•If we take a closer look at nature, we can see that everything in nature is balanced, self-regulated and optimal. Human beings are themselves part of nature. So far we couldn't come up with something that would at least match nature creations and probably will never do.

•This is why we, human beings, have to discover nature’s laws, study them and follow them. This is what we are trying to achieve in our work.•.

At the current time, the major goal in work of scientists and other professionals working on improvement of combustion systems that use air as oxidizer is to diminish adverse effects of ballast gases that affect heating value of the fuel. The greater amount of ballast gases is the grater are adverse effects.

Measures for diminishing these effects:

•use of very dry fuel or manipulating air supply systems in order to get lowest possible amount of excess air without increasing emissions.

www.stove.ru

•Our System suggests different way for diminishing adverse effects of excess air on combustion. Heat produced in the combustion is also utilized differently on our System.

The "System of Free Gas Movement" was born in Russia at the beginning of the 20th century. Professor V. E. Grum-Grzhimailo(1864-1928) elaborated the basic theory. His follower, Podgorodnikov I. S. Ph.D.(1886-1958), continued his work. He proposed to design stoves using ”Double bell” method.

In mid 60s, Igor Kuznetsov, another Russian engineer and mason, has continued the work on further improvement of the System. He defined some basic principles that weren't reflected in the previous work. In particular, basics for design of the stoves, functioning on the principle of "free gas movement" were formulated.

Грум-Гржимайло

www.stove.ru

•Hot gas has lower density, therefore it goes up if surrounded by the pool of colder gas. Thus, all stoves in all their parts must be designed in such manner that gases would be allowed to move naturally - hot gases up and cooler gases down.

•While this idea allowed to come up with significant improvements in kiln and stove designs, neither Grum Grzhimailo nor Podgorodnikov were able to come up with the most important solution: facilitation of the FGM principles right in the firebox.

•The drawing features a stove of Grum Grzhimailo

www.stove.ru

The basic idea of the FGM system that was formulated by Grum Grzhimailo is as follows:

It is only possible to to achieve natural hot gases movement in the fire chambers built according to the formula that I was able to come up with: “Lower part of the stove and firebox are sharing common space, creating a lower bell. I.e. firebox is an integral part of the bell itself.

www.stove.ru

•My formula assumes such an important feature as “dry joint” – 2-3 cm wide vertical slot connecting firebox and the bell into a common volume.

•The formula works for fire chambers of any shape or volume, of different combustion principles and for different types of fuel.

•Bell essentially is a glass or a cavity turned upside down where hot gases are floating up while pushing cooler ones down.

Here we speak about fuel combustion in the firebox; the firebox and the bell are connected into common volume with 2-3 cm wide vertical crevice (dry joint) that makes the firebox to be an integral part of the bell, not a separate part inserted into the bell. This solution creates conditions in which gases are allowed to move naturally:hot gases are floating up while pushing cooler ones down.

This formula corresponds to the theory of V.E. Grum Grzhimailo. The novelty is that at such design of heat-generator not only in the bell but also in the combustion chamber the conditions are created allowing the gases to move naturally. In this case specific heat stress can be maintained within lower and upper limits.

www.stove.ru

Essence of the formula

•To extract maximum amount of heat possible with combustion of the corresponding fuel (highest combustion efficiency)

•Utilize maximum of the extracted heat (maximum heat transfer efficiency);

•Design has to correspond to functional and aesthetic requirements while maintaining highest combustion and heat transfer efficiency.

•It turned out that it is possible to reach all these goals in the system of free gas movement (FGM) .

www.stove.ru

The essence of the conception

Double bell

The combustion of fuel can be performed effectively, utilizing maximum of the extracted energy but at the same time use the heat ineffectively.

On the contrary,it is possible not to extract the fuel energy in full but utilize it effectively.

Therefore it is possible to consider that the efficiency of the energy plant is made up of:

•Efficiency of energy extraction from the fuel

•Efficiency of utilizing of the extracted heat.

www.stove.ru

The essence of the conception

www.stove.ru

Utilizing the extracted heat (efficiency) in FGM and FGM and the difference in systems

In any stove design with convective system, gas flow moves around heat energy and products of combustion. For easier understanding the difference of principles of gas movement in the “system of forced gas movement” (FGM) and in FGM, let’s imagine that an electric heating element is our heat source and we therefore don’t have to exhaust products of combustion.

Let’s fill the bell with a portion of hot air (Fig. A1). Being lighter, it will raise up, push according portion of the cooler gas out of the bell and will sit there transferring its heat to the walls.

Heat-accumulating bell

www.stove.ru

If hot air generated by the electric heater is constantly supplied to the bell, part of the flow heat will heat the bell walls and the heat exchanger inserted in the bell.

If more heat is generated than the bell with the heat exchanger can accept,the excess heat (cooled air from the lower part of the bell) comes into the pipe.

High pressure is formed in the bell, which grows in height.

Hot air moves in the bell without pipe draw due to natural forces of nature and does not require external energy.

Heat-accumulating bell

www.stove.ru

Let’s see what is going to happen if we will get a flow of hot air to pass through the lower portion of the bell, Fig. A2, hot gas will rise where heat-exchanging processes take place. •Heat is going to be transferred to walls of the bell and to the heat exchanger inserted in the bell. The excess of heat (cooled air) goes outside.

• Such heat exchanger can represent anything: a water coil, air-to-air heat exchanger, retort for fuel gasifying or any other technological insert.

•Theoretically it is possible to come up with heat exchanger of such size that it will take all the heat from the hot gas. Thus, in this case we can say that heat transfer efficiency will be close to 100%.

Heat-accumulating bell

www.stove.ru

•Rate of heat transfer from hot gas to the heat exchanger depends on several variables:

•Contact area for the heat transfer (surface area of the heat exchanger);

•Delta “T” – difference in temperatures of the gas and the heat exchanger;

•Duration (time) of the heat transfer.

•The greater they get – the greater is the rate of heat transfer.

•As bell can have any volume and shape, it is possible to create better conditions for heat exchanger that will facilitate better, more efficient heat transfer.

www.stove.ru

•What is going to happen if we will direct gas flow from an external firebox where combustion of any fuel is happening using ambient air as oxidizer (Fig. A2) the same way – through the lower portion of the bell?

•This gas flow will contain products of combustion – a mixture of different gases where part of them is ballast gases (gases that came with the air but haven’t participated in the reaction of combustion). Their molecules are totally independent and not interconnected.

Products of the combustion reaction using oxygen as oxidizer: (СО2);

•steam from reaction (combustion of hydrogen);

•evaporated moisture from the fuel

In this case heat extraction takes place.

Besides, if oxygen is used as oxidizer,there is nitrogen and excess air.

Heat-accumulating bell

www.stove.ru

Ballast gases:

Nitrogen – is an integral part of air required for combustion that takes 4/5th of the volume. Due to imperfection of air mixing the supply of air shall be 1.6-2.4 times more than the required amount, therefore in the combustion chamber there is an excess of air that didn’t participate in combustion reaction as well аs evaporated moisture from the fuel.

All these gases are ballast gases, they are harmful components of the flow as they do not take part in combustion but only get heated due to the heat extracted during carbon and hydrogen combustion, that is they absorb useful heat.

This gas flow gets separated into different components while passing through the lower part of the bell.

Heat-accumulating bell

www.stove.ru

•Each and every particle of the gas flow has its own condition: weight,temperature, energy and moves around in the bell according to its condition for the duration of its free movement through the bell.Hotter part of the gas flow, being lighter, will raise up in the bell, while the cooler portion, being heavier, will have higher speed and will pass through the lower portion of the bell not affecting top of the chamber.

•It is similar to the water behavior in a deep hole: cold water at the bottom is never bothered by the lighter warmer layers on the top.

•The hotter portion raise up and will stay till it will cool down sufficiently to be replaced by a portion of new hot gases.

•Conclusion: Heat transfer efficiency will be higher when gases are directed to pass through a bell due to the fact that adverse effects of the ballast gases is diminished.

•This is impossible to achieve in systems of forced gas movement. If we remove the dry joint, all gases are mixed together.

www.stove.ru

•In Forced GM systems, all products of combustion including ballast gases are mixed together and dragged through all channels in common flow. This results in lower overall temperature of the gas flow, and lower heat transfer efficiency.

•Volume of ballast gases has to be lowered in order to diminish these adverse effects and to increase efficiency. The volume of the ballast gases is diminished due to combustion of dry fuel and improvement of mixture of gases (decrease the efficiency ratio of excess air - λ, not permitting incomplete combustion).

•Important conclusion: Heat transfer efficiency is higher in convective systems (heat exchanging part of the stove) constructed by the FGM principle (bell). It is important that it is true regardless of what kind of fuel is used and what type of firebox is used as long as air is used as oxidizer for the combustion.

www.stove.ru

Extraction of energy from fuel (Combustion efficiency)

•Combustion must be complete in order to improve efficiency of a heat generator and to lower emissions into the atmosphere.

•In the process of combustion, concentration of the combustible gases and oxygen is decreasing rapidly while concentration of the products of the combustion and temperature are increasing rapidly.

•In any system, secondary combustion air has to be supplied above fuel to combust burnable gases originating from gasified fuel.

•There are four known conditions that facilitate complete combustion:

•Proper design of the firebox;

•Proper mixing of gases;

•High temperature;

•Optimal supply of primary and secondary combustion air.

www.stove.ru

•In systems of Forced GM, combustible gases and oxidizer (air) move in the same direction, increasing amount of ballast gases in the flow as they go through the channels.

•Concentration of the combustible gases and oxygen is decreasing rapidly in the finial zone of combustion.

• Combustible gases get separated with increasing amount of products of combustion.

• In this case it is very important to facilitate high turbulence of the gas flow.

• It is also necessary to provide the amount of air sufficient for complete combustion, while trying to come up with minimal possible amount of excess air.

www.stove.ru

•However, in any case, firebox will contain excess air, nitrogen and steam. They lower temperature of the gas flow and worsen conditions for the fuel combustion.

•Not all energy is extracted from the fuel due to lower combustion temperatures in the flow. And extracted heat energy is not used completely as well because part of it is used to heat ballast gases in the flow.

•Therefore, we can make an important conclusion:

•Adverse effects of the ballast gases on combustion have to be diminished and temperature of combustion increased.

www.stove.ru

Combustion systems of Forced GM have no space for location of heat exchangers in a way that allows conditions of combustion to correspond to the conditions of utilization of the extracted heat

•There is a disagreement between the conditions of combustion and the conditions of heat utilization when heat exchangers are installed inside the firebox, i.e. the more heat is extracted by the heat exchanger (higher heat transfer efficiency) the worse is combustion or conditions for combustion (lower combustion efficiency).

•Heat exchangers located inside the firebox lower combustion temperature and affect fuel combustion adversely.

•However, temperature of the gas flow will also decrease if cross-section of a channel is increased so it can accept a heat exchanger, energy gets “dissipated” .

www.stove.ru

•Theoretically, it is possible to burn fuel right inside a bell, without a firebox, however, combustion will be far from ideal as temperatures will be low, air supply not optimized, no good mixing of gases possible and no pre-heating of combustion air is possible. This is the reason why combustion has to happen in a proper firebox or fire chamber.

Conditions that we create in our System are different from conditions that are common in systems of Forced GM.

Firebox is surrounded by the walls at all the sides and has a “catalyst” –a grate made from firebrick located at the upper level;

The firebox is provided with “dry joint” connecting it with the bell.

•There are channels supplying preheated secondary air over the fuel through outlets in the walls, and there is a 15-20 mm slot for secondary air supply right in front of the firebox door.

www.stove.ru

•We create conditions in the firebox (Fig.1) where each and every particle of the gas flow has its own motion path defined by its own condition and moves around in the bell according to its condition for the duration of its free movement through the bell.

•If we supply air into the top portion of the firebox, it will be pushed down against direction of hot gas flow as being lighter in the hot gases environment. It is similar to water pushing down particles that are lighter than water onto the surface. The largest part of preheated secondary air supply is supplied to the top levels of the firebox under the catalyst area and into it;

•The catalyst induces turbulence and increases temperature in the firebox by reflecting heat back.Secondary cooler air coming into the bell condition is pushed down against direction of hot gas flow.

www.stove.ru

•Contrary to systems of Forced GM, oxidizer and burnable gases travel in opposite directions. It stimulates turbulence and good mixing. This zone in the firebox becomes extremely important.

• The particles of burnable gases get connected with oxygen of the air and extract heat turning into carbon dioxide and water steam.Products of combustion are also produced.

•Hotter gases raise up in the bell, creating high temperature area at the top of the bell where heat is utilized in heat exchanging parts of the stove that are located outside of the firebox.Ballast gases are pushed down into lower area of the firebox and then through the “dry joint” to lower parts of the bell and out of the lower bell for secondary use or out into the chimney.

www.stove.ru

•In this case we can supply more air into the firebox without fear of lowering temperature in the firebox or in the bell.

•It has to be noted in this respect, that test methods developed for testing of systems of Forced GM may not apply to the system of Free GM that may need different test methods developed.

•It has also be pointed out, that it seem to be possible that heating value of fuel may in fact be higher if combustion takes place in the bell environment for the fact that adverse effects of the ballast gases on the oxidation process are greatly diminished.

• As is known,wet wood has lower heating value,i.e. if we burn wet wood the amount of ballast gases increases.

•The influence of ballast gases on the combustion process and fuel heating value can also be traced on example of acetylene burning while performing welding operations.

www.stove.ru

•Heating value of acetylene depends on type of oxidizer, i.e. on amount of ballast gases.

• If air instead of oxygen is supplied into a burner,the temperature of combustion and heating value of acetylene will be too low for metal cutting and welding.

Combustion conditions in the firebox get changed.

Separation of the colder ballast gases (including excess air)takes place.

•High temperature environment is created that facilitates fuel heat-up and gasification at temperature around 1060°C in clean combustion.

www.stove.ru

Gas mixture incombustible at low temperatures becomes combustible at high temperatures. Separation of cooler and hotter gases as well as separation of gas flow (a mixture of gases) to components occurs.

•The fact that we locate heat exchanger outside of the firebox allows to maximum increase efficiency of the heat transfer without reducing efficiency of energy extraction from the fuel.

In this case the whole process of fuel combustion is natural, self-regulated and optimal.

The conditions for fuel combustion get improved,i.e.combustion efficiency gets higher.

The tests of stoves designed according to our system even made according to old technology without taking into account the latest developments, carried out in Canada and France showed their high efficiency, which are 10-20 % higher than the stoves traditionally used in these countries. .

www.stove.ru

Our system is characterized by extraordinary flexibility. That made it possible for us to create thousands high-efficiency designs of stoves of various purpose. We have a possibility of creating a large variety of heat generators of various shape, capacity and purpose, including industrial-type furnaces. In our system it is easy to create a great number of energy plants of different purpose using uniform components.

Fig.1is shown as an example.

It is possible to make a firebox from heat-resistant concrete or factory-made fire-proof brick.

One and the same firebox can be used in energy plants of different purpose.

This can be a bakery oven, stove used in steam sauna, a boiler, a multi-layer stove, combined stove with different functions, etc.

www.stove.ru

We insert into space above the catalyst3:

•Bakery chamber (in bakery oven);

•Steam generator (in steam sauna).

The firebox is shown with symmetric outlets into symmetric bells. The firebox can have an asymmetric shape, that is it can have an outlet to one side only.

The bells can have:

•a different shape;

•a different volume;

•They can be designed of various materials;

• Different devices can be inserted into them, such as a heating boiler or hot water supply boiler, air-to air heater, etc. An energy plant can have a second bell.

www.stove.ru

Gas generation in the system of free gas movement

Why do we speak about solid fuel gas generation?

• During burning of wood, peat or timber waste especially with high moisture content it is not possible to get high temperatures whereas during gas combustion received from this fuel,one can reach such temperatures.

• During solid fuel burning the combustion power adjustment is carried out only due to mixing (the amount of air).

• If we want to decrease the combustion power with reduced air supply (energy installation efficiency) the efficiency factor of the system is significantly reduced.

• The highest efficiency is reached at maximum power of fuel combustion.

• One can remove moisture contained in gas, which is ballast.

• It is not difficult to heat gas before combustion.

• When we burn gas less amount of excess air is required as compared with lump fuel.Thanks to that the combustion temperature increases, as well as energy extraction contained in the fuel.

www.stove.ru

• It is easier to introduce automation in the process of fuel combustion. There is a possibility to approximate combustion of solid fuel to gas or diesel fuel combustion with regard to convenience and efficiency.

•One can install a retort for fuel gasification into the bell.

•A retort represents a closed metal vessel, into which fuel is charged.

• A process of combustion product extraction from fuel in retorts with external heating without access of air is called dry distillation.

The calorific value of dry distillation gases is higher than producer gas obtained in the devices with internal heat carrier. This is high quality gas.

While heating fuel without access of air steam and gases are extracted,which are called volatile part of fuel, and solid, rich in carbon residue remains, which is called coke (for wood this is charcoal). Coke is carbon.

The gas produced and coke can be burnt or used for other purposes.

www.stove.ru

We will dwell on production and combustion of gas received during pyrolysis of fire-wood, production of coke and a possibility of its combustion.

Coke is produced in charcoal burning plants, burning the gas produced.

It is possible to burn the gas produced and coke completely receiving heat (in gas plant)or other products.

The difference between the charcoal burning plant and gas-generating boiler is that in the first case only produced gases are burnt while in the second case everything is burnt.

An important coke property for gasification is its reactivity (activity), i.е. capability to interact with oxygen, carbon dioxide and water vapor. When water vapor acts with burning hot coke the following reaction takes place between it and carbon in gasification zone: С + Н2О = СО+Н2; and С + 2Н2О = СО2 + 2Н2. For both reactions the heat is used; for the first reaction more heat is used than for the second.

In the first reaction only fuel gases are produced (50%СО and 50% Н2). The calorific value of mixture of these gases is 2802 kcal/Nm3.

www.stove.ru

In the result of the second reaction partly fuel gases and partly non-inflammable gases are produced (33,3% СО2 and 66,7% Н2). The calorific value of mixture of these gases is 1714 kcal/Nm3.

When the temperature is higher the first reaction in gas generator is more intensive. At lower temperatures-the second.

I suggest three formulae of design of charcoal burning plants and gas generating heat-generators in the system of free gas movement. These formulae can be used both for design of charcoal plants and for gas-generating heat-generators.

It shall be pointed out that the above-mentioned formulae are my priority application for an invention of method for creation of energy plants. Anyone who wants to use the result of this work shall acquire the right for doing so and pay the required amount to the international fund.

The fund shall be controlled and distribution of money shall be carried out under the supervision of an international organization: the money is to be be used for the development of a system of free gas movement.

The main task of those people who will get the money from the fund is to make the results of their work accessible to other people.

www.stove.ru

1. «The plant consists of a number of bell-type furnaces, each of them being surrounded by heat-accumulating bell, which in their lower level contain free gates to connect them with each other through heat-accumulating bell. The upper part incorporates channels for interconnection of the bell-type furnaces with heat-accumulating bell. The channels are provided with gates.

Each of the bell furnaces contains a retort or another device, for example, a heat exchanger).

The adjustment of heating temperature of retort and burning power is carried out due to redistribution of the flow ways:

of hot gases;

or steam and gas.

Burning of steam and gas takes place both in:

the bell-type furnace;

and in heat-accumulating bell.

www.stove.ru

www.stove.ru

2. «The lower level of gas-generating heat-generator consists of a firebox and a number of bells combined through the firebox to form a single space.

Each of the bells is combined with the firebox by means of dry joint and an opening in the upper part and is provided with its own exit in the lower part into the pipe, the next bell or smoke chamber.

Each of the bells contains a retort or another device, e.g. a heat exchanger.

Using our system it is easy to create a large number of preassembled, various purpose energy plants using standard structures.

Below is an example showing the use of unified firebox made of heat-resistant concrete or fire clay in gas-generating plant.

www.stove.ru

The degree of retort heating and combustion power adjustment is carried out due to redistribution of flow ways of hot gases. The combustion of steam and gas takes place only in the firebox (combustion chamber).

Damper adjustment

FuelHeat through dry joint

Heat through dry joint

Heat exchanger

Steam and gas

Ballast gases

Retort for fuel pyrolysis Retort cap Furnace bell

Heat exchanger cap

www.stove.ru

Two plants operating according to formula 2

www.stove.ru

3. «The plant consists of firebox installed in the bell and combined with it to form a single space by means of dry joint according to the formula “The lower level and the firebox are combined to form a single space creating a lower bell" (this is heat-generator), and a number of secondary bells. Each secondary bell and heat-generator are interconnected through the opening in the lower part. The secondary bell in the lower part is provided with an opening to its own pipe or to the common pipe through the smoke chamber».

Each of the secondary bells contains a retort (or other device, e.g.a heat exchanger). The degree of retort heating and combustion power adjustment is carried out due to redistribution of flow ways of hot gases. The combustion of steam and gas takes place only in the firebox of heat-generator.

Adjustment damper

Fuel Heat exchanger

Heat exchanger cap

Steam and gas

Ballast gases

1-Retort for pyrolysis;2-Retort cap;3-Furnace bell;

4-Heat exchanger cap

www.stove.ru

Each bell, secondary bell or bell-type furnace can contain a heat exchanger in the form of water boiler heating elements, air heater, retort for fuel pyrolysis, process materials, equipment, device, etc.

At present solid fuel combustion all over the world takes place in two

stages :

1. Expensive and power-consuming stage for production of pellets, brick fuel, etc.

2. Pellet combustion from the point of view of automation, is organized at the level of gas and diesel fuel combustion.

In the system of free gas movement while creating gas-generating plants according to any of the above formulas it is possible to use wet fuel because its drying is performed due to the heat of effluent gases, moreover, in adjustable mode.

Thus expensive and power-consuming stage of fuel preparation is excluded.

Combustion power adjustment in this case takes place without efficiency reduction.

www.stove.ru

The system of free gas movement provides a possibility of creating a mechanism of vacuum drying of fuel due to the heat of effluent gases. The content, features and steam and gas output depends on fuel heating speed and temperature. • While heating at low temperatures that is revealed at the initial stage of

pyrolisys; steam and gas is, per se, a heterogeneous mixture, which does dot really allow for optimal fuel combustion.

• It should be also noted that at temperatures below 150 ° C water vapors are extracted from the retort and can extinguish the flare.

The system of free gas movement provides a possibility of bringing the steam and gas obtained at low-temperature pyrolysis to molecular level and prepare for efficient combustion due to heating in high-temperature oxygen-free medium.

• The main purpose of the above presentation is to show not only theoretic advantages of heating plants designed on the principle of FGM but also to invite businessmen and organizations that have financial and intellectual possibilities for organizing an “energy center” for implementation the above given ideas into world

economy. 16.12.2007 © Igor Kuznetsov "Kuznetsov's stoves"

I.V. Kuznetsov. tel. 7(343)332-94-90 e-mail: igor@stove.ru; http://stove.ru

620042 Ekaterinburg, Russia

Pobedy str., 51-87

www.stove.ru

References:1. Под редакцией Г.Ф. Кнорре, «Введение в теорию топочных процессов», М

1968 г;2. Д.Б. Гинзбург. Газификация твердого топлива. Госстройиздат, 1958 г.3. А.Н. Кислицин. «Пиролиз древесины: химизм, кинетика, продукты, новые

процессы». Москва. Лесная промышленность 1990 г; 4. Э.Д. Левин, Теоретические основы производства древесного угля. 1980 г.

Лесная промышленность, Москва; 5. Ю.Д. Юдкевич, С.Н. Васильев, В.И. Ягодин. Получение химических

продуктов из древесных отходов. С.-Петербург 2002 г; 6. «Fuel combustion and optimal use …» http://www.stove.ru/index.php?

lng=0&rs=168 ;7. New system of fuel combustion and its application. http://stove.ru/index.php?

lng=0&rs=173 ;8. «Gas plant boilers …» http://www.stove.ru/index.php?lng=0&rs=126 ;9. «Charcoal burning units in the system of free gas movement»

http://www.stove.ru/index.php?lng=0&rs=124 ;10.«Once again about the system …» http://www.stove.ru/index.php?

lng=0&rs=16 ;11.«Pyrolysis of biofuel in the bell and combustion of its products in the system of

free gas movement» http://www.stove.ru/index.php?lng=0&rs=116