Principle of operation of the pyrolysis boiler

Having a solid understanding of the technology underlying our heating systems is essential to maintaining a warm and comfortable home. The pyrolysis boiler is one cutting-edge option that is becoming more and more popular in the home heating market. In contrast to conventional boilers, which use direct fuel combustion to produce heat, pyrolysis boilers use a different strategy that makes use of the pyrolysis process.

What precisely is pyrolysis, then? In essence, pyrolysis is a chemical reaction that takes place when organic materials, like wood or biomass, are heated without the presence of oxygen. Unlike traditional burning, which involves the direct combustion of the material, pyrolysis breaks down the organic matter into gases, liquids, and solid residues, releasing energy in the form of heat that can be used to heat our homes.

Let’s now examine the operation of a pyrolysis boiler. Imagine that you are filling the boiler chamber with biomass, such as wood. The pyrolysis process starts when the boiler is lit, heating the chamber. Combustible gases like methane and carbon monoxide, as well as liquids like tar and charcoal, are released when the organic matter breaks down. After that, these byproducts are directed into a different combustion chamber and lit there to generate heat.

The efficiency of pyrolysis boilers is one of their main benefits. These boilers are able to extract more energy from the same amount of fuel than traditional boilers because they make use of the gases and liquids that are produced during the pyrolysis process. Additionally, pyrolysis is a more environmentally friendly option because it produces fewer harmful emissions like carbon dioxide and particulate matter because it occurs in the absence of oxygen.

Moreover, the kind of biomass that pyrolysis boilers can use is highly versatile. These boilers can use a wide range of materials, from wood chips and sawdust to agricultural residues and even some types of waste biomass, giving homeowners flexibility and possibly lowering heating costs.

In conclusion, knowing how pyrolysis boilers work opens the door to a creative and environmentally responsible method of heating your home. These boilers, which use the power of pyrolysis to achieve efficiency, lower emissions, and a variety of fuel options, are a promising choice for homeowners who care about the environment and want to stay warm while leaving as little carbon imprint as possible.

In understanding how a pyrolysis boiler works, imagine it as a sustainable heat magician. Instead of burning wood directly like traditional boilers, it performs a clever trick called pyrolysis. Here"s the scoop: wood is heated in a low-oxygen environment, causing it to break down into gases, tar, and charcoal. These gases then ignite, producing heat that"s used to warm your home. Meanwhile, the charcoal left behind is burned in a separate chamber, generating even more heat. It"s like getting a double dose of warmth from a single batch of wood! Plus, since pyrolysis releases fewer pollutants than traditional burning, it"s kinder to both your wallet and the environment. So, with a pyrolysis boiler, you"re not just heating your home – you"re doing it efficiently and sustainably.

What a gas generator consists of?

The main difference from the classic wood-fired boiler is the presence of an additional combustion chamber in which the released gas is afterburning, and in the primary furnace it is generated from firewood with insufficient amount of oxygen. The layout of the chambers and the device of the pyrolysis boiler can be different, the furnace can be located both below and above, the principle of operation does not change this. Traditionally, it is located at the bottom, above the ash pan, in which a drawer is placed for easy cleaning. The ash pan cover is hinged upwards and in the operating mode serves to regulate the amount of air entering the furnace. This is realized by means of a chain drive, which is tensioned or released by a thermostat. The latter is installed in the upper part of the boiler.

Operating principle of the pyrolysis boiler

A detailed drawing of the pyrolysis boiler will show you all the important components and installation details. A door for loading firewood is installed on the main furnace, and it is kept securely closed while it is in use. The secondary combustion chamber, which houses the air supply devices, is positioned above it. Although they may appear differently in units made by different manufacturers, they all have the same function, which is to supply heated air to the afterburning chamber through a number of holes with a specific diameter. The route from the ash pan door to the distributors involves air heating.

The pyrolysis boiler’s design allows for the possibility of cleaning the upper afterburning chamber; a special door is included for this purpose. The combustion gases are elevated through a channel that connects the spaces of the two chambers. Both furnaces heat the body’s outer layer, which is a water jacket. Threaded sockets are cut into the cooling system to supply coolant to the heating system. Instruments on the front panel track the pressure and temperature of the water.

The design of the chimney for a pyrolysis boiler is the same as that of the pipes used to expel combustion products from traditional units. One prerequisite is that there must be enough draught for the boiler to operate. Since the unit’s basic design does not allow for the installation of a blowing fan, combustion is achieved through natural draft. The insulation of the portion of the pipe that is situated on the street is the second prerequisite. The reason is that flue gases can reach temperatures of up to 150 °C, which greatly increases the likelihood of condensation and the quick deterioration of chimney material.

Description of pyrolysis boilers operation scheme

A schematic diagram of the pyrolysis boiler can be obtained with a thorough understanding of the unit’s operation. First, fuel is added to and ignited in the main furnace. The ash pan flap is fully opened simultaneously. The door begins to close as soon as the firewood is ignited, and the burning process slows down and becomes smoldering. Then, as wood gas rises and enters the secondary afterburning chamber, it begins to emit intensely. There are several calibrated openings through which heated air is supplied. The latter gets heat from the furnace’s hot wall as it travels through the same opening beneath the ash pan cover to enter the duct.

Diagram of a boiler circuit

The natural draught produced by the chimney drives the entire technological process, which is why the air and flue gas velocities in the channels are low. The pyrolysis boiler works by igniting wood gases through a thermochemical reaction between heated air and the gases in the secondary chamber. Consequently, tiny volatile particles as well as gases are burned, making chimney smoke nearly invisible. Since the combustion products from pyrolysis combustion produce substantially fewer carbon and nitrogen oxides as well as ash particles, it is actually more environmentally friendly than traditional combustion.

Firewood in the firebox burns slower than usual, so one load may be enough for 10-12 hours of operation, depending on the power of the gas-generator unit and the moisture content of the firewood. Adjustment of the pyrolysis boiler consists in limiting the supply of combustion air. Too little of it will not allow the thermochemical process to start in the secondary furnace, and too much will cause incomplete combustion of gases and decrease the efficiency of the unit. For a natural draught appliance, it will be necessary to adjust the air flow rate on a case-by-case basis, as the height and diameter of the chimney can vary greatly. Accordingly, the thrust force will be different. In some cases it must be increased by raising the chimney to a greater height.

The appliance’s settings are limited to adjusting the heating medium’s desired temperature if the chain drive of the ash pan cover has a thermostatic regulator installed. The thermocouple integrated into the gas generator set’s water jacket controls the circuit drive by acting on the water’s temperature and opening or closing the damper, which modifies the degree of combustion.

A comparison between solid fuel boilers and pyrolysis

Pyrolysis boilers are also fitted with a blowing fan and a series of automatic controls to produce an artificial draught that is independent of the chimney’s parameters. The blowing machine helps to develop the efficiency of a conventional unit up to 93%, if it can only operate at 85–90% efficiency. This has a drawback: reliance on outside energy sources.

Advantages and disadvantages

These kinds of heat sources have numerous benefits:

• The principle of action and operation of pyrolysis boilers allows you to achieve excellent efficiency indicators when burning solid fuel – 90-93% efficiency factor.
• The process is more environmentally friendly, much less harmful substances are emitted into the atmosphere.
• The interval between fuel loadings is not less than in the case of long burning units – 12 hours, you will have to work as a stoker not more than 2 times a day.
• Maintenance and cleaning of the unit is not a problem, the entire interior space is accessible, and many units are equipped with a sliding ash drawer. The principle of operation of the pyrolysis boiler is practically waste-free, there is very little ash and ash, so the operation should be performed infrequently.
• Cost-effectiveness. Approximately the fuel consumption per 100 m² of the room at its height up to 3 m is 10 kg per day.
• Installations operating on natural draught do not depend on the availability of electricity in the network.

The Pyrolysis heating boiler requires protection against the coolant inside the water jacket boiling, just like any other solid fuel-operating apparatus. This may result in the shells rupturing and expensive repairs. This is the reason why producers add extra water cooling heaters to their goods so that they can simultaneously provide hot water for domestic needs.

Among the drawbacks of units of the pyrolysis type are the following:

• Requires fuel with low moisture content, the moisture content of firewood should not exceed 25%. The process of intensive extraction of afterburning gases is greatly hampered if the wood is frankly raw. This negatively affects the operation of the pyrolysis boiler, reducing its efficiency.
• The practice of operation shows that on the walls of the primary chamber with time appear deposits of tar and resins, because the temperature in it is relatively low, and as a fuel most often take birch or softwoods. This plaque must be periodically removed, it hinders the transfer of heat to the water jacket.
• The cost is higher than the classic solid fuel boiler. This is justified, because the technology of the process is more progressive and gives high performance, which will save money in operation.

Gaining an understanding of a pyrolysis boiler’s working principle reveals an intriguing procedure that uses the force of nature. These boilers work on the principle of pyrolysis, which is the natural process by which organic materials break down in the absence of oxygen. Gases that can be used for heating are released during this breakdown.

The combustion chamber, which is the central component of a pyrolysis boiler, is where biomass or wood is heated in an oxygen-free atmosphere. The organic material breaks down into combustible gases like methane, hydrogen, and carbon monoxide as a result of pyrolysis, which is sparked by this oxygen shortage. A secondary combustion chamber receives these gases after which they are directed, where they ignite and release heat energy.

Boilers that use pyrolysis have several benefits, two of which are their low emissions and high efficiency. These boilers achieve impressive levels of energy conversion with minimal environmental impact by using the gases produced during pyrolysis. For heating homes and buildings, this makes them a sustainable and environmentally beneficial choice.

Additionally, because pyrolysis boilers are capable of efficiently burning a variety of biomass, such as wood chips, pellets, and agricultural residues, they provide a wide range of fuel options. Due to this flexibility, homeowners can select from a variety of easily accessible and renewable fuel sources, which lessens their reliance on fossil fuels and helps them achieve carbon neutrality.

To sum up, the working principle of a pyrolysis boiler illustrates how creativity and nature can work together to produce effective and long-lasting heating solutions. These boilers provide a promising route towards future heating practices that are greener and more environmentally friendly by utilizing the power of pyrolysis.

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