Burning a wide variety of wood (logs, waste), pyrolysis or gas generator boilers have gained wide popularity for heating domestic and residential premises. Their operating principle differs from classical solid-state models.

However, a design that is more complex at first glance provides a lot of advantages and savings on heating costs. You can build a simple pyrolysis boiler with your own hands in the shortest possible time.

Pyrolysis boiler test video

How does a pyrolysis boiler work?

The basis of the gas generator boiler is the firebox, which is divided into a couple of sections:

• In the first one, wood burns due to lack of oxygen.
• In the second, the released gases burn out

The firebox sections are divided among themselves by a grate. One of the main differences between a pyrolysis boiler and a classic one is the downward movement of air. High aerodynamic resistance does not allow air masses independently circulate in the desired direction, so forced draft is installed using a blower fan or smoke exhauster.

The basic principle underlying the operation of the installations of this type– wood decomposition thermally. Subsequently, it is divided into coal and volatile gaseous mixtures.

The process necessarily takes place in the firewood storage chamber at high temperatures, but there should not be enough air saturated with oxygen for complete combustion. Volatile gaseous mixtures that enter the second chamber burn out at temperatures above a thousand degrees. Subsequently, carbon monoxide is redirected through the convective part into the chimney, giving off its heat.

To keep the wood burning ideal conditions, inner surface lined with refractory lining. In this case, both chambers must be lined.

Drawings and diagrams

To assemble a pyrolysis boiler with your own hands, you need to become more familiar with the structure in the drawings. In any scheme, the main elements of the models under consideration will be:

1. Place for water
2. Heat exchanger
3. Firebox

Click to enlarge image

Video on boiler construction

It is very difficult to build such a structure from scratch, which is why you can take Belyaev’s boiler as a basis. Whether to make changes to it or not - it all depends on engineering skills and the desire to experiment. However, changing the volume internal space definitely not recommended.

Instead of liquid coolant, pyrolysis boilers can use water circulating through pipes to heat rooms. hot air. This option won't freeze. It has become widespread in heating systems country house, because it is not delivered unnecessary hassle in winter.

Necessary materials

In order to assemble a pyrolysis boiler with your own hands, you need to prepare hand tools, welding machine, a grinder with cutting wheels and brushes for cleaning. From Supplies You should have at hand:

1. Doors, fastenings and locks for them
2. At least one detailed drawing with dimensions
3. Temperature sensor
4. Blower fan
5. Pipes for supply line, hot and cold water supply
6. Sheet metal large thickness
7. Fireclay brick
8. Grate

Assembling a simple pyrolysis boiler

Four walls must be cut from prepared sheet metal at once. In the front, a pair of rectangular holes are pre-cut with a grinder:

• Bottom - under the ash pan
• Top - under the firebox

The back wall can be put aside for a while. The remaining three cut plates are securely welded to each other. At the joints, the formed growths are carefully polished with a grinder.

Now you can assemble a heat exchanger through which water or another, usually liquid, coolant will circulate. All its elements are also securely welded and cleaned so that seams and joints are not visible.

The next step is to install the heat exchange device directly into the furnace. Water is sent through the pipes and created operating pressure inside to determine the presence of defects - leaks.

The combustion chamber will be located at the bottom, and not at the top as in high-performance factory models. It is separated from the gasification zone, which is located above, by a grate.

See also, professional guide

The wood burning section must be lined fire brick below, above and on the sides. An air duct is also provided here. Now you can install the doors, which should be pressed as tightly as possible against the walls.

A few finishing touches remain: cut holes for pipe pipes and a smoke exhauster, weld back wall and sand the corners.

The final stage is to check the efficiency of the assembled and ready-to-use device. If the output is not observed carbon monoxide– the equipment is fully operational and can continue to be used.

Other features of a gas generator boiler

Separately, it is worth highlighting some features that a productive pyrolysis boiler assembled by yourself should have:

1. It is recommended to install a valve outside, through which the coolant flow passing through the heat exchanger will be controlled (for heating)
2. To increase heat transfer, it is recommended to make the coolant pipe curved, for example, in the form of a coil
3. A hole for storing firewood is made rectangular shape, while a steel pad is provided on the door for a tighter fit
4. Control air flow entering inside, it is necessary to use a restrictor

Safety precautions

Making a pyrolysis boiler yourself is a difficult task and not always justified. The resulting model is perfect for heating a small utility room, but for a residential building it is recommended to purchase factory-made equipment.

However, any gas generator boiler must be installed correctly. If installation instructions are not followed, the installation may cause fires, putting the lives of occupants at risk.

Let's name a few mandatory rules:

1. The area of ​​the ventilation opening in the room must be at least 100 square meters. cm.
2. The boiler must be removed from any surfaces of other objects or walls at a distance of at least 0.2 m
3. Need to put sheet metal in front of the boiler with a thickness of about 2-3 mm, since combustion products (ash, coal, sparks, etc.) may fall out
4. The boiler must be placed exclusively on a concrete or brick base
5. For pyrolysis heating equipment it is necessary to have a separate room - a boiler room, maximally protected from fires
6. The chimney should be properly insulated with insulation so that sudden hypothermia does not cause excessive digging and other plantings inside

how and with what to heat industrial premises

Waste oil pyrolysis boiler

Gas generating units can operate not only on wood, but also on other fuels, for example, waste oil. They are perfect for small automotive workshops. Building a simple pyrolysis boiler with your own hands during mining is beneficial not only from a practical point of view, but also economically.

An oil pyrolysis boiler is assembled as follows:

• The lower container simultaneously acts as a combustion chamber and fuel tank
• To prevent direct interaction between the firebox and the floor surface, it is recommended to weld metal legs 10-15 cm high
• The top of the container is drilled air damper, for which a valve is installed that allows you to regulate the air flow (it can simultaneously act as a plug for filling fuel)

• A pipe with a diameter of about 15 cm leading upward is welded to the tank; the wall thickness is chosen to be larger
• Holes are drilled in the pipe
• The heat exchanger is welded on top in the form of another container, but in order to prevent quick removal hot smoke, jumpers are welded inside
• The last stage - the exhaust pipe for the chimney is welded

Let's sum it up

Make a pyrolysis boiler with your own hands or buy factory model– everyone must decide for themselves. Structurally, such an installation is very complex. You will definitely be able to save a lot of money. Money. But equipment can operate as efficiently as possible and remain safe only if numerous features and nuances are observed.

Of all types of heating installations operating on solid fuel, the most effective are those in which pyrolysis occurs when burning wood or coal. This is the process of afterburning gases released from firewood or coal during their smoldering, which allows almost all the energy of fuel combustion to be transferred to the coolant. This principle uses a pyrolysis boiler circuit, in which the separation of combustible gas from fuel and its subsequent combustion is realized.

Design and layout of installation elements

In contrast to classic solid fuel installations, the design of pyrolysis boilers long burning provides two combustion chambers instead of a traditional firebox. In the first chamber it is carried out slow burning due to insufficient air. In this case, the fuel begins to release so-called pyrolysis gas, which flows into the secondary chamber along with combustion products. A sufficient amount of air is supplied there, as a result of which the gas ignites and burns, heating the water jacket of the unit.

The location of the two cameras may be different because heating boilers pyrolysis type can operate both on the natural draft of the chimney, and with the help of forced air supply by a fan. In installations using natural cravings, the secondary chamber is located above the primary and air passes through the fuel from bottom to top. When artificially generated thrust the main firebox, on the contrary, is located above the afterburner and the air flow is directed from top to bottom. This is reflected in the diagrams below for the design of pyrolysis boilers with different chamber layouts.

Combustion air supply methods

Increased requirements are placed on the height and diameter of the chimney when the air supply circuit in pyrolysis boiler involves the use conventional traction. It should be enough to overcome the resistance of the gas-air duct of the installation and the chimney pipe, as well as to create a vacuum in the firebox of 16-20 Pa. You can select the diameter according to the outlet pipe, and the height should be at least 5-6 m.

Forced air supply to both chambers can be carried out in three ways:

Typically, the design of a pyrolysis boiler involves installing a fan in pressure mode. This is explained by the fact that a conventional blower is more affordable than a smoke exhauster, since the latter must extract exhaust gases at high temperatures. For this reason it structural elements are more expensive.

Leading manufacturers of pyrolysis boilers install smoke exhausters on their products at the exit of combustion products. The reason is to ensure safety for the person who opens the firebox door in operating mode. The smoke exhauster creates a vacuum, so the flame will not blaze through the open opening into a person’s face.

For high-power installations, manufacturers use fans for both types of boilers, at the inlet and outlet of the gas-air duct.

In order to understand how a pyrolysis boiler works, we recommend watching the following video.

Manufacturing of a pyrolysis boiler

The effectiveness of this type of wood-burning installations has become the reason for their popularity among craftsmen who can make solid fuel boilers pyrolysis type on our own from available materials. This process is quite labor-intensive and requires plumbing and welding work, a certain minimum of tools and equipment:

• electric welding machine;
• angle grinder;
• electric drill;
• set of locksmith tools.

If you have the skills, tools and a great desire, you can make a unit using the following drawing of a natural draft pyrolysis boiler:

1 – air channel; 2 – door for loading fuel; 3 – secondary chamber door; 4 – direct draft damper; 5 – primary chamber; 6 – top cover; 7 – inlet channel for air supply; 8 – air damper; 9 – pipe for the safety group; 10 – secondary afterburning chamber; 11 – chimney connection pipe; 12 – nozzle; 13 – fire tube heat exchanger.

The material for making the chambers can be heat-resistant alloy steel, but this is an expensive material, so craftsmen take simple carbon steel 5 mm thick. To protect it from high temperatures, the pyrolysis boiler is lined with refractory bricks in the lower part of the furnace. They also need to protect the bottom of the secondary chamber, where the flame is directed. To cover the water jacket, sheet metal 3 mm thick is used, it is welded to the stiffeners made of strip steel. The doors, lids and frames of openings are made from the same metal.

Heat transfer from flue gases The boiler is installed through a fire tube heat exchanger located inside the water jacket. Seamless fabrics are suitable for its manufacture. steel pipes from carbon steel outer diameters 48 or 57 mm. The number of pipes should be selected according to required area heat exchange surface, for which the calculation of the pyrolysis boiler is performed.

Considering that the fuel in pyrolysis units burns for a long time (up to 12 hours) and is productive, some owners of classic direct combustion units are wondering whether they can be modernized. Such a rework solid fuel boiler in pyrolysis is possible, but provided that the furnace of the unit is made of metal and not cast iron. The grate is removed and, using electric welding, a partition is fixed in its place, separating the main firebox and the ash pan, which will serve as a secondary chamber. A nozzle is installed between them. In addition, you will need to organize an air supply to both chambers; you need to make air channels and install them, as shown in the drawing.

As a rule, converting a boiler into a pyrolysis boiler occurs not on factory units, but on home-made ones, this expands the possibilities for improving the design. You can change the flow area of ​​the nozzle, the dimensions of both chambers or the surface heat exchange area, achieving best performance duration of combustion and increasing the efficiency of the installation.

Calculation of a pyrolysis boiler

The calculation begins with determining the temperature difference, ºС:

Ƭ= (∆T - ∆t) / ln (∆T / ∆t)

In this formula:

• ∆Т – temperature difference of combustion products before and after the heat exchanger;
• ∆t is the difference between the temperatures in the coolant supply and return pipelines.

The resulting value Ƭ is substituted into the formula:

S = Q / k / Ƭ, Where:

• Q – design power heating installation, W;
• k – heat transfer coefficient, equal to 30 W / m 2 ºС.

An enlarged calculation of the power of a pyrolysis boiler (Q, kW) is performed based on the area of ​​the building. Its value must be taken according to the external measurement of the house, the result divided by 10. The meaning of this action is that approximately 10 kW of thermal energy is required to heat every 100 m 2 of the building. The result obtained is the calculated power of the heating system, and the heat source is taken with a safety factor. It depends on the region of residence and ranges from 1.1 to 1.5.

Commissioning works

After the assembly of the pyrolysis boiler is completed, it is necessary to check the tightness of the welded joints. Water jacket is filled with water, then air is pumped into it, creating overpressure. Poorly welded seams will make themselves felt by leaks. Now you can carry out tests, it is better to do this outside, supplying running water from a hose. If a safety group is installed on the unit, then you can fill the boiler tank with water and check its operation at a critical pressure of 2-2.5 Bar. The test order is as follows:

• Attach a temporary chimney, load fuel into the chamber and open the direct draft damper.
• Stop feeding running water, providing a temporary crane for this.
• Ignite and start the pyrolysis boiler. As soon as the wood burns, the direct draft damper must be closed so that the pyrolysis process can begin.
• Open the secondary chamber door and make sure there is a flame. This requires adjustment of the pyrolysis boiler; you need to achieve an even and stable flame by opening or closing the air damper.
• Close the door and observe the readings of the thermometer and pressure gauge. In a closed water jacket, the vaporization process can begin when the pressure reaches 1.5 Bar, at which time the temperature must be carefully monitored.
• High-quality welded pyrolysis heating boilers can withstand pressures of up to 3 Bar, but there is no need to set records. It is enough if safety valve, set to a pressure of 2 or 2.5 Bar will begin to release steam, then you can open the tap and resume water circulation. The air supply damper must be closed for the fuel to begin to fade.

Be careful when carrying out such tests, there is a danger of scalding with boiling water due to negligence or if the water jacket ruptures.

Connecting the boiler to the heating system

The last stage is connecting the pyrolysis boiler and piping it. As with all solid fuel installations, it is necessary to prevent the formation of condensation on the internal walls of the firebox during heating. This phenomenon shortens the service life of the furnace body, since the condensate contains sulfur inclusions and will cause intense corrosion of the metal. For this reason, the piping of the heating boiler must be done according to a scheme that does not allow cold water to enter the jacket during heating.

Below is a classic diagram for connecting a pyrolysis boiler to a heating system with a balancing valve between the supply and return pipelines.

The jumper forms a small circuit in which the coolant is driven circulation pump. The piping of a pyrolysis heating boiler shown in the diagram allows water to circulate through a small circuit, warming up along with the unit. The thermostatic three-way valve will begin to mix cold water from the system at the moment when the water temperature in the small circuit reaches the set value, usually 45-50 ºС.

The operating temperature in the heating system lies in the range of 60-80 ºС; it is rarely necessary to raise it higher. If your home is cool when operating in this temperature range, then you need to look for the reason in the system itself. It makes no sense to increase the temperature; this will only increase the consumption of firewood in the pyrolysis boiler.

Conclusion

Do-it-yourself pyrolysis plants are becoming increasingly popular. The reason is the high cost of factory-made boilers, homemade units are often the only alternative. The only drawback is that fuel for pyrolysis boilers must have a moisture content no higher than 25%, otherwise the pyrolysis process will be weak, which affects the performance of the installation.

Increasingly, solid fuel devices are becoming an alternative to the good old stove. However, the most cost-effective and easiest to use are gas generator models.

But since their cost is quite high, many people prefer not to purchase industrial designs, but to assemble a pyrolysis boiler with their own hands. In the presence of certain knowledge it is quite possible.

We will consider below what tools, components and circuits are needed for this.

Pyrolysis - what is it?

In order for the assembled device to be made taking into account all the requirements, it is necessary to find out what its operation is based on and what it represents this process. Let's start with the concept of pyrolysis. This is the ability of wood to decompose during combustion into gas and solid residues, namely coal. But in order for this process to proceed according to all the rules, it is necessary to create certain conditions:

• High temperature
• Lack of oxygen

This requires a special design that can provide everything necessary for pyrolysis. It is implemented in industrial gas-generating boilers and is a welded container made of steel with a thickness of at least 5 mm. This is due high temperatures, during which fuel combustion occurs.

Equipment Features

The operating principle of heating devices is based on fuel combustion, but gas generator boilers have a significant difference from classic ones. It consists of burning not only wood, but also the gas that is released during its combustion. This feature made it possible to avoid frequent cleaning of the devices, so when burning pyrolysis gas, no soot is formed, and the ash yield is also minimal.

Watch the video for the construction of a homemade fire boiler:

But the main achievement was high efficiency, for such devices it reaches 85%. Another feature is the ability to adjust the boiler power in the range from 30 to 100%.

But, like any complex technical device, pyrolysis equipment has its advantages and disadvantages.

The latter include:

• High cost, but it is well justified by the complexity of the design
• Ineffectiveness of working with wet wood
• Power dependency

And although there are not so many of them, each of them to some extent slows down the growth of the popularity of such devices.

But having considered the disadvantages, we cannot help but talk about the advantages.

These include:

1. Easy to use
2. Minimum amount of harmful components in exhaust gases
3. Long-term work on one tab
4. Possibility of use in any heating systems
5. Easy control of the combustion process and, therefore, the possibility of automating operation control

Features of a classic pyrolysis apparatus

Structurally, the boiler consists of two chambers - this is its main difference from other similar devices. This feature is required for the normal operation of the process.

The loading chamber is used for burning wood under certain conditions. It is here that the firewood is separated into dry residue and gases, which then enter the second compartment. It is carried out forced submission secondary air, which improves fuel combustion.

The separation of the chambers is made using a grate with briquettes laid on it. Increased aerodynamic resistance is created in the furnace during boiler operation, so in such devices they usually use forced draft. It is implemented using:

• Smoke exhauster
• Fan

Economic benefits for self-assembly

The price of gas generating equipment is very high, so more and more people prefer to assemble it themselves. Of course, you can make a pyrolysis boiler for heating with your own hands, but this process cannot be called easy, and it is not very cheap either. Therefore, before you decide to do it yourself, you need to carefully study the information on this issue.

It wouldn’t hurt to evaluate your own capabilities. But those who still decide to take such a step can easily save a decent amount of up to $2,000.

Information on assembly can be found on various forums or you can order calculations from companies that provide such services at professional level. Of course, such a project costs money, but it will still allow you to spend a lot less funds than when purchasing an industrial design.

Components for assembling the device

So, if you are determined to make a pyrolysis boiler without anyone else’s help with your own hands, then you will not only have to make some efforts to achieve good result, but also have everything required to complete the work.

Let's watch the video of what is needed for the side of the boiler:

If followed in a specific order, you first need to perform the calculations required to determine the type of combustion. Structurally, it can be made both with a slot burner and on grates. Then purchased necessary components, such as:

• Steel sheets
• Pipe diameter 4 mm
• Electrodes
• Profile products
• Reinforcement (20mm)
• Fan (centrifugal)
• Fasteners
• Brick
• Automation system

But, in addition to the listed elements, you also need drawings and diagrams according to which you will assemble your boiler. They allow you to calculate required quantity each of the listed materials, and also, guided by them, assemble a solid fuel pyrolysis boiler yourself.

Typically, the proposed diagrams indicate the main components:

• Firebox
• Heat exchanger
• Water supply unit

Boiler diagram, watch the video:

This is very convenient, since you do not have to invent a circuit from scratch, but have the opportunity to use a ready-made one, making certain adjustments to it. However, you will not get by with components alone; assembling pyrolysis boilers yourself with your own hands, you will need drawings, as well as a set of tools.

What is required to complete the work

Since the combustion chamber of the boiler is a welded structure, when individually assembling the device you will need the following tools:

• Welding machine (preferably DC)
• Electric drill
• Grinding machines for wheels with diameters: 230 and 125 mm.

Having everything you need in stock, you can begin assembly. In this case, the design of the device can be changed at its discretion, but in such a way that the internal volume is constant.

During the assembly process, you will need a diagram for making a pyrolysis boiler with your own hands, according to which the assembly is carried out. Since this equipment is not characterized by freezing and leakage, perfect sealing of the pipes is not required.

Many of the DIY pyrolysis boilers use air as a coolant. Moreover, it is supplied to the system through pipes, and it returns back by gravity. This design has its advantages and is most often used in country houses, which are visited by the owners occasionally.

Fire safety

Having assembled the pyrolysis boiler yourself, you can immediately begin installing and testing it. If everything was done correctly, the device will quickly reach set temperature, and it will take no more than half an hour to warm up the system.

But during installation, basic requirements must be met fire safety, such as:

• Availability of a special boiler room
• Brick or concrete base under the device
• In front of the fireboxes, it is necessary to lay sheets of metal with a thickness of at least 1.5 mm on the floor
• The distance from the walls cannot be less than 20 cm
• Availability of 100 cm² ventilation hole

Only if all these requirements are met can you be sure of safe work equipment.

Bottom line

As you can see, assembling a pyrolysis boiler with your own hands using drawings is not only possible, but also profitable. However, it should be remembered that only if all requirements are taken into account, its operation will be economically profitable and safe for the lives of people living in a heated room. Therefore, during assembly and installation, strict compliance with all fire safety rules is necessary.