FR2482702A1 - SOLID FUEL STOVE HAVING TWO THERMALLY INSULATED COMBUSTION CHAMBERS - Google Patents

Abstract

THE INVENTION CONCERNS AN PERFECTED STOVE. IN THIS STOVE FOR THE COMBUSTION OF A SOLID FUEL INCLUDING A PRIMARY COMBUSTION CHAMBER 1 AND A SECONDARY COMBUSTION CHAMBER 6 WITH SEPARATE AIR SUPPLIES, THE TWO CHAMBERS 1, 6 ARE THERMALLY INSULATED IN SUCH AS THE SECONDARY CHAMBER IS INSULATED AS THE PRIMARY CHAMBER, THE SECONDARY CHAMBER BEING DESIGNED AS A TWO-STOREY CHAMBER ALLOWING COMPLETE COMBUSTION OF THE FUEL OVER AN EXTENDED ENERGY DISSIPATION RANGE; A HEAT EXCHANGE SURFACE 9 BETWEEN A DUCT 8 FOR SUPPLYING SECONDARY AIR AND AN OUTLET DUCT 10 FOR HOT COMBUSTION GAS FROM SECONDARY CHAMBER 6 ALLOWS PREHEATING OF THE COMBUSTION AIR LEADING TO THE LATTER . APPLICATION ESPECIALLY TO DOMESTIC HEATING STOVES OPERATING WITH WOOD, COKE OR COAL.

Description

The present invention relates to perfected stoves

  for the combustion of a solid fuel such as

  for example, wood, coke, coal, etc. of the type com

  carrying a primary combustion chamber and a secondary combustion chamber, both of which have

  separate power supplies for combustion air.

  Tests have been carried out with previously known stoves of this type to achieve a post-combustion of incompletely burned gas by supply of secondary air to

  these gases inside the combustion chamber. How-

  tests have shown that the desired effect is very rarely obtained in small stoves and that, in the case

  o this result is obtained, this is due to specific conditions

particularly advantageous.

  Given the signs of a future energy shortage,

  Recently, there has been a growing interest in the use of forest products as a source of home heating. Then there will be a demand in the field

  stoves which, without causing environmental pollution,

  will be able to burn forest products and similar fuels with the highest

  possible and the best possible rate of controlled combustion

  EEA. A characteristic of this type of stoves is that the fuel undergoes incomplete (pyrolytic) combustion at a relatively low temperature in a

  primary room. During this process, disgazed

  Makes (pyrolytic gases) are released with a flow rate that depends on the temperature and the form and the composition of the fuel. The temperature in the primary chamber depends on the rate of combustion, which occurs there, and by

  of the primary air supply and the isolation

  temperature of the primary chamber. Total dissipation

  potential energy will therefore be the sum of

  Tensity of primary combustion and calorific value of pyrolytic gases Controlled dissipation of energy requires at all times adjustment of the amount of primary air and isolation of the primary chamber by

  function of the fuel that is used.

  In order to guarantee a complete combustion of the pyrolytic gases and thus to obtain a high efficiency, it will be necessary to supply secondary air to the gases under conditions controlled from the point of view of its quantity, temperature and temperature. residence time. Combustion can be effective in a room

  separate secondary system with appropriate thermal insulation.

  required and an adequate supply of air.

  That is why the object of the present invention is

  to provide a stove for the combustion of

  solid, in which the combustion is carried out in two stages, namely in the first place in a primary chamber

  and then in a secondary chamber, in a way that

  putting a high efficiency for the stove, said

  stove to be further designed in such a way as to obtain a

controlled busting.

  According to the present invention, this problem

  is solved by means of an improved stove of the type mentioned

  born earlier, which is characterized by the fact that both chambers are thermally insulated in such a way

  the production of pyrolytic gases in the primary chamber

  mayor takes place in a predetermined space, and that the

  temperature inside the secondary chamber is suf-

  elevated to cause complete combustion of all pyrolytic gases. Usually the highest temperature is required in the secondary chamber and this suggests the achievement of better thermal insulation

  for this room only for the primary room.

  Another feature of the present invention is that the secondary chamber is designed as a two-stage combustion chamber. The size of an optimal secondary chamber will depend on the energy dissipation of the stove. A secondary chamber to

  two stages will thus ensure good secondary combustion.

  on a wide range of adjustment, as combustion will occur with low energy dissipation in the first stage and combustion will be completed with greater dissipation in the

second floor.

  Another feature of the present invention is to provide a heat exchange surface between an intake duct for secondary air and an outlet duct for the hot combustion gases from the secondary chamber, in order to preheat of

  the combustion air admitted into the secondary chamber.

  Another feature of the present invention

  lies in the fact that the secondary air duct

  in the space between the primary chamber and the

secondary bedroom.

  A preferred embodiment of the invention

  characterized by the fact that the secondary air duct

  is located in the separation wall between the primary chamber and the secondary chamber and that this passage is

  isolated from the primary chamber and has a safe

  heat exchange face towards the chamber.

  dary. This results in a preheating of the secondary air.

  Another feature of the present invention resides in the fact that a heat source is located in the secondary chamber or in the air supply duct leading to the secondary chamber, said source of

  heat is fed by external energy and can

  for example to be constituted by a heating device

  electric fage. The energy dissipated by this source of heat

  may be ordered in accordance with this

  (a) by the temperature inside the secondary chamber, or (b) by the rise in temperature in the secondary chamber, or

  (c) the temperature present in the secondary chamber;

daire, or

  d) a combination of parameters (a, b, c).

  In order to reduce the ignition temperature of the gases in the secondary chamber, it is provided according to a feature of the present invention that the secondary chamber

  can be provided with a catalyst. A variant of this characteristic

  is that the secondary chamber is equi-

  of plates, rods, or similar devices

  of great thermal inertia so that

  combustion gases will be easier to

  only with a free gas atmosphere.

  In order to safely obtain a combustion process

  self-controlled with a high efficiency in all cases, regardless of fuel type or shape or

  varying conditions of airflow, according to a specific

  of the present invention, it is possible to pre-

  see a fan to ensure a power supply

  Uniform air for combustion. According to a trained person

  advantage, the fan is driven by an orga-

  no thermoelectric disposed on one of the walls in one

  combustion chambers, preferably the secondary chamber

  dary. The fan can be controlled by a thermosat.

  Hereinafter will be described the present invention with reference to the single figure showing a diagram of a

  embodiment of the present invention.

  The stove shown as an example consists of

  of a primary chamber 1 in which at least the upper wall

  2 is isolated. However it is possible to isolate

  also the side walls if this provi-

  It would be necessary to increase the temperature in the primary chamber, when it is desired to obtain a predetermined rate of combustion. The combustion air brought to the

  primary chamber 1 is introduced through openings of

  air 4 in the front part of the stove.

  The combustion gases from the primary chamber are brought into the interior of the secondary chamber 6 via an opening 5 formed in the rear wall 3. This chamber is constituted as a two-stage chamber , in which the combustion takes place in stage 1 when the energy dissipation is low while it is completed in stage 2

  when the energy dissipation is high. The air of com

  The bustion brought to the secondary chamber is dragged into the

  of the latter through an air flow opening 7 formed in the front part of the stove, towards a duct * 8 in the upper wall.

  of the primary chamber 2. The supply of combustion air

  is adjusted so that the primary air and the air se-

  are controlled or controlled simultaneously. The duct 8 is isolated relative to the primary chamber, as shown in the figure, but is equipped

  a heat exchange surface 9 with the discharge duct

  tie 10 from the secondary chamber. The secondary chamber

  Daire has a good thermal insulation, so that in this room are obtained sufficiently high temperatures (750-10000C). In order to be sure that it will happen

  ignition with complete combustion of the combustion gases

  in the secondary chamber, that is to say that the temperature

  will be higher than the ignition temperature for gases, it is possible to use a heating device

  12 having an external source of energy supply

  ogy. The heater 12 may be an electric heater as in the embodiment shown, or it may be an oil burner, a gas burner, and the like. The heater may be located in the supply duct 8 for air

  secondary, instead of being placed in the secondary chamber

  daire proper. As mentioned above,

  the secondary chamber may have a surface

  catalytic material, for example a platinum or rhodium

  dium, so as to reduce the ignition temperature of the combustion gases. The secondary chamber may also be equipped with plates, rods or similar devices having a certain thermal inertia, so that the ignition of the combustion gases will be carried out more easily than in a free gas atmosphere. Note that he is

  possible to use separately or in combination a

  heating system, a catalyst, rods or

similar characteristics.

  The hot gases from the secondary chamber 6 are conveyed in the outlet duct 10, are returned

  at the front edge of the upper wall 11 and

  slow in a conduit 13 above the upper

  11 from the duct 10 to the chimney, the flue gases dissipate as much heat as possible and the duct 13 is therefore equipped with a heat exchanger. heat allowing the transfer of heat

to the environment.

  The chimney 14 can be equipped with a fan

  15 that could be powered by an electric current pro-

  from a thermocouple 16 located on the surface of the hot wall of the conduit 13. The thermocouple will produce an electric current depending on the temperature difference between

  the warm side of the wall and the environment. The ventilation

  15 can be controlled by a thermostat so that

  the supply of combustion air is carried out according to

  a desired temperature of the room. The start

  a cold stove can be done using a bat-

  since the thermocouple does not provide

  no current or that we can not use the

  natural air circulation in the chimney.

  The external supply of energy to the secondary chamber

  re is not required permanently. To carry out the command

  From this power supply, the following parameters should be taken into account: a) the temperature in the secondary chamber. If this temperature falls below 800C, external energy input is required if flue gases still flow from the primary chamber. One could then provide a temperature sensor in the secondary chamber. b) Increase in temperature between the entrance

  and the output of the secondary combustion zone. A variety

  their positive, not due to the energy input, indicates that

  flue gases to be burned still flow.

  c) The temperature in the primary chamber. A

  low limit value indicates that the stove no longer contains.

  of fuel and therefore an external input

energy is not necessary.

  By combining these parameters for example in the form of signals. from thermocouples, thermistors or similar devices, it is

  possible to achieve fully automatic combustion

  that and complete with all flammable gases.

Claims (13)

  1. Advanced stove for the combustion of a solid fuel such as for example wood, coke, coal, etc., -type having a primary combustion chamber (1) and a secondary combustion chamber (2), both of which have separate power supplies   in combustion air, characterized in that the two chambers   (1, 6) are thermally isolated, preferably in such a way that the secondary chamber is better   thermally insulated as the primary chamber.   2. Stove according to claim 1, characterized in that the secondary chamber (6) is designed as a two-stage chamber to obtain a complete combustion in a wide range of dissipation energy.   3. Stove according to claims 1 and 2 taken   as a whole, characterized in that there is provision for   heat exchange surface (9) between an intake duct   secondary air (8) and an outlet duct (10)   hot combustion gases from the secondary chamber   (6) to preheat the air   combustion leading to the secondary chamber (6).   4. Stove according to claims 1 to 3 taken in   together, characterized in that the conduit (8) of   from the air to the secondary chamber (6) opens into the space (5) between the primary chamber (1) and the secondary bedroom (6).   5. Stove according to any one of the claims   * 1 to 4, characterized in that the air duct (8) bringing the air to the secondary chamber (6) -is provided with a partition wall (2) disposed between the primary chamber (1), the   secondary chamber (6) and the exit (10) of the chamber se-   condenser and has a heat exchange surface with the exit (10).   Stove according to one of the claims   i to 5, characterized in that the volume, insulation and 24827Z02   the supply of combustion air to the primary chamber (1) is dimensioned to provide a uniform combustion rate and pyrolysis to produce a properly adapted quantity of unburned gases, and in particular that CO is sent to the secondary chamber (6).   7. Stove according to any one of the claims   1 to 6, characterized in that the volume, the insulation and the supply of secondary air to the secondary chamber (6) are   sized to achieve ignition of the fuel   complete pyrolytic gas.   8. Stove according to any one of the claims   1 to 7, characterized in that the secondary chamber (6) or the duct (8) for supplying secondary air is equipped with a heat source (12) comprising a supply of external energy.   9. Stove according to any one of the claims   1 to 8, characterized in that the secondary chamber (6) is equipped with a catalyst so that the temperature of   the ignition of the gases in this chamber is reduced.   10. Stove according to any one of the claims   1 to 9, characterized in that the secondary chamber (6) is equipped with plates, rods, or similar devices   possessing some thermal inertia so that the allu-   burning of combustion gases is easier   only with a free gas atmosphere.   11. Stove according to any one of the claims   1 to 10, characterized in that a fan (15) is provided to ensure a uniform supply of air to the combustion   in order to obtain a controlled combustion.   12. Stove according to claim 11, characterized in that the fan (15) is controlled by a thermocouple (16) provided on one of the walls in one of the chambers of   combustion or at the outlet of the secondary chamber re (6).   13. Stove according to claim 8, characterized in that the heat source (12) is controlled by:   a) the temperature present in the secondary chamber   (6) or (b) the increase of the temperature in the secondary chamber (6) or (c) the temperature present in the primary chamber (1) or (d) a combination of the parameters (a, b, c) indicated below. above.