Hydrolysis heating boilers. Hydrolysis boiler is a misnomer

The term “hydrolysis heating boilers” is used by some people by mistake, since such units do not exist. Most likely, when they say that, they mean pyrolysis boilers. The names are similar, but this is where the commonality between pyrolysis and hydrolysis ends - these are completely different processes.

Hydrolysis and pyrolysis - what is the difference

The pyrolysis boiler is always two-chamber.

In principle, there is no such thing as hydrolysis heating boilers. When the question is posed in this way, people often mean pyrolysis boilers, making a mistake in pronunciation. The process of pyrolysis and hydrolysis has one thing in common - this is the breakdown of a substance with the formation of new compounds under the influence external factors. The key difference lies in the influencing factors themselves.

Hydrolysis is an ancient Greek word that consists of two parts: hydro (water) and olisis (decomposition). This is the process of decomposition (solvolysis) of a substance under the influence of a solvent. Water acts as a solvent. That is, when water hits a substance, it activates the mechanisms for the decomposition of this substance into several components. By definition, there cannot be a boiler (hot water hydrolysis unit) in which heat is released from the energy carrier due to the action of water.

Pyrolysis is also an ancient Greek word that consists of two parts: pyro (fire or heat) and olisis (decay). That is, the process of decomposition of a substance into several components occurs under the influence of fire. This is exactly what we see in pyrolysis boilers. Their second name gas generator boilers, but in no way hydrolytic. This definition is incorrect.

Operating principle of pyrolysis boilers

Without a doubt, if you enter the query “hydrolysis boilers” into the search bar, you will not find anything intelligible, since such a definition is fundamentally incorrect. This is what is mistakenly called pyrolysis boilers, the operating principles of which we will discuss below.

The fuel must smolder.

The idea is to create conditions under which pyrolysis gas is released from solid fuel. For this:

is loaded into the boiler furnace solid fuel and is set on fire;
the air duct opens completely until the firewood flares up;
then the duct closes, the flame disappears, and the wood begins to smolder.

The purpose of such measures is to bring the temperature in the firebox to 500-800 degrees and ensure oxygen deficiency. Naturally, the firebox doors must close tightly so that the air flow is controlled only by the air duct damper.

So, pyrolysis gas has been released, but given that there is no flame in the firebox and very little oxygen, it cannot ignite. Therefore, it needs to be enriched with oxygen, as a result of which it will flare up and release heat. It turns out that in this way we take away from solid fuel thermal energy in two passes: the first time when the fuel is smoldering, and the second when the pyrolysis gases are burned out.

Design of pyrolysis boilers

We have already figured out that in the furnace to release pyrolysis gas there must be heat and necessarily oxygen deficiency. In this case, the pyrolysis gas will not ignite until it is mixed with air. That is why the boiler firebox is divided into two chambers. Fuel smolders in the upper one, and gas is burned in the lower one. For this purpose, there are special nozzles in the lower compartment through which secondary air flows.

One of possible options designs.

The afterburner is designed in such a way that the gas does not immediately fly out into the gas, but lingers until it is enriched with oxygen. The main design elements of a pyrolysis heater:

loading chamber with grates;
primary air supply pipe;
afterburner;
secondary air supply pipes;
chimney pipe.

Typically, in pyrolysis boilers, smoldering occurs from top to bottom.

Therefore, the afterburner is located at the bottom. Gas gets there under the influence of draft. The principle of burning fuel from top to bottom allows you to dry fuel that is not yet smoldering. For such heaters, the humidity of the wood is one of the key parameters. They should contain no more than 30% moisture. The drier the energy carrier, the higher the efficiency of the heater.

Advantages and disadvantages of gas generating plants

Pyrolysis (gas generator) boilers have many more advantages than disadvantages. For example, the disadvantages include the high cost of the unit, which has nothing to do with the operation of the heater. The only factor that needs to be taken into account in operation is the quality of solid fuel (we are talking about its humidity). In other respects, such units are better than simple boilers:

One download lasts a long time.

Efficiency 90-92%;
work on one load of fuel from 6 hours to 3 days, depending on the model;
more stable temperature.

In one of the articles we talked about, and these units are the leaders in terms of combustion duration. They have a large firebox; if you load it to the top, you can stay away from the heater for several days. The fuel burns out completely, almost no soot remains, which is also undoubtedly a plus. You can load unsplitted logs into the firebox, the length of which can be up to 60 cm.

Such boilers can operate in any water heating systems. You can connect a boiler to them indirect heating or, which stabilizes the heating circuit. Water can be used as a coolant, and in some models even non-freezing liquid.

Results

There are no hydrolysis boilers, since hydrolysis is the decomposition of one substance into several others under the influence of water. This is mistakenly called pyrolysis boilers, where the process of decomposition of solid fuel into solid particles and pyrolysis gas also occurs, but under the influence of heat. Despite the similarity of names, the essence of the matter is completely different. Pyrolysis heaters are also called gas generator heaters, but the term “hydrolysis boilers” is absurd.

Hydrolysis heating boilers are devices that operate on solid fuel. Firewood, straw, wood waste, pellets, granules, etc. are suitable as fuel for such boilers. Hydrolysis boilers have become widespread in heating systems of industrial and domestic premises (warehouses, workshops, farms, greenhouses, factories, etc.). The advantages of such boilers include their efficiency, high environmental friendliness, as well as ease of operation, cleaning and maintenance. Hydrolysis heating boilers can be used even in areas where there are frequent interruptions in the supply of electricity and main gas.

Solid fuel boilers work like this:

Fuel is loaded into the bunker, set on fire and the door is closed. In this case, you need to start the smoke exhauster.

When the temperature in the boiler rises from 200 to 800ºC, charring of the combustible materials occurs and wood gas is released. This process is called hydrolysis.

When hydrolysis products fall into the grate, they mix with secondary air.

The part of the heat that returns to the bottom layer of firewood helps support the hydrolysis process.

One of the stages preparatory work When installing a floor-standing boiler, it is necessary to install a foundation pad or support frame, the height of which should be from 10 to 20 cm. By installing the support frame, you can ensure the horizontal position of the seating surfaces.

Boilers are most often installed on brickwork, not exceeding 360 mm in height from the boiler room floor, this is necessary so that the lower side screen collectors are flush with the grates and serve as cooled panels. Installation of smoke exhausters also begins with the installation of a support frame, which is attached to the foundation with bolts.

Once-through steam boilers

Boilers of this type are equipped with a steam shut-off valve, a pressure gauge with three-way valve, two piston feed pumps, electrical panel, purge valve and purge valve to start the boiler. The components of a horizontal once-through steam boiler are a working pressure switch, safety safety valves, a flow switch, a pressure gauge with a three-way valve, and an overpressure valve.

What is the pipe for?

The boiler pipe plays an important role in the operation of the boiler. These products, being part of the heating system, have some absolutely justified requirements for their quality. Pipes used in the form of a chimney in heating system, must withstand pressure and temperature changes, high humidity and heavy contamination. Therefore, manufacturers must strictly adhere to the parameters established in the technical specifications and GOSTs when producing these products.

Only seamless boiler pipes are suitable for boiler installations, since the seam can concentrate stress and reduce corrosion resistance, strength and lead to destruction of the product itself. The pipe wall thickness should be from 0.5 to 18 mm. (See also: )

Steel chimney pipes can be column, truss, façade, mast, or self-supporting. These pipes are made from special durable steel, which is extremely resistant to corrosion. They are mounted to existing structures. For steam boilers, a special type of pipe is used, which can be safely operated at supercritical steam temperatures.

Calculating the heat balance of the boiler

The heat balance of the boiler is easily calculated as follows. It is taken into account that during the operation of a water heating boiler, all the heat entering it must be spent on generating useful heat, which is contained in superheated steam. The total amount of heat that enters the boiler is called available heat and is indicated in the form QPP. There must be equality between the heat entering the boiler and the heat leaving it. The heat released from the boiler is the sum of useful heat and heat losses associated with the process of generating superheated steam. That is, the heat balance of a boiler for 1 m3 of gas burned under normal conditions looks like this:

QPP= Q1 + Q2 + Q3 + Q5

QРР - available heat, (kJ/m3);

Q1 - useful heat contained in hot water, (kJ/m3);

Q2 - heat loss with gases that escape (kJ/m3);

Q3 - heat loss from chemically incomplete combustion, (kJ/m3);

Q5 - heat loss of the boiler due to temperature environment, (kJ/m3).

100 = q1 + q2 + q3 + q5

You can often find a turbocharged boiler in the homes of our compatriots. Its distinctive quality is the presence of an exhaust fan in the design. The fan creates the air draft necessary for the emission of combustion products, and forces this air into the combustion chamber, which is necessary for the combustion process itself.

This design is used for the manufacture of wall-mounted boilers equipped with a combustion chamber closed type. Using turbocharging, you can use horizontal chimneys to get rid of combustion products, and this circumstance will greatly simplify installation gas boiler and will eliminate the need to install a major chimney. If there is a lack of draft, turbofans can also be used in floor-standing boilers.

Use of materials is permitted only if there is an indexed link to the page with the material.

Under hydrolysis heating boilers It is customary to understand equipment that uses solid fuel during operation. Straw, wood waste, firewood - all this can be used by hydrolysis boilers during operation. This equipment is most widely used in household and production premises, be it factories, workshops, warehouses or farms. The main advantages of data are that they are inexpensive to operate, environmentally friendly, and easy to maintain and manage.

Hydrolysis devices operate according to the following scheme:

The fuel is placed in a special bunker where it is ignited. The bunker door closes, the smoke exhauster is activated;
Increasing the temperature to 800 degrees causes the combustible material to char, releasing significant amounts of wood gas. It is this process that is called hydrolysis;
The entry of hydrolysis products into the grate leads to their mixing with secondary air;
The hydrolysis process is constant due to the fact that part of the heat is constantly returned to the layer of firewood located below.

Installation and maintenance

When a hydrolysis boiler is installed on the floor, it is necessary to pre-install a support frame with a height of 10-20 centimeters, or a foundation pad. By installing the support frame, it is possible to ensure that all mounting surfaces are exactly in the horizontal plane.

As a rule, boilers are mounted on brickwork, the height of which is no more than 36 centimeters from the floor surface. This approach is necessary so that the lower collectors of the screens located on the side are at the same level with the grate bars, and therefore serve as cooled panels. The installation of smoke exhausters also begins with the installation of a support frame, which is fixed to the foundation with strong bolted connections.

An important difference between hydrolytic ones is the material from which they are made.

Features and service life

The heat exchanger can be made from steel or cast iron. Solid fuel boilers, which are made on a cast iron basis, are considered more durable. Their main nuance is that they warm up for quite a long time, but also cool down extremely slowly, giving off maximum heat.

The negative feature is the fragility of the equipment: cast iron is extremely sensitive to sudden temperature changes, which will inevitably cause destruction of the walls of the device and its subsequent complete failure. Fortunately, modern technological solutions in the production of cast iron made it possible to improve its properties, increasing its strength indicators.

Solid fuel boilers on a steel base are able to withstand temperature fluctuations more steadfastly, but their weakness lies in their susceptibility to rust, which begins to actively develop due to condensate accumulations. It is this feature that leads to the fact that a steel heat exchanger significantly reduces the service life of boilers. In many ways, the service life of a steel boiler depends on the quality of the material, its thickness, and careful handling.

Taking this factor into account, we can say that a cast iron boiler, despite its initial high cost, will ultimately be a better purchase.

It is also worth noting such an additional detail of the hydrolysis boiler as the presence of a special fan that forces air into the combustion chamber. This, in general, simple device can significantly increase the efficiency of the device.