How to choose pellets. How to determine quality pellets, which ones are better? Poor quality pellets - why is it bad

Pellets are cylindrical sticks made from sawdust or other agro-waste. The diameter of such cylinders is usually 6-8 mm, and the length is from 5 to 70 mm. For pressing, it is not necessary to add any gluing additives to the feedstock, since the pellets are pressed under very high pressure and the natural binder - LIGNIN - is squeezed out of the fibers of the raw material. This substance sticks together the raw materials, and the pellet retains its shape. Basically, pellets are made from sawdust of coniferous wood, but there are also pellets from birch or oak. In some regions, pellets are produced from various agricultural waste - buckwheat, sunflower, straw. Such agro-pellets are much cheaper, as they have worse energy characteristics. Specific gravity pellets are larger than 1, so they sink in water. But the bulk density in the medium is 750 kg per 1 m3. When burning 1 kg of pellets, an average of 5 kW of thermal energy is released. Moisture content of pellets is 7-10%. The surface of the pellets is smooth and glossy. It is customary to call pellets made from sawdust without bark and any impurities "WHITE", and all the rest - "GREY" or industrial. Naturally WHITE pellets are always more expensive than GRAY ones.

Pellets in this moment considered the most environmentally friendly fuel. One does not emit any toxic substances. When burning pellets, exactly the same amount of CO2 is released as was absorbed during the growth of a tree or plant. Pellet boilers that use pellets provide the most efficient fuel combustion due to the efficient shape of the burner and the supply of a large amount of oxygen.

Pellet boiler

There are two types of pellet boilers - with a flare burner and boilers with a retort burner with a rigid pellet feed screw. Boilers with a flare burner are cheaper, but they are more demanding on the quality of pellet fuel - the diameter, length of the pellets must be of a certain size, which is associated with the peculiarity of feeding the pellets into the burner, and the pellets must also be "white" with a low ash content.

Pellet boilers "START" are equipped with a Polish cast-iron retort burner for volumetric combustion with secondary air supply to the combustion zone. Such a burner can work on any granular fuel - on white, gray and agro-pellets, of any diameter and length. The cast iron bowl allows you to provide ideal conditions for efficient combustion of pellets and get maximum efficiency. When burning pellets in the boiler, no smell is emitted, and the color of the smoke is almost colorless, so outwardly it does not differ from a gas boiler. Unlike a gas boiler house, such boilers can be installed at recreation centers and in residential areas.

Pellets in such a boiler are poured into a large hopper, which is enough for continuous operation for several days. The boiler automation controls the fuel supply to the burner and maintains the temperature in the heating system or in the room. You can even control such a boiler using a cell phone.

How to determine the quality of pellets and where to buy them?

Where to buy pellets and how to choose the best quality fuel for your pellet boiler. After purchasing boilers, many people are faced with this - where to buy pellets, who makes them. It is difficult and almost impossible for an inexperienced person to distinguish high-quality pellets from low-quality pellets. Have to trust in the first purchase on the seller. It is better to purchase a trial batch first. You will recognize low-quality pellets as soon as you start using them. High ash content is not the biggest trouble. It is much worse if, during the combustion of pellets, large pieces of solid slag are formed - this is sand, earth, which should not be in good pellets. The photo shows appearance the resulting slag. Slag interferes with the normal combustion of fuel, so it must be removed immediately as it forms. Usually once a day. Fuel consumption when using low-quality pellets can be several times higher!

The highest quality "white" pellets are not always white in appearance. Pellets may be brown, but are referred to as "white". During granulation, the raw material is heated and the pellet may darken a little because of this.

The easiest and most reliable way is to contact your friends, they have already checked everything and will not advise you bad. If there are no such acquaintances, then it remains only to search on the Internet. You should not trust certificates, it would be better to purchase a trial batch. Through the Internet you can find contacts of manufacturers and sellers. There are also specialized sites on pellets, woodworking - some bulletin boards. It should also be noted that not all manufacturers have websites on the Internet. Moreover, the prices of such manufacturers can be quite low.

Prices for pellets are the lowest in summer. But it is possible that there are no pellet manufacturers in your area, then look in the neighboring areas. Many manufacturers can organize deliveries themselves, or you can bring them yourself through any transport company. It is not difficult.

Quality pellets must be dry and break with a characteristic click (like a pencil), have a hard smooth outer surface, color does not matter, must not contain sand and other impurities, must be made from fresh wood (not dust) or other pure plant components (buckwheat, sunflower, straw, oats). Sunflower pellets are simply black in color and their only drawback is their high ash content. The price of such pellets is several times lower than wood pellets.

Conditions for storing pellets

Pellets are usually sold in bags from 15 to 40 kg, as well as in large bags - BIG-BAGS weighing about 700-1000 kg. You can store pellets in any room or under a canopy, always on a floor or wooden pallets. It is necessary to exclude the ingress of precipitation on bags with pellets. When moisture gets in, the pellets disintegrate and turn into the raw material from which they were produced - that is, into sawdust. Also keep in mind that pellets do not like temperature changes, and if cold, frosty pellets are brought in from the street, they can become damp due to moisture condensation. At least you should not unpack the bag immediately from the street, it must be at the same temperature as the temperature in the boiler room. Pellets do not absorb moisture from the air. Purchased pellets can be stored for many years without losing their quality.

Last update: 31-10-2015

The use of wood pellets as fuel obliges the owner of the boiler to know the parameters by which they should be selected. Understand the indicators that are indicated in the certificates of product quality.

If, when buying pellets, you ask questions about what is indicated in the certificate, then the likelihood of purchasing low-quality fuel will increase significantly.

To understand the methods for determining the quality of pellets and their physical indicators, let's get acquainted with the main indicators.

Of course, the simplest method for determining the quality is to burn a test amount of fuel. Under the same conditions, it is possible to obtain average values ​​from a number of studies, but this is by no means always possible. Therefore, it is necessary to navigate by indirect signs.

Burning pellets, like any other fuel, has its own time, which is directly related to its quality. Therefore, when buying a new batch of fuel, you need to know the approximate combustion time.

How to evaluate the quality of pellets visually

1. Pellets good quality with a shiny surface. They are dense, do not have longitudinal or transverse cracks. This is an indicator of the quality of production - maintaining the desired temperature during granulation, when lignin binds pellets well.
2. If you try the granules for a break, then they should not crumble or break. Pellets that crumble or break will also behave during transport and loading. In the mass of such fuel, the passage of air, which ensures proper combustion, will be uneven. Part of the pellets will not burn completely and will clog the ash pan. This parameter is called abrasiveness by specialists and is determined by a lignotester. The sample is pressed with a weight of 0.1 t for 1 min, and then blown with air. The more crumbs, the lower the quality. The amount of crumbs determines the dustiness of the fuel.

Granules have two standard sizes 6 and 8 mm, but according to observations, larger granules are less likely to crumble, more resistant to transportation and loading.

Visual quality analysis by color is ineffective. The color determines the raw material used and the granulation temperature. The same can be said for smell.

Dissolving pellets in water can only indicate the use in the manufacturing process of chemical components for high-quality gluing of granules.

Laboratory indicators of pellet quality

The most accurate indicators of pellets can only be determined by laboratory analysis with special professional equipment. Based on the results of the study, a certificate for products is issued, in which there are basic indicators. These indicators are summarized in a table depending on chemical and physical parameters.

Pellet standardization

Standardization of pellet production in the Russian Federation is not currently being carried out. Manufacturers often justify their specifications both on the quality of production and on the quality of the resulting product, but Western manufacturers serve as a guideline, where the market has long been formed and pellets are very popular.

There are a large number of manufacturers on the pellet boiler market. Each manufacturer dictates its own conditions for fuel in its recommendations. The fulfillment of these conditions directly depends on warranty conditions, which forces pellet manufacturers to develop such a standardization in which the fuel will be in demand among consumers.

The pellet fuel market has not yet been fully formed; not all indicators for products have become common in determining quality. This work depends largely on the consumer, who can give his comments or suggestions.

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How to evaluate the quality of pellets?

At the pellet High Quality usually shiny smooth surface, no longitudinal cracks. A shiny and smooth surface is evidence that the granulation was carried out at the right temperature.

Hard pellets are preferred, soft pellets often break into crumbs when they are loaded into the hopper, fed into the burner area. A smaller number of particles than required by the standard affects the quality of the pellets - pellets with a large number of particles crumble more easily, their quality is lower. By the amount of dust, fragments in the package, you can determine how often the pellets were reloaded, additional unloading and loading gives a larger amount of small particles, which means dust. Pellets packed in bags are less dusty when compared to pellets shipped in bulk.

Colour

Most often, pellets of white-yellow shades are made from furniture production waste, pellets with an admixture of brown are made from raw materials with bark. The color of the pellets is not an indicator of quality, it only indicates what raw materials were used, how the pelletizing and storage of the pellets was carried out.

Smell

Usually, pellets have the smell of the wood that served as the material for them, or they don’t smell at all. However, pellets that are stored for a long time are filled with the humidity of the surrounding air and absorb its odors.

Why dissolve pellets?

Pellets immersed in water quickly turn into a wet mixture. If this did not happen, then the chemical substance acted as a binding component. Rotating the glass, it is not difficult to see the concentration of heavy particles, if there are a lot of them, then there is sand or wood waste mixed in, dust from grinding equipment. This technique for detecting sand in pellets is not as accurate as burning pellets in boilers.

Usually, in a large enterprise, raw materials come from a single source; this, to some extent, acts as a guarantee of stable operation. Small industries often do not have their own source of raw materials (otherwise the production would have acquired a larger scale), raw materials are taken from nearby sawmills, and so on.

Large production volume means consistent pellet quality. For small volumes, different raw materials are used, equipment is often not converted to raw materials, in the end, this negatively affects the quality of the pellets.

What parameters should not be used to evaluate the quality of pellets:

1. Pellets of any quality are capable of sinking in water;

2. The odor does not affect the assessment, except for a foreign one, which indicates the use of synthetic binders, or improper storage.

3. Do not pay much attention to the unevenness of the edge at the break of the pellet.

Test result in laboratory conditions

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Traditional firewood, fuel briquettes, coal - all this has its advantages and disadvantages. The choice is dictated by the availability and individual performance characteristics of each type of fuel, as well as technical specifications equipment.

In this article we will talk about an alternative source of thermal energy - pellets for space heating.

Comparative characteristics

Below are the main characteristics of known types of fuel.

1. Firewood. The most common and effective type fuel. For high-quality heating of premises in firewood there should be no more than 25% humidity. If this indicator will be higher, the firewood may not flare up or will smoke heavily. Their main and, perhaps, the only drawback is the need to constantly monitor the amount of fuel in the burner. By the way, unlike pellets, the supply of which is fully automated, it is enough to pour a portion of fuel into the furnace once, and this will be enough for several days of boiler operation.

   Firewood is a relatively cheap material if you harvest it yourself. Ordering dry wood, chopped into neat segments, will cost 2-3 times more. conifers(spruce, pine) are among the most expensive, but burn out faster than others. Oak, hornbeam, maple, ash are premium options. An intermediate position in terms of price and properties is occupied by birch, alder, and aspen.

2. Coal. This type of fuel has excellent performance in terms of burning time and the amount of thermal energy released. However, the disadvantages are no less significant. In particular, after the combustion of coal, a large amount of slag remains inside the boiler, so it will have to be cleaned regularly. The second negative is the unpleasant smell that spreads throughout the room.
3. Fuel briquettes. They are nothing more than waste from the woodworking industry compressed into small blocks. Like fuel pellets, briquettes are environmentally friendly, leaving a minimum of waste. For some, the decisive factor may be that they do not require additional boiler equipment.

   It is not recommended to use cheap briquettes made from waste fiberboard, chipboard or MDF boards - they contain many harmful substances, in particular, furniture glue. It is easy to distinguish such fuel by its white color and fine-grained structure.

4. Pellets. They are produced in the same way as briquettes, only compressed into small granules. They require additional equipment of heating equipment with a special pellet burner. This will entail additional expenses, but will fully pay off in efficiency and cost-effectiveness.

The choice of the type of solid fuel for the boiler is limited only by the budget and your own ideas about efficiency.

Note that the Kupper boilers operate on all types of fuel, so here the user is not limited in his choice by anything other than the budget and his own ideas about the efficiency of a particular variety.

Please note that the boiler equipment manufactured by Teplodar is characterized by the maximum configuration among other analogues on the market. The basic package includes accessories for cleaning the boiler, a heating element block, a thermometer and a stainless steel rotary valve.

Pellets for boilers: advantages and disadvantages

The main advantages of fuel pellets include:

• efficient heat generation at more than a small consumption (1 ton of pellets gives as much heat energy as 1.5 tons of firewood or 500 m 3 of gas);
• minimum waste (ash is 1% of the initial volume of fuel);
• the rarity of cleaning the boiler (no more than 1-2 times a month);
• uniform combustion and temperature constancy;
• lack of spark;
• ease of transportation (pellets are delivered in packages);
• absence of unpleasant odors;
• environmental friendliness (only 0.03% sulfur is produced during combustion);
• ash can be used as fertilizer;
• acceptable cost of fuel;
• permits are not required to equip the boiler with a pellet burner.

Solid fuel has such an indicator as calorific value - the amount of energy obtained by burning 1 kg of material. For pellets, it is 4500-5300 kcal / kg, which is comparable to the calorific value of black coal and dry firewood.

This fuel has only one drawback: before using pellets, you will have to buy a special burner.

The use of pressed pellets sometimes requires the purchase of a new boiler, although more often you can get by with retrofitting an existing one. Pellet boilers are special devices that work only on this fuel. The devices organize a full-fledged heating circuit inside the house, and also provide the owners with hot water.

Before using pellet fuel, you will have to buy a special burner.

Selection rules

Alas, not every manufacturer delivers good quality products to the consumer. Next - about the types of fuel and how to determine the quality of the pellets in appearance.

Pellets consist of sawdust, shavings, may include straw, peat, seed shells.

Fuel standardization is poorly developed in the Russian Federation, therefore, products Low quality occurs, unfortunately, quite often.

Typically, fuel is supplied in bags (packages) from 5 to 25 kg. Well, if there is an opportunity to look inside and assess the condition of the granules. Some recommendations for fuel selection:

• the less dust, fine fraction, broken granules, the better;
• the color of quality pellets is brown or slightly lighter;
• the dark color of the fuel is a sign of a high concentration of bark, which makes combustion difficult;
• the lighter the granules, the more chemical impurities they contain.

The main criterion for classifying fuel by quality is moisture content. There are three classes:

• the first (minimum humidity, heat transfer up to 95%, high cost);
• the second (an intermediate option in terms of price and quality);
• the third (fuel is noticeably moist, smokes a lot, leaves a lot of ash, is cheap).

In terms of cost, pellets of classes I and III differ by 20-30%.

Usually pellets are supplied in bags (packages) from 5 to 25 kg. Well, if there is an opportunity to look inside and assess the condition of the granules.

Terms of storage and use

When buying a large batch of pellets, you need to take care of the place of their storage. When stored indoors, they must not be placed near open sources of fire. It is also necessary to protect the material from the worst enemy - dampness.

How to store pellets if there is no space in the house? Closed bags / packages can be folded outside under a canopy. However, this option is undesirable - when it rains, the risk of wetting the package and irreversible damage to the fuel increases.

A few words about how to properly heat a solid fuel boiler with pellets. This requires a burner, which can be bought separately and installed on the boiler in just half an hour. The operation of such a tandem is extremely simple - the user will need to fill the hopper with fresh pellets from time to time and clean out the ash. The temperature balance is controlled by the control panel.

Fuel pellets - economical, affordable, efficient solid fuel. And, although the cost of a special pellet burner is quite high, within no more than 1 year, investments in equipment are fully paid off.