Solid Molded Sulfite-Based Oxygen Scavenger Composition and Method of Manufacutre
A thermally stable, solid sulfite-based treatment composition for treating water systems, particularly heated water systems, to reduce corrosion. A treatment composition comprises (1) a sulfite salt that may provide at least 50% weight active sulfite and (2) a second inorganic salt hydrate that may have a melting point of 45° C. or higher. The treatment composition does not physically degrade or experience melting when stored at temperatures of 35° C.-40° C. The treatment composition is made by mixing water and a sulfite salt at an elevated temperature, then adding a second inorganic salt while maintaining the elevated temperature until a homogenous mixture is formed, then pouring the mixture in a mold and allowing it to cure at room temperature. A preferred sulfite salt is sodium metabisulfite. A preferred second inorganic salt is dipotassium phosphate.
1 . A solid sulfite-based composition comprising:
a first inorganic salt; and
a hydrate of a second inorganic salt;
wherein the first inorganic salt is a sulfite; and
wherein the solid sulfite-based composition is thermally stable at temperatures between 35° C.-40° C.
2 . The solid sulfite-based composition according to claim 1 wherein the solid sulfite-based composition comprises at least 50% active sulfite as SO 3 by weight.
3 . The solid sulfite-based composition according to claim 1 wherein the second inorganic salt is a phosphate.
4 . The solid sulfite-based composition according to claim 3 wherein the phosphate is dipotassium phosphate.
5 . The solid sulfite-based composition according to claim 4 wherein the hydrate of the second inorganic salt is dipotassium heptahydrate.
6 . The solid sulfite-based composition according to claim 1 wherein the sulfite is sodium metabisulfite.
7 . The solid sulfite-based composition according to claim 1 wherein the hydrate has a melting point of at least 40° C.
8 . The solid sulfite-based composition according to claim 1 wherein the hydrate has a melting point of at least 48° C.
9 . The solid sulfite-based composition according to claim 1 further comprising a catalyst or a decharacterization additive or both.
10 . The solid sulfite-based composition according to claim 9 wherein the catalyst comprises sodium erythorbate or cobalt sulfate heptahydrate or both; and
wherein the decharacterization additive comprises a lignosulfonate.
11 . The solid sulfite-based composition according to claim 10 wherein the lignosulfonate comprises sodium lignosulfonate.
12 . The solid sulfite-based composition according to claim 1 wherein the solid sulfite-based composition is in a molded form and maintains the molded form at temperatures between 35° C.-40° C. for at least 5 days.
13 . A sulfite-based composition for treating heated water systems to reduce corrosion, the sulfite-based composition comprising the following ingredients:
60 to 80% by weight of a first inorganic salt;
5 to 30% by weight of a second inorganic salt; and
10 to 30% by weight of deionized water;
wherein the first inorganic salt is a sulfite; and
wherein the second inorganic salt is capable of forming a hydrate having a melting point of at least 40° C.
14 . The sulfite-based composition according to claim 13 wherein the sulfite-based composition comprises at least 50% active sulfite (as SO3) by weight.
15 . The sulfite-based composition according to claim 13 wherein the second inorganic salt is dipotassium phosphate and wherein the hydrate has a melting point of at least 48° C.
16 . The sulfite-based composition according to claim 15 wherein the sulfite is sodium metabisulfite.
17 . The sulfite-based composition according to claim 13 further comprising a catalyst or a decharacterization additive or both.
18 . The sulfite-based composition according to claim 17 wherein the catalyst comprises 0 to 3% sodium erythorbate or 0 to 1% cobalt sulfate heptahydrate or both; and
wherein the decharacterization additive comprises 0 to 5% sodium lignosulfonate.
19 . A method of making a solid sulfite-based composition, the method comprising:
heating water to a first temperature range;
adding and mixing a first inorganic salt to the water after heating the water to form a first mixture;
adding and mixing a second inorganic salt to the first mixture to form a second mixture;
pouring the second mixture into a mold;
curing the second mixture in the mold until it is solid;
wherein the first inorganic salt is a sulfite salt; and
wherein the solid sulfite-based composition is thermally stable at temperatures between 35° C.-40° C.
20 . The method according to claim 19 wherein the first temperature range is around 65 to 70° C.
21 . The method according to claim 19 further comprising adding a catalyst or a decharacterization additive or both prior to adding and mixing the sulfite salt.
22 . The method according to claim 21 wherein the catalyst comprises sodium erythorbate or cobalt sulfate heptahydrate or both; and
wherein the decharacterization additive comprises sodium lignosulfonate.
23 . The method according to claim 20 further comprising heating during adding and mixing the first inorganic salt until the first mixture is within the first temperature range.
24 . The method according to claim 23 wherein adding and mixing the second inorganic salt comprises slowly adding the second inorganic salt in a manner in which the second mixture stays within 5° C. of the first temperature range.
25 . The method according to claim 23 wherein adding and mixing the second inorganic salt comprises adding 5 to 30% of the second inorganic salt by weight of the solid sulfite-based composition and mixing until the second mixture is homogenous.
26 . The method according to claim 23 wherein curing the second mixture comprises allowing the second mixture to sit in the mold at a second temperature range for at least 16 hours.
27 . The method according to claim 26 wherein the second temperature range is around 15 to 30° C.
28 . The method according to claim 20 wherein the solid sulfite-based composition comprises around 60 to 80% of the first inorganic salt and around 5 to 30% of the second inorganic salt by weight.
29 . The method according to claim 20 further comprising heating during adding and mixing the first inorganic salt until the first mixture is within the first temperature range;
wherein the first temperature range is around 65 to 70° C.;
wherein adding and mixing the second inorganic salt comprises slowly adding the second inorganic salt in a manner in which the second mixture stays within 5° C. of the first temperature range;
wherein curing the second mixture comprises allowing the second mixture to sit in the mold at a second temperature range for at least 16 hours;
wherein the second temperature range is around 15 to 30° C.;
wherein the solid sulfite-based composition comprises around 60 to 80% of the first inorganic salt and around 5 to 30% of the second inorganic salt by weight;
wherein the first inorganic salt is sodium metabisulfite; and
wherein the second inorganic salt is dipotassium phosphate.
30 . A method of treating a water system comprising:
adding a sulfite-based composition to the water system, the sulfite-based composition comprising (1) first inorganic salt, and (2) a hydrate of a second inorganic salt;
wherein the first inorganic salt is a sulfite;
wherein the sulfite-based composition is in a solid form prior to adding the sulfite-based composition to the water system, wherein the solid form is thermally stable at temperatures between 35° C.-40° C.; and
wherein the water system is a heated water system or boiler system.
31 . The method of claim 30 further comprising dissolving the solid form prior to adding the sulfite-based composition to the water system.
32 . The method of claim 30 wherein the sulfite-based composition provides an active sulfite concentration as SO 3 in the water system of at least 10,000 ppm.
33 . The method of claim 30 wherein the sulfite-based composition comprises at least 50% active sulfite as SO 3 by weight.
34 . The method of claim 30 wherein the second inorganic salt is a phosphate.
35 . The method of claim 34 wherein the phosphate is dipotassium phosphate.
36 . The method of claim 35 wherein the hydrate of the dipotassium phosphate is dipotassium heptahydrate.