Solid Molded Sulfite-Based Oxygen Scavenger Composition and Method of Manufacutre

Abstract

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.

We claim: 
     
         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.