Pyrolysis boilers with automatic loading of pellets. Solid fuel boilers of long burning - myth or reality. The range of pyrolysis boilers on the Russian market

07.05.2020

Comfort and coziness in the house is unthinkable without heat. More recently, the assortment in specialized stores left no choice when buying a heating boiler. One or two stoves were forlornly huddled in shop windows. Now the situation has changed and the buyer is offered the widest range of heating appliances.

Boilers offered by manufacturers today differ in the type of fuel, power, design and many other parameters. Even the unshakable classic solid fuel stoves can differ in the type of fuel used.

There are three main types of solid fuel stoves:

Standard. Where the usual coal and firewood act as fuel.
Pellet. For their work, pressed granules from sawdust, shavings and other woodworking waste are used.
Pyrolysis, or "upper combustion boilers". Such devices are capable of operating on all types of fuel. If everything is more or less clear with the first option, then pellet ones require more careful consideration.

Pellet solid fuel boiler

For the operation of a pellet heating boiler, fuel is loaded directly into the combustion chamber. The loading of pellets into the furnace and their supply to the combustion area are fully automatic. In the furnace itself, the fuel burns as in a conventional solid fuel boiler or in a fire.

A pellet boiler, as the name implies, requires a special fuel for its operation - pellets. They burn with the help of a special pellet burner, where they get through a special screw mechanism. The main advantage of a pellet boiler is the ability to operate without maintenance for a long time.

Depending on the capacity of the hopper, the oven will maintain the temperature for a week or even longer. Compared to conventional boilers that require daily maintenance, this is quite convenient. Pellet solid fuel boilers, despite complex system automation are considered quite reliable and do not require constant repair. However, the automatic fuel loading process has certain disadvantages.

For example, planned Maintenance It is impossible to carry out the boiler on your own, for this you will have to contact the service department. In addition, when buying such a solid fuel boiler, the cost of the pellets themselves should also be taken into account. For the manufacture of granules can be used different kinds wood residues and other materials, which affects the price and quality. Buying pellets now is no problem, the choice is large, but it is better to prefer reliable manufacturers and not save on quality.

It is worth considering that it is undesirable to use pellets made from coniferous wood. this is fraught with resinous deposits on the screw conveyor and the walls of the combustion chamber.

Pyrolysis solid fuel boiler

The design of the pyrolysis boiler is also not simple. Such heater consists of two chambers interconnected by ceramic nozzles. The chambers are stacked one above the other, and the fuel must be loaded into the compartment located on top. Here the fuel will undergo a decomposition process. In its lower part, the fuel is heated to a temperature at which it begins to smolder.

The conditions in the gas generating chamber do not allow firewood or pellets to fully flare up, and pyrolysis gas appears as a result of smoldering. The intensity of the creation of gas from the wood is regulated by a fan, which, if necessary, increases or decreases the amount of air in the lower combustion chamber. The gas resulting from the smoldering process enters the lower chamber through ceramic nozzles. It burns much more efficiently than solid fuels and with less environmental impact.

The combustion temperature of pyrolysis gases can exceed 1100Cº. The principle of fuel separation makes it possible to realize the following advantages of such boilers: low ash content, soot on the heat exchanger and the walls of the combustion chamber remains in a minimum amount. Automatic control combustion process allows to provide high efficiency, more than 90%, and as a result, the interval between fuel loads increases to 15-16 hours. It should be noted that only dry firewood is suitable for use in a pyrolysis boiler.

findings

Comparing the efficiency, price, ease of operation and availability of fuel, we can confidently speak about the advantage of a pyrolysis boiler:

Almost any type of wood fuel is suitable for its operation, whether it be firewood or pellets.
The high combustion temperature of the fuel provides high thermal power boiler.
The main effect is the combustion of pyrolysis gas. Unlike pellet and other solid fuel boilers, gas is much better controlled by automation. This means that the likelihood of a possible breakdown is reduced.

Of course, a pyrolysis-type boiler will initially require a solid cash investment, but over time, these costs will pay off with interest. For boilers intended for industrial use, you need to connect to electrical network. However, power supply is also required for pellet boilers.

Various new products are offered on the market of solid fuel boilers, not so long ago varieties appeared - pellet and pyrolysis. They differ from each other technically, but are similar in one thing - an increased price. What is this money for, what additional benefits can be obtained by paying an increased price for these boilers?

What is a pellet boiler

Pellet is an automated solid fuel boiler. It can work without maintenance for a week or even more in automatic mode. The frequency of maintenance depends mainly on the capacity of the fuel tank that can be selected. Usually it is chosen so that the pellet boiler needs to be loaded no more than once a week. It is comfortable compared to conventional solid fuel.

Pellet boilers, although technically complex, are now considered reliable, there are no massive breakdowns. But complexity and automation entails disadvantages - you can’t serve it yourself, you still have to pay in service department for periodic inspection and repair, sometimes they break down, and repairs cost a pretty penny, winter downtime occurs ...

Pellets are sold by the same organizations that sell these boilers. They accompany their products with fuel.

Is it profitable to use

The cost of a kilogram of pellets is 8 rubles. The energy received from a kilogram of pellets is 5 kW. But taking into account the boiler efficiency of 80% - 5x0.8 = 4 kW. Therefore, 1 kilowatt of energy will cost 2 rubles. And this is at least 1.5 times more expensive than firewood, 1.7 times more expensive than coal (for most regions, but not for all), and moreover, more expensive than the nightly electricity rate - 1, 7 rubles/kWh.

That is, heating with pellets is simply not profitable. But comfortable. It is more convenient than heating a conventional solid fuel boiler, which needs to be serviced at least once a day, and often, if the boiler is not powerful and is not equipped with an accompanying electric boiler and (or) a heat accumulator, then several times a day.

Why do we pay a big price - first we buy an expensive automated pellet boiler, then constantly expensive fuel. Naturally, we pay for comfort.

A pellet boiler should be used if the residents, firstly, are ready to overpay for comfort, and, of course, there is no main gas. And secondly, when the house is large (300 square meters or more) and heating it with wood and coal is simply tiring, and with the daily electricity tariff, there is a big difference in favor of pellets.

In general, when more power is needed for big houses, then the pellets acquire, although not economic, but practical meaning.

What are the features of pyrolysis boilers

Pyrolysis boilers can also be called gas-generating boilers, since gas is generated in them from firewood using high temperature, which is then burned.

Manufacturers praise pyrolysis units and advertise them in every possible way, while stating the following:

You can heat (and sometimes they say you need to!) Wet firewood with a moisture content of 50%.
The fuel burns completely, no ash remains.
The efficiency reaches 89 percent - 10 percent more than a conventional boiler.
Duration of work on one load - a day or more - lengthening the burning time.

Firewood must be dry

Pyrolysis starts on dry wood, which has a moisture content of no more than 20 percent. Those. put wet wood in this boiler, the same as in a regular one, as in a fire - up to 50% of combustion energy is spent on drying moisture.

Water does not burn, it does not decompose into hydrogen and oxygen, it evaporates and takes the lion's share of the power.

Firewood should be placed in the firebox as dry as possible. And they should dry for a long time under a canopy, then, perhaps, in a boiler room near the boiler, above the radiators, if possible, for a week or two. Then the power will be spent not on the evaporation of water, but on heating the coolant.

Ash

Firewood cannot burn completely, ash content is theirs physical property, it will be with any method of burning them. And there is no ash left in the boiler because the fan is running, and light wood ash is carried away by a jet into the sky, and then settles on the heads of users. The area next to such a boiler is simply sprinkled with ash.

efficiency

Big efficiency? Perhaps the heat exchanger of this boiler allows you to get the most out of what firewood can give, but now it works under the influence of a fan. There is a constant purge of the chambers where the firewood is heated and where the released gas is burned. And ventilation takes electricity 50 - 100 watts per hour.

You have to pay for it at the daily rate. And this directly affects the profitability of this boiler. In addition, the heat of exhaust gases given in the characteristics of 150 -200 degrees directly indicates that the boiler does not develop an efficiency of 90 percent.

Duration

The duration of any boiler is determined simply by the amount of firewood loaded at the same time.
In the same way, you can make a long-term operation of an ordinary solid fuel boiler, but powerful, with a large combustion chamber. There you can arrange the same pyrolysis, only by natural draft on a high chimney, stuffing more firewood into the firebox, and covering the air supply so that the firewood smolders.

But at the same time, a conventional boiler can be started at full power at any time, when required, and instantly heat bathing water or raise the temperature in the house.

Pyrolysis

Pyrolysis is the decomposition of organic compounds at high temperatures. With the access of oxygen, the pyrolysis process turns into ordinary combustion. If the access of oxygen is limited, then the hydrocarbon fuel will decompose into low molecular weight combustible compounds and slag. In the case of wood pyrolysis, a mixture of gases of methyl alcohol, acetone, benzene and a small amount other combustible substances and practically pure carbon with impurities of metal oxides.

More recently, charcoal has been widely used as a fuel - a fuel that is obtained by burning wood without access to air in coal pits. Such a traditional one leads to significant losses of thermal energy during primary combustion. A modern solid fuel pellet boiler is devoid of this drawback and is able to fully use thermal energy, which is formed during the pyrolysis of wood. Therefore, such a device is also called a gas generator.

The principle of operation of the boiler on pellets

Boilers long burning on pellets consist of three separate mechanisms:

directly from the boiler with a burner;
conveyor for feeding granules;

The pellet boiler operates as follows:

pellets are loaded into the fuel bunker;
pellets are fed into the boiler by a screw conveyor;
pellets burn in the boiler furnace and heat up the coolant.

Pellet boilers use the top-down principle of fuel combustion. At the same time, combustion is much slower than in a conventional furnace, where the fuel burns “from bottom to top” and the circulating heated gas flows involve layers of fuel that are higher in the process. Structurally, this is solved as follows.

In the furnace itself there is a burner with a nozzle for supplying heated air directly to the combustion zone. Thanks to this, it becomes possible to control the rate of fuel combustion by moving the fire zone gradually down. The supply of heated air makes it possible to burn the fuel in the most complete way. At the same time, ash and soot are formed in a minimal amount, and the efficiency (efficiency factor) of boilers operating on pellets increases to 96%.

This mechanism of operation ensures the gradual combustion of fuel. Boilers of long burning on pellets can work on one tab for more than a day, which makes this equipment quite convenient for household use. In addition, the presence of a fuel bunker in the equipment design makes it possible to automate the operation of heating equipment as much as possible.

Construction and internal arrangement

Boilers are similar in design to general scheme, according to which all solid fuel boilers are manufactured. However, they have some features. For example, the size of the furnace for these models is much smaller, since their heat exchanger is heated not so much by an open flame, but by hot air in the convection channels. This allows more complete use of thermal energy. The temperature of the exhaust gases in equipment of this design usually does not exceed 150 degrees Celsius.

The furnace of the pyrolysis boiler on pellets is designed with the calculation of the possibility of controlling the air supply to it. The presence of a fuel bunker allows you to control the supply of pellets to it with the ability to adjust the speed and temperature of combustion. Due to this, it is possible to control the heating temperature of the coolant in the system. Structurally, this is solved by installing a screw conveyor, which directly supplies fuel.

For the manufacture of boilers for heating on pellets, high-strength steel alloys are most often used. The furnace and heat exchanger are made of corrosion-resistant cast iron. It should be noted that the service life of cast iron boilers can reach 45 years, which is much longer than the performance of equipment made of steel.
Pellet granules are ignited with the help of a special electric heating element. Air is blown into the furnace by a fan. After the equipment enters the operating mode, the electrical circuit is turned off. Thus, pellet boilers consume very little electricity.

Automatic operation

Modern models of long-burning pellet boilers are necessarily equipped with automation that feeds pellets into the furnace according to a specific program, and also turns the burner on and off to save fuel consumption and maintain a given temperature regime, which can change during the day. The control panel is located on the boiler itself or on the remote control.

A medium-sized 25 kW pellet boiler with a fuel consumption of approximately 5 kg of fuel per day is equipped with a hopper with a volume of 250 to 350 liters. Thus, completely continuous automatic operation equipment can be carried out for at least three days. With the installation of an external hopper, this time can be further increased.

Construction of the outer bunker

Due to the fact that the supply of pellets to the boiler is metered, the burner does not overheat and all equipment can be turned off remotely by stopping the fuel supply. In this case, the boiler will automatically stop working after a few minutes, when the loaded dose of pellets is completely burned.

Equipment cost and customer reviews

In general, the price of solid fuel boilers is not the strongest point of this equipment. The fact is that pellet boilers are significantly more expensive, for example, gas equipment the same power. Nevertheless, significant operational savings due to the availability and cheapness of fuel provide it with a high demand.
If we talk about the price level, we can cite the following data. Pellet boiler Zota ( Russian production) with a capacity of 15 kW costs approximately 150 thousand rubles. The price of the most powerful (with a capacity of 100 kW) is about 350 thousand rubles. The owners of these boilers note that the cost of one kW of thermal energy costs no more than 1 ruble. (subject to the purchase of fuel at a price of up to 4.00 rubles / kg).

The pellet boiler Grandeg (manufactured in Latvia) with a capacity of 25 kW is sold at an average of 250 thousand rubles. A 100-kilowatt boiler from the same manufacturer will cost 500 thousand rubles.

If we analyze the reviews of the owners of this equipment, it can be noted that they all confirm the significant cost-effectiveness of this type of heating equipment and ease of use. A pellet boiler house for one heating season will save tens of thousands of rubles on fuel alone.

In addition, pellet boilers are distinguished by their quiet operation and ergonomic design.
Some owners complain that this equipment needs to be connected to the mains in order to work. However, such devices consume very little electricity.

The price of pellets is about 5500 rubles per ton, i.е. one kilogram, on average, costs about 5-6 rubles. If necessary, you can set up the production of pellets by purchasing necessary equipment or do it yourself.

The video below shows how a pellet boiler works.

It is rightly considered that European pellet boilers are the best in their class of heating equipment. Although, recently several competitive Russian models have appeared, the domestic manufacturer is not yet able to create a boiler that will be identical in its parameters to the same “Germans” or “Czechs”.

European manufacturers of pellet boilers

Solid fuel boilers on pellets from Europe, available to domestic consumers for more than 10 recent years. During this time, manufacturers have studied the Russian market well and began to offer equipment that is more adapted to the operating conditions and the wishes of customers.

European heating boilers on pellets differ in the following parameters:

Profitability.
Reliability.
Minimum harmful emissions into the atmosphere when fuel is burned.
Automation of the combustion process.
Long service life.

The largest foreign manufacturers of pellet equipment are located in Germany, Italy, Poland, the Czech Republic, Austria and Finland. Below is a description of the most popular brands.

German pellet boilers

The leading manufacturers of pellet boilers in Germany are Buderus and Viessmann. The factories of the companies produce wide range of water-heating equipment and components necessary for the installation of heating systems. At the moment, the products of German manufacturers have no competition in terms of quality and reliability:

German pellet boilers are distinguished by traditional build quality, reliability and full compliance with the parameters specified in the technical documentation. All products are covered by a factory warranty.

Italian boilers for pellets

Italian pellet boilers are somewhat inferior in performance and reliability to their German counterparts. Favorably stand out due to the versatility of the proposed equipment. The most popular products of the following companies:

Italian manufacturers produce autonomous pellet boilers designed for simultaneous heating of heating and hot water systems, controlled by intelligent automation, operating on almost any type of fuel.

Polish pellet boilers

Boilers made in Poland are presented in the lowest price segment. At the same time, the produced equipment is reliable and productive. The most popular are two brands of equipment - Defro and Kostrzewa:

Polish pellet boilers have earned a reputation as reliable and unpretentious equipment with a high degree of automation and control.

Positive feedback about Polish boilers, are gradually bringing Kostrzewa and Defro products into the class of the most demanded pellet equipment.

Czech pellet boilers

From the product range of Czech manufacturers, boilers manufactured at the OPOP and Benekov factories stand out in particular. In terms of performance, reliability and cost, the equipment is similar to German units:

The Czechs produce economical, distinguished by a well-thought-out design and the absence of everything superfluous, pellet boilers. AT summer time, models are able to work on heating hot water.

Austrian pellet boiler

There are not so many Austrian companies for the production of pellet boilers, but they all enjoy continued popularity due to the high efficiency of the equipment offered. The low costs of pellets, together with high heat transfer, made it possible to bring the cost of heating on pellets closer to the main gas:

Despite the initial costs, it is profitable to purchase Austrian heating equipment, due to the economical costs of pellets during operation. All overpayments will fully pay off in a few years of service.

Finnish boilers on pellets

Finnish pellet boilers are not as well known to the domestic consumer as Italian and German units. Manufacturers from Finland are mainly associated with sauna heaters and solid fuel boilers for domestic and industrial purposes:

Finland produces equipment "without frills", designed for domestic operating conditions, productive and reliable.

Pricing policy for pellet boilers from Europe

The main disadvantage that distinguishes imported pellet boilers has always been their high cost. Compared to domestic units with similar characteristics, the price is often 2-3 times higher. The average cost for boilers is as follows:

Pellet boilers from Finland for 30 kW will cost 360 thousand rubles. However, when choosing, it must be taken into account that the design does not provide for an automation system, remote control and other additional options.
German pellet heating boilers for long burning - for full automation of the combustion process, self-cleaning system and others functionality, you will have to pay up to 500 thousand rubles. (boiler for 30 kW Buderus).
Polish-made pellet boilers - a fully autonomous 25 kW thermal power plant manufactured by Kostrzewa, will cost approximately 280-300 thousand rubles. The cost is given taking into account the simultaneous purchase of the Fuzzy Logic 2 logic control system.
Czech-made pellet boilers - offered for about 320 thousand rubles. with the usual set. Additionally, you will need to purchase a silo to increase battery life, a controller for remote control, etc.
Boilers for pellets from Austria - a price target from 280-320 thousand rubles. depending on the manufacturer and basic configuration. It is possible to connect a built-in tank for heating hot water (purchased separately).

The lowest prices for boilers are traditionally offered by Polish manufacturers. For 280-300 thousand rubles. you can buy a fully equipped, automated and ready-to-work station.

The German units will cost the most. Moreover, the cost is higher than the average price level, by 150-200 thousand rubles. than other analogues.

Another country that “spoils” the domestic consumer with “cheap” products is Italy. Pellet boilers, the same FACI, for 30 kW will cost only 200 thousand rubles.

Are the "Europeans" demanding on the quality of pellets

The operating instructions expressly state that wood pellets for heating boilers must meet the following requirements:

woody origin.
First grade.
The maximum percentage of ash content is not higher than 2-3%.
White color.

Industrial and vegetable pellets burn poorly, leave a large number of soot. European boilers quickly fail, as they are not designed for this type of fuel.

If you plan to use low quality pellets, it is better to choose heating equipment adapted to Russian conditions. Finnish units are suitable, as well as domestic counterparts.

Manufacturers reserve the right to refuse warranty service if it is proved that the boiler was fired with low-grade pellets.

Which pellet boiler is better, ours or imported

Why are imported pellet boilers better than analogues offered by a domestic manufacturer?

Automation of the combustion process - unfortunately, Russian manufacturers often have flaws that affect the operation of the equipment. If you take similar units from the same "Germans", the boilers work without failures.
Thermal efficiency - fuel consumption in imported pellet boilers is 10-15% less than that of Russian counterparts. In some models, the savings are even greater through the use of modulating burners and condensing units.
Fuel quality - in this respect, domestic units win, which are distinguished by "omnivorousness".
Cost - European models of "western" assembly are 2-3 times more expensive than Russian products. The exception is the Italian FACI, assembled in the territory of the Russian Federation. The cost of such units is not higher than that of Russian heat generators.

European manufacturers offer truly high-quality products with a high degree of automation, but at a high cost. In terms of thermal performance, boilers have almost no equal among Russian counterparts.

For many owners country houses one of the main tasks is to reduce the cost of their maintenance. This is especially true for those buildings where sewerage, heating and water supply systems operate offline. In the heating system, the installation of a solid fuel pellet boiler helps to reduce the cost of providing the house with the necessary amount of heat.

Such boilers appeared relatively recently, but they have already managed to occupy their niche in the boiler equipment market. Consumers are attracted by the relatively low cost of pellet boilers, the availability of fuel material and ease of maintenance, due to the automation of the heating process. Pellets are used as fuel, which are granules consisting of wood waste: pressed wood chips, chips, shavings.

Design and principle of operation

The pellet boiler consists of a fuel bunker, automation and a burner. Pellets are delivered to the pre-furnace via an external screw, and from it, via an internal screw, they are fed to the burner nozzle. After the granules hit the nozzle, automatic ignition and fed pellets are burned completely.

In terms of calorific value, burning 1 kg of pellets is comparable to half a liter of diesel fuel and amounts to 5 kW / h. When compared with firewood, due to the high density of the pellets, their combustion occurs much more efficient and productive excluding the possibility of spontaneous combustion. In addition, ash cleaning can be done much less frequently, reducing this process to once a week. When using pellets as fuel, carbon dioxide emissions into the atmosphere are reduced, which leads to a decrease in the greenhouse effect.

Installation of a pellet boiler requires compliance some rules due to which it will be possible to avoid possible alterations during its operation:

it is more expedient to install the boiler in a separate room, for example, a basement or an extension;
the floor covering in the boiler room must be made of ceramic tiles or concrete;
in the room that will be used as a boiler room, there must be enough free space for the possibility of repair and maintenance of the boiler;
the room must be dry, well ventilated, with a constant temperature in the range of +10 0 С.

An important indicator for any type of boiler equipment is its efficiency. In order to more clearly imagine the efficiency of a pellet boiler, let's compare it with other equipment used for heating a house. So the efficiency of wood is in the range of 35%, natural gas - 87.1%, electric energy is 97%, and incinerated pellets in the range from 86% to 93%, depending on the model of the pellet boiler.

This material will help to make a solid fuel boiler:

Automatic control mode

Pellet granules are stored in stand-alone bunker which is connected to the combustion chamber. Automation allows you to set a weekly program for feeding pellets into the boiler. In addition, according to the set program, the automation will turn the burner on or off, which saves fuel consumption and maintains the set temperature regime depending on the time of day. Operation can be done either with the remote control or using the buttons on the display.

The bunker with a volume from 200 to 300 liters provides continuous operation of the boiler for three days. For the uninterrupted operation of a medium-sized boiler in the range of 25 kW, the daily rate is 5 kg. It is possible to install an external bunker, which will greatly increase the amount of pellet loading, thereby increasing the boiler's operating time without your intervention. Responsible for the operation of the burner control system, granules are fed into the combustion chamber in small batches, which eliminates the possibility of overheating. If you want to turn off the boiler, then after pressing the function button, its operation will automatically stop after 5-10 minutes, which is required for complete combustion loaded batch of pellets.

Environmental Safety

Thanks to special design of pellet boilers, the ecology of your premises is not threatened. In them, the circuit through which air is supplied for complete combustion of the fuel is located separately from the circuit through which the room is heated. Due to this design, there is no " burnout» oxygen and therefore you will always feel comfortable. Some users additionally take air from the boiler room, thereby drying and ventilating it. In addition, to benefits pellet boilers include the following factors:

energy-saving and low-noise fan, able to provide uniform effective circulation of warm air;
low level of electricity consumption, within 60 watts, for the operation of automation and a fan;
small amount of ash and soot, in comparison with solid fuel boilers for wood;
the boiler body does not heat up, so it is absolutely safe for animals and small children;
implementation automatic fuel loading from the bunker;
intelligent control system, timer and thermostat control and ensure continuous operation of the boiler, depending on the set program.

Disadvantages of pellet boilers

Speaking about the advantages of this type of solid fuel boilers, it is worth mentioning their disadvantages.

despite the fact that pellets are made from wood waste, the unit of heat released will cost more when compared with wood-burning boiler equipment;
store pellets required in a dry room, since under the influence of moisture they begin to swell and fall apart due to which the screws clog
for offline operation in remote suburban areas you will need to purchase a generator and additional equipment, what can make the purchase of a pellet boiler an expensive pleasure;
consumption of granules per month can be about 1 ton. Knowing the price of pellets in your area, it is not difficult to calculate how much heating will cost you. country house in winter period. As practice shows, your costs will be comparable to using electric boilers and exceed the costs if you use natural gas as fuel.