Renewable Fuel Source Burner for a Furnace

Abstract

A furnace comprising a housing defining a combustion chamber therein, a burner in the housing, the burner comprising a body defining a burning zone, a fuel feeder in communication with the burning zone adapted to feed a renewable fuel source therein, an air supplier in fluid flow communication with the burning zone for supplying oxygen for fuel combustion, a cooling jacket integrated in the body and cooling the burning zone independently of the air supplier, the burner being operable to release hot combustion gases into the combustion chamber, and a heat exchanger in the housing capturing heat from the hot combustion gases and transferring the heat to another medium.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a furnace, and more particularly to a furnace comprising a burner for burning a renewable fuel source.

2. Background Art

The advantages of using renewable fuel sources to produce thermal energy are well known. Cereal and corn kernels as well as wood pellets are among the readily renewable fuel sources that are presently being explored for thermal energy production. For example, corn is readily available naturally as kernels and provides competitive pricing per unit of energy produced. However, the use of corn as a fuel source has presented several challenges One such challenge is the delivery of the kernels to the combustion chamber of the burner in a heating system such as a furnace. Another challenge is the requirement for proper temperature, mixing and oxygen exposure. A further challenge is maintaining optimum temperature control of the burner and of the furnace as a whole.

Therefore, there exists a need for improvements in the art of burning renewable fuel sources.

SUMMARY OF INVENTION

Therefore, in accordance with an aspect of the present invention, there is provided a furnace comprising a housing defining a combustion chamber therein, a burner in the housing, the burner comprising a body defining a burning zone, a fuel feeder in communication with the burning zone adapted to feed a renewable fuel source therein, an air supplier in fluid flow communication with the burning zone for supplying oxygen for fuel combustion, a cooling jacket integrated in the body and cooling the burning zone independently of the air supplier, the burner being operable to release hot combustion gases into the combustion chamber, and a heat exchanger in the housing capturing heat from the hot combustion gases and transferring the heat to another medium.

In accordance with another aspect of the present invention, there is provided a burner comprising a body defining a burning zone having an area of greater burning and an area of lesser burning, an air supplier in fluid flow communication with the burning zone supplying oxygen for fuel combustion, a fuel feeder in communication with the burning zone supplying a renewable fuel source directly into the area of lesser burning of the burning zone.

In accordance with a further aspect of the present invention, there is provided a method of operating a furnace comprising a heat exchanger and a burner, the method comprising the steps of providing a burner having an air supplier and a cooling jacket, the air supplier and the cooling jacket being independently fed, determining a maximum and a minimum temperature for the heat exchanger and for the burner, determining an actual temperature in the heat exchanger and in the burner, controlling the air supplier and the cooling jacket independently thereby moderating the actual temperature in the heat exchanger and in the burner relative to the respective maximum and minimum temperatures.

BRIEF DESCRIPTION OF DRAWINGS

Reference will now be made to the accompanying drawings, showing by way of illustration a particular embodiment thereof, and in which:

FIG. 1 is a cross-sectional side view of a furnace comprising a burner for burning a renewable fuel source in accordance with a particular embodiment of the present invention;

FIG. 2 is a cross-sectional rear view of the furnace of FIG. 1;

FIG. 3 is a cross-sectional side view of the burner of FIG. 1;

FIG. 4 is a cross-sectional front view of the burner of FIG. 1;

FIG. 5 is a front view of a back wall plate adapted to receive the burner of the furnace of FIG. 1; and

FIG. 6 is a schematic view of a burning zone in the burner of FIG. 1, showing a formation of fuel pellets.

DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, a furnace for creating thermal energy by burning a renewal fuel source in accordance with a particular embodiment of the present invention is shown at 10. The furnace 10 generally comprises a housing 12 defining a combustion chamber 14 therein. The housing 12 includes a front, a rear and a pair of side walls 16, 18 and 20 respectively and a ceiling 22 and floor 24. In this exemplary embodiment, the walls 16, 18 and 20 and the floor 24 are at least partially isolated to contain heat produced in the combustion chamber 14. The isolation is identified by numeral 25. The front wall 16 includes a front door 26 for access to the combustion chamber 14. The ceiling 22 includes an exhaust pipe or chimney 28 for directing and releasing the combustion gases produced in the furnace 10 to a safe exterior environment. The floor 24 includes a removable tray 30 for facilitating cleaning of ash and debris which may accumulate on the floor 24. More specifically, the front wall 16 includes a tray door 31 for slidably removing the tray 30.

The furnace 10 further comprises a burner 32 positioned inside the combustion chamber 14 adjacent the rear wall 18 of the housing 12 and racing the front door 26 thereof. More particularly, the rear wall 18 of the housing 12 includes an aperture 34 proximal to the floor 24 shown covered by a back wall plate 36, which is used for mounting the burner 32 in the furnace 10. Particularly, the burner 32 is fixed to the back wall plate 36 as will be described in detail furtheron, and is subsequently inserted through the aperture 34 of the rear wall 18 such that the back wall plate 36 is fixed thereto. The burner 32 can then be accessed by way of the front door 26 of the furnace 10.

The burner 32 is adapted to burn fuel pellets such as corn kernels or other cereals, or wood pellets to name a few renewal fuel sources. As the fuel burns, it generates hot combustion gasses which arc released into the combustion chamber 14 of the furnace 10. The furnace further comprises a heat exchanger 38 disposed in the housing 12 to capture the heat from the hot combustion gasses in the combustion chamber 14 and transfer the heat to another medium such as air or water, which is then used to heat an enclosure such as a building or the like.

In the exemplary embodiment illustrated in FIGS. 1 and 2, the heat exchanger 38 includes a plurality of vertically positioned metal tubes 40 extending through an enclosed reservoir 42 disposed within the housing 12. The reservoir 42 includes a top and bottom wall 44 and 46 across which the tubes 40 allow fluid flow. The top wall 44 is positioned in spaced relation with the ceiling 22 of the housing 12, thus, defining a plenum 48 therebetween. When the furnace 10 is in operation, the hot combustion gases produced by the burning fuel and released by the burner 32 into the combustion chamber 14 rise and travel through the tubes 40 thereby heating same before exiting into the plenum 48 and out through the exhaust pipe 28. The reservoir 42 is filled with water that circulates about the tubes 40 to absorb heat from the hot metal surfaces. Thus, the water does not come into contact with the hot combustion gases directly. The reservoir 42 includes a pair of inlets 50 defined in the bottom right and left corners of the rear wall 18 of the housing 12, and an outlet 52 defined in the top right corner of the rear wall 18. Also, the reservoir 42 includes a pair of upstanding walls 54 in spaced relation with the side walls 20 of the housing 12, defining passageways 56 therebetween. The pair of upstanding walls 54 intersects the bottom wall 46 of the reservoir 42 at opposite ends thereof.

Furthermore, the furnace 10 includes a pump (not shown) for circulating a flow of water in through the reservoir inlets 50 and out through the reservoir outlet 52. In greater detail, the flow of water travels upwards between the side and upstanding walls 20 and 54 through the passageways 56 and then between the top and bottom walls 44 and 46 about the tubes 40 before exiting through the reservoir outlet 52. Advantageously, the water traveling upwardly through the passageways 56 cools the side walls 20 of the housing 12 before being heating by the hot metal tubes 40. The heated water in the reservoir 42 is then transported through a piping system (not shown) and subsequently used to heat a building or the like.

In another example not illustrated, the heat exchanger 38 may include curved metal tubing disposed in the combustion chamber 14 through which air is passed therethrough. The metal tubing surfaces are heated by the upward flow of hot combustion gasses such that the air passing through the tubing absorbs heat from the hot metal surfaces. The heated air is then circulated through air ducts for distribution throughout a building or the like.

Now referring concurrently to FIGS. 1 to 4, the burner 32 is shown in accordance with a particular embodiment of the present invention. The burner 32 comprises an elongated body 57 defining a burning zone 58 therein. More specifically, the burner 32 includes front inner and outer walls 60 and 62, a pair of side inner and outer walls 64 and 66, a rear wall 68, a floor 70, a pair of top covers 72 and a front door 74. The elongated body 57 is preferably rectangular. The burner 32 is mounted to the previously mentioned back wall plate 36 that is clearly shown in FIG. 5. As can be seen, the back wall plate 36 comprises a slot configuration 76 in the shape of the cross-section of the side inner walls 64 and 66 and of the floor 70 adapted to mate with same. The back wall plate 36 further comprises a plurality of equidistantly spaced apertures 78 about the perimeter thereof adapted to receive fixation, means for attachment to the rear wall 18 of the housing 12. The back wall plate 36 also includes water inlet and outlet orifices 80 and 82, an air outlet orifice 84, a temperature sensor receiving orifice 86 and a first fuel feeder receiving opening 88. The water inlet and outlet orifices 80 and 82 are located on opposite sides of the slot configuration 76 portion corresponding to the side inner walls 64, adjacent thereto. Similarly, the air outlet orifice 84 is located near the water inlet orifice 80 adjacent the slot configuration 76. The temperature sensor receiving orifice 86 is disposed in the center of the back wall plate 36 and the first fuel feeder receiving opening 88 is located above the slot configuration 76 portion corresponding to the floor 70, adjacent thereto.

In the exemplary embodiment illustrated in FIGS. 1 through 5, the burner 32 is assembled in the following way in no particular order. The rear wall 68 of the burner 32 is positioned a predetermined distance away from the back wall plate 36 in parallel relation thereto. The rear wall 68 comprises a second fuel feeder receiving opening 89 that is aligned with the first fuel feeder receiving opening 88 of the back wall plate 36. Next, the side inner walls 64 and the floor 70 are inserted perpendicularly through the slot configuration 76 and are attached on the back surface of the back wall plate 36 and along the perimeter of the rear wall 68 of the burner 32. The front inner wall 60 is attached to the side inner walls 64 and the floor 70 such that it extends at an angle away from the vertical. Next, the side outer walls 66 are perpendicularly attached to the front surface of the back wall plate 36 and to top and bottom edges 90 and 92 of the side inner walls 64. The front outer wall 62 is perpendicularly attached to the ends of the side outer walls 66 and floor 70 such that it extends vertically. It should be understood that the above described assembly of the burner 32 is merely one example, and conversely, the burner can be manufactured as an integral unit. It should also be understood that the back wall plate is provided for manufacturability purposes and that the burner can be inserted in the furnace without the help of a back wall plate.

Referring to FIGS. 3 and 4, it can be seen that the burner 32 comprises a cooling jacket 93 integrated in the elongated body 57 there. In this exemplary embodiment the front and side inner and outer walls 60-66 define an enclosure 94 therebetween which is in fluid communication with water inlet and outlet orifices 80 and 82 and air outlet orifice 84. Thus, the enclosure 94 is adapted to receive a flow of water for cooling the walls of the burner 32 and thereby controlling the temperature of the burning zone 58 inside the burner 32. The burner 32 comprises a pump (not shown) for circulating a flow of water along one side of the burner 32, then through the front thereof and back along the other side of the burner 32. The air outlet orifice 84 is adapted to receive an aerator (not shown) for removing air from the enclosure 94 while keeping the water therein. Notably, in another example, the cooling jacket 93 can be provided as an air jacket integrated in the walls of the burner 32.

Now referring to FIG. 1, the burner 32 further comprises a fuel feeder 96 for transporting fuel pellets into the burning zone 58. For example, the fuel feeder 96 may include an endless screw 98 in communication with a container 100 supplying the fuel pellets. More particularly, the endless screw 98 defines a first and second end 102 and 104, the first end 102 being inserted through the first fuel feeder receiving opening 88 in the back wall plate 36 to mate with the second fuel feeder receiving opening 89 in the rear wall 68 for providing fuel pellets into the burning zone 58. The endless screw 98 extends out of the rear wall 18 of the housing 12 and is activated by a motor 106 engaged to the second end 104 thereof. Furthermore, the container 100 is located outside of the housing 12 of the furnace 10 above the endless screw 98 such that it operates to drop fuel pellets into the endless screw 98 that are then transported into the burner 32. For example the container 100 may be a hopper.

It can be seen that the fuel feeder 96 of the burner 32 is positioned near the floor 70 thereof so as to push fuel pellets into the burning zone 58 rather than drop same from an elevated position. During operation, the fuel feeder 96 transports the fuel pellets into the burner 32 through the second fuel feeder receiving opening 88. As the fuel pellets build up near the opening 88, the incoming fuel pellets push the accumulated fuel pellets towards the front of the elongated body 57 of the burner 32 thereby defining a longitudinal feeding direction 107. As the fuel pellets continue to accumulate in the burner 32, they form a hill-like formation that rises and expands as more and more fuel pellets arc introduced into the burner 32. The dimensions of the elongated body 57 and the volume of fuel pellets and speed at which they are delivered into the burner 32 are pre-determined to ensure that the hill-like formation of fuel pellets is built up in the burning zone 58 of the burner 32. Furthermore, the fuel feeder 96 is controlled by a control system (not shown) that can moderate the fuel flow thereby permitting continuous, sporadic or no fuel flow into the burner 32.

Now referring to FIG. 6, a schematic view of a hill-like formation of fuel pellets are generally identified by numeral 108 is shown in the burning zone 58 of the burner 32. More specifically, the burning zone 58 defines a bottom portion 110 which further defines an area of lesser burning 112, and a top portion 114 which further defines an area of greater burning 116. Thus, the fuel feeder 96 is positioned to feed fuel pellets into the bottom portion 110 of the burning zone 58; thereby causing an accumulation of fuel pellets 108 to rise and expand in the burning zone 58, and more particularly, into the top portion 114 of the burning zone 58. During combustion of the fuel pellets 108, the area of greater burning 116 comprises the fuel pellets 108 at the top of the hill-like formation and the area of lesser burning 112 comprises the fuel pellets 108 at the bottom of the hill-like formation. As the fuel pellets 108 burn, the ash that is produced falls to the floor 70 of the burner 32. As the more fuel is introduced into the burner 32, the fuel pellets 108 in the area of lesser burning 112 are pushed upwardly towards the area of greater burning 116 thereby being exposed to greater heat which increases combustion thereof.

Now referring concurrently to FIGS. 3 and 4, it can be seen that the burner 32 further comprises oxygen supplying means for enabling the combustion of fuel. In this exemplary embodiment the oxygen supplying means include a pair of longitudinal air conduits 118 integrated in the side inner walls 64 of the burner 32 on opposite sides thereof The air conduits 118 each include first and second rows of longitudinally spaced-apart air inlets 120 parallel to the longitudinal feeding direction 107 for supply oxygen in the burning zone 58. The air conduits 118 are spaced from the floor 70 of the burner 32, preferably at a distance close to half the height of the burner 32 to prevent clogging of the air inlets 120. More specifically, the air inlets 120 release air generally perpendicular to the longitudinal feeding direction 107, spraying air directly into the area of greater burning 116 to optimize combustion of fuel. The pair of longitudinal air conduits 118 extends through the back wall plate 36 out of the housing 12 and are in fluid communication with a fan 122 for blowing air therein.

It should be pointed out that the oxygen supplying means is separate from the cooling jacket 93 such that the latter can continue to cool the burner 32 even if the flow of air through air inlets 120 is cut off. A control system (not shown) independently controls both the oxygen supplying means and the flow of water in the cooling jacket 93. Also, it can be seen from FIG. 3 that the cooling jacket 93 is in direct contact with the pair of longitudinal air conduits 118 thereby cooling same.

Now referring to FIGS. 1 and 2, the pair of top covers 72 of the burner 32 partially enclose the burner 32, thereby allowing only for smoke to escape via gaps 124 defined between the top covers 72 and the side walls 66, 68 and between the pair themselves. The top covers 72 help increase the overall temperature in the burning zone 58 for maximizing fuel efficiency.

Furthermore, the front door 74 of the burner 32 is located above the front walls 60, 62 thereof opposite the fuel feeder 96 disposed in the rear wall 68. An opening 126 is present in the front end of the burner 32 between one of the top covers 72 and the front door 74. The front door 74 is angled inwardly towards the rear wall 68 of the burner 32 for redirecting the flames upwardly, partly through opening 126. The front door 74 is removable or openable to provide readily available front access to the interior of the burner 32, thereby facilitating cleaning thereof. As previously mentioned the front door 74 of the burner 32 faces the front door 26 of the furnace 10 for easy access.

In the case of using corn kernels as fuel, the formation of unburned carbon structures commonly referred to in the industry as clinkers need to be removed from the burner 32. Therefore, the front door 74 permits quick and easy access to the inside of the burner 32 for removal thereof. Furthermore, the top covers 72 increase the temperature in the burner 32 which in turn helps increase the maximum energy (BTU) output for a given size burner while also helping to minimize the formation of ash and clinkers. Still further, the cooling jacket 93 integrated in the elongated body 57 of the burner 32 keeps the inner walls 60 and 64 cool thereby preventing the clinkers from sticking thereto.

Now referring concurrently to FIGS. 2 and 3, it can be seen that the burner 32 further comprises a sensor 128 for detecting temperature inside the burning zone 58. In this exemplary embodiment, the sensor 128 is received through the sensor receiving orifice 86 in the back wall plate 36 and engages another sensor receiving orifice 130 defined in the rear wall 68 of the burner 32. The sensor 128 is maintained at a safe distance from the area of greater burning 116 defined in the burning zone 58.

Moreover, a control system (not shown) as previously mentioned is used to control the furnace 10. For example, the control system can be controlled at a distance by a thermostat that can moderate the temperature in a given enclosure such as a room of a house. The control system determines the temperature in the furnace reservoir 42 and in the burner 32 by way of the previously mentioned sensors and subsequently controls the burner 32 output and the furnace 10 output as a whole according to the respective temperatures. The control system independently controls: the flow of water in and out of the reservoir 42, the flow of water in and out of the cooling jacket 93 of the burner 32 as well as the flow of air released into the burning zone 58 for combustion, and the flow of fuel into the burning zone 58.

A method of operating the furnace in accordance with a particular embodiment of the present invention is described below. A pre-determined minimum and maximum temperature is set for the reservoir 42 and for the burner 32. The temperature of the reservoir 42 and the temperature in the burner 32 is determined by the respective sensors and the information is supplied to the control system. If the temperature in either the reservoir 42 or the burner 32 is less than the respective minimum pre-determined temperature, then the control system goes into heating mode. If the temperature in either the reservoir 42 or the burner 32 is greater than the respective maximum predetermined temperature, then the control system goes into standby mode. When in heating mode, the control system is programmed to allow the fuel feeder 96 to continuously feed fuel pellets into the burning zone 58 at a predetermined speed. When in standby mode, the fuel feeder 96 sporadically feeds fuel pellets into the burning zone 58 thereby providing a minimum amount of fuel to maintain the fire burning.

More particularly, if the temperature in the reservoir 42 is less than the respective minimum pre-determined temperature, the flow of water through the reservoir 42 inlets 50 is reduced to prevent condensation from forming on the walls of the furnace 10 which would lead to ash sticking thereto. If the temperature in the burner 32 is less than the respective minimum predetermined temperature, the pump providing water flow into the cooling jacket 93 is stopped. If the temperature in the burner 32 is greater than the respective maximum pre-determined temperature, the pump providing water flow into the cooling jacket 93 is started. Notably, the control system may include an alarm to notify if the lire in the burner 32 is extinguished. In such a case, the control system is programmed to stop the fuel feeder 96 completely.

Therefore, it can be seen that the burner 32 can continue to be cooled even if the oxygen supply means supplying air into the burning zone 58 is completely shut down. Furthermore, the fuel feeder 96 is independent from both the cooling and aeration systems of the burner 32. And the cooling system of the burner 32 is independent of the reservoir 42 of the furnace 10.

It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.

Claims

1. A furnace comprising:

a housing defining a combustion chamber therein;

a burner in the housing, the burner comprising a body defining a burning zone, a fuel feeder in communication with the burning zone adapted to feed a renewable fuel source therein, an air supplier in fluid flow communication with the burning zone for supplying oxygen for fuel combustion, a cooling jacket integrated in the body and cooling the burning zone independently of the air supplier, the burner being operable to release hot combustion gases into the combustion chamber; and

a heat exchanger in the housing capturing heat from the hot combustion gases and transferring the heat to another medium.

2. The furnace of claim 1, wherein the cooling jacket of the burner is separately controlled from the air supplier thereby cooling the burner irrespective of the air supplier.

3 The furnace of claim 1, wherein the cooling jacket of the burner includes at least one of an air cooling jacket and a water cooling jacket.

4. The furnace of claim 1, wherein the cooling jacket is disposed proximal to the air supplier for cooling the air supplier.

5. The furnace of claim 1, wherein the air supplier includes at least one air conduit integrated in the body of the burner, the air conduit having a plurality of air inlets in fluid flow communication with the burning zone.

6. The furnace of claim 5, wherein the burning zone defines an area of greater burning and an area of lesser burning, and wherein the air inlets release air directly into the area of greater burning.

7. The furnace of claim 6, wherein the burner has an elongated body defining a longitudinal direction, and wherein the air conduit extends in the longitudinal direction and the air inlets release air generally perpendicular to the longitudinal direction into the burning zone.

8. The furnace of claim 7, wherein the body of the burner includes inner and outer walls and wherein the cooling jacket extends between the inner and outer walls in the longitudinal direction.

9. The furnace of claim 8, wherein the air conduit is defined in an inner wall of the body, and wherein the cooling jacket extends adjacent the air conduit.

10. The furnace of claim 1, wherein the burning zone has an area of greater burning and an area of lesser burning, and wherein the fuel feeder supplies the renewable fuel source directly into the area of lesser burning of the burning zone.

11. The furnace of claim 10, wherein the burner is operable to burn a portion of the renewable fuel source in the burning zone, and wherein the fuel feeder supplies the renewable fuel source below the burning portion of the renewable fuel source already in the burning zone.

12. The furnace of claim 11, wherein the burning zone has a bottom portion and a top portion, and wherein the fuel feeder supplies the renewable fuel source directly into the bottom portion of the burning zone.

13. The furnace of claim 12, wherein the body has a floor and the bottom portion of the burning zone is defined by the floor.

14. The furnace of claim 13, wherein the fuel feeder is disposed proximal to the floor in the body of the burner.

15. The furnace of claim 1, wherein the body includes a floor and the air conduit is spaced from the floor.

16. The furnace of claim 1, wherein the burning zone of the burner is at least partially enclosed.

17. The furnace of claim 16, wherein the body includes at least one top cover at least partially enclosing the burning zone of the burner.

18. The furnace of claim 1, wherein the burner has a front door openable for easy access to the burning zone.

19. The furnace of claim 1, further comprising a control system in communication with the cooling jacket, the air supplier and the fuel feeder of the burner, the cooling system independently operating the cooling jacket, the air supplier and the fuel feeder.

20. A burner comprising a body defining a burning zone having an area of greater burning and an area of lesser burning, an air supplier in fluid flow communication with the burning zone supplying oxygen for fuel combustion, a fuel feeder in communication with the burning zone supplying a renewable fuel source directly into the area of lesser burning of the burning zone.

21. The burner of claim 20, wherein the burner is operable to burn a portion of the renewable fuel source in the burning zone, and wherein the fuel feeder supplies the renewable fuel source below the burning portion of the renewable fuel source already in the burning zone.

22. The burner of claim 21, wherein the burning zone has a bottom portion and a top portion, and wherein the fuel feeder supplies the renewable fuel source directly into the bottom portion of the burning zone.

23. The burner of claim 22, wherein the body has a floor and the bottom portion of the burning zone is defined by the floor.

24. The burner of claim 23, wherein the fuel feeder is disposed proximal to the floor in the body of the burner.

25. A method of operating a furnace comprising a heat exchanger and a burner, the method comprising the steps of:

providing a burner having an air supplier and a cooling jacket, the air supplier and the cooling jacket being independently fed;

determining a maximum and a minimum temperature for the heat exchanger and for the burner;

determining an actual temperature in the heat exchanger and in the burner;

controlling the air supplier and the cooling jacket independently thereby moderating the actual temperature in the heat exchanger and in the burner relative to the respective maximum and minimum temperatures.