Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
  • F24H1/22—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating
  • F24H1/34—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water chamber arranged adjacent to the combustion chamber or chambers, e.g. above or at side
  • F24H1/36—Water heaters other than continuous-flow or water-storage heaters, e.g. water heaters for central heating with water chamber arranged adjacent to the combustion chamber or chambers, e.g. above or at side the water chamber including one or more fire tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
  • F23B1/00—Combustion apparatus using only lump fuel
  • F23B1/30—Combustion apparatus using only lump fuel characterised by the form of combustion chamber
  • F23B1/36—Combustion apparatus using only lump fuel characterised by the form of combustion chamber shaft-type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23K—FEEDING FUEL TO COMBUSTION APPARATUS
  • F23K3/00—Feeding or distributing of lump or pulverulent fuel to combustion apparatus
  • F23K3/16—Over-feed arrangements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/06—Regulating fuel supply conjointly with draught
  • F23N1/065—Regulating fuel supply conjointly with draught using electrical or electromechanical means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/04—Measuring pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2233/00—Ventilators
  • F23N2233/02—Ventilators in stacks
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2239/00—Fuels
  • F23N2239/02—Solid fuels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H2230/00—Solid fuel fired boiler

Definitions

• the invention is in the field of heating techniques, and it relates to a boiler with continuous supply of divided solid fuel.
• Boilers are known comprising two superimposed stages, one lower housing a combustion chamber and the other upper housing a heat exchanger. An access is provided in the combustion chamber for the supply of solid fuel, in particular wood.
• solid fuel in particular wood.
• a problem with these boilers is that they do not allow a continuous supply of fuel to the combustion chamber. Indeed, the fuel is supplied by the loading door, which remains closed during combustion so as not to induce disturbing air circulation; it is recalled that in general, the modes of air circulation in the combustion chambers are essential for the maintenance of combustion, and therefore constitutes a problem to be solved in the case of a continuous supply of solid fuel.
• the object of the invention is to provide a boiler with continuous supply of divided solid fuel, which offers a high efficiency and a reliable control of the combustion and of the composition of the fumes, the operation of which is carried out naturally in complete safety, and which is of a simple structure, and therefore of a competitive cost price, both with respect to devices of this type and to those using a fuel of another nature.
• a boiler with continuous supply of divided solid fuel is generally characterized in that it is mainly composed of two superposed stages, one of which is lower, in which is located a tubular combustion chamber with vertical extension in which lead to fuel supply means, and of which another superior, in which are located an exchanger and a smoke evacuation duct, the two stages communicating via a nozzle for the escape of the flames out from the combustion chamber to the exchanger, under the effect of means of air circulation, said primary, from the base of the combustion chamber and axially through its interior space, towards the smoke evacuation duct.
• the abovementioned organization of the boiler has the result of offering a high efficiency, due to the optimization of the combustion and the removal of the heat produced, optimization obtained by means of upward ventilation from the base of the combustion chamber.
• upward ventilation means comprising in particular the organization of the boiler in two superposed stages communicating by a nozzle for escaping flames from combustion, and the tubular configuration of the combustion chamber which is arranged vertically.
• the air circulation means are means for depressurizing the upper and lower stages from downstream of the upper stage.
• the combustion chamber is preferably arranged in a primary air intake chamber, its base opening into the latter, inside which intake chamber is introduced in a controlled manner the primary air from outside the boiler, prior to its introduction into the combustion chamber.
• Such arrangements during operation of the boiler, constitute means of preheating, in contact with the external wall of the combustion chamber, of the primary air introduced into the intake chamber prior to its introduction into the combustion chamber.
• the boiler is equipped with means for self-regulating its operation, said means comprising: a) means for selection by the user of at least one set temperature at the outlet of the exchanger , and thermostatic means for controlling the starting and stopping of the means for putting under vacuum, respectively below and above the threshold of the, or of the so-called set temperatures, and b) a vacuum switch for measuring the vacuum inside the air intake chamber, and to control the starting and stopping of the fuel supply means of the combustion chamber, respectively above and below a determined threshold of said depression, determined and preset threshold as a function of the maximum tolerated pressure losses resulting from the resistance offered by the fuel present in the combustion chamber against the introduction of the primary air in the latter, and therefore determined and preset according to the maximum amount of fuel tolerated in the combustion chamber.
• the fuel supply means are also placed under the dependence of timing means, to compensate by successive short on-off cycles for the reaction times of the boiler to abrupt variations in combustion and pressure ( depression) inside the combustion chamber, resulting from a fuel supply in the latter.
• the latter further comprises means of air intake, called secondary, inside the combustion chamber through at least one radial orifice formed at its top and opening out at the base of the nozzle, and means for adjusting the quantity of secondary air admitted for adjusting the composition of the fumes, and therefore the pollution levels of the fumes discharged from the boiler.
• the nozzle opens into the upper stage in a combustion pot which constitutes a means for causing a fallout of the ashes and solid particles not consumed in the nozzle and prohibiting dispersion in the upper floor of ash and unburned particles, in particular to limit fouling of the upper floor.
• the upper floor is advantageously provided at its top with an access door to
• the exchanger then to the combustion chamber through the nozzle, to facilitate maintenance of the boiler and in particular cleaning of the exchanger.
• the exchanger is for example generally formed of a double-walled cylinder disposed around the combustion pot, between which walls extend axially to the exchanger a plurality of tubes for the circulation of smoke, the cylinder being provided with its top of a refractory cover overhanging the burn pot to send back to the nozzle the flames that escape, the heads and unburnt particles.
• the tubes are advantageously provided internally with helical cores intended to force the passage of smoke along the wall of the tubes, and therefore to promote heat exchange.
• the said screw passes through the wall of the combustion chamber to open, at one of its ends, at the in the vicinity of the top of the latter, the other end being intended to communicate with the outlet of a silo containing a reserve of divided solid fuel.
• the outlet of the silo is preferably closed off by means of additional division of the fragmented fuel which it contains, so that only materials whose dimensions do not exceed a determined threshold are admitted into the supply screw.
• Said means of dividing the fuel are for example constituted by a plate closing the outlet of the silo provided with a passage for materials, and by a disc driven in rotation superimposed on the plate and itself provided with a material passing light, so that too much material long are sheared between the rotating disc and the plate when they fall out of the silo.
• the silo is provided with a centrifugal arm for stirring the fuel that it contains and for supplying the fuel from the walls of the silo to its outlet.
• FIGS. 2 and 3 are diagrammatic representations in perspective, respectively in exploded and assembled view, of the members equipping the outlet of a silo for the supply of fuel to a boiler of the invention.
• Fig.4 is a sectional illustration of an improved embodiment of a boiler such as that shown in Fig.l.
• a boiler In fig.l, a boiler is supplied with solid fuel divided out by means of an endless screw 2 connected to a silo 4.
• the boiler generally consists of an upper stage 6 in which is disposed a water exchanger 8, and a lower stage 10 in which is disposed a vertical tubular combustion chamber 12 inside which opens the worm 2.
• the two stages 6 and 10 communicate with each other by means of a nozzle 14 through which the flames escape from the combustion chamber 12 towards the exchanger 8.
• the combustion is maintained by an ascending stream of primary air taken from outside the boiler, which first circulates in a primary air intake chamber 16 surrounding the combustion 12, then axially through the latter 12 from its base towards the nozzle 14, and in a second step, in the form of flue gases, through the tubes 18 for heating the exchanger 8 towards a duct 20 for discharging the fumes out of the boiler.
• the primary air circulation is obtained by means 22, such as a turbine, generating a vacuum inside the upper 6 and lower 10 stages, the said means 22 being located downstream of the upper stage 6 for create an air intake through the nozzle 14, through the combustion chamber 12 from its base, and through the primary air intake chamber 16 from the outside of the boiler.
• means 22 such as a turbine
• the boiler is self-regulated by means of monitoring and controlling its operation: the user has means 72 for selecting a set temperature of the water in the exchanger 8 measured by thermostatic means 70. In the if the water temperature is lower than the set temperature, the thermostatic means 70 control the starting of the turbine 22.
• a vacuum switch 24 controls, depending on the vacuum prevailing in the primary air intake chamber 16, the implementation of the means 2 for supplying fuel to the combustion chamber 12, in the case where said vacuum is greater than a determined and preset threshold. When the vacuum reaches said threshold, the vacuum switch 24 controls the stopping of the fuel supply means 2. When the temperature of the water in the exchanger 8 is reached and / or is higher than the set temperature, the thermostatic means 70 control the stopping of the means 22 for placing under vacuum. Stopping the primary air intake, and therefore the absence of vacuum in the chamber 16 measured by the vacuum switch 24, induces the latter 24 to stop the supply means 2.
• the nozzle 14 opens into a combustion pot 28 and is overhung by a cover 30 of refractory material resting on the exchanger 8, to cause a fall of the ash and unconsumed solid particles in the nozzle 14.
• the opening of the valve 38 for primary air intake inside the intake chamber 16 is placed under the dependence of an electromagnet 74, the implementation of which is controlled by the said thermostatic means 70 simultaneously with that of the means 22 generating vacuum.
• the valve 38 is shaped as an air inlet airlock, one of the openings of which is closed by a first flap 76, for pre-setting the maximum quantity d admissible air inside the boiler, and the other opening of which is closed by a second flap 78 which can be operated by said electromagnet 74.
• the latter 74 constitutes a means for firmly holding the second flap 78 in the position of opening, in order to avoid variations in the admitted air flow which would result from instability and oscillations of the flap 78 in the open position under the effect of turbulence, which would affect control of the composition of the fumes discharged from the boiler.
• the outlet of the vacuum switch 24 is arranged inside the airlock 38, in order to obtain a certain shutdown of the means 2 for supplying fuel in the event of failure of the electromagnet 74, and therefore in case da inoportune closure of the second flap 78 under the effect of its own weight, while the depression means 22 are active.
• the stages 6 and 10 comprise a respective enclosure each formed by a box 42 and 44, the boxes 42 and 44 being assembled to one another, by bolting 46 in particular.
• the combustion chamber 12 consists of a rolled sheet 48 inside which is molded a refractory lining 50, said sheet 48 then being welded to the upper wall of the box 44 of the lower stage 10, so as to be supported by the latter in suspension and therefore clear the opening of the base of the combustion chamber 12 to allow the passage of primary air. Equivalently but nonetheless not preferred, the combustion chamber 12 could rest on the bottom of the lower box 44 by means of a base forming at the base of the combustion chamber 12 sufficient clearance for primary air circulation.
• the outlet of the silo is closed by a plate 56 provided with a light 58 for the passage of materials, and by a disc 60 superimposed on the plate 56 and connected to means 64 of rotational drive, disc 60 itself provided with the same lumen 58, so that the materials can be admitted into the worm 2 only on condition that their parcelling is sufficient.
• a centrifugal arm 66 connected to means 64 for driving in rotation is provided for driving the materials contained in the silo 4 towards its outlet. This arm 66, crenellated and driven in rotation on itself, rolls on a ring gear 68 equipping the silo 4 around the axis of the latter.
• the tubular combustion chamber 12 delimits an interior volume which is preferably conical, in particular in order to obtain a fall of the fuel in its axial zone rather than along its wall, thanks to which the fuel is naturally distributed at the base of the combustion chamber 12. It will also be noted that thanks to these provisions, the combustion chamber 12 is all the more robust, which is preferable insofar as it where it participates in support of the burn pot 28. According to the improvements shown in fig.4, the boiler of the invention is further equipped with an automatic ignition device, comprising means 80,82,84,86 for drawing a stream of hot air, such as at a temperature between 480 ° C and 520 ⁇ C, at the base of the combustion chamber 12.
• This device comprises means 80 for taking the air outside the boiler and circulating it through a resistance 82 for heating, then through a conduit 86 to the base of the combustion chamber.
• the implementation of the pulsing means 80 is placed under the dependence of timing means 84, so that the burning air is spontaneously maintained drawn from the base of the combustion chamber for a predetermined period, from 1 to 5 minutes per example, when switching on the boiler.
• the blower 80, air heating 82, and timer 84 means are disposed away from the combustion chamber, and even preferably outside the boiler, thanks to what the said means do not require special arrangements to preserve them from the heat of the hearth, and finally thanks to which their manufacturing cost is reduced.
• the boiler of the invention is preferably equipped with means for de-ashing the base of the combustion chamber 12, in order to avoid engorgement which is detrimental to the free circulation of air through the combustion chamber 12.
• These means include a squeegee 92 animated by a back and forth movement (arrow 1) for dropping the ashes in a tank 88, disposed at the base of the boiler, through ports 90 for communication between the ash tank 88 and the chamber air intake 16, said lights 90 opening in the vicinity of the periphery of the combustion chamber 12.
• the movement of the squeegee 92 can be generated, either manually by the user at his discretion, or and preferably regularly by means of motors 94, by means of a pinion comprising a rack 96 fitted to the squeegee 92.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Solid-Fuel Combustion (AREA)
• Fluidized-Bed Combustion And Resonant Combustion (AREA)

Applications Claiming Priority (3)

Publications (2)

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Family Applications (1)

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• 1996
  • 1996-02-20 FR FR9602307A patent/FR2745072B1/fr not_active Expired - Fee Related
• 1997
  • 1997-02-14 DE DE69703875T patent/DE69703875T2/de not_active Expired - Lifetime
  • 1997-02-14 ES ES97905203T patent/ES2154892T3/es not_active Expired - Lifetime
  • 1997-02-14 AT AT97905203T patent/ATE198659T1/de active
  • 1997-02-14 EP EP97905203A patent/EP0882201B1/de not_active Expired - Lifetime
  • 1997-02-14 WO PCT/FR1997/000280 patent/WO1997031224A1/fr not_active Ceased

Non-Patent Citations (1)

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