WO2016062317A1

WO2016062317A1 - Multi-purpose furnace system

Info

Publication number: WO2016062317A1
Application number: PCT/DK2015/050295
Authority: WO
Inventors: Tonny Sander Holm
Original assignee: Proces Sander Aps
Priority date: 2014-10-22
Filing date: 2015-09-30
Publication date: 2016-04-28
Also published as: EP3209942A1

Abstract

A multi-purpose furnace system comprising a furnace (35), an inflow channel (30),an outflow channel (31) an outflow pipe (34), a primary combustion chamber (29) and a secondary combustion chamber (19), a ventilator or blower (13) for providing combustion air being preheated by an exit gas chamber (32) of the outflow pipe to the furnace, a construction (14) and a housing (36), an access device (15) and a door or hatch (37) for receiving and removal of residual or waste products, a primary opening or damper (12) for regulating primary combustion air to the primary combustion chamber and a secondary opening or damper (11) for regulating secondary combustion air to the secondary and/or primary combustion chamber,a heat storage chamber (4) and at least one air channel (5), a heat transferring chamber (20) and a heat transferring element (25) for transferring heat to the heat transferring chamber, a valve or opening (8) for allowing exit gas to flow from the primary and secondary combustion chambers into the heat transferring chamber, a resistance spiral unit (24) providing a resistance to exit gases flowing through the at least one outflow channel and at least one unit (9, 10) arranged in a heat transferring relationship with the at least one outflow channel such as to utilize the heat transferred to the heat transferring chamber.

Description

Multi-purpose furnace system

The present invention relates to a multi-purpose furnace system ac- cording to the introductory part of claim 1 .

As used in the below as well as in the claims, the word "furnace" is intended to refer to the combustion chamber of any of the various above- mentioned furnace system types.

Likewise as used herein, including in the claims, the word "furnace system" is intended to refer to such a furnace and an associated outflow pipe or chimney in combination, and in particular to such furnace systems being of the type used as wood burners, wood burning stoves, open fireplaces, furnaces, stoves or heaths for burning wood, smaller furnaces or boilers for bio- mass fuel or wood pellets, furnaces burning oil, coal or coke, and like furnace systems and most particularly such furnace systems for use in smaller scale domestic applications.

It is well known that commonly known types of furnace systems have relatively low efficiencies due to at least the following two factors. Firstly, a large amount of the heat produced in commonly known types of furnace sys- terns escape to the exterior through the outflow pipe or chimney associated with the system and is thus never put to use in the building in which the furnace system is installed. Secondly, the combustion of at least some types of fuel in commonly known types of furnace systems is rather inefficient. Consequently the commonly known types of furnace systems use relatively large amounts of fuel and are thus relatively expensive in use, and furthermore emit rather large amounts of particles to the surroundings and are thus polluting.

DE 42 04 163 A1 describes an attempt at solving the above problems in the form of a furnace system comprising a primary combustion chamber, a secondary combustion chamber, a drawer with an associated space for collecting ashes, a door providing access to the primary combustion chamber, a primary air supply via a grate being openable and closeable by means of a control disc, a secondary air supply via a channel and openings in a wall of the furnace system, a ring channel with openings for extra supply of air to the primary combustion chamber, an opening between the two combustion chambers, an opening from the secondary combustion chamber to an outlet channel leading to a smoke outlet pipe, a heat exchanger with smoke guide plates arranged in the outlet channel in a distance from the secondary combustion chamber and isolating plates arranged between the channel of the secondary air supply and the combustion chambers.

There is, however, still a demand and desire for providing a new and/or alternative multi-purpose furnace system with a higher or even considerably higher efficiency as compared to commonly known and thoroughly tested furnace systems both with regard to the combustion process and the exploitation of the heat generated. Furthermore, there is a demand and desire for providing a multi-purpose furnace system with mechanical improvements enabling e.g. the use of a larger variety of fuels and/or a more versatile utilization of the heat generated in the multi-purpose furnace system.

Thus, the object of the invention is to provide such a multi-purpose furnace system.

These and other objects are solved by means of a smoke purification device comprising the features of the characterizing part of claim 1 .

Particularly, the distinctive part of the invention is that the furnace system further comprises a ventilator or blower mounted at or on the inflow channel for providing combustion air from an outer gas chamber of the outflow pipe to the furnace, the combustion air thereby getting preheated by an exit gas chamber of the outflow pipe, arranged at or in connection with the furnace, a construction and a housing for receiving residual or waste products, an access device for opening and/or closing the housing and a door or hatch adapted for enabling removal of residual or waste products and the like, a primary opening or damper for opening and closing for primary combustion air to the primary combustion chamber and, arranged in a secondary air channel, a secondary opening or damper for opening and closing for secondary combustion air to the secondary combustion chamber and/or to the pri- mary combustion chamber, at least one heat storage chamber and at least one air channel arranged between the heat storage chamber and at least one of the primary combustion chamber and the secondary combustion chamber, the at least one air channel being open towards the exterior, a heat transfer- ring chamber and a heat transferring element arranged such as to transfer heat from the secondary combustion chamber to the heat transferring chamber, a valve or opening for allowing exit gas to flow from the primary and secondary combustion chambers into the heat transferring chamber, at least one, preferably two, resistance spiral units arranged in the at least one, preferably two, outflow channels and providing a resistance to exit gases flowing through the at least one, preferably two, outflow channels and further through an exit gas chamber of the outflow pipe, and at least one, preferably two, units arranged in a heat transferring relationship with the at least one, preferably two, outflow channels such as to utilize the heat transferred to the heat transferring chamber, e.g. to produce electricity or warm water or to furnish heat to a heating circuit.

Thereby a multi-purpose furnace system is provided having a construction in which the combustion air is provided from the exterior surroundings and by means of the ventilator or blower and the secondary air channel is distributed to the primary and secondary combustion chamber, respectively. Furthermore, a multi-purpose furnace system is provided with which the combustion air during intake through the associated outflow pipe is preheated by the excess heat remaining in the exit gases. The result is a multipurpose furnace system in which the combustion efficiency is improved con- siderably, which in turn enables the use of a larger variety of fuels, and especially fuels requiring a more efficient combustion to be sufficiently exploited.

The at least one air channel being open towards the exterior and the heat storage chamber provides for a multi-purpose furnace system which may transfer heat to the exterior - e.g. to the interior of a building - by convection in an effective manner with low heat losses. The heat storage chamber in particular enables this heat transfer to be extended over longer periods of time such as e.g. throughout a night time during which it may be desired to shut down the combustion in the multi-purpose furnace system to save fuel. As a supplement to this convection based heat transfer small amounts of heat may also be emitted by radiation from the outer surface of the multi-purpose furnace system.

The heat transferring element arranged such as to transfer heat from the secondary combustion chamber to the heat transferring chamber provides for a laminar flow of heat through the heat transferring chamber, which increases the heat exploitation efficiency of the multi-purpose furnace system.

The at least one, preferably two, resistance spiral units arranged in the at least one, preferably two, outflow channels and providing a resistance to exit gases flowing through the at least one, preferably two, outflow channels provides for a multi-purpose furnace system with which heat may furthermore be used for other external uses such as e.g. heating up an external heat element, driving a cooling or heating circuit or for production of hot water or electricity.

In the event that two outflow channels and two resistance spiral units are provided a further optimization of the heat extraction process is obtained.

In combination a multi-purpose furnace system is thus provided which in virtue of the combination of the above-mentioned distinctive features and their respective associated effects has a higher or even considerably higher overall efficiency, particularly an efficiency being larger than 73 % or even larger than 80 %, as compared to the known furnace systems and with mechanical improvements enabling e.g. the use of a larger variety of fuels and/or a more versatile utilization of the heat generated in the multi-purpose furnace system.

Furthermore, the construction and housing for receiving residual or waste products, the access device for opening and/or closing the housing and the door or hatch adapted for enabling removal of residual or waste products and the like provide for a multi-purpose furnace system with which residual or waste products and the like may be disposed of in a safe manner by means of a substantially closed system.

In an embodiment the multi-purpose furnace system further com- prises a receptacle for containing a liquid, such as a lime solution or a lime solution containing activated carbon, and a spindle with a driving means for providing a mist of the liquid comprised in the receptacle to the heat transferring chamber.

In an embodiment the multi-purpose furnace system may furthermore comprise a CO2 scrubber such as to remove CO2 from the exit gases. This may e.g. be obtained in the event that the liquid contained in the receptacle for containing a liquid is a solution suitable for removing CO2 from the exit gases. Such solutions encompass solutions of suitable amines, e.g. mono- ethanolamine, sodium hydroxide solutions, potassium hydroxide solutions and lithium hydroxide solutions. Another example of a CO2 scrubber is activated carbon

Thereby removal of dioxins and other unpleasant gases is achieved for purification of the exit gases.

In an embodiment the multi-purpose furnace system further comprises an insulated loft, the valve or opening for allowing smoke to flow from the primary and secondary combustion chambers into the heat transferring chamber being arranged in the loft.

Thereby a particularly compact construction is achieved and the loss of heat through the loft is reduced or altogether avoided.

In an embodiment the receptacle for containing a liquid and the spindle with a driving means is arranged in the loft.

Thereby a particularly compact construction is achieved while simultaneously ensuring that the distribution of the mist of the liquid comprised in the receptacle to the heat transferring chamber is achieved from above, and may furthermore be aided by gravity, such as to obtain a particularly even and efficient distribution. This in turn provides for a particularly efficient exit gas purification.

In an embodiment the secondary air channel comprises at least one opening for providing secondary combustion air to the primary combustion chamber such as to ensure an improved combustion in the primary combustion chamber. In an embodiment the multi-purpose furnace system further comprises at least one opening for providing tertiary combustion air to the primary combustion chamber, such as to ensure an even further improved combustion in the primary combustion chamber.

In an embodiment the primary combustion air constitutes about 40 -

60 % of the total amount of combustion air, the secondary combustion air constitutes about 15 - 50 % of the total amount of combustion air. Where provided for, the optional teritiary combustion air constitutes about 5 - 10 % of the total amount of combustion air. Whether tertiary combustion air is pro- vided for or not, such a distribution has been shown experimentally to provide for a particularly thorough and complete fuel combustion.

In an embodiment the multi-purpose furnace system further comprises a top plate or lid, the top plate or lid being insulated, and optionally a handle for opening and closing the top plate or lid.

Providing an insulated top plate or lid provides for a minimal heat loss through the top plate or lid and consequently an improved heat distribution towards the heat storage chamber and heat transferring chamber.

In an embodiment the secondary air channel extends upwards from the inflow channel and further through a bend such as to comprise an end section terminating between the primary combustion chamber and the secondary combustion chamber and extending in a direction inclined downwards.

Thereby a multi-purpose furnace system is provided with which the secondary combustion air gets preheated while flowing through the secondary air channel. Furthermore, a multi-purpose furnace system is thereby provided with which the secondary combustion air is delivered from the end section or nose of the secondary air channel in such a way that particularly good turbulence characteristics are provided in the secondary combustion chamber. In combination this ensures a particularly thorough combustion in the secondary combustion chamber.

In an embodiment the multi-purpose furnace system further comprises at least one return valve and at least one flow valve for connection to an external heating or cooling circuit. Thereby heat generated by the multi- purpose furnace system may be exploited in a heating or cooling system e.g. in the building in which the multi-purpose furnace system is installed.

In an embodiment the heat storage chamber comprises at least one of a volcanic rock and a bio-oil, and that the multi-purpose furnace system optionally further comprises at least one valve for filling bio-oil into the heat storage chamber. Thereby a particularly efficient and durable heat storage is achieved such as to enable submission of heat from the heat storage chamber to the surroundings over a long period of time, particularly over many hours, such as throughout a night or at least 6-10 hours.

A further object of the invention is to provide a multi-purpose furnace system with associated mechanical improvements for protection against the unpleasant particles, which are today emitted to our surroundings, and which cause respiratory diseases including lung cancer and other lung diseases.

To achieve this object, the multi-purpose furnace system in an em- bodiment further comprises a smoke purification device, the smoke purification device comprising an exit gas cleaning bag arranged in the exit gas chamber of the outflow pipe, an air bleeding device adapted for removing exit gases by suction through the exit gas cleaning bag, a valve for opening or closing for the exit gases and a plurality of openings for entry of combustion air through the outer air chamber of the outflow pipe to the furnace, the air bleeding device, the valve and the plurality of openings being arranged at an end of the outflow pipe opposite to the furnace, and the construction for receiving residual or waste products further being adapted for cleaning the exit gas cleaning bag, and the access device for opening and/or closing the hous- ing and the door or hatch further being adapted for enabling removal of the exit gas cleaning bag and the like.

It is noted that the smoke purification device may advantageously be of the type described in the applicant's Danish utility model no DK 2013 00192 U1 and European patent application no. EP 14174948.1.

In a further embodiment the multi-purpose furnace system comprises a control unit for electronically monitoring, controlling and/or operating the multi-purpose furnace system, and particularly the supply of primary and sec- ondary combustion air, as well as where provided the smoke purification device.

The control unit, which may e.g. be a PC or a PLC or a unit based on Fuzzy logic, receives information based on relevant measurements, such as e.g. measurements of one or more of the content or level of O2, CO, CO2, dioxins or other gases or particulate matter in the combustion chambers and/or in the exit gases. The measurements may be performed during installation and/or running in of the multi-purpose furnace system and/or the multipurpose furnace system may comprise measurement equipment for perform- ing the measurements continuously or at predetermined time intervals.

Based on the measurements the control unit may control and adjust various parameters related to the multi-purpose furnace system, such as e.g. the amount of primary and/or secondary and/or tertiary combustion air to the combustion chambers or the amount of liquid released by the spindle with a drive means with the purpose of removing of dioxins or other gases.

The control unit may also be used to control and optimize the combustion process, e.g. based on the measurements of the O2 and/or CO level. In this connection it may for instance be advantageous that the control unit controls the combustion process in such a way that the level of O2 in the exit gases does not fall below 6 % and/or that the level of CO in the exit gases is as low as possible.

Also, the control unit may be adapted for per default switching to automatic control when the door of the multi-purpose furnace system is closed in a gastight manner.

The control unit may be automatic and/or may further comprise a control panel for enabling manual control of the multi-purpose furnace system and, where provided, the smoke purification device.

The invention will be described in more detail below by means of a non-limiting example of a presently preferred embodiment and with reference to the schematic drawings, in which:

Fig. 1 shows a cross sectional view of a first embodiment of a multipurpose furnace system, and Fig. 2 shows a cross sectional view of a second embodiment of a multi-purpose furnace system comprising a smoke purification device.

Irrespective of the embodiment the features of the multi-purpose furnace system according to the invention is constructed or made in materials, which fulfil the temperature related requirements in connection with a furnace of the relevant type.

Irrespective of the embodiment the height of the multi-purpose furnace system according to the invention may be of the same order of magnitude as the known types of furnace systems, or it may alternatively be higher or lower.

Turning now to Fig. 1 , a first embodiment of a multi-purpose furnace system according to the invention and comprising a furnace 35 and an associated outflow pipe 34 or chimney for leading exit gases away from the furnace 35 to the surroundings is illustrated.

Irrespective of the embodiment, the furnace 35 may be covered or coated with a suitable heat insulating and heat resistant material such as vermiculite-based plates, an example being Skamolex®-plates manufactured by the Danish company Skamol A/S.

Generally, and irrespective of the embodiment, a multi-purpose fur- nace system according to the exemplary embodiments shown on the figures comprises the following:

Two outflow channels 31 for leading exit gases away from the furnace 35 to the associated outflow pipe 34 and further to the surroundings. In other embodiments only one outflow channel 31 may be provided. Embodi- ments with more than two outflow channels 31 are also feasible.

A primary combustion chamber 29 and a secondary combustion chamber 19. The secondary combustion chamber 19 is arranged above the primary combustion chamber 29.

An inflow channel 30 and a ventilator or blower 13 mounted at or on the inflow channel 30 for providing combustion air from the exterior. The combustion air is drawn through an outer gas chamber 33 of the outflow pipe 34 and the inflow channel 30 to the furnace 35, the combustion air thereby getting preheated by an exit gas chamber 32 of the outflow pipe 34.

A primary opening or damper 12 for opening and closing for primary combustion air to the primary combustion chamber 29.

A secondary air channel 21 and, arranged in the secondary air chan- nel 21 , a secondary opening or damper 1 1 for opening and closing for secondary combustion air to the secondary combustion chamber 19 and/or to the primary combustion chamber 29. As shown on the figures the secondary air channel 21 marks a transition between the primary and secondary combustion chambers 19, 29. In this way the secondary combustion air is primarily introduced in the part of the secondary combustion chamber 19 closest to the primary combustion chamber 29. This ensures that combustible gases have relatively long dwelling times in regions of the combustion chambers 19, 29 with elevated temperature, thus in turn ensuring an optimized burning and decomposition of the combustible gases, including e.g. dioxins which decom- pose at sufficiently high temperatures.

The secondary air channel 21 extends upwards from the inflow channel 30. The secondary air channel 21 further comprises an end section 21 ' terminating between the primary combustion chamber and the secondary combustion chamber and extending in a direction inclined downwards, or in other words in a direction towards the housing 36.

A heat transferring chamber 20 and a heat transferring element 25 arranged such as to transfer heat from the secondary combustion chamber 19 to the heat transferring chamber 20.

A valve or opening 8 for allowing exit gas to flow from the primary and secondary combustion chambers 19, 29 into the heat transferring chamber 20, and further into the outflow channels 31 and the exit gas chamber 32 of the outflow pipe 35.

A heat storage chamber 4 and an air channel 5. The air channel 5 is arranged between the heat storage chamber 4 and at least one of the primary combustion chamber 29 and the secondary combustion chamber 19. The at least one air channel 5 is open towards the exterior. In the embodiments shown the heat storage chamber 4 and the air channel 5 extend such that they enclose the furnace 35 partially, and especially the surface are of the furnace 35 adjacent the primary combustion chamber 29, the secondary combustion chamber 19 and the heat transferring chamber 20. In other embodiments two or more separate heat storage chambers 4 and air channels 5 may be provided. The heat storage chamber 4 may comprise a material or a combination of materials suitable for storing heat, suitable examples being volcanic rocks and bio oil.

Each of the outflow channels 31 comprise a resistance spiral unit 24 arranged in the outflow channel and providing a resistance to exit gases flow- ing through the outflow channels 31 .

Each of the outflow channels 31 further comprise a unit 9 and 10, respectively, for utilizing the heat transferred to the heat transferring chamber 20. The units 9 and 10 are generally arranged in heat transferring relationship with the outflow channels 31. In the embodiment shown the one unit 9 is ar- ranged on one of the two outflow channels, while the other unit 10 is arranged on the other of the two outflow channels. The units 9 and 10 may in principle be any feasible unit suitable for such a purpose.

In the embodiment shown the unit 9 is a unit adapted for driving a refrigerator for a cooling circuit, particularly an absorption cooling circuit having a low background noise during operation, or a heater for a heating circuit. Thereby an optimum exit temperature and efficiency of the multi-purpose furnace system may be achieved.

Furthermore, in the embodiment shown the unit 10 is a unit adapted for transporting heat to fuel thermoelectric components for producing an elec- trical current. A battery may be provided for storing the electrical current produced by the thermoelectric components. For instance, the electrical current may be used for powering the control unit.

Another feasible example of a unit adapted for utilizing the heat transferred to the heat transferring chamber 20 would be a heater associated with a water tank with the aim of producing warm water or a unit adapted for transporting heat to a heater associated with a water tank with the aim of producing warm water. The provision of a connection to another type of heat storage unit, such as a district heating unit, is also feasible.

A handle 1 for moving a fire grate 16 such that residual or waste products resulting from the burning of fuels in the furnace 35 fall down to a construction 14, such as a worm or a screw, arranged in a housing 36 below the primary combustion chamber 29 and provided for removal of the residual or waste products.

A door 3 for providing access to the primary combustion chamber 29 such that fuel may be filled into the primary combustion chamber 29 and a handle 2 for opening and closing the door 3. The door 3 may be provided with a pane made of a glass suitable for withstanding the elevated temperatures prevailing in the furnace during combustion of fuel.

A loft 6 insulated by means of an insulating material.

A top plate 7 for closing off the loft 6 towards the exterior. The top plate 7 may also be insulated by means of an insulating material.

An access device 15, such as a valve or a connector, arranged on the housing 36 for opening and/or closing the housing 36 for residual or waste products.

A device, such as a motor, denoted M for producing a force urging residual products from the furnace 35 towards the access device 15, such as a valve or connector, at which removal of the residual products for safe disposal may be performed, e.g. by suction exerted by a vacuum cleaner-like device.

A stop 17 may be provided to avoid fuel pieces falling out of the multi-purpose furnace system.

At least one, and particularly a plurality of, holes 18 for providing tertiary combustion air to the primary combustion chamber may be provided. A further optimization of the burning and decomposition of the combustable gases may be ensured by ensuring a continuous provision of tertiary combustion air by means of the holes 18.

Furthermore, a supporting element, such as a stone or a bowl, for supporting fuel pieces may also be provided, particularly arranged near the holes 18. A return valve 22 and a flow valve 23 for connection to an external heating circuit.

A receptacle 26 for containing a liquid, such as a lime solution or a lime solution containing activated carbon, and a spindle 28 with a driving means for providing a mist of the liquid comprised in the receptacle 26 to the heat transferring chamber 20.

In some embodiments the receptacle 26 for containing a liquid and the spindle 28 with a driving means is arranged in the loft 6. In such embodiments a lid or hatch 27 is provided to enable servicing the receptacle 26 for containing a liquid and the spindle 28. The lid or hatch 27 is fixedly mounted by means of bolts or the like and comprises a gas tight sealing.

In other embodiments a valve, closable opening or the like may be provided for refilling the receptacle.

Turning now to Fig. 2, a second embodiment of a multi-purpose fur- nace system according to the invention and comprising a furnace 35 and an associated outflow pipe 34 or chimney for leading exit gases away from the furnace 35 to the surroundings is illustrated. The multi-purpose furnace system shown in Fig. 2 differs from that shown in Fig. 1 only in that it comprises a smoke purification system.

The smoke purification system generally comprises the following:

An exit gas cleaning bag 41 arranged in the exit gas chamber 32 of the outflow pipe. By way of example the exit gas filter bag 41 may be a filter bag, arranged in a filter basket, filter net or the like in the exit gas chamber 32 such as to filter and thereby clean the exit gases.

An air bleeding device 44 adapted for removing exit gases by suction through the exit gas cleaning bag 41 .

A valve 42 for opening or closing for the exit gases and a plurality of openings 43 for entry of combustion air through the outer air chamber 33 of the outflow pipe 34 to the furnace 35.

The air bleeding device 44, the valve 42 and the plurality of openings

43 are arranged at an end of the outflow pipe 34 opposite to the furnace.

The construction 14, such as a worm or a screw, arranged in the housing 36 below the primary combustion chamber 29 and provided for removal of the residual or waste products is in this embodiment further adapted for cleaning the exit gas cleaning bag 41 . Likewise, the access device 15 for opening and/or closing the housing 36 is in this embodiment further adapted for enabling removal of the exit gas cleaning bag 41 .

Furthermore, the door or hatch 37 is furthermore adapted for enabling removal of the exit gas cleaning bag 41 and the like.

In this embodiment the exit gas chamber generally denoted 32 further comprises a secondary chamber 32' and thus two chambers in total, for the exit gases. The secondary chamber 32', and thus the two chambers in total of the exit gas chamber 32, is provided as furnace systems of the wood burner type are gas tight constructions with a low internal oxygen content. In this case the exit gases are therefore introduced in a transverse direction into the exit gas chamber such that the exit gases and particles are forced down- wards towards the construction 14 at the bottom of the exit gas cleaning bag 41 before rising towards the top of the exit gas cleaning bag 41. Thereby the whole length of the exit gas cleaning bag 41 is utilized, which in turn enhances the efficiency of the smoke purification device.

It is noted that the smoke purification device may advantageously be of the type described in the applicant's Danish utility model no DK 2013 00192 U1 and European patent application no. EP 14174948.1 , which disclose further advantageous embodiments and features of such a smoke purification device.

It should be noted that the above description of preferred embodi- ments serves only as examples, and that a person skilled in the art will know that numerous variations are possible without deviating from the scope of the claims.

Particularly, the skilled person will readily realize that the various components and features of one of the embodiments described above may likewise find use in the other embodiment described above.

Furthermore, and irrespective of the embodiment the multi-purpose furnace system according to the invention may also be equipped with a smoke purification device comprising two or more exit gas cleaning bags 41 , which may be arranged in parallel or in series. Also, when the multi-purpose furnace system comprises a smoke purification device, the control system of the multi-purpose furnace system according to the invention may also be adapted for controlling the smoke purification device.

Furthermore, the multi-purpose furnace system according to the invention may also be adapted for removal of ΝΟχ-gases, dioxins and other unpleasant gases for further purification of the exit gases, for instance by recirculating the gases to ensure an even more thorough combustion and/or by supplying ammonia to the multi-purpose furnace system.

The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

Claims

P A T E N T C L A I M S

1 . A multi-purpose furnace system, such as a wood burner, a wood burning stove, an open fireplace, a furnace, stove or heath for burning wood or a smaller furnace or boiler for burning biomass fuel or wood pellets or oil or coal or coke, comprising a furnace (35), an inflow channel (30) and at least one, preferably two, outflow channels (31 ) as well as an associated outflow pipe (34) or chimney for leading exit gases away from the furnace (35) to the surroundings, a primary combustion chamber (29) and a secondary combustion chamber (19) arranged above the primary combustion chamber (29), c h a r a c t e r i z e d in that the furnace system further comprises:

a ventilator or blower (13) mounted at or on the inflow channel for providing combustion air from an outer gas chamber (33) of the outflow pipe (34) to the furnace, the combustion air thereby getting preheated by an exit gas chamber (32) of the outflow pipe (34),

arranged at or in connection with the furnace (35), a construction (14) and a housing (36) for receiving residual or waste products, an access device (15) for opening and/or closing the housing (36) and a door or hatch (37) adapted for enabling removal of residual or waste products and the like,

a primary opening or damper (12) for opening and closing for primary combustion air to the primary combustion chamber (29) and, arranged in a secondary air channel (21 ), a secondary opening or damper (1 1 ) for opening and closing for secondary combustion air to the secondary combustion chamber (19) and/or to the primary combustion chamber (29),

at least one heat storage chamber (4) and at least one air channel (5) arranged between the heat storage chamber (4) and at least one of the primary combustion chamber and the secondary combustion chamber, the at least one air channel (5) being open towards the exterior,

a heat transferring chamber (20) and a heat transferring element (25) arranged such as to transfer heat from the secondary combustion chamber (19) to the heat transferring chamber (20),

a valve or opening (8) for allowing exit gas to flow from the primary and secondary combustion chambers (19, 29) into the heat transferring chamber,

at least one, preferably two, resistance spiral units (24) arranged in the at least one, preferably two, outflow channels (31) and providing a resistance to exit gases flowing through the at least one, preferably two, outflow channels (31) and further through an exit gas chamber (32) of the outflow pipe, and

at least one, preferably two, units (9, 10) arranged in a heat transferring relationship with the at least one, preferably two, outflow channels (31) such as to utilize the heat transferred to the heat transferring chamber (20), e.g. to produce electricity or warm water or to furnish heat to a heating circuit.

2. A multi-purpose furnace system according to claim 1 , characterized in further comprising a receptacle (26) for containing a liquid, such as a lime solution or a lime solution containing activated carbon, and a spindle (28) with a driving means for providing a mist of the liquid comprised in the receptacle (26) to the heat transferring chamber (20).

3. A multi-purpose furnace system according to claim 1 or2, characterized in further comprising an insulated loft (6), the valve or opening (8) for allowing smoke to flow from the primary and secondary combustion chambers (19, 29) into the heat transferring chamber being arranged in the loft (6).

4. A multi-purpose furnace system according to claims 2 and 3, characterized in that the receptacle (26) for containing a liquid and the spindle (28) with a driving means is arranged in the loft (6).

5. A multi-purpose furnace system according to any one of the above claims, characterized in that the secondary air channel (21) comprises at least one opening for providing secondary combustion air to the primary combustion chamber (29).

6. A multi-purpose furnace system according to any one of the above claims, characterized in that it further comprises at least one open- ing (18) for providing tertiary combustion air to the primary combustion chamber (29).

7. A multi-purpose furnace system according to any one of the above claims, characterized in that it further comprises a top plate or lid (7), the top plate or lid (7) preferably being insulated, and optionally a handle for opening and closing the top plate or lid (7).

8. A multi-purpose furnace system according to any one of the above claims, characterized in that the secondary air channel (21 ) extends upwards from the inflow channel (30) and further through a bend such as to comprise an end section (21') terminating between the primary combustion chamber and the secondary combustion chamber and extending in a direction inclined downwards.

9. A multi-purpose furnace system according to any one of the above claims, characterized in that the multi-purpose furnace system further comprises at least one return valve (22) and at least one flow valve (23) for connection to an external cooling or heating circuit.

10. A multi-purpose furnace system according to any one of the above claims, characterized in that it further comprises a smoke purification device, the smoke purification device comprising:

an exit gas cleaning bag (41) arranged in the exit gas chamber (32) of the outflow pipe,

an air bleeding device (44) adapted for removing exit gases by suc- tion through the exit gas cleaning bag (41 ), a valve (42) for opening or closing for the exit gases and a plurality of openings (43) for entry of combustion air through the outer air chamber (33) of the outflow pipe (34) to the furnace, the air bleeding device (44), the valve (42) and the plurality of openings (43) being arranged at an end of the outflow pipe (34) opposite to the furnace, and the construction (14) for receiving residual or waste products further being adapted for cleaning the exit gas cleaning bag (41), and the access device (15) for opening and/or closing the housing (36) and the door or hatch (37) further being adapted for enabling removal of the exit gas cleaning bag (41) and the like.