US3664885A - Method for protection of evaporator heating elements from corrosion - Google Patents
Method for protection of evaporator heating elements from corrosion Download PDFInfo
- Publication number
- US3664885A US3664885A US35564A US3664885DA US3664885A US 3664885 A US3664885 A US 3664885A US 35564 A US35564 A US 35564A US 3664885D A US3664885D A US 3664885DA US 3664885 A US3664885 A US 3664885A
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- Prior art keywords
- chromium
- steel
- heating elements
- corrosion
- nickel
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- 238000000034 method Methods 0.000 title claims description 17
- 238000010438 heat treatment Methods 0.000 title abstract description 25
- 230000007797 corrosion Effects 0.000 title abstract description 21
- 238000005260 corrosion Methods 0.000 title abstract description 21
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 23
- 239000011651 chromium Substances 0.000 claims abstract description 23
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 15
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 11
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 48
- 239000012670 alkaline solution Substances 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 9
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 8
- XTEGARKTQYYJKE-UHFFFAOYSA-M chlorate Inorganic materials [O-]Cl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-M 0.000 claims description 8
- 238000001704 evaporation Methods 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 239000011780 sodium chloride Substances 0.000 claims description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- -1 chlorate ions Chemical class 0.000 claims description 2
- BZSXEZOLBIJVQK-UHFFFAOYSA-N 2-methylsulfonylbenzoic acid Chemical compound CS(=O)(=O)C1=CC=CC=C1C(O)=O BZSXEZOLBIJVQK-UHFFFAOYSA-N 0.000 abstract description 14
- 229910000831 Steel Inorganic materials 0.000 description 30
- 239000010959 steel Substances 0.000 description 30
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 25
- 229910052759 nickel Inorganic materials 0.000 description 15
- 235000011121 sodium hydroxide Nutrition 0.000 description 14
- 238000004519 manufacturing process Methods 0.000 description 7
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910045601 alloy Inorganic materials 0.000 description 5
- 239000000956 alloy Substances 0.000 description 5
- 239000003112 inhibitor Substances 0.000 description 5
- 229910000975 Carbon steel Inorganic materials 0.000 description 4
- 239000010962 carbon steel Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000003628 erosive effect Effects 0.000 description 4
- 238000002161 passivation Methods 0.000 description 4
- OGSYQYXYGXIQFH-UHFFFAOYSA-N chromium molybdenum nickel Chemical compound [Cr].[Ni].[Mo] OGSYQYXYGXIQFH-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 238000009533 lab test Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- VWDWKYIASSYTQR-UHFFFAOYSA-N sodium nitrate Chemical compound [Na+].[O-][N+]([O-])=O VWDWKYIASSYTQR-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- CZMRCDWAGMRECN-UGDNZRGBSA-N Sucrose Chemical compound O[C@H]1[C@H](O)[C@@H](CO)O[C@@]1(CO)O[C@@H]1[C@H](O)[C@@H](O)[C@H](O)[C@@H](CO)O1 CZMRCDWAGMRECN-UGDNZRGBSA-N 0.000 description 1
- 229930006000 Sucrose Natural products 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 235000013681 dietary sucrose Nutrition 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 235000010344 sodium nitrate Nutrition 0.000 description 1
- 239000004317 sodium nitrate Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229960004793 sucrose Drugs 0.000 description 1
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
- 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
- C23F11/06—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly alkaline liquids
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D1/00—Oxides or hydroxides of sodium, potassium or alkali metals in general
- C01D1/04—Hydroxides
- C01D1/42—Concentration; Dehydration
Definitions
- ABSTRACT The corrosion of heating elements in evaporators for alkaline media is substantially prevented by using chromium steel containing preferably 25-28 percent chromium as the metal for the heating elements in the presence of 0.05 to 1 g/ 1 of sodium chlorate.
- This invention relates to methods for corrosion protection of heating elements in evaporators operating in alkaline media, for example, in evaporators used for the manufacture of caustic soda.
- the aforesaid evaporators are intended for carrying out the processes of concentrating (evaporating) alkaline solutions under elevated temperatures and diverse service conditions, such as natural or forced circulation of alkaline solutions, various pressures of heat carrier (heating steam), ing a significant proportion of solid matter, etc.
- heating elements manufactured from corrosion-resisting materials, e.g.nickel, nickel-base alloys, or high-alloy austenitic steels which contain, apart from chromium, molybdenum and other alloying elements, also an adequately high proportion of nickel, viz. 25-28 percent.
- corrosion-resisting materials e.g.nickel, nickel-base alloys, or high-alloy austenitic steels which contain, apart from chromium, molybdenum and other alloying elements, also an adequately high proportion of nickel, viz. 25-28 percent.
- the aforesaid studies are essentially aimed at minimizing the consumption of nickel for the equipment to be used in large-tonnage manufacturing processes, among which mention may be made of caustic soda production, under temperature conditions which do not necessarily heat-resistant materials.
- a protective film formed as a result of the interaction between chromium steel and a chlorate-containing alkaline solution exhibits high adhesiveness to the base metal and is corrosion protection by the present invention to eliminate the erosion due to the circulation of alkaline pulp containalso noted for its good resistance to erosive effects caused by a rapid stream of hot alkaline medium (stream rate, 4-5 m/sec containing about 20 percent of solid phase, e.g. sodium chloride in the manufacture of caustic soda.
- the aforespecified amount of. the inhibitor should be incorporated into the solution being handled.
- chromium-nickel steel containing 18% Cr and 10% Ni can be used in conjunction with the heating elements, according to the present invention, since the contact between the aforesaid steel and chromium steel (25% Cr) is permissible and a heating element may be assembled by flaring chromium steel tubes in a tube sheet made from chromium-nickel steel.
- chromium steel or carbon steel clad with chromium steel for fabricating tube sheets of heating elements.
- Table l Data listed in Table l pertains to laboratory experiments under static conditions in a 50 percent solution of sodium hydroxide and made it possible to evaluate the behavior of various steel grades and of nickel in an alkaline environment at temperatures that are close to those used for the evaporation of alkaline solution under plant conditions.
- Table 3 summarizes the results of laboratory tests on chromium steel specimens containing 13 and 17% Cr. Corrosion resistance was evaluated at different temperatures in a 30 percent solution of sodium hydroxide containing sodium chlorate.
- EXAMPLE 1 Plant tests were conducted on specimens made from diverse steel grades, viz., chromium-nickel steel containing 18% Cr and Ni; chromium-nickel-molybdenum steel containing 18% Cr, 12% Ni and 3% Mo; and chromium steel containing 17% and 25% Cr, in a medium consisting of 42 percent solution of sodium hydroxide, in which the content of sodium chlorate equals 0.8-1 g/l and the content of sodium chloride equals 20 g/l, the temperature of the heating steam being 120 C.
- test specimens Apart from the corrosive action exerted by the medium, the test specimens undergo erosion caused by a high-speed stream of alkaline pulp V stream 4-5 m/sec) Under the aforespecified conditions, the steel specimens are corroded at the following rate, millimeters per year: 7
- EXAMPLE 2 carbon steel tubes 2 to 3 chromium-nickel and chromium-nickel molybdenum steel tubes 6 to 8 1n the tubes made from chromium steel, continuous service resulted in neither corrosion damage of the tubes nor diminution of the tube wall thickness. At the sites of flaring the tubes in the tube sheets of heating elements there developed no leaks.
- aqueous alkaline solution is an aqueous solution of sodium hydroxide.
- aqueous alkaline solution is an aqueous solution of sodium hydroxide and sodium chloride.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Inorganic Chemistry (AREA)
- Rigid Pipes And Flexible Pipes (AREA)
- Sorption Type Refrigeration Machines (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
The corrosion of heating elements in evaporators for alkaline media is substantially prevented by using chromium steel containing preferably 25-28 percent chromium as the metal for the heating elements in the presence of 0.05 to 1g/1 of sodium chlorate.
Description
United States Patent Orlova et al.
[451 May23,'l972 METHOD FOR PROTECTION OF EVAPORATOR HEATING ELEMENTS FROM CORROSION Frida Abramovna Orlova, Leninsky prospekt, 41, kv. 334, Moscow; Georgy Vasilievich Seleznev, ulitsa Mayakovskogo, 10, kv. 10; Petr Veniaminovich Bonjuk, prospekt 40 let Oktyabrya, 2, kv. 5, both of Dzerzhinsk, all of USSR.
Filed: May 7, 1970 Appl. No.: 35,564
Inventors:
US. Cl ..l48/6.14, 21/2.7, 23/184,
Sakiyama et al., Chemical Abstracts Vol. 682240700 2/5/68 Primary Examiner-Ralph S, Kendall AttameyWaters, Roditi, Schwartz & Nissen [57] ABSTRACT The corrosion of heating elements in evaporators for alkaline media is substantially prevented by using chromium steel containing preferably 25-28 percent chromium as the metal for the heating elements in the presence of 0.05 to 1 g/ 1 of sodium chlorate.
4 Claims, No Drawings METHOD FOR PROTECTION OF EVAPORATOR HEATING ELEMENTS FROM CORROSION This invention relates to methods for corrosion protection of heating elements in evaporators operating in alkaline media, for example, in evaporators used for the manufacture of caustic soda. The aforesaid evaporators are intended for carrying out the processes of concentrating (evaporating) alkaline solutions under elevated temperatures and diverse service conditions, such as natural or forced circulation of alkaline solutions, various pressures of heat carrier (heating steam), ing a significant proportion of solid matter, etc.
During the service life of evaporating plant equipment the principal elements of evaporators, viz., heating tubes, undergo maximum deterioration under the effect of corrosive alkaline media and also suffer from pronounced erosion corrosion, particularly where evaporator operation involves forced circulation of alkaline solutions containing different admixtures.
Diversified methods for corrosion protection of heating elements of evaporators intended for handling alkaline media are known in the art.
For example, use is made of heating elements manufactured from corrosion-resisting materials, e.g.nickel, nickel-base alloys, or high-alloy austenitic steels which contain, apart from chromium, molybdenum and other alloying elements, also an adequately high proportion of nickel, viz. 25-28 percent.
In some instances recourse is had to equipment made from ordinary steel, provided diverse inhibitors, such as sodium nitrate or saccharose, are incorporated into the alkaline corrosive medium.
It is further known to effect anode polarization technique.
The known methods for corrosion protection suffer from the drawback of resorting to heating elements made from nickel, which is a critical metal, or from nickel-base alloy and nickel-bearing steels, the employment of nickel for this purpose being particularly undesirable in view of the constantly growing consumption of nickel for the production of heat-resistant and high-temperature alloys. This situation has prompted world-wide studies directed to the development of steels and alloys containing a lower percentage of nickel and to finding conditions, under which steels containing little or no nickel would exhibit corrosion-resisting properties for specific applications.
The aforesaid studies are essentially aimed at minimizing the consumption of nickel for the equipment to be used in large-tonnage manufacturing processes, among which mention may be made of caustic soda production, under temperature conditions which do not necessarily heat-resistant materials.
The known methods involving the use of corrosion inhibitors are not invariably effective, particularly where the equipment to be protected is made from carbon steel.
The employment of anodic protection in heating elements is likewise inefficient due to the principles on which the design of these elements is based.
It is an object of the aforesaid disadvantages.
It is a further and more specific object of the present invention to provide a method for corrosion protection of heating elements of evaporators handling alkaline media which will made it possible to improve substantially the dependability and service life of heating elements and to make the heating elements from non-critical materials.
According to the invention, the objects have been accomplished by the provision of heating elements made from chromium steels which undergo passivation under the effect of an inhibitor, sodium chlorate, present in a concentration of 005-1 g/l in an alkaline medium at a temperature of 90-450 C.
A protective film formed as a result of the interaction between chromium steel and a chlorate-containing alkaline solution exhibits high adhesiveness to the base metal and is corrosion protection by the present invention to eliminate the erosion due to the circulation of alkaline pulp containalso noted for its good resistance to erosive effects caused by a rapid stream of hot alkaline medium (stream rate, 4-5 m/sec containing about 20 percent of solid phase, e.g. sodium chloride in the manufacture of caustic soda.
No incorporation of the corrosion inhibitor (sodium chlorate) in alkaline solution is required when manufacturing caustic soda, since in this case sodium chlorate is the byproduct of caustic soda manufacture and is present in the alkaline solution in an amount of 0.05-1 g/l which is adequate for chromium steel passivation.
Where no sodium chlorate is present in alkaline solution, the aforespecified amount of. the inhibitor should be incorporated into the solution being handled.
Currently available equipment manufactured from chromium-nickel steel containing 18% Cr and 10% Ni can be used in conjunction with the heating elements, according to the present invention, since the contact between the aforesaid steel and chromium steel (25% Cr) is permissible and a heating element may be assembled by flaring chromium steel tubes in a tube sheet made from chromium-nickel steel.
It is also preferable to use chromium steel or carbon steel clad with chromium steel for fabricating tube sheets of heating elements.
Data listed in Table l pertains to laboratory experiments under static conditions in a 50 percent solution of sodium hydroxide and made it possible to evaluate the behavior of various steel grades and of nickel in an alkaline environment at temperatures that are close to those used for the evaporation of alkaline solution under plant conditions.
it follows from the above data that among the steels tested chromium steel is unique in that it exhibits high corrosion resistance in corrosive alkaline medium throughout the range of test temperatures.
Under the same conditions, carbon and chromium-nickel steels undergo dissolution at a high rate and the presence of an oxidizing component (sodium chlorate) exerts a marked accelerating effect on the rate of corrosion.
Hence, carbon steel and also chromium -nickel steel and chromium-nickel-molybdenum steel at elevated temperatures Table 2 Steel grade Starting Sodium Temp. Specimen specimen chlorate C weight weight, content loss dug. g/l ring test period, 180 hrs, in grams.
Steel containing It is apparent from the data of Table 2 that even at high temperatures the inhibiting action of sodium chlorate is retained, the rate of the specimen corrosion in melted alkali in the presence of sodium chlorate being 20-23 times lower than without sodium chlorate.
With reference to chromium steels containing a lower percentage of chromium 13 and 17% Cr), it is evident that these materials retain an adequate corrosion resistance and undergo passivation in a 30 percent solution of sodium hydroxide containing sodium chlorate.
Table 3 summarizes the results of laboratory tests on chromium steel specimens containing 13 and 17% Cr. Corrosion resistance was evaluated at different temperatures in a 30 percent solution of sodium hydroxide containing sodium chlorate.
Table 3 Steel Content Corrosion rate, mm/year grade of sodium Temperature, C
chlorate,
Steel 0.0 0.6 1.3-1.8 containing 13% Cr 0.35-0.45 0.19 0.77 Steel 0.0 0.24 0.45 0.60 containing 17% Cr 0.35-0.45 0.07 0.08 0.15-0.20 0.68
It is apparent from the data of Table 3 that increasing the degree of alloying the steel with chromium results in broadening the range oftemperatures at which this type ofsteel retains its ability to undergo passivation in a 30 percent solution of sodium hydroxide.
For a better understanding of the present invention, presented hereinbelow are the following examples of plant tests on specimens of diverse metals placed in the tubes of heating elements in evaporators at caustic soda plants. Tests were also conducted on tubes made from appropriate metals and flared in the tube sheets of heating elements in evaporators used for evaporating electrolytic caustic soda from diaphragm cells.
EXAMPLE 1 Plant tests were conducted on specimens made from diverse steel grades, viz., chromium-nickel steel containing 18% Cr and Ni; chromium-nickel-molybdenum steel containing 18% Cr, 12% Ni and 3% Mo; and chromium steel containing 17% and 25% Cr, in a medium consisting of 42 percent solution of sodium hydroxide, in which the content of sodium chlorate equals 0.8-1 g/l and the content of sodium chloride equals 20 g/l, the temperature of the heating steam being 120 C.
Apart from the corrosive action exerted by the medium, the test specimens undergo erosion caused by a high-speed stream of alkaline pulp V stream 4-5 m/sec) Under the aforespecified conditions, the steel specimens are corroded at the following rate, millimeters per year: 7
Steel containing 18% Cr and 10% Ni 2.5 Steel containing 18% Cr,
l2% Ni, and 3% M0 1.8 Steel containing 25% Cr 0.06 Steel containing 17% Cr 1.2
EXAMPLE 2 carbon steel tubes 2 to 3 chromium-nickel and chromium-nickel molybdenum steel tubes 6 to 8 1n the tubes made from chromium steel, continuous service resulted in neither corrosion damage of the tubes nor diminution of the tube wall thickness. At the sites of flaring the tubes in the tube sheets of heating elements there developed no leaks.
The present method is useful not only for corrosion protection of evaporator heating elements, but also for corrosion protection of equipment handling alkaline media under the aforesaid conditions in diverse chemical processes.
What we claim is:
1. In a method of dehydrating an aqueous alkaline solution by evaporating water from said solution at a temperature of to 450 C. while in contact with metal surfaces, the improvement which comprises adding 0.05 to lg/l of sodium chlorate to the alkaline solution and utilizing a metal consisting of chromium steel containing 25 to 28 percent of chromium.
2. In a method of dehydrating an aqueous alkaline solution containing chlorate ions by evaporating water from said solution at a temperature of 90 to 450 C. while in contact with metal surfaces, the improvement which comprises utilizing a metal consisting of chromium steel containing 25 to 28 percent chromium.
3. A method according to claim 1 wherein the aqueous alkaline solution is an aqueous solution of sodium hydroxide.
4. A method according to claim 2 wherein the aqueous alkaline solution is an aqueous solution of sodium hydroxide and sodium chloride.
Claims (3)
- 2. In a method of dehydrating an aqueous alkaline solution containing chlorate ions by evaporating water from said solution at a temperature of 90* to 450* C. while in contact with metal surfaces, the improvement which comprises utilizing a metal consisting of chromium steel containing 25 to 28 percent chromium.
- 3. A method according to claim 1 wherein the aqueous alkaline solution is an aqueous solution of sodium hydroxide.
- 4. A method according to claim 2 wherein the aqueous alkaline solution is an aqueous solution of sodium hydroxide and sodium chloride.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US3556470A | 1970-05-07 | 1970-05-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3664885A true US3664885A (en) | 1972-05-23 |
Family
ID=21883471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US35564A Expired - Lifetime US3664885A (en) | 1970-05-07 | 1970-05-07 | Method for protection of evaporator heating elements from corrosion |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3664885A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6669837B1 (en) | 2002-12-17 | 2003-12-30 | Sunbelt Chlor Alkali Partnership | Alkali metal hydroxide evaporator system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2610105A (en) * | 1951-03-26 | 1952-09-09 | Dow Chemical Co | Process of simultaneously purifying and dehydrating caustic alkali solutions containing chlorates |
| US3325251A (en) * | 1962-12-27 | 1967-06-13 | Diamond Alkali Co | Process for evaporating aqueous caustic solutions |
| US3380806A (en) * | 1965-07-02 | 1968-04-30 | Frontier Chemical Company | Reduction of chlorates in caustic soda |
-
1970
- 1970-05-07 US US35564A patent/US3664885A/en not_active Expired - Lifetime
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2610105A (en) * | 1951-03-26 | 1952-09-09 | Dow Chemical Co | Process of simultaneously purifying and dehydrating caustic alkali solutions containing chlorates |
| US3325251A (en) * | 1962-12-27 | 1967-06-13 | Diamond Alkali Co | Process for evaporating aqueous caustic solutions |
| US3380806A (en) * | 1965-07-02 | 1968-04-30 | Frontier Chemical Company | Reduction of chlorates in caustic soda |
Non-Patent Citations (1)
| Title |
|---|
| Sakiyama et al., Chemical Abstracts Vol. 68:24070c 2/5/68 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6669837B1 (en) | 2002-12-17 | 2003-12-30 | Sunbelt Chlor Alkali Partnership | Alkali metal hydroxide evaporator system |
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