US 4,443,340 AGranted

Control of iron induced fouling in water systems

AssigneeBetz Laboratories, Inc.

InventorsRoger C. May, Frank C. Sessa

Life of this patent

Estimating the term…

Loading patent…

Abstract

A method for inhibiting corrosion and controlling deposition in an iron containing aqueous medium is disclosed. The method is capable of providing for the formation of a protective passive oxide film on the metallic surfaces in contact with the aqueous medium without resulting in unacceptable iron based deposition or fouling. Surprisingly, the method does not call for the addition of an organic-phosphonic acid compound or derivative to the aqueous medium as would be normally expected due to the known iron dispersing characteristics of these type compounds. The invention comprises maintaining the pH level at 5.5 or above, assuring that a certain minimal calcium or other ion level is maintained, and adding to the system an orthophosphate compound, a water soluble acrylic acid/hydroxyalkylacrylate copolymer, and a topping agent selected from the group consisting of effective water soluble aminocarboxylic acids, lignosulfonates, citric acid, and tannic acid, and water soluble salt forms and mixtures thereof.

Claims25

Dependent claims

A method of inhibiting corrosion and controlling deposition in an aqueous medium contained in a cooling water system of the type comprising iron species present in said medium in a deposit forming amount and under deposit forming conditions, said method being capable of providing for the formation of a protective passive oxide film on metallic surfaces in contact with said aqueous medium, said medium being further characterized by the absence of an organo-phosphonic acid compound therein, wherein said method consists essentially of:

(i) assuring that the pH of said aqueous medium is 5.5 or above;
(ii) assuring that the aqueous medium contains a calcium or other appropriate ion concentration selected from the group consisting of zinc, nickel and chromium and mixtures thereof;
and
(iii) adding to said aqueous medium
(a) a water-soluble polymer comprising moieties derived from an acrylic acid or water-soluble salt thereof and moieties of an hydroxylated lower alkyl acrylate, wherein the moieties of the polymer have the following formulas:
##STR1## wherein R is hydrogen or a lower alkyl of from 1 to 3 carbon atoms;
R.sub.1 is OH, OM or NH.sub.2 where M is a water-soluble cation;
R.sub.2 is a lower alkyl of from about 2 to 6 carbon atoms and the mole ratio of x:y is 34:1 to 1:4;
(b) a water-soluble orthophosphate compound;
said polymer, together with the orthophosphate compound, being effective to promote the formation of said metal oxide film with no attendant deposition of said iron, and the amount of (a) and (b) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface, and
(c) from about 0.4 to 450 parts per million parts of said aqueous medium of a topping agent selected from the group consisting of effective water soluble aminocarboxylic acids, lignosulfonates, citric acid, and tannic acid, and water soluble salt forms and mixtures thereof.

8 more elements

(i) assuring that the pH of said aqueous medium is 5.5 or above;
(ii) assuring that the aqueous medium contains a calcium or other appropriate ion concentration selected from the group consisting of zinc, nickel and chromium and mixtures thereof;
and
(iii) adding to said aqueous medium
(a) a water-soluble polymer comprising moieties derived from an acrylic acid or water-soluble salt thereof and moieties of an hydroxylated lower alkyl acrylate, wherein the moieties of the polymer have the following formulas:
##STR2## wherein R is hydrogen or a lower alkyl of from 1 to 3 carbon atoms;
R.sub.1 is OH, OM or NH.sub.2 where M is a water-soluble cation;
R.sub.2 is a lower alkyl of from about 2 to 6 carbon atoms and the mole ratio of x:y is 34:1 to 1:4;
and
(b) a water-soluble orthophosphate compound;
and
(c) a water-soluble polyphosphate compound;
said polymer, together with the orthophosphate compound being effective to promote the formation of said metal oxide film with no attendant deposition of said iron, and
(d) from about 0.4 to 450 parts per million parts of said aqueous medium of a topping agent selected from the group consisting of effective water soluble aminocarboxylic acids, lignosulfonates, citric acid, and tannic acid, and water soluble salt forms and mixtures thereof, the amount of (a), (b) and (c) being added being sufficient to provide a substantially scale-free protective passive oxide film on the metallic surface.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/497,612Filed 24 May 1983 · continuation in part
Priority: 9 Oct 1981
Granted: 17 Apr 1984
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

C02F 5/125
Containing nitrogen: combined with inorganic substances
C02F 5/105
Using organic substances: combined with inorganic substances
C23F 11/08
Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent: in…
C02F
Treatment of water, waste water, sewage, or sludge