Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Patent
1995-02-17
1996-06-25
Warden, Jill
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
134 10, 134 2213, 134 2214, 134 2216, 134 2217, 134 2219, 134 41, B08B 308, B08B 900, C23G 102, C23G 108
Patent
active
055296378
ABSTRACT:
Methods and solutions useful for removing iron oxide-containing scale from the interior surfaces of steel. An aqueous cleaning solution containing formic acid and at least one carboxylic acid having at least two carbon atoms wherein the weight ratio of formic acid to higher carboxylic acid is greater than about 4:1 is contacted with the scale in the absence of an oxidizing agent. Preferred carboxylic acids are the mono-, di-, hydroxy-, and polyhydroxy-carboxylic acids having from two to six carbon atoms. More preferrably, the aqueous solution includes about 0.5-10.0 percent-by-weight in total of such acids wherein the weight ratio of formic acid to higher carboxylic acid is from about 4:1 to about 9:1, together with an effective amount of an organic acid corrosion inhibitor and, optionally, a scale dissolution accelerating agent. Preferrably, contact is under a reducing atmosphere, at a temperature in the range of about 150.degree.-200.degree. F. and a pH less than 7. More preferrably, the cleaning solution is circulated through the vessel for a time less than 30 hours. These high ratio formic/carboxylic acid solutions are capable of holding more iron in solution than low ratio solutions, especially in a reducing atmosphere where iron is maintained in the ferrous state.
REFERENCES:
patent: 1892093 (1932-12-01), Battistella
patent: 2084361 (1937-06-01), Vanderbilt
patent: 2423385 (1947-07-01), Hixson et al.
patent: 2462341 (1949-02-01), Tremaine
patent: 2516685 (1950-07-01), Douty
patent: 3003898 (1961-10-01), Reich
patent: 3003899 (1961-10-01), Eberhard et al.
patent: 3072502 (1963-01-01), Alfano
patent: 3171800 (1965-03-01), Rice et al.
patent: 3296143 (1967-01-01), Boiko
patent: 3298931 (1967-01-01), Herbert et al.
patent: 3492238 (1970-01-01), Wohlberg
patent: 3530000 (1970-09-01), Searles
patent: 3915633 (1975-10-01), Ramachandran
patent: 4174290 (1979-11-01), Leveskis
patent: 4595517 (1986-06-01), Abadi
patent: 4637899 (1987-01-01), Kennedy Jr.
patent: 4855069 (1989-08-01), Schuppiser et al.
patent: 5021096 (1991-06-01), Abadi
patent: 5045352 (1991-09-01), Mueller
patent: 5360488 (1994-11-01), Hieatt et al.
McLaughlin, L. G., "Improved Acid Solution for Boilers Removes Oxides Without Precipitate", E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware, Aug. 1963, pp. 52, 54 and 57.
Frenier et al., "Mechanism of Iron Oxide Dissolution--A Review of Recent Literature", Corrosion, vol. 40, No. 12, pp. 663-668, Dec. 1984.
Frenier, Wayne, "The Mechanism of Magnetite Dissolution in Chelant Solutions", Corrosion, vol. 40, No. 4, pp. 176-180, Apr. 1984.
El-Arini Zeinab
Hydrochem Industrial Services, Inc.
Warden Jill
LandOfFree
Formic-carboxylic acid mixtures for removing iron oxide sclae fr does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Formic-carboxylic acid mixtures for removing iron oxide sclae fr, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Formic-carboxylic acid mixtures for removing iron oxide sclae fr will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2186267