CA1119467A - Fluid bed furnaces - Google Patents
Fluid bed furnacesInfo
- Publication number
- CA1119467A CA1119467A CA000325095A CA325095A CA1119467A CA 1119467 A CA1119467 A CA 1119467A CA 000325095 A CA000325095 A CA 000325095A CA 325095 A CA325095 A CA 325095A CA 1119467 A CA1119467 A CA 1119467A
- Authority
- CA
- Canada
- Prior art keywords
- bed
- chamber
- fluid
- furnace according
- bed furnace
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Furnace Details (AREA)
- Vertical, Hearth, Or Arc Furnaces (AREA)
Abstract
ABSTRACT OF DISCLOSURE
A fluid-bed furnace has one or more combustion chambers containing a fluidisable bed 10 of particulate material. At least adjacent pairs of combustion chambers are shown to share a common exhaust gas outlet system 30. For the or each combustion chamber there is an in-bed removable chamber 35 for housing a bed preheating burner 36 and supplying fluidising combustion promoting gas via transverse feed pipes 38, usually equipped with upstanding outlet heads. Bed material support is by a V- or U-section trough 32 also at least partially accommodating the chamber 35 and a material extraction feed 34.
A fluid-bed furnace has one or more combustion chambers containing a fluidisable bed 10 of particulate material. At least adjacent pairs of combustion chambers are shown to share a common exhaust gas outlet system 30. For the or each combustion chamber there is an in-bed removable chamber 35 for housing a bed preheating burner 36 and supplying fluidising combustion promoting gas via transverse feed pipes 38, usually equipped with upstanding outlet heads. Bed material support is by a V- or U-section trough 32 also at least partially accommodating the chamber 35 and a material extraction feed 34.
Description
6'7 ~ le invention rela~es -to fluidised bed furnaces where com-bustion promoting gas, normally air, is forced through and "fluidises", that is maintains in motion~ a bed of particulate material including or ~o l~hich is added combustible fuel, normally solid such as coal, or even liquid fuel su~h as oil.
Prior to introduction of fuel, beds of such furnaces require their incombustible particulate material to be fluidised and heated a~
least to the combustion temperature of the fuel to be added. From the point of viel~ of simplici*y of furnace construction, this preheating is probably most conveniently done by burners, say oil burners, in the combustion chamber above the bed. However, from the point of view of efficiency, the preheating is best done from below or within the bed material, but this does lead to more complex structures that are less easy to repair and main-tain.
According to the presen-t invention there is provided a fluid-bed furnace having in a combustion chamber a fluidised bed of imcombust-ible particulate material within which fuel is to be burnt and a remov-able elongate chamber having a single extension surrounded by and extending through the bed material from one end of the bed, said single extension housing a bed preheating burner extending from said one end of the chamber and said chamber being connected to spaced upstanding dis-charge pipes or ducts extending from upper parts of the chamber extension into the bed material to supply ~luidising combustion promoting gas into the bed mater;al substantially over the whole bed.
Preferably, the ch~nber is bodily removable from the f.urnace from said one end of the bed.
Preferably also, the discharge pipes or ducts are spaced along ''`,.1~` ~
4~7 a plurality of feed pipes or ducts e.~tending -transversely of a said chamber and in communication therewith.
It is also proposed herein that two or more combustion chambers eacil equipped with their own preheating and combustion gas discharge systems be provided in generally side-by-side relation. Then, within an overall enclosure of refractory material, preferably externally insulated, one or more vertical partitions may conveniently define the combustion chambers to either side thereof. In a preferred embodiment, a dual-chamber furnace has a single central partitlon wall between the two chambers with access thereto for repair or maintenance purposes from side walls of the overall enclosure.
Another proposal of this invention is to provide a pre-heating burner housing and combustion promoting gas distribution plenum chamber in a do~nwardly V- or U-shaped section trough below the bed proper. Such a trough of that section may be provided, at its lowest part and chamber, ; with an e~traction arrangement, such as a worm screw, for the bed material and particularly for removal of ash, heavy incidental incombustibles of the fuel, and agglomorated material that sinks through the bed material.
Clearly, a wor~ scre~-type extraction element ~ay convenientl~ extend p~rallel with the pre-combustion burner housing of gas pl~num chamber ~nd extend at least betweeD ends of the furnace b~d.
~he or each combustion cha~ber conveniently has its bed extend beyond an internal baffle or wall~ usually vertical, forcing exhaust gases to rise over its top, preferabl~ with a subsequent forced do~.nturn thereof towards a furnace exhaust, so that at least some entrained solid material from the bed will drop out on the rise or fall of the exhaust gas and back onto the bed ~naterial itself~ ~or a plural, preferably dual, chamber furnace as mentioned above~ a single furnace exhaust may be provided in an end chamber common to the fur~ace cha~bers~
Another proposal hereof concerns material extractio~
; includi~g coarse or agglomerated combustion residues from a low part o~ the bed preferably with return of fine material to the combustio~ chamber.
O~e embodi~ent o~ the invent-ion will now be described, 1 20 b~ way ~f example, with reference to the accompany1ng I drawings, in which:-F:igure 1 is a section through a furnace chamber;
~igure 2 is a section taken at ri.ght angles to that Or Figure 1 through a dual-chamber furnace;
Figure 3~is an incomplete par-t sectional plan view of the furnace of Figure 2 showing one furnace bed.
1 ~Ll9~G7 In Fi6ure ~, a ~ed of fluidisable incombustible p~rticulate ma~erial, normall~ sand, shown at 10 extends from a refractory end wall 11 of the f~rn3ce that has a downwardly inclined solid fuel leed 12 to the upper surface of the bed from a hopper 13 via a sealed rot~r~ feed 14.
At its other end the bed is bounded by a riser 15 from the furnace b~se t~ a step 16 of refractor~ material. Figure
Prior to introduction of fuel, beds of such furnaces require their incombustible particulate material to be fluidised and heated a~
least to the combustion temperature of the fuel to be added. From the point of viel~ of simplici*y of furnace construction, this preheating is probably most conveniently done by burners, say oil burners, in the combustion chamber above the bed. However, from the point of view of efficiency, the preheating is best done from below or within the bed material, but this does lead to more complex structures that are less easy to repair and main-tain.
According to the presen-t invention there is provided a fluid-bed furnace having in a combustion chamber a fluidised bed of imcombust-ible particulate material within which fuel is to be burnt and a remov-able elongate chamber having a single extension surrounded by and extending through the bed material from one end of the bed, said single extension housing a bed preheating burner extending from said one end of the chamber and said chamber being connected to spaced upstanding dis-charge pipes or ducts extending from upper parts of the chamber extension into the bed material to supply ~luidising combustion promoting gas into the bed mater;al substantially over the whole bed.
Preferably, the ch~nber is bodily removable from the f.urnace from said one end of the bed.
Preferably also, the discharge pipes or ducts are spaced along ''`,.1~` ~
4~7 a plurality of feed pipes or ducts e.~tending -transversely of a said chamber and in communication therewith.
It is also proposed herein that two or more combustion chambers eacil equipped with their own preheating and combustion gas discharge systems be provided in generally side-by-side relation. Then, within an overall enclosure of refractory material, preferably externally insulated, one or more vertical partitions may conveniently define the combustion chambers to either side thereof. In a preferred embodiment, a dual-chamber furnace has a single central partitlon wall between the two chambers with access thereto for repair or maintenance purposes from side walls of the overall enclosure.
Another proposal of this invention is to provide a pre-heating burner housing and combustion promoting gas distribution plenum chamber in a do~nwardly V- or U-shaped section trough below the bed proper. Such a trough of that section may be provided, at its lowest part and chamber, ; with an e~traction arrangement, such as a worm screw, for the bed material and particularly for removal of ash, heavy incidental incombustibles of the fuel, and agglomorated material that sinks through the bed material.
Clearly, a wor~ scre~-type extraction element ~ay convenientl~ extend p~rallel with the pre-combustion burner housing of gas pl~num chamber ~nd extend at least betweeD ends of the furnace b~d.
~he or each combustion cha~ber conveniently has its bed extend beyond an internal baffle or wall~ usually vertical, forcing exhaust gases to rise over its top, preferabl~ with a subsequent forced do~.nturn thereof towards a furnace exhaust, so that at least some entrained solid material from the bed will drop out on the rise or fall of the exhaust gas and back onto the bed ~naterial itself~ ~or a plural, preferably dual, chamber furnace as mentioned above~ a single furnace exhaust may be provided in an end chamber common to the fur~ace cha~bers~
Another proposal hereof concerns material extractio~
; includi~g coarse or agglomerated combustion residues from a low part o~ the bed preferably with return of fine material to the combustio~ chamber.
O~e embodi~ent o~ the invent-ion will now be described, 1 20 b~ way ~f example, with reference to the accompany1ng I drawings, in which:-F:igure 1 is a section through a furnace chamber;
~igure 2 is a section taken at ri.ght angles to that Or Figure 1 through a dual-chamber furnace;
Figure 3~is an incomplete par-t sectional plan view of the furnace of Figure 2 showing one furnace bed.
1 ~Ll9~G7 In Fi6ure ~, a ~ed of fluidisable incombustible p~rticulate ma~erial, normall~ sand, shown at 10 extends from a refractory end wall 11 of the f~rn3ce that has a downwardly inclined solid fuel leed 12 to the upper surface of the bed from a hopper 13 via a sealed rot~r~ feed 14.
At its other end the bed is bounded by a riser 15 from the furnace b~se t~ a step 16 of refractor~ material. Figure
2 shows two such ~urnace chambers within an overall furnace enclosure having bed bounding side walls 205 21 and central partition 22, and a top plate or wall 23, all o~ refractory material.
This top wall is shown with rei~forcementsana support girders~ Desirably it may be o~ any convenient prefabricated form to allow its ready removal and repl~cement both to facilitate repair and maintenance and allow shipping with parts tempaIarily stowed within the furnace chamber.
l At a position closer to the step 16 than the end wall `; 11, but spaced therefrom, each combustion chamber ha~ a transverse vertical wall 241 slid in ~etwêen side wall protrusions 25, and extending from immediately above the bed material to a position short of the cha~ber top 23 which, at a position above the riser 15 to step 16 has a transverse short depending wall 26. ~hus exhaust gases will be forced upwardly and then downwardly over the top of wall 25 and towards a furnace exhaust 28 substantially centrally of furnace end wall 29 spaced from and extending from below i7 the step 15 -to form an exhaust chamber 30, usually and preferably commo~ to both combustion chailibers.
The bottom of each furnace chamber has a V-shaped trough 32 within and to a total depth above which the nco~bustible bed material is disposed. At its base 3~, each such trough has a material extxaction worm screw 34 e~tending the full length of the trough below the bed.
Above this worm screw 34 is a combined pre-heater burner housing and combustion promoting gas plenum chamber 35 of elGngate c~lindrical form ~1BO extending the fuIl length of the bed. hn oil or gas burner 36 is housed at o~e end 37 of th~chamber and communication is provided at least at spaced positions along the length of the chamber with T-shaped gas distribution ducts or pipes 38 of which the cross pipes have a ~uralit: of spaced gas release he~ads 39 extending upwardly therefrorl,.
It mag be found convenierit ill building the fl~nace to .~, provide a 1edge at each side o~ ~ch combustion ch~nber to upport and~or locate ends of t.~ T-shaped distribution members thereb~ allowing them to be simpl~ lifted out for maintenance or repair purposes. ~he downwardly directed inlets of these T-pipes 38 may rit i.nto re-entrantly edged holes 40 in the c~lindrical chani~)er or, and perhaps preferabl.y, are located in a channel thereof that may be closed except where it is to register with such a T-pipe, but will still allow ready removal of the cha7nber whenever ~, r~quired.
The entire furnace structure is shown supp~rted on girder 42 located l~der side and partition walls there~f w-th the troughs disposed between them. Access doors 44 to the furnace chamber proper and 45 to the exhaust chamber are shown in the side walls.
In ~peration, eombustio~ pro~oting gas, usually air, will be pressurised by a fan 46, a~d supplied to the bl~ner mounting end of the chamber 35 for discharge into the bed 13 of incombustible materi~l. 0~ start up, the burner 36 will be lit to heat the fluidising gas. When the bed material reaches the desired ignition temperature for fuel supplied via feed 12 that fuel will start to feed in and the burner 76 may be extinguished as normal furnace operation ta~es place.
It will be noted from ~igure 3 that the ends of partition wall 22 have transversely extending parts 50 to each side and side walls 20, 21 have extensions 52 at the positio~ o~ riser 15 to ~rther c~nstra~n the exhaust gas ~low path and facilitate drop out of entrained particles. If desired collectio~s of such particles on the shelf 16 may be returned to the bed by an inclined at least intermi-ttently vibratable plate on the shelf 16.
It will be appreciated that -the worm screw 34 could be replaced by other suitable feeding means1 such as a pneumatic feed. It is also a valuable aspect o~ this ~ .
~946~
invention to provide a return of fine extracte~ material to the combustion chamber. To that end, we show a screening system 60, upon whic~ lumps of agglomerate material ~ill collec-t and from which they may be removed, and a transfer conveyor 62 of any suitable type, e~g. pneumatic, scraper, bucket or the like, to take the fine material bac~ to the combustion chamber at 64, which may be a sealed feed from a conveyor reception hopper. This is usually preferable to the conveyor 62 feeding directly into the solid fuel hopper 13, but that could be done if desired and any problems concerning wear and possibly erratic fuel dilution are within tolerable limits.
We also envisage that the chamber 30 could have gas delivery tubes taken directly from upper parts thereof instead of the gas discharge piping 38.
Such tubes could be radial oE a chamber 30 of generally circular cross-section as shown or could be medially bent, but should result in substantially even gas delivery across the width of the bed in the plane of Figure 2.
Another possibly advantageous modification of the chamber 30 is to line it with refractory, typically a castable material, to limit expansion thereof, which could be significant given that the chamber itself will usually be of stainless steel. Then~ short tubes welded to the upper part and ending in flanges can be coupled by bolting to flanges terminating the inlet tubes of the gas discharge .
~, ' .
, piping sets 38. The flan~es are readily made tolera~t of di~ferential eXpansion by slottins fro~ edges between ~olt holes.
. .
, !
' .
'
This top wall is shown with rei~forcementsana support girders~ Desirably it may be o~ any convenient prefabricated form to allow its ready removal and repl~cement both to facilitate repair and maintenance and allow shipping with parts tempaIarily stowed within the furnace chamber.
l At a position closer to the step 16 than the end wall `; 11, but spaced therefrom, each combustion chamber ha~ a transverse vertical wall 241 slid in ~etwêen side wall protrusions 25, and extending from immediately above the bed material to a position short of the cha~ber top 23 which, at a position above the riser 15 to step 16 has a transverse short depending wall 26. ~hus exhaust gases will be forced upwardly and then downwardly over the top of wall 25 and towards a furnace exhaust 28 substantially centrally of furnace end wall 29 spaced from and extending from below i7 the step 15 -to form an exhaust chamber 30, usually and preferably commo~ to both combustion chailibers.
The bottom of each furnace chamber has a V-shaped trough 32 within and to a total depth above which the nco~bustible bed material is disposed. At its base 3~, each such trough has a material extxaction worm screw 34 e~tending the full length of the trough below the bed.
Above this worm screw 34 is a combined pre-heater burner housing and combustion promoting gas plenum chamber 35 of elGngate c~lindrical form ~1BO extending the fuIl length of the bed. hn oil or gas burner 36 is housed at o~e end 37 of th~chamber and communication is provided at least at spaced positions along the length of the chamber with T-shaped gas distribution ducts or pipes 38 of which the cross pipes have a ~uralit: of spaced gas release he~ads 39 extending upwardly therefrorl,.
It mag be found convenierit ill building the fl~nace to .~, provide a 1edge at each side o~ ~ch combustion ch~nber to upport and~or locate ends of t.~ T-shaped distribution members thereb~ allowing them to be simpl~ lifted out for maintenance or repair purposes. ~he downwardly directed inlets of these T-pipes 38 may rit i.nto re-entrantly edged holes 40 in the c~lindrical chani~)er or, and perhaps preferabl.y, are located in a channel thereof that may be closed except where it is to register with such a T-pipe, but will still allow ready removal of the cha7nber whenever ~, r~quired.
The entire furnace structure is shown supp~rted on girder 42 located l~der side and partition walls there~f w-th the troughs disposed between them. Access doors 44 to the furnace chamber proper and 45 to the exhaust chamber are shown in the side walls.
In ~peration, eombustio~ pro~oting gas, usually air, will be pressurised by a fan 46, a~d supplied to the bl~ner mounting end of the chamber 35 for discharge into the bed 13 of incombustible materi~l. 0~ start up, the burner 36 will be lit to heat the fluidising gas. When the bed material reaches the desired ignition temperature for fuel supplied via feed 12 that fuel will start to feed in and the burner 76 may be extinguished as normal furnace operation ta~es place.
It will be noted from ~igure 3 that the ends of partition wall 22 have transversely extending parts 50 to each side and side walls 20, 21 have extensions 52 at the positio~ o~ riser 15 to ~rther c~nstra~n the exhaust gas ~low path and facilitate drop out of entrained particles. If desired collectio~s of such particles on the shelf 16 may be returned to the bed by an inclined at least intermi-ttently vibratable plate on the shelf 16.
It will be appreciated that -the worm screw 34 could be replaced by other suitable feeding means1 such as a pneumatic feed. It is also a valuable aspect o~ this ~ .
~946~
invention to provide a return of fine extracte~ material to the combustion chamber. To that end, we show a screening system 60, upon whic~ lumps of agglomerate material ~ill collec-t and from which they may be removed, and a transfer conveyor 62 of any suitable type, e~g. pneumatic, scraper, bucket or the like, to take the fine material bac~ to the combustion chamber at 64, which may be a sealed feed from a conveyor reception hopper. This is usually preferable to the conveyor 62 feeding directly into the solid fuel hopper 13, but that could be done if desired and any problems concerning wear and possibly erratic fuel dilution are within tolerable limits.
We also envisage that the chamber 30 could have gas delivery tubes taken directly from upper parts thereof instead of the gas discharge piping 38.
Such tubes could be radial oE a chamber 30 of generally circular cross-section as shown or could be medially bent, but should result in substantially even gas delivery across the width of the bed in the plane of Figure 2.
Another possibly advantageous modification of the chamber 30 is to line it with refractory, typically a castable material, to limit expansion thereof, which could be significant given that the chamber itself will usually be of stainless steel. Then~ short tubes welded to the upper part and ending in flanges can be coupled by bolting to flanges terminating the inlet tubes of the gas discharge .
~, ' .
, piping sets 38. The flan~es are readily made tolera~t of di~ferential eXpansion by slottins fro~ edges between ~olt holes.
. .
, !
' .
'
Claims (13)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A fluid-bed furnace having in a combustion chamber a fluidised bed of incombustible particulate material within which fuel is to be burnt and a removable elongate chamber having a, single extension surrounded by and extending through the bed material from one end of the bed, said single extension housing a bed preheating burner extending from said one end of the chamber and said chamber being connected to spaced upstanding discharge pipes or ducts extending from upper parts of the chamber extension into the bed material to supply fluidising combustion promoting gas into the bed material substantially over the whole bed.
2. A fluid-bed furnace according to claim 1 wherein the chamber is bodily removable from the furnace from said one end of the bed.
3. A fluid-bed furnace according to claim 1 wherein the dis-charge pipes or ducts are spaced along a plurality of feed pipes or ducts extending transversely of a said chamber and in communi-cation therewith.
4. A fluid-bed furnace according to claim 1 wherein the chamber has a bed material supporting means of V- or U-section.
5. A fluid-bed furnace according to claim 1, 2 or 3 comprising at least two said combustion chambers formed by partitioning an overall structure so that the fluidisable beds thereof are in generally side-by-side relation.
6. A fluid-bed furnace according to claim 4 comprising at least two said combustion chambers formed by partitioning an overall structure so that the fluidisable beds thereof are in generally side-by-side relation.
7. A fluid-bed furnace according to claim 6 wherein at least one adjacent pair of said combustion chamber shares a single exhaust outlet.
8. A fluid-bed furnace according to claim 1 further comprising, at a position below normal fluidisation levels, material extraction means capable of accommodating coarse or agglomerated material.
9. A fluid-bed furnace according to claim 8 comprising material extraction means disposed and operative along the lowest part of the or each said trough.
10. A fluid-bed furnace according to claim 9, wherein the or each extraction means comprises a worm screw.
11. A fluid-bed furnace according to claim 6 wherein the or each combustion chamber has internal walling of height and location to force upward and then downward movement to exhaust gas flow from bed parts more remote from an exhaust position than said walling.
12. A fluid-bed furnace according to claim 11 wherein the walling is located so that said downward movement is at least partially above an end part of the bed adjacent said exhaust position.
13. A fluid-bed furnace according to claim 11 wherein said walling comprises a first transverse vertical wall extending from above the bed to a height less than the associated chamber and a second transverse vertical wall depending from the roof of that chamber at a position closer to said exhaust position than the first vertical wall.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000325095A CA1119467A (en) | 1979-04-06 | 1979-04-06 | Fluid bed furnaces |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000325095A CA1119467A (en) | 1979-04-06 | 1979-04-06 | Fluid bed furnaces |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1119467A true CA1119467A (en) | 1982-03-09 |
Family
ID=4113933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000325095A Expired CA1119467A (en) | 1979-04-06 | 1979-04-06 | Fluid bed furnaces |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1119467A (en) |
-
1979
- 1979-04-06 CA CA000325095A patent/CA1119467A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |