CA2134908A1 - Closed cooling system corrosion inhibitors - Google Patents
Closed cooling system corrosion inhibitorsInfo
- Publication number
- CA2134908A1 CA2134908A1 CA 2134908 CA2134908A CA2134908A1 CA 2134908 A1 CA2134908 A1 CA 2134908A1 CA 2134908 CA2134908 CA 2134908 CA 2134908 A CA2134908 A CA 2134908A CA 2134908 A1 CA2134908 A1 CA 2134908A1
- Authority
- CA
- Canada
- Prior art keywords
- ppm
- cooling system
- coolant fluid
- corrosion
- closed cooling
- 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.)
- Abandoned
Links
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
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
-
- 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
- C23F11/08—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids
- C23F11/10—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids using organic inhibitors
- C23F11/12—Oxygen-containing compounds
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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)
Abstract
Abstract of the Invention Novel closed cooling system corrosion preventatives are disclosed. The ingredients include sorbitol, an alkali metal gluconate, and borax. Optionally, yellow metal corrosion inhibitors such as tolyltriazole may be incorporated into the formulation. The mixture is particulary effective in high heat flux and low conductivity closed cooling systems.
Description
-~` 2134908 .. .. .....
- BACKGROI)ND QF THE; INVENll`ION
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Introduction~
Closed recirculating water systems are used for a variety of heating a~d cooling systerns. These systems range from those used i~ automobile and truck ., ~...........
S cooling systerns, heating and cooling of buildings, the cooling of molten steel in continuous casting ur~its, the cooling of industrial process equipment, and manyother applications. In all of these systems, the prevention of scaling and the rn~nirnization of corrosion of metal parts in contact with the heating or cooling liquid are of paramount irnportance. While the liquids used in the heating or ' i~
cooling systems are primar Iy aqueous, t ese ~uids may conta i certain : -instances high levels of anti-freeze compounds such as ethylene glycol. In other ~-instances, the cooling systerns may be required to be relatively pure aqueous fluids such as in high heat ~lux, or low conductivity systerns which are employed in the steel industry.
Many corrosion and scale inhibitors have been used in the past. Many of the most successful materials have contained nitrites, molybdates, chromates, soluble oils, amines or phosphates. Each of these components have some environmental or safety consideration involving their use. For exarnple, nitrites ;~
are suspected carcinogens, molybdates and chromates are heavy metals, amines are reactive, and phosphates provide a nutrient source for algae when discharged. -~
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- BACKGROI)ND QF THE; INVENll`ION
:, . , ,"~
Introduction~
Closed recirculating water systems are used for a variety of heating a~d cooling systerns. These systems range from those used i~ automobile and truck ., ~...........
S cooling systerns, heating and cooling of buildings, the cooling of molten steel in continuous casting ur~its, the cooling of industrial process equipment, and manyother applications. In all of these systems, the prevention of scaling and the rn~nirnization of corrosion of metal parts in contact with the heating or cooling liquid are of paramount irnportance. While the liquids used in the heating or ' i~
cooling systems are primar Iy aqueous, t ese ~uids may conta i certain : -instances high levels of anti-freeze compounds such as ethylene glycol. In other ~-instances, the cooling systerns may be required to be relatively pure aqueous fluids such as in high heat ~lux, or low conductivity systerns which are employed in the steel industry.
Many corrosion and scale inhibitors have been used in the past. Many of the most successful materials have contained nitrites, molybdates, chromates, soluble oils, amines or phosphates. Each of these components have some environmental or safety consideration involving their use. For exarnple, nitrites ;~
are suspected carcinogens, molybdates and chromates are heavy metals, amines are reactive, and phosphates provide a nutrient source for algae when discharged. -~
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In addition, many of these additives, and other additives of the prior art do not exhibit properties which modem systerns now require. While prior art references ~ -teach the seperate use of gluconate and sorbitol in coolant systems, there is no ~: -. - . . . - . - , disclosure of utilizing these ingredients in combination with each other.
In my copending application serial 08/079,702 filed June 17, 1992, the disclosure of which is hereinafter incorporated by reference, I have disclosed the ~ ~
use of certain sorbitol,and gluconate mixtures which may op~ionally contain ; A' borates as effective corrosion and scale inhibitors for brine based refrigeration ~ -systems. Surprisingly, wben the additives of my earlier filed applicationwere ;
tested as corrosion and scale inhibitors for non-brine systems, they perforrned well, at lower dosages than those required in my earlier filed application. ~ -.. , .. ~ ;~
.. . ...... ..
Objects of the InYention~
It is an object of this invention to provide to ~he art a practical scale and corrosion inhibitor formulation for use in closed system cooling and heating systems.
It is a further object of this invention to provide to the art an effective scale and corrosion control formulation for use in dosed cooling and heating ~ -systerns where ni$rites, phosphonates, phosphates, metal inhibitors and soluble oils most be avoided.
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In addition, many of these additives, and other additives of the prior art do not exhibit properties which modem systerns now require. While prior art references ~ -teach the seperate use of gluconate and sorbitol in coolant systems, there is no ~: -. - . . . - . - , disclosure of utilizing these ingredients in combination with each other.
In my copending application serial 08/079,702 filed June 17, 1992, the disclosure of which is hereinafter incorporated by reference, I have disclosed the ~ ~
use of certain sorbitol,and gluconate mixtures which may op~ionally contain ; A' borates as effective corrosion and scale inhibitors for brine based refrigeration ~ -systems. Surprisingly, wben the additives of my earlier filed applicationwere ;
tested as corrosion and scale inhibitors for non-brine systems, they perforrned well, at lower dosages than those required in my earlier filed application. ~ -.. , .. ~ ;~
.. . ...... ..
Objects of the InYention~
It is an object of this invention to provide to ~he art a practical scale and corrosion inhibitor formulation for use in closed system cooling and heating systems.
It is a further object of this invention to provide to the art an effective scale and corrosion control formulation for use in dosed cooling and heating ~ -systerns where ni$rites, phosphonates, phosphates, metal inhibitors and soluble oils most be avoided.
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It is still a further object of this invention to - -`
provide to the art a scale and corrosion control formulation that ~-~
would perform in normal closed system cooling systems, but which would also offer protection to mild steel in contact with closed cooling system liquids in high heat flux and low conductivity ~;
systems. It is an additional object of this i.nvention to provide - ' a closed cooling system corrosion and scale inhibitor that would be satisfactory for use in critical systems including high heat flux and low conductivity systems. Further objects will appear `~
hereina~ter.
According to one aspect of the present invention there is provided a method for the prevention of corrosion on the metal -~
surfaces in contact with a coolant fluid in a closed cooling system which comprises maintaining in the coolant fluid from 5 ppm to 4000 ppm of sorbitol and from 5 ppm to 4000 ppm of an alkali metal gluconate. ` ~' `
According to a further aspect of the present invention there is provided a method for the prevention of corrosion on metal surfaces in contact with an aqueous coolant fluid in a ~-closed cooling system which comprises maintaining in the coolant fluid from 40 ppm to 2000 ppm of an alkali metal gluconate, from 40 ppm to 2000 ppm of sorbitol and from 5 ppm to 200 ppm of borax.
According to another aspect of the present invention `~;
there is provided a method for the prevention of corrosion on ~ -metal surfaces in contact with an aqueous coolant fluid present in a closed cooling system which comprises maintaining in the aqueous coolant fluid from 40 ppm to 2000 ppm of an alkali metal .~. . ..
2 1 3 ~ 9 0 8 ~ - . . , gluconate, from 40 ppm to 2000 ppm sorbitol, from 5 ppm to 200 ppm of borax (as sodium tetraborate pentahydrate, and maintaining such coolant fluid at a pH of 7.5 to 9.5.
According to a still further aspect of the present `' invention there is provided a composition for controlling scale and corrosion on the surfaces of metal in contact with aqueous coolant fluids in closed cooling systems which comprises adding to such system an effective amount of a composition comprising~
a. to 2-25% sorbitol; ` ~--b. to 2-25% alkali metal gluconate; and, c. to 0-9% borax, `
d. balance water.
The Invention:
The Cooling Systems The closed cooling systems to which the corrosion and scale inhibitors of this invention are applicable are those ~
normally encountered in the heating and cooling systems of large ~ ~
buildings, machinery, metals processing and the like. These ~`
systems differ from open recirculating systems in that they are not exposed to the ambient air, and cooling is not achieved ~-~
through evaporation as in the case of open recirculating systems.
Typical closed cooling systems operate by picking up heat at a ~ b~
heat rich point, and releasing the heat at a heat deficient point, , ~
generally a heat exchanger. While the term cooling system is used herein, the invention is equally applicable to closed hot water heating systems such as those found in large buildings, and the term cooling system is meant to encompass heating systems as well.
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2 1 3 ~ 9 ~ 8 As stated before, this invention finds particular utility in the treatment of high heat flux cooling systerns. These systerns are often designed to handle high temperature gradients and are often prone to scaling due to the great amount of ' - . -heat being dissipated into the cooling system at any one time. rnong the v~ous S types of systems of this type that the corrosion and scale inhibitor of this invention find utility are those in: blast furnace tuyeres, electromagnetic stirrers, moldcoolants, electric arc furnace coolillg roofs, blast furnace hearth staves, electrode cooling, and basic oxygen furnace hood cooling systems.
Likewise, the corrosion and scale inhibitors of this invention are also find utility in low conductivity water systems which without treatment are highly ~ ;
corrosive to mild steel as naturally occurring waters but do not accomodate conventional inhibitors because their conductivity contributions are too significant.
Systems of this type include but are not limited to: hot water boiler coolant systerns, chilled water systems, air compressors, heating and ventilating equipment systerns ~comfort systems), thermal storage, and ice systems and other systems where the presence of foreign materials in the event of leakage could cause severe contanunation or scaling problerns.
The coolant fluid in the closed system is generally pumped ftom point to point, although gravity may be used to move the fluid from an upper point to a lower point without the use of supplementary mechanical pumps. Coolant fluids are generally aqueous, and depending upon their ultimate use, may be simple well - 5 ~
' ~,,- ;`' ' 2 1 3 ~ 9 0 8 water containing high levels of dissolved hardness ions (ICalcium and Magnesium), ;
treated municipal drinking water, or ion-exchanged, low conductivity water. The fluids may on occasion be wintenzed in those locations requiring such treatment through the use of ethylene glycol or methanol anti-freeze additives. It is - - -S desirable in certain instances to use aqueous coolant 1uids having low levels of alkali or alkaline earth metals contained therein. In these cases, ie may be desirable to use a distilled or deior~ized water as the basis for the aquous coolant fluid.
Typical coolants to which this invention finds applicability are water based -and contain frorn 0.1-1000 ppm of bardness expressed as Ca(C03). Preferably, the coolants to which this invention finds apphcability are water based and contain from 1.0-750 ppm of hardness expressed as Ca(C03). Most preferably, the coolants to which this invention finds applicability are water containing aslittle as 0.5-SOO ppm of hardness expressed as Ca(C03).
The metals used in closed cooling systems are generally categorized as mild steel or galvanized steel, although special steel alloys may be used in certain high heat flux or low conductivity applications. Occasionally, so called yellow metals, copper, and brass may be present in the system and the selection of corrosion and ~ --scale inhibitors must be weighed with these metals in mind. Typically, most - ~
coolant systems which are the intended beneficiaries of the corrosion and scale ~ -protection agents of this invention are made of mi~tures of various steel alloys - 6~
`~''`' including rnild steel. When used with yellow rnetals, it ;s optional to add from 1 100ppm of known copper corrosion inhibitors such as tolyltriazole, benzotriazoleand mercaptobenzothiazole.
Typical}y, the pH values of the aqueous coolant tluids contained in the S closed cooling systems of this invention are maintained in the range of 6.5 to 11.5 ~ ~ -and preferably from 7.5 to 9.S.
The Corrosion and Scale Inhibitors o~ this In~ention The corrosion and scale inhibitor of this invention is a blend of sorbitol and alkali metal gluconate. Optionally, alkali metal borate may be added. If yellow metals are present in the system, typical copper corrosion inhibitors such as ~ `
tolyltriæole may also be added.
Generally, the corrosion and scale inhibitors of this invendon are added in enough quantity to provide from S ppm to 4000 ppm of gluconate and from 5 ppm to 4000 ppm of sorbitol in the coolant contained in the system. Preferably, from 40 ppm to 2000 ppm of gluconate is present and most preferably from 80 ppm to 200 ppm of gluconate is added. Preferably, from 40 ppm to 2~0 ppm of sorbitol is present in the coolant liquid. Most preferably, from 80 ppm to 200 i ~ --ppm of sorbitol is added to the coolant liquid. Optionally, from 0 to 700 ppm ofborate as sodium tetraborate pentahydrate may be added to the system and - 7 - ~ ~ `
2 i 3 ~ 9 ~ 8 preferably from 5 ppm to 200 ppm of borate is added. In the most preferred embodiment of this invention, from 10 ppm to 60 ppm of borate as sodium tetraborate is added to the coolant liquid.
While the dosages to the coolant fluids given above are typical, they may vary depending upon the hardness present in the coolant. Dosages of active ~;
ingredients are typically lowered in the case of low cond~ctivity systerns containing little hardness, and increased for coolants containing hardness causing constituents.
. :. ~ .-While the dosages listed above are expressed as an arnount to be added to the closed cooling system to which they are added, typical formulations may be manufactured which contain the corrosion and scale inhibitor ingredients of thisinvention so that the mixture may be preformulated and fed into the coolant ~ -system. Since all of the components of this invention are water soluble, they may be readily mixed together to forrn suitable inhibitor packages. A typical formulation for use in this invention may broadly comprise in percentages by weight~
Water 95-10 ;
Sodium Gluconate 2-25 Sorbitol 2-25 Sodium Tetraborate 0-9 '' ':
213~908 ........
More preferably a formulation for use in this invention tYill comprise~
Water 9~15 Sodium Gluconate 3-20 Sorbitol 3-20 Sodium Tetraborate 0.5-7 Most preferably a formulation for use in this imention will comprise~
Water 85-25 Sodium Gluconate 5-15 Sorbitol 5-15 Sodium Tetraborate 1-5 A preferred corrosion inhibitory package used for the practice of this ;
invention comprises in percentages by weight:
, ~, . . .
Compound A - -26.5% of 50 wt. % Gluconic Acid 19.0% of 70% wt. % Sorbitol 8.4% 50% NaOH
l~o of 50 wt. ~o Sodium Tolyltriazole 3.13% Sodium Tetraborate 5H2O
balance ------ water .......................................................................................... ........ ... ,'',~,~ :' The gluconate used in this invention is an alkali metal gluconate salt.
Preferably, sodium gluconate is employed although other alkali metal salts of gluconate may be utilized. Sodium gluconate is available commercially from the American International Chemical Inc as sodium gluconate. Additionally, gluconic acid may also be used in the preparation of the corrosion inhibitors of this invention, although, if the acid form is utilized, it is preferred to neutralize it with ~" "' " . :
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213~90~
an alkali metal hydroxide either prior to addition to the Eormula, or after ehe ~ ~ -other ingredients have been mixed so as to avoid the possibility of having a lowpH in the coolant system that is being treated. ;
The sorbitol utilized as an ingredient in this invention is generally of a technical grade, although food grades may also be employed. A preferred sorbitolfor use in this invention is available from ICI Americas Inc. under the tradename SORBO. The borate material utili~ed in this invention is generally categorized as borax, Na2B407. While the sodium salt is prefelTed, other alkali metal tetraborate ;
salts can be used In the forrnulations of the corrosion and scale inhibitors of this invention, itwill be readily apparent that other ingredients may also be added. Other ingredients which may find utility in the subject invention include anti-foam materials such as silicon oils, hydrophobized silica, and the like. While the `
formulations of this invention when used properly do not promote foaming, process leaks may occur into the coolant system which may necessitate the inclusion of anti-foam type materials. Tracer ~pe materials such as those described in U.S. Patents 5,006,311, 5,132,096, 4,966,711 and 5,200,106 may alsobe included in the formulations. These typically inert tracer type materials maybe added to help monitor or control the amount of active sorbitol, gluconaee and ~ d borate in the coolant system. In the practice of this invention it is preferred to uti}i~e an inert fluorescent indicator described and claimed in U.S. 5,006,311 and 2 1 3 ~ 9 0 8 U. S. 5,132,096 rather than the transition metal tracers clescribed in U.S. 4,966,711 and U. S. 5,200,106 above. In a most preferred application of this inventiorl, an inert fluorescent tracer dye is added to the system in known concentration to the -sorbitol ,gluconate or borax, and is used to rnonitor the dosage of active treatment chemicals in the coolant system through the use of fluorescence spectroscopy.
While the gluconate/sorbitol blends of this invention have been shown to not foster the growth of bacteria, mold, slime or algae in coolant systems, process leaks into the system may necessitate the inclusion of a microbiocide into the .
system. While prior art systems employing nitrite based corrosion inhibitors could not utilize the so called oxidizing biocides, oxidizing biocides may be used in the processes of the instant invention. Typical oxidiz~ng biocides which are compatible with the gluconate/sorbitol blends of this invention include chlorine, calcium hypochlorite, stabilized chlorine, sodium hypochlorite, and mL~tures of sodium bromide with chlorine or hypochlorite. Non-oxidizing biocides rnay also be .
employed in conjunction with the formulations of this invention. Typical ~on- -oxidizing biocides that may find utility in the corrosion and scale control forrnulations of this invention include: 2,2-dibromo-3-nitrilopropionamide, polyoxyethylene (dimethyliminio)ethylene (dirnethylirninio)ethylene; S-chloro-2 methyl~-isothi~701in-3-one; 2-methyl~-isothiazolin-3-one; gluteraldehyde, 21~e Iterbùt'hylazin~, kathon, methylenebisthiocyanate, and the like. The examples of - ~ ~ -biocides given herein are meant to be representative and are rlo~ in way inclusive .~., ~, . - . - , . .
213~08 of the current commercially available oxidizing and non-oxidi~ng biocides which may find utility in the coolant system treatments of this invention.
Other additives that rnay be considered for addition to the coolant formulations of this invention include visible dyes for the purpose of visible leak -. . . ~., 5 detection and coolant source identification. Dyes of this type should be stable at the maximum temperatures to be encountered in the coolant system.
In order to show the efficacy of the corrosion inhibitors of this invention ;~
the following experiments were performed. ~ ~
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Tbe corrosion inhibitors of this invention were evaluated against several :, commonly available commercial closed system cooling inhibitor formulations. The experiments were conducted in the following manner~
A liter of water containing the ingredients to be tested is placed into a one liter container. The container is then placed in a constant temperature bath. The corrosive water is agitated to 1 foot/second using a magnetic stirrer. The constant temperature bath is heated to maintain 110-F inside the container. The corrosion coupons are suspended in the container using an ordinary Teflon tape.
the tape needs to be rolled into a string before it can be inserted into the small hole at one end of the corrosion coupon. The coupon is suspended in the ~ `
corrosion cell by pinching the ends of the rolled Te~on tape against the outside - 12- ~;
-.
~ ~ .
r~ 2 ~ 3 ~ 9 0 8 wall of the corrosion cell with a rubber band. E~ccessive evaporation of the corrosive water is eliminated by covering the top of the corrosion cell with a plastic wrap, Saran brand wrap being prefered.
Coupons were prepared by polishing with sand paper to 600 ~t finish. ;
Each coupon is weighed individually to 0.1 mg and, its dimensions measured by a -caliper to the nearest 0.1mm. The surface areas measured averaged 21.82 cm with a standa~d deviation of + 0.5 cm2. Coupon surface is caluculated by~
Area (cm2) = 2(A)(B)~2(A)(C)~2(B)(C)-2(2~Tr2) where A = length (cm) ~ ~;. .
B = widtb (cm) C = tbickness(cm) ~r = pi = 3.142 r = Radius of the coupon hole Procedure -The test duration is 14 days, and the temperature of the corrosive water as well as the stirring action of the magnetic stirrer are checked daily. At the end of - -each test, the coupon is removed from the cell and cleaned of its corrosion - -products by an abrasive Nylon pad. After rinsing with deionized water, the coupon is dAed and weighed. The corrosion rate is calculated using the following formula~
MPY={[(A')-(B')~ x lQ00 rnils x 1 inch}}/~(C'~(D)~E)}
yr. inch 2.54 crn - 13 ~
.
` . . ``:` "''"'~
r-- 2 1 3 ~ 9 0 8 where A' is the initial weight of the coupo~ in grams B' is the final weight of the coupon in grams C' is the test duration in days measured to the nearest hour D is the density of the coupon (value used is 7.87g/cc) S E is the area of the coupon (cm2) The following Examples reported in Table I were run using the procedure described above. All tests were run in water containing û.24~o CaC12 to simulate a corrosive environment. An additional test, not reported in Lhe table was performed using a commercial forrnulation containing nitrite. The formulation , precipitated in the high hardness water and the test was discontinued. Based on~
the results shown, a rmL~ture of sorbitol and gluconate provided superior corrosion protection to mild steel over a blank containing no corrosion inhibitors or sorbitol by itself. Localized pitting corrosion obtained using gluconate alone was lowered using the sorbitol/gluconate blend. Borax helped to further lower localized pitting corrosion. ;~
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The corrosion inhibitor~ of this invention were evaluated in a pilot high heat ~
recirculating cooling unit. This unit consisted of a 250 gallon tank equipped v.~th a heat exchanger to allow regulation of the temperature in the tank, a bottom outlet leading to an S adjustable recirculating pump. After the pump, water passed through a 240 volt copper clad ~, electrical heater having a high output and back to the top opçniDg of the tank. Sufficient ~ ~ -electrical energy could be added to the heater. Temperature and flow could be monitored at several points. Corraters were installed to measure corrosion rates, and corrosion - -coupons could be added to the system.
Compound A
26.5% - 50 vt. % GIUCOD;C ~c~d l9.0~o of 70~o wt. % Sorbitol 8.4~o 50% NaOH
lYo of 50 wt. % Sodium Tolyltriazole 3.13% Sodium Tetraborate SH2O
balance------water Low Conductivitv A~;plications The first two experiments were performed on low conductivity systems and the conditions ;~
were as follows:
20 Water Deionized water Conductivity < 100 ~Lrnhos Heat Flux 150,000 Btu/hr-ft2 ~Ieater voltage 132 Volts Velocity 5 ~t/sec 25 Flowrate 12 gpm Bulk Water Temperature 135- F
-16- ;
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2 ~ 3 ~ 9 0 ~
Skin Temperature 231 F - of heater Heater Material Mild Steel Corraters Mild Steel, Copper Coupon Mild Steel , ~ ~
S Initially, to the water was added 55 ppm of Compound A, the preferred material as desc~ibed on page 9 of the specification, and stabilized chlorine to provide 5 ppm of total ~ .::
residual chlorine. Upon the initial addition of stabilized chlorine, the conductivity of the water increased by about 30 ,umhos. 55 ppm of Compound A did not not prov~de enough corrosion protection on mild steel when S ppm of total chlorine were maintained in the system. Over a - ~ ;
period of 44 hours, the corrosion rate on rnild steel increased to 4.80 mpy. During this time, the conductivity of the water was 55-70 ~ rnhos. Since the maximum allowed conductivity for the test had not been reached, the dosage of Compound A was increased during the experiment so that the conductivity was 90~ mhos.
~ -. . -The final dosage of Compound A was approximately 300 ppm and total chlorine was ` ~
.: ~
15 3.04 ppm. It was apparent that as the product dosage was increased, rnild steel corrosion decreased over time. Over the next 120 hrs., the corrosion rate on mild steel decreased from .: ~ L'' ~ '"
,:
It is still a further object of this invention to - -`
provide to the art a scale and corrosion control formulation that ~-~
would perform in normal closed system cooling systems, but which would also offer protection to mild steel in contact with closed cooling system liquids in high heat flux and low conductivity ~;
systems. It is an additional object of this i.nvention to provide - ' a closed cooling system corrosion and scale inhibitor that would be satisfactory for use in critical systems including high heat flux and low conductivity systems. Further objects will appear `~
hereina~ter.
According to one aspect of the present invention there is provided a method for the prevention of corrosion on the metal -~
surfaces in contact with a coolant fluid in a closed cooling system which comprises maintaining in the coolant fluid from 5 ppm to 4000 ppm of sorbitol and from 5 ppm to 4000 ppm of an alkali metal gluconate. ` ~' `
According to a further aspect of the present invention there is provided a method for the prevention of corrosion on metal surfaces in contact with an aqueous coolant fluid in a ~-closed cooling system which comprises maintaining in the coolant fluid from 40 ppm to 2000 ppm of an alkali metal gluconate, from 40 ppm to 2000 ppm of sorbitol and from 5 ppm to 200 ppm of borax.
According to another aspect of the present invention `~;
there is provided a method for the prevention of corrosion on ~ -metal surfaces in contact with an aqueous coolant fluid present in a closed cooling system which comprises maintaining in the aqueous coolant fluid from 40 ppm to 2000 ppm of an alkali metal .~. . ..
2 1 3 ~ 9 0 8 ~ - . . , gluconate, from 40 ppm to 2000 ppm sorbitol, from 5 ppm to 200 ppm of borax (as sodium tetraborate pentahydrate, and maintaining such coolant fluid at a pH of 7.5 to 9.5.
According to a still further aspect of the present `' invention there is provided a composition for controlling scale and corrosion on the surfaces of metal in contact with aqueous coolant fluids in closed cooling systems which comprises adding to such system an effective amount of a composition comprising~
a. to 2-25% sorbitol; ` ~--b. to 2-25% alkali metal gluconate; and, c. to 0-9% borax, `
d. balance water.
The Invention:
The Cooling Systems The closed cooling systems to which the corrosion and scale inhibitors of this invention are applicable are those ~
normally encountered in the heating and cooling systems of large ~ ~
buildings, machinery, metals processing and the like. These ~`
systems differ from open recirculating systems in that they are not exposed to the ambient air, and cooling is not achieved ~-~
through evaporation as in the case of open recirculating systems.
Typical closed cooling systems operate by picking up heat at a ~ b~
heat rich point, and releasing the heat at a heat deficient point, , ~
generally a heat exchanger. While the term cooling system is used herein, the invention is equally applicable to closed hot water heating systems such as those found in large buildings, and the term cooling system is meant to encompass heating systems as well.
' ", ' - .. .' 4a . ~ :
2 1 3 ~ 9 ~ 8 As stated before, this invention finds particular utility in the treatment of high heat flux cooling systerns. These systerns are often designed to handle high temperature gradients and are often prone to scaling due to the great amount of ' - . -heat being dissipated into the cooling system at any one time. rnong the v~ous S types of systems of this type that the corrosion and scale inhibitor of this invention find utility are those in: blast furnace tuyeres, electromagnetic stirrers, moldcoolants, electric arc furnace coolillg roofs, blast furnace hearth staves, electrode cooling, and basic oxygen furnace hood cooling systems.
Likewise, the corrosion and scale inhibitors of this invention are also find utility in low conductivity water systems which without treatment are highly ~ ;
corrosive to mild steel as naturally occurring waters but do not accomodate conventional inhibitors because their conductivity contributions are too significant.
Systems of this type include but are not limited to: hot water boiler coolant systerns, chilled water systems, air compressors, heating and ventilating equipment systerns ~comfort systems), thermal storage, and ice systems and other systems where the presence of foreign materials in the event of leakage could cause severe contanunation or scaling problerns.
The coolant fluid in the closed system is generally pumped ftom point to point, although gravity may be used to move the fluid from an upper point to a lower point without the use of supplementary mechanical pumps. Coolant fluids are generally aqueous, and depending upon their ultimate use, may be simple well - 5 ~
' ~,,- ;`' ' 2 1 3 ~ 9 0 8 water containing high levels of dissolved hardness ions (ICalcium and Magnesium), ;
treated municipal drinking water, or ion-exchanged, low conductivity water. The fluids may on occasion be wintenzed in those locations requiring such treatment through the use of ethylene glycol or methanol anti-freeze additives. It is - - -S desirable in certain instances to use aqueous coolant 1uids having low levels of alkali or alkaline earth metals contained therein. In these cases, ie may be desirable to use a distilled or deior~ized water as the basis for the aquous coolant fluid.
Typical coolants to which this invention finds applicability are water based -and contain frorn 0.1-1000 ppm of bardness expressed as Ca(C03). Preferably, the coolants to which this invention finds apphcability are water based and contain from 1.0-750 ppm of hardness expressed as Ca(C03). Most preferably, the coolants to which this invention finds applicability are water containing aslittle as 0.5-SOO ppm of hardness expressed as Ca(C03).
The metals used in closed cooling systems are generally categorized as mild steel or galvanized steel, although special steel alloys may be used in certain high heat flux or low conductivity applications. Occasionally, so called yellow metals, copper, and brass may be present in the system and the selection of corrosion and ~ --scale inhibitors must be weighed with these metals in mind. Typically, most - ~
coolant systems which are the intended beneficiaries of the corrosion and scale ~ -protection agents of this invention are made of mi~tures of various steel alloys - 6~
`~''`' including rnild steel. When used with yellow rnetals, it ;s optional to add from 1 100ppm of known copper corrosion inhibitors such as tolyltriazole, benzotriazoleand mercaptobenzothiazole.
Typical}y, the pH values of the aqueous coolant tluids contained in the S closed cooling systems of this invention are maintained in the range of 6.5 to 11.5 ~ ~ -and preferably from 7.5 to 9.S.
The Corrosion and Scale Inhibitors o~ this In~ention The corrosion and scale inhibitor of this invention is a blend of sorbitol and alkali metal gluconate. Optionally, alkali metal borate may be added. If yellow metals are present in the system, typical copper corrosion inhibitors such as ~ `
tolyltriæole may also be added.
Generally, the corrosion and scale inhibitors of this invendon are added in enough quantity to provide from S ppm to 4000 ppm of gluconate and from 5 ppm to 4000 ppm of sorbitol in the coolant contained in the system. Preferably, from 40 ppm to 2000 ppm of gluconate is present and most preferably from 80 ppm to 200 ppm of gluconate is added. Preferably, from 40 ppm to 2~0 ppm of sorbitol is present in the coolant liquid. Most preferably, from 80 ppm to 200 i ~ --ppm of sorbitol is added to the coolant liquid. Optionally, from 0 to 700 ppm ofborate as sodium tetraborate pentahydrate may be added to the system and - 7 - ~ ~ `
2 i 3 ~ 9 ~ 8 preferably from 5 ppm to 200 ppm of borate is added. In the most preferred embodiment of this invention, from 10 ppm to 60 ppm of borate as sodium tetraborate is added to the coolant liquid.
While the dosages to the coolant fluids given above are typical, they may vary depending upon the hardness present in the coolant. Dosages of active ~;
ingredients are typically lowered in the case of low cond~ctivity systerns containing little hardness, and increased for coolants containing hardness causing constituents.
. :. ~ .-While the dosages listed above are expressed as an arnount to be added to the closed cooling system to which they are added, typical formulations may be manufactured which contain the corrosion and scale inhibitor ingredients of thisinvention so that the mixture may be preformulated and fed into the coolant ~ -system. Since all of the components of this invention are water soluble, they may be readily mixed together to forrn suitable inhibitor packages. A typical formulation for use in this invention may broadly comprise in percentages by weight~
Water 95-10 ;
Sodium Gluconate 2-25 Sorbitol 2-25 Sodium Tetraborate 0-9 '' ':
213~908 ........
More preferably a formulation for use in this invention tYill comprise~
Water 9~15 Sodium Gluconate 3-20 Sorbitol 3-20 Sodium Tetraborate 0.5-7 Most preferably a formulation for use in this imention will comprise~
Water 85-25 Sodium Gluconate 5-15 Sorbitol 5-15 Sodium Tetraborate 1-5 A preferred corrosion inhibitory package used for the practice of this ;
invention comprises in percentages by weight:
, ~, . . .
Compound A - -26.5% of 50 wt. % Gluconic Acid 19.0% of 70% wt. % Sorbitol 8.4% 50% NaOH
l~o of 50 wt. ~o Sodium Tolyltriazole 3.13% Sodium Tetraborate 5H2O
balance ------ water .......................................................................................... ........ ... ,'',~,~ :' The gluconate used in this invention is an alkali metal gluconate salt.
Preferably, sodium gluconate is employed although other alkali metal salts of gluconate may be utilized. Sodium gluconate is available commercially from the American International Chemical Inc as sodium gluconate. Additionally, gluconic acid may also be used in the preparation of the corrosion inhibitors of this invention, although, if the acid form is utilized, it is preferred to neutralize it with ~" "' " . :
.' '-..'.~- ~",.'., -: ~ . , ' .;
213~90~
an alkali metal hydroxide either prior to addition to the Eormula, or after ehe ~ ~ -other ingredients have been mixed so as to avoid the possibility of having a lowpH in the coolant system that is being treated. ;
The sorbitol utilized as an ingredient in this invention is generally of a technical grade, although food grades may also be employed. A preferred sorbitolfor use in this invention is available from ICI Americas Inc. under the tradename SORBO. The borate material utili~ed in this invention is generally categorized as borax, Na2B407. While the sodium salt is prefelTed, other alkali metal tetraborate ;
salts can be used In the forrnulations of the corrosion and scale inhibitors of this invention, itwill be readily apparent that other ingredients may also be added. Other ingredients which may find utility in the subject invention include anti-foam materials such as silicon oils, hydrophobized silica, and the like. While the `
formulations of this invention when used properly do not promote foaming, process leaks may occur into the coolant system which may necessitate the inclusion of anti-foam type materials. Tracer ~pe materials such as those described in U.S. Patents 5,006,311, 5,132,096, 4,966,711 and 5,200,106 may alsobe included in the formulations. These typically inert tracer type materials maybe added to help monitor or control the amount of active sorbitol, gluconaee and ~ d borate in the coolant system. In the practice of this invention it is preferred to uti}i~e an inert fluorescent indicator described and claimed in U.S. 5,006,311 and 2 1 3 ~ 9 0 8 U. S. 5,132,096 rather than the transition metal tracers clescribed in U.S. 4,966,711 and U. S. 5,200,106 above. In a most preferred application of this inventiorl, an inert fluorescent tracer dye is added to the system in known concentration to the -sorbitol ,gluconate or borax, and is used to rnonitor the dosage of active treatment chemicals in the coolant system through the use of fluorescence spectroscopy.
While the gluconate/sorbitol blends of this invention have been shown to not foster the growth of bacteria, mold, slime or algae in coolant systems, process leaks into the system may necessitate the inclusion of a microbiocide into the .
system. While prior art systems employing nitrite based corrosion inhibitors could not utilize the so called oxidizing biocides, oxidizing biocides may be used in the processes of the instant invention. Typical oxidiz~ng biocides which are compatible with the gluconate/sorbitol blends of this invention include chlorine, calcium hypochlorite, stabilized chlorine, sodium hypochlorite, and mL~tures of sodium bromide with chlorine or hypochlorite. Non-oxidizing biocides rnay also be .
employed in conjunction with the formulations of this invention. Typical ~on- -oxidizing biocides that may find utility in the corrosion and scale control forrnulations of this invention include: 2,2-dibromo-3-nitrilopropionamide, polyoxyethylene (dimethyliminio)ethylene (dirnethylirninio)ethylene; S-chloro-2 methyl~-isothi~701in-3-one; 2-methyl~-isothiazolin-3-one; gluteraldehyde, 21~e Iterbùt'hylazin~, kathon, methylenebisthiocyanate, and the like. The examples of - ~ ~ -biocides given herein are meant to be representative and are rlo~ in way inclusive .~., ~, . - . - , . .
213~08 of the current commercially available oxidizing and non-oxidi~ng biocides which may find utility in the coolant system treatments of this invention.
Other additives that rnay be considered for addition to the coolant formulations of this invention include visible dyes for the purpose of visible leak -. . . ~., 5 detection and coolant source identification. Dyes of this type should be stable at the maximum temperatures to be encountered in the coolant system.
In order to show the efficacy of the corrosion inhibitors of this invention ;~
the following experiments were performed. ~ ~
' ~ ,::.
Tbe corrosion inhibitors of this invention were evaluated against several :, commonly available commercial closed system cooling inhibitor formulations. The experiments were conducted in the following manner~
A liter of water containing the ingredients to be tested is placed into a one liter container. The container is then placed in a constant temperature bath. The corrosive water is agitated to 1 foot/second using a magnetic stirrer. The constant temperature bath is heated to maintain 110-F inside the container. The corrosion coupons are suspended in the container using an ordinary Teflon tape.
the tape needs to be rolled into a string before it can be inserted into the small hole at one end of the corrosion coupon. The coupon is suspended in the ~ `
corrosion cell by pinching the ends of the rolled Te~on tape against the outside - 12- ~;
-.
~ ~ .
r~ 2 ~ 3 ~ 9 0 8 wall of the corrosion cell with a rubber band. E~ccessive evaporation of the corrosive water is eliminated by covering the top of the corrosion cell with a plastic wrap, Saran brand wrap being prefered.
Coupons were prepared by polishing with sand paper to 600 ~t finish. ;
Each coupon is weighed individually to 0.1 mg and, its dimensions measured by a -caliper to the nearest 0.1mm. The surface areas measured averaged 21.82 cm with a standa~d deviation of + 0.5 cm2. Coupon surface is caluculated by~
Area (cm2) = 2(A)(B)~2(A)(C)~2(B)(C)-2(2~Tr2) where A = length (cm) ~ ~;. .
B = widtb (cm) C = tbickness(cm) ~r = pi = 3.142 r = Radius of the coupon hole Procedure -The test duration is 14 days, and the temperature of the corrosive water as well as the stirring action of the magnetic stirrer are checked daily. At the end of - -each test, the coupon is removed from the cell and cleaned of its corrosion - -products by an abrasive Nylon pad. After rinsing with deionized water, the coupon is dAed and weighed. The corrosion rate is calculated using the following formula~
MPY={[(A')-(B')~ x lQ00 rnils x 1 inch}}/~(C'~(D)~E)}
yr. inch 2.54 crn - 13 ~
.
` . . ``:` "''"'~
r-- 2 1 3 ~ 9 0 8 where A' is the initial weight of the coupo~ in grams B' is the final weight of the coupon in grams C' is the test duration in days measured to the nearest hour D is the density of the coupon (value used is 7.87g/cc) S E is the area of the coupon (cm2) The following Examples reported in Table I were run using the procedure described above. All tests were run in water containing û.24~o CaC12 to simulate a corrosive environment. An additional test, not reported in Lhe table was performed using a commercial forrnulation containing nitrite. The formulation , precipitated in the high hardness water and the test was discontinued. Based on~
the results shown, a rmL~ture of sorbitol and gluconate provided superior corrosion protection to mild steel over a blank containing no corrosion inhibitors or sorbitol by itself. Localized pitting corrosion obtained using gluconate alone was lowered using the sorbitol/gluconate blend. Borax helped to further lower localized pitting corrosion. ;~
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The corrosion inhibitor~ of this invention were evaluated in a pilot high heat ~
recirculating cooling unit. This unit consisted of a 250 gallon tank equipped v.~th a heat exchanger to allow regulation of the temperature in the tank, a bottom outlet leading to an S adjustable recirculating pump. After the pump, water passed through a 240 volt copper clad ~, electrical heater having a high output and back to the top opçniDg of the tank. Sufficient ~ ~ -electrical energy could be added to the heater. Temperature and flow could be monitored at several points. Corraters were installed to measure corrosion rates, and corrosion - -coupons could be added to the system.
Compound A
26.5% - 50 vt. % GIUCOD;C ~c~d l9.0~o of 70~o wt. % Sorbitol 8.4~o 50% NaOH
lYo of 50 wt. % Sodium Tolyltriazole 3.13% Sodium Tetraborate SH2O
balance------water Low Conductivitv A~;plications The first two experiments were performed on low conductivity systems and the conditions ;~
were as follows:
20 Water Deionized water Conductivity < 100 ~Lrnhos Heat Flux 150,000 Btu/hr-ft2 ~Ieater voltage 132 Volts Velocity 5 ~t/sec 25 Flowrate 12 gpm Bulk Water Temperature 135- F
-16- ;
. ~';',`.'.
''``' '`'''-'`',`'''';
2 ~ 3 ~ 9 0 ~
Skin Temperature 231 F - of heater Heater Material Mild Steel Corraters Mild Steel, Copper Coupon Mild Steel , ~ ~
S Initially, to the water was added 55 ppm of Compound A, the preferred material as desc~ibed on page 9 of the specification, and stabilized chlorine to provide 5 ppm of total ~ .::
residual chlorine. Upon the initial addition of stabilized chlorine, the conductivity of the water increased by about 30 ,umhos. 55 ppm of Compound A did not not prov~de enough corrosion protection on mild steel when S ppm of total chlorine were maintained in the system. Over a - ~ ;
period of 44 hours, the corrosion rate on rnild steel increased to 4.80 mpy. During this time, the conductivity of the water was 55-70 ~ rnhos. Since the maximum allowed conductivity for the test had not been reached, the dosage of Compound A was increased during the experiment so that the conductivity was 90~ mhos.
~ -. . -The final dosage of Compound A was approximately 300 ppm and total chlorine was ` ~
.: ~
15 3.04 ppm. It was apparent that as the product dosage was increased, rnild steel corrosion decreased over time. Over the next 120 hrs., the corrosion rate on mild steel decreased from .: ~ L'' ~ '"
4.80 to 1.80 mpy and still appeared to be decreasing over time as the test was ended. Copper corrosion remained at approximately 0.10 mpy. The corrosion rate on the mild steel coupon was determined to be 3.12 mpy, which was approximately the average corrosion rate for rnild 20 steel during the period. The heat transfer surface (rnild steel~ had a yellowish color with some . ~ . - .
raised, brownish spots and the unheated surface had more of the raised deposits, which left pits on the heater material. The deposit on the heated and unheated areas were analy~ed and the . ,~, - 17~
: . .: . -- ::.
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2~3~908 -::
analytical results showed that the material was approximately 99% iron as Fe203 and less than -~
l~o carbonate as CO2. There was less than 1~o dichloromethane extractables.
A second test was run under the same operatin~ conditions with the treatment pro~ram ,slightly different. Initially, 157 ppm of Compound A and 34 ppm of a commerically available S non-oxidizing biocidal product (45~o gluteraldehyde) was added to the system. The conductivity of the water was added to the system. The conductivity of the water was approximately 23 ,~mhos which was all from Compound ~ There was ~o apparent increase in the conductivity of the water upon the addition of the biocide. During the test, an increase in rnild steel corrosion `~-was not observed. After 52 hours, mild steel and copper corrosion rates remained at 0.10 mpy.
10 The corrosiorl rate on the rnild steel coupon was 0.0 mpy. The heat transfer surface felt smooth, had a shiny appearance, and no major discoloration was observed.
The next three tests were performed on a simulated continuous caster cooling system.
Conditions were as follows~
Water (as CaC03) 13 ppm Calcium 6 ppm Magnesiurn 18 ppm Alkalinity 13 ppm Chloride 6 ppm Sulfate .
Heat Flux 300,~Btu/hr-ft2 20 Heater Voltage 187 Volts `
Velocity 21 ft/sec Flowrate 52 gpm Bulk Water Temperature 120 F
Skin Temperature 185- F
25 Heater Material Copper Corraters Mild Steel, Copper Coupon Mild Steel .. . : ~: . ;::..
... -~ .. .- - .
. -.:-~ ...~ .
., ' `" '~' `:, `
-The initial dosage of Compound A was 183 ppm with stabilized chlorine added to provide chlonne present at 5 ppm. During the ~Irst 35 hrs. the product dosage did not provide enough protection against corrosion when maintaining this dosage of chlorine. Mild steel corrosion increased from 0.6 to 1.20 mpy during that period. As a result, dosage of Compound 5 A was increased to 3ao ppm over the next 60 hours. As Compound A was added, corrosion rate on mild steel increased for a short period of time and then continued to again increase.
Copper corrosion remained at .10 mpy for the duration of the test, while mild corrosion was ~ ~;
increasing over time. The copper surface of the heater was smooth and no deposition orf discoloration was observed. The corrosion rate that was obtained on the mild steel coupon was ;
. . .
10 about 20 mpy. `
''-- ; ~`" '1 `"' ' '''`
The next test was run under the same conditions as the previousl however the initial dosage of Compound A was 800 ppm. At this dosage, mild steel corrosion was 0.35 mpy.
Stabilized chlorine to provide 5 ppm of total chlorine was initially added to ~he system in the ~ ~
form of a sodlum salt of sulfanuc acld ~ chlonne contaunmg 7.91ro as avaulable chlonne = ~ ~ -lS stabilized chlorine. However, it was observed that at the dosage of Compound A in the system, a rapid degradation of total chlorine occurred. During the first seventeen hours, total chlorine . ~ :. i decreased to 0.52 ppm. Subsequently, stabilized chlorine to provide about 4.5 ppm total ~ ~ ~
~ ~, chlorine was added to the system. Several hours following the addition of biocide, total ~ ~ -chlorine was measured at 3.42 ppm. Mild steel corrosion remained at about 0.33 mpy for the 20 duration of the test, while copper was rnaintained at 0.07 mpy. The corrosion rate on the mild ;
steel coupon was 0.30 mpy which was in better agreernent with corrater readings. The final -- ~
~, ,-, ...
,. . . :~. ~ . , .
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.... .
:
213~908 total chlorine content was measured at about 0.1 ppm. Corrosion rate on copper and mild steel remained the same. At the end of the test, the copper heater was smooth and no deposition nor discoloration was obselved.
The next test ran under the same operating conditions with the treatment program S slightly varied. Initially, 300 ppm of Compound A and 60 ppm of a 1.5% by weight aqueous solution of 2-methyl4-isothiazolin-3-one was added to the system. The corrosion rate on mild steel using this treatment program was about 0.35 mpy. Throughout the test, the dosage of Compound A was incrementally increased to determine the reduction in mild steel corrosior~
At 450 ppm, Compound A corrosion rate decreased slightly to about 0.30 mpy. At 600 ppm, 1~ the change was minimal, and at 800 ppm, mild steel corrosion decreased to about 0.25 mpy.
With the addition of 53 additional ppm of the biocide, corrosion rates remained the same. I
Copper corrosion remained at 0.05 mpy for the du}ation of the test. The copper heater surface remained smooth and there was no deposition or discoloration on the heat transfer surface.
Corrcsion rate on the rnild steel coupon was 1.41 mpy which did not agree with the corrater ~ - -15 readings due to the short lerlgth of time that the coupon remained in the water.
According to the above results, 300 ppm of Compound A provided satisfactory corrosion ;
protection to mild steel in the presence of S ppm total chlorine. At this level, the conductivity - ~ ~
of water is about 1~ ~urnhos which leaves little room for dosage increase in systems requiring `- ` -low conductivity. With 45 gluteraldehyde as a biocidal treatment, 1~0 ppm of Compound A is 20 recommended. his dosage maintained the conducti ity of water at about 5 ~mhos which allows room for dosage increase if needed.
" '~ ~ '" ' "~'''' - 20 - ` ~
. .~. .~ .-, - .
: ' ' - `
. - .. ,-; -~ 2 1 3 ~ 9 0 8 In the high heat flux test described above, higher levels of t:reatment chemical arerequired when biocide is added. However, the treatment program provided satis~actory results by lowering corrosion rates.
Hav~ng thus described my invention, I claim~
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raised, brownish spots and the unheated surface had more of the raised deposits, which left pits on the heater material. The deposit on the heated and unheated areas were analy~ed and the . ,~, - 17~
: . .: . -- ::.
'' '''"~"" ~' ~ "-:'-':"
2~3~908 -::
analytical results showed that the material was approximately 99% iron as Fe203 and less than -~
l~o carbonate as CO2. There was less than 1~o dichloromethane extractables.
A second test was run under the same operatin~ conditions with the treatment pro~ram ,slightly different. Initially, 157 ppm of Compound A and 34 ppm of a commerically available S non-oxidizing biocidal product (45~o gluteraldehyde) was added to the system. The conductivity of the water was added to the system. The conductivity of the water was approximately 23 ,~mhos which was all from Compound ~ There was ~o apparent increase in the conductivity of the water upon the addition of the biocide. During the test, an increase in rnild steel corrosion `~-was not observed. After 52 hours, mild steel and copper corrosion rates remained at 0.10 mpy.
10 The corrosiorl rate on the rnild steel coupon was 0.0 mpy. The heat transfer surface felt smooth, had a shiny appearance, and no major discoloration was observed.
The next three tests were performed on a simulated continuous caster cooling system.
Conditions were as follows~
Water (as CaC03) 13 ppm Calcium 6 ppm Magnesiurn 18 ppm Alkalinity 13 ppm Chloride 6 ppm Sulfate .
Heat Flux 300,~Btu/hr-ft2 20 Heater Voltage 187 Volts `
Velocity 21 ft/sec Flowrate 52 gpm Bulk Water Temperature 120 F
Skin Temperature 185- F
25 Heater Material Copper Corraters Mild Steel, Copper Coupon Mild Steel .. . : ~: . ;::..
... -~ .. .- - .
. -.:-~ ...~ .
., ' `" '~' `:, `
-The initial dosage of Compound A was 183 ppm with stabilized chlorine added to provide chlonne present at 5 ppm. During the ~Irst 35 hrs. the product dosage did not provide enough protection against corrosion when maintaining this dosage of chlorine. Mild steel corrosion increased from 0.6 to 1.20 mpy during that period. As a result, dosage of Compound 5 A was increased to 3ao ppm over the next 60 hours. As Compound A was added, corrosion rate on mild steel increased for a short period of time and then continued to again increase.
Copper corrosion remained at .10 mpy for the duration of the test, while mild corrosion was ~ ~;
increasing over time. The copper surface of the heater was smooth and no deposition orf discoloration was observed. The corrosion rate that was obtained on the mild steel coupon was ;
. . .
10 about 20 mpy. `
''-- ; ~`" '1 `"' ' '''`
The next test was run under the same conditions as the previousl however the initial dosage of Compound A was 800 ppm. At this dosage, mild steel corrosion was 0.35 mpy.
Stabilized chlorine to provide 5 ppm of total chlorine was initially added to ~he system in the ~ ~
form of a sodlum salt of sulfanuc acld ~ chlonne contaunmg 7.91ro as avaulable chlonne = ~ ~ -lS stabilized chlorine. However, it was observed that at the dosage of Compound A in the system, a rapid degradation of total chlorine occurred. During the first seventeen hours, total chlorine . ~ :. i decreased to 0.52 ppm. Subsequently, stabilized chlorine to provide about 4.5 ppm total ~ ~ ~
~ ~, chlorine was added to the system. Several hours following the addition of biocide, total ~ ~ -chlorine was measured at 3.42 ppm. Mild steel corrosion remained at about 0.33 mpy for the 20 duration of the test, while copper was rnaintained at 0.07 mpy. The corrosion rate on the mild ;
steel coupon was 0.30 mpy which was in better agreernent with corrater readings. The final -- ~
~, ,-, ...
,. . . :~. ~ . , .
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.... .
:
213~908 total chlorine content was measured at about 0.1 ppm. Corrosion rate on copper and mild steel remained the same. At the end of the test, the copper heater was smooth and no deposition nor discoloration was obselved.
The next test ran under the same operating conditions with the treatment program S slightly varied. Initially, 300 ppm of Compound A and 60 ppm of a 1.5% by weight aqueous solution of 2-methyl4-isothiazolin-3-one was added to the system. The corrosion rate on mild steel using this treatment program was about 0.35 mpy. Throughout the test, the dosage of Compound A was incrementally increased to determine the reduction in mild steel corrosior~
At 450 ppm, Compound A corrosion rate decreased slightly to about 0.30 mpy. At 600 ppm, 1~ the change was minimal, and at 800 ppm, mild steel corrosion decreased to about 0.25 mpy.
With the addition of 53 additional ppm of the biocide, corrosion rates remained the same. I
Copper corrosion remained at 0.05 mpy for the du}ation of the test. The copper heater surface remained smooth and there was no deposition or discoloration on the heat transfer surface.
Corrcsion rate on the rnild steel coupon was 1.41 mpy which did not agree with the corrater ~ - -15 readings due to the short lerlgth of time that the coupon remained in the water.
According to the above results, 300 ppm of Compound A provided satisfactory corrosion ;
protection to mild steel in the presence of S ppm total chlorine. At this level, the conductivity - ~ ~
of water is about 1~ ~urnhos which leaves little room for dosage increase in systems requiring `- ` -low conductivity. With 45 gluteraldehyde as a biocidal treatment, 1~0 ppm of Compound A is 20 recommended. his dosage maintained the conducti ity of water at about 5 ~mhos which allows room for dosage increase if needed.
" '~ ~ '" ' "~'''' - 20 - ` ~
. .~. .~ .-, - .
: ' ' - `
. - .. ,-; -~ 2 1 3 ~ 9 0 8 In the high heat flux test described above, higher levels of t:reatment chemical arerequired when biocide is added. However, the treatment program provided satis~actory results by lowering corrosion rates.
Hav~ng thus described my invention, I claim~
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Claims (19)
1. A method for the prevention of corrosion on the metal surfaces in contact with a coolant fluid in a closed cooling system which comprises maintaining in the coolant fluid from 5 ppm to 4000 ppm of sorbitol and from 5 ppm to 4000 ppm of an alkali metal gluconate.
2. The method of claim 1 wherein the coolant fluid is water.
3. The method of claim 1 wherein the closed cooling system is a low conductivity cooling system.
4. The method of claim 1 wherein the closed cooling system is a high heat flux cooling system.
5. The method of claim 1 wherein up to 700 ppm of borax as sodium tetroborate pentahydrate is added to the cooling system.
6. A method for the prevention of corrosion on metal surfaces in contact with an aqueous coolant fluid in a closed cooling system which comprises maintaining in the coolant fluid from 40 ppm to 2000 ppm of an alkali metal gluconate, from 40 ppm to 2000 ppm of sorbitol and from 5 ppm to 200 ppm of borax.
7. The method of claim 6 wherein the closed cooling system is a high heat flux cooling system.
8. The method of claim 6 wherein the closed cooling system is a low conductivity cooling system.
9. The method of claim 6 wherein the coolant fluid contains at least one additional ingredient selected from the group consisting of: inert fluorescent tracers, anti-foam compounds, biocide control agents.
10. The method of claim 6 wherein an effective amount of yellow metal corrosion inhibitor from the group consisting of tolyltriazole, mercaptobenzotriazole, and benzotriazole is added to the closed cooling system.
11. The method of claim 6 wherein the coolant fluid contains from .1 ppm to 1000 ppm of hardness expressed as CaCO3.
12. The method of claim 6 wherein the coolant fluid is maintained at a pH of from 6.5 to 11.5.
13. A method for the prevention of corrosion on metal surfaces in contact with an aqueous coolant fluid present in a closed cooling system which comprises maintaining in the aqueous coolant fluid from 40 ppm to 2000 ppm of an alkali metal gluconate, from 40 ppm to 2000 ppm sorbitol, from 5 ppm to 200 ppm of borax (as sodium tetraborate pentahydrate, and maintaining such coolant fluid at a H of 7.5 to 9.5.
14. The method of claim 13 wherein an inert fluroscent tracer is added to the aqueous, coolant fluid in proportion to the amount of sorbitol present.
15. The method of claim 13 wherein the aqueous coolant fluid is deionized water.
16. The method of claim 13 wherein an effective amount of an oxidizing biocide is added to the coolant fluid to prevent microbiological growth.
17. The method of claim 13 wherein an effective amount of an antifoam agent is added to the coolant fluid to prevent foaming.
18. A composition for controlling scale and corrosion on the surfaces of metal in contact with aqueous coolant fluids in closed cooling systems which comprises adding to such system an effective amount of a composition comprising:
a. to 2-25% sorbitol;
b. to 2-25% alkali metal gluconate; and, c. to 0-9% borax.
d. balance water.
a. to 2-25% sorbitol;
b. to 2-25% alkali metal gluconate; and, c. to 0-9% borax.
d. balance water.
19. A method for the prevention of scale and corrosion on the surfaces of metal in contact with aqueous coolant fluids in closed cooling systems which comprises adding to the aqueous coolant fluid present in such cooling system an effective amount of the composition of claim 18.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US14555693A | 1993-11-04 | 1993-11-04 | |
| US08/145,556 | 1993-11-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2134908A1 true CA2134908A1 (en) | 1995-05-05 |
Family
ID=22513635
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2134908 Abandoned CA2134908A1 (en) | 1993-11-04 | 1994-11-02 | Closed cooling system corrosion inhibitors |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0652305B1 (en) |
| JP (1) | JP3383441B2 (en) |
| BR (1) | BR9404329A (en) |
| CA (1) | CA2134908A1 (en) |
| DE (1) | DE69417685T2 (en) |
Families Citing this family (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1996039549A1 (en) * | 1995-06-05 | 1996-12-12 | Betzdearborn Inc. | Method for inhibiting metal corrosion in large scale water systems |
| LV12958B (en) * | 2001-06-25 | 2003-06-20 | Grjazevs Olegs | Inhibitors of ferrous metal corrosion |
| JP4470121B2 (en) * | 2001-08-28 | 2010-06-02 | 栗田工業株式会社 | Disinfecting and algae killing method of circulating cooling water system |
| WO2003040046A1 (en) * | 2001-11-06 | 2003-05-15 | Buddy Don Gray | Coolant treatment formulation |
| KR100507831B1 (en) * | 2002-03-15 | 2005-08-17 | 삼성코닝 주식회사 | Anti-contamination coating composition and article having coat layer formed using same |
| AU2003248060A1 (en) | 2003-07-11 | 2005-01-28 | Shishiai-Kabushikigaisha | Cooling fluid composition for fuel battery |
| AU2003296103A1 (en) | 2003-10-01 | 2005-04-21 | Shishiai-Kabushikigaisha | Liquid coolant composition |
| WO2005091413A1 (en) | 2004-03-24 | 2005-09-29 | Shishiai-Kabushikigaisha | Cooling fluid composition for fuel cell |
| JP2007255788A (en) * | 2006-03-23 | 2007-10-04 | Aquas Corp | Management method for heat storage cold and hot water system |
| JP4936772B2 (en) * | 2006-04-10 | 2012-05-23 | 三菱電機株式会社 | Water treatment method |
| US7692041B2 (en) | 2006-08-07 | 2010-04-06 | The University Of Montana | Method of oxidation using nitric acid |
| US20090250653A1 (en) | 2006-08-07 | 2009-10-08 | Kiely Donald E | Hydroxycarboxylic Acids and Salts |
| WO2009065143A2 (en) | 2007-11-15 | 2009-05-22 | The University Of Montana | Hydroxypolyamide gel forming agents |
| US8021607B2 (en) | 2008-10-31 | 2011-09-20 | General Electric Company | Methods for inhibiting corrosion in aqueous media |
| US8025840B2 (en) | 2008-10-31 | 2011-09-27 | General Electric Company | Compositions and methods for inhibiting corrosion in aqueous media |
| CN102408880A (en) * | 2010-09-23 | 2012-04-11 | 中国石油化工集团公司 | Glycol aqueous solution coolant |
| US9404188B2 (en) * | 2010-11-11 | 2016-08-02 | Rivertop Renewables | Corrosion inhibiting composition |
| CA2833374A1 (en) | 2011-04-21 | 2012-10-26 | Rivertop Renewables, Inc. | Calcium sequestering composition |
| JP6047781B2 (en) * | 2012-08-28 | 2016-12-21 | 中部キレスト株式会社 | Rust preventive composition, aqueous rust preventive lubricant, and metal material processing method using the same |
| WO2014085262A1 (en) | 2012-11-28 | 2014-06-05 | Rivertop Renewables | Corrosion inhibiting, freezing point lowering compositions |
| US9187398B2 (en) | 2013-03-13 | 2015-11-17 | Rivertop Renewables, Inc. | Nitric acid oxidation processes |
| US9346736B2 (en) | 2013-03-13 | 2016-05-24 | Rivertop Renewables, Inc. | Oxidation process |
| US9670124B2 (en) | 2013-03-13 | 2017-06-06 | Rivertop Renewables, Inc. | Nitric acid oxidation process |
| USD740917S1 (en) | 2013-03-16 | 2015-10-13 | Kohler Co. | Shower faceplate for shower device |
| US9677031B2 (en) | 2014-06-20 | 2017-06-13 | Ecolab Usa Inc. | Catalyzed non-staining high alkaline CIP cleaner |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL257355A (en) * | 1959-11-10 | |||
| US3589859A (en) * | 1967-10-09 | 1971-06-29 | Exxon Research Engineering Co | Gluconate salt inhibitors |
| US4202796A (en) * | 1978-07-31 | 1980-05-13 | Chemed Corporation | Anti-corrosion composition |
| DE3063270D1 (en) * | 1979-05-23 | 1983-07-07 | Ciba Geigy Ag | Process for the continuous production of textile materials by wet bonding and the foamed compositions utilised in carrying out this process |
| JPS5891174A (en) * | 1981-11-21 | 1983-05-31 | Seiwa Kogyo Kk | Rust preventive material for brine of inorganic salt |
| FR2538406B1 (en) * | 1982-12-27 | 1985-09-20 | Bp Chimie Sa | PROCESS FOR TREATING AQUEOUS FLUIDS TO REDUCE CORROSION OF METALS ON CONTACT |
| JPS6136152A (en) * | 1984-07-30 | 1986-02-20 | ミサワホ−ム株式会社 | Antirust composition for iron bar |
| JPH01212781A (en) * | 1988-02-18 | 1989-08-25 | Kurita Water Ind Ltd | Corrosion inhibitor |
| DE69011316T2 (en) * | 1990-04-13 | 1995-02-16 | Denac Nv | Processes for the prevention of deposits and corrosion in water treatment systems. |
| DE69101606T2 (en) * | 1990-08-06 | 1994-07-21 | Basf Corp | Cleaning solutions for cooling systems. |
| US5330683A (en) * | 1992-04-16 | 1994-07-19 | Nalco Chemical Company | Method of inhibiting corrosion in brine solutions |
-
1994
- 1994-11-02 CA CA 2134908 patent/CA2134908A1/en not_active Abandoned
- 1994-11-03 EP EP94117381A patent/EP0652305B1/en not_active Expired - Lifetime
- 1994-11-03 DE DE1994617685 patent/DE69417685T2/en not_active Expired - Fee Related
- 1994-11-03 BR BR9404329A patent/BR9404329A/en not_active IP Right Cessation
- 1994-11-04 JP JP27115994A patent/JP3383441B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07258871A (en) | 1995-10-09 |
| BR9404329A (en) | 1995-07-04 |
| EP0652305A1 (en) | 1995-05-10 |
| EP0652305B1 (en) | 1999-04-07 |
| DE69417685T2 (en) | 1999-09-16 |
| JP3383441B2 (en) | 2003-03-04 |
| DE69417685D1 (en) | 1999-05-12 |
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