CA1174461A - Method for removing carbonaceous deposits from heat treating furnaces - Google Patents
Method for removing carbonaceous deposits from heat treating furnacesInfo
- Publication number
- CA1174461A CA1174461A CA000382206A CA382206A CA1174461A CA 1174461 A CA1174461 A CA 1174461A CA 000382206 A CA000382206 A CA 000382206A CA 382206 A CA382206 A CA 382206A CA 1174461 A CA1174461 A CA 1174461A
- Authority
- CA
- Canada
- Prior art keywords
- furnace
- carbon dioxide
- gas
- burnout
- carbon
- 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
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
Abstract
ABSTRACT
A process for removing carbonaceous deposits (e.g.
soot) from a heat-treating furnace by passing a burn out gas containing from, by volume, 10 to 100% carbon dioxide, 0 to 20% water vapor balance nitrogen, air, or mixtures thereof through the furnace at a temperature of at least 1500°F.
A process for removing carbonaceous deposits (e.g.
soot) from a heat-treating furnace by passing a burn out gas containing from, by volume, 10 to 100% carbon dioxide, 0 to 20% water vapor balance nitrogen, air, or mixtures thereof through the furnace at a temperature of at least 1500°F.
Description
~7~
METHOD FOR REMOVING CARBONACEOUS DEPOSITS
FROM HEAT TREATING FURNACES
TECHNICAL FIELD
This invention pertains to the removal of carbona-'ceous deposits such as soot from heat-treating furnaces used to heat treat ferrous metals under an atmosphere containing reactive carbon.
S BACKGROUND O~ THE PRIOR ART
The metallurgical industry employs heat-treating furnaces for a variety of purposes. Under certain heat-treating conditions deposits of carbon may form in the furnace. For example, in gas carburization an atmosphere containing carbon donating (reactive carbon) constituents is employed to transfer carbon to the surface of steel, thereby causing a high carbon surface layer to be formed which increases the surface hardness of the part after rapid cooling (e.g. quenching). The presence of these carbon donors in the atmosphere may ~' also lead to unwanted deposits of el~mental carbon being formed at various points in the furnace.
~ owder metallurgy involves the sintering of objects produced by compression of powdered metals. To insure S the development of adequate density, and release of the ohject from the mold, these powders contain a lubricant W}liCh is usually a carbon-containing solid, such as a metal soap. During heating in the furnace, the lubri-cant decomposes releasing volatile materials which form sooty deposits in the furnace.
Deposi-tion of soot or other carbonaceous material in the furnace is undesirable. It ~ay obstruct the flow of gases through the furnace, interfere with effective heat transfer, and in some cases, may react with high temperature alloy components of the furnace reducing their strength and durability. It is necessary periodically to remove carbon from heat-treating furnaces.
An effective way to achieve this end is to burn the carbon out with air or with air diluted with an inert gas such as nitrogen.
However, since the reaction of oxygen with carbon to form carbon dioxide is highly exothermic (96,000 calories (96 kcal) per gram mole at 1700F.) great care must be exercised to avoid overheating which can cause severe damage to the furnace or its internal components.
The effects of sooting and of the catastrophic melting of an alloy radiant heating tube during soot buxnout is shown and discussed in an article entitled, "Under-standing Conditions that Affect Performance of Heat Resisting Alloys`', Parts I and II appearing in the March and April 1979 editions of Industrial Heating, Vol. XLVI, No. 3, pp. 8-11 and Vol. XLVI, No. 4, pp.
44-47. It is customary to control the rate of carbon ~urnout by lowering the furnace temperature, and by using a gas containing only a low concentration of J L~
oxygen so the heat may be removed as it is produced.
However, this slow process may require many hours for completion, and during this time the furnace is not available for useful work.
We have discovered means which rapidly remove carbon deposits by reaction with a gaseous cleaning agent (burnout gas) without creating excessive tempera-tures (hot spots) at any point in the furnace. It has been found that if the furnace is maintained at the temperature normally employed for heat~treating, e.g., from about 1500F. to about 1900F. (816C to 1038C~, an atmosphere containiny substantial quantities of carbon dioxide will rapidly and completely convert any deposits oE carbon to gaseous carbon monoxide. Further, since the reaction of carbon and carbon dioxide to form carbon monoxide is endothermic, (40 kcal being absorbed per gram mole of carbon removed), the region in which carbon removal takes place is actually cooler than the remainder of the furnace, and heat must be supplied.
Upon completion of the carbon removal, which may be monitored by observing the concentration of carbon monoxide in the exit gases, the ~urnace may be put back on stream in a short time simply by flushing with the normal heat-treating atmosphere to which a small amount of a carbon dioxide scavanger, such as natural gas, has been added.
Water may also be employed for safe removal of carbon since it too reacts rapidly with carbon in a process which requires 32 kcal per gram mole of carbon removed. Water is more difficult to remove from a furnace than is carbon dioxide, and, therefore, additional time will be lost before ~he furnace is completely prepared to go back into heat-treating service. Further-more, when water is employed as a cleaning agent, itusually must be diluted with an inert carrier gas such as nitrogen to avoid condensation in cooler parts of the system such as inlet ducts, vent lines and stacks~
Carbon dioxide may be employed in admixture with an inert carrier, or if desired, may be used undiluted, in which case the most rapid clean out of the furnace will be attained.
DETA I LED DE S CR I PT I ON OF THE I NVENT I ON
-Normally furnaces containing heavy deposits of carbonaceous material (e.g. soot) are burned out with lQ air or diluted air, for example, 10% air in nitrogen.
The reason for this is the generation of hot spots when substantial amounts of soot are deposited on the radiant tubes. Oxygen reacts with carbon to form either carbon monoxide or carbon dioxide depending on the relative amounts of oxygen and carbon. This reaction is exo-thermic, by generating one gram mole of carbon monoxide at 1700F about 28 kcal would be produced; by ~enerating one gram mole of carbon dioxide at 1700F about 95 kcal would be produced. On the other hand, the reaction between carbon dioxide and carbon consumes 39 kcal per gram mole and hot spots simply cannot occur. Therefore, it was reasoned that pure carbon dioxide could be used for removing the soot and a much faster operation would result.
The following example illustrates the furnace cleaning process of the present invention.
A heat-treating furnace having a volume of 7.5 cu.
ft. was intentionally sooted by passing a mixture of nitrogen and propane through it for a period of 17 hrs.
at a temperature of 1~00F (927C). The flow rate of nitrogen was 100 standard cubic feet per hour (SCFH3 and of propane was 2.5 SCFH. A total of about four pounds of soot was deposited in the furnace. The nitrogen propane mixture was then replaced by a stream of carbon dioxide at a rate of 100 SC~1 whereupon the temperature of the furnace dropped about 60F (33.3C~, an indication of an endothermic process. The furnace atmosphere was sarnpled and analyzed a-t periodic intervals with the results as shown in the following Table I:
TABLE I
-Time Furnace Atmosphere (By Volume~
Minute _ ~ C2 % C0 7 5.49 2.42 B5.B7 13 2.05 2.37 89.74 0.92 2.37 89.74 27 0.48 3.22 91.40 34 0.28 3.89 91.26 41 0.17 7.32 88.52 47 0.11 14.61 81.79 54 0.07 21.72 75.22 6~ 0.05 30.87 66.S0 , The concentration of hydrogen, which resulted from - 20 cracking of the propane, drops rapidly as carbon dioxide sweeps through the furnace. However, only a low concen-tration of the latter appears at the exit of the furnace, most of it being converted to carbon monoxide by reaction with soot. This process occurs for about 40 minutes, at which time an abrupt rise in carbon dioxide concen-tration and a corresponding decline in carbon monoxide is ohserved as complete burnout is approached.
From these data it is estimated that approximately three pounds of carbon has been removed in a period of about 60 minutes without production of a hot spot in the furnace.
To remove the same quantity of carbon with 100 SCFH flow of pure air reguires 2.2. hours, and would ~ ê)~
result in generation of localized high temperatures at the points where the soot burns. If the normal mixture of 10% air and 90% nitrogen were employed at a flow rate of 100 SCF~, 22 hours would be re~uired to achieve 5 the same result.
The carbon dioxide level in the burnou-t mixture is preferentially 100% but could be varied between 10 and 100%. The flow of burnout gas can be as high as 300 SCFH or 40 v~lume changes. Since the gas volume is doubled upon combining with carbon, a considerable increase in gas pressure occurs in the furnace. The upper limit of the carbon dioxide flow is determined by the maximum flow the furnace is designed for. The pr~ferred carbon dioxide flow is between 10 and 40 volume changes. At smaller flows, carbon dioxide would be completely converted but the burnout would last longer. The burnout temperature is limited to the normal carburizing temperatures and will prefexentially be between 1500 and 1700F (816C and 927C). At lower temperatures burn out will be slower and less efficient.
Higher temperatures will not be a problem. The upper limit is given by the maximum operating temperature of the furnace.
In order to prepare the furnace for normal opera-tion and xeduce the carbon dioxide level a mixture of100 SCFH nitrogen and 20 SCFH natural gas was fed to the furnace. After 10 minutes the furnace atmosphere contained 20% hydrogen, 0.05% carbon dioxide, 1.6%
methane and 12% carbon monoxide. This may be considered a perfect atmosphere to start any nitrogen based carbur-izing system.
The results indicate that the proposed method of burning out a furnace results in production time savings of 1.2 up to 21 hours. At the same time the risk of tube burnout is completely eliminated.
Water vapor can be used as a component of the burn out gas since water vapor has a heat consumption of 32 kcal/grc~m mole of carbon. The water in a nitrogen gas 4~i~
mixture should be present in an amount from, by volume, 0% to 20%. However, water in the liquid form compli-cates metering it into the furnace and ~he furnace will have a high dew point. Thus it reguires at least several hours at temperature after cessation of ~ater injection to dry out the furnace.
METHOD FOR REMOVING CARBONACEOUS DEPOSITS
FROM HEAT TREATING FURNACES
TECHNICAL FIELD
This invention pertains to the removal of carbona-'ceous deposits such as soot from heat-treating furnaces used to heat treat ferrous metals under an atmosphere containing reactive carbon.
S BACKGROUND O~ THE PRIOR ART
The metallurgical industry employs heat-treating furnaces for a variety of purposes. Under certain heat-treating conditions deposits of carbon may form in the furnace. For example, in gas carburization an atmosphere containing carbon donating (reactive carbon) constituents is employed to transfer carbon to the surface of steel, thereby causing a high carbon surface layer to be formed which increases the surface hardness of the part after rapid cooling (e.g. quenching). The presence of these carbon donors in the atmosphere may ~' also lead to unwanted deposits of el~mental carbon being formed at various points in the furnace.
~ owder metallurgy involves the sintering of objects produced by compression of powdered metals. To insure S the development of adequate density, and release of the ohject from the mold, these powders contain a lubricant W}liCh is usually a carbon-containing solid, such as a metal soap. During heating in the furnace, the lubri-cant decomposes releasing volatile materials which form sooty deposits in the furnace.
Deposi-tion of soot or other carbonaceous material in the furnace is undesirable. It ~ay obstruct the flow of gases through the furnace, interfere with effective heat transfer, and in some cases, may react with high temperature alloy components of the furnace reducing their strength and durability. It is necessary periodically to remove carbon from heat-treating furnaces.
An effective way to achieve this end is to burn the carbon out with air or with air diluted with an inert gas such as nitrogen.
However, since the reaction of oxygen with carbon to form carbon dioxide is highly exothermic (96,000 calories (96 kcal) per gram mole at 1700F.) great care must be exercised to avoid overheating which can cause severe damage to the furnace or its internal components.
The effects of sooting and of the catastrophic melting of an alloy radiant heating tube during soot buxnout is shown and discussed in an article entitled, "Under-standing Conditions that Affect Performance of Heat Resisting Alloys`', Parts I and II appearing in the March and April 1979 editions of Industrial Heating, Vol. XLVI, No. 3, pp. 8-11 and Vol. XLVI, No. 4, pp.
44-47. It is customary to control the rate of carbon ~urnout by lowering the furnace temperature, and by using a gas containing only a low concentration of J L~
oxygen so the heat may be removed as it is produced.
However, this slow process may require many hours for completion, and during this time the furnace is not available for useful work.
We have discovered means which rapidly remove carbon deposits by reaction with a gaseous cleaning agent (burnout gas) without creating excessive tempera-tures (hot spots) at any point in the furnace. It has been found that if the furnace is maintained at the temperature normally employed for heat~treating, e.g., from about 1500F. to about 1900F. (816C to 1038C~, an atmosphere containiny substantial quantities of carbon dioxide will rapidly and completely convert any deposits oE carbon to gaseous carbon monoxide. Further, since the reaction of carbon and carbon dioxide to form carbon monoxide is endothermic, (40 kcal being absorbed per gram mole of carbon removed), the region in which carbon removal takes place is actually cooler than the remainder of the furnace, and heat must be supplied.
Upon completion of the carbon removal, which may be monitored by observing the concentration of carbon monoxide in the exit gases, the ~urnace may be put back on stream in a short time simply by flushing with the normal heat-treating atmosphere to which a small amount of a carbon dioxide scavanger, such as natural gas, has been added.
Water may also be employed for safe removal of carbon since it too reacts rapidly with carbon in a process which requires 32 kcal per gram mole of carbon removed. Water is more difficult to remove from a furnace than is carbon dioxide, and, therefore, additional time will be lost before ~he furnace is completely prepared to go back into heat-treating service. Further-more, when water is employed as a cleaning agent, itusually must be diluted with an inert carrier gas such as nitrogen to avoid condensation in cooler parts of the system such as inlet ducts, vent lines and stacks~
Carbon dioxide may be employed in admixture with an inert carrier, or if desired, may be used undiluted, in which case the most rapid clean out of the furnace will be attained.
DETA I LED DE S CR I PT I ON OF THE I NVENT I ON
-Normally furnaces containing heavy deposits of carbonaceous material (e.g. soot) are burned out with lQ air or diluted air, for example, 10% air in nitrogen.
The reason for this is the generation of hot spots when substantial amounts of soot are deposited on the radiant tubes. Oxygen reacts with carbon to form either carbon monoxide or carbon dioxide depending on the relative amounts of oxygen and carbon. This reaction is exo-thermic, by generating one gram mole of carbon monoxide at 1700F about 28 kcal would be produced; by ~enerating one gram mole of carbon dioxide at 1700F about 95 kcal would be produced. On the other hand, the reaction between carbon dioxide and carbon consumes 39 kcal per gram mole and hot spots simply cannot occur. Therefore, it was reasoned that pure carbon dioxide could be used for removing the soot and a much faster operation would result.
The following example illustrates the furnace cleaning process of the present invention.
A heat-treating furnace having a volume of 7.5 cu.
ft. was intentionally sooted by passing a mixture of nitrogen and propane through it for a period of 17 hrs.
at a temperature of 1~00F (927C). The flow rate of nitrogen was 100 standard cubic feet per hour (SCFH3 and of propane was 2.5 SCFH. A total of about four pounds of soot was deposited in the furnace. The nitrogen propane mixture was then replaced by a stream of carbon dioxide at a rate of 100 SC~1 whereupon the temperature of the furnace dropped about 60F (33.3C~, an indication of an endothermic process. The furnace atmosphere was sarnpled and analyzed a-t periodic intervals with the results as shown in the following Table I:
TABLE I
-Time Furnace Atmosphere (By Volume~
Minute _ ~ C2 % C0 7 5.49 2.42 B5.B7 13 2.05 2.37 89.74 0.92 2.37 89.74 27 0.48 3.22 91.40 34 0.28 3.89 91.26 41 0.17 7.32 88.52 47 0.11 14.61 81.79 54 0.07 21.72 75.22 6~ 0.05 30.87 66.S0 , The concentration of hydrogen, which resulted from - 20 cracking of the propane, drops rapidly as carbon dioxide sweeps through the furnace. However, only a low concen-tration of the latter appears at the exit of the furnace, most of it being converted to carbon monoxide by reaction with soot. This process occurs for about 40 minutes, at which time an abrupt rise in carbon dioxide concen-tration and a corresponding decline in carbon monoxide is ohserved as complete burnout is approached.
From these data it is estimated that approximately three pounds of carbon has been removed in a period of about 60 minutes without production of a hot spot in the furnace.
To remove the same quantity of carbon with 100 SCFH flow of pure air reguires 2.2. hours, and would ~ ê)~
result in generation of localized high temperatures at the points where the soot burns. If the normal mixture of 10% air and 90% nitrogen were employed at a flow rate of 100 SCF~, 22 hours would be re~uired to achieve 5 the same result.
The carbon dioxide level in the burnou-t mixture is preferentially 100% but could be varied between 10 and 100%. The flow of burnout gas can be as high as 300 SCFH or 40 v~lume changes. Since the gas volume is doubled upon combining with carbon, a considerable increase in gas pressure occurs in the furnace. The upper limit of the carbon dioxide flow is determined by the maximum flow the furnace is designed for. The pr~ferred carbon dioxide flow is between 10 and 40 volume changes. At smaller flows, carbon dioxide would be completely converted but the burnout would last longer. The burnout temperature is limited to the normal carburizing temperatures and will prefexentially be between 1500 and 1700F (816C and 927C). At lower temperatures burn out will be slower and less efficient.
Higher temperatures will not be a problem. The upper limit is given by the maximum operating temperature of the furnace.
In order to prepare the furnace for normal opera-tion and xeduce the carbon dioxide level a mixture of100 SCFH nitrogen and 20 SCFH natural gas was fed to the furnace. After 10 minutes the furnace atmosphere contained 20% hydrogen, 0.05% carbon dioxide, 1.6%
methane and 12% carbon monoxide. This may be considered a perfect atmosphere to start any nitrogen based carbur-izing system.
The results indicate that the proposed method of burning out a furnace results in production time savings of 1.2 up to 21 hours. At the same time the risk of tube burnout is completely eliminated.
Water vapor can be used as a component of the burn out gas since water vapor has a heat consumption of 32 kcal/grc~m mole of carbon. The water in a nitrogen gas 4~i~
mixture should be present in an amount from, by volume, 0% to 20%. However, water in the liquid form compli-cates metering it into the furnace and ~he furnace will have a high dew point. Thus it reguires at least several hours at temperature after cessation of ~ater injection to dry out the furnace.
Claims (9)
1. A method for removing carbonaceous deposits from a furnace utilized for heat treating ferrous metals under an atmosphere containing reactive carbon without creating hot spots in interior parts of said furnace comprising the steps of:
heating said furnace to a temperature of at least 1500°F;
injecting a burnout gas into said furnace said burnout gas consisting essentially of from 10 to 100% by volume carbon dioxide, 0 to 20% water or mixtures thereof, balance nitrogen; and continuing flow of said burnout gas into said furnace until between 10 and 40 volume changes of carbon dioxide in said furnace have occurred.
heating said furnace to a temperature of at least 1500°F;
injecting a burnout gas into said furnace said burnout gas consisting essentially of from 10 to 100% by volume carbon dioxide, 0 to 20% water or mixtures thereof, balance nitrogen; and continuing flow of said burnout gas into said furnace until between 10 and 40 volume changes of carbon dioxide in said furnace have occurred.
2. A method according to Claim 1 wherein 100% by volume carbon dioxide is injected into said furnace.
3. A method according to Claim 1 wherein after said burnout gas injection is completed said furnace is conditioned for normal operation by flowing a condi-tioning gas mixture through said furnace for a minimum of ten minutes.
4. A method according to Claim 3 wherein said conditioning gas mixture contains by volume 40% nitrogen and 10% natural gas.
5. A method according to Claim 1 wherein said flow of burnout gas containing carbon dioxide is continued while monitoring the furnace atmosphere until said furnace atmosphere passes a point at which the residual carbon dioxide has reached its lowest level.
6. A method according to Claim 1 wherein said burnout gas consists essentially of from 10 to 100% by volume carbon dioxide, balance nitrogen.
7. A method according to Claim 6 wherein after said burnout gas injection is completed said furnace is conditioned for normal operation by flowing a conditioning gas mixture through said furnace for a minimum of ten minutes.
8. A method according to Claim 7 wherein said conditioning gas mixture is formed by feeding 100 SCFH nitrogen and 20 SCFH natural gas to said furnace.
9. A method according to Claim 6 wherein said flow of burnout gas containing carbon dioxide is continued while monitoring the furnace atmosphere until said furnace atmosphere passes a point at which the residual carbon dioxide has reached its lowest level.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17864380A | 1980-08-15 | 1980-08-15 | |
| US178,643 | 1980-08-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1174461A true CA1174461A (en) | 1984-09-18 |
Family
ID=22653327
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382206A Expired CA1174461A (en) | 1980-08-15 | 1981-07-22 | Method for removing carbonaceous deposits from heat treating furnaces |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0047067A1 (en) |
| CA (1) | CA1174461A (en) |
| ZA (1) | ZA815254B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5071486A (en) * | 1986-02-06 | 1991-12-10 | University Of Dayton | Process for removing protective coatings and bonding layers from metal parts |
| US5133813A (en) * | 1990-07-03 | 1992-07-28 | Tokyo Heat Treating Company Ltd. | Gas-carburizing process and apparatus |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB604538A (en) * | 1945-11-26 | 1948-07-06 | Gen Electric Co Ltd | Improvements in or relating to the surface carburisation of steel |
| NO135330C (en) * | 1970-11-10 | 1991-03-26 | Rivenaes Ivar | PROCEDURE AND APPARATUS FOR CLEANING A COMBUSTION ENGINE OR LIKE. |
| DE2152439C3 (en) * | 1971-10-21 | 1978-04-27 | Brown, Boveri & Cie Ag, 6800 Mannheim | Process and device for preventing the formation of soot in carburizing rooms |
| IT1036474B (en) * | 1974-07-24 | 1979-10-30 | Kurita Water Ind Ltd | PROCEDURE FOR REMOVING CARBON ENGRAVINGS |
| DE2841626C2 (en) * | 1978-09-25 | 1982-06-24 | Brown, Boveri & Cie Ag, 6800 Mannheim | Process for de-sooting furnaces for fully automatic gas carburizing |
-
1981
- 1981-07-22 CA CA000382206A patent/CA1174461A/en not_active Expired
- 1981-07-30 ZA ZA815254A patent/ZA815254B/en unknown
- 1981-08-03 EP EP81303537A patent/EP0047067A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| ZA815254B (en) | 1982-08-25 |
| EP0047067A1 (en) | 1982-03-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Grabke | Thermodynamics, mechanisms and kinetics of metal dusting | |
| CA1208107A (en) | Method and apparatus for metal treatment | |
| US4461656A (en) | Low temperature hardening of the surface of a ferrous metal workpiece in a fluidized bed furnace | |
| US2501051A (en) | Siliconizing processes | |
| Rahmel et al. | Carburization–introductory survey | |
| JP2012505314A (en) | Nickel-chromium-alloy | |
| JPH06502219A (en) | metallurgy lance | |
| US3022204A (en) | Process for nitriding metals | |
| JP2006504867A (en) | Copper-based alloy resistant to metal dusting and use thereof | |
| CA1174461A (en) | Method for removing carbonaceous deposits from heat treating furnaces | |
| Grabke | Nickel-based alloys in carbonaceous gases | |
| AU8607698A (en) | Corrosion resistance of high temperature alloys | |
| US4236941A (en) | Method of producing heat treatment atmosphere | |
| US2181093A (en) | Heat treatment of metals | |
| US3539165A (en) | Apparatus for treating metallic and nonmetallic materials | |
| US2240146A (en) | Carburizing ferrous metals | |
| Stack et al. | The effect of pre-oxidation of chromia and alumina forming alloys on erosion in laboratory simulated fluidized-bed conditions | |
| US4008163A (en) | Method of preparing a saturated fluid mixture | |
| JP2718734B2 (en) | Steel pipe for boiler which is resistant to sulfidation corrosion and erosion | |
| Yi et al. | Novel internal oxidation behavior of new 17Cr2Ni2MoVNb steel | |
| US3987224A (en) | Oxygen control in continuous metal casting system | |
| Zhang et al. | The corrosion behavior of four commercial steels in reducing atmospheres containing HCl at 773–873 K | |
| US3744960A (en) | Fluid environment in a treatment zone | |
| Nishiyama et al. | Degradation of surface oxide scale on Fe-Ni-Cr-Si alloys upon cyclic coking and decoking procedures in a simulated ethylene pyrolysis gas environment | |
| Poor et al. | Furnace Atmospheres for Heat Treating |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry | ||
| MKEX | Expiry |
Effective date: 20010918 |