1. Raw material -related factors
(1) Types of raw materials
Different types of raw materials have very different compressed molding characteristics.The type of raw material will affect the quality of the molding (such as the density, strength, thermal value, etc.) of the molding, and it will also affect the output and power consumption of the molding machine.Among the agricultural and forestry waste, some plants are easily pressed into pellets after crushing, while some are more difficult.For example, the wood content of the wood itself is high, and the bonding effect can be played at 80 degrees at high temperature. The wood chips do not need to add any adhesives, and some other biomass may require different treatment methods or additives to make good shape.
(2) The granularity of raw materials
Granularity:
For the determined molding method, the granularity of the raw material should not be greater than a certain size.For example, a pellet molding fuel with a diameter of 8mm is usually required that the granularity of the raw material is not greater than 5mm.Generally speaking, raw materials with small granularity are easy to compress, and raw materials with large pellet size are difficult to compress.The smaller the pellet size of the raw material, under the same pressure and other conditions, the pellet extension rate or deformation is large, the easier it is to mold, but the too small will have too much powder and the molding pellets are short.Easy to suppress and fully release wood quality without producing a lot of powder.For example, under the forming method with a small granularity of raw materials, this control is more obvious.
Granopia uniformity:
When the raw material is uneven, especially when the morphological differences are large, the surface of the molding stick will cause cracks, and the density and strength will be reduced, and it will also affect the efficiency of the molding machine.For example, when the granularity of the raw material is large, the molding machine is efficient, the energy consumption is large, and the output is small.
3. The moisture content of raw materials
Excessive water content:
When the moisture content of raw materials is too high (such as greater than 18%), at the same molding temperature, the heat transfer speed of biomass will be reduced.Some heat will consume excess water evaporated, affecting heat transfer.The evaporating moisture easily forms high -pressure steam after vaporizing in the molding mold. When the steam pressure is stronger than the friction between the molding wall of the molding mold and the biomass, the number of biomass pellets that have been continuously squeezed in the molding pores will be continuously squeezed out.The section collapse from the molding hole, that is, the phenomenon of "artillery" occurs, and cannot be formed normally.
The water content is too low:
If the moisture content of the raw material is too low (such as less than 8%), it not only requires higher molding pressure, but also increases energy consumption during biomass drying.For granular molding fuels, the moisture content of raw materials is generally about 15% -25%; for biomass with high wood quality (such as sawdust), the forming of cone or cone long can be appropriate;Low biomass (such as corn straw, wheat straw, etc.), the forming of cone or cone long is more appropriate.
2. Equipment -related factors
(1) Ring mold pores
Different biomass fuels, their material resistance and looseness are different, they need to choose different ring mold pores.If the cycle of the ring mold is too small, the density of biomass fuel pellets will be too high, increasing the difficulty of combustion, and affecting the production efficiency; if the ring mold pore diameter is too large, the intensity of biomass pellets will be reduced, which is not conducive to storage and transportation.
(2) Compression ratio
Excessive compression ratio:
The compression ratio refers to the ratio of the length of the ring -molded hole to the diameter of the moldhole when the pellet machine suppresses the biomass fuel. The higher compression ratio can obtain higher pellet strength and closer pellet structure, but if the compression ratio is too high, it will increase the energy consumption and maintenance difficulty of equipment, and even affect the output of the pellet machine.
The compression ratio is too low:
Excessive compression ratio will cause insufficient intensity and density of biomass pellets, which affects the molding quality and use performance of the pellets.
(3) Model roller related issues
Mold holes blocking:
The blocking of the moldhole will cause the raw material to enter the granular chamber but cannot press the pellets. It needs to remove the materials in the mold hole in time.
The gap between the mold pressure roller is too large:
Excessive gap between the mold pressure roller is one of the reasons why there is a raw material into the granular chamber but cannot press the pellets. It is necessary to re -adjust the gap between the mold pressure roller.
Demonstration of mold pressure rollers:
The wear of the mold pressure roller is seriously caused by the raw material to enter the granular chamber but cannot press the pellets. The mold pressure roller needs to be replaced.
.