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Brick rocket stove. How to make a rocket stove to heat your home. Video: homemade rocket stove from a gas cylinder

Simple heating device, which is not much inferior in popularity to the potbelly stove, is the rocket stove. It runs on wood, and the design is so simple that production is possible on your own. The stove can also be made economical - many people think that looking like a potbelly stove means the combustion chamber is gluttonous, but no. There are schemes that operate on smoldering wood (pyrolysis), which means they are economical with the same efficiency.

Why rocket and why jet

Such a stove is often called a “rocket”, but not because the wood in it burns at a high speed, but because of the shape of the structure - the traditional version of the rocket stove is made from two sections of iron pipes welded to each other. The unit resembles a rocket in a child's drawing. Using a simplified form allows you to make it in less than a day. The adjective “reactive” is also used for the stove, but also not because of the rate of fuel combustion, but because of the combustion characteristics - at a certain stage of supplying air to the firebox, it begins to hum strongly, as if the turbocharging of the injectors in the engine is turned on.

A humming stove is an inefficient and wasteful combustion mode. During normal operation, it makes a quiet rustling sound.

Any owner of a country or country house has at least a minimum set of carpentry, plumbing and automotive repair tools in his workshop. These are the ones that will help in the manufacture of a miracle rocket, plus drawings and a minimum supply of materials: pipes or metal boxes, a sheet of iron and - when building a stationary version - brick and mortar on clay. Now it becomes clear that the jet stove is made portable or stationary, for example, for heating a house or bathhouse.

If a stationary jet stove will heat the house, then it is placed along the outer wall. Properly designed and equipped, it can heat a house with an area of ​​up to 50m2. The stove is also installed in an open area - on a personal plot, and is used as a summer option for cooking.

How does a rocket stove work?

The device is the simplest - two principles of fuel combustion, borrowed from other stoves:

1. Natural circulation of hot gases and smoke through the stove channels is a standard solution, as in a potbelly stove.
2. Afterburning of unburned gases (pyrolysis) with limited access of oxygen to the combustion chamber.

The circuit of the simplest reactive stove, which is intended only for cooking, uses precisely the natural combustion of wood - in open cell it is impossible to create conditions to maintain the pyrolysis reaction and afterburning of unburnt gases.

Let's consider a simple design rocket stove direct combustion, which is traditionally installed in the yard in an open area. You can quickly heat water on it or prepare lunch for your family on vacation. From the figure below it becomes clear that such a sample will require two pieces of cylindrical or rectangular iron pipe, which are connected to each other by welding at an angle of 90 0.

A horizontal section of a metal box acts as a combustion chamber; firewood is placed there. Fuel loading can also be arranged vertically - add from above horizontal pipe vertical iron cylinder for loading firewood. Thus, you will get a structure of three pipes or boxes, the lowest of which (horizontal) will work as a firebox. In a stationary scheme, the simplest stove design often uses red brick, which is placed on a clay mortar.

The efficiency of the design cannot be called satisfactory, so the craftsmen figured out how to increase its efficiency. The additional element is another pipe of larger diameter (as you can see, all materials are available and cheap), into which the main pipe of the riser stove (primary chimney) is installed. This increases the overall heating and the duration of heat retention.

On the diagram:

1. Outer casing.
2. A pipe that serves as a firebox.
3. A channel for air outlet into the combustion chamber.
4. Insulated area between the body and the riser. The same ash can serve as insulation.

How to heat

The Robinson jet stove is heated according to the principle of starting a fire - paper, hay, straw or other flammable material is laid first, then small chips or large shavings. The last logs to be placed are the size of the firebox. Hot combustion products rise through the vertical pipe (2) and exit outside. You can place a pan or tank of water on the open end of the pipe (2).

In order for the fuel to burn continuously and actively, it is necessary to provide a gap between the outlet pipe (2) and the pan of water using a special lattice metal stand.

The diagram below shows a simple device with a door on the opening for loading fuel. Air draft is formed due to the presence of a special channel formed by the lower surface of the firebox and an iron plate welded 8-10 mm from the combustion chamber. This design will force air to be pumped in even if the door is completely closed. It is clear from the diagram that the design is also designed to operate in pyrolysis mode, while a constant flow of a “secondary” air stream will burn the exhaust gases. But in order for afterburning to take place 100%, it is necessary to equip the thermal insulation of the secondary chamber in which the gas burns out in order to ensure the required temperature indicators for pyrolysis.

On the diagram:

1. Forced channel for blowing air when the combustion door is closed.
2. Active combustion area.
3. Burnt gases.

The improved scheme provides not only the possibility of heating the surrounding space, but also cooking, for which the upper hob is designed. Total: to the very simple option“rocket”, you can add an outer casing, which will additionally heat the room, combustion door, blowing air to maintain the pyrolysis mode and a stove for cooking food. This scheme can already be implemented in the house itself, and not in the yard, since the chimney pipe is led outside. This minor upgrade significantly increases the efficiency of the model. Thus, a do-it-yourself rocket stove, the drawings of which are presented below, has the following capabilities:

1. Due to the inclusion of an outer casing made of a larger diameter pipe and its insulation, which creates a thermal insulation layer for the riser, as well as the ability to hermetically close the upper pipe hot air takes much longer to cool down.
2. A separate channel for blowing has been added to the lower section of the stove, which makes it possible to organize pyrolysis combustion.
3. In this design, it is recommended to place the chimney not vertically at the top, but at the bottom at the back of the body, which will allow for additional circulation of hot flows through the internal channels of the stove, ensuring quick heating hob and the entire insulated body.

In the firebox (1), the fuel does not burn completely (2), since the air supply is not complete - this is mode “A”, which can be controlled using the damper (3). Gases that are hot, but not burned out from pyrolysis, are supplied to the end section of the fire channel (5), in which they are burned. Afterburning is ensured by high-quality thermal insulation and a constant flow of “secondary” air in mode “B” through channel (4).

The hot stream then enters the internal riser (7), rises up to the cooking plate (10) and heats it. Next, hot air enters the volume (6) between the outer and inner pipes, insulated with a layer of ash (4, 9), heats the furnace body, which releases heat into the room. Finally, the cooled air falls down to enter the chimney (11) and exit out.

Consistently high temperature in the riser (7) ensures maximum heat transfer and creates conditions for complete combustion of gases due to the placement of the riser in the pipe larger size– shell (8). The free space is filled with ash or other heat-resistant substance (9) for lining - this can also be a solution of ordinary clay and sand in proportions 1:3.

The palm of popularity belongs to the industrial model “Robinson” - it is a simple but reliable design. Having such a mobile stove, you can quickly cook food or heat water at the dacha or on a hike. Structurally, it is an inverted L-shaped pipe, as shown in the diagrams below.

Firewood is placed in the horizontal section of the fuel receiver, and ignition is carried out from the side where the vertical pipe enters. In an L-shaped pipe, due to the difference in pressure of hot and cold air, draft arises, and the intensity of combustion will only increase as the furnace body heats up. The air supply is regulated by a slide damper.

The furnace operates on the principle of using the energy of a natural flow of hot gases. It turns out to be a closed cycle: as the temperature rises, the fuel begins to burn more actively and the chamber and cooking surface heat up faster. As a result, Robinson is able to heat 10 liters of water in 10 minutes if you place the tank on an already warm surface. The diagram shows that the hob in Robinson has a thick thermal insulation layer, which allows large diameter logs to be placed in the firebox.

Stationary oven

Stationary models have a hood to keep the heat in the room longer. In such a stove, fuel combustion occurs according to a different scenario. The beginning of the wood combustion process is the same - the air supply is limited. This causes the release of pyrolysis gases, which are burned in the lower section of a vertical pipe or box, where secondary air is supplied separately.

The hot gas, once at the top, begins to cool and falls into the free inter-chamber volume, and then into the chimney. It happens like this:

1. Gravity forces force cooler, and therefore heavier, burnt gases to rush downward, where they enter the chimney.
2. This is facilitated by the constantly maintained pressure from the added firewood and the consistently high temperature of the gases.
3. Natural draft in the chimney pipe.

All this creates effective conditions for burning wood and it becomes possible to attach a smoke channel with arbitrary geometry to the “rocket”. Basically, long and complex chimneys are needed in order to better heat the room.

The main disadvantage of all solid fuel stoves is the inability to retain most of the heat in the house. But positive qualities allow you to level out the negative aspects - the high gas escape rate allows you to organize complex vertical or horizontal chimneys with several channels. The implementation of this principle in practice is the Russian stove. In a jet stove with a horizontal multi-channel chimney, you can also equip a warm bench, as shown in the diagram below.

A rocket stove is a home heating option that can only be cheaper for nothing. A person familiar with the basics of construction can build a combined brick stove in a design suitable for any home interior. The main task of refining appearance There will be decoration of the iron cap and firebox lid - everything else will not be in plain sight.

Combined brick-metal barrel stove

It is stationary, because the structure cannot be moved. The fuel chamber and chimney are made of fireclay bricks, and valves and doors are made of metal. Brick gives off heat very slowly, so the room will be warmed for a long time.

High efficiency- not the strong point of such models, but good heat transfer can be achieved by adjusting the air supply to the chamber, without trying to reach a combustion mode in which the stove begins to “roar” and “hum.”

In order to somehow minimize heat losses when operating this simplest design, many craftsmen build a water circuit into the stove and connect a hot water tank. Also, the preservation of heat in the room is facilitated by the construction of a couch with a multi-channel horizontal chimney. Negative qualities of “rocket” models that cannot be minimized or eliminated:

1. Constant monitoring and adjustment of traction is required - no automatic devices are provided.
2. Every 2-3 hours you need to load a new portion of firewood.
3. The iron cap heats up to dangerous temperatures.

The simplest and cheap option– model “Robinson”, which is in the drawing below. To make it, you need cuttings of pipes or a rectangular profile box, metal corners for the legs, and a welding machine. Its dimensions are selected based on the dimensions of the workpieces. The main thing is to adhere to the principle of action, not the size.

For homemade design They often take 200-liter gas cylinders or barrels - thick walls and the appropriate size are exactly what was intended. Both are used to make the outer casing, and the internal elements are made from pipes of smaller diameter or are laid out with bricks - in halves, quarters or whole.

There is no general formula for calculating heat transfer for all models of a rocket stove, so the option of using ready-made calculations based on the principle of similarity of circuits is quite suitable. The main thing is that the size of the future “rocket” at least approximately corresponds to the volume of the heated room. For example, it will do for a garage gas cylinder, for a country house - a two-hundred-liter barrel. An approximate selection of internal elements is shown in the diagram below.

Iron cylinder stove

1. Cylinder – gas, oxygen, carbon dioxide.
2. Pipe ≥ 150 mm for fuel and loading chambers.
3. Pipes 70 and 150 mm - for internal vertical chimney.
4. Pipes 150 mm - for the outlet chimney.
5. Insulation of any type, always non-flammable.
6. Sheet metal blanks H = 3 mm.

The upper part of the cylinder is cut off by welding. To be safe, it is best to open the shut-off valve on it and fill it with water before cutting. On the sides you need to cut openings for the fuel chamber and chimney. The pipe under the firebox is connected to the vertical pipe of the chimney channel from the bottom of the cylinder.

After installing the internal elements, the cut top is welded back. The seams are checked visually and the main chimney is connected. If there is a water circuit, it is connected too. After this, the rocket stove can be tested.

Sufficient draft is ensured by the height of the chimney pipe - it must be raised above the firebox by at least 4 meters.

How to lay a firebox out of brick

This model requires the use of only fireclay (clay) bricks - ceramic or silicate bricks will immediately crack. The masonry is carried out using clay mortar, the proportions of the composition are indicated above. A pit is dug under the base of the stove, the soil at the bottom is compacted and poured concrete mortar. The size of the foundation is 1200x400x100 mm.

After the base has hardened, it is protected with a sheet of basalt cardboard, then they begin to lay out the firebox, vertical chimney and loading chamber. A door is attached to the front of the firebox for removing ash. After drying clay mortar the trench is backfilled and a pipe of the required diameter is inserted into the vertical chimney. The cavities between the brick and the pipe should be filled with insulation - basalt wool, ash or other non-flammable material, for example, asbestos.

Now a Ø 600 mm cap is placed on the masonry - a cut-out lid from a metal barrel will do. Before installation, a hole is cut in it into which the chimney pipe is inserted. When putting on this cap, the barrel should be turned over, and the pipe will be where it is needed. Then the chimney is brought out - either directly to the street, or through the arrangement of a sunbed with horizontal chimney channels. The lounger can be laid out as usual sand-lime brick, since the temperature of the gases will already be low.

Dear visitors to the site “” today we will look at detailed instructions By self-assembly Do-it-yourself camping rocket stove without welding. The jet furnace appeared relatively recently and was invented abroad, but in a short period of time it gained popularity in our Country. people's love and respect, especially among tourists, fishermen and hunters, and of course, this stove is distinguished by its efficiency in the consumption of firewood and the output of the maximum amount of heat due to the jet thrust created by the design of the stove itself. With its help, you can quickly prepare food or boil a kettle, which is very important during a hike.

The design of a jet stove is very simple - it is a vertically located pipe (also known as a body and a chimney) and a firebox adjacent at an angle, divided inside by a plate into two parts (top for loading firewood, bottom for air access to the combustion center), thus creating jet draft, from here and a great name « «.

The presented stove is made with compactness in mind, since every gram of cargo and space in a backpack is very important on a hike. To make it, a used helium cylinder was taken (you can use a fire extinguisher), its upper part was sawed off, and a technological hole was sawn on the side for installing the firebox, the design is completely dismountable and all the parts are located inside the body in the stowed position. We remind you that during its manufacture a welding machine is not needed, which simplifies the creation process to the maximum.

Let's look at all the stages of assembling a jet stove.

Materials

1. helium cylinder or used fire extinguisher
2. square pipe
3. metal perforated plate
4. bolts and nuts
5. metal sheet 1-2 mm

Tools

1. grinder (angle grinder)
2. drill
3. pliers
4. can of heat-resistant paint

Step-by-step instructions for creating a traveling rocket stove.

First, let's look at the drawing of the domestic Robinson stove. It is also an excellent design, but welded, and the one presented below is much universal and is rightfully considered a camp stove.

The first thing you need to do is find a used helium cylinder or an old fire extinguisher, bleed out the remaining contents, unscrew the valve and rinse with water, then cut it off top part, as well as make a technological hole in the lower part for installing a firebox from square pipe.




We make a grate from a perforated plate.
Support legs for the firebox.
We collect all the details into a single whole.

A pointed metal pin is screwed into the lower part; it is necessary so that when installing the stove in the working position, it stands firmly on the ground, and this stake is buried in the ground. In the stowed position it unscrews. We cut out a burner from 1-2 mm sheet metal.




By the way, here is the pin in the stowed position.
Also, in addition to the components from the stove, you can put a small supply of dry firewood in the cylinder, which can be very helpful in damp and rainy weather. Just imagine... you went on a hike and you were caught in heavy rain, everything around you was wet, damp and disgusting, and you calmly took out your camping stove-rocket and make a fire, cook food, boil the kettle and everything is fine with you 😉
Additionally, a cable was pulled to secure the firebox.
This is such a wonderful stove; its advantage is that it is economical, compact, and collapsible.

This design is made without the use of welding, which simplifies the assembly process as much as possible for those people who do not have a welding machine or do not know how to use welding. We hope our material was useful to you. You can also watch a video of the oven in action. Enjoy watching!

They are still very often used for heating buildings. various ovens. They are suitable for baths or saunas, as well as a variety of outbuildings.

They can be intended to form full-fledged heating, which will highly efficient and reliable. As a rule, pipes are installed simultaneously with the stove, which makes it possible to use the design for heating several rooms at once.

What is a rocket stove?

A DIY rocket stove is considered a rather interesting option for any room. Its design is original and it fits as for a private home, and for the bath, as well as for other types of structures. When creating it with a contour, expensive materials are not required; the dimensions are selected depending on the dimensions of the heated room, but it is important in advance make the right drawing to obtain an efficient and durable device. If the correct and current scheme is used, then you can do it yourself quality water heating indoors.

Operating principle of the furnace

The rocket stove operates on two specific principles. They are borrowed from other popular stoves that are supposed to be used for heating. These two principles include:

• , consisting in afterburning wood gases that arise during fuel combustion;
• the principle of free passage of gases through various channels, available in the equipment.

If the simplest design is assumed to be used for cooking, then the second principle of operation is applied, since it does not contain elements suitable for creating pyrolysis.

The direct combustion wood rocket stove, which is the simplest, is not used for heating, but is suitable for cooking food, it has small sizes , and pipes are used to form it. The design of the unit consists of a short pipe, which is a firebox. It is in it that the fuel is placed, and during its combustion, hot gases arise, rising upward and escaping.

Read also: Why does a potbelly stove smoke when the door is opened?

A special cut is made in the pipe where you can cook food, and such a device is suitable for the home that is used very rarely in winter. This type of stove is not suitable for heating, but it is very easy to find old pipes to create one, and if you watch the training video, the work can be easily implemented independently.

For heating a house or bath it is best to use improved equipment. It is usually created from bricks and metal sheets, and pipes are also used. “Robinson” is complemented by a heat exchange device and special channels for gas removal. The oven is also equipped with a suitable circuit, high quality and reliable shirt.

Such long-lasting equipment is usually used to form water and quality heating , which can be used for home with a large number rooms different sizes. A video showing the operating principle of this equipment can be found easy to find on the Internet.

What are the pros and cons of a stove?

The rocket stove has positive and negative parameters. The advantages include:

• installation of equipment for a house using bricks, pipes and metal are simple;
• the cost of long-term equipment will be low;
• the ability to do the work with your own hands, since there are no difficulties in the process of laying bricks, when working with a contour, when installing a pipe or other elements, also rarely have to deal with modifications;
• such a furnace can be used to create full water heating;
• the dimensions of the equipment may vary depending on the heated room;
• Efficiency is very high, and the water heater turns out to be durable and reliable:
• Loading fuel for heating rooms is quick and hassle-free.

Wood rocket the stove also has disadvantages, which include:

• for heating it is important to use high-quality and completely dry, otherwise it will not be possible to achieve the desired combustion;
• Robinson oven requires constant human presence and control for safety of use.

Read also: Potbelly stoves for the home

What needs to be done before the actual work?

Initially, all materials and equipment should be prepared, and also drawings. It is important to determine the size of the future equipment, as well as decide what the its design and other parameters.

If the oven will be used to create water heating, then it is necessary to prepare pipes of the required quantity and quality. For masonry, you need to use heat-resistant red brick, since then you will get a long-burning stove that will not be dangerous to use and will also last a long time.

The use of brick is justified only for creating a stationary oven. A metal barrel and pipes for the chimney, a water heater, fittings and some other consumables are also purchased, thanks to which you will get a full-fledged stove for high-quality and uniform water heating of the building.

Since the rocket stove will have a water circuit, it is important to decide whether a heat exchanger will be purchased for an already created stove or whether it will be created to fit the dimensions of an existing device.

The process of creating a furnace

Forming a Robinson oven is considered a simple process, but it is best to first watch several videos to accurately understand all the nuances. The work is carried out in the following stages:

• a hole of suitable depth and size is created in the floor, which is intended for installing a stove chimney with a contour;
• a metal barrel is placed that protrudes into as a special cap, and it should be coated with heat-resistant paint to create a durable structure that does not deteriorate during fuel combustion;
• installation of a foundation for a furnace from bricks with water circuit, and for this, formwork is initially installed, and two or more bricks are deepened, then reinforcement is laid on the bottom and bricks are laid around the perimeter, after which the base is poured;
• After preparing the foundation, you can begin laying a furnace with a long-term circuit, and for this it is important to constantly refer to available drawings;
• During laying, it is important to place a flange in the barrel, with which chimney will be connected, a tee of a suitable type is also installed, thanks to which the pipes will be cleaned;
• on the rising part water heating element is installed, to which pipes intended for water heating are connected;
• the base of the resulting rocket stove must be surrounded with sandbags, and all holes and gaps are covered with clay;
• connects chimney pipe the right size , on the ascending part of which a metal barrel is mounted;
• checking the functionality of a rocket stove with a circuit designed for long-term burning, and if problems are detected, all problems are eliminated.

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Let's say right away: rocket stove - a simple and convenient heating and cooking device using wood fuel with good but not exceptional parameters. Its popularity is explained not only by its catchy name, but moreover by the fact that it can be made with one’s own hands and not by a stove maker or even a mason; if necessary - literally in 15-20 minutes. And also because, by investing a little more work, you can get an excellent bed in your home without resorting to complex, expensive and bulky construction. Moreover, the very principle of the design of the rocket stove gives greater freedom to design and the manifestation of creative abilities, see fig.

But perhaps more remarkable is the “jet furnace” for the huge number of, at times, completely absurd inventions associated with it. Here, for example, are a few pearls snatched at random:

• “The principle of operation of the furnace is the same as that of the MIG-25 ramjet engine.” Yes, the MIG-25 and its descendant MIG-31 did not even sit down in the bushes near the ramjet engine (ramjet engine), as they say. The 25th and 31st are powered by double-circuit turbojet engines (turbojet engines), four of which later pulled the Tu-144 and still power other vehicles. And any oven with any jet engine(RD) – technical antipodes, see below.
• “Reverse jet thrust furnace.” Is the stove flying tail first, or what?
• “How will she blow through such a pipe?” A non-pressurized oven does not blow into the chimney. On the contrary, the chimney draws from it, using natural draft. The higher the pipe, the better the pull.
• “The rocket stove is a combination of a Dutch bell stove (sic!) with a Russian stove bench.” Firstly, there is a contradiction in the definition: a Dutch oven is a channel oven, and any bell-type oven is anything other than a Dutch oven. Secondly, the bed of a Russian stove warms up completely differently than a rocket stove.

Note: in fact, the rocket stove was so nicknamed because in the wrong combustion mode (more on that later), it makes a loud whistling hum. A properly tuned rocket stove whispers or rustles.

These and similar inconsistencies, understandably, confuse and prevent you from making a rocket stove properly. So let's figure out what the truth is about the rocket stove, and how to use this truth correctly so that this really good stove shows all its advantages.

Furnace or rocket?

For complete clarity, we still need to figure out why a stove cannot be a rocket, and a rocket cannot be a stove. Any RD is the same as an internal combustion engine, only the escaping gases themselves act as pistons, connecting rods with a crank and transmission. In a piston internal combustion engine, already at the moment of combustion, the high temperature of the working fluid creates a lot of pressure, which pushes the piston, and it moves all the mechanics. The movement of the piston is active, the working fluid pushes it to where it itself tends to expand.

When fuel is burned in the combustion chamber of the thruster, the thermal potential energy of the working fluid is immediately converted into kinetic energy, like that of a load falling from a height: since the outlet for hot gases is open to the nozzle, they rush there. In the RD, the pressure plays a subordinate role and nowhere exceeds the first tens of atmospheres; this, for any conceivable nozzle cross-section, is not enough to accelerate the migar to 2.5 M or launch a satellite into orbit. According to the law of conservation of momentum (amount of motion), the aircraft with a taxiway receives a push in reverse side(recoil impulse), this is jet thrust, i.e. thrust from recoil, reaction. In a turbofan engine, the second circuit creates an invisible air shell around the jet stream. As a result, the recoil impulse is, as it were, contracted in the direction of the thrust vector, so a turbofan engine is much more economical than a simple turbofan engine.

In a furnace there is no conversion of energy types into each other, therefore it is not an engine. The stove simply distributes potential thermal energy appropriately in space and time. From the point of view of the furnace, an ideal RD has an efficiency = 0%, because it only pulls due to fuel. From the point of view of the jet engine, the stove has an efficiency of 0%, it only dissipates heat and does not draw at all. On the contrary, if the pressure in the chimney rises to or above atmospheric pressure (and without this, where will the jet thrust or active force come from?), the stove will at least smoke, or even poison the residents or start a fire. The draft in the chimney is without pressurization, i.e. without external energy consumption, it is ensured due to the temperature difference along its height. Potential energy here, again, is not converted into any other energy.

Note: in a rocket thruster, fuel and oxidizer are supplied to the combustion chamber from the tanks, or they are immediately refueled into it if the thruster is powered by solid fuel. In a turbojet engine (TRE), the oxidizer - atmospheric air - is pumped into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes some of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the jet power, which is transmitted to propeller and compressor. In a ramjet engine (ramjet), the air supply to the combustion chamber is ensured by hypersonic speed pressure. A lot of experiments have been carried out on ramjet engines, but there have been no production aircraft with them, there are none, and there are no plans to do so, as ramjet engines are too capricious and unreliable.

Kan or not Kan?

Among the myths about the rocket stove, there are some that are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the “racket” with the Chinese kan.

The author had the opportunity to visit the Amur region in winter, in the Blagoveshchensk region, as a child. Even then there were a lot of Chinese living in the villages there, fleeing in all directions from the cultural revolution of the Great Chairman Mao and his completely frostbitten Red Guards.

Winter in those parts is not like Moscow, frost of -40 is common. And what amazed and aroused interest in stoves in general was how Chinese fanzas were heated by canals. Firewood is transported to Russian villages by carts, and smoke comes out of the chimneys in a column. And all the same, in a hut made of logs not the size of a child’s girth, by morning the corners from the inside were frozen. And the fanza is built like a country house (see picture), the windows are covered with fish bladder or even rice paper, bunches of wood chips or twigs are placed in the can, but the room is always warm.

However, there are no subtle thermal engineering wisdom in the can. This is an ordinary one, only small, kitchen stove with a lower exit into the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is located. The chimney, for fire safety reasons, is outside the building.

The effectiveness of the can is determined primarily by the thermal curtain it creates: the couch goes around, if not the entire perimeter from the inside, except for the door, then certainly 3 walls. Which once again confirms: the design and parameters of the stove must be linked to those of the heated room.

Note: The Korean Ondol stove operates on the principle of a warm floor - a very low stove occupies almost the entire area of ​​the room.

Secondly, in the very cold, the Kans were drowned with argal - the dried droppings of ruminant animals, domestic and wild. His calorific value quite large, but argal burns slowly. In fact, an argal fire is already a long-burning stove.

It is not the Russian custom to constantly stick twigs into the oven, and our men disdained to cook food in cattle feces. But travelers of the past highly valued argal as a fuel; they collected it along the way and took it with them, carefully protecting it from getting wet. N. M. Przhevalsky in one of his letters stated that without argal he would not have been able to conduct his expeditions in Central Asia without losses. And the British, who disdained argal, had 1/3-1/4 of the detachments’ personnel returning to base. True, he was recruited from sepoys, Indian soldiers in English service, and pandits - spies recruited from the local population. One way or another, the highlight of the rocket stove is not at all the bed on the hog. To get to it, you will have to learn to think like an American: all the primary sources on the rocket furnace are from there, and utter speculation is generated only and only by misunderstanding.

How to deal with rockets?

With our view of things, it is necessary to study the original technical documentation of rocket stoves with caution, but not at all because of inches-millimeters, liters-gallons and the intricacies of American technical jargon. Although they also mean a lot.

Note: a textbook example is “Naked conductor runs under the carriage.” Literary translation - a naked conductor runs under the carriage. And in the original Petroleum Engineer article, this meant “Bare wire runs under the crane trolley.”

The rocket stove was invented by members of survival societies– people with a unique way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they automatically always converted everything into money, taking into account their own benefit; a person with a different worldview simply will not get along in America. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of spiritual impulse, but with the expectation of dividends. Not in this life, so in the next.

Note: How much the average citizen of the greatest empire in history is afraid of everything can only be understood by talking to them long enough. And sociopsychologists go out of their way to convince you that living in fear is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Without heating and cooking, of course, you cannot survive. What is a stove for? For the time being, the survivors were content camping stoves. But then, according to the Americans themselves, in 1985-86. they were greatly impressed by two films that were released with a short interval and triumphantly went around all the screens of the world: the Soviet science fiction parody of the entire human race “Kin-dza-dza” and the Hollywood “The Day After”, about the global nuclear war.

The survivors realized that after the nuclear winter there would be no extreme romance, but there would be the planet Plyuk in the Kin-dza-dza galaxy. The newly-minted plukans will have to be content with “ka-tse” in small quantities, bad, expensive and difficult to obtain. Yes, in case anyone hasn’t watched “Kin-dza-dza” - ka-tse in Plyukan style, a match, a measure of wealth, prestige and power. It was necessary to come up with your own furnace; none of the existing ones are designed for post-nuclear blast.

Americans are very often endowed with a sharp mind, but a deep mind is found as a rare exception. A completely normal US citizen with an IQ above average may sincerely not understand how it is that someone else does not get what he himself has already “caught up with” and how someone else may not like what suits him.

If an American has already understood the essence of the idea, then he brings the product to its possible perfection - what if a buyer is found, you can’t sell raw iron. But technical documentation, which looks beautiful and neat, can be drawn up extremely carelessly, or even deliberately distorted. What's wrong with this, this is my know-how. Maybe I'll sell it to someone. Either there will be a trick or not, but for now know-how costs money. In America, such an attitude to business is considered quite honest and worthy, but there, a clinical alcoholic at work as a stopper would never miss a job and wouldn’t take a couple of bolts home for the farm. That, in general, is what all of America stands for.

And Russian breadth of soul is also a double-edged sword. Our master most often just from the sketch immediately understands how this thing works, but in the little things he turns out to be careless and overly trusting of the source code: how is it for a fellow craftsman to deceive his own man. If something isn’t there, well, it’s not necessary. It seems clear how everything is spinning there - my hands are already itching. And then, perhaps, until it comes to the hammer, chisel and accompanying literature, still count and count. Yes, even important points may be omitted, veiled or obviously incorrect.

Note: An American acquaintance once asked the author of this article - how did we, really stupid ones, choose the very smart Reagan as president? And you, who are really smart, tolerate a slobbering senile with dyed eyebrows in the Kremlin? True, then in America no one in a bad dream would have dreamed that in the next century a black citizen with a Muslim name would be installed in the Oval Office, and his first lady would dig up a vegetable garden near the White House and begin to grow turnips there. Times is changing, as Bob Dylan once sang for a completely different reason...

Sources of misunderstandings

There is such a thing in technology - the square-cube law. Simply, when the size of something changes, its surface area changes by the square, and its volume changes by the cube. Most often, this means changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. In relation to solid fuel stoves, the square-cube law is doubly valid, because the fuel also obeys it: it releases heat from the surface, and its reserve is contained in the volume.

Note: a consequence of the square-cube law - any specific furnace design has a certain permissible range of its size and power, within which the specified parameters are ensured.

Why, for example, can’t it be made the size of a refrigerator and with a power somewhere around 50-60 kilowatts? Because a potbelly stove, in order for it to provide any heat, must itself be heated inside to at least 400-450 degrees. And in order to warm up the volume of the refrigerator to such a temperature at a given heat transfer, you need as much firewood or coal as will not fit in it. A mini-potbelly stove will also be of no use: the heat will escape through the outer surface of the stove, which has grown relative to its volume, and the fuel will not release more of it than it can.

The square-cube law applies threefold to the rocket stove, because she is “polished” in an American professional way. With our kondachka it is better to stay away from her. For example, here in Fig. an American development, which, judging by its demand, many of our craftsmen take as a prototype.

The fact that the exact type of fire clay is not indicated here will be something that our people will figure out later. But, to be honest, who noticed that, judging by the absence of an external chimney and the presence of transportation holes (carrying pipe), this stove is mobile with an open firebox? And most importantly, the fact that her drum used a 20-gallon barrel with a diameter of 17 inches (431 mm with change)?

Judging by the designs from the RuNet - no one at all. They take this thing and adjust it according to the principle of geometric similarity to a domestic 200-liter barrel with a diameter of 590 mm on the outside. Many people think of setting up a ash pit, but the bunker is left open. The exact proportions of vermiculite and perlite for lining the riser and molding the furnace body (core) are not specified? We make the lining homogeneous, although from what follows it will be clear that it should consist of an insulating and accumulating part. As a result, the stove roars, it eats only dry fuel, and a lot of it, and before the end of the season it becomes covered in smoke inside.

How was the rocket stove born?

So, without science fiction and futurology, the survivors needed stove for heating a home, operating with high efficiency on low-quality random wood fuel: wet wood chips, twigs, bark. Which, in addition, will need to be reloaded without stopping the furnace. And it most likely won’t be possible to dry it in a woodshed. Heat transfer after heating is needed for at least 6 hours to get enough sleep; getting burned in your sleep on Plyuk is no better than in America. Additional conditions: the design of the furnace should not contain complex metal products, non-metallic materials and components that require production equipment for manufacturing, and the furnace itself must be accessible for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics or other energy dependencies.

They immediately took a bed from the kana, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning stoves even operate on sawdust, but only dry ones, and do not allow stopping with additional loading. They were still taken as a basis, it was very attractive high efficiency, achieved in simple ways. But in attempts to make “long stoves” work on bad fuel, another circumstance became clear.

What is wood gas?

High efficiency is achieved largely due to the afterburning of pyrolysis gases. Pyrolysis is the thermal decomposition of solid fuel into volatile combustible substances. As it turned out (and the survivors have their own research centers with highly qualified specialists), the pyrolysis of wood fuel, especially wet wood, continues for quite a long time in the gas phase, i.e. The pyrolysis gases that have just been released from the wood still require quite a lot of heat to form a mixture that can burn out completely. This mixture was called wood gas.

Note: in RuNet, woodgas has created further confusion, because... in American vernacular gas can mean any fuel, cf. eg gas station - gas station, gas station. When translating primary sources without knowing American technical knowledge, it turned out that woodgas is simply wood fuel.

Before that, no one had seen wood gas: in conventional stoves it is formed immediately in the firebox, due to the excess energy of flaming combustion. The designers of long-burning furnaces came to the conclusion that the primary air needs to be heated, and the exhaust gases must be retained in a significant volume over a large mass of fuel, simply by trial and error, so they also overlooked wood gas.

This was not the case when burning bundles of twigs: here the draft immediately pulled the primary pyrolysis gases into the chimney. Wood gas could have formed in it at some distance from the firebox, but by that time the primary mixture had cooled, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney as soot. Which quickly tightened the channel completely; Hobbyists who build rocket stoves at random are familiar with this phenomenon. But the survival researchers eventually realized what was going on, and still made the necessary stove.

Who are you, the Rocket Stove?

There is an unspoken rule in technology: if it seems that it is impossible to create a device according to the given requirements, then, smart guy, read your school textbooks. That is, go back to basics. In this case, to the basics of thermodynamics. Survivors do not suffer from sick pride; they turned to the basics. And they found the main operating principle of their furnace, which has no analogues in others: slow adiabatic afterburning of pyrolysis gases in a low flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume subject to the square-cube law and an energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but almost into the free volume. And now we are learning to think like an American.

How does a rocket stove work?

A diagram of the final fruit of the survivors' labors is shown on the left side of Fig. Fuel is loaded vertically into the bunker (Fuel Magazine) and burns, gradually settling down. Air enters the combustion zone through the ash pan (Air Intake). The blower should provide excess air so that it is enough for afterburning. But not excessively, so that the cold air does not cool the primary mixture. With vertical loading of fuel and a blind hopper lid, the regulator, however, is not very effective, but the flame itself acts as a regulator: when it gets too hot, it pushes out the air.

Then things begin to become non-trivial. We need to heat up a large oven with good efficiency. The square-cube law does not allow it: the meager heat will immediately dissipate so much that pyrolysis will not reach the end, and the thermal gradient from the inside to the outside will not be enough to transfer heat into the room; everything will whistle down the pipe. This law is harmful, you can’t break it in the forehead. Okay, let's look at the basics to see if there is anything there that is beyond his control.

Well, yes, there is. The same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares rest, and the cubes can be reduced either to a thimble or to a skyscraper.

Let's imagine a volume of gas completely isolated from everything else. Let's say energy is released in it. Then the temperature and pressure will begin to increase until the energy release stops and freeze at a new level. Great, we have completely burned the fuel, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do this without technical difficulties? And most importantly, how to supply air for afterburning without violating the adiabatics?

And we will make the adiabatic process nonequilibrium. How? Let the primary gases immediately from the combustion source go into a pipe covered with high-quality insulation with a low intrinsic heat capacity (Insulation). Let’s call this pipe a fire tube or a combustion tunnel (Burn Tunnel), but we won’t sign it (know-how! If you don’t catch up, give us money for drawings and consultations! Without theory, of course. Who sells fixed capital at retail.) On the diagram, so that not accused of “opacity”, let’s denote it with flame.

Along the length of the flame tube, the adiabatic index changes (this is a nonequilibrium process): the temperature first drops slightly (wood gas is formed), then increases sharply, and the gas burns out. You can release it into a storage tank, but we forgot - what will the gases be drawn through the flame tube? Supercharging means energy dependence, and there will not be an exact adiabatic, but something mixed with an isobar, i.e. efficiency will drop.

Then we will lengthen the pipe by half, maintaining the insulation, so that the heat does not go away in vain. We bend the “idle” half up, making the insulation on it weaker; We’ll think about how to preserve the heat seeping through it a little later. In a vertical pipe there will be a temperature difference in height, and, therefore, draft. And a good one: the thrust force depends on the temperature difference, and with an average temperature in the flame tube of about 1000 degrees, it is not difficult to achieve a difference of 100 at a height of about 1 m. So, while we have made a small, economical stove-stove, now we need to think about how to use its heat.

Yes, it doesn’t hurt to further encrypt it. If we call the vertical part of the flame tube a primary or internal chimney, then they will guess the main idea, but we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipes with rising current - a riser. Purely American: correct and unclear.

Now let's remember about heat transfer after heating. Those. we need a cheap, always available and very capacious heat accumulator. There is nothing to invent here; adobe (Thermal Mass) was invented by the primitives. But it is not fire-resistant, it does not hold more than 250 degrees, and at the mouth of the riser we have about 900.

It is not difficult to convert high-potential heat into medium-potential heat without losses: you need to give the gas the opportunity to expand in an isolated volume. But, if you leave the expansion adiabatic, then the volume needed is too large. This means it is material and labor intensive.

I had to go back to basics again: immediately after leaving the riser, let the gases expand at constant pressure, isobarically. This requires heat removal to the outside, about 5-10% of the thermal power, but it will not be lost and will even be useful for quickly warming up the room during the morning fire. And further along the flow of gases – cooling is isochoric (in a constant volume); Thus, almost all the heat will go into the battery.

How to do this technically? Let's cover the riser with a thin-walled iron drum (Steel Drum), which will also prevent heat loss from the riser. The “drum” turns out to be a little high (the riser sticks out a lot), but it doesn’t matter: we will coat it 2/3 of the height with the same adobe. We attach a stove bench with a sealed chimney (Airtight Duct), external chimney(Exhaust Vent), and the oven is almost ready.

Note: The riser and the drum covering it look like a stove hood above an elongated heil. But the thermodynamics here, as we see, are completely different. It is useless to try to improve a bell-type stove by building on it - only extra material and work will go away, and the stove will not get any better.

It remains to solve the problem of cleaning the channel in the bed. To do this, the Chinese have to break down the kan from time to time and wall it up again, but we are not in the 1st century. BC We live when kan was invented. We will install a secondary ash pit (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of the flue gases in it, everything in them that has not burned out immediately condenses and settles. This ensures the cleanliness of the external chimney for years.

Note: Secondary cleaning will have to be opened once or twice a year, so you don’t have to bother with the hinge-latches. Let's just make a lid from a metal sheet with screws and a mineral cardboard gasket.

Small rocket

The next task of the designers was to create a small continuous combustion stove on the same principle for cooking food in the warm season. During the heating season, the drum cover (Optional Cooking Surface) of a large oven is suitable for cooking; it heats up to about 400 degrees. The small rocket stove had to be portable, but it was permissible to make it with an open firebox, because When it’s warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law by making it work for themselves: they combined the fuel bunker with the blower, see Fig. at the beginning of the section on the right. This cannot be done in a large furnace; precise adjustment of the furnace mode as the fuel settles (see below) will be impossible.

Here, the volume of incoming primary air (Primary Air) turns out to be small relative to the area of ​​heat release and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the hopper lid (Cover Lid). The hopper, inclined at 45 degrees, optimizes the automatic adjustment of oven power for standard culinary procedures, but it is more difficult to make.

Secondary air for afterburning wood gas in a small stove enters through additional holes in the mouth of the riser or simply leaks under the burner if a cooking vessel is placed on it. If the small stove is close to the maximum size (about 450 mm in diameter), then for complete afterburning you may need an Optional Secondary Woodgas Frame).

Note: It is impossible to supply secondary air to the mouth of the riser of a large furnace through holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas and smoke path is lower than atmospheric, as it should be in a furnace, due to strong turbulence, flue gases will be emitted into the room. This is where their kinetic energy, which is harmful to the furnace, comes into play; This is perhaps the only thing that a rocket stove has in common with a jet engine.

The small rocket stove revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (Bond stove in the West) will help you cook a stew or wait out a snowstorm in a one- or two-person tent, but it won’t save a group caught in a spring hike by belated bad weather. A small rocket stove is only slightly larger; it can be quickly made out of nothing, but is capable of developing power up to 7-8 kW. However, we’ll talk about rocket stoves made from just about anything later.

Also, the small rocket stove gave rise to many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for constructing a compact and fairly powerful water heater, see the video below. The large rocket oven was also modified, we will talk about this a little at the end, but for now we will focus on more significant things.

Video: water heater based on a rocket stove designed by Gabriel Apostol

How to sink a rocket?

A rocket stove with long-burning stoves has a common property: You only need to run them on a warm pipe. For a small one this is unimportant, but a large one on a cold chimney will only burn fuel in vain. Therefore, before loading standard fuel into the bunker after a long break in the firebox and kindling, a large rocket stove needs to be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open ash pit. The end of acceleration is judged by a change in the tone of the furnace hum or its subsidence. Then you can load fuel into the bunker, and it will ignite automatically from the booster fuel.

The rocket stove, unfortunately, is not one of the stoves that is completely self-adjusting to the quality of the fuel and external conditions. At the beginning of combustion of standard fuel, the ash door or hopper lid in a small furnace is opened completely. When the stove starts to hum loudly, cover it “to the point of a whisper.” Further, during the combustion process, it is necessary to gradually cover the access of air, guided by the sound of the stove. Suddenly the air damper slammed shut for 3-5 minutes - no big deal, if you open it, the oven will light up again.

Why such difficulties? As the fuel burns, the flow of air into the combustion zone increases. When there is too much air, the furnace explodes, but do not rejoice: now the excess air cools the primary gas mixture, and the sound intensifies because the stable vortex in the riser is knocked into a chaotic lump. Pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and a deposit of soot cemented with bituminous particles settles in the riser. This, firstly, is a fire hazard, but most likely it won’t lead to a fire; the riser channel will quickly become completely overgrown with carbon deposits. How to clean it if you have a non-removable drum cover?

In a large furnace, a spontaneous change of mode occurs abruptly, when the top of the sticks drops to the bottom edge of the hopper, and in a small furnace - gradually, as the fuel mass settles. Because when cooking on the stove experienced housewife does not leave it for a long time, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

This trick will not work with a large stove: the high riser pulls very hard, and the air gap needs to be so thin (and it also needs to be adjusted) that it is impossible to achieve a stable stove mode. It’s easier with a separate blower: it’s easier for the air to flow around the sides of a mass of fuel that is round in cross-section, and a flame that gets too hot pushes it there. The stove turns out to be self-regulating to some extent; however, within very small limits, so you still have to manipulate the blower door from time to time.

Note: It is impossible to make a bunker for a large oven for the sake of simplicity without a tight lid, as is often done. Due to the unregulated additional air flow through the fuel mass, it is unlikely to be possible to achieve stable operation of the furnace.

Materials, sizes and proportions, lining

Now let's see what a homemade rocket stove should look like from the materials available to us. Here, too, we need to be careful: not everything that is at hand in America is what we have, and vice versa.

From what?

For a large stove with a stove bench, more or less reliable experimental data is available for products with a drum from a 55-gallon drum with a diameter of 24 inches. 55 gallons is 208-odd liters, and 24 inches is almost exactly 607 mm, so our 200-liter is quite suitable without additional conversion. While maintaining the oven parameters, the diameter of the drum can be halved, to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

The ash pit, bunker, firebox and riser will use pipes of different sizes, see below, round or profile. This way it will be possible to make an insulating lining of the firebox from a mixture of equal parts of oven clay and crushed fireclay, without resorting to brickwork; We’ll talk about the riser lining in more detail below. Combustion in a rocket furnace is weak, therefore the thermochemistry of gases is gentle and the thickness of the steel of all metal parts, except for the gas pipeline in the stove bench, is from 2 mm; the latter can be made from a thin-walled metal corrugated sheet, here the flue gases are already completely exhausted both in terms of chemistry and temperature.

For external coating, the best heat accumulator is adobe. If the dimensions indicated below are observed, the heat transfer of a rocket stove in adobe after combustion can reach 12 hours or more. The remaining parts (doors, covers) are made of galvanized metal, aluminum, etc., with sealing gaskets made of mineral cardboard. Conventional stove fittings are not suitable, it is difficult to ensure their tightness, and a cracked rocket stove will not work properly.

Note: It is advisable to equip the rocket stove with a view in the external chimney. Although the gas vent in the high riser seals the overall smoke path tightly, strong winds outside can suck the heat out of the bench prematurely.

Dimensions and proportions

The basic calculated values ​​to which the rest are tied are the diameter of the drum D and its area cross section inside S. Everything else, based on the size of the available iron, is determined as follows:

1. Drum height H – 1.5-2D.
2. Drum coating height – 2/3H; For the sake of design, the edge of the coating can be made oblique and curved, then 2/3H should be maintained on average.
3. The thickness of the drum coating is 1/3D.
4. Riser cross-sectional area – 4.5-6.5% of S; It's better to stay within 5-6% of S.
5. The height of the riser is the larger the better, but the gap between its edge and the drum tire must be at least 70 mm; its minimum value is determined by the viscosity of the flue gases.
6. The length of the flame tube is equal to the height of the riser.
7. The cross-sectional area of ​​the flame tube (fire duct) is equal to that of the riser. It is better to make the fire duct from a square corrugated pipe, so the furnace mode will be more stable.
8. The cross-sectional area of ​​the blower is 0.5 of its own firebox and riser. A more stable furnace mode and its smooth adjustment will be provided by a rectangular corrugated pipe with sides 2:1, laid flat.
9. The volume of the secondary ash pan is from 5% of the original volume of the drum (excluding the volume of the riser) for a stove from a barrel to 10% of the same for a stove from a cylinder. Interpolation for intermediate drum sizes is linear.
10. The cross-sectional area of ​​the external chimney is 1.5-2s, where s is the cross-sectional area of ​​the riser.
11. The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is counted from its lowest point. If the bed is on wooden floors, the pillow under the chimney can be halved.
12. The height of the coating of the stove bench above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. You can do less, but then the heat transfer after heating will be shorter.
13. The height of the external chimney is from 4 m.
14. The permissible length of the gas duct in the bed - see next. section

The maximum thermal power of a rocket stove made from a barrel is approximately 25 kW, and a stove made from a gas cylinder is about 15 kW. The power can be adjusted only by the size of the fuel load. By supplying air, the oven is put into operation, and nothing more!

Note: in the original survivalist stoves, the riser cross-section was taken at 10-15% S based on very wet fuel. Then, there, in America, rocket stoves with a bungalow bench appeared, designed for air-dry fuel and more economical. In them, the riser cross-section is reduced to the recommended ones and here it is 5-6% S.

Riser lining

The efficiency of a rocket stove largely depends on the thermal insulation of the riser. But American lining materials, alas, are not available to us. In terms of reserves of high-quality refractories, the United States has no equal; there they are considered strategic raw materials and are sold even to trusted allies with caution.

From our available materials for heating engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-excavated bricks river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous; in the oven they will quickly become saturated with carbon deposits. Then the oven will roar with any air supply, with all that follows. Therefore, we need to surround the riser lining with a metal shell, and the end of the lining must be covered with oven clay.

Lining diagrams for 3 types of furnaces are shown in Fig. The point here is that as the size of the drum decreases, the share of its direct heat transfer through the bottom and unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining power can be reduced. This makes it possible to correspondingly increase the relative cross-section of the annular lowering of the flue gases in the drum.

For what? Firstly, the requirements for the external chimney are reduced, because The external rod now pulls better. And since it pulls better, then the permissible length of the hog in the bed drops more slowly than the size of the stove. As a result, if a stove from a barrel heats a stove bench with a length of up to 6 m, then a stove made from a cylinder half as long is 4 m.

How to line with sand?

If the riser lining is fireclay, then the residual cavities are simply filled with construction sand. There is no need to carefully prepare a river self-dug for lining entirely from sand; just select large debris. But they pour it in layers, in 5-7 layers. Each layer is compacted and sprayed until a crust forms. Then the entire backfill is dried for a week, the top edge is covered with clay, as already mentioned, and the construction of the furnace continues.

Balloon rocket

From the above, it is clear that it is more profitable to make a rocket stove: less work, fewer unsightly parts in sight, and the stove warms up almost the same. Thermal curtain or a warm floor in the Siberian frost will heat a room of 50 square meters with a power of 10-12 kW. m or more, so here, too, a balloon rocket turns out to be more profitable; a large barrel will rarely have to be launched at full power with maximum efficiency.

The craftsmen apparently understood this too; at least some. For example, here in Fig. – drawings of a balloon furnace-rocket. On the right is the original; the author seems to have wisely understood the initial developments and, in general, everything turned out right for him. On the left are the necessary improvements taking into account the use of air-dry fuel and heating the bed.

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the fire tube can be made shorter. The cross-sectional area of ​​its air duct is about 10% of the riser cross-section. The oven always operates with the secondary completely open. First, the mode is set by the primary valve; Precisely adjust with the hopper lid. At the end of the firebox, the stove will roar, but here it’s not so scary; to clean the riser, the author of the design provides a removable drum cover. It, of course, must have a seal.

Rockets made from anything

Canning

Tourists, hunters and fishermen (many of them members of survival societies) soon adapted the small rocket stove into a camp stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by using horizontal fuel supply, see the diagram on the right. True, at the cost of some inconvenience: the sticks need to be pushed inward as they burn out. But the furnace mode began to hold fast. How? Due to the automatic redistribution of air flows through the plenum and over/through the fuel. The power of a can rocket stove lies in the range of 0.5-5 kW depending on the size of the stove and is regulated by approximately three times the amount of fuel loading. The basic proportions are also simple:

• The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
• The height of the combustion chamber is 3-5 times its diameter.
• The cross-section of the blower is 0.5 from its own combustion chamber.
• The thickness of the thermal insulation layer is not less than the diameter of the combustion chamber.

These proportions are very approximate: changing them by half does not prevent the stove from working, and efficiency on a hike is not so important. If the insulation is made of wet sandy loam, as described above, the joints of the parts can simply be coated with clay (left position in the figure below). Then, after 1-2 fires, the stove will acquire strength that allows it to be transported without special precautions. But in general, any of the available non-combustible materials will do the insulation, trace. two pos. A burner of any design must provide free air flow, 3rd position. A rocket stove welded from a steel sheet (right position) with sand insulation is twice as light and economical as a potbelly stove of the same power.

Brick

We won’t talk about large stationary rocket furnaces: all the original thermodynamics are in tatters in them, and they are deprived of one of the main advantages of the original furnace - ease of construction. We'll tell you a little about rocket stoves made from brick, clay or stone fragments, which can be made in 5-20 minutes when you don't have tins at hand.

Here, for example (see video below), is a thermodynamically complete rocket oven made of 16 bricks laid dry. The voice acting is in English, but everything is clear even without words. A similar one can be built from fragments of brick (see figure), cobblestones, or sculpted from clay. A stove made from rich earth is enough for one time. The efficiency of all of them is not so great, the height of the combustion chamber is too small, but it is enough for pilaf or to quickly warm up.

Video: rocket stove made of 16 bricks (eng)

New material

Among the domestic developments, the Shirokov-Khramtsov rocket stove deserves attention (see figure on the right). The authors, not caring about survival in the splash, used a modern material - heat-resistant concrete, adjusting all the thermodynamics to it. The components of reinforced concrete are not cheap; a concrete mixer is needed for mixing. But its thermal conductivity is much lower than that of most other refractories. The new rocket stove began to work more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. The result was a rocket stove - a fireplace.

Do rockets fly in a bathhouse?

Wouldn't a rocket stove be suitable for a sauna? It seems like you can build a heater on the drum cover. Or a flow one instead of a bed.

Unfortunately, the rocket stove is not suitable for a sauna. To get light steam, you must immediately warm up the walls with thermal (IR) radiation, and immediately, or a little later, the air, by convection. To do this, the oven must be a compact source of infrared and a convection center. Convection from a rocket furnace is distributed, and it provides little IR at all; the very principle of its design excludes significant losses due to radiation.

In conclusion: to the rocket makers

IN successful designs For rocket stoves, there is still more intuition than precise calculation. Therefore, good luck to you too! – the rocket stove is a fertile field for craftsmen with a creative streak.

Among heating devices, the rocket stove deserves special attention. It has an original structure, which involves the use of available materials and components. Almost anyone can organize one. It is enough to understand how drawings are read, and also be able to use the basic construction tools and materials.

Option for making a rocket stove with your own hands

Despite the simplicity of the design, the rocket stove involves the use of two operating principles at once:

• free flow of wood gases through channels;
• pyrolysis is the afterburning of gases that are released during combustion.

The simplest rocket stove uses only the first principle of operation, since there are not enough conditions for pyrolysis.

A neat, homemade rocket stove

Let's look at the options first jet furnaces used for cooking. In such a device, a short pipe located horizontally is used as a firebox, and then it is directed upward. This is the simplest design.

Fuel is placed into the rocket stove directly into the pipe, after which it is ignited. As a result, a flow of hot gases is formed, which is oriented to go out, which means it tends to the vertical section.

At the end of the pipe there is a container used for water or food. There is a gap between it and the pipe so that combustion products can escape.

Many people are interested in why such a stove is called a rocket. The design has a nozzle turned upward, from which, when the device is operating, a flame bursts out. Hence the name.

Flames escaping from a rocket stove

Of course, such a unit will not be able to warm up the room. The rocket furnace must be supplemented with a heat exchanger, as well as channels for removing combustion products. To ensure high temperatures, the vertical part of the pipe is insulated with fire-resistant material.

The nozzle can be covered with a cap. This is necessary for high-quality heat selection. A channel is created at the bottom of the horizontal section of the pipe to supply secondary air.

The modern version involves a slightly different design. Such a reactive furnace involves the afterburning of pyrolysis gases, which is possible due to the supply of secondary air. In addition, combustion products collect under the top of the hood, which increases the pressure to excess. Over time, heat is transferred outward through the walls of the pipe, forcing the gases to cool and flow downward. Hot air awaits them there, so they have to go into the space between the walls of the hood and the pipe, going into the chimney channel.

Application of a rocket stove with a hood on the site

Due to pyrolysis processes, efficiency increases significantly. And thanks to the flow of gases, a self-regulating system is organized.

Productive heat removal

The gases that are sent to have a high temperature. Therefore, it is clear that you should not get rid of them so easily. Otherwise, the effect of the device will be minimal. Therefore, several solutions have been invented for a do-it-yourself rocket stove:

• a water circuit is installed on the rocket stove;
• gases are passed through channels equipped under the stove bench.

A water-heated rocket stove is made without a hood; the energy of combustion products is used in a metal heat exchanger. You should not use a coil with water, it is better to make a water jacket.

You can also make chimney channels lined with brick. They can be placed on the floor, and a bed can be equipped on top. And in this case, the length of the channels must be accurately calculated, otherwise natural traction will have to be organized.

Design of a brick rocket stove with a stove bench

Advantages

Create a rocket stove with your own hands and get the following benefits:

• You can add fuel during the process;
• Efficiency is not a constant value, but with proper selection of thermal energy from gases, it can be very high;
• natural draft of the chimney is not a prerequisite;
• accessibility of installation - to organize a rocket stove with your own hands, a little experience in the stove business is enough, minimum costs for materials.

Using a rocket stove outdoors

Such advantages make the rocket stove a popular device.

Flaws

Note: And although the rocket stove is characterized by simplicity and attractiveness, it also has disadvantages. For example, there are certain requirements for fuel quality. The firewood should not be wet, otherwise the pyrolysis effect will not be achieved. In addition, the structure requires constant supervision.

A do-it-yourself rocket stove is not very suitable for a bathhouse, since it gives off little of the heat needed for a steam room. Small area the surface of the stove prevents effective heating of the bath.

Species

There are several types of rocket stoves:

1. Brick boilers. They differ from furnaces - they are equipped with a built-in heat exchanger, from which the coolant is supplied to heating system: tank, pipes, radiators.
2. Heating. They demonstrate the efficiency of heating rooms using the convection principle of operation.
3. Designs with a hob, they are called heating and cooking.
4. Fireplaces. Most often they are used for heating one room in which they are located.
5. For the bath. They have original design. The main task of the device is to increase the temperature of the stones, thereby heating the air in the steam room. An important indicator of decisions is intensity.

A simple DIY rocket stove design

Of course, these are not all the species that exist.

From a cylinder

This is a fairly popular option, which is successfully implemented by the hands of many craftsmen. Most often, a 50 liter gas cylinder is used for production. It will serve as a cap. To create a loading hopper and firebox, you can use a pipe with a diameter of 15 cm. A pipe with a diameter of 10 cm is used for the chimney, and 7 cm for the internal channel.

Using a rocket stove from a gas cylinder on the site

It is necessary to cut the products to the required length, and cut off the upper part of the cylinder. Next, using the drawing, you should weld the parts together with your own hands. Fill the gap between the pipes 7 and 15 cm thermal insulation material. You can use sand, but it is recommended to calcinate it to kill the organic environment. Otherwise, the heating process will be accompanied by an unpleasant odor.

When assembled, a rocket stove made from a gas cylinder weighs little, so it does not require a special base. The legs need to be welded to the device.

Made of brick

You can make a rocket stove out of brick with your own hands. In this case, you will have to work hard to get a high-quality design. The fire channels of the device are made using. You can use a barrel as a cap.

What a rocket oven made of brick might look like

To position the structure, it is recommended to dig a small hole, since it should be below floor level. The bottom needs to be compacted, after which it is poured concrete base 10 cm thick. When it hardens, you can start laying. For this purpose, a solution is used, which includes refractory clay. When the structure is built, the solution has hardened, and the dug hole can be filled in. A barrel is placed on the channel, the bottom of which is cut out with your own hands. The space between the brick and it is filled with insulation.

The end of the device is coated with a solution, a barrel is put on top large size, to the bottom of which the chimney is welded.

Let's sum it up

Note: A rocket stove is an original solution that you can build with your own hands. Just choose suitable option design, take into account recommendations and requirements. You must first make a drawing. If you can’t draw a diagram with your own hands, you can use ready-made options presented by experts.

In this matter, the main thing is not to rush, then the result will definitely comply with accepted standards and will become an effective tool for heating.

A detailed description of the manufacture of a rocket furnace from steel elements.

Features of the design and use of a simple rocket stove, which you can take with you on fishing or outdoor recreation.

Branded rocket stove. Description by a specialist.