Wood pellets have become a popular option as more and more homeowners search for cost-effective and environmentally friendly heating options. These tiny, cylinder-shaped compressed wood fragments provide a sustainable substitute for conventional fossil fuels. To make sure you’re getting a dependable product, though, given the rising demand for pellets, it’s imperative to comprehend production guidelines, quality standards, and methods for evaluating their quality.
Wood shavings and compressed sawdust, typically from leftover materials from furniture manufacturing or lumber mills, are used to make wood pellets. This biomass is compressed under high pressure during the production process to produce dense pellets that burn cleanly and emit few emissions. But not all pellets are made equal, and there are a number of variables that can affect the quality.
Many organizations establish quality standards for wood pellets to make sure they fulfill particular requirements for moisture content, ash residue, and heating efficiency. These guidelines assist buyers in selecting premium pellets that will operate efficiently in their heating systems with the least amount of upkeep and environmental effect. Making an informed choice when buying pellets for your house can be aided by knowing how to verify these requirements.
Topic | All about pellets: production rules, standards and ways to check quality |
Production Rules | Use only clean, dry wood without additives. Ensure proper moisture content (below 10%). |
Standards | Look for certifications like ENplus or DINplus. These ensure quality and efficiency. |
Quality Check | Inspect pellet size, color, and consistency. Conduct ash content and calorific value tests. |
- Varieties of pellets
- Main stages of the production process
- Stage #1 – wood pulverization
- Stage #2 – drying and regrinding
- Step #3 – water treatment
- Step #4 – pressing
- Stage #5 – cooling the pellets and cleaning them from dust
- Stage #6 – filling of fuel pellets and packaging
- What standards are used to determine the quality of pellets?
- Video on the topic
- Influence of production stages on pellet quality
- Measuring the strength of pellets – fuel pellets. Lignotester. EN/ENplus certificate. Pellets grinding 😎
- Food quality assessment methods
- Checking the quality of pellets
- Pellet production 500kg/h. Pellet equipment. F-Z Ukraine. www.f-z.prom.ua
- Checking pellets for moisture. Kraslesinvest Quality Laboratory.
Varieties of pellets
The current classification divides fuel pellets into three categories:
- white pellets, which are commonly referred to as premium fuel suitable for high-tech heating boilers;
- dark or industrial pellets, slightly inferior to the first group in quality, as not only wood but also bark is used (suitable for burning in pellet boilers, but with more frequent removal of ash);
- agropellets, considered a cheap fuel of standard quality, are burned in large boilers produced by manufacturers specifically for this type of solid fuel.
Agropellets have a lower calorific value of 15 MJ/kg, whereas the calorific value of white and dark pellets is the same at 17.2 MJ/kg. Premium pellets have an ash content of 0.5%, dark pellets of 0.7% and higher, and agro pellets of 3% and higher.
The cylindrical shape and physical and geometric properties (density, abrasion resistance, bulk weight) of dry fuel pellets guarantee their bulkiness. These characteristics enable fuel to be automatically fed through unique equipment that boiler rooms use. The heating boiler’s pellet feeding automation enables long-term operation without the need for direct human intervention. This is the key to pellets’ success in the fuel market across many European nations.
Main stages of the production process
Traditionally, the process of making pellets can be divided into multiple stages:
- grinding of raw materials;
- drying of the crushed components;
- Finishing of dried particles;
- water treatment to moisten the wood flour;
- pressing chopped and moistened raw materials into pellets;
- Pellets are cooled and dusted;
- Fuel pellets filling and packaging.
Let’s take a closer look at each phase.
Stage #1 – wood pulverization
The raw materials made of wood are chopped into fractions with a thickness of 2 mm and dimensions of 25 mm in length and width by using machines known as crushers. After that, drying is applied to the ground raw material. Less energy is needed to dry the fractions the smaller they are in size.
The raw wood materials are chopped into 25 mm-long and 25 mm-wide fractions with the aid of machines known as chippers.
Stage #2 – drying and regrinding
The moisture content of the raw wood material that is sent under the press must meet certain standards. With a 2% margin of error on either side, the moisture content should be 10%. It will take longer to dry the raw material if it is too wet. The wood pieces will need to be further moistened to reach 10% of the moisture level if they are excessively dry.
There are two types of drying equipment: belt and drum. Although the latter is more costly, it is the preferred option. It is safer to use dryers with belts. Wood waste or gas can be used to run the dryers. The equipment is further divided according to the kind of drying agent that is being used, which includes flue gases, hot air, and water vapor.
Only when the size of the input raw material fraction is less than 4 mm can the press operate steadily. In addition, the dehydrated raw material is ground in chippers, hammer mills, and disintegrators.
Step #3 – water treatment
Pressing raw materials with a moisture content of less than 8% is challenging. The dried raw material must be run through the extra moistening device in order to reach the appropriate level of moisture. Screw mixers, which can be powered by steam or water, are thought to be the best option. When processing raw materials made of hardwood, steam must be used. Steam causes wood to lose some of its strength and gain more of its plasticity.
Certain manufacturers’ presses are made in a way that eliminates the need for raw materials to be steam-treated beforehand. Certain dishonest manufacturers process stale raw materials using steam. Still, it is not possible to produce high-quality pellets from "revitalized" raw materials.
Step #4 – pressing
Presses from renowned global manufacturers such as CPM, Salmatec, Andritz, Amandus Kahl, Munch, Buhler, and others are used to carry out the pelletizing process. The primary design distinction for this kind of equipment is the kind of die. Presses exist:
- with round matrix (created for use in food and chemical industry, as well as for the production of mixed fodder);
- with flat matrix (created for MSW utilization).
The presses of both modifications work on the same principle, despite their different designs. The raw material is squeezed onto the matrix by running rollers, which permits it to be forced through the holes drilled in its surface. Special knives are used to cut pressed pellets. By compressing the raw material three times, the machinery accomplishes this task.
The method of using a cylindrical matrix press to form pellets. The pellets with the same diameter are cut off after being forced out of the matrix through the holes.
The working area of the press can reach a temperature of up to 100 degrees Celsius due to friction forces in the adiabatic process caused by sharp compression of raw materials. An hour’s worth of processing one ton of raw materials uses 30 to 50 kW of electricity.
Because the equipment pelletizing wood is subjected to high loads, it is constructed of materials that are especially durable. Wear-resistant alloys that have been hardened are used to make individual parts, like dies.
Stage #5 – cooling the pellets and cleaning them from dust
The amount of work put into pressing the raw material and the temperature at which the pellets are formed determine the quality of the pellets. There is, however, a maximum "ceiling" temperature of 120°C, above which irreversible processes in the pelletized raw material start to take place and adversely impact the pellet quality.
Pellets that have been compressed require cooling, which conditions them. Prominent manufacturers’ equipment is fitted with systems to remove dust and small particles from the finished pellets. Cleaning of the pellets happens right away following the cooling process. The quality of pellet fuel is improved by this.
Stage #6 – filling of fuel pellets and packaging
Granulated fuel can be packaged and packed in a variety of ways to satisfy a wide range of customer needs. Pellets can be purchased in large quantities in free form or in bulk bags, also known as "big-bags," which can hold 500–1200 kg of pellets.
Parts of a large polymer bag (big-bag) that is used to transport pellets from the manufacturer’s warehouses to the bed consumer
Typically, fuel pellets are shipped in large quantities to CHPPs. High-quality pellets are bought for boiler heating and subsequent sale in smaller packages, though bulk shipments are also an option.
Polymer bags fitted with slings to automate the loading and unloading process are called "big-bags." Pellets maintain the necessary amount of humidity and their bulk characteristics when they are kept and transported in bags. For the average consumer, however, the cost of buying fuel pellets that have already been packaged is typically higher.
Trailers specifically designed to move large bags filled with pellets. heavily packed bags are unloaded using forklift trucks.
Packs of 10–20 kg of pellets are also well-liked by customers. Small packs of pellets are purchased by owners of pellet fireplaces and boilers without hoppers to store bulk supplies. It goes without saying that this is the priciest way to buy fuel pellets. But only specific pellets are actually realized in tiny containers.
For convenience, many customers prefer to buy certain pellets in small polyethylene bags that are portable in their own cars.
What standards are used to determine the quality of pellets?
European-accepted quality standards are used by Russian pellet producers. Foreign producers of pellet boiler fuel are granted certification that their products meet European quality standards. Customers are put off when they can’t find documentation attesting to the pellets’ quality. Simultaneously, certified products of equivalent quality come at a higher price than non-certified ones.
The EN-B and EN-plus quality standards set the specifications for industrial and household pellets based on several factors, including:
- diameter
- length;
- bulk mass;
- heat of combustion;
- moisture content;
- abrasion (percentage of dust);
- hardness;
- ash content;
- Ash melting point;
- content of metals and other chemical elements, specified in mg per kg.
A certificate EN plus must be included in the package of documents submitted by producers hoping to win a tender for the public procurement of pellet fuel.
Pellets are an eco-friendly and efficient option for home heating that has gained popularity. To guarantee that you receive a high-quality product that functions well and is safe to use, it is imperative that you comprehend the production regulations. Pellets that are produced correctly burn cleanly and release little smoke while producing steady heat.
Certifications such as ENplus or DINplus are good measures of quality when it comes to standards. These accreditations guarantee that the pellets satisfy particular requirements concerning size, moisture content, and ash content. Verifying if a product has these certifications will reassure you about its quality and help you steer clear of inferior pellets that could damage your heating system.
It is crucial to consistently verify the quality of the pellets you are using; quality control should not end at the point of purchase. You can evaluate the condition of the pellets and make sure they’re operating as they should by conducting simple tests like looking for moisture or dust. Recall that purchasing premium pellets will save you money over time by lowering maintenance expenses and increasing the effectiveness of your heating system.
Okay, so here’s a succinct and straightforward central claim for your paper:Since they provide a greener option to conventional fuels, pellets have grown in popularity as a home heating material. It’s crucial to comprehend pellet production guidelines and quality standards to guarantee safe and effective heating. This article explores the production process of pellets, the quality standards that apply to them, and how to inspect them before making a purchase. Regardless of your level of experience with pellet heating, this guide will assist you in making well-informed decisions for a comfortable and environmentally friendly home.