Consumption of pellets for heating a house 100m2, 150m2, 200m2

Pellets and briquettes are modern types of fuel that are superior to traditional firewood in terms of heat capacity and are optimally suited for boilers with automatic feed.

They can also be burned in conventional heating stoves or boilers, but this method is only effective for briquettes, and for burning with pellets you need a special device - a pellet burner .

In this article we will talk about:

• various heating methods;
• combustion of pellets and briquettes;
• features of heating with pellets and briquettes;
• boilers with automatic fuel supply;
• features of the choice of boilers for heating with briquettes and pellets.

Heating a private house with pellets: pros and cons

A solid fuel pellet boiler for a home with automatic fuel supply, like any other heating option, has both its advantages and disadvantages.
Consideration of the pros and cons helps to make the most reasonable decision regarding the advisability of equipping a boiler room with wood pellet equipment. The disadvantages are the following:

• Dependence on pellets – a few years ago, good quality pellets were difficult to obtain, which significantly affected the cost of fuel. Today, purchasing pellets of plant or wood origin is not difficult. Refilling a pellet boiler lasts for several hours, days or even months, depending on the chosen model. The user is required to calculate the operating time and purchase the necessary fuel in advance.
• High installation cost. Another disadvantage pointed out by opponents of pellet equipment is its high cost and expensive repairs. Today, the price of equipment is gradually declining due to high market saturation.

The reasons for purchasing pellet equipment are:

• Economical - fuel costs are slightly higher than for a gas boiler, but if you take into account the cost of obtaining permits, the need to prepare design documentation, and pay for gas pipeline installation, the difference becomes not so obvious. Economical pellet boilers for home use less raw materials than convection and gas-generating solid fuel units. Heating costs are also lower compared to an electric boiler.
• Simple installation requirements - the boiler is installed fairly quickly. Combined systems with an integrated fuel tank simply need to be connected to the power supply network and a chimney installed.
• Versatility - most modern models manufactured by domestic manufacturers are capable of using, in addition to pellets, firewood, coal, wood waste, and after replacing the burner, can be converted to use liquid fuel.
• Backup heat sources - an automatic pellet boiler, often has a built-in heating element for heating the coolant. If the solid fuel runs out, the boiler automatically switches to using electricity and continues to heat the house until the pellets are refilled.

Having weighed all the pros and cons of purchasing pellet equipment, many buyers come to the conclusion that it is advisable to purchase a heat generator of this type.

How pellets and briquettes burn

Despite the fact that the combustion of pellets and briquettes is based on the process of pyrolysis, that is, the release of flammable gases when wood is heated and their subsequent combustion, these materials burn differently .

Pellets due to:

• small size;
• dense laying

They do not allow air to pass through them well, so the traditional movement of fire from the bottom up is ineffective .

For efficient combustion, it is necessary to either reduce the thickness of the pellet layer placed in the firebox, or use the movement of fire from top to bottom.

You can read more about this combustion process, as well as the equipment for it, in this article.

Reducing the thickness of the pellet layer in the firebox leads to a reduction in their burning time , and therefore the need to frequently add fuel to the stove or boiler.

There are boilers with automatic pellet feeding that completely solve this problem. Pellets are poured into a hopper, from which they automatically enter the firebox. The pellet supply is regulated by automation , which determines the temperature of the coolant (water) or exhaust gases and uses them to estimate the remaining fuel in the firebox.

The combustion of briquettes
depends on their shape .
Rectangular briquettes (RUF, brick) burn in the same way as firewood, that is, the denser they are stacked, the longer they will burn, releasing less heat.

The greater the distance between them, the faster they will burn, releasing more heat.

Regardless of the installation method, the total amount of thermal energy that will be released during the combustion of briquettes is the same .

In contrast, briquettes of the Nestro type (round) burn equally no matter how they are laid , because there is enough space for passage between them:

• air;
• pyrolysis gases.

Briquettes like Piny & Kay burn in the same way - octagonal logs with a through hole in the middle.

Therefore, for ordinary ones:

• ovens;
• fireplaces;
• boilers,

which do not have an automatic fuel reloading system , any type of pellets are effective.

How to calculate pellet consumption

The calculation is carried out in several stages, although in general it is quite simple. Its result should be the average monthly fuel consumption of a pellet boiler during the heating season and the average cost of such heating. To do this, we will simultaneously consider an example for a house with an area of ​​100 m².

Stage one. First you need to understand how much heat actually enters the heating system when burning 1 kg of fuel pellets. After all, heating equipment is not so perfect as to direct all the energy received to heat the house; some of it still flies out into the chimney. To do this, the combustion heat of the granules should be multiplied by the efficiency of the heat generator, divided by 100:

5 kW/kg x 80% / 100 = 4 kW/kg.

Stage two. For ease of calculation, you need to do the opposite to find out how many pellets you need to burn to obtain 1 kW of thermal energy in real conditions:

1 kW / 4 kW/kg = 0.25 kg.

Stage three. Since the weather outside changes during the heating season and the temperature fluctuates from +10 °C to -30 °C, the average specific heat consumption for the entire season for a 100 m² dwelling will not be 10 kW, but half as much - 5 kW. Considering that power units are assigned to a time of 1 hour, the heat consumption per day will be:

5 kW/h x 24 hours = 120 kW.

The same, only for a month:

120 kW x 30 days = 3600 kW.

Stage four. Now it is easy to calculate the average consumption of pellets per month for a building of 100 m² during the entire heating season:

3600 kW x 0.25 kg/kW = 900 kg.

If the cold season lasts 7 months, as in Moscow, Russian Federation, then the total amount of fuel pellets for heating a private house with an area of ​​100 square meters will be 900 x 7 = 6.3 tons. The average monthly consumption of pellets for a house with an area of ​​150 and 200 m² is determined in the same way; it is equal to 1.35 and 1.8 tons, respectively. Since pellets are sold by weight and not by volume, there is no need to convert this quantity into volumetric units.

Those who are interested in the theoretical value of wood pellet consumption on average per day can calculate it in this way (for our example):

120 kW x 0.25 kg/kW = 30 kg.

Attention! The average calculated value should not be confused with actual fuel consumption on the coldest and warmest days. In a building of 100 m² it can vary between 15-60 kg of pellets per day

To get approximate costs for pellet heating in monetary terms, you need to multiply the obtained figures by the price per ton accepted in your region. At prices in the capitals of the Russian Federation and Ukraine, monthly heating costs for a private house of 100 square meters will be:

• for Moscow: 0.9 t x 7000 rub/t = 6300 rub;
• for Kyiv: 0.9 t x 2000 UAH/t = 1800 UAH.

It should be taken into account that we carried out an abstract calculation and in the conditions of Ukraine, financial costs for pellet heating will be less due to the milder climate.

Production flow diagram

In order to produce fuel pellets that meet all the required characteristics, it is necessary not only to use high-quality raw materials and special equipment for the production of pellets for these purposes, but also to strictly adhere to the technology.

Technological scheme for the production of fuel pellets

The pellet manufacturing process consists of several stages.

1. First, the wood raw material is cleaned from foreign impurities and its primary crushing is carried out. As a result of this process, for which conventional crushers are used, wood raw materials are divided into fairly large fractions.
2. This is followed by drying, during which the moisture content of the wood raw material is brought to a value not exceeding 12–14%. For drying raw materials, drum or aeration type installations are used.
3. After drying, the wood raw materials are subjected to finer grinding, for which hammer-type crushers are mainly used. The output from such installations is fine sawdust or even crumbly wood pulp, reduced to the state of flour, from which the highest quality fuel pellets are produced.
4. If, after repeated grinding, the moisture content of the resulting wood pulp does not reach the required minimum value (10–12%), this parameter is artificially increased using steam or ordinary water for this purpose.
5. After the parameters of the raw material for the production of fuel pellets are brought to the required values, it is fed to a pressing plant - a pelletizer. In such installations, which may differ from each other in design, the bulk mass is pressed through the holes of the matrix, resulting in the formation of dense cylindrical granules of a certain diameter. Exerting significant pressure on the crumbly wood pulp promotes its spontaneous heating. At the same time, a natural component is released from it - lignin, which has good binding properties. It is this component that ensures the formation of a dense briquette with a stable internal structure from individual particles of crumbly wood raw materials.
6. Matrices, in the working cavities of which crumbly wood raw materials are converted into dense fuel briquettes, can be cylindrical or flat. Installations of the first type, as a rule, are produced in a stationary design and are used primarily to equip industrial enterprises. Their design includes a special cutting device that allows the production of pellets of approximately the same length. Flat-type matrix installations, which can be equipped with one or more rollers, are characterized by compact dimensions. This type of equipment is most often used to organize the production of pellets at home or in a small enterprise.
7. The finished pellets, the temperature of which, as a result of their spontaneous heating during the pressing process, can range from 65 to 90°, are cooled, dried if necessary, and then packaged and sent to consumers or to a warehouse.

The stages of pellet production are demonstrated in detail by relevant videos that are easy to find on the Internet.

Pellets consumption for heating a house

Recently, many owners of private houses use pressed pellets made from waste of a wide variety of combustible materials to heat the premises of their homes. These granules are called pellets. Those homeowners who are just planning to install hot water boilers in their home that use pellets as fuel are interested in the consumption rates of this fuel material, as well as the amount of heat released during its combustion. We will try to cover these issues in as much detail as possible within the confines of this short article. As a rule, the choice of one or another type of solid fuel boiler is based on the availability and cost of fuel. In addition, many owners of private houses try to choose equipment that requires minimal maintenance. In other words, there is no need to fill the firebox every day, remove combustion products, etc. Therefore, among a wide range of types of boilers operating on solid fuel, pellet equipment is the most in demand.

Required power

In private houses, boilers with a power of 15 kW to 100 kW are installed. If less than 15 kW is required to heat the building, then it will be more profitable to install a pellet fireplace. The simplest way to determine the power that heating a private house with pellets will require is measured as 1 kW per 10 square meters of house area.

Advice! The above method is quite rough and approximate. It does not take into account heat loss from the house. Therefore, when calculating the required boiler power in this way, you need to add at least another 15%. Otherwise, the power of the equipment may not be enough.

Which pellet boiler is suitable for your home?

Now you can buy absolutely everything and the choice depends only on preferences, the area that will need to be heated, and cost. Which pellet boiler should you choose? Always choose one with a slightly higher power to provide a small reserve, because running the equipment at maximum power does not benefit it. Here is an overview of pellet boilers depending on the area of ​​the heated zone.

Up to 50 sq.m

For such a small room, you can take a LAMINOX ADA AIR 6 pellet fireplace with automatic fuel supply. This will eliminate the need for additional communications and ensure a comfortable temperature.

LAMINOX ADA AIR

50-100 sq.m

The Termal-10 Basic pellet fireplace is ideal for heating such an area. This is the most inexpensive automatic fireplace for organizing air heating.

Termal-10 Basic

100-150 sq.m

A pellet stove with a water circuit Buderus Logano S181-15 E and automatic fuel supply is suitable here. It will perfectly provide the house with heat and hot water.

Buderus Logano S181-15 E

150-200 sq.m

It is worth taking a pellet-coal universal boiler with automatic fuel supply WBS-AC-UB 25. The versatility of the fuel will allow for more flexible operation, and its power will more than provide the required temperature.

WBS-AC-UB 25

From 200 sq.m

To heat such an area, you need units from 25 kW, for example, Buderus Logano S181-25 E with automatic fuel supply and water circuit.

Buderus Logano S181-25 E

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Where can I buy

It is better to buy popular models of pellet boilers in specialized stores of heating equipment for the home, as well as in representative offices of manufacturers of such equipment or their dealers. The best units offered by the best manufacturers, where you can not only visually inspect them, but also twirl them or listen to practical advice and recommendations - which company is better to buy, what they are, how much they cost, how to choose, what to pay attention to in order to avoid mistakes when choosing .

In addition, budget new items can be ordered online in an online store specializing in the sale of such products. In this case, help will be provided by popular aggregators, such as E-catalog or Yandex.Market, where product cards with the necessary information are posted - description, parameters and their comparison, photos.

Maintenance

Heating a home using pellet boilers requires little maintenance.
They usually have an open heating system, so you need to monitor the water level in the system. You can automatically supply water replenishment to the heating system. The boiler itself must be cleaned of soot, especially the heat exchanger jacket, as this affects the consumption of pellets. Smoke exhaust pipes need to be cleaned. This does not take much time, and the moment when cleaning is necessary can be determined visually by looking at the water jacket, or if the consumption of pellets has increased. The deadline is when the boiler begins to smoke into the room.

If pellets are supplied using a rigid auger, then it is necessary to periodically clean this system from dust that accumulates in the air supply channels.

Conclusion

Pellets and briquettes are modern types of fuel that are superior to firewood in terms of heat capacity, and coal in terms of ease of use.

However, to effectively use this fuel, special equipment is required, because the main advantage of pellets and briquettes is that they can be loaded automatically .

Now you know:

• what equipment is needed for heating using these materials;
• what is the difference between heating devices using pellets and briquettes from conventional solid fuel stoves and boilers;
• how much do heating devices with pellets and briquettes cost;
• how to choose boilers for heating with pellets and briquettes.

Medium quality pellets

In the above calculations, the indicator of calorific value inherent in high-quality white granules, the so-called elite, was used. They are made from good wood waste and have virtually no foreign inclusions, such as tree bark. Meanwhile, various impurities increase the ash content of the fuel and reduce its calorific value, but the price per ton of such wood pellets is significantly less than elite ones. By reducing the cost, many homeowners are trying to make their pellet heating more economical.

In addition to elite fuel pellets, cheaper pellets are produced from agricultural waste (usually straw), whose color is somewhat darker. Their ash content is low, but their calorific value is reduced to 4 kW/kg, which will ultimately affect the quantity consumed. In this case, the consumption per day for a house of 100 m2 will be 35 kg, and per month - as much as 1050 kg. The exception is pellets made from rapeseed straw; their combustion heat is no worse than that of birch or pine pellets.

There are other granules that are produced from a variety of waste from wood processing enterprises. They contain all sorts of impurities, including bark, which cause malfunctions and even malfunctions in modern pellet boilers. Naturally, unstable operation of equipment always causes increased fuel consumption. Heat generators with retort burners in the form of a bowl facing upwards are especially often capricious from low-quality pellets. There, an auger supplies fuel to the lower part of the “bowl”, and there are holes around it for air to pass through. Soot gets into them, causing the combustion intensity to decrease.

To avoid such situations and reduce the efficiency of the boiler, it is advisable to choose fuel with low ash content and in no case wet. Otherwise, problems will begin with the screw feed because the wet granules crumble and turn into dust, clogging the mechanism. You can use cheaper fuel to heat your house with pellets when the boiler is equipped with a torch-type burner. Then the ash covers the walls of the firebox and falls down without getting back into the burner. The only condition is that the combustion chamber and burner elements will have to be serviced and cleaned more often as they become dirty.

How to make pellets from sawdust, straw or husks with your own hands

First of all, it is necessary to carefully calculate the feasibility of this event. If the raw materials for the pellets are free or the owner got them for next to nothing, then the implementation of the idea will be profitable.

To produce pellets, two components are needed: raw materials and equipment. Sawdust, husks or straw are also not suitable, they need to be prepared first:

1. Only softwood will make it possible to produce high-quality pellets. Sawdust from hard types of wood will have to be mixed with softer ones, otherwise granules will not form - the pellets will crumble into powder, and when burned they will produce a large amount of ash.
2. The humidity of sawdust plays an important role in the production of pellets - it should be at the level of 12%. Wetter sawdust will have to be pre-dried (straw and husks, as a rule, are initially well dried), and overdried raw materials must be moistened, otherwise the granule will not form.
3. Sawdust of a large fraction must be crushed, since sawdust or straw, previously cut into small pieces, is fed into the granulator.

Based on these requirements, it is easy to determine the number of pieces of equipment in a production line for making pellets with your own hands:

• crusher for primary grinding of branches, wood chips and bark;
• drying or drying chamber;
• another crusher for finer and better grinding of sawdust;
• humidifier for sawdust;
• granulator;
• cooler for finished pellets.

Each of these devices needs to be described in more detail, but it is the working tool that deserves the most attention - a granulator or a press for squeezing out granules.

Pre-treatment of sawdust

Before pressing, raw materials for pellets must go through several stages of preparation:

• primary grinding, during which branches are cut, bark, twigs and other hard and large fragments that can be caught in sawdust are broken. For these purposes, it is necessary to use a crusher capable of crushing sawdust to a size of 1.25 cm³. You can avoid this stage if you use high-quality sawdust from furniture or carpentry, straw or husks.
• Sawdust must be dried in special chambers with high temperatures. The moisture content of the material after this stage should not exceed 8-12%.
• In small hammer-type crushers, dried sawdust is crushed to a fraction of 1.5 mm. The straw is cut with special scissors.
• In order for the sawdust or hay powder to clump, it must be moistened again. Sawdust from soft wood is irrigated with water, while sawdust from oak or beech must be treated with hot steam.

Attention! Making pellets from straw is much easier than making pellets from sawdust. The straw does not need to be dried; it is chopped with scissors rather than crushers, and, due to its softness, the straw is much easier to press through the holes of the granulator. Less equipment, less power spent on granulation - the result is lower costs for the production of pellets.

Pressing of raw materials

The granulator is the most important and most expensive piece of equipment for the production of fuel pellets. This device can be purchased, but craftsmen with access to a lathe and welding machine can make a pellet press with their own hands.

There are several types of pellet granulators:

1. A screw press resembles a regular meat grinder - the same shaft moves inside it, and a mass of crushed sawdust is pressed through a matrix with holes. It’s not difficult to make such a press with your own hands, but its power may not be enough for sawdust granulation; a screw granulator is more suitable for straw and husks.

2. Flat die presses are the most popular type of equipment in home pellet production. Sawdust is poured into a hopper, at the bottom of which there is a matrix with holes; two toothed cylinders roll along this flat matrix, which press the sawdust to the holes, pushing them through and forming granules. It is quite possible to make such a granulator yourself, you just need to know how to use a milling and lathe. There are press parts for sale, which allows you to simply assemble the device from ready-made parts. It is enough to purchase an electric motor and a metal matrix, after which you need to assemble a pellet pressing machine from all the parts.
3. Presses with a cylindrical matrix are considered the most productive, therefore, they are most often used on an industrial scale. The principle of their operation is the same as the previous granulators, only the toothed rollers are located inside a large cylinder with holes, and roll along its walls, pressing a mass of crushed sawdust. There is a knife installed outside that cuts the granules to the required length.

Advice! Home sawdust granulators, as a rule, are not very powerful, so they work quite slowly. In order not to stand near the hopper all the time and not fill up the raw materials, you can make a screw conveyor along which the sawdust will move to the granulator hopper at a certain speed.

Final stage

During the pressing process, sawdust is heated to 70-90 degrees; in this form, the granules are very brittle, they can easily crumble and deteriorate. Therefore, the pellets must be cooled immediately after leaving the granulator. To do this, they are placed on flat pallets and blown with cool air or left to cool in natural conditions.

After cooling, the granules become hard and are no longer so easy to break. Now the pellets need to be sifted to separate unformed parts, dust and fine wood powder - all this causes the appearance of excess ash on the walls of the boiler.

Screened sawdust pellets can be placed in plastic bags and stored until the next heating season.

Important! In the room where sawdust pellets are stored, fire safety standards must be strictly observed, since the material is highly flammable.

Construction of pellet boilers

Pellets are solid fuel that is produced from wood waste, peat and agricultural waste. In fact, these are pressed pellets of small diameter, up to 5 cm in length. The main advantage of pellets over other types of solid fuel is their low ash content; therefore, the need to remove soot arises less often than when using firewood

If the impact on the environment is important to the home owner, then pellets cause minimal harm to the environment. Operating principles of a pellet boiler - pellets are loaded into a hopper, then they are fed into the firebox, where they burn, releasing heat

The most important thing is that all processes are controlled automatically. Those. if you need to quickly warm up the house before guests arrive, a pellet boiler will burn fuel at maximum speed, feeding pellets into the firebox using an auger. As soon as the required temperature is reached, the equipment will switch to temperature maintenance mode, reducing the fuel supply rate.

Burners in pellet boilers are divided into two types - retort and flare. A retort burner is a bowl with slots into which pellets fall and ignite under the influence of hot air. In torch-type burners, pellets are fed to a platform where hot air creates a torch directed horizontally. There are no clear advantages for any type of burner, so when choosing specific equipment it is not a decisive factor.

Flare-type burners are used in the Metal-Fach Smart BIO line. Smart BIO is the company’s own development; the burner is made in the form of a trench. Designed for burning pellets and grain. The design of the firebox allows the use of coal and firewood.

Most pellet boilers are equipped with an automatic ignition system. The absence of such a function means that the process must be started manually each time, which significantly reduces ease of use. If there is automatic ignition, the boiler can start heating the house on its own using a timer, sensor or command from a mobile phone.

The Metal-Fach SEG BIO model allows you to light a fire from anywhere on the planet by simply sending the appropriate command from your phone or via the Internet. In emergency cases, wood or coal can be used as fuel, but pellets are preferable.

Metal-Fach SD DUO BIO is designed for minimal environmental impact - it is designed for the use of pellets. It can also work on eco-seed coal, wheat grains, and grape seeds. The equipment is automated - there is automatic feeding, automatic ignition, and can be controlled from a cell phone and via the Internet. In addition, boilers of the SD DUO series have a water-filled grate, which increases heat removal. It is worth noting that SD DUO boilers are the flagship in the line of boilers of the Polish company Metal-Fach.

How to calculate pellet consumption

Considering the fact that fuel is supplied in bulk or packaged in bags, it is, in principle, not difficult to calculate the consumption of pellets per 1 kW or per 1 m2. There is no need to convert weight units into volume, since delivery always occurs in kilograms, and the heat of combustion of fuel is also measured in kW per 1 kg of weight.

Good quality granules have excellent calorific value; burning 1 kg of such fuel produces almost 5 kW of thermal energy. Accordingly, to get 1 kW of heat for heating a house, you need to burn about 200 grams of pellets. The average consumption of granules per unit area can be easily determined based on the fact that heating each 1 m2 of area requires 100 W of energy

One condition is important: the ceiling height should be within 2.8-3 m. 100 W of heat will be obtained from 20 grams of granules, it would seem simple arithmetic

But it was not there. The figures presented above are correct if the pellet boiler has absolute efficiency - 100% efficiency, but this does not happen in real life. In fact, the efficiency of such heat generators, although higher than that of solid fuel boilers, is still only 85%. This means that after burning 1 kg of pellets in the furnace of the unit, not 5 kW of energy will be obtained, but 5 x 0.85 = 4.25 kW. Conversely, to release 1 kW of heat in pellet boilers, 1 / 4.25 = 0.235 kg or 235 grams of fuel is consumed. This is the first point.

The second nuance is that 100 W of heat per 1 m2 of room is required when the ambient temperature is the lowest, which lasts for 5 days. On average, during the heating season, thermal energy consumption is half as much. This means that the specific heat transfer per unit area is only 50 W. Determining the consumption of pellets in a pellet boiler for 1 hour relative to 1 m2 will be incorrect; the figure will be small and inconvenient. It would be more correct to calculate the weight of pellets burned per day.

Since Watt is a unit of power per 1 hour, then per day for each square of the room you will need 50 W x 24 hours = 1200 W or 1.2 kW. For this purpose, you will need to burn the following mass of pellets per day:

1.2 kW / 4.25 kW/kg = 0.28 kg or 280 grams.

Knowing the specific fuel consumption, we can finally obtain values ​​useful for financial calculations, for example, the average seasonal weight of pellets used per day and per month in a house with an area of ​​100 m2:

• per day - 0.28 x 100 = 28 kg;
• per month – 28 x 30 = 840 kg.

It turns out that 8.4 kg of fuel is needed per month to heat 1 m2 of a building. At the same time, according to user reviews on various forums, heating a well-insulated house of 100 m2, located in the middle zone, takes about 550 kg of pellets, which in terms of square footage is 5.5 kg/m2. This means that the consumption of pellets in the boiler in the amount of 840 kg per month for a building of 100 m2 is very large and suitable for calculations of poorly insulated houses.

Let us summarize some results in the form of calculation results for dwellings of various sizes. The following are the monthly costs of pellets for heating a private home:

• 100 m2 – 840 kg with poor insulation, 550 kg for good thermal insulation;
• 150 m2 – 1260 kg and 825 kg, respectively;
• 200 m2 - 1680 kg and 1100 kg under the same conditions.

For reference. In many boiler installations, the controller has a function that allows you to see on the display the consumption of pellets in kilograms over a certain period.

Features of application

The main problem that arises when heating with any solid fuel is that the burning time of one bookmark with maximum efficiency does not exceed 1–2.5 hours . This fully applies not only to firewood or coal, but also to pellets and briquettes.

Therefore, solid fuel heating is implemented in three different ways:

• increase burning time;
• store the released thermal energy;
• use automatic fuel loading systems.

Increased burning time

The burning time of such fuel is increased in two ways:

• burning from top to bottom;
• restriction of air supply.

Combustion from top to bottom is implemented in boilers and furnaces of the “Stropuva” type, however, such devices are very demanding in terms of :

• fuel quality;
• cravings;
• temperature of the returning coolant.

In addition, boilers of this type are not cheap , their average cost is 100 thousand rubles.

Increase in combustion time due to air supply limitation dramatically:

• reduces the efficiency of the boiler or furnace;
• increases fuel consumption.

How to store thermal energy

More efficient systems are those that store thermal energy to then heat the house for a long time.

Such systems include:

• brick kilns;
• fireplaces with rough brick;
• water boilers of excess power with a heat accumulator (TA).

Brick stoves and fireplaces with rough materials store heat due to the high heat capacity of brick . The temperature of the gases inside the furnace reaches 1000 degrees, so during the burning time of one bookmark (1–2 hours), the brick walls store enough heat to heat the house for 12–20 hours.

Coal and wood stoves work well with briquettes, but heating with pellets requires a pellet burner because pellets are not well suited for such devices due to their combustion characteristics.

Excess power boiler with heat storage

Another option for a system that stores heat is an excess power boiler with a water heater .

Excessive boiler power is necessary in order to release enough heat during one fire to heat the house for 50–70 hours.

In this case, the capacity of the heat accumulator is determined by the formula V=S/10, where:

• V – area of ​​the house in m2;
• S – TA volume in m3.

The boiler power for a well-insulated house is determined by the formula P=S/2, where:

• P – boiler power in kW;
• S – area of ​​the house in m2.

Such systems work well on any type of fuel , so pellets and briquettes have no advantages, except that these materials are cheaper than any other fuel.
also no advantage when using conventional or pyrolysis solid fuel boilers, in which it is necessary to add fuel after 2–6 hours .

However, any of the described systems works well on pellets or briquettes, so the cost of fuel decides everything .

Automatic fuel loading systems

Pellets and briquettes are most effective in boilers with automatic fuel supply . Despite the fact that some models of such boilers can run on wood or coal, pellets and briquettes are preferable. Pellets because of their small size, and briquettes because they have the same shape.

All systems of this type can be divided into:

• pneumatic;
• screw;
• conveyor;
• elevators;
• monoblock.

Pneumatic

Pneumatic systems combine forced air supply to the combustion zone and fuel supply, therefore they are only suitable for boilers operating on:

• pellets;
• wood chips

In such systems, exhaust gas temperature sensors are installed that determine the intensity of combustion.
Therefore, the amount of air and fuel supplied over a period of time is precisely dosed to ensure the most efficient combustion .

During warming up, the amount of air and fuel is maximum, so a strong fire burns in the firebox.

When the temperature in the house has reached the set value, the automation reduces the supply of fuel and air, due to which the boiler switches to low power mode and maintains the temperature .

In pneumatic systems, the boiler and compressor are connected by a thick pipe, the diameter of which is sufficient for the free passage of pellets in any position.

In this case, the diameter depends on the power of the boiler, because even in temperature maintenance mode, the speed of air movement in the pipe must be sufficient to transport fuel .

A dosing device installed under the hopper regulates the fuel supply by changing the cross-section of the hole through which pellets fall into the air duct. On some models, instead of a hole with a variable diameter, a screw drive is installed, providing more precise adjustment .

The main disadvantage of pneumatic systems is their large size, because the pipes take up a lot of space. Therefore, they are installed only in certain rooms. In addition, the boiler can be installed in one room, and the bunker and compressor in another.

Screw

Screw automatic fuel supply systems operate on the same principle as a screw in a meat grinder . A rotating screw moves material from the hopper to the firebox.

By turning the engine on and off, as well as changing its rotation speed in high-power boilers, the supply of fuel to the furnace is regulated.

Such devices are much more compact than pneumatic ones, because in most cases the bunker and boiler are combined into one device. The exception is high-power boilers ; bunkers for them are installed separately and connected to each other by a screw conveyor.

Depending on the firebox model, the screw conveyor delivers pellets either directly into the combustion zone or into the upper part of the firebox, from where the pellets fall into the combustion zone.

In both cases, the hole through which the fuel enters the boiler is closed by a metal valve controlled by an electric motor or solenoid. Therefore, the hole opens only during fuel loading , after which it closes hermetically.

This system protects burning fuel from excess air and also prevents smoke from entering the room.

Boilers with a screw feed are in maximum demand, because without modification or changing settings they can operate not only on pellets, but also on such types of fuel as:

• wood chips;
• sawdust;
• crushed biomass;
• peat;
• black and brown fine coal.

Conveyor

In such systems, the bunker and firebox are connected by a conveyor with:

• tape;
• mesh;
• trays.

The advantage of systems of this type is the ability to supply fairly large fragments to the boiler, which is beyond the capabilities of pneumatic and screw systems, so they are used for boilers operating on:

• coal;
• firewood;
• briquettes.

Due to the fact that firewood and coal consist of fragments of different sizes, difficulties arise with dosing , so in addition to the conveyor, it is necessary to install a complex and expensive loading device.

Briquettes do not have this drawback, therefore, to work with the conveyor, they use the simplest cassette storage facilities, in which the briquettes are stacked in neat and even cassettes.

In such systems, briquettes are first selected from the furthest cassette, then moved to the front, and all this does not require any complex automation .

However, the conveyor system is very poorly suited for pellets, because it is necessary to install a complex loading device based on an auger , and also use not a metal mesh or trays, but a rubber band, which is sensitive to high temperatures.

Therefore, such a system can only deliver pellets to the top of the boiler, where the temperature is not too high, then the pellets will fall into the combustion zone.

This loading method leads to the release of a large amount of combustion products, so the boiler cannot be used in residential buildings or in areas where people are often present.

Elevators

Loading systems of this type are most often used for wood-fired boilers. The elevator lifts the fuel, and the guide located on top sends the top layer of fuel into the boiler.

Such systems can also be used for heating with briquettes, because the guide will send them into the firebox in the same way as firewood.

The main disadvantage of systems of this type is the very high price, therefore for briquettes in which each log corresponds to one:

• form;
• size,

It makes no sense to use such complex and expensive systems.

Monoblock

This is the most popular way to use pellets in boilers of small (up to 50 kW) power.

A bunker is installed above the boiler, which contains enough fuel for heating at maximum mode for at least a day.

After the sensors detect a decrease in the temperature of the exhaust gases, an electric motor or solenoid opens the valve between the boiler and the bunker for a strictly defined time .

Thanks to this, a certain volume of pellets is poured into the firebox, necessary to release the required amount of thermal energy.

All calculations are performed by a built-in processor , which evaluates many parameters and supports combustion in the selected mode.

Automatic cleaning of the firebox and grate

However, automatic fuel reloading is not the only problem that needs to be solved to increase the boiler operating time from one fill, because sawdust and briquettes leave behind ash, which reduces the air supply from below to the combustion zone .

Therefore, automatic ash removal is necessary:

• firebox;
• grate.

To do this, the grate is connected to a vibrator based on:

• electromagnet;
• electric motor.

Based on a signal from the processor, the vibrator pulls the grate, the ash spills down, and the coals and burning fuel remain on the grate .

The same systems are used on any automatic solid fuel boilers, regardless of the type of fuel they operate on.

Calculation of pellet consumption initial data

For calculations performed to determine the theoretical fuel consumption for heating a country house, it is necessary to collect the following initial data:

• the amount of heat load on the heating system of a cottage or country house, expressed in kW;
• Efficiency of the pellet boiler model that you plan to install in your furnace room;
• calculated heat of combustion of fuel pellets;
• To get the result in monetary terms, it is advisable to find out the price per ton of pellets in your region of residence.

The most difficult thing is to obtain a figure for the actual heat load, which consists of heat losses through external walls, roofing, glazing and floors, plus the cost of thermal energy to warm up the ventilation air.

The ideal option is to contact a qualified heating engineer for such a calculation, then you will find out the exact figure. Otherwise, you will have to calculate the thermal load and fuel consumption in aggregated ways:

1. Based on specific heat consumption per square meter of area. For dwellings in central Russia, it is assumed that in a room with 1 window and one external wall, 100 W of heat per 1 m² will be consumed, with two external walls - 110 W/m², with 2 walls and two windows - 120 W/m².
2. The same applies to the volume of the building. The method is used when the ceilings in the rooms are higher than 2.8 m. The total volume of heated rooms is calculated and multiplied by 40 W.

In the calculation example discussed below, the heat load for a private house of 100 m² is conventionally assumed to be 10 kW, since pellet consumption is determined in an abstract building with a pellet boiler from an unknown manufacturer.

The efficiency of a heat generator that burns wood pellets is indicated in its technical data sheet. If the model and manufacturer have not yet been selected, then for calculations you can take the figure of 80%. Manufacturers leading the rating of heating equipment (for example, Viessmann or Buderus) declare the efficiency of their pellet boilers to be 85%. But these are high-quality and reliable products whose cost cannot be called low. For equipment with a more affordable price, the performance is not so high.

The theoretical calorific value of pellets is a known value; it lies in the range of 4.9–5.2 kW/kg, depending on the quality of the fuel and the raw materials from which they are made

If you do not take into account peat granules with high ash content and low heat transfer, then for calculations it is worth taking the average figure - 5 kW / kg

Features of pellet heating systems

In order to evaluate the effectiveness of pellet heating, you need to know about the difference that exists between ordinary firewood and pellets. During the production of pellets, wood processing waste is used. The raw materials for the production of pellets or ordinary sawdust are first thoroughly dried, then treated with steam, resulting in the formation of a viscous mass, from which cylindrical granules with a length of about 70 mm and a diameter of 6 to 8 mm are formed under pressure of 300 atmospheres. Boilers supplied to the market by pellet manufacturers equipment, differ from their analogues that use ordinary firewood as fuel by a higher degree of heat transfer. Quantitative indicators of the calorific value of various types of solid fuel are indicated in the table.

In addition to high heat transfer, pellet boilers have another advantage - their combustion chamber is loaded automatically. Automatic fuel supply is implemented as follows:

1. A certain supply of pellets is stored in a special hopper made of stainless steel. The presence of a large-volume bunker allows you to refuel it once every few days.
2. The fuel enters the boiler through a flexible cable and an auger located inside it. The granules' own weight causes the auger to rotate, which ensures their supply to the distribution chamber of the boiler in the required quantity.
3. Next, from the distribution chamber, the pellets enter the air burner zone, where they are incompletely burned, accompanied by the release of wood gas.
4. The main source of high heat transfer is wood gas, which burns completely in the afterburner.

This design of the boiler allows its owner, during continuous operation of the equipment, to fill the bunker with fuel only once every 3-4 days and remove solid combustion products, i.e. ash.

Thermal accumulators

All boilers of these types are effective only when connected to a heat accumulator , otherwise the boiler will have to be fired several times a day:

• clean;
• download;
• melt.

Due to the high cost of the TA and the cost of its installation, even the cheapest boiler will cost several times more than the average cost automatic boiler.

For a house with an area of ​​100 m2, the optimal capacity of the heat accumulator is 10 m3.

The TA must be installed below floor level; if it leaks, there is a high probability of severe burns.

Reducing the TA capacity leads to a reduction in heating time , so it is undesirable to reduce its volume by more than 3 times.

For example, a heat exchanger with a capacity of 3 m3 can heat a well-insulated house with an area of ​​100 m2 for 20–25 hours, even in severe frosts. That is, the boiler will have to be heated once a day.

If the capacity of one heat accumulator is not enough, then several heat accumulators are installed, using different connection schemes; this does not change the heating time of the house .

Here is the approximate cost and a brief description of heat accumulators, as well as various types of boilers for working with them:

Conditions of storage and use

When purchasing a large batch of pellets, you need to take care of where they are stored. When stored indoors, they should not be placed near open sources of fire. It is also necessary to protect the material from its worst enemy - dampness.

How to store pellets if there is no space in the house? Closed bags/packages can be placed outside under a canopy. However, this option is undesirable - when it rains, the risk of the packaging getting wet 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 purchased separately and installed on the boiler literally within 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 using the control panel.

Pros and cons of this type of raw material

Pellets entered the market as a heating product relatively recently, but their popularity is already obvious. And although the prices for equipment that uses them as fuel are not cheap, due to their positive qualities they are becoming more and more popular for heating rooms. Thanks to the variety of their types, you can choose heating equipment according to your needs. If possible, you can choose a boiler with a combustion load for several hours, several days, and even months

In the modern world, more and more attention is paid to the environmental friendliness of the products used. And compressed wood waste becomes an alternative in this case

They are convenient to store; when supplied in bags, they are light and compact in placement. And their quantity is required less than other types of fuel

It is also important that when they burn, the smoke has no odor

The disadvantage of using them, which cannot be avoided, of course, is the release of ash. And even when using elite brands of wood pellets, it is necessary to clean the boiler at least once every two months. And after the winter season, be sure to completely disassemble and clean the boiler. The storage location is also important. And for better performance of their properties, they should be stored in dry rooms without the possibility of getting damp. Since raw ones can cause the boiler to stop working.

Equipment for the production of fuel pellets from sawdust

Equipment for the production of pellets from sawdust allows you to quickly set up a business for processing wood waste. As a result, you will not only help enterprises in your region get rid of sawdust, wood chips and other garbage, but you will also be able to earn some money from this, and if you put the business on an industrial basis, then this type of activity may even become your main source of income. At the same time, mini-production of pellets will make it possible to close the shortage of this type of fuel in a particular region, which is not uncommon, because heating with pellets is becoming increasingly widespread in Russia due to its high environmental safety.

Types of equipment for pellet production

The pellet production line can be either industrial or household, designed for the production of mini-pellets for domestic use. Such a line can be driven by a diesel engine, an electric motor or a tractor shaft. In this case, the most common option is the tractor power take-off shaft, since such a power mechanism can provide fairly high productivity in the amount of 200-250 kg/h.

Equipment for the production of sawdust pellets includes:

• tenon cutter, whose main task is to chop wood;
• dryer drum;
• hammer type mill;
• screw mixer;
• press;
• cooler

The approximate cost of such a line could be about 2 million rubles. In this case, a machine for the production of pellets, powered by an electric motor, can only be stationary. This reduces its mobility and requires a special place for it. Carrying out such work can cost several tens of thousands of rubles.

As for the installation, driven by a diesel engine, as well as a tractor, it is highly mobile and can be installed directly in the place where woodworking work is carried out. By the way, in this case, the production of pellets from sawdust will not require additional costs for transporting the material to the place of its processing.

Separately, it is worth noting that stationary industrial-type production lines capable of producing 700-1000 kilograms of pellets per hour will cost about $132,000. This is quite a serious investment, but it will be able to pay off within 7 years.

Mini granulator

Cost from 64 thousand rubles.

Diesel engine pellet press

Cost from 89 thousand rubles.

Pellet press with electric motor

Cost from 100 thousand rubles.

Industrial line

Cost from 1.8 million rubles.

Each type has its own characteristics. For example, a device for electric motors has a certain stationarity, while devices with diesel engines are more mobile.

Example of equipment parts for the production of fuel pellets based on an industrial type line:

Such a line costs about 1,800,000 rubles.

Key elements of pellet lines and their approximate prices separately:

1. Wood chipper (wood chipper) - about 180,000 rubles.
2. Dryer of raw materials for the production of pellets - from 400,000 to 2,500,000 rubles.
3. Granulator - from 50,000 to 1,100,000 rubles. Model OGM-1.5 costs about 1,000,000 rubles.
4. Pellet cooler - about 400,000 rubles.

Granulators are divided into types relative to the matrix:

• flat die granulator;
• round die granulator;
• hybrid granulator with flat and round matrix;

Flat Die Granulator

A flat die is a flat metal disk that is made of high quality steel. Its diameter is 100-1250 mm, thickness 20-100 mm. The steel used must be wear-resistant and hardened to 60-60 on the Rockwell hardness scale. As a rule, domestically produced steel 40X is used, or HARDOX 500 and 20CRMN steels are used.

The productive capacity of the granulator directly depends on the diameter of the matrix. For example, equipment with a matrix diameter of 1250 millimeters can produce up to 3 tons of granules per hour.

The round matrix on granulators reaches a diameter of 550 millimeters. It is made from stainless steel with great wear resistance. Such steel should heat up to a hardness of forty-five to fifty kgf according to Rockwell.

When it comes to productivity, it is necessary to differentiate its value from the high-quality preparation of wood and its components. Also, the power of the electric motor is important for high productivity. Manufacturers, as a rule, install a gearbox on the granulator with torque parameters and a gear ratio with high efficiency, which allows the existing electric motor to be used at optimal power.

Such granulators have long been known in the CIS. They produce compound feed. Their series is DG and OGM. But craftsmen have learned to convert them to make fuel pellets. It is necessary to replace the matrix for the raw materials used and the rolling rollers.

The third version of granulators is almost never used in our territories, but is very common in China. The circular matrix is ​​located parallel to the base. Roll out rollers roll the wood into the granulator using their own weight.

Pellet presses driven by tractor power take-off shaft

Cost from 100 thousand rubles.

Types of pellets and their production technology

Pellets, or sawdust granules, are one of the most popular types of secondary raw materials in the future. Thus, in the UK, approximately 600,000 tons of this biofuel are produced annually, and China is planning to reach a production volume of biopellets of 50 million tons by 2022.

If we take the technical side of the issue, then all pellets differ in their composition. For example, they can consist of wood alone or contain admixtures of sunflower husks, bark, straw and other combustible materials. In this case, biogranules are used not only as fuel, but also as cat litter.

Thus, equipment for the production of sawdust pellets, with slight improvement, can be used not only for the production of biofuel, but also for the production of various materials from wood waste. Modernization is also important because equipment for the production of pellets must ensure the ash content of finished fuel pellets within 1.5%.

The production technology of this biofuel includes several stages:

• crushing wood into large fractions using powerful crushing plants (if large wood waste is used);
• drying semi-finished products in drying drums to a humidity level of 8-12%;
• crushing wood pulp into small fractions using hammer mills;
• processing of workpieces with steam or water using screw mixers (this stage is necessary for better gluing of granules during their pressing);
• pressing of pellets and their cooling.

It is worth noting that the pellet production plant creates virtually no waste: all rejected and substandard products can be completely recycled.

Some pros and cons

• Combustion is supported by pellets, a fairly inexpensive type of fuel.
• They have a high level of efficiency, which brings their characteristics closer to gas boilers.
• Fuel is supplied to the burner and the temperature is maintained automatically.
• Storing pellets is not difficult, since they are packaged in bags (often thirty kilograms each) and only need a dry room.
• When burned, they leave behind small amounts of environmentally friendly ash.
• The pellet appliance provides the house with both hot water and a comfortable, constant temperature regime.
• They have a smart control system; some system models are designed for remote control.
• Pellet equipment for autonomous home heating is safe and does not require registration with regulatory authorities.

When deciding to buy a good pellet boiler, it is worth paying attention to some disadvantages

• Installation and connection to the home heating system must be carried out by qualified specialists.
• Pellet production is not yet well organized, which may result in fuel shortages.

Pallet boiler

Difference from firewood

When heating with wood, a lot of energy is spent on evaporating moisture.
Both types of fuel are produced from the same materials. But their combustion process is different. This is due to the fact that the firewood is more humid, which is why some of the energy is spent on evaporation of moisture. Only after this does combustion occur. It also contains ash, which is non-combustible ash. Pellets consist of the same parts, but in different proportions. They contain about 5% water, so it will take less time to evaporate, all the energy will be spent on heating.

The density of pellet granules is higher than that of firewood. For this reason, fewer of them are required for heating. When burning 1600 kg of wood, the same amount of heat is released as when using 1000 kg of pellets.