In this article we will analyze the principle of operation of a pyrolysis boiler long burning, let’s read the reviews from its operation and see which manufacturers are ready to offer the best models.
Each type of boiler, be it solid fuel, gas or liquid fuel, has its own advantages and disadvantages. Liquid fuel boilers have expensive fuel, electric ones are constantly dependent on the network... At the same time, owners of gas boilers note low cost fuel. But a design of this type implies a high danger, so their installation and maintenance are carried out by specially trained people.
You can find out the price and buy heating equipment and related products from us. Write, call and come to one of the stores in your city. Delivery throughout the Russian Federation and CIS countries.
Owners of boilers solid fuel They know that fuel is not difficult to get: firewood and peat are available in almost all residential regions. However, their maintenance requires constant fuel supply, cleaning and constant attention to safety precautions. But a long-burning pyrolysis boiler can help solve these problems.
Pyrolysis solid fuel boiler
Operating principle
A modern and universal option can be a long-burning solid fuel pyrolysis boiler. Like another unit, it can be used for heating residential premises and hot water supply, heating greenhouses or providing heat for industrial and public areas.
The pyrolysis boiler is economical; it is enough to refuel it 2-3 times a day. Much depends on the fuel and the temperature outside the window. It can be single-circuit or double-circuit, which allows you to build various schemes heating and hot water supply systems.
It can work efficiently on many types of solid fuel: brown and black coal, wood, peat, etc. The combustion time of raw materials for a gas generator boiler can be seen in the table.
If these types of fuel are not available or cannot be purchased, then any organic fuel can be used.
The most effective raw material for a pyrolysis boiler will be dry wood: it increases the operating time of the pyrolysis boiler and makes its operation more productive.
Long-burning pyrolysis boilers operate by decomposing carbon-containing fuel in the absence of oxygen into a huge amount of flammable substances and gases. Because of this, the devices are also called gas generator boilers.
Wood (carbon-containing raw materials) can decompose into a solid residue (charcoal), acetone, resins, methyl alcohol and acetic acid.
How does a pyrolysis boiler work?
The substances combust and release huge amounts of calories. Because of this solid fuel boilers pyrolysis combustion has two chambers. One chamber is designed for loading fuel and ignition. The other is the afterburner. It removes gases that were released during the combustion of raw materials. Since the gases have a high temperature, they mix with the incoming air and ignite. Air is supplied to both chambers separately and, depending on it, the combustion force and power changes.
The design of the pyrolysis boiler can be different: in some models the afterburner chamber is located under the primary one, in others - on top:
- The first case is when the camera is at the top. These are the most common designs, simple and easy to use. Since the fuel raw material is located at the top, the exhaust gas exits through the pipe located at the bottom. Such a pyrolysis combustion boiler will have to be cleaned of ash from time to time, because ash can get into the afterburner.
- The second case is when the camera is located at the bottom. A less common option, but at the same time has its advantages. In contrast, such units do not need to be cleaned of ash. The gas rises here and, using a nozzle, enters the chimney and cools.
Comparison of pyrolysis and conventional solid fuel boiler
If you decide to make a long-burning pyrolysis boiler with your own hands, then keep in mind that for the design you will have to purchase all the necessary materials and components. Plus, experience in this activity, tools and drawings.
User reviews
Owners pyrolysis long-burning boilers are noted for their environmental friendliness, good boiler performance and their high efficiency(on average 85%, compared to direct combustion boilers, where the efficiency is about 65%).
Pyrolysis boiler Buderus Logano S171 W
Another difference is that a wood-fired gas generator boiler saves about 40% of fuel. The pyrolysis process can be controlled: if desired, set the power to 30% or turn on the unit at 100%. This ultimately improves fuel efficiency.
Here, the entire setting is regulated by automation, focusing on the specified standards. As an example for comparison - an ordinary boiler. Its power is conditionally regulated manually: open or close doors, dampers, blowers.
Users of such boilers note a long fuel burning time and an almost complete absence of waste. Logs can be used without being chopped.
Among the disadvantages, owners of pyrolysis boilers point to the high cost of the units and their constant dependence on electricity, as well as the need to use dry wood.
When purchasing a pyrolysis boiler, you need to consider the following parameters:
- Boiler efficiency. According to this criterion, the best manufacturing companies are Viessmann, Buderus, Biasi, Dakon, Atmos, Ferroli, Viadrus.
- What material is the heat exchanger made of?
- Is it possible to use additional fuel without changing it, as well as which main fuel and which additional (there can be various combinations, for example, wood-pellets, wood-coal, etc.).
- Is it possible to re-equip the boiler when changing the burner?
Pyrolysis boiler Atmos DC 15 E
Review of pyrolysis boiler manufacturers
There are many models of long-burning pyrolysis boilers on the market. Foreign and domestic manufacturers offer heating devices of various configurations and prices. All units differ in performance characteristics, which are described in the table below (some of the popular manufacturers are noted).
| Manufacturer | Characteristic |
|---|---|
| Blago | The peculiarity of this gas generator boiler is its extreme energy independence. The unit operates on natural draft, and not on artificial air supply. It assumes the possibility of heating with various types of fuel (firewood, wood chips, sawdust, scraps, old tires, leather, rubber, polyethylene), and can work on raw wood (with humidity up to 50%) without loss of power. If the design is of low power, then it can cope with humidity up to 30-35%. The power of the models ranges from 12 to 58 kW. The company claims that the unit requires on average 25% less fuel compared to other boilers with the same operating mechanism. Fuel is added to them every 12-18 hours. High safety is guaranteed, and ease of use is obvious: automatic control, automatic cleaning of fuel channels and no smoke. You can select a boiler of the required power based on the area of the heated room:
|
| Atmos | This is a Czech company that produces more than two hundred models of heating boilers. The units burn wood, liquefied gas. Eat combi boilers, and a gas boiler can be made to order. The Atmos company produces units with a power ranging from 15 kW, which are suitable for areas of 90-180 m², up to 1000 m² and more for industrial premises. Pyrolysis boilers long-burning boilers can operate on wood, in which case they are marked as Atmos DC, those operating on coal and wood - Atmos C and Atmos AC, pyrolysis boilers are marked as Atmos DC 24 RS, DC 30 RS, and pellet boilers - Atmos. Boiler markings also contain the prefixes GS, GSE and S. The first two types have an all-ceramic finish on both fireboxes. Due to this, the efficiency becomes higher, and the percentage of carbon dioxide emissions into the atmosphere is significantly lower. |
| Bosch (Bosch) | They are distinguished by the possibility of wide power adjustment. Their efficiency is on average 80%, and the volume of water in the system is 76-124 liters. Can work on wood up to 25% humidity. The manufacturer produces three main types of boilers:
|
| Viessmann | This is a stable company that has been producing products for over a hundred years. Today the manufacturer has competitive advantages in the production of equipment for heat supply systems. Viessmann boiler equipment is popular in enterprises and in country houses, apartments and cottages. Wissmann products are premium products, the quality of which corresponds to its price, as well as norms and standards. It is extremely economical, has high level safety and comfort in operation. |
| Dakon (Dakon) | The power of pyrolysis boilers from this manufacturer ranges from 18 kW to 40 kW. All units are environmentally friendly and economical in their operation (combustion in a chamber with a ceramic nozzle increases the efficiency sometimes up to 85%). The maximum moisture content of solid fuel reaches 20%. The Dakon pyrolysis wood boiler has a large raw material loading chamber. This helps to increase the boiler operating time without supervision. The unit can burn logs with a diameter of no more than 130 mm. The maximum length of logs varies depending on the size of the firebox in a particular boiler model. |
Thus, a pyrolysis boiler makes it possible to achieve ease of use of a solid fuel unit due to long-term combustion of fuel.
Combustion of fuel in classic solid fuel boilers is a good alternative to using traditional energy sources such as natural gas or electricity for home heating. But these devices do not fully utilize the energy of wood combustion. When a conventional boiler operates, the gas released from the fuel at high temperatures simply goes outside along with the combustion products. Operating principle of a pyrolysis boiler allows the use of this gas, thereby increasing the efficiency of the unit and the duration of the interval between fuel loadings. Such devices are also called gas generators.
What does a gas generator set consist of?
The main difference from a classic wood-burning boiler is the presence additional camera combustion, in which the afterburning of the released gas occurs, and in the primary firebox it is generated from firewood with an insufficient amount of oxygen. The layout of the chambers and the design of the pyrolysis boiler can be different, the firebox can be located either below or above, this does not change the principle of operation. Traditionally, it is located below, above the ash pan, into which a drawer is placed for ease of cleaning. The ash pan lid tilts up and in operating mode serves to regulate the amount of air entering the firebox. This is realized using a chain drive, which is tensioned or released by a thermostat. The latter is installed at the top of the boiler.
All the main elements and details of the installation can be seen by studying detailed drawing pyrolysis boiler. The main firebox is equipped with a door for loading firewood and is tightly closed during operation. Above it is a secondary combustion chamber in which air supply devices are located. They can have different configurations in devices different manufacturers, but their task is the same: to supply heated air into the afterburning chamber through many holes of a certain diameter. The air is heated along the path from the ash pan door to the distributors.
The design of the pyrolysis boiler provides for the possibility of cleaning the upper afterburning chamber; for this purpose it is equipped with a special door. The spaces of both chambers are connected to each other by a channel through which gases rise for combustion. The outer shell of the housing is a water jacket, heated by both fireboxes. To supply coolant to the heating system, threaded pipes are cut into it. Water temperature and pressure are controlled using instruments installed on the front panel.
The chimney for a pyrolysis boiler is no different in design from the pipes for the emission of combustion products of classical units. One of the requirements is sufficient draft for the boiler to operate. Most simple design The unit does not provide for the installation of a blower fan, so combustion occurs due to natural draft. The second requirement is that the part of the pipe located on the street be insulated. The reason is the low temperature of the flue gases (up to 150 ⁰C), so there is a very high probability of condensation forming on it and rapid destruction of the pipe material.
Description of the operation scheme of pyrolysis boilers
A complete picture of the operation of the unit can be given by circuit diagram pyrolysis boiler. First, the main firebox is loaded with fuel and ignited. In this case, the ash pan damper is open as much as possible. After the firewood starts to burn, the door begins to close, the burning process slows down and turns into smoldering. Then the intensive release of wood gas begins, which rises and enters the secondary afterburning chamber. Heated air is supplied there through many calibrated holes. The latter enters the channel from the same opening under the ash pan lid and along the way receives heat from the hot wall of the firebox.
The entire technological process proceeds thanks to the natural draft created by the chimney, so the speed of movement of air and flue gases in the channels is low. The operating principle of a pyrolysis boiler is that in the secondary chamber, heated air enters into a thermochemical reaction with wood gases and ignites them. As a result, not only gases are burned, but also small volatile particles, making the smoke from the chimney almost invisible. In fact, pyrolysis fuel combustion is more environmentally friendly than traditional combustion, since its combustion products contain much less carbon and nitrogen oxides, as well as ash particles.
The firewood in the firebox burns more slowly than usual, so one load can be enough for 10–12 hours of operation, depending on the power of the gas generating unit and the moisture content of the wood. Setting up a pyrolysis boiler involves limiting the supply of combustion air. Too little of it will not allow the thermochemical process to begin in the secondary furnace, and too much will cause incomplete combustion of gases and a decrease in the efficiency of the unit. For a device operating on natural draft, the air flow will need to be adjusted in each individual case, since the height and diameter of the chimney pipe can vary greatly. Accordingly, the traction force will be different. In some cases, it should be increased by raising the pipe to a greater height.
If the chain drive of the ash pan lid is equipped with a thermostatic regulator, then setting the device is reduced to setting the desired coolant temperature. The thermocouple, built into the water jacket of the gas generator, acts on the chain drive depending on the water temperature and closes or opens the damper itself, regulating the combustion intensity.
To create artificial draft that will not depend on the parameters of the chimney, pyrolysis-type boilers are additionally equipped with a blower fan and an automation kit that regulates its operation. If a conventional unit can operate with an efficiency of about 85–90%, then a blowing machine helps to develop it to 93%. There is a disadvantage here - dependence on external energy sources.
Advantages and disadvantages
Heat sources of this type have many advantages:
- The principle of operation and operation of pyrolysis boilers makes it possible to achieve excellent efficiency indicators when burning solid fuels - 90–93% efficiency.
- The process is more environmentally friendly, and much less is emitted into the atmosphere harmful substances.
- The interval between fuel loadings is no less than for long-burning units - 12 hours; you will have to work as a fireman no more than 2 times a day.
- Maintenance and cleaning of the unit are not a problem, the entire interior space is accessible, and many units are equipped with drawer ash pit. The principle of operation of the pyrolysis boiler is practically waste-free; very little ash and ashes remain, so the operation must be performed infrequently.
- Economical. Approximately fuel consumption per 100 m² of premises with a height of up to 3 m is 10 kg per day.
- Installations operating on natural draft do not depend on the availability of electricity in the network.
Like any other device that runs on solid fuel, a pyrolysis heating boiler needs protection from boiling of the coolant inside the water jacket. This can lead to shell rupture and costly repairs. For this reason, manufacturers install additional water cooling heating elements on their products, which can simultaneously serve as a source hot water for household needs.
The disadvantages of pyrolysis-type units include the following:
- Fuel with a low moisture content is required; the moisture content of firewood should not exceed 25%. The process of intensive release of gases for afterburning is very difficult if the firewood is frankly damp. This negatively affects the operation of the pyrolysis boiler, reducing its efficiency.
- Operating practice shows that deposits of tar and resins appear on the walls of the primary chamber over time, since the temperature in it is relatively low, and birch or wood is most often used as fuel coniferous species. This deposit must be removed periodically; it makes it difficult to transfer heat to the water jacket.
- The cost is higher than that of a classic solid fuel boiler. This is justified, because the process technology is more advanced and gives high performance that will allow savings during operation.
Conclusion
When choosing a heat source for your home, it is better to focus on products of medium price category, you shouldn’t save much in this matter. After all, the comfort and warmth of your home depends on how the pyrolysis boiler works.
Modern solid fuel boilers increasingly use the pyrolysis process in their operation. The operating principle of heating equipment is based on the ability of wood, when burned, to release large amounts of carbon dioxide.
A long-burning pyrolysis boiler accumulates heat obtained during the combustion of fuel from wood or its waste and afterburning of the released gas.
How do pyrolysis boilers with long burning times work?
A long-burning solid fuel pyrolysis boiler differs from classical heat generators in several design differences and internal device. The changes affected work processes, combustion chamber and smoke channel.As a result of modifications and design solutions, the following advantages and characteristics were achieved:
- Operating time from one fill of fuel is from 8 to 120 hours, depending on the model and fuel quality.
- Reduced wood consumption - compared to the classic version of the boiler, fuel costs have decreased by 15-20%.
- Adjustment accuracy - the operating principle used and the automation used provide precise adjustment of the heating medium heating intensity, with an error of no more than 1°C.
- High heat transfer - the efficiency of pyrolysis models varies, depending on the quality of the fuel and the manufacturer, in the range of 80-92%.
What is the process of fuel pyrolysis
The operating principle of a long-burning pyrolysis boiler is based on natural physical processes and properties of wood:- Wood, when heated, begins to release carbon dioxide.
- When mixed with oxygen, it becomes flammable gas-air mixture CO, which under normal conditions, simply goes out into the chimney.
- Long-burning steel solid fuel pyrolysis boilers with a water circuit are equipped with a special afterburning chamber. The produced gas is sent to an additional furnace, where it burns at a temperature of 600-800°C.
Design features of pyrolysis boilers
The long-burning pyrolysis heating boiler with a water circuit differs from classical equipment models in several features:- Loading type - all boilers are equipped with an enlarged firebox with vertical or horizontal loading. The large capacity of the combustion chamber helps to increase the time of the pyrolysis process. About 20 minutes after lighting, the boilers operate as usual. After heating to a temperature of 600°C, pyrolysis combustion begins.
- Firebox design - the design includes two combustion chambers. The main firebox has convection holes for air intake and uniform distribution. The afterburning chamber is lined with fireclay to maintain a high temperature.
- The design of the heat exchanger - long-burning household pyrolysis boilers using solid fuel, uses the heat released during combustion as efficiently as possible. Combustion as such, in the full sense of the word, does not occur; wood smolders with limited air supply and high temperature. Flue gases are directed into the broken smoke channel of the boiler. The heat exchanger surrounds two combustion chambers and a duct. Progressive technologies make it possible to accumulate most of the heat coming from heated smoke.
- Heating the coolant – models with a long burning time heat the coolant using a flow method. Boilers have one or two circuits. The first heating circuit is designed to be connected to the heating system. Through the second, water for domestic hot water is heated. The technical characteristics of the boiler, in particular productivity, largely depend on the presence of a hot water supply coil. In dual-circuit units, the power is less.
- Air supply control – boilers are equipped with natural or forced air supply. Non-volatile models are controlled by mechanical ones connected to the ash pan door. Installation of automation connected to smoke exhausters and blower fans ensures precise combustion control.
Dependence on electricity, solved by installing a source uninterruptible power supply. The voltage consumption in boilers is 150-300 W/hour.
Is it possible to increase the burning time of a pyrolysis boiler?
The operating time of a pyrolysis boiler depends on several factors, taking into account which you can extend the operating time from one load:
Factory-made briquettes, wood chips and sawdust have a moisture content of 8-18%, which is the optimal moisture content for the pyrolysis process.
Which pyrolysis boiler is better
According to the statistical report, regarding sales of pyrolysis models of heating equipment, boilers from European manufacturers remain the most popular. Even the high cost of the models, which is 2-3 times higher than their domestic counterparts, does not affect their popularity.
A short review of long-burning pyrolysis heating boilers using solid fuel helps to identify models in demand by domestic consumers:
- German boilers - the leaders in popularity are the German Buderus, Viessmann, HDG. The assortment includes both completely autonomous boilers and manually operated equipment.
- Czech boilers - Wattek company offers energy-independent heating equipment for domestic use. The products became available to domestic consumers relatively recently, but are already popular.
- Russian equipment - pyrolysis boilers are represented by the brands Burzhuy K, Trayan, Geyser, Termofor, Divo. The difference between the equipment is the ability to work on wood with a high moisture content. Most models are universal.
- Bulgarian boilers are not widely used. A Russian buyer was able to evaluate Burnit boilers from Sunsystem. There are no other competitive models made in Bulgaria.
- Co-production – several Russian manufacturers established joint production with European manufacturers. One of the most popular models are Lavoro boilers, manufactured by an Italian-Russian concern.
How much do pyrolysis boilers cost?
To select a pyrolysis boiler, you need to take into account not only technical specifications and productivity, but also its cost and further maintenance costs.Low-power boilers, up to 20 kW, depending on the manufacturer, cost from 60 to 350 thousand rubles. The German Buderus and Wismann are the most expensive.
Domestic Termofor and Burzhuy-K belong to the middle price category. Czech Watteks are expensive, almost like their German counterparts, which somewhat limits their popularity.
Requirements for the installation site of a pyrolysis type boiler
Requirements fire safety to pyrolysis heating equipment the same as for all other solid fuel boilers. When installing, comply with the rules of industrial safety and industrial safety:- High power boilers, over 40 kW, are installed in a separate room. Installation of equipment with lower productivity is allowed anywhere in the house.
- Before installation, prepare the base. Due to the presence of two combustion chambers, the weight of the boiler reaches several centners. Due to the large mass of the unit, a foundation is required.
- When the chimney passes through the floor slabs and roof, a special fireproof cut is made.
- The floor and walls are lined with non-flammable finishing materials.
Opinions and reviews on pyrolysis heating boilers
You can find a variety of reviews from owners about long-burning pyrolysis boilers. Moreover, there are directly opposite opinions: from enthusiastic praise to extremely negative statements:- Harm to human health from the operation of a pyrolysis boiler. One of the most serious concerns regarding the negative impact of equipment on humans is unfounded. In the operation of the boiler, only natural physical laws are used.
- Efficiency and heat transfer are significantly exaggerated. To achieve maximum thermal efficiency, it is necessary to use wood and waste with a maximum moisture content of up to 20%. Improper operation leads to a decrease in heat transfer.
There are many types of heating boilers. I would like to note that today the most popular and high-tech boilers are long-burning pyrolysis boilers. They have a more spacious firebox compared to other boilers, so there is no need to frequently add fuel.
In this article I will present detailed description about the types of pyrolysis boilers, features of their operation and much other useful information.
Long-burning pyrolysis boilers with a water circuit are an excellent alternative source of energy in private homes in conditions of frequent gas supply interruptions.
A long-burning solid fuel boiler with a water circuit can operate on wood and other types of solid fuel: coal, wood waste, etc.
The main disadvantage of this type of boiler is the high price. In addition, unlike many other types of boiler equipment, a long-burning pyrolysis boiler with a water circuit is most often energy-dependent.
Not only are they powered by electricity circulation pump and control devices, but also a built-in fan: this equipment, as a rule, does not work on natural draft.
Solid fuel wood and coal boilers In popularity they are second only to gas ones. However, they have one serious drawback - fuel must be loaded several times a day.
During normal combustion of wood, the efficiency of boilers does not exceed 75%, and some of the flammable substances simply fly away into the chimney.
Long-burning pyrolysis boilers with a water circuit are much more practical and efficient.
It will not be a secret to anyone that pyrolysis heating boilers are currently very necessary and in demand heating system devices. It is for this reason that many of our people have become interested in these particular units.
A pyrolysis boiler is a special heating boiler that can use pallets, coal, wood, and other materials as fuel.
One of the main criteria, depending on which they subdivide heating boilers, is the type of fuel they run on. Thus, in today’s market you can find boilers based on pallets, coal, and wood. You can also find so-called universal boilers for yourself.
The most common at the moment are wood-burning solid fuel boilers, which have many advantages. The first is that fuel is considered the most affordable. It should also be noted that such boilers are sold at reasonable prices.
A distinctive feature of pyrolysis boilers is control of the oxygen level in the combustion chamber, and accordingly control of the temperature and rate of fuel combustion. A solid fuel pyrolysis boiler will ensure your independence from gas and electricity, since the costs of these energy sources significantly exceed the cost of solid fuel.
Design Features
Pyrolysis boilers are one of the types of solid fuel boilers, which have recently been in increased demand due to constantly rising prices for gas and electricity; they are also called gas generator boilers.
The main fuel for a pyrolysis solid fuel boiler is:
- wood;
- briquettes;
- wood chips;
- wood waste.
Very rarely used as fuel coal or coke. Pyrolysis boilers are easy to use, reliable and have a long service life. Before buying a pyrolysis boiler, you need to study the possibility of meeting strict requirements for the quality of the fuel used.
In the vast majority of cases, it is allowed to use wood with a moisture content of no more than 20%. When using wood with a large amount of moisture, efficiency decreases sharply.
The pyrolysis boiler operates on the principle of dry distillation of fuel.
With a lack of oxygen, under the influence of high temperature, dry wood decomposes into a solid residue and a volatile part (pyrolysis gas, which is subsequently mixed with hot air).
This air-gas mixture, which was formed during the pyrolysis process, is the fuel of the pyrolysis boiler. The pyrolysis combustion process is exothermic (accompanied by the release of heat).
It occurs at temperatures from 200 to 800 °C and provides heating of the air entering the combustion chamber. In this case, the fuel in the unit chamber is heated and dried, thereby minimizing the release of soot and ash.
For a pyrolysis or gas generator boiler, it is more typical high efficiency compared to traditional solid fuel technology.
When burning high-quality fuel, the efficiency of a pyrolysis boiler is at the level of pellet boilers and long-burning boilers and reaches 90%.
Pyrolysis solid fuel boilers are used both in private houses and apartments, and for heating industrial premises.
Pyrolysis boilers are a very cost-effective type of heating equipment. The fairly high price of a pyrolysis boiler is covered by low fuel consumption.
In a conventional long-burning solid fuel unit, the coolant is heated by the heat released during fuel combustion, but pyrolysis boilers operate on a different principle.
When burning organic fuel (wood, pellets, wood briquettes and even coal) at a temperature of 400-800°C, gas is released, burning which can produce much more heat than when burning fuel.
The process of gas formation from solid fuel and subsequent combustion of the resulting gas is called pyrolysis, and units using this operating principle are called pyrolysis, or gas generator boilers.
There are two chambers in the pyrolysis boiler, and combustion takes place in both:
- Combustion chamber – wood or other fuel is burned (charred).
- Afterburner – the gas emitted by the fuel is burned.
Fuel is located and ignited in the combustion chamber. Primary air is supplied to the combustion zone. When the fuel warms up to a certain temperature, gas evolution begins.
Using a smoke exhauster, gas, together with secondary air, is sucked into the afterburner chamber (it is located below the fuel level) and burns there, releasing heat.
Combustion products enter the smoke duct (flue) and enter the chimney, passing through the water jacket of the unit and heating the coolant.
As a result, firewood turns into charcoal, burning almost completely, and the smoke is cleared of unpleasant odors and carbon monoxide.
Advantages and Disadvantages
Advantages of use:
- when burning firewood, it is impossible to obtain such a high temperature as during the combustion of pyrolysis gas (especially if the firewood contains a lot of moisture);
- With the help of a control controller, we can automate the operation of a pyrolysis boiler without much difficulty, since the combustion process of pyrolysis gas is easy to control and regulate;
- burning wood or coal requires much more secondary air than burning wood gas. Therefore, with the same volume of secondary air, the combustion efficiency of wood gas, the duration and temperature of combustion will be greater;
- the emission of harmful substances from pyrolysis boilers into the atmosphere is reduced to a minimum, therefore a pyrolysis boiler is an almost environmentally friendly source of heat;
- solid fuel pyrolysis combustion boilers need to be cleaned from ash extremely rarely;
- pyrolysis boilers can operate for a very long time (up to 15 hours) on one load of firewood, while conventional solid fuel boilers need to be reloaded every 3-4 hours.
If we talk about the disadvantages of this type of unit, then, in addition to the price, which is the payment for increased efficiency, and more complex design, because pyrolysis boilers are 30-35% heavier than conventional ones, since more metal is required for their manufacture, other “cons” are insignificant.
For maximum operating efficiency, the moisture content of firewood should be no more than 20%. If the wood is wet, when it burns, steam is generated, which reduces gas emissions and leads to the deposition of tar and soot. As a result, the efficiency of the boiler decreases, and there is a need to clean it.
Most pyrolysis units are electronically controlled.
Consequently, it becomes necessary to use electricity to operate the controller, which controls the fan and smoke exhauster.
Pyrolysis boilers with natural draft exist, but they require a very high and powerful chimney, so such models are unpopular.
The need to fill the firebox by 50-100% - only in this case will the high efficiency of the boiler be maintained.
Long-burning pyrolysis solid fuel boilers, although twice as expensive as a conventional solid fuel boiler, are distinguished by the possibility of economical use of fuel with maximum efficiency, which is significantly higher than from the combustion of coal and wood in conventional units.
Types of pyrolysis boilers with a water circuit
There are many models on the market that can be divided into groups.
The location of the chamber in which the contents are burned.
Most boilers are designed so that this compartment is located at the bottom. This is more convenient for laying the material, but after its combustion, the ash enters the chamber where the resulting gas burns.
This obliges the owner to frequently clean the equipment. The upper location of the camera eliminates this need, but has a number of disadvantages. The main disadvantages of such a system include the inconvenience of placing the chimney and the larger amount of materials for its manufacture.
Traction type.
It can be carried out either by force or by supercharging. Boilers in which the draft power can be manually adjusted require the installation of a reinforced chimney and do not depend on the power supply. Such models are few and far between.
Devices of the second type are equipped with automatic systems that determine the blowing time. Maintaining power requires the energy dependence of the unit, but the rate of pyrolysis output in it is quite high. These models are the most popular.
Type of fuel.
When determining the possibility of using a particular type of fuel, one should start from the moisture level of the material. If it is higher than 20%, then the first operating time of the boiler will be spent drying the material, which leads to a decrease in the efficiency of the device.
If the humidity of the fuel used is initially high, then the pyrolysis process will take no more than 1/5 of the entire combustion cycle. This is extremely ineffective and irrational.
It will be difficult to recoup the high cost of the boiler. Therefore, the conclusion is obvious: the best material for combustion in pyrolysis boilers is firewood, coal or briquettes, the moisture level of which is minimal.
Each material has its own burning time. The smoldering time determines the quality and uniformity of heating of a living space. The best option– this is dry wood with a moisture level of no more than 10–15%.
Today, there are two main types of pyrolysis units, differing in design.
Boilers with forced air supply.
In the first version of the boiler design, the primary combustion chamber, where solid fuel, is located above the secondary combustion chamber, where afterburning of pyrolysis gases is organized. A special nozzle is installed between the chambers, having a straight cross-section and made of a refractory composition similar to fireclay bricks.
In this design, air is forced into the main firebox using an installed fan, and partly enters the firebox with solid fuel, and partly into the afterburning chamber of the released gases.
In this case, it is obvious that the principle of pyrolysis is violated initially, since the fan creates an excess of oxygen instead of limiting it.
But, despite this, efficient and complete combustion of firewood occurs, with virtually no residue of even fine ash, since dry wood or products based on it burn to fine ash, and it is easily blown out through the nozzle by a fan into the chimney pipe.
Knowing the features of this design, it can be called a “top blowing device”, since the air pumped by the fan enters mainly into the upper main combustion chamber.
Due to the influx of oxygen, the temperature during combustion increases and gas production increases, but it burns quite quickly, escaping through the nozzle.
In this regard, firewood quickly burns out, and it has to be added quite often in the process of heating the house. This principle of boiler operation cannot be called pyrolysis in the full sense of the word, although similar devices are sold quite often under this name.
It’s another matter if a fan standing on the outlet pipe (often called a “smoke exhauster”) creates air movement that would normally mechanically or using automation it is proportionally divided into primary and main - secondary.
In this case, the primary air damper is located so that it is supplied precisely to bottom part fuel bookmark.
Smoldering of firewood occurs from below, and the temperature released during this process promotes heating - in the middle layers of the stack, and final drying - in the upper ones.
The main air flow will be supplied only to the nozzle area, so that the final combustion of the pyrolysis gases with the maximum amount of heat generated takes place in the lower chamber. Such a boiler can rightfully be classified as a long-burning pyrolysis boiler.
Boiler with natural air supply.
In such a boiler design, the combustion chamber for storing firewood is located in the lower part of the device, and the combustion section of the pyrolysis gases released by the fuel is in the upper area of the body.
A fan is not installed in this design, and the air for lighting the boiler and afterburning pyrolysis gases is supplied naturally through dampers for primary and secondary air.
In this version of the arrangement of the chambers and the dosed supply of air flows, the pyrolysis process is carried out properly, since instead of intense combustion, with the primary air supply damper closed, wood smoldering occurs in the combustion chamber with the release of a large amount of pyrolysis gases.
However, this design also has its own problem. And it lies in the fact that the correct debugging of the combustion process is extremely important.
When the main chamber damper is completely closed, the temperature in it decreases, as well as the formation of gases. The concentration and temperature of the gases becomes insufficient for their complete afterburning and the upper chamber turns into a regular gas outlet.
The combustion products that rise into it do not burn out, but simply give off heat to the walls of the water circuit and go into the chimney. The efficiency of the boiler during such operation is sharply reduced. If the damper is opened more than required to create the conditions necessary for pyrolysis, the combustion intensity in the main firebox will increase, which leads to completely irrational fuel consumption and the need for frequent refills.
To achieve ideal operation of a pyrolysis boiler of this design, it is necessary to correctly adjust the supply of primary and secondary air, which is quite difficult to do, since this requires practical experience.
Modern models have automated process monitoring and control systems, and when correct operation automatic fuel loading is enough for 12-14 hours of operation at maximum heat transfer.
Fuel for pyrolysis boiler
Solid fuel pyrolysis boilers are practically omnivorous. Various types of solid fuel can be used as fuel: from ordinary firewood to peat.
Based on this, a boiler can be heated with any type of solid fuel, but still each type has its own inherent qualities and properties, so the operation of the boiler will also differ.
Therefore, fuel selection is a very important process.
Along with firewood or briquettes, sawdust can also be used as fuel. But they should be taken no more than a third of the main part of the fuel by volume.
The operating instructions stipulate that the fuel moisture content should not be higher than 45%. The lower the moisture content of the wood, the greater the power of the boiler and the longer it can operate without repair.
For example, a kilogram of wood with 20% humidity when burned produces heat equivalent to 4 kWh, and firewood with 50% humidity produces only 2 kWh. In addition to the fact that with an increase in moisture content in the fuel, the specific heat of combustion decreases, fuel consumption increases significantly.
Why is it better to choose a pyrolysis boiler and the basic rules for its operation
- Firstly, during the combustion of firewood it is impossible to reach such a high temperature as during the combustion of the gas obtained from them.
- Secondly, to maintain the combustion of gas, less secondary air is required than for burning wood, accordingly, the combustion temperature will be higher, and with it the efficiency.
- Thirdly, the procedure for burning pyrolysis gas is easier to control, thus, the operation of a gas generator boiler is automated in the same way as a liquid fuel or gas boiler.
This equipment is based on pyrolysis fuel combustion technology. Its essence lies in the fact that under the influence of elevated temperature and in conditions of lack of oxygen, wood begins to decompose into a solid residue and a volatile part - pyrolysis gas.
Pyrolysis occurs at temperatures ranging from 270 – 700 degrees. This process is exothermic, in other words, it is characterized by the release of heat, which increases the drying and heating of the fuel in the boiler.
Subsequently, the mixing of oxygen with pyrolysis gas at a high temperature leads to combustion of the latter, which is used to obtain thermal energy.
Pyrolysis gas actively interacts with carbon, due to which it leaves the boiler flue gases almost do not include harmful impurities, being considered, to a greater extent, a mixture of water vapor and carbon dioxide.
Numerous studies have shown that carbon dioxide will be released into environment up to three times less than from an ordinary wood-burning and, even more so, coal-fired boiler.
The pyrolysis combustion procedure is characterized by the formation of a small amount of ash and soot, which is why this equipment rarely requires cleaning.
The advantages of long-burning pyrolysis boilers with a water circuit are environmental friendliness.
The efficiency declared by the manufacturers is only 4–10% higher than the productivity of a conventional solid fuel boiler. Obviously, the choice should be based on consideration individual characteristics heating system and owner preferences.
The main features of a quality model that is worth purchasing:
- Good, neat welds and sufficient material thickness (at least 4 mm). Thin metal in cheap boilers burns out quickly and is more susceptible to corrosion. Buying such products is a bad decision!
- Ceramic nozzle and gas combustion chamber lining (this model will last longer). This material has excellent fire-resistant properties. Make sure that ceramics is used, as the most reliable material for these parts of the boiler.
- Two working chambers with the ability to smoothly adjust the air supply. Two chambers are the main feature of an effective pyrolysis model! If you need high performance and at the same time economical boilers long burning - choose long burning pyrolysis boilers with a water circuit.
- The coolant is in contact only with the chimney and gas combustion chamber. If this technical point is not observed, the boiler will lose heat, since the main combustion chamber has more low temperature(the coolant cools upon contact).
- Availability of an automatic control unit and a corresponding warranty for it. Repairing this very important unit for regulating the air supply in some cases costs up to 50% of the total cost of the equipment. Take this part of the boiler seriously.
Some more tips for choosing a boiler:
- The required power can be calculated based on the area of the room and the degree of insulation. Approximately you need to take 1 kW per 10 m2, while adding a few kW, also taking into account the functions of the boiler as a boiler. So, if you have an area of 80 m2, then a 10 kW option is suitable, but if the area is 100 m2 and the walls are not insulated, then 10 kW will not be enough;
- The size of the firebox is important, if you burn with wood, the larger it is, the large sizes firewood can be placed there;
- Burning time without additional loading is usually indicated taking into account excellent quality fuel, so take 2/3 of these data. For example, if 10 hours are stated, you can count on 6;
- Energy independence is very important when choosing a boiler for a dacha or a place remote from electricity; in addition, it also saves electricity.
For normal operation equipment, it is necessary to maintain a certain range of fuel combustion temperatures. This range is from 2000 to 8000 C.
It is necessary to configure the device quite accurately. To prevent emergency situations at high temperatures, the water circuit of the unit is used.
The housing plays the role of a heat exchanger; water passes between its walls. This feature and the built-in coil in one of the walls prevents the creation of prohibitive temperatures.
When the water temperature is insufficient, the formation of pyrolysis gas stops, air is supplied to the combustion chamber and the boiler operates like a conventional solid fuel stove. It is not allowed to cool the water below a temperature below 600 C. In this case, the combustion process without oxygen stops in any type of pyrolysis boilers.
To ensure a small water circuit and transfer the equipment to an operating state, an additional jumper (bypass) is installed in the water circuit. The bypass is adjusted manually; temperature sensors are installed to control the temperature.
This type of equipment can work on all types of firewood, briquettes, pallets.
In reality, a type of fuel such as coal can be used. Provision is made for the processing of flammable household and industrial waste. But this can cause unpleasant consequences due to the content in them high content polymers and rubber.
Pyrolysis boilers are produced only as single-circuit boilers and cannot be used for heating water. But, in case of absence natural gas, to create in the building comfortable conditions, this type equipment is the best solution to the problem.
DIY pyrolysis boiler
Make a pyrolysis boiler with your own hands according to the drawings, or order production from specialists (which is still cheaper than buying a ready-made one).
To make such a complex device, you will need a fairly wide range of tools and materials.
Here is an approximate list of them:
- Plan diagram. Without an accurate calculation, you are unlikely to be able to do everything correctly. You don’t have to make the drawings yourself, if you don’t have the appropriate skills, you can simply download it on the Internet.
- Welding machine.
- Grinding machine.
- Metal pipes different diameters and length (120, 130 and 150 centimeters, with a diameter of 50, 45 and 6-8 centimeters) the boiler frame itself and the chimney will be made from pipes.
- Sheet of metal for making a door.
- Hinges and handles for installing dampers.
Manufacturing a pyrolysis boiler includes the following steps:
- Next, in the lower part of the frame - the firebox, you need to cut a hole-door; the door itself is made from a sheet of metal. It is very important that the door fits as tightly as possible to prevent excess air from entering the boiler.
- The last stage of manufacturing a pyrolysis boiler will be the installation of a chimney and an outlet pipe through which unburned gas will be discharged into the chimney and outside.
Making the frame.
The frame of the pyrolysis boiler consists of two parts: a casing and a firebox. A frame is made from two pipes of a larger and smaller diameter. One pipe is inserted into another and welded. In this case, the larger pipe acts as a casing, and the smaller one as a firebox.
The bottom and top of the pipes are welded in circles cut from a metal sheet. The space between the pipes is filled with a heat-conducting agent.
The second stage is the division of the firebox by putting on the chambers.
Firewood will be loaded into one of them, and gas will burn out in the second. The air distributor acts as a separator. This is a pipe of the smallest diameter onto which a sheet of metal with blades is welded.
In addition to the fact that the pyrolysis boiler must be manufactured correctly, it must also be installed correctly:
- As a rule, a pyrolysis boiler is installed in a separate room - a boiler room; this is the safest option.
- Install the pyrolysis boiler at a distance of at least thirty centimeters from the walls.
- The floor on which the boiler will stand must be made of non-combustible materials.
- The boiler room must be equipped with good ventilation.
- The boiler chimney must be well insulated to avoid the release of combustion products into the room.
- The fuel loading hole for home-made models is usually placed slightly higher than that of conventional solid fuel boilers.
- It is imperative to install a limiter that will allow you to control the amount of air entering the fuel chamber, as well as timely add firewood or briquettes.
- To make a limiter, you can use a pipe with a diameter of about 70 mm, slightly longer than the body of the device.
- A steel disk should be welded to the bottom of the limiter, forming a gap of about 40 mm with the pipe walls.
- To install the limiter, a corresponding hole must be made in the boiler lid.
- The loading hole for firewood should be made rectangular. This hole is closed with a door with a special steel plate that ensures a secure fit.
- Below you need to make a hole to remove ash.
- The pipe through which the coolant moves inside the boiler must be bent to maximize heat transfer. The amount of coolant entering the boiler can be adjusted using a valve installed outside.
- If after the first start-up of the boiler there is no carbon monoxide in the combustion products, it means that the design is made accurately and functions correctly. In the future, you should regularly monitor the condition of the boiler welds and promptly clean it of accumulated ash and soot.
Pyrolysis boiler from a gas cylinder
A homemade pyrolysis boiler made from a gas cylinder can operate on a wide variety of solid fuels:
- firewood;
- coal;
- slate;
- wood production waste.
Having created such a design, you can safely forget about the lack of heat even in a large room.
A pyrolysis boiler from a gas cylinder is made with your own hands according to the following, simple principle: firewood or other solid fuel is loaded from above or from the side, then ignited. It is necessary to wait until the fire appears, and then cover it with a piston, which acts as an air duct in this design.
From above, the entire structure should be additionally closed with a tight top cover with a hole for the pipe.
The optimal size of a gas cylinder suitable for making a boiler is 50 liters.
Tools you will need to make your own pyrolysis boiler:
- welding machine;
- cutting torch;
- Bulgarian.
As additional materials Sheet metal, metal strip and fittings are used.
The cylinder is cut off along its upper part, which can be made into a lid, if desired. To do this, you just need to sand the entire structure.
After this, again a hole is made at the top for the pipe. A loading door is cut out on the side, which opens access to the firebox, where the fuel is placed.
The chimney must have different diameters to provide better draft. This trick will allow you to maintain a stable pyrolysis process for 8-10 hours, that is, you will need to heat the stove once a day.
A pyrolysis boiler made from a gas cylinder has a grate made of fittings. With its help, the fuel falls down, leaving a minimum of ash.
Water vapor that may form during boiler operation condenses into vertical pipe, in which there is a special valve called a ball valve.
In places where interruptions in gas or electricity supply are possible, where fuel (wood, coal, etc.) is available, long-burning solid fuel boilers are taking root as the main or backup heat sources in heating systems. And long-burning pyrolysis boilers have proven themselves especially well. They are both effective and economical!
The topic of solid fuel boilers at one time lost its relevance, but is now quite confidently making its way into the heating sector. This is successfully helped by rising energy prices (gas, oil, electricity), as well as the greater popularization of individual construction of houses and cottages.
Let's look at their features...
Who are they?
The group of pyrolysis boilers for heating usually includes their solid fuel “brothers”, which consume mainly wood.
Important! Firewood in our country has the status of an easily accessible fuel. And, mind you, renewable. The main thing to remember is that forests not only need to be cut down, but also need to be planted...
High-tech supporters need not be nervous! This is not a leap into the past, but a smart integration of scientific technologies into human life. Studying a wood-fired pyrolysis boiler (even the simplest one) reveals the beginning of an impressive list of its advantages.
The benefits of pyrolysis in heating
The long-term search for energy-saving technologies has affected little organic chemistry. Scientists have noticed that in a high-temperature environment with limited access to oxygen, the combustion process of many organic solids is accompanied by a stable release of flammable gas, which in itself is suitable for further combustion. And when it burns, a large amount of heat is released.
In other words, when one fuel burns, a new (gaseous) fuel is formed. Wood is the leader in this process!
This process of generating flammable gas from solid organic substances during their smoldering was called pyrolysis, which determined the name of the pyrolysis heating boiler. They are also called gas generators or long-burning solid fuel boilers.
Due to the two-stage combustion of fuel (solid and newly formed gaseous), pyrolysis boilers release more heat when burning the same volume of fuel than conventional ones solid fuel units. That is, their efficiency is much higher.
The main practical advantage of such boilers is their ability to operate for a long time (up to 25-30 hours) on one load of fuel. This is achieved by deliberately restricting the air supply to the combustion chamber.
And how does it work?
The difference between a pyrolysis boiler and a conventional solid fuel boiler is that it has two combustion chambers. It also has a separate compartment for waste from the combustion process.
The upper chamber (gasification) is intended for loading fuel. The primary breakdown of firewood occurs in it.
Due to the restriction of air access into the chamber, an exothermic reaction occurs in it. High temperatures from 200 to 800 °C lead to the formation of two flammable components: pyrolysis gas and charcoal.
The heat released at this stage is also spent on drying the wood and heating the air entering the combustion zone.
Next, the gas enters the middle chamber, where, in “pair” with air drawn into the chamber by a fan-exhaust fan at a high temperature of 1150-1200 O C, it ignites, releasing a significant amount of thermal energy and virtually complete combustion of the entire contents of the chamber.
The resulting ash, as well as soot, fall into the lower chamber, adapted for periodic cleaning, the frequency of which depends on the quality of the fuel and the intensity of use of the wood-burning boiler.
The high-temperature processes occurring in a long-burning pyrolysis boiler determine the requirements for the strength of the entire unit. Steel or cast iron are used. Cast iron is more “slow” (inertial), both when heating and when cooling, but it is also more durable. Steel improves dynamics when heated, but rapid cooling of a pyrolysis boiler is not always convenient. Cast iron has higher corrosion resistance, and steel surfaces are predominantly coated with ceramic materials, which protects the metal from “destructiveness.” high temperatures. Various construction materials, the presence of automation, and the power of the unit determine its cost.
Set of advantages and disadvantages
Modern technologies that use pyrolysis boilers have allowed them to acquire a number of advantages:
- Efficiency of up to 85% is explained by the operating features of the boiler, which ensures complete combustion of fuel;
- complete combustion of fuel ensures minimization of waste;
- the slow combustion process allows you to add a new portion of fuel twice, and in some designs, with economical use, even once a day;
- the boiler design provides the ability to automatically dynamically control the power of the heating system within the range of 30-100%, by regulating the rate of air flow into the lower combustion chamber;
- the environmental friendliness of this boiler design is ensured by the virtually complete combustion of both solid and the resulting gaseous fuel mass, which ensures low emissions (about 3 times less) of carbon dioxide into the atmosphere;
Wood-burning pyrolysis boilers also have disadvantages. These are also worth mentioning:
- the most insignificant is the need for constant power supply to the unit. But due to the fact that modern heating systems are predominantly forced circulation coolant, then electricity will be required to ensure the operation of the circulation pump.
- “single-circuit” pyrolysis units, which is also easily compensated by installing a storage boiler for DHW systems, which naturally leads to additional costs;
- quite high price, which is also compensated by economical fuel consumption;
- the need, although rare, is still “manual” loading of fuel. This disadvantage is successfully overcome by new pyrolysis boilers using wood pellets, which can be automatically reloaded from a fuel bunker or warehouse.
- “demanding” on the quality of wood fuel, especially its moisture content, to ensure highly efficient operation.
And in conclusion about the global...
As we can see, energy-saving technologies have firmly taken root in the long-burning pyrolysis boiler, realizing their current global goals in them:
- minimizing fuel consumption;
- increasing the heat transfer of fuel during combustion;
- reducing the concentration of morbid substances in combustion products.
By installing a boiler of this type in your home, you will not only optimize your time spent on its maintenance, but also make your contribution to the conservation of nature.
