Go Greener with KMEC Biomass Pellet Mill & Pellet Plant

Main factors influencing the productivity of pellet plant (2)

3. The steam quality
Pelletizing with steam can effectively improve the production of pellet plant and the quality of pellets. Steam is the origin of the water added in the conditioning. It is also the heat source in starch gelatinization of feed. Add a certain amount of steam in the process of conditioning can not only kill part of the bacteria in the feed, but also dilute the natural binder in the feed so that a thin water-bearing layer would form in the

pellet machine

external of each particle in the material, which is good for material gelatinization and pellet forming. Steam is produced by the boiler at a given pressure (under 0.7MPa) and provided in saturated steam condition. In the process of saturated steam flowing from the boiler to the biomass pellet machine, part of energy would lose and condensed water is formed. In the system of reasonable design, the condensed water and suspended matter would be collected through the steam-distributing cylinder and steam trap before entering the conditioning device of pellet plant, then flow back to the boiler or directly discharged outside. The longer the pipeline, the more energy loss, the much condensation water would be formed, the more difficult the condensed water can be removed, which reduces the quality of steam.
 
Conditioning is the hydro-thermal treatment carried out on the feed to make the starch pasting. Protein denaturation and material softening can improve the quality and effect of pelletizing of biomass pellet mill and improve the palatability, digestion and absorption of feed. There is a complementary relationship between the conditioning temperature and moisture. Under the effect of moisture and temperature, the grain starch pellets begin to absorb water and swell in 50 ~ 60 ℃, while bean starch pellets in 55-75 ℃ until fracture to make the emulsion into viscous paste, namely starch gelatinization. The starch gelatinization temperature should be controlled at above 75 ℃, and the temperature and moisture of conditioning are mainly achieved by joining the steam.
 
The proper saturated steam pressure should be 0.2 ~ 0.4MPa. If the pressure is too low (less than 0.2MPa), it can not reach the conditioning index in a fixed conditioning time; while if the pressure is too high (more than 0.4MPa), the steam temperature would be higher, the heat conduction of steam to the material through the conditioner is strengthened obviously, which is easy to cause the material in high temperature, low moisture content and burned of part of materials, affecting the quality of pelletizing.
 
To ensure the stability of the steam pressure, in general, the pressure fluctuation amplitude should not be greater than 0. 5MPa. While the guarantee of steam pressure is inseparable with the design and the correct installation of steam piping system. Generally, the moisture content of raw material is 12% or so before conditioning. Since high steam pressure would lead to less moisture content, so materials with low moisture can be processed with steam pressure of lower and wet to achieve the pelletizing of good quality and high broken resistance. If the material has high moisture, it is better to use dry saturated steam of high pressure. While if the moisture content is higher than 16. 5% after conditioning, then the moisture content of pellet produced by the pellet plant is higher, which is not easy to keep for a long time. If the moisture is less than 15% after conditioning, the electrical consumption of pellet plant would be large with low broken resistance. Higher conditioning steam pressure is suitable for high moisture materials, since the quantity of steam material absorbed is less and the gelatinization is poor; low steam pressure is suitable for materials of low moisture content, since materials would absorb more steam with good pasting effect.

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A lot of people are not clear about how to protect the main machine of pellet plant when processing different products. When we use the pellet plant to process all kinds of biomass materials, due to the size of the materials are different, thus the sieve used in the pellet plant is different, and the load is also different...