Wood fuel pellets. Everything about pellets: production rules, standards and quality control methods. How pellets are produced

The color of wood pellets can vary from bright white-yellow (almost white) to very, very dark, but are pellets other than white of poor quality?

In our country, the issue of "color" of wood pellets is not legally regulated due to the absence of the very concept of "pellets", and therefore any manufacturer (seller) has the right to characterize his product (goods) in this regard as he pleases. And none of the foreign standards, including such as German DINplus, Swedish SS 187120, Swiss SN 166000, English The British BioGen Code of Practice for biofuel (pellets), have explicit requirements for the "color" of pellets.

In fact, high-quality pellets differ from low-quality ones primarily in their calorific value and the presence of impurities.

By default, pellets are produced without the use of any chemical additives, which ensures their environmental friendliness. Figuratively speaking, these are the same firewood, but transformed into a form convenient for transportation, storage and use. The composition of the combustible substance is the same for both wood pellets and firewood, in addition, both contain water and non-combustible components. The fundamental difference between pellets and ordinary firewood, in addition to the already mentioned form, lies in the ratio of the listed components (wood fiber, water, ash, etc.). At the same time, a natural component of wood, lignin, acts as a connecting component in pellets, which, in the course of the technological process, when certain temperature and pressure indicators are reached, "sticks" wood particles together, which makes it possible to produce granules of a given shape.

If the temperature, pressure and humidity during pellet molding meet the technological requirements, then the pellets will have a smooth and shiny surface without significant longitudinal cracks. Such a surface indicates, first of all, that the lignin "fixed" the shape of the granules properly.

Lower regulated pressure and temperature will not cause the pellets to darken - the pellets will remain white, but will not keep their shape, they will turn out to be soft and will subsequently crumble at each reloading (from the factory to the warehouse, from the warehouse to the seller, etc.), which, during - firstly, it will reduce their amount (dust cannot be used effectively), and secondly, it can significantly reduce the efficiency of the heat generator.

Too high a pelletizing temperature will cause the pellets to burn, becoming darker and no longer white. However, this will not deteriorate their quality, they will remain firm.

Thus, it is only possible to judge the quality of the granules by their color in the aspect under consideration. In addition, pellets with excellent strength and abrasion resistance, smooth and shiny in appearance, may contain non-metallic inclusions, which subsequently, due to intense slag formation during their combustion, can disrupt the normal operation of the heat generator at the consumer, up to emergency stops.

Note that the hardest pellets are obtained from hardwood, but their production requires the use of equipment of a higher class than in the manufacture of pellets from softwood.

The raw material for their production can be both industrial wood and bark, sawdust, chips and other waste from logging and wood processing. It is the type of raw material used that determines the color of the final product.

Dark-colored pellets can be made from waste obtained, for example, from the disposal of old wooden structures, while in terms of such a parameter as ash content, such pellets may well meet stringent Western European standards.

The use of bark-containing logging waste (sawing, etc.) for the production of pellets, always containing mineral inclusions, leads to the coloration of the pellets in the color of "cappuccino". The reasons for the appearance of mineral inclusions in pellets are different, in particular, sand can get stuck in the bark of a tree when it is transported by dragging to logging or when waste from logging and woodworking is taken directly from the ground.

In certification laboratories, they usually do not separate the reasons for the appearance of ash and slag, but write in the conclusions: "Ash content". However, slag, in contrast to ash, which partially escapes into the pipe, accumulates in the burner of the heat generator and can render it inoperative. Ash is a mineral product obtained by burning stem and other wood. It is no more than 1% of the stem wood mass and no more than 3% of the bark mass. Thus, even in the case of making pellets from a mixture of sawdust containing 85% of stem wood sawdust and 15% of pure bark sawdust, the total ash content of the produced pellets will not exceed 0.5%, which corresponds to Western European standards. These pellets can be distinguished by brown inclusions, although the color, as already noted, can also indicate an incorrect setting of the pellet press (the pellets burn).

Raw materials from secondary processing of wood (manufacturing of furniture, windows, etc.) are cleaner (compared to raw materials from primary processing), and pellets made from it are white-yellow, however, in this case, the question arises of the presence of impurities in it. the form of artificial components and resin-containing materials used in the manufacture of furniture, and then there is no need to talk about the environmental friendliness of the product. An indirect sign of the presence of such impurities may be red scale on the grates of the boiler (heat generator) after the combustion of such pellets.

Transportation and storage conditions, in which wood pellets are not protected from the effects of the external environment (sunlight, humidity, etc.), not only worsen their properties, but also affect the color of the pellets, which becomes darker. No matter how high the quality of the produced pellets, no matter how light shade of high intensity they have, no matter how strict requirements of the standards they meet, inadequate conditions of transportation and storage will make it impossible for the manufacturer to sell his products as premium goods.

Thus, the color of the pellets, neither legally nor in fact, can serve as an unconditional indicator of their high quality, belonging to the premium segment. The magic of the set of words "white pellets are a premium product" should not influence the rational choice of the consumer, for whom the most important criteria for evaluating wood pellets should be their size, bulk density, moisture, ash content, heat of combustion, sulfur, nitrogen, chlorine content etc., as well as abrasion resistance. And the main task of the manufacturer and supplier is to ensure the stability of these parameters.

Pellets are a worthy competitor to diesel fuel, coal and firewood. These are small cylindrical pellets that are used for combustion in specialized heating boilers. This type of fuel has been successfully used in Europe for a long time. This is facilitated by environmental friendliness (this is compressed waste from woodworking and plant growing) and the ability to automate the heating process: granules are loose, which makes it possible to store them in tanks and, automatically, as needed, feed into the boiler. The diameter of the pellets used for domestic boilers is 6–8 mm; industrial boilers burn larger pellets up to 10 mm in diameter. The length can generally be from 5 to 70 mm.

How pellets are made from wood pellets

For the production of pellets, they take the most inexpensive wood that cannot be used for any other purpose. These are trimmings, chips, sawdust. This waste is sorted, cleaned of impurities, sand is sifted out, etc. Further, the powerful magnet used on the sorting belt attracts iron (eg nails). After removing foreign objects, the wood waste is sent to a hammer mill, where it is crushed to fragments of 4 mm in size. This stage is called pre-grinding. It is necessary for uniform drying of raw materials at the next stage.

The resulting sawdust is dried in a special bin to the required moisture content (8–12%). Then they are sent for re-grinding. As a result, small pieces of wood are obtained, which, after bringing to the ideal moisture content (10%), are sent to a pellet press. Here, under the influence of pressure (in some high temperature presses) the sawdust is converted into pellets. For this, the composition is passed through a matrix in which round holes are cut. The design of the press-granulator resembles a conventional meat grinder: the dough is pressed through the holes, and granules are obtained. They are cooled in a cooling column. This is how the final product is obtained - fuel pellets.

Types and raw materials used

If you classify pellets by grade, then there are three types of them:

What are they made of

Any raw material containing lignin is suitable for making pellets. The most widespread in Russia is wood raw material, moreover, conifers are used more often, despite the fact that higher quality fuel is obtained from deciduous ones. The popularity of conifers is explained by the fact that the processing of hardwood requires more complex and expensive equipment: almost all hardwoods are not very well pressed, therefore more powerful equipment is required, often it is necessary to experimentally select the processing / humidification / pressing mode, and this is time and money ... Moreover, the cost of pellets when sold on the domestic market depends slightly on the material.

What is the difference birch pellets from conifers? Birch pellets have a slightly higher heat released during combustion than coniferous ones, but the difference is small. But in the burning of birch there are no resins, which, with prolonged use of pine, settle in the chimney, which requires cleaning.

Agropellets more often made from straw. Although the heat transfer of such pellets is less than that of wood pellets, they are much cheaper. Rape straw pellets are distinguished by the highest heat transfer among agricultural pellets. Husk pellets(husk) of sunflower are excellent competitors to pellets from. They have many advantages: pellets from husk are cheaper, they have many times less ash content, and they emit more heat and the ash of the husk is environmentally friendly, which is an excellent fertilizer for agricultural crops.

Peat pellets is a waste-free, economic and ecological type of fuel. But they are used mainly in industry due to their high ash content. The use of peat granules to enhance the effect of mineral fertilizers is also widespread.

Pellets from waste paper manufactured using a different technology. Instead of drying, they are moistened and then placed in a pellet press. Due to the nature of the raw material, more costs are required for paper pelletizing.

Features of heating with pellets

In order to use pellets as fuel more efficiently, it is necessary to purchase a special boiler. work in an automated mode: fuel pellets are stored in special containers, from which they are fed with a screw to the boiler.

If you want to save money and buy gray rather than white pellets, we advise you not to buy a large batch of fuel at once: not all burners can cope with them. Purchase a bag first, test it. If the boiler is working properly, you can purchase a more solid batch. Do the same with agropellets: first test the operation of the boiler with a small amount. But besides the ash content, there may be other problems: these granules do not tolerate transportation well, so you will get a lot of waste already at this stage. So it turns out that it is advisable to heat with this fuel, even if the boiler can handle it, if the production is somewhere nearby.

Ideal pellets for boilers are white. Their composition is usually homogeneous, and the ash content is low, due to the characteristics of the raw material, the surface of such granules is dense, they crack and crumble less, and they tolerate transportation better.

Date: 12.12.2015

What it is?

Fuel pellets or pellets are fuel that is produced from wood waste and peat. Pellets look like small cylindrical pieces of compressed friable material. The first pellets were produced in 1947.

Low-quality wood and waste from its processing (for example, chips, bark and sawdust), agricultural waste - all kinds of remnants of corn, cereals, straw, even chicken droppings, as well as peat are used as raw materials.

How fuel pellets are made

First, the raw material is sent to a crusher, where it is crushed into dust. After that, the dust is thoroughly dried and transferred to a pellet press, where it is pressed by heating and release of sticky lingin into cylindrical granules familiar to everyone.

About 2.6 cubic meters of all kinds of wood waste is used for 1 ton of pellets.

Granulation finished products are packed in different packages, from small packages up to 20 kg to industrial packages weighing about a ton. Part of the pellets is delivered to customers in bulk.

Advantages

Ecological cleanliness.
Ash content within 3%.
Use of waste wood - wood waste that would otherwise lie idle, rot or burn.
Less susceptibility to spontaneous combustion compared to other fuels.
Less allergenicity to humans.
High calorific value compared to wood due to its density and dryness.
The possibility of automating the processes of supplying fuel to the boiler due to the small size of the pellets, their high density and regular shape.

disadvantages

Wood waste actively absorbs harmful substances and toxins from the atmosphere. If pellets are made from "poisoned" wood, when burned, they will actively spread poison into the environment.
Low humidity, which means increased production costs due to the need to organize proper drying. Some industries do without this, using initially dry shavings as raw materials.
The need to buy a pellet boiler for optimum efficiency.

Pellet quality standards

In Russia, standards for the production of granules are regulated by GOST R 54220-2010.

The quality and appearance entirely depend on the technology used by the manufacturer and also on the raw materials. For example, pellets made from bark have a darker shade, and from plain wood - a light one, while during drying, light cylinders can burn, comparing in color to dark ones. The color has little effect on consumer properties, but burnt ones can emit dust during transportation - they rub against each other, and the ash layer is erased.

Use of pellets

Light-colored, high quality fuel pellets are used for home heating. In European countries where the use of alternative energy sources is developed, they can heat up to 2/3 of the premises.

Dark pellets are more commonly used for heat generation in industrial plants. If "residential" pellets are more often sold in bags of 20 or more kilograms, then "industrial" ones are brought in bulk from 2-3 thousand tons.

Raw pellets are also used as cat litter. They absorb moisture well and retain unpleasant odors.

Production and development prospects of fuel pellets in Russia

In 2008, about 600 tons of pellets were produced on the territory of our country at 150 enterprises in different regions. In 2009, about 960 tons of pellets were already produced, most of which were exported.

In modern Europe, they have been looking for a replacement for petroleum fuels for a long time. Alternative energies are not an easy search for something new to increase the sales of large corporations. This is a necessity dictated by time and circumstances. The rapidly growing prices for energy resources constantly make the countries of the European Union dependent. The development of such a material was required, capable of replacing coal and fuel oil, diesel fuel and gas.

The task is to use natural raw materials to obtain a special type of fuel that is well stored, easily and quickly transported. And most importantly, due to its physical properties, it is possible to use automatic feeding into combustion boilers. This modern type of fuel has become fuel pellets - pellets (from English pellets). In fact, these granules are already well and for a long time used in industry, but the relevance of their widespread use until now has not been.

Fuel pellets have been produced since 1947. These were granules of a certain size, usually their diameter is from four to ten millimeters, and the length is from one to five centimeters. They consist of waste from wood production, agriculture and as a processing of independent plant raw materials. Industrial boilers and home heating systems are the main consumers of pellet fuel.

The raw materials for their production are environmentally friendly products, namely, agricultural and woodworking waste. Due to the good combustible properties of these materials, and the constant need for their disposal, the industry received its main impetus for development.

What wastes are produced from

Several types of waste are used for the production of pellets:

wood sawdust, shavings, wood chips and wood of unsatisfactory quality;
husk of sunflower seeds, buckwheat, nut peels;
peat;
chicken droppings.

Wood pellets come in different colors, depending on the type of wood and the composition of the impurities added during manufacture.

There are several types of wood pellets.

Industrial pellets used for combustion in large industrial boilers, heating systems in cities, shopping centers, remote industrial sites. These granules are mostly dark.

Household - light granules, used in home heating appliances.

Granules from natural raw materials - vegetable granules, are used for industrial equipment, due to the increased ash content. The heat transfer of pellets from agricultural waste is slightly lower.

The widest range of applications is for peat pellets. In addition to industrial boilers, these pellets are used:

as a material for storing vegetables;
for plant nutrition;
as an absorbent material;
instead of thermal insulation material;
as artificial soil.

Poultry manure pellets are most commonly used for local boiler plants, for heating poultry farms and factories. The granules themselves are a wonderful natural fertilizer.

Manufacturing process

The process of making wood pellets is quite laborious, but almost completely automated.

The first stage of production. Raw materials are crushed, achieving a homogeneous mass in the form of particles from two to four millimeters in diameter.

At the second stage of production, the whole mass is sent to drying. Here, in specially designed drums, moisture is reduced from fifty to twelve percent.

The third stage of production is granulation. The entire mass of raw materials is fed into a hopper, in which steam is added to equalize moisture. The total humidity is now eighteen percent. Then, using special metal presses - rollers, the raw mass is directed through a metal mesh, with holes corresponding to the required dimensions, like a "meat grinder", ready-made granules come out of these holes. The pressure inside the "meat grinder" is about 50 MPa, which heats the raw material, which is already warm after drying, up to 100 degrees Celsius.

At this pressure, lignin begins to release from the chips. This substance will be the basis for bonding the granules. Excess moisture, in the process of extrusion, is removed from the rollers using special grooves.

After the main transformation, the finished granules are sent for repeated drying and cooling. Here they take on the desired strength and appearance. They are now ready to pack.

Pellets are packed both in Big Bag for large industrial farms and in plastic bags of 10–20 kilograms for private households.

Granule categories

Fuel pellets are divided into 4 main grades, they can be determined by their appearance. All varieties differ in color.

The first grade is a light beige color, almost white, indicating that fuel pellets are made of wood pellets with high heat transfer. Light granules give almost five and a half kilowatts. The ash content of wood pellets is the lowest and amounts to half a percent.

The second grade is beige to dark beige, depending on the impurities added to the raw material. The bark of trees, straw, cereal husks do not affect heat transfer, but increase the ash content up to one and a half percent.

The third grade is gray to dark gray, almost black in color, made from agricultural waste, the amount of ash after using plant pellets is two to three percent. This requires more frequent cleaning of the boilers, respectively, the price of such pellets is lower and the range of use is much narrower.

The fourth grade is black. Fuel pellets of this class are made from peat. It is least used as a fuel because there are a large number of alternative applications. And the heat transfer rates are slightly less than five kilowatts, and the ash content gives the highest values among all grades. This includes pellets from chicken manure.

Homemade pellet making

Complex processes for producing fuel pellets can suggest that the process of making pellets on your own is extremely expensive. How much will the kit cost approximately? And is it possible to set up production with your own hands?

To make fuel pellets at home, you will need:

chopper;
granulator;
drying chamber.

It is difficult to make fuel pellets on an industrial scale. But it is quite possible to provide small volumes.

Chopper purpose

First, you need to make a choice, what kind of raw materials will be the mass for the manufacture of pellets. In the case of using plant materials, it is necessary to purchase a shredder. Its price varies from 10 thousand rubles to 15. At this stage, you can make a good raw material mass. But if the basis is wood waste, then the shredder is, in principle, not needed.

Using a granulator

There are many varieties and types of this appliance. The pelletizing technology at home will require machines that are capable of delivering from 100 to 150 kilograms of finished pellets per hour. Their cost is from 20 to 30 thousand rubles. Making such a machine yourself is not difficult, especially if you are friends with metalworking and welding equipment, and also own the necessary tools for bending and cutting metal.

According to the description, it is impossible to make screws and the metal sieve itself, to create granules. We need diagrams and specific dimensions, types of materials, the number of gears and gears. It is easier, given the low cost of the granulator, to purchase it directly from the manufacturer. In the case of rural use, the payback is just one cold winter.

Purchase of a drying chamber

The manufacturer will need a tumble dryer for the drying process. It is also better to purchase it. As a result, the amount of the entire set for making pellets at home will come out in the region of 50 thousand rubles. Quite a small amount. The main thing to remember is that it is profitable to produce pellets in the case of available plant waste. In this case, space heating will be a double pleasure due to its low cost.

Comparison of pellets with other fuels

Taking heat transfer as a basis, one can understand that pellets, with a heat transfer of 5 kilowatts from each kilogram, lose a little to coal. And, of course, it outperforms ordinary firewood, with heat transfer from two to four kilowatts per kilogram. But things get interesting when price demands a comparison.

Ordinary firewood at a cost of about three rubles per kilogram is the absolute leader, and pellets are in the middle of the list. As for coal, its price of ten rubles per kilogram becomes the most unprofitable, given the average efficiency of combustion plants for these types of fuel, and the amount of ash.

Firewood leaves two percent ash, pellets one and a half, and anthracite coal up to twenty-five percent. With approximately the same cost per kilowatt of finished energy, when buying fuel and using it as the main one, pellets significantly benefit from the quality and purity of energy.

After all, the process of combustion of fuel cells releases as much carbon dioxide as the tree consumes in the process of growth. Soot pellets emit much less than wood or coal. Pellet transportation is quite simple. But if you produce pellets from waste of your own production or agricultural waste, then the cost of a kilowatt of energy decreases sharply. A kilowatt of energy can cost three times less than regular firewood.

conclusions

So what are pellets? This is a new type of biofuel, with ease of manufacture, economy and the widest possible range of applications. In some European countries already two thirds of all houses use biofuels as the main fuel for generating thermal energy.

In North America, Finland, Austria, Italy, Germany and France, the phrase pellet heat generator has long and firmly entered into everyday life. Electricity from thermal power plants is becoming more economical. Russia has rich potential in this direction. Huge reserves of forest, wide areas of fields, give impetus to the development of this industry in the coming years.

Biofuel production is growing exponentially every year. Huge waste processing plants are under construction, their estimated capacity is more than a million tons of pellets per year. Whichever grade of biofuel is chosen, consumers get clean energy.

When planning a heating system in a private house, the first and most important issue that needs to be resolved is the choice of a power source. If the main gas pipeline runs far from the house, and it is not possible to pull it because of the complexity and cost, and an electric boiler can also significantly hit the budget, the option with an alternative fuel remains. One of these is pellets.

This type of fuel in Russia is recognized as ecological, and it successfully replaces traditional firewood that needs to be prepared or coal, the delivery of the latter can also cost a pretty penny. Only natural gas can provide them with healthy competition, but as it was said, it's all about cost.

Pellets have several names: pellets, pilots and simply pressed pellets made from waste wood-based material. They have a small cylindrical shape. Abroad, this type of fuel has long been successfully used in domestic and industrial boiler houses.

And I must say that they are in demand due to the following qualities:

Environmentally friendly, thanks to the original material in production.
Economical due to the high degree of combustion.
Thermal conductivity.

In general, it is a modern type of fuel that, if necessary, can replace any of the materials existing today.

Application

Being, in fact, a means of igniting and maintaining combustion in home and industrial furnaces, they have found application in several other areas, which should be discussed in more detail.

Home stoves and fireplaces

There is nothing new in this - this is their main purpose. They are used in solid fuel boilers. They perfectly support combustion, no worse than classic coal or firewood. But in recent years, pellets have become in great demand among the happy owners of home fireplaces. Agree that it is inconvenient to keep a bundle of firewood in the room so that you can throw in a few firewood if necessary.

How much time and effort does the procurement take? And if you only use a country house on weekends, then you need to ensure their storage. In this case, a bag of pellets that fits comfortably in any pantry will come in handy.

But there are some guidelines for use here. Having decided to use them as fuel for the fireplace, you will need to replace the standard grate with a version with smaller holes so that the pellets do not fall through them. It is also recommended to adjust the air supplied to support the fire by reducing it slightly. In this case, they will burn longer and warm the room faster.

Field use

They have also come to be used frequently in this area. Lightweight and convenient picnic fuel. In order not to look for dry sticks in the forest for lighting a fire, you can use pellets before preparing dinner. One tab will burn for an hour and a half, which is quite enough to cook soup or barbecue.

Pet cleanliness

When pellets first appeared on the market, no one thought that they would find wide application in this area. Enterprising people, feeling the opportunity to earn money, began to pack them in bags with the name "Toilet filler". It began to be used as an adsorbent in cat trays, rodent cages and other animals. It must be said that the man's friends accepted this innovation with a bang. And on the net you can find a lot of positive responses on this topic.

How did he interest pet owners?

The porosity allows you to absorb not only moisture, but also reliably "lock" odors.
When used, there is no dirt and dust, everything is simple and easy to clean by flushing them down the toilet.
The ecological component and production materials give the pellets an unobtrusive smell of needles.
Safety both in relation to humans and to pets. Does not cause allergies and does not stick to paws, so it does not spread around the house.
Does not decompose, and the tray can be easily cleaned before changing.

It can be added that pellets competed well with the main types of toilet fillers, displacing them from a high line in the consumption rating.

Good absorbent

Many dealerships and just large auto repair shops purchase it for their own needs. But not as a fuel, but as a preventive measure. Not having a big difference with sawdust, pellets allow you to perfectly cope with oil stains, removing them to the slightest drop.

Pellet classification and their characteristics

At first, one of their varieties could be found on sale, and there were no distinctions.

But as they say, time does not stand still, and even such a simple material has acquired several types, classified by type of application:

Pellet white

Top grade (premium). The production uses clean wood-shaving waste without bark and resinous secretions, which allows you to leave a minimum of ash after combustion. The calorific value of this product is 17.2 MJ / kg. In production and sale on the market, they make up 95% of all products, they are used in any furnaces for heating and for household needs.

Less quality product, as indicated by its purpose. They are used only in boiler furnaces, without the possibility of using at home. The presence of non-combustible residues and tree bark in the composition affects the ash content. And if we talk about heat capacity, then it is almost the same with white pellets.

This is a standard type of fuel made from production waste and sunflower seeds, buckwheat and other combustion products. They are used in large boiler houses working on heating small villages, or in private houses, which is facilitated by a high calorific value of 15 MJ / kg. Ash content, which is 3%, and residues can clog the air ducts, therefore, when using them, periodic cleaning is recommended, and it is better to use a special boiler exclusively for heating with agricultural pellets.

Specifications

Pellets are presented in the form of small pressed cylinders of a rounded shape, with a different diameter of a maximum of 25 mm. 6-10 mm granules are in special demand. This form ensures the flowability of the fuel, making it possible to use them with any automated feeding devices in boiler rooms existing today.

Advantages and disadvantages

Speaking about quality characteristics, you need to start from the positive side, the benefit of such qualities in the material is more than negative:

Environmental friendliness. Enough has already been said about this, you can add that in the process of combustion, carbon dioxide is released from them, in an amount equal to the natural decomposition of wood. This helps to reduce the greenhouse effect, which is a global problem today.
Low ash content makes it practically waste-free material, and the remaining cinders can be used as fertilizer.
Pellets are not susceptible to spontaneous combustion therefore, the risks of fire during transportation and storage are minimal.
They are convenient for warehousing and storage, and high bulk density, allows them to be transported in large quantities.
High calorific value characterized by the fact that one ton of this fuel generates up to 3.5 thousand kWh of heat.
Waste-free production, is justified by the fact that for their manufacture, the remains of the woodworking industry are used.

They also have disadvantages that do not stand out too much against the background of positive qualities:

To use them, a specialized pellet boiler is required. It is not prohibited to work with ordinary sources, it is simply, in this way, the combustion efficiency is increased.
Despite its widespread use abroad, in Russia it is an expensive type of fuel., and purchasing a specialized boiler will cost more than buying a regular wood boiler.
By organizing heating with pellets, you will certainly be able to save on heating in the future, but for their storage, you need a dry storage room.

Pellet production

The technological process consists of several stages at which the starting material, undergoing various processing, is fed into the molding machines:

First, chips or other waste is crushed, depending on the type of pellets produced. The material is crushed to such an extent that there will be no particles in the structure exceeding 1.25 cubic meters. see Such raw materials will dry out faster and will be allowed for further action.
At the second stage, the semi-finished product is dried. Technological parameters do not allow the use in the manufacture of crumb with excess moisture content above 8-12%. Dryers are drum and belt machines used according to the type of raw material produced.
NS After drying, the raw material is subjected to another crushing stage to obtain smaller granules that are better compressed.
The material enters the press after sorting: 4 mm, granules for the manufacture of industrial pellets, and no more than 1.5-2 mm for first class raw materials.
Water treatment. This stage of technological production allows you to bring the chips to "condition". In fact, this is another drying step, in which the original product is given a nominal percentage of moisture, ideal for gluing.
Pressing produced in various devices, with a flat or cylindrical matrix. At the end of the process, the workpieces are cooled, after heating in automatic machines to 70 ° -90 ° C.
The last step is sifting, sorting and packaging of the finished product. This is necessary to separate the broken granules from the good ones.

Waste-free production means that substandard granules are re-processed.

Standards and quality

On the Russian market, it is customary to use European quality standards, which are received by foreign manufacturers. Our business for the production of pellets, it is customary to equate to these already accepted standards. The absence of permits can scare away wholesale buyers, while a certified product is an order of magnitude higher.

European standards, "EN plus and EN" require the following data in the product documents:

the length and diameter of the granules;
bulk weight;
maximum indicators of calorific value;
product moisture;
slag percentage per specific gravity;
hardness;
ash content;
maximum combustion temperature;
the content of volatile impurities and production slags;

If a manufacturer wants to establish pellets production, he must confirm the presence and premises, certified according to the EN plus class.

Combustion stages

When burning, any fuel gives out a certain percentage of heat. The same happens with pellets when they enter the combustion chamber.

The heat transfer process can be conditionally divided into three stages:

Stage one - evaporation of the liquid. This is a fleeting process. Due to the low moisture content (8-10%), for example, in dry wood, it is 30%, a high combustion efficiency is ensured.
Stage two - pyrolysis. At which about 80% of thermal energy is released from the pellets. The most important point here is to ensure the maximum flow of oxygen into the combustion chamber.
Stage three - burning charcoal. In the residues of the product, after the release of pyrolysis gas, about 20% of the thermal energy remains. To maximize the production of heat from the pellets, the oxygen supply at this time must also be maintained at the required level.

It is important at all times to maintain an optimal combustion level, controlled by the oxygen content in the furnace. An overabundance is also not recommended, in this case, most of the energy will "fly into the pipe", the lack is undesirable because the pellets will not completely burn out, providing a minimum heat flow.

Comparison with other fuels

The use of this fuel is beneficial from various points of view. And it is harmless to the environment.

For comparison, you can conduct an oral analysis:

Like other fuels, the use of wood pellets can be carried out in a fully automated mode.
High calorific value, distinguishes them against the background of ordinary chips and lump wood.
They burn almost completely, unlike wood and coal, leaving no ash that can clog the air ducts and the boiler burner.
High bulk capacity, and convenient packaging allows you to transport them in any container.
Less space is needed for storage than for the same firewood.
They are not explosive and will not ignite with any handling, this makes them stand out against the background of heavy fuel oil and liquid fuel.

Economic components:

Price stability not tied to the dollar jump.
Also, the economic component is distinguished by the fact that for long-term use, the pellets will not clog the boiler system and there is no need to spend money on the purchase of new burners or to carry out expensive cleaning of the system, as when using heavy fuel oil.

Environmental benefits:

Unlike other fuels, they can be stored in close proximity to housing, no odors and no harm to health.
The granules do not contain allergic spores, only a natural product.
Complete harmlessness to the environment.

Speaking about the amount of heat generated, in relation to other types of fuel, the following figures are obtained: a ton of granular fuel releases 5000 kW of energy during combustion.

The same amount is emitted by other materials in the following amount:

diesel fuel - 500 liters .;
fuel oil - 685 liters.;
wood - 1600 kg.;
gas - 475 cubic meters / m;

Storage

The material is transported and stored in special plastic bags. It is not forbidden to use other containers for this purpose: boxes, tanks, etc. The main thing is that the place is dry and clean. You can pack it in small portions and store it in your home pantry, adding it to the fireplace as needed.