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Drawings of a jet stove from a gas cylinder. What is a Rocket Furnace?

Let's say right away: a rocket stove is a simple and convenient wood-fueled heating and cooking device with good, but not exceptional parameters. Its popularity is explained not only by the catchy name, but more so by the fact that it can be made with your own hands and not by a stove-maker or even a bricklayer; if necessary - literally in 15-20 minutes.

And also by the fact that, with a little more work, you can get an excellent couch in the house without resorting to the construction of a complex, expensive and cumbersome Russian or bell-type stove. Moreover, the very principle of the device of the furnace-rocket gives great freedom to design and the manifestation of creative abilities.

Rocket stove - wood-fired device

But perhaps more remarkable is the "jet furnace" by the huge number of associated, at times completely absurd inventions. 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 sit down near the ramjet engine (ramjet), as they say, and did not sit down in the bushes. On the 25th and 31st there are bypass turbojet engines (turbojet engines), four of which then pulled the Tu-144 and still pull other cars. And any furnace with any jet engine (RD) is technical antipodes, see below.
"Reverse jet furnace". Is this a tail-first stove, or what?
“But how will she blow such a pipe?” A naturally aspirated stove does not blow into the chimney. On the contrary, the chimney pulls out of it, on natural draft. The higher the pipe, the better it pulls.
“The rocket stove is a combination of a Dutch bell-type 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 but a Dutch one. Secondly, the couch of the Russian stove warms up in a completely different way than the rocket stove.

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

These and similar inconsistencies, of course, are confusing and prevent us from making a rocket furnace properly. So let's figure out what is true 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 internal combustion engine, only the outflowing 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 large pressure that pushes the piston, and it already moves the entire mechanics. The movement of the piston is active, the working fluid pushes it to where it tends to expand itself.

When fuel is burned in the RD combustion chamber, 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 exit to the nozzle is open to the hot gases, they rush there. In RD, pressure plays a subordinate role and nowhere exceeds a few tens of atmospheres, this, for any conceivable nozzle cross section, is not enough to disperse a flashlight to 2.5M or put a satellite into orbit. According to the law of conservation of momentum (momentum), the aircraft with RD at the same time receives a push in the opposite direction (recoil momentum), this is jet thrust, i.e. thrust from recoil, reactions. In a turbofan engine, the second circuit creates an invisible air shell around the jet. As a result, the recoil momentum is, as it were, contracted in the direction of the thrust vector, so the turbofan is much more economical than a simple turbofan.

In the furnace, there is no conversion of types of energy into each other, therefore it is not an engine. The stove simply distributes potential thermal energy properly in space and time. From the point of view of the furnace, the ideal RD has an efficiency of 0%, because it just runs on fuel. From the point of view of a jet engine, the furnace has an efficiency = 0%, it only dissipates heat and does not pull at all. On the contrary, if the pressure in the chimney rises to or above atmospheric (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. Draft in the chimney without pressurization, i.e. without the expenditure of energy from the side, it is provided due to the temperature difference along its height. Potential energy here, again, is not converted into any other.

Note: in a rocket propellant rocket engine, fuel and oxidizer are fed into the combustion chamber from tanks, or they are immediately filled into it if the rocket engine is on solid fuel. In a turbojet engine (TRD), the oxidizing agent - atmospheric air - is injected into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes a certain fraction of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the power of the jet, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), air is supplied to the combustion chamber by hypersonic velocity pressure. A lot of experiments were carried out in the ramjet, but there were no production aircraft with it, there is not and is not expected, the ramjet is painfully capricious and unreliable.

Can or not can?

Among the myths about the rocket stove, there are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the "racquet" with the Chinese kan.

As a child, the author had a chance to visit the Amur region, in the region of Blagoveshchensk, in winter. There were a lot of Chinese there in the villages even then, who were scrambled in all directions from the cultural revolution of the Great Chairman Mao and his completely frostbitten hungweibins.

Winter in those parts is not Moscow, frost at -40 is a common thing. And what struck and aroused interest in stoves in general was how Chinese fanzes were heated by kanami. In Russian villages, firewood is transported by carts, smoke is a pillar from the chimneys. And all the same, in the log hut, not in a children's girth, by morning the corners were frosted over from the inside. And the fanza is built like a country house (see the figure), the windows are covered with a fish bladder or even rice paper, bunches of chips or twigs are placed in the kan, but the room is always warm.

However, there are no subtle heat engineering tricks in the canal. This is an ordinary, only small, stove with a lower exit to the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is arranged. The chimney, for the sake of fire safety, is outside the building.

The effectiveness of the kan 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 3 walls for sure. Which once again confirms: the design and parameters of the furnace must be linked to those of the heated room.

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

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

It is not in the Russian custom to stick twigs into the oven every now and then, and our peasants abhorred cooking on animal feces. But travelers of the past highly valued argal as a fuel, collected it along the way and carried a supply with them, diligently protecting it from getting wet. N. M. Przhevalsky, in one of his letters, argued that without the argal, he could not have carried out his expeditions in Central Asia without loss. And for the British, who were disdainful of the argal, 1/3-1/4 of the personnel of the detachments returned to the base. True, he was recruited from sepoys, Indian soldiers in the English service, and pandits - spies recruited from the local population. One way or another, but the highlight of the rocket stove is not at all in the couch on the hog. To get to it, you will have to learn to think in an American way: 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?

In our view of things, the original technical documentation of rocket furnaces should be studied with caution, but not at all because of inches-millimeters, liters-gallons and the subtleties 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 car. And in the original article from Petroleum Engineer, it meant "Bare wire runs under the crane trolley."

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

Note: How much the average inhabitant of the greatest empire in history is afraid of everything can only be understood by talking with them long enough. And sociopsychologists go out of their way there, convincing that living, languishing 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 will not survive. What is an oven for? For the time being, for the time being, the survivors were content with 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 Hollywood's "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. It will be necessary to be content with the newly appeared plukans "ka-tse" in small quantities, bad, expensive and difficult to access. Yes, all of a sudden someone hasn’t watched “Kin-dza-dza” - like a match in Plukansky, a measure of wealth, prestige and power. It was necessary to invent your own furnace, none of the existing ones is designed for a post-nuclear spit.

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

If an American has already understood the essence of an idea, then he brings the product to its possible perfection - what if there is a buyer, you can’t sell raw iron. But the technical documentation, which looks beautiful and neat, can be drawn up in fact extremely carelessly, or even deliberately distorted. And what is it, this is my know-how. Maybe I'll sell it to someone. Whether there will be a plus, or not, but for now the know-how is worth the money. In America, such an attitude to business is considered quite honest and worthy, but there a clinical alcoholic at work will never miss a stopper and will not drag a couple of bolts home to the household. On that, in general, the whole of America stands.

And the Russian breadth of the soul is also a double-edged sword. Most often, our master simply understands from a sketch how this thing works, but in the details it turns out to be careless and overly trusting in the source code: how is it for a crafty brother to deceive his own. If you don't have something, then you don't need it. It seems clear how everything is spinning there - already my hands itch. And there, perhaps, until it comes to a hammer, chisel and related literature, still count and count. Moreover, important points can be omitted, veiled or deliberately wrong.

Note: an American acquaintance once asked the author of this article - how did we, the really stupid ones, elect the very smart Reagan as president? And you, 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 settle in the Oval Office, and his first lady would dig a 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 misunderstanding

There is such a thing in technology - the square-cube law. Simply put, when something changes in size, its surface area changes squarely, and its volume changes cubed. Most often, this means that changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. With regard to solid fuel stoves, the square-cube law is doubly valid, because fuel is also subject to 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 design of the furnace has a certain allowable fork of its size and power, within which the specified parameters are provided.

Why, for example, is it impossible to make a potbelly stove the size of a refrigerator and with a power of about 50-60 kilowatts that way? Because the potbelly stove, in order for it to somehow warm, 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, firewood or coal needs as much as it does not fit in it. There will also be no sense from a mini-potbelly stove: the heat will leave through the outer surface of the furnace, which has grown relative to its volume, and the fuel will not give it away more than it can.

The square-cube law acts triple on the rocket furnace, because she is "licked" in an American professional way. With our kondachka, it is better to stay away from her. Here, for example, here in Fig. American development, which, judging by its demand, many of our craftsmen take as a prototype.

The original blueprint for the mobile rocket oven

With the fact that the exact grade of refractory clay (fire clay) is not indicated here, ours will sort it out. 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 a 20-gallon keg with a diameter of 17 inches (431 mm with change) went to her drum?

Judging by the structures from 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 guess to arrange a blower, but the bunker is left open. Are the exact proportions of vermiculite with perlite for lining the riser and forming the furnace body (core) not indicated? We make the lining homogeneous, although it will be clear from what follows that it should consist of insulating and accumulating parts. As a result, the furnace roars, the fuel eats only dry, and a lot, and even before the end of the season, it overgrows with burning inside.

How was the rocket oven born?

So, already without fiction with futurology, the survivors needed a stove to heat the house, operating with high efficiency on low-quality random wood fuel: wet wood chips, twigs, bark. Which, moreover, will need to be reloaded without stopping the furnace. And most likely it will not be possible to dry in a firewood shed. Heat dissipation after heating needs at least 6 hours to get enough sleep; getting pissed off in a dream on Pluka 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 are required for the manufacture of production equipment, and the furnace itself must be available for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics and other energy dependencies.

They immediately took a couch from the kan, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning furnaces work even on sawdust, but only dry, and do not allow shutdown with additional loading. Nevertheless, they were taken as a basis, they were very attracted by the high efficiency achieved by simple methods. But in an attempt to make the "long stoves" work on bad fuel, another circumstance became clear.

What is wood gas?

The high efficiency of long-burning furnaces 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 fuel, continues for 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, woodgas.

Note: in Runet, woodgas has created more confusion, because in American vernacular, gas can mean any fuel, cf. e.g. gas station - gas station, gas station. When translating primary sources without knowing the American technical, it turned out that woodgas is just wood fuel.

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

It turned out not so when firing with bundles of twigs: here the primary pyrolysis gases were immediately dragged into the chimney. Wood gas could have formed in it at some distance from the furnace, but the primary mixture had cooled by that time, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney like soot. Which quickly tightened the channel completely; amateurs building rocket furnaces at random are well familiar with this phenomenon. But the survivors eventually figured out what was going on and made the right oven anyway.

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 read, smart guy, school textbooks. That is, go to the 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 principle of operation of their furnace, which has no analogues in others: slow adiabatic afterburning of pyrolysis gases in a weak flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume, subject to the square-cube law, and the energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but practically into free volume. And now - learn to think in an American way.

How does a rocket oven work?

The scheme of the final fruit of the labors of the survivors is presented 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 blower (Air Intake). The blower must provide an excess of air so that it is enough for afterburning. But not excessive, so that the cold air does not cool the primary mixture. With vertical loading of fuel and a blind cover of the bunker, the flame itself acts as a regulator, however, not very effective: when it flares up too much, it pushes the air out.

The device of rocket furnaces

Further things already non-trivial begin. We need to warm up, and with good efficiency, a large oven. The law of the square-cube does not allow: the meager heat will immediately dissipate so much that the 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 through the trumpet. This law is harmful, you can't break it in the forehead. Okay, let's see in the basics, if there is anything there that is not subject to him.

But how, there is. That same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares are resting, and the cubes can be reduced even to a thimble, even to a skyscraper.

Imagine a completely isolated volume of gas. Let's say it releases energy. Then the temperature and pressure will begin to rise until the energy release stops, and will freeze at a new level. Great, we burned the fuel completely, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do it without technical difficulties? And most importantly - how, without violating the adiabat, to supply air for afterburning?

And we will make the adiabatic process non-equilibrium. 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 for ourselves a flame or a burning tunnel (Burn Tunnel), but we will not sign it (know-how! You can’t catch up - give money for consulting drawings! Without theory, of course. Who sells the fixed capital at retail.) On the diagram, so that not accused of "opacity", denoted by the flame.

Along the length of the flame tube, the adiabatic index changes (this is a non-equilibrium process): the temperature will first drop slightly (wood gas is formed), then it will increase sharply, the gas will burn out. It is possible to release it into the accumulator, but we forgot - what will pull gases through the flame tube? Supercharging means energy dependence, and there will be no exact adiabat, but something mixed with an isobar, i.e. the efficiency drops.

Then we will lengthen the pipe by half, keeping the insulation so that the heat does not go in vain. We bend the “idle” half up, making the insulation weaker on it; how to keep the heat seeping through it, we will think a little later. In a vertical pipe, a temperature difference will appear along the height, which means thrust. And good: the thrust force depends on the temperature difference, and with an average 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 potbelly stove, now we need to think about how to use it warmly.

Yes, it does not interfere with additional encryption. If we call the vertical part of the flame tube the primary or internal chimney (Primary or Internal Vent), then they will guess the main idea, we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipes with upward current - the riser (riser). Purely American: correct and incomprehensible.

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

It is not difficult to convert high-potential heat into medium-potential heat without loss: you need to give the gas the opportunity to expand in an isolated volume. But, if the expansion is left adiabatic, then the volume will need to be too large. And that means - material and labor intensive.

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

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

Note: the riser and the drum that covers it look like a furnace hood over an elongated hail. But the thermodynamics here, as we see, is quite different. It is useless to try to improve the bell-type stove by building on a high loft - only the 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 couch. For this, the Chinese have to break the kan from time to time and remake it, but we are not in the 1st century. BC. we live when kan was invented. We will arrange a secondary ash pan (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of flue gases in it, everything in them that did not burn out immediately condenses and settles. The cleanliness of the external chimney is guaranteed by this for years.

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to fool around with the latches. We will simply make a cover from a metal sheet on screws with a mineral cardboard gasket.

small rocket

The next task of the designers was to create on the same principle a small continuous combustion oven for cooking in the warm season. In 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 was supposed to be portable, but it was permissible to make it with an open firebox, because. when warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law, forcing it to work for themselves: they combined the fuel tank with the blower, see Fig. at the beginning of the section on the right. It is impossible to do this in a large furnace, fine 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 heat release area, and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the cover of the hopper (Cover Lid). The 45-degree hopper optimizes the oven's auto-adjustment for standard cooking routines, but it's harder to make.

Secondary air for afterburning wood gas in a small oven enters through additional holes in the mouth of the riser or simply flows under the burner if there is a cooking vessel on it. If a small furnace is close to the limit size (about 450 mm in diameter), then an optional secondary woodgas frame may be needed for complete afterburning.

Note: It is not possible to supply secondary air to the mouth of the riser of a large furnace through the holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas-smoke path is lower than atmospheric pressure, as it should be in the furnace, flue gases will be emitted into the room due to strong turbulence. Here their kinetic energy, harmful to the furnace, affects; this, perhaps, is the only thing that makes a rocket stove related to a jet engine.

The small rocket stove has revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (a Bond stove in the West) will help to cook a stew or wait out a snowstorm in a one-two-man tent, but it will not save a group caught on a spring campaign by a belated bad weather. A small rocket furnace is only a little larger, it can be quickly made from nowhere, but is capable of developing power up to 7-8 kW. However, we will talk about furnace-rockets from anything we will talk further.

Also, the small rocket oven has spawned many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for the device of a compact and rather powerful water heater, see the video below. The large rocket furnace was also modified, we will talk about this a little at the end, but for now let's dwell on more significant things.

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

How to fire a rocket?

A rocket furnace with long-burning furnaces has a common property: they need to be launched only on a warm pipe. For a small one, this is not essential, but a large one on a cold chimney will only burn fuel in vain. Therefore, a large rocket furnace, before loading regular fuel into the bunker after a long break in the furnace and kindling, must be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open blower. The end of acceleration is judged by a change in the tone of the hum of the furnace or its subsidence. Then you can load fuel into the bunker, and its ignition will occur by itself from the accelerating fuel.

The rocket furnace, unfortunately, does not apply to furnaces that are completely self-adjusting to the quality of the fuel and external conditions. At the beginning of regular fuel combustion, the blower door or the bunker cover in the small furnace is fully opened. When the stove hums strongly, cover it "to a whisper." Further, in the process of burning, 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 - it's okay, if you open it, the stove will flare up again.

Why such difficulties? In the process of burning the fuel, the flow of air into the combustion zone increases. When there is too much air, the stove roars, but don't be happy: now the excess air cools the primary gas mixture, and the sound is amplified as the steady swirl in the riser clumps into a disorderly lump. The pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and soot deposits from the soot cemented by bituminous particles in the riser. This, firstly, is a fire hazard, but most likely it will not come to a fire, the riser channel will quickly overgrow with soot completely. And 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 bunker, and in a small furnace, gradually, as the fuel mass settles. Since an experienced housewife does not leave her for a long time when cooking on the stove, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

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

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

Materials, dimensions and proportions, lining

Now let's see what a home-made rocket stove should be from the materials available to us. Here, too, we need to look back: not everything that is at hand in America is also with us, and vice versa.

Of what?

For a large stove with a 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-plus liters, and 24 inches is almost exactly 607mm, so our 200-litre is fine without additional conversion. Keeping the parameters of the furnace, the diameter of the drum can be halved, up to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

Pipes of different sizes will go to the blower, bunker, firebox and riser, see below, round or shaped. So it will be possible to make an insulating lining of the furnace part from a mixture of equal parts of furnace clay and fireclay crushed stone, without resorting to brickwork; we will talk about the riser lining in more detail below. Combustion in the 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 thin-walled metal corrugated, here the flue gases have already completely exhausted both in terms of chemistry and temperature.

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

Note: it is desirable to equip the rocket stove with a view in the external chimney. Although the gas view in the high riser seals the common smoke path tightly, strong winds outside can prematurely draw heat out of the couch.

Dimensions and proportions

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

Drum height H - 1.5-2D.
Drum coating height - 2/3H; for the sake of design, the edge of the coating of the design can be made oblique curvilinear, then 2/3H must be maintained on average.
The thickness of the coating of the drum is 1/3D.
The cross-sectional area of the riser is 4.5-6.5% of S; it is better to stay within 5-6% of S.
The height of the riser - 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.
The length of the flame tube is equal to the height of the riser.
The cross-sectional area of the flame tube (fire pipe) is equal to that of the riser. It is better to make a fire pipe from a square corrugated pipe, so the furnace mode will be more stable.
The cross-sectional area of the blower is 0.5 from 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.
The volume of the secondary ash pan is from 5% of the initial volume of the drum (excluding the volume of the riser) for a furnace from a barrel to 10% of it for a furnace from a cylinder. Interpolation for intermediate drum sizes is linear.
The cross-sectional area of the external chimney is 1.5-2S.
The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is considered from its lower point. If the bench is on wooden floors, the pillow under the chimney can be halved.
The height of the bed coating above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. It can be less, but then the heat transfer after heating will be shorter.
The height of the external chimney is from 4 m.
Permissible length of the flue in the couch - see next. sec.

The maximum thermal power of a barrel rocket furnace is approximately 25 kW, and a gas cylinder furnace is about 15 kW. Power adjustment - 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 ovens, the riser cross-section was taken as 10-15% S, based on very wet fuel. Then, in the same place, in America, rocket stoves with a stove bench for a bungalow appeared, designed for air-dry fuel and more economical. In them, the riser section is reduced to the recommended ones and here 5-6% S.

Riser lining

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

Of our available materials for heat engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-digged river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous, in the oven they are quickly saturated with soot. Then the stove will roar with any air supply, with all the consequences. Therefore, we need to surround the riser lining with a metal shell, and be sure to cover the end of the lining with furnace clay.

Lining schemes for 3 types of furnaces are shown in fig. The bottom line here is that with a decrease in the size of the drum, the proportion of its direct heat transfer through the bottom and the unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining capacity can be reduced. This makes it possible to correspondingly increase the relative cross section of the annular descent of the flue gases in the drum.

Riser lining schemes in rocket furnaces

What for? Firstly, the requirements for an external chimney are reduced, since the outer traction pulls better now. And since it pulls better, then the permissible length of the hog in the stove bench falls more slowly than the dimensions of the furnace. As a result, if a stove from a barrel warms up a bench with a pine forest up to 6 m long, then half the size from a cylinder is 4 m.

How to line with sand?

If the riser lining is fireclay, then the remaining cavities are simply covered with construction sand. River self-digging for lining entirely of sand does not need to be carefully prepared, it is enough to 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 whole backfill is dried for a week, the upper edge is covered with clay, as already mentioned, and the construction of the furnace is continued.

balloon rocket

From the foregoing, it is clear that it is more profitable to make a rocket stove from a gas cylinder: less work, fewer unsightly parts in plain sight, and the bench warms up almost the same. A thermal curtain or underfloor heating in 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, it is rarely necessary to launch a large barrel at full power with maximum efficiency.

Craftsmen, apparently, also understood this; at least some. For example, here in Fig. - drawings of a balloon furnace-rocket. On the right is the original; the author, it seems, was wisely versed in the initial developments and, in general, everything turned out right for him. On the left - the necessary improvements, taking into account the use of air-dry fuel and warming up the couch.

Drawings of a rocket stove from a gas cylinder

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the flame tube can be made shorter. The cross-sectional area of its air duct is about 10% of the riser cross-section. The furnace always works with the secondary fully open. First, the mode is set with a primary valve; finely adjust the hopper cover. At the end of the furnace, the furnace will roar, but here it is not so scary; the author of the design provides for a removable drum cover to clean the riser. She, of course, should be with a seal.

Rockets from anything

Canned

Scheme of a rocket furnace from cans

Tourists, hunters, and fishermen (many of them members of survival societies) soon converted the small rocket stove into a camping stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by applying a 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 iron. How? Due to the automatic redistribution of air flows through the blower and over / through the fuel. The power of a jar rocket furnace is in the range of 0.5-5 kW, depending on the size of the furnace, 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 of its diameters.
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 the efficiency in the campaign is not so important. If the insulation is made of wetted sandy loam, as described above, the joints of the parts can simply be smeared with clay (left pos. in the figure below). Then the stove, after 1-2 fires, will acquire strength, allowing it to be transported without any special precautions. But in general, any of the improvised non-combustible materials will do the insulation, next. two pos. A burner of any design must provide a free flow of air, 3rd pos. A rocket stove welded from a steel sheet (right pos.) with sand insulation is twice as light and more economical than a potbelly stove of the same power.

Compact Rocket Furnaces

brick

Brick rocket stove

We will not expand on large stationary rocket furnaces: in them all the initial thermodynamics goes to pieces, and they are deprived of one of the main advantages of the original furnace - ease of construction. We will talk a little about rocket stoves made of bricks, clay or stone fragments, which can be made in 5-20 minutes when there are no tins at hand.

Here, for example (see the video below), is a completely thermodynamically complete rocket stove of 16 bricks laid dry. The voice acting is English, but everything is clear without words. A similar one can be folded from fragments of bricks (see Fig.), Cobblestones, fashioned from clay. For 1 time, a stove made of greasy earth is enough. The profitability of all of them is not so hot, the height of the combustion chamber is small, but it’s enough for pilaf or urgently to warm up.

Video: 16 brick rocket oven (eng)

new material

Scheme of the Shirokov-Khramtsov furnace

Of domestic developments, the Shirokov-Khramtsov rocket furnace deserves attention (see the figure on the right). The authors, not caring about survival in a plus, used a modern material - heat-resistant concrete, adjusting all thermodynamics to it. The components of refractory 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 furnace became more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. It turned out a rocket stove - a fireplace.

Do rockets fly in the bath?

Isn't a rocket stove suitable for a bath? It seems to be possible to arrange a heater on the drum cover. Or flowing instead of a couch.

Unfortunately, the rocket oven is not suitable for a bath. To get light steam, the sauna stove 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 IR source and a convection center. The convection from the rocket furnace is distributed, and it gives little IR at all, the very principle of its design eliminates significant radiation losses.

In conclusion: rocket stove-makers

In successful designs of rocket furnaces, there is still more intuition than precise calculation. And therefore - good luck to you too! - a rocket oven is a fertile field for craftsmen with a creative streak.published

P.S. And remember, just by changing your consciousness - together we change the world! © econet

Rocket furnace according to its design is divided into two main types: portable and stationary. A portable model is used in hiking, relaxing in nature. Its industrial model called "Robinson" is widespread. It bears its name because it looks like a rocket. The similarity of the image is added by the fact that a flame bursts out of a short chimney during combustion, with an unlimited supply of air, a rumble is emitted. It is used for cooking, heating the kettle in field conditions.

Consider the principle of operation, based on the above model.

Description of work

For the construction, steel with a thickness of 2-3 mm is used.
It has the shape of a matchbox, without a box. A lid and a bottom are welded to its side. On the other side there will be a firebox into which firewood is directly loaded.
At the top, closer to the bottom, a pipe is welded to the box at an angle of 45 degrees. A structure is welded on top to act as a stand for dishes and a flame divider.
So that the flame does not burn through the bottom of the dishes during cooking. For manufacturing, you will need a piece of pipe, which is cut into three rings, each ring is cut in half, for a total of six half rings, we weld them with a uniform indent in the center, the product is welded to the top of the chimney.
Legs are welded to the bottom of the box, ensuring the stability of the structure.

The finished sample with dimensions is shown below in the illustration and diagram.

Principle of operation

The considered option is good in that it is not required to build a structure over a fire for hanging a cauldron or a teapot.
Cooking kulesh or fish soup will be more comfortable, like on a stove at home. The installation should be oriented towards the wind, it should blow into the furnace.
Firewood burns out quickly, the heat generated is enough for cooking, but most of it disappears.
In the stationary model, these shortcomings are eliminated by improving the basic design. Namely, the furnace is equipped with a door, a blower is arranged under it, which limits the air supply, thereby slowing down the process of burning firewood.
Air is also supplied to the area above the combustion, where the gases go, but do not burn there, this makes it possible to start the pyrolysis process, thereby ensuring the burning of the pyrolysis gases.
Also, the fuel combustion chamber should be wrapped in a casing, which increases thermal insulation. A manufactured thermal insulator is put on it, this additionally retains heat inside, shown below.

materials

The Rocket Furnace will require the following consumables to be crafted: two gas bottles and everything listed in the table below.

Getting Started

We cut off a piece of 20 cm from the profile, cut the rest into three parts.

From a piece, 315 mm in size, a “bed” base is made, from the second, 300 mm in size - a place for loading firewood and weld it at an angle. To do this, we do a saw cut on an oblique.

We cut the third blank, 280 mm in size, across, we get two channels, the one with a width of 35 mm is welded from the bottom, thereby making a blower.

On the upper surface of the base, we cut out a rectangular hole for the entire width, long for a bunker with a blower, on it, from the side of the joint, we make a cutout for it. The distance from the beginning to the workpiece is 100 mm.

Safety measures should be observed when cutting, first it must be filled with water, this will etch the remaining gas condensate.

Blower manufacturing process

From the bottom of the base, opposite the hole, we weld five rods, 16 cm long, from reinforcement. We make slots between the welded grates. Next, we weld another part of the channel (the remainder from the third workpiece) below the grate. We weld on the back wall, on which, for the convenience of further installation, the bevel, its plug. After the “working” blank has been welded to the base, the bottom should be welded with a plug.

Next, we proceed to the manufacture of the casing, which will act as a conductor. The space between them will be filled with mineral filler perlite. At the bottom of it, we make a cutout for the “sunbed”, the width is 120, and the height of the cutout will be 160 mm, i.e. from below we weld a strip using a cut piece 40 mm long.

This insulates the bottom at the junction with perlite. We hide it in the casing, weld a round cover on its bottom.

Desired volume of perlite

For the upcoming purchase, you should find out experimentally, for this you should fill this space with water. It turns out the desired volume. Perlite is sold in garden stores, its measure is liters. A channel is welded to the bunker, traction will be provided through it and the loading bunker will be mounted on the base. Inside the "working" we organize the air supply. To do this, we crash there through the casing and weld the workpiece to the place of the slot, in the form of a ring. With a piece of profile pipe we make a branch for the air duct. It has a door for adjustment.

Doors are made and attached to the furnace with a blower and to the loading chamber with a draft chamber. The doors on the boot should be used regularly, but on the firebox - only when igniting or when choosing ash, so it’s better to construct them as shown below, it will be more practical.

Perlite is filled in and the hole is welded from above with an annular plug. In this case, 5 and a half liters of insulation were used.

Measurements are made and a hole is cut out in order to put on the lower section of the insulation. Since an air leak was attached to the side of the stove, the cutout does not come out in the correct rectangular shape.

We also manufacture two balloon rings.

Rings are worn at the junction between, one outside, the other inside.

Between them, a packing is laid, which is a non-combustible sealing cord, 150 mm long and 10 mm thick. These manipulations will allow you to securely fix the upper section of the cap, putting it in the grooves of the so-called “saddle”, while it remains removable in order to ensure the possibility of cleaning from waste in the future.

rocket stove video

For ease of installation of the lower part of the oven can be turned over. We center it by welding spacers between the cap and the casing. After that, we weld the insert over the "bed" to the place of the cutout. We weld rings, the width of which is 30 mm with a release to the top of 20 mm, one inside the lower cap, the other from the outside.

We calculate the distance between the top of the "working" pipe and the upper surface of the cap. The cross-sectional area must be less than the lateral area of the imaginary cylinder. In this case, its diameter is 120 mm. The cross-sectional area is 11304 mm². The experimentally calculated figure of the desired distance is 50 mm.

Summary: the top will heat up, and the heat will diverge over the entire surface area - this will be a stove with excellent efficiency, since the heat will remain in the device and not fly out into the chimney.

The cap is fastened as follows: corners with 10 holes are welded along the contour from below and from above and twisted with bolts 8x8 cm long in four places.

The last stage is the output of the chimney at the bottom. To do this, cut a hole under it.

The stationary rocket furnace in this article was considered using the example of video material, which can be viewed by clicking on the links below.

A practical heating device that is not inferior in its functionality to a traditional potbelly stove is a rocket stove. Its demand lies in high efficiency, economy, availability of design and ease of manufacture. Even novice craftsmen can assemble such a unit at home.

What is a Rocket Oven?

The jet furnace got its original name due to the special design of the body - the traditional form of the device is made from cuts of metal pipes interconnected by a weld. Outwardly, it resembles a rocket launcher. A simplified model of the furnace can be assembled in a few hours.

The heater becomes reactive as a result of the peculiarities of the combustion process of the fuel material, when at a certain moment of operation, with a high supply of air mass to the fuel chamber, the furnace begins to create a powerful hum and vibration.

Important! The buzz mode of the rocket furnace is characterized by irrational fuel consumption in the process of its combustion. The economical heating mode ensures quiet operation of the heating unit.

Principle of operation

Despite the fact that the rocket oven is quite simply arranged, its principle of operation is based on the following processes:

Natural circulation of heated gases and air inside the channels. This means that the device does not require additional blowing, and the internal draft is created by a flue system. The higher the chimney, the stronger the draft.
Afterburning of waste gases (pyrolysis process) is carried out with a slight supply of oxygen to the fuel chamber. It provides a rapid increase in the efficiency of the device and the efficient consumption of fuel material in the combustion process.

The process of heating the furnace itself is carried out as follows:

Firewood is placed in the fuel compartment, and ignition is performed.
Next, the standard operating mode of the furnace is set, in which the complete heating of the vertical part of the structure - the chimney pipe - is carried out.
Sufficient heating of the furnace body provides ignition of volatile substances in the chimney and rarefaction of air in its upper part.
Natural draft increases, which leads to air flow into the fuel compartment and an increase in the efficiency of the combustion process.
To maintain complete combustion of the fuel material, the furnace design must be equipped with a special zone for afterburning pyrolysis gases.

A simple version of a rocket stove made of a profile pipe is intended for cooking and heating food, as well as for heating garden houses, summer cottages and camping baths.

Advantages and disadvantages

The long-burning rocket furnace has gained particular popularity and demand due to its positive characteristics:

Affordable design and easy assembly. The simplest version of the oven can be made at home from available materials in a few hours.
Efficient heat transfer using various types of wood fuels - firewood, wood chips, twigs, bark and shavings.
Wide functionality. Possibility of using the device for space heating, cooking and water heating.
Complete combustion of fuel with the possibility of afterburning pyrolysis gases. This allows you to increase efficiency and at the same time avoid carbon monoxide poisoning.
Possibility of refilling fuel without interrupting the work process.
No need to create forced draft in the chimney system. High level of self-regulation of operating modes of the device.

The ergonomic stove can be installed in any room, and lightweight construction does not require additional arrangement of a reinforced foundation.

Despite the significant advantages, such a unit is not without some disadvantages:

The lack of the possibility of automating the furnace process. Homemade stoves require constant human control over the laying of fuel material.
High probability of getting burns with significant heating of the metal structure.
The device is not intended for heating large residential buildings and stationary bath complexes.
The stove is designed to use well-dried fuel, since excess moisture can lead to back draft in the chimney.
Unaesthetic appearance of the finished device.

Design

The rocket-type stove is represented by a fairly simple design, which is made from pipes of the required diameter.

The fuel chamber is a horizontal pipe section into which fuel is loaded. In some cases, the oven may have a vertical loading option. In this case, the device consists of three structural elements - two vertical pipes of different heights, mounted on a horizontal pipe. The short section of the pipe is the fuel compartment, the long section is the chimney.

To ensure an increase in efficiency, rocket furnaces may have additional structural elements:

Fuel compartment (vertical or horizontal position) - for loading fuel.
Afterburner (horizontal) - for fuel combustion and thermal energy accumulation.
Blower compartment - for afterburning pyrolysis gases, which are formed during the combustion of fuel.
The outer casing of the furnace is for thermal insulation of the structure.
A lounger is a platform for resting in a lying or sitting position.
Chimney pipe - to remove the products of combustion of fuel and create natural draft.
A hob is a horizontal platform for cooking or heating water.

DIY manufacturing

A home-made stove from a spent gas cylinder is an affordable option for a wood-burning stove, which is designed for efficient space heating and economical fuel consumption.

To make an oven at home, you will need:

Empty cylinder body - 2 pcs.
Metal pipe for creating a vertical chimney channel (diameter - 12 cm).
A profile pipe for the manufacture of a firebox and a loading chamber (length 100 cm, cross section - 12 × 12 cm).
Cuts of metal pipes: short by 80 cm (diameter - 15 cm) and long by 150 cm (diameter - 12 cm).
Steel sheet (thickness 3 mm).
Metal rods.
Warming heat-resistant material (perlite).
Welding equipment.
Bulgarian.
Personal protective equipment - goggles and gloves.

To ensure the correct assembly of the furnace, it is recommended to prepare a working drawing indicating the exact dimensions of all structural elements of the device.

Step-by-step instructions for making a rocket furnace:

Three segments are cut from the profile pipe - two of them are 30 cm each and one for a 35 cm lounger. A rectangular hole for the fuel compartment and a semicircle for a vertical pipe are made from the blank for the lounger by a grinder.
One 30 cm blank is cut lengthwise and welded to the fuel chamber to create an air channel.
The fuel compartment is connected to the pipe by hot welding.
A grate is made from fittings, for a fuel chamber and an ash pan - doors.
Next, a secondary chamber for afterburning pyrolysis gases is manufactured.
A hole is made at the bottom of the cylinder for the fuel compartment. On the outside of the cylinder, a knee is fixed under a pipe with a diameter of 12 cm for the chimney.
A hole is cut at the bottom of the pipe to clean the chimney.
A piece of pipe with a diameter of 15 cm is mounted on top of the pipe and welded to the cylinder by welding.
The free space between the two pipes is filled with insulation, the edges are closed with a weld.
In the second cylinder, the bottom is cut off and a hole for the valve is welded. It will be used for afterburning pyrolysis gases.
Both cylinders are fixed to each other in a special groove using two welded rings so as to ensure the tightness of the finished structure. The groove is sealed with asbestos cord.

Important! Before starting to fire a home-made rocket stove, it is necessary to carefully check the quality of the connecting seams and the tightness of the structure. Air masses must not penetrate uncontrollably into the operating installation.

How to properly fire a rocket?

To obtain the maximum heating effect, the rocket-type furnace should be thoroughly heated before the main laying of the fuel material. For this, flammable materials are used: paper, wood chips, dry shavings, sawdust, cardboard, reeds or straw, which are placed in an open blower compartment.

Warming up the system will lead to the appearance of a characteristic sound - a quiet or loud buzz. Further, the main fuel is loaded into the heated device to obtain the required amount of thermal energy.

The firing process itself is carried out according to the following scheme:

Opening the door to the blower compartment.
Bookmark fuel material to maintain the optimum combustion temperature.
With the appearance of a hum in the furnace, the blower closes until the moment of complete transition to the silent mode of operation.

Important! If a closed air damper has led to a decrease in the intensity of the flame, it must be opened in order to increase traction and intensify the combustion process of the fuel.

Other types of rocket stoves

Based on the basic design of the rocket stove, other variants of heating devices with a higher efficiency were created, which are intended for outdoor use and internal operation as a source of heating and hot water supply.

Stove-stove

The device is designed for cooking and winter preservation, equipped with an extended cooking surface designed for several containers.

A distinctive characteristic of the rocket stove is that the vertical channel with the fuel chamber is located in the lower part of the cooking surface. In this case, hot air from the furnace quickly heats the surface, and in order to keep the stove hot as long as possible, fuel gases accumulate inside the horizontal channel. The remains of the gas mixture are discharged into a vertical smoke channel connected at an angle to the hob.

For ease of use, the stove is equipped with stable supports, so it can be easily used on any surface, both indoors and outdoors.

Stove with water circuit

Such a unit is equipped with a heat exchanger, which is connected to the heating system: radiators, pipes and a water tank. It is designed to create a complete autonomous heating system for a small garden or country house.

Structurally, the stove consists of the following functional elements:

The vertical fuel compartment and the brick fire channel are laid out on a solid concrete base. At the bottom of the structure there is an ash pan with a door for removing ash.
Vertical steel channel with a heat-insulating gasket, protected by an outer metal casing.
Heat exchange unit with a water circuit mounted on a metal casing.

A distinctive feature of the furnace is the creation of a water jacket, when a liquid heat carrier circulates through the pipes instead of air, providing efficient space heating.

Stove with stove bench

Another option for using a jet stove in everyday life is the arrangement of a convenient design with a special platform for relaxing in a sitting or lying position. The lounger can have a different form of execution - a trestle bed, a wide bed, a compact sofa, a bench.

Brick, rubble stone, clay mass with sawdust are used to make the stove bench. The high heat capacity of materials contributes to the accumulation of thermal energy for a long time, due to which it is recommended to install such a stove in living rooms.

According to the type of material used for the manufacture of the structure, rocket furnaces are:

Clay-brick. The good heat capacity of bricks and fireclay clay contributes to the fact that such structures accumulate well and release heat into the room. The temperature regime of fuel combustion in such furnaces can reach 1000 degrees. Clay-brick units require minimal maintenance, which consists in periodically coating the body with clay and eliminating cracks.
Metal . Such devices are made of metal barrels, gas cylinders, fire extinguishers, pipes and sheet steel. The availability of materials allows you to get a reliable and efficient heating unit. Camping metal stoves - "Robinson", "Ognivo" or "Taiga" are especially popular. They are compact in size, can be installed anywhere and are easy to use.
From improvised materials. Simplified designs of rocket ovens can be made from the cheapest and most affordable materials: cans, steel buckets and other containers. Low-power stoves can be used to quickly heat water in the field.

A mobile stove is a practical and cheap option for hiking and outdoor recreation, which is designed for economical fuel consumption and ease of use in any climatic conditions.

A stationary stove is an efficient and safe option for heating small areas, organizing hot water supply and cooking.

For all its merits, a do-it-yourself reactive furnace design is not suitable as a full-fledged heat source for heating a residential building. But to use the technical capabilities of the device to solve everyday problems is quite acceptable.

Let's say right away: rocket stove - a simple and convenient heating and cooking device for wood fuel with good, but not exceptional parameters. Its popularity is explained not only by the catchy name, but more so by the fact that it can be made with your own hands and not by a stove-maker or even a bricklayer; if necessary - literally in 15-20 minutes. And also by the fact that, having invested a little more work, you can get an excellent couch in the house without resorting to the construction of a complex, expensive and cumbersome or. Moreover, the very principle of the device of the rocket furnace gives great freedom to design and the manifestation of creative abilities, see fig.

But perhaps more remarkable is the "jet furnace" by the huge number of associated, at times completely absurd inventions. 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 sit down near the ramjet engine (ramjet), as they say, and did not sit down in the bushes. On the 25th and 31st there are bypass turbojet engines (turbojet engines), four of which then pulled the Tu-144 and still pull other cars. And any furnace with any jet engine (RD) is technical antipodes, see below.
"Reverse jet furnace". Is this a tail-first stove, or what?
“But how will she blow such a pipe?” A naturally aspirated stove does not blow into the chimney. On the contrary, the chimney pulls out of it, on natural draft. The higher the pipe, the better it pulls.
“The rocket stove is a combination of a Dutch bell-type 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 but a Dutch one. Secondly, the couch of the Russian stove warms up in a completely different way than the rocket stove.

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

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 internal combustion engine, only the outflowing 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 large pressure that pushes the piston, and it already moves the entire mechanics. The movement of the piston is active, the working fluid pushes it to where it tends to expand itself.

In the furnace, there is no conversion of types of energy into each other, therefore it is not an engine. The stove simply distributes the potential heat energy properly in space and time. From the point of view of the furnace, the ideal RD has an efficiency of 0%, because it just runs on fuel. From the point of view of a jet engine, the furnace has an efficiency = 0%, it only dissipates heat and does not pull at all. On the contrary, if the pressure in the chimney rises to or above atmospheric (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. Draft in the chimney without pressurization, i.e. without the expenditure of energy from the side, it is provided due to the temperature difference along its height. Potential energy here, again, is not converted into any other.

Note: in a rocket-propelled rocket engine, fuel and oxidizer are fed into the combustion chamber from tanks, or they are immediately filled into it if the rocket engine is on solid fuel. In a turbojet engine (TRD), the oxidizing agent - atmospheric air - is injected into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes a certain fraction of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the power of the jet, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), air is supplied to the combustion chamber by hypersonic velocity pressure. A lot of experiments were carried out in the ramjet, but there were no production aircraft with it, there is not and is not expected, the ramjet is painfully capricious and unreliable.

Can or not can?

Among the myths about the rocket stove, there are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the "racquet" with the Chinese kan.

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

How to deal with rockets?

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

The Rocket Oven Was Invented by Members of Survival Societies- people with a peculiar way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they always automatically converted everything into money, taking into account their own benefit; a person with a different worldview in America simply does not get along. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of a spiritual outburst, but out of the calculation of dividends. Not in this life, but in that one.

Note: How much the average inhabitant of the greatest empire in history is afraid of everything can be understood only after talking with them long enough. And sociopsychologists go out of their way there, convincing that living, languishing in fear, is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Note: An American acquaintance once asked the author of this article - how did we, the really stupid ones, elect the very smart Reagan as president? And you, 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 settle in the Oval Office, and his first lady would dig a 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 misunderstanding

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

Why, for example, can not be made the size of a refrigerator and a power somewhere that way at 50-60 kilowatts? Because the potbelly stove, in order for it to somehow warm, 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, firewood or coal needs as much as it does not fit in it. There will also be no sense from a mini-potbelly stove: the heat will leave through the outer surface of the furnace, which has grown relative to its volume, and the fuel will not give it away more than it can.

Judging by the structures from 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 guess to arrange a blower, but the bunker is left open. Are the exact proportions of vermiculite with perlite for lining the riser and forming the furnace body (core) not specified? We make the lining homogeneous, although it will be clear from what follows that it should consist of insulating and accumulating parts. As a result, the furnace roars, the fuel eats only dry, and a lot, and even before the end of the season, it overgrows with burning inside.

How was the rocket oven born?

So, already without science fiction with futurology, the survivors needed high-efficiency home heating stove with low-quality random wood fuel: wet wood chips, twigs, bark. Which, moreover, will need to be reloaded without stopping the furnace. And most likely it will not be possible to dry in a firewood shed. Heat dissipation after heating needs at least 6 hours to get enough sleep; getting pissed off in a dream on Pluka 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 are required for the manufacture of production equipment, and the furnace itself must be available for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics and other energy dependencies.

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 fuel, continues for 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, woodgas.

Note: in RuNet, woodgas has created more confusion, because in American vernacular, gas can mean any fuel, cf. e.g. gas station - gas station, gas station. When translating primary sources without knowing the American technical, it turned out that woodgas is just wood fuel.

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 read, smart guy, school textbooks. That is, go to the 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 principle of operation of their furnace, which has no analogues in others: slow adiabatic post-combustion 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 the energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but practically into free volume. And now - learn to think in an American way.

How does a rocket oven work?

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

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to fool around with the latches. We will simply make a cover from a metal sheet on screws with a mineral cardboard gasket.

small rocket

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

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

How to fire a rocket?

A rocket furnace with long-burning furnaces has a common property: you need to run them only on a warm pipe. For a small one, this is not essential, but a large one on a cold chimney will only burn fuel in vain. Therefore, a large rocket furnace, before loading regular fuel into the bunker after a long break in the furnace and kindling, must be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open blower. The end of acceleration is judged by a change in the tone of the hum of the furnace or its subsidence. Then you can load fuel into the bunker, and its ignition will occur by itself from the accelerating fuel.

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

Materials, dimensions and proportions, lining

Now let's see what a home-made rocket stove should be from the materials available to us. Here, too, we need to look back: not everything that is at hand in America is also with us, and vice versa.

Of what?

Note: it is desirable to equip the rocket furnace with a view in the external chimney. Although the gas view in the high riser seals the common smoke path tightly, strong winds outside can prematurely draw heat out of the couch.

Dimensions and proportions

Drum height H - 1.5-2D.
Drum coating height - 2/3H; for the sake of design, the edge of the coating of the design can be made oblique curvilinear, then 2/3H must be maintained on average.
The thickness of the coating of the drum is 1/3D.
The cross-sectional area of the riser is 4.5-6.5% of S; it is better to stay within 5-6% of S.
The height of the riser - 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.
The length of the flame tube is equal to the height of the riser.
The cross-sectional area of the flame tube (fire pipe) is equal to that of the riser. It is better to make a fire pipe from a square corrugated pipe, so the furnace mode will be more stable.
The cross-sectional area of the blower is 0.5 from 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.
The volume of the secondary ash pan is from 5% of the initial volume of the drum (excluding the volume of the riser) for a furnace from a barrel to 10% of it for a furnace from a cylinder. Interpolation for intermediate drum sizes is linear.
The cross-sectional area of the external chimney is 1.5-2s, where s is the cross-sectional area of the riser.
The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is considered from its lower point. If the bench is on wooden floors, the pillow under the chimney can be halved.
The height of the bed coating above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. It can be less, but then the heat transfer after heating will be shorter.
The height of the external chimney is from 4 m.
Permissible length of the flue in the couch - see next. sec.

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

Riser lining

How to line with sand?

balloon rocket

From the foregoing, it is clear that it is more profitable to make a rocket stove: less work, fewer unsightly parts in sight, and the stove bench warms up almost the same. A thermal curtain or underfloor heating in 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, it is rarely necessary to launch a large barrel at full power with maximum efficiency.

Rockets from anything

Canned

The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
The height of the combustion chamber is 3-5 of its diameters.
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.

brick

Video: 16 brick rocket oven (eng)

new material

Do rockets fly in the bath?

Isn't a rocket stove suitable for a bath? It seems to be possible to arrange a heater on the drum cover. Or flowing instead of a couch.

Unfortunately, the rocket oven is not suitable for a bath.. To get light steam, it must immediately warm up the walls with thermal (IR) radiation, and immediately, or a little later - air, by convection. To do this, the oven must be a compact IR source and a convection center. The convection from the rocket furnace is distributed, and it gives little IR at all, the very principle of its design eliminates significant radiation losses.

In conclusion: rocket stove-makers

Now there are many stoves that use firewood as fuel. A special place among them is occupied by the so-called jet (rocket) units, which have specific features that are indispensable in certain operating conditions. Let's talk about them.

The rocket is a real marvelous unit!

The rocket stove is a heating and cooking system that operates on wood, is famous for its high technical performance and has a simple design. The principle of operation of such a long-burning unit is based on the fact that the gases formed during the combustion of fuel enter a special bell, in which they are completely burned. Due to this, the temperature indicators of the stove increase significantly, and the pressure value decreases. Moreover, soot is not formed in the jet heating system.

The cycles of combustion of heated gases are repeated constantly (while the furnace is being heated). This causes the system to go into maximum thrust mode. Its specific value is determined by the features of a home-made unit. If the heating device is assembled really correctly, the temperature in its hood can reach 1200 ° C. In this case, all the fuel used is burned without residue. It is also important that the heated cap is allowed to be used as a hob. On it you can dry fruits, heat water, cook food.

Initially, the stove we are interested in was designed for use in difficult (for example, camping) conditions. Because of this, its design put forward special requirements. The result is a unique unit that:

makes it possible to cook in areas where there is no gas and electricity;
qualitatively heats the room;
saves heat for 6-8 hours (minimum) after burning firewood;
has a high efficiency;
quite safe to use.

In addition, the rocket has a design that allows you to report a new portion of firewood into the furnace without stopping the combustion process. The operation of the unit with similar capabilities, of course, is to the liking of any person. This determines the high popularity of the described heating systems both among outdoor enthusiasts and among ordinary summer residents who need unpretentious and efficient stoves.

An important point. If you plan to create the simplest jet unit with your own hands, it can only be heated with dry wood. Wet wood can cause backdraft. However, it is not recommended to kindle more complex rockets with wet wood, since they will not be able to provide the high temperature required for burning heated gases.

The described heating devices must not be left unattended. Melted the stove, wait until the fuel burns out completely. Another drawback of rocket equipment is the impossibility of heating private baths with it (in particular, their steam rooms). This is due to the fact that the jet unit gives very little infrared heat, which is exactly what is required for taking bath procedures. Missiles, perhaps, have no other disadvantages.

Types of jet heating installations - what do you need?

The simplest rockets are made from almost any tin can. A portable stove can be made from a bucket, a can of paint, and so on. Such systems are ideal for a picnic in nature, they are often used on construction sites. Simple stoves are not suitable for space heating. They are used exclusively for cooking, heating water. A rocket made from a bucket can be fired with a small torch, dry cones and foliage, bunches of branches. In such a stove, combustion products do not have time to form combustible wood gas. They immediately go into the chimney.

More complex heating structures are created from an old gas cylinder or from a metal barrel and brick. These furnaces are necessarily equipped with a riser to increase traction and a horizontally located smoke path. There are also rockets made entirely of bricks. They can be equipped with several chimneys at once and are used for heating large rooms and floor heating. And if you wish, it’s really possible to build even a full-fledged stove-bed.

We will tell you how to independently make all these types of reactive devices for heating. And let's start our master class with the simplest - with the manufacture of an elementary garden-camping stove from two tin containers (buckets, cans). In addition to them, we need steel clamps with a section of 10 cm, metal corners, a grinder, a stainless steel chimney pipe, metal scissors, gravel. The scheme of work will be as follows:

1. We take two buckets. From a container of a smaller volume (diameter) we make a cover for our rocket. Cut a hole in the bucket. It is necessary for the organization of the chimney.
2. In a larger bucket, cut out another hole at the bottom. We will connect the firebox to it. We carry out all operations with scissors for metal, bending the resulting petals (pieces of tin) inward.
3. We construct a forward flow from the pipe and corners. We insert it into the bucket, and then, using a clamp, we connect it with curved petals.
4. We fill the space between the forward flow and the body of the heating device with gravel. This building material will play the role of a heat accumulator and at the same time a heat insulator.
5. We put the second bucket on the stove.
6. We bend a small burner from the wire, on which it will be possible to install dishes with water and food.

It is advisable to paint a portable rocket with any paint with a high level of heat resistance. After drying, we can use an elementary cooking stove. Note! The ignition of the rocket is carried out through a branch pipe extending from the forward flow.

A stove made of barrels and bricks - both cooks and heats!

The construction of a stationary rocket launcher requires significantly more money and time. We prepare the following materials and tools: a metal chimney pipe, a red (required heat-resistant) brick, a shovel, an old barbecue, a metal brush, a trowel, cement and sand (it is better to immediately buy a mixture of these materials ready for use), reinforcing bars, a little perlite, adobe and expanded clay, heat-resistant paint, a barrel of 200 liters. We proceed to the construction of a brick oven and a metal barrel:

1. We dig a hole in the floor with a depth of 0.3-0.5 m. We will hide a horizontal chimney in it, without which the rocket launcher will not work.
2. We burn a 200-liter barrel, thoroughly clean it. We mount a flange in the tank that will connect it to the chimney. After that, we apply several layers of heat-resistant paint to the container. We use the barrel prepared in this way as a cap for the heating unit.
3. We equip the foundation. We make a simple formwork from boards, deepen 2-3 bricks into the ground at the installation site of the furnace. We place reinforcing bars on top. Then we lay bricks in the lower part of the combustion chamber (around the entire perimeter). We fill the structure with a cement-sand mortar.

After the fill dries, we proceed to the masonry. It is done with . We bring the first tier of masonry up. We need to leave only a hole for the firebox. On the second line we form a channel (lower) of the heating structure. It should be blocked on the third tier, and in such a way that we have two holes left. One of them is intended for the vertical channel, the second - directly for the combustion chamber.

Next, we mount a tee in the barrel to clean the chimney. It is not necessary to install it, but it is desirable if you plan to use the stove for a long time. After that, we put a vertical channel. The rising section of the structure (we take its diameter of about 18 cm) is laid out using the "boot" technology. Then we put on the old water heater on the ascending part of the furnace. All voids that remain after this operation are filled with perlite.

Now we cover the base of the casing of the rocket unit with clay and surround the base of our structure with sandbags. All remaining free areas are filled with expanded clay. We connect the chimney pipe to the structure, turn the casing barrel over and pull it onto the rising part of the stove. The final work is lining the chimney with sand in bags and filling them with expanded clay. Then we give the structure the required shape with the help of clay (fireclay), mount a barbecue grill in the neck of a home-made rocket and cover it with a lid.

The last step is to seal the existing seams on the furnace. In principle, we can already do a trial run of our design. But experts advise additionally bringing a separate air duct from the street to the stove. It is important. A heating rocket needs a lot of air to function properly. In the room it will not be enough. A street duct is guaranteed to solve this problem.

Rocket heating from a cylinder - let's work with a welding machine

For the construction of the rocket, we choose a heat-resistant and non-explosive cylinder. An all-metal 50-liter tank in which propane is stored is optimal for these purposes. Such a balloon has standard dimensions: height - 85 cm and cross section - 30 cm.

Such parameters are ideal for self-production of the furnace. The modest size and small weight of the cylinder do not make it difficult to work with it. At the same time, it is allowed to burn any wood fuel in the finished rocket. You can also take propane cylinders for 27 or 12 liters. They make compact portable stoves. But the power indicators of such devices are small. It is not advisable to use them for heating rooms, country houses.

For the construction of the furnace, in addition to the cylinder, you will need:

pipes made of steel with a cross section of 15, 7 and 10 cm (the first two will go to the organization of a vertical internal channel, the third - to the chimney);
profile tubular product 15x15 cm (we will make a loading compartment and a firebox from it);
3 mm thick sheet of metal;
dense (100 or more kg / cubic meter) basalt fiber (it will serve as a heat-insulating material).

On the Internet there are various drawings for creating a stove from a balloon. We propose to follow this scheme.

The algorithm for manufacturing a rocket balloon installation is simple. First, we bleed all the gas from the tank. Then we unscrew the valve, fill the tank with water (up to the top) and cut off its upper part along the seam. We cut out the windows on the two sides of the gas cylinder that are required to connect the chimney and install the fuel chamber.

After that, we insert the profile tubular product into the container, connect it to the channel (vertical). The latter is taken out through the bottom of the tank. Next, we perform all the necessary actions, focusing on the presented drawing, as well as on the video that we offer home craftsmen for review.

At the end of the work, we weld the cut off part of the container in its place, analyze all the resulting seams for permeability. Uncontrolled entry of air into the structure must not be allowed. If the seams are reliable, we connect a chimney to a home-made system. We weld the legs to the bottom of the rocket balloon. We install the stove on a steel sheet with parameters of 1.5x1 m. The unit is ready for use!

Stove-couch - for lovers of special comfort

The heating unit with a place to sleep and rest is equipped with a special heat exchanger. Its channels are interconnected. They are made from non-flammable materials. The heat exchanger is installed under the bed plane. The design of such a furnace is very thoughtful and relatively complex. The bed itself is a surface made of brick or stone and clay. When the stove burns, the heated gas moves through the heat exchange channels, gives up heat, and then is removed through the smoke duct outside the house. The height of the chimney is made within 3–3.5 m. The stove is mounted at the edge of the bench (on one side). In most cases, it is equipped with a cooking surface. A detailed drawing of this system is shown below.

Elements of the furnace in the diagram:

blower - 1a;
fuel bunker - 1b;
channel for secondary air - 1v;
flame tube - 1g;
riser (primary chimney) - 1d.

The fuel chamber is equipped with a blind cover, the blower is equipped with a special regulator for adjusting the amount of air supplied. The flame tube has a length of 15–20 cm. The secondary air channel is necessary for the complete combustion of gases. The cross section of the riser is 7–10 cm. A chimney with a diameter of 10 cm is recommended for cases where we want to get the most rocket power. A riser with a cross section of 7 cm provides an optimal indicator of the efficiency of the stove. The flame tube and the primary chimney need high-quality thermal insulation.

We will make the rocket body from a gas cylinder, although a metal barrel can also be used. Under the housing cover (2a), the primary chimney supplies heated air, and the heated gases leaving the riser heat the cooking device (2b). Other body elements:

lower part (2d);
heat exchange channels (2d);
shell - metal insulation of the chimney (2c);
exit to the cleaning chamber (2e).

The flue pipe must be completely sealed throughout. At a height of 1/3 from the upper end of the drum (body), the gases already have a low temperature. They get cold. Approximately from the specified height, the rocket bed is lined (to the floor). This process is understood as the thermal insulation of the furnace with special compounds. The second cleaning chamber in the scheme (3a) is needed to remove carbon deposits from the hog (4) - the heat exchanger. It must be equipped with a sealed door (3b). Now that we have dealt with the design of the couch, we can proceed to its construction.

Building a rocket with a place to sleep - the first steps are the most important!

Before starting work, we knead all the necessary compositions:

Kiln clay (designation 5b in the diagram), which is connected to crushed stone. This composition plays the role of the main heat insulator.
Saman (5a). It is a composition of straw and any clay at hand, diluted with water to a relatively thick consistency.
Seeded sand (5g).
Heat-resistant lining (5v). It is made from equal parts fireclay sand and clay.
Clay of medium fat content (5d). It is used for laying rockets.

We make a bed for our couch. In fact, we need to knock down high-strength shields under the stove bench and directly under the stove. We make the frame of the structures from wooden bars 10x10 cm. We make the cells of the frame with dimensions of 60x120 cm (for the bed) and 60x90 cm (for the heating installation). Then we sheathe the resulting 4-centimeter skeleton. And the facade of the couch can be finished later with sheets of drywall.

It is advisable to treat wood products with Biocide before installation, and then apply two layers of an aqueous emulsion on them.

We lay on the floor, where we will put a heating rocket, basalt cardboard 4 mm thick. In shape and geometric parameters, it must be similar to the characteristics of the bed. We install an iron roofing sheet on top of the basalt lining. In front of the firebox, it will come out from under the unit by about 25 cm. We mount the bed made earlier on the place prepared for it. On the wall at a height of 13 cm above the level of the bench (at one of its ends), we punch a hole. It is necessary for the device of the chimney.

The next stage is the installation of formwork along the perimeter of the bed and pouring the installed structure with adobe. The surface of the mixture is carefully leveled using the rule. We wait 14-20 days until the adobe hardens. During this time, it is possible to make the body of the heating structure from a gas cylinder according to the previously described scheme. The furnace parts of the rocket (blower, flame channel, chamber) are welded into a single structure with a gas container and coated with a heat-resistant lining. Important! We apply the composition in a continuous layer only below. We do not process the upper part and sides of the structure with a solution.

Next, we mount another formwork under the area where the rocket will stand. It will allow us to make a heat-resistant thermal protection of the stove. The height of the formwork structure is about 10 cm. We fill it with a mixture of crushed stone and oven clay. Then, one by one, we do:

1. Shell. We bend it from a sheet of steel or use a finished pipe with a section of 15–20 cm.
2. Furnace structure.
3. Cleaning chamber. This element is made of 1.5 mm galvanized steel. On the side, we cut an opening with a section of 16–18 cm. A chimney will subsequently enter it.

Completion of work - a warm couch will turn out well!

We put the drum from the gas cylinder on the primary chimney. At the bottom of the installed body, lay out the oven clay, forming an inclined surface (about 7 °) with a spatula, which is directed to the window of the cleaning compartment. Then we put a metal round timber on the chimney. It should be pressed into the clay composition. Then we stretch the shell on the riser and coat it with clay of medium fat content. The next steps are:

1. We line the chimney from the inside. We use sand. It should be covered in separate layers. Each of them is wetted and rammed. The total number of layers is 7. We put 5 cm of medium-fat clay on top of the sand.
2. We put a cleaning box, coating its bottom and side surfaces with clay. We mount the opening of the transition channel in the opening of the drum, press it as hard as possible. All remaining gaps are sealed with clay. It is necessary to achieve complete tightness of this stove assembly.
3. Along the contour (external) of the bed, we mount the next formwork. It should rise above the edge of the hole for the hog by about 9 cm. Fill the formwork with adobe mixture.
4. We stretch the corrugated pipe along the entire length of the rocket bed. We connect one end of the corrugated product to the cleaning department.
5. We lay the fixed corrugated pipe in a spiral and insert its second end into the chimney outlet opening, fixing the junction with a clay composition.
6. We process the burs along the entire length with a solution of adobe, compact this coating.
7. We fix the housing covers and the cleaning chamber with bolts, under which we install rubber gaskets.
8. We coat the drum with adobe (we do not touch only the upper part) with a layer of about 10 cm.

After about 17 days, the adobe will dry out. We will be able to remove the formwork, apply special enamel to the drum, which can withstand heating up to 750 °C. Then experts advise to treat the adobe surface with acrylic-based varnish (preferably in two layers). Such a coating will protect the structure from moisture and make the stove outwardly very attractive.

The heated bed is done. We test our facility before the start of its full operation. Verification is elementary. We put some paper in the firebox, set it on fire, and monitor the behavior of the rocket. If everything is fine - there are no frightening sounds, we put firewood. After a while, the unit will begin to hum. At this point, we close the blower of the furnace. We wait. When the buzz is replaced by a gentle whisper (the soft sound of a working stove), open the blower a little. Next, we use the heating installation for its intended purpose.

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Drawings of a jet stove from a gas cylinder. What is a Rocket Furnace?

Rocket stove - wood-fired device

Furnace or rocket?

Can or not can?

How to deal with rockets?

Sources of misunderstanding

How was the rocket oven born?

What is wood gas?

Who are you, the Rocket Stove?

How does a rocket oven work?

small rocket

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

How to fire a rocket?

Materials, dimensions and proportions, lining

Of what?

Dimensions and proportions

Riser lining

How to line with sand?

balloon rocket

Rockets from anything

Canned

brick

Video: 16 brick rocket oven (eng)

new material

Do rockets fly in the bath?

In conclusion: rocket stove-makers

Description of work

Principle of operation

materials

Getting Started

Blower manufacturing process

Desired volume of perlite

rocket stove video

What is a Rocket Oven?

Principle of operation

Advantages and disadvantages

Design

DIY manufacturing

How to properly fire a rocket?

Other types of rocket stoves

Stove-stove

Stove with water circuit

Stove with stove bench

Furnace or rocket?

Can or not can?

How to deal with rockets?

Sources of misunderstanding

How was the rocket oven born?

What is wood gas?

Who are you, the Rocket Stove?

How does a rocket oven work?

small rocket

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

How to fire a rocket?

Materials, dimensions and proportions, lining

Of what?

Dimensions and proportions

Riser lining

How to line with sand?

balloon rocket

Rockets from anything

Canned

brick

Video: 16 brick rocket oven (eng)

new material

Do rockets fly in the bath?

In conclusion: rocket stove-makers

The rocket is a real marvelous unit!

Types of jet heating installations - what do you need?

A stove made of barrels and bricks - both cooks and heats!

Rocket heating from a cylinder - let's work with a welding machine

Stove-couch - for lovers of special comfort

Building a rocket with a place to sleep - the first steps are the most important!

Completion of work - a warm couch will turn out well!

What else to read

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