EP1409756B1 - Steel parts made of austenitic or semi-austenitic steel in a plant for producing sulfuric acid and method for the protection against corrosion - Google Patents

Steel parts made of austenitic or semi-austenitic steel in a plant for producing sulfuric acid and method for the protection against corrosion Download PDF

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Publication number
EP1409756B1
EP1409756B1 EP02743117A EP02743117A EP1409756B1 EP 1409756 B1 EP1409756 B1 EP 1409756B1 EP 02743117 A EP02743117 A EP 02743117A EP 02743117 A EP02743117 A EP 02743117A EP 1409756 B1 EP1409756 B1 EP 1409756B1
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Prior art keywords
sulfuric acid
steel
austenitic
steel part
content
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EP02743117A
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German (de)
French (fr)
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EP1409756A1 (en
Inventor
Karl-Heinz Daum
Wolf-Christopf Rauser
Nikola Anastasijevic
Wolfram Schalk
Stefan Laibach
Herbert Schnaubelt
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Metso Corp
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Outokumpu Oyj
Outokumpu Technology Oyj
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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
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
    • F28F21/08—Constructions of heat-exchange apparatus characterised by the selection of particular materials of metal
    • F28F21/081—Heat exchange elements made from metals or metal alloys
    • F28F21/082—Heat exchange elements made from metals or metal alloys from steel or ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C23F13/00—Inhibiting corrosion of metals by anodic or cathodic protection
    • C23F13/005—Anodic protection
    • 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
    • F28F19/004—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using protective electric currents, voltages, cathodes, anodes, electric short-circuits

Definitions

  • This invention relates to a method for the protection against corrosion of steel parts made of austenitic or semi-austenitic steel during the production of sulfuric acid and to respective steel parts.
  • sulfuric acid is produced by the catalytic conversion of the SO 2 content of gases to obtain SO 3 and - in the case of dry gases - by the subsequent absorption of the SO 3 formed in concentrated sulfuric acid or - in the case of humid gases - by the subsequent condensation of the sulfuric acid formed.
  • the usual technical components such as drier, absorber, heat exchanger etc. get in contact with concentrated sulfuric acid starting at about 93 wt-% and an elevated temperature.
  • This sulfuric acid is extremely aggressive and exerts a fast and strong corrosion on the structural parts to be used. Therefore, the structural parts which get in contact with sulfuric acid must be made of corrosion-resistant materials.
  • the non-metallic materials generally have unfavorable mechanical properties and are difficult to process.
  • the metallic materials have good mechanical properties, but their corrosion resistance is not sufficient, or the materials are very expensive.
  • very thin-walled components are required, which need a high transfer of heat. In these components, the previous corrosion resistance no longer is sufficient.
  • These plants are usually operated with a sulfuric acid concentration ⁇ 93 wt-% to 100 wt-% and a temperature up to 140°C.
  • a known method of corrosion protection is the anodic corrosion protection. In this method, the materials to be protected are coated with a metal oxide layer which prevents the corrosion attack.
  • US 5,028,396 proposes austenitic stainless steels with a relatively high silicon content consisting essentially of 17.5 % Cr, 17.5 % Ni, 4.6 to 5.8 % Si, the balance being Fe.
  • US 5,695,716 discloses austenitic, corrosion resistant chromium, nickel iron alloys including at least 32 wt-% chromium.
  • the ratio is particularly favorable when molybdenum is present in a not too large amount of 0 wt-% to 2.5 wt-%.
  • austenitic or semi-austenitic steel parts with a molybdenum content of 2 wt-% to 2.5 wt-% can be used.
  • What is particularly critical for corrosion are those ranges in which the concentration of sulfuric acid is about 97 wt-% to 99 wt-% or the temperature of sulfuric acid is about 160°C to 230°C.
  • heat exchangers such as e.g. plate-type heat exchangers or shell-and-tube heat exchangers, as well as the entire pipe system.
  • Fig. 1 shows the current density/potential curve of a typical austenitic material containing 16.5 to 18.5 wt-% chromium, 11 to 14 wt-% nickel and 2 to 2.5 wt-% molybdenum.
  • sulfuric acid was used as medium with 98 wt-% at a temperature of 200°C.
  • cathode there was used a steel cathode made of 1.4404.
  • the potential is plotted in millivolt (mV) against a Hg/HgSO 4 reference electrode, and on the ordinate the current density is plotted in milliampere per square centimeter (mA/cm 2 ).
  • mV millivolt
  • mA/cm 2 milliampere per square centimeter
  • reference electrodes such as e.g. a calomel electrode or a cadmium bar.
  • the first part of the diagram in the range from 0 to 600 mV shows a peak which is referred to as active potential.
  • active potential In the range from 600 mV to 1800 mV then follows the saddle of the curve, the so-called passive potential.
  • passive potential The subsequent rise from 1800 mV is referred to as transpassive potential.
  • transpassive potential To achieve a corrosion protection as effective as possible in the anodic corrosion protection, the current density must lie within the range of the passive potential.
  • the values represented here are exemplary, as they are material- and temperature-dependent.
  • Fig. 2 shows the arrangement of the anodic corrosion protection in a shell-and-tube heat exchanger (1) for sulfuric acid.
  • cooling medium is introduced into a first chamber (3) of a shell-and-tube heat exchanger (1). From there, the cooling medium is distributed and flows through individual tubes (4) into a second chamber (5), from which the cooling medium is discharged again.
  • only two tubes (4) are represented here.
  • connection (6) hot sulfuric acid is introduced.
  • the sulfuric acid flows around the tubes (4) filled with cooling medium and is discharged again via the connection (7).
  • the sulfuric acid is cooled.
  • a plurality of metal cathodes (8) are mounted between the tubes (4) in the shell-and-tube heat exchanger.
  • the representation shows a cathode (8) by way of example.
  • the number of cathodes (8) used depends on the size of the heat exchanger and also on the temperature and the concentration of the sulfuric acid.
  • the cathode (8) is made of the material 1.4404 and is in permanent contact with the sulfuric acid.
  • the cathode (8) is connected with the negative pole of a potentiostat (9) by an electric line.
  • the potentiostat (9) is a d.c. voltage source whose positive pole (10) is connected with the parts of the shell-and-tube heat exchanger (1) to be protected via an electric line.
  • a second reference electrode (11) is inserted in the shell-and-tube heat exchanger via a seal and is connected with the potentiostat (9) via an electric line.
  • This reference electrode (11) likewise is permanently surrounded by the sulfuric acid and provides the measurement basis for the potentiostat (9).
  • the potential required for the corrosion protection is determined and adjusted at the potentiostat (9).

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Spark Plugs (AREA)

Abstract

This invention relates to a method for the protection against corrosion of steel parts made of austenitic or semi-austenitic steel during the production of sulfuric acid. To improve the corrosion resistance of the steel parts which are in contact with the sulfuric acid, it is proposed to use austenitic or semi-austenitic steel which has a Cr content of 15 wt-% to 36 wt-% and an Ni content of 9 wt-% to 60 wt-% and in which the ratio of the chemical elements (Cr+Si)/(Ni+Mo) lies in the range from 0.9 to 1.9 or in which the ratio of the chemical elements Cr/(Ni+Mo) lies in the range from 0.8 to 1.5, and to additionally provide this steel part with an anodic corrosion protection.

Description

  • This invention relates to a method for the protection against corrosion of steel parts made of austenitic or semi-austenitic steel during the production of sulfuric acid and to respective steel parts.
  • In general, sulfuric acid is produced by the catalytic conversion of the SO2 content of gases to obtain SO3 and - in the case of dry gases - by the subsequent absorption of the SO3 formed in concentrated sulfuric acid or - in the case of humid gases - by the subsequent condensation of the sulfuric acid formed. The usual technical components such as drier, absorber, heat exchanger etc. get in contact with concentrated sulfuric acid starting at about 93 wt-% and an elevated temperature. This sulfuric acid is extremely aggressive and exerts a fast and strong corrosion on the structural parts to be used. Therefore, the structural parts which get in contact with sulfuric acid must be made of corrosion-resistant materials. Special ferritic steel alloys, cast iron, plastics, ceramics, glass or other materials with a corresponding lining turned out to be particularly corrosion-resistant. For these applications, the non-metallic materials generally have unfavorable mechanical properties and are difficult to process. The metallic materials have good mechanical properties, but their corrosion resistance is not sufficient, or the materials are very expensive. In particular for use in heat exchangers, very thin-walled components are required, which need a high transfer of heat. In these components, the previous corrosion resistance no longer is sufficient. These plants are usually operated with a sulfuric acid concentration ≥ 93 wt-% to 100 wt-% and a temperature up to 140°C. A known method of corrosion protection is the anodic corrosion protection. In this method, the materials to be protected are coated with a metal oxide layer which prevents the corrosion attack.
  • The use of austenitic steels during the production of sulfuric acid is known from EP 0 130 967. The steel grades indicated in this protective right are intended in particular for use in heat exchangers. The materials used here do not satisfy the requirements which must now be fulfilled by corrosion-resistant materials. For the technical plants now in use smaller corrosion rates are required in particular.
  • In order to improve the corrosion resistance, US 5,028,396 proposes austenitic stainless steels with a relatively high silicon content consisting essentially of 17.5 % Cr, 17.5 % Ni, 4.6 to 5.8 % Si, the balance being Fe.
  • Furthermore, US 5,695,716 discloses austenitic, corrosion resistant chromium, nickel iron alloys including at least 32 wt-% chromium.
  • DE 38 30 365 describes the use of ferritic chromium-molybdenum steels which are resistant to sulfuric acid with a concentration from 94 wt-% onwards and with a temperature below the boiling point. These ferritic steels are very expensive and more difficult to process than austenitic steels. The corrosion resistance is not regarded as sufficient either.
  • Proceeding from this prior art, it is the object underlying the invention to improve the protection against corrosion of at least one steel part of a device made of austenitic or semi-austenitic steel during the production of sulfuric acid, in which device the steel part gets in contact with the sulfuric acid.
  • In accordance with the invention, there is provided a method comprising the features of claim 1.
  • Advantageous embodiments of the invention are evident from the dependent claims.
  • Experiments have shown that steel grades with a Cr content of 15 wt-% to 26.2 wt-%, a Ni content of 9 wt-% to 25.2 wt-% and a Si content of 0.75 wt-% at most are particularly resistant to corrosion.
  • In terms of corrosion resistance, especially the elements silicon and chromium from among the chemical alloying elements are known to form a passive layer, whereas the chemical elements nickel and molybdenum weaken the formation of a passive layer,
  • The ratio of the chemical elements (Cr + Si)/(Ni + Mo) in the range from 1.01 to 1.34 turned out to be particularly advantageous.
  • Likewise, for those steel grades which only have a minor content of silicon there was obtained an advantageous ratio of the chemical elements Cr/(Ni + Mo) in the range from 0.8 to 1.1.
  • The ratio is particularly favorable when molybdenum is present in a not too large amount of 0 wt-% to 2.5 wt-%. Depending on the availability of the steel grades to be supplied for the raw materials such as tubes or sheets, austenitic or semi-austenitic steel parts with a molybdenum content of 2 wt-% to 2.5 wt-% can be used.
  • What is particularly critical for corrosion are those ranges in which the concentration of sulfuric acid is about 97 wt-% to 99 wt-% or the temperature of sulfuric acid is about 160°C to 230°C.
  • During the production of sulfuric acid, components particularly susceptible to corrosion are heat exchangers, such as e.g. plate-type heat exchangers or shell-and-tube heat exchangers, as well as the entire pipe system.
  • Embodiments of the process will be explained by way of example with reference to the drawing, in which:
    • Fig. 1
    shows the current density/potential curve of an austenitic material,
    Fig. 2
    is a schematic representation of the anodic protection in a heat exchanger.
  • Fig. 1 shows the current density/potential curve of a typical austenitic material containing 16.5 to 18.5 wt-% chromium, 11 to 14 wt-% nickel and 2 to 2.5 wt-% molybdenum. In this measurement, sulfuric acid was used as medium with 98 wt-% at a temperature of 200°C. As cathode, there was used a steel cathode made of 1.4404. On the abscissa, the potential is plotted in millivolt (mV) against a Hg/HgSO4 reference electrode, and on the ordinate the current density is plotted in milliampere per square centimeter (mA/cm2). There can also be used other reference electrodes, such as e.g. a calomel electrode or a cadmium bar.
  • The first part of the diagram in the range from 0 to 600 mV shows a peak which is referred to as active potential. In the range from 600 mV to 1800 mV then follows the saddle of the curve, the so-called passive potential. The subsequent rise from 1800 mV is referred to as transpassive potential. To achieve a corrosion protection as effective as possible in the anodic corrosion protection, the current density must lie within the range of the passive potential. The values represented here are exemplary, as they are material- and temperature-dependent.
  • Fig. 2 shows the arrangement of the anodic corrosion protection in a shell-and-tube heat exchanger (1) for sulfuric acid. Via a connection (2), cooling medium is introduced into a first chamber (3) of a shell-and-tube heat exchanger (1). From there, the cooling medium is distributed and flows through individual tubes (4) into a second chamber (5), from which the cooling medium is discharged again. By way of example, only two tubes (4) are represented here.
  • Via a further connection (6), hot sulfuric acid is introduced. The sulfuric acid flows around the tubes (4) filled with cooling medium and is discharged again via the connection (7). When flowing around the tube bundles (4), the sulfuric acid is cooled.
  • A plurality of metal cathodes (8) are mounted between the tubes (4) in the shell-and-tube heat exchanger. The representation shows a cathode (8) by way of example. The number of cathodes (8) used depends on the size of the heat exchanger and also on the temperature and the concentration of the sulfuric acid. The cathode (8) is made of the material 1.4404 and is in permanent contact with the sulfuric acid. The cathode (8) is connected with the negative pole of a potentiostat (9) by an electric line. The potentiostat (9) is a d.c. voltage source whose positive pole (10) is connected with the parts of the shell-and-tube heat exchanger (1) to be protected via an electric line.
  • A second reference electrode (11) is inserted in the shell-and-tube heat exchanger via a seal and is connected with the potentiostat (9) via an electric line. This reference electrode (11) likewise is permanently surrounded by the sulfuric acid and provides the measurement basis for the potentiostat (9). By means of the electric voltage between reference electrode (11) and cathode (8), the potential required for the corrosion protection is determined and adjusted at the potentiostat (9).
  • In the subsequent Table, the corrosion behavior of the materials in accordance with the invention is shown at different temperatures and a sulfuric acid concentration of 98 wt-%. The flow rate of the sulfuric acid was 1 m/s. The corrosion behavior was determined by immersion tests. In all cases, the test period was 7 days. The removal rates were determined by measuring the corrosion flow and by conversion to mm/a. The test medium was renewed after each test cycle.
    Temperature [°C] 1.4571 1.4404 1.4465 1.4591
    Corrosion rate mm/a 160 0.02 0.03 0.15 -
    180 0.06 0.04 0.06 0.01
    200 0.04 0.10 0.14 0.11
  • Thus, the corrosion rates are distinctly lower than in the previous prior art.

Claims (14)

  1. A method for the protection against corrosion of at least one steel part of a device which is used in a plant for producing sulfuric acid, and in which the steel part gets in contact with concentrated sulfuric acid, characterized in that at a sulfuric acid concentration of 93 wt-% up to 100 wt-% and a temperature of 140°C up to the boiling point of the sulfuric acid, the steel part is made of austenitic or semi-austenitic steel which has a Cr content of 15 wt-% to 26.2 wt-%, a Ni content of 9 wt-% to 25.2 wt-% and a Si content of up to 0.75 wt-%, and in which the ratio of the chemical elements (Cr + Si)/(Ni + Mo) lies in the range from 0.9 to 1.9 or in which the ratio of the chemical elements Cr/(Ni + Mo) lies in the range from 0.8 to 1.5, and in which the steel part has an anodic corrosion protection, wherein an anode, a cathode and a reference electrode are connected with a potentiostat which supplies an adjustable direct electric current, and wherein the cathode and the reference electrode are in contact with the sulfuric acid and the anode is in contact with the steel part.
  2. The method as claimed in claim 1, characterized in that the ratio of the chemical elements (Cr + Si)/(Ni + Mo) lies in the range from 1.01 to 1,34.
  3. The method as claimed in claim 1, characterized in that the ratio of the chemical elements Cr/(Ni + Mo) lies in the range from 0,8 to 1.1.
  4. The method as claimed in claim 1, characterized in that the steel part is made of austenitic or semi-austenitic steel which has a molybdenum content of 0 wt-% to 2.5 wt-%.
  5. The method as claimed in claim 1, characterized in that the steel part has a molybdenum content of 2 wt-% to 2.5 wt-%.
  6. The method as claimed in claim 1, characterized in that the steel part is made of steel 1.4465.
  7. The method as claimed in claim 1, characterized in that the concentration of the sulfuric acid lies in the range from 97 wt-% to 99 wt-%.
  8. The method as claimed in claim 1, characterized in that the temperature of the sulfuric acid is about 160°C to 230°C.
  9. The method as claimed in claim 1, characterized in that the steel part is used in a heat exchanger.
  10. The method as claimed in claim 1, characterized in that the steel part is used in an acid-conducting pipe.
  11. A heat exchanger (1) used in a plant for producing sulfuric acid and comprising at least one steel part being in contact with concentrated sulfuric acid having a sulfuric acid concentration of 93 wt-% up to 100 wt-% and a temperature of 140°C up to the boiling point of the sulfuric acid,
    wherein the steel part has an anodic corrosion protection, wherein an anode, a cathode (8) and a reference electrode (11) are connected with a potentiostat (9) which supplies an adjustable direct electric current, and wherein the cathode (8) and the reference electrode (11) are in contact with the sulfuric acid and the anode is in contact with the steel part,
    wherein the steel part is made of austenitic or semi-austenitic steel,
    characterized in that the steel has
    a Cr content of 15 wt-% to 26.2 wt-%,
    a Ni content of 9 wt-% to 25.2 wt-% and
    a Si content of up to 0,75 wt-%,
    and in which the ratio of the chemical elements (Cr + Si)/(Ni + Mo) lies in the range from 0.9 to 1.9 or
    in which the ratio of the chemical elements Cr/(Ni + Mo) lies in the range from 0.8 to 1.5.
  12. The heat exchanger as claimed in claim 11, characterized in that the steel part is made of steel 1.4465.
  13. An acid-conducting pipe used in a plant for producing sulfuric acid and comprising at least one steel part being in contact with concentrated sulfuric acid having a sulfuric acid concentration of 93 wt-% up to 100 wt-% and a temperature of 140°C up to the boiling point of the sulfuric acid,
    wherein the steel part has an anodic corrosion protection, wherein an anode, a cathode (8) and a reference electrode (11) are connected with a potentiostat (9) which supplies an adjustable direct electric current, and wherein the cathode (8) and the reference electrode (11) are in contact with the sulfuric acid and the anode is in contact with the steel part,
    wherein the steel part is made of austenitic or semi-austenitic steel,
    characterized in that the steel has
    a Cr content of 15 wt-% to 26.2 wt-%,
    a Ni content of 9 wt-% to 25.2 wt-% and
    a Si content of up to 0.75 wt-%,
    and in which the ratio of the chemical elements (Cr + Si)/(Ni + Mo) lies in the range from 0.9 to 1.9 or
    in which the ratio of the chemical elements Cr/(Ni + Mo) lies in the range from 0.8 to 1.5.
  14. The acid-conducting pipe as claimed in claim 13, characterized in that the steel part is made of steel 1.4465.
EP02743117A 2001-06-08 2002-05-28 Steel parts made of austenitic or semi-austenitic steel in a plant for producing sulfuric acid and method for the protection against corrosion Expired - Lifetime EP1409756B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE10128032 2001-06-08
DE10128032A DE10128032A1 (en) 2001-06-08 2001-06-08 Process for protecting steel part of apparatus against corrosion comprises using anodic protection, in which an anode, cathode and reference electrode are connected together
PCT/EP2002/005842 WO2002101106A1 (en) 2001-06-08 2002-05-28 Method for the protection against corrosion of a steel part made of austenitic or semi-austenitic steel during the production of sulfuric acid

Publications (2)

Publication Number Publication Date
EP1409756A1 EP1409756A1 (en) 2004-04-21
EP1409756B1 true EP1409756B1 (en) 2006-09-20

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EP02743117A Expired - Lifetime EP1409756B1 (en) 2001-06-08 2002-05-28 Steel parts made of austenitic or semi-austenitic steel in a plant for producing sulfuric acid and method for the protection against corrosion

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US (1) US20040238375A1 (en)
EP (1) EP1409756B1 (en)
JP (1) JP2004529274A (en)
KR (1) KR20040023612A (en)
AT (1) ATE340274T1 (en)
DE (2) DE10128032A1 (en)
EA (1) EA006778B1 (en)
ES (1) ES2272733T3 (en)
MX (1) MXPA03011234A (en)
PE (1) PE20030023A1 (en)
WO (1) WO2002101106A1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009051735A2 (en) * 2007-10-18 2009-04-23 Roberts, Wayne High efficiency, corrosion resistant heat exchanger and methods of use thereof
DE102010006541B4 (en) 2010-02-01 2016-03-17 Outotec Oyj Method and apparatus for cooling acid

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU5702880A (en) * 1979-04-02 1980-10-09 Monsanto Company Anodic passivation system and method
CA1199305A (en) * 1982-01-21 1986-01-14 C-I-L Inc. Anodic protection system and method
US5028396A (en) * 1982-06-11 1991-07-02 Chemetics International Company, Ltd. Apparatus formed of high silicon chromium/nickel in steel in the manufacture of sulpheric acid
US4576813A (en) * 1983-07-05 1986-03-18 Monsanto Company Heat recovery from concentrated sulfuric acid
DE4342188C2 (en) * 1993-12-10 1998-06-04 Bayer Ag Austenitic alloys and their uses
DE19807632A1 (en) * 1998-02-23 1999-09-02 Bayer Ag Device for concentrating and purifying sulfuric acid

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US20040238375A1 (en) 2004-12-02
EA200400008A1 (en) 2004-04-29
EA006778B1 (en) 2006-04-28
DE60214859D1 (en) 2006-11-02
DE60214859T2 (en) 2007-04-12
DE10128032A1 (en) 2002-12-12
MXPA03011234A (en) 2004-02-26
ES2272733T3 (en) 2007-05-01
WO2002101106A1 (en) 2002-12-19
JP2004529274A (en) 2004-09-24
ATE340274T1 (en) 2006-10-15
PE20030023A1 (en) 2003-02-03
KR20040023612A (en) 2004-03-18
EP1409756A1 (en) 2004-04-21

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