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US3306235A - Corrosion reducing method and material for furnaces - Google Patents

Corrosion reducing method and material for furnaces Download PDF

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Publication number
US3306235A
US3306235A US406500A US40650064A US3306235A US 3306235 A US3306235 A US 3306235A US 406500 A US406500 A US 406500A US 40650064 A US40650064 A US 40650064A US 3306235 A US3306235 A US 3306235A
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US
United States
Prior art keywords
corrosion
furnace
tubes
additive
furnaces
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 - Lifetime
Application number
US406500A
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English (en)
Inventor
Everett C Lewis
John T Reese
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Combustion Engineering Inc
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Combustion Engineering Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to US342680A priority Critical patent/US3306255A/en
Application filed by Combustion Engineering Inc filed Critical Combustion Engineering Inc
Priority to US406500A priority patent/US3306235A/en
Priority to ES0317733A priority patent/ES317733A1/es
Priority to GB40862/65A priority patent/GB1097886A/en
Priority to FR35325A priority patent/FR1452332A/fr
Priority to BE671049A priority patent/BE671049A/xx
Priority to NL6513625A priority patent/NL6513625A/xx
Application granted granted Critical
Publication of US3306235A publication Critical patent/US3306235A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F15/00—Other methods of preventing corrosion or incrustation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/025—Devices and methods for diminishing corrosion, e.g. by preventing cooling beneath the dew point
    • 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

Definitions

  • This invention relates to additive materials for use in reducing the corrosion of heat transfer surfaces in large furnaces due to the action of combustion products and more particularly to a material for and method of obtaining better adhesion of the additive materials to the heat transfer surfaces.
  • a problem of increasing importance in modern furnaces and high capacity steam generators in power plants is corrosion and fouling of tube surfaces as a result of the combined action of corrosive combustion products in the gases and the existing high temperatures. Such corrosion weakens the tubes and leaves scaled deposits which have a deleterious effect on the heat transfer capacity of the furnace.
  • One method of achieving increased adhesion is to mix the additives with water and to spray the resultant slurry onto the tubes through the soot-blowers which are common to most large furnaces.
  • the water slurry in some manner tends to increase the adhesion to some degree.
  • this slurry method is not entirely satisfactory since greater adhesion is desired than can be achieved thereby, and the spraying of the water on the high temperature tubes produces thermal shock and early failure of the tubes.
  • a particular object of the invention is to provide a furnace additive mixture incorporating a material which will increase the adherence of the additives.
  • FIG. 1 schematically illustrates a steam generator to which the present method may be applied
  • FIG. 2 is an elevational view of a device for admitting the additives of the present invention to the steam generator; and I FIG. 3 is a graph illustrating the effect of theadditive constituent of the present inventio
  • a typical boiler furnace or steam generator having a combustion chamber 10 in which a solid fuel, such as pulverized coal, is burned.
  • the fuel is introduced into the-furnace by means of burners 12, while the combustion air enters through wind boxes 14.
  • the combustion gases generated pass upwardly through the chamber 10, through the horizontal gas pass 16, down through the vertical gas pass 18, and out the lower end thereof to the stack (not shown).
  • Feedwater is supplied to the economizer 20 by means of header 21, where the water is heated to a certain extent. This heated water then flows to the header 22, through the tubes 23 to the outlet header 24, and from there to the steam and water drum 26.
  • the steam separates from the water and flows on to distribution header 34.
  • the steam passes fromthe header 34 down through the tubes 36 to the supply headers 38 and then to the primary superheaters 40 and 42.
  • the superheated steam then flows to the final superheater section 44 by way of the header 45, and from there to a turbine (not shown).
  • Modern steam generators of the type illustrated in FIG. 1 are characterized by large physical dimensions. Thus, one unit having a capacity of 1,200,000 pounds of steam per hour extends upwardly about 170 feet from its foundation with the furnace measuring 28 feet from front to rear and being 40 feet wide.
  • the invention is, of course, also applicable to furnaces of other capacities, dimensions and types.
  • Combustion gases from the furnace entering into and passing over the superheater 44 will typically be at a temperature within the range from about 1500 F. to about 2500 F. Gas-side corrosion and fouling is most severe on the high temperature tubes of the superheater 44 and the reheaters 46 and 47. Steam outlet temperatures from these tubes may be in the range from 1000 F. to 1200 F. and the tube metal temperatures may be as high as 1300 F.
  • the present invention is carried out by introducing the additive mixture into the steam generator at locations which will give adequate and relatively uniform coverage of the superheater and reheater tubes.
  • locations which will give adequate and relatively uniform coverage of the superheater and reheater tubes.
  • the exact locations and the required number of locations will, of course, vary from furnace to furnace.
  • a plurality of additive supply tubes 50 have been illustrated in FIG. 1. These tubes terminate in nozzles which protrude through suitable access openings in the furnace wall and which are located so as to give a distribution of the additive material to adequately cover superheater 44 and reheaters 46 and 47.
  • FIG. 2 Apparatus for feeding a dry additive mixture prepared in accordance with the present invention is illustrated in FIG. 2.
  • the mixture is stored in a conical feeder 52 and fed from the bottom thereof into the inclined chute means 54.
  • Both the conical feeder and the chute means are vibrated by means 56 and 58 respectively to keep the dry material flowing properly from the cone and the chute.
  • These vibrating means 56 and 58 are operated from the control means 60. Any conventional vibrating apparatus may be used for this purpose.
  • the additive mixture drops from the chute means 54 into the funnel 62.
  • the funnel is attached to and part of a simple aspirator 64 into which air is fed from line 66. The air will aspirate the additive mixture into the aspirator 64 and carry the mixture into the furnace through the line or lines 50.
  • the present invention involves the mixing of sodium tetraborate with conventional additive materials to improve the adhesion of the additives to the desired tube surfaces.
  • Sodium tetraborate is particularly desirable since it not only performs this function satisfactorily but it is also a comparatively inexpensive material.
  • borax Na B O .10H O
  • the anhydrous or the penta-hydrate forms could also be used but the problem of caking due to water absorption wouldthen have to be contendedwith.
  • the deca-hydrate when introduced into the furnace will melt (at about 167 F.) and then lose its water of hydration.
  • the anhydride will then melt again at about 1366 F. and will deposit on the tubes in this molten, sticky condition and provide a bonding agent to bond the corrosion retarding additive material to the tubes.
  • the graph of 'FIG. 3 illustrates the effect of sodium tetraborate on the ability of the additive materials to adhere to the tube surfaces.
  • the graph shows the relationship between the percent borax in the additive mixture fed to the test furnace and the percentage of the material impinging upon the tubes which adheres thereto.
  • the impinging material is calculated by multiplying the total material introduced into the furnace by the ratio of the projected tube area to the total gas pass area.
  • projected tube area is meant the cross sectional area of the gas pass which is filled with tubes. The graph therefore indicates the percentage of the material which actually adheres relative to that which theoretically strikes the tubes and has an opportunity to adhere.
  • Curve A shows the percentage of the total impinging material which will adhere while curve B shows the percentage of the impinging additive, in this case magnesium oxide, which adheres.
  • the borax and the magnesium oxide will deposit in approximately equal proportions by weight and thus a 50-50 mixture of the two materials by weight is a desirable mixture although the invention is not limited thereto since the addition of any amount of borax has the desirable effect.
  • the amount of additive required per unit period of time for a particular size furnace depends primarily upon the tube metal temperature and the corrosiveness of the combustion products and thus the amounts may vary widely. Accordingly, it is not feasible to specify in advance the amount of any particular additive mixture required for a particular furnace. The amounts must be determined under the operating conditions and adjusted to effectively reduce the corrosion.
  • a preferred additive for use in the present invention with the sodium tetraborate is magnesium oxide which was used in the test illustrated in the graph of FIG. 3.
  • This material is commercially available and ulitized as an additive in either the -200 or 325 mesh size range.
  • a typical utilization rate for such an additive by itself without sodium tetraborate might be on the order of 720 pounds per 24 hours in a steam generator with a capacity of 1,200,000 pounds of steam per hour although, as previously stated, this can vary widely. This could be introduced continuously throughout the 24-hour period, at various intervals or all at one time. This latter procedure, however, would not be the most desirable since a large single application would tend to build up an excessively thick coating on the tubes and thus reduce the heat transfer rate to an unacceptably low level.
  • the preferred embodiment of the present invention would, therefore, involve the mixing of magnesium oxide of the stated commercial grade with an equal portion of borax by weight and introducing the resulting mixture into the steam generator at the required rates.
  • the rate of application would, of course, be far less with the borax added than without.
  • the present invention may, however, be applied to a variety of additive materials.
  • One group of such materials is the alkaline earth oxides which will react with 50;; or acid salts produced in coal ash deposits.
  • the present invention is intended to be applicable not only to the additive materials specifically mentioned 'but to all additives which exhibit the same adhering problems and to which the invention would be beneficial. It will therefore be understood that the examples given above are for illustrative purposes only and that additions thereto or alterations thereof may be made without departing from the s ulcer of this invention as defined by the following claims.
  • a method of reducing corrosion of heat transfer surfaces due to the action of combustion products in a steam generator comprising applying a mixture of a corrosion retardant material and sodium tetraborate to the surfaces subject to said corrosion.
  • a method of reducing corrosion of heat transfer surfaces due to the action of combustion products in a steam generator comprising introducing into said steam generator a mixture of a corrosion retardant material and sodium tetraborate so that said mixture will impinge upon and deposit on said heat transfer surfaces.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Incineration Of Waste (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
US406500A 1964-02-05 1964-10-26 Corrosion reducing method and material for furnaces Expired - Lifetime US3306235A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US342680A US3306255A (en) 1964-02-05 1964-02-05 Dampening apparatus for planographic printing
US406500A US3306235A (en) 1964-10-26 1964-10-26 Corrosion reducing method and material for furnaces
ES0317733A ES317733A1 (es) 1964-10-26 1965-09-23 Un metodo de reducir la corrosion de superficies de transmision de calor, debida a la accion de productos de combustion en un hogar.
GB40862/65A GB1097886A (en) 1964-10-26 1965-09-24 Method of reducing corrosion of heat transfer surfaces
FR35325A FR1452332A (fr) 1964-10-26 1965-10-18 Perfectionnements apportés à la protection des surfaces d'échange de chaleur à l'encontre de la corrosion
BE671049A BE671049A (xx) 1964-10-26 1965-10-18
NL6513625A NL6513625A (xx) 1964-10-26 1965-10-21

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US406500A US3306235A (en) 1964-10-26 1964-10-26 Corrosion reducing method and material for furnaces
BE671049A BE671049A (xx) 1964-10-26 1965-10-18

Publications (1)

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US3306235A true US3306235A (en) 1967-02-28

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Country Status (4)

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US (1) US3306235A (xx)
BE (1) BE671049A (xx)
GB (1) GB1097886A (xx)
NL (1) NL6513625A (xx)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406042A (en) * 1965-12-14 1968-10-15 Cons Edison Co New York Inc Process for corrosion control
US3886872A (en) * 1972-03-25 1975-06-03 Nitro Nobel Ab Method and composition for removal of soot and deposits from heat exchange surfaces of combustion units
DE3329567A1 (de) * 1983-08-16 1985-03-21 Hölter, Heinz, Dipl.-Ing., 4390 Gladbeck Fossile verbrennungskessel mit chemisorptionseinbauten
EP0188063A1 (en) * 1984-12-03 1986-07-23 W.R. Grace & Co. Method of inhibiting cold end corrosion in boilers
US4629603A (en) * 1984-12-03 1986-12-16 W. R. Grace & Co. Method of inhibiting cold end corrosion in boilers
US4968231A (en) * 1988-02-23 1990-11-06 Bernard Zimmern Oil-free rotary compressor with injected water and dissolved borate
WO2003001113A1 (en) * 2001-06-26 2003-01-03 Pure Fire Technologies Ltd. An incineration process using high oxygen concentrations
WO2011131842A3 (en) * 2010-04-23 2012-05-03 Metso Power Oy A boiler and a superheater, as well as a method
US20150114320A1 (en) * 2013-10-29 2015-04-30 Emerson Process Management Power & Water Solutions, Inc. Steam temperature control using model-based temperature balancing

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10143136C2 (de) * 2001-09-03 2002-11-14 Siegfried T Gellermann Verminderung der Hochtemperatur-Halogen-Korrosion in Verbrennungsanlagen durch den Einsatz von Aluminium-Verbindungen in Wirkstoff-Mischungen

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR795919A (fr) * 1934-10-04 1936-03-25 Procédé de combustion de combustibles pulvérisés
US2412809A (en) * 1944-06-21 1946-12-17 Comb Eng Co Inc Corrosion reduction in heat exchangers
US2859146A (en) * 1956-07-09 1958-11-04 Republic Steel Corp Method of treating galvanized metal to inhibit corrosion
US3234580A (en) * 1961-07-19 1966-02-15 Julian W Keck Treatment of heat exchanger surfaces

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR795919A (fr) * 1934-10-04 1936-03-25 Procédé de combustion de combustibles pulvérisés
US2412809A (en) * 1944-06-21 1946-12-17 Comb Eng Co Inc Corrosion reduction in heat exchangers
US2859146A (en) * 1956-07-09 1958-11-04 Republic Steel Corp Method of treating galvanized metal to inhibit corrosion
US3234580A (en) * 1961-07-19 1966-02-15 Julian W Keck Treatment of heat exchanger surfaces

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3406042A (en) * 1965-12-14 1968-10-15 Cons Edison Co New York Inc Process for corrosion control
US3886872A (en) * 1972-03-25 1975-06-03 Nitro Nobel Ab Method and composition for removal of soot and deposits from heat exchange surfaces of combustion units
DE3329567A1 (de) * 1983-08-16 1985-03-21 Hölter, Heinz, Dipl.-Ing., 4390 Gladbeck Fossile verbrennungskessel mit chemisorptionseinbauten
EP0188063A1 (en) * 1984-12-03 1986-07-23 W.R. Grace & Co. Method of inhibiting cold end corrosion in boilers
US4629603A (en) * 1984-12-03 1986-12-16 W. R. Grace & Co. Method of inhibiting cold end corrosion in boilers
US4968231A (en) * 1988-02-23 1990-11-06 Bernard Zimmern Oil-free rotary compressor with injected water and dissolved borate
WO2003001113A1 (en) * 2001-06-26 2003-01-03 Pure Fire Technologies Ltd. An incineration process using high oxygen concentrations
US20040182292A1 (en) * 2001-06-26 2004-09-23 Yoram Shimrony Incineration process using high oxygen concentrations
US6952997B2 (en) 2001-06-26 2005-10-11 Pure Fire Technologies Ltd. Incineration process using high oxygen concentrations
WO2011131842A3 (en) * 2010-04-23 2012-05-03 Metso Power Oy A boiler and a superheater, as well as a method
US20130068175A1 (en) * 2010-04-23 2013-03-21 Metso Power Oy Boiler and a superheater, as well as a method
CN103026137A (zh) * 2010-04-23 2013-04-03 美特索电力公司 锅炉和过热器以及方法
US20150114320A1 (en) * 2013-10-29 2015-04-30 Emerson Process Management Power & Water Solutions, Inc. Steam temperature control using model-based temperature balancing
US9841185B2 (en) * 2013-10-29 2017-12-12 Emerson Process Management Power & Water Solutions, Inc. Steam temperature control using model-based temperature balancing

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Publication number Publication date
BE671049A (xx) 1966-04-18
GB1097886A (en) 1968-01-03
NL6513625A (xx) 1966-04-27

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