Composition Useful in Sulfate Scale Removal
The present invention discloses a novel aqueous composition for use in removing mixed sulfate scale from a surface contaminated with such, said composition comprising: a chelating agent and a counterion component selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA; a dissolution enhancer; optionally a compound such as sodium gluconate or the like and a carboxyl-containing fructan such as carboxymethyl inulin. There is also disclosed methods to use such compositions.
1 . A method of removing mixed sulfate scale, said method comprising:
providing a liquid composition comprising:
a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA;
optionally, a scale removal enhancer;
a carboxyl-containing fructan; and
a compound selected from the group consisting of: sodium gluconate; gluconic acid; glucono-delta-lactone; sodium gluconate; calcium gluconate; potassium gluconate;
exposing a surface contaminated with said mixed sulfate scale to the liquid composition; and
allowing sufficient time of exposure to remove said mixed sulfate scale from the contaminated surface.
2 . The method according to claim 1 , wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate; cesium carbonate; and combinations thereof.
3 . The method according to claim 3 , wherein the carboxyl-containing fructan is carboxymethylinulin (CMI).
4 . An aqueous composition for use in removing mixed sulfate scale from a surface contaminated with such, said composition comprising:
a chelating agent and a counterion component selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA;
optionally, a scale removal enhancer;
carboxyl-containing fructan; and
a compound selected from the group consisting of: sodium gluconate; gluconic acid; glucono-delta-lactone; sodium gluconate; calcium gluconate; potassium gluconate.
5 . The aqueous composition according to claim 4 , wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate and cesium carbonate and combinations thereof.
6 . The aqueous composition according to claim 4 , wherein the scale removal enhancer is present in the composition in an amount ranging from 5 to 20% wt of the weight of the composition.
7 . The aqueous composition according to claim 4 , wherein the scale removal enhancer is present in the composition in an amount ranging from 10 to 15% wt of the weight of the composition.
8 . The aqueous composition according to claim 4 , wherein the scale removal enhancer is present in the composition in an amount of approximately 10 wt % of the weight of the composition.
9 . The aqueous composition according to claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 5 to 40 wt % of the weight of the composition.
10 . The aqueous composition according to claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 10 to 30 wt % of the weight of the composition.
11 . The aqueous composition according to claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 10 to 20 wt % of the weight of the composition.
12 . The aqueous composition according to claim 4 , wherein the pH of the composition ranges from 10 to 11.
13 . The aqueous composition according to claim 4 , wherein the scale removal enhancer is selected from the group consisting of: K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; and K 4 EDTA.
14 . The aqueous composition according to claim 4 , wherein the carboxymethyl inulin is present in the composition in an amount ranging from 0.5 to 15% wt of the weight of the composition.
15 . The aqueous composition according to claim 4 , wherein the sodium gluconate is present in the composition in an amount ranging from 1% to 20% wt of the weight of the composition.
16 . A method of solubilizing barium sulfate into particles of less than 1 micron in size, said method comprising:
providing a surface contaminated with a scale containing barium sulfate;
providing a liquid composition comprising:
a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA;
optionally, a scale removal enhancer;
a carboxyl-containing fructan such as carboxymethyl inulin; and
exposing said surface contaminated with said barium sulfate scale to the liquid composition;
allowing sufficient time of exposure to remove particles of barium sulfate scale from the contaminated surface;
wherein said particles of barium sulfate complexted with the carboxymethyl inulin and have a particle size of less than 1 micron; and
allowing the pH of the solution to drop from a pH ranging from 10 to 11 to a pH ranging from 7 to 8 thereby causing a reprecipitation of the solubilzed barium sulfate to a particle size of less than 1 micron.
17 . The method according to claim 16 , wherein the carboxyl-containing fructan is carboxymethylinulin (CMI).
18 . The method according to claim 16 wherein the composition comprises:
a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA;
optionally, a scale removal enhancer;
carboxymethyl inulin; and
sodium gluconate
19 . The method according to claim 16 wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate and cesium carbonate and combinations thereof.