•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.
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•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
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The basic idea of the FGM system that was formulated by Grum Grzhimailo is as
follows:
•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
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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.
•Bell essentially is a glass or a cavity turned
upside down where hot gases are floating up
while pushing cooler ones down.
•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.
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Essence of the formula
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.
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The essence of the conception
Double bell
•To extract maximum amount of heat possible
with combustion of the corresponding fuel
(highest combustion efficiency)
•Utilize maximum of the extracted
(maximum heat transfer efficiency);
heat
•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) .
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The essence of the conception
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.
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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.
Heat-accumulating
bell
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.
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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.
Heataccumulating bell
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.
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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.
Heat-accumulating
bell
•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%.
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•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.
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•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.
Heat-accumulating
bell
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.
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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.
Heat-accumulating
bell
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.
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•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.
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•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.
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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.
•There are four known conditions that facilitate
complete combustion:
•Proper design of the firebox;
•Proper mixing of gases;
•High temperature;
•Optimal supply
combustion air.
of
primary
and
secondary
•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.
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•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.
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•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.
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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” .
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•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.
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•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.
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•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.
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•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.
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•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.
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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. .
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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 factorymade 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.
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We insert into space above the catalyst3:
•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.
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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.
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• 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.
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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.
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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 heatgenerators.
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.
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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.
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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.
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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
Fuel
Heat 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
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Two plants operating according to formula 2
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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».
Adjustment damper
Fuel
Heat
exchanger
Heat
exchanger
cap
Steam
and
gas
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.
Ballast
gases
1-Retort for pyrolysis;2-Retort cap;3-Furnace bell;
4-Heat exchanger cap
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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.
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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 hightemperature oxygen-free medium.
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• 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: [email protected];
http://stove.ru
620042 Ekaterinburg, Russia
Pobedy str., 51-87
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
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