US3705057A - Method for treating heat exchangers and similar apparatus in thermal power plants - Google Patents
Method for treating heat exchangers and similar apparatus in thermal power plants Download PDFInfo
- Publication number
- US3705057A US3705057A US151261A US3705057DA US3705057A US 3705057 A US3705057 A US 3705057A US 151261 A US151261 A US 151261A US 3705057D A US3705057D A US 3705057DA US 3705057 A US3705057 A US 3705057A
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- US
- United States
- Prior art keywords
- heat exchangers
- thermal power
- power plants
- pressure
- protective
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- 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 - Lifetime
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
- F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
Definitions
- a method of treating heat exchangers and like apparatus used in thermal power plants for applying a protective magnetite layer to the surface of iron or steel tubes or other wall portions of the heat exchanger has the steps of subjecting the surface to a flow of steam at a temperature above 220 C. in the absence of air and simultaneously, during the time the protective layer is applied, subjecting the tube to a pressure differential corresponding approximately to the pressure differential to which the tube is subjected in actual use.
- My invention relates to a method for treating heat exchangers and similar apparatus used in thermal power plants. It is desirable to produce magnetite protective layers on the surfaces of heat exchanger tubes or other wall portions made of steel, for the purpose of preventing damage due to corrosion. Such protective layers can be applied on iron or steel surfaces with the aid of steam, without admitting air and at temperatures above 220' C., according to the reaction:
- the wall portions to be treated for production of protective layers are subjected to difference pressures which correspond approximately to the pressure values that occur during operation.
- the steam pressure may be adjusted so that it is close to the operating pressure of the subsequent working medium.
- the vapor pressure during the production of protective layers may amount inside the tubes, to about to of the pressure difference which occurs during subsequent operation, while the pressure outside the tubes corresponds approximately to atmospheric pressure.
- a difference pressure of 23 kp./cm. prevails during operation.
- the protective layer is produced at a vapor pressure inside the tubes 1 of 20 kp./cm. and at an atmospheric pressure in the region 2 surrounding the tubes, the protective layer will have been formed at conditions which are somewhat below the conditions encountered in later operation with respect to expansions. During subsequent operation this leads to a slight tensile stress and, when the exchanger is shut down there is a compressive stress in the magnetite protective layer. Both stresses may be withstood without fissures developing so that the magnetite layer can maintain its protective function during at all occurring pressures.
- the total range to be bridged depends upon how the tubular wall thickness is dimensioned.
- the invention makes it possible, however to cover pressure ranges which without entailing a danger of damage, are at least three times as high as those of the methods used heretofore.
- Method of treating heat exchangers and like apparatus used in thermal power plans for applying a protective magnetite layer to the surface of iron or steel tubes or other wall portions of heat exchangers comprising the steps of subjecting said surface to a fiow of steam at a temperature above 220 C. in the absence of air and simultaneously, during the time the protective layer is applied, subjecting said tube to a pressure differential corresponding approximately to the pressure differential to which said tube is subjected in actual use.
- Method of applying a layer of protective magnetite to the surface of iron or steel tubes or other wall portions of heat exchangers and like apparatus for use in thermal power plants comprising the steps of applying a protective layer of magnetite to said surface while, simultaneously, subjecting said surface to a flow of steam at a temperature above 220 C. in the ab- References Cited UNITED STATES PATENTS 2,399,758 5/1946 Pierri 1486.35 X
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Heat Treatment Of Articles (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
A METHOD OF TREATING HEAT EXCHANGERS AND LIKE APPARATUS USED IN THERMAL POWER PLANTS FOR APPLYING A PROTECTIVE MAGNETITE LAYER TO THE SURFACE OF IRON OR STEEL TUBES OR OTHER WALL PORTIONS OF THE HEAT EXCHANGER HAS THE STEPS OF SUBJECTING THE SURFACE TO A FLOW OF STEAM AT A TEMPERATURE ABOVE 220* C. IN THE ABSENCE OF AIR AND SIMULTANEOUSLY, DURING THE TIME THE PROTECTIVE LAYER IS APPLIED SUBJECTING THE TUBE TO A PRESSURE DIFFERENTIAL CORRESPONDING APPROXIMATELY TO THE PRESSURE DIFFERENTIAL TO WHICH THE TUBE IS SUBJECTED IN ACTUAL USE.
Description
Dec. 5, 1972 F. KELP 3,795,057
METHOD FOR TREATING HEAT EXCHANGERS AND SIMILAR APPARATUS IN THERMAL POWER PLANTS Filed June 9, 1971 United States Patent METHOD FOR TREATING HEAT EXCHANGERS AND SIMILAR APPARATUS IN THERMAL POWER PLANTS Fritz Kelp, Erlangen, Germany, assignor to Kraftwerk Union Aktiengesellschaft, Mulheim (Ruhr), Germany Filed June 9, 1971, Ser. No. 151,261 Claims priority, application Germany, June 13, 1970, P 20 29 249.3 Int. Cl. F281 19/02 US. Cl. 148-635 4 Claims ABSTRACT OF THE DISCLOSURE A method of treating heat exchangers and like apparatus used in thermal power plants for applying a protective magnetite layer to the surface of iron or steel tubes or other wall portions of the heat exchanger has the steps of subjecting the surface to a flow of steam at a temperature above 220 C. in the absence of air and simultaneously, during the time the protective layer is applied, subjecting the tube to a pressure differential corresponding approximately to the pressure differential to which the tube is subjected in actual use.
My invention relates to a method for treating heat exchangers and similar apparatus used in thermal power plants. It is desirable to produce magnetite protective layers on the surfaces of heat exchanger tubes or other wall portions made of steel, for the purpose of preventing damage due to corrosion. Such protective layers can be applied on iron or steel surfaces with the aid of steam, without admitting air and at temperatures above 220' C., according to the reaction:
At lower temperatures, this reaction would take place under otherwise the same conditions, only very slowly or not at all.
It has been discovered that, though uniform magnetite layers could be provided in this manner on the surfaces of heat exchanger tubes, the protective effectiveness of these layers may prove unsatisfactory. When a heat exchanger treated in the foregoing manner is operated, as a result of the pressure in the tubes conjointly with thermal influences, expansion phenomena will occur in the tubular wall which could easily be sustained by the heat exchanger material itself within the elastic range but which will cause the relatively brittle although relatively well-adhering, magnetite layer to tear apart. Hence tears or fissures may occur at whose bottom metallic bare iron or metallic bare steel may lie unprotected, so that corrosion will set in there and tend to expand even farther.
Accordingly, it is an object of my invention to provide a method of treating heat exchangers and the like for applying a protective magnetite layer to the surface of iron or steel tubes or other wall portions of the heat exchanger. Subsidiary to this object, it is an object of my invention to provide a method of treating heat exchangers to permit protective magnetite layers to be applied to pertinent surfaces of the heat exchangers which will not develop tears or fissures in normal operational use.
It is another object of my invention to provide a method of applying a layer of protective magnetite to the surface of iron or steel tubes or other wall portions of heat exchangers which will not develop tears or fissures during normal operational use.
Based on this recognition and in accordance with my invention, the wall portions to be treated for production of protective layers are subjected to difference pressures which correspond approximately to the pressure values that occur during operation. When steam is passed through, the steam pressure may be adjusted so that it is close to the operating pressure of the subsequent working medium. For treating feedwater preheaters, the vapor pressure during the production of protective layers may amount inside the tubes, to about to of the pressure difference which occurs during subsequent operation, while the pressure outside the tubes corresponds approximately to atmospheric pressure.
The invention will now be discussed with reference to the drawing which illustrates, in schematic representation, a heat exchanger which can be treated according to the method of the invention.
If such a heat exchanger, for example, a low pressure feedwater preheater is later operated with a feedwater pressure of 25 kp./cm. in the tubes and a steam pressure of 2 kp./cm. outside the tubes, then a difference pressure of 23 kp./cm. prevails during operation. If the protective layer is produced at a vapor pressure inside the tubes 1 of 20 kp./cm. and at an atmospheric pressure in the region 2 surrounding the tubes, the protective layer will have been formed at conditions which are somewhat below the conditions encountered in later operation with respect to expansions. During subsequent operation this leads to a slight tensile stress and, when the exchanger is shut down there is a compressive stress in the magnetite protective layer. Both stresses may be withstood without fissures developing so that the magnetite layer can maintain its protective function during at all occurring pressures.
The total range to be bridged depends upon how the tubular wall thickness is dimensioned. The invention makes it possible, however to cover pressure ranges which without entailing a danger of damage, are at least three times as high as those of the methods used heretofore.
While the invention has been described by means of a specific example and in a specific embodiment, I do not wish to become limited thereto for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.
I claim:
1. Method of treating heat exchangers and like apparatus used in thermal power plans for applying a protective magnetite layer to the surface of iron or steel tubes or other wall portions of heat exchangers, said method comprising the steps of subjecting said surface to a fiow of steam at a temperature above 220 C. in the absence of air and simultaneously, during the time the protective layer is applied, subjecting said tube to a pressure differential corresponding approximately to the pressure differential to which said tube is subjected in actual use.
2. Method according to claim 1, wherein the pressure of said steam is adjusted to correspond to the pressure of the medium traversing said tube during actual use.
3. Method according to claim 1, wherein the tubes of feed-water preheaters are treated for facilitating the ap- 3 plication of said protective layer, the pressure of said steam within said tube being adjusted during the application of said layer to correspond to within 80 to 90% of the pressure difference occurring during actual use of the preheater while the pressure outside said tube corresponds to atmospheric pressure.
4. Method of applying a layer of protective magnetite to the surface of iron or steel tubes or other wall portions of heat exchangers and like apparatus for use in thermal power plants, said method comprising the steps of applying a protective layer of magnetite to said surface while, simultaneously, subjecting said surface to a flow of steam at a temperature above 220 C. in the ab- References Cited UNITED STATES PATENTS 2,399,758 5/1946 Pierri 1486.35 X
RALPH S. KENDALL, Primary Examiner US. Cl. X.R. 165-133
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19702029249 DE2029249A1 (en) | 1970-06-13 | 1970-06-13 | Process for the treatment of heat exchangers and similar devices in thermal power stations |
Publications (1)
Publication Number | Publication Date |
---|---|
US3705057A true US3705057A (en) | 1972-12-05 |
Family
ID=5773883
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US151261A Expired - Lifetime US3705057A (en) | 1970-06-13 | 1971-06-09 | Method for treating heat exchangers and similar apparatus in thermal power plants |
Country Status (5)
Country | Link |
---|---|
US (1) | US3705057A (en) |
AT (1) | AT300493B (en) |
CH (1) | CH564609A5 (en) |
DE (1) | DE2029249A1 (en) |
ZA (1) | ZA713797B (en) |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3969153A (en) * | 1974-01-18 | 1976-07-13 | Hitachi, Ltd. | Method of manufacturing a stainless steel boiler tube with anticorrosive coating |
US3990862A (en) * | 1975-01-31 | 1976-11-09 | The Gates Rubber Company | Liquid heat exchanger interface and method |
US4082575A (en) * | 1976-04-21 | 1978-04-04 | Thermacore, Inc. | Production of liquid compatible metals |
US4082140A (en) * | 1972-11-14 | 1978-04-04 | Austral-Erwin Engineering Company | Heat exchange method |
US4127164A (en) * | 1972-11-14 | 1978-11-28 | Austral-Erwin Engineering Co. | Heat exchange apparatus |
US5786296A (en) * | 1994-11-09 | 1998-07-28 | American Scientific Materials Technologies L.P. | Thin-walled, monolithic iron oxide structures made from steels |
US6051203A (en) * | 1996-04-30 | 2000-04-18 | American Scientific Materials Technologies, L.P. | Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures |
US6461562B1 (en) | 1999-02-17 | 2002-10-08 | American Scientific Materials Technologies, Lp | Methods of making sintered metal oxide articles |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3145236C2 (en) * | 1981-11-13 | 1984-11-22 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8000 München | Process for the production of deformation-resistant oxidic protective layers |
-
1970
- 1970-06-13 DE DE19702029249 patent/DE2029249A1/en active Pending
-
1971
- 1971-04-29 CH CH621471A patent/CH564609A5/xx not_active IP Right Cessation
- 1971-06-03 AT AT480471A patent/AT300493B/en not_active IP Right Cessation
- 1971-06-09 US US151261A patent/US3705057A/en not_active Expired - Lifetime
- 1971-06-11 ZA ZA713797A patent/ZA713797B/en unknown
Cited By (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4082140A (en) * | 1972-11-14 | 1978-04-04 | Austral-Erwin Engineering Company | Heat exchange method |
US4127164A (en) * | 1972-11-14 | 1978-11-28 | Austral-Erwin Engineering Co. | Heat exchange apparatus |
US3969153A (en) * | 1974-01-18 | 1976-07-13 | Hitachi, Ltd. | Method of manufacturing a stainless steel boiler tube with anticorrosive coating |
US3990862A (en) * | 1975-01-31 | 1976-11-09 | The Gates Rubber Company | Liquid heat exchanger interface and method |
US4093755A (en) * | 1975-01-31 | 1978-06-06 | The Gates Rubber Company | Method for making a liquid heat exchanger coating |
US4082575A (en) * | 1976-04-21 | 1978-04-04 | Thermacore, Inc. | Production of liquid compatible metals |
US5786296A (en) * | 1994-11-09 | 1998-07-28 | American Scientific Materials Technologies L.P. | Thin-walled, monolithic iron oxide structures made from steels |
US5814164A (en) * | 1994-11-09 | 1998-09-29 | American Scientific Materials Technologies L.P. | Thin-walled, monolithic iron oxide structures made from steels, and methods for manufacturing such structures |
US6051203A (en) * | 1996-04-30 | 2000-04-18 | American Scientific Materials Technologies, L.P. | Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures |
US6071590A (en) * | 1996-04-30 | 2000-06-06 | American Scientific Materials Technologies, L.P. | Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures |
US6077370A (en) * | 1996-04-30 | 2000-06-20 | American Scientific Materials Technologies, L.P. | Thin-walled monolithic metal oxide structures made from metals, and methods for manufacturing such structures |
US6461562B1 (en) | 1999-02-17 | 2002-10-08 | American Scientific Materials Technologies, Lp | Methods of making sintered metal oxide articles |
Also Published As
Publication number | Publication date |
---|---|
CH564609A5 (en) | 1975-07-31 |
DE2029249A1 (en) | 1971-12-23 |
AT300493B (en) | 1972-07-25 |
ZA713797B (en) | 1972-01-26 |
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