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Biomass Pellet Mill

Biomass Pellet Mill

APPLICATION: Biomass Fuel Industry

The production of energy by means of biomass has shown a clear trend towards the use of pellets due to their homogeneous size, which facilitates handling and feeding while also reducing costs associated with storage and transportation. The pellet quality depends on the properties of the feedstock and on the operative variables of the densification process. Quality parameters can be modified by adapting the process to the raw material to be pelletized. According to our experience in industries of biomass, we have designed MZLH biomass pellet mill, which can be used efficiently to produce pellets of different raw biomass materials, which enables our customers get maximum benefits from it.

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Biomass Pellet Mill

Applications Of Biomass Pellet Mill

The Biomass Pellet Mill is mainly a kind of mechanical equipment that uses wood crop straw as raw material, which is crushed, pressurized, densified, shaped, and extruded into small rod-shaped solid pellet fuel. The volume after molding is 1/30 ~ 40 of the volume of the raw material, the specific gravity is 10 ~ 15 times (the density is 0.8 ~ 1.4), the calorific value can reach 3400 ~ 6000 kcal, and it is a high-volatile solid fuel.

Raw materials for RICHI biomass pellet machine:

Biomass raw materials for bio pellets can be categorized into forestry, agriculture and waste‐based materials, and they can be subdivided into primary sources (directly produced materials) or secondary sources (derived from other processes). There has been a considerable amount of publications within the last years, mainly dealing with optimization of pelletization processes.

The raw materials studied range from wood species, such as pine, spruce, beech, oak, poplar, aspen, salix, and fir, to agricultural residues, such as alfalfa, barely, canola, oat, wheat, rice, soybean, rye, reed canary grass, corn stover, corn cobs, switch grass, big blue stem, sugar cane bagasse, cotton, olive residues and peanut hulls and also mixed residues.
raw marerials for bio pellet machine

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Technical Features Of Biomass Pellet Mill

1. RICHI biomass pellet mill is equipped with advanced gear-driving system with motors on this wood pellet machine, stable and reliable.

2.  RICHI adopts high-qualified components on this biomass pellet making machine, with stable performance, long service life and low noise.

3. Whole transmission parts (including motor) of this biomass pellet press machine chooses high-quality SKF bearings to ensure the transmission efficient, stable, low noise. Main motor choose Siemens.

4. This biomass pellet machine is equipped with full single layer stainless steel feeder, forced feeder, ring die and cutter.

5. Adopting international advanced technology on this biomass pelletizing machine: German gun drill and vacuum furnace heat manufacturing process in ring die making to ensure the pellets smooth and of high quality.

Working Principle Of Biomass Pellet Mill

Pellets are produced in a biomass pellet mill machine that generally consists of a die with cylindrical press channels and rollers that force the biomass to flow into and through the channels. Due to the friction between the steel surface and the biomass in the press channel, a high back pressure is built up and heat is generated. The physical forces built up in the press channel of a biomass pellet forming machine are crucial for understanding and optimizing the pelletizing process. A ring die with press channels and roller(s) are the basic parts of a biomass pellet making machine.

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Biomass Pellet Machine Specification

Model MZLH320 MZLH350 MZLH420 MZLH520 MZLH768 MZLH858
Biomass Pellet Press Power 37KW 55KW 90KW 132KW 250KW 280KW
Capacity(wood sawdust,biomass) 300-400KG/H 500-700KG/H 1.0-1.2 T/H 2.0-2.5 T/H 2.5-4 T/H 3-4.5 T/H
Capacity(grass,straw) 600-800KG/H 800-1000KG/H 1.5-2 T/H 3-4 T/H 5-7 T/H 8-10 T/H
Capacity(organic fertilizer) 1-2 T/H 3-4 T/H 5-6 T/H 7-8 T/H 9-10 T/H 10-12 T/H
Final Pellet 6-12mm 6-12mm 6-12mm 6-12mm 6-12mm 6-12mm
Weight(KG) 2500 3500 4000 4500 5000 5500
Biomass Pellet Mill Cost 10000-100000USD
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Energy content for various biomass (dry weight basis)

Pelleting plays a significant role in biomass pellet line production as the act of pelletizing breaks down plant based structures, facilitating optimal energy withdrawal while simultaneously reducing original structure size and densifying raw materials to reduce shipping and handling costs. The application of biomass pellets is increasingly widespread, but the application as fuel pellets is still dominant. Therefore, it is still necessary to discuss the raw materials of biomass pellets.

Raw material KJ/Kg (KiloJoule/Kg) Kcal/Kg (Kilo calories/Kg)
  lower calorific value higher calorific value lower calorific value higher calorific value
Softwood 17500 21100 4183 5043
Hardwood 18600 20700 4445 4947
Miscanthus/Napier grass 17800 19100 4254 4565
Switchgrass 16800 19100 4015 4565
Bamboo 19000 19800 4541 4732
Alfalfa 17030 18500 4070 4422
Lucerne 17700 19000 4230 4541
Cotton gin trash 15200 16300 3633 3896
Cotton stalks 17000 18300 4063 4374
Flax 17800 18800 4254 4493
Hemp 16500 17600 3944 4206
Jute stick 17800 19400 4254 4637
Grass 17000 18100 4063 4326
Hay 16200 18300 3872 4374
Corn stalks/stover 16800 18500 4015 4422
Sugar cane bagasse 17700 19400 4230 4637
Wheat straw 15000 18900 3585 4517
Rice straw 13500 14800 3227 3537
Rice husk 14200 15400 3394 3681
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Complete Biomass Pellet Produciton Line Process Flow

Wood and agricultural biomass pellets boost the potential as bio-fuels toward power production in tertiary and residential sectors. The production of pellets, however, is a multi-stage process where the supply-processing phases and the overall energy input strongly depend on the characteristics of the input biomass.

Generally speaking, just using a biomass pelletizer cannot support efficient biomass pellet processing, and equipment such as good quality biomass sawdust hammer mill, high efficiency wood chips, high drying efficiency biomass rotary dryer, biomass pellet cooler machine, pellet screening machine, biomass pellet bagging machine, etc., sre also required.

Complete biomass pellet manufacturing process: (Related post: how to build complete biomass pellet plant)

biomass pellet manufacturing process

Biomass materials supply

This section includes the collection, transport, and storage of biomass to the collection point; green wood is mechanically removed, and pruning residues are air-dried.

Biomass pre-treatments section

This section includes the mechanical processes such as converting wood into wood chips (except when starting from sawdust), the removal of ferrous material, drying, milling, and conditioning. The wood chips are typically dried in heaters fed with conventional fuel, although sometimes the heaters use wood chips as fuel. The most common driers use rotating drums with flow of air, in which the wet biomass does not stick to the drum surfaces and over-heating is minimized.

If the biomass can withstand contact with the combustion products, the simplest and cheapest system is a direct-heating wood drier, in which the wet biomass is in contact with hot combustion gases. Alternatively, the wet biomass can be dried using hot air. The dried biomass is further milled to obtain wood chips with average length of 3 mm and to homogenize the end product.

The most common biomass material hammer mills use rotating hammers, and the material is shifted through the machine using compressed air. Sometimes, the secondary milling is bypassed by a simple tilted-plane mechanical size selector. The pre-conditioning involves exposure of the biomass to an appropriate mix of environmental conditions (temperature, moisture, length of exposure time) to optimize its behavior in the subsequent pelleting.

A common pre-conditioning process exposes the biomass to rapid heating using hot water vapor, with the effect of softening the wood chips and obtaining a partial decomposition of starch and cellulose in simpler sugars, which allow easier compacting. The short time of exposure to hot vapor minimizes significant increases in the moisture content of the biomass.

Additives aimed at improving biomass quality and extrusion behavior can be added to the raw materials during this section.

Pelletizing section

This section involves the physical production of the biomass pellet by applying mechanical pressure on the biomass through a suitable holed plate, to obtain pellets with diameters in the 2–12 mm range and heights in the 12–18 mm range. The main technical parameters of the biomass pellet making machine are as follows: canal geometry, number and speed of pressurizing drums, ratio between diameter and length of canals, and distance between drum and holed plate. The devices may use a vertical cylindrical holed drum or a plane plate.

Post-Treatments section

These sections include cooling, screening (selection of pellet size), collection, and storage in silos or sacks for subsequent sale. The cooling section is critical for the stabilization of the product, since, during the biomass pelletizing section, the pellets reach comparatively high temperatures (90–95℃) and are typically obtained via forced exposure to air at room temperature. Pellets with a non-standard size are mechanically removed to minimize development of dust in the storage areas.

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Mixing and conditioning needed before pelletizing by biomass pellet machine?

Not all raw materials require mixing. Nevertheless, if necessary, mixers are used after the raw material has been milled and dried to: get a more consistent material blend to be fed into the biomass pellet mill machine when the raw material for biomass pellets presents significant changes in moisture percentage, binding properties or material density; produce a homogeneous mixture of raw materials in the case of pellets made up of different raw materials.

Once the biomass making raw material has been mixed and its consistency is high enough, it may require the addition of other constituents able to increase the productivity of the pellet mill and enhance the final properties of the biomass pellets produced.
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Additives play a major role in wood pellet characteristics. They are a subject of major interest: as binding agents for the biomass raw material, they serve to improve pellet durability and physical quality, reduce the dust, improve pelleting efficiency and reduce energy costs.

A maximum content of 2% of additives is permitted in woody pellets. No limitation exists for the non-woody pellets, though it is required to indicate the type and quantity used. To produce wood pellets with desired physical and thermal characteristics, the additive should be suited to the right biomass material. The most common additives are:

Lignin is a natural, optimal binder of biomass, because it melts under the heat of the pellet mill for biomass pellets. If the lignin content of the biomass is low, it may be necessary to add other additives, however. One of the simplest binders is vegetable oil, which also aids the biomass pellet line production process by reducing the frequency of blocked dies, but the most widely used substance overall is starch.

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Common additive for biomass pellet machine pelleting process

Each additive will produce unique physical and thermal characteristics when used with different biomass materials:

Corn starch and dolomite additives are the most effective in reducing the wood pellet particle density. All types of starch (native wheat starch, oxidized corn starch, native potato starch and oxidized potato starch) increase the mechanical durability of the wood pellets, the best results for mechanical durability being obtained by adding oxidized corn starch.
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Motor and vegetable oil additives increase the calorific value minimally, while corn starch and dolomite additives reduce the calorific values of wood pellets. Wheat starch is an additive that significantly reduces ash formation, but dolomite additive increases ash formation as well as the ash melting point in wood pellet combustion. Both corn starch and dolomite additives significantly increase carbon monoxide emissions.

Many biomass wood pelletizing machines come with a built-in steam conditioning chamber. Super-heated steam, at temperatures above 100°C, is used to soften the wood before it is compacted. Steam conditioning is not necessary, but it does make the biomass raw material less abrasive to the biomass pelletizer equipment and this helps reduce the maintenance costs.

In general, the final choice of the type of biomass pellet granulator depends on the customer's raw materials and technology. What Richi Machinery has to do is to design the best biomass pellet making process design and the most durable equipment for the customers.

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Why Choose Richi

why choose richi
why choose richi
Introduction of RICHI
Strength certification

Richi Machinery is a professional manufacturing enterprise integrating scientific research and development, manufacturing, sales and service. We have developed and manufactured multifunctional pelletizers, grinders, mixers, dryers and more than ten categories and more than 30 models of complete machine products are widely used in feed, biomass, organic fertilizer, pet supplies, solid waste recycling, chemical industry, road construction and other fields. All RICHI products have passed ISO9001:2008 international quality system certification, EU CE certification and Customs Union CU-TR certification, successfully serving more than 2,000 customers in more than 100 countries and regions around the world.

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Customized Design And Business Plan

In RICHI, every equipment and every pellet production line business plant can be customized. We will formulate multiple sets of pellet production process plans for comparative analysis according to the actual needs of customers, select a reasonable plan, and realize private customization. Our services run through all aspects of on-site terrain and environment survey, production line process design, raw material testing, cost requirement analysis, project investment budget, equipment installation and commissioning.

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Customized Design And Business Plan
Customized Design And Business Plan
Customized Design And Business Plan
Customized Design And Business Plan
Quality Control
Richi Machinery

We adhere to the ISO9001 quality management system, and strictly implement international standards for product design and manufacturing processes. In terms of management systems, there are product quality accountability systems, product quality accountability systems, and safety production management systems; in terms of management tools, QC quality control management, SPC statistical process control, sampling inspection and measurement system analysis are used for quality control, to achieve effective control of the entire process of equipment production, and never let go of any quality hidden dangers that may affect customer operations.

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Delivery And Installation

RICHI has always been adhering to the spirit of craftsmanship to make every detail good, especially in the link of equipment preparation and delivery, we follow the standardized process: preparation order check-equipment factory quality inspection-packing list re-inspection-scientific packaging and transportation, ensure the safe and non-destructive delivery of equipment. According to customer needs, RICHI installation engineers will guide the construction of site infrastructure, equipment installation and commissioning and trial operation of the entire production line throughout the process. When the relevant project indicators reach the design standards, the client will carry out the project acceptance.

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Delivery And Installation
Delivery And Installation
Delivery And Installation
Delivery And Installation
Delivery And Installation
Delivery And Installation
Delivery And Installation
Delivery And Installation
After-sales And Training
After-sales And Training
Richi Machinery

We have built a team of nearly 100 technical engineers to solve a series of problems in the project from consultation, site survey, sample analysis to plan design, installation and commissioning, and maintenance. We provide comprehensive and systematic training for the technical staff of each customer to better serve the customer's project needs. After the technicians have finished their studies, RICHI will provide follow-up technical support services, and the training engineers will follow up the project use effects in the later stage to ensure the stable operation of the customer's project.

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