CA1111337A - Feeding steam into a continuous open flame - Google Patents
Feeding steam into a continuous open flameInfo
- Publication number
- CA1111337A CA1111337A CA294,425A CA294425A CA1111337A CA 1111337 A CA1111337 A CA 1111337A CA 294425 A CA294425 A CA 294425A CA 1111337 A CA1111337 A CA 1111337A
- Authority
- CA
- Canada
- Prior art keywords
- flame
- steam
- rate
- furnace
- volatiles
- 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
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERALÂ ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
- F23L7/00—Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
- F23L7/002—Supplying water
- F23L7/005—Evaporated water; Steam
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Drying Of Solid Materials (AREA)
- Air Supply (AREA)
Abstract
ABSTRACT
Although it is known to improve the efficiency of combustion by feeding steam into an open flame, the present invention achieves an extra-ordinary increase in efficiency by feeding steam from the vicinity of the burner directly into the flame at a controlled rate such that the steam exceeds 15% (and preferably is 60% to 90%) of the oxygen theoretically required for complete combustion, but less than the rate at which the flame would be extinguished.
Although it is known to improve the efficiency of combustion by feeding steam into an open flame, the present invention achieves an extra-ordinary increase in efficiency by feeding steam from the vicinity of the burner directly into the flame at a controlled rate such that the steam exceeds 15% (and preferably is 60% to 90%) of the oxygen theoretically required for complete combustion, but less than the rate at which the flame would be extinguished.
Description
1~1133'~
J a~S~t It is known from U.S. Patents No.~ 2~9 and 1,966,591 that the efficiency of combustion of a continuous open flame can be improved by feeding steam directly into the flame. By "continuous" is meant a flame which usually burns continuously for at least one minute at a time.
The present invention provides a method of improving the efficiency of a continuous open flame of a burner of a furnace comprising feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a controlled rate such that the oxygen of the steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished.
It appears that optimum results are attained when the rate is such that the steam furnishes 60-90% more oxygen (as steam) than the oxygen (as air) which is theoretically required for complete combustion of the fuel.
When the steam supplies more than 100% additional oxygen, the flame might be extinguished if the temperature of the steam is near 100C before it is exposed to the heat of the flame. If its original temperature is higher, the steam may be fed into the flame at even greater rates without extinguishing the flame.
When the flame is shut off, the flow of steam should be interrupted ~-~
until after the flame is re-ignited. ~sually a delay of 5-10 seconds after re-ignition should be sufficient to insure against accidentally extinguishing the flame.
Where the fuel is a gas, it is desirably mixed with the steam before being fed into the flame. Where the steam is generated from water, a fuel such as alcohol may be dissolved in the water. Where the steam is generated in drying a substance, the volatile matter may be a gaseous fuel.
From another aspect, the invention provides in a furnace, a burner having a continuous open flame and means for feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a control-led rate such that the oxygen as steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished.
33'7 The invention also provides apparatus for heating materials to drive off water and other volatiles comprising: a furnace having a continuous open flame, a drying chamber, means for applying heat from the furnace to the drying chamber, means for collecting volatiles emitted from the drying chamber, and means for feeding said volatiles directly into the open flame.
1 ~
33'7 When the steam ls ~irst fed into a continuous open flame, any yellow or red color disappears, and the entire ~lame becomes blue and lengthens in a pulsating manner.
The maximum length of the pulsating flame substantially exceeds that of the unmodified flame. If the flame tends to grow to a length exceeding that of the combustion chamber, the flame should be directed into a devious (e.g., helical) path.
The invention is applicable to a variety of fuels including methane, petroleum oil, wood, coal and alcohol.
Where the fuel contains significant amounts of water, its j water content should be taken into account in calculating the maximum rate of adding water as steam without danger of accidentally extinguishing the flame.
Under conditions of high ambient humidity, it may ; be desirable to take into account the quantity of water in the combusti~n air and to reduce the rate of applied steam accordingly-to insure against extinguishing the flame. Under conditions of high humidity, the combustion air for natural gas may contain water in an amount furnishing oxygen tas water) about equaling 5% of the oxygen (as air) theoretically required for complete combustlon. -~
Depending upon the choice of fuel, a typical installation in the prior art may call for about 200% excess combustion air for maximum fuel efficiency. In the practice of the present invention, it is generally possible to reduce the combustion air to the theoretical level or even below.
This by itself produces considerably increased heating efficiency, especially where the combustion air is supplied at ambient temperature. In a heating plant which draws 33'7 combustion air from the area belng heated, there is less danger of suffocation and less waste since the combustion air normally goes up the chimney.
In the practice of the present invention, the elimination of excess combustion air is believed to provide greater assurance against accidentally extinguishing the flame when steam is being fed into the flame at very high rates.
For instaliations in which it would be incon-venient to reduce the flow of combustion air mechanically,part of the steam may be fed into the combustiQn air line to replace part of the combustion air.
When steam was applied at an optimum rate to the flame of a conventional alfalfa drier, the fuel consumption was reduced about 20%. By applying the steam emitted from the drying alfalfa to the flame, the total reduction in fuel consumption was about 35%, the additional saving apparently being due to combustion of gaseous fuel emitted from the alfalfa. Comparable savings in fuel consumption should be reaIized in the drying of other materials which evolve water, e.g., cotton, grain, milk, fish, eggs, wood, textiles, feces and latex paint.
It is theorized that when the steam strikes the flame, some of the water disassociates into hydrogen and oxygen, and combustion of the hydrogen and the avail-ability of nascent oxygen enhances the heat output.
Whether or not that theory is correct, the degree of increased efficiency of combustion is startling and of tremendous significance in this era of fuel shortages.
33`;' In the drawing:
FIGURE 1 is a schematic elevation, partly cut away to a central section, of a rotary alfalfa drier incorporat-ing the present invention; and FIGURE 2 is an enlarged cross section along line
J a~S~t It is known from U.S. Patents No.~ 2~9 and 1,966,591 that the efficiency of combustion of a continuous open flame can be improved by feeding steam directly into the flame. By "continuous" is meant a flame which usually burns continuously for at least one minute at a time.
The present invention provides a method of improving the efficiency of a continuous open flame of a burner of a furnace comprising feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a controlled rate such that the oxygen of the steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished.
It appears that optimum results are attained when the rate is such that the steam furnishes 60-90% more oxygen (as steam) than the oxygen (as air) which is theoretically required for complete combustion of the fuel.
When the steam supplies more than 100% additional oxygen, the flame might be extinguished if the temperature of the steam is near 100C before it is exposed to the heat of the flame. If its original temperature is higher, the steam may be fed into the flame at even greater rates without extinguishing the flame.
When the flame is shut off, the flow of steam should be interrupted ~-~
until after the flame is re-ignited. ~sually a delay of 5-10 seconds after re-ignition should be sufficient to insure against accidentally extinguishing the flame.
Where the fuel is a gas, it is desirably mixed with the steam before being fed into the flame. Where the steam is generated from water, a fuel such as alcohol may be dissolved in the water. Where the steam is generated in drying a substance, the volatile matter may be a gaseous fuel.
From another aspect, the invention provides in a furnace, a burner having a continuous open flame and means for feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a control-led rate such that the oxygen as steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished.
33'7 The invention also provides apparatus for heating materials to drive off water and other volatiles comprising: a furnace having a continuous open flame, a drying chamber, means for applying heat from the furnace to the drying chamber, means for collecting volatiles emitted from the drying chamber, and means for feeding said volatiles directly into the open flame.
1 ~
33'7 When the steam ls ~irst fed into a continuous open flame, any yellow or red color disappears, and the entire ~lame becomes blue and lengthens in a pulsating manner.
The maximum length of the pulsating flame substantially exceeds that of the unmodified flame. If the flame tends to grow to a length exceeding that of the combustion chamber, the flame should be directed into a devious (e.g., helical) path.
The invention is applicable to a variety of fuels including methane, petroleum oil, wood, coal and alcohol.
Where the fuel contains significant amounts of water, its j water content should be taken into account in calculating the maximum rate of adding water as steam without danger of accidentally extinguishing the flame.
Under conditions of high ambient humidity, it may ; be desirable to take into account the quantity of water in the combusti~n air and to reduce the rate of applied steam accordingly-to insure against extinguishing the flame. Under conditions of high humidity, the combustion air for natural gas may contain water in an amount furnishing oxygen tas water) about equaling 5% of the oxygen (as air) theoretically required for complete combustlon. -~
Depending upon the choice of fuel, a typical installation in the prior art may call for about 200% excess combustion air for maximum fuel efficiency. In the practice of the present invention, it is generally possible to reduce the combustion air to the theoretical level or even below.
This by itself produces considerably increased heating efficiency, especially where the combustion air is supplied at ambient temperature. In a heating plant which draws 33'7 combustion air from the area belng heated, there is less danger of suffocation and less waste since the combustion air normally goes up the chimney.
In the practice of the present invention, the elimination of excess combustion air is believed to provide greater assurance against accidentally extinguishing the flame when steam is being fed into the flame at very high rates.
For instaliations in which it would be incon-venient to reduce the flow of combustion air mechanically,part of the steam may be fed into the combustiQn air line to replace part of the combustion air.
When steam was applied at an optimum rate to the flame of a conventional alfalfa drier, the fuel consumption was reduced about 20%. By applying the steam emitted from the drying alfalfa to the flame, the total reduction in fuel consumption was about 35%, the additional saving apparently being due to combustion of gaseous fuel emitted from the alfalfa. Comparable savings in fuel consumption should be reaIized in the drying of other materials which evolve water, e.g., cotton, grain, milk, fish, eggs, wood, textiles, feces and latex paint.
It is theorized that when the steam strikes the flame, some of the water disassociates into hydrogen and oxygen, and combustion of the hydrogen and the avail-ability of nascent oxygen enhances the heat output.
Whether or not that theory is correct, the degree of increased efficiency of combustion is startling and of tremendous significance in this era of fuel shortages.
33`;' In the drawing:
FIGURE 1 is a schematic elevation, partly cut away to a central section, of a rotary alfalfa drier incorporat-ing the present invention; and FIGURE 2 is an enlarged cross section along line
2-2 of Figure 1.
As seen in Figure 1, a cylindrical hot-air furnace 10 which is lined with fire brick is connected to the central flue of a con~entional drum-type alfalfa drier 12. Alfalfa entering a belt-fed hopper 14 is drawn through the drier 12 in an S-shaped path by a thermostatically controlled blower 16 and through a duct 18 to a conventional cyclone separator 19. The dried alfalfa drops through a chute 20 while water and other volatiles from the alfalfa in the form of steam rise to a skimmer 22 and are drawn by the suction of a fan 24 through a conduit 26 and fed directly into the flame of the furnace 10. A humidistat (not shown3 in ~he conduit 26 controls an intake 28 o~
additional steam as required to supply the furnace at the des~red rate.
As seen in Figure 2, the furnace 10 is equipped with five gun-type burners 30. A series of vanes 32 directs the steam from the conduit 26 into helical flow patterns and thence directly into the flame of the burners.
The helical flow of the steam redirects the flame into a helical path, thus insuring good circulation both within the furnace 10 and within the flue of the drier 12.
~xample In an experimental operation of apparatus as illustrated in Figures 1 and 2, the combustion chamber of 33'7 the furnace was 1.~7 m ln diameter and 6 m in length.
Initially, alfalfa was fed into the hopper 14 at a rate of 3000 kg per hour and the blower 16 was operated at about 225 m per minute. The steam produced reached a temperature of about 130C in the duct 18 and about 115C in the con-duit 26.
As the steam began to be fed into the flame, the te~perature of the drier 12 increased. The thermostatic controls had been pre-ad~usted to respond to such decrease in temperature by reducing the ratio of combustion air to natural gas. That ratio was initially 34:1 and was gradually reduced to the theoretical 17 13 thus dimin~shing the cool-ing effect of the combustion air. The ability to operate at the theoretical ratio was deemed to be due in part to the effect of the steam feedback and in part to better mixing ; by virtue of greater turbulence. Before reaching the 17:1 ratio, two of the five burners had been shut off, and addi-tional steam was being added through the intake 28. In steady operation, the total steam being fed into the flame was 0.74 kg per m3 of combustion air.
Before any steam was generated, the temperature of the furnace 10 was 2090C. After two burners had been shut off and additional steam was being added, the furnace tem-perature was 2070C. The flame slowly pulsated to a maximum length extending well into the drier 12, thus substantially increasing the temperature in the drier. The rate at which the alfalfa was fed into the hopper was gradually increased to 4500 kg per hour and was drled at that faster rate as effectively as it was lnitlally without any steam feedback.
The more rapidly dried alfalfa reportedly had substantially l33'~
higher protein content than was obtained using an unmodified, but otherwise identical drier. The operator of the equip-ment reported that the modi~ied drier required only 2.59 ~oules/kg of water driven off as compared to 4.05 joules/
5 kg without any feedback. - -'
As seen in Figure 1, a cylindrical hot-air furnace 10 which is lined with fire brick is connected to the central flue of a con~entional drum-type alfalfa drier 12. Alfalfa entering a belt-fed hopper 14 is drawn through the drier 12 in an S-shaped path by a thermostatically controlled blower 16 and through a duct 18 to a conventional cyclone separator 19. The dried alfalfa drops through a chute 20 while water and other volatiles from the alfalfa in the form of steam rise to a skimmer 22 and are drawn by the suction of a fan 24 through a conduit 26 and fed directly into the flame of the furnace 10. A humidistat (not shown3 in ~he conduit 26 controls an intake 28 o~
additional steam as required to supply the furnace at the des~red rate.
As seen in Figure 2, the furnace 10 is equipped with five gun-type burners 30. A series of vanes 32 directs the steam from the conduit 26 into helical flow patterns and thence directly into the flame of the burners.
The helical flow of the steam redirects the flame into a helical path, thus insuring good circulation both within the furnace 10 and within the flue of the drier 12.
~xample In an experimental operation of apparatus as illustrated in Figures 1 and 2, the combustion chamber of 33'7 the furnace was 1.~7 m ln diameter and 6 m in length.
Initially, alfalfa was fed into the hopper 14 at a rate of 3000 kg per hour and the blower 16 was operated at about 225 m per minute. The steam produced reached a temperature of about 130C in the duct 18 and about 115C in the con-duit 26.
As the steam began to be fed into the flame, the te~perature of the drier 12 increased. The thermostatic controls had been pre-ad~usted to respond to such decrease in temperature by reducing the ratio of combustion air to natural gas. That ratio was initially 34:1 and was gradually reduced to the theoretical 17 13 thus dimin~shing the cool-ing effect of the combustion air. The ability to operate at the theoretical ratio was deemed to be due in part to the effect of the steam feedback and in part to better mixing ; by virtue of greater turbulence. Before reaching the 17:1 ratio, two of the five burners had been shut off, and addi-tional steam was being added through the intake 28. In steady operation, the total steam being fed into the flame was 0.74 kg per m3 of combustion air.
Before any steam was generated, the temperature of the furnace 10 was 2090C. After two burners had been shut off and additional steam was being added, the furnace tem-perature was 2070C. The flame slowly pulsated to a maximum length extending well into the drier 12, thus substantially increasing the temperature in the drier. The rate at which the alfalfa was fed into the hopper was gradually increased to 4500 kg per hour and was drled at that faster rate as effectively as it was lnitlally without any steam feedback.
The more rapidly dried alfalfa reportedly had substantially l33'~
higher protein content than was obtained using an unmodified, but otherwise identical drier. The operator of the equip-ment reported that the modi~ied drier required only 2.59 ~oules/kg of water driven off as compared to 4.05 joules/
5 kg without any feedback. - -'
Claims (10)
- THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOW:
l. Method of improving the efficiency of a continuous open flame of a burner of a furnace comprising feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a controlled rate such that the oxygen of the steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished. - 2. Method as defined in claim l wherein the steam in-cludes gaseous fuel.
- 3. Method as defined in claim l or 2 wherein said rate is 60-90%.
- 4. In a furnace, a burner having a continuous open flame and means for feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a con-trolled rate such that the oxygen as steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished.
- 5. A burner as defined in claim 4 wherein said rate for said means for feeding steam is 60-90%.
- 6. Apparatus for heating materials to drive off water and other volatiles comprising: a furnace having a burner having a continuous open flame and means for feeding steam from the vicinity of the burner into helical flow patterns directly into the flame at a controlled rate such that the oxygen as steam exceeds 15% of the oxygen theoretically required for complete combustion but less than the rate at which the flame would be extinguished, a drying chamber, means for applying heat from the furnace to the drying chamber, means for col-lecting volatiles emitted from the drying chamber, and means for feeding said volatiles directly into the open flame.
- 7. Apparatus as defined in claim 6 wherein said means for feeding said volatiles and said means for feeding steam together feed steam into the open flame at a rate such that the oxygen of the steam furnishes 60-90% of the oxygen theoretically required for complete combustion.
- 8. Apparatus as defined in claim 6 wherein the flame of the furnace is at one end of a cylindrical combustion chamber, the other end of which is connected to a flue in the drying chamber.
- 9. Apparatus as defined in any of claims 6, 7 or 8 useful for drying an agricultural commodity in said drying chamber wherein the drying chamber is connected to means for separating the agricultural commodity from said volatiles and there is a conduit for carrying the volatiles from the separat-ing means to the furnace.
- 10. Apparatus as defined in any of claims 6, 7 or 8 useful for drying an agricultural commodity in said drying chamber wherein the drying chamber is connected to means for separating the agricultural commodity from said volatiles and there is a conduit for carrying the volatiles from the separating means to the furnace, and wherein said separating means is a cyclone .
separator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75919077A | 1977-01-13 | 1977-01-13 | |
| US759,190 | 1977-03-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111337A true CA1111337A (en) | 1981-10-27 |
Family
ID=25054722
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA294,425A Expired CA1111337A (en) | 1977-01-13 | 1978-01-05 | Feeding steam into a continuous open flame |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS53113332A (en) |
| CA (1) | CA1111337A (en) |
| DE (1) | DE2801050A1 (en) |
| GB (1) | GB1600500A (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US643269A (en) | 1899-04-06 | 1900-02-13 | C C Hutchinson | Plate-ice machine. |
| US1996591A (en) | 1931-03-23 | 1935-04-02 | Karl Biagosch | Cutting machine for paper, cardboard and the like provided with automatic means for feeding the material to be cut |
-
1977
- 1977-12-29 GB GB54183/77A patent/GB1600500A/en not_active Expired
-
1978
- 1978-01-05 CA CA294,425A patent/CA1111337A/en not_active Expired
- 1978-01-09 DE DE19782801050 patent/DE2801050A1/en not_active Withdrawn
- 1978-01-12 JP JP158378A patent/JPS53113332A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| DE2801050A1 (en) | 1978-07-20 |
| GB1600500A (en) | 1981-10-14 |
| JPS53113332A (en) | 1978-10-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |