Notes

What influence the molding result of biomass pellets?<br>
Biomass energy has lots of application settings, such as biogas, alcohol, and biomass molding fuel. Biomass molding gas is the most practical and affordable setting. Biomass molding fuel has biomass pellets and biomass briquettes 2 forms. Biomass pellets slowly change briquettes owing to tiny dimension, high thickness, and also simple usage.



Biomass briquettes and biomass pellets

Biomass pellets are made from timber pellet equipment. It utilizes high pressure from roller as well as die to mold and mildew biomass products right into high-density solid pellets. The molding result is influenced by the resources top quality, molding process, as well as equipment efficiency. To enhance the molding results of biomass pellets, you should discover the following factors.



Raw material top quality

Raw material composition

The raw products for making timber pellets are made up of various components. They have various responses in high warm and also high pressure. Some contents like healthy proteins as well as lignin will soften as well as have gluing impact. Some components like cellulose as well as not natural particles are tough to break down or split. They hinder the molding of timber pellets, yet they takes up one of the most part of biomass products



The composition of raw materials has the biggest influence on the pellet sturdiness. The following chart shows the Pellet High quality Coefficient (PQF) of a number of usual resources



The bigger the PQF, the tighter the timber pellets are bound. Some products like bentonite, lignin have high PQF. They can work as binders. Some materials like acid oil has low PQF, the particles inside can not bind together effectively. Loose biomass pellets has much less resilience. Just when the total PQF of all products add up to more than 4.7, the wood pellets can materialize effectively.



The excellence of basic materials.

Resources with smaller sized granularity have larger area, so they are very easy to bind. And also the created pellets are more portable and also smooth, hard to break. The smaller sized the granulates, the higher the timber pellet toughness. However also tiny granulates calls for high energy usage for pulverizing. It is not recommend to go after too small granulates.



The granulates need to be uniform in size. Too large granulates are not easy to bind with others, and also the surface often tend to be rough. Large fragments usually create radiant crack, where the timber pellets are very easy to damage. Also large granulates are difficult to get involved in the die holes. https://richimachine.seesaa.net/ will exacerbate the abrasion of pellet mill die as well as roller, minimize the wood pellet production, and lower the molding rate.



As a result, the granularity of basic materials need to be 1/2 -2/ 3 of the wood pellet size. You can embrace a screener with the pore size less than 10mm in crushing procedure, to ensure that the raw materials can meet the requirement for pelletizing and blending, as well as decrease the power usage and also tools abrasion.



The moisture of basic materials.

The wetness in the biomass materials have lubrication feature. They can decrease the friction between the granulates, and also enhance their bonding. The wetness can likewise soften the products so that they are less complicated to deform as well as mold.



Biomass products varies in moisture web content, normally between 8% -15%. The dampness is influenced by temperature level. For those materials with over-high moisture, we require to dry them before making pellets.



Molding procedure

The molding temperature level

The biomass molding is to make the natural parts of biomass soften, bond as well as changed under high temperature and also stress.



Usually, the organic matters soften at the temperature of 70 ℃ ～ 80 ℃, bond at the temperature level of 160 ℃, dissolve at the temperature of 240 ℃. With the rise temperature level, the raw materials end up being extra soften, the liquidity boosts, the resistance between resources decrease, so they are easier to mold. As gauged, the molding stress in high temperature is half of that in high temperature.



Heat is not constantly excellent. Over-high temperature will trigger carbonization of the biomass materials. Such carbonization is neither consistent neither controlled, which will certainly hinder molding as well as impact the timber pellet top quality.



The thickness of product layer

In pellet machines, there is a clearance between the roller as well as die, where the biomass materials create a layer. The clearance can be changed from 0.1 mm to 0.3 mm. To generate small-size wood pellets, the clearance is tiny, and the other way around.



The density of product layer likewise influence the power consumption of the pellet maker. When the product layer is thick, the extrusion pressure will certainly increase. With way too much resources getting into the die holes, they will be as well limited to discharge, and also cause damages to the tools. When the material layer is also slim, the extrusion pressure is small, the raw materials squeezed right into the die openings are insufficient, so the wood pellet manufacturing is reduced.



The picture listed below shows the influence of resources on the extrusion pressure. B refers to suitable density, A describes the layer is as well thick, C refers to the layer is also thin. In the A condition, the extrusion force raise a whole lot owing to the long pressing location. In the C status, the extrusion pressure is also small. So a suitable density is a premise of high-efficient manufacturing.



Devices performance

Extrusion rate

Extrusion speed identifies the moment that basic materials are in the die holes, so as to influence the molding top quality. When the raw products leave in the die holes for short time, the system power consumption is low, yet the timber pellets may be loose. When pellet press die leave in the die holes for long, the wood pellets will have higher density as well as quality, the unit power consumption likewise enhance.



If the raw materials leave in the die holes for also long, the rubbing will certainly be too high, the pellets will be also dense, the pellet equipment will certainly be warm and also stop.



The extrusion speed of a pellet maker is influenced by the roller diameter as well as revolving speed. A correct extrusion rate guarantee the equipment work constantly with low power intake.



Extrusion strength

The pressing stress on the raw products establishes the thickness of timber pellets. High pressure extrusion as well as friction will certainly soften and also deform the raw products and bind them together.



If the extrusion toughness is insufficient, the raw products can't be molded effectively. If the extrusion stamina is expensive, it will worsen the abrasion of dies and include in cost.



The criteria of die hole


The parameters of die openings are restricted by resources granularity, extrusion rate, squeezing out toughness. Oppositely, the criteria of die openings influence the molding of timber pellets.



Pellet mill die openings have certain compression ratio. High compression ratio raise the extrusion strength, lower the extrusion speed. They appropriate for the products with low adhesive force.



The hole access shape influence the speed of basic materials entering the die openings, as well as affect the thickness of raw materials.



The specification of die openings should be adjusted according to various products, to make sure that you can get top notch wood pellets with reduced unit power usage.

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