EP0010390A1 - Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen - Google Patents

Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen Download PDF

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Publication number
EP0010390A1
EP0010390A1 EP79302132A EP79302132A EP0010390A1 EP 0010390 A1 EP0010390 A1 EP 0010390A1 EP 79302132 A EP79302132 A EP 79302132A EP 79302132 A EP79302132 A EP 79302132A EP 0010390 A1 EP0010390 A1 EP 0010390A1
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EP
European Patent Office
Prior art keywords
additive
combustion
amount
combustion gases
cold
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Granted
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EP79302132A
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English (en)
French (fr)
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EP0010390B1 (de
Inventor
Richard J. Sujdak
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BetzDearborn Europe Inc
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Betz International Inc
Betz Europe Inc
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Priority claimed from US05/950,960 external-priority patent/US4185071A/en
Priority claimed from US06/019,687 external-priority patent/US4206172A/en
Application filed by Betz International Inc, Betz Europe Inc filed Critical Betz International Inc
Publication of EP0010390A1 publication Critical patent/EP0010390A1/de
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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
    • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/02—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in air or gases by adding vapour phase inhibitors

Definitions

  • the sulfur in the fuel is converted to sulfur dioxide and sulfur trioxide.
  • sulfur trioxide and water vapor are in equilibrium with sulfuric acid.
  • Below about 450°F essentially all of the SO 3 is converted to H 2 SO 4 for typical flue gas compositions of oil fired boilers.
  • the resulting sulfuric acid condenses upon metal surfaces which are at temperatures below the acid dewpoint. Corrosion results from the attack of the condensed sulfuric acid on the metals.
  • the basic area to which the present invention is directed is often referred to in the industry as the "cold-end" of a boiler. This area is generally the path in the boiler system that the combustion gases follow after the gases have, in fact, performed their primary service of producing and/or superheating steam.
  • the last stages through which the hot combustion gases flow include the enconom- izer, the air heater, the collection equipment or electrostatic precipitator, and then the stack through which the gases are discharged.
  • the present invention is drawn to the present inventor's discovery of ethylene polyamines optionally in combination with aliphatic, water-soluble alkanolamines, as cold-end additives. It was determined that if this additive is fed, preferably in droplet form, and preferably as an aqueous solution, to the moving combustion gases upstream of the cold-end surfaces to be treated and preferably at a point where the gases are undergoing turbulence, it will travel along with the gases as vapor and/or liquid droplets and deposit on the downstream cold-end surfaces. It is understood that any reference to ethylene polyamine is intended to include mixtures of such compounds and any reference to alkanolamine is intended to include mixtures thereof. While a point of turbulence of the combustion gases is a preferred feed.
  • a point of laminar gas flow could also be used, provided that suitable mechanical means are utilized to create a zone of relative turbulence for proper treatment distribution.
  • suitable mechanical means are utilized to create a zone of relative turbulence for proper treatment distribution.
  • an increased number of spray nozzles may be suitably arranged within a gas flow conduit to provide adequate treatment distribution.
  • the invention in addition to providing a method of reducing the amount of sulfuric acid corrosion of metal parts at the cold-end of a combustion system also provides a composition for such use which comprises (i) aliphatic, water-soluble alkanolamine, and (ii) ethylene polyamine.
  • ethylene polyamines is intended to include hydrocarbon chains consisting of at least two amino groups connected by ethylene group(s). For example, the lowest homolog in the series would be ethylene diamine having the following structure:
  • ethylene polyamines according to the present invention could best be described by the following:
  • n is 0. It is the present inventor's opinion that there is no upper limit for n in Formula I other than that based on the commercial availability of the material.
  • the highest homolog tested was poly(ethylenimine) having the formula: which material had an average molecular weight of about 50,000 to 100,000; and, therefore, n was about 1000 to 2500. While all of the compounds tested had ethylene groups connecting the amino groups, it is believed that other lower alkyl interconnecting groups could be used. For example, it is the present inventor's belief that trimethylene or tetramethylene groups are suitable equivalents for the ethylene group. However, preliminary testing has indicated that hexamethylene interconnecting groups are unsuitable for the purpose.
  • the additive can be fed neat; however, an aqueous solution of additive is preferred. Due to its high solubility in water, the concentration of actives in the aqueous solution could, of course, vary over a wide range, depending only on economics of handling and shipment and the characteristics of the feed system. For example, the additive could be shipped neat and diluted at the point of application. If dilution at the point of application is undesirable or not possible,. then the additive would be sent pre-diluted. Due to costs of shipment and handling, it would be undesirable to ship very dilute aqueous solutions. The preferred lower concentration limit would be about 5% actives on a weight basis, with the most preferred lower limit being about 15%. The upper concentration limit could approach 100%, however, about 60% represents the preferred upper limit.
  • the additive is preferably added to the combustion gases upstream, in the direction of flow of the combustion gases through the combustion system, of the metal parts, and may be added to the combustion gases at a point of turbulence or at a point of laminar flow.
  • the additive may be added in droplet form, it may be added in aqueous form, it may be sprayed into the combustion gases.
  • the additive could be sprayed at a point of turbulence of the combustion gases upstream of the problem area using any well known atomizing spray nozzle(s).
  • precautions should be taken to ensure that the problem areas will encounter treated flue gas. For instance, if the problem area is located centrally within a flow conduit for the combustion gases, the spray should be directed into the conduit in such a manner as to ensure that a sufficient amount of additive is present in the centre of the conduit upon reaching the location of the problem area.
  • an axially located spray nozzle which sprays the additive in the same direction that the combustion gases flow would be recommended for such a centrally located problem area. While the additive could be fed neat an aqueous solution is preferred.
  • the amount of additive used could vary over a wide range depending on the nature and severity of the problem to be solved and would be a function of the sulfur content of the oil.
  • the particular species is also seen to be an important consideration with respect to feedrate. For example,for a fuel oil containing 1% sulfur, .05 mole of triethylenetetramine per barrel (m/bbl) of fuel oil consumed has proven to be efficacious; while only .0004 mole of high molecular weight poly(ethyleninine) per barrel of fuel oil consumed (m/bb1) was required to do the job. It is the inventor's opinion that the upper limit would depend only on economic considerations.
  • the upper limit would be considered to be about 1 m/bb1 based on economic considerations, with about 0.5 m/bb1 representing a preferred upper limit.
  • the active alkanolamine could be fed in an amount as low as about 0.05 m/bbl.
  • the preferred lower limit is about 0.1 m/bb1.
  • the amount of active alkanolamine could be as high as about 1 m/bb1, with about 0.75 m/bb1, representing the preferred upper limit.
  • the inventive additive is considered to comprise from about .0004 to about 0.95 m/bb1 of ethylene polyamine and from about 0.05 to about 1 m/bb1 of alkanolamine.
  • the preferred relative proportions are from about 0.1 to about 0.5 m/bb1 ethylene polyanine and from about 0.1 to about 0.75 m/bb1 alkanolamine. Based on economic considerations, the total amount of active additive should not exceed about 1.1 m/bbl.
  • the temperature of the combustion gases at the point of feed is typically about 400°F to 750°F, but this range could widen depending on the gas temperature at the furnace exit.
  • a cold-end additive should be capable of travelling; along with the combustion gases and depositing on the downstream cold-end surfaces to be treated, the various additives tested were sprayed, using a standard atomizing spray nozzle arrangement, into the combustion gases at a point of turbulence located upstream of the air-cooled probe.
  • the boiler was taken tbrough a soot blowing cycle, and the burner tip was manually cleaned. The boiler was then base loaded for one hour prior to initiating testing. Fuel oil of precisely the same composition was fired over a given period of time to ensure reproducibility of baseline data throughout the period. However, for critical testing, daily determination of baseline data is recommended.
  • the boiler was fired with number 6 grade fuel oil containing 1% sulfur (by weight). The oil was preheated to 170°F and atomized with steam. Combustion air was at ambient temperature. Flue gas temperatures at the sampling point ranged from 440°F to 480°F.
  • the sulfuric acid dewpoint using either a Land Dewpoint Meter or a corrosion probe was typically 262°F. Using a Research Appliance Corporation sampling device, the concentration of SO 3 was determined to be about 7 parts per million parts of combustion gas (ppm, on volume basis).
  • the materials tested were ethylene diamine, available from Union Carbide; diethylenetriamine, obtained from Fisher; triethylenetetramine, obtained from Aldrich; tetraethylenepentamine, obtained from Aldrich; poly (ethylenimine), also obtained from Aldrich, and ethylamine, obtained from Pennwalt.
  • the results of a series of tests are reported below in Table 1, wherein a different test number indicates that tests were conducted on a different day.
  • the % 0 2 reported is the oxygen content of the combustion gas on a volume basis.
  • the additive feedrates are reported as mole(s) of feed per barrel of fuel oil consumed (mole/bb1), and the probe corrosion results are reported as % reduction in iron content of the probe washings for the indicated temperatures as compared to base condition corrosion.
  • Figure 1 are reported the results of tests comparing diethylenetriamine and triethylenetetramine to base conditions. As can be seen from the figure, the results are graphically reported as a plot of concentration of iron in the probe washings, in ppm, against the sampling temperature in °F. The results for base conditions are represented by circles, the results for diethylenetriamine are represented by squares, and the results for triethylenetetramine are represented by triangles.
  • the boiler was operated at approximately 14,000 pounds of steam per hour with oxygen being 6% of the flue gas. The additives were both fed at a rate of 0.33 mole per barrel of oil consumed (0.33 m/bb1).
  • Figure 2 are reported the results of tests comparing ethylene diamine and poly(ethylenimine) to base conditions.
  • the poly(ethylenimine) has a molecular weight average of about 50,000 to 100,000 such that n in Formula I above would be about 1000 to 2500.
  • the results are graphically reported as a plot of concentration of iron in the probe washings, in ppm, against the sampling temperature °F.
  • the results for base conditions are represented by solid circles
  • the results for ethylene diamine are represented by solid squares
  • the results for poly(ethylenimine) are represented by solid triangles.
  • the boiler was operated at approximately 12,000-13,000 pounds of steam per hour with oxygen being about 6% of the flue gas.
  • the ethylene diamine was fed at a rate of 0038 mole/bb1 of fuel' oil consumed, and the poly(ethylenimine) was fed at a rate of 36.3 milliliters per barrel of oil consumed. Due to the uncertainty of the exact molecular weight of the poly(ethylenimine), no exact molar feedrate was calculable. However, based on the noted molecular weight range for the material and a density of approximately 1 gram per milliliter, the feedrate was about .0004 to .0007 mole/bbl.
  • the various additives tested were sprayed, using a standard atomizing spray nozzle arrangement, into the combustion gases at a point of turbulence located upstream of the air-cooled probe.
  • the boiler was fired with number 6 grade fuel oil containing 1% sulfur (by weight).
  • the oil was preheated to 170°F and atomized with steam. Combustion air was at ambient temperature. Flue gas temperatures at the sampling paint ranged from 440°F to 480°F.
  • the sulfuric acid dew point using either a Land Dew Point meter or a corrosion probe was typically 262°F.
  • the 'concentration of SO 3 was determined to be about 7 parts per million parts of combustion gas (ppm, on volume basis).
  • the oxygen content of the flue gas was kept at about 6%.
  • the materials tested were monoethanolamine, obtained from Fisher; 2-(ethylamino)ethanol, obtained from Fisher; 3-amino-1-propanol, obtained from Eastman; 2-amino-2-methyl-1 propanol, obtained from IMC; 2-dibutyl-aminoethanol, obtained from Eastman; 2-amino-2-ethyl-1,3-propanediol, obtained from Aldrich; 1-amino-2-propanol, obtained from Eastman; triethanolamine, obtained from Eastman; and diisopropanolamine, obtained from Dow.
  • the additive feedrates are reported as mole(a) of additive per barrel of oil consumed (m/bb1), and the . probe corrosion results are reported as % reduction in iron content of the probe washings for the indicated temperatures as compared to base condition corrosion. Negative results indicate a condition of increased corrosion of the probe as compared to base conditions.
  • the steam loads are reported as pounds per hour (pph).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Solid Fuels And Fuel-Associated Substances (AREA)
EP19790302132 1978-10-13 1979-10-08 Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen Expired EP0010390B1 (de)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US05/950,960 US4185071A (en) 1978-10-13 1978-10-13 Ethylene polyamines as cold-end additives
US950960 1978-10-13
US1968679A 1979-03-12 1979-03-12
US19687 1979-03-12
US19686 1979-03-12
US06/019,687 US4206172A (en) 1978-10-13 1979-03-12 Alkanolamines and ethylene polyamines as cold-end additives

Publications (2)

Publication Number Publication Date
EP0010390A1 true EP0010390A1 (de) 1980-04-30
EP0010390B1 EP0010390B1 (de) 1982-09-29

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EP19790302132 Expired EP0010390B1 (de) 1978-10-13 1979-10-08 Verfahren und Mittel zum Vermindern der Korrosion auf kalten Stellen

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EP (1) EP0010390B1 (de)
CA (1) CA1113236A (de)
DE (1) DE2963783D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103614727A (zh) * 2013-11-28 2014-03-05 阜阳安固锅炉压力容器制造有限公司 一种水基金属表面防锈液及其制备方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2053024A (en) * 1934-02-16 1936-09-01 Western Chemical Company Compound and method for conditioning boiler, steam and condensate systems
US2750339A (en) * 1953-04-03 1956-06-12 Exxon Research Engineering Co Method for inhibiting corrosion
US2972681A (en) * 1956-08-10 1961-02-21 Westinghouse Electric Corp Cinefluorographic apparatus
GB897709A (en) * 1960-03-23 1962-05-30 British Petroleum Co Improved method for the prevention of furnace corrosion
US3406042A (en) * 1965-12-14 1968-10-15 Cons Edison Co New York Inc Process for corrosion control
GB1338908A (en) * 1969-12-08 1973-11-28 Kurita Water Ind Ltd Method of preventing corrosion in distillation apparatus substituent
US4134727A (en) * 1976-08-12 1979-01-16 Betz Laboratories, Inc. Aqueous solution of sodium metasilicate and N-aminoethyl ethanolamine as a cold-end additive

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2053024A (en) * 1934-02-16 1936-09-01 Western Chemical Company Compound and method for conditioning boiler, steam and condensate systems
US2750339A (en) * 1953-04-03 1956-06-12 Exxon Research Engineering Co Method for inhibiting corrosion
US2972681A (en) * 1956-08-10 1961-02-21 Westinghouse Electric Corp Cinefluorographic apparatus
GB897709A (en) * 1960-03-23 1962-05-30 British Petroleum Co Improved method for the prevention of furnace corrosion
US3406042A (en) * 1965-12-14 1968-10-15 Cons Edison Co New York Inc Process for corrosion control
GB1338908A (en) * 1969-12-08 1973-11-28 Kurita Water Ind Ltd Method of preventing corrosion in distillation apparatus substituent
US4134727A (en) * 1976-08-12 1979-01-16 Betz Laboratories, Inc. Aqueous solution of sodium metasilicate and N-aminoethyl ethanolamine as a cold-end additive

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103614727A (zh) * 2013-11-28 2014-03-05 阜阳安固锅炉压力容器制造有限公司 一种水基金属表面防锈液及其制备方法
CN103614727B (zh) * 2013-11-28 2015-12-09 阜阳安固锅炉压力容器制造有限公司 一种水基金属表面防锈液及其制备方法

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DE2963783D1 (en) 1982-11-11
CA1113236A (en) 1981-12-01
EP0010390B1 (de) 1982-09-29

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