Notes

What affect the molding impact of biomass pellets?<br>
Biomass energy has lots of application settings, such as biogas, alcohol, and also biomass molding fuel. Biomass molding fuel is one of the most hassle-free and affordable setting. Biomass molding gas has biomass pellets and also biomass briquettes 2 forms. Biomass pellets slowly replace briquettes owing to little size, high density, and also easy use.



Biomass briquettes and biomass pellets

Biomass pellets are made from timber pellet maker. It uses high pressure from roller as well as die to mold and mildew biomass products right into high-density solid pellets. The molding impact is affected by the raw material quality, molding procedure, and also tools performance. To boost the molding impacts of biomass pellets, you ought to discover the following factors.



Raw material quality

Basic material structure

The raw materials for making wood pellets are made up of different materials. They have various reactions in high heat and high pressure. Some components like healthy proteins and also lignin will certainly soften and have gluing effect. Some materials like cellulose and also not natural fragments are tough to break down or split. They prevent the molding of wood pellets, yet they uses up the most part of biomass materials



The composition of resources has the biggest impact on the pellet longevity. The following graph shows the Pellet Quality Coefficient (PQF) of a number of typical resources



The bigger the PQF, the tighter the timber pellets are bound. Some products like bentonite, lignin have high PQF. They can serve as binders. Some products like acid oil has low PQF, the particles inside can't bind together properly. Loose biomass pellets has less toughness. Only when the total PQF of all materials amount to greater than 4.7, the timber pellets can take shape successfully.



The excellence of basic materials.

Raw materials with smaller granularity have larger surface, so they are simple to bind. And the created pellets are a lot more compact and smooth, hard to damage. The smaller the granulates, the higher the wood pellet strength. However also homemade pellet press requires high energy consumption for grating. It is not recommend to pursue as well tiny granulates.



The granulates ought to be consistent in size. Also big granulates are difficult to bind with others, and also the surface tend to be rough. Large particles normally cause glowing crack, where the wood pellets are easy to break. Also huge granulates are hard to enter into the die openings. They will certainly exacerbate the abrasion of pellet mill die as well as roller, lower the timber pellet production, and lower the molding price.



As a result, the granularity of raw materials should be 1/2 -2/ 3 of the timber pellet size. You can embrace a screener with the pore diameter less than 10mm in pulverizing process, to ensure that the raw materials can satisfy the criterion for pelletizing and blending, and lower the power intake and tools abrasion.



The wetness of resources.

The dampness in the biomass materials have lubrication feature. They can minimize the rubbing between the granulates, as well as boost their bonding. The moisture can also soften the products to ensure that they are less complicated to deform and also mold and mildew.



Biomass products differs in dampness material, typically in between 8% -15%. The moisture is impacted by temperature level. For those materials with over-high dampness, we need to dry them prior to making pellets.



Molding process

The molding temperature level

The biomass molding is to make the natural parts of biomass soften, bond and also transformed under high temperature and also pressure.



Normally, the raw materials soften at the temperature level of 70 ℃ ～ 80 ℃, bond at the temperature level of 160 ℃, dissolve at the temperature of 240 ℃. With the boost temperature level, the raw products end up being a lot more soften, the liquidity enhances, the resistance in between resources decrease, so they are simpler to mold and mildew. As measured, the molding stress in heat is half of that in heat.



Heat is not constantly good. Over-high temperature level will create carbonization of the biomass products. Such carbonization is neither uniform neither controllable, which will certainly prevent molding and affect the wood pellet high quality.



The density of product layer

In pellet equipments, there is a clearance in between the roller as well as die, where the biomass products develop a layer. kahl pelletizer can be changed from 0.1 mm to 0.3 mm. To create small-size timber pellets, the clearance is small, as well as the other way around.



The density of material layer additionally influence the power consumption of the pellet device. When the product layer is thick, the extrusion stress will certainly increase. With excessive raw materials getting into the die openings, they will certainly be too limited to release, and even trigger damages to the devices. When the product layer is too thin, the extrusion pressure is little, the raw products pressed right into the die holes want, so the timber pellet production is low.



The picture listed below programs the impact of raw materials on the extrusion force. B describes suitable thickness, A refers to the layer is too thick, C refers to the layer is also thin. In the A condition, the extrusion pressure increase a great deal owing to the lengthy pressing area. In the C standing, the extrusion force is also tiny. So an appropriate density is a premise of high-efficient manufacturing.



Devices efficiency

Extrusion speed

Extrusion rate figures out the time that resources are in the die holes, so as to affect the molding quality. When the raw materials leave in the die openings for short time, the device power intake is reduced, however the timber pellets may be loose. When the raw products leave in the die holes for long, the timber pellets will have higher density and top quality, the system power consumption also raise.



If the raw materials leave in the die holes for too long, the rubbing will be too expensive, the pellets will certainly be as well dense, the pellet device will certainly be warm and also even stop.



The extrusion rate of a pellet maker is influenced by the roller diameter as well as revolving speed. An appropriate extrusion rate guarantee the equipment job continually with reduced power intake.



Extrusion stamina

The squeezing pressure on the raw materials establishes the thickness of timber pellets. High pressure extrusion as well as friction will certainly soften as well as flaw the raw products and bind them with each other.



If the extrusion stamina wants, the raw products can't be built effectively. If the extrusion strength is expensive, it will certainly exacerbate the abrasion of dies as well as contribute to cost.



The specifications of die opening


The specifications of die holes are limited by resources granularity, extrusion rate, extruding toughness. Oppositely, the parameters of die openings influence the molding of wood pellets.



Pellet mill die openings have certain compression ratio. High compression ratio raise the extrusion toughness, lower the extrusion speed. They appropriate for the materials with low glue force.



The hole entrance shape affect the speed of basic materials getting into the die openings, and influence the density of raw materials.



The specification of die openings should be changed according to various materials, to ensure that you can get top quality wood pellets with low system power usage.

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