicator can measure the thermal stability of the product. It is found that the ignition time of the rice husk biomass particles is above 85S. Similar to most woods, thermal stability is safe.
The heat release rate is the rate at which the heat is released per unit surface area after the fuel is ignited under the set external heating radiation intensity. This indicator can be used to assess the fire safety performance of the material. The higher the peak value, in a fire, The more easily the material accelerates the propagation of the flame. Using the cone calorimeter to measure the heat release rate of the rice husk biomass particles, the heat release rate of the rice husk biomass particles is increased rapidly after being ignited, at 305S. Peak, and can be at 100kW/m 2The above higher heat release rate is maintained for a longer period of time. After detection, the effective value of the heat release rate of rice husk biomass particles is 138.9 kW / m. 2, close to most wood, in a safe range.
2.3 Thermal performance
According to the test data in Table 1, the calorific value of the rice husk biomass pellet is above 18003.2kJ/kg, while the calorific value of the raw coal is generally around 20934kJ/kg. This indicates that the calorific value of the rice husk biomass pellet is close to that of the raw coal. Fully meet the thermal efficiency requirements of alternative energy sources. In addition, the ash content ratio produced by the complete combustion of rice husk biomass pellets (<13% )远小于原煤燃烧后所产生的灰分含量比率(>25%). The effective value of the amount of carbon monoxide (CO) released during combustion is 0.02 kg / kg, which is the effective value (0.06 kg / kg) of the amount of carbon monoxide (CO) released when burning coal. This indicates that under the same combustion conditions The rice husk biomass particles are completely burned compared to the raw coal, the heat energy loss is small, and the ash content released is less.
2.4 Environmental performance
2.4.1 Soot emission performance
This study mainly uses smoke blackness (Lingeman grade) to evaluate the concentration of smoke emitted during fuel combustion. The indicator is divided into 0 (all white) to 5 six grades. Under standard conditions, Ringermann 1 degree ( Grade) has a soot concentration equivalent to 0.25 g/m 3, 4 degrees (level) equivalent to 2.3g / m 3, 5 degrees (level) is equivalent to 4 ~ 5g / m 3China's "Industrial Kiln Dust Emission Standards" (GB9078.88) stipulates that the blackness of the coal-fired kiln in urban living areas shall not exceed the Lingeman class 1, and the other areas shall not exceed 2, and the oil-fired kiln shall not exceed 1 level. It can be seen from Table 1 that the smoke blackness of rice husk biomass pellets is less than grade 1. It is in full compliance with China's regulations on soot emissions.
2.4.2 Carbon emission performance
The carbon emission performance of rice husk biomass pellet fuel mainly refers to carbon dioxide (CO 2And the release of carbon monoxide (CO) gas. Among them, the effective value of carbon monoxide emission is 0.02kg / kg, and carbon dioxide is a kind of greenhouse gas, its massive emissions have caused the world's most worrying 'greenhouse effect However, as an organic fuel, the release of carbon dioxide during combustion is inevitable, and rice husk biomass particles as an alternative energy source are not spared.
As can be seen from Table 1, carbon dioxide (CO) released during the combustion of rice husk biomass pellets 2The effective value of the amount is 1.42kg / kg. The carbon dioxide released during the burning of raw coal (CO 2The effective value of the amount is 2.6kg/kg, which is almost twice that of the mixture biomass particles. In addition, the raw coal also produces sulfur dioxide (SO) during combustion. 2), nitrogen oxides and other polluting gases, and biomass particles are completely free of these pollution problems.
3 conclusions
In this test, the detection performance of rice husk biomass pellets was tested, and the important characterization index of its performance was obtained. The utilization performance of rice husk biomass pellet products is excellent, and some indicators are better than raw coal, especially environmental performance indicators. Carbon monoxide (CO) emissions are only 0.02kg / kg, carbon dioxide (CO 2The emission is only 1.42kg/kg, which is much lower than that of raw coal. Its performance and pollution emission indicators can fully meet the requirements of alternative energy sources, which indicates that rice husk biomass energy pellet products have great utilization prospects.
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