Boiler for burning sawdust. DIY sawdust heating boiler for a private home

Pellet with the ability to work on sawdust

Pellet boiler for a cottage. Works on pellets, sawdust.
Automatic solid fuel boilers using pellets, sawdust, wood chips. Designed for heating cottages, country houses equipped with water heating systems with forced circulation, for heat supply of technological processes. Can be used for heating a cottage, country house, cottage, shop, workshop, etc. Feeding of pellets, sawdust, wood chips - automatic from the feeder hopper. Boiler automation provides control of the boiler operation depending on the temperature at the boiler outlet.

The boilers were specially designed to operate on pellets and wood (sawdust, shavings, etc.).

Description of the boiler design
The boiler is steel, fire tube with two gas passages. The boiler body consists of two main parts.

Kolosnikovaya the part is equipped with inclined water-cooled inclined grates, a cavity for collecting ash, a pellet supply retort, a blast air distributor with adjustable dampers for primary and secondary blast. Equipped with doors for cleaning, maintenance and ash removal.

Firebox It is a cylindrical steel water-cooled shell of sufficient volume. The large volume of the firebox ensures maximum combustion of long-flame wood fuel. The walls of the firebox have holes for supplying secondary air for complete combustion of fuel, in particular pellets. The special arrangement of the holes ensures the development of vortex processes in the firebox, facilitating a uniform and rapid supply of air to the burning torch.

Computer modeling of the operation of a boiler using pellets and sawdust allows you to optimize the design and avoid many mistakes
In the combustion area, the firebox is lined with heat-resistant fireclay bricks with operating temperature 1650 °C. The lining allows you to increase the temperature in the combustion zone, which increases the rate of oxidation reactions of fuel components, increases the stability of the boiler at low loads and when using high-moisture firewood and sawdust.

Above the combustion zone is located heat exchange convection unit. Flue gases from the furnace pass through a large diameter heat exchanger pipe to the upper part. Next, the gases unfold in the upper part of the boiler and descend through the pipes of the second pass bundle, where they are collected in the gas receiver and removed into the chimney. This design makes it possible to cool gases to 140-180 °C and achieve an efficiency of 90%. The heat exchange pipes are located vertically and are not clogged with ash deposits. The top cover of the heat exchanger allows, if necessary, easy and quick cleaning of the heat exchange pipes, so the efficiency of the boiler does not decrease over time. The outside of the boiler body is thermally insulated and covered with a decorative shell made of sheet metal with a resistant coating.

This arrangement provides high performance with compact installation sizes. The design of the firebox allows you to effectively burn wood waste, in no way inferior to “gas generators”.

The pellets are fed into the fuel retort of the grate part using the auger of the fuel supply device, at the command of the automation system. After filling the cavity with pellets, they are poured onto the grate. Primary air is pumped under the grate by a fan; here, mainly charcoal is burned, remaining after the pyrolysis of the pellets and the release of volatiles. Volatile components burn in the flame with an intensive supply of secondary air to the furnace. This achieves very high fuel efficiency. Water-cooled grates prevent an excessive increase in temperature in the combustion zone of the coke residue, thereby preventing the fuel ash from caking. This is especially important when working with pellets High Quality or sawdust with high ash content. The sintering of ash forms a hard crust that interferes with the passage of fuel and air, which can cause the boiler to stop. Thus, the combustion zone is surrounded on all sides by a coolant, and the maximum heat released during the combustion of pellets is transferred to consumers.

Video of an automatic pellet boiler with a power of 30 kW at an exhibition in medium power mode
Boilers for working on sawdust are equipped with a fuel supply device, additionally equipped with a agitator with a separate drive.

The fuel path of all boilers is equipped with multi-stage fire protection.

The boiler delivery set includes:

• - Boiler (grid part, firebox, heat exchanger)
• - Fuel supply device (pellets or sawdust and pellets)
• - Block of control and alarm devices,
• - Blower fan

Modes: maximum power, medium power and pause mode.

When the load on the boiler is high, the maximum power mode is activated; as the outlet temperature increases, the boiler switches to the medium power mode. The supply of pellets and air is reduced. Thanks to the presence of the lining, the temperature in the furnace remains sufficient for efficient combustion of fuel. If the heating power in this mode is not enough, it switches to maximum power, but if the temperature rises after switching to medium power, the fan and fuel supply stop, after which the temperature inevitably decreases and the medium power mode starts again.

It turns out that the boiler, in the process of changing the load, switches automatically from one mode to another, depending on the heat removal.

The “pause” mode is the most disadvantageous. On the one hand, there is no fuel supply, which means there are no costs, but a significant amount of cold air passes through the boiler under the influence of pipe draft, taking away heat. Many people are familiar with how quickly a wood-burning stove cools down if the pipe is not laid in time; the same thing happens with the boiler. In addition, in a cooled firebox, effective combustion is not established immediately, but only with heating of the firebox; before this, some of the pellets do not burn completely, increasing the average consumption.

Considering that it is correctly selected in terms of power. The boiler for heating the house works on full power only at the most very coldy, and the rest of the time at medium power, the effectiveness of three-stage adjustment is obvious.

Most similar boilers have only 2 modes. With average power, typical for most of the heating season, such boilers are in “pause” mode for a significant time, uselessly heating the street.

A good alternative to gas heating equipment are solid fuel boilers on sawdust and wood chips. Fully autonomous sawdust and chip boilers are suitable for heating private and industrial facilities. Boilers are especially popular among cottage owners.

How does a sawdust-chip heating boiler work?

To increase efficiency, instead of the usual way burning wood chips, the principle of gas generator or pyrolysis combustion is used. The supply of sawdust and air is controlled by sensitive automation connected to thermostats. The error in adjusting the heating of the coolant is only 1-2°C.

The principle of operation of the burner for wood chips and sawdust

The efficiency of boilers operating on sawdust and wood chips reaches 92%. The use of a lambda probe in the device allows you to adjust the performance within the range of 30-100% (depending on the actual heat needs of the room), which increases the efficiency of the station.

Systems for supplying chips and sawdust to the burner

Using sawdust or wood chips as fuel for a hot water boiler is especially beneficial if there is a fuel source nearby: woodworking.

Automation of cleaning and ash removal

Requirements for wood chips and sawdust

1. No more than 8% bark.
2. 5% rotten remains.
3. 0.5% mineral impurities.

All sawdust undergoes mandatory double screening. After screening, raw materials with a diameter of 10 to 30 mm remain. The use of sawdust or wood chips for heating a country house or cottage that contains impurities and metal inclusions is strictly prohibited.

The boiler is able to operate on wet wood chips, but at the same time its thermal efficiency decreases. The pyrolysis process is possible only at a maximum humidity of no more than 20%.

The optimal sawdust moisture content for the pyrolysis process is 20%. This percentage of moisture contains raw materials produced in special processing plants and intended for heating.

Norms and rules for arranging a boiler room for a sawdust-chip boiler

Electrical equipment of the boiler room, metal parts of the boiler and screw transmission, are grounded. Connection to the power supply network is carried out directly to the switchboard. They install automatic machines and RCDs. Additionally, a voltage stabilizer and an alternative power supply source (generator or) are connected.

Which heating equipment using wood chips and sawdust to choose

• Boilers from European manufacturers are distinguished by high reliability of automation and mechanized fuel supply. The stations are equipped with a self-cleaning system, have high accuracy of adjustment and are equipped with a modulation system for changing power. Among European manufacturers, systems produced by the following companies stand out:
• Russian boilers - the main advantage is their low cost. On average, fully equipped systems will cost approximately 500-800 thousand rubles, compared to European analogues, the cost of which starts at 1.5 million. Russian boilers are adapted to the realities of domestic conditions. Not picky about fuel quality.
  The disadvantage is a not fully thought-out fuel supply mechanism that causes malfunctions, an insufficient safety system, and minor design flaws that reduce performance.

Pros and cons of choosing a sawdust-chip boiler

• Large footprint - the boiler is located in two adjacent rooms. Installation requires additional refurbishment of each room.
• High cost - compared to a conventional solid fuel boiler, automatic station has a price of 3-5 times more.
• Autonomy – a boiler equipped with a mechanized fuel supply can operate throughout the entire heating season without stopping.
• Economical - automation regulates the combustion process, choosing the most economy mode. Power modulation is possible within the range of 30-100%, which is unattainable for a conventional solid fuel boiler.

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A heat generator based on sawdust is currently rare, although it can be used to effectively heat a private house. Basically, sawdust heating boilers are produced by foreign companies.

Heating boilers using sawdust - operating principle

Sawdust heating boilers have a simple design, but despite this, they are able to effectively heat a house thanks to controlled combustion, three-stage air supply and gas generation of combustion products.

The process of converting fuel into thermal energy occurs in several stages:

1. Entering the combustion chamber, sawdust is automatically ignited and burned using a three-stage air supply system that provides swirling flames.
2. Under the influence of combustion, the heat exchanger heats up.
3. The gas formed during the combustion of fuel is sent to a special chamber where it is burned. Usually this compartment is installed additionally. Combustion products are removed through the smoke exhaust system.

Thus, the sawdust boiler is a large-scale installation - this can be seen by looking at the photo. Installation of this heating system is justified only if it is possible to allocate a large room for fuel storage and ensure constant replenishment of resources. For one hour of operation of a 25 kW boiler, about 40 kilograms of sawdust will be required.

Sawdust boiler design

It is more correct to call the boiler a whole station consisting of several elements:

1. Screw system. It provides an automated process for sawdust entering the hopper and combustion chamber.
2. Air pump. Such heating boilers are not able to operate without forced air injection into the firebox. An air pump is also present in devices that require manual insertion of sawdust. Air is forced into the firebox by fans in such a way that the necessary pressure and flame swirl are generated.
3. Gas generation chamber. It is not present in all models; sometimes it has to be installed additionally. Heating with sawdust is possible without this structural element. The heating efficiency in the presence of a gas generator compartment increases by 30-40%, and almost completely cooled air goes into the chimney. As a result, all the heat obtained from burning sawdust is accumulated and transferred to the coolant.
4. Exhaust fan. It is necessary if there is a gas generation chamber. Since cooled gas causes a decrease in thrust, its removal is only possible through the use of an exhaust device.
5. Automation. It serves to control the temperature and the rate of sawdust entering the combustion chamber. If necessary, you can buy equipment that allows you to control it remotely. If unexpected situations arise, the owner of the house will receive an alert on his mobile phone.

It is worth considering that sawdust boilers may have different configurations depending on the type of equipment and manufacturer. Installations are also created to order.

Types of sawdust boilers

• conventional - heat is generated only as a result of fuel combustion, such boilers are less profitable than those that have a gas generator chamber;
• with a gas generator element - more efficient units, may have different designs.

You can assemble a homemade sawdust boiler if you wish, but it will be the simplest design. As for automated heating systems, even domestic manufacturers cannot offer high-quality and economical equipment.

The German Hargassner models are considered the best - they are highly effective, but at the same time expensive. Some other foreign companies also produce high-quality boilers.

Cost-effectiveness of heating with sawdust

For a house with an area of ​​about 200 square meters, you will need a boiler with a capacity of about 25 kW. One hour of operation will require 40 kilograms of sawdust, so the fuel storage tank must be large enough. They are inexpensive, and if you buy them at woodworking enterprises, they will cost even less. Pressed sawdust for heating is also very profitable.

For comparison: gas equipment the same power consumes about 3 cubic meters per hour. meters. The cost of such a volume of gas is almost equal to 40 kilograms of sawdust. Thus, heating with a gas boiler costs the same amount as with sawdust-fired equipment. At the same time, gas boilers are much cheaper and do not take up as much space (read also: "").

Heating boiler using sawdust - video:

A universal-to-use, economical and easy-to-maintain sawdust boiler with your own hands will completely solve the problems with heating a country house or a small country house. The use of wood chips as fuel reduces the homeowner's heating costs, while such installations are highly functional and can operate on one fill for several days.

Operating principle of the boiler

Today, there are various designs of heating boilers operating on sawdust. These can be classic potbelly stoves with a thermal circuit connected to them. Modifications in which there is no ash pan are very popular, and fuel is loaded from above using a hopper and a mechanized auger, which makes it possible to automate the operation of heating equipment.

Modifications of boilers with a bunker are not only efficient, but also make it possible to significantly simplify the heating of a private home. The homeowner will not have to top up the fuel every day, and if high-quality dried sawdust is used, such heaters will be as efficient and economical as possible. Some modifications, which are equipped with larger combustion tanks and additional bins with sawdust, can operate on one load of fuel for 5-6 days, providing heat to a private house with an area of ​​150-200 square meters.

DIY pyrolysis boiler

The operating features of heating devices of this type include the following:

• Possibility of adjusting the air supply to the burner.
• Large volume of firebox.
• Increased area of ​​the water jacket and heat exchanger.
• Depending on the modification of the boiler, fuel combustion occurs from top to bottom or bottom to top.

Autonomous heating boilers using sawdust, which use the pyrolysis principle of operation, are popular. Such installations have several combustion chambers at once, allowing to significantly increase the efficiency of the equipment. In the lower firebox, the fuel smolders under the influence high temperatures Gas is released from the wood, which is burned in the upper compartments, which ensures the highest possible efficiency of the equipment.

Such long-burning sawdust boilers have a design similar to solid fuel pyrolysis plants. The only difference is the presence of an additional bunker and a special screw system that automatically supplies fuel to the combustion chamber.

Equipment advantages

The popularity of heating appliances that run on wood chips is largely due to the numerous advantages of this technology. Handmade A long-burning sawdust boiler has the following advantages:

• Safety of use.
• Ability to control raw material consumption and temperature conditions.
• Environmental friendliness of the equipment.
• Minimum fuel costs.
• Fast heating of the room.
• High efficiency.

Self-made sawdust boilers are characterized by versatility and efficiency. With the help of such heating equipment, you can easily heat a room of any size. Thanks to the simple design of the device, you can make it yourself, and subsequently you can buy fuel for free at sawmills or buy ready-made dried pressed sawdust briquettes.

Among the disadvantages of sawdust boilers, they note their increased requirements for fuel quality and its moisture content. You will also need to periodically clean the chimney from ash and soot. From the correctness of this service The efficiency of the equipment and its operational safety will directly depend.

Solid fuel pyrolysis boiler for: wood, sawdust, shavings, chips, biomass, pellets, briquettes

Operating modes and protective systems used

Factory models of boilers operating on wood chips and sawdust are equipped with various safety systems that prevent fire of the equipment, as well as its overheating. Some models also have additional sensors that detect high levels of carbon monoxide and can detect smoke, thereby warning of the danger of fire.

The equipment can operate in several modes at once:

• Maximum performance.
• Average power.
• Pause mode.

The maximum operating mode of the boiler is activated immediately after turning on the equipment and if the required amount of fuel is available in the bunker. As soon as the coolant and air in the room warm up to the required level, the automation will independently reduce the intensity of combustion, which will ensure efficient use of fuel.

The medium power mode allows the equipment to operate for as long as possible on one load of fuel. The intensity of sawdust combustion in the firebox is regulated by increasing or decreasing the flow of air into the combustion chamber. When this mode is activated, the boiler, equipped with additional automation, can maintain the room temperature at a given level.

In the “Pause” mode, the boiler does not heat the room, and fuel combustion stops or its intensity is reduced to a minimum. Subsequently, the homeowner can quickly heat the boiler by switching it to medium or maximum operating mode.

The presence of boiler operating modes allows us to guarantee the ease of use of the heating device, increasing the safety of its operation. In the presence of automatic system control, the homeowner can set the required coolant temperature at will, and the built-in sensors will reduce or increase the heating intensity, ensuring the comfort of living in a private home.

Long-burning mine boiler 25 kW on sawdust EVERYTHING from IGNITION to DYING. Video 1 / 2

Basic fuel requirements

The efficiency of a solid fuel boiler will largely depend on the quality of the fuel. It is recommended to use well-dried small chips of various types of wood. The following requirements apply to sawdust:

Certain modifications of boilers, which have the function of auto-loading fuel from the bunker, cannot work with sawdust with a moisture content of more than 40%. Therefore, due attention must be paid to the quality of chip drying. For ease of loading and storing such fuel, compressed sawdust is often used, which is offered at affordable prices, which significantly reduces the cost of heating a private home.

DIY making

On sale today you can find various modifications of autonomous heating boilers that burn wood chips and sawdust. Despite all their advantages, they have one significant drawback - the high cost of equipment. Therefore, many summer residents and owners of private houses make universal boilers on their own, since the simple design of such equipment allows you to construct it even in the absence of relevant knowledge and experience.

To make a wood chip boiler with your own hands, you will need the following tools and materials:

On the Internet you can find various drawings of the design of boilers operating on sawdust and wood chips. The easiest way to make such heaters is on the basis of a pipe or gas cylinder. You just need to use durable thick-walled steel, which will ensure the durability of a self-made boiler.

At this point, the work on manufacturing the heating boiler is completed. It is necessary to carry out a test run, check the quality of welding, and also make sure that there are no leaks in the water jacket, along the contour of which the coolant circulates. In the future, it is possible to modernize the heating boiler, to which a hopper with sawdust and a screw mechanism for automatically loading chips into the combustion chamber are additionally mounted.

Mine boiler on sawdust

By making a homemade pyrolysis boiler using sawdust and wood chips, you can not only solve problems with heating a small private house or country house, but also reduce the cost of living outside the city in winter time of the year. In specialized stores you can purchase ready-made industrial boilers that have one or two circuits, are completely safe to operate and are equipped with automatic control.

If necessary, it is possible to produce universal versions of autonomous heaters, which will differ in their power ratings, duration of operation from one fuel fill, as well as a number of other characteristics.

1. Industrial model
2. The working process
3. Learning how to properly light a stove

Sawdust stoves are not a new phenomenon, but they are still quite popular today. Such units only increase their popularity among the population every year due to their significant advantages. The design features of devices operating on wood waste contribute to long-term combustion of fuel with maximum heat transfer. Heating with sawdust, a cheap and environmentally friendly material, allows you to save significantly by purchasing inexpensive raw materials for heating a private home.

Sawdust stoves, as they are also called, do an excellent job of heating greenhouses, workshops, service stations, garages and not very large residential premises. The manufacture of such common boilers can be done with your own hands without much difficulty by first viewing the drawings and studying technological process assemblies. Here you can use any available containers such as old metal barrels, pipes, gas cylinders, of course, without contents, and other similar containers. Before making a sawdust stove with your own hands, which you plan to heat in the cold season, we suggest that you familiarize yourself with the design and features of industrial equipment, and based on it, draw conclusions about what a wood chip boiler should be like and how to handle its assembly.

Industrial model

On the modern market of heating devices, there are many models of boilers that use wood, or more precisely, its crushed waste, as fuel. Depending on the technical characteristics products, sawdust stoves can heat only a house or, in addition, outbuildings. Exists standard scheme, allowing to provide hot water supply for the heating system and household needs, where the main element is a double-circuit solid fuel pyrolysis boiler. Heat productivity in this case depends on the power of the sawdust boiler, as well as the quality and quantity of the specified fuel.

Advantages of modern units

The main advantages of factory-made heating devices for the home are:

• maximum automation of fuel combustion and stable maintenance of the required temperature. Chip boilers independently control how full the storage hopper is, from which sawdust is fed into the boiler by screw. Due to the fact that the automatic safety system is triggered in time, the fire augers do not allow the flame to spread back to the bunker;
• The automatic mode of ash ejection into a special collection relieves owners from stopping the system for manual intervention in the cleaning system. In this case, heating boilers using sawdust stop their operation only in case of problems in order to eliminate them;
• The sawdust heat generator is environmentally friendly, because here combustion is not accompanied by the release of ash from the chimney into the atmosphere, and the heated air goes through several degrees of purification from heavy particles, and only then enters the room. Meanwhile, the ash deposited by a special cyclone is disposed of without harming the environment;
• the vast majority of boilers operating on pressed or loose sawdust are distinguished by reliable operation and high heat transfer efficiency;
• full automation of the control system, which scans equipment for faults and alerts the operator about possible errors in operation, if any.

Disadvantages of factory-assembled boilers

This type of device that generates heat has practically no disadvantages, except that their cost, depending on the brand and model, can be very high. Also, sometimes problems arise with replacing failed components, which need to be ordered from the manufacturer and wait for the goods to be delivered, which is problematic during the heating season, when stopping the system is very undesirable.

Solid fuel sawdust boiler in action

It’s time to get acquainted with the operating technology of the unit, which will allow you to understand the principle of its operation:

1. The process begins with the automatic feeding of sawdust into a hopper equipped with a system of moving floors, from where it enters the conveyor.
2. The compressed or loose wood material is stored in a hopper until the sawdust burner compartment is empty, after which the movable floors come into operation. When the tank is completely filled, fuel will not be supplied until the tank begins to empty.
3. At the next stage, wood chips from the hopper are fed into the boiler using a wood chip and sawdust auger.
4. After entering the combustion chamber, the fuel is burned in full due to air supply. Further, the boiler operates continuously according to the same cycle discussed in these four points.

Homemade design: materials and assembly procedure

So, when we have figured out the structure and operating principle of the industrial design, we can begin to make a mini household unit similar in operation. First you need to stock up necessary tool and materials from which the stove will be assembled, namely we will need:

• welding machine;
• pipe of existing diameter (32 - 56 mm);
• gas exhaust pipe (100 mm);
• a set of adjustable and gas wrenches;
• Bulgarian;

• roulette;
• clock relay;
• temperature sensor;
• anti-explosion valve;
• water pump;
• ball valves (3 pcs) and couplings with screw threads;
• feed auger;
• ash removal auger (optional);
• metal corner 45 – 50 mm;
• hydraulic cylinder;
• 200 liter barrels for ash pan and sawdust (2 pcs);
• electric fan;
• sheet metal (4 mm);
• tow or fum tape.

The working process

The assembly of homemade sawdust boilers begins with the manufacture of the body and bottom of the unit. Everyone chooses the dimensions of the structure individually for themselves. With help welding machine a boiler body is formed without a bottom and covered with a water jacket. Homemade boilers can consist of empty gas cylinders, but we will focus on the welded version, which will allow you to vary the dimensions and power of the installation.

Next, it is necessary to make stiffening ribs between the water jacket, and also to provide technological openings through which air will be supplied from the fan to the combustion chamber. A “living” bottom is mounted from a metal corner, if provided, for which it is cut to dimensions of 50x25 mm and the output rod is attached to the cylinder. When the sawdust stove body is ready, it is mounted on the seat, an auger is installed to remove ash and a container is secured under it. Now you can install a fan, a screw that supplies wood chips, as well as a container for fuel, and you can say that the sawdust burner has been assembled with your own hands.

How to light a stove

In order for homemade sawdust stoves to operate as efficiently as possible, it is necessary to burn the fuel correctly. Initially, the crushed wood is placed in a barrel (or in a “live” bottom bunker) to the extent of 75% of its volume, after which the clock relay is activated and the auger feeds sawdust into the firebox, where it is ignited with special care with gasoline or diesel fuel. Next you need to turn on the fan.

There is another scheme for heating with wood chips, which differs slightly from the previous option, as it fits a simpler sawdust boiler, created by yourself (see photo).

To implement this, you need to fill the fuel chamber with sawdust to three-quarters of its volume, while it is recommended to press the crushed wood around a cone-shaped pipe. After compaction, the pipe is removed, the sawdust heating boiler is closed with a lid and the damper on the chimney is opened. Firewood is placed and lit in the lower part of the stove, the heat of which causes the sawdust to slowly smolder.

Now you know how to assemble a sawdust stove with your own hands, how it should work and how to fire it correctly. A well-made unit can provide economical heating of a small living space or any other outbuilding, and you can learn more about the operation of a potbelly stove from the video attached below.